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Note: This page contains sample records for the topic "measurement variable convection" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Instantaneous Measurement of Nonlocal Variables Lev Vaidman  

E-Print Network [OSTI]

Instantaneous Measurement of Nonlocal Variables Lev Vaidman 1 School of Physics and Astronomy variables related to two or more separate sites can be measured instantaneously, except for a finite time of the measurement. It is a verification measurement: it yields reliably the eigenvalues of the nonlocal variables

Vaidman, Lev

2

Influence of variable property effects on natural convection flows in asymmetrically-heated vertical channels  

SciTech Connect (OSTI)

The influence of variable property effects on the laminar air flow induced by natural convection in a vertical, asymmetrically-heated channel is investigated. A full-elliptic model that accounts for variations of viscosity and thermal conductivity with temperature and determines the density from the state equation, has been solved numerically for cases for which variable property effects are important, particularly for conditions for which flow reversals may appear. The corresponding numerical results are compared with those obtained from an alternative model in which all thermophysical properties are assumed to be constant and the Boussinesq approximation is used. It has been found that variable property effects have a strong influence, not reported in previous works, on the recirculation patterns, and may produce, for certain ranges of parameters that roughly coincide with those for which flow reversals exist, an increase in the mass flow rate induced in the channel.

Zamora, B. [Univ. de Murcia (Spain)] [Univ. de Murcia (Spain); Hernandez, J. [Ciudad Universitaria, Madrid (Spain)] [Ciudad Universitaria, Madrid (Spain)

1997-12-01T23:59:59.000Z

3

Variable-property effects in laminar aiding and opposing mixed convection of air in vertical tubes  

SciTech Connect (OSTI)

Mixed convection flow in tubes is encountered in many engineering applications, such as solar collectors, nuclear reactors, and compact heat exchangers. Here, a numerical investigation has been conducted in order to determine the effects of variable properties on the flow pattern and heat transfer performances in laminar developing ascending flow with mixed convection for two cases: in case 1 the fluid is heated, and in case 2 it is cooled. Calculations are performed for air at various Grashof numbers with a fixed entrance Reynolds number of 500 using both the Boussinesq approximation (constant-property model) and a variable-property model. In the latter case, the fluid viscosity and thermal conductivity are allowed to vary with absolute temperature according to simple power laws, while the density varies linearly with the temperature, and the heat capacity is assumed to be constant. The comparison between constant- and variable-property models shows a substantial difference in the temperature and velocity fields when the Grashof number {vert_bar}Gr{vert_bar} is increased. The friction factor is seen to be underpredicted by the Boussinesq approximation when the fluid is heated (case 1), while it is overpredicted for the cooling case (case 2). However, the effects on the heat transfer performance remain negligible except for cases with reverse flow. On the whole, the variable-property model predicts flow reversal at lower values of {vert_bar}Gr{vert_bar}, especially for flows with opposing buoyancy forces. The deviation in results is associated to the difference between the fluid bulk and the wall temperature.

Nesreddine, H.; Galanis, N. [Univ. de Sherbrooke, Quebec (Canada). Faculty of Applied Sciences; Nguyen, C.T. [Univ. de Moncton, New Brunswick (Canada). School of Engineering

1997-01-01T23:59:59.000Z

4

AERIAL MEASUREMENTS OF CONVECTION CELL ELEMENTS IN HEATED LAKES  

SciTech Connect (OSTI)

Power plant-heated lakes are characterized by a temperature gradient in the thermal plume originating at the discharge of the power plant and terminating at the water intake. The maximum water temperature discharged by the power plant into the lake depends on the power generated at the facility and environmental regulations on the temperature of the lake. Besides the observed thermal plume, cloud-like thermal cells (convection cell elements) are also observed on the water surface. The size, shape and temperature of the convection cell elements depends on several parameters such as the lake water temperature, wind speed, surfactants and the depth of the thermocline. The Savannah River National Laboratory (SRNL) and Clemson University are collaborating to determine the applicability of laboratory empirical correlations between surface heat flux and thermal convection intensity. Laboratory experiments at Clemson University have demonstrated a simple relationship between the surface heat flux and the standard deviation of temperature fluctuations. Similar results were observed in the aerial thermal imagery SRNL collected at different locations along the thermal plume and at different elevations. SRNL will present evidence that the results at Clemson University are applicable to cooling lakes.

Villa-Aleman, E; Saleem Salaymeh, S; Timothy Brown, T; Alfred Garrett, A; Malcolm Pendergast, M; Linda Nichols, L

2007-12-19T23:59:59.000Z

5

Measuring spatial variability in soil characteristics  

DOE Patents [OSTI]

The present invention provides systems and methods for measuring a load force associated with pulling a farm implement through soil that is used to generate a spatially variable map that represents the spatial variability of the physical characteristics of the soil. An instrumented hitch pin configured to measure a load force is provided that measures the load force generated by a farm implement when the farm implement is connected with a tractor and pulled through or across soil. Each time a load force is measured, a global positioning system identifies the location of the measurement. This data is stored and analyzed to generate a spatially variable map of the soil. This map is representative of the physical characteristics of the soil, which are inferred from the magnitude of the load force.

Hoskinson, Reed L. (Rigby, ID); Svoboda, John M. (Idaho Falls, ID); Sawyer, J. Wayne (Hampton, VA); Hess, John R. (Ashton, ID); Hess, J. Richard (Idaho Falls, ID)

2002-01-01T23:59:59.000Z

6

Multiscale Variability of Deep Convection In Realation to Large-Scale Circulation in TOGA COARE  

Science Journals Connector (OSTI)

Deep convection over the Indo–Pacific oceanic warm pool in the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) occurred in cloud clusters, which grouped together in regions favoring their occurrence. ...

Shuyi S. Chen; Robert A. Houze Jr.; Brian E. Mapes

1996-05-01T23:59:59.000Z

7

Regional variability of convection over northern India during the pre-monsoon season  

Science Journals Connector (OSTI)

In general, the overall differences in activity and timing of convection are a result of the influence of large-scale regional and synoptic flow patterns on the local mesoscale environment. The linkage between...

Soma Sen Roy; Shouraseni Sen Roy

2011-01-01T23:59:59.000Z

8

Atmospheric structure and variability in areas of convective storms determined from 3-h rawinsonde data  

E-Print Network [OSTI]

changes in TTI determined from charts in Fig. 58. . 101 60 61 62 Cumulative frequency distributions of changes in TTI in AVE II . . ~ . . . . . ~ Surface analysis at 2100 GMT, 11 May 1974 Satellite and radar composite at 2200 GMT, 11 May 1974 102... change in the probability of convective activity by a factor of 8 or more in 3 h. Between 30% and 60% of the total changes in parameters associated with convective activity over a 12-h period is shown to take place during a 3-h period. These large...

Wilson, Gregory Sims

2012-06-07T23:59:59.000Z

9

Application of a ratiometric laser induced fluorescence (LIF) thermometry for micro-scale temperature measurement for natural convection flows  

E-Print Network [OSTI]

A ratiometric laser induced fluorescence (LIF) thermometry applied to micro-scale temperature measurement for natural convection flows. To eliminate incident light non-uniformity and imperfection of recording device, two fluorescence dyes are used...

Lee, Heon Ju

2004-11-15T23:59:59.000Z

10

Convective Coupling and Interannual and Intraseasonal Coupled Variabilities in the Tropics  

Science Journals Connector (OSTI)

Recent analyses point at close structural similarities and intimate dynamical connections among the members of a wide spectrum of variabilities in the global Tropics. This suggests that these oscillations with widely different timescales may have ...

P. Goswami; Rameshan K.

2000-08-01T23:59:59.000Z

11

Ten Years of Measurements of Tropical Upper-Tropospheric Water Vapor by MOZAIC. Part I: Climatology, Variability, Transport, and Relation to  

E-Print Network [OSTI]

the International Satellite Cloud Climatology Project (ISCCP). 1. Introduction Water vapor is the key atmosphericTen Years of Measurements of Tropical Upper-Tropospheric Water Vapor by MOZAIC. Part I: Climatology, Variability, Transport, and Relation to Deep Convection ZHENGZHAO LUO, DIETER KLEY,* AND RICHARD H. JOHNSON

Lombardi, John R.

12

Variability in Measured Space Temperatures in 60 Homes  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Variability in Measured Space Variability in Measured Space Temperatures in 60 Homes David Roberts National Renewable Energy Laboratory Kerylyn Lay EnerNOC (formerly of the National Renewable Energy Laboratory) Technical Report NREL/TP-5500-58059 March 2013 NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. National Renewable Energy Laboratory 15013 Denver West Parkway Golden, Colorado 80401 303-275-3000 * www.nrel.gov Contract No. DE-AC36-08GO28308 Variability in Measured Space Temperatures in 60 Homes David Roberts National Renewable Energy Laboratory Kerylyn Lay EnerNOC (formerly of the National Renewable Energy Laboratory)

13

Variability Analysis of Complex Networks Measures based on Stochastic Distances  

E-Print Network [OSTI]

Complex networks can model the structure and dynamics of different types of systems. It has been shown that they are characterized by a set of measures. In this work, we evaluate the variability of complex networks measures face to perturbations and, for this purpose, we impose controlled perturbations and quantify their effect. We analyze theoretical models (random, small-world and scale-free) and real networks (a collaboration network and a metabolic networks) along with the shortest path length, vertex degree, local cluster coefficient and betweenness centrality measures. In such analysis, we propose the use of three stochastic quantifiers: the Kullback-Leibler divergence and the Jensen-Shannon and Hellinger distances. The sensitivity of these measures was analyzed with respect to the following perturbations: edge addition, edge removal, edge rewiring and node removal, all of them applied at different intensities. The results reveal that the evaluated measures are influenced by these perturbations. Additio...

Cabral, Raquel; Ramírez, Jaime

2014-01-01T23:59:59.000Z

14

Comment on Magnetohydrodynamic non-Darcy mixed convection heat transfer from a vertical heated plate embedded in a porous medium with variable porosity, by Dulal Pal  

E-Print Network [OSTI]

In the above paper the author treats the boundary layer flow along a vertical flat plate, immersed in a Darcy Brinkman Forchheimer porous medium. The porosity and the permeability of the porous medium are variable across the boundary layer. In addition a magnetic field with constant strength is applied normal to the plate. The fluid temperature at the plate is constant and different from that of the ambient fluid. This temperature difference creates a buoyancy force and the flow is characterized as mixed convection. The partial differential equations of the boundary layer flow are transformed into ordinary differential equations and subsequently are solved with the Runge-Kutta Fehlberg method. The results are presented in two tables and 11 figures.

Pantokratoras, Asterios

2014-01-01T23:59:59.000Z

15

A Climatological measurement methods This appendix describes the methods of climatological variable measurement at the  

E-Print Network [OSTI]

as the total energy received as radiation per unit surface area tangential to the earths surface. As mentioned-wave A sensor used to measure the energy flux density of short-wave radiation is referred to as a pyranometerA Climatological measurement methods This appendix describes the methods of climatological variable

16

Measurement and Modeling of Solar and PV Output Variability: Preprint  

Broader source: Energy.gov (indexed) [DOE]

Measurement and Modeling of Measurement and Modeling of Solar and PV Output Variability Preprint M. Sengupta To be presented at SOLAR 2011 Raleigh, North Carolina May 17-21, 2011 Conference Paper NREL/CP-5500-51105 April 2011 NOTICE The submitted manuscript has been offered by an employee of the Alliance for Sustainable Energy, LLC (Alliance), a contractor of the US Government under Contract No. DE-AC36-08GO28308. Accordingly, the US Government and Alliance retain a nonexclusive royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for US Government purposes. This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty,

17

Robust Shot Noise Measurement for Continuous Variable Quantum Key Distribution  

E-Print Network [OSTI]

We study a practical method to monitor in real-time the behavior of a Continuous Variable Quantum Key Distribution (CVQKD) system, and especially the shot noise measurement procedure, for the presence of an eavesdropper. The amount of secret key that can be extracted from the raw statistics of a CVQKD system depends strongly on a shot noise estimate since this quantity affects in particular the computation of the excess noise (i.e. noise in excess of the shot noise) added by an eavesdropper on the quantum channel. Some powerful quantum hacking attacks rely on faking the estimated value of the shot noise to hide an intercept-and-resend eavesdropping strategy, notably by targeting the calibration of the system, the saturation of the homodyne detection device or the wavelength dependency of some optical components. We describe a new countermeasure that consists in fairly general statistical tests build on top of an existing real-time shot-noise measurement technique and show that it is able to defeat all these attacks.

Sébastien Kunz-Jacques; Paul Jouguet

2014-06-29T23:59:59.000Z

18

What measures climate? A variety of variables including their variability and extreme values determine climate for  

E-Print Network [OSTI]

climate zones? The sun is the ultimate power source for the climate "machine". The uneven distribution conditions. Typical variables to consider are temperature (maximum, miniumum), precipitation (includes rain, sleet, snow, hail, etc), sunlight/cloudiness, wind, humidity, ice cover, sea temperature, etc... Many

Allan, Richard P.

19

Convection towers  

DOE Patents [OSTI]

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

Prueitt, Melvin L. (Los Alamos, NM)

1996-01-01T23:59:59.000Z

20

Convection towers  

DOE Patents [OSTI]

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

Prueitt, Melvin L. (Los Alamos, NM)

1995-01-01T23:59:59.000Z

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


21

Convection towers  

DOE Patents [OSTI]

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water. 6 figs.

Prueitt, M.L.

1996-01-16T23:59:59.000Z

22

Convection towers  

DOE Patents [OSTI]

Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode.

Prueitt, Melvin L. (Los Alamos, NM)

1994-01-01T23:59:59.000Z

23

A software framework for developing measurement applications under variable requirements  

Science Journals Connector (OSTI)

A framework for easily developing software for measurement and test applications under highly and fast-varying requirements is proposed. The framework allows the software quality in terms of flexibility usability and maintainability to be maximized. Furthermore the development effort is reduced and finalized by relieving the test engineer of development details. The framework can be configured for satisfying a large set of measurement applications in a generic field for an industrial test division a test laboratory or a research center. As an experimental case study the design the implementation and the assessment inside the application to a measurement scenario of magnettesting at the European Organization for Nuclear Research is reported.

Pasquale Arpaia; Marco Buzio; Lucio Fiscarelli; Vitaliano Inglese

2012-01-01T23:59:59.000Z

24

Experience in Measuring Backbone Traffic Variability: Models, Metrics, Measurements and Meaning  

E-Print Network [OSTI]

was specifically motivated by the question: to what extent does traffic variability justify the M. Roughen, A

Fisher, Kathleen

25

Convection towers  

DOE Patents [OSTI]

Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode. 5 figures.

Prueitt, M.L.

1994-02-08T23:59:59.000Z

26

Experimental Verification of a Mass Measurement Device under Zero Gravity with a Prismatic Variable Stiffness Mechanism  

Science Journals Connector (OSTI)

A new method to measure the mass of an object in microgravity is proposed in this paper. The proposed method uses a new system that consists of a prismatic variable stiffness mechanism and an actuator. The obj...

Ryota Ishibashi; Ryuta Ozawa; Sadao Kawamura

2010-01-01T23:59:59.000Z

27

EPR-Steering measure for two-mode continuous variable states  

E-Print Network [OSTI]

Steering is a manifestation of quantum correlations that embodies the Einstein-Podolsky-Rosen (EPR) paradox. While there have been recent attempts to quantify steering, continuous variable systems remained elusive. We introduce a steering measure for two-mode continuous variable systems that is valid for arbitrary states. The measure is based on the violation of an optimized variance test for the EPR paradox, and admits a computable and experimentally friendly lower bound only depending on the second moments of the state, which reduces to a recently proposed quantifier of steerability by Gaussian measurements. We further show that Gaussian states are extremal with respect to our measure, minimizing it among all continuous variable states with fixed second moments. As a byproduct of our analysis, we generalize and relate well-known EPR-steering criteria. Finally an operational interpretation is provided, as the proposed measure is shown to quantify the optimal guaranteed key rate in semi-device independent qua...

Kogias, Ioannis

2014-01-01T23:59:59.000Z

28

EPR-Steering measure for two-mode continuous variable states  

E-Print Network [OSTI]

Steering is a manifestation of quantum correlations that embodies the Einstein-Podolsky-Rosen (EPR) paradox. While there have been recent attempts to quantify steering, continuous variable systems remained elusive. We introduce a steering measure for two-mode continuous variable systems that is valid for arbitrary states. The measure is based on the violation of an optimized variance test for the EPR paradox, and admits a computable and experimentally friendly lower bound only depending on the second moments of the state, which reduces to a recently proposed quantifier of steerability by Gaussian measurements. We further show that Gaussian states are extremal with respect to our measure, minimizing it among all continuous variable states with fixed second moments. As a byproduct of our analysis, we generalize and relate well-known EPR-steering criteria. Finally an operational interpretation is provided, as the proposed measure is shown to quantify the optimal guaranteed key rate in semi-device independent quantum key distribution.

Ioannis Kogias; Gerardo Adesso

2014-11-03T23:59:59.000Z

29

Measurements of Heavy Convective Rainfall in the Presence of Hail in Flood-Prone Areas Using an X-Band Polarimetric Radar  

Science Journals Connector (OSTI)

The utility of X-band polarimetric radar to provide rainfall estimations with high spatial and temporal resolution in heavy convective precipitation in the presence of hail is explored. A case study involving observations of strong convective ...

Sergey Y. Matrosov; Robert Cifelli; David Gochis

2013-02-01T23:59:59.000Z

30

Atmospheric Radiation Measurement (ARM) Data from Black Forest Germany for the Convective and Orographically Induced Precipitation Study (COPS)  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

The primary goal of the ARM Program is to improve the treatment of cloud and radiation physics in global climate models in order to improve the climate simulation capabilities of these models. ARM maintains four major, permanent sites for data collection and deploys the ARM Mobile Facility (AMF) to other sites as determined. In 2007 the AMF operated in the Black Forest region of Germany as part of the Convective and Orographically Induced Precipitation Study (COPS). Scientists studied rainfall resulting from atmospheric uplift (convection) in mountainous terrain, otherwise known as orographic precipitation. This was part of a six -year duration of the German Quantitative Precipitation Forecasting (QPF) Program. COPS was endorsed as a Research and Development Project by the World Weather Research Program. This program was established by the World Meteorological Organization to develop improved and cost-effective forecasting techniques, with an emphasis on high-impact weather. A large collection of data plots based on data streams from specific instruments used at Black Forest are available via a link from ARM's Black Forest site information page. Users will be requested to create a password, but the plots and the data files in the ARM Archive are free for viewing and downloading.

31

Convective heater  

DOE Patents [OSTI]

A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation.

Thorogood, Robert M. (Macungie, PA)

1983-01-01T23:59:59.000Z

32

Convective heater  

DOE Patents [OSTI]

A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation.

Thorogood, Robert M. (Macungie, PA)

1986-01-01T23:59:59.000Z

33

Midlatitude Continental Convective Clouds Experiment (MC3E)  

SciTech Connect (OSTI)

Convective processes play a critical role in the Earth’s energy balance through the redistribution of heat and moisture in the atmosphere and subsequent impacts on the hydrologic cycle. Global observation and accurate representation of these processes in numerical models is vital to improving our current understanding and future simulations of Earth’s climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales that are associated with convective and stratiform precipitation processes; therefore, they must turn to parameterization schemes to represent these processes. In turn, the physical basis for these parameterization schemes needs to be evaluated for general application under a variety of atmospheric conditions. Analogously, space-based remote sensing algorithms designed to retrieve related cloud and precipitation information for use in hydrological, climate, and numerical weather prediction applications often rely on physical “parameterizations” that reliably translate indirectly related instrument measurements to the physical quantity of interest (e.g., precipitation rate). Importantly, both spaceborne retrieval algorithms and model convective parameterization schemes traditionally rely on field campaign data sets as a basis for evaluating and improving the physics of their respective approaches. The Midlatitude Continental Convective Clouds Experiment (MC3E) will take place in central Oklahoma during the April–May 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administration’s (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign leverages the unprecedented observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors, and new ARM instrumentation purchased with American Recovery and Reinvestment Act funding. The overarching goal is to provide the most complete characterization of convective cloud systems, precipitation, and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall retrieval algorithms over land that have never before been available. Several different components of convective cloud and precipitation processes tangible to both the convective parameterization and precipitation retrieval algorithm problem are targeted, such as preconvective environment and convective initiation, updraft/downdraft dynamics, condensate transport and detrainment, precipitation and cloud microphysics, spatial and temporal variability of precipitation, influence on the environment and radiation, and a detailed description of the large-scale forcing.

Jensen, MP; Petersen, WA; Del Genio, AD; Giangrande, SE; Heymsfield, A; Heymsfield, G; Hou, AY; Kollias, P; Orr, B; Rutledge, SA; Schwaller, MR; Zipser, E

2010-04-01T23:59:59.000Z

34

Does the ECMWF IFS convection parameterisation with stochastic physics correctly reproduce relationships between convection and the large-scale state?  

Science Journals Connector (OSTI)

Important questions concerning parameterisation of tropical convection are how should sub-grid scale variability be represented, and which large-scale variables should be used in the parameterisations? Here we compare the statistics of ...

Peter A. G. Watson; H. M. Christensen; T. N. Palmer

35

ARM - Evaluation Product - Convective Vertical Velocity  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

ProductsConvective Vertical Velocity ProductsConvective Vertical Velocity Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Evaluation Product : Convective Vertical Velocity 2011.04.25 - 2011.05.23 Site(s) SGP General Description Convective processes play an important role in Earth's energy balance by distributing heat and moisture throughout the atmosphere. In particular, vertical air motions associated with these processes are inherently linked to the life cycle of these convective systems and are therefore directly tied to their energy budget. However, direct measurements of vertical air motions (e.g., in situ aircraft observations) are sparse, making it difficult to compare them with numerical model output, which relies on convective parameterization schemes that have yet to be extensively

36

ECG-Derived Respiration: Comparison and New Measures for Respiratory Variability  

E-Print Network [OSTI]

ECG-Derived Respiration: Comparison and New Measures for Respiratory Variability Devy Widjaja1 During ECG recording, several methods can be applied to derive a respiratory signal from the ECG (EDR signal). In this paper 4 EDR methods, including ECG filtering, R and RS amplitude based techniques

37

3 Canopy microclimate measurement This chapter presents methods general to the measurement of climate variables at  

E-Print Network [OSTI]

to maximize data capture and improve signal quality assessment. Duplicate measurements were usually recorded.1. For measurements that did not vary spatially (e.g. incoming solar radiation on a clear day), a single measurement-2 s-1 72 24 Air temperature 0.243 1.5 °C 2 3 Net Radiation 5.174 12 W m-2 14 3 Global short-wave 1

38

SURFACE TENSION DRIVEN CONVECTION  

E-Print Network [OSTI]

SURFACE TENSION DRIVEN CONVECTION DIJKSTRA, SENGUL, WANG INTRODUCTION LINEAR THEORY MAIN THEOREMS CONCLUDING REMARKS DYNAMIC TRANSITIONS OF SURFACE TENSION DRIVEN CONVECTION H.Dijkstra T. Sengul S. Wang #12;SURFACE TENSION DRIVEN CONVECTION DIJKSTRA, SENGUL, WANG INTRODUCTION LINEAR THEORY MAIN THEOREMS

Wang, Shouhong

39

Abstract--Heart rate variability (HRV) is frequently used to measure autonomic nervous system (ANS) activity. However,  

E-Print Network [OSTI]

1 of 4 Abstract--Heart rate variability (HRV) is frequently used to measure autonomic nervous frequency (HF) ratio with little change in mean heart rate. Results suggest that nicotine affects both components may yield erroneous results. Keywords--Autonomic regulation, heart rate variability, Lomb

40

Observation of moisture tendencies related to shallow convection  

Science Journals Connector (OSTI)

Tropospheric moisture is a key factor controlling the global climate and its variability. For instance, moistening of the lower troposphere is necessary to trigger the convective phase of a Madden-Julian Oscillation. However, the relative ...

H. Bellenger; K. Yoneyama; M. Katsumata; T. Nishizawa; K. Yasunaga; R. Shirooka

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


41

Evaluation of Trigger Functions for Convective Parameterization Schemes Using Observations  

Science Journals Connector (OSTI)

Realistic simulation of different modes of atmospheric variability ranging from diurnal cycle to interannual variation in global climate models (GCMs) depends crucially on the convection trigger criteria. In this study, using the data from ...

E. Suhas; Guang J. Zhang

2014-10-01T23:59:59.000Z

42

Convective heat flow probe  

DOE Patents [OSTI]

A convective heat flow probe device is provided which measures heat flow and fluid flow magnitude in the formation surrounding a borehole. The probe comprises an elongate housing adapted to be lowered down into the borehole; a plurality of heaters extending along the probe for heating the formation surrounding the borehole; a plurality of temperature sensors arranged around the periphery of the probe for measuring the temperature of the surrounding formation after heating thereof by the heater elements. The temperature sensors and heater elements are mounted in a plurality of separate heater pads which are supported by the housing and which are adapted to be radially expanded into firm engagement with the walls of the borehole. The heat supplied by the heater elements and the temperatures measured by the temperature sensors are monitored and used in providing the desired measurements. The outer peripheral surfaces of the heater pads are configured as segments of a cylinder and form a full cylinder when taken together. A plurality of temperature sensors are located on each pad so as to extend along the length and across the width thereof, with a heating element being located in each pad beneath the temperature sensors. An expansion mechanism driven by a clamping motor provides expansion and retraction of the heater pads and expandable packet-type seals are provided along the probe above and below the heater pads.

Dunn, J.C.; Hardee, H.C.; Striker, R.P.

1984-01-09T23:59:59.000Z

43

ARM Convective Available Potential Energy (CAPE), Convective Inhibition (CIN) Product  

SciTech Connect (OSTI)

ARM soundings are used to determine Convective Available Potential Energy (CAPE), Convective Inhibition (CIN) and associated properties, using the following relationships;

Jensen, Michael

2014-04-10T23:59:59.000Z

44

ARM Convective Available Potential Energy (CAPE), Convective Inhibition (CIN) Product  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

ARM soundings are used to determine Convective Available Potential Energy (CAPE), Convective Inhibition (CIN) and associated properties, using the following relationships;

Jensen, Michael

45

Heat Transfer and Convection Currents  

Science Journals Connector (OSTI)

...October 1965 research-article Heat Transfer and Convection Currents D. C...convection in a medium with internal heat generation is discussed semi-quantitatively...States English United Kingdom 1966 Heat transfer and convection currents Tozer D...

1965-01-01T23:59:59.000Z

46

Origins of convective activity over Panama  

E-Print Network [OSTI]

Satellite-derived outgoing longwave radiation (OLR) data. were used to examine convective variability over the Panama region. Time series analysis of the area- averaged daily OLR data, for 1984 and 1985 revealed a, persistent 12-d oscillation... in convective activity during each season. Composite analyses of OLR data, for the area 120'W-40'W and 35'S-35'N for the 1984 dry (1 January ? 9 May) and wet (10 Msy? 4 December) seasons showed this oscillation extends beyond Panama and the Central America...

Strager, Christopher Stephen

1989-01-01T23:59:59.000Z

47

A new measure of acceleration of heart rate: dependence on age and comparison with time domain conventional heart rate variability measures  

E-Print Network [OSTI]

A new measure of acceleration of heart rate: dependence on age and comparison with time domain conventional heart rate variability measures Giuseppe Germanò, M.D., Gianfranco Piccirillo, M.D., *Camillo We introduce a new index, Acceleration Ratio (AR), in order to investigate the dependence of Heart

Cammarota, Camillo

48

Towards an extension of 1905 relativistic dynamics with a variable rest mass measuring potential energy  

E-Print Network [OSTI]

From a rigorous historic analysis of 1686 I. Newton and 1905 A. Einstein works where the last derived the universal mass-energy relationship, it is concluded that rest mass measures potential energy. From the same formula used to obtain that relation, it is derived the ratio Total Energy/Potential Energy is equal to the gamma relativistic factor. It is derived a formula for the variation of a body rest mass with its position in a gravity field, explaining with it the behavior of an atomic clock. It is revised the bodies free fall in a gravitational field, finding that a constant total mass is equal to the gravitational mass, while the variable rest mass is equal to the inertial mass, maintaining all an identical behavior independent of their masses. A revision of the E\\"otv\\"os experiment concludes that it is unable to detect the found difference between inertial and gravitational mass. Applying the extended 1905 relativistic dynamics to Mercury, its perihelion shift is determined; it is concluded with the convenience to continue its development, what can imply a revision of Physics since 1905 with important results in the unification of natural forces and other open problems.

Rafael A. Valls Hidalgo-Gato

2012-10-15T23:59:59.000Z

49

Damage measurements on the NWTC direct-drive, variable-speed test bed  

SciTech Connect (OSTI)

The NWTC (National Wind Technology Center) Variable-Speed Test Bed turbine is a three-bladed, 10-meter, downwind machine that can be run in either fixed-speed or variable-speed mode. In the variable-speed mode, the generator torque is regulated, using a discrete-stepped load bank to maximize the turbine`s power coefficient. At rated power, a second control loop that uses blade pitch to maintain rotor speed essentially as before, i.e., using the load bank to maintain either generator power or (optionally) generator torque. In this paper, the authors will use this turbine to study the effect of variable-speed operation on blade damage. Using time-series data obtained from blade flap and edge strain gauges, the load spectrum for the turbine is developed using rainflow counting techniques. Miner`s rule is then used to determine the damage rates for variable-speed and fixed-speed operation. The results illustrate that the controller algorithm used with this turbine introduces relatively large load cycles into the blade that significantly reduce its service lifetime, while power production is only marginally increased.

Sutherland, H.J. [Sandia National Lab., Albuquerque, NM (United States); Carlin, P.W. [National Renewable Energy Lab., Golden, CO (United States)

1998-12-31T23:59:59.000Z

50

Convective Cloud Lifecycles Lunchtime seminar  

E-Print Network [OSTI]

Convective Cloud Lifecycles Lunchtime seminar 19th May 2009 Bob Plant Department of Meteorology, University of Reading, UK #12;Introduction Obtain life cycle statistics for clouds in CRM simulations Why Conclusions Convective Cloud Lifecycles ­ p.1/3 #12;Why bother? Convective Cloud Lifecycles ­ p.2/3 #12;Some

Plant, Robert

51

Measuring the period of the delta Scuti variable U1425-01208594 in Cassiopeia  

E-Print Network [OSTI]

The variability of U1425-01208594 was recently discovered by Schmidtobreick et al, who suggested that it is a member of the delta Scuti family of pulsating stars. Photometry conducted by the authors revealed a period of 0.06695(8) d and a peak-to-peak amplitude of 0.014 mag.

Jeremy Shears; David Boyd; Steve Brady; Ian Miller; Roger Pickard

2007-11-30T23:59:59.000Z

52

Patterns of Convection in the Tropical Western Pacific  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Patterns of Convection in the Tropical Western Pacific Patterns of Convection in the Tropical Western Pacific J. H. Mather Pacific Northwest National Laboratory Richland, Washington Introduction Convection is ubiquitous throughout the maritime continent region. However, the frequency of convec- tion is not uniform. While much of this region does not experience seasons to the same degree as one finds in mid-latitudes, the annual cycle of the sun's passage does have a large impact on convection throughout the maritime continent and the tropical western Pacific. The distribution of islands also affects convection in a variety of ways. Atmospheric Radiation Measurement (ARM) Program has three sites in the Tropical Western Pacific (TWP) region, illustrated in Figure 1. The sites are located on Manus, Nauru, and at Darwin, Australia.

53

Physical Characterization of Tropical Oceanic Convection Observed in KWAJEX  

Science Journals Connector (OSTI)

The Tropical Rainfall Measuring Mission (TRMM) Kwajalein Experiment (KWAJEX) was designed to obtain an empirical physical characterization of precipitating convective clouds over the tropical ocean. Coordinated datasets were collected by three ...

Sandra E. Yuter; Robert A. Houze Jr.; Eric A. Smith; Thomas T. Wilheit; Edward Zipser

2005-04-01T23:59:59.000Z

54

Dose measurements behind reduced shielding at the Texas A&M University variable energy cyclotron  

E-Print Network [OSTI]

, the relative count rates of the detectors after irradiation can be used to estimate the spectral dis- tribution of the neutron field, while the absolute activity of the detector is a measure of exposure (Ce69). This technique is useful in measuring neutron... be measured simultaneously in high flux areas in the vault and in low flux areas outside the reduced shielding. The detector normally utilized in the spherical remmeter is a lithium iodide, europium activated (LiI(Eu)) scintillation type thermal neutron...

Kay, Douglas Carey

2012-06-07T23:59:59.000Z

55

Dimension Reduction with Gene Expression Data Using Targeted Variable Importance Measurement  

E-Print Network [OSTI]

and we refer to it as the TMLE-VIM procedure. 1. Obtain theResults: We propose a TMLE-VIM dimension reduction procedureimportance measurement (VIM) in the frame work of targeted

Wang, Hui; van der Laan, Mark J

2011-01-01T23:59:59.000Z

56

Measurement of the orbital and superhump periods of the eclipsing cataclysmic variable SDSS J170213.26+322954.1  

E-Print Network [OSTI]

The orbital period of the eclipsing cataclysmic variable SDSS J170213.26+322954.1 has been measured as 0.10008215+/-0.00000001d using observations of eclipses during the first recorded superoutburst in October 2005 together with eclipses observed in quiescence in July 2003. This period puts the system in the centre of the period gap. Observation of superhumps during the October 2005 outburst with a period of 0.10496+/-0.00015d confirms this to be a UGSU-type system with a period excess of 4.9%.

David Boyd; Arto Oksanen; Arne Henden

2006-01-31T23:59:59.000Z

57

The Variability of LateType Stars' Diameters Measured Using MidInfrared Interferometry  

E-Print Network [OSTI]

a , D. D. S. Hale b , and C. H. Townes a a Space Sciences Laboratory, UC Berkeley, Berkeley, CA 94720 b and a narrow bandpass appear to be optimum for penetrating the dust and gas and obtaining a representative description can be found in Hale et al. (2000). 2 Baselines up to 56 m were used to measure visibilities of ff

California at Berkeley, University of

58

Synergistic Effect of coal blends on thermoplasticity evaluated using a temperature-variable dynamic viscoelastic measurement  

SciTech Connect (OSTI)

To maximize the conversion of low-quality coal into good coke, we investigated the thermoplasticity of various binary blends of caking coals with slightly or noncaking coals using a dynamic viscoelastic technique with a temperature-variable rheometer. Coal blend samples were prepared by mixing two coals (1:1 by weight), which were heated from room temperature to 600 C at a rate of 3-80{sup o}C/min. At the slow rate of 3{sup o}C/min, the blends had a tan {delta} that was generally lower than the calculated value, showing that a negative interaction caused a loss of thermoplasticity. In contrast, at the rapid heating rate of 80{sup o}C/min, the tan {delta} of some blends was higher than the calculated value, indicating a positive interaction that enhanced the thermoplasticity. With rapid heating, the thermoplasticity of each coal itself increased, and their thermoplastic temperature ranges widened with rapid heating. Therefore, rapid heating was effective at converting these coal blends into good cokes. Moreover, even with slow heating, when a combination of coals (Gregory:Enshu, 1:1) showing some thermoplasticity in nearly the same temperature range was blended, a desirable synergistic effect of the blend was obtained. This suggests that blending coal with an overlapping thermoplastic temperature range is important for the synergistic effect, regardless of the heating rate. 15 refs., 9 figs., 2 tabs.

Toshimasa Takanohashi; Takahiro Shishido; Ikuo Saito; Kensuke Masaki; Atsushi Dobashi; Kiyoshi Fukada [National Institute of Advanced Industrial Science and Technology, Tsukuba (Japan)

2006-12-15T23:59:59.000Z

59

Kinematic measures and stroke rate variability in elite female 200-m swimmers in the four swimming techniques: Athens 2004 Olympic semi-finalists and French National  

E-Print Network [OSTI]

1 Kinematic measures and stroke rate variability in elite female 200-m swimmers in the four of this work was to study stroke rate variability in elite female swimmers (200-m events, all four techniques semi-finalists (group N, n=64). Since swimming speed (V) is the product of stroke rate (SR) and stroke

Paris-Sud XI, Université de

60

The Phenix ultimate natural convection test  

SciTech Connect (OSTI)

The French sodium cooled fast reactor Phenix was shut down in 2009 after 35 years of operation. Before decommissioning, a final set of tests were performed by the CEA during 9 months. Several topics were involved such as thermal hydraulics, core physics and fuel behaviour. Among these ultimate experiments, two thermal hydraulic tests were performed: an asymmetrical test consisting in a trip of one secondary pump and a natural convection test in the primary circuit. Recognizing the unique opportunity offered by these Phenix ultimate tests, IAEA decided in 2007 to launch a Coordinated Research Project (CRP) devoted to benchmarking analyses with system codes on the Phenix natural convection test. One objective of the natural convection test in Phenix reactor is the assessment of the CATHARE system code for safety studies on future and advanced sodium cooled fast reactors. The aim of this paper is to describe this test, which was performed on June 22-23, 2009, and the associated benchmark specifications for the CRP work. The paper reminds briefly the Phenix reactor with the main physical parameters and the instrumentation used during the natural convection test. After that, the test scenario is described: - initial state at a power of 120 MWth, - test beginning resulting from a manual dry out of the two steam generators, - manual scram, - manual trip on the three primary pumps without back-up by pony motors, - setting and development of natural convection in the primary circuit, in a first phase without significant heat sink in the secondary circuits and in a second phase with significant heat sink in the secondary circuits, by opening the casing of steam generators to create an efficient heat sink, by air natural circulation in the steam generators casing. The benchmark case ends after this second phase, which corresponds to the experimental test duration of nearly 7 hours. The paper presents also the benchmark specifications data supplied by the CEA to all participants of this CRP in order to perform calculations (core, primary circuit, primary pumps, IHX, shutdown system, operating parameters, test scenario and real test conditions). Finally, main test results and analyses are presented including the evolution of the core and of the heat exchangers inlet and outlet temperatures, and some local temperature measurements. The natural convection has been easily set up in the pool type reactor Phenix with different boundary conditions at the secondary side, with or without heat sink. The data obtained during this unique test represent some very useful and precious results for the development of SFR in a wide range of thematic such as numerical methods dedicated to thermal-hydraulics safety analyses (system codes, CFD codes and coupling system and CFD codes) and instrumentation. (authors)

Gauthe, P. [CEA, DER, SESI, F-13108, Saint Paul lez Durance (France); Pialla, D.; Tenchine, D. [CEA, DEN, STMF, F-38054, Grenoble (France); Vasile, A. [CEA, DER, SESI, F-13108, Saint Paul lez Durance (France); Rochwerger, D. [CEA, DEN, DEIM, F-30207, Bagnols-sur-Ceze (France)

2012-07-01T23:59:59.000Z

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


61

Different convection models in ATLAS  

E-Print Network [OSTI]

Convection is an important phenomenon in the atmospheres of A-type and cooler stars. A description of convection in ATLAS models is presented, together with details of how it is specified in model calculations. The effects of changing the treatment of convection on model structures and how this affects observable quantities are discussed. The role of microturbulence is examined, and its link to velocity fields within the atmosphere. Far from being free parameters, mixing-length and microturbulence should be constrained in model calculations.

Barry Smalley

2005-09-19T23:59:59.000Z

62

Seasonal and ENSO variability in global ocean phytoplankton chlorophyll derived from 4 years of SeaWiFS measurements  

E-Print Network [OSTI]

of a possible 184 modes, which explain 67% of the total temporal variability associated with the global meanSeasonal and ENSO variability in global ocean phytoplankton chlorophyll derived from 4 years of Sea and other sources of phytoplankton variability on global scales, which is an important component

Yoder, James S.

63

Isentropic Analysis of Convective Motions  

Science Journals Connector (OSTI)

This paper analyzes the convective mass transport by sorting air parcels in terms of their equivalent potential temperature to determine an isentropic streamfunction. By averaging the vertical mass flux at a constant value of the equivalent ...

Olivier M. Pauluis; Agnieszka A. Mrowiec

2013-11-01T23:59:59.000Z

64

Stratiform and Convective Precipitation Observed by Multiple Radars during the DYNAMO/AMIE Experiment  

Science Journals Connector (OSTI)

In this study, methods of convective/stratiform precipitation classification and surface rain-rate estimation based on the Atmospheric Radiation Measurement Program (ARM) cloud radar measurements were developed and evaluated. Simultaneous and ...

Min Deng; Pavlos Kollias; Zhe Feng; Chidong Zhang; Charles N. Long; Heike Kalesse; Arunchandra Chandra; Vickal V. Kumar; Alain Protat

2014-11-01T23:59:59.000Z

65

Passive microwave observations of mesoscale convective systems over the tropical Pacific Ocean  

E-Print Network [OSTI]

This paper presents high resolution passive microwave measurements obtained in the western Pacific warm pool region. These measurements represent the first comprehensive observations of convection over the tropical oceans, and were obtained from...

McGaughey, Gary Rae

2012-06-07T23:59:59.000Z

66

Turbulent Compressible Convection with Rotation - Penetration above a Convection Zone  

E-Print Network [OSTI]

We perform Large eddy simulations of turbulent compressible convection in stellar-type convection zones by solving the Navi\\'{e}r-Stokes equations in three dimensions. We estimate the extent of penetration into the stable layer above a stellar-type convection zone by varying the rotation rate ({\\boldmath$\\rm\\Omega$}), the inclination of the rotation vector ($\\theta$) and the relative stability ($S$) of the upper stable layer. The computational domain is a rectangular box in an f-plane configuration and is divided into two regions of unstable and stable stratification with the stable layer placed above the convectively unstable layer. Several models have been computed and the penetration distance into the stable layer above the convection zone is estimated by determining the position where time averaged kinetic energy flux has the first zero in the upper stable layer. The vertical grid spacing in all the model is non-uniform, and is less in the upper region so that the flows are better resolved in the region of interest. We find that the penetration distance increases as the rotation rate increases for the case when the rotation vector is aligned with the vertical axis. However, with the increase in the stability of the upper stable layer, the upward penetration distance decreases. Since we are not able to afford computations with finer resolution for all the models, we compute a number of models to see the effect of increased resolution on the upward penetration. In addition, we estimate the upper limit on the upward convective penetration from stellar convective cores.

Partha S. Pal; Harinder P. Singh; Kwing L. Chan; M. P. Srivastava

2008-02-13T23:59:59.000Z

67

Pseudosteady-state mixed convection inside rotating spherical containers  

SciTech Connect (OSTI)

A computational study of the pseudosteady-state two-dimensional mixed convection within rotating spherical containers is presented. The computations are based on an iterative, finite-volume numerical procedure using primitive dependent variables, whereby the time-dependent continuity, momentum and energy equations in the spherical coordinate system are solved. Natural convection effect is modeled via the Boussinesq approximation. For a fixed Prandtl number of 4.62, parametric studies were performed by varying the Rayleigh number in order to cover the laminar regime adequately. For a given Rayleigh number, the ratio of Gr/Re{sup 2} was varied between 0.1 and 10. Given a Rayleigh number, the streamline patterns maintain their general shape with a dominant rotating vortex. As the forced convection effect becomes less marked, the streamlines exhibit less pronounced gradients near the surface of the sphere. As the rotational effect become more marked, the extent of the deviation from the limiting case of non-rotating spheres becomes more noticed. However, the bottom of the sphere still remains to be the region with enhanced heat transfer. Given a rotational Reynolds number, the streamline patterns are not affected greatly as the natural convection is promoted, however the temperature gradients near the surface are markedly enhanced. It is noticed that as natural convection effects are promoted, the greater portion of the sphere's surface experiences enhanced heat transfer rates. Given a Rayleigh number, the contours of the azimuthal velocity exhibit a nearly vertical equally-spaced pattern suggesting that solid-body rotation for high rotational Reynolds numbers. However, as the natural convection effects are enhanced, the contours become more slanted. The variation of the mean Nusselt number with the Reynolds and Rayleigh numbers is also quantified.

Khodadadi, J.M.; Li, W.; Shi, X.

1999-07-01T23:59:59.000Z

68

Atmospheric Radiation Measurement Convective and Orographically...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

of precipitation. These data will be combined with coincident radar, aircraft, and satellite data to improve how clouds and precipitation in low-mountain regions are...

69

ARM - Midlatitude Continental Convective Clouds  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

Convective processes play a critical role in the Earth's energy balance through the redistribution of heat and moisture in the atmosphere and their link to the hydrological cycle. Accurate representation of convective processes in numerical models is vital towards improving current and future simulations of Earths climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales important to convective processes and therefore must turn to parameterization schemes to represent these processes. In turn, parameterization schemes in cloud-resolving models need to be evaluated for their generality and application to a variety of atmospheric conditions. Data from field campaigns with appropriate forcing descriptors have been traditionally used by modelers for evaluating and improving parameterization schemes.

Jensen, Mike; Bartholomew, Mary Jane; Genio, Anthony Del; Giangrande, Scott; Kollias, Pavlos

70

Data assimilation for stratified convection  

E-Print Network [OSTI]

We show how the 3DVAR data assimilation methodology can be used in the astrophysical context of a two-dimensional convection flow. We study the way this variational approach finds best estimates of the current state of the flow from a weighted average of model states and observations. We use numerical simulations to generate synthetic observations of a vertical two-dimensional slice of the outer part of the solar convection zone for varying noise levels and implement 3DVAR when the covariance matrices are scalar. Our simulation results demonstrate the capability of 3DVAR to produce error estimates of system states between up to tree orders of magnitude below the original noise level present in the observations. This work exemplifies the importance of applying data assimilation techniques in simulations of the stratified convection.

Svedin, Andreas; Brandenburg, Axel

2013-01-01T23:59:59.000Z

71

Title: Radar-observed convective characteristics during TWP-ICE  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Title: Radar-observed convective characteristics during TWP-ICE Title: Radar-observed convective characteristics during TWP-ICE Schumacher, Courtney Texas A&M University Houze, Robert University of Washington May, Peter Bureau or Meteorology Research Centre Frederick, Kaycee Cetrone, Jasmine Vallgren, Andreas Category: Field Campaigns This poster will describe the radar dataset obtained in the Tropical Warm Pool International Cloud Experiment (TWP-ICE), which is to take place 20 January - 14 February 2006 in the vicinity of Darwin, Australia. We will describe the convective systems observed during the project by two scanning C-band Doppler radars, one of which will provide dual-polarization measurements, and ARM's vertically pointing cloud radar and lidar installations. In addition, we will discuss the potential for combining

72

GAMS program used to estimate capacity with the hyperbolic graph efficiency measure, with variable returns to scale and undesirable outputs.  

E-Print Network [OSTI]

. "Estimating Capacity and Efficiency in Fisheries with Undesirable Outputs." VIMS Marine resource Report N(obs) weights gamma(obs,var) ; POSITIVE Variable weight, gamma; EQUATIONS CONSTR1(GOUTPUT, OBS) DEA constraint

73

RADIAL STELLAR PULSATION AND THREE-DIMENSIONAL CONVECTION. II. TWO-DIMENSIONAL CONVECTION IN FULL AMPLITUDE RADIAL PULSATION  

SciTech Connect (OSTI)

We have developed a three-dimensional radiation hydrodynamics code to simulate the interaction of convection and radial pulsation in classical variable stars. One key goal is the ability to carry these simulations to full amplitude in order to compare them with observed light curves. Previous multi-dimensional calculations were prevented from reaching full amplitude because of drift in the radial coordinate system, due to the algorithm defining radial movement of the coordinate system during the pulsation cycle. We have removed this difficulty by defining our radial coordinate flow algorithm to require that the mass in a spherical shell remain constant for every time step throughout the pulsation cycle. We have used our new code to perform two-dimensional (2D) simulations of the interaction of radial pulsation and convection. We have made comparisons between light curves from our 2D convective simulations with observed light curves and find that our 2D simulated light curves are better able to match the observed light curve shape near the red edge of the RR Lyrae instability strip than light curves from previous one-dimensional time-dependent convective models.

Geroux, Chris M.; Deupree, Robert G., E-mail: geroux@astro.ex.ac.uk [Institute for Computational Astrophysics and Department of Astronomy and Physics, Saint Mary's University, Halifax, NS B3H 3C3 (Canada)

2013-07-10T23:59:59.000Z

74

variability temperature  

E-Print Network [OSTI]

related relative remote resolution results sampling ships studies validation weather world approach balance benguela biases buoyancy cod comparisons convection cooling energy error estimation fluctuations pacificocean phase plankton predictability present principal shelf shift simulated southwest statistics

75

A transilient matrix for moist convection  

SciTech Connect (OSTI)

A method is introduced for diagnosing a transilient matrix for moist convection. This transilient matrix quantifies the nonlocal transport of air by convective eddies: for every height z, it gives the distribution of starting heights z{prime} for the eddies that arrive at z. In a cloud-resolving simulation of deep convection, the transilient matrix shows that two-thirds of the subcloud air convecting into the free troposphere originates from within 100 m of the surface. This finding clarifies which initial height to use when calculating convective available potential energy from soundings of the tropical troposphere.

Romps, D.; Kuang, Z.

2011-08-15T23:59:59.000Z

76

Aircraft Observations of Convective Systems in the Indian Ocean [EVS Event]  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Aircraft Observations of Convective Systems in the Indian Ocean Aircraft Observations of Convective Systems in the Indian Ocean August 23, 2013 Speaker: Bradley Nicholas Guy National Research Council Postdoctoral Fellow NOAA National Severe Storms Laboratory Date: Friday, August 23, 2013 Time: 11:00 a.m. Location: Argonne National Laboratory TCS Building 240 Room 4301 In the DYNAMO (Dynamics of the Madden-Julian Oscillation) field experiment, a large number of measurement platforms were deployed to study environmental and convective cloud system characteristics of the Madden-Julian Oscillation (MJO) initiation region in the Indian Ocean. A mobile platform, the NOAA P-3 instrumented aircraft, sampled intense convective cloud systems, along with the surrounding environment. This presentation will explore the characteristics of mesoscale convective

77

The Relationship between Height and Precipitation Characteristics of Summertime Convective Cells in South Florida  

Science Journals Connector (OSTI)

Radar volume scan studies employed two radars simultaneously to measure heights and other echo characteristics of convective cells. Maps produced from the date were used to identify and track cells, whose properties were then related to one ...

A. Gagin; D. Rosenfeld; R. E. López

1985-01-01T23:59:59.000Z

78

On free convection heat transfer with well defined boundary conditions  

SciTech Connect (OSTI)

The scaling of free convection heat transfer is investigated. The non-dimensional groups for Boussinesq and fully compressible variable property free convection, driven by isothermal surfaces, are derived using a previously published novel method of dimensional analysis. Both flows are described by a different set of groups. The applicability of each flow description is experimentally investigated for the case of the isothermal horizontal cylinder in an air-filled isothermal enclosure. The approach taken to the boundary conditions differs from that of previous investigations. Here, it is argued that the best definition of the boundary conditions is achieved for heat exchange between the cylinder and the enclosure rather than the cylinder and an arbitrarily chosen fluid region. The enclosure temperature is shown both analytically and experimentally to affect the Nusselt number. The previously published view that the Boussinesq approximation has only a limited range of application is confirmed, and the groups derived for variable property compressible free convection are demonstrated to be correct experimentally. A new correlation for horizontal cylinder Nusselt number prediction is presented.

Davies, M.R.D.; Newport, D.T.; Dalton, T.M.

1999-07-01T23:59:59.000Z

79

REGIONAL VARIABILITY IN TROPICAL CONVECTION: OBSERVATIONS FROM TRMM  

E-Print Network [OSTI]

and longitude. The reflectivity histograms and ice water contents were then combined with LIS lightning flash structure histograms, and lightning flash density data reveal that 1) relative to tropical continental characteristics of precipitation vertical structure and associated lightning flash density. In general

Rutledge, Steven

80

Convective cell development and propagation in a mesoscale convective complex  

E-Print Network [OSTI]

~ , National Fisheries University of Pusan Chairman of Advisory Committee: Dr ~ Kennth CD Brundidge A case study was made of the mesoscale convective complex (MCC) which occurred over southern Oklahoma and northern Texas on 27 May 1981. This storm moved... in an east-southeasterly direction and during much of its lifetime was observable by radars at Oklahoma City, OK and Stephenville, TX. It was found that the direction of cell (VIP level 3 or more reflectivity) propagation was somewhat erratic...

Ahn, Yoo-Shin

2012-06-07T23:59:59.000Z

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


81

Properties of tropical convection observed by ARM millimeter-radars  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Properties of tropical convection observed by ARM millimeter-radars Properties of tropical convection observed by ARM millimeter-radars Haynes, John Colorado State University Stephens, Graeme Colorado State University Category: Cloud Properties The results of an analysis of tropical cloud systems observed from a variety of vertically pointing radar systems are described. In particular, observations taken during five years of operation of the ARM millimeter wavelength radar system (MMCR) at Manus Island in the Tropical West Pacific region are characterized into cloud classes according to the radar reflectivity structures of these cloud systems, associated rainfall, and surface radiative properties. These observations of cloud properties are composited with respect to various phases of the Madden Julian Oscillation, which is a dominant mode of variability at Manus Island. A method of better

82

Performance Variability  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Variability Variability of Highly Parallel Architectures William T.C. Kramer 1 and Clint Ryan 2 1 Department of Computing Sciences, University of California at Berkeley and the National Energy Research Scientific Computing Center, Lawrence Berkeley National Laboratory 2 Department of Computing Sciences, University of California at Berkeley Abstract. The design and evaluation of high performance computers has concentrated on increasing computational speed for applications. This performance is often measured on a well configured dedicated sys- tem to show the best case. In the real environment, resources are not always dedicated to a single task, and systems run tasks that may influ- ence each other, so run times vary, sometimes to an unreasonably large extent. This paper explores the amount of variation seen across four large distributed memory systems in a systematic manner. It then

83

The structure of the solar convective overshooting zone  

Science Journals Connector (OSTI)

......turbulent kinetic energy fluxes , and super-adiabatic...convection model of the solar convection envelope...the convective energy flux becomes negative...the base of the solar convection zone...that convective energy transfer is very...distance. In the solar atmosphere, the...the National Key Project through grant......

D.R. Xiong; L. Deng

2001-11-11T23:59:59.000Z

84

Measurement of charged-particle event shape variables in inclusive ?(s)=7??TeV proton-proton interactions with the ATLAS detector  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

The measurement of charged-particle event shape variables is presented in inclusive inelastic pp collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the LHC. The observables studied are the transverse thrust, thrust minor, and transverse sphericity, each defined using the final-state charged particles’ momentum components perpendicular to the beam direction. Events with at least six charged particles are selected by a minimum-bias trigger. In addition to the differential distributions, the evolution of each event shape variable as a function of the leading charged-particle transverse momentum, charged-particle multiplicity, and summed transverse momentum is presented. Predictions from several Monte Carlo models show significant deviations from data.

Aad, G.; Abajyan, T.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdelalim, A. A.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Acerbi, E.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Addy, T. N.; Adelman, J.; Adomeit, S.; Adragna, P.; Adye, T.; Aefsky, S.; Aguilar-Saavedra, J. A.; Agustoni, M.; Aharrouche, M.; Ahlen, S. P.; Ahles, F.; Ahmad, A.; Ahsan, M.; Aielli, G.; Akdogan, T.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Alam, M. S.; Alam, M. A.; Albert, J.; Albrand, S.; Aleksa, M.; Aleksandrov, I. N.; Alessandria, F.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Allbrooke, B. M. M.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alonso, F.; Alvarez Gonzalez, B.; Alviggi, M. G.; Amako, K.; Amelung, C.; Ammosov, V. V.; Amorim, A.; Amram, N.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Anduaga, X. S.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoki, M.; Aoun, S.; Aperio Bella, L.; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Arfaoui, S.; Arguin, J-F.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnal, V.; Arnault, C.; Artamonov, A.; Artoni, G.; Arutinov, D.; Asai, S.; Asfandiyarov, R.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astbury, A.; Atkinson, M.; Aubert, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Avolio, G.; Avramidou, R.; Axen, D.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Baccaglioni, G.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Badescu, E.; Bagnaia, P.; Bahinipati, S.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, M. D.; Baker, S.; Banas, E.; Banerjee, P.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barbaro Galtieri, A.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Barrillon, P.; Bartoldus, R.; Barton, A. E.; Bartsch, V.; Basye, A.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battaglia, A.; Battistin, M.; Bauer, F.; Bawa, H. S.; Beale, S.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Becker, A. K.; Becker, S.; Beckingham, M.; Becks, K. H.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Begel, M.; Behar Harpaz, S.; Beimforde, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellina, F.; Bellomo, M.; Belloni, A.; Beloborodova, O.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez Garcia, J. A.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernat, P.; Bernhard, R.; Bernius, C.; Berry, T.; Bertella, C.; Bertin, A.; Bertolucci, F.; Besana, M. I.; Besjes, G. J.; Besson, N.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Bierwagen, K.; Biesiada, J.; Biglietti, M.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biscarat, C.; Bittner, B.; Black, K. M.; Blair, R. E.; Blanchard, J.-B.; Blanchot, G.; Blazek, T.; Blocker, C.; Blocki, J.; Blondel, A.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. B.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boelaert, N.; Bogaerts, J. A.; Bogdanchikov, A.; Bogouch, A.; Bohm, C.; Bohm, J.; Boisvert, V.; Bold, T.; Boldea, V.; Bolnet, N. M.; Bomben, M.; Bona, M.; Boonekamp, M.; Booth, C. N.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borjanovic, I.; Borri, M.; Borroni, S.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozovic-Jelisavcic, I.; Bracinik, J.; Branchini, P.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brazzale, S. F.; Brelier, B.; Bremer, J.; Brendlinger, K.; Brenner, R.; Bressler, S.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Broggi, F.; Bromberg, C.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brown, G.; Brown, H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Buanes, T.; Buat, Q.; Bucci, F.; Buchanan, J.; Buchholz, P.; Buckingham, R. M.

2013-08-01T23:59:59.000Z

85

Technical Sessions Parameterization of Convective Clouds, Mesoscale...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

and Convective-Generated Clouds W. R. Cotton Department of Atmospheric Science Colorado State University Fort Collins, CO 80523 This presentation is a summary of research...

86

M. Bahrami ENSC 388 (F09) Forced Convection Heat Transfer 1 Forced Convection Heat Transfer  

E-Print Network [OSTI]

1 Forced Convection Heat Transfer Convection is the mechanism of heat transfer through a fluid / The convective heat transfer coefficient h strongly depends on the fluid properties and roughness of the solid. As a result, the heat transfer from the solid surface to the fluid layer adjacent to the surface

Bahrami, Majid

87

Slide 1Falk Herwig7 Aug 2006 Convective and non-convective mixing  

E-Print Network [OSTI]

Slide 1Falk Herwig7 Aug 2006 Convective and non-convective mixing in AGB stars Falk Herwig and Bernd Freytag Los Alamos National Laboratory Theoretical Astrophysics Group #12;Slide 2Falk Herwig7 Aug envelope models for sun-like stars #12;Slide 3Falk Herwig7 Aug 2006 3D hydro simulations of AGB convective

Herwig, Falk

88

Measurable energy savings of installing variable frequency drives for cooling towers’ fans, compared to dual speed motors  

Science Journals Connector (OSTI)

Abstract In recent years the building management system (BMS) controllers have been used to control the operation of heating, ventilation, and air conditioning system in addition to lighting and some electrical equipment in order to save energy. In the water cooled system, the BMS controls the operation process of the cooling towers (CTs) fans of dual speed motors to maintain a constant leaving water temperature for different cooling loads and different ambient wet bulb temperature (WBT). This paper presents the effect of installing variable frequency drives (VFDs) for \\{CTs\\} fans in Kuwait during summer season on energy savings compared to dual speed control. The results have shown that with VFD mode, the reduction in water consumption was over 13% compared to the commonly used dual speed mode. More importantly, the combined power for the chillers and the \\{CTs\\} fans for the same amount of cooling produced were reduced by 5.8% in the VFD mode.

E. Al-Bassam; R. Alasseri

2013-01-01T23:59:59.000Z

89

The development and application of a questionnaire designed to measure pre-existing, process, and outcome variables in the productivity measurement and enhancement  

E-Print Network [OSTI]

measurement: 1. Takes guesswork out of observation about productivity 2. Assists in the efficient conduct of operations. 3. Facilitates communication between members of the organization. 4. Aids in evaluating progress toward improving productivity. 5...

Decuir, Arlette Desha

1997-01-01T23:59:59.000Z

90

Realistic Solar Convection Simulations Robert F. Stein  

E-Print Network [OSTI]

Realistic Solar Convection Simulations Robert F. Stein Michigan State University, East Lansing, MIAFG, Juliane Maries Vej 30, Dk­2100 Copenhagen �, Denmark Abstract. We report on realistic simulations of solar and intensity spectra, the p­mode excitation rate, and the depth of the convection zone. We describe how solar

Stein, Robert

91

ARM - Field Campaign - ARM Support for the Plains Elevated Convection...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

convection, and (d) this lack of understanding greatly hampers the ability of numerical weather and climate models to simulate nocturnal convection well which leads to...

92

ARM - Field Campaign - Midlatitude Continental Convective Clouds Experiment  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Experiment Experiment (MC3E): Multi-Frequency Profilers Related Campaigns Midlatitude Continental Convective Clouds Experiment (MC3E) 2011.04.22, Jensen, SGP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers 2011.04.22 - 2011.06.06 Lead Scientist : Christopher Williams For data sets, see below. Description The scientific focus was to study the vertical structure of precipitation in a vertical column over the SGP Central Facility. These multi-frequency profiler observations enabled directly measuring the vertical air motion and retrieving the raindrop size distributions from near the surface to just under the freezing level. These profilers were deployed during MC3E

93

Convective Cooling and Passive Stack Improvements in Motors (Presentation)  

SciTech Connect (OSTI)

This presentation discusses current research at NREL in convective cooling and passive stack improvements in motors.

Bennion, K.

2014-06-01T23:59:59.000Z

94

Heat Transport by Turbulent Rayleigh-Benard Convection  

SciTech Connect (OSTI)

We have developed a research program dedicated to the quantitative laboratory study of turbulent convection.

None

2008-10-03T23:59:59.000Z

95

A FULL SCALE ROOM FOR THE EXPERIMENTAL STUDY OF INTERIOR BUILDING CONVECTIVE HEAT TRANSFER  

E-Print Network [OSTI]

air flow measurement. A water source heat pump provided chilled water to a fan-coil unit which in turn on volumetric air flow measurement and an overall room heat balance. Analysis was directed at results fromA FULL SCALE ROOM FOR THE EXPERIMENTAL STUDY OF INTERIOR BUILDING CONVECTIVE HEAT TRANSFER: DESIGN

96

Steady, three-dimensional, internally heated convection  

SciTech Connect (OSTI)

Numerical calculations have been carried out of steady, symmetric, three-dimensional modes of convection in internally heated, infinite Prandtl number, Boussinesq fluids at a Rayleigh number of 1.4[times]10[sup 4] in a spherical shell with inner/outer radius of 0.55 and in a 3[times]3[times]1 rectangular box. Multiple patterns of convection occur in both geometries. In the Cartesian geometry the patterns are dominated by cylindrical cold downflows and a broad hot upwelling. In the spherical geometry the patterns consist of cylindrical cold downwellings centered either at the vertices of a tetrahedron or the centers of the faces of a cube. The cold downflow cylinders are immersed in a background of upwelling within which there are cylindrical hot concentrations (plumes) and hot halos around the downflows. The forced hot upflow return plumes of internally heated spherical convection are fundamentally different from the buoyancy-driven plumes of heated from below convection.

Schubert, G. (Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90024 (United States)); Glatzmaier, G.A.; Travis, B. (Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

1993-08-01T23:59:59.000Z

97

Modeling convection in the Greenland Sea  

E-Print Network [OSTI]

A detailed examination of the development of a deep convection event observed in the Greenland Sea in 1988-89 is carried out through a combination of modeling, scale estimates, and data analysis. We develop a prognostic ...

Bhushan, Vikas

1998-01-01T23:59:59.000Z

98

Observations on Buoyant Convection in Reverse Osmosis  

Science Journals Connector (OSTI)

Observations on Buoyant Convection in Reverse Osmosis ... Buoyancy Effects in Dead-End Reverse Osmosis:? Visualization by Holographic Interferometry ... Buoyancy Effects in Dead-End Reverse Osmosis:? Visualization by Holographic Interferometry ...

Terry J. Hendricks; Jean F. Macquin; Forman A. Williams

1972-05-01T23:59:59.000Z

99

Circulation and convection in the Irminger Sea  

E-Print Network [OSTI]

Aspects of the circulation and convection in the Irminger Sea are investigated using a variety of in-situ, satellite, and atmospheric reanalysis products. Westerly Greenland tip jet events are intense, small-scale wind ...

Våge, Kjetil

2010-01-01T23:59:59.000Z

100

CATHARE calculations of Phenix ultimate natural convection test  

SciTech Connect (OSTI)

The Phenix Sodium cooled Fast Reactor (SFR) started operation in 1973 and it was stopped in 2009. Before the reactor was definitively shutdown, in order to collect experimental data for code assessments in the frame of Generation IV an intensive program of ultimate tests was set up. Among these ultimate experiments, two thermal hydraulic tests were performed: an asymmetrical test consisting in a trip on one secondary pump and a natural convection test in the primary circuit. The natural convection test has been used for an international benchmark on system codes in the frame of the IAEA. The CATHARE code - initially developed for water cooled reactors and now extended for safety analyses for other kinds of reactors, including Sodium Fast Reactor - was used by CEA for this benchmark. The paper reminds briefly the Phenix reactor with the main physical parameters and the instrumentation used during the natural convection test. Main test results are also briefly reminded including the evolution of the core and the heat exchangers inlet and outlet temperatures, and some local temperature measurements. The main developments to perform CATHARE SFR computations and the strategy of system code assessment are presented. Then the CATHARE modelling of Phenix reactor is depicted and the various assumptions are pointed out. CATHARE encountered no problem to predict the initial nominal state. Afterwards, the whole transient scenario is calculated and CATHARE calculations are compared to the Phenix measurements. The global trend is rather well predicted by the CATHARE code. Nevertheless, due to complex flow phenomena occurring in large plena and components, the system code encountered physical limitations, leading to remaining discrepancies between code prediction and plant data. Various sensitivity calculations are presented and they bring partial answers. Additional analyses are in progress to understand more deeply the complex 3D phenomena involved during the different phases of the natural convection test. Additional work for coupling CATHARE system code and TRIO-U CFD code is in progress and will bring useful information to better understand the physical phenomena involved during the natural convection test and to improve system modeling for future SFR safety analysis. (authors)

Pialla, D.; Tenchine, D. [CEA, DEN, DM2S/STMF, Grenoble, F-17 rue des Martyrs, 38000 Grenoble (France); Gauthe, P. [CEA, DEN, DER/SESI, Cadarache, F-13108 Saint Paul lez Durance (France); Vasile, A. [CEA, DEN, DER, Cadarache, F-13108 Saint Paul lez Durance (France)

2012-07-01T23:59:59.000Z

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


101

ARM - Midlatitude Continental Convective Clouds Microwave Radiometer Profiler (jensen-mwr)  

SciTech Connect (OSTI)

A major component of the Mid-latitude Continental Convective Clouds Experiment (MC3E) field campaign was the deployment of an enhanced radiosonde array designed to capture the vertical profile of atmospheric state variables (pressure, temperature, humidity wind speed and wind direction) for the purpose of deriving the large-scale forcing for use in modeling studies. The radiosonde array included six sites (enhanced Central Facility [CF-1] plus five new sites) launching radiosondes at 3-6 hour sampling intervals. The network will cover an area of approximately (300)2 km2 with five outer sounding launch sites and one central launch location. The five outer sounding launch sites are: S01 Pratt, KS [ 37.7oN, 98.75oW]; S02 Chanute, KS [37.674, 95.488]; S03 Vici, Oklahoma [36.071, -99.204]; S04 Morris, Oklahoma [35.687, -95.856]; and S05 Purcell, Oklahoma [34.985, -97.522]. Soundings from the SGP Central Facility during MC3E can be retrieved from the regular ARM archive. During routine MC3E operations 4 radiosondes were launched from each of these sites (approx. 0130, 0730, 1330 and 1930 UTC). On days that were forecast to be convective up to four additional launches were launched at each site (approx. 0430, 1030, 1630, 2230 UTC). There were a total of approximately 14 of these high frequency launch days over the course of the experiment. These files contain brightness temperatures observed at Purcell during MC3E. The measurements were made with a 5 channel (22.235, 23.035, 23.835, 26.235, 30.000GHz) microwave radiometer at one minute intervals. The results have been separated into daily files and the day of observations is indicated in the file name. All observations were zenith pointing. Included in the files are the time variables base_time and time_offset. These follow the ARM time conventions. Base_time is the number seconds since January 1, 1970 at 00:00:00 for the first data point of the file and time_offset is the offset in seconds from base_time.

Jensen, Mike

2012-02-01T23:59:59.000Z

102

ARM - Midlatitude Continental Convective Clouds - Ultra High Sensitivity Aerosol Spectrometer(tomlinson-uhsas)  

SciTech Connect (OSTI)

Ultra High Sensitivity Aerosol Spectrometer (UHSASA) A major component of the Mid-latitude Continental Convective Clouds Experiment (MC3E) field campaign was the deployment of an enhanced radiosonde array designed to capture the vertical profile of atmospheric state variables (pressure, temperature, humidity wind speed and wind direction) for the purpose of deriving the large-scale forcing for use in modeling studies. The radiosonde array included six sites (enhanced Central Facility [CF-1] plus five new sites) launching radiosondes at 3-6 hour sampling intervals. The network will cover an area of approximately (300)2 km2 with five outer sounding launch sites and one central launch location. The five outer sounding launch sites are: S01 Pratt, KS [ 37.7oN, 98.75oW]; S02 Chanute, KS [37.674, 95.488]; S03 Vici, Oklahoma [36.071, -99.204]; S04 Morris, Oklahoma [35.687, -95.856]; and S05 Purcell, Oklahoma [34.985, -97.522]. Soundings from the SGP Central Facility during MC3E can be retrieved from the regular ARM archive. During routine MC3E operations 4 radiosondes were launched from each of these sites (approx. 0130, 0730, 1330 and 1930 UTC). On days that were forecast to be convective up to four additional launches were launched at each site (approx. 0430, 1030, 1630, 2230 UTC). There were a total of approximately 14 of these high frequency launch days over the course of the experiment. These files contain brightness temperatures observed at Purcell during MC3E. The measurements were made with a 5 channel (22.235, 23.035, 23.835, 26.235, 30.000GHz) microwave radiometer at one minute intervals. The results have been separated into daily files and the day of observations is indicated in the file name. All observations were zenith pointing. Included in the files are the time variables base_time and time_offset. These follow the ARM time conventions. Base_time is the number seconds since January 1, 1970 at 00:00:00 for the first data point of the file and time_offset is the offset in seconds from base_time.

Tomlinson, Jason; Jensen, Mike

2012-02-28T23:59:59.000Z

103

ARM - Midlatitude Continental Convective Clouds (jensen-sonde)  

SciTech Connect (OSTI)

A major component of the Mid-latitude Continental Convective Clouds Experiment (MC3E) field campaign was the deployment of an enhanced radiosonde array designed to capture the vertical profile of atmospheric state variables (pressure, temperature, humidity wind speed and wind direction) for the purpose of deriving the large-scale forcing for use in modeling studies. The radiosonde array included six sites (enhanced Central Facility [CF-1] plus five new sites) launching radiosondes at 3-6 hour sampling intervals. The network will cover an area of approximately (300)2 km2 with five outer sounding launch sites and one central launch location. The five outer sounding launch sites are: S01 Pratt, KS [ 37.7oN, 98.75oW]; S02 Chanute, KS [37.674, 95.488]; S03 Vici, Oklahoma [36.071, -99.204]; S04 Morris, Oklahoma [35.687, -95.856]; and S05 Purcell, Oklahoma [34.985, -97.522]. Soundings from the SGP Central Facility during MC3E can be retrieved from the regular ARM archive. During routine MC3E operations 4 radiosondes were launched from each of these sites (approx. 0130, 0730, 1330 and 1930 UTC). On days that were forecast to be convective up to four additional launches were launched at each site (approx. 0430, 1030, 1630, 2230 UTC). There were a total of approximately 14 of these high frequency launch days over the course of the experiment.

Jensen, Mike; Comstock, Jennifer; Genio, Anthony Del; Giangrande, Scott; Kollias, Pavlos

2012-01-19T23:59:59.000Z

104

Convection automated logic oven control  

SciTech Connect (OSTI)

For the past few years, there has been a greater push to bring more automation to the cooling process. There have been attempts at automated cooking using a wide range of sensors and procedures, but with limited success. The authors have the answer to the automated cooking process; this patented technology is called Convection AutoLogic (CAL). The beauty of the technology is that it requires no extra hardware for the existing oven system. They use the existing temperature probe, whether it is an RTD, thermocouple, or thermistor. This means that the manufacturer does not have to be burdened with extra costs associated with automated cooking in comparison to standard ovens. The only change to the oven is the program in the central processing unit (CPU) on the board. As for its operation, when the user places the food into the oven, he or she is required to select a category (e.g., beef, poultry, or casseroles) and then simply press the start button. The CAL program then begins its cooking program. It first looks at the ambient oven temperature to see if it is a cold, warm, or hot start. CAL stores this data and then begins to look at the food`s thermal footprint. After CAL has properly detected this thermal footprint, it can calculate the time and temperature at which the food needs to be cooked. CAL then sets up these factors for the cooking stage of the program and, when the food has finished cooking, the oven is turned off automatically. The total time for this entire process is the same as the standard cooking time the user would normally set. The CAL program can also compensate for varying line voltages and detect when the oven door is opened. With all of these varying factors being monitored, CAL can produce a perfectly cooked item with minimal user input.

Boyer, M.A.; Eke, K.I. [Apollo U.S.A. Inc., Orlando, FL (United States)] [Apollo U.S.A. Inc., Orlando, FL (United States)

1998-03-01T23:59:59.000Z

105

Characterization of Fuego for laminar and turbulent natural convection heat transfer.  

SciTech Connect (OSTI)

A computational fluid dynamics (CFD) analysis is conducted for internal natural convection heat transfer using the low Mach number code Fuego. The flow conditions under investigation are primarily laminar, transitional, or low-intensity level turbulent flows. In the case of turbulent boundary layers at low-level turbulence or transitional Reynolds numbers, the use of standard wall functions no longer applies, in general, for wall-bounded flows. One must integrate all the way to the wall in order to account for gradients in the dependent variables in the viscous sublayer. Fuego provides two turbulence models in which resolution of the near-wall region is appropriate. These models are the v2-f turbulence model and a Launder-Sharma, low-Reynolds number turbulence model. Two standard geometries are considered: the annulus formed between horizontal concentric cylinders and a square enclosure. Each geometry emphasizes wall shear flow and complexities associated with turbulent or near turbulent boundary layers in contact with a motionless core fluid. Overall, the Fuego simulations for both laminar and turbulent flows compared well to measured data, for both geometries under investigation, and to a widely accepted commercial CFD code (FLUENT).

Francis, Nicholas Donald, Jr. (,; .)

2005-08-01T23:59:59.000Z

106

Triggering Deep Convection with a Probabilistic Plume Model  

Science Journals Connector (OSTI)

A model unifying the representation of the planetary boundary layer and dry, shallow, and deep convection, the probabilistic plume model (PPM), is presented. Its capacity to reproduce the triggering of deep convection over land is analyzed in ...

Fabio D’Andrea; Pierre Gentine; Alan K. Betts; Benjamin R. Lintner

2014-11-01T23:59:59.000Z

107

Heat Transfer by Free Convection in a Liquid Metal  

Science Journals Connector (OSTI)

19 December 1961 research-article Heat Transfer by Free Convection in a Liquid Metal F. J. Bayley...an experimental investigation of the free convection heat transfer process under the special conditions associated with...

1961-01-01T23:59:59.000Z

108

Structures and Dynamics of Quasi-2D Mesoscale Convective Systems  

Science Journals Connector (OSTI)

Recently, three distinct archetypes for midlatitude linear mesoscale convective systems (MCSs) have been identified. This article focuses on the fundamentals of two of these archetypes: convective lines with trailing stratiform (TS) precipitation ...

Matthew D. Parker; Richard H. Johnson

2004-03-01T23:59:59.000Z

109

Structure and evolution of a convective band MCS  

E-Print Network [OSTI]

The structure and evolution of the synoptic, mesoscale, and lightning characteristics of the 5 May 1993 non-squall line Mesoscale Convective System has been described. This storm was a long-lived Mesoscale Convective Complex. Its formation...

Valdes-Manzanilla, Arturo

2012-06-07T23:59:59.000Z

110

A Moisture-Stratiform Instability for Convectively Coupled Waves  

Science Journals Connector (OSTI)

A simple model of two vertical modes is constructed and analyzed to reveal the basic instability mechanisms of convectively coupled waves. The main novelty of this model is a convective parameterization based on the quasi-equilibrium concept and ...

Zhiming Kuang

2008-03-01T23:59:59.000Z

111

Radiative–Convective Equilibrium over a Land Surface  

Science Journals Connector (OSTI)

Radiative–convective equilibrium (RCE) describes an idealized state of the atmosphere in which the vertical temperature profile is determined by a balance between radiative and convective fluxes. While RCE has been applied extensively over oceans, ...

Nicolas Rochetin; Benjamin R. Lintner; Kirsten L. Findell; Adam H. Sobel; Pierre Gentine

2014-12-01T23:59:59.000Z

112

Non-Oberbeck-Boussinesq Effects in Gaseous Rayleigh-Bénard Convection  

Science Journals Connector (OSTI)

Non-Oberbeck-Boussinesq (NOB) effects are measured experimentally and calculated theoretically for strongly turbulent Rayleigh-Bénard convection of ethane gas under pressure where the material properties strongly depend on the temperature. Relative to the Oberbeck-Boussinesq case we find a decrease of the central temperature as compared to the arithmetic mean of the top- and bottom-plate temperature and an increase of the Nusselt number. Both effects are of opposite sign and greater magnitude than those for NOB convection in liquids like water.

Guenter Ahlers; Francisco Fontenele Araujo; Denis Funfschilling; Siegfried Grossmann; Detlef Lohse

2007-01-29T23:59:59.000Z

113

Non-Oberbeck-Boussinesq Effects in Gaseous Rayleigh-Benard Convection Guenter Ahlers,1  

E-Print Network [OSTI]

Non-Oberbeck-Boussinesq Effects in Gaseous Rayleigh-Be´nard Convection Guenter Ahlers,1 Francisco December 2006; published 29 January 2007) Non-Oberbeck-Boussinesq (NOB) effects are measured experimentally where the material properties strongly depend on the temperature. Relative to the Oberbeck-Boussinesq

Ahlers, Guenter

114

Convection in Arc Weld Pools Electromagnetic and surface tension forces are shown to  

E-Print Network [OSTI]

Convection in Arc Weld Pools Electromagnetic and surface tension forces are shown to dominate flow tension forces. It is shown that the electromag- netic and surface tension forces domi- nate the flow by experimental measurements of segrega- tion in the weld pool. It is also shown that the surface tension driven

Eagar, Thomas W.

115

Noise-Induced Intermittency in a Convecting Dilute Solution of He3 in Superfluid He4  

Science Journals Connector (OSTI)

Measurements on a convecting dilute He3-superfluid-He4 solution show a transition from periodic to chaotic behavior via intermittency. In a region near but below the onset of intermittency, injection of external noise greater than some threshold value induces chaos.

H. Haucke; R. E. Ecke; Y. Maeno; J. C. Wheatley

1984-11-26T23:59:59.000Z

116

Inverse natural convection problem of estimating wall heat flux using a moving sensor  

SciTech Connect (OSTI)

Inverse heat transfer problems have many applications in various branch of science and engineering. Here, the inverse problem of determining heat flux at the bottom wall of a two-dimensional cavity from temperature measurement in the domain is considered. The Boussinesq equation is used to model the natural convection induced by the wall heat flux. The inverse natural convection problem is posed as a minimization problem of the performance function, which is the sum of square residuals between calculated and observed temperature, by means of a conjugate gradient method. Instead of employing several fixed sensors, a single sensor is used which is moving at a given frequency over the bottom wall. The present method solves the inverse natural convection problem accurately without a priori information about the unknown function to be estimated.

Park, H.M.; Chung, O.Y.

1999-11-01T23:59:59.000Z

117

On the Features of Radiative and Convective Regimes Under the Cumulus Cloudiness  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

On the Features of Radiative and Convective Regimes On the Features of Radiative and Convective Regimes Under the Cumulus Cloudiness B. M. Koprov, V. M. Koprov, G. S. Golitsyn A.M. Oboukhov Institute of Atmospheric Physics Moscow, Russia E. N. Kadygrov, A. V. Koldaev Central Aerological Observatory Dolgoprudny, Russia Introduction The study of instant temperature field transformation, convective and radiative regime perturbation within the layer of 0 to 650 m was fulfilled as caused by cloud modulation of solar radiation flux. It was made within the scope of Zvenigorod Atmospheric Radiation Measurement (ARM) experiments in 2001 and 2002. Instrumentation The equipment used: 1. Microwave temperature profiler designed in Central Aerological Observatory (CAO) and manufactured by Russian company ATTEX (Kadygrov and Pick 1998).

118

Monitoring variability of multivariate processes  

Science Journals Connector (OSTI)

The paper focuses on determining changes in process variability of multivariate processes. The problem is compounded by the fact that any of the elements in the variance-covariance matrix of variables could change, leading to a change in the process variability. While it may not be feasible to maintain individual control charts for each element of the variance-covariance matrix, some aggregate measure of the variability criteria could be monitored to initially determine if a change has occurred in the process variability. A couple of aggregate measures are proposed and the performance of these suggested measures is explored through a simulation procedure. Compared to the traditional method, which monitors the determinant of the variance-covariance matrix, these alternatives perform well. The performance measure used is the mean time to first detection of a change in the process variability.

Amitava Mitra; Mark Clark

2014-01-01T23:59:59.000Z

119

The Convective Instability Pathway to Warm Season Drought in Texas. Part II: Free-Tropospheric Modulation of Convective Inhibition  

Science Journals Connector (OSTI)

This study is concerned with the modulation by convective instability of summertime precipitation in Texas as a mechanism for maintaining or enhancing drought. The important role of convective inhibition (CIN), its dependence on the temperature ...

Boksoon Myoung; John W. Nielsen-Gammon

2010-09-01T23:59:59.000Z

120

Turbulent convection in liquid metal with and without rotation  

E-Print Network [OSTI]

is the efficiency of convective heat transfer (Nu). In general, we find that the convective behavior of liquid metal=ðkT�, where q is total heat flux and k is the fluid's thermal conductivity. Heat flux q is total heat power P by turbulent, rotating convection in liquid metal. Liquid metals are peculiar in that they diffuse heat more

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


121

Realistic Solar Surface Convection Simulations Robert F. Stein  

E-Print Network [OSTI]

Realistic Solar Surface Convection Simulations Robert F. Stein Michigan State University, East free simulations with re­ alistic physics of convection near the solar surface. We summarize solar convection is non­local. It is driven from a thin surface thermal boundary layer where radiative

Stein, Robert

122

Testing turbulent convection theory in solar models – I. Structure of the solar convection zone  

Science Journals Connector (OSTI)

......outer envelope of the Sun, low-temperature opacities from Alexander...SSM. Fig. 9 shows the distribution of the temperature gradient in the solar...on the structure of the Sun, especially the temperature gradient in the convection......

Y. Li; J. Y. Yang

2007-02-11T23:59:59.000Z

123

The convective structures associated with cloud-to-ground lightning in TOGA COARE Mesoscale Convective Systems  

E-Print Network [OSTI]

indicate a pronounced difference between lightning producing and non-lightning producing cells. Lightning producing convective cells have higher radar reflectivity in the 5.0- 8.0 km layer, and a slower decrease with height, both observations indicating...

Restivo, Michael Edward

2012-06-07T23:59:59.000Z

124

Solar MagnetoConvection David J. Bercik  

E-Print Network [OSTI]

Solar Magneto­Convection David J. Bercik Dept. of Physics and Astronomy, Michigan State University, Michigan State University, East Lansing, MI 48824, U.S.A. š Ake Nordlund Theoretical Astrophysics Center, �ster Voldgade 3, 1350 Copenhagen K, Denmark Robert F. Stein Dept. of Physics and Astronomy, Michigan

Stein, Robert

125

Laminar boundary layers in convective heat transport  

E-Print Network [OSTI]

We study Rayleigh-Benard convection in the high-Rayleigh-number and high-Prandtl-number regime, i.e., we consider a fluid in a container that is exposed to strong heating of the bottom and cooling of the top plate in the absence of inertia effects. While the dynamics in the bulk are characterized by a chaotic convective heat flow, the boundary layers at the horizontal container plates are essentially conducting and thus the fluid is motionless. Consequently, the average temperature exhibits a linear profile in the boundary layers. In this article, we rigorously investigate the average temperature and oscillations in the boundary layer via local bounds on the temperature field. Moreover, we deduce that the temperature profile is indeed essentially linear close to the horizontal container plates. Our results are uniform in the system parameters (e.g. the Rayleigh number) up to logarithmic correction terms. An important tool in our analysis is a new Hardy-type estimate for the convecting velocity field, which can be used to control the fluid motion in the layer. The bounds on the temperature field are derived with the help of local maximal regularity estimates for convection-diffusion equations.

Christian Seis

2012-12-12T23:59:59.000Z

126

Mantle Convection with Strong Subduction Zones  

E-Print Network [OSTI]

of the oceanic lithosphere within a small region of a nite element grid. By imposing velocity boundary conditions thermal structure. To make the model dynamically consistent, we specify a rate for subduction that balances the energy budget for convection, which includes an expression for the energy needed to bend

Conrad, Clint

127

Measurements of Sea Surface Height Variability in the Eastern South Atlantic from Pressure Sensor-Equipped Inverted Echo Sounders: Baroclinic and Barotropic  

E-Print Network [OSTI]

Variability in sea surface height (SSH) can be decomposed into two contributions: one from changes in mass in the water column (barotropic) and the other from purely steric changes (baroclinic). Both contributions can be ...

Baker-Yeboah, Sheekela

128

Measurement  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

localization that limits the present measurements. The knowledge thus gained will have input not only to fusion research, but to may ques- tions of basic plasma physics....

129

Measurement  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

in the Department of Physics & Astronomy. Chapel Hill 2005 Approved: A. E. Champagne, Advisor J. C. Blackmon, Reader C. Iliadis, Reader ABSTRACT Ryan P. Fitzgerald: Measurement of...

130

EFFECTS OF ASYMMETRIC FLOWS IN SOLAR CONVECTION ON OSCILLATION MODES  

SciTech Connect (OSTI)

Many helioseismic measurements suffer from substantial systematic errors. A particularly frustrating one is that time-distance measurements suffer from a large center to limb effect which looks very similar to the finite light travel time, except that the magnitude depends on the observable used and can have the opposite sign. This has frustrated attempts to determine the deep meridional flow in the solar convection zone, with Zhao et al. applying an ad hoc correction with little physical basis to correct the data. In this Letter, we propose that part of this effect can be explained by the highly asymmetrical nature of the solar granulation which results in what appears to the oscillation modes as a net radial flow, thereby imparting a phase shift on the modes as a function of observing height and thus heliocentric angle.

Baldner, Charles S.; Schou, Jesper, E-mail: baldner@stanford.edu [W.W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States)

2012-11-20T23:59:59.000Z

131

Convective equilibrium and mixing-length theory for stellarator reactors  

SciTech Connect (OSTI)

In high ..beta.. stellarator and tokamak reactors, the plasma pressure gradient in some regions of the plasma may exceed the critical pressure gradient set by ballooning instabilities. In these regions, convective cells break out to enhance the transport. As a result, the pressure gradient can rise only slightly above the critical gradient and the plasma is in another state of equilibrium - ''convective equilibrium'' - in these regions. Although the convective transport cannot be calculated precisely, it is shown that the density and temperature profiles in the convective region can still be estimated. A simple mixing-length theory, similar to that used for convection in stellar interiors, is introduced in this paper to provide a qualitative description of the convective cells and to show that the convective transport is highly efficient. A numerical example for obtaining the density and temperature profiles in a stellarator reactor is given.

Ho, D.D.M.; Kulsrud, R.M.

1985-09-01T23:59:59.000Z

132

ON THE PENETRATION OF MERIDIONAL CIRCULATION BELOW THE SOLAR CONVECTION ZONE. II. MODELS WITH CONVECTION ZONE, THE TAYLOR-PROUDMAN CONSTRAINT, AND APPLICATIONS TO OTHER STARS  

SciTech Connect (OSTI)

The solar convection zone exhibits a strong level of differential rotation, whereby the rotation period of the polar regions is about 25%-30% longer than the equatorial regions. The Coriolis force associated with these zonal flows perpetually 'pumps' the convection zone fluid, and maintains a quasi-steady circulation, poleward near the surface. What is the influence of this meridional circulation on the underlying radiative zone, and in particular, does it provide a significant source of mixing between the two regions? In Paper I, we began to study this question by assuming a fixed meridional flow pattern in the convection zone and calculating its penetration depth into the radiative zone. We found that the amount of mixing caused depends very sensitively on the assumed flow structure near the radiative-convective interface. We continue this hydrodynamic study here by including a simple model for the convection zone 'pump', and calculating in a self-consistent manner the meridional flows generated in the whole Sun. We find that the global circulation timescale depends in a crucial way on two factors: the overall stratification of the radiative zone as measured by the square root of the Prandtl number times the ratio of the Brunt-Vaeisaelae frequency to the rotation rate, and, for weakly stratified systems, the presence or absence of stresses within the radiative zone capable of breaking the Taylor-Proudman constraint. We conclude by discussing the consequences of our findings for the solar interior and argue that a potentially important mechanism for mixing in young main-sequence stars has so far been neglected.

Garaud, P.; Acevedo Arreguin, L. [Department of Applied Mathematics and Statistics, Baskin School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States)

2009-10-10T23:59:59.000Z

133

Climate monitoring with Earth radiation budget measurements  

Science Journals Connector (OSTI)

The Earth Radiation Budget (ERB) and its geographical distribution is intimately linked with the earth’s climate and with the general circulation. We analyze 10 years of global Clouds and the Earth’s Radiant Energy System (CERES) measurements from 2000 to 2010 and 8 years of diurnally resolved Geostationary Earth Radiation Budget (GERB) from 2004 to 2011 to illustrate this link and to verify if we can detect climate variability or systematic change. In response to the diurnal wave of solar heating three tropical convection maxima exist over South America Africa and around Indonesia. The Indonesian convection maximum is unstable due to a lack of a stabilizing land mass; this is the root cause of the El Ni?o/La Ni?a inter-annual variation with a global pattern of teleconnected variations through the general Walker circulation. Since 2000 a change in global dynamics seems to have occurred. There was a general strengthening of La Ni?a coinciding with a ‘break in global temperature rise’ and with an ‘eastern dimming’ i.e. an increase of aerosols over Asia. There is a resemblance to the period of ‘western dimming’ from 1945 to 1980 and a contrast with the period of global temperature rise and El Ni?o strengthening from 1980 to 2000. It is of paramount importance that the suspected link between the eastern dimming the strengthening of La Ni?a and the break in global temperature rise is thoroughly investigated. This can best be done by a move of a satellite of the Meteosat Second Generation (MSG) series over the Indian Ocean. MSG provides diurnally resolved measurements of the key variables of the ERB clouds and aerosols and of the auxiliary variables of Sea Surface Temperature (SST) and static stability.

2013-01-01T23:59:59.000Z

134

Thermocapillary convection induced by laser surface heating  

SciTech Connect (OSTI)

Thermocapillary convection was excited by a laser source in experiments on molten paraffin. The parameters of the resultant flow were determined. The nature of the flow was demonstrated to correspond to shear-driven boundary-layer flow at high Reynolds numbers. Correlation dependences of the flow velocity of the melt and its temperature in the surface region were derived theoretically and were shown to agree with the experimental results. When the size of the laser spot was much less than the characteristic convection scales, three regions of flow of the melt could be distinguished: a viscous surface boundary layer, a stagnation zone under the laser spot, and a large-scale region of flow with a homogeneous temperature distribution. (interaction of laser radiation with matter. laser plasma)

Gladush, G G; Drobyazko, S V; Likhanskii, V V; Loboiko, A I; Senatorov, Yu M [State Research Center of Russian Federation 'Troitsk Institute for Innovation and Fusion Research', Troitsk, Moscow Region (Russian Federation)

1998-05-31T23:59:59.000Z

135

ARM - Field Campaign - Midlatitude Continental Convective Clouds Experiment  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Experiment (MC3E) Experiment (MC3E) Campaign Links Science Plan MC3E Website Related Campaigns Midlatitude Continental Convective Clouds Experiment: 2DVD Support 2011.04.22, Schwaller, SGP Midlatitude Continental Convective Clouds Experiment (MC3E): Airborne Instruments 2011.04.22, Poellot, AAF Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers 2011.04.22, Williams, SGP Midlatitude Continental Convective Clouds Experiment: Parsivel Disdrometer Support 2011.04.22, Schwaller, SGP Midlatitude Continental Convective Clouds Experiment (MC3E): Inner Domain Thermodynamic Profiling during MC3E 2011.04.22, Turner, SGP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Midlatitude Continental Convective Clouds Experiment (MC3E)

136

Meridional Circulation in Solar and Stellar Convection Zones  

E-Print Network [OSTI]

We present a series of 3-D nonlinear simulations of solar-like convection, carried out using the Anelastic Spherical Harmonic (ASH) code, that are designed to isolate those processes that drive and shape meridional circulations within stellar convection zones. These simulations have been constructed so as to span the transition between solar-like differential rotation (fast equator/slow poles) and ``anti-solar' differential rotation (slow equator/fast poles). Solar-like states of differential rotation, arising when convection is rotationally constrained, are characterized by a very different convective Reynolds stress than anti-solar regimes, wherein convection only weakly senses the Coriolis force. We find that the angular momentum transport by convective Reynolds stress plays a central role in establishing the meridional flow profiles in these simulations. We find that the transition from single-celled to multi-celled meridional circulation profiles in strong and weak regimes of rotational constraint is lin...

Featherstone, Nicholas A

2015-01-01T23:59:59.000Z

137

What Goes Up Must Come Down: The Lifecycle of Convective Clouds (492nd Brookhaven Lecture)  

SciTech Connect (OSTI)

Some clouds look like cotton balls and others like anvils. Some bring rain, some snow and sleet, and others, just shade. But, whether big and billowy or dark and stormy, clouds affect far more than the weather each day. Armed with measurements of clouds’ updrafts and downdrafts—which resemble airflow in a convection oven—and many other atmospheric interactions, scientists from Brookhaven Lab and other institutions around the world are developing models that are crucial for understanding Earth’s climate and forecasting future climate change. During his lecture, Dr. Jensen provides an overview of the importance of clouds in the Earth’s climate system before explaining how convective clouds form, grow, and dissipate. His discussion includes findings from the Midlatitude Continental Convective Clouds Experiment (MC3E), a major collaborative experiment between U.S. Department of Energy (DOE) and NASA scientists to document precipitation, clouds, winds, and moisture in 3-D for a holistic view of convective clouds and their environment.

Jensen, Michael [BNL Environmental Sciences

2014-02-19T23:59:59.000Z

138

Experimental study of free and mixed convective flow of air in a heated cavity  

SciTech Connect (OSTI)

Free and mixed convection in a strongly-heated rectangular open cavity have been investigated experimentally, to observe the effects of cavity shape and inclination, and of ambient wind, on the velocity and temperature distribution were observed. The long edges of the cavity were horizontal, and parallel to an axis around which the cavity could be rotated. The aperture plane was either vertical (..cap alpha.. = 0/sup 0/), or inclined downward at ..cap alpha.. - 20/sup 0/ or ..cap alpha.. = 45/sup 0/. The height of the aperture, b, was always 0.0947 m, while the depth of the cavity, a, was set so that a/b = 0.5, 1.0, or 1.46. The bottom and back walls were electrically heated - the top wall was indirectly heated by conduction, radiation and convection. The average wall temperature and the ambient temperature were used to define the dimensionless overheat and Grashof numbers. The Prandtl number was that of air. In the studies of mixed convection, the axis of rotation was horizontal and normal to the ambient wind. The Reynolds number was varied from Re = 120 - 1100 to Re = 2000 - 8740. For both free and mixed convection, wall and gas temperature were measured with thermocouples, and shadowgraph pictures were taken. For pure free convection, three time-averaged velocity components, the corresponding normal Reynolds stress components, and one off-diagonal Reynolds stress component were measured with a two-color laser-Doppler velocimeter. A PDP-11/34 minicomputer controlled the sequence of automatic data acquisition, the statistical data reduction and its storage. Statistical results are presented numerically and graphically for two averaging procedures. The principal quantitative result for free convection is that the rate of convective heat loss across the cavity aperture plane is reduced both by increasing a/b and by increasing ..cap alpha... Qualitative observations are recorded and discussed. The most striking observation was the appearance of a periodic oscillation of frequency 2 to 5.5 Hz.

Humphrey, J.A.C.; Sherman, F.S.

1985-04-01T23:59:59.000Z

139

Seismic measurement of the depth of the solar convection zone  

Science Journals Connector (OSTI)

......Grundforskningsfond, Institut for Fysik og Astronomi, Aarhus Universitet...testing the technique, while the basic technique used to determine...3 THE PROCEDURE 3.1 The basic technique The temperature gradient...Toornre J., eds, Challenges to theories of the structure of moderate-mass......

Sarbani Basu; H. M. Antia

1997-05-01T23:59:59.000Z

140

Tracer Gas Transport under Mixed Convection Conditions in an Experimental  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Tracer Gas Transport under Mixed Convection Conditions in an Experimental Tracer Gas Transport under Mixed Convection Conditions in an Experimental Atrium: Comparison Between Experiments and CFD Predictions Title Tracer Gas Transport under Mixed Convection Conditions in an Experimental Atrium: Comparison Between Experiments and CFD Predictions Publication Type Journal Article Year of Publication 2006 Authors Jayaraman, Buvaneswari, Elizabeth U. Finlayson, Michael D. Sohn, Tracy L. Thatcher, Phillip N. Price, Emily E. Wood, Richard G. Sextro, and Ashok J. Gadgil Journal Atmospheric Environment Volume 40 Start Page Chapter Pagination 5236-5250 Keywords airflow and pollutant transport group, atria, indoor airflow and pollutant transport, indoor environment department, indoor pollutant dispersion, mixed convection, turbulence model

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


141

Posters Mesoscale Simulations of Convective Systems with Data...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

7 Posters Mesoscale Simulations of Convective Systems with Data Assimilation During June 1993 in the Southern Great Plains J. Dudhia Mesoscale and Microscale Meteorology Division...

142

Diurnal Cycle of Convection at the ARM SGP Site: Role of Large-Scale Forcing, Surface Fluxes, and Convective Inhibition  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Diurnal Cycle of Convection at the ARM SGP Site: Diurnal Cycle of Convection at the ARM SGP Site: Role of Large-Scale Forcing, Surface Fluxes, and Convective Inhibition G. J. Zhang Center for Atmospheric Sciences Scripps Institution of Oceanography La Jolla, California Introduction Atmospheric convection undergoes strong diurnal variation over both land and oceans (Gray and Jacobson 1977; Dai 2001; Nesbitt and Zipser 2003). Because of the nature of the diurnal variation of solar radiation, the phasing of convection with solar radiation has a significant impact on the atmospheric radiation budget and cloud radiative forcing. A number of studies have investigated the possible mechanisms of the diurnal variation of convection (Gray and Jacobson 1977; Randall et al. 1991; Dai et al. 1999; Dai 2001). Yet, in regional and global climate models, the diurnal variation of

143

Meridional circulation dynamics from 3D MHD global simulations of solar convection  

E-Print Network [OSTI]

The form of the solar meridional circulation is a very important ingredient for mean field flux transport dynamo models. Yet a shroud of mystery still surrounds this large-scale flow, given that its measurement using current helioseismic techniques is challenging. In this work we use results from 3D global simulations of solar convection to infer the dynamical behavior of the established meridional circulation. We make a direct comparison between the meridional circulation that arises in these simulations and the latest observations. Based on our results we argue that there should be an equatorward flow at the base of the convection zone at mid latitudes, below the current maximum depth helioseismic measures can probe (0.75 R). We also provide physical arguments to justify this behaviour. The simulations indicate that the meridional circulation undergoes substantial changes in morphology as the magnetic cycle unfolds. We close by discussing the importance of these dynamical changes for current methods of obse...

Passos, Dario; Miesch, Mark

2015-01-01T23:59:59.000Z

144

Transitions between patterns in thermal convection  

SciTech Connect (OSTI)

We present experimental studies of the transitions between conduction, hexagons, and rolls in non-Boussinesq convection of gaseous CO{sub 2} in a cylindrical cell of radius-to-height ratio 86. Except for the transition from conduction to hexagons, transitions occur when the two states involved have nearly the same value of a generalized potential rather than at the stability limits. Conduction gives way to hexagons via the propagation of a front connecting the two states, while the transitions between hexagons and rolls are facilitated at the cell walls which appear to nucleate the minority state.

Bodenschatz, E.; de Bruyn, J.R.; Ahlers, G.; Cannell, D.S. (Department of Physics and Center for Nonlinear Science, University of California, Santa Barbara, Santa Barbara, California (USA) Memorial University of Newfoundland, St. John's, Newfoundland (Canada))

1991-11-25T23:59:59.000Z

145

Mechanisms initiating deep convection over complex terrain during COPS.  

SciTech Connect (OSTI)

Precipitating convection in a mountain region of moderate topography is investigated, with particular emphasis on its initiation in response to boundary-layer and mid- and upper-tropospheric forcing mechanisms. The data used in the study are from COPS (Convective and Orographically-induced Precipitation Study) that took place in southwestern Germany and eastern France in the summer of 2007. It is found that the initiation of precipitating convection can be roughly classified as being due to either: (i) surface heating and low-level flow convergence; (ii) surface heating and moisture supply overcoming convective inhibition during latent and/or potential instability; or (iii) mid-tropospheric dynamical processes due to mesoscale convergence lines and forced mean vertical motion. These phenomena have to be adequately represented in models in order to improve quantitative precipitation forecast. Selected COPS cases are analyzed and classified into these initiation categories. Although only a subset of COPS data (mainly radiosondes, surface weather stations, radar and satellite data) are used here, it is shown that convective systems are captured in considerable detail by sensor synergy. Convergence lines were observed by Doppler radar in the location where deep convection is triggered several hours later. The results suggest that in many situations, observations of the location and timing of convergence lines will facilitate the nowcasting of convection. Further on, forecasting of the initiation of convection is significantly complicated if advection of potentially convective air masses over changing terrain features plays a major role. The passage of a frontal structure over the Vosges - Rhine valley - Black Forest orography was accompanied by an intermediate suppression of convection over the wide Rhine valley. Further downstream, an intensification of convection was observed over the Black Forest due to differential surface heating, a convergence line, and the flow generated by a gust front.

Kottmeier, C.; Kalthoff, N.; Barthlott, C.; Corsmeier, U.; Van Baelen, J.; Coulter, R.; Environmental Science Division; Inst. for Meteorology and Climate Research; Lab. de Meteorologie Physique; Inst. of Physics and Meteorology

2008-12-01T23:59:59.000Z

146

Predicting free laminar convection heat transfer on curvilinear surfaces  

SciTech Connect (OSTI)

Free laminar convection on an isothermal surface of cylindrical and axisymmetric bodies of arbitrary cross section is considered in the Boussinesq approximation. The problem is solved by the method of generalized similarity in its local approximation. Universal formulae are obtained for calculating the local Nusselt number. Prediction of convection on a heated horizontal cylindrical and sphere are given as examples of the method.

Stepanyants, L.G.; Shelukho, S.I.

1989-07-01T23:59:59.000Z

147

EXPERIMENTAL INVESTIGATION OF BOILING HEAT CONVECTION IN A FRACTURE  

E-Print Network [OSTI]

EXPERIMENTAL INVESTIGATION OF BOILING HEAT CONVECTION IN A FRACTURE A REPORT SUBMITTED between heat conduction and heat convection with boiling flow in a rock fracture. An experimental coefficient. This coefficient is the proportionality factor between the heat flux to a fracture surface

Stanford University

148

Environmental Distinctions between Cellular and Slabular Convective Lines  

Science Journals Connector (OSTI)

The organizational mode of quasi-linear convective systems often falls within a spectrum of modes described by a line of discrete cells on one end (“cellular”) and an unbroken two-dimensional swath of ascent on the other (“slabular”). Convective ...

Richard P. James; J. Michael Fritsch; Paul M. Markowski

2005-09-01T23:59:59.000Z

149

Deep storage of oceanic crust in a vigorously convecting mantle  

E-Print Network [OSTI]

Deep storage of oceanic crust in a vigorously convecting mantle J. P. Brandenburg1 and P. E. van: Brandenburg, J. P., and P. E. van Keken (2007), Deep storage of oceanic crust in a vigorously convecting cycle of creation, interaction with seawater and subduction may be responsi- ble for the loss of Pb

van Keken, Peter

150

Theoretical analysis of convective heat transfer enhancement of microencapsulated phase change material slurries  

Science Journals Connector (OSTI)

...This paper analyzes the convective heat transfer enhancement mechanism of microencapsulated phase change material slurries based on the analogy between convective ... addition, the conventional Nusselt number ...

Yinping Zhang; Xianxu Hu; Xin Wang

2003-12-01T23:59:59.000Z

151

ARM - Field Campaign - Year of Tropical Convection (YOTC)  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

govCampaignsYear of Tropical Convection (YOTC) govCampaignsYear of Tropical Convection (YOTC) Campaign Links Year of Tropical Convection Website Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Year of Tropical Convection (YOTC) 2008.05.01 - 2010.04.30 Lead Scientist : Sally McFarlane Description Example of a sonde profile available from the ARM Archive The realistic representation of tropical convection in global atmospheric models is a long-standing challenge for weather and global climate models. The lack of fundamental knowledge in this area causes difficulties in modeling and predicting prominent phenomena of the tropical atmosphere such as the inter-tropical convergence zone (ITCZ), El-Nino/Southern Oscillation (ENSO), monsoons, the Madden-Julian Oscillation (MJO), tropical cyclones,

152

BNL | Midlatitude Continental Convective Clouds Experiment (MC3E)  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Midlatitude Continental Convective Clouds Experiment Midlatitude Continental Convective Clouds Experiment Convective processes play a critical role in the Earth's energy balance through the redistribution of heat and moisture in the atmosphere and their link to the hydrological cycle. Accurate representation of convective processes in numerical models is vital towards improving current and future simulations of Earths climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales important to convective processes and therefore must turn to parameterization schemes to represent these processes. In turn, parameterization schemes in cloud-resolving models need to be evaluated for their generality and application to a

153

Limiting Factors for Convective Cloud Top Height in the Tropics  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Limiting Factors for Convective Cloud Top Limiting Factors for Convective Cloud Top Height in the Tropics M. P. Jensen and A. D. Del Genio National Aeronautics and Space Administration Goddard Institute for Space Studies Columbia University New York, New York Introduction Populations of tropical convective clouds are mainly comprised of three types: shallow trade cumulus, mid-level cumulus congestus and deep convective clouds (Johnson et al. 1999). Each of these cloud types has different impacts on the local radiation and water budgets. For climate model applications it is therefore important to understand the factors which determine the type of convective cloud that will occur. In this study, we concentrate on describing the factors that limit the cloud-top heights of mid-

154

On the practice of dichotomization of quantitative variables  

E-Print Network [OSTI]

The authors examine the practice of dichotomization of quantitative measures, wherein relationships among variables are examined after 1 or more variables have been converted to dichotomous variables by splitting the sample ...

MacCallum, R. C.; Zhang, S.; Preacher, K. J.; Rucker, D. D.

2002-01-01T23:59:59.000Z

155

Review of fluid flow and convective heat transfer within rotating disk cavities with impinging jet  

E-Print Network [OSTI]

Fluid flow and convective heat transfer in rotor-stator configurations, which are of great importance in different engineering applications, are treated in details in this review. The review focuses on convective heat transfer in predominantly outward air flow in the rotor-stator geometries with and without impinging jets and incorporates two main parts, namely, experimental/theoretical methodologies and geometries/results. Experimental methodologies include naphthalene sublimation techniques, steady state (thin layer) and transient (thermochromic liquid crystals) thermal measurements, thermocouples and infra-red cameras, hot-wire anemometry, laser Doppler and particle image velocimetry, laser plane and smoke generator. Theoretical approaches incorporate modern CFD computational tools (DNS, LES, RANS etc). Geometries and results part being mentioned starting from simple to complex elucidates cases of a free rotating disk, a single disk in the crossflow, single jets impinging onto stationary and rotating disk,...

Harmand, Souad; Poncet, Sébastien; Shevchuk, Igor V; 10.1016/j.ijthermalsci.2012.11.009

2013-01-01T23:59:59.000Z

156

Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters  

SciTech Connect (OSTI)

Deep-sea gorgonian corals secrete a 2-part skeleton of calcite, derived from dissolved inorganic carbon at depth, and gorgonin, derived from recently fixed and exported particulate organic matter. Radiocarbon contents of the calcite and gorgonin provide direct measures of seawater radiocarbon at depth and in the overlying surface waters, respectively. Using specimens collected from Northwest Atlantic slope waters, we generated radiocarbon records for surface and upper intermediate water layers spanning the pre- and post bomb-{sup 14}C eras. In Labrador Slope Water (LSW), convective mixing homogenizes the pre-bomb {Delta}{sup 14}C signature (-67 {+-} 4{per_thousand}) to at least 1000 m depth. Surface water bomb-{sup 14}C signals were lagged and damped (peaking at {approx} +45{per_thousand} in the early 1980s) relative to other regions of the northwest Atlantic, and intermediate water signals were damped further. Off southwest Nova Scotia, the vertical gradient in {Delta}{sup 14}C is much stronger. In surface water, pre-bomb {Delta}{sup 14}C averaged -75 {+-} 5{per_thousand}. At 250-475 m depth, prebomb {Delta}{sup 14}C oscillated quasi-decadally between -80 and -100{per_thousand}, likely reflecting interannual variability in the presence of Labrador Slope Water vs. Warm Slope Water (WSW). Finally, subfossil corals reveal no systematic changes in vertical {Delta}{sup 14}C gradients over the last 1200 years.

Sherwood, O; Edinger, E; Guilderson, T P; Ghaleb, B; Risk, M J; Scott, D B

2008-08-15T23:59:59.000Z

157

Divergent subcritical convection in magnetized plasma from asymmetric sourcing  

SciTech Connect (OSTI)

Asymmetric particle and heat sourcing in a plasma confined in a closed magnetic field line configuration results in convection cells, as is well known. This phenomenon occurs even if the sourcing on average produces density and temperature profiles that are subcritical, i.e., magnetohydrodynamically stable to interchange modes. Such subcritical convection is expected to be small compared to the convection from supercritical driving for which the system is interchange unstable. The ratio of subcritical to supercritical convection is expected to scale as the inverse Reynolds numbers (for large Reynolds numbers). It is shown that this ratio is, in fact, considerably larger. As marginal stability is approached, the subcritical convection grows from very small to almost the unstable convection size, i.e., of order unity. This effect may be similar to why a driven, damped harmonic oscillator increases in amplitude as resonance is approached. A numerical simulation is done to demonstrate this effect. It is also shown that transport from the large convection can be substantial.

Adler, D.T.; Hassam, A.B. [Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

2005-06-15T23:59:59.000Z

158

Final Technical Report for "Radiative Heating Associated with Tropical Convective Cloud Systems: Its Importance at Meso and Global Scales"  

SciTech Connect (OSTI)

Heating associated with tropical cloud systems drive the global circulation. The overall research objectives of this project were to i) further quantify and understand the importance of heating in tropical convective cloud systems with innovative observational techniques, and ii) use global models to determine the large-scale circulation response to variability in tropical heating profiles, including anvil and cirrus cloud radiative forcing. The innovative observational techniques used a diversity of radar systems to create a climatology of vertical velocities associated with the full tropical convective cloud spectrum along with a dissection of the of the total heating profile of tropical cloud systems into separate components (i.e., the latent, radiative, and eddy sensible heating). These properties were used to validate storm-scale and global climate models (GCMs) and were further used to force two different types of GCMs (one with and one without interactive physics). While radiative heating was shown to account for about 20% of the total heating and did not have a strong direct response on the global circulation, the indirect response was important via its impact on convection, esp. in how radiative heating impacts the tilt of heating associated with the Madden-Julian Oscillation (MJO), a phenomenon that accounts for most tropical intraseasonal variability. This work shows strong promise in determining the sensitivity of climate models and climate processes to heating variations associated with cloud systems.

Schumacher, Courtney

2012-12-13T23:59:59.000Z

159

Detection of surface mobility of poly (2, 3, 4, 5, 6-pentafluorostyrene) films by in situ variable-temperature ToF-SIMS and contact angle measurements  

Science Journals Connector (OSTI)

Abstract Poly (2, 3, 4, 5, 6-pentafluorostyrene) (5FPS) was prepared by bulk radical polymerization. The spin-cast films of this polymer were analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS) at various temperatures ranging from room temperature to 120 °C. Principal component analysis (PCA) of the ToF-SIMS data revealed a transition temperature (TT) at which the surface structure of 5FPS was rearranged. A comparison between the results of the PCA of ToF-SIMS spectra obtained on 5FPS and polystyrene (PS) indicate that the pendant groups of 5FPS and PS moved in exactly opposite directions as the temperature increased. More pendant groups of 5FPS and PS migrated from the bulk to the surface and verse versa, respectively, as the temperature increased. These results clearly support the view that the abrupt changes in the normalized principal component 1 value was caused by the surface reorientation of the polymers and not by a change in the ion fragmentation mechanism at temperatures above the TT. Contact angle measurement, which is another extremely surface sensitive technique, was used to monitor the change in the surface tension as a function of temperature. A clear TT was determined by the contact angle measurements. The TT values determined by contact angle measurements and ToF-SIMS were very similar.

Yi Fu; Yiu-Ting R. Lau; Lu-Tao Weng; Kai-Mo Ng; Chi-Ming Chan

2014-01-01T23:59:59.000Z

160

Lattice Boltzmann method for double-diffusive natural convection  

Science Journals Connector (OSTI)

A lattice Boltzmann method for double-diffusive natural convection is presented. The model combines a multicomponent lattice Boltzmann scheme with a finite-difference solution of the energy equation to simulate natural convection caused by gradients in temperature and concentration. The model is validated both in two and three dimensions, and the agreement with literature data is satisfactory. A case study of thermosolutal convection of air in a cubical enclosure with horizontal thermal and solutal gradients is presented, exhibiting a rich variety of flow structures.

F. Verhaeghe; B. Blanpain; P. Wollants

2007-04-12T23:59:59.000Z

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


161

Numerical and Experimental Modeling of Natural Convection for a Cryogenic Prototype of a Titan  

E-Print Network [OSTI]

in Sutherland's law D = diameter g = gravitation acceleration h = convection coefficient k = thermal

Colonius, Tim

162

Convective heat transfer characteristics of China RP-3 aviation kerosene at supercritical pressure  

E-Print Network [OSTI]

Convective heat transfer characteristics of China RP-3 aviation kerosene at supercritical pressure Keywords: Supercritical pressure Aviation kerosene Convective heat transfer Numerical study a b s t r a c convective in kerosene pipe flow is complicated. Here the convective heat transfer characteristics of China

Guo, Zhixiong "James"

163

Penetration of Convective Envelope into Stellar Core and Existence of Neutrino Loss  

Science Journals Connector (OSTI)

......the products of Penetration of Convective Envelope...convective mixing for any rate of the neutrino...superadiabaticity is determined Penetration of Convective Envelope...used.15> 459 the rate of Since the main...energy generation rate is sensitive to...smaller mass stars, penetration of convective envelope......

Ken'ichi Nomoto

1974-08-01T23:59:59.000Z

164

Energy Analysis of Convectively Induced Wind Perturbations  

Science Journals Connector (OSTI)

Budgets of divergent and rotational components of kinetic energy (KD and KR) are examined for four upper level wind speed maxima that develop during the fourth Atmospheric Variability Experiment (AVE IV) and the first AVE-Severe Environmental ...

Henry E. Fuelberg; Dennis E. Buechler

1989-04-01T23:59:59.000Z

165

Numerical study of natural convection in fully open tilted cavities  

SciTech Connect (OSTI)

A numerical simulation of two-dimensional laminar natural convection in a fully open tilted square cavity with an isothermally heated back wall is conducted. The remaining two walls of the cavity are adiabatic. Steady-state solutions are presented for Grashof numbers between 10{sup 2} and 10{sup 5} and for tilt angles ranging from {minus}60{degree} to 90{degree} (where 90{degree} represents a cavity with the opening facing down). The fluid properties are assumed to be constant except for the density variation with temperature that gives rise to the buoyancy forces, which is treated by the Boussinesq approximation. The fluid concerned is air with Prandtl number fixed at 0.71. The governing equations are expressed in a normalized primitive variables formulation. Numerical predictions of the velocity and temperature fields are obtained using the finite-volume-based power law (SIMPLER: Semi-Implicit Method for Pressure-Linked Equations Revised) algorithm. For a vertical open cavity ({alpha} = 0{degree}), the algorithm generated results that were in good agreement with those previously published. Flow patterns and isotherms are shown in order to give a better understanding of the heat transfer and flow mechanisms inside the cavity. Effects of the controlling parameters-Grashof number and tilt angle-on the heat transfer (average Nusselt number) are presented and analyzed. The results also revealed that the open-cavity Nusselt number approaches the flat-plate solution when either Grashof number or tilt angle increases. In addition, a correlation of the Nusselt number in terms of the Grashof number and tilt angle is developed and presented; a comparison is made with available data from other literature.

Elsayed, M.M.; Al-Najem, N.M.; El-Refaee, M.M.; Noor, A.A.

1999-09-01T23:59:59.000Z

166

Raindrop axis ratios, fall velocities and size distribution over Sumatra from 2D-Video Disdrometer measurement  

Science Journals Connector (OSTI)

Raindrop axis ratio, falling velocity and size distribution are important in broad list of applications. However, they are not frequently observed in the equatorial region. This paper elucidated the characteristics of raindrop axis ratio, falling velocity and size distribution based on 2D-Video Disdrometer (2DVD) data that have been collected in the equatorial Indonesia, particularly at Kototabang (hereafter called KT), west Sumatra, Indonesia (0.20°S, 100.32°E, 864 m above sea level). A comprehensive follow-up of the previous study on the natural variability of raindrop size distributions (DSDs) is presented. Precipitation was classified through 1.3-GHz wind profiler observation. The dependence of raindrop falling velocity and axis ratio on rainfall type was not clearly observed. Overall, measured raindrop fall velocities were in good agreement with Gunn–Kinzer's data. Raindrop axis ratio at KT was more spherical than that of artificial rain and equilibrium model, and close to the values reported in the turbulent high shear zone of surface layer which can be partially due to the effect of the instrument errors (e.g., location and container shape). Of some natural variations of DSD investigated, the dependence of DSD on rainfall rate and rainfall type as well as diurnal variation was clearly visible. A striking contrast between the stratiform and convective rains is that the size distributions from the stratiform (convective) rains tend to narrow (broaden) with increasing rainfall rates. For rainfall rate R < 10 mm/h, the size distribution of stratiform was broader than that of convective. On the other hand, at higher rainfall rate more large-sized drops were found in convective rain. During the convective rain, very large-sized drops were found mainly at the very start of rain event while for the stratiform they were found to be associated with a strong bright band. In diurnal basis, the \\{DSDs\\} in the morning hours were narrower than those in the evening which was indicated by smaller Dm values in the morning hours than their counterparts in the evening. Rainfall type dependence and diurnal variation of DSD lead to significant variation of Z–R relations so that they must be considered to increase the accuracy of Z–R conversion from weather radar in this region. Consistent with the previous study, lack of seasonal DSD variability was also found in this work that would be due to significant local convective and orographic effect at this region throughout the year. However, Dm values in our result were larger than the typical orographic DSD.

Marzuki; Walter L. Randeu; Toshiaki Kozu; Toyoshi Shimomai; Hiroyuki Hashiguchi; Michael Schönhuber

2013-01-01T23:59:59.000Z

167

Heat transfer and convection onset in a compressible fluid:?3He near the critical point  

Science Journals Connector (OSTI)

Heat transport in 3He above its critical temperature Tc was studied along the critical isochore in a flat Rayleigh-Bénard cell (height h=1 mm, diameter D=57 mm). The range of the reduced temperature ? was 5×10-4fluid layer as a function of the time t was measured for different values of the heat current q until steady state was reached. The crossover was observed from the regime dominated by the Rayleigh criterion for the convection onset to that controlled by the adiabatic temperature gradient (ATG), or “Schwarzschild criterion,” in good quantitative agreement with predictions. The slope of the convective heat current versus the reduced Rayleigh number was found to be independent of compressibility and the same as for still less compressible fluids. Plots of Nu versus Ra, both corrected for the ATG effect, are presented for early-stage convective turbulence (1×105fluid is described, and the derivation for ?T(t) in the diffusive regime is outlined.

Andrei B. Kogan and Horst Meyer

2001-04-24T23:59:59.000Z

168

Seismic diagnostics of mixing beyond the convective core in intermediate mass main-sequence stars  

E-Print Network [OSTI]

We study prospects for seismic sounding the layer of a partial mixing above the convective core in main-sequence stars with masses in the 1.2 -- 1.9 solar mass range. There is an initial tendency to an increase of convective core mass in such stars and this leads to ambiguities in modeling. Solar-like oscillations are expected to be excited in such objects. Frequencies of such oscillations provide diagnostics, which are sensitive to the structure of the innermost part of the star and they are known as the small separations. We construct evolutionary models of stars in this mass range assuming various scenarios for element mixing, which includes formation of element abundance jumps, as well as semiconvective and overshooting layers. We find that the three point small separations employing frequencies of radial and dipole modes provide the best probe of the element distribution above the convective core. With expected accuracy of frequency measurement from the space experiments, a discrimination between various scenarios should be possible.

B. L. Popielski; W. A. Dziembowski

2005-05-25T23:59:59.000Z

169

Experimental Investigation of Natural Convection in Trombe Wall Systems  

E-Print Network [OSTI]

In this paper, experiments with a passive solar building with Trombe wall in the north cold climate are carried out and discussed, and the natural convection heat transfer process has been investigated. The relativity of the factors affecting indoor...

Chen, B.; Zhao, J.; Chen, C.; Zhuang, Z.

2006-01-01T23:59:59.000Z

170

Ensemble Sensitivity Analysis Applied to a Southern Plains Convective Event  

Science Journals Connector (OSTI)

Forecast sensitivity of an April 2012 severe convection event in northern Texas is investigated with a high resolution Weather Research and Forecasting (WRF) model-based Ensemble Kalman Filter (EnKF). Through Ensemble Sensitivity Analysis (ESA), ...

Christopher N. Bednarczyk; Brian C. Ancell

171

Theory for induced convection experiments in the tokamak edge  

E-Print Network [OSTI]

Theory for induced convection experiments in the tokamak edge P. Helander1 , D.D. Ryutov2 , and R National Laboratory, Livermore, USA By biasing alternate divertor plates in a tokamak, one can create

172

Initiating Moist Convection in an Inhomogeneous Layer by Uniform Ascent  

Science Journals Connector (OSTI)

Using aircraft data from the recent Dominica Experiment (DOMEX) project in Dominica, the authors evaluate a modified version of Woodcock’s theory of moist convective initiation. Upstream of Dominica, anticorrelated fluctuations in temperature and ...

Alison D. Nugent; Ronald B. Smith

2014-12-01T23:59:59.000Z

173

Effects of aerosols on deep convective cumulus clouds  

E-Print Network [OSTI]

This work investigates the effects of anthropogenic aerosols on deep convective clouds and the associated radiative forcing in the Houston area. The Goddard Cumulus Ensemble model (GCE) coupled with a spectral-bin microphysics is employed...

Fan, Jiwen

2009-05-15T23:59:59.000Z

174

Vertical Structure of Convective Systems during NAME 2004  

Science Journals Connector (OSTI)

This study describes the vertical structure of mesoscale convective systems (MCSs) that characterized the 2004 North American monsoon utilizing observations from a 2875-MHz (S band) profiler and a dual-polarimetric scanning Doppler radar. Both ...

David G. Lerach; Steven A. Rutledge; Christopher R. Williams; Robert Cifelli

2010-05-01T23:59:59.000Z

175

Scaling Laws for the Heterogeneously Heated Free Convective Boundary Layer  

Science Journals Connector (OSTI)

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

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

2014-11-01T23:59:59.000Z

176

A Unified Convection Scheme (UNICON). Part I: Formulation  

Science Journals Connector (OSTI)

The author develops a unified convection scheme (UNICON) that parameterizes relative (i.e., with respect to the grid-mean vertical flow) subgrid vertical transport by nonlocal asymmetric turbulent eddies. UNICON is a process-based model of subgrid ...

Sungsu Park

2014-11-01T23:59:59.000Z

177

Representing Forecast Error in a Convection-Permitting Ensemble System  

Science Journals Connector (OSTI)

Ensembles provide an opportunity to greatly improve short-term prediction of local weather hazards, yet generating reliable predictions remain a significant challenge. In particular, convection-permitting ensemble forecast systems (CPEFSs) have ...

Glen S. Romine; Craig S. Schwartz; Judith Berner; Kathryn R. Fossell; Chris Snyder; Jeff L. Anderson; Morris L. Weisman

2014-12-01T23:59:59.000Z

178

Convective stability of carbon sequestration in anisotropic porous media  

Science Journals Connector (OSTI)

...Convective stability of carbon sequestration in anisotropic porous media...media|stability theory|carbon sequestration| 1. Introduction The world's...processes occurring during carbon dioxide sequestration in underground saline aquifers...

2014-01-01T23:59:59.000Z

179

Land-atmosphere interaction and radiative-convective equilibrium  

E-Print Network [OSTI]

I present work on several topics related to land-atmosphere interaction and radiative-convective equilibrium: the first two research chapters invoke ideas related to land-atmosphere interaction to better understand ...

Cronin, Timothy (Timothy Wallace)

2014-01-01T23:59:59.000Z

180

A Unified Convection Scheme (UNICON). Part II: Simulation  

Science Journals Connector (OSTI)

A unified convection scheme (UNICON) is implemented into the Community Atmosphere Model, version 5 (CAM5), and tested in single-column and global simulations forced by observed sea surface temperature. Compared to CAM5, UNICON substantially ...

Sungsu Park

2014-11-01T23:59:59.000Z

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


181

Interaction between surface and atmosphere in a convective boundary layer /  

E-Print Network [OSTI]

heat, and thermal conductivity of the ground and grid sizegrid was stretched uniformly to 0.1 m resolution. The heatheat flux) are friction velocity and convective velocity respectively. The grid

Garai, Anirban

2013-01-01T23:59:59.000Z

182

The Convective Instability Pathway to Warm Season Drought in Texas. Part I: The Role of Convective Inhibition and Its Modulation by Soil Moisture  

Science Journals Connector (OSTI)

This research is designed to investigate how convective instability influences monthly mean precipitation in Texas in the summertime and to examine the modulation of convective instability and precipitation by local and regional forcings. Since ...

Boksoon Myoung; John W. Nielsen-Gammon

2010-09-01T23:59:59.000Z

183

Dynamic Transitions of Surface Tension Driven Convection  

E-Print Network [OSTI]

We study the well-posedness and dynamic transitions of the surface tension driven convection in a three-dimensional (3D) rectangular box with non-deformable upper surface and with free-slip boundary conditions. It is shown that as the Marangoni number crosses the critical threshold, the system always undergoes a dynamic transition. In particular, two different scenarios are studied. In the first scenario, a single mode losing its stability at the critical parameter gives rise to either a Type-I (continuous) or a Type-II (jump) transition. The type of transitions is dictated by the sign of a computable non-dimensional parameter, and the numerical computation of this parameter suggests that a Type-I transition is favorable. The second scenario deals with the case where the geometry of the domain allows two critical modes which possibly characterize a hexagonal pattern. In this case we show that the transition can only be either a Type-II or a Type-III (mixed) transition depending on another computable non-dimensional parameter. We only encountered Type-III transition in our numerical calculations. The second part of the paper deals with the well-posedness and existence of global attractors for the problem.

Henk Dijkstra; Taylan Sengul; Shouhong Wang

2011-05-05T23:59:59.000Z

184

Mesoscale disturbances in the tropical stratosphere excited by convection: Observations and effects on the stratospheric momentum budget  

SciTech Connect (OSTI)

The importance of the momentum flux of topographically generated mesoscale gravity waves to the extratropical middle atmosphere circulation has been well established for over a decade. Estimates of the zonal forcing due to tropical mesoscale gravity waves, however, are hampered by lack of data on their primarily convective sources. The advent of aircraft measurements over tropical convective systems now makes such estimates possible without the use of ad hoc assumptions about amplitudes and phase speeds. Aircraft measurements from NASA's 1980 Panama and 1987 STEP/Australia Missions show that convectively generated disturbances observed just above the tropopause have horizontal scales comparable to those of the underlying anvils (about 50--100 km) with peak-to-peak isentropic surface variations of about 300--400 m. Satellite imagery of tropical anvil evolution indicates a typical lifetime of about five hours. Assuming that each convective system's impact on the stratosphere can be modeled as a time-dependent [open quotes]mountain[close quotes] with the preceding spatial and time scales, the excited spectrum of gravity waves can be calculated. A suitable quasi-linear wave-mean flow interaction parameterization and satellite-derived cloud area statistics can then be used to evaluate the zonal acceleration as a function of altitude induced by gravity waves from mesoscale convective systems. The results indicate maximum westerly accelerations due to breaking mesoscale gravity waves of almost 0.4 m s[sup [minus]1]/day in the upper stratosphere (in the region of the semiannual oscillation) during September, comparable to but probably smaller than the accelerations induced by planetary-scale Kelvin waves. Calculated easterly accelerations due to breaking mesoscale gravity waves in the QBO region below 35 km are smaller, accounting for about 10% of the required zonal acceleration. 35 refs., 14 figs., 1 tab.

Pfister, L.; Scott, S.; Loewenstein, M. (NASA/Ames Research Center, Moffett Field, CA (United States)); Bowen, S. (San Jose State Univ., CA (United States)); Legg, M. (Synernet, Fremont, CA (United States))

1993-04-15T23:59:59.000Z

185

Predictor Variables of the Maximum Radar Echo Activity on Convective Days  

Science Journals Connector (OSTI)

Digital radar data and atmospheric sounding information were analyzed with the intention of beginning a search for atmospheric parameters which are easily attainable, are independent of whether or not clouds are seeded, and either individually or ...

Gerard E. Klazura; Robert G. Pritchard

1980-03-01T23:59:59.000Z

186

Convective variability associated with a mesoscale vortex in a midlatitude squall line system  

E-Print Network [OSTI]

. . . . . . . . . . CASE DESCRIPTION. . STORM MORPHOLOGY Low Levels (surface to 1. 9 km) Mid-to-Low Levels (2. 4 to 3. 9 km). . . . . . . . Mid-to-Upper Levels (4. 4 to 8. 9 km). . . . . . Upper Levels (9. 4 km and above). . . . . . . . . . Vertical Cross... Streamline/isotachanalysisofstorm-relativewinds at1150UTCon 28 May 1985. 1152 UTC dual Doppler analysis of kinematic and reflectivity field at 1. 4 km Mean Sea Level (MSL). . 47 , . 49 20b 1152 UTC dual Doppler analysis of the storm-relative horizontal...

Hristova-Veleva, Svetla M.

1994-01-01T23:59:59.000Z

187

The Convective and Orographically Induced Precipitation Study (COPS): The Scientific Strategy, the Field Phase, and Research Highlights  

SciTech Connect (OSTI)

Within the frame of the international field campaign COPS (Convective and Orographically-induced Precipitation Study), a large suite of state-of-the-art meteorological instrumentation was operated, partially combined for the first time. The COPS field phase was performed from 01 June - 31 August 2007 in a low-mountain area in southwestern Germany/eastern France covering the Vosges Mountains, the Rhine valley and the Black Forest Mountains. The collected data set covers the entire evolution of convective precipitation events in complex terrain from their initiation, to their development and mature phase up to their decay. 18 Intensive Operation Periods (IOPs) with 34 operation days and 8 additional Special Observation Periods (SOPs) were performed providing a comprehensive data set covering different forcing conditions. In this paper an overview of the COPS scientific strategy, the field phase, and its first accomplishments is given. Some highlights of the campaign are illustrated with several measurement examples. It is demonstrated that COPS provided new insight in key processes leading to convection initiation and to the modification of precipitation by orography, in the improvement of QPF by the assimilation of new observations, and in the performance of ensembles of convection permitting models in complex terrain.

Wulfmeyer, Volker; Behrendt, Andreas; Kottmeir, Christoph; Corsmeier, Ulrich; Barthlott, Christian; Craig, George C.; Hagen, Martin; Althausen, Dietrich; Aoshima, Fumiko; Arpagaus, Marco; Bauer, Hans-Stefan; Bennett, Lindsay; Blyth, Alan; Brandau, Christine; Champollion, Cedric; Crewell, Susanne; Dick, Galina; di Girolamo, Paolo; Dorninger, Manfred; Dufournet, Yann; Eigenmann, Rafael; Engelmann, Ronny; Flamant, C.; Foken, Thomas; Gorgas, Theresa; Grzeschik, Matthias; Handwerker, Jan; Hauck, Christian; Holler, Hartmut; Junkermann, W.; Kalthoff, Norbert; Kiemle, Christoph; Klink, Stefan; Konig, Marianne; Krauss, Liane; Long, Charles N.; Madonna, Fabio; Mobbs, S.; Neininger, Bruno; Pal, Sandip; Peters, Gerhard; Pigeon, Gregoire; Richard, Evelyne; Rotach, Mathias W.; Russchenberg, Herman; Schwitalla, Thomas; Smith, Victoria; Steinacker, Reinhold; Trentman, Jorg; Turner, David D.; van Baelen, Joel; Vogt, Siegfried; Volkert, Hans; Weckwerth, Tammy; Wernli, Heini; Wieser, Andreas; Wirth, Martin

2011-02-24T23:59:59.000Z

188

Power-Law Behavior of Power Spectra in Low Prandtl Number Rayleigh-Benard Convection  

SciTech Connect (OSTI)

The origin of the power-law decay measured in the power spectra of low Prandtl number Rayleigh-Benard convection near the onset of chaos is addressed using long time numerical simulations of the three-dimensional Boussinesq equations in cylindrical domains. The power law is found to arise from quasidiscontinuous changes in the slope of the time series of the heat transport associated with the nucleation of dislocation pairs and roll pinch-off events. For larger frequencies, the power spectra decay exponentially as expected for time continuous deterministic dynamics.

Paul, M. R.; Cross, M. C.; Fischer, P. F.; Greenside, H. S.

2001-10-08T23:59:59.000Z

189

Convective heat transfer in an annular porous layer with centrifugal force field  

SciTech Connect (OSTI)

The present study deals with natural convection in an annular porous layer under the influence of a centrifugal force field. It is assumed that the outer boundary is heated by a constant heat flux, while the inner boundary is perfectly insulated. The problem is formulated in terms of Darcy-Boussinesq equations and solved using analytical and numerical techniques. An analytical solution for the flow and heat transfer variables, based on a concentric flow assumption, is obtained in terms of the Rayleigh number and the radius ratio. Finite amplitude results are verified by a numerical approach. Predicted thresholds in terms of critical Rayleigh numbers are verified by a linear stability analysis. Results obtained from the numerical approach indicate the existence of multiple solutions differing by the number of cells involved.

Aboubi, K.; Robillard, L.; Bilgen, E. [Univ. of Montreal, Quebec (Canada). Dept. of Mechanical Engineering

1995-09-01T23:59:59.000Z

190

Compact range for variable-zone measurements  

DOE Patents [OSTI]

A compact range for testing antennas or radar targets includes a source for directing energy along a feedline toward a parabolic reflector. The reflected wave is a spherical wave with a radius dependent on the distance of the source from the focal point of the reflector.

Burnside, Walter D. (Columbus, OH); Rudduck, Roger C. (Columbus, OH); Yu, Jiunn S. (Albuquerque, NM)

1988-01-01T23:59:59.000Z

191

Compact range for variable-zone measurements  

DOE Patents [OSTI]

A compact range for testing antennas or radar targets includes a source for directing energy along a feedline toward a parabolic reflector. The reflected wave is a spherical wave with a radius dependent on the distance of the source from the focal point of the reflector. 2 figs.

Burnside, W.D.; Rudduck, R.C.; Yu, J.S.

1987-02-27T23:59:59.000Z

192

A dual mass flux framework for boundary layer convection  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

A dual mass flux framework for boundary layer convection A dual mass flux framework for boundary layer convection Neggers, Roel European Centre for Medium-range Weather Forecasts (ECMWF) Category: Modeling A new convective boundary layer scheme is presented that is currently being developed for the Integrated Forecasting System (IFS) of the European Centre for Medium-range Weather Forecasts (ECMWF). Part of the total turbulent flux is modeled through advective mass flux by multiple updrafts, initialized at the surface. Two groups of updrafts are explicitly represented; i) updrafts that never reach their lifting condensation level, and ii) updrafts that condensate and become cloudy. Key new ingredient is the flexibility of the associated updraft area fractions, as a function of model state. As a result, an extra degree of freedom is introduced in the

193

Natural Convection Shutdown Heat Removal Test Facility (NSTF)  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Natural Convection Natural Convection Shutdown Heat Removal Test Facility Scaling Basis Full Scale Half Scale NSTF Argonne National Laboratory's Natural Convection Shutdown Heat Removal Test Facility (NSTF) - one of the world's largest facilities for ex-vessel passive decay heat removal testing-confirms the performance of reactor cavity cooling systems (RCCS) and similar passive confinement or containment decay heat removal systems in modern Small Modular Reactors. Originally built to aid in the development of General Electric's Power Reactor Innovative Small Module (PRISM) Reactor Vessel Auxiliary Cooling System (RVACS), the NSTF has a long history of providing confirmatory data for the airside of the RVACS. Argonne National Laboratory's NSTF is a state-of-the-art, large-scale facility for evaluating performance

194

ARM - Midlatitude Continental Convective Clouds (comstock-hvps)  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

Convective processes play a critical role in the Earth's energy balance through the redistribution of heat and moisture in the atmosphere and their link to the hydrological cycle. Accurate representation of convective processes in numerical models is vital towards improving current and future simulations of Earths climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales important to convective processes and therefore must turn to parameterization schemes to represent these processes. In turn, parameterization schemes in cloud-resolving models need to be evaluated for their generality and application to a variety of atmospheric conditions. Data from field campaigns with appropriate forcing descriptors have been traditionally used by modelers for evaluating and improving parameterization schemes.

Jensen, Mike; Comstock, Jennifer; Genio, Anthony Del; Giangrande, Scott; Kollias, Pavlos

195

The influence of convective heat transfer on flow stability in rotating disk chemical vapor deposition reactors  

SciTech Connect (OSTI)

Flow and heat transfer of NH{sub 3} and He were studied in a rotating disk system with applications to chemical vapor deposition reactors. Flow field and disk heat flux were obtained over a range of operating conditions. Comparisons of disk convective heat transfer were made to infinite rotating disk results to appraise uniformity of transport to the disk. Important operating variables include disk spin rate, disk and enclosure temperatures, flow rate, composition, pressure, and gas mixture temperature at the reactor inlet. These variables were studied over ranges of the spin Reynolds number, Re{omega}; disk mixed convection parameter, MCP{sub w}; and wall mixed convection parameter, MCP{sub w}. Results obtained for NH{sub 3} show that increasing Re{omega} from 314.5 to 3145 increases the uniformity of rotating disk heat flux and results in thinner thermal boundary layers at the disk surface. At Re{omega}=314.5, increasing MCP{sub d} to 15 leads to significant departure from the infinite disk result with nonuniform disk heat fluxes and recirculating flow patterns; flow becomes increasingly complex at larger values of MCP{sub d}. At Re{omega} of 3145, results are closer to the infinite disk for MCP{sub d} up to 15. For large negative (hot walls) and positive (cold walls) values of MCP{sub w}, flow recirculates and there is significant deviation from the infinite disk result; nonuniformities occur at both values of Re{omega}. The influence of MCP{sub w} on flow stability is increased at larger MCP{sub d} and lower Re{omega}. To determine the influence of viscosity and thermal conductivity variation with temperature, calculations were made with He and NH{sub 3}; He transport property variation is low relative to NH{sub 3}. Results show that the flow of NH{sub 3} is less stable than that of He as MCP{sub d} is increased for MCP{sub w}=0 and Re{omega}=314.5. 16 refs., 15 figs., 1 tab.

Winters, W.S.; Evans, G.H. [Sandia National Labs., Livermore, CA (United States); Grief, R. [Univ. of California, Berkeley, CA (United States). Mechanical Engineering Dept.

1997-06-01T23:59:59.000Z

196

Conjugate High Latitude Measurements along the 40 Magnetic Meridian  

E-Print Network [OSTI]

Conjugate High Latitude Measurements along the 40º Magnetic Meridian: Autonomous Adaptive Low the 2014 season marked as red squares. #12;Autonomous Adaptive Low-Power Instrument #12;Conjugate observations of Travelling Convection Vorticies produced by solar wind pressure

Michigan, University of

197

Convective exergy losses of developing slip flow in microchannels  

Science Journals Connector (OSTI)

A numerical formulation of convective exergy losses in microchannels is developed. Using a new convection model (called Non-Inverted Skew Upwind Scheme (NISUS)), the predicted velocity field is post-processed to determine frictional irreversibilities within the microchannel. Boundary conditions are established from a first-order slip velocity, based on streamwise temperature gradients and transverse velocity gradients at the wall. Parametric studies are conducted for varying flow rates, channel aspect ratios, slip coefficients and pressure ratios across the microchannel. The predicted exergy destruction results provide useful new data, from which design modifications can be made to reduce power input when transporting fluid through a microchannel.

E.O.B. Ogedengbe; G.F. Naterer; M.A. Rosen

2007-01-01T23:59:59.000Z

198

Spiral-pattern formation in Rayleigh-Benard convection  

SciTech Connect (OSTI)

We present a numerical study of the spontaneous formation of spiral patterns in Rayleigh-Benard convection in non-Boussinesq fluids. We solve a generalized two-dimensional Swift-Hohenberg equation that includes a quadratic nonlinearity and coupling to mean flow. We show that this model predicts in quantitative detail many of the features observed experimentally in studies of Rayleigh-Benard convection in CO[sub 2] gas. In particular, we study the appearance and stability of a rotating spiral state obtained during the transition from an ordered hexagonal state to a roll state.

Xi, H.; Gunton, J.D. (Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)); Vinals, J. (Supercomputer Computations Research Institute, B-186, and Department of Chemical Engineering, B-203, Florida State University, Tallahassee, Florida 32306-4052 (United States))

1993-05-01T23:59:59.000Z

199

The Three-Dimensional Morphology of Simulated and Observed Convective Storms over Southern England  

Science Journals Connector (OSTI)

A set of high-resolution radar observations of convective storms has been collected to evaluate such storms in the Met Office Unified Model during the Dynamical and Microphysical Evolution of Convective Storms (DYMECS) project. The 3-GHz ...

Thorwald H. M. Stein; Robin J. Hogan; Kirsty E. Hanley; John C. Nicol; Humphrey W. Lean; Robert S. Plant; Peter A. Clark; Carol E. Halliwell

2014-09-01T23:59:59.000Z

200

Convection Initiation along Soil Moisture Boundaries in the Southern Great Plains  

Science Journals Connector (OSTI)

Boundaries between two dissimilar air masses have been shown to be the focus region for convection initiation. One feature that has been shown to create these boundaries, as well as mesoscale circulation patterns conducive for convection, is soil ...

John D. Frye; Thomas L. Mote

2010-04-01T23:59:59.000Z

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


201

The Impact of Data Assimilation Length Scales on Analysis and Prediction of Convective Storms  

Science Journals Connector (OSTI)

An idealized convective test bed for the local ensemble transform Kalman filter (LETKF) is set up to perform storm-scale data assimilation of simulated Doppler radar observations. Convective systems with lifetimes exceeding 6 h are triggered in a ...

Heiner Lange; George C. Craig

2014-10-01T23:59:59.000Z

202

Lateral Heat Exchange after the Labrador Sea Deep Convection in 2008  

Science Journals Connector (OSTI)

The mechanisms through which convected water restratifies in the Labrador Sea are still under debate. The Labrador Sea restratification after deep convection in the 2007/08 winter is studied with an eddy-resolving numerical model. The modeled ...

Weiwei Zhang; Xiao-Hai Yan

2014-12-01T23:59:59.000Z

203

Correlated spectral variability in brown dwarfs  

E-Print Network [OSTI]

Models of brown dwarf atmospheres suggest they exhibit complex physical behaviour. Observations have shown that they are indeed dynamic, displaying small photometric variations over timescales of hours. Here I report results of infrared (0.95-1.64 micron) spectrophotometric monitoring of four field L and T dwarfs spanning timescales of 0.1-5.5 hrs, the goal being to learn more about the physical nature of this variability. Spectra are analysed differentially with respect to a simultaneously observed reference source in order to remove Earth-atmospheric variations. The variability amplitude detected is typically 2-10%, depending on the source and wavelength. I analyse the data for correlated variations between spectral indices. This approach is more robust than single band or chisq analyses, because it does not assume an amplitude for the (often uncertain) noise level (although the significance test still assumes a shape for the noise power spectrum). Three of the four targets show significant evidence for correlated variability. Some of this can be associated with specific features including Fe, FeH, VO and KI, and there is good evidence for intrinsic variability in water and possibly also methan. Yet some of this variability covers a broader spectral range which would be consistent with dust opacity variations. The underlying common cause is plausibly localized temperature or composition fluctuations caused by convection. Looking at the high signal-to-noise ratio stacked spectra we see many previously identified spectral features of L and T dwarfs, such as KI, NaI, FeH, water and methane. In particular we may have detected methane absorption at 1.3-1.4 micron in the L5 dwarf SDSS 0539-0059.

C. A. L. Bailer-Jones

2007-11-28T23:59:59.000Z

204

Convective heat transfer in the nonstationary motion of a Maxwellian fluid between parallel planes  

Science Journals Connector (OSTI)

The convective heat-transfer problem is investigated for a Maxwellian fluid in generalized Couette flow in the case...

Z. P. Shul'man; É. A. Zal'tsgendler

1970-06-01T23:59:59.000Z

205

Boussinesq convection and motions of boundary spheres in a rotating spherical shell  

E-Print Network [OSTI]

RIMS­1772 Boussinesq convection and motions of boundary spheres in a rotating spherical shell #12; Boussinesq convection and motions of boundary spheres in a rotating spherical shell Keiji Kimura; Abstract Boussinesq thermal convection in rotating spheres or spherical shells has been investigated

206

Boussinesq convection and motions of boundary spheres in a rotating spherical shell  

E-Print Network [OSTI]

RIMS-1772 Boussinesq convection and motions of boundary spheres in a rotating spherical shell #12;Boussinesq convection and motions of boundary spheres in a rotating spherical shell Keiji Kimura Boussinesq thermal convection in rotating spheres or spherical shells has been investigated for over half

207

Evolution du contenu physique 1. Nouveau bloc couche limite convection nuages (nouvelle physique)  

E-Print Network [OSTI]

Evolution du contenu physique 1. Nouveau bloc couche limite ­ convection ­ nuages (nouvelle physique) ON DISPOSE D'UN NOUVEAU CADRE DE TRAVAIL. ?? - Convection /relief (Jean-Yves Grandpeix, Jingmei Yu, Alain Lahelec) ++ - glace dans la convection (Arnaud Jam, Jean-Yves Grandpeix) ?? - Modèle micro-physique

Madeleine, Jean-Baptiste

208

Review of fluid flow and convective heat transfer within rotating disk cavities  

E-Print Network [OSTI]

Review of fluid flow and convective heat transfer within rotating disk cavities with impinging jet * Corresponding author : souad.harmand@univ-valenciennes.fr Abstract Fluid flow and convective heat transfer, are treated in details in this review. The review focuses on convective heat transfer in predominantly outward

Boyer, Edmond

209

Numerical analysis of binary fluid convection in extended systems  

E-Print Network [OSTI]

arising in the primary subcritical bifurcation. The dynamics triggered by Eckhaus instability is discussed mixtures. For such mixtures, the onset of convection is via a subcritical Hopf bifurcation that gives rise of S. In the case of the experiment reported in [2] a S = -0.257 water-ethanol mixture is used. A final

Batiste, Oriol

210

A numerical study of convection with an ambient wind field  

E-Print Network [OSTI]

. The citations on the following pages follow the style of the Journal of the Atmos heric Sciences. Orville (1968) constructed a convective model based on the same equations as those used by Assi. He concerned himself with the development of cumulus clouds over...

Cottrell, Kit Garfield

1970-01-01T23:59:59.000Z

211

Constraints on mantle convection from seismic tomography and flow modeling  

E-Print Network [OSTI]

In this thesis I combine high resolution seismic tomography and realistic flow modeling to constrain mantle convection. The bulk of the data used in the tomographic imaging are millions of P, pP and pwP travel time residuals, ...

Kárason, Hrafnkell, 1970-

2002-01-01T23:59:59.000Z

212

The Influence of Wind Speed on Shallow Marine Cumulus Convection  

Science Journals Connector (OSTI)

The role of wind speed on shallow marine cumulus convection is explored using large-eddy simulations and concepts from bulk theory. Focusing on cases characteristic of the trades, the equilibrium trade wind layer is found to be deeper at stronger ...

Louise Nuijens; Bjorn Stevens

2012-01-01T23:59:59.000Z

213

Toward the Long-range Prediction of Severe Convective Windstorms  

E-Print Network [OSTI]

thunderstorm systems (or mesoscale convective system (MCS)), cause major disruption to society, including widespread power outages, tree and structural damage, and transportation accidents that affect multi- state � Left five million without power � Traveled 700 miles in 12 hours #12;June 2012 Derecho Overview http

Kuligowski, Bob

214

Development of Ensemble Neural Network Convection Parameterizations for Climate Models  

SciTech Connect (OSTI)

The novel neural network (NN) approach has been formulated and used for development of a NN ensemble stochastic convection parametrization for climate models. This fast parametrization is built based on data from Cloud Resolving Model (CRM) simulations initialized with and forced by TOGA-COARE data. The SAM (System for Atmospheric Modeling), developed by D. Randall, M. Khairoutdinov, and their collaborators, has been used for CRM simulations. The observational data are also used for validation of model simulations. The SAM-simulated data have been averaged and projected onto the GCM space of atmospheric states to implicitly define a stochastic convection parametrization. This parametrization is emulated using an ensemble of NNs. An ensemble of NNs with different NN parameters has been trained and tested. The inherent uncertainty of the stochastic convection parametrization derived in such a way is estimated. Due to these inherent uncertainties, NN ensemble is used to constitute a stochastic NN convection parametrization. The developed NN convection parametrization have been validated in a diagnostic CAM (CAM-NN) run vs. the control CAM run. Actually, CAM inputs have been used, at every time step of the control/original CAM integration, for parallel calculations of the NN convection parametrization (CAM-NN) to produce its outputs as a diagnostic byproduct. Total precipitation (P) and cloudiness (CLD) time series, diurnal cycles, and P and CLD distributions for the large Tropical Pacific Ocean for the parallel CAM-NN and CAM runs show similarity and consistency with the NCEP reanalysis. The P and CLD distributions for the tropical area for the parallel runs have been analyzed first for the TOGA-COARE boreal winter season (November 1992 through February 1993) and then for the winter seasons of the follow-up parallel decadal simulations. The obtained results are encouraging and practically meaningful. They show the validity of the NN approach. This constitutes an important practical conclusion of the study: the obtained results on NN ensembles as a stochastic physics parametrization show a realistic possibility of development of NN convection parametrization for climate (and NWP) models based on learning cloud physics from CRM/SAM simulated data.

Fox-Rabinovitz, M. S.; Krasnopolsky, V. M.

2012-05-02T23:59:59.000Z

215

A Comparison of Precipitation Forecast Skill between Small Convection-Allowing and Large Convection-Parameterizing Ensembles  

E-Print Network [OSTI]

Submitted to Weather and Forecasting in October 2008, Accepted in January 2009 * Corresponding author) Weather Research and Forecasting (WRF) model ensemble, which cover a similar domain over the central-convection resolution (PCR) ensembles. Computation of various precipitation skill metrics for probabilistic

Droegemeier, Kelvin K.

216

Modeling the Dynamical Coupling of Solar Convection with the Radiative Interior  

Science Journals Connector (OSTI)

The global dynamics of a rotating star like the Sun involves the coupling of a highly turbulent convective envelope overlying a seemingly benign radiative interior. We use the anelastic spherical harmonic code to develop a new class of three-dimensional models that nonlinearly couple the convective envelope to a deep stable radiative interior. The numerical simulation assumes a realistic solar stratification from r = 0.07 up to 0.97R (with R the solar radius), thus encompassing part of the nuclear core up through most of the convection zone. We find that a tachocline naturally establishes itself between the differentially rotating convective envelope and the solid body rotation of the interior, with a slow spreading that is here diffusively controlled. The rapid angular momentum redistribution in the convective envelope leads to a fast equator and slow poles, with a conical differential rotation achieved at mid-latitudes, much as has been deduced by helioseismology. The convective motions are able to overshoot downward about 0.04R into the radiative interior. However, the convective meridional circulation there is confined to a smaller penetration depth and is directed mostly equatorward at the base of the convection zone. Thermal wind balance is established in the lower convection zone and tachocline but departures are evident in the upper convection zone. Internal gravity waves are excited by the convective overshooting, yielding a complex wave field throughout the radiative interior.

Allan Sacha Brun; Mark S. Miesch; Juri Toomre

2011-01-01T23:59:59.000Z

217

Scaling Laws for Convection with Temperature-dependent Viscosity and Grain-damage  

E-Print Network [OSTI]

Numerical experiments of convection with grain-damage are used to develop scaling laws for convective heat flow, mantle velocity, and plate velocity across the stagnant lid and plate-tectonic regimes. Three main cases are presented in order of increasing complexity: a simple case wherein viscosity is only dependent on grainsize, a case where viscosity depends on temperature and grainsize, and finally a case where viscosity is temperature and grainsize sensitive, and the grain-growth (or healing) is also temperature sensitive. In all cases, convection with grain-damage scales differently than Newtonian convection due to the effects of grain-damage. For the fully realistic case, numerical results show stagnant lid convection, fully mobilized convection that resembles the temperature-independent viscosity case, and partially mobile or transitional convection, depending on damage to healing ratio, Rayleigh number, and the activation energies for viscosity and healing. Applying our scaling laws for the fully reali...

Foley, Bradford J

2014-01-01T23:59:59.000Z

218

Evaluation of a Modified Scheme for Shallow Convection: Implementation of CuP and Case Studies  

SciTech Connect (OSTI)

A new treatment for shallow clouds has been introduced into the Weather Research and Forecasting (WRF) model. The new scheme, called the cumulus potential (CuP) scheme, replaces the ad-hoc trigger function used in the Kain-Fritsch cumulus parameterization with a trigger function related to the distribution of temperature and humidity in the convective boundary layer via probability density functions (PDFs). An additional modification to the default version of WRF is the computation of a cumulus cloud fraction based on the time scales relevant for shallow cumuli. Results from three case studies over the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) site in north central Oklahoma are presented. These days were selected because of the presence of shallow cumuli over the ARM site. The modified version of WRF does a much better job predicting the cloud fraction and the downwelling shortwave irradiance thancontrol simulations utilizing the default Kain-Fritsch scheme. The modified scheme includes a number of additional free parameters, including the number and size of bins used to define the PDF, the minimum frequency of a bin within the PDF before that bin is considered for shallow clouds to form, and the critical cumulative frequency of bins required to trigger deep convection. A series of tests were undertaken to evaluate the sensitivity of the simulations to these parameters. Overall, the scheme was found to be relatively insensitive to each of the parameters.

Berg, Larry K.; Gustafson, William I.; Kassianov, Evgueni I.; Deng, Liping

2013-01-01T23:59:59.000Z

219

ARM - Field Campaign - COPS - Initiation of Convection and the  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

govCampaignsCOPS - Initiation of Convection and the Microphysical govCampaignsCOPS - Initiation of Convection and the Microphysical Properties of Clouds in Orographic Terrain Campaign Links AMF Black Forest Deployment Related Campaigns COPS - AOS Intercomparison 2007.08.09, Jefferson, AMF COPS - ADMIRARI at Black Forest 2007.07.30, Battaglia, AMF COPS - University of Cologne Micromet Station 2007.07.23, Schween, AMF COPS - Cloud Microwave Validation Experiment in Support of CLOWD 2007.06.22, Vogelmann, AMF COPS - WILI Coherent Doppler Wind Lidar at Black Forest 2007.05.10, Althausen, AMF COPS - Multi Wavelength Raman Lidar (MWL) at Black Forest 2007.05.10, Althausen, AMF COPS - 35.5 GHz Cloud Radar Comparison at Black Forest 2007.05.01, Handwerker, AMF COPS - HATPRO at Black Forest 2007.04.01, Crewell, AMF COPS - Micro-Rain Radar at Black Forest

220

Natural convection heating system: off-the-wall evaluation methods  

SciTech Connect (OSTI)

One day data collection results are described for supplementary monitoring of convective air collectors coupled with rock bin storage for house heating. This particular 100% passive heated solar house in the mountains of Arizona had been extensively monitored and previously reported. New information includes the performance of collectors and storage during changeable insolation. In addition, there are evaluations of the alternative techniques for monitoring leakage of dampers on delivery registers, an empirical technique for determining the thermal contribution of direct gain features, and subjective responses of owners to the quality of convective and radiative comfort. Warm is warm, said the owner-builders. Design recommendations for future systems are made and a testing method using a bag volumeter is described. Post-occupancy evaluation is strongly recommended.

Cook, J.; Morris, W.S.

1981-01-01T23:59:59.000Z

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


221

Bifurcation analysis of interacting stationary modes in thermohaline convection  

SciTech Connect (OSTI)

The Boussinesq equations for thermohaline convection in a finite two-dimensional box and with stress-free boundaries are considered. There are critical values of the aspect ratio at which the conduction state becomes unstable to two different roll patterns simultaneously. Near such a critical value a center manifold reduction allows us to reduce the dynamical behavior of the Boussinesq equations to a standard normal form equation that describes the interaction of two stationary modes. We present explicit analytical expressions for the linear and nonlinear coefficients on which the normal form depends. A numerical investigation of these coefficients leads to a division of the space of parameters (Prandtl number, solute Rayleigh number, Lewis number) into various regions that give rise to qualitatively different bifurcation behavior. Besides those encountered in ordinary convection, a variety of further phenomena is found, in particular in a vicinity of double tricritical points.

Neveling, M.; Dangelmayr, G.

1988-09-01T23:59:59.000Z

222

Using stochastic analysis to capture unstable equilibrium in natural convection  

SciTech Connect (OSTI)

A stabilized stochastic finite element implementation for the natural convection system of equations under Boussinesq assumptions with uncertainty in inputs is considered. The stabilized formulations are derived using the variational multiscale framework assuming a one-step trapezoidal time integration rule. The stabilization parameters are shown to be functions of the time-step size. Provision is made for explicit tracking of the subgrid-scale solution through time. A support-space/stochastic Galerkin approach and the generalized polynomial chaos expansion (GPCE) approach are considered for input-output uncertainty representation. Stochastic versions of standard Rayleigh-Benard convection problems are used to evaluate the approach. It is shown that for simulations around critical points, the GPCE approach fails to capture the highly non-linear input uncertainty propagation whereas the support-space approach gives fairly accurate results. A summary of the results and findings is provided.

Asokan, Badrinarayanan Velamur [Materials Process Design and Control Laboratory, Sibley School of Mechanical and Aerospace Engineering, 188 Frank H.T. Rhodes Hall, Cornell University, Ithaca, NY 14853-3801 (United States); Zabaras, Nicholas [Materials Process Design and Control Laboratory, Sibley School of Mechanical and Aerospace Engineering, 188 Frank H.T. Rhodes Hall, Cornell University, Ithaca, NY 14853-3801 (United States)]. E-mail: zabaras@cornell.edu

2005-09-01T23:59:59.000Z

223

Magnetic particle mixing with magnetic micro-convection for microfluidics  

Science Journals Connector (OSTI)

Abstract In this paper we discuss the magnetic micro-convection phenomenon as a tool for mixing enhancement in microfluidics systems in cases when one of the miscible fluids is a magnetic particle colloid. A system of a water-based magnetic fluid and water is investigated experimentally under homogeneous magnetic field in a Hele–Shaw cell. Subsequent image analysis both qualitatively and quantitatively reveals the high enhancement of mixing efficiency provided by this method. The mixing efficiency dependence on the magnetic field and the physical limits is discussed. A suitable model for a continuous-flow microfluidics setup for mixing with magnetic micro-convection is also proposed and justified with an experiment. In addition, possible applications in improving the speed of ferrohydrodynamic sorting and magnetic label or selected tracer mixing in lab on a chip systems are noted.

Guntars Kitenbergs; Kaspars E¯rglis; Régine Perzynski; Andrejs C?bers

2014-01-01T23:59:59.000Z

224

The CHUVA Project how does convection vary across the Brazil?  

E-Print Network [OSTI]

1 The CHUVA Project ­ how does convection vary across the Brazil? Luiz A. T. Machado1 , Maria A. F de Previsão de Tempo e Estudos Climáticos (CPTEC), Brazil. 2. Universidade de São Paulo. Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Brazil. 3. Departamento de Ciências e Tecnologia Espacial

Chaboureau, Jean-Pierre

225

Non-Boussinesq effects in free thermal convection  

Science Journals Connector (OSTI)

Non-Boussinesq effects in a Rayleigh-Bénard convection system lead to a symmetry breaking between the top and the bottom boundary layers. We have found that the two layers adjust their temperature drops and the thicknesses ? such that their temperature scales ??/g??3 are equal, where ? is the thermal expansion coefficient, g is the gravitational acceleration, and ? and ? are the kinematic viscosity and thermal diffusivity, respectively.

Xiao-Zhong Wu and Albert Libchaber

1991-03-15T23:59:59.000Z

226

STELLAR DYNAMOS AND CYCLES FROM NUMERICAL SIMULATIONS OF CONVECTION  

SciTech Connect (OSTI)

We present a series of kinematic axisymmetric mean-field ?? dynamo models applicable to solar-type stars, for 20 distinct combinations of rotation rates and luminosities. The internal differential rotation and kinetic helicity profiles required to calculate source terms in these dynamo models are extracted from a corresponding series of global three-dimensional hydrodynamical simulations of solar/stellar convection, so that the resulting dynamo models end up involving only one free parameter, namely, the turbulent magnetic diffusivity in the convecting layers. Even though the ?? dynamo solutions exhibit a broad range of morphologies, and sometimes even double cycles, these models manage to reproduce relatively well the observationally inferred relationship between cycle period and rotation rate. On the other hand, they fail in capturing the observed increase of magnetic activity levels with rotation rate. This failure is due to our use of a simple algebraic ?-quenching formula as the sole amplitude-limiting nonlinearity. This suggests that ?-quenching is not the primary mechanism setting the amplitude of stellar magnetic cycles, with magnetic reaction on large-scale flows emerging as the more likely candidate. This inference is coherent with analyses of various recent global magnetohydrodynamical simulations of solar/stellar convection.

Dubé, Caroline; Charbonneau, Paul, E-mail: dube@astro.umontreal.ca, E-mail: paulchar@astro.umontreal.ca [Département de Physique, Université de Montréal, C.P. 6128 Succ. Centre-ville, Montréal, QC H3C 3J7 (Canada)

2013-09-20T23:59:59.000Z

227

Breakdown of large-scale circulation in turbulent rotating convection  

Science Journals Connector (OSTI)

Turbulent rotating convection in a cylinder is investigated both numerically and experimentally at Rayleigh number Ra=109 and Prandtl number ?=6.4. In this letter we discuss two topics: the breakdown under rotation of the domain-filling large-scale circulation (LSC) typical for confined convection, and the convective heat transfer through the fluid layer, expressed by the Nusselt number. The presence of the LSC is addressed for several rotation rates. For Rossby numbers Ro1.2 no LSC is found (the Rossby number indicates relative importance of buoyancy over rotation, hence small Ro indicates strong rotation). For larger Rossby numbers a precession of the LSC in anticyclonic direction (counter to the background rotation) is observed. It is shown that the heat transfer has a maximal value close to Ro=0.18 being about 15% larger than in the non-rotating case Ro=?. Since the LSC is no longer present at this Rossby value we conclude that the peak heat transfer is independent of the LSC.

R. P. J. Kunnen; H. J. H. Clercx; B. J. Geurts

2008-01-01T23:59:59.000Z

228

Variable frequency microwave heating apparatus  

DOE Patents [OSTI]

A variable frequency microwave heating apparatus (10) designed to allow modulation of the frequency of the microwaves introduced into a multi-mode microwave cavity (34) for testing or other selected applications. The variable frequency microwave heating apparatus (10) includes a microwave signal generator (12) and a high-power microwave amplifier (20) or a high-power microwave oscillator (14). A power supply (22) is provided for operation of the high-power microwave oscillator (14) or microwave amplifier (20). A directional coupler (24) is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity (34). A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Bible, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN); Johnson, Arvid C. (Lake in the Hills, IL); Thigpen, Larry T. (Angier, NC)

1999-01-01T23:59:59.000Z

229

Morphological Evolution of Thermal Plumes in Turbulent Rayleigh-Bénard Convection  

Science Journals Connector (OSTI)

An experimental study of the morphological evolution of thermal plumes in turbulent thermal convection is presented. Individual sheetlike plumes are extracted and their area, circumference, and “heat content” are found to all exhibit log-normal distributions. As the sheetlike plumes move across the plate they collide and convolute into spiraling swirls. These swirls then spiral away from the plates to become mushroomlike plumes which are accompanied by strong vertical vorticity. The measured profiles of plume numbers and of vertical vorticity quantify the morphological transition of sheetlike plumes to mushroomlike ones and the mixing and merging or clustering of mushroomlike plumes. The fluctuating vorticity is found to have the same exponential distribution and scaling behavior as the fluctuating temperature.

Quan Zhou; Chao Sun; Ke-Qing Xia

2007-02-12T23:59:59.000Z

230

A three-dimensional numerical model of dry convection in an ambient wind field  

E-Print Network [OSTI]

effects of the ambient wind field on convection. Nost of the numerical results are shown to correspond to empirical observations, while some results are unexpected but reasonable. Nechanical and thermal energy equations have been developed... to investigate the effects on convection of an The citations on the following pages follow the tyl of th J* J of ~At * h ' f ambient wind with a vertical shear He also examined the energy interactions between convective flow and nean flows. There were many...

Burgeson, John Carl

2012-06-07T23:59:59.000Z

231

Comparisons of Two- and Three-Dimensional Convection in Type I X-ray Bursts  

E-Print Network [OSTI]

We perform the first detailed three-dimensional simulation of low Mach number convection preceding thermonuclear ignition in a mixed H/He X-ray burst. Our simulations include a moderate-sized, approximate network that captures hydrogen and helium burning up through rp-process breakout. We look in detail at the difference between two- and three-dimensional convective fields, including the details of the turbulent convection.

Zingale, M; Nonaka, A; Almgren, A S; Bell, J B

2014-01-01T23:59:59.000Z

232

Variable Frequency Drives  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

How BPA Supports VFDs Rebates are available from your utility for Variable Frequency Drives on pumps 20hp or greater and storage fans.. Energy savings from VFDs vary and can...

233

Damping of Type I X-ray Burst Oscillations by Convection  

E-Print Network [OSTI]

I construct a simple model of the convective burning layer during a type I X-ray burst to investigate the effects convection has on the stability of the layer to nonradial oscillations. A linear perturbation analysis demonstrates that the region is stable to nonradial oscillations when energy transport is convection-dominated, but it is unstable when energy transport is radiation-dominated. Thus, efficient convection always dampens oscillations. These results may explain the nondetection of oscillations during the peak of some X-ray bursts.

Randall L. Cooper

2008-03-26T23:59:59.000Z

234

Convection in X-ray Bursts Michael Zingale Stony Brook University  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

many stellar systems dominated by convective transport of energy - Supernovae (both thermonuclear and gravitational) - X-ray bursts and novae (thermonuclear explosion of accreted...

235

A numerical study of mesoscale convection in a rotating tropical atmosphere  

E-Print Network [OSTI]

similar to the profile of a tropical disturbance. The meso-p forcing of convection consisted of' seven temperature perturbations con- fined below 2. 4 km at intervals of 8 km out to 60 km. The meso-9 forcing of convection comprised of a cosine thermal... perturbation field out to 75 km. Two different classes of simulations were performed. The first part explored how background vorticity affects convection generated by meso-7 and meso-9 forcing. The second part investigated how meso-9 forcing of convection...

Fitzpatrick, Patrick James

1992-01-01T23:59:59.000Z

236

Interference mechanisms of acoustic/convective disturbances in a swirl-stabilized lean-premixed combustor  

Science Journals Connector (OSTI)

Interference mechanisms of acoustic/convective disturbances were experimentally investigated in a swirl-stabilized lean-premixed gas turbine combustor operated with natural gas fuel and air at atmospheric pressure and elevated temperature. Interference between azimuthal and acoustic velocity disturbances at high-amplitude limit cycle oscillations is characterized in detail as a function of axial swirler location, oscillation frequency, and mean nozzle velocity. We show that both the frequency and the intensity of self-excited instabilities in a model gas turbine combustor are correlated with axial swirler position, which indicates that a vorticity wave generated at the swirl vanes is a primary source of convective disturbances in the absence of equivalence ratio nonuniformities. Flame transfer function measurements confirm that the linear/nonlinear heat release response is a strong function of axial swirler location, even when unforced flame structures remain unchanged. The key parameter controlling this phenomenon is the phase difference between the azimuthal and acoustic velocity perturbations at the combustor dump plane; the phase difference is affected by swirler location, frequency, mean velocity, and the speed of sound. It was found that out-of-phase interference between azimuthal and acoustic velocity disturbances at the combustor inlet yields large flame angle fluctuations in relation to swirl number fluctuations, and therefore the formation of a coherent structure is hindered due to high kinematic viscosity within the vortex formation region. In-phase interference mechanisms, on the other hand, lead to high-amplitude limit cycle oscillations. This interference mechanism is then explored in the presence of temporal equivalence ratio nonuniformities, in which two different sources of convective mechanisms should be considered simultaneously in connection with acoustic velocity perturbations and the vortex dynamics. Results reveal that equivalence ratio oscillation has a significant effect on the strength of combustion-acoustic interactions. Strong self-excited instabilities of partially premixed flames are produced by in-phase interactions between acoustic velocity and equivalence ratio oscillations, which are governed by fuel injection location, frequency, mean nozzle velocity, and fuel injector impedance. At this phase condition, unburned reactants with high equivalence ratio impinge on the flame front with high inlet velocity, potentially causing large fluctuations of heat release rate.

Kyu Tae Kim; Dom A. Santavicca

2013-01-01T23:59:59.000Z

237

CONVECTION AND DIFFERENTIAL ROTATION IN F-TYPE STARS  

SciTech Connect (OSTI)

Differential rotation is a common feature of main-sequence spectral F-type stars. In seeking to make contact with observations and to provide a self-consistent picture of how differential rotation is achieved in the interiors of these stars, we use the three-dimensional anelastic spherical harmonic (ASH) code to simulate global-scale turbulent flows in 1.2 and 1.3 M{sub Sun} F-type stars at varying rotation rates. The simulations are carried out in spherical shells that encompass most of the convection zone and a portion of the stably stratified radiative zone below it, allowing us to explore the effects of overshooting convection. We examine the scaling of the mean flows and thermal state with rotation rate and mass and link these scalings to fundamental parameters of the simulations. Indeed, we find that the differential rotation becomes much stronger with more rapid rotation and larger mass, scaling as {Delta}{Omega}{proportional_to}M {sup 3.9}{Omega}{sup 0.6}{sub 0}. Accompanying the growing differential rotation is a significant latitudinal temperature contrast, with amplitudes of 1000 K or higher in the most rapidly rotating cases. This contrast in turn scales with mass and rotation rate as {Delta}T{proportional_to}M {sup 6.4}{Omega}{sup 1.6}{sub 0}. On the other hand, the meridional circulations become much weaker with more rapid rotation and with higher mass, with their kinetic energy decreasing as KE{sub MC}{proportional_to}M {sup -1.2}{Omega}{sup -0.8}{sub 0}. Additionally, three of our simulations exhibit a global-scale shear instability within their stable regions that persists for the duration of the simulations. The flow structures associated with the instabilities have a direct coupling to and impact on the flows within the convection zone.

Augustson, Kyle C.; Toomre, Juri [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Brown, Benjamin P. [Department of Astronomy and Center for Magnetic Self-Organization (CMSO) in Laboratory and Astrophysical Plasmas, University of Wisconsin, Madison, WI 53706-1582 (United States); Brun, Allan Sacha [DSM/IRFU/SAp, CEA-Saclay and UMR AIM, CEA-CNRS-Universite Paris 7, F-91191 Gif-sur-Yvette (France); Miesch, Mark S., E-mail: Kyle.Augustson@colorado.edu [High Altitude Observatory, Center Green 1, Boulder, CO 80301 (United States)

2012-09-10T23:59:59.000Z

238

Natural convection in high heat flux tanks at the Hanford Waste Site / [by] Mark van der Helm and Mujid S. Kazimi  

E-Print Network [OSTI]

A study was carried out on the potential for natural convection and the effect of natural convection in a High Heat Flux Tank, Tank 241-C-106, at the Hanford Reservation. To determine the existence of natural convection, ...

Van der Helm, Mark Johan, 1972-

1996-01-01T23:59:59.000Z

239

Convection in magnetic fluids with internal heat generation  

SciTech Connect (OSTI)

The effect of a uniform distribution of heat source on the onset of stationary convection in a horizontal Boussinesq magnetic fluid layer bounded by isothermal nonmagnetic boundary is investigated. Solutions are obtained using a higher order Galerkin expansion technique, considering different isothermal boundary combinations (rigid-rigid, rigid-free, and free-free). It is found that the effect of internal magnetic number, due to a heat source, is to make the system more unstable. The results obtained, in the limiting cases, compare well with the existing literature.

Rudraiah, N.; Sekhar, G.N. (Bangalore Univ. (India))

1991-02-01T23:59:59.000Z

240

Defect Chaos of Oscillating Hexagons in Rotating Convection  

SciTech Connect (OSTI)

Using coupled Ginzburg-Landau equations, the dynamics of hexagonal patterns with broken chiral symmetry are investigated, as they appear in rotating non-Boussinesq or surface-tension-driven convection. We find that close to the secondary Hopf bifurcation to oscillating hexagons the dynamics are well described by a single complex Ginzburg-Landau equation (CGLE) coupled to the phases of the hexagonal pattern. At the band center these equations reduce to the usual CGLE and the system exhibits defect chaos. Away from the band center a transition to a frozen vortex state is found. (c) 2000 The American Physical Society.

Echebarria, Blas; Riecke, Hermann

2000-05-22T23:59:59.000Z

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


241

Granular fountains: Convection cascade in a compartmentalized granular gas  

Science Journals Connector (OSTI)

This paper extends the two-compartment granular fountain [D. van der Meer, P. Reimann, K. van der Weele, and D. Lohse, Phys. Rev. Lett. 92, 184301 (2004)] to an arbitrary number of compartments: The tendency of a granular gas to form clusters is exploited to generate spontaneous convective currents, with particles going down in the well-filled compartments and going up in the diluted ones. We focus upon the bifurcation diagram of the general K-compartment system, which is constructed using a dynamical flux model and which proves to agree quantitatively with results from molecular dynamics simulations.

Devaraj van der Meer; Ko van der Weele; Peter Reimann

2006-06-22T23:59:59.000Z

242

Generation of large-scale winds in horizontally anisotropic convection  

E-Print Network [OSTI]

We simulate three-dimensional, horizontally periodic Rayleigh-B\\'enard convection between free-slip horizontal plates, rotating about a horizontal axis. When both the temperature difference between the plates and the rotation rate are sufficiently large, a strong horizontal wind is generated that is perpendicular to both the rotation vector and the gravity vector. The wind is turbulent, large-scale, and vertically sheared. Horizontal anisotropy, engendered here by rotation, appears necessary for such wind generation. Most of the kinetic energy of the flow resides in the wind, and the vertical turbulent heat flux is much lower on average than when there is no wind.

von Hardenberg, J; Provenzale, A; Spiegel, E A

2015-01-01T23:59:59.000Z

243

Density measurements Viscosity measurements  

E-Print Network [OSTI]

Density measurements Viscosity measurements Temperature measurements Pressure measurements Flow rate measurements Velocity measurements Sensors How to measure fluid flow properties ? Am´elie Danlos Ravelet Experimental methods for fluid flows: an introduction #12;Density measurements Viscosity

Ravelet, Florent

244

Variable Frequency Pump Drives  

E-Print Network [OSTI]

-frequency electric motor drive. What is happenin9 with variable frequency driven pun,ps is a classical illustration that evolution in technical products takes place not only because of changes in the processes served by these products, or because of innovations...-pole 3550 rpm squirrel caqe induction motor became available in the early 1930s that high pressure pumps operating at that speed could be buil t. And now, in the 1980s, the development of the solid-state, variable frequency electric motor drive...

Karassik, I. J.; Petraccaro, L. L.; McGuire, J. T.

245

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

SciTech Connect (OSTI)

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

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

1996-06-01T23:59:59.000Z

246

Non-Boussinesq rolls in 2d thermal convection  

Science Journals Connector (OSTI)

Abstract A study of convection in a circular two dimensional cell is presented. The system is heated and cooled at two diametrically opposed points on the edge of the circle, which are parallel or anti-parallel to gravity. The latter’s role in the plane of the cell can be changed by tilting the cell. When the system is in a horizontal position, a non-trivial analytic solution for the temperature distribution of the quiescent fluid can be found. For a slight inclination, the projection of gravity in the plane of the cell is used as a perturbation parameter in the full hydrodynamic description, as the Boussinesq approximation is unjustified. To first order, the equations are solved for the stationary case and four symmetrical rolls become apparent, showing that a purely conductive state is impossible if gravity–however small–is present; an approximate closed analytical expression is obtained, which describes the four convection rolls. Further analysis is done by a direct numerical integration. Comparison with preliminary observations is mentioned.

C. Málaga; F. Mandujano; R. Peralta-Fabi; C. Arzate

2015-01-01T23:59:59.000Z

247

Non-Boussinesq Rolls in 2d Thermal Convection  

E-Print Network [OSTI]

A study of convection in a circular two dimensional cell is presented. The system is heated and cooled at two diametrically opposed points on the edge of the circle, which are parallel or anti-parallel to gravity. The latter's role in the plane of the cell can be changed by tilting the cell. When the system is in a horizontal position, a non-trivial analytic solution for the temperature distribution of the quiescent fluid can be found. For a slight inclination, the projection of gravity in the plane of the cell is used as a perturbation parameter in the full hydrodynamic description, as the Boussinesq approximation is inadequate. To first order, the equations are solved for the stationary case and four symmetrical rolls become apparent, showing that a purely conductive state is impossible if gravity -however small- is present; an approximate closed analytical expression is obtained, which describes the four convection rolls. Further analysis is done by a direct numerical integration. Comparison with prelimina...

Málaga, C; Peralta-Fabi, R; Arzate, C

2013-01-01T23:59:59.000Z

248

Special session: computational predictability of natural convection flows in enclosures  

SciTech Connect (OSTI)

Modern thermal design practices often rely on a ''predictive'' simulation capability--although predictability is rarely quantified and often difficult to confidently achieve in practice. The computational predictability of natural convection in enclosures is a significant issue for many industrial thermal design problems. One example of this is the design for mitigation of optical distortion due to buoyancy-driven flow in large-scale laser systems. In many instances the sensitivity of buoyancy-driven enclosure flows can be linked to the presence of multiple bifurcation points that yield laminar thermal convective processes that transition from steady to various modes of unsteady flow. This behavior is brought to light by a problem as ''simple'' as a differentially-heated tall rectangular cavity (8:1 height/width aspect ratio) filled with a Boussinesq fluid with Pr = 0.71--which defines, at least partially, the focus of this special session. For our purposes, the differentially-heated cavity provides a virtual fluid dynamics laboratory.

Christon, M A; Gresho, P M; Sutton, S B

2000-08-14T23:59:59.000Z

249

Neutrino-driven convection versus advection in core collapse supernovae  

E-Print Network [OSTI]

A toy model is analyzed in order to evaluate the linear stability of the gain region immediately behind a stalled accretion shock, after core bounce. This model demonstrates that a negative entropy gradient is not sufficient to warrant linear instability. The stability criterion is governed by the ratio \\chi of the advection time through the gain region divided by the local timescale of buoyancy. The gain region is linearly stable if \\chi3, perturbations are unstable in a limited range of horizontal wavelengths centered around twice the vertical size H of the gain region. The threshold horizontal wavenumbers k_{min} and k_{max} follow simple scaling laws such that Hk_{min}\\propto 1/{\\chi} and Hk_{max}\\propto \\chi. The convective stability of the l=1 mode in spherical accretion is discussed, in relation with the asymmetric explosion of core collapse supernovae. The advective stabilization of long wavelength perturbations weakens the possible influence of convection alone on a global l=1 mode.

T. Foglizzo; L. Scheck; H. -Th. Janka

2005-07-27T23:59:59.000Z

250

LE JOURNAL DE PHYSIQUE NON BOUSSINESQ CONVECTIVE STRUCTURES IN WATER NEAR 4 C  

E-Print Network [OSTI]

LE JOURNAL DE PHYSIQUE NON BOUSSINESQ CONVECTIVE STRUCTURES IN WATER NEAR 4 °C M. DUBOIS, P. BERGE répondant à l'approximation de Boussinesq. On trouve en particulier des structures convectives hexagonales profile of such a layer produces qualitatively different behaviour from that observed in « Boussinesq

Paris-Sud XI, Université de

251

Pattern formation in binary mixture convection in cylindrical three-dimensional cells  

E-Print Network [OSTI]

present numerical results of pattern selection near the onset of convection for a water-ethanol mixture of the cell is = 11. The onset of convection occurs via a subcritical Hopf bifurcation. Slightly above ratio mixtures, S subcritical and gives rise

Batiste, Oriol

252

Lattice Boltzmann model for melting with natural convection Christian Huber a,*, Andrea Parmigiani b  

E-Print Network [OSTI]

Lattice Boltzmann model for melting with natural convection Christian Huber a,*, Andrea Parmigiani Boltzmann Heat transfer Melting Convection a b s t r a c t We develop a lattice Boltzmann method to couple and Stefan numbers) over which the correlations have been tested remains limited. The lattice Boltzmann

Manga, Michael

253

A LATTICE BOLTZMANN MODEL FOR CONVECTION HEAT TRANSFER IN POROUS MEDIA  

E-Print Network [OSTI]

A LATTICE BOLTZMANN MODEL FOR CONVECTION HEAT TRANSFER IN POROUS MEDIA Zhaoli Guo and T. S. Zhao Kong, China A lattice Boltzmann model for convection heat transfer in porous media is proposed-difference, finite-volume, and finite-element methods (e.g., [2, 3]). The lattice Boltzmann method (LBM

Zhao, Tianshou

254

Review of fluid flow and convective heat transfer within rotating disk cavities  

E-Print Network [OSTI]

1 Review of fluid flow and convective heat transfer within rotating disk cavities with impinging axial direction #12;5 Introduction Fluid flow and convective heat transfer in rotor-stator configuration heat transfer in rotor-stator configurations, which are of great importance in different engineering

Paris-Sud XI, Université de

255

Improving Convection Parameterization Using ARM Observations and NCAR Community Atmosphere Model  

SciTech Connect (OSTI)

Highlight of Accomplishments: We made significant contribution to the ASR program in this funding cycle by better representing convective processes in GCMs based on knowledge gained from analysis of ARM/ASR observations. In addition, our work led to a much improved understanding of the interaction among aerosol, convection, clouds and climate in GCMs.

Zhang, Guang J [Scripps Institution of Oceanography

2013-07-29T23:59:59.000Z

256

HEAT TRANSFERS IN A DOUBLE SKIN ROOF VENTILATED BY NATURAL CONVECTION IN SUMMER TIME  

E-Print Network [OSTI]

1 HEAT TRANSFERS IN A DOUBLE SKIN ROOF VENTILATED BY NATURAL CONVECTION IN SUMMER TIME P. H or in tropical and arid countries. In this work, radiation, convection and conduction heat transfers-dimensional numerical simulation of the heat transfers through the double skin reveals the most important parameters

Boyer, Edmond

257

Numerical study of natural convection in a vertical porous annulus with discrete heating  

E-Print Network [OSTI]

Numerical study of natural convection in a vertical porous annulus with discrete heating M. Sankar online 20 December 2010 Keywords: Natural convection Annulus Discrete heating Porous medium Radii ratio to discrete heating. The outer wall is maintained iso- thermally at a lower temperature, while the top

Lopez, John M.

258

Benchmark solution for a three-dimensional mixed convection flow -Detailed technical report  

E-Print Network [OSTI]

in many industrial applications: thermal and chemical reactors, chimneys, solar collectors, thermal-dimensional mixed convection flow in a horizontal rectangular channel heated from below and cooled from above) configuration (i.e. mixed convection flows in horizontal rectan- gular channels heated from below

Boyer, Edmond

259

Environment and the Lifetime of Tropical Deep Convection in a Cloud-Permitting Regional Model Simulation  

SciTech Connect (OSTI)

By applying a cloud tracking algorithm to tropical convective systems simulated by a regional high resolution model, the study documents environmental conditions before and after convective systems are initiated over ocean and land by following them during their lifetime. The comparative roles of various environmental fields in affecting the lifetime of convection are also quantified. The statistics of lifetime, maximum area, propagation speed and direction of the simulated deep convection agrees well with geostationary satellite observations. Over ocean, convective systems enhance surface fluxes through the associated wind gusts as well as cooling and drying of the boundary layer. A significant relationship is found between the mean surface fluxes during their lifetime and the longevity of the systems which in turn is related to the initial intensity of the moist updraft and to a lesser extent upper level shear. Over land, on the other hand, convective activity suppresses surface fluxes through cloud cover and the lifetime of convection is related to the upper level shear during their lifetime and strength of the heat fluxes several hours before the initiation of convection. For systems of equal lifetime, those over land are significantly more intense than those over ocean especially during early stages of their lifetime.

Hagos, Samson M.; Feng, Zhe; McFarlane, Sally A.; Leung, Lai-Yung R.

2013-08-01T23:59:59.000Z

260

THE EFFECT OF A SHEAR FLOW ON CONVECTION NEAR A TWO-DIMENSIONAL HOT-PATCH  

Science Journals Connector (OSTI)

......CONVECTION NEAR A TWO-DIMENSIONAL HOT-PATCH I. C. WALTON Department of Mathematics...takes the form of a two-dimensional hot-patch. Ingersoll's (6) results for uniform...CONVECTION NEAR A TWO-DIMENSIONAL HOT-PATCH By I. C. WALTON (Department of Mathematics......

I. C. WALTON

1985-11-01T23:59:59.000Z

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


261

THE MAGNETIC CONNECTION BETWEEN THE CONVECTION ZONE AND CORONA IN THE QUIET SUN  

E-Print Network [OSTI]

THE MAGNETIC CONNECTION BETWEEN THE CONVECTION ZONE AND CORONA IN THE QUIET SUN W. P. Abbett Space connection between the convectively unstable layers below the visible surface of the Sun and the overlying application of this numerical model, we present a series of simulations of the quiet Sun in a domain

Abbett, Bill

262

Impact of Convective Organization on the Response of Tropical Precipitation Extremes to Warming  

E-Print Network [OSTI]

Impact of Convective Organization on the Response of Tropical Precipitation Extremes to Warming extremes to warming in organized convection is ex- amined using a cloud-resolving model. Vertical shear, the fractional increase of precipitation extremes is similar to that of surface water vapor, which

Paris-Sud XI, Université de

263

The evolution of total lightning and radar reflectivity characteristics of two mesoscale convective systems over Houston, Texas  

E-Print Network [OSTI]

Two mesoscale convective systems (MCSs) passed over the Houston Lightning Detection and Ranging (LDAR) network on 31 October 2005 and 21 April 2006. As the MCSs traverse the LDAR network, the systems slowly mature with a weakening convective line...

Hodapp, Charles Lee

2009-05-15T23:59:59.000Z

264

Evaluation of Ensemble Configurations for the Analysis and Prediction of Heavy-Rain-Producing Mesoscale Convective Systems  

Science Journals Connector (OSTI)

This study investigates probabilistic forecasts made using different convection-allowing ensemble configurations for a three-day period in June 2010 when numerous heavy-rain-producing mesoscale convective systems (MCSs) occurred in the United ...

Russ S. Schumacher; Adam J. Clark

2014-11-01T23:59:59.000Z

265

Role of Diurnal Warm Layers in the Diurnal Cycle of Convection over the Tropical Indian Ocean during MISMO  

Science Journals Connector (OSTI)

The role of air–sea interaction in the diurnal variations of convective activity during the suppressed and developing stages of an intraseasonal convective event is analyzed using in situ observations from the Mirai Indian Ocean cruise for the ...

H. Bellenger; Y. N. Takayabu; T. Ushiyama; K. Yoneyama

2010-06-01T23:59:59.000Z

266

3D Simulation of Convection and Spectral Line Formation in A-type Stars  

E-Print Network [OSTI]

We present first realistic numerical simulations of 3D radiative convection in the surface layers of main sequence A-type stars with Teff = 8000 K and 8500 K, log g = 4.4 and 4.0, recently performed with the CO5BOLD radiation hydrodynamics code. The resulting models are used to investigate the structure of the H+HeI and the HeII convection zones in comparison with the predictions of local and non-local convection theories, and to determine the amount of "overshoot" into the stable layers below the HeII convection zone. The simulations also predict how the topology of the photospheric granulation pattern changes from solar to A-type star convection. The influence of the photospheric temperature fluctuations and velocity fields on the shape of spectral lines is demonstrated by computing synthetic line profiles and line bisectors for some representative examples, allowing us to confront the 3D model results with observations.

M. Steffen; B. Freytag; H. -G. Ludwig

2005-09-15T23:59:59.000Z

267

Convective heat and mass transfer and evolution of the moisture distribution in combined convection and radio frequency drying  

SciTech Connect (OSTI)

In a previous study (Dostie and Navarri, 1994), experiments indicated that a non-uniform moisture distribution could develop in radio frequency drying depending on the applied power and initial conditions, making the design and scale-up of such a dryer a more difficult task. Consequently, a thorough study of the combined convection and RF drying process was undertaken. Experimental results have shown that the values of the heat and mass transfer coefficients decrease with an increase in evaporation rate caused by RF energy. This effect is adequately taken into account by the boundary layer theory. Furthermore, the usual analogy between heat and mass transfer has been verified to apply in RF drying. Experiments have also shown that a different mass transfer resistance on both sides of the product should not result in non-uniform drying. However, it appears that non-uniform drying is dependent upon the initial moisture distribution and the relative intensity of heat transfer by convection and RF. It was shown that the maximum drying rate occurs at a higher average water content and that the total drying time increases with non-uniformity of the initial moisture distribution.

Poulin, A.; Dostie, M.; Kendall, J. [LTEE d`Hydro-Quebec, Shawinigan, Quebec (Canada); Proulx, P. [Univ. de Sherbrooke, Quebec (Canada)

1997-10-01T23:59:59.000Z

268

Orogenic Convection in Subtropical South America as Seen by the TRMM Satellite KRISTEN L. RASMUSSEN AND ROBERT A. HOUZE JR.  

E-Print Network [OSTI]

Orogenic Convection in Subtropical South America as Seen by the TRMM Satellite KRISTEN L. RASMUSSEN storms in southeastern South America are divided into three categories: storms with deep convective cores, the intense storms with wide convective cores over southeastern South America are unlike their Himalayan

Houze Jr., Robert A.

269

NUMERICAL DETERMINATION AND TREATMENT OF CONVECTIVE HEAT TRANSFER COEFFICIENT IN THE COUPLED BUILDING ENERGY AND CFD SIMULATION  

E-Print Network [OSTI]

for the correct prediction of the convective heat. A finer grid resolution in CFD does not always lead to a more conservation equations of flow on these grid cells. As shown in Figure 1(a), CFD calculates convective heat1 NUMERICAL DETERMINATION AND TREATMENT OF CONVECTIVE HEAT TRANSFER COEFFICIENT IN THE COUPLED

Chen, Qingyan "Yan"

270

Highly Unstable Double-Diffusive Finger Convection in a Hele-Shaw Cell: Baseline Experimental Data for Evaluation of Numerical Models  

SciTech Connect (OSTI)

An experimental investigation was conducted to study double-diffusive finger convection in a Hele-Shaw cell by layering a sucrose solution over a more-dense sodium chloride (NaCl) solution. The solutal Rayleigh numbers were on the order of 60,000, based upon the height of the cell (25 cm), and the buoyancy ratio was 1.2. A full-field light transmission technique was used to measure a dye tracer dissolved in the NaCl solution. They analyze the concentration fields to yield the temporal evolution of length scales associated with the vertical and horizontal finger structure as well as the mass flux. These measures show a rapid progression through two early stages to a mature stage and finally a rundown period where mass flux decays rapidly. The data are useful for the development and evaluation of numerical simulators designed to model diffusion and convection of multiple components in porous media. The results are useful for correct formulation at both the process scale (the scale of the experiment) and effective scale (where the lab-scale processes are averaged-up to produce averaged parameters). A fundamental understanding of the fine-scale dynamics of double-diffusive finger convection is necessary in order to successfully parameterize large-scale systems.

PRINGLE,SCOTT E.; COOPER,CLAY A.; GLASS JR.,ROBERT J.

2000-12-21T23:59:59.000Z

271

Variable frequency microwave furnace system  

DOE Patents [OSTI]

A variable frequency microwave furnace system (10) designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity (34) for testing or other selected applications. The variable frequency microwave furnace system (10) includes a microwave signal generator (12) or microwave voltage-controlled oscillator (14) for generating a low-power microwave signal for input to the microwave furnace. A first amplifier (18) may be provided to amplify the magnitude of the signal output from the microwave signal generator (12) or the microwave voltage-controlled oscillator (14). A second amplifier (20) is provided for processing the signal output by the first amplifier (18). The second amplifier (20) outputs the microwave signal input to the furnace cavity (34). In the preferred embodiment, the second amplifier (20) is a traveling-wave tube (TWT). A power supply (22) is provided for operation of the second amplifier (20). A directional coupler (24) is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

Bible, Don W. (Clinton, TN); Lauf, Robert J. (Oak Ridge, TN)

1994-01-01T23:59:59.000Z

272

Variable frequency microwave furnace system  

DOE Patents [OSTI]

A variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency microwave furnace system includes a microwave signal generator or microwave voltage-controlled oscillator for generating a low-power microwave signal for input to the microwave furnace. A first amplifier may be provided to amplify the magnitude of the signal output from the microwave signal generator or the microwave voltage-controlled oscillator. A second amplifier is provided for processing the signal output by the first amplifier. The second amplifier outputs the microwave signal input to the furnace cavity. In the preferred embodiment, the second amplifier is a traveling-wave tube (TWT). A power supply is provided for operation of the second amplifier. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. 5 figs.

Bible, D.W.; Lauf, R.J.

1994-06-14T23:59:59.000Z

273

Variable depth core sampler  

DOE Patents [OSTI]

A variable depth core sampler apparatus comprising a first circular hole saw member, having longitudinal sections that collapses to form a point and capture a sample, and a second circular hole saw member residing inside said first hole saw member to support the longitudinal sections of said first hole saw member and prevent them from collapsing to form a point. The second hole saw member may be raised and lowered inside said first hole saw member.

Bourgeois, Peter M. (Hamburg, NY); Reger, Robert J. (Grand Island, NY)

1996-01-01T23:59:59.000Z

274

Variable laser attenuator  

DOE Patents [OSTI]

The disclosure relates to low loss, high power variable attenuators comprising one or more transmissive and/or reflective multilayer dielectric filters. The attenuator is particularly suitable to use with unpolarized lasers such as excimer lasers. Beam attenuation is a function of beam polarization and the angle of incidence between the beam and the filter and is controlled by adjusting the angle of incidence the beam makes to the filter or filters. Filters are selected in accordance with beam wavelength. 9 figs.

Foltyn, S.R.

1987-05-29T23:59:59.000Z

275

Variable depth core sampler  

DOE Patents [OSTI]

A variable depth core sampler apparatus is described comprising a first circular hole saw member, having longitudinal sections that collapses to form a point and capture a sample, and a second circular hole saw member residing inside said first hole saw member to support the longitudinal sections of said first hole saw member and prevent them from collapsing to form a point. The second hole saw member may be raised and lowered inside said first hole saw member. 7 figs.

Bourgeois, P.M.; Reger, R.J.

1996-02-20T23:59:59.000Z

276

Some properties of convective oscillations in porous medium  

SciTech Connect (OSTI)

Convective oscillations in porous media are studied numerically. A two-dimensional square, differentially heated cavity, filled with a saturated porous medium, is considered subject to linear harmonic oscillations in the vertical direction. The formulation is based on the Darcy-Boussinesq model. The problem includes three nondimensional parameters: the Rayleigh number for porous media Ra, its vibrational analog Ra{sub v}, and the nondimensional frequency f. The time-dependent Darcy-Boussinesq equations have been solved using a pseudo-spectral Chebyshev collocation method. The instantaneous fields of the established oscillatory regimes are presented. Also, some instantaneous and mean characteristics are studied and discussed. The distinctions from the case of viscous fluid alone are emphasized.

Khallouf, H.; Mojitabi, A. [Univ. Paul Sabatier, Toulouse (France); Gershuni, G.Z. [Perm State Univ. (Russian Federation). Dept. of Theoretical Physics

1996-11-08T23:59:59.000Z

277

Energy stability bounds on convective heat transport: Numerical study  

SciTech Connect (OSTI)

The concept of nonlinear energy stability has recently been extended to deduce bounds on energy dissipation and transport in incompressible flows, even for turbulent flows. In this approach an effective stability condition on {open_quotes}background{close_quotes} flow or temperature profiles is derived, which when satisfied ensures that the profile produces a rigorous upper estimate to the bulk dissipation. Optimization of the test background profiles in search of the lowest upper bounds leads to nonlinear Euler-Lagrange equations for the extremal profile. In this paper, in the context of convective heat transport in the Boussinesq equations, we describe numerical solutions of the Euler-Lagrange equations for the optimal background temperature and present the numerical computation of the implied bounds. {copyright} {ital 1997} {ital The American Physical Society}

Doering, C.R. [Department of Mathematics, University of Michigan, Ann Arbor, Michigan 48109-1109 (United States)] [Department of Mathematics, University of Michigan, Ann Arbor, Michigan 48109-1109 (United States); Hyman, J.M. [Theoretical Division and Center for Nonlinear Studies, MS-B284, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division and Center for Nonlinear Studies, MS-B284, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1997-06-01T23:59:59.000Z

278

Wind reversals in turbulent Rayleigh-Benard convection  

E-Print Network [OSTI]

The phenomenon of irregular cessation and subsequent reversal of the large-scale circulation in turbulent Rayleigh-B\\'enard convection is theoretically analysed. The force and thermal balance on a single plume detached from the thermal boundary layer yields a set of coupled nonlinear equations, whose dynamics is related to the Lorenz equations. For Prandtl and Rayleigh numbers in the range $10^{-2} \\leq \\Pr \\leq 10^{3}$ and $10^{7} \\leq \\Ra \\leq 10^{12}$, the model has the following features: (i) chaotic reversals may be exhibited at Ra $\\geq 10^{7}$; (ii) the Reynolds number based on the root mean square velocity scales as $\\Re_{rms} \\sim \\Ra^{[0.41 ... 0.47]}$ (depending on Pr), and as $\\Re_{rms} \\sim \\Pr^{-[0.66 ... 0.76]}$ (depending on Ra); and (iii) the mean reversal frequency follows an effective scaling law $\\omega / (\

Francisco Fontenele Araujo; S. Grossmann; D. Lohse

2005-08-29T23:59:59.000Z

279

Radiative-Convective Equilibrium Revisited: the Greenhouse Effect of Clouds  

Science Journals Connector (OSTI)

A parameterized spectral radiative-convective equilibrium model is built and the heating rates and temperature profiles for various absorbers are calculated and compared with the results of a classical model. Then using an optical depth that is dependent on both the extinction coefficient and the cloud-water path the validity of the black-cloud assumption is tested. It is determined under what conditions one would need to know the liquid or ice water path of the cloud and when one can simply treat the cloud as a black object. A distribution of both ice and water clouds is inputted into the model and the global average surface temperature is obtained. The sensitivity of the surface temperature to a change in either the ice or liquid water path of the cloud is also evaluated.

R. Davies; C. Radley

2009-01-01T23:59:59.000Z

280

Discharge convective instability as modifier of nonlinear hydrodynamic spectrum  

E-Print Network [OSTI]

Discharge source is considered as modifier of flow hydrodynamic spectrum. Characteristic frequency of nonlinear spectrum and spectrum power were determined under conditions of arc sliding discharge in supersonic flow. Two stages of discharge were defined: sliding stage and still stage. It was found that stage transition occurs due to convective instability of discharge. Fraction of sliding stage in overall discharge duration is determined by averaged current that is general stable discharge parameter. This phenomenon gives opportunity to control power of pressure fluctuations spectrum. Theoretical insight of field and hydrodynamic factors influencing on pulsations frequency was achieved. Hydrodynamic resistance of discharge region and holding cathode electric field turned out to be basic factors of frequency modification. Corresponding experimental verification was taken. Basic frequency law was determined for several discharge regimes.

Sergey Kamenshchikov

2012-04-26T23:59:59.000Z

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


281

Field synergy principle analysis for reducing natural convection heat loss of a solar cavity receiver  

Science Journals Connector (OSTI)

Abstract Due to the operating temperature from 900 K to 1300 K produced by the concentrating ratio over 2000 in solar parabolic dish-engine system, the natural convection heat loss driven by the buoyancy force of air contributes an important role in the energy loss of cavity receiver. 3-D numerical simulations were performed and the results are analyzed from the novel viewpoint of field synergy principle (FSP) in order to study the heat transfer and fluid flow characteristics in natural convection heat loss of cavity receiver. The effects of geometric parameters, including the inclination angle, aperture size, aperture position and cavity geometric shape on the natural convection heat loss of cavity receiver were examined. The FSP analysis on the simulation results demonstrates that FSP can well explain the reduction mechanism for natural convection heat loss of cavity receiver because the smaller inner production of velocity vector and temperature gradient always corresponds to the lower Nusselt number occurred in the cases with lager inclination angle, smaller aperture size, lower aperture position and frustum-cylinder cavity, respectively. Therefore, the reducing natural convection heat loss attributes to the weakening synergy between velocity vector and temperature gradient. In addition, the local heat transfer performance is studied by the presented distributions of heat transferred via fluid motion, where more interesting natural convection heat loss characteristics of cavity receiver and the detailed explanations were provided. The results of this work offer benefits for the development of theory and technique about reducing natural convection heat loss of cavity receiver.

Yuqiang Li; Gang Liu; Zhenghua Rao; Shengming Liao

2015-01-01T23:59:59.000Z

282

Numerical investigation of flow structure and mixed convection heat transfer of impinging radial and axial jets  

SciTech Connect (OSTI)

Mixed convection flow fields and heat transfer of partially enclosed axial and radial laminar jets impinging on a heated flat plate have been investigated from the numerical solution of incompressible unsteady Navier-Stokes and energy equations with a Boussinesq approximation. For mixed convection flow at Re = 200, steady flow has not been observed for either the radial or the axial jet. For the smallest Grashof number (Gr = 10,000), periodic solutions have been obtained. With Gr = 40,000 nonsteady nonperiodic (chaotic) flow appears. Free convection may increase that heat transfer by more than 200%.

Potthast, F.; Laschefski, H.; Mitra, N.K. (Ruhr-Univ. Bochum (Germany). Inst. fuer Thermo- und Fluiddynamik); Biswas, G. (Indian Inst. of Tech., Kanpur (India). Dept. of Mechanical Engineering)

1994-08-01T23:59:59.000Z

283

Towards a new scheme for parametrisation of deep convection in NAME III  

Science Journals Connector (OSTI)

This paper describes an updated scheme for parametrisation of atmospheric convection to be used in the Met Office Atmospheric Dispersion Model (NAME III). In this scheme, the vertical transport of particles due to convection is represented in a 1-dimensional model based on a 'mass-flux' approach. Empirical formulas are used to obtain the mass fluxes and the convective precipitation is used for closure. Results compared with the mass fluxes from the single column version of the Met Office's NWP model show good agreement. Lastly, an alternative method to estimate the mass fluxes by calculating a dilute parcel ascent is also discussed.

Elena Meneguz; David J. Thomson

2014-01-01T23:59:59.000Z

284

Improving the Model Convective Storm Quantitative Precipitation Nowcasting by Assimilating State Variables Retrieved from Multiple-Doppler Radar Observations  

Science Journals Connector (OSTI)

This research combines an advanced multiple-Doppler radar synthesis technique with the thermodynamic retrieval method, originally proposed by Gal-Chen, and a moisture/temperature adjustment scheme, and formulates a sequential procedure. The focus ...

Yu-Chieng Liou; Jian-Luen Chiou; Wei-Hao Chen; Hsin-Yu Yu

2014-11-01T23:59:59.000Z

285

On convergence of an iterative technique for solution of the implicit relationship between variables in the equations for moist convection  

E-Print Network [OSTI]

N)+M+ Sa (37) (3) a a (O) e a (O) and D) (3S~ R~ R~ ) Ds + (Ss 38~ R~ ) D) + (Ry M + Sr N)+N+ Sa (38) Ifn=3 Dq ? (Sg -6S R +Rq) Dq ? (4S~R~ - 4Sa R') D) + ~(Sj R~)M (2SyR~)N] + (SyM RyN) + M + Sa (39) and 12 D~ = (4SI3RI - I R ) Dk + (Sl ? 6SIRj... CONTINUE )rR I TE ( 6 r 9) I rRR ~ R ( rFC( I ) 9 FORFAT (Tier 'DR( ' r IZr ) r T3lrEl ~ 6 r(R ( TE (6 ~ I I ) I r IF, ( I, IC ( ( ) ll FOR& AT(Tle, rn I(' l2, ') ', T31, El4. 6, T6l, f14. 6, T9[, E14. 6) 200 CONTINUE 119o CONT(NUE RETURN ENO FUNCT...

Perry, Richard Allan

2012-06-07T23:59:59.000Z

286

Interannual variability of the mixed layer winter convection and spice injection in the Eastern Subtropical North Atlantic  

Science Journals Connector (OSTI)

The Argo data set is used to study the winter upper ocean conditions in the North-Eastern Subtropical (NEA) Atlantic during 2006-2012. During the late winter 2010, the mixed layer depth is abnormally shallow and a negative anomaly of density-...

Nicolas Kolodziejczyk; Gilles Reverdin; Alban Lazar

287

Convective Precipitation Variability as a Tool for General Circulation Model Analysis CHARLOTTE A. DEMOTT, DAVID A. RANDALL, AND MARAT KHAIROUTDINOV  

E-Print Network [OSTI]

. DEMOTT, DAVID A. RANDALL, AND MARAT KHAIROUTDINOV Department of Atmospheric Science, Colorado State

Randall, David A.

288

PHP: Constructs and Variables Introduction  

E-Print Network [OSTI]

PHP: Constructs and Variables Introduction This document describes: 1. the syntax and types of variables, 2. PHP control structures (i.e., conditionals and loops), 3. mixed-mode processing, 4. how to use one script from within another, 5. how to define and use functions, 6. global variables in PHP, 7

Vander Zanden, Brad

289

Variable path length spectrophotometric probe  

DOE Patents [OSTI]

A compact, variable pathlength, fiber optic probe for spectrophotometric measurements of fluids in situ. The probe comprises a probe body with a shaft having a polished end penetrating one side of the probe, a pair of optic fibers, parallel and coterminous, entering the probe opposite the reflecting shaft, and a collimating lens to direct light from one of the fibers to the reflecting surface of the shaft and to direct the reflected light to the second optic fiber. The probe body has an inlet and an outlet port to allow the liquid to enter the probe body and pass between the lens and the reflecting surface of the shaft. A linear stepper motor is connected to the shaft to cause the shaft to advance toward or away from the lens in increments so that absorption measurements can be made at each of the incremental steps. The shaft is sealed to the probe body by a bellows seal to allow freedom of movement of the shaft and yet avoid leakage from the interior of the probe.

O'Rourke, Patrick E. (157 Greenwood Dr., Martiney, GA 30907); McCarty, Jerry E. (104 Recreation Dr., Aiken, SC 29803); Haggard, Ricky A. (1144 Thornwood Drive, North Augusta, SC 29891)

1992-01-01T23:59:59.000Z

290

Heart rate variability in mice with coronary heart disease  

E-Print Network [OSTI]

Heart rate variability (HRV), the beat-to-beat fluctuation of the heart rate, is a non-invasive test that measures the autonomic regulation of the heart. Assessment of HRV has been shown to predict the risk of mortality ...

Zapanta, Laurence (Laurence F.)

2005-01-01T23:59:59.000Z

291

Study of formation and convective transport of aerosols using optical diagnostic technique  

E-Print Network [OSTI]

. To optimize VI performance, the characteristics of convective transport should be identified. This objective is achieved by visualization techniques. The applied visualization techniques are Mie-scattering and laser induced fluorescence (LIF). To investigate...

Kim, Tae-Kyun

2004-09-30T23:59:59.000Z

292

Mesoscale Structure of Trade Wind Convection over Puerto Rico: Composite Observations and Numerical Simulation  

Science Journals Connector (OSTI)

We examine the mesoscale structure of the atmospheric boundary layer (ABL), low-level circulation, and trade wind convection over the sub-tropical island of Puerto Rico in mid-summer. Shallow afternoon thunder...

Mark R. Jury; Sen Chiao; Eric W. Harmsen

2009-08-01T23:59:59.000Z

293

A Boussinesq Model for the Convection Zone and the Solar Angular Velocity  

Science Journals Connector (OSTI)

We assume that the main mechanism responsible for setting up and driving the circulation is the interaction of rotation with convection. We solve the first-order equations (perturbation of the spherically symmetr...

G. Belvedere; L. Paternò

1976-01-01T23:59:59.000Z

294

Non-Oberbeck-Boussinesq Effects in Rayleigh-Bénard Convection of Liquids  

Science Journals Connector (OSTI)

The influence of temperature-dependent material properties on Rayleigh–Bénard convection is investigated in three different liquids, ranging from a very small Prandtl number for mercury with Pr?=?0.0232, over a m...

Susanne Horn; Olga Shishkina; Claus Wagner

2014-01-01T23:59:59.000Z

295

The excitation of solar-like oscillations in a delta Scuti star by efficient envelope convection  

E-Print Network [OSTI]

Delta Scuti (delta Sct) stars are opacity-driven pulsators with masses of 1.5-2.5M$_{\\odot}$, their pulsations resulting from the varying ionization of helium. In less massive stars such as the Sun, convection transports mass and energy through the outer 30 per cent of the star and excites a rich spectrum of resonant acoustic modes. Based on the solar example, with no firm theoretical basis, models predict that the convective envelope in delta Sct stars extends only about 1 per cent of the radius, but with sufficient energy to excite solar-like oscillations. This was not observed before the Kepler mission, so the presence of a convective envelope in the models has been questioned. Here we report the detection of solar-like oscillations in the delta Sct star HD 187547, implying that surface convection operates efficiently in stars about twice as massive as the Sun, as the ad hoc models predicted.

Antoci, V; Campante, T L; Thygesen, A O; Moya, A; Kallinger, T; Stello, D; Grigahcène, A; Kjeldsen, H; Bedding, T R; Lüftinger, T; Christensen-Dalsgaard, J; Catanzaro, G; Frasca, A; De Cat, P; Uytterhoeven, K; Bruntt, H; Houdek, G; Kurtz, D W; Lenz, P; Kaiser, A; Van Cleve, J; Allen, C; Clarke, B D

2011-01-01T23:59:59.000Z

296

Properties of a Simulated Convective Boundary Layer in an Idealized Supercell Thunderstorm Environment  

Science Journals Connector (OSTI)

Nearly all previous numerical simulations of supercell thunderstorms have neglected surface fluxes of heat, moisture, and momentum. This choice precludes horizontal inhomogeneities associated with dry boundary layer convection in the near-storm ...

Christopher J. Nowotarski; Paul M. Markowski; Yvette P. Richardson; George H. Bryan

2014-11-01T23:59:59.000Z

297

Natural convection and radiation in small enclosures with a non-attached obstruction  

E-Print Network [OSTI]

Numerical simulations were used to investigate natural convection and radiation interactions in small enclosures of both two and three-dimensional geometries. The objectives of the research were to (1) determine the relative importance of natural...

Lloyd, Jimmy Lynn

2004-09-30T23:59:59.000Z

298

Role of Convective Entrainment in Spatial Distributions of and Temporal Variations in Precipitation over Tropical Oceans  

Science Journals Connector (OSTI)

The authors demonstrate that an appropriate treatment of convective entrainment is essential for determining spatial distributions of and temporal variations in precipitation. Four numerical experiments are performed using atmospheric models with ...

Nagio Hirota; Yukari N. Takayabu; Masahiro Watanabe; Masahide Kimoto; Minoru Chikira

2014-12-01T23:59:59.000Z

299

Sensitivity of Tropical Cyclones to Parameterized Convection in the NASA GEOS5 Model  

Science Journals Connector (OSTI)

The sensitivity of tropical cyclones (TCs) to changes in parameterized convection is investigated to improve the simulation of TCs in the North Atlantic. Specifically, the impact of reducing the influence of the Relaxed Arakawa-Schubert (RAS) ...

Young-Kwon Lim; Siegfried D. Schubert; Oreste Reale; Myong-In Lee; Andrea M. Molod; Max J. Suarez

300

Observational Analysis of the Predictability of Mesoscale Convective Systems ISRAEL L. JIRAK AND WILLIAM R. COTTON  

E-Print Network [OSTI]

AND WILLIAM R. COTTON Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado merge into a large, long-lived organized convective system (Cotton and Anthes 1989). Thus, forecasting

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


301

Urban Aerosol Impacts on Downwind Convective Storms SUSAN C. VAN DEN HEEVER AND WILLIAM R. COTTON  

E-Print Network [OSTI]

Urban Aerosol Impacts on Downwind Convective Storms SUSAN C. VAN DEN HEEVER AND WILLIAM R. COTTON. 2004; Givati and Rosenfeld 2004; Molders and Olson 2004; Jirak and Cotton 2006); 2) increased surface

Collett Jr., Jeffrey L.

302

Lattice Boltzmann Simulation of Mixed Convection in a Driven Cavity Packed with Porous Medium  

Science Journals Connector (OSTI)

The problem of mixed convection in a driven cavity packed with porous medium is studied with lattice Boltzmann method. A lattice Boltzmann model for incompressible flow in porous media and another thermal lattice

Zhenhua Chai; Zhaoli Guo; Baochang Shi

2007-01-01T23:59:59.000Z

303

Convective heat transfer in a locally heated plane incompressible fluid layer  

Science Journals Connector (OSTI)

The problem of convection in a plane horizontal layer of incompressible fluid with rigid boundaries when the temperature is ... . Together with the wellknown solutions which describe heat transfer for the linear ...

S. N. Aristov; K. G. Shvarts

2013-05-01T23:59:59.000Z

304

Unsteady hydromagnetic free-convection flow with radiative heat transfer in a rotating fluid  

Science Journals Connector (OSTI)

We study the unsteady free-convection flow near a moving infinite flat plate in a totating medium by imposing a time-dependent perturbation on a constant plate temperature. The temperatures involved are assume...

A. R. Bestman; S. K. Adjepong

305

Rheology and Convective Heat Transfer of Colloidal Gas Aphrons in Horizontal Minichannels  

E-Print Network [OSTI]

Single-phase convective heat transfer in microchannels: aand Newell, M. E. , 1967. Heat transfer in fully developed3 /s at 130 W. Water CGA Heat Transfer Coefficient, h (W/m 2

Tseng, H.; Pilon, L.; Warrier, G.

2006-01-01T23:59:59.000Z

306

Natural convection in shallow porous cavities near the density maximum: the conduction and intermediate regimes  

Science Journals Connector (OSTI)

......and to the design of solar energy collectors. Convection in shallow...where x and y are the horizontal and vertical coordinates, and u and v are the horizontal and vertical Darcy...central core regions horizontal changes will occur......

D. M. Leppinen; D. A. S. Rees

2014-06-01T23:59:59.000Z

307

Conduction and convection heat transfer in composite solar collector systems with porous absorber  

Science Journals Connector (OSTI)

Steady natural convection and conduction heat transfer has been studied in composite solar collector systems. The system consists of a glazing ... bounding wall isothermal at different temperatures, two horizontal

M. Mbaye; E. Bilgen

1993-01-01T23:59:59.000Z

308

Mesoscale Convective Systems in Relation to African and Tropical Easterly Jets  

Science Journals Connector (OSTI)

This paper documents the interaction processes between mesoscale convective systems (MCS), the tropical easterly jet (TEJ), and the African easterly jet (AEJ) over West Africa during the monsoon peak of 2006 observed during the African Monsoon ...

L. Besson; Y. Lemaître

2014-09-01T23:59:59.000Z

309

Physica D 143 (2000) 169186 Surface tension-driven convection patterns in two liquid layers  

E-Print Network [OSTI]

Physica D 143 (2000) 169­186 Surface tension-driven convection patterns in two liquid layers Anne a liquid layer with a free surface is heated from below, both surface tension gradients and buoyancy may

Texas at Austin. University of

310

Tropical Cyclogenesis Sensitivity to Environmental Parameters in Radiative-Convective Equilibrium  

E-Print Network [OSTI]

In this study, the relationship between the likelihood of tropical cyclogenesis and external environmental forcings is explored in the simplest idealized modelling framework possible: radiative-convective equilibrium on a ...

Nolan, David S.

311

Changes in convective properties over the solar cycle: effect on p-mode damping rates  

Science Journals Connector (OSTI)

......Grundforskningsfond, Denmark 5 Institute for Fysik og Astronomi, Aarhus Universitet, Denmark...of 1997). 2 Computational details The basic model calculations were carried out essentially...173, Workshop on Stellar Structure: Theory and Tests of Convective Energy Transport......

G. Houdek; W.J. Chaplin; T. Appourchaux; J. Christensen-Dalsgaard; W. Däppen; Y. Elsworth; D.O. Gough; G.R. Isaak; R. New; M.C. Rabello-Soares

2001-10-21T23:59:59.000Z

312

A Multisatellite Investigation of the Convective Properties of Developing and Nondeveloping Tropical Disturbances  

Science Journals Connector (OSTI)

A comprehensive passive microwave satellite dataset is analyzed to quantify and compare the time evolution of convective properties of the pregenesis stage of developing disturbances (12 cases) and nondeveloping disturbances (3 cases), to ...

Jonathan Zawislak; Edward J. Zipser

2014-12-01T23:59:59.000Z

313

Computation of electric-arc parameters taking account of convective and radiant losses  

Science Journals Connector (OSTI)

An approximate solution of the problem of an electrical arc in a turbulent argon stream is obtained, taking into account convective and radiant energy losses in the discharge channel at atmospheric pressure.

N. A. Zyrichev

1971-10-01T23:59:59.000Z

314

Study of natural convection heat transfer above a horizontal heated plate using a laser specklegram technique  

E-Print Network [OSTI]

Heat transfer by free convection in air from an isothermal horizontal heated flat plate facing upward has been experimentally studied by using a non intrusive and accurate optical technique, Speckle photography or a specklegram technique. The local...

Cheeti, Satish K.R.

2012-06-07T23:59:59.000Z

315

Using CASA IP1 to Diagnose Kinematic and Microphysical Interactions in a Convective Storm  

Science Journals Connector (OSTI)

Data from the Collaborative Adaptive Sensing of the Atmosphere (CASA) Integrated Project I (IP1) network of polarimetric X-band radars are used to observe a convective storm. A fuzzy logic hydrometeor identification algorithm is employed to study ...

Brenda Dolan; Steven A. Rutledge

2010-05-01T23:59:59.000Z

316

Geodynamic and seismic constraints on the thermochemical structure and dynamics of convection in the deep mantle  

Science Journals Connector (OSTI)

...Brodholt and B. J. Wood Geodynamic and seismic constraints on the thermochemical structure...by this viscosity peak. geodynamics|seismic tomography|mantle viscosity|three-dimensional...anomalies|mantle convection| Geodynamic and seismic constraints on the thermochemical structure...

2002-01-01T23:59:59.000Z

317

Numerical analysis of binary solid-liquid phase change with buoyancy and surface tension driven convection  

SciTech Connect (OSTI)

The effects of thermo/diffusocapillary convection on the solidification of aqueous NH{sub 4}Cl in a rectangular cavity have been simulated numerically using a newly developed continuum model. Diffusocapillary convection is negligible relative to thermocapillary convection, and for a 20 {times} 20 mm cavity in a one-gravity environment, thermocapillary effects are most pronounced during the early stages of solidification, when flow conditions are characterized by three major cells. One cell, driven by solutal buoyancy forces, extends from the mush region to the melt and separates top and bottom melt region cells driven primarily by surface tension and buoyancy forces, respectively. With increasing time, however, the top cell strengthens and eventually envelops the entire melt. In terms of the strength of the flow, the liquidus front morphology, and the amount of solid formed, final conditions differ only slightly from those predicted for pure thermal/solutal convection.

Incropera, F.P.; Engel, A.H.H. (Purdue Univ., Lafayette, IN (USA). Heat Transfer Lab.); Bennon, W.D. (Alcoa Technical Center, Alcoa Center, PA (US))

1989-01-01T23:59:59.000Z

318

Convectively unstable wave packets in spatially developing open flows and media with algebraically decaying tails  

Science Journals Connector (OSTI)

...first recognized in the plasma physics literature (see Twiss 1951...absolute and convective. In Handbook of plasma physics (ed. M. N. Rosenbluth & R...Stability of traveling waves. In Handbook of dynamical systems II (ed...

2005-01-01T23:59:59.000Z

319

The effect of shear on heat budgets in a simulated Mesoscale Convective System  

E-Print Network [OSTI]

The evolution and structure of simulated Mesoscale Convective Systems (MCS) were examined using the Collaborative Model for Multiscale Atmospheric Simulations. Three numerical simulations were performed, with the amount of vertical wind shear...

Shaw, Justin David

2000-01-01T23:59:59.000Z

320

A visualization comparison of convective flow boiling heat transfer augmentation devices  

E-Print Network [OSTI]

The qualitative effects of inset-table heat transfer phics. augmentation devices on vertical in-tube convective flow boiling flow regimes, transition mechanisms, and heat transfer are presented in this study. Three twisted tapes with twist ratios...

Lundy, Brian Franklin

2012-06-07T23:59:59.000Z

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


321

Characteristics of convective cells over the coastal regions of southeast Texas  

E-Print Network [OSTI]

Vertical profiles of radar reflectivity and cloud-to-ground lightning characteristics associated with convective cells were analyzed for mesoscate systems occurring over the coastal regions of southeast Texas during the spring and summer months...

Robinson, Michael

2012-06-07T23:59:59.000Z

322

Experimental Investigation of Forced Convection Heat Transfer of Nanofluids in a Microchannel using Temperature Nanosensors  

E-Print Network [OSTI]

Experiments were performed to study forced convective heat transfer of de-ionized water (DI water) and aqueous nanofluids flowing in a microchannel. An array of temperature nanosensors, called “Thin Film Thermocouples (TFT)”, was utilized...

Yu, Jiwon 1982-

2012-12-03T23:59:59.000Z

323

Short-wavelength geoid, bathymetry and the convective pattern beneath the Pacific Ocean  

Science Journals Connector (OSTI)

......convective pattern beneath the Pacific Ocean L. Fleitout C. Moriceau aboratoire...geoid and bathymetry data in the Pacific Ocean are used to shed new light on...various wavebands on the Central Pacific Ocean: constraints on the origin of......

L. Fleitout; C. Moriceau

1992-07-01T23:59:59.000Z

324

A Climatology of Midlatitude Mesoscale Convective Vortices in the Rapid Update Cycle  

Science Journals Connector (OSTI)

Climatological characteristics of mesoscale convective vortices (MCVs) occurring in the state of Oklahoma during the late spring and summer of four years are investigated. The MCV cases are selected based on vortex detection by an objective ...

Eric P. James; Richard H. Johnson

2010-05-01T23:59:59.000Z

325

A Satellite-Based Parameter to Monitor the Aerosol Impact on Convective Clouds  

Science Journals Connector (OSTI)

A method to monitor the aerosol impact on convective clouds using satellite data is presented. The impacts of forest fires and highly polluting megacities on cloud precipitation formation processes are quantified by the vertical extent above ...

Itamar M. Lensky; Ron Drori

2007-05-01T23:59:59.000Z

326

Organization of Oceanic Convection during the Onset of the 1998 East Asian Summer Monsoon  

Science Journals Connector (OSTI)

The organizational modes of convection over the northern South China Sea (SCS) during the onset of the summer monsoon are documented using radar and sounding data from the May–June 1998 South China Sea Monsoon Experiment (SCSMEX). The onset ...

Richard H. Johnson; Steven L. Aves; Paul E. Ciesielski; Thomas D. Keenan

2005-01-01T23:59:59.000Z

327

The Distribution of Deep Convection over Ocean and Land during the Asian Summer Monsoon  

Science Journals Connector (OSTI)

Tle highly reflective cloud (HRC) dataset is a daily index of organized deep convection, at one degree resolution, from 17 years of polar-orbiting, satellite imagery. These data are used to analyze and discuss the climatological geographical ...

Robert L. Grossman; Oswaldo Garcia

1990-09-01T23:59:59.000Z

328

Feature-Point Detection Using Distance Transforms: Application to Tracking Tropical Convective Complexes  

Science Journals Connector (OSTI)

The identification, tracking, and statistical analysis of tropical convective complexes using satellite imagery is explored in the context of identifying feature points suitable for tracking. The feature points are determined based on the shape ...

K. I. Hodges

1998-03-01T23:59:59.000Z

329

Convective cloud and rainfall processes over the Maritime Continent : simulation and analysis of the diurnal cycle  

E-Print Network [OSTI]

The Maritime Continent experiences strong moist convection, which produces significant rainfall and drives large fluxes of heat and moisture to the upper troposphere. Despite the importance of these processes to global ...

Gianotti, Rebecca L. (Rebecca Louise)

2013-01-01T23:59:59.000Z

330

Hadley Circulations in Radiative–Convective Equilibrium in an Axially Symmetric Atmosphere  

Science Journals Connector (OSTI)

Hadley circulations in radiative–convective equilibrium are investigated using an idealistic axially symmetric model. Calculations show that the distribution of temperature in the Hadley cell is controlled by the moist process; the vertical ...

Masaki Satoh

1994-07-01T23:59:59.000Z

331

Quasi-Stationary Convective Systems Forming Perpendicular to, Above the Cold Pool of, Strong Bow Echoes  

E-Print Network [OSTI]

and Forecasting (WRF) model are analyzed in an attempt to understand the mechanisms responsible for initiating and maintaining the convective line. Due to coarse resolution, observational analyses are only useful for inspection of the synoptic-scale. Model...

Keene, Kelly M.

2012-10-19T23:59:59.000Z

332

Turbulent convection in the anelastic rotating sphere : a model for the circulation on the giant planets  

E-Print Network [OSTI]

This thesis studies the dynamics of a rotating compressible gas sphere, driven by internal convection, as a model for the dynamics on the giant planets. We develop a new general circulation model for the Jovian atmosphere, ...

Kaspi, Yohai

2008-01-01T23:59:59.000Z

333

Analysis of Strengthening and Dissipating Mesoscale Convective Systems Propagating off the West African Coast  

Science Journals Connector (OSTI)

A large number of Atlantic tropical depressions are generated in the eastern basin in relation to the African easterly wave (AEW) and embedded mesoscale convective systems (MCSs) coming from the African continent. In this paper, the structures of ...

Abdou L. Dieng; Laurence Eymard; Saidou M. Sall; Alban Lazar; Marion Leduc-Leballeur

2014-12-01T23:59:59.000Z

334

MJO and Convectively Coupled Equatorial Waves Simulated by CMIP5 Climate Models  

Science Journals Connector (OSTI)

This study evaluates the simulation of the Madden–Julian oscillation (MJO) and convectively coupled equatorial waves (CCEWs) in 20 models from the Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) in the Intergovernmental Panel on ...

Meng-Pai Hung; Jia-Lin Lin; Wanqiu Wang; Daehyun Kim; Toshiaki Shinoda; Scott J. Weaver

2013-09-01T23:59:59.000Z

335

Deep Convective Transition Characteristics in the Community Climate System Model and Changes under Global Warming  

Science Journals Connector (OSTI)

Tropical deep convective transition characteristics, including precipitation pickup, occurrence probability, and distribution tails related to extreme events, are analyzed using uncoupled and coupled versions of the Community Climate System Model (...

Sandeep Sahany; J. David Neelin; Katrina Hales; Richard B. Neale

2014-12-01T23:59:59.000Z

336

On the Diurnal Cycle of Deep Convection, High-Level Cloud, and Upper Troposphere Water Vapor in the Multiscale Modeling Framework  

SciTech Connect (OSTI)

The Multiscale Modeling Framework (MMF), also called ‘‘superparameterization’’, embeds a cloud-resolving model (CRM) at each grid column of a general circulation model to replace traditional parameterizations of moist convection and large-scale condensation. This study evaluates the diurnal cycle of deep convection, high-level clouds, and upper troposphere water vapor by applying an infrared (IR) brightness temperature (Tb) and a precipitation radar (PR) simulator to the CRM column data. Simulator results are then compared with IR radiances from geostationary satellites and PR reflectivities from the Tropical Rainfall Measuring Mission (TRMM). While the actual surface precipitation rate in the MMF has a reasonable diurnal phase and amplitude when compared with TRMM observations, the IR simulator results indicate an inconsistency in the diurnal anomalies of high-level clouds between the model and the geostationary satellite data. Primarily because of its excessive high-level clouds, the MMF overestimates the simulated precipitation index (PI) and fails to reproduce the observed diurnal cycle phase relationships among PI, high-level clouds, and upper troposphere relative humidity. The PR simulator results show that over the tropical oceans, the occurrence fraction of reflectivity in excess of 20 dBZ is almost 1 order of magnitude larger than the TRMM data especially at altitudes above 6 km. Both results suggest that the MMF oceanic convection is overactive and possible reasons for this bias are discussed. However, the joint distribution of simulated IR Tb and PR reflectivity indicates that the most intense deep convection is found more often over tropical land than ocean, in agreement with previous observational studies.

Zhang, Yunyan; Klein, Stephen A.; Liu, Chuntao; Tian, Baijun; Marchand, Roger T.; Haynes, J. M.; McCoy, Renata; Zhang, Yuying; Ackerman, Thomas P.

2008-08-22T23:59:59.000Z

337

Thermodynamics of Eastern Mediterranean Rainfall Variability  

Science Journals Connector (OSTI)

This note focuses on thermodynamic changes caused by Eastern Mediterranean (EM) subsidence anomalies. Subsidence anomalies are shown to modulate EM-wide stability with respect to moist ascent. Additionally, convective available potential energy (...

Gidon Eshel; Brian F. Farrell

2001-01-01T23:59:59.000Z

338

Pre-convective environmental conditions indicative of non-tornadic severe thunderstorm winds over Southeast Florida  

E-Print Network [OSTI]

PRE-CONVECTIVE ENVIRONMENTAL CONDITIONS INDICATIVE OF NON-TORNADIC SEVERE THUNDERSTORM WINDS OVER SOUTHEAST FLORIDA A Thesis by JEFFREY MICHAEL WILHELM Submitted to the Graduate College of Texas ARM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 1987 Major Subject: Meteorology PRE-CONVECTIVE ENVIRONMENTAL CONDITIONS INDICATIVE OF NON-TORNADIC SEVERE THUNDERSTORM WINDS OVER SOUTHEAST FLORIDA A Thesis by JEFFREY MICHAEL WILHELM Approved...

Wilhelm, Jeffrey Michael

2012-06-07T23:59:59.000Z

339

Non-Oberbeck-Boussinesq effects in turbulent thermal convection in ethane close to the critical point  

Science Journals Connector (OSTI)

As shown in earlier work [Ahlers et al., J. Fluid Mech. 569, 409 (2006)], non-Oberbeck-Boussinesq (NOB) corrections to the center temperature in turbulent Rayleigh-Bénard convection in water and also in glycerol are governed by the temperature dependences of the kinematic viscosity and the thermal diffusion coefficient. If the working fluid is ethane close to the critical point, the origin of non-Oberbeck-Boussinesq corrections is very different, as will be shown in the present paper. Namely, the main origin of NOB corrections then lies in the strong temperature dependence of the isobaric thermal expansion coefficient ?(T). More precisely, it is the nonlinear T dependence of the density ?(T) in the buoyancy force that causes another type of NOB effect. We demonstrate this through a combination of experimental, numerical, and theoretical work, the last in the framework of the extended Prandtl-Blasius boundary-layer theory developed by Ahlers et al. as cited above. The theory comes to its limits if the temperature dependence of the thermal expension coefficient ?(T) is significant. The measurements reported here cover the ranges 2.1?Pr?3.9 and 5×109?Ra?2×1012 and are for cylindrical samples of aspect ratios 1.0 and 0.5.

Guenter Ahlers; Enrico Calzavarini; Francisco Fontenele Araujo; Denis Funfschilling; Siegfried Grossmann; Detlef Lohse; Kazuyasu Sugiyama

2008-04-08T23:59:59.000Z

340

Long-Period Solar Variability  

SciTech Connect (OSTI)

Terrestrial climate records and historical observations of the Sun suggest that the Sun undergoes aperiodic oscillations in radiative output and size over time periods of centuries and millenia. Such behavior can be explained by the solar convective zone acting as a nonlinear oscillator, forced at the sunspot-cycle frequency by variations in heliomagnetic field strength. A forced variant of the Lorenz equations can generate a time series with the same characteristics as the solar and climate records. The timescales and magnitudes of oscillations that could be caused by this mechanism are consistent with what is known about the Sun and terrestrial climate.

GAUTHIER,JOHN H.

2000-07-20T23:59:59.000Z

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


341

Eddy-resolving Lidar Measurements and Numerical Simulations of the Convective Internal Boundary Layer  

E-Print Network [OSTI]

in speed. The vertical gradient of wind-speed decreases offshore because of strong vertical mixing caused correlation functions and winds derived from horizontal (PPI) and vertical (RHI) scans of the VIL during Lake.4 0.5 0.6 0.7 DOWNSTREAM WIND SPEEDS FROM RHI SCANS ON 13 JANUARY 1998 SPATIALLY RESOLVED 5-m WINDS

Eloranta, Edwin W.

342

Convective flow measurements in a heated cavity using pulsed laser velocimetry with digital image processing  

E-Print Network [OSTI]

. This is essentially the trapezoidal sheet shown in figure 4. The thickness of the beam remains on the order of 1-1. 5 13 x-v plane z-y plane First Lens Focal Point Second Lens Third Lens Fig. 4. Laser light passing through a trio of piano-convex cylindrical...2 U3 v1 v2 3 u4 u5 u7 u8 u6 u9 v4 v 5 v7 v8 Figure 24. Pixel positions in relation to vector components. Expressing equation (15) spatially, where uij and vij are gray level values ranging from 0 to 255 at position i and j of each region...

Chavez, Hector Luis

2012-06-07T23:59:59.000Z

343

Measurements of Saharan Dust in Convective Clouds over the Tropical Eastern Atlantic Ocean  

Science Journals Connector (OSTI)

Mineral dust particles have been shown to act as cloud condensation nuclei, and they are known to interact with developing tropical storms over the Atlantic downwind of the Sahara. Once present within liquid droplets, they have the potential to ...

Cynthia H. Twohy

344

Compactification of Patterns by a Singular Convection or Stress  

SciTech Connect (OSTI)

A wide variety of propagating disturbances in physical systems are described by equations whose solutions lack a sharp propagating front. We demonstrate that presence of particular nonlinearities may induce such fronts. To exemplify this idea, we study both dissipative u{sub t}+{partial_derivative}{sub x}f(u)=u{sub xx} and dispersive u{sub t}+{partial_derivative}{sub x}f(u)+u{sub xxx}=0 patterns, and show that a weakly singular convection f(u)=-u{sup {alpha}}+u{sup m}, 0<{alpha}<1

Rosenau, Philip [School of Mathematical Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

2007-12-07T23:59:59.000Z

345

Natural convection heat transfer analysis of ATR fuel elements  

SciTech Connect (OSTI)

Natural convection air cooling of the Advanced Test Reactor (ATR) fuel assemblies is analyzed to determine the level of decay heat that can be removed without exceeding the melting temperature of the fuel. The study was conducted to assist in the level 2 PRA analysis of a hypothetical ATR water canal draining accident. The heat transfer process is characterized by a very low Rayleigh number (Ra {approx} 10{sup {minus}5}) and a high temperature ratio. Since neither data nor analytical models were available for Ra < 0.1, an analytical approach is presented based upon the integral boundary layer equations. All assumptions and simplifications are presented and assessed and two models are developed from similar foundations. In one model, the well-known Boussinesq approximations are employed, the results from which are used to assess the modeling philosophy through comparison to existing data and published analytical results. In the other model, the Boussinesq approximations are not used, thus making the model more general and applicable to the ATR analysis.

Langerman, M.A.

1992-05-01T23:59:59.000Z

346

Convective Heating of the LIFE Engine Target During Injection  

SciTech Connect (OSTI)

Target survival in the hostile, high temperature xenon environment of the proposed Laser Inertial Fusion Energy (LIFE) engine is critical. This work focuses on the flow properties and convective heat load imposed upon the surface of the indirect drive target while traveling through the xenon gas. While this rarefied flow is traditionally characterized as being within the continuum regime, it is approaching transition where conventional CFD codes reach their bounds of operation. Thus ANSYS, specifically the Navier-Stokes module CFX, will be used in parallel with direct simulation Monte Carlo code DS2V and analytically and empirically derived expressions for heat transfer to the hohlraum for validation. Comparison of the viscous and thermal boundary layers of ANSYS and DS2V were shown to be nearly identical, with the surface heat flux varying less than 8% on average. From the results herein, external baffles have been shown to reduce this heat transfer to the sensitive laser entrance hole (LEH) windows and optimize target survival independent of other reactor parameters.

Holdener, D S; Tillack, M S; Wang, X R

2011-10-24T23:59:59.000Z

347

Radial convection of finite ion temperature, high amplitude plasma blobs  

SciTech Connect (OSTI)

We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width, and the initial amplitude, we found an FLR dominated regime where the blob behavior is significantly different from what is predicted by cold-ion models. The transition to this regime is very well described by the ratio of the ion gyroradius to the characteristic gradient scale length of the blob. We compare the global gyrofluid model with a partly linearized local model. For low ion temperatures, we find that simulations of the global model show more coherent blobs with an increased cross-field transport compared to blobs simulated with the local model. The maximal blob amplitude is significantly higher in the global simulations than in the local ones. When the ion temperature is comparable to the electron temperature, global blob simulations show a reduced blob coherence and a decreased cross-field transport in comparison with local blob simulations.

Wiesenberger, M., E-mail: Matthias.Wiesenberger@uibk.ac.at; Kendl, A. [Institute for Ion Physics and Applied Physics, Association EURATOM-ÖAW, University of Innsbruck, A-6020 Innsbruck (Austria); Madsen, J. [Association EURATOM-DTU, Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark)

2014-09-15T23:59:59.000Z

348

Natural convection heat transfer from two horizontal cylinders  

SciTech Connect (OSTI)

Natural convection heat transfer from a single horizontal cylinder and a pair of vertically aligned horizontal cylinders is investigated. Surface heat transfer distributions around the circumference of the cylinders are presented for Rayleigh numbers of 2 x 10{sup 6}, 4 x 10{sup 6} and 6 x 10{sup 6} and a range of cylinder spacings of 1.5, 2 and 3 diameters. With a cylinder pairing the lower cylinder is unaffected by the presence of the second cylinder; the same is true of the upper cylinder if the lower one is not heated. However, when both cylinders are heated it has been found that a plume rising from the heated lower cylinder interacts with the upper cylinder and significantly affects the surface heat transfer distribution. Spectral analysis of surface heat transfer signals has established the influence of the plume oscillations on the heat transfer. Thus, when the plume from the lower cylinder oscillates out of phase with the flow around the upper cylinder it increases the mixing and results in enhanced heat transfer. (author)

Reymond, Olivier; Murray, Darina B. [Department of Mechanical and Manufacturing Engineering, Trinity College Dublin (Ireland); O'Donovan, Tadhg S. [School of Engineering and Physical Sciences, Heriot-Watt University, Nasmyth Building, Edinburgh EH14 4AS (United Kingdom)

2008-09-15T23:59:59.000Z

349

Is Salinity Variability a Benthic Disturbance?  

E-Print Network [OSTI]

include: salinity, pH, dissolved oxygen, temperature, conductivity, oxidation-reduction potential, and depth (Monatgna and Kalke 1992, 1995). Measurements were collected both at depth (0.1 m above bay bottom) and at the surface using a sonde... IS SALINITY VARIABILITY A BENTHIC DISTURBANCE? A Thesis by AMANDA D. VAN DIGGELEN Submitted to the Office of Graduate and Professional Studies of Texas A&M University and the Graduate Faculty of The Texas A&M University – Corpus...

Van Diggelen, Amanda

2014-05-07T23:59:59.000Z

350

15 - Measurement  

Science Journals Connector (OSTI)

Publisher Summary This chapter focuses on the various methods and equipments used in the measurement of liquids and gases in pipelines. Streams that transport mixed natural gas liquids require the use of mass measurement to accurately account for the volume of the components, which make up the mix. Mass measurement eliminates the effects of non-ideal mixing and the need for compressibility factors. The measurement system that provides basic simplicity, reliability, wide acceptance, and the capability of handling variable mix streams without breaking new frontiers in measurement methods is the orifice flow measuring element with online density meter and microprocessor flow computer. The orifice is a static device generally inert to the measured fluid conditions, and calibration consists of simple dimensional measurement and conformance to specified physical tolerances. The second element, the density meter, is an external unit that is easily isolated from the flowing stream for calibration, inspection, and maintenance. The relative insensitivity of CO2 density to small changes in pressure in the primary flow to the orifice meters permits locating the density meter upstream of the meter manifold, thereby serving several meters. The microprocessor flow computer, or third element of the system, is essential to achieve the advantages of integrated mass flow, which comes from the ability of the computer to make computations in essentially "real time." A development program to improve the overall uncertainty of orifice metering was initiated by Shell Pipeline Corporation. The program's goal was to develop an economical method for proving ethylene orifice meters under actual operating conditions. Shell's ethylene systems are operated in the dense phase fluid region due to lower transportation costs. The ethylene meter stations operate in two regions, the dense-phase fluid and single-phase gas regions.

2005-01-01T23:59:59.000Z

351

Constructing a Merged Cloud-Precipitation Radar Dataset for Tropical Convective Clouds during the DYNAMO/AMIE Experiment at Addu Atoll  

SciTech Connect (OSTI)

To improve understanding of the convective processes key to the Madden-Julian-Oscillation (MJO) initiation, the Dynamics of the MJO (DYNAMO) and Atmospheric Radiation Measurement MJO Investigation Experiment (AMIE) collected four months of observations from three radars, the S-band Polarization Radar (S-Pol), the C-band Shared Mobile Atmospheric Research & Teaching Radar (SMART-R), and Ka-band Zenith Radar (KAZR) on Addu Atoll in the tropical Indian Ocean. This study compares the measurements from the S-Pol and SMART-R to those from the more sensitive KAZR in order to characterize the hydrometeor detection capabilities of the two scanning precipitation radars. Frequency comparisons for precipitating convective clouds and non-precipitating high clouds agree much better than non-precipitating low clouds for both scanning radars due to issues in ground clutter. On average, SMART-R underestimates convective and high cloud tops by 0.3 to 1.1 km, while S-Pol underestimates cloud tops by less than 0.4 km for these cloud types. S-Pol shows excellent dynamic range in detecting various types of clouds and therefore its data are well suited for characterizing the evolution of the 3D cloud structures, complementing the profiling KAZR measurements. For detecting non-precipitating low clouds and thin cirrus clouds, KAZR remains the most reliable instrument. However, KAZR is attenuated in heavy precipitation and underestimates cloud top height due to rainfall attenuation 4.3% of the time during DYNAMO/AMIE. An empirical method to correct the KAZR cloud top heights is described, and a merged radar dataset is produced to provide improved cloud boundary estimates, microphysics and radiative heating retrievals.

Feng, Zhe; McFarlane, Sally A.; Schumacher, Courtney; Ellis, Scott; Comstock, Jennifer M.; Bharadwaj, Nitin

2014-05-16T23:59:59.000Z

352

Quantitative Differences between Lightning and Nonlightning Convective Rainfall Events as Observed with Polarimetric Radar and MSG Satellite Data  

Science Journals Connector (OSTI)

To increase understanding of the relationships between lightning and nonlightning convective storms, lightning observations from the National Aeronautics and Space Administration (NASA) African Monsoon Multidisciplinary Analyses (NAMMA) campaign ...

Retha Matthee; John R. Mecikalski; Lawrence D. Carey; Phillip M. Bitzer

2014-10-01T23:59:59.000Z

353

Stability in the Plant Communities of the Park Grass Experiment: The Relationships between Species Richness, Soil pH and Biomass Variability  

Science Journals Connector (OSTI)

...between Species Richness, Soil pH and Biomass Variability Mike E. Dodd Jonathan Silvertown...of species number and soil reaction on biomass variability in a suite of comparable plant communities. Biomass variability was measured by calculating...

1994-01-01T23:59:59.000Z

354

Measurement-Measurement-  

E-Print Network [OSTI]

Internet Measurement- System A Measurement- System B Control System GPS Satellite GPS Satellite GPS Receiver GPS Receiver 2) measurement 3) data1) command Methodology for One-way IP Performance Measurement This paper proposes a methodology for measurement of one-way IP performance metrics such as one-way delay

Jeong, Jaehoon "Paul"

355

Triclosan: Source Attribution, Urinary Metabolite Levels and Temporal Variability in Exposure Among Pregnant Women in Canada .  

E-Print Network [OSTI]

??OBJECTIVE: To measure urinary triclosan levels and their variability across pregnancy, and to identify sources of triclosan exposure among Canadian pregnant women. METHODS: Single spot… (more)

Weiss, Lorelle D.

2013-01-01T23:59:59.000Z

356

Selection automatique de variables pertinentes  

E-Print Network [OSTI]

S´election automatique de variables pertinentes Vers la d´ecouverte de nouvelles modalit´es sensori-motrices corr´elations entre ses variables sensori-motrices afin d'apprendre `a r´esoudre sa t^ache d

Boyer, Edmond

357

Natural convection with mixed insulating and conducting boundary conditions: low and high Rayleigh numbers regimes  

E-Print Network [OSTI]

We investigate the stability and dynamics of natural convection in two dimensions, subject to inhomogeneous boundary conditions. In particular, we consider a Rayleigh-B\\`enard (RB) cell, where the horizontal top boundary contains a periodic sequence of alternating thermal insulating and conducting patches, and we study the effects of the heterogeneous pattern on the global heat exchange, both at low and high Rayleigh numbers. At low Rayleigh numbers, we determine numerically the transition from a regime characterized by the presence of small convective cells localized at the inhomogeneous boundary to the onset of bulk convective rolls spanning the entire domain. Such a transition is also controlled analytically in the limit when the boundary pattern length is small compared with the cell vertical size. At higher Rayleigh number, we use numerical simulations based on a lattice Boltzmann method to assess the impact of boundary inhomogeneities on the fully turbulent regime up to $Ra \\sim 10^{10}$.

Ripesi, P; Sbragaglia, M; Wirth, A

2014-01-01T23:59:59.000Z

358

Statistics and scaling properties of temperature field in symmetrical non-Oberbeck-Boussinesq turbulent convection  

E-Print Network [OSTI]

The influence of symmetrical non-Oberbeck-Boussinesq (SNOB) effect on statistical and scaling properties of temperature field in turbulent convection is investigated experimentally in $SF_{6}$ in the vicinity of its gas-liquid critical point (CP). The main conclusion of the studies is that besides the strong $Ra$ and $Pr$ dependence of the rms of temperature fluctuations normalized by the temperature difference across the cell, different from the Oberbeck-Boussinesq (OB) case of turbulent convection, all rest of statistical and scaling properties of temperature field discussed in details are the same as in the OB case.

Yuri Burnishev; Victor Steinberg

2011-08-31T23:59:59.000Z

359

Numerical study of pattern formation following a convective instability in non-Boussinesq fluids  

Science Journals Connector (OSTI)

We present a numerical study of a model of pattern formation following a convective instability in a non-Boussinesq fluid. It is shown that many of the features observed in convection experiments conducted on CO2 gas can be reproduced by using a generalized two-dimensional Swift-Hohenberg equation. The formation of hexagonal patterns, rolls, and spirals is studied, as well as the transitions and competition among them. We also study nucleation and growth of hexagonal patterns and find that the front velocity in this two-dimensional model is consistent with the prediction of marginal stability theory for one-dimensional fronts.

Hao-wen Xi; Jorge Viñals; J. D. Gunton

1992-10-15T23:59:59.000Z

360

Four-Dimensional Assimilation of Multitime Wind Profiles over a Single Station and Numerical Simulation of a Mesoscale Convective  

E-Print Network [OSTI]

on the numerical simulation of the convective initiation and evolution. Besides the wind fields, the structureFour-Dimensional Assimilation of Multitime Wind Profiles over a Single Station and Numerical Simulation of a Mesoscale Convective System Observed during IHOP_2002 LEI ZHANG AND ZHAOXIA PU Department

Pu, Zhaoxia

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


361

A new predictive dynamic model describing the effect of1 the ambient temperature and the convective heat transfer2  

E-Print Network [OSTI]

and the convective heat transfer2 coefficient on bacterial growth3 4 H. Ben Yaghlenea,b* , I. Leguerinela , M. Hamdib Ratkowsky "square root" model and a simplified two-parameter20 heat transfer model regarding an infinite air temperature, the convective heat transfer22 coefficient and the growth parameters of the micro

Paris-Sud XI, Université de

362

Magnetic buoyancy instabilities in the presence of magnetic flux pumping at the base of the solar convection zone  

Science Journals Connector (OSTI)

......in a model of the solar tachocline. In particular...therefore the kinetic energy of the shear is not...for a primordial solar magnetic field...similar mean kinetic energy density as the convection...convection zone and to the solar surface. One important...be seen as a pilot project which has the limited......

Adrian J. Barker; Lara J. Silvers; Michael R. E. Proctor; Nigel O. Weiss

2012-07-21T23:59:59.000Z

363

CRYSTALLINE SILICON THIN-FILM SOLAR CELLS FROM THE POROUS SILICON PROCESS APPLYING CONVECTION ASSISTED CHEMICAL VAPOR DEPOSITION  

E-Print Network [OSTI]

CRYSTALLINE SILICON THIN-FILM SOLAR CELLS FROM THE POROUS SILICON PROCESS APPLYING CONVECTION ASSISTED CHEMICAL VAPOR DEPOSITION Barbara Terheiden,1* Thomas Kunz,2 Ingo Burkert2 , Renate Horbelt,1, D-91058 Erlangen, Germany ABSTRACT: Convection assisted chemical vapor deposition (CoCVD) is applied

364

Unsteady MHD combined convection over a moving vertical sheet in a fluid saturated porous medium with uniform surface heat flux  

Science Journals Connector (OSTI)

The group transformation method is applied for solving the combined convection problem in an unsteady, two-dimensional, laminar, boundary-layer flow of a viscous, incompressible and electrically-conducting fluid along a vertical continuous moving plate ... Keywords: Flow, Group transformation method, MHD, Natural convection, Porous medium

S. M. M. El-Kabeir; A. M. Rashad; Rama Subba Reddy Gorla

2007-08-01T23:59:59.000Z

365

Group solution for unsteady free-convection flow from a vertical moving plate subjected to constant heat flux  

Science Journals Connector (OSTI)

The problem of heat and mass transfer in an unsteady free-convection flow over a continuous moving vertical sheet in an ambient fluid is investigated for constant heat flux using the group theoretical method. The nonlinear coupled partial differential ... Keywords: 22E05, 35Q53, 54H15, Free convective flow, Group theoretic method, Prandtl number, Thermal boundary layer

M. Kassem

2006-03-01T23:59:59.000Z

366

Mesoscale Convective Vortices in Multiscale, Idealized Simulations: Dependence on Background State, Interdependency with Moist Baroclinic Cyclones, and Comparison with BAMEX Observations  

Science Journals Connector (OSTI)

A set of multiscale, nested, idealized numerical simulations of mesoscale convective systems (MCSs) and mesoscale convective vortices (MCVs) was conducted. The purpose of these simulations was to investigate the dependence of MCV development and ...

Robert J. Conzemius; Michael T. Montgomery

2010-04-01T23:59:59.000Z

367

VoLUME 57, NUM@BR 16 PHYSICAL REVIEW LETTERS 20 OcToBER 1986 Competing Patterns in a Convective Binary Mixture  

E-Print Network [OSTI]

of convection in ethanol-water mixtures at positive values of the separation ratio Q are presented. Close-driven convection in ethanol-water mixtures. The Soret effect is a mechanism by which an externally imposed tempera

Moses, Elisha

368

Measuring Cost Variability in Provision of Transit Service  

E-Print Network [OSTI]

W. , and S. R. Mundle. Peak-Base Cost Allocation Models. In29–33. Reilly, J. M. Transit Costs During Peak and Off-PeakHow to Allocate Bus Route Costs. Transit, Vol. 5, No. 2,

Taylor, Brian D.; Garrett, Mark; Iseki, Hiroyuki

2010-01-01T23:59:59.000Z

369

Measuring the performance and intrinsic variability of evolved circuits  

Science Journals Connector (OSTI)

This paper presents a comparison between conventional and multi-objective Cartesian Genetic Programming evolved designs for a 2-bit adder and a 2-bit multiplier. Each design is converted from a gate-level schematic to a transistor level implementation, ...

James Alfred Walker; James A. Hilder; Andy M. Tyrrell

2010-09-01T23:59:59.000Z

370

Variability in the Measurement of Hospital-wide Mortality Rates  

Science Journals Connector (OSTI)

...the substantially different results we observed among methods may reflect flaws in the fundamental hypothesis that hospital-wide mortality is a valid metric for the quality of hospital care. Our study also does not rule out the possibility that the estimation of hospital-wide mortality rates on the... This study showed that four commonly used methods to calculate hospitals' risk-adjusted rates of death produced different results. The same hospitals were classified as having higher-than-expected mortality by one method and lower-than-expected mortality by other methods.

Shahian D.M.Wolf R.E.Iezzoni L.I.Kirle L.Normand S.-L.T.

2010-12-23T23:59:59.000Z

371

Harvard Forest Environmental Measurement Site  

E-Print Network [OSTI]

Harvard University #12;Site Descrip>on · Mixed hardwood and conifer forest · 40Harvard Forest Environmental Measurement Site Petersham, MA Evan Goldman interannual variability and long-term trends in fluxes and forest physiological responses

372

Improved sample size determination for attributes and variables sampling  

SciTech Connect (OSTI)

Earlier INMM papers have addressed the attributes/variables problem and, under conservative/limiting approximations, have reported analytical solutions for the attributes and variables sample sizes. Through computer simulation of this problem, we have calculated attributes and variables sample sizes as a function of falsification, measurement uncertainties, and required detection probability without using approximations. Using realistic assumptions for uncertainty parameters of measurement, the simulation results support the conclusions: (1) previously used conservative approximations can be expensive because they lead to larger sample sizes than needed; and (2) the optimal verification strategy, as well as the falsification strategy, are highly dependent on the underlying uncertainty parameters of the measurement instruments. 1 ref., 3 figs.

Stirpe, D.; Picard, R.R.

1985-01-01T23:59:59.000Z

373

The Chuva Project: How Does Convection Vary across Brazil?  

Science Journals Connector (OSTI)

CHUVA, meaning “rain” in Portuguese, is the acronym for the Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud-Resolving Modeling and to the Global Precipitation Measurement (GPM). The CHUVA project has conducted five ...

Luiz A. T. Machado; Maria A. F. Silva Dias; Carlos Morales; Gilberto Fisch; Daniel Vila; Rachel Albrecht; Steven J. Goodman; Alan J. P. Calheiros; Thiago Biscaro; Christian Kummerow; Julia Cohen; David Fitzjarrald; Ernani L. Nascimento; Meiry S. Sakamoto; Christopher Cunningham; Jean-Pierre Chaboureau; Walter A. Petersen; David K. Adams; Luca Baldini; Carlos F. Angelis; Luiz F. Sapucci; Paola Salio; Henrique M. J. Barbosa; Eduardo Landulfo; Rodrigo A. F. Souza; Richard J. Blakeslee; Jeffrey Bailey; Saulo Freitas; Wagner F. A. Lima; Ali Tokay

2014-09-01T23:59:59.000Z

374

Interaction between surface and atmosphere in a convective boundary layer /  

E-Print Network [OSTI]

II.4) to measure vertical profiles of wind speed, direction,a larger vertical gradient of horizontal wind-speed in theintense vertical mixing, resulting in constant wind speed,

Garai, Anirban

2013-01-01T23:59:59.000Z

375

Effect of a horizontal magnetic field on convective instabilities in mercury  

E-Print Network [OSTI]

L-455 Effect of a horizontal magnetic field on convective instabilities in mercury S. Fauve, C on the three-dimensional instabilities which occur in a Rayleigh-Bénard experiment with mercury is studied which occur in a Rayleigh-Benard experi- ment in mercury, a low Prandtl number fluid. (The Prandtl

Boyer, Edmond

376

A numerical investigation of natural convection heat transfer within horizontal spent-fuel assemblies  

SciTech Connect (OSTI)

A numerical investigation of natural convection heat transfer is carried out for a single, horizontal, spent-fuel assembly in an environment typical of spent-fuel transportation systems as well as some dry storage/disposal scenarios. The objective is to predict computationally the convective heat transfer trends for horizontal spent fuel and to compare the results to data taken in a supporting experimental effort. The predicted data consist of thermal and flow fields throughout the assembly for a wide range of Rayleigh number, as well as numerically obtained Nusselt-number data that are correlated as a function of Rayleigh number. Both laminar and turbulent approaches are examined for a Boussinesq fluid with Pr = 0.7. The data predict the existence of a conduction-dominated regime, a transition regime, and a convection regime. Compared with the laminar approach, a significant improvement in the predicted Nusselt number is obtained for large Rayleigh numbers when a turbulence model is employed. This lends additional support to the experimental evidence that a transition to turbulent flow occurs for Rayleigh numbers greater than 10{sup 7}. Overall, the numerically predicted heat transfer trends compare well with previously obtained experimental data, and the computed assembly Nusselt numbers generally reside within the range of experimental uncertainty. The predicted thermal and flow fields further provide a numerical flow visualization capability that enhances the understanding of natural convection in horizontal spent fuel and allows improved physical interpretation of the experimental data.

Canaan, R.E. [Lawrence Livermore National Lab., CA (United States); Klein, D.E. [Univ. of Texas System, Austin, TX (United States)

1998-08-01T23:59:59.000Z

377

Asymptotic Behavior of the Global Attractors to the Boussinesq System for Rayleigh-Bnard Convection  

E-Print Network [OSTI]

Asymptotic Behavior of the Global Attractors to the Boussinesq System for Rayleigh study asymptotic behavior of the global attractors to the Boussinesq sys- tem for Rayleigh-Bénard convection at large Prandtl number. In particular, we show that the global attractors to the Boussinesq

Wang, Xiaoming

378

Non-Oberbeck-Boussinesq effects in three-dimensional Rayleigh-Bénard convection  

Science Journals Connector (OSTI)

To study the classical problem of Rayleigh-Bénard convection, i.e. a fluid layer confined between a heating-plate at the bottom and a cooling-plate at the top, a common assumption is that all material properti...

Susanne Horn; Olga Shishkina; Claus Wagner

2011-01-01T23:59:59.000Z

379

Dynamic RadiativeConvective Equilibria Using GCM Column Physics ISAAC M. HELD  

E-Print Network [OSTI]

Dynamic Radiative­Convective Equilibria Using GCM Column Physics ISAAC M. HELD NOAA and Oceanic Sciences, Department of Geosciences, Princeton University, Princeton, New Jersey BRUCE WYMAN NOAA author address: Dr. Isaac M. Held, NOAA/Geo- physical Fluid Dynamics Laboratory, Princeton University

380

EulerianEulerian two-phase numerical simulation of nanofluid laminar forced convection in a microchannel  

E-Print Network [OSTI]

by a cooling system to guarantee their appropriate performance. One possible way to cool these devises canEulerian­Eulerian two-phase numerical simulation of nanofluid laminar forced convection August 2010 Accepted 5 August 2010 Keywords: Nanofluid Microchannel Two-phase Laminar Heat transfer a b

Harting, Jens

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


381

ThermalEngineeringLaboratory,VanderbiltUniversity Convection Heat Transfer of Nanofluids in Commercial  

E-Print Network [OSTI]

in Commercial Electronic Cooling Systems N.A. Roberts and D.G. Walker Department of Mechanical Engineering in real systems · Benefits of nanofluids ­ reduced sedimentation and viscosity ­ reduced damageThermalEngineeringLaboratory,VanderbiltUniversity Convection Heat Transfer of Nanofluids

Walker, D. Greg

382

Morphology, Intensity, and Rainfall Production of MJO Convection: Observations from DYNAMO Shipborne Radar and TRMM  

Science Journals Connector (OSTI)

This study uses DYNAMO shipborne (R/V Revelle) radar and TRMM Precipitation Radar (PR) datasets to investigate MJO-associated convective systems in specific organizational modes (MCS vs. sub-MCS, linear vs. non-linear). The Revelle radar sampled ...

Weixin Xu; Steven A. Rutledge

383

Compact fluorescent lamp using horizontal and vertical insulating septums and convective venting geometry  

DOE Patents [OSTI]

A novel design is described for a compact fluorescent lamp, including a lamp geometry which will increase light output and efficacy of the lamp in a base down operating position by providing horizontal and vertical insulating septums positioned in the ballast compartment of the lamp to provide a cooler coldspot. Selective convective venting provides additional cooling of the ballast compartment. 9 figs.

Siminovitch, M.

1998-02-10T23:59:59.000Z

384

Lattice Boltzmann simulations of a time-dependent natural convection problem  

E-Print Network [OSTI]

Lattice Boltzmann simulations of a time-dependent natural convection problem Beno^it Trouette September 2, 2013 Abstract A two-dimensional double Multiple-Relaxation-Time thermal lattice Boltzmann-dependent flows as well as the space and time convergence orders. Keywords: Thermal lattice Boltzmann method

Boyer, Edmond

385

Parameterized Mesoscale Forcing Mechanisms for Initiating Numerically Simulated Isolated Multicellular Convection  

E-Print Network [OSTI]

Multicellular Convection ADRIAN M. LOFTUS* School of Meteorology, University of Oklahoma, Norman, Oklahoma DANIEL B. WEBER Center for Analysis and Prediction of Storms, University of Oklahoma, Norman, Oklahoma CHARLES A. DOSWELL III Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma

Doswell III, Charles A.

386

TACKLEY ET AL.:THERMO-CHEMICAL PHILOSOPHY Numerical and laboratory studies of mantle convection: Philosophy,  

E-Print Network [OSTI]

TACKLEY ET AL.:THERMO-CHEMICAL PHILOSOPHY 1 Numerical and laboratory studies of mantle convection: Philosophy, accomplishments and thermo-chemical structure and evolution Paul J. Tackley Department of Earth how the solid parts of Earth and other terrestrial planets work. Here, the general philosophy

Tackley, Paul J.

387

Numerical computation of 3D heat transfer in complex parallel convective exchangers using generalized Graetz modes  

E-Print Network [OSTI]

Numerical computation of 3D heat transfer in complex parallel convective exchangers using insights into the most con- tributing structure to exchanges and transfers. Several examples of heat, whilst many other can be found in a recent review [12]. As quoted in [12] conjugate heat transfer

Paris-Sud XI, Université de

388

High-latitude ionospheric convection models derived from Defense Meteorological Satellite Program ion drift  

E-Print Network [OSTI]

Vladimir O. Papitashvili Space Physics Research Laboratory, University of Michigan, Ann Arbor, Michigan to the average solar wind (i.e., the ``quasi-viscous'' interaction) and to changes in the IMF By, Bz 0, and Bz, plasma convection, current systems 1. Introduction [2] Earth's magnetosphere is immersed in the solar

Michigan, University of

389

Evaluation of mesoscale convective systems in South America using multiple satellite products and an objectbased approach  

E-Print Network [OSTI]

Evaluation of mesoscale convective systems in South America using multiple satellite products­2003 in the La Plata river basin, southeastern South America, were analyzed with the Contiguous Rain Area (CRA; Salby and Callaghan, 1997]. However, in South America, few studies have assessed the validity

Ebert, Beth

390

Natural convection in tunnels at Yucca Mountain and impact on drift seepage  

SciTech Connect (OSTI)

The decay heat from radioactive waste that is to be disposed in the once proposed geologic repository at Yucca Mountain (YM) will significantly influence the moisture conditions in the fractured rock near emplacement tunnels (drifts). Additionally, large-scale convective cells will form in the open-air drifts and will serve as an important mechanism for the transport of vaporized pore water from the fractured rock in the drift center to the drift end. Such convective processes would also impact drift seepage, as evaporation could reduce the build up of liquid water at the tunnel wall. Characterizing and understanding these liquid water and vapor transport processes is critical for evaluating the performance of the repository, in terms of water-induced canister corrosion and subsequent radionuclide containment. To study such processes, we previously developed and applied an enhanced version of TOUGH2 that solves for natural convection in the drift. We then used the results from this previous study as a time-dependent boundary condition in a high-resolution seepage model, allowing for a computationally efficient means for simulating these processes. The results from the seepage model show that cases with strong natural convection effects are expected to improve the performance of the repository, since smaller relative humidity values, with reduced local seepage, form a more desirable waste package environment.

Halecky, N.; Birkholzer, J.T.; Peterson, P.

2010-04-15T23:59:59.000Z

391

Marangoni convection induced by a nonlinear temperature-dependent surface tension  

E-Print Network [OSTI]

23 Marangoni convection induced by a nonlinear temperature-dependent surface tension A. Cloot and G'instabilité de Marangoni dans une mince lame horizontale de fluide lorsque la tension de surface est une fonction ofthe surface- tension with respect to the temperature is studied. This behaviour is typical of some

Paris-Sud XI, Université de

392

Time-independent square patterns in surface-tension-driven Benard convection  

E-Print Network [OSTI]

Time-independent square patterns in surface-tension-driven Be´nard convection Michael F. Schatza The transition between hexagonal and square patterns is investigated in laboratory experiments on surface-tension, the transition from hexagons to other patterns was unexplored for the surface-tension-driven regime of Be

Texas at Austin. University of

393

Simulation and Cryogenic Experiments of Natural Convection for the Titan Montgolfiere  

E-Print Network [OSTI]

Simulation and Cryogenic Experiments of Natural Convection for the Titan Montgolfiere Yuri Feldman for prediction of the buoyancy of single- and double- walled balloons in a cryogenic environment such as Titan at cryogenic conditions. The predicted buoyancy and temperature fields compare favorably with experiments

Dabiri, John O.

394

Cryogenic cooling system of HTS transformers by natural convection of subcooled liquid nitrogen  

E-Print Network [OSTI]

Cryogenic cooling system of HTS transformers by natural convection of subcooled liquid nitrogen Ho-793, South Korea Abstract Heat transfer analysis on a newly proposed cryogenic cooling system is performed, and over-load operation. One of the key techniques to realize these advantages in practice is the cryogenic

Chang, Ho-Myung

395

Lightning flash rate and chemistry simulation of tropical island convection using a cloud-resolved model  

E-Print Network [OSTI]

Lightning flash rate and chemistry simulation of tropical island convection using a cloud schemes (FRPSs) and estimating the average NO production per lightning flash in this unique storm type network (LINET) provided lightning flash data for the model and a lightning placement scheme injected

Maryland at College Park, University of

396

Relationships between lightning and properties of convective cloud Joanna M. Futyan1,2  

E-Print Network [OSTI]

August 2007. [1] Satellite observations of convective system properties and lightning flash rate are used with the lightning flash rate. A roughly second order power-law fit to the mean radar echo top height above the 0°C isotherm is shown to capture both regional and land-ocean contrasts in lightning occurrence and flash rate

397

Three-dimensional simulations of the upper radiation–convection transition layer in subgiant stars  

Science Journals Connector (OSTI)

......University of Science Technology, Hong Kong...subgiant of one solar mass and a lower-gravity...of convection cell sizes. Differences...contrast with 2 106 cells observed on the solar surface. Observations...800 times the solar radius (Gray...approximately 600 cells would be needed......

F. J. Robinson; P. Demarque; L. H. Li; S. Sofia; Y.-C. Kim; K. L. Chan; D. B. Guenther

2004-02-01T23:59:59.000Z

398

A numerical simulation of supersonic turbulent convection relating to the formation of the Solar system  

Science Journals Connector (OSTI)

......formation of the Solar system A. J. R...California Institute of Technology, Pasadena, California...from which the Solar system formed. The...giant convective cells, which span the whole layer. At cell boundaries the downflows...theory (MLT) of Solar system origin. Here......

A. J. R. Prentice; C. P. Dyt

2003-05-11T23:59:59.000Z

399

Testing turbulent convection theory in solar models – II. Solar p-mode oscillations  

Science Journals Connector (OSTI)

......Reynolds number in the solar convection zone makes the turbulent energy spectrum greatly...and concluded that solar models considering...turbulent kinetic energy could result in better...turbulence in our solar models in the present...of China through project number 10303007......

J. Y. Yang; Y. Li

2007-02-11T23:59:59.000Z

400

Eects of convection instability due to incompatibility between ocean dynamics and surface forcings  

E-Print Network [OSTI]

- bility between a surface temperature climatology and a given ocean model, into which the climatology by thermal and wind forcing only. Initially, the temperature climatology is forcefully assimilated climatology. In areas characterized by sharp oceanic fronts and high convective activity, the OGCM, due

Paris-Sud XI, Université de

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


401

Three Dimensional Simulation of Rayleigh-Bénard Convection for Rapid Microscale Polymerase Chain Reaction  

E-Print Network [OSTI]

Rayleigh-Bénard convection has been extensively studied in literature owing to its ubiquitous nature. However, most of the studies have been confined to geometries where the aspect ratio of the cylinder was less than 1. Here we study the motion...

Muddu, Radha Malini Gowri

2012-02-14T23:59:59.000Z

402

Using CASA IP1 to Diagnose Kinematic and Microphysical Interactions in a Convective Storm  

E-Print Network [OSTI]

bulk hydrometeor identification and dual-Doppler wind retrievals. Comparisons are made with the nearby-band radars are used to observe a convective storm. A fuzzy logic hydrometeor identification algorithm the type of echoes in the network based on storm identification al- gorithms, then allocates radars

Rutledge, Steven

403

Internal wave generation by convection in water. Part 2. Numerical simulations  

E-Print Network [OSTI]

Water's density maximum at 4C makes it well suited to study internal gravity wave excitation by convection: an increasing temperature profile is unstable to convection below 4C, but stably stratified above 4C. We present numerical simulations of water near its density maximum in a two dimensional tank, similar to the experiment described in a companion paper (Le Bars et al. 2015). The simulations agree very well with the experiments, despite differences in lateral boundary conditions in the two systems. We successfully model the damping of waves in the simulations using linear theory, provided we do not take the weak damping limit typically used in the literature. In order to isolate the physical mechanism exciting internal waves, we use the novel spectral code Dedalus to run several simulations of the simulation. We use data from the full simulation as source terms in two simplified models of internal wave excitation by convection: bulk excitation by convective Reynolds stresses, and interface forcing via th...

Lecoanet, Daniel; Burns, Keaton J; Vasil, Geoffrey M; Brown, Benjamin P; Quataert, Eliot; Oishi, Jeffrey S

2014-01-01T23:59:59.000Z

404

Can a Convective Cloud Feedback Help to Eliminate Winter Sea Ice at High CO2 Concentrations?  

E-Print Network [OSTI]

have remote effects on global climate as well. Accurate forecasting of winter sea ice has significantCan a Convective Cloud Feedback Help to Eliminate Winter Sea Ice at High CO2 Concentrations? DORIAN) ABSTRACT Winter sea ice dramatically cools the Arctic climate during the coldest months of the year and may

Tziperman, Eli

405

Influence of Sea Surface Temperature on Humidity and Temperature in the Outflow of Tropical Deep Convection  

E-Print Network [OSTI]

-Service Aircraft (MOZAIC) project are analyzed in the vicinity of deep convective outflow to study the variationsInfluence of Sea Surface Temperature on Humidity and Temperature in the Outflow of Tropical Deep upper-tropospheric temperature and humidity by the Mea- surement of Ozone and Water Vapor by Airbus In

Johnson, Richard H.

406

Do the Tallest Convective Cells over the Tropical Ocean Have Slow Updrafts?  

Science Journals Connector (OSTI)

Far from continents, a few storms lift precipitation-size ice particles into the stratosphere, 17 to 18 km above the tropical ocean. This study is the first to examine the observed properties of a large sample of these extremely tall convective ...

Owen A. Kelley; John Stout; Michael Summers; Edward J. Zipser

2010-05-01T23:59:59.000Z

407

10.12 CONVECTION INITIATION AND MISOCYCLONE DEVELOMENT: IS THERE A LINK ?  

E-Print Network [OSTI]

Kingsmill·, and Carl Young £ · University of Colorado, CIRES, Boulder, Colorado Desert Research Institute to horizontal shear instabilities can produce wave pattern that produce small scale ( 4 km) vertical vortic- ity with the initiation of deep convection along the Florida Peninsula using a net- work of anemometers. Since

408

Adaptive Thermal Management for Portable System Batteries by Forced Convection Cooling  

E-Print Network [OSTI]

Adaptive Thermal Management for Portable System Batteries by Forced Convection Cooling Qing Xie the battery longevity increases. This is the first work that formulates the adaptive thermal management is proposed to derive the ATMB policy. Keywords-- battery system; adaptive thermal management; forced

Pedram, Massoud

409

Radar, satellite, and lightning characteristics of select mesoscale convective systems in Texas  

E-Print Network [OSTI]

This study compares radar data from the League City, Texas WSR-88D and cloud-to-ground (CG) lightning data for a set of eight mesoscale convective systems (MCSs) which occur at various stages of development along the upper Texas Gulf Coast. Vertical...

Toracinta, Ernest Richard

2012-06-07T23:59:59.000Z

410

Magneto-convective models of red dwarfs: constraints imposed by the lithium abundance  

E-Print Network [OSTI]

Magnetic fields impede the onset of convection, thereby altering the thermal structure of a convective envelope in a low mass star: this has an effect on the amount of lithium depletion in a magnetized star. In order to quantify this effect, we have applied a magneto-convective model to two low mass stars for which lithium abundances and precise structural parameters are known: YY Gem and CU Cnc. For both stars, we have obtained models which satisfy empirical constraints on the following parameters: R, L, surface magnetic field strength, and Li abundance. In the case of YY Gem, we have obtained a model which satisfies the empirical constraints with an internal magnetic field of several megagauss: such a field strength is within the range of a dynamo where the field energy is in equipartition with rotational energy deep inside the convection zone. However, in the case of CU Cnc, the Li requires an internal magnetic field which is probably too strong for a dynamo origin: we suggest possible alternatives which m...

MacDonald, J

2015-01-01T23:59:59.000Z

411

The performance of PEM fuel cells fed with oxygen through the free-convection mode  

E-Print Network [OSTI]

The performance of PEM fuel cells fed with oxygen through the free-convection mode Pei-Wen Li; accepted 27 September 2002 Abstract The feasibility and restrictions of feeding oxygen to a PEM fuel cell in the fuel cell. Experimental tests were conducted for one PEM fuel cell stack and two single PEM fuel cell

412

Mantle convection with strong subduction zones Clinton P. Conrad* and Bradford H. Hager  

E-Print Network [OSTI]

for convection, which includes an expression for the energy needed to deform the oceanic lithosphere the entire oceanic lithosphere, subduction is an ef®cient mechanism for converting the signi®cant negative method for implementing subduction that parametrizes the deformation of the oceanic lithosphere within

Conrad, Clint

413

The Tilt of the Leading Edge of Mesoscale Tropical Convective Lines  

Science Journals Connector (OSTI)

The tilt with height of the leading edge of seven mesoscale convective lines in GATE is determined by two independent methods. When averaged over time and along the line axis, the tilt is found to he surprisingly shallow, between 20 and 35 ...

M. A. LeMone; G. M. Barnes; E. J. Szoke; E. J. Zipser

1984-03-01T23:59:59.000Z

414

Mesoscale Convective Systems and Their Synoptic-scale Environment in Finland  

Science Journals Connector (OSTI)

The environments which high-latitude intense and non-intense mesoscale convective systems (iMCSs and niMCSs) and smaller thunderstorm clusters (subMCS) develop in were studied using proximity soundings. Eight-year MCS statistics were created by ...

ARI-JUHANI PUNKKA; MARJA BISTER

415

BUBBLE CHARACTERISTICS AND CONVECTIVE EFFECTS IN THE FLOW BOILING HEAT TRANSFER OF BINARY MIXTURES  

E-Print Network [OSTI]

BUBBLE CHARACTERISTICS AND CONVECTIVE EFFECTS IN THE FLOW BOILING HEAT TRANSFER OF BINARY MIXTURES on the bubble growth and associated heat transfer phenomena. The present work focuses on obtaining the bubble. The bubble growth is observed using a high speed camera (1000 fps) under a magnification of 290X. The bubble

Kandlikar, Satish

416

Movement of oxygen from the atmosphere to the mitochondria occurs via several convective and diffusive steps  

E-Print Network [OSTI]

4111 Movement of oxygen from the atmosphere to the mitochondria occurs via several convective and diffusive steps (Weibel et al., 1981). In mammals, maximal rate of oxygen consumption (VOmax) is not limited by any one step of the oxygen cascade; rather limitations to VOmax are distributed across all steps

Bennett, Albert F.

417

An experimental investigation of convection heat transfer to supercritical carbon dioxide in miniature tubes  

E-Print Network [OSTI]

as an onboard coolant. Highly charged machine elements such as gas turbine blades, supercomputer elements of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Received 22 December 2001; received on the experimental data, correlations were developed for the axially-averaged Nusselt number of convection heat

Zhao, Tianshou

418

Convective flow of sisko fluid over a bidirectional stretching sheet  

E-Print Network [OSTI]

The present investigation discusses the flow and heat transfer characteristics of a steady three dimensional Sisko fluid. The flow is induced due to bidirectional stretching sheet. The influence of power-law index and stretching ratio on flow and heat transfer is studied thoroughly. Governing partial differential equations are reduced to coupled ordinary differential equations by suitable similarity variable. The resulting equations are then solved numerically by shooting method using adaptive Runge Kutta algorithm in combination with Broyden's method in the domain . The numerical results for the velocity and temperature fields are graphically presented and effects of the relevant parameters are discussed in detail. Moreover, the skin-friction coefficient and local Nusselt number for different values of the power-law index and stretching ratio are presented through tabulated data. The numerical results are verified with the results obtained by HAM. Additionally, the results are also validated with previously ...

Munir, Asif; Khan, Masood

2014-01-01T23:59:59.000Z

419

Secure Quantum Key Distribution using Continuous Variables of Single Photons  

Science Journals Connector (OSTI)

We analyze the distribution of secure keys using quantum cryptography based on the continuous variable degree of freedom of entangled photon pairs. We derive the information capacity of a scheme based on the spatial entanglement of photons from a realistic source, and show that the standard measures of security known for quadrature-based continuous variable quantum cryptography (CV-QKD) are inadequate. A specific simple eavesdropping attack is analyzed to illuminate how secret information may be distilled well beyond the bounds of the usual CV-QKD measures.

Lijian Zhang; Christine Silberhorn; Ian A. Walmsley

2008-03-18T23:59:59.000Z

420

A phenomenological model of thermal-hydraulics of convective boiling during the quenching of hot rod bundles  

SciTech Connect (OSTI)

After completion of the thermal-hydraulic model developed in a companion paper, the authors performed developmental assessment calculation of the model using steady-state and transient post-critical heat flux (CHF) data. This paper discusses the results of those calculations. The overall interfacial drag model predicted reasonable drag coefficients for both the nucleate boiling and the inverted annular flow (IAF) regimes. The predicted pressure drops agreed reasonably well with the measured data of two transient experiments, CCTF Run 14 and a Lehigh reflood test. The thermal-hydraulic model for post-CHF convective heat transfer predicted the rewetting velocities reasonably well for both experiments. The predicted average slope of the wall temperature traces for these tests showed reasonable agreement with the measured data, indicating that the transient-calculated precursory cooling rates agreed with measured data. The hot-patch model, in conjunction with the other thermal-hydraulic models, was capable of modeling the Winfrith post-CHF hot-patch experiments. The hot-patch model kept the wall temperatures at the specified levels in the hot-patch regions and did not allow any quench-front propagation from either the bottom or the top of the test section. The interfacial heat-transfer model tended to slightly underpredict the vapor temperatures. The maximum difference between calculated and measured vapor temperatures was 20%, with a 10% difference for the remainder of the runs considered. The wall-to-fluid heat transfer was predicted reasonably well, and the predicted wall temperatures were in reasonable agreement with measured data with a maximum relative error of less than 13%.

Unal, C.; Nelson, R.

1991-01-01T23:59:59.000Z

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


421

The TAOS Project Stellar Variability II. Detection of 15 Variable Stars  

SciTech Connect (OSTI)

The Taiwanese-American Occultation Survey (TAOS) project has collected more than a billion photometric measurements since 2005 January. These sky survey data - covering timescales from a fraction of a second to a few hundred days - are a useful source to study stellar variability. A total of 167 star fields, mostly along the ecliptic plane, have been selected for photometric monitoring with the TAOS telescopes. This paper presents our initial analysis of a search for periodic variable stars from the time-series TAOS data on one particular TAOS field, No. 151 (RA = 17{sup h} 30{sup m} 6.67{sup s}, Dec = 27 degrees, 17 minutes, 30 seconds, J2000), which had been observed over 47 epochs in 2005. A total of 81 candidate variables are identified in the 3 square degree field, with magnitudes in the range 8 < R < 16. On the basis of the periodicity and shape of the lightcurves, 32 variables, 18 of which were previously unknown, are classified as RR Lyrae, Cepheid, {delta} Scuti, SX Phonencis, semi-regular and eclipsing binaries.

Mondal, S; Lin, C C; Zhang, Z W; Alcock, C; Axelrod, T; Bianco, F B; Byun, Y I; Coehlo, N K; Cook, K H; Dave, R; Kim, D W; King, S K; Lee, T; Lehner, M J; Lin, H C; Marshall, S L; Protopapas, P; Rice, J A; Schwamb, M E; Wang, J H; Wang, S Y; Wen, C Y

2010-01-28T23:59:59.000Z

422

Constitutive correlations for wire-wrapped subchannel analysis under forced and mixed convection conditions. Part 1. [LMFBR  

SciTech Connect (OSTI)

A simple subchannel analysis method based on the ENERGY series of codes, ENERGY-IV, has been established for predicting the temperature field in a single isolated wire-wrapped Liquid Metal Fast Breeder Reactor (LMFBR) subassembly under steady state forced and mixed convection conditions. The ENERGY-IV is a totally empirical code employed for fast running purposes and requires well calibrated lead length averaged input parameters to achieve satisfactory predictions. These input parameters were identified to be the inlet flow split parameters, the subchannel friction factors, the interchannel mixing parameters, the conduction shape factor, and the transverse velocity at the edge gap. Experiments were performed in a 37-pin wire-wrapped rod bundle with a geometry between that of a typical LMFBR fuel subassembly and blanket subassembly for filling the gap in the available data base for the input parameters. The isokinetic extraction method for measuring subchannel velocity, the pitot-static probe for measuring pressure drop, and the salt tracer injection method for estimating the interchannel mixing, were used in these experiments.

Cheng, S.K.; Todreas, N.E.

1984-08-01T23:59:59.000Z

423

Connecting Atlantic temperature variability and biological cycling in two earth system models  

Science Journals Connector (OSTI)

Abstract Connections between the interdecadal variability in North Atlantic temperatures and biological cycling have been widely hypothesized. However, it is unclear whether such connections are due to small changes in basin-averaged temperatures indicated by the Atlantic Multidecadal Oscillation (AMO) Index, or whether both biological cycling and the AMO index are causally linked to changes in the Atlantic Meridional Overturning Circulation (AMOC). We examine interdecadal variability in the annual and month-by-month diatom biomass in two Earth System Models with the same formulations of atmospheric, land, sea ice and ocean biogeochemical dynamics but different formulations of ocean physics and thus different AMOC structures and variability. In the isopycnal-layered ESM2G, strong interdecadal changes in surface salinity associated with changes in AMOC produce spatially heterogeneous variability in convection, nutrient supply and thus diatom biomass. These changes also produce changes in ice cover, shortwave absorption and temperature and hence the AMO Index. Off West Greenland, these changes are consistent with observed changes in fisheries and support climate as a causal driver. In the level-coordinate ESM2M, nutrient supply is much higher and interdecadal changes in diatom biomass are much smaller in amplitude and not strongly linked to the AMO index.

Anand Gnanadesikan; John P. Dunne; Rym Msadek

2014-01-01T23:59:59.000Z

424

Reading with fixed and variable character pitch  

Science Journals Connector (OSTI)

We compared the effects of fixed and variable (proportional) spacing on reading speeds and found variable pitch to yield better performance at medium and large character sizes and...

Arditi, Aries; Knoblauch, Kenneth; Grunwald, Ilana

1990-01-01T23:59:59.000Z

425

Kinematics of Turbulence Convected by a Random Wave Field  

Science Journals Connector (OSTI)

Turbulent velocity spectra measured beneath wind waves show a large enhancement about the central wave frequency. A “5/3" frequency dependence can be seen both above and below the central peak, but with an apparent increase in spectral density at ...

J. L. Lumley; E. A. Terray

1983-11-01T23:59:59.000Z

426

Evaluation of convection-permitting model simulations of cloud populations associated with the Madden-Julian Oscillation using data collected during the AMIE/DYNAMO field campaign  

SciTech Connect (OSTI)

Regional cloud permitting model simulations of cloud populations observed during the 2011 ARM Madden Julian Oscillation Investigation Experiment/ Dynamics of Madden-Julian Experiment (AMIE/DYNAMO) field campaign are evaluated against radar and ship-based measurements. Sensitivity of model simulated surface rain rate statistics to parameters and parameterization of hydrometeor sizes in five commonly used WRF microphysics schemes are examined. It is shown that at 2 km grid spacing, the model generally overestimates rain rate from large and deep convective cores. Sensitivity runs involving variation of parameters that affect rain drop or ice particle size distribution (more aggressive break-up process etc) generally reduce the bias in rain-rate and boundary layer temperature statistics as the smaller particles become more vulnerable to evaporation. Furthermore significant improvement in the convective rain-rate statistics is observed when the horizontal grid-spacing is reduced to 1 km and 0.5 km, while it is worsened when run at 4 km grid spacing as increased turbulence enhances evaporation. The results suggest modulation of evaporation processes, through parameterization of turbulent mixing and break-up of hydrometeors may provide a potential avenue for correcting cloud statistics and associated boundary layer temperature biases in regional and global cloud permitting model simulations.

Hagos, Samson M.; Feng, Zhe; Burleyson, Casey D.; Lim, Kyo-Sun; Long, Charles N.; Wu, Di; Thompson, Gregory

2014-11-12T23:59:59.000Z

427

Natural convection in shallow enclosures with differentially heated endwalls  

SciTech Connect (OSTI)

We consider a low-aspect-ratio two-dimensional rectangular cavity, differentially heated with an arbitrarily large horizontal temperature difference. Steady-state results obtained from numerical solutions of the transient Navier--Stokes equations are given for air using the ideal gas law and Sutherland law transport properties. We clarify the different flow regimes possible by using numerical results for aspect ratios 0.025less than or equal toAless than or equal to1 and for Rayleigh numbers (based on height) 10/sup 2/less than or equal toRaless than or equal to10/sup 9/. We present Nusselt numbers, and temperature and velocity distributions, and compare them with existing data. At high Ra in the Boussinesq limit we show the existence of weak secondary and tertiary flows in the core of the cavity. In addition we present novel solutions in the non-Boussinesq regime. We find that the classical parallel flow solution, accurate in the core of the cavity in the Boussinesq limit, does not exist when variable properties are introduced. For higher Rayleigh numbers, we generalized the well-known analytical boundary layer solution of Gill. The non-Boussinesq solutions show greatly reduced static pressure levels and lower critical Rayleigh numbers.

Paolucci, S.; Chenoweth, D.R.

1988-08-01T23:59:59.000Z

428

Operating Reserves and Variable Generation  

SciTech Connect (OSTI)

This report tries to first generalize the requirements of the power system as it relates to the needs of operating reserves. It also includes a survey of operating reserves and how they are managed internationally in system operations today and then how new studies and research are proposing they may be managed in the future with higher penetrations of variable generation.

Ela, E.; Milligan, M.; Kirby, B.

2011-08-01T23:59:59.000Z

429

Cosmological models with variable constants  

E-Print Network [OSTI]

The behavior of the constants, G,c,h,a,e,m and Lambda, considering them as variable, in the framework of a flat cosmological model with FRW symmetries described by a bulk viscous fluid and considering mechanisms of adiabatic matter creation are investigated. Within two models; one with radiation predominance and another of matter predominance, this behavior are studied.

J. A. Belinchon

1999-07-01T23:59:59.000Z

430

Variability in Automated Responses of Commercial Buildings and Industrial  

E-Print Network [OSTI]

consumption of commercial buildings and industrial facilities (C&I facilities) during Demand Response (DR. Keywords: demand response, baseline models, load prediction, error analysis, variability, measurement in the past ­ either with relays that interrupt power to air conditioners and water heaters [1], [2

431

HEART RATE VARIABILITY AS DETERMINISM WITH JUMP STOCHASTIC PARAMETERS  

E-Print Network [OSTI]

HEART RATE VARIABILITY AS DETERMINISM WITH JUMP STOCHASTIC PARAMETERS JIONGXUAN ZHENG, JOE SKUFCA, AND ERIK BOLLT§ Abstract. We use measured heart rate information (RR intervals) to develop a one with persistence which causes the heart rate and rhythm system to wander about a bifurcation point. We propose

Bollt, Erik

432

Characterization of initiation and growth of selected severe convective storms over Central Europe with MSG-SEVIRI  

Science Journals Connector (OSTI)

The early development of severe convective storms over Central Europe was investigated based on nine cases from the year 2012. Using data from the SEVIRI imaging radiometer aboard the geostationary Meteosat satellite, dynamical and microphysical ...

Fabian Senf; Felix Dietzsch; Anja Hünerbein; Hartwig Deneke

433

The Effect of Heavy Oil Viscosity Reduction by Solvent Dissolution on Natural Convection in the Boundary Layer of VAPEX  

Science Journals Connector (OSTI)

We have studied the effect of viscosity on natural convection in the boundary layer of the vapor extraction (VAPEX) process. VAPEX is a heavy oil recovery method that uses solvents to reduce oil viscosity, and...

Mohammad Javaheri; Jalal Abedi

2013-09-01T23:59:59.000Z

434

An Analytical Model for Determination of the Solvent Convective Dispersion Coefficient in the Vapor Extraction Heavy Oil Recovery Process  

Science Journals Connector (OSTI)

In this article, a new model is developed to determine the solvent convective dispersion coefficient in a solvent vapor extraction (VAPEX) heavy oil recovery process. It is assumed that solvent mass transfer b...

Mohammad Derakhshanfar; Yongan Gu

2012-03-01T23:59:59.000Z

435

List of Publications A Numerical Study of Transient Mixed Convection Flows in a Thermal Storage Tank, J. Solar  

E-Print Network [OSTI]

List of Publications A Numerical Study of Transient Mixed Convection Flows in a Thermal Storage Tank, J. Solar Energy Eng. 105, 246­253 (1983) (with A.M.C. Chan & D. Giusti) An Approximate Analytical

Smereka, Peter

436

Rfrences bibliographiques [1] R. E. Kelly, The onset and development of Rayleigh-Bnard convection in shear flows: a  

E-Print Network [OSTI]

1 Références bibliographiques [1] R. E. Kelly, The onset and development of Rayleigh Publication, London, 1977, pp. 65-79. [2] R. E. Kelly, The onset and development of thermal convection

Paris-Sud XI, Université de

437

Mixed convection and high-pressure low-flow steam cooling data from a 64-rod bundle  

SciTech Connect (OSTI)

Heat transfer data were obtained from low flow steam cooling experiments in a partially uncovered 64-rod bundle. These tests indicated that free convection effects were superimposed on the laminar and turbulent forced convection heat transfer. This paper describes the influence of buoyancy on laminar and turbulent forced convection heat transfer coefficients. Mechanisms due to buoyancy which alter the local heat transfer are summarized. Criteria indicating the importance of buoyancy on laminar and turbulent upflow in a vertical pipe were developed and compared to other criteria found in the literature. These criteria were used to determine the steam cooling data with significant buoyancy influence. Data with buoyancy influence were compared to mixed convection correlations and to a numerical study for rod bundles.

Sozer, A.

1984-01-01T23:59:59.000Z

438

Distribution of Liposomes into Brain and Rat Brain Tumor Models by Convection-Enhanced Delivery Monitored with Magnetic Resonance Imaging  

Science Journals Connector (OSTI)

...Convection-Enhanced Delivery Monitored with Magnetic Resonance Imaging Ryuta Saito...B, T 1-weighted coronal magnetic resonance image of a 9L-2 rat...assistance, Dr. David Newitt (Magnetic Resonance Science Center, University of California...

Ryuta Saito; John R. Bringas; Tracy R. McKnight; Michael F. Wendland; Christoph Mamot; Daryl C. Drummond; Dmitri B. Kirpotin; John W. Park; Mitchel S. Berger; and Krys S. Bankiewicz

2004-04-01T23:59:59.000Z

439

Chaotic flow in a 2D natural convection loop with heat flux boundaries William F. Louisos a,b,  

E-Print Network [OSTI]

- clear reactors, and gas turbine blade cooling among many others [4­6]. The nonlinear dynamics. Examples of natural convection cells occurring in engineering devices include solar water heaters, nu

Danforth, Chris

440

A Synthetic Aperture Radar–Based Climatology of Open-Cell Convection over the Northeast Pacific Ocean  

Science Journals Connector (OSTI)

This paper presents an 8-yr (1999–2006) climatology of the frequency of open-cell convection over the northeastern Pacific Ocean and the thermodynamic and kinematic environment associated with its development. The climatology is based on ...

Todd D. Sikora; George S. Young; Caren M. Fisher; Matthew D. Stepp

2011-03-01T23:59:59.000Z

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


441

Evolution of cloud-to-ground lightning characteristics within the convective region of a midlatitude squall line  

E-Print Network [OSTI]

has been examined over a period of 49 minutes. Lightning data from the National Severe Storms Laboratory lightning detection network combined with seven dual-Doppler analyses provided a unique dataset in which to study this Mesoscale Convective System...

Billingsley, David Brian

2012-06-07T23:59:59.000Z

442

Dependence of Tropospheric Temperature on the Parameterization of Cumulus Convection in the GLAS Model of the General Circulation  

Science Journals Connector (OSTI)

Analysis of the simulation of seasonal change by the GLAS model of the general circulation reveals deficiencies in the simulation of tropospheric temperature and of convective cloud cover. These interrelated deficiencies are due to a spurious ...

H. Mark Helfand

1981-01-01T23:59:59.000Z

443

An Alternative Mass Flux Profile in the Kain–Fritsch Convective Parameterization and Its Effects in Seasonal Precipitation  

Science Journals Connector (OSTI)

The authors have altered the vertical profile of updraft mass flux detrainment in an implementation of the Kain–Fritsch2 (KF2) convective parameterization within the fifth-generation Pennsylvania State University–National Center for Atmospheric ...

Christopher J. Anderson; Raymond W. Arritt; John S. Kain

2007-10-01T23:59:59.000Z

444

Squall Lines and Convectively Coupled Gravity Waves in the Tropics: Why Do Most Cloud Systems Propagate Westward?  

Science Journals Connector (OSTI)

The coupling between tropical convection and zonally propagating gravity waves is assessed through Fourier analysis of high-resolution (3-hourly, 0.5°) satellite rainfall data. Results show the familiar enhancement in power along the dispersion ...

Stefan N. Tulich; George N. Kiladis

2012-10-01T23:59:59.000Z

445

Quarterly Journal of the Royal Meteorological Society Q. J. R. Meteorol. Soc. (2013) Phenomenology of Sahelian convection observed in Niamey  

E-Print Network [OSTI]

Quarterly Journal of the Royal Meteorological Society Q. J. R. Meteorol. Soc. (2013) Phenomenology SM. 2013. Phenomenology of Sahelian convection observed in Niamey during the early monsoon. Q. J. R

Guichard, Francoise

446

Momentum transport processes in the stratiform regions of mesoscale convective systems over the western Pacific warm pool  

E-Print Network [OSTI]

Momentum transport by the stratiform components of mesoscale convective systems (MCSs) during the Tropical Ocean–Global Atmosphere Coupled Ocean–Atmosphere Response Experiment in December 1992 is investigated using a ...

Mechem, David B.; Chen, Shuyi S.; Houze, Robert A. Jr.

2006-04-01T23:59:59.000Z

447

Variable trim compressor – a new approach to variable compressor geometry  

Science Journals Connector (OSTI)

ABSTRACT Variable compressor geometry can be employed irrespective of the combustion process selected. It provides the capability of improving response behavior, reducing fuel consumption or cutting exhaust emissions from exhaust-gas turbocharged engines. Previous concepts on variable compressor geometries have been based on using inlet guide vanes to impart a swirl motion to the air that is fed to the compressor with the ultimate aim of enhancing the angle at which the flow of air enters the blade channel. This paper shows an inlet guide configuration that is based on a different operating principle. The inlet guide assembly shown here is designed in a way that minimizes any pressure losses even at high flow rates. Numerical studies were carried out using CFD to test the system's sensitivity. Based on these studies, a rigid conical element was then produced and the potential for increasing efficiency (up to 7% points) and shifting the surge line (up to 33%) verified on a turbocharger test bench. Finally, a design configuration is presented for a variable system.

P. Grigoriadis; S. Müller; A. Benz; M. Sens

2012-01-01T23:59:59.000Z

448

Natural convection phenomena in a nuclear power plant during a postulated TMLB' accident  

SciTech Connect (OSTI)

After the TMI (Three Mile Island) accident, there has been significant interest in analyzing and understanding the phenomena that may occur in a PWR (Pressurized Water Reactor) accident which may lead to partial or total core meltdown and degradation. Natural convection is one of the important phenomena. In the present paper the results of two numerical simulations of (1) four-loop PWR and (2) three-loop PWR are presented. The simulations were performed with the COMMIX(2) computer code. Our analysis shows that in severe accident scenarios, natural convection phenomena does occur and that it helps to delay core degradation by transferring decay heat from the reactor core to other internal structures of the reactor system. The amount of heat transfer and delay in core degradation depends on the geometry and internal structures of the system and on the events of an accident.

Domanus, H.M.; Schmitt, R.C.; Sha, W.T.; Shah, V.L.; Han, J.T.

1987-01-01T23:59:59.000Z

449

Numerical study of convection heat transfer during the melting of ice in a porous layer  

SciTech Connect (OSTI)

A numerical study is made of the melting of ice in a rectangular porous cavity heated from above. The Landau transformation is used to immobilize the ice-water interface, and the Darcy-Boussinesq equations are solved by a finite-difference technique. Results are analyzed in terms of the heating temperature and the aspect ratio of the cavity. A comparison is made with the case of melting from below. It was found that melting from above is more effective than melting from below when the heating temperature is between 0 and 8 C: convection arises earlier, the melting process is faster, and the total melt at steady state is thicker. The critical time for onset of convection is minimum when the upper boundary is heated at 6 C. At this heating temperature, one also obtains a maximum heat transfer rate (Nusselt number).

Zhang, X.; Nguyen, T.H. (Ecole Polytechnique de Montreal, Quebec (Canada). Dept. of Mechanical Engineering)

1994-05-01T23:59:59.000Z

450

Numerical investigation of transient flow-mode transition of laminar natural convection in an inclined enclosure  

SciTech Connect (OSTI)

The present work is concerned with a numerical investigation of transient laminar natural convection and the associated flow-mode transition in a two-dimensional rectangular enclosure. Navier-Stokes/Boussinesq equations for fluid flow and energy balance are solved by using the SIMPLE-C algorithm. Air of Pr = 0.71 in a differentially heated enclose of length-to-height aspect ratio As = 4 and at Ra = 5,000 is chosen as the flow model to examine the influences of the inclination. Calculations of time accuracy are performed to investigate the transient procedure of the flow-mode transition with increasing or decreasing inclination. The present results reveal that, at some critical situations, natural convection in inclined enclosures is very sensitive to the change in tilt angle, and the associated heat transfer rates are closely related to the correspondent cellular flow patterns.

Tzeng, P.Y.; Soong, C.Y.; Sheu, T.S. [Chung Cheng Inst. of Tech., Taoyuan (Taiwan, Province of China). Dept. of Aeronautical Engineering

1997-02-07T23:59:59.000Z

451

Large plasma pressure perturbations and radial convective transport in a tokamak  

SciTech Connect (OSTI)

Strongly localized plasma structures with large pressure inhomogeneities (such as plasma blobs in the scrape-off-layer (SOL)/shadow regions, pellet clouds, ELMs) observed in the tokamaks, stellarators and linear plasma devices. Experimental studies of these phenomena reveal striking similarities including more convective rather than diffusive radial plasma transport. We suggest that rather simple models can describe many essentials of blobs, ELMs, and pellet clouds dynamics. The main ingredient of these models is the effective plasma gravity caused by magnetic curvature, centrifugal or friction forces effects. As a result, the equations governing plasma transport in such localized structures appear to be rather similar to that used to describe nonlinear evolution of thermal convection in the Boussinesq approximation (directly related to the Rayleigh-Taylor instability).

Krasheninnikov, S; Ryutov, D; Yu, G

2004-02-04T23:59:59.000Z

452

A lattice-Boltzmann relaxation scheme for coupled convection-radiation systems  

SciTech Connect (OSTI)

The convection-radiation effects in thermal fluid flows are studied based on the lattice-Boltzmann method. Nine-velocity flow and temperature distributions are used to obtain the mass, momentum and energy equations in thermal incompressible flows by studying equivalent moment systems. The radiative heat flux in the energy equation is obtained using the discrete-ordinates solution of the radiative transfer equation. A non-oscillatory relaxation scheme is used to solve the coupled moment equations. Such schemes have the advantage of being simple and easy to implement. Numerical results are presented for two test examples on coupled convection-radiation flows in two dimensional enclosures. Detailed simulation results at different flow and radiative regimes, as well as benchmark solutions, are presented and discussed.

Banda, Mapundi K. [School of Mathematical Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209 Pietermaritzburg (South Africa)], E-mail: bandamk@ukzn.ac.za; Klar, Axel [AG Technomathematik, Fachbereich Mathematik, Technische Universitaet Kaiserslautern, 67663 Kaiserslautern (Germany)], E-mail: klar@itwm.fhg.de; Seaid, Mohammed [AG Technomathematik, Fachbereich Mathematik, Technische Universitaet Kaiserslautern, 67663 Kaiserslautern (Germany)], E-mail: seaid@mathematik.uni-kl.de

2007-10-01T23:59:59.000Z

453

A Theory of Non-Local Mixing Length Convection. III. Comparing Theory and Numerical Experiment  

E-Print Network [OSTI]

We solve the nonlocal convection equations. The solutions for four model problems are compared with results of GSPH simulations. In each case we test two closure schemes: 1) where third moments are defined by the diffusion approximation; and 2) where the full third moment equations are used and fourth moments are defined by a modified form of the quasi-normal approximation. In overshooting models, the convective flux becomes negative shortly after the stability boundary. The negative amplitude remains small, and the temperature gradient in the overshooting zone has nearly the radiative value. Turbulent velocities decay by a factor of $e$ after $0.5$--$1.5\\ell$, depending on the model, where $\\ell$ is the mixing length. Turbulent viscosity is more important than negative buoyancy in decelerating overshooting fluid blobs. These predictions are consistent with helioseismology.

Scott Grossman

1995-09-08T23:59:59.000Z

454

Thermodynamic fluctuations in solar photospheric three-dimensional convection simulations and observations  

E-Print Network [OSTI]

Numerical 3D radiative (M)HD simulations of solar convection are used to understand the physical properties of the solar photosphere. To validate this approach, it is important to check that no excessive thermodynamic fluctuations arise as a consequence of the partially incomplete treatment of radiative transfer. We investigate the realism of 3D convection simulations carried out with the Stagger code. We compared the characteristic properties of several spectral lines in solar disc centre observations with spectra synthesized from the simulations. We degraded the synthetic spectra to the spatial resolution of the observations using the continuum intensity distribution. We estimated the necessary spectral degradation by comparing atlas spectra with averaged observed spectra. In addition to deriving a set of line parameters directly, we used the SIR code to invert the spectra. Most of the line parameters from the observational data are matched well by the degraded simulation spectra. The inversions predict a m...

Beck, C; Moreno-Insertis, F; Puschmann, K G; Rezaei, R

2013-01-01T23:59:59.000Z

455

Numerical investigation of the convection of heat-emitting liquid reactor materials taking stratification into account  

SciTech Connect (OSTI)

Convective heat transfer to a reactor vessel following core destruction is analyzed. Fuel fragment and structural materials are assumed to melt either mix uniformly or stratify. The Navier-Stokes equations were solved numerically with a rectangular coarse difference grid, neglecting the negligibly small contribution of the laminar boundary layer. Calculations for different levels of volume heat release showed that integral heat fluxes at the lateral and top surfaces of the melt are virtually independent of the convective flow scenario. However, the maximum heat flux on the lateral surface is approximately 1.5 times higher for the homogeneous case than for the stratified case. The higher heat flux could result in larger mechanical loads on the reactor vessel, requiring more cooling of the reactor vessel outer surface. 12 refs., 4 figs.

Likhanskii, V.V.; Loboiko, A.I.; Khoruzhii, O.V.

1994-11-01T23:59:59.000Z

456

A Statistical Analysis of Characteristics of Mesoscale Convective System Mountain Initiation Location Clusters in the Arkansas-Red River Basin  

E-Print Network [OSTI]

A Statistical Analysis of Characteristics of Mesoscale Convective System Mountain Initiation Location Clusters in the Arkansas-Red River Basin By Elisabeth F. Callen Submitted to the graduate degree program in Geography and the Graduate... ____________________________________ David Mechem Date Defended: November 9, 2012 ii The Thesis Committee for Elisabeth F. Callen certifies that this is the approved version of the following thesis: A Statistical Analysis of Characteristics of Mesoscale Convective...

Callen, Elisabeth F.

2012-12-31T23:59:59.000Z

457

Design, construction and testing of a boiling and convective condensation experiment for use in a microgravity environment  

E-Print Network [OSTI]

DESIGN, CONSTRUCTION AND TESTING OF A SOILING AND CONVECTIVE CONDENSATION EXPERIMENT FOR USE IN A MICROGRAVITY ENVIRONMENT A Thesis by LEO JOSEPH KACHNIK Submitted to the Graduate College of Texas ASM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 1987 Major Subject: Nuclear Engineering DESIGN, CONSTRUCTION AND TESTING OF A BOILING AND CONVECTIVE CONDENSATION EXPERIMENT FOR USE IN A MICROGRAVITY ENVIRONMENT A Thesis by LEO JOSEPH KACHNIK...

Kachnik, Leo Joseph

2012-06-07T23:59:59.000Z

458

Mixed Convection in the VHTR in the Event of a LOFA  

SciTech Connect (OSTI)

The US Department of Energy, Office of Nuclear Energy (DOE-NE) is supporting the development of a very high temperature reactor (VHTR) concept as the primary focus of it next generation nuclear power plant (NGNP) program. The VHTR is cooled by forcing helium downwards through the core into the lower plenum and out the hot duct. In the event that the coolant circulators are lost, the driving pressure drop across the core will reduce to zero and there will be the opportunity for natural circulation to occur. During the time that the circulators are powering down, the heat transfer in the core from the graphite blocks to the helium coolant will transform from turbulent forced convection to mixed convection, where buoyancy effects become important, to free or natural convection, where buoyancy is dominant. Analysis of the nature of the forced, mixed and free convection is best done using computational fluid dynamic (CFD) software that can provide fine details of the flow and heat transfer. However, CFD analysis involves approximations in the results because of the finite nature of the spatial and temporal discretizations required, the inexact nature of the turbulence models that are used and the finite precision of the computers employed. Therefore, it is necessary to validate the CFD computations. Validation is accomplished by comparing results from specific CFD computations to experimental data that have been taken specifically for the purpose of validation and that are related to the physical phenomena in question. The present report examines the flow and heat transfer parameters (dimensionless numbers) that characterize the flow and reports ranges for their values based on specific CFD studies performed for the VHTR.

Richard W. Johnson

2012-05-01T23:59:59.000Z

459

Impacts of Microphysical Scheme on Convective and Stratiform Characteristics in Two High Precipitation Squall Line Events  

SciTech Connect (OSTI)

This study investigates the impact of snow, graupel, and hail processes on the simulated squall lines over the Southern Great Plains in the United States. Weather Research and Forecasting (WRF) model is used to simulate two squall line events in May 2007, and the results are validated against radar and surface observations in Oklahoma. Several microphysics schemes are tested in this study, including WRF 5-Class Microphysics Scheme (WSM5), WRF 6-Class Microphysics Scheme (WSM6), Goddard Three Ice scheme (Goddard 3-ice) with graupel, Goddard Two Ice scheme (Goddard 2-ice), and Goddard 3-ice hail scheme. The simulated surface precipitation is sensitive to the microphysics scheme, and especially to whether graupel or hail category is included. All of the three ice (3-ice) schemes overestimated the total precipitation, within which WSM6 has the highest overestimation. Two ice (2-ice) schemes, missing a graupel/hail category, produced less total precipitation than 3-ice schemes. By applying a radar-based convective/stratiform partitioning algorithm, we find that by including the graupel/hail processes, there is an increase in areal coverage, precipitation intensity, updraft and downdraft intensity in convective region and a reduction of areal coverage and its precipitation intensity in stratiform region. For vertical structures, all the bulk schemes, especially 2-ice schemes, have the highest reflectivity located at upper levels (~8 km), which is unrealistic compared to observations. In addition, this study shows the radar-based convective/stratiform partitioning algorithm can reasonably identify WRF simulated precipitation, wind and microphysics fields in both convective and stratiform regions.

Wu, Di; Dong, Xiquan; Xi, Baike; Feng, Zhe; Kennedy, Aaron; Mullendore, Gretchen; Gilmore, Matthew; Tao, Wei-Kuo

2013-10-04T23:59:59.000Z

460

Extinction of a bacterial colony under forced convection in pie geometry  

Science Journals Connector (OSTI)

The extinction of a bacterial colony, as it is forced to migrate into a hostile environment, is analyzed in pie geometry. Under convection, separation of the radial and the azimuthal degrees of freedom is not possible, so the linearized evolution operator is diagonalized numerically. Some characteristic scales are compared with the results of recent experiments, and the “integrable” limit of the theory in the narrow growth region is studied.

Nadav M. Shnerb

2000-12-21T23:59:59.000Z

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


461

Antisymmetric polar modes of thermal convection in rotating fluid spherical shells at high Taylor numbers  

E-Print Network [OSTI]

of the liquid sodium ( = 0.01). For the first time, it is shown that at very high Taylor numbers the first numbers: 47.15.-x, 47.20.-k Electronic address: sanchez@fa.upc.edu Electronic address: marta@fa.upc by the properties of convection. The large-scale zonal winds observed in the surface of Jupiter at mid- and low

Sánchez, Juan

462

Method and Appartus for Calibrating a Linear Variable Differential Transformer  

SciTech Connect (OSTI)

A calibration apparatus for calibrating a linear variable differential transformer (LVDT) having an armature positioned in au LVDT armature orifice, and the armature able to move along an axis of movement. The calibration apparatus includes a heating mechanism with an internal chamber, a temperature measuring mechanism for measuring the temperature of the LVDT, a fixture mechanism with an internal chamber for at least partially accepting the LVDT and for securing the LVDT within the heating mechanism internal chamber, a moving mechanism for moving the armature, a position measurement mechanism for measuring the position of the armature, and an output voltage measurement mechanism. A method for calibrating an LVDT, including the steps of powering the LVDT; heating the LVDT to a desired temperature; measuring the position of the armature with respect to the armature orifice; and measuring the output voltage of the LVDT.

Pokrywka, Robert J.

2005-01-18T23:59:59.000Z

463

Method and apparatus for calibrating a linear variable differential transformer  

DOE Patents [OSTI]

A calibration apparatus for calibrating a linear variable differential transformer (LVDT) having an armature positioned in au LVDT armature orifice, and the armature able to move along an axis of movement. The calibration apparatus includes a heating mechanism with an internal chamber, a temperature measuring mechanism for measuring the temperature of the LVDT, a fixture mechanism with an internal chamber for at least partially accepting the LVDT and for securing the LVDT within the heating mechanism internal chamber, a moving mechanism for moving the armature, a position measurement mechanism for measuring the position of the armature, and an output voltage measurement mechanism. A method for calibrating an LVDT, including the steps of: powering the LVDT; heating the LVDT to a desired temperature; measuring the position of the armature with respect to the armature orifice; and measuring the output voltage of the LVDT.

Pokrywka, Robert J. (North Huntingdon, PA)

2005-01-18T23:59:59.000Z

464

Massive Variability Surveys from Venezuela  

E-Print Network [OSTI]

At the Venezuela National Astronomical Observatory we are carrying out variability surveys spanning many hundreds of square degrees near the celestial equator, using an 8k x 8k CCD Mosaic Camera optimized for drift-scanning on a 1m Schmidt telescope. Among the initial efforts was a project to obtain the first moderately deep, homogeneous sample of young stars over an area of ~180sqr.deg. encompassing the entire Orion OB1 association, one of the nearest and most active regions of star formation. The results show that variability is a powerful technique to identify pre-main sequence populations, specially in sparse areas devoid of gas and dust. We are currently developing a massive database, equipped with web-based data mining tools, that will make our data and results available to the astronomical community.

Cesar Briceno

2003-04-03T23:59:59.000Z

465

Chapter Seven - Variable speed drives  

Science Journals Connector (OSTI)

Publisher Summary The electromechanical controllers are a kind of variable speed drives (VSDs) that are obsolete but are still in use because when a motor and a drive is combined, they become a power drive system (PDS). There are two ways of varying the speed of an induction motor, either by varying the motor slip or by varying the supply frequency. The preferred practice for electrical speed variation is to change the supply frequency with a variable frequency drive (VFD). Many other designs also have been developed. However, except the specialized applications, few are still in operation. A number of motor and drive manufacturers are now producing the integrated motor/VFD units. These units consist of a motor and a specially designed VFD, produced as a single package, with the VFD unit mounted variously on the top, side, or end of the motor.

Europump; Hydraulic Institute

2005-01-01T23:59:59.000Z

466

Simulation of Rayleigh-Benard convection using a lattice Boltzmann method  

SciTech Connect (OSTI)

Rayleigh-Benard convection is numerically simulated in two and three dimensions using a recently developed two-component lattice Boltzmann equation (LBE) method. The density field of the second component, which evolves according to the advection-diffusion equation of a passive scalar, is used to simulate the temperature field. A body force proportional to the temperature is applied, and the system satisfies the Boussinesq equation except for a slight compressibility. A no-slip, isothermal boundary condition is imposed in the vertical direction, and periodic boundary conditions are used in horizontal directions. The critical Rayleigh number for the onset of the Rayleigh-Benard convection agrees with the theoretical prediction. As the Rayleigh number is increased higher, the steady two-dimensional convection rolls become unstable. The wavy instability and aperiodic motion observed, as well as the Nusselt number as a function of the Rayleigh number, are in good agreement with experimental observations and theoretical predictions. The LBE model is found to be efficient, accurate, and numerically stable for the simulation of fluid flows with heat and mass transfer. {copyright} {ital 1997} {ital The American Physical Society}

Shan, X. [U.S. Air Force Phillips Laboratory, Hanscom Air Force Base, Massachusetts 01731 (United States)] [U.S. Air Force Phillips Laboratory, Hanscom Air Force Base, Massachusetts 01731 (United States); [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1997-03-01T23:59:59.000Z

467

Chaotic mean wind in turbulent thermal convection and long-term correlations in solar activity  

E-Print Network [OSTI]

It is shown that correlation function of the mean wind velocity in a turbulent thermal convection (Rayleigh number $Ra \\sim 10^{11}$) exhibits exponential decay with a very long correlation time, while corresponding largest Lyapunov exponent is certainly positive. These results together with the reconstructed phase portrait indicate presence of a chaotic component in the examined mean wind. Telegraph approximation is also used to study relative contribution of the chaotic and stochastic components to the mean wind fluctuations and an equilibrium between these components has been studied. Since solar activity is based on the thermal convection processes, it is reasoned that the observed solar activity long-term correlations can be an imprint of the mean wind chaotic properties. In particular, correlation function of the daily sunspots number exhibits exponential decay with a very long correlation time and corresponding largest Lyapunov exponent is certainly positive, also relative contribution of the chaotic and stochastic components follows the same pattern as for the convection mean wind.

A. Bershadskii

2009-08-27T23:59:59.000Z

468

Review of Probability Random Variable  

E-Print Network [OSTI]

at close 4) Height of wheel going over a rocky road #12;3 Random Variable Non-examples 1) `Heads' or `Tails' on coin 2) Red or Black ball from urn But we can make these into RV's Basic Idea ­ don't know · Temperature · Wheel height #12;5 Given Continuous RV X... What is the probability that X = x0 ? Oddity : P

Fowler, Mark

469

Improvements of the Variable Thermal Resistance  

E-Print Network [OSTI]

A flat mounting unit with electronically variable thermal resistance [1] has been presented in the last year [2]. The design was based on a Peltier cell and the appropriate control electronics and software. The device is devoted especially to the thermal characterization of packages, e.g. in dual cold plate arrangements. Although this design meets the requirements of the static measurement we are intended to improve its parameters as the settling time and dynamic thermal impedance and the range of realized thermal resistance. The new design applies the heat flux sensor developed by our team as well [3], making easier the control of the device. This development allows even the realization of negative thermal resistances.

V. Szekely; S. Torok; E. Kollar

2008-01-07T23:59:59.000Z

470

Statistics of Storm Updraft Velocities from TWP-ICE Including Verification with Profiling Measurements  

E-Print Network [OSTI]

. The vertical component of storm dynamics has a large impact on the life cycle of convective systems. While use, in which measurements from a dual-frequency radar profiler system and volumetric radar-based wind the profiling system. This prompted a statistical analysis of an extended period of an active monsoon period

Protat, Alain

471

MAGNETIC CYCLES IN A CONVECTIVE DYNAMO SIMULATION OF A YOUNG SOLAR-TYPE STAR  

SciTech Connect (OSTI)

Young solar-type stars rotate rapidly and many are magnetically active. Some appear to undergo magnetic cycles similar to the 22 yr solar activity cycle. We conduct simulations of dynamo action in rapidly rotating suns with the three-dimensional magnetohydrodynamic anelastic spherical harmonic (ASH) code to explore dynamo action achieved in the convective envelope of a solar-type star rotating at five times the current solar rotation rate. We find that dynamo action builds substantial organized global-scale magnetic fields in the midst of the convection zone. Striking magnetic wreaths span the convection zone and coexist with the turbulent convection. A surprising feature of this wreath-building dynamo is its rich time dependence. The dynamo exhibits cyclic activity and undergoes quasi-periodic polarity reversals where both the global-scale poloidal and toroidal fields change in sense on a roughly 1500 day timescale. These magnetic activity patterns emerge spontaneously from the turbulent flow and are more organized temporally and spatially than those realized in our previous simulations of the solar dynamo. We assess in detail the competing processes of magnetic field creation and destruction within our simulations that contribute to the global-scale reversals. We find that the mean toroidal fields are built primarily through an {Omega}-effect, while the mean poloidal fields are built by turbulent correlations which are not well represented by a simple {alpha}-effect. During a reversal the magnetic wreaths propagate toward the polar regions, and this appears to arise from a poleward propagating dynamo wave. As the magnetic fields wax and wane in strength and flip in polarity, the primary response in the convective flows involves the axisymmetric differential rotation which varies on similar timescales. Bands of relatively fast and slow fluid propagate toward the poles on timescales of roughly 500 days and are associated with the magnetic structures that propagate in the same fashion. In the Sun, similar patterns are observed in the poleward branch of the torsional oscillations, and these may represent poleward propagating magnetic fields deep below the solar surface.

Brown, Benjamin P. [Department of Astronomy, University of Wisconsin, Madison, WI 53706-1582 (United States); Miesch, Mark S. [High Altitude Observatory, NCAR, Boulder, CO 80307-3000 (United States); Browning, Matthew K. [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S3H8 (Canada); Brun, Allan Sacha [Laboratoire AIM Paris-Saclay, CEA/Irfu Universite Paris-Diderot CNRS/INSU, 91191 Gif-sur-Yvette Cedex (France); Toomre, Juri, E-mail: bpbrown@astro.wisc.edu [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309-0440 (United States)

2011-04-10T23:59:59.000Z

472

Method and system to estimate variables in an integrated gasification combined cycle (IGCC) plant  

DOE Patents [OSTI]

System and method to estimate variables in an integrated gasification combined cycle (IGCC) plant are provided. The system includes a sensor suite to measure respective plant input and output variables. An extended Kalman filter (EKF) receives sensed plant input variables and includes a dynamic model to generate a plurality of plant state estimates and a covariance matrix for the state estimates. A preemptive-constraining processor is configured to preemptively constrain the state estimates and covariance matrix to be free of constraint violations. A measurement-correction processor may be configured to correct constrained state estimates and a constrained covariance matrix based on processing of sensed plant output variables. The measurement-correction processor is coupled to update the dynamic model with corrected state estimates and a corrected covariance matrix. The updated dynamic model may be configured to estimate values for at least one plant variable not originally sensed by the sensor suite.

Kumar, Aditya; Shi, Ruijie; Dokucu, Mustafa

2013-09-17T23:59:59.000Z

473

Variability in the Southerly Flow into the Eastern Pacific ITCZ* SIMON P. DE SZOEKE  

E-Print Network [OSTI]

and latent heat release in deep convective towers form the vigor- ous upward branch of the Hadley circulation, which transmits surface solar heating throughout the tropo- sphere. The distribution of deep convection

Bretherton, Chris

474

Experimental and CFD Analysis of Advanced Convective Cooling Systems  

SciTech Connect (OSTI)

The objective of this project is to study the fundamental physical phenomena in the reactor cavity cooling system (RCCS) of very high-temperature reactors (VHTRs). One of the primary design objectives is to assure that RCCS acts as an ultimate heat sink capable of maintaining thermal integrity of the fuel, vessel, and equipment within the reactor cavity for the entire spectrum of postulated accident scenarios. Since construction of full-scale experimental test facilities to study these phenomena is impractical, it is logical to expect that computational fluid dynamics (CFD) simulations will play a key role in the RCCS design process. An important question then arises: To what extent are conventional CFD codes able to accurately capture the most important flow phenomena, and how can they be modified to improve their quantitative predictions? Researchers are working to tackle this problem in two ways. First, in the experimental phase, the research team plans to design and construct an innovative platform that will provide a standard test setting for validating CFD codes proposed for the RCCS design. This capability will significantly advance the state of knowledge in both liquid-cooled and gas-cooled (e.g., sodium fast reactor) reactor technology. This work will also extend flow measurements to micro-scale levels not obtainable in large-scale test facilities, thereby revealing previously undetectable phenomena that will complement the existing infrastructure. Second, in the computational phase of this work, numerical simulation of the flow and temperature profiles will be performed using advanced turbulence models to simulate the complex conditions of flows in critical zones of the cavity. These models will be validated and verified so that they can be implemented into commercially available CFD codes. Ultimately, the results of these validation studies can then be used to enable a more accurate design and safety evaluation of systems in actual nuclear power applications (both during normal operation and accident scenarios).

Yassin A. Hassan; Victor M. Ugaz

2012-06-27T23:59:59.000Z

475

Variable pressure operation: An assessment  

SciTech Connect (OSTI)

This report summarizes the benefits, drawbacks, and technical issues of variable pressure operation (VPO) retrofit. Under VPO, turbine throttle pressure is reduced at low loads. This operating mode offers several significant advantages for units that cycle or operate at low loads for extended periods. Information used in the report was assembled from published sources, from major equipment manufacturers, and from utilities operating units under VPO in the US, Europe and Japan. The report also contains statistics of VPO use in this country and abroad. Design features of new units using VPO in Europe and Japan are presented to identify potential directions for future US designs incorporating VPO.

Kimel, E.; Kemeny, P.; Bierman, E.; Lagomarsino, J.; Clarke, D. (Burns and Roe, Inc., Oradell, NJ (USA))

1990-03-01T23:59:59.000Z

476

The Plant–Craig Stochastic Convection Scheme in ICON and Its Scale Adaptivity  

Science Journals Connector (OSTI)

The emergence of numerical weather prediction and climate models with multiple or variable resolutions requires that their parameterizations adapt correctly, with consistent increases in variability as resolution increases. In this study, the ...

Richard J. Keane; George C. Craig; Christian Keil; Günther Zängl

2014-09-01T23:59:59.000Z

477

A group bridge approach for variable selection  

Science Journals Connector (OSTI)

......group bridge approach for variable...Actuarial Science, University...Department of Management Science, University...group bridge approach that is capable...group bridge approach for variable...Actuarial Science, University...Department of Management Science......

Jian Huang; Shuange Ma; Huiliang Xie; Cun-Hui Zhang

2009-06-01T23:59:59.000Z

478

Development of procedure for and results from calculated study of thermal state of turbine first-stage nozzle vanes and efficiency of their convective-film air cooling  

Science Journals Connector (OSTI)

Information on the development of a comprehensive procedure for calculating a nozzle vane with convective-film cooling and on its hydraulic, thermal, and strength characteristics is presented.

K. D. Andreev; A. V. Lipin; V. G. Polishchuk; N. P. Sokolov

2009-07-01T23:59:59.000Z

479

Mon. Not. R. Astron. Soc. 000, 000000 (0000) Printed 31 July 2012 (MN LATEX style file v2.2) Data assimilation for stratified convection  

E-Print Network [OSTI]

assimilation for stratified convection Andreas Svedin1 , Milena C. Cu´ellar2 and Axel Brandenburg3,4 1Astronomy

Brandenburg, Axel

480

Variable Average Absolute Percent Differences  

U.S. Energy Information Administration (EIA) Indexed Site

Variable Variable Average Absolute Percent Differences Percent of Projections Over- Estimated Gross Domestic Product Real Gross Domestic Product (Average Cumulative Growth)* (Table 2) 1.0 42.6 Petroleum Imported Refiner Acquisition Cost of Crude Oil (Constant $) (Table 3a) 35.2 18.6 Imported Refiner Acquisition Cost of Crude Oil (Nominal $) (Table 3b) 34.7 19.7 Total Petroleum Consumption (Table 4) 6.2 66.5 Crude Oil Production (Table 5) 6.0 59.6 Petroleum Net Imports (Table 6) 13.3 67.0 Natural Gas Natural Gas Wellhead Prices (Constant $) (Table 7a) 30.7 26.1 Natural Gas Wellhead Prices (Nominal $) (Table 7b) 30.0 27.1 Total Natural Gas Consumption (Table 8) 7.8 70.2 Natural Gas Production (Table 9) 7.1 66.0 Natural Gas Net Imports (Table 10) 29.3 69.7 Coal Coal Prices to Electric Generating Plants (Constant $)** (Table 11a)

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


481

Strategies for Mitigating the Reduction in Economic Value of Variable Generation with Increasing Penetration Levels  

SciTech Connect (OSTI)

In this report, we evaluate individual options that have the potential to stem the decline in the marginal value of variable generation (VG) with increasing penetration levels. We focus only on the effectiveness of mitigation measures for wind and PV.

Mills, Andrew; Wiser, Ryan

2014-03-03T23:59:59.000Z

482

Variability of Load and Net Load in Case of Large Scale Distributed Wind Power  

SciTech Connect (OSTI)

Large scale wind power production and its variability is one of the major inputs to wind integration studies. This paper analyses measured data from large scale wind power production. Comparisons of variability are made across several variables: time scale (10-60 minute ramp rates), number of wind farms, and simulated vs. modeled data. Ramp rates for Wind power production, Load (total system load) and Net load (load minus wind power production) demonstrate how wind power increases the net load variability. Wind power will also change the timing of daily ramps.

Holttinen, H.; Kiviluoma, J.; Estanqueiro, A.; Gomez-Lazaro, E.; Rawn, B.; Dobschinski, J.; Meibom, P.; Lannoye, E.; Aigner, T.; Wan, Y. H.; Milligan, M.

2011-01-01T23:59:59.000Z

483

TURBULENT MIXING AND LAYER FORMATION IN DOUBLE-DIFFUSIVE CONVECTION: THREE-DIMENSIONAL NUMERICAL SIMULATIONS AND THEORY  

SciTech Connect (OSTI)

Double-diffusive convection, often referred to as semi-convection in astrophysics, occurs in thermally and compositionally stratified systems which are stable according to the Ledoux criterion but unstable according to the Schwarzschild criterion. This process has been given relatively little attention so far, and its properties remain poorly constrained. In this paper, we present and analyze a set of three-dimensional simulations of this phenomenon in a Cartesian domain under the Boussinesq approximation. We find that in some cases the double-diffusive convection saturates into a state of homogeneous turbulence, but with turbulent fluxes several orders of magnitude smaller than those expected from direct overturning convection. In other cases, the system rapidly and spontaneously develops closely packed thermo-compositional layers, which later successively merge until a single layer is left. We compare the output of our simulations with an existing theory of layer formation in the oceanographic context and find very good agreement between the model and our results. The thermal and compositional mixing rates increase significantly during layer formation and increase even further with each merger. We find that the heat flux through the staircase is a simple function of the layer height. We conclude by proposing a new approach to studying transport by double-diffusive convection in astrophysics.

Rosenblum, E. [Department of Physics, Stony Brook University, Stony Brook, New York, NY 11794 (United States); Garaud, P.; Traxler, A. [Department of Applied Mathematics and Statistics, Baskin School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Stellmach, S. [Institut fuer Geophysik, Westfaelische Wilhelms-Universitaet Muenster, Muenster D-48149 (Germany)

2011-04-10T23:59:59.000Z

484

Utilizing CLASIC observations and multiscale models to study the impact of improved Land surface representation on modeling cloud- convection  

SciTech Connect (OSTI)

The CLASIC experiment was conducted over the US southern great plains (SGP) in June 2007 with an objective to lead an enhanced understanding of the cumulus convection particularly as it relates to land surface conditions. This project was design to help assist with understanding the overall improvement of land atmosphere convection initiation representation of which is important for global and regional models. The study helped address one of the critical documented deficiency in the models central to the ARM objectives for cumulus convection initiation and particularly under summer time conditions. This project was guided by the scientific question building on the CLASIC theme questions: What is the effect of improved land surface representation on the ability of coupled models to simulate cumulus and convection initiation? The focus was on the US Southern Great Plains region. Since the CLASIC period was anomalously wet the strategy has been to use other periods and domains to develop the comparative assessment for the CLASIC data period, and to understand the mechanisms of the anomalous wet conditions on the tropical systems and convection over land. The data periods include the IHOP 2002 field experiment that was over roughly same domain as the CLASIC in the SGP, and some of the DOE funded Ameriflux datasets.

Niyogi, Devdutta S. [Purdue

2013-06-07T23:59:59.000Z

485

Natural Convection Heat Transfer in a Rectangular Liquid Metal Pool With Bottom Heating and Top Cooling  

SciTech Connect (OSTI)

An experimental study is performed to investigate the natural convection heat transfer characteristics with subcooled coolant to create engineering database for basic applications in a lead alloy cooled reactor. Tests are performed in the ALTOS (Applied Liquid-metal Thermal Operation Study) apparatus as part of MITHOS (Metal Integrated Thermo Hydrodynamic Operation System). A relationship is determined between the Nusselt number Nu and the Rayleigh number Ra in the liquid metal rectangular pool. Results are compared with correlations and experimental data in the literature. Given the similar Ra condition, the present test results for Nu of the liquid metal pool with top subcooling are found to be similar to those predicted by the existing correlations or experiments. The current test results are utilized to develop natural convection heat transfer correlations applicable to low Prandtl number Pr fluids that are heated from below and cooled by the external coolant above. Results from this study are slated to be used in designing BORIS (Battery Optimized Reactor Integral System), a small lead cooled modular fast reactor for deployment at remote sites cycled with MOBIS (Modular Optimized Brayton Integral System) for electricity generation, tied with NAVIS (Naval Application Vessel Integral System) for ship propulsion, joined with THAIS (Thermochemical Hydrogen Acquisition Integral System) for hydrogen production, and coupled with DORIS (Desalination Optimized Reactor Integral System) for seawater desalination. Tests are performed with Wood's metal (Pb-Bi-Sn-Cd) filling a rectangular pool whose lower surface is heated and upper surface cooled by forced convection of water. The test section is 20 cm long, 11.3 cm high and 15 cm wide. The simulant has a melting temperature of 78 deg. C. The constant temperature and heat flux condition was realized for the bottom heating once the steady state had been met. The test parameters include the heated bottom surface temperature of the liquid metal pool, the input power to the bottom surface of the section, and the coolant temperature. (authors)

Lee, Il S.; Yu, Yong H.; Son, Hyoung M.; Hwang, Jin S.; Suh, Kune Y. [Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul, 151-742 (Korea, Republic of)

2006-07-01T23:59:59.000Z

486

Finite element analysis of laminar mixed convection in the entrance region of horizontal annular ducts  

SciTech Connect (OSTI)

The laminar mixed convection in the entrance region of horizontal straight ducts of an annular cross section is studied by means of a generally applicable finite element procedure based on the parabolized simplification of the Navier-Stokes and energy equations and on the Boussinesq approximation of the buoyancy term. The procedure is validated through comparisons of computed results with available data from the literature. New results concern annuli with radius ratios equal to 0.25, 0.5, and 0.75 subjected to the fundamental boundary condition of the second and the third kinds, for Prandtl numbers equal to 0.7 and 7, and different values of Grashof number.

Nonino, C.; Giudice, S. del [Univ. di Udine (Italy). Dipt. di Energetica e Macchine

1996-02-23T23:59:59.000Z

487

Effect of modulation on the onset of convection in a sparsely packed porous layer  

SciTech Connect (OSTI)

The stability of a Boussinesq fluid-saturated horizontal porous layer heated from below is examined when the applied temperature gradient is the sum of a steady component and a time-dependent sinusoidal component. The Brinkman model is employed and only infinitesimal disturbances are considered. A perturbation solution as a function of the applied field is obtained. The critical Rayleigh number is obtained for several cases depending on the frequency of oscillations and it is found that it is possible to advance or delay the onset of convection by thermal modulation of the wall temperature. The Darcy limit and viscous flow limit are obtained as degenerate cases.

Rudraiah, N.; Malashetty, M.S. (Bangalore Univ. (India))

1990-08-01T23:59:59.000Z

488

CGL Defect Chaos and Bursts in Hexagonal Rotating non-Boussinesq Convection  

E-Print Network [OSTI]

We employ numerical computations of the full Navier-Stokes equations to investigate non-Boussinesq convection in a rotating system using water as a working fluid. We identify two regimes. For weak non-Boussinesq effects the Hopf bifurcation from steady to oscillating (whirling) hexagons is supercritical and typical states exhibit defect chaos that is systematically described by the cubic complex Ginzburg-Landau equation. For stronger non-Boussinesq effects the Hopf bifurcation becomes subcritical and the oscillations exhibit localized chaotic bursting, which can be modeled by a quintic complex Ginzburg-Landau equation.

Santiago Madruga; Hermann Riecke; Werner Pesch

2005-07-26T23:59:59.000Z

489

Unsteady mixed convection in horizontal ducts with applications to chemical vapor deposition processes  

SciTech Connect (OSTI)

Mixed convection in a horizontal rectangular duct of aspect ratio 4 heated from below with cold side walls was studied numerically for a non-Boussinesq fluid. Results are presented for a reduced temperature of 2.33 and a Rayleigh number of 130,700. The resulting flow field at Re = 25 consisted of four steady longitudinal vortices, symmetric about the duct centerline, with a leading transverse roll cell. A reduction to Re = 10 resulted in the introduction of traveling transverse waves. A further reduction Re = 5 resulted in a loss of symmetry about the duct centerline plane. Further work is underway to verify the Re = 5 results.

Spall, R.E. [Univ. of South Alabama, Mobile, AL (United States). Dept. of Mechanical Engineering] [Univ. of South Alabama, Mobile, AL (United States). Dept. of Mechanical Engineering

1996-01-01T23:59:59.000Z

490

Effect of wind speed on the growth of the upper convective zone in a solar pond  

E-Print Network [OSTI]

[2]. The distance which the wind has to act on the surface of a pond is commonly called fetch, or fetch length. The purpose of the nets or other devices used in wind suppression is to reduce the fetch and transmit some of the energy in the waves... to the sides of the pond. Wind mixing of the upper convective zone can be thought of as converting some of the kinetic energy in the wind to potential energy in the fluid by a process called entrainment. Entrainment is defined in detail in Chapter V...

McMinn, Steven Lee

2012-06-07T23:59:59.000Z

491

Liquid Salts as Media for Process Heat Transfer from VHTR's: Forced Convective Channel Flow Thermal Hydraulics, Materials, and Coating  

SciTech Connect (OSTI)

The goal of this NERI project was to perform research on high temperature fluoride and chloride molten salts towards the long-term goal of using these salts for transferring process heat from high temperature nuclear reactor to operation of hydrogen production and chemical plants. Specifically, the research focuses on corrosion of materials in molten salts, which continues to be one of the most significant challenges in molten salts systems. Based on the earlier work performed at ORNL on salt properties for heat transfer applications, a eutectic fluoride salt FLiNaK (46.5% LiF-11.5%NaF-42.0%KF, mol.%) and a eutectic chloride salt (32%MgCl2-68%KCl, mole %) were selected for this study. Several high temperature candidate Fe-Ni-Cr and Ni-Cr alloys: Hastelloy-N, Hastelloy-X, Haynes-230, Inconel-617, and Incoloy-800H, were exposed to molten FLiNaK with the goal of understanding corrosion mechanisms and ranking these alloys for their suitability for molten fluoride salt heat exchanger and thermal storage applications. The tests were performed at 850��������C for 500 h in sealed graphite crucibles under an argon cover gas. Corrosion was noted to occur predominantly from dealloying of Cr from the alloys, an effect that was particularly pronounced at the grain boundaries Alloy weight-loss due to molten fluoride salt exposure correlated with the initial Cr-content of the alloys, and was consistent with the Cr-content measured in the salts after corrosion tests. The alloys���¢�������� weight-loss was also found to correlate to the concentration of carbon present for the nominally 20% Cr containing alloys, due to the formation of chromium carbide phases at the grain boundaries. Experiments involving molten salt exposures of Incoloy-800H in Incoloy-800H crucibles under an argon cover gas showed a significantly lower corrosion for this alloy than when tested in a graphite crucible. Graphite significantly accelerated alloy corrosion due to the reduction of Cr from solution by graphite and formation on Cr-carbide on the graphite surface. Ni-electroplating dramatically reduced corrosion of alloys, although some diffusion of Fe and Cr were observed occur through the Ni plating. A pyrolytic carbon and SiC (PyC/SiC) CVD coating was also investigated and found to be effective in mitigating corrosion. The KCl-MgCl2 molten salt was less corrosive than FLiNaK fluoride salts for corrosion tests performed at 850oC. Cr dissolution in the molten chloride salt was still observed and consequently Ni-201 and Hastelloy N exhibited the least depth of attack. Grain-boundary engineering (GBE) of Incoloy 800H improved the corrosion resistance (as measured by weight loss and maximum depth of attack) by nearly 50% as compared to the as-received Incoloy 800H sample. Because Cr dissolution is an important mechanism of corrosion, molten salt electrochemistry experiments were initiated. These experiments were performed using anodic stripping voltammetry (ASV). Using this technique, the reduction potential of Cr was determined against a Pt quasi-reference electrode as well as against a Ni(II)-Ni reference electrode in molten FLiNaK at 650 oC. The integrated current increased linearly with Cr-content in the salt, providing for a direct assessment of the Cr concentration in a given salt of unknown Cr concentration. To study heat transfer mechanisms in these molten salts over the forced and mixed convection regimes, a forced convective loop was constructed to measure heat transfer coefficients, friction factors and corrosion rates in different diameter tubes in a vertical up flow configuration in the laminar flow regime. Equipment and instrumentation for the forced convective loop was designed, constructed, and tested. These include a high temperature centrifugal pump, mass flow meter, and differential pressure sensing capabilities to an uncertainty of < 2 Pa. The heat transfer coefficient for the KCl-MgCl2 salt was measured in t

Kumar Sridharan; Mark Anderson; Todd Allen; Michael Corradini

2012-01-30T23:59:59.000Z

492

Variable White Dwarf Data Tables  

SciTech Connect (OSTI)

Below, I give a brief explanation of the information in these tables. In all cases, I list the WD {number_sign}, either from the catalog of McCook {ampersand} Sion (1987) or determined by me from the epoch 1950 coordinates. Next, I list the most commonly used name (or alias), then I list the variable star designation if it is available. If not, I list the constellation name and a V** or?? depending on what the last designated variable star for that constellation is. I present epoch 2000 coordinates for all of the stars, which I precessed from the 1950 ones in most cases. I do not include proper motion effects; this is negligible for all except the largest proper motion DAV stars, such as L 19-2, BPM 37093, B 808, and G 29-38. Even in these cases, the error is no more than 30` in declination and 2 s in right ascension. I culled effective temperatures from the latest work (listed under each table); they are now much more homogeneous than before. I pulled the magnitude estimates from the appropriate paper, and they are mean values integrated over several cycles. The amplitude given is for the height of a typical pulse in the light curve. The periods correspond the dominant ones found in the light curve. In some cases, there is a band of power in a given period range, or the light curve is very complex, and I indicate this in the table. In the references, I generally list the paper with the most comprehensive pulsation analysis for the star in question. In some cases, there is more than one good reference, and I list them as well.

Bradley, P. A.

1997-12-31T23:59:59.000Z

493

Environmental Assisted Quantum Information Correction for Continuous Variables  

E-Print Network [OSTI]

Quantum information protocols are inevitably affected by decoherence which is associated with the leakage of quantum information into an environment. In this paper we address the possibility of recovering the quantum information from an environmental measurement. We investigate continuous variable quantum information, and we propose a simple environmental measurement that under certain circumstances fully restores the quantum information of the signal state although the state is not reconstructed with unit fidelity. We implement the protocol for which information is encoded into conjugate quadratures of coherent states of light and the noise added under the decoherence process is of Gaussian nature. The correction protocol is tested using both a deterministic as well as a probabilistic strategy. The potential use of the protocol in a continuous variable quantum key distribution scheme as a means to combat excess noise is also investigated.

Metin Sabuncu; Radim Filip; Gerd Leuchs; Ulrik L. Andersen

2009-09-18T23:59:59.000Z

494

The influence of winter convection on primary production: a parameterisation using a hydrostatic three-dimensional biogeochemical model  

E-Print Network [OSTI]

In the recent past observational and modelling studies have shown that the vertical displacement of water parcels, and therefore, phytoplankton particles in regions of deep-reaching convection plays a key role in late winter/early spring primary production. The underlying mechanism describes how convection cells capture living phytoplankton cells and recurrently expose them to sunlight. This study presents a parameterisation called `phytoconvection' which focuses on the influence of convection on primary production. This parameterisation was implemented into a three-dimensional physical-biogeochemical model and applied to the Northwestern European Continental Shelf and areas of the adjacent Northeast Atlantic. The simulation was compared to a `conventional' parameterisation with respect to its influence on phytoplankton concentrations during the annual cycle and its effect on the carbon cycle. The simulation using the new parameterisation showed good agreement with observation data recorded during winter, whe...

Große, Fabian; Pätsch, Johannes; Backhaus, Jan O

2014-01-01T23:59:59.000Z

495

Atomic filtering for hybrid continuous-variable/discrete-variable quantum optics  

E-Print Network [OSTI]

We demonstrate atomic filtering of frequency-degenerate photon pairs from a sub-threshold optical parametric oscillator (OPO). The filter, a modified Faraday anomalous dispersion optical filter (FADOF), achieves 70% peak transmission simultaneous with 57 dB out-of-band rejection and a 445 MHz transmission bandwidth. When applied to the OPO output, only the degenerate mode, containing one-mode squeezed vacuum, falls in the filter pass-band; all other modes are strongly suppressed. The high transmission preserves non-classical continuous-variable features, e.g. squeezing or non-gaussianity, while the high spectral purity allows reliable discrete-variable detection and heralding. Correlation and atomic absorption measurements indicate a spectral purity of 96% for the individual photons, and 98% for the photon pairs. These capabilities will enable generation of atom-resonant hybrid states, e.g. "Schr\\"odinger kittens" obtained by photon subtraction from squeezed vacuum, making these exotic states available for quantum networking and atomic quantum metrology applications.

Joanna A. Zieli?ska; Federica A. Beduini; Vito Giovanni Lucivero; Morgan W. Mitchell

2014-09-04T23:59:59.000Z

496

Convective heat transfer on leeward building walls in an urban environment: Measurements in an outdoor scale model  

E-Print Network [OSTI]

layer wind speed (height 2H) and the vertical velocity nearthe horizontal wind speed at 2H and the average verticalvertical error bars indicate the magnitude of the UC wind speed

Nottrott, A.; Onomura, S.; Inagaki, A.; Kanda, M.; Kleissl, J.

2011-01-01T23:59:59.000Z

497

Convective heat transfer on leeward building walls in an urban environment: Measurements in an outdoor scale model  

E-Print Network [OSTI]

surface, Proc. 5 th Int. Heat Transfer Conf. 3 (1974) 129-a vertical plate, J. Heat Transfer 109(1) [13] K. Patel,Experimental study of heat transfer in turbulent flows over

Nottrott, A.; Onomura, S.; Inagaki, A.; Kanda, M.; Kleissl, J.

2011-01-01T23:59:59.000Z

498

Scaling behavior in the convection-driven Brazil-nut effect  

E-Print Network [OSTI]

The Brazil-nut effect is the phenomenon in which a large intruder particle immersed in a vertically shaken bed of smaller particles rises to the top, even when it is much denser. The usual practice, while describing these experiments, has been to use the dimensionless acceleration \\Gamma=a \\omega^2/g, where a and \\omega are respectively the amplitude and the angular frequency of vibration and g is the acceleration due to gravity. Considering a vibrated quasi-two-dimensional bed of mustard seeds, we show here that the peak-to-peak velocity of shaking v= a\\omega, rather than \\Gamma, is the relevant parameter in the regime where boundary-driven granular convection is the main driving mechanism. We find that the rise-time \\tau of an intruder is described by the scaling law \\tau ~ (v-v_c)^{-\\alpha}, where v_c is identified as the critical vibration velocity for the onset of convective motion of the mustard seeds. This scaling form holds over a wide range of (a,\\omega), diameter and density of the intruder.

Prakhyat Hejmady; Ranjini Bandyopadhyay; Sanjib Sabhapandit; Abhishek Dhar

2011-11-18T23:59:59.000Z

499

The Brinkman model for thermosolutal convection in a vertical annular porous layer  

SciTech Connect (OSTI)

Double-diffusive natural convection in porous media, i.e. flows generated by buoyancy due to simultaneous temperature and concentration gradients, has received considerable attention in recent years. Interest in this phenomenon has been motivated by such diverse engineering problems as the migration of moisture contained in fibrous insulation, grain storage, the contaminated transport in saturated soil, the underground disposal of nuclear wastes, drying processes, etc. Here, numerical study is carried out on double-diffusive natural convection within a vertical circular porous annulus. Motions are driven by the externally applied constant temperature and concentration differences imposed across the vertical walls of the enclosure. In the formulation of the problem, use is made of the Brinkman extended Darcy model which allows the no-slip boundary condition on a solid wall, to be satisfied. The flow is assumed to be laminar and two dimensional. The density variation is taken into account by the Boussinesq approximation. The control-volume approach is used for solving the governing equations. Solutions for the flow fields, temperature and concentration distributions and Nusselt, {ovr Nu}{sub i} and Sherwood, {ovr Sh}{sub i} numbers are obtained in terms of the governing parameters of the problem. The effect of both the Darcy number, Da, and the radius ratio, {kappa}, or {ovr Nu}{sub i} and {ovr Sh}{sub i} is found to be significant. Results for a pure viscous fluid and a Carcy (densely packed) porous medium emerge from the present model is limiting cases.

Bennacer, R.; Beji, H.; Duval, R.; Vasseur, P.

2000-01-01T23:59:59.000Z

500

Pattern formation and dynamics in Rayleigh-Benard convection : numerical simulations of experimentally realistic geometries.  

SciTech Connect (OSTI)

Rayleigh-Benard convection is studied and quantitative comparisons are made, where possible, between theory and experiment by performing numerical simulations of the Boussinesq equations for a variety of experimentally realistic situations. Rectangular and cylindrical geometries of varying aspect ratios for experimental boundary conditions, including fins and spatial ramps in plate separation, are examined with particular attention paid to the role of the mean flow. A small cylindrical convection layer bounded laterally either by a rigid wall, fin, or a ramp is investigated and our results suggest that the mean flow plays an important role in the observed wavenumber. Analytical results are developed quantifying the mean flow sources, generated by amplitude gradients, and its effect on the pattern wavenumber for a large-aspect-ratio cylinder with a ramped boundary. Numerical results are found to agree well with these analytical predictions. We gain further insight into the role of mean flow in pattern dynamics by employing a novel method of quenching the mean flow numerically. Simulations of a spiral defect chaos state where the mean flow is suddenly quenched is found to remove the time dependence, increase the wavenumber and make the pattern more angular in nature.

Paul, M. R.; Chiarn, K.-H.; Cross, M. C.; Fischer, P. F.; Greenside, H. S.; Mathematics and Computer Science; California Inst. of Tech.; Duke University

2003-10-01T23:59:59.000Z