Science.gov

Sample records for vertical ground-coupled heat

  1. A Modified Analytical Method for Simulating Cyclic Operation of Vertical U-Tube Ground-Coupled Heat Pumps 

    E-print Network

    Dobson, M. K.; O'Neal, D. L.; Aldred, W.

    1994-01-01

    A modified analytical model is presented which discretizes the ground-coupled heat exchanger of a ground-coupled heat pump and utilized a separate cylindrical source solution for each element. First law expressions are utilized for each element...

  2. A Simplified Procedure for Sizing Vertical Ground Coupled Heat Pump Heat Exchangers for Residences in Texas 

    E-print Network

    O'Neal, D. L.; Gonzalez, J. A.; Aldred, W.

    1994-01-01

    for ground temperature, ground density, ground thermal conductivity, and indoor air temperature were presented. Soil temperature and thermal conductivity were found to be the most important parameters for sizing GCHP heat exchangers. Results from...

  3. Optimization of a ground coupled heat pump

    NASA Astrophysics Data System (ADS)

    Baxter, V. D.; Catan, M. A.

    A cooperative analytical project has optimized a horizontal ground coil heat pump system for the Pittsburgh climate. This is the first step in the exploration of several advanced designs including various ground coil devices and advanced heat pump components. The project made use of new and existing design tools to simulate system performance and determine first cost. The system life cycle cost was minimized while constraining the system to meet the design day cooling load using a function minimizing program. Among the system parameters considered were: air-to-refrigerant frontal area, air-to-refrigerant fin pitch, air-to-refrigerant air flowrate, compressor displacement, liquid-to-refrigerant coil length, liquid-to-refrigerant coil diameter, ground coil fluid flowrate, ground coil length, and ground coil depth are described.

  4. Ground-Coupled Heat Pump Applications and Case Studies 

    E-print Network

    Braud, H. J.

    1989-01-01

    ground loop was given by Braud (1). See also Bose et al. (2) and Partin (3). APPLICATIONS OF GROUND-COUPLED HEAT PUMPS COLD SUPPLY +-fi- ;-"" WATER TANK A recent development in ground loop technolorn is to use a ground loop for refrigerators.... Earth drilling is difficult in rock or other problem areas. REFERENCES 1 .Braud, H.J. 1986. Ground loops for heat pump and refrigeration. Building energy symposium. Mechanical En- gineering Department, Texas A&M University. 2. Bose, J.E., J...

  5. Thermal and economic assessment of ground-coupled storage for residential solar heat pump systems

    NASA Astrophysics Data System (ADS)

    Choi, M. K.; Morehouse, J. H.

    1980-11-01

    This study performed an analysis of ground-coupled stand-alone and series configured solar-assisted liquid-to-air heat pump systems for residences. The year-round thermal performance of these systems for space heating, space cooling, and water heating were determined by simulation and compared against non-ground-coupled solar heat pump systems as well as conventional heating and cooling systems in three geographic locations: Washington, D.C., Fort Worth, Tex., and Madison, Wis. The results indicate that without tax credits a combined solar/ground-coupled heat pump system for space heating and cooling is not cost competitive with conventional systems. Its thermal performance is considerably better than non-ground-coupled solar heat pumps in Forth Worth. Though the ground-coupled stand-alone heat pump provides 51% of the heating and cooling load with non-purchased energy in Forth Worth, its thermal performance in Washington and Madison is poor.

  6. Solar goes underground - The SERI packaged ground-coupled heat pump

    SciTech Connect

    MacCracken, C.D.

    1985-01-01

    Independently monitored data from an innovative ground-coupled pump system in a test house is given. Testing was conducted in association with the SERI residential packaged solar heating system program. Innovations included: shallow horizontal slit trenches; multiple small counterflow tubes covered with concrete; two-speed compressor and blower; use of the ground as both heat source and sink; a small tube vertical heat exchanger serving as both evaporator and condenser; superheat coming only from a suction line heat exchanger; only 110 feet of a 4-foot-spaced trenching per ton; elimination of any back-up system; utilization of full night setback; and packaging of system components. Results fully met expectations with performance far better than air-to-air heat pumps since annual heating/cooling compressor COPs were near 3.5. It is felt this compact horizontal trenching system meets a broad requirement.

  7. Performance comparison of air- and ground-coupled heat pump systems. Final report

    SciTech Connect

    Parker, J.D.; Kavanaugh, S.; Ramanathan, R.

    1984-01-01

    Research initiated in 1979 to compare the performance of air-coupled and ground-coupled heat pumps is described. Three heat pump systems were installed in small, neighboring all-electric residences served by the Oklahoma Gas and Electric Company in Perkins, Oklahoma. An air-coupled heat pump and two ground-coupled heat pumps - one with solar assistance - were field tested. However, equipment and instrumentation problems precluded gathering meaningful data for the solar-assisted ground-coupled system. Generally, the unassisted ground-coupled heat pump system proved superior to the air-coupled system, both in reducing peak demand and in consuming less energy on an annual basis. The unassisted ground-coupled system reduced summer and winter peak demand, and experienced no performance degradation due to buildup of rejected waste heat in the ground well. A polyethylene U-tube ground heat exchanger was installed in both ground-coupled systems midway through the project, replacing a five-inch annular PVC pipe arrangement that had functioned poorly. The U-tube performed well throughout the remainder of research. Differing lifestyles and thermostat changes by building occupants during the monitoring period produced quite different demands and loads in the test houses, but when results were normalized through simulation, the superior performance of the unassisted ground-coupled heat pump was confirmed.

  8. Ground-Coupled Heating-Cooling Systems in Urban Areas: How Sustainable Are They?

    ERIC Educational Resources Information Center

    Younger, Paul L.

    2008-01-01

    Ground-coupled heating-cooling systems (GCHCSs) exchange heat between the built environment and the subsurface using pipework buried in trenches or boreholes. If heat pumps in GCHCSs are powered by "green electricity," they offer genuine carbon-free heating-cooling; for this reason, there has been a surge in the technology in recent years.…

  9. Development and Application of a Ground-Coupled Heat Pump Simulation Model for Residential Code-Compliance Simulation in Texas 

    E-print Network

    Do, Sung Lok

    2014-04-18

    The intent of this study was to improve residential energy efficiency in Texas by developing an improved tool for home builders and code officers to use for evaluating their designs. It was achieved by developing a new ground-coupled heat pump (GCHP...

  10. Field Performance of a Ground-Coupled Heat Pump in Abilene, Texas 

    E-print Network

    Dobson, M.; O'Neal, D. L.; Aldred, W.; Margo, R.

    1994-01-01

    (COP), and ground-coil heat rejection. Data for operation in the cooling and heating mode are discussed here. Based on the experimental data, it was discovered that the water temperature entering the condenser (EWT) exhibited a prolonged minimum after...

  11. Ground-Coupled Heat and Moisture Transfer from Buildings; Part 2: Application (Preprint)

    SciTech Connect

    Deru, M.P.; Kirkpatrick, A.T.

    2001-02-21

    In this paper the effects of moisture on the heat transfer from two basic types of building foundations, a slab-on-grade and a basement, are examined. A two-dimensional finite element heat and moisture transfer program is used to show the effects of precipitation, soil type, foundation insulation, water table depth, and freezing on the heat transfer from the building foundation. Comparisons are made with a simple heat conduction model to illustrate the dependency of the soil thermal conductivity on moisture content.

  12. Design, operation and performance of a ground coupled heat pump system in a cold climate

    NASA Astrophysics Data System (ADS)

    Metz, P. D.

    An antifreeze filled serpentine earth coil was designed to just meet heating needs of a small, well insulated house with an average brine temperature never less than 7 C (20 F). The 155 m (507 ft) long, 1.2 m (4 ft) coil made from nominal size 1-1/2 in medium density polyethylene pipe was installed by a local plumbing contractor using two different chain driven trenchers. A commercially available water to air heat pump was used with minor modifications. System performance was monitored using kilowat hour meters, a Btu meter, and a datalogger microcomputer data acquisition system. The house temperature was kept between 21 and 23 C (70 and 74 F) all winter despite outdoor temperature as low as 24 C (-11 F). During a period when the outdoor temperature averaged -2 C (28 F), the system extracted approximately 10.2 x 10 to the 9th power 3 (9.7 x 10 to the 6th power Btu) from the ground with an almost constant heat pump COP (coefficient of performance) averaging about 2.3 and a system COP of 2.2. No resistance heating was used.

  13. A Review of Ground Coupled Heat Pump Models Used in Whole-Building Computer Simulation Programs 

    E-print Network

    Do, S. L.; Haberl, J. S.

    2010-01-01

    , in the 1970s, mathematical models for the GCHP technology were developed and tested by Dr. Jim Bose and Dr. Harry Braud (Wagers & Wagers, 1985). In a similar fashion as the GSHP, the GCHP takes an advantage of the ground as heat source and sink...

  14. Effect of Backfill on the Performance of a Vertical U-Tube Ground Coupled Heat Pump 

    E-print Network

    Gu, Yian

    1995-01-01

    stream_source_info ESL-TH-95-08-04.pdf.txt stream_content_type text/plain stream_size 22501 Content-Encoding ISO-8859-1 stream_name ESL-TH-95-08-04.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Reproduced...) pg. n/a ESL-TH-95-08-04 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ESL-TH-95-08-04 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ESL-TH...

  15. Polysilicon Vertical Actuator Powered with Waste Heat

    E-print Network

    Hamoui, Anas

    Polysilicon Vertical Actuator Powered with Waste Heat J. Varona1 , M. Tecpoyotl-Torres1 , and A. A and electronic circuitry together on the same substrate that can be manufactured in high volumes and low cost due, for example in the automotive industry and in every application using electronic circuitry that dissipates

  16. Geothermal Energy Utilization via Effective Design of Ground-Coupled

    E-print Network

    Tennessee, University of

    Geothermal Energy Utilization via Effective Design of Ground-Coupled Heat Exchange System Charlie of Tennessee Knoxville, TN 37996 05/18/2010 #12;Geothermal energy is the most recent research subject AJ and I ­ Reactive Flow Film Cooling in Turbine · Renewable Energy ­ Geothermal Energy Heat Exchange System ­ Bio

  17. Heat transfer about a vertical permeable membrane

    SciTech Connect

    Kaviany, M. )

    1988-05-01

    The natural convection heat transfer about both sides of vertical walls without any seepage has been studied and the effects of the wall thickness and thermal conductivity on the local and average heat transfer rates have been determined. Viskanta and Lankford have concluded that in predicting the heat transfer rate through the wall, for low-thermal-conductivity walls the a priori unknown wall surface temperatures can be walls the a priori unknown wall surface temperatures can be estimated as the arithmetic average of the reservoir temperatures without loss of accuracy (for most practical situations). Sparrow and Prakash treated the surface temperature as variable but used the local temperature along with the available isothermal boundary-layer analysis for determination of the local heat transfer rate and found this to be reasonable at relatively low Grashof numbers. In this study the heat trasnfer rate between two reservoirs of different temperature connected in part through a permeable membrane is analyzed. Rather than solving the complete problem numerically for the three domains (fluid-wall-fluid), the available results on the effects of suction and blowing on the natural convection boundary layer are used in an analysis of the membranes with low thermal conductivity and small seepage velocities, which are characteristic of membranes considered. This will lead to rather simple expressions for the determination of the heat transfer rate.

  18. Field and Laboratory Study of a Ground-Coupled Water Source Heat Pump with an Integral Enthalpy Exchange System for Classrooms 

    E-print Network

    Domitrovic, R.; Hayzen, G. J.; Johnson, W. S.; Chen, F. C.

    2002-01-01

    technologies is needed to increase the dehumidification abilities of equipment without compromising energy efficiency or the need for fresh ventilation air. To study the effectiveness of integrated heat pump and enthalpy exchange equipment, a nominal 4-ton...

  19. The vertical structure of ocean heat transport G. Boccaletti,1

    E-print Network

    Ferrari, Raffaele

    is through its poleward heat transport: about 1.5 PW or more than 30% of that accomplished by the ocean-atmosphere this heat transport (Watson et al., 2001), for example, reducing high latitude convection and triggeringThe vertical structure of ocean heat transport G. Boccaletti,1 R. Ferrari,1 A. Adcroft,2 D

  20. ENTROPY CONSTRAINTS ON VERTICAL HEAT TRANSPORT AND STRUCTURES

    E-print Network

    ENTROPY CONSTRAINTS ON VERTICAL HEAT TRANSPORT AND STRUCTURES Wei Wu and Yangang Liu are still poorly understood and quantified. In this work, we use a simple 1D vertical energy-entropy climate model to investigate this issue. Especially, we explore the roles of the entropy-rated constraints

  1. Limitations of Using Uniform Heat Flux Assumptions in Sizing Vertical Borehole Heat Exchanger Fields

    E-print Network

    Limitations of Using Uniform Heat Flux Assumptions in Sizing Vertical Borehole Heat Exchanger heat exchangers and the surrounding ground are essential for design, optimization and energy analysis of ground heat exchangers (GHE) used with ground source heat pump (GSHP) systems. These models can account

  2. Numerical model of mixed convection heat transfer between a series of vertical parallel plates with planar heat sources 

    E-print Network

    Watson, James Christopher

    1995-01-01

    Heat transfer between a series of vertical parallel plates with planar heat sources has been studied numerically. The series of plates formed a series of channels, or cooling passages, in which fluid could flow. Heat dissipation from the heat...

  3. Mixed turbulent convective heat transfer in vertical ducts: Final report

    SciTech Connect

    Catton, I.; Swanson, L.

    1988-07-01

    A recently developed heat transfer correlation can help determine acceptable water temperatures during a severe overcooling of the reactor vessel downcomer. This study contributes to an ongoing effort to prevent thermally induced cracking in reactor vessels. Thermally induced cracking develops when cold water suddenly contacts hot metal walls. This phenomenon could occur during certain PWR transients. Following an extensive literature survey, investigators built an experimental test facility to simulate the heat transfer phenomena found in a PWR reactor downcomer. The facility design emphasized reproducing the horizontal and vertical aspect ratios and the correct flow boundary conditions. The investigators selected Freon 113 as a working fluid to attain correct buoyancy forces with minimal wall heating. They then used the facility to test several inlet flows and temperature distributions using a wide range of Prandtl, Reynolds, and Grashof numbers. Thermocouples distributed at various elevations and distances from the walls measured heat fluxes and temperature profiles. The experimental observations allowed a detailed analysis of turbulent flow in the downcomer, from which the team developed a theoretical model of the heat transfer mechanisms. Surface renewal theory provided a starting point for the theoretical investigation. The key product of this study is a heat transfer correlation that accurately represents the impact of the parameters. This correlation fits the experimental data within 7% over Prandtl, Reynolds, and Grashof numbers spanning the thermal-hydraulic conditions commonly found in PWRs. 35 refs., 31 figs.

  4. Flow regimes and heat transfer in vertical narrow annuli

    SciTech Connect

    Ulke, A.; Goldberg, I.

    1993-11-01

    In shell side boiling heat exchangers narrow crevices that are formed between the tubes and the tube support structure provide areas for local thermal-hydraulic conditions which differ significantly from bulk fluid conditions. Understanding of the processes of boiling and dryout in flow restricted crevices can help in designing of tube support geometries to minimize the likelihood of tube support plate and tube corrosion observed in commercial power plant steam generators. This paper describes a one dimensional thermal-hydraulic model of a vertical crevice between a tube and a support plate with cylindrical holes. The annulus formed by the support plate hole and an eccentrically located tube has been represented by vertical strips. The formation, growth and collapse of a steam bubble in each strip has been determined. Based on the bubble history, and flow regimes characterized by ``isolated`` bubbles, ``coalesced`` bubbles and liquid deficient regions have been defined.

  5. Changes in ocean vertical heat transport with global warming

    NASA Astrophysics Data System (ADS)

    Zika, Jan D.; Laliberté, Frédéric; Mudryk, Lawrence R.; Sijp, Willem P.; Nurser, A. J. G.

    2015-06-01

    Heat transport between the surface and deep ocean strongly influences transient climate change. Mechanisms setting this transport are investigated using coupled climate models and by projecting ocean circulation into the temperature-depth diagram. In this diagram, a "cold cell" cools the deep ocean through the downwelling of Antarctic waters and upwelling of warmer waters and is balanced by warming due to a "warm cell," coincident with the interhemispheric overturning and previously linked to wind and haline forcing. With anthropogenic warming, the cold cell collapses while the warm cell continues to warm the deep ocean. Simulations with increasingly strong warm cells, set by their mean Southern Hemisphere winds, exhibit increasing deep-ocean warming in response to the same anthropogenic forcing. It is argued that the partition between components of the circulation which cool and warm the deep ocean in the preindustrial climate is a key determinant of ocean vertical heat transport with global warming.

  6. Natural convection in symmetrically heated vertical parallel plates with discrete heat sources

    SciTech Connect

    Manca, O.; Nardini, S.; Naso, V.

    1996-12-31

    Laminar air natural convection in a symmetrically heated vertical channel with uniform flush-mounted discrete heat sources has been experimentally investigated. The effects of heated strips location and of their number are pointed out in terms of the maximum wall temperatures. A flow visualization in the entrance region of the channel was carried out and air temperatures and velocities in two cross sections have been measured. Dimensionless local heat transfer coefficients have been evaluated and monomial correlations among relevant parameters have bee derived in the local Rayleigh number range 10--10{sup 6}. Channel Nusselt number has been correlated in a polynomial form in terms of channel Rayleigh number.

  7. Vertical heat flux and lateral mass transport in nonlinear internal waves

    E-print Network

    (2010), Vertical heat flux and lateral mass transport in nonlinear internal waves, Geophys. Res. Lett and heat flux over the shelf. [3] By definition, particle speeds (uw) in NLIWs are com- parable to the waveClick Here for Full Article Vertical heat flux and lateral mass transport in nonlinear internal

  8. Bounds on vertical heat transport for infinite Prandtl number Rayleigh-B\\'enard convection

    E-print Network

    Rheinisch-Westfälische Technische Hochschule Aachen (RWTH)

    Bounds on vertical heat transport for infinite Prandtl number Rayleigh- B\\'enard convection Journal of the Boussinesq equations, the enhancement of vertical heat transport in Rayleigh-B´enard convection, the Nusselt and astrophysics. Rayleigh-B´enard convection, where a fluid layer between rigid plates is heated from below

  9. Supermarket with Ground Coupled Carbon Dioxide Refrigeration Plant 

    E-print Network

    Rehault, N.

    2012-01-01

    SUPERMARKET WITH GROUND COUPLED CARBON DIOXIDE REFRIGERATION PLANT Dipl.-Ing. Nicolas R?hault Fraunhofer Institute for Solar Energy Systems ISE ICEBO 2012 Manchester, 25.10.2012 ? Fraunhofer ISE 2 AGENDA 1. Background on supermarkets, energy...

  10. Heat transfer augmentation of mixed convection through vortex shedding from an inclined plate in a vertical channel containing heated blocks

    SciTech Connect

    Wu, H.W.; Perng, S.W.

    1998-02-06

    A numerical analysis is made of the unsteady flow and heat transfer characteristics of mixed convection in a vertical block-heated channel with and without installing an inclined plate above an upstream block. Parameter studies including the inclined plate angle, Reynolds number (ranging from 260 to 530), and Grashof number (in the range of 0--3,200,000) on heat transfer performance have been explored in detail. The results show that the installation of an inclined plate in the vertical block-heated channel can effectively augment the blocks` heat transfer performance in the channel. This can be applied to heat exchangers.

  11. Effect of horizontal heat and fluid flow on the vertical temperature distribution in a semiconfining layer

    USGS Publications Warehouse

    Lu, N.; Ge, S.

    1996-01-01

    By including the constant flow of heat and fluid in the horizontal direction, we develop an analytical solution for the vertical temperature distribution within the semiconfining layer of a typical aquifer system. The solution is an extension of the previous one-dimensional theory by Bredehoeft and Papadopulos [1965]. It provides a quantitative tool for analyzing the uncertainty of the horizontal heat and fluid flow. The analytical results demonstrate that horizontal flow of heat and fluid, if at values much smaller than those of the vertical, has a negligible effect on the vertical temperature distribution but becomes significant when it is comparable to the vertical.

  12. Diffusive vertical heat flux in the Canada Basin of the Arctic Ocean inferred from moored instruments

    NASA Astrophysics Data System (ADS)

    Lique, Camille; Guthrie, John D.; Steele, Michael; Proshutinsky, Andrey; Morison, James H.; Krishfield, Richard

    2014-01-01

    Observational studies have shown that an unprecedented warm anomaly has recently affected the temperature of the Atlantic Water (AW) layer lying at intermediate depth in the Arctic Ocean. Using observations from four profiling moorings, deployed in the interior of the Canada Basin between 2003 and 2011, the upward diffusive vertical heat flux from this layer is quantified. Vertical diffusivity is first estimated from a fine-scale parameterization method based on CTD and velocity profiles. Resulting diffusive vertical heat fluxes from the AW are in the range 0.1-0.2 W m-2 on average. Although large over the period considered, the variations of the AW temperature maximum yields small variations for the temperature gradient and thus the vertical diffusive heat flux. In most areas, variations in upward diffusive vertical heat flux from the AW have only a limited effect on temperature variations of the overlying layer. However, the presence of eddies might be an effective mechanism to enhance vertical heat transfer, although the small number of eddies sampled by the moorings suggest that this mechanism remains limited and intermittent in space and time. Finally, our results suggest that computing diffusive vertical heat flux with a constant vertical diffusivity of ˜2 × 10-6 m2 s-1 provides a reasonable estimate of the upward diffusive heat transfer from the AW layer, although this approximation breaks down in the presence of eddies.

  13. The Design of Ground-Coupled Heat Pump Systems 

    E-print Network

    Parker, J. D.

    1985-01-01

    reliability. Programs of this type have been written and used by several investigators. Ball, et al., have mmpiled an excellent summary of mmputer models and design methdologies for the period up through 1981 (1). Bose, J. E. Water 9-urce HVAC Manual...

  14. A simple model for the interaction between vertical eddy heat fluxes and static stability

    NASA Technical Reports Server (NTRS)

    Gutowski, W. J., Jr.

    1985-01-01

    A numerical model for studying the interaction of vertical eddy heat fluxes and vertical temperature structure in midlatitude regions is described. The temperature profile for the model was derived from calculations of the equilibrium among heating rates in simplified representations of large-scale vertical eddy heat flux, moist convection and radiation. An eddy flux profile is calculated based on the quasi-geostrophic, liner baroclinic instability of a single wave. Model equilibrium states for summer and winter conditions are compared with observations, and the results are discussed in detail.

  15. 45 (2008-5) Heat Transfer of liquid droplets impinging on vertically aligned SWNTs film

    E-print Network

    Maruyama, Shigeo

    45 (2008-5) Heat Transfer of liquid droplets impinging on vertically aligned SWNTs film bonded as a heat transfer surface, the phase change phenomena were investigated. The VA-SWNT film serves camera. By measuring the heat transfer characteristics, the surface of the VA-SWNT film was compared

  16. Vertical Concentric Tube Ground Couoled Heat Exchangers V. C. Mei and S. K. Fischer*

    E-print Network

    Oak Ridge National Laboratory

    #12;Vertical Concentric Tube Ground Couoled Heat Exchangers V. C. Mei and S. K. Fischer* Abstract exchangers for use in heat-pump applications is described. The experimental apparatus consists. This heat exchanger was placed in a 0.20-m (8-in.) inside-diameter well and backfilled with sand

  17. Gas Heat Transfer in a Heated Vertical Channel under Deteriorated Turbulent Heat Transfer Regime

    E-print Network

    Lee, Jeongik

    Passive cooling via natural circulation of gas after a loss of coolant (LOCA) accident is one of the major goals of the Gas-cooled Fast Reactor (GFR). Due to its high surface heat flux and low coolant velocities under ...

  18. Gas heat transfer in a heated vertical channel under deteriorated turbulent heat transfer regime

    E-print Network

    Lee, Jeongik

    2007-01-01

    Passive cooling via natural circulation of gas after a loss of coolant (LOCA) accident is one of the major goals of the Gas-cooled Fast Reactor (GFR). Due to its high surface heat flux and low coolant velocities under ...

  19. A traceable physical calibration of the vertical advection-diffusion equation for modeling ocean heat uptake

    NASA Astrophysics Data System (ADS)

    Huber, Markus; Tailleux, Remi; Ferreira, David; Kuhlbrodt, Till; Gregory, Jonathan

    2015-04-01

    The classic vertical advection-diffusion (VAD) balance is a central concept in studying the ocean heat budget, in particular in simple climate models (SCMs). Here we present a new framework to calibrate the parameters of the VAD equation to the vertical ocean heat balance of two fully-coupled climate models that is traceable to the models' circulation as well as to vertical mixing and diffusion processes. Based on temperature diagnostics, we derive an effective vertical velocity w? and turbulent diffusivity k?? for each individual physical process. In steady state, we find that the residual vertical velocity and diffusivity change sign in middepth, highlighting the different regional contributions of isopycnal and diapycnal diffusion in balancing the models' residual advection and vertical mixing. We quantify the impacts of the time evolution of the effective quantities under a transient 1% CO2 simulation and make the link to the parameters of currently employed SCMs.

  20. Augmentation of condensation heat transfer with electrohydrodynamics on vertical enhanced tubes 

    E-print Network

    Motte, Edouard

    1994-01-01

    from the surface can be realized. The liquid film thickness is reduced and as a result the condensation heat transfer coefficient is increased. A vertical single tube condenser (I m long) is used to investigate the electrohydrodynamically enhanced...

  1. Method and apparatus for determining vertical heat flux of geothermal field

    DOEpatents

    Poppendiek, Heinz F. (LaJolla, CA)

    1982-01-01

    A method and apparatus for determining vertical heat flux of a geothermal field, and mapping the entire field, is based upon an elongated heat-flux transducer (10) comprised of a length of tubing (12) of relatively low thermal conductivity with a thermopile (20) inside for measuring the thermal gradient between the ends of the transducer after it has been positioned in a borehole for a period sufficient for the tube to reach thermal equilibrium. The transducer is thermally coupled to the surrounding earth by a fluid annulus, preferably water or mud. A second transducer comprised of a length of tubing of relatively high thermal conductivity is used for a second thermal gradient measurement. The ratio of the first measurement to the second is then used to determine the earth's thermal conductivity, k.sub..infin., from a precalculated graph, and using the value of thermal conductivity thus determined, then determining the vertical earth temperature gradient, b, from predetermined steady state heat balance equations which relate the undisturbed vertical earth temperature distributions at some distance from the borehole and earth thermal conductivity to the temperature gradients in the transducers and their thermal conductivity. The product of the earth's thermal conductivity, k.sub..infin., and the earth's undisturbed vertical temperature gradient, b, then determines the earth's vertical heat flux. The process can be repeated many times for boreholes of a geothermal field to map vertical heat flux.

  2. Computer cooling using a two phase minichannel thermosyphon loop heated from horizontal and vertical sides and cooled from vertical side

    NASA Astrophysics Data System (ADS)

    Bieli?ski, Henryk; Mikielewicz, Jaros?aw

    2010-10-01

    In the present paper it is proposed to consider the computer cooling capacity using the thermosyphon loop. A closed thermosyphon loop consists of combined two heaters and a cooler connected to each other by tubes. The first heater may be a CPU processor located on the motherboard of the personal computer. The second heater may be a chip of a graphic card placed perpendicular to the motherboard of personal computer. The cooler can be placed above the heaters on the computer chassis. The thermosyphon cooling system on the use of computer can be modeled using the rectangular thermosyphon loop with minichannels heated at the bottom horizontal side and the bottom vertical side and cooled at the upper vertical side. The riser and a downcomer connect these parts. A one-dimensional model of two-phase flow and heat transfer in a closed thermosyphon loop is based on mass, momentum, and energy balances in the evaporators, rising tube, condenser and the falling tube. The separate two-phase flow model is used in calculations. A numerical investigation for the analysis of the mass flux rate and heat transfer coefficient in the steady state has been accomplished.

  3. Numerical analysis of a symmetrically heated vertical channel with obstruction

    NASA Astrophysics Data System (ADS)

    Cammarata, G.; Desrayaud, G.; Fichera, A.; Fischetti, C.

    In this paper, a numerical investigation of laminar natural convection flows in a vertical channel with obstructions is carried out. The main purpose was to analyze the effects of the locations of symmetric obstructions. The computations were performed in a two-dimensional domain and a symmetric uniform wall temperature has been taken as thermal boundary condition. The governing equations were solved using a control volume method and the SIMPLER algorithm for the velocity-pressure coupling was employed. The profiles of the local Nusselt number were given for three different locations of the obstructions. The variation of the average Nusselt number and inlet flow rate versus the modified Rayleigh number were investigated. The results demonstrated that the average Nusselt number decreases as the distance of the obstructions from the inlet increases.

  4. Modeling of Vertical Ground Loop Heat Exchangers with Variable Convective Resistance and Thermal Mass of the Fluid

    E-print Network

    Modeling of Vertical Ground Loop Heat Exchangers with Variable Convective Resistance and Thermal-term behavior of ground loop heat exchangers (GLHE) is critical to the design and energy analysis of ground. 2002), have been used for dimensioning vertical ground heat exchangers. Direct numerical solutions, e

  5. Natural convection along slender vertical cylinders with variable surface heat flux

    SciTech Connect

    Heckel, J.J.; Chen, T.S.; Armaly, B.F. )

    1989-11-01

    Heat transfer by natural convection along a vertical cylinder has been analyzed rather extensively by many investigators using different solution methods. The major restriction to most of these studies is that the solutions are valid only for cylinders with small surface curvature, that is, for cylinders whose diameters are not small. To data no analysis seems to have been presented for natural convection along slender vertical cylinders under the variable surface heat flux condition, and this has motivated the present study as a supplement to the solution of the problem with variable wall temperature.

  6. Experimental Investigation of Free-Convection Heat Transfer in Vertical Tube at Large Grashof Numbers

    NASA Technical Reports Server (NTRS)

    Eckert, E R G; Diaguila, A J

    1955-01-01

    Report presents the results of an investigation conducted to study free-convection heat transfer in a stationary vertical tube closed at the bottom. The walls of the tube were heated, and heated air in the tube was continuously replaced by fresh cool air at the top. The tube was designed to provide a gravitational field with Grashof numbers of a magnitude comparable with those generated by the centrifugal field in rotating-blade coolant passages (10(8) to 10(13)). Local heat-transfer coefficients in the turbulent-flow range and the temperature field within the fluid were obtained.

  7. Natural convection heat transfer in vertical triangular subchannel in Zirconia-water nanofluid

    NASA Astrophysics Data System (ADS)

    Tandian, N. P.; Alkharboushi, A. A. K.; Kamajaya, K.

    2015-09-01

    Natural convection heat transfer in vertical triangular sub-channel has important role in cooling mechanism of the APWR and the PHWR nuclear reactors. Unfortunately, natural convection correlation equations for such geometry are scarcely available. Recent studies showed that ZrO2-water nanofluid has a good prospect to be used in the nuclear reactor technology due to its low neutron absorption cross section. Although several papers have reported transport properties of ZrO2-water nanofluids, practically there is no correlation equation for predicting natural convection heat transfer in a vertical triangular sub-channel in ZrO2-water nanofluid. Therefore, a study for finding such heat transfer correlation equation has been done by utilizing Computational Fluid Dynamics software and reported in this paper. In the study, natural convection heat transfer in a vertical triangular sub-channel has been simulated at several values of heat transfer flux within 9.1 to 30.9 kW/m2 range and ZrO2 concentrations of 0 (pure water), 0.27, and 3 volume-% of ZrO2. The study shows that the ZrO2 concentration has no significant influence to the natural convection heat transfer at those concentration levels. The obtained theoretical heat transfer correlation equations were verified through experiment, and they showed very similar results. The correlation equations are reported in this paper.

  8. Experimental study on condensation heat transfer characteristics of R410A in short vertical tubes

    NASA Astrophysics Data System (ADS)

    Xu, Wenyun; Jia, Li; Tan, Zetao

    2015-06-01

    An experimental study on condensation heat transfer of R410A in short vertical tubes (8.02 mm ID and 10.7mm ID) was presented. Experiments were performed in eight short copper tubes length varied from 300mm to 600mm at mass fluxes range of 58-246 kg m-2s-1 and saturation temperature of 38°C. Effects of mass flux, tube length on condensation heat transfer coefficient were investigated. The distribution of temperature, thickness of condensate film and local condensation heat transfer coefficient along the tube were also analyzed. It is indicated that the entrance effect played an important role in condensation heat transfer of vertical tube, and the influence of entrance effect on average condensation heat transfer coefficients will weaken with the length of tube in the experimental condensation. The experimental results were compared with four well known correlations available in literatures, and the Chen correlation shows good agreement with the experimental data but with ±40% deviation. A new modified condensation heat transfer correlation with 12.7% mean deviation was developed to predict the condensation heat transfer coefficients in short vertical tube based on the experimental data.

  9. Experimental study of natural convective heat transfer in a vertical hexagonal sub channel

    SciTech Connect

    Tandian, Nathanael P.; Umar, Efrizon; Hardianto, Toto; Febriyanto, Catur

    2012-06-06

    The development of new practices in nuclear reactor safety aspects and optimization of recent nuclear reactors, including the APWR and the PHWR reactors, needs a knowledge on natural convective heat transfer within sub-channels formed among several nuclear fuel rods or heat exchanger tubes. Unfortunately, the currently available empirical correlation equations for such heat transfer modes are limited and researches on convective heat transfer within a bundle of vertical cylinders (especially within the natural convection modes) are scarcely done. Although boundary layers around the heat exchanger cylinders or fuel rods may be dominated by their entry regions, most of available convection correlation equations are for fully developed boundary layers. Recently, an experimental study on natural convective heat transfer in a subchannel formed by several heated parallel cylinders that arranged in a hexagonal configuration has been being done. The study seeks for a new convection correlation for the natural convective heat transfer in the sub-channel formed among the hexagonal vertical cylinders. A new convective heat transfer correlation equation has been obtained from the study and compared to several similar equations in literatures.

  10. Heat-transfer characteristics of climbing film evaporation in a vertical tube

    SciTech Connect

    Yang, Luopeng; Chen, Xue; Shen, Shengqiang

    2010-09-15

    Heat-transfer characteristics of climbing film evaporation were experimentally investigated on a vertical climbing film evaporator heated by tube-outside hot water. The experimental setup was designed for determining the effect of the height of feed water inside a vertical tube and the range of temperature difference on local heat transfer coefficient inside a vertical tube (h{sub i}). In this setup, the height of feed water was successfully controlled and the polypropylene shell effectively impedes the heat loss to the ground. The results indicated that a reduction in the height of feed water contributed to a significant increase in h{sub i} if no dry patches around the wall of the heated tube appeared inside the tube. The height ratio of feed water R{sub h} = 0.3 was proposed as the optimal one as dry patches destroyed the continuous climbing film when R{sub h} is under 0.3. It was found that the minimum temperature difference driving climbing film evaporation is suggested as 5 C due to a sharp reduction in h{sub i} for temperature difference below 5 C. The experiment also showed that h{sub i} increased with an increase in temperature difference, which proved the superiority of climbing film evaporation in utilizing low-grade surplus heating source due to its wide range of driving temperature difference. The experimental results were compared with the previous literature and demonstrated a satisfactory agreement. (author)

  11. Heat transfer analysis in a two-side heated smooth square vertical channel with adverse and favorable mixed convection

    SciTech Connect

    Dutta, S.; Zhang, X.; Khan, J.A.; Bell, D.

    1997-07-01

    Experimental heat transfer measurements and analysis for mixed convection in a vertical square channel are presented. The flow direction is changed with respect to the earth's gravity field by selectively opening and closing the flow control valves. Desired flow directions are selected such that buoyancy assists or opposes the bulk flow direction pressure gradient. The heating condition is asymmetric. Most previous experiments used symmetrically heated circular tubes. Present configuration shows significant increase in the Nusselt number in both assisted and opposed flow conditions. In general, opposed flow shows higher heat transfer coefficients. Unlike symmetric heating conditions, Nusselt number ratio is observed to be increasing with increasing Gr/Re or Gr/Re{sup 2} ratios for both assisted and opposed flow conditions.

  12. The Experimental Analysis of Local Heat and Mass Transfer Data for Vertical Falling Film Absorption

    SciTech Connect

    Keyhani, M.; Miller, W.A.

    1999-11-14

    In pure heat transfer, specifications of effectiveness, fluid properties, and flows enable calculation of the heat exchanger area. In the case of falling film absorption, a simultaneous heat and mass transfer governs the performance of the absorber. The exchange of mass across the liquid-vapor interface involves the generation of heat. The heat effects associated with the mass exchange increase the temperature, which affects the equilibrium state of the pressure and composition and in turn affects the mass. The falling film flow rate coupled to the physical properties of kinematic viscosity and surface tension govern the flow regime of a vertical falling film. Wavy-laminar, roll-wave laminar, and turbulent flows will develop convective contributions that can enhance the transfer of mass into the film. The combined interaction of all these factors makes the absorption process very difficult to analyze and predict. A study of simultaneous heat and mass transfer was therefore conduct ed on a vertical falling film absorber to better understand the mechanisms driving the heat and mass transfer processes. Falling films are characteristically unstable, and a wavy-laminar flow was observed during the experimental study. The wavy flow further complicates the problem; therefore, only limited information is known about the temperature and concentration profiles along the length of the absorber that describe the local heat and mass transfer rates.

  13. Vertical heat fluxes generated by mesoscale atmospheric flow induced by thermal inhomogeneities in the PBL

    SciTech Connect

    Dalu, G.A. IFA-CNR, Rome ); Pielke, R.A. )

    1993-03-15

    An analytical evaluation of the vertical heat fluxes associated with the mesoscale flow generated by thermal inhomogeneities in the PBL in the absence of a synoptic wind is presented. Results show that the mesoscale fluxes are of the same order as the diabatic beat fluxes. In the sea-breeze case, results show that in the lower layer of the atmosphere the heat flux is positive over the land and negative over the sea with an overall positive horizontal average. In the free atmosphere above the PBL, the mesoscale vertical heat flux is negative over the land and over the sea. The mesoscale flow contributes to the weakening of the atmospheric stability within a region that extends a Rossby radius distance from the coastline and up to an altitude larger than twice the depth of the convective PBL. The average momentum flux equals zero. Sinusoidally periodic thermal inhomogeneities induce periodic atmospheric cells of the same horizontal scale. The intensity of mesoscale cells increases for increasing values of the wavenumber, maximizes when the wavelength of the forcing is of the order of the local Rossby radius, and then decreases as the wavelength of the forcing decreases. The intensity of the vertical velocity and vertical fluxes is only a weak function of the wavenumber, at large wavenumber. The intensity of the mesoscale heat flux does not decrease substantially at high wavenumbers; however, the transport of cool air over small heated patches of land may cut off the temperature gradient in the atmosphere between the land and water early in the day, thereby reducing the duration of the mesoscale activity. Horizontal diffusion of heat in the convective boundary layer can significantly weaken horizontal temperature gradients for large wavenumbers. Periodic square-wave thermal inhomogeneities are more effective than sinusoidal waves in generating mesoscale cells. When dealing with low resolution models the mesoscale heat fluxes have to be introduced in a parametric form.

  14. Heat transfer in vertical Bridgman growth of oxides - Effects of conduction, convection, and internal radiation

    NASA Technical Reports Server (NTRS)

    Brandon, S.; Derby, J. J.

    1992-01-01

    In the present investigation of crystalline phase internal radiation and heat conduction during the vertical Bridgman growth of a YAG-like oxide crystal, where transport through the melt is dominated by convection and conduction, heat is also noted to be conducted through ampoule walls via natural convection and enclosure radiation. The results of a quasi-steady-state axisymmetric Galerkin FEM indicate that heat transfer through the system is powerfully affected by the optical absorption coefficient of the crystal. The coupling of internal radiation through the crystal with conduction through the ampoule walls promotes melt/crystal interface shapes that are highly reflected near the ampoule wall.

  15. Experimental study on flow boiling heat transfer of LNG in a vertical smooth tube

    NASA Astrophysics Data System (ADS)

    Chen, Dongsheng; Shi, Yumei

    2013-10-01

    An experimental apparatus is set up in this work to study the upward flow boiling heat transfer characteristics of LNG (liquefied natural gas) in vertical smooth tubes with inner diameters of 8 mm and 14 mm. The experiments were performed at various inlet pressures from 0.3 to 0.7 MPa. The results were obtained over the mass flux range from 16 to 200 kg m-2 s-1 and heat fluxes ranging from 8.0 to 32 kW m-2. The influences of quality, heat flux and mass flux, tube diameter on the heat transfer characteristic are examined and discussed. The comparisons of the experimental heat transfer coefficients with the predicted values from the existing correlations are analyzed. The correlation by Zou et al. [16] shows the best accuracy with the RMS deviation of 31.7% in comparison with the experimental data.

  16. Constructal multi-scale package of vertical channels with natural convection and maximal heat transfer density. CONSTRUCTAL DESIGN: THE GENERATION OF MULTI-SCALE HEAT

    E-print Network

    Kihm, IconKenneth David

    transfer density. CONSTRUCTAL DESIGN: THE GENERATION OF MULTI-SCALE HEAT AND FLUID FLOW STRUCTURES-scale structures in natural convection with the objective of maximizing the heat transfer density, or the heat transfer rate per unit of volume§ . The flow volume is filled with vertical equidistant heated blades

  17. Simultaneous heat and mass transfer inside a vertical channel in evaporating a heated falling glycols liquid film

    NASA Astrophysics Data System (ADS)

    Nait Alla, Abderrahman; Feddaoui, M'barek; Meftah, Hicham

    2015-12-01

    The interactive effects of heat and mass transfer in the evaporation of ethylene and propylene glycol flowing as falling films on vertical channel was investigated. The liquid film falls along a left plate which is externally subjected to a uniform heat flux while the right plate is the dry wall and is kept thermally insulated. The model solves the coupled governing equations in both phases together with the boundary and interfacial conditions. The systems of equations obtained by using an implicit finite difference method are solved by Tridiagonal Matrix Algorithm. The influence of the inlet liquid flow, Reynolds number in the gas flow and the wall heat flux on the intensity of heat and mass transfers are examined. A comparison between the results obtained for studied glycols and water in the same conditions is made. The results indicate that water evaporates in more intense way in comparison to glycols and the increase of gas flow rate tends to improve slightly the evaporation.

  18. General analysis of steady laminar mixed convection heat transfer on vertical slender cylinders

    SciTech Connect

    Wang, T.Y.; Kleinstreuer, C. )

    1989-05-01

    A general analysis has been developed to study fluid flow and heat transfer characteristics for steady laminar mixed convection on vertical slender cylinders covering the entire range from pure forced to pure natural convection. Two uniquely transformed sets of axisymmetric boundary-layer equations for the constant wall heat flux case and the isothermal surface case are solved using a two-point finite difference method with Newton linearization. Of interest are the effects of the new mixed convection parameter, the cylinder heating/cooling mode, the transverse curvature parameter, and the Prandtl number on the velocity/temeprature profiles and on the local skin friction parameter and the heat transfer parameter. The results of the validated computer simulation model are as follows. Depending upon the magnitude and direction of the buoyancy force, i.e., the value of the mixed convection parameter and the heating or cooling mode applied, natural convection can have a significant effect on the thermal flow field around vertical cylinders. Specifically, strong variations of the local skin friction parameter and reversing trends in the heat transfer parameter are produced as the buoyancy force becomes stronger in aiding flow. The skin friction parameter increases with higher curvature parameters and Prandtl numbers. Similarly, the modified Nusselt number is larger for higher transverse curvature parameters; however, this parameter may reverse the impact of the Prandtl number on the Nusselt number for predominantly forced convection.

  19. Heat Dissipation Interfaces Based on Vertically Aligned Diamond/Graphite Nanoplatelets.

    PubMed

    Santos, N F; Holz, T; Santos, T; Fernandes, A J S; Vasconcelos, T L; Gouvea, C P; Archanjo, B S; Achete, C A; Silva, R F; Costa, F M

    2015-11-11

    Crystalline carbon-based materials are intrinsically chemically inert and good heat conductors, allowing their applications in a great variety of devices. A technological step forward in heat dissipators production can be given by tailoring the carbon phase microstructure, tuning the CVD synthesis conditions. In this work, a rapid bottom-up synthesis of vertically aligned hybrid material comprising diamond thin platelets covered by a crystalline graphite layer was developed. A single run was designed in order to produce a high aspect ratio nanostructured carbon material favoring the thermal dissipation under convection-governed conditions. The produced material was characterized by multiwavelength Raman spectroscopy and electron microscopy (scanning and transmission), and the macroscopic heat flux was evaluated. The results obtained confirm the enhancement of heat dissipation rate in the developed hybrid structures, when compared to smooth nanocrystalline diamond films. PMID:26495875

  20. Absolute and convective instabilities of the natural convection in a vertical heated slot

    PubMed

    Tao; Zhuang

    2000-12-01

    The spatiotemporal instability of a natural convection flow in vertical heated slot is studied theoretically. The two unstable modes, secondary cell and traveling wave, are illustrated to be absolute and convective instabilities, respectively. Using a model to simulate the temperature gradient in the center of the slot, we propose an interpretation of the mechanism controlling the reverse transition of flow patterns, and explain the temperature fluctuation observed after the reverse transition in terms of the traveling wave mode. PMID:11138079

  1. An approach to heat and mass transfer analysis during film condensation inside a vertical tube

    SciTech Connect

    Kotcioglu, I.; Gullapoglu, S. ); Uyarel, A.Y. ); Kaygusuz, K. ); Dincer, I. )

    1993-03-01

    An Investigation was conducted to determine the effects of non-condensing gas on vapor condensation. Experiments were carried out during condensation of a mixture of water vapor/non-condensing gas along the inner surface of a vertical tube. Air was used as non-condensing gas and the various profiles of the water vapor/non-condensing gas mixture were employed. A theoretical analysis to predict the heat and mass transfer is presented. The amount of the condensed water obtained by the experiments was found to be close to the theoretical results. The obtained heat and mass transfer results were in good agreement with earlier published results.

  2. Augmentation of heat transfer in a bubble agitated vertical rectangular channel

    NASA Astrophysics Data System (ADS)

    Mitra, Asish; Dutta, Tapas Kumar; Ghosh, Dibyendu Narayan

    2012-04-01

    This paper presents the results of an experimental study of convective heat transfer between three parallel vertical plates symmetrically spaced with and without bubble agitation to ascertain the degree of augmentation of the heat transfer coefficients due to agitation. The centre plate was electrically heated, while the other side plates were water-cooled forming two successive parallel vertical rectangular channels of dimensions 20 cm × 3.5 cm × 35 cm (length W, gap L, height H) each. At the bottom of the hot and cold plates air spargers were fitted. Water/ethylene glycol (100%) was used to fill the channels. The superficial gas velocity ranged from 0.0016 to 0.01 m/s. Top, bottom and sides of the channels were open to the water/ethylene glycol in the chamber which is the novel aspect of this study. Experimental data have been correlated as under: Natural convective heat transfer: Nu = 0.60 Gr 0.29, r = 0.96, ? = 0.186, 1.17 E6 < Gr < 1.48 E7; Bubble agitated heat transfer: St = 0.11( ReFrPr 2)-0.23, r = 0.82, ? = 0.002, 1.20 E-2 < ( ReFrPr 2) < 1.36 E2.

  3. Natural Convection Heat and Mass Transfer from Falling Films in Vertical Channels

    NASA Astrophysics Data System (ADS)

    Buck, Gregory Allen

    1990-01-01

    In the design of solar collector/regenerators for use in open cycle absorption refrigeration (OCAR) units, the problem of predicting evaporation rates and solution temperatures is of paramount importance in determining overall cycle performance. This transport of heat and mass is dominated by natural convection with buoyant forces primarily generated as a result of film heating by the solar flux, but aided by the evaporation of water (the lighter species) into the rising moist air stream. In order to better understand the mechanism of these combined buoyant interactions, the governing equations for natural convection flow in a vertical channel bounded by a heated falling film (simulating a glazed collector/regenerator) were solved using several different finite difference techniques. The numerical results were validated against existing experimental and numerical results for simplified boundary conditions. The appropriate nondimensionalization for the falling film boundary condition was established, ostensibly for the first time, and a parametric study for an air-water vapor mixture has been presented. Curve fits to the numerical results were determined for engineering design applications. To further confirm the validity of the numerical solutions, an experimental apparatus was constructed using electric resistance heat to simulate the constant heat flux of the solar source. Water was introduced at the top of this heated vertical surface at various flow rates and under various supplied heat fluxes, and a natural convection channel flow generated between the heated falling film and a parallel, plexiglass surface. Film temperatures and moist air velocity profiles were measured at various streamwise (vertical) locations for comparison with the numerical results. In general, measured film temperatures were 15 to 20 percent lower than the predicted values, but came to within 3 percent of the predictions when experimental uncertainty was incorporated into the numerical inputs. Photographic smoke-wire measurements of the induced moist air velocity were about 20 percent higher than the numerical predictions for small channel gap spacing, and about 50 percent higher for large gap spacing. These trends in the data indicate that a redistribution of the supplied heat flux from the film to the moist air is required to lower predicted film temperatures and raise predicted gas velocities. Physically plausible arguments to explain this redistribution and suggestions for improving the numerical predictions and the experimental measurements are offered.

  4. Experimental study of mixed convection heat transfer in vertical helically coiled tube heat exchangers

    SciTech Connect

    Ghorbani, N.; Taherian, H.; Gorji, M.; Mirgolbabaei, H.

    2010-10-15

    In this study the mixed convection heat transfer in a coil-in-shell heat exchanger for various Reynolds numbers, various tube-to-coil diameter ratios and different dimensionless coil pitch was experimentally investigated. The experiments were conducted for both laminar and turbulent flow inside coil. Effects of coil pitch and tube diameters on shell-side heat transfer coefficient of the heat exchanger were studied. Different characteristic lengths were used in various Nusselt number calculations to determine which length best fits the data and several equations were proposed. The particular difference in this study in comparison with the other similar studies was the boundary conditions for the helical coils. The results indicate that the equivalent diameter of shell is the best characteristic length. (author)

  5. Natural convection heat transfer of nanofluids along a vertical plate embedded in porous medium.

    PubMed

    Uddin, Ziya; Harmand, Souad

    2013-01-01

    The unsteady natural convection heat transfer of nanofluid along a vertical plate embedded in porous medium is investigated. The Darcy-Forchheimer model is used to formulate the problem. Thermal conductivity and viscosity models based on a wide range of experimental data of nanofluids and incorporating the velocity-slip effect of the nanoparticle with respect to the base fluid, i.e., Brownian diffusion is used. The effective thermal conductivity of nanofluid in porous media is calculated using copper powder as porous media. The nonlinear governing equations are solved using an unconditionally stable implicit finite difference scheme. In this study, six different types of nanofluids have been compared with respect to the heat transfer enhancement, and the effects of particle concentration, particle size, temperature of the plate, and porosity of the medium on the heat transfer enhancement and skin friction coefficient have been studied in detail. It is found that heat transfer rate increases with the increase in particle concentration up to an optimal level, but on the further increase in particle concentration, the heat transfer rate decreases. For a particular value of particle concentration, small-sized particles enhance the heat transfer rates. On the other hand, skin friction coefficients always increase with the increase in particle concentration and decrease in nanoparticle size. PMID:23391481

  6. Buoyant instabilities in downward flow in a symmetrically heated vertical channel

    SciTech Connect

    Evans, G.; Greif, R.

    1996-07-01

    This study of the downward flow of nitrogen in a tall, partially heated vertical channel (upstream isothermal at T{sub in}*, heated region isothermal at T{sub s}* downstream adiabatic) shows the strong effects of buoyancy even for small temperature differences. Time-dependent oscillations including periodic flow reversals occur along the channel walls. Although the flow and heat transfer are asymmetric, the temperature and axial component of velocity show symmetric reflections at two times that are half a period apart and the lateral component of velocity shows antisymmetric reflections at the two times. There is strong interaction between the downward flow in the central region of the channel and the upward flow along the heated channel walls. At the top of the heated region, the upward buoyant flow turns toward the center of the channel and is incorporated into the downward flow. Along the channel centerline there are nonmonotonic variations of the axial component of velocity and temperature and a large lateral component of velocity that reverses direction periodically. Results are presented for Re = 219.7 and Gr/Re{sup 2} = 1.83, 8.0, and 13.7. The heat transfer and the frequency of the oscillations increases and the flow and temperature fields become more complex as Gr/Re{sup 2} increases. The results have applications to fiber drying, food processing, crystal growth, solar energy collection, cooling of electronic circuits, ventilation, etc.

  7. Experimental investigation on the heat transfer characteristics and flow pattern in vertical narrow channels heated from one side

    NASA Astrophysics Data System (ADS)

    Huang, Lihao; Li, Gang; Tao, Leren

    2015-08-01

    Experimental investigation for the flow boiling of water in a vertical rectangular channel was conducted to reveal the boiling heat transfer mechanism and flow patterns map aspects. The onset of nucleate boiling went upward with the increasing of the working fluid mass flow rate or the decreasing of the inlet working fluid temperature. As the vapour quality was increased, the local heat transfer coefficient increased first, then decreased, followed by various flow patterns. The test data from other researchers had a similar pattern transition for the bubble-slug flow and the slug-annular flow. Flow pattern transition model analysis was performed to make the comparison with current test data. The slug-annular and churn-annular transition models showed a close trend with current data except that the vapor phase superficial velocity of flow pattern transition was much higher than that of experimental data.

  8. A vertical resonance heating model for X- or peanut-shaped galactic bulges

    NASA Astrophysics Data System (ADS)

    Quillen, Alice C.; Minchev, Ivan; Sharma, Sanjib; Qin, Yu-Jing; Di Matteo, Paola

    2014-01-01

    We explore a second-order Hamiltonian vertical resonance model for X-shaped or peanut-shaped galactic bulges. The X- or peanut-shape is caused by the 2:1 vertical Lindblad resonance with the bar, with two vertical oscillation periods per orbital period in the bar frame. We examine N-body simulations and find that due to the bar slowing down and disc thickening during bar buckling, the resonance and associated peanut-shape moves outward. The peanut-shape is consistent with the location of the 2:1 vertical resonance, independent of whether the bar buckled or not. We estimate the resonance width from the potential m = 4 Fourier component and find that the resonance is narrow, affecting orbits over a narrow range in the angular momentum distribution, dL/L ˜ 0.05. As the resonance moves outward, stars originally in the mid-plane are forced out of the mid-plane and into orbits just within the resonance separatrix. The height of the separatrix orbits, estimated from the Hamiltonian model, is approximately consistent with the peanut-shape height. The peanut- or X-shape is comprised of stars in the vicinity of the resonance separatrix. The velocity distributions from the simulations illustrate that low-inclination orbits are depleted within resonance. Within resonance, the vertical velocity distribution is broad, consistent with resonant heating caused by the passage of the resonance through the disc. In the Milky Way bulge, we relate the azimuthally averaged mid-plane mass density near the vertical resonance to the rotation curve and bar pattern speed. At an estimated vertical resonance galactocentric radius of ˜1.3 kpc, we confirm a mid-plane density of ˜5 × 108 M? kpc-3, consistent with recently estimated mass distributions. We find that the rotation curve, bar pattern speed, 2:1 vertical resonance location, X-shaped tips and mid-plane mass density, are all self-consistent in the Milky Way galaxy bulge.

  9. Heat Transfer in MHD Mixed Convection Flow of a Ferrofluid along a Vertical Channel

    PubMed Central

    Gul, Aaiza; Khan, Ilyas; Shafie, Sharidan; Khalid, Asma; Khan, Arshad

    2015-01-01

    This study investigated heat transfer in magnetohydrodynamic (MHD) mixed convection flow of ferrofluid along a vertical channel. The channel with non-uniform wall temperatures was taken in a vertical direction with transverse magnetic field. Water with nanoparticles of magnetite (Fe3O4) was selected as a conventional base fluid. In addition, non-magnetic (Al2O3) aluminium oxide nanoparticles were also used. Comparison between magnetic and magnetite nanoparticles were also conducted. Fluid motion was originated due to buoyancy force together with applied pressure gradient. The problem was modelled in terms of partial differential equations with physical boundary conditions. Analytical solutions were obtained for velocity and temperature. Graphical results were plotted and discussed. It was found that temperature and velocity of ferrofluids depend strongly on viscosity and thermal conductivity together with magnetic field. The results of the present study when compared concurred with published work. PMID:26550837

  10. Heat Transfer in MHD Mixed Convection Flow of a Ferrofluid along a Vertical Channel.

    PubMed

    Gul, Aaiza; Khan, Ilyas; Shafie, Sharidan; Khalid, Asma; Khan, Arshad

    2015-01-01

    This study investigated heat transfer in magnetohydrodynamic (MHD) mixed convection flow of ferrofluid along a vertical channel. The channel with non-uniform wall temperatures was taken in a vertical direction with transverse magnetic field. Water with nanoparticles of magnetite (Fe3O4) was selected as a conventional base fluid. In addition, non-magnetic (Al2O3) aluminium oxide nanoparticles were also used. Comparison between magnetic and magnetite nanoparticles were also conducted. Fluid motion was originated due to buoyancy force together with applied pressure gradient. The problem was modelled in terms of partial differential equations with physical boundary conditions. Analytical solutions were obtained for velocity and temperature. Graphical results were plotted and discussed. It was found that temperature and velocity of ferrofluids depend strongly on viscosity and thermal conductivity together with magnetic field. The results of the present study when compared concurred with published work. PMID:26550837

  11. Vertical disc heating in Milky Way-sized galaxies in a cosmological context

    E-print Network

    Grand, Robert J J; Gómez, Facundo A; Marinacci, Federico; Pakmor, Rüdiger; Campbell, David J R; Jenkins, Adrian

    2015-01-01

    Vertically extended, high velocity dispersion stellar distributions appear to be a ubiquitous feature of disc galaxies, and both internal and external mechanisms have been proposed to be the major driver of their formation. However, it is unclear to what extent each mechanism can generate such a distribution, which is likely to depend on the assembly history of the galaxy. To this end, we perform 16 high resolution cosmological-zoom simulations of Milky Way-sized galaxies using the state-of-the-art cosmological magneto-hydrodynamical code \\textlcsc{AREPO}, and analyse the evolution of the vertical kinematics of the stellar disc in connection with various heating mechanisms. We find that the bar is the dominant heating mechanism in most cases, whereas spiral arms, radial migration, and adiabatic heating from mid-plane density growth are all sub-dominant. The strongest source, though less prevalent than bars, originates from external perturbations from satellites/sub-halos of masses log$_{10} (M/\\rm M_{\\odot}) ...

  12. Potential vertical movement of large heat-generating waste packages in salt.

    SciTech Connect

    Clayton, Daniel James; Martinez, Mario J.; Hardin, Ernest L.

    2013-05-01

    With renewed interest in disposal of heat-generating waste in bedded or domal salt formations, scoping analyses were conducted to estimate rates of waste package vertical movement. Vertical movement is found to result from thermal expansion, from upward creep or heave of the near-field salt, and from downward buoyant forces on the waste package. A two-pronged analysis approach was used, with thermal-mechanical creep modeling, and coupled thermal-viscous flow modeling. The thermal-mechanical approach used well-studied salt constitutive models, while the thermal-viscous approach represented the salt as a highly viscous fluid. The Sierra suite of coupled simulation codes was used for both approaches. The waste package in all simulations was a right-circular cylinder with the density of steel, in horizontal orientation. A time-decaying heat generation function was used to represent commercial spent fuel with typical burnup and 50-year age. Results from the thermal-mechanical base case showed approximately 27 cm initial uplift of the package, followed by gradual relaxation closely following the calculated temperature history. A similar displacement history was obtained with the package density set equal to that of salt. The slight difference in these runs is attributable to buoyant displacement (sinking) and is on the order of 1 mm in 2,000 years. Without heat generation the displacement stabilizes at a fraction of millimeter after a few hundred years. Results from thermal-viscous model were similar, except that the rate of sinking was constant after cooldown, at approximately 0.15 mm per 1,000 yr. In summary, all calculations showed vertical movement on the order of 1 mm or less in 2,000 yr, including calculations using well-established constitutive models for temperature-dependent salt deformation. Based on this finding, displacement of waste packages in a salt repository is not a significant repository performance issue.

  13. Modeling Vertical Structure and Heat Transport within the Oceans of Ice-covered Worlds (Invited)

    NASA Astrophysics Data System (ADS)

    Goodman, J. C.

    2010-12-01

    Indirect observational evidence provides a strong case for liquid oceans beneath the icy crust of Europa and several other frozen moons in the outer solar system. However, little is known about the fluid circulation within these exotic oceans. As a first step toward understanding circulations driven by buoyancy (rather than mechanical forcing from tides), one must understand the typical vertical structure of temperature, salinity, and thus density within the ocean. Following a common approach from terrestrial oceanography, I have built a "single column convection model" for icy world oceans, which describes the density structure of the ocean as a function of depth only: horizontal variations are ignored. On Earth, this approach is of limited utility, because of the strong influence of horizontal wind-driven currents and sea-surface temperature gradients set in concert with the overlying atmosphere. Neither of these confounding issues is present in an icy world's ocean. In the model, mixing of fluid properties via overturning convection is modeled as a strong diffusive process which only acts when the ocean is vertically unstable. "Double diffusive" processes (salt fingering and diffusive layering) are included: these are mixing processes resulting from the unequal molecular diffusivities of heat and salt. Other important processes, such as heating on adiabatic compression, and freshwater fluxes from melting overlying ice, are also included. As a simple test case, I considered an ocean of Europa-like depth (~100 km) and gravity, heated from the seafloor. To simplify matters, I specified an equation of state appropriate to terrestrial seawater, and a simple isothermal ocean as an initial condition. As expected, convection gradually penetrates upward, warming the ocean to an adiabatic, unstratified equilibrium density profile on a timescale of 50 kyr if 4.5 TW of heat are emitted by the silicate interior; the same result is achieved in proportionally more/less time for weaker/stronger internal heating. Unlike Earth's oceans, I predict that since icy worlds' oceans are heated from below, they will generally be unstratified, with constant potential density from top to bottom. There will be no pycnocline as on Earth, so global ocean currents supported by large-scale density gradients seem unlikely. However, icy world oceans may be "weird" in ways which are unheard-of in terrestrial oceanography The density of sulfate brine has a very different equation of state than chloride brines: does this affect the vertical structure? If the ocean water is very pure, cold water can be less dense than warm. Can this lead to periodic catastrophic overturning, as proposed by other authors? These and other questions are currently being investigated using the single-column convection model as a primary tool.

  14. Downflow heat transfer in a heated ribbed vertical annulus with a cosine power profile

    SciTech Connect

    Anderson, J.L.; Condie, K.G.; Larson, T.K.

    1991-10-01

    Experiments designed to investigate downflow heat transfer in a heated, ribbed annulus test section simulating one of the annular coolant channels of a Savannah River Plant production reactor Mark 22 fuel assembly have been conducted at the Idaho National Engineering Laboratory. The inner surface of the annulus was constructed of aluminum and was electrically heated to provide an axial cosine power profile and a flat azimuthal power shape. Data presented in this report are from the ECS-2c series, which was a follow on series to the ECS-2b series, conducted specifically to provide additional data on the effect of different powers at the same test conditions, for use in evaluation of possible power effects on the aluminum temperature measurements. Electrical powers at 90%, 100%, and 110% of the power required to result in the maximum aluminum temperature at fluid saturation temperature were used at each set of test conditions previously used in the ECS-2b series. The ECS-2b series was conducted in the same test rig as the previous ECS-2b series. Data and experimental description for the ECS-2b series is provided in a previous report. 18 refs., 25 figs., 3 tabs.

  15. Characterization of heat loads from mitigated and unmitigated vertical displacement events in DIII-D

    SciTech Connect

    Hollmann, E. M.; Moyer, R. A.; Commaux, N.; Jernigan, T. J.; Eidietis, N. W.; Humphreys, D. A.; Strait, E. J.; Wesley, J. C.; Lasnier, C. J.; Pitts, R. A.; Sugihara, M.; Watkins, J.

    2013-06-15

    Experiments have been conducted on the DIII-D tokamak to study the distribution and repeatability of heat loads and vessel currents resulting from vertical displacement events (VDEs). For unmitigated VDEs, the radiated power fraction appears to be of order 50%, with the remaining power dominantly conducted to the vessel walls. Shot-to-shot scatter in heat loads measured at one toroidal location is not large (<±50%), suggesting that toroidal asymmetries in conducted heat loads are not large. Conducted heat loads are clearly observed during the current quench (CQ) of both mitigated and unmitigated disruptions. Significant poloidal asymmetries in heat loads and radiated power are often observed in the experiments but are not yet understood. Energy dissipated resistively in the conducting walls during the CQ appears to be small (<5%). The mitigating effect of neon massive gas injection (MGI) as a function of MGI trigger delay has also been studied. Improved mitigation is observed as the MGI trigger delay is decreased. For sufficiently early MGI mitigation, close to 100% radiated energy and a reduction of roughly a factor 2 in vessel forces is achieved.

  16. Pool boiling heat transfer on vertical fins with wire mesh structures

    NASA Astrophysics Data System (ADS)

    Pastuszko, Robert

    2012-04-01

    Experimental investigations into pool boiling heat transfer on finned arrays with internal tunnels limited by copper wire mesh were conducted. The experiments were carried out for water, ethanol and fluorinert FC-72 at atmospheric pressure. The wire net with mesh aperture of 0.3 and 0.5 mm, sintered with the vertical side of the 10 mm high rectangular fins and horizontal inter-fin surface formed a system of connected tunnels. Tunnel width was 0.6 and 1.0 mm. Substantial enhancement of heat transfer coefficient was observed for the investigated surfaces. In water, ethanol and FC-72 boiling the highest increase in the heat transfer coefficient was obtained for the surface with mesh aperture of 0.5 mm and tunnel width of 0.6 mm. The ratio of boiling heat transfer coefficients for the investigated fins with mesh covering and smooth fins (10 mm height), at the heat flux 100 kW/m2, was about 3 for water and ethanol as working fluids.

  17. An Algorithm to Estimate the Heating Budget from Vertical Hydrometeor Profiles.

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Simpson, Joanne; Lang, Stephen; McCumber, Michael; Adler, Robert; Penc, Richard

    1990-12-01

    A simple algorithm to estimate the latent heating of cloud systems from their vertical hydrometer profiles is proposed. The derivation as well as the validation of the algorithm is based on output generated by a non-hydrostatic cloud model with parameterized microphysical processes. Mature and decaying stages of a GATE squall-type convective system have been tested. The algorithm-derived heating budget is in reasonable agreement with the budget predicted by the cloud model. The input to the proposed algorithm can be obtained from either a rain retrieval technique based on information from multichannel passive microwave signals or a kinematic cloud model based on information from Doppler radar wind fields and radar reflectivity patterns. Such an application would have significant implications for spaceborne remote sensing and the large-scale weather prediction data assimilation problem.

  18. An algorithm to estimate the heating budget from vertical hydrometeor profiles

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Simpson, Joanne; Mccumber, Michael; Adler, Robert; Lang, Stephen

    1990-01-01

    A simple algorithm to estimate the latent heating of cloud systems from their vertical hydrometeor profiles is proposed. The derivation as well as the validation of the algorithm is based on output generated by a nonhydrostatic cloud model with parameterized microphysical processes. Mature and decaying stages of a GATE squall-type convective system have been tested. The algorithm-derived heating budget is in reasonable agreement with the budget predicted by the cloud model. The input to the proposed algoritm can be obtained from either a rain retrieval technique based on information from multichannel passive microwave signals or a kinematic cloud model based on information from Doppler radar wind fields and radar reflectivity patterns. Such an application would have significant implications for spaceborne remote sensing and the large-scale weather prediction data assimilation problem.

  19. Vertical single-wall carbon nanotube forests as plasmonic heat pipes.

    PubMed

    Nemilentsau, Andrei M; Rotkin, Slava V

    2012-05-22

    High thermal conductivity of carbon nanotubes (NTs) is attractive for the heat removal applications. However, the problem of efficient thermal coupling to the heater/cooler still needs to be resolved. We study near-field electromagnetic tunneling as a mechanism of heat transfer across the interface. We report interface thermal (Kapitza) conductance between a low-density vertical metallic single-wall NT forest and a quartz substrate on the order of 50 MW/Km(2) and explain it by strong electromagnetic interaction and near-field entanglement between the surface phonon-polaritons in the polar dielectric and the NT plasmons. We predict that the thickness of the NT film can be tweaked to the resonance wavelength of these entangled modes for performance optimization of nanocarbon thermal interconnects. PMID:22480248

  20. Unsteady Pulsatile Flow through a Vertical Constricted Annulus with Heat Transfer

    NASA Astrophysics Data System (ADS)

    Abd elmaboud, Yasser; Mekheimerc, Khaled Saad

    2012-04-01

    This paper investigates the effects of heat transfer and pulsatile flow of a Newtonian fluid (blood) through a vertical annulus with mild constriction on the outer wall while the inner wall represents the catheter tube. An analytical expression in terms of Bessel functions of the first and second kind is obtained for the heat and the velocity components. The variation of pressure gradient with steady flow rate is given as well as the wall shear stress distribution for different values of time. The pressure gradient and the wall shear stress are calculated, and their variations are discussed with respect to the Grashof number, the height of the constriction, and the size of the catheter. It is observed that an increase in the catheter size increases the pressure gradient as well as the wall shear stress

  1. The vertical structure of cloud radiative heating over the Indian subcontinent during summer monsoon

    NASA Astrophysics Data System (ADS)

    Johansson, E.; Devasthale, A.; L'Ecuyer, T.; Ekman, A. M. L.; Tjernström, M.

    2015-10-01

    Clouds forming during the summer monsoon over the Indian subcontinent affect its evolution through their radiative impact as well as the release of latent heat. While the latter is previously studied to some extent, comparatively little is known about the radiative impact of different cloud types and the vertical structure of their radiative heating/cooling effects. Therefore, the main aim of this study is to partly fill this knowledge gap by investigating and documenting the vertical distributions of the different cloud types associated with the Indian monsoon and their radiative heating/cooling using the active radar and lidar sensors onboard CloudSat and CALIPSO. The intraseasonal evolution of clouds from May to October is also investigated to understand pre-to-post monsoon transitioning of their radiative heating/cooling effects. The vertical structure of cloud radiative heating (CRH) follows the northward migration and retreat of the monsoon from May to October. Throughout this time period, stratiform clouds radiatively warm the middle troposphere and cool the upper troposphere by more than ±0.2 K day-1 (after weighing by cloud fraction), with the largest impacts observed in June, July and August. During these months, the fraction of high thin cloud remains high in the tropical tropopause layer (TTL). Deep convective towers cause considerable radiative warming in the middle and upper troposphere, but strongly cool the base and inside of the TTL. This cooling is stronger during active (-1.23 K day-1) monsoon periods compared to break periods (-0.36 K day-1). The contrasting radiative warming effect of high clouds in the TTL is twice as large during active periods than in break periods. These results highlight the increasing importance of CRH with altitude, especially in the TTL. Stratiform (made up of alto- and nimbostratus clouds) and deep convection clouds radiatively cool the surface by approximately -100 and -400 W m-2 respectively while warming the atmosphere radiatively by about 40 to 150 W m-2. While the cooling at the surface induced by deep convection and stratiform clouds is largest during active periods of monsoon, the importance of stratiform clouds further increases during break periods. The contrasting CREs (cloud radiative effects) in the atmosphere and at surface, and during active and break periods, should have direct implications for the monsoonal circulation.

  2. Effect of rolling motion on critical heat flux for subcooled flow boiling in vertical tube

    SciTech Connect

    Hwang, J. S.; Park, I. U.; Park, M. Y.; Park, G. C.

    2012-07-01

    This paper presents defining characteristics of the critical heat flux (CHF) for the boiling of R-134a in vertical tube operation under rolling motion in marine reactor. It is important to predict CHF of marine reactor having the rolling motion in order to increase the safety of the reactor. Marine Reactor Moving Simulator (MARMS) tests are conducted to measure the critical heat flux using R-134a flowing upward in a uniformly heated vertical tube under rolling motion. MARMS was rotated by motor and mechanical power transmission gear. The CHF tests were performed in a 9.5 mm I.D. test section with heated length of 1 m. Mass fluxes range from 285 to 1300 kg m{sup -2}s{sup -1}, inlet subcooling from 3 to 38 deg. C and outlet pressures from 13 to 24 bar. Amplitudes of rolling range from 15 to 40 degrees and periods from 6 to 12 sec. To convert the test conditions of CHF test using R-134a in water, Katto's fluid-to-fluid modeling was used in present investigation. A CHF correlation is presented which accounts for the effects of pressure, mass flux, inlet subcooling and rolling angle over all conditions tested. Unlike existing transient CHF experiments, CHF ratio of certain mass flux and pressure are different in rolling motion. For the mass fluxes below 500 kg m{sup -2}s{sup -1} at 13, 16 (region of relative low mass flux), CHF ratio was decreased but was increased above that mass flux (region of relative high mass flux). Moreover, CHF tend to enhance in entire mass flux at 24 bar. (authors)

  3. The relationship between latent heating, vertical velocity, and precipitation processes: The impact of aerosol

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Li, Xiaowen

    2015-04-01

    In this study, a two-dimensional cloud-resolving model with spectral-bin microphysics is used to investigate the vertical velocity and precipitation associated with three physical processes (i.e., latent heating (LH), cool-pool and ice microphysics) that could determine the aerosol impact on deep convective precipitation. Evaporative cooling in the lower troposphere is found to enhance rainfall under high cloud condensation nuclei (CCN) concentrations versus low in the developing stages of a tropical precipitation system. In contrast, a midlatitude case produced more rainfall under low CCN concentrations. Deep convective invigoration in this case was also via evaporative cooling. Nevertheless, LH release is stronger (especially after initial precipitation) for the case having more rainfall in both the tropical and midlatitude environment. Sensitivity tests are performed to examine the impact of ice and evaporative cooling on the relationship between aerosols, LH and precipitation processes. Detailed analyses of the individual terms governing convective draft strengths show that temperature buoyancy can enhance updrafts (downdrafts) in the middle/lower troposphere in the convective core region; however, the vertical pressure gradient force (PGF) is the same order and acts in the opposite direction. This suggests that the PGF is as important as the LH term in determining convective updraft strength. Water loading is small but on the same order as the net PGF-temperature buoyancy forcing, suggesting that water loading could also be important for cloud vertical velocities. The balance among these terms determines the intensity of convection.

  4. The vertical structure of cloud radiative heating over the Indian subcontinent during summer monsoon

    NASA Astrophysics Data System (ADS)

    Johansson, E.; Devasthale, A.; L'Ecuyer, T.; Ekman, A. M. L.; Tjernström, M.

    2015-02-01

    Every year the monsoonal circulation over the Indian subcontinent gives rise to a variety of cloud types that differ considerably in their ability to heat or cool the atmosphere. These clouds in turn affect monsoon dynamics via their radiative impacts, both at the surface and in the atmosphere. New generation of satellites carrying active radar and lidar sensors are allowing realistic quantification of cloud radiative heating (CRH) by resolving the vertical structure of the atmosphere in an unprecedented detail. Obtaining this information is a first step in closing the knowledge gap in our understanding of the role that different clouds play as regulators of the monsoon and vice versa. Here, we use collocated CloudSat-CALIPSO data sets to understand following aspects of cloud-radiation interactions associated with Indian monsoon circulation. (1) How does the vertical distribution of CRH evolve over the Indian continent throughout monsoon season? (2) What is the absolute contribution of different clouds types to the total CRH? (3) How do active and break periods of monsoon affect the distribution of CRH? And finally, (4) what are the net radiative effects of different cloud types on surface heating? In general, the vertical structure of CRH follows the northward migration and the retreat of monsoon from May to October. It is found that the alto- and nimbostratus clouds intensely warm the middle troposphere and equally strongly cool the upper troposphere. Their warming/cooling consistently exceeds ±0.2 K day-1 (after weighing by vertical cloud fraction) in monthly mean composites throughout the middle and upper troposphere respectively, with largest impact observed in June, July and August. Deep convective towers cause considerable warming in the middle and upper troposphere, but strongly cool the base and inside of the tropical tropopause layer (TTL). Such cooling is stronger during active (-1.23 K day-1) monsoon conditions compared to break periods (-0.36 K day-1). The contrasting warming effect of high clouds inside the TTL is found to be double in magnitude during active conditions compared to break periods. It is further shown that stratiform clouds (combining alto- and nimbostratus clouds) and deep convection significantly cool the surface with net radiative effect in the order of -100 and -400 W m-2, respectively, while warming the atmosphere in the order of 40 and 150 W m-2. While deep convection produces strong cooling at the surface during active periods of monsoon, the importance of stratiform clouds, on the other hand, increases during break periods. The contrasting CREs in the atmosphere and at surface, and during active and break conditions, have direct implications for monsoonal circulation.

  5. Cloud vertical structure, radiative heating profile and diurnal variation during TOGA COARE

    NASA Astrophysics Data System (ADS)

    Qian, Taotao

    This thesis consists of two parts: (1) the vertical structure of clouds and radiative heating during TOGA COARE and (2) diurnal variations during TOGA COARE. The purpose of the first part (Chapter 1) is to determine a realistic gridded (1 degree by 1 degree) cloud vertical structure and radiative heating profile for the Intensive Flux Array (IFA) during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean Atmosphere Response Experiment (COARE). First, we deduce the cloud vertical structure from the sounding data using an improved relative humidity (RH) threshold method. The RH threshold is height-dependent and is tuned by three surface and TOA observations of clouds: the Micropulse Lidar (MPL), the High-Resolution Infrared Sounder (HIRS) and the International Satellite Cloud Climatology Project (ISCCP). Then, a modified CCM3 Column Radiation Model (CRM) is used to calculate the radiative heating profiles. The modification of the CRM replaces the model microphysics with the observed microphysics profiles. The calculated radiation budgets are shown to be consistent with the surface and top of the atmosphere (TOA) observations and are much better than those of the standard version of the CRM. The purpose of the second part (Chapter 2) is to test different diurnal variation mechanisms, that have been proposed in previous studies, by using the abundant observational data obtained during TOGA COARE. The preliminary findings are: (1) The stratiform precipitation lags the convective precipitation, suggesting that the effect of the life cycle of the mesoscale convective systems (MCS) is important to the midnight rainfall maximum; i.e., the stratiform component helps to shift the maximum toward midnight. This supports the MCS life cycle mechanism. (2) This study supports the direct radiation-convection interaction mechanism and emphasize that the variation is strongly affected by the variation of upper-level clouds. (3) The current study does not, however, support the day versus night radiation-subsidence mechanism. The vertical motion in the undisturbed region might be partly forced by the disturbed region, rather than by local radiative cooling. (4) Also, the current study does not support the large-scale radiative destabilization mechanism as the cause of the nocturnal maximum of total precipitation, although it may contribute to the evening maximum of the convective component of precipitation.

  6. Mixed Convection with Conduction and Surface Radiation from a Vertical Channel with Discrete Heating

    NASA Astrophysics Data System (ADS)

    Londhe, S. D.; Rao, C. G.

    2013-10-01

    A numerical investigation into fluid flow and heat transfer for the geometry of a vertical parallel plate channel subjected to conjugate mixed convection with radiation is attempted here. The channel considered has three identical flush-mounted discrete heat sources in its left wall, while the right wall that does not contain any heat source acts as a sink. Air, assumed to be a radiatively non-participating and having constant thermophysical properties subject to the Boussinesq approximation, is the cooling agent. The heat generated in the left wall gets conducted along it and is later dissipated by mixed convection and radiation. The governing equations, considered in their full strength sans the boundary layer approximations, are converted into vorticity-stream function form and are then normalized. These equations along with pertinent boundary conditions are solved through finite volume method coupled with Gauss-Seidel iterative technique. The effects of modified Richardson number, surface emissivity, thermal conductivity and aspect ratio on local temperature distribution along the channel, maximum channel temperature and relative contributions of mixed convection and radiation have been thoroughly studied. The prominence of radiation in the present problem has been highlighted.

  7. Boiling Heat Transfer and Pressure Drop of a Refrigerant Flowing Vertically Downward in a Small Diameter Tube

    NASA Astrophysics Data System (ADS)

    Miyata, Kazushi; Mori, Hideo; Ohishi, Katsumi; Tanaka, Hirokazu

    Experiments were performed on boiling heat transfer and pressure drop of a refrigerant R410A flowing vertically downward in a copper smooth tube of 1.0 mm inside diameter for the development of a high-performance heat exchanger using small diameter tubes for air conditioning systems. Local heat transfer coefficients were measured in a range of mass fluxes from 30 to 200 kg/(m2•s), heat fluxes from 1 to 16 kW/m2 and quality from 0.1 to over 1 at evaporation temperature of 10°C. Pressure drops were measured and flow patterns were observed at mass fluxes from 30 to 200 kg/(m2•s) and quality from 0.1 to 0.9. The characteristics of frictional pressure drop, heat transfer coefficient and dryout qualities were clarified by comparing the measurements with the data for the vertically upward flow previously obtained.

  8. Sensitivity of shortwave radiative flux density, forcing, and heating rates to the aerosol vertical profile

    SciTech Connect

    Guan, Hong; Schmid, Beat; Bucholtz, Anthony; Bergstrom, Robert

    2010-03-31

    The effect of the aerosol vertical distribution on the solar radiation profiles, for idealized and measured profiles of optical properties (extinction and single-scattering albedo (SSA)) during the May 2003 Atmospheric Radiation Measurement (ARM) Aerosol Intensive Observation Period (AIOP), has been investigated using the Rapid Radiative Transfer Model Shortwave (RRTM_SW) code. Calculated profiles of down-welling and up-welling solar fluxes during the AIOP have been compared with the data measured by up- and down-looking solar broadband radiometers aboard a profiling research aircraft. The measured profiles of aerosol extinction, SSA, and water vapor obtained from the same aircraft that carried the radiometers served as the inputs for the model calculations. It is noteworthy that for this study, the uplooking radiometers were mounted on a stabilized platform that kept the radiometers parallel with respect to the earth’s horizontal plane. The results indicate that the shape of the aerosol extinction profiles has very little impact on direct radiative forcings at the top of atmosphere and surface in a cloud-free sky. However, as long as the aerosol is not purely scattering, the shape of the extinction profiles is important for forcing profiles. Identical extinction profiles with different absorption profiles drastically influence the forcing and heating rate profiles. Using aircraft data from 19 AIOP profiles over the Southern Great Plains (SGP), we are able to achieve broadband down-welling solar flux closure within 0.8% (bias difference) or 1.8% (rms difference), well within the expected measurement uncertainty of 1 to 3%. The poorer agreement in up-welling flux (bias -3.7%, rms 10%) is attributed to the use of inaccurate surface albedo data. The sensitivity tests reveal the important role accurate, vertically resolved aerosol extinction data plays in tightening flux closure. This study also suggests that in the presence of a strongly absorbing substance, aircraft flux measurements from a stabilized platform have the potential to determine heating rate profiles. These measurement-based heating rate profiles provide useful data for heating rate closure studies and indirect estimates of single scattering albedo assumed in radiative transfer calculations.

  9. Comparison of Soil Moisture Content Estimated with Air-Launched and Ground-Coupled GPR Techniques

    NASA Astrophysics Data System (ADS)

    Kelly, B. B.; Grote, K. R.

    2007-12-01

    Air-launched Ground Penetrating Radar (GPR) data are commonly used in assessment of pavement conditions for highway and bridge maintenance. These data can be collected over large distances very quickly and have relatively simple data processing requirements, so data processing is usually automated. In contrast, ground- coupled GPR data must be collected more slowly, and ground-coupled data used for soil moisture content estimation usually require a user who is experienced in GPR data interpretation. Thus, air-launched GPR data are used relatively easily for commercial applications, while ground-coupled GPR data used for soil moisture estimation have thus far primarily been employed in research applications. This experiment compares GPR data collected over wet and dry soil in the air-launched and ground-coupled modes to determine whether air-launched data could be used for accurate, field-scale soil moisture estimation. In this experiment, GPR data are collected using 250-, 500-, and 1000-MHz antennas in a large tank with controlled soil moisture conditions. The dielectric constant is determined using reflection coefficient theory for the common-offset air-launched data and electromagnetic velocity analysis of the variable-offset ground-coupled data. Data were initially collected using both the ground-coupled and air-launched modes over wet sand. Then, a 3-cm layer of dry sand was placed over the wet sand, and air-launched and ground-coupled GPR surveys were repeated. Repeated layers of sand, each 3-cm thick, were added until both air-launched and ground-coupled data show no change in dielectric constant with the addition of more dry sand. Analysis of these GPR data will allow comparisons of dielectric constants estimated from both ground-coupled and air-launched data for different frequencies and will indicate the suitability of air-launched GPR techniques for soil moisture estimation. These data will also provide experimental results for the depth of penetration of air-launched GPR signals for different frequencies.

  10. Vertical Profiles of Latent Heating in TRMM: Validation and Assimilation in the GEOS Data Assimilation System. [Year 2001 Project Report

    NASA Technical Reports Server (NTRS)

    Zhang, Ming-Hua

    2001-01-01

    I have derived the vertical profiles of apparent heating Q and Q2 by using 3-hourly balloon sounding data from the ARM SGP sounding array for three IOPs in 2000. These IOPs cover the periods from 3/1 to 3/22, from 9/25 to 10/8, and from 11/27 to 12/22. These heating profiles will be collocated with the TRMM heating profiles for validation studies once the TRMM profiles become available to the investigators. I have also produced the objective analyses of Q1, Q2 and forcing fields for the international GCSS Case 3 Intercomparison project. The GSFC CRM participated in study, based on which TRMM heating profiles are derived. I have also studied to assimilate the vertical heating profile by constraining the cloud-base mass flux in the cumulus convection scheme using the CCM3. I first derive the vertical heating profile for each convective plume of unit cloud-base mass flux. The observed heating profile form ARM is then de-convoluted to derive the cloud base mass fluxes of all individual plumes. These fluxes are compared with those derived from the quasi-equilibrium hypothesis. They are shown to improve many other aspects of the model behavior.

  11. Open-cycle absorption solar cooling: Natural convection heat and mass transfer from falling films in vertical channels

    NASA Astrophysics Data System (ADS)

    Buck, G. A.; Wood, B. D.

    1992-06-01

    In the design of solar collector/regenerators for use in open cycle absorption refrigeration (OCAR) units, the problem of predicting evaporation rates and solution temperatures is of paramount importance in determining overall cycle performance. The governing equations for natural convection flow in a vertical channel bounded by a heated falling film (simulating a glazed collector/regenerator) were solved using several different finite difference techniques. The numerical results were validated against existing experimental and numerical results for simplified boundary conditions. The appropriate nondimensionalization for the falling film boundary condition was established, ostensibly for the first time, and a parametric study for an air-water vapor mixture has been presented. Curve fits to the numerical results were determined for engineering design applications. To further confirm the validity of the numerical solutions, an experimental apparatus was constructed using electric resistance heat to simulate the constant heat flux of the solar source. Water was introduced at the top of this heated vertical surface at various flow rates and under various supplied heat fluxes, and a natural convection channel flow generated between the heated falling film and a parallel, plexiglas surface. Film temperatures and moist air velocity profiles were measured at various streamwise (vertical) locations for comparison with the numerical results.

  12. Transient Heat Transfer from a Wire Inserted into a Vertically Mounted Pipe to Forced Flow Liquid Hydrogen

    NASA Astrophysics Data System (ADS)

    Tatsumoto, Hideki; Shirai, Yasuyuki; Shiotsu, Masahiro; Naruo, Yoshihiro; Kobayashi, Hiroaki; Inatani, Yoshifumi

    The transient heat transfer from a Pt-Co wire heater inserted into a vertically mounted pipe, through which forced flow subcooled liquid hydrogen was passed, is measured by increasing the exponential heat input with various time periods at a pressure of 0.7 MPa and an inlet temperature of 21 K. The flow velocities range from 0.8 to 5.5 m/s. For shorter periods, the non-boiling heat transfer becomes higher than that given by the Dittus-Boelter equation due to the transient conductive heat transfer contribution. In addition, the transient critical heat flux (CHF) becomes higher than the steady-state CHF. The effect of the flow velocity and period on the transient CHF heat flux is also clarified.

  13. Unsteady Convection Flow and Heat Transfer over a Vertical Stretching Surface

    PubMed Central

    Cai, Wenli; Su, Ning; Liu, Xiangdong

    2014-01-01

    This paper investigates the effect of thermal radiation on unsteady convection flow and heat transfer over a vertical permeable stretching surface in porous medium, where the effects of temperature dependent viscosity and thermal conductivity are also considered. By using a similarity transformation, the governing time-dependent boundary layer equations for momentum and thermal energy are first transformed into coupled, non-linear ordinary differential equations with variable coefficients. Numerical solutions to these equations subject to appropriate boundary conditions are obtained by the numerical shooting technique with fourth-fifth order Runge-Kutta scheme. Numerical results show that as viscosity variation parameter increases both the absolute value of the surface friction coefficient and the absolute value of the surface temperature gradient increase whereas the temperature decreases slightly. With the increase of viscosity variation parameter, the velocity decreases near the sheet surface but increases far away from the surface of the sheet in the boundary layer. The increase in permeability parameter leads to the decrease in both the temperature and the absolute value of the surface friction coefficient, and the increase in both the velocity and the absolute value of the surface temperature gradient. PMID:25264737

  14. Unsteady convection flow and heat transfer over a vertical stretching surface.

    PubMed

    Cai, Wenli; Su, Ning; Liu, Xiangdong

    2014-01-01

    This paper investigates the effect of thermal radiation on unsteady convection flow and heat transfer over a vertical permeable stretching surface in porous medium, where the effects of temperature dependent viscosity and thermal conductivity are also considered. By using a similarity transformation, the governing time-dependent boundary layer equations for momentum and thermal energy are first transformed into coupled, non-linear ordinary differential equations with variable coefficients. Numerical solutions to these equations subject to appropriate boundary conditions are obtained by the numerical shooting technique with fourth-fifth order Runge-Kutta scheme. Numerical results show that as viscosity variation parameter increases both the absolute value of the surface friction coefficient and the absolute value of the surface temperature gradient increase whereas the temperature decreases slightly. With the increase of viscosity variation parameter, the velocity decreases near the sheet surface but increases far away from the surface of the sheet in the boundary layer. The increase in permeability parameter leads to the decrease in both the temperature and the absolute value of the surface friction coefficient, and the increase in both the velocity and the absolute value of the surface temperature gradient. PMID:25264737

  15. Nonlinear time series analysis and clustering for jet axis identification in vertical turbulent heated jets

    NASA Astrophysics Data System (ADS)

    Charakopoulos, A. K.; Karakasidis, T. E.; Papanicolaou, P. N.; Liakopoulos, A.

    2014-03-01

    In the present work we approach the hydrodynamic problem of discriminating the state of the turbulent fluid region as a function of the distance from the axis of a turbulent jet axis. More specifically, we analyzed temperature fluctuations in vertical turbulent heated jets where temperature time series were recorded along a horizontal line through the jet axis. We employed data from different sets of experiments with various initial conditions out of circular and elliptical shaped nozzles in order to identify time series taken at the jet axis, and discriminate them from those taken near the boundary with ambient fluid using nonconventional hydrodynamics methods. For each temperature time series measured at a different distance from jet axis, we estimated mainly nonlinear measures such as mutual information combined with descriptive statistics measures, as well as some linear and nonlinear dynamic detectors such as Hurst exponent, detrended fluctuation analysis, and Hjorth parameters. The results obtained in all cases have shown that the proposed methodology allows us to distinguish the flow regime around the jet axis and identify the time series corresponding to the jet axis in agreement with the conventional statistical hydrodynamic method. Furthermore, in order to reject the null hypothesis that the time series originate from a stochastic process, we applied the surrogate data method.

  16. Nonlinear time series analysis and clustering for jet axis identification in vertical turbulent heated jets.

    PubMed

    Charakopoulos, A K; Karakasidis, T E; Papanicolaou, P N; Liakopoulos, A

    2014-03-01

    In the present work we approach the hydrodynamic problem of discriminating the state of the turbulent fluid region as a function of the distance from the axis of a turbulent jet axis. More specifically, we analyzed temperature fluctuations in vertical turbulent heated jets where temperature time series were recorded along a horizontal line through the jet axis. We employed data from different sets of experiments with various initial conditions out of circular and elliptical shaped nozzles in order to identify time series taken at the jet axis, and discriminate them from those taken near the boundary with ambient fluid using nonconventional hydrodynamics methods. For each temperature time series measured at a different distance from jet axis, we estimated mainly nonlinear measures such as mutual information combined with descriptive statistics measures, as well as some linear and nonlinear dynamic detectors such as Hurst exponent, detrended fluctuation analysis, and Hjorth parameters. The results obtained in all cases have shown that the proposed methodology allows us to distinguish the flow regime around the jet axis and identify the time series corresponding to the jet axis in agreement with the conventional statistical hydrodynamic method. Furthermore, in order to reject the null hypothesis that the time series originate from a stochastic process, we applied the surrogate data method. PMID:24730919

  17. Experimental investigation of convection heat transfer of CO{sub 2} at supercritical pressures in a vertical circular tube

    SciTech Connect

    Li, Zhi-Hui; Jiang, Pei-Xue; Zhao, Chen-Ru; Zhang, Yu.

    2010-11-15

    The convection heat transfer characteristics of supercritical CO{sub 2} in a vertical circular tube of 2 mm inner diameter were investigated experimentally for pressures ranging from 78 to 95 bar, inlet temperatures from 25 to 40 C, and inlet Reynolds numbers from 3800 to 20,000. The effects of the heat flux, thermo-physical properties, buoyancy and thermal acceleration on the convection heat transfer were analyzed. The experimental results show that for high inlet Reynolds numbers (e.g. Re = 9000) and high heat fluxes, a significant local deterioration and recovery of the heat transfer was found for upward flows but not for downward flows. Comparison of the experimental data for inlet Reynolds numbers from 3800 to 20,000 with some well-known empirical correlations showed large differences especially when the heat transfer deteriorates and then recovers when the effect of buoyancy is significant. The experimental data was used to develop modified local turbulent Nusselt number correlations for supercritical CO{sub 2} flowing in vertical small circular tubes. (author)

  18. Circulation, heat exchange and vertical structure of the Hornsund - the Svalbard Archipelago fiord.

    NASA Astrophysics Data System (ADS)

    Jakacki, Jaromir; Przyborska, Anna; Kosecki, Szymon; Sundfjord, Arild

    2015-04-01

    The Hornsund fjord is located in the southwestern part of Spitsbergen- the biggest island of the Svalbard Archipelago. The fjord is influenced by two major currents in this area. The first one is the current carrying the cold and less saline waters around the southern Spitsbergen tip, often called the Sørkapp Current or the South Cape Current. The second is the well-known West Spitsbergen Current (WSC), carrying salty and warm Atlantic Waters through Fram Strait into the Arctic Ocean. From a biological point of view, Hornsund can be treated as a young unstable system or cold system, which suggests that it is under an influence of the South Cape Current. Because of limited measurements in this area, the hydrodynamic model MIKE3D has been implemented for this fjord to diagnose which current has the main influence on Hornsund. The fjord domain was extended into the shelf area. At the lateral boundary of the extended domain, data from the ROMS simulation of the Svalbard area made by the Norwegian Institute of Marine Research (IMR) with resolution of 800 m have been used. Atmospheric data from European Centre for Medium Weather Forecast (ECMWF) were employed as well as from the Global Data Assimilation System (GDAS, 1 and 0.5 degrees) reanalysis that uses metrological data from Polish Polar Station located in Hornsund. Based on 5 years of simulation (2005-2010) seasonal and annual general circulation in the fjord has been described. Estimation of the heat transport between fjord and ocean, and between fjord and atmosphere will permit to establish the heat budget and help to evaluate the influence of the South Cape Current and WSC on the fjord ecosystem development. An influence of the fresh water fluxes and vertical structure of water masses and their transformations will be also discussed. This work was partially performed in the frame of the projects GAME (DEC-2012/04/A/NZ8/00661) and AWAKE2 (Pol-Nor/198675/17/2013)

  19. Numerical modeling of a 2K J-T heat exchanger used in Fermilab Vertical Test Stand VTS-1

    SciTech Connect

    Gupta, Prabhat Kumar; Rabehl, Roger

    2014-07-01

    Fermilab Vertical Test Stand-1 (VTS-1) is in operation since 2007 for testing the superconducting RF cavities at 2 K. This test stand has single layer coiled finned tubes heat exchanger before J-T valve. A finite difference based thermal model has been developed in Engineering Equation Solver (EES) to study its thermal performance during filling and refilling to maintain the constant liquid level of test stand. The model is also useful to predict its performance under other various operating conditions and will be useful to design the similar kind of heat exchanger for future needs. Present paper discusses the different operational modes of this heat exchanger and its thermal characteristics under these operational modes. Results of this model have also been compared with the experimental data gathered from the VTS-1 heat exchanger and they are in good agreement with the present model.

  20. Forced convection heat transfer from a wire inserted into a vertically-mounted pipe to liquid hydrogen flowing upward

    NASA Astrophysics Data System (ADS)

    Tatsumoto, H.; Shirai, Y.; Shiotsu, M.; Naruo, Y.; Kobayashi, H.; Inatani, Y.

    2014-12-01

    Forced convection heat transfer from a PtCo wire with a length of 120 mm and a diameter of 1.2 mm that was inserted into a vertically-mounted pipe with a diameter of 8.0 mm to liquid hydrogen flowing upward was measured with a quasi-steady increase of a heat generation rate for wide ranges of flow rate under saturated conditions. The pressures were varied from 0.4 MPa to 1.1 MPa. The non-boiling heat transfer characteristic agrees with that predicted by Dittus-Boelter correlation. The critical heat fluxes are higher for higher flow rates and lower pressures. Effect of Weber number on the CHF was clarified and a CHF correlation that can describe the experimental data is derived based on our correlation for a pipe.

  1. MHD Free Convective Boundary Layer Flow of a Nanofluid past a Flat Vertical Plate with Newtonian Heating Boundary Condition

    PubMed Central

    Uddin, Mohammed J.; Khan, Waqar A.; Ismail, Ahmed I.

    2012-01-01

    Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement. PMID:23166688

  2. MHD free convective boundary layer flow of a nanofluid past a flat vertical plate with Newtonian heating boundary condition.

    PubMed

    Uddin, Mohammed J; Khan, Waqar A; Ismail, Ahmed I

    2012-01-01

    Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement. PMID:23166688

  3. Experimental investigation of free-convection heat transfer in vertical tube at large Grashof numbers / E. R. G. Eckert, A. J. Diaguila

    NASA Technical Reports Server (NTRS)

    Eckert, E R G; Diaguila, A J

    1952-01-01

    Local free-convection heat-transfer coefficients and temperature fields in the turbulent flow range were obtained within a vertical, stationary tube closed at the boom, heated along its walls, and having a length-to-diameter ratio of 5. Convective heat-transfer coefficients were correlated by the general relations for free-convection heat transfer. These coefficients, converted to dimensionless Nusselt numbers were 35 percent below known relations for vertical flat plates. Air temperature measurements within the tube indicated a thin boundary layer along the heated wall surface and unstable conditions in the air flow.

  4. Retrieved Vertical Profiles of Latent Heat Release Using TRMM Rainfall Products

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Olson, W. S.; Meneghini, R.; Yang, S.; Simpson, J.; Kummerow, C.; Smith, E.

    2000-01-01

    This paper represents the first attempt to use TRMM rainfall information to estimate the four dimensional latent heating structure over the global tropics for February 1998. The mean latent heating profiles over six oceanic regions (TOGA COARE IFA, Central Pacific, S. Pacific Convergence Zone, East Pacific, Indian Ocean and Atlantic Ocean) and three continental regions (S. America, Central Africa and Australia) are estimated and studied. The heating profiles obtained from the results of diagnostic budget studies over a broad range of geographic locations are used to provide comparisons and indirect validation for the heating algorithm estimated heating profiles. Three different latent heating algorithms, the Goddard Convective-Stratiform (CSH) heating, the Goddard Profiling (GPROF) heating, and the Hydrometeor heating (HH) are used and their results are intercompared. The horizontal distribution or patterns of latent heat release from the three different heating retrieval methods are quite similar. They all can identify the areas of major convective activity (i.e., a well defined ITCZ in the Pacific, a distinct SPCZ) in the global tropics. The magnitude of their estimated latent heating release is also not in bad agreement with each other and with those determined from diagnostic budget studies. However, the major difference among these three heating retrieval algorithms is the altitude of the maximum heating level. The CSH algorithm estimated heating profiles only show one maximum heating level, and the level varies between convective activity from various geographic locations. These features are in good agreement with diagnostic budget studies. By contrast, two maximum heating levels were found using the GPROF heating and HH algorithms. The latent heating profiles estimated from all three methods can not show cooling between active convective events. We also examined the impact of different TMI (Multi-channel Passive Microwave Sensor) and PR (Precipitation Radar) rainfall information on latent heating structures.

  5. Inverse conjugate mixed convection in a vertical substrate with protruding heat sources: a combined experimental and numerical study

    NASA Astrophysics Data System (ADS)

    Ahamad, Shaik Imran; Balaji, C.

    2015-07-01

    This paper reports the results of a combined numerical and experimental study to estimate the heat inputs of three protruding heat sources of the same size placed on a vertically placed PCB board of height 150 mm, depth 250 mm, and thickness 5 mm. First, limited measurements of temperatures were recorded at eight locations along the height of the back of the PCB board for different (and known) values of heat inputs of the protruding heat sources and different velocities. These were followed by three-dimensional calculations of fluid flow and conjugate heat transfer for various heat transfer coefficients on the backside of the PCB board. The difference between the CFD predicted and experimentally measured temperature distributions on the back of the PCB board was minimized using least squares and the best value of heat transfer coefficient was obtained. Using this `data assimilated' CFD model, detailed CFD simulations were done for various values of heat input values and Reynolds numbers (each of these can be different from one another) of the flow. The temperatures at the same eight locations at the back of the PCB board were noted. An artificial neural network was then developed with ten inputs (eight temperatures together with the input velocity and the ambient temperature) to estimate the three outputs (three heat inputs) after carrying out extensive studies on the architecture of the network. This inverse solution was then tested with experiments for validating the ANN approach to solve the inverse conjugate heat transfer problem. Finally, with the ANN estimated heat inputs, CFD simulations were again run to compare the temperature distribution at the back of the PCB board with measurements.

  6. Numerical modelling the unsteady process of closed rectangular area radiant heating in conjugate formulation with accounting energy distribution along horizontal and vertical enclosure structures

    NASA Astrophysics Data System (ADS)

    Nee, A. E.

    2014-08-01

    Mathematical modelling of unsteady convective-conductive heat exchange in premises, heated by infrared radiant heater is passed. Heat flux density from infrared radiant heater was calculated accounting energy distribution along horizontal and vertical building envelope. Comparison between zonal method and Lambert's law radiant energy distribution was done.

  7. Experimental investigation on heat transfer and frictional characteristics of vertical upward rifled tube in supercritical CFB boiler

    SciTech Connect

    Yang, Dong; Pan, Jie; Zhu, Xiaojing; Bi, Qincheng; Chen, Tingkuan; Zhou, Chenn Q.

    2011-02-15

    Water wall design is a key issue for supercritical Circulating Fluidized Bed (CFB) boiler. On account of the good heat transfer performance, rifled tube is applied in the water wall design of a 600 MW supercritical CFB boiler in China. In order to investigate the heat transfer and frictional characteristics of the rifled tube with vertical upward flow, an in-depth experiment was conducted in the range of pressure from 12 to 30 MPa, mass flux from 230 to 1200 kg/(m{sup 2} s), and inner wall heat flux from 130 to 720 kW/m{sup 2}. The wall temperature distribution and pressure drop in the rifled tube were obtained in the experiment. The normal, enhanced and deteriorated heat transfer characteristics were also captured. In this paper, the effects of pressure, inner wall heat flux and mass flux on heat transfer characteristics are analyzed, the heat transfer mechanism and the frictional resistance performance are discussed, and the corresponding empirical correlations are presented. The experimental results show that the rifled tube can effectively prevent the occurrence of departure from nucleate boiling (DNB) and keep the tube wall temperature in a permissible range under the operating condition of supercritical CFB boiler. (author)

  8. The vertical structure of diabatic heating associated with the Madden-Julian oscillation simulated by the Goddard Laboratory for Atmospheres climate model

    NASA Technical Reports Server (NTRS)

    Chen, Tsing-Chang; Yen, Ming-Cheng; Pfaendtner, James; Sud, Y. C.

    1993-01-01

    The diabatic heating structure of the nine-layer Goddard Laboratory for Atmospheres model of the Madden-Julian oscillation (MJO) is illustrated with composite charts made for those times when this low-frequency mode reaches its maximum and minimum amplitudes. These composite charts compare the vertically integrated diabatic heating with potential functions, the vertical distribution of diabatic heating with the east-west mass flux function in the tropics, and the vertical profiles of diabatic heating at the centers of maximum and minimum MJO amplitude. Three interesting features of the model MJO's diabatic heating are revealed: (1) the maximum heating rate of this low-frequency mode is located over the Asian monsoon region and its amplitude is about a half of the maximum value of the seasonal mean heating rate in this region, (2) the vertical diabatic heating rate profile has a maximum at 500 mbar and resembles the seasonal mean total heating profile, and (3) the total diabatic heating is for the most part composed of the latent heat released by cumulus convection.

  9. Transient natural convective flow of a nanofluid past a vertical plate in the presence of heat generation

    NASA Astrophysics Data System (ADS)

    Loganathan, P.; Nirmal Chand, P.; Ganesan, P.

    2015-05-01

    In this work, an exact analysis on the effects of heat generation and nanoparticle volume concentration on an unsteady free convective flow of a nanofluid past an impulsively started infinite vertical plate is presented. Nanofluids containing nanoparticles of aluminum oxide, copper, titanium oxide, and silver with a nanoparticle volume concentration range smaller than or equal to 0.04 are considered. The governing dimensionless partial differential equations are solved by using the Laplace transform technique. The effects of heat generation and nanoparticle volume concentration on the velocity and temperature profiles are represented graphically. The expressions for the skin friction coefficient and Nusselt number are derived. The effect of heat transfer is found to be more pronounced in a silver-water nanofluid than in the other nanofluids. Comparisons with other published results are found to be in excellent agreement.

  10. Numerical simulation of laminar film boiling heat transfer from vertically suspended smooth surfaces in cryogenic fluids subjected to constant wall heat flux

    SciTech Connect

    Akyuzlu, K.M.; Malipeddi, S.

    1996-12-31

    This study is aimed at solving the one-field conservation of mass, momentum, and energy equations for laminar film boiling from vertically suspended smooth surfaces in cryogenic fluids subjected to constant wall heat flux boundary condition. Solutions to the problem of laminar film boiling under constant wall temperature boundary condition have been obtained in the past using analytical and iterative techniques. Here, the governing equations are solved under constant heat flux boundary condition using an analytical method supplemented with curve fitting techniques. The procedure is iterative because it assumes the vapor film thickness to start the calculations and then uses the energy equation at the interface to check the accuracy of this assumption. A computer program was developed to integrate this iterative procedure with a scheme that repeats the calculations at different discrete locations along the heated surface to estimate the laminar film thickness and to generate the velocity and the temperature profiles within the film boundary. The numerical results are compared to the experimental results for a stainless steel plate vertically suspended in liquid nitrogen where the plate is heated by constant current. The numerical predictions are matched with the experimental results by using a calibration parameter that relates various properties of the liquid and the vapor.

  11. Diurnal and vertical variability of the sensible heat and carbon dioxide budgets in the atmospheric surface layer

    USGS Publications Warehouse

    Casso-Torralba, P.; de Arellano, J. V. -G.; Bosveld, F.; Soler, M.R.; Vermeulen, A.; Werner, C.; Moors, E.

    2008-01-01

    The diurnal and vertical variability of heat and carbon dioxide (CO2) in the atmospheric surface layer are studied by analyzing measurements from a 213 in tower in Cabauw (Netherlands). Observations of thermodynamic variables and CO2 mixing ratio as well as vertical profiles of the turbulent fluxes are used to retrieve the contribution of the budget terms in the scalar conservation equation. On the basis of the daytime evolution of turbulent fluxes, we calculate the budget terms by assuming that turbulent fluxes follow a linear profile with height. This assumption is carefully tested and the deviation ftom linearity is quantified. The budget calculation allows us to assess the importance of advection of heat and CO2 during day hours for three selected days. It is found that, under nonadvective conditions, the diurnal variability of temperature and CO2 is well reproduced from the flux divergence measurements. Consequently, the vertical transport due to the turbulent flux plays a major role in the daytime evolution of both scalars and the advection is a relatively small contribution. During the analyzed days with a strong contribution of advection of either heat or carbon dioxide, the flux divergence is still an important contribution to the budget. For heat, the quantification of the advection contribution is in close agreement with results from a numerical model. For carbon dioxide, we qualitatively corroborate the results with a Lagrangian transport model. Our estimation of advection is compared with, traditional estimations based on the Net Ecosystem-atmosphere Exchange (NEE). Copyright 2008 by the American Geophysical Union.

  12. Seismic-geodynamic constraints on three-dimensional structure, vertical flow, and heat transfer in the mantle

    USGS Publications Warehouse

    Forte, A.M.; Woodward, R.L.

    1997-01-01

    Joint inversions of seismic and geodynamic data are carried out in which we simultaneously constrain global-scale seismic heterogeneity in the mantle as well as the amplitude of vertical mantle flow across the 670 km seismic discontinuity. These inversions reveal the existence of a family of three-dimensional (3-D) mantle models that satisfy the data while at the same time yielding predictions of layered mantle flow. The new 3-D mantle models we obtain demonstrate that the buoyancy forces due to the undulations of the 670 km phase-change boundary strongly inhibit the vertical flow between the upper and lower mantle. The strong stabilizing effect of the 670 km topography also has an important impact on the predicted dynamic topography of the Earth's solid surface and on the surface gravity anomalies. The new 3-D models that predict strongly or partially layered mantle flow provide essentially identical fits to the global seismic data as previous models that have, until now, predicted only whole-mantle flow. The convective vertical transport of heat across the mantle predicted on the basis of the new 3-D models shows that the heat flow is a minimum at 1000 km depth. This suggests the presence at this depth of a globally defined horizon across which the pattern of lateral heterogeneity changes rapidly. Copyright 1997 by the American Geophysical Union.

  13. Equipment for the emplacement of heat-producing waste in long horizontal boreholes. [Horizontal vs vertical emplacement

    SciTech Connect

    Young, K.D.; Scully, L.W.; Fisk, A.; deBakker, P.; Friant, J.; Anderson, A.

    1983-01-01

    Emplacement of heat-producing waste in long horizontal holes may offer several technical and economic advantages over shallow vertical hole emplacement. Less of the host rock suffers damage as a result of drift construction; the heat from the waste can be isolated from the access drifts for long periods of time; and the amount of rock which must be excavated is much less than in traditional disposal scenarios. One of the major reasons that has been used to reject the long hole concept in the past and adhere to the shallow vertical hole concept is the equipment required to drill the holes and to emplace and retrieve the waste. Such equipment does not currently exist. It clearly is more difficult to drill a 600 to 1000 foot horizontal hole, possibly 3 to 4 feet in diameter, and place a canister of waste at the end of it than to drill a 30 foot vertical hole and lower the waste to the bottom. A liner, for emplacement hole stabilization, appears to be feasible by adapting existing technology for concrete slip forming or jacking in a steel liner. The conceptual design of the equipment to drill long horizontal holes, emplace waste and retrieve waste will be discussed. Various options in concept will be presented as well as their advantages and disadvantages. The operating scenario of the selected concept will be described as well as solutions to potential problems encountered.

  14. Ocean Turbulence. Paper 2; One-Point Closure Model Momentum, Heat and Salt Vertical Diffusivities in the Presence of Shear

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Howard, A.; Cheng, Y.; Dubovikov, M. S.

    1999-01-01

    We develop and test a 1-point closure turbulence model with the following features: 1) we include the salinity field and derive the expression for the vertical turbulent diffusivities of momentum K(sub m) , heat K(sub h) and salt K(sub s) as a function of two stability parameters: the Richardson number R(sub i) (stratification vs. shear) and the Turner number R(sub rho) (salinity gradient vs. temperature gradient). 2) to describe turbulent mixing below the mixed layer (ML), all previous models have adopted three adjustable "background diffusivities" for momentum, heat and salt. We propose a model that avoids such adjustable diffusivities. We assume that below the ML, the three diffusivities have the same functional dependence on R( sub i) and R(sub rho) as derived from the turbulence model. However, in order to compute R(sub i) below the ML, we use data of vertical shear due to wave-breaking.measured by Gargett et al. The procedure frees the model from adjustable background diffusivities and indeed we employ the same model throughout the entire vertical extent of the ocean. 3) in the local model, the turbulent diffusivities K(sub m,h,s) are given as analytical functions of R(sub i) and R(sub rho). 5) the model is used in an O-GCM and several results are presented to exhibit the effect of double diffusion processes. 6) the code is available upon request.

  15. Boiling Heat Transfer and Pressure Drop of a Refrigerant Flowing Vertically Upward in a Small Diameter Tube

    NASA Astrophysics Data System (ADS)

    Miyata, Kazushi; Mori, Hideo; Ohishi, Katsumi; Tanaka, Hirokazu

    In the present study, experiments were performed to examine characteristics of flow boiling heat transfer and pressure drop of a refrigerant R410A flowing vertically upward in a copper smooth tube with 1.0 mm inside diameter for the development of a high-performance heat exchanger using small diameter tubes for air conditioning systems. Local heat transfer coefficients were measured in a range of mass fluxes from 30 to 200 kg/(m2•s), heat fluxes from 1 to 16 kW/m2 and qualities from 0.1 to over 1 at evaporation temperature of 10°C, and pressure drops were also measured at mass fluxes of 100 and 200 kg/(m2•s) and qualities from 0.1 to 0.9. Three types of flow pattern were observed in the tube: A slug, a slug-annular and an annular flow. Based on the measurements, the characteristics of frictional pressure drop, heat transfer coefficient and dryout qualities were clarified. The measured pressure drop and heat transfer coefficient were compared with correlations.

  16. Evaporation heat transfer and friction characteristics of R-134a flowing downward in a vertical corrugated tube

    SciTech Connect

    Aroonrat, Kanit; Wongwises, Somchai

    2011-01-15

    Differently from most previous studies, the heat transfer and friction characteristics of the pure refrigerant HFC-134a during evaporation inside a vertical corrugated tube are experimentally investigated. The double tube test sections are 0.5 m long with refrigerant flowing in the inner tube and heating water flowing in the annulus. The inner tubes are one smooth tube and two corrugated tubes, which are constructed from smooth copper tube of 8.7 mm inner diameter. The test runs are performed at evaporating temperatures of 10, 15, and 20 C, heat fluxes of 20, 25, and 30 kW/m{sup 2}, and mass fluxes of 200, 300, and 400 kg/m{sup 2} s. The quality of the refrigerant in the test section is calculated using the temperature and pressure obtained from the experiment. The pressure drop across the test section is measured directly by a differential pressure transducer. The effects of heat flux, mass flux, and evaporation temperature on the heat transfer coefficient and two-phase friction factor are also discussed. It is found that the percentage increases of the heat transfer coefficient and the two-phase friction factor of the corrugated tubes compared with those of the smooth tube are approximately 0-10% and 70-140%, respectively. (author)

  17. Heat and mass transfer from a row of tubes in a vertical plane of an evaporative heat dissipator

    SciTech Connect

    Rana, R.S. ); Charan, V.; Varma, H.K. )

    1989-11-01

    Evaporative cooling is used in the chemical industry and in refrigeration systems. In an evaporative tubular heat exchanger, the water is made to fall over horizontal tubes inside which hot fluid passes. Water flowing over the tubes is cooled evaporatively by the air blown from bottom to top. Simultaneous heat and mass transfer takes place in the equipment. The investigation of heat and mass transfer of a row of tubes is considered here as the first step in addressing the problem of evaporative cooling in a bank of tubes.

  18. Measuring the electrical properties of soil using a calibrated ground-coupled GPR system

    USGS Publications Warehouse

    Oden, C.P.; Olhoeft, G.R.; Wright, D.L.; Powers, M.H.

    2008-01-01

    Traditional methods for estimating vadose zone soil properties using ground penetrating radar (GPR) include measuring travel time, fitting diffraction hyperbolae, and other methods exploiting geometry. Additional processing techniques for estimating soil properties are possible with properly calibrated GPR systems. Such calibration using ground-coupled antennas must account for the effects of the shallow soil on the antenna's response, because changing soil properties result in a changing antenna response. A prototype GPR system using ground-coupled antennas was calibrated using laboratory measurements and numerical simulations of the GPR components. Two methods for estimating subsurface properties that utilize the calibrated response were developed. First, a new nonlinear inversion algorithm to estimate shallow soil properties under ground-coupled antennas was evaluated. Tests with synthetic data showed that the inversion algorithm is well behaved across the allowed range of soil properties. A preliminary field test gave encouraging results, with estimated soil property uncertainties (????) of ??1.9 and ??4.4 mS/m for the relative dielectric permittivity and the electrical conductivity, respectively. Next, a deconvolution method for estimating the properties of subsurface reflectors with known shapes (e.g., pipes or planar interfaces) was developed. This method uses scattering matrices to account for the response of subsurface reflectors. The deconvolution method was evaluated for use with noisy data using synthetic data. Results indicate that the deconvolution method requires reflected waves with a signal/noise ratio of about 10:1 or greater. When applied to field data with a signal/noise ratio of 2:1, the method was able to estimate the reflection coefficient and relative permittivity, but the large uncertainty in this estimate precluded inversion for conductivity. ?? Soil Science Society of America.

  19. Stability of a vertical liquid film with consideration of the marangoni effect and heat exchange with the environment

    NASA Astrophysics Data System (ADS)

    Burmistrova, O. A.

    2014-05-01

    The stability of a free vertical liquid film under the combined action of gravity and thermocapillary forces has been studied. An exact solution of the Navier-Stokes and thermal conductivity equations is obtained for the case of plane steady flow with constant film thickness. It is shown that if the free surfaces of the film are perfectly heat insulated, the liquid flow rate through the cross section of the layer is zero. It is found that to close the model with consideration of the heat exchange with the environment, it is necessary to specify the liquid flow rate and the derivative of the temperature with respect to the longitudinal coordinate or the flow rate and the film thickness. The stability of the solution with constant film thickness at small wave numbers is studied. A solution of the spectral problem for perturbations in the form of damped oscillations is obtained.

  20. Vertical Mass, Momentum, Moisture, and Heat Fluxes in Hurricanes above 10 km during CAMEX-3 and CAMEX-4

    NASA Technical Reports Server (NTRS)

    Pfister, Leonhard; Bui, Paul; Herman, Robert; Dean-Day, Jon; Hipskind, R. Stephen (Technical Monitor)

    2002-01-01

    The third and fourth NASA Convection and Moisture Experiments (CAMEX-3 and CAMEX-4) during the Atlantic hurricane seasons of 1998 and 2001, respectively, have yielded comprehensive multi-aircraft datasets using, both remote and in-situ instrumentation. Among these are high-frequency in-situ measurements of vertical wind, horizontal wind, temperature, and water vapor, made from NASA's DC-8 aircraft in the upper portions of the hurricane (typically above 10 km). Wind and temperature measurements were made at 20 hz by the NASA/Ames Meteorological Measurement System, while water vapor was measured at 1 hz by the NASA/JPL Laser Hygrometer. Fluxes of heat, momentum, and moisture at these levels are important, since modeling studies have shown that ice processes, which are dominant at temperatures below -40C (where the DC-8 flies) are important for hurricane intensification. Also, there are indications from satellite studies that latent heat release at DC-8 levels is significant, perhaps a third of those in the mid-troposphere. Preliminary results show that typical updrafts in the eyewall region are comparable to or higher than previous observations of tropical convection, with several instances of updraft magnitudes of 15 meters per second (the maximum observed was 21 meters per second). They also show significant supersaturations (10-20% or more) in the updrafts, which would enhance the latent heat release at the upper levels of the hurricane. This paper will examine the magnitude and distribution of small and mesoscale vertical fluxes of mass, momentum, moisture, and heat. The goal is to examine the role of these fluxes in the overall budgets of the respective quantities in the upper portions of the hurricane.

  1. Influence of wick properties in a vertical LHP on remove waste heat from electronic equipment

    NASA Astrophysics Data System (ADS)

    Smitka, Martin; Nemec, Patrik; Malcho, Milan

    2014-08-01

    The loop heat pipe is a vapour-liquid phase-change device that transfers heat from evaporator to condenser. One of the most important parts of the LHP is the porous wick structure. The wick structure provides capillary force to circulate the working fluid. To achieve good thermal performance of LHP, capillary wicks with high permeability and porosity and fine pore radius are expected. The aim of this work is to develop porous wick of sintered nickel powder with different grain sizes. These porous wicks were used in LHP and there were performed a series of measurements to remove waste heat from the insulated gate bipolar transistor (IGBT).

  2. Influence of wick properties in a vertical LHP on remove waste heat from electronic equipment

    SciTech Connect

    Smitka, Martin E-mail: patrik.nemec@fstroj.uniza.sk Nemec, Patrik E-mail: patrik.nemec@fstroj.uniza.sk Malcho, Milan E-mail: patrik.nemec@fstroj.uniza.sk

    2014-08-06

    The loop heat pipe is a vapour-liquid phase-change device that transfers heat from evaporator to condenser. One of the most important parts of the LHP is the porous wick structure. The wick structure provides capillary force to circulate the working fluid. To achieve good thermal performance of LHP, capillary wicks with high permeability and porosity and fine pore radius are expected. The aim of this work is to develop porous wick of sintered nickel powder with different grain sizes. These porous wicks were used in LHP and there were performed a series of measurements to remove waste heat from the insulated gate bipolar transistor (IGBT)

  3. The flow structure under mixed convection in a uniformly heated vertical pipe

    E-print Network

    Lee, Jeongik

    2005-01-01

    For decay heat removal systems in the conceptual Gas-cooled Fast Reactor (GFR) currently under development, passive emergency cooling using natural circulation of a gas at an elevated pressure is being considered. Since ...

  4. MHD Forced Convective Laminar Boundary Layer Flow from a Convectively Heated Moving Vertical Plate with Radiation and Transpiration Effect

    PubMed Central

    Uddin, Md. Jashim; Khan, Waqar A.; Ismail, A. I. Md.

    2013-01-01

    A two-dimensional steady forced convective flow of a Newtonian fluid past a convectively heated permeable vertically moving plate in the presence of a variable magnetic field and radiation effect has been investigated numerically. The plate moves either in assisting or opposing direction to the free stream. The plate and free stream velocities are considered to be proportional to whilst the magnetic field and mass transfer velocity are taken to be proportional to where is the distance along the plate from the leading edge of the plate. Instead of using existing similarity transformations, we use a linear group of transformations to transform the governing equations into similarity equations with relevant boundary conditions. Numerical solutions of the similarity equations are presented to show the effects of the controlling parameters on the dimensionless velocity, temperature and concentration profiles as well as on the friction factor, rate of heat and mass transfer. It is found that the rate of heat transfer elevates with the mass transfer velocity, convective heat transfer, Prandtl number, velocity ratio and the magnetic field parameters. It is also found that the rate of mass transfer enhances with the mass transfer velocity, velocity ratio, power law index and the Schmidt number, whilst it suppresses with the magnetic field parameter. Our results are compared with the results existing in the open literature. The comparisons are satisfactory. PMID:23741295

  5. Impact of aerosol vertical distribution on aerosol direct radiative effect and heating rate in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Pappas, Vasileios; Hatzianastassiou, Nikolaos; Matsoukas, Christos; Koras Carracca, Mario; Kinne, Stefan; Vardavas, Ilias

    2015-04-01

    It is now well-established that aerosols cause an overall cooling effect at the surface and a warming effect within the atmosphere. At the top of the atmosphere (TOA), both positive and negative forcing can be found, depending on a number of other factors, such as surface albedo and relative position of clouds and aerosols. Whilst aerosol surface cooling is important due to its relation with surface temperature and other bio-environmental reasons, atmospheric heating is of special interest as well having significant impacts on atmospheric dynamics, such as formation of clouds and subsequent precipitation. The actual position of aerosols and their altitude relative to clouds is of major importance as certain types of aerosol, such as black carbon (BC) above clouds can have a significant impact on planetary albedo. The vertical distribution of aerosols and clouds has recently drawn the attention of the aerosol community, because partially can account for the differences between simulated aerosol radiative forcing with various models, and therefore decrease the level of our uncertainty regarding aerosol forcing, which is one of our priorities set by IPCC. The vertical profiles of aerosol optical and physical properties have been studied by various research groups around the world, following different methodologies and using various indices in order to present the impact of aerosols on radiation on different altitudes above the surface. However, there is still variability between the published results as to the actual effect of aerosols on shortwave radiation and on heating rate within the atmosphere. This study uses vertical information on aerosols from the Max Planck Aerosol Climatology (MAC-v1) global dataset, which is a combination of model output with quality ground-based measurements, in order to provide useful insight into the vertical profile of atmospheric heating for the Mediterranean region. MAC-v1 and the science behind this aerosol dataset have already been presented and its validity has been tested against satellite-based retrievals. A detailed spectral radiative transfer model (RTM), already used in a number of planetary and regional studies, has been used in the present study to calculate the vertically distributed aerosol direct radiative effects (DREs) and the associated aerosol heating/cooling profiles within the troposphere. Specific emphasis is given to assessment of the crucial issue of the differences between modeling the aerosol DREs using either columnar aerosol optical properties, as usually done, or vertically layered information on those properties, which is the state of the art and ideal practice. To address this problem, the following experiment has been performed: the same RTM has been used twice with the same meteorological conditions but in the first run (set1) columnar values for aerosol optical depth (AOD) have been used while using vertically distributed AOD in the second run (set2). In the second run vertically layered information for AOD is considered for 20 layers extending from the surface to 20 km a.m.s.l.. The vertical profile of AOD has been mainly based on ECHAM model. The aerosol DREs are computed at the Earth's surface, at TOA and at various levels in the atmosphere. Apart from AOD, the model also requires single-scattering albedo (SSA) and asymmetry parameter (ASY) in 18 different wavelengths, which are obtained by linear interpolation from the available wavelengths in HAC. The comparison between the obtained two sets of DRE (set1 and set2) reveal small, but notable differences which vary from one place to another. Within the atmosphere, the difference -averaged over the four seasons - ranges from -0.3 to 1.7 Wm-2 with a mean value of 0.32 Wm-2. Given the fact that the average column-integrated DREAtm values for the entire Mediterranean region based on columnar aerosol optical properties is 11.44 Wm-2, there is an average variance of 3.7 %, which locally could get to 14.9 %. Differences between the columnar and the vertically layered versions of the model also exist for DRE(TOA)

  6. Flow boiling heat transfer in vertical tubes correlated by an asymptotic model

    SciTech Connect

    Steiner, D.; Taborek, J. )

    1992-01-01

    In flow boiling, the nucleate an convective components are superimposed by a very complex mechanism, which so far is not well understood. Two models exist in this paper, one by Chen, using addition of the two components with a suppression factor; and one by Shah, using the greater of the two components with a Bo-number simplified correlation. Neither model presents a satisfactory solution, as attested by the numerous methods published since them, mostly based only on regression analysis-derived correction factors. In this article a new model, based on asymptotic addition of the two boiling components, is introduced. It follows the established principles of flow boiling and converges correctly to the extremes of all parameters. Tested on the University of Karlsruhe data bank containing over 13,000 data points in vertical flow boiling, results superior to previous correlations are demonstrated.

  7. The empirical correlations for natural convection heat transfer Al2O3 and ZrO2 nanofluid in vertical sub-channel

    NASA Astrophysics Data System (ADS)

    Kamajaya, K.; Umar, E.; Sudjatmi

    2015-09-01

    Study on convection heat transfer using water-Al2O3 nanofluid as the working fluid in the vertical sub-channel has been conducted. The results of the study have been compared with the water-ZrO2 nanofluid and pure-water as the working fluid. The equipment used in this experiment is a vertical triangular sub-channel, equipped by primary cooling system, heat exchanger and a secondary cooling system. As a heating source used three vertical cylinders that have a uniform heat flux with a pitch to diameter ratio (P/D) 01:16. Cooling is used is water-Al2O3 colloid at 0.05 wt. %. Heat transfer from heating to cooling would occur in natural or forced convection. However, in this study will be discussed only natural convection heat transfer. The results showed that the natural convection heat transfer of water-Al2O3 nanofluid in a triangular sub-channels depending on the position. The results of the correlation as follows,

  8. Influence of Test Tube Material on Subcooled Flow Boiling Critical Heat Flux in Short Vertical Tube

    SciTech Connect

    Koichi Hata; Masahiro Shiotsu; Nobuaki Noda

    2006-07-01

    The steady state subcooled flow boiling critical heat flux (CHF) for the flow velocities (u = 4.0 to 13.3 m/s), the inlet subcooling ({delta}T{sub sub,in} = 48.6 to 154.7 K), the inlet pressure (P{sub in} = 735.2 to 969.0 kPa) and the increasing heat input (Q{sub 0} exp(t/t), t = 10, 20 and 33.3 s) are systematically measured with the experimental water loop. The 304 Stainless Steel (SUS304) test tubes of inner diameters (d = 6 mm), heated lengths (L = 66 mm) and L/d = 11 with the inner surface of rough finished (Surface roughness, R{sub a} = 3.18 {mu}m), the Cupro Nickel (Cu-Ni 30%) test tubes of d = 6 mm, L = 60 mm and L/d = 10 with R{sub a} = 0.18 {mu}m and the Platinum (Pt) test tubes of d = 3 and 6 mm, L = 66.5 and 69.6 mm, and L/d 22.2 and 11.6 respectively with R{sub a} = 0.45 {mu}m are used in this work. The CHF data for the SUS304, Cu-Ni 30% and Pt test tubes were compared with SUS304 ones for the wide ranges of d and L/d previously obtained and the values calculated by the authors' published steady state CHF correlations against outlet and inlet subcooling. The influence of the test tube material on CHF is investigated into details and the dominant mechanism of subcooled flow boiling critical heat flux is discussed. (authors)

  9. Heat and Mass Transfer in a Second Grade Fluid Over a Stretching Vertical Surface in a Porous Medium

    NASA Astrophysics Data System (ADS)

    Baoku, I. G.; Onifade, Y. S.; Adebayo, L. O.; Yusuff, K. M.

    2015-05-01

    The investigation deals with the combined heat and mass transfer in a mixed convection boundary layer flow over a stretching vertical surface in a porous medium filled with a viscoelastic second grade fluid. The partial differential equations governing the model have been transformed by a similarity transformation and the system of coupled-ordinary differential equations is solved by employing the shooting method with the fifth-order Runge-Kutta-Fehlberg iteration technique. Effects of various values of physical parameters embedded in the flow model on the dimensionless velocity, temperature and concentration distributions are discussed and shown with the aid of graphs. Numerical values of physical quantities, such as the local skin-coefficient, local Nusselt number and local Sherwood number are presented in a tabular form. It is observed that the boundary layer fluid velocity increases as the second grade parameter, mixed convection parameter and Prandtl number increase.

  10. Study of dynamic structure and heat and mass transfer of a vertical ceramic tiles dryer using CFD simulations

    NASA Astrophysics Data System (ADS)

    Kriaa, Wassim; Bejaoui, Salma; Mhiri, Hatem; Le Palec, Georges; Bournot, Philippe

    2014-02-01

    In this study, we developed a two-dimensional Computational Fluid Dynamics (CFD) model to simulate dynamic structure and heat and mass transfer of a vertical ceramic tiles dryer (EVA 702). The carrier's motion imposed the choice of a dynamic mesh based on two methods: "spring based smoothing" and "local remeshing". The dryer airflow is considered as turbulent ( Re = 1.09 × 105 at the dryer inlet), therefore the Re-Normalization Group model with Enhanced Wall Treatment was used as a turbulence model. The resolution of the governing equation was performed with Fluent 6.3 whose capacities do not allow the direct resolution of drying problems. Thus, a user defined scalar equation was inserted in the CFD code to model moisture content diffusion into tiles. User-defined functions were implemented to define carriers' motion, thermo-physical properties… etc. We adopted also a "two-step" simulation method: in the first step, we follow the heat transfer coefficient evolution (Hc). In the second step, we determine the mass transfer coefficient (Hm) and the features fields of drying air and ceramic tiles. The found results in mixed convection mode (Fr = 5.39 at the dryer inlet) were used to describe dynamic and thermal fields of airflow and heat and mass transfer close to the ceramic tiles. The response of ceramic tiles to heat and mass transfer was studied based on Biot numbers. The evolutions of averages temperature and moisture content of ceramic tiles were analyzed. Lastly, comparison between experimental and numerical results showed a good agreement.

  11. A Vertical Resonance Heating Model for X- or Peanut-Shaped Galactic Bulges

    E-print Network

    Quillen, Alice C; Sharma, Sanjib; Di Matteo, Paola

    2013-01-01

    We explore a second order Hamiltonian vertical resonance model for X-shaped galactic bulges. We examine N-body simulations and find that due to the bar slowing down and disk thickening during bar buckling, the resonance and associated peanut-shape moves outward. The peanut-shape is consistent with the location of the resonance, independent of whether the bar buckled or not. We estimate the resonance width from the potential m=4 Fourier component and find that the resonance is narrow, affecting orbits in angular momentum over a range dL/L ~ 0.05. As the resonance moves outward, stars originally in the mid plane are forced out of the mid plane and into orbits just within the resonance separatrix. The height of these orbits, estimated from the Hamiltonian model, is consistent with the peanut-shape height. The X-shape is comprised of stars in these orbits as they are the only ones that would support the peanut-shape in the drifting system. The resonance condition in the Milky Way bulge relates the mid-plane mass ...

  12. Ocean Turbulence. Paper 3; Two-Point Closure Model Momentum, Heat and Salt Vertical Diffusivities in the Presence of Shear

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Dubovikov, M. S.; Howard, A.; Cheng, Y.

    1999-01-01

    In papers 1 and 2 we have presented the results of the most updated 1-point closure model for the turbulent vertical diffusivities of momentum, heat and salt, K(sub m,h,s). In this paper, we derive the analytic expressions for K(sub m,h,s) using a new 2-point closure model that has recently been developed and successfully tested against some approx. 80 turbulence statistics for different flows. The new model has no free parameters. The expressions for K(sub m, h. s) are analytical functions of two stability parameters: the Turner number R(sub rho) (salinity gradient/temperature gradient) and the Richardson number R(sub i) (temperature gradient/shear). The turbulent kinetic energy K and its rate of dissipation may be taken local or non-local (K-epsilon model). Contrary to all previous models that to describe turbulent mixing below the mixed layer (ML) have adopted three adjustable "background diffusivities" for momentum. heat and salt, we propose a model that avoids such adjustable diffusivities. We assume that below the ML, K(sub m,h,s) have the same functional dependence on R(sub i) and R(sub rho) derived from the turbulence model. However, in order to compute R(sub i) below the ML, we use data of vertical shear due to wave-breaking measured by Gargett et al. (1981). The procedure frees the model from adjustable background diffusivities and indeed we use the same model throughout the entire vertical extent of the ocean. Using the new K(sub m,h, s), we run an O-GCM and present a variety of results that we compare with Levitus and the KPP model. Since the traditional 1-point (used in papers 1 and 2) and the new 2-point closure models used here represent different modeling philosophies and procedures, testing them in an O-GCM is indispensable. The basic motivation is to show that the new 2-point closure model gives results that are overall superior to the 1-point closure in spite of the fact that the latter rely on several adjustable parameters while the new 2-point closure has none. After the extensive comparisons presented in papers 1 and 2, we conclude that the new model presented here is overall superior for it not only is parameter free but also 2 because is part of a more general turbulence model that has been previously successfully tested on a wide variety of other types of turbulent flows.

  13. Retrieving latent heating vertical structure from cloud and precipitation Profiles—Part I: Warm rain processes

    NASA Astrophysics Data System (ADS)

    Min, Qilong; Li, Rui; Wu, Xiaoqing; Fu, Yunfei

    2013-06-01

    An exploratory study on physical based latent heat (LH) retrieval algorithm is conducted by parameterizing the physical linkages of hydrometeor profiles of cloud and precipitation to the major processes related to the phase change of atmospheric water. Specifically, rain events are segregated into three rain types: warm, convective, and stratiform, based on their dynamical and thermodynamical characteristics. As the first of the series, only the warm rain LH algorithm is presented and evaluated here. The major microphysical processes of condensation and evaporation for warm rain are parameterized through traditional rain growth theory, with the aid of Cloud Resolving Model (CRM) simulations. The evaluation or the self-consistency tests indicate that the physical based retrievals capture the fundamental LH processes associated with the warm rain life cycle. There is no significant systematic bias in terms of convection strength, illustrated by the month-long CRM simulation as the mesoscale convective systems (MCSs) experience from initial, mature, to decay stages. The overall monthly-mean LH comparison showed that the total LH, as well as condensation heating and evaporation cooling components, agree with the CRM simulation.

  14. Particle image velocimetry measurements for opposing flow in a vertical channel with a differential and asymmetric heating condition

    SciTech Connect

    Martinez-Suastegui, L.; Trevino, C.

    2007-10-15

    Particle image velocimetry (PIV) measurements were carried out in an experimental investigation of laminar mixed convection in a vertical duct with a square cross-section. The main downward water-flow is driven by gravity while a portion of a lateral side is heated, and buoyancy forces produce non-stationary vortex structures close to the heated region. Various ranges of the Grashof number, Gr are studied in combination with the Reynolds number, Re varying from 300 to 700. The values of the generalized buoyancy parameter or Richardson number, Ri = Gr/Re{sup 2} parallel to the Grashof number are included in the results. The influence of these nondimensional parameters and how they affect the fluid flow structure and vortex sizes and locations are reported. The flow patterns are nonsymmetric, periodic, and exhibit increasing complexity and frequency for increasing buoyancy. For the averaged values of the resulting vortex dimensions, it was found that a better and more congruent representation occurs when employing the Grashof and Reynolds numbers as independent parameters. (author)

  15. MEASURED SPACE CONDITIONING PERFORMANCE OFA VERTICAL-BORE GROUND SOURCE HEAT PUMP (GSHP) OVER TWELVE MONTHS UNDER SIMULATED OCCUPANCY LOADS

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D; Baxter, Van D; Gehl, Anthony C

    2014-01-01

    This paper presents monthly performance metrics of a 7.56 kW (2.16 ton) GSHP serving the space conditioning loads of a 251m2 (2700ft2) residential home with a phase change material in its envelope, and a single vertical-bore 94.5m (310 ft) ground loop. The same ground loop also serviced a ground source heat pump water heater. Envelope characteristics are discussed briefly in the context of reducing thermal losses. Data on entering water temperatures, energy extracted from the ground, energy delivered/removed, compressor electricity use, COP, GSHP run times (low and high compressor stages), and the impact of fan and pump energy consumption on efficiency are presented for each month. Both practical as well as research and development issues are discussed. The findings suggest that GSHPs represent a practical technology option to reduce source energy reduction and greenhouse emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 target of generating over 25% of heat consumed in the EU from renewable energy.

  16. Data, exergy, and energy analysis of a vertical-bore, ground-source heat pump to for domestic water heating under simulated occupancy conditions

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D; Baxter, Van D; Gehl, Anthony C

    2015-01-01

    Evidence is provided to support the view that greater than two-thirds of energy required to produce domestic hot water may be extracted from the ground which serves as renewable energy resource. The case refers to a 345 m2 research house located in Oak Ridge, Tennessee, 36.01 N 84.26 W in a mixed-humid climate with HDD of 2218 C-days (3993 F-days) and CDD of 723 C-days (1301 F-days). The house is operated under simulated occupancy conditions in which the hot water use protocol is based on the Building America Research Benchmark Definition (Hendron 2008; Hendron and Engebrecht 2010) which captures the water consumption lifestyles of the average family in the United States. The 5.275 (1.5-ton) water-to-water ground source heat pump (WW-GSHP) shared the same vertical bore with a 7.56 KW water-to-air ground source heat pump for space conditioning the same house. Energy and exergy analysis of data collected continuously over a twelve month period provide performance metrics and sources of inherent systemic inefficiencies. Data and analyses are vital to better understand how WW-GSHPs may be further improved to enable the ground to be used as a renewable energy resource.

  17. Vertical structure and physical processes of the Madden-Julian oscillation: Linking hindcast fidelity to simulated diabatic heating and moistening

    NASA Astrophysics Data System (ADS)

    Klingaman, Nicholas P.; Woolnough, Steven J.; Jiang, Xianan; Waliser, Duane; Xavier, Prince K.; Petch, Jon; Caian, Mihaela; Hannay, Cecile; Kim, Daehyun; Ma, Hsi-Yen; Merryfield, William J.; Miyakawa, Tomoki; Pritchard, Mike; Ridout, James A.; Roehrig, Romain; Shindo, Eiki; Vitart, Frederic; Wang, Hailan; Cavanaugh, Nicholas R.; Mapes, Brian E.; Shelly, Ann; Zhang, Guang J.

    2015-05-01

    Many theories for the Madden-Julian oscillation (MJO) focus on diabatic processes, particularly the evolution of vertical heating and moistening. Poor MJO performance in weather and climate models is often blamed on biases in these processes and their interactions with the large-scale circulation. We introduce one of the three components of a model evaluation project, which aims to connect MJO fidelity in models to their representations of several physical processes, focusing on diabatic heating and moistening. This component consists of 20 day hindcasts, initialized daily during two MJO events in winter 2009-2010. The 13 models exhibit a range of skill: several have accurate forecasts to 20 days lead, while others perform similarly to statistical models (8-11 days). Models that maintain the observed MJO amplitude accurately predict propagation, but not vice versa. We find no link between hindcast fidelity and the precipitation-moisture relationship, in contrast to other recent studies. There is also no relationship between models' performance and the evolution of their diabatic heating profiles with rain rate. A more robust association emerges between models' fidelity and net moistening: the highest-skill models show a clear transition from low-level moistening for light rainfall to midlevel moistening at moderate rainfall and upper level moistening for heavy rainfall. The midlevel moistening, arising from both dynamics and physics, may be most important. Accurately representing many processes may be necessary but not sufficient for capturing the MJO, which suggests that models fail to predict the MJO for a broad range of reasons and limits the possibility of finding a panacea.

  18. The Correlation of Coupled Heat and Mass Transfer Experimental Data for Vertical Falling Film Absorption

    SciTech Connect

    Keyhani, M.; Miller, W.A.

    1999-11-14

    Absorption chillers are gaining global acceptance as quality comfort cooling systems. These machines are the central chilling plants and the supply for cotnfort cooling for many large commercial buildings. Virtually all absorption chillers use lithium bromide (LiBr) and water as the absorption fluids. Water is the refrigerant. Research has shown LiBr to he one of the best absorption working fluids because it has a high affinity for water, releases water vapor at relatively low temperatures, and has a boiling point much higher than that of water. The heart of the chiller is the absorber, where a process of simultaneous heat and mass transfer occurs as the refrigerant water vapor is absorbed into a falling film of aqueous LiBr. The more water vapor absorbed into the falling film, the larger the chiller?s capacity for supporting comfort cooling. Improving the performance of the absorber leads directly to efficiency gains for the chiller. The design of an absorber is very empirical and requires experimental data. Yet design data and correlations are sparse in the open literature. The experimental data available to date have been derived at LiBr concentrations ranging from 0.30 to 0.60 mass fraction. No literature data are readily available for the design operating conditions of 0.62 and 0.64 mass fraction of LiBr and absorber pressures of 0.7 and 1.0 kPa.

  19. Characterizing fractured rock aquifers using heated Distributed Fiber-Optic Temperature Sensing to determine borehole vertical flow

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    In highly heterogeneous media, fracture network connectivity and hydraulic properties can be estimated using methods such as packer- or cross-borehole pumping-tests. Typically, measurements of hydraulic head or vertical flow in such tests are made either at a single location over time, or at a series of depths by installing a number of packers or raising or lowering a probe. We show how this often encountered monitoring problem, with current solutions sacrificing either one of temporal or spatial information, can be addressed using Distributed Temperature Sensing (DTS). Here, we electrically heat the conductive cladding materials of cables deployed in boreholes to determine the vertical flow profile. We present results from heated fiber optic cables deployed in three boreholes in a fractured rock aquifer at the much studied experimental site near Ploemeur, France, allowing detailed comparisons with alternative methods (e.g. Le Borgne et al., 2007). When submerged in water and electrically heated, the cable very rapidly reaches a steady state temperature (less than 60 seconds). The steady state temperature of the heated cable, measured using the DTS method, is then a function of the velocity of the fluid in the borehole. We find that such cables are sensitive to a wide range of fluid velocities, and thus suitable for measuring both ambient and pumped flow profiles at the Ploemeur site. The cables are then used to monitor the flow profiles during all possible configurations of: ambient flow, cross-borehole- (pumping one borehole, and observing in another), and dipole-tests (pumping one borehole, re-injection in another). Such flow data acquired using DTS may then be used for tomographic flow inversions, for instance using the approach developed by Klepikova et al., (submitted). Using the heated fiber optic method, we are able to observe the flow response during such tests in high spatial detail, and are also able to capture temporal flow dynamics occurring at the start of both the pumping and recovery phase of cross-borehole- and dipole- tests. In addition, the clear advantage of this is that by deploying a single fiber optic cable in multiple boreholes at a site, the flow profiles in all boreholes can be simultaneously measured, allowing many different pumping experiments to be conducted and monitored in a time efficient manner. Klepikova M. V., Le Borgne T., Bour O., and J-R.de Dreuzy, Inverse modelling of flow tomography experiments in fractured media, submitted to Water Resources Research. Le Borgne T., Bour O., Riley M. S., Gouze P., Pezard P.A., Belghoul A., Lods G., Le Provost R., Greswell R. B., Ellis P.A., Isakov E., and B. J. Last, Comparison of alternative methodologies for identifying and characterizing preferential flow paths in heterogeneous aquifers. Journal of Hydrology 2007, 345, 134-148.

  20. Heat flux measurement from vertical temperature profile and thermal infrared imagery in low-flux fumarolic zones

    NASA Astrophysics Data System (ADS)

    Gaudin, Damien; Finizola, Anthony; Beauducel, François; Brothelande, Elodie; Allemand, Pascal; Delacourt, Christophe; Delcher, Eric; Peltier, Aline

    2014-05-01

    Hydrothermal systems are associated to most of the dormant volcanoes. Heat is transported by steam from the hot magma body in the connected porosity and the fissures of the rock to the surface. If the flux is low enough (<500 W/m²), the steam mainly condensates in the soil close to surface, and a significant proportion of the heat is transported to the surface by conduction, producing a gradient of temperature and a thermal anomaly detectable at the surface. Detecting and monitoring these fluxes is crucial for hazard management, since it reflects the state of the magma body in depth. In order to quantify this flux two methods are considered. First, a vertical profile of temperature is measured by a series of thermocouples, and the conducted flux is estimated thanks to the Fourier law. Secondly, a more recent method uses the thermal infrared imagery to monitor the surface temperature anomaly (STA) between the studied zone and an equivalent zone not affected by the geothermal flux. The heat flux from the soil to the atmosphere is computed as the sum of (1) the radiative flux, (2) the sensible flux and (3) the residual steam flux. These two methods are complementary and have an equivalent uncertainty of approximately 20%, which would allow to track the major changes in the hydrothermal system. However, the surface and sub-surface temperatures are strongly influenced by the climate. For instance, it has been widely demonstrated that the surface temperature dramatically decreases after a rainfall. In order to estimate the reliability of the measurements, a numerical model simulating the evolution of the subsurface temperature in low flux fumarolic zone has been built. In depth, the heat can be transported either by conduction, or by the rising steam, or by condensed water. In surface, both the radiative flux and the sensible flux (convection of the atmosphere) are taken into account. This model allows to estimate the changes of temperature due to a variation of solar illumination, wind, or rainfalls. It has been successfully tested during 5 months with a permanent station built on the Ty fault on La Soufrière volcano (Guadeloupe, Lesser Antilles). Results show that the diurnal cycle has a significant influence on the temperature up to ca. 30 cm depth, hindering the use of the thermal gradient in this zone, while the STA has a negligible variation. Rain has a more dramatic influence: the surface temperature and the STA are significantly affected, even for small rains. The model shows that the drop of temperature and the affected thickness are mainly controlled by the amount of rain, while the relaxation time is primarily a function of the heat flux. These results have strong implications in the interpretation and the reliability of the temperature surveys, and could be used to correct them from the climate fluctuations.

  1. Transient conjugate free convection from a vertical flat plate in a porous medium subjected to a sudden change in surface heat flux

    E-print Network

    Shu, Jian-Jun

    2015-01-01

    The paper presents a theoretical study using the Karman-Pohlhausen method for describing the transient heat exchange between the boundary-layer free convection and a vertical flat plate embedded in a porous medium. The unsteady behavior is developed after the generation of an impulsive heat flux step at the right-hand side of the plate. Two cases are considered according to whether the plate has a finite thickness or no thickness. The time and space evolution of the interface temperature is evidenced.

  2. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    NASA Astrophysics Data System (ADS)

    Hollmann, E. M.; Commaux, N.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Parks, P. B.; Shiraki, D.

    2015-10-01

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma edge magnetic perturbation is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Clear indications of plasma infra-red (IR) emission are observed both before and during the disruptions. This IR emission can affect calculation of disruption heat loads; here, the time decay of post-disruption IR signals is used to correct for this effect.

  3. Nonlinear radiation heat transfer effects in the natural convective boundary layer flow of nanofluid past a vertical plate: a numerical study.

    PubMed

    Mustafa, Meraj; Mushtaq, Ammar; Hayat, Tasawar; Ahmad, Bashir

    2014-01-01

    The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge-Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter. PMID:25251242

  4. Nonlinear Radiation Heat Transfer Effects in the Natural Convective Boundary Layer Flow of Nanofluid Past a Vertical Plate: A Numerical Study

    PubMed Central

    Mustafa, Meraj; Mushtaq, Ammar; Hayat, Tasawar; Ahmad, Bashir

    2014-01-01

    The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge–Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter. PMID:25251242

  5. The effect of transpiration on coupled heat and mass transfer in mixed convection over a vertical plate embedded in a saturated porous medium

    SciTech Connect

    Yih, K.A.

    1997-03-01

    Effect of transpiration velocity on the heat and mass transfer characteristics of mixed convection about a permeable vertical plate embedded in a saturated porous medium under the coupled effects of thermal and mass diffusion is numerically analyzed. The plate is maintained at a uniform temperature and species concentration with constant transpiration velocity. The transformed governing equations are solved by Keller box method. Numerical results for the local Nusselt number and local Sherwood number are presented. In general, it has been found for thermally assisted flow that the local surface heat and mass transfer rates increase owing to suction of fluid. This trend reversed for blowing of fluid. It is apparent that the Lewis number has a pronounced effect on the local Sherwood number than it does on the local Nusselt number. Increasing the Lewis number decreases (increases) the local heat (mass) transfer rate.

  6. Excellent scalability including self-heating phenomena of vertical-channel field-effect-diode type capacitor-less one transistor dynamic random access memory cell

    NASA Astrophysics Data System (ADS)

    Imamoto, Takuya; Endoh, Tetsuo

    2014-01-01

    The scalability study and the impact of the self-heating effect (SHE) on memory operation of the bulk vertical-channel field effect diode (FED) type capacitorless one transistor (1T) dynamic random access memory (DRAM) cell are investigated via device simulator for the first time. The vertical-channel FED type 1T-DRAM cell shows the excellent hold characteristics (100 ms at 358 K of ambient temperature) with large enough read current margin (1 µA/cell) even when silicon pillar diameter (D) is scaled down from 20 to 12 nm. It is also shown that by employing the vertical-channel FED type, maximum lattice temperature in the memory cell due to SHE (T_{\\text{L}}^{\\text{Max}}) can be suppressed to a negligible small value and only reach 300.6 from 300 K ambient temperature due to the low lateral electric field, while the vertical-channel bipolar junction transistor (BJT) type 1T-DRAM shows significant SHE (T_{\\text{L}}^{\\text{Max}} = 330.6 K). Moreover, this excellent thermal characteristic can be maintained even when D is scaled down from 20 to 12 nm.

  7. The influence of heat transfer and magnetic field on peristaltic transport of a Newtonian fluid in a vertical annulus: Application of an endoscope

    NASA Astrophysics Data System (ADS)

    Mekheimer, Kh. S.; Abd elmaboud, Y.

    2008-03-01

    This Letter discusses the influence of heat transfer and magnetic field on the peristaltic flow of Newtonian fluid in a vertical annulus under a zero Reynolds number and long wavelength approximation. The inner tube is uniform, rigid, while the outer tube has a sinusoidal wave traveling down its wall. The flow is investigated in a wave frame of reference moving with velocity of the wave. Numerical calculations are carried out for the pressure rise and frictional forces. The features of the flow characteristics are analyzed by plotting graphs and discussed in detail.

  8. On the importance of cavity-length and heat dissipation in GaN-based vertical-cavity surface-emitting lasers

    PubMed Central

    Liu, W. J.; Hu, X. L.; Ying, L. Y.; Chen, S. Q.; Zhang, J. Y.; Akiyama, H.; Cai, Z. P.; Zhang, B. P.

    2015-01-01

    Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated. The cavity lengths were well controlled by employing etching with inductively coupled plasma and chemical mechanical polishing. It was found that the lasing characteristics including threshold, slope efficiency and spontaneous emission coupling factor were substantially improved with reducing the cavity length. In comparison with the device pumped by a 400?nm pulsed laser, the lasing spectrum was featured by a red shift and simultaneous broadening with increasing the pumping energy of a 355?nm pulsed laser. Moreover, the lasing threshold was much higher when pumped by a 355?nm pulsed laser. These were explained by taking into account of the significant heating effect under 355?nm pumping. Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs. PMID:25873327

  9. On the importance of cavity-length and heat dissipation in GaN-based vertical-cavity surface-emitting lasers.

    PubMed

    Liu, W J; Hu, X L; Ying, L Y; Chen, S Q; Zhang, J Y; Akiyama, H; Cai, Z P; Zhang, B P

    2015-01-01

    Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated. The cavity lengths were well controlled by employing etching with inductively coupled plasma and chemical mechanical polishing. It was found that the lasing characteristics including threshold, slope efficiency and spontaneous emission coupling factor were substantially improved with reducing the cavity length. In comparison with the device pumped by a 400?nm pulsed laser, the lasing spectrum was featured by a red shift and simultaneous broadening with increasing the pumping energy of a 355?nm pulsed laser. Moreover, the lasing threshold was much higher when pumped by a 355?nm pulsed laser. These were explained by taking into account of the significant heating effect under 355?nm pumping. Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs. PMID:25873327

  10. Combined effect of buoyancy force and Navier slip on MHD flow of a nanofluid over a convectively heated vertical porous plate.

    PubMed

    Mutuku-Njane, Winifred Nduku; Makinde, Oluwole Daniel

    2013-01-01

    We examine the effect of magnetic field on boundary layer flow of an incompressible electrically conducting water-based nanofluids past a convectively heated vertical porous plate with Navier slip boundary condition. A suitable similarity transformation is employed to reduce the governing partial differential equations into nonlinear ordinary differential equations, which are solved numerically by employing fourth-order Runge-Kutta with a shooting technique. Three different water-based nanofluids containing copper (Cu), aluminium oxide (Al2O3), and titanium dioxide (TiO2) are taken into consideration. Graphical results are presented and discussed quantitatively with respect to the influence of pertinent parameters, such as solid volume fraction of nanoparticles (?), magnetic field parameter (Ha), buoyancy effect (Gr), Eckert number (Ec), suction/injection parameter (f w ), Biot number (Bi), and slip parameter ( ? ), on the dimensionless velocity, temperature, skin friction coefficient, and heat transfer rate. PMID:24222749

  11. Comparison of air-launched and ground-coupled configurations of SFCW GPR in time, frequency and wavelet domain

    NASA Astrophysics Data System (ADS)

    Van De Vijver, Ellen; De Pue, Jan; Cornelis, Wim; Van Meirvenne, Marc

    2015-04-01

    A stepped frequency continuous wave (SFCW) ground penetrating radar (GPR) system produces waveforms consisting of a sequence of sine waves with linearly increasing frequency. By adopting a wide frequency bandwidth, SFCW GPR systems offer an optimal resolution at each achievable measurement depth. Furthermore, these systems anticipate an improved penetration depth and signal-to-noise ratio (SNR) as compared to time-domain impulse GPRs, because energy is focused in one single frequency at a time and the phase and amplitude of the reflected signal is recorded for each discrete frequency step. However, the search for the optimal practical implementation of SFCW GPR technology to fulfil these theoretical advantages is still ongoing. In this study we compare the performance of a SFCW GPR system for air-launched and ground-coupled antenna configurations. The first is represented by a 3d-Radar Geoscope GS3F system operated with a V1213 antenna array. This array contains 7 transmitting and 7 receiving antennae resulting in 13 measurement channels at a spacing of 0.075 m and providing a total scan width of 0.975 m. The ground-coupled configuration is represented by 3d-Radar's latest-generation SFCW system, GeoScope Mk IV, operated with a DXG1212 antenna array. With 6 transmitting and 5 receiving antennae this array provides 12 measurement channels and an effective scan width of 0.9 m. Both systems were tested on several sites representative of various application environments, including a test site with different road specimens (Belgian Road Research Centre) and two test areas in different agricultural fields in Flanders, Belgium. For each test, data acquisition was performed using the full available frequency bandwidth of the systems (50 to 3000 MHz). Other acquisition parameters such as the frequency step and dwell time were varied in different tests. Analyzing the data of the different tests in time, frequency and wavelet domain allows to evaluate different performance aspects of the air-launched and ground-coupled configurations such as acquisition speed, measurement resolution, SNR and penetration depth. Based on this analysis, we highlight the advantages and disadvantages of the different SFCW GPR configurations in different application environments. The authors thank Colette Grégoire and Carl Van Geem of the Belgian Road Research Centre for the collaboration on the road test site. This work is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

  12. Unsteady hydromagnetic flow of dusty fluid and heat transfer over a vertical stretching sheet with thermal radiation

    NASA Astrophysics Data System (ADS)

    Isa, Sharena Mohamad; Ali, Anati

    2015-10-01

    In this paper, the hydromagnetic flow of dusty fluid over a vertical stretching sheet with thermal radiation is investigated. The governing partial differential equations are reduced to nonlinear ordinary differential equations using similarity transformation. These nonlinear ordinary differential equations are solved numerically using Runge-Kutta Fehlberg fourth-fifth order method (RKF45 Method). The behavior of velocity and temperature profiles of hydromagnetic fluid flow of dusty fluid is analyzed and discussed for different parameters of interest such as unsteady parameter, fluid-particle interaction parameter, the magnetic parameter, radiation parameter and Prandtl number on the flow.

  13. Ground-coupled acoustic airwaves from Mount St. Helens provide constraints on the May 18, 1980 eruption

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey B.; Malone, Stephen D.

    2007-06-01

    The May 18, 1980 Mount St. Helens eruption perturbed the atmosphere and generated atmosphere-to-ground coupled airwaves, which were recorded on at least 35 seismometers operated by the Pacific Northwest Seismograph Network (PNSN). From 102 distinct travel time picks we identify coherent airwaves crossing Washington State primarily to the north and east of the volcano. The travel time curves provide evidence for both stratospheric refractions (at 200 to 300 km from the volcano) as well as probable thermospheric refractions (at 100 to 350 km). The very few first-hand reports of audible volcano sounds within about 80 km of the volcano coincide with a general absence of ground-coupled acoustic arrivals registered within about 100 km and are attributed to upward refraction of sound waves. From the coherent refracted airwave arrivals, we identify at least four distinct sources which we infer to originate 10 s, 114 s, ˜ 180 s and 319 s after the onset of an 8:32:11 PDT landslide. The first of these sources is attributed to resultant depressurization and explosion of the cryptodome. Most of the subsequent arrivals also appear to be coincident with a source located at or near the presumed volcanic conduit, but at least one of the later arrivals suggests an epicenter displaced about 9 km to the northwest of the vent. This dislocation is compatible with the direction of the sector collapse and lateral blast. We speculate that this concussion corresponds to a northern explosion event associated with hot cryptodome entering the Toutle River Valley.

  14. Hydrodynamics and heat transfer of a water flow with supercritical parameters in a vertical assembly of fuel elements

    NASA Astrophysics Data System (ADS)

    Avramenko, A. A.; Kondrat?eva, E. A.; Kovetskaya, M. M.; Tyrinov, A. I.

    2013-07-01

    Water flow in a hexahedral seven-rod fuel assembly at supercritical pressure has been modeled. Consideration has been given to nonstationary regimes of this flow in the case of a stepwise increase in the heat flux on the fuelelement surface and of a drop in the flow rate of the coolant at entry. Numerical investigation of the processes of hydrodynamics and heat transfer was based on the RNG k-? turbulence model; equations of state of the IF-97 formulation were used. Hydrodynamic and thermal characteristics of the coolant flow in the indicated assembly have been obtained as a result of the modeling.

  15. Exergy Analysis of a Two-Stage Ground Source Heat Pump with a Vertical Bore for Residential Space Conditioning under Simulated Occupancy

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D; Baxter, Van D; Gehl, Anthony C

    2015-01-01

    This twelve-month field study analyzes the performance of a 7.56W (2.16- ton) water-to-air-ground source heat pump (WA-GSHP) to satisfy domestic space conditioning loads in a 253 m2 house in a mixed-humid climate in the United States. The practical feasibility of using the ground as a source of renewable energy is clearly demonstrated. Better than 75% of the energy needed for space heating was extracted from the ground. The average monthly electricity consumption for space conditioning was only 40 kWh at summer and winter thermostat set points of 24.4oC and 21.7oC, respectively. The WA-GSHP shared the same 94.5 m vertical bore ground loop with a separate water-to-water ground-source heat pump (WW-GSHP) for meeting domestic hot water needs in the same house. Sources of systemic irreversibility, the main cause of lost work are identified using Exergy and energy analysis. Quantifying the sources of Exergy and energy losses is essential for further systemic improvements. The research findings suggest that the WA-GSHPs are a practical and viable technology to reduce primary energy consumption and greenhouse gas emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 targets of using renewable energy resources.

  16. Heat Transfer Analysis of MHD Thin Film Flow of an Unsteady Second Grade Fluid Past a Vertical Oscillating Belt

    PubMed Central

    Gul, Taza; Islam, Saeed; Shah, Rehan Ali; Khan, Ilyas; Khalid, Asma; Shafie, Sharidan

    2014-01-01

    This article aims to study the thin film layer flowing on a vertical oscillating belt. The flow is considered to satisfy the constitutive equation of unsteady second grade fluid. The governing equation for velocity and temperature fields with subjected initial and boundary conditions are solved by two analytical techniques namely Adomian Decomposition Method (ADM) and Optimal Homotopy Asymptotic Method (OHAM). The comparisons of ADM and OHAM solutions for velocity and temperature fields are shown numerically and graphically for both the lift and drainage problems. It is found that both these solutions are identical. In order to understand the physical behavior of the embedded parameters such as Stock number, frequency parameter, magnetic parameter, Brinkman number and Prandtl number, the analytical results are plotted graphically and discussed. PMID:25383797

  17. Experimental investigation on heat transfer coefficient during upward flow condensation of R410A in vertical smooth tubes

    NASA Astrophysics Data System (ADS)

    Yang, Yunxiao; Jia, Li

    2015-04-01

    This paper presents an experimental investigation on condensation of R410A upward flow in vertical tubes with the same inner diameter of 8.02mm and different lengths of 300 mm, 400 mm, 500 mm and 600mm. Condensation experiments were performed at mass fluxes of 103-490 kg m-2s-1. The saturation temperatures of experimental condition were 31°C, 38°C and 48°C, alternatively. The average vapor quality in the test section is between 0.91 and 0.98. The effects of tube length, mass flux and condensation temperature on condensation were discussed. Four correlations used for the upward flow condensation were compared with the experimental data obtained from various experimental conditions. A modified correlation was proposed within a ±15% deviation range.

  18. Steady and oscillatory laminar opposing mixed convection in a vertical channel of finite length subjected to symmetrical isothermal discrete heat sources

    NASA Astrophysics Data System (ADS)

    Martínez-Suástegui, Lorenzo; Treviño, César; Cajas, Juan Carlos

    2015-06-01

    Transient laminar opposing mixed convection in a gravity driven downward flow confined inside a vertical rectangular channel has been investigated, with both walls suddenly subjected to symmetrical isothermal heat sources over a finite portion of the channel walls. The unsteady two-dimensional Navier-Stokes and energy equations have been solved numerically for a wide parametric set. Studies are carried out for Reynolds numbers of 100 and 200 and several values of buoyancy strength or Richardson number. The effect of Reynolds number and opposing buoyancy on the temporal evolution of the overall flow structure, temperature field, and Nusselt number from the heated surfaces is investigated using fixed geometrical parameters and considering heat losses to the channel walls. In this parameter space, for a given Reynolds number and relatively small values of the buoyancy parameter, the transient process leads to a final symmetric or asymmetric steady-state. However, as the value of buoyancy strength increases, the flow and temperature fields become more complex and an oscillatory flow with a fundamental frequency sets in when a critical value of the Richardson number is reached. Numerical predictions show that the critical value of the Richardson number between the two regimes strongly depends on the value of the Reynolds number, and the time scales, natural frequencies, and phase-space portraits of flow oscillation are presented and discussed in detail. Stability of the symmetric response has been analyzed. The results include the effects of Prandtl number and heat losses to the channel walls on the evolution of the final flow and thermal responses.

  19. An analytical study on heat and mass transfer for ammonia-water system in a vertical falling-film type of absorber and generator

    NASA Astrophysics Data System (ADS)

    Honda, Katsumi; Matsuda, Akira

    A numerical analysis on simultaneous heat and mass transfer for ammonia-water air-conditioning with a vertical falling-film type of absorber and generator was performed by the one-dimensional difference method which takes into account only the change of flow direction. In the calculation, the geometries of absorber/generator and the temperature conditions were taken like as those in our previous works for water-lithium bromide system. Therefore, the liquid and vapor concentrations ranged 53-55 and 99-l00mass%NH3, respectively. The ratio of the liquid mass flow rate to the vapor mass flow rate, L/V, ranged up to 18000. For these thermal conditions, it was found that the vapor-phase mass transfer resistance is negligibly small, and the absorption/generation rates are almost constant regardless of the vapor flow rate, but increase with increasing liquid flow rate. It was also found that the calculated values of heat fluxes in the absorber/generator for ammonia-water system are equivalent or superior to those for water-lithium bromide system.

  20. Vertical structure of aerosols and clouds in the atmospheres of Uranus and Neptune: Implications for their heat budgets

    NASA Technical Reports Server (NTRS)

    Pollack, James B.; Rages, Kathy; Bergstralh, Jay; Baines, Kevin; Wenkert, Daniel; Danielson, G. Edward

    1986-01-01

    Models possessing an upper haze layer of finite optical depth and a lower cloud layer of infinite optical depth at discrete altitudes are used to bound the wavelength-averaged phase integrals and bolometric albedos of Uranus and Neptune. The models differ in the assumed value of the particles single scattering phase function and the wavelength dependence of the haze optical depth. A range of phase functions, from the isotropic to those characterizing Titan, Jupiter, and Saturn atmosphere particles, are discussed. The results obtained imply that the meteorological regimes in the observable atmospheres of Uranus and Neptune may differ considerably; internal heat flux could play a much more important role for Neptune than for Uranus.

  1. The role of diabatic heating, torques and stabilities in forcing the radial-vertical circulation within cyclones part ii: case study of extratropical and tropical cyclones

    NASA Astrophysics Data System (ADS)

    Yuan, Zhuojian; Johnson, Donald R.

    1998-12-01

    Utilizing Eliassen's concepts, the forcing of the isentropic azimuthally-averaged mass-weighted radial-vertical circulation by diabatic heating and torques within an extratropical cyclone and a typhoon was studied through numerical simulations based on the linear diagnostic equation derived previously. The structure of the forcing associated with diabatic heating and torques was determined from quasi-Lagrangian diagnostic analyses of actual case studies. The two cyclones studied were the Ohio extratropical cyclone of 25-27 January 1978 and typhoon Nancy of 18-23 September 1979. The Ohio cyclone, which formed over the Gulf Coast and moved through Ohio and eastern Michigan, was one of the most intense storms with blizzard conditions to ever occur in this region. Typhoon Nancy which occurred over the South China Sea during the FGGE year was selected since relatively high quality assimilated data were available. Within the Ohio cyclone, the dominant internal processes forcing the mean circulation with embedded relatively strong hydrodynamic stability were the pressure torque associated with baroclinic (asymmetric) structure and the horizontal eddy angular momentum transport associated with the typical S-shaped thermal and wind structures of self-development. Within typhoon Nancy, the dominant internal process forcing the mean circulation with embedded weak hydrodynamic stability was the latent heat release. This analysis shows that the simulated azimuthally-averaged mass-weighted radial motions within these two cyclones agree quite well with the “ observed? azimuthally-averaged mass-weighted radial motions. This isentropic numerical study also provides insight into the relatively important internal forcing processes and the trade off between forcing and stability within both extratropical and tropical cyclones.

  2. Retrieving latent heating vertical structure from cloud and precipitation profiles—Part II: Deep convective and stratiform rain processes

    NASA Astrophysics Data System (ADS)

    Li, Rui; Min, Qilong; Wu, Xiaoqing; Fu, Yunfei

    2013-06-01

    An exploratory study on physical based latent heat (LH) retrieval algorithm is conducted by parameterizing the physical linkages between observed cloud and precipitation profiles to the major processes of phase change of atmospheric water. Specifically, rain is segregated into three rain types: warm, convective, and stratiform rain, based on their dynamical and thermodynamical characteristics. As the second of series, both convective and stratiform rain LH algorithms are presented and evaluated here. For convective and stratiform rain, the major LH-related microphysical processes including condensation, deposition, evaporation, sublimation, and freezing-melting are parameterized with the aid of Cloud Resolving Model (CRM) simulations. The condensation and deposition processes are parameterized in terms of rain formation processes through the precipitation formation theory. LH associated with the freezing-melting process is relatively small and is assumed to be a fraction of total condensation and deposition LH. The evaporation and sublimation processes are parameterized for three unsaturated scenarios: rain out of the cloud body, clouds at cloud boundary and clouds and rain in downdraft region. The evaluation or self-consistency test indicates the retrievals capture the major features of LH profiles and reproduce the double peaks at right altitudes. The LH products are applicable at various stages of cloud system life cycle for high-resolution models, as well as for large-scale climate models.

  3. Effects of Surface Heat Flux Anomalies on Stratification, Convective Growth and Vertical Transport within the Saharan Boundary Layer

    NASA Astrophysics Data System (ADS)

    Huang, Qian; Marsham, John; Parker, Doug; Tian, Wenshou; Grams, Christian; Cuesta, Juan; Flamant, Cyrille

    2010-05-01

    The very large surface sensible and very low latent heat fluxes in the Sahara desert lead to its unusually deep, almost dry-adiabatic boundary layer, that often reaches 6 km. This is often observed to consist of a shallow convective boundary layer (CBL) with a near neutral residual layer above (the Saharan Residual Layer, or SRL). It has been shown that the SRL can be both spatially extensive and persist throughout the day. Multiple near-neutral layers are frequently observed within the SRL, or within the SAL, each with a different water vapour and/or dust content, and each separated by a weak lid (e.g., Figure 1). A local maximum in not only relative humidity, but also water vapour mixing ratio (WVMR) is often seen at the top of the SRL or SAL. This structure suggests that in some locations, at some times, convection from the surface is mixing the full depth of the Saharan boundary layer, but in most locations and times this is not the case, and varying horizontal advection leads to the multiple layering observed. During the GERBILS (GERB Intercomparison of Longwave and Shortwave radiation) field campaign in the Sahara, coherent couplings were observed between surface albedo, CBL air temeperatures and CBL winds. Using two cases based on observations from GERBILS, large eddy model (LEM) simulations have been used to investigate the effects of surface flux anomalies on the growth of the summertime Saharan CBL into the Saharan Residual layer (SRL) above, and transport from the CBL into the SRL. Hot surface anomalies generated updraughts and convergence in the CBL that increased transport from the CBL into the SRL. The induced subsidence in regions away from the anomalies inhibited growth of the CBL there. If the domain-averaged surface fluxes were kept constant this led to a shallower, cooler CBL. If fluxes outside the anomalies were kept constant, so that stronger anomalies led to increased domain-averaged fluxes, this gave a warmer, shallower CBL. These effects were larger for wider, stronger anomalies, with low winds. These LEM simulations show that mesoscale variations in surface fluxes can contribute to both inhibiting the growth of the Saharan CBL into the SRL, and generating layerings within the SRL.

  4. Thermal conductivity of cementitious grouts for geothermal heat pumps. Progress report FY 1997

    SciTech Connect

    Allan, M.L.

    1997-11-01

    Grout is used to seal the annulus between the borehole and heat exchanger loops in vertical geothermal (ground coupled, ground source, GeoExchange) heat pump systems. The grout provides a heat transfer medium between the heat exchanger and surrounding formation, controls groundwater movement and prevents contamination of water supply. Enhanced heat pump coefficient of performance (COP) and reduced up-front loop installation costs can be achieved through optimization of the grout thermal conductivity. The objective of the work reported was to characterize thermal conductivity and other pertinent properties of conventional and filled cementitious grouts. Cost analysis and calculations of the reduction in heat exchanger length that could be achieved with such grouts were performed by the University of Alabama. Two strategies to enhance the thermal conductivity of cementitious grouts were used simultaneously. The first of these was to incorporate high thermal conductivity filler in the grout formulations. Based on previous tests (Allan and Kavanaugh, in preparation), silica sand was selected as a suitable filler. The second strategy was to reduce the water content of the grout mix. By lowering the water/cement ratio, the porosity of the hardened grout is decreased. This results in higher thermal conductivity. Lowering the water/cement ratio also improves such properties as permeability, strength, and durability. The addition of a liquid superplasticizer (high range water reducer) to the grout mixes enabled reduction of water/cement ratio while retaining pumpability. Superplasticizers are commonly used in the concrete and grouting industry to improve rheological properties.

  5. Analysis of hyperbolic signatures from small discontinuities using an UWB ground-coupled radar: FDTD simulations and field experiments

    NASA Astrophysics Data System (ADS)

    Sagnard, Florence; Tebchrany, Elias; Baltazart, Vincent

    2013-04-01

    Ground penetrating radar (GPR) is a well-known non-destructive technique based on electromagnetic wave propagation that is able to detect by reflection or scattering of waves dielectric discontinuities in the underground. Our application is mainly concerned with civil engineering to perform supervision, inventory, and soil characterization. Because the air-coupled radar suffers from a significant reflection at the ground interface that reduces energy transfer of electromagnetic radiation in the sub-surface and penetration depth, we have developed an ultra-wide band (UWB) ground-coupled radar made of a pair of partially shielded compact planar bowtie slot antennas. As the antenna dimension (36*23 cm2) is close to the A4 sheet size, the maturity of the microstrip technology has allowed to design a particular geometry on the FR4 substrate (h=1.5 mm) which is able to operate at frequencies from 460 MHz to beyond 4 GHz in air. Contrary to a commercial GPR where details on antenna design are not available, it appears here possible to know and control the radiation characteristics and develop full-wave FDTD modeling that can represent field experiments for comparisons and analyses. The objective of this work is to improve, by means of a parametric study, the knowledge of physical phenomena involved in dielectric polarization when waves interact with buried discontinuities and particularly cracks, pipes, delaminations that can be distinguished by their shape, size, dielectric contrast with the surrounding medium, orientation relative to the electric field… Thus, we have first characterized by FDTD modeling and field measurements in a wet sand the radar link in two perpendicular polarizations (parallel and mirror) in the presence of a common soil (epsilon'=5.5, sigma=0.01 S/m) considering variable offsets. Afterwards, we have studied and analyzed the hyperbola signatures generated by the presence of buried canonical objects (pipes, strips) with several dielectric properties (dielectric and conductive) in a wet sand with a small lateral dimension (less than 20 mm) in both polarizations. Comparisons with FDTD simulations including the detailed structure of the antennas appear promising as they have allowed to interpret the measurements and take advantage of signal polarization to extract information associated with the discontinuities. After cluster removal using classical data processing (SVD, median value substraction…), the analytical model based on the ray theory and including the antenna size has allowed to first analyze the hyperbola responses. This study is supposed to prepare the development of data processing associated with B-scans to extract quantitative information from the electromagnetic probing of the subsurface in a very large frequency band.

  6. THE VERTICAL

    NASA Technical Reports Server (NTRS)

    Albert, Stephen L.; Spencer, Jeffrey B.

    1994-01-01

    'THE VERTICAL' computer keyboard is designed to address critical factors which contribute to Repetitive Motion Injuries (RMI) (including Carpal Tunnel Syndrome) in association with computer keyboard usage. This keyboard splits the standard QWERTY design into two halves and positions each half 90 degrees from the desk. In order to access a computer correctly. 'THE VERTICAL' requires users to position their bodies in optimal alignment with the keyboard. The orthopaedically neutral forearm position (with hands palms-in and thumbs-up) reduces nerve compression in the forearm. The vertically arranged keypad halves ameliorate onset occurrence of keyboard-associated RMI. By utilizing visually-reference mirrored mylar surfaces adjustable to the user's eye, the user is able to readily reference any key indicia (reversed) just as they would on a conventional keyboard. Transverse adjustability substantially reduces cumulative musculoskeletal discomfort in the shoulders. 'THE VERTICAL' eliminates the need for an exterior mouse by offering a convenient finger-accessible curser control while the hands remain in the vertically neutral position. The potential commercial application for 'THE VERTICAL' is enormous since the product can effect every person who uses a computer anywhere in the world. Employers and their insurance carriers are spending hundreds of millions of dollars per year as a result of RMI. This keyboard will reduce the risk.

  7. Measured water heating performance of a vertical-bore water-to-water ground source heat pump (WW-GSHP) for domestic water heating over twelve months under simulated occupancy loads

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D; Baxter, Van D; Gehl, Anthony C

    2014-01-01

    This paper presents monthly performance metrics of a 5.275 kW (1.5 ton) WW-GSHP providing 227 L day-1 domestic hot water at 49 C. Daily water use is simulated as stipulated in the Building America Research Benchmark Definition capturing the living habits of the average U.S household. The 94.5m vertical-bore ground loop is shared with a separate GSHP for space conditioning the 251m2 residential home. Data on entering water temperatures, energy extracted from the ground, delivered energy, compressor electricity use, COP, WW-GSHP run times, and the impact of fan and pump energy consumption on efficiency are presented for each month. Factors influencing performance metrics are highlighted.

  8. VERTICAL GARDEN DIY CHECKLIST

    E-print Network

    Peters, Richard

    VERTICAL GARDEN DIY CHECKLIST Vertical greenery is not a new concept; it dates back thousands-growingvarietiesbecome established. Theneedforpermissionfromcouncil, strataetc. #12;VERTICAL GARDEN DIY CHECKLIST THE PLAN

  9. Variable viscosity effect on free convection of a non-Newtonian power-law fluid over a vertical cone in a porous medium with variable heat flux

    NASA Astrophysics Data System (ADS)

    Mahmoud, M. A. A.

    2011-01-01

    The effect of variable viscosity on the free-convection boundary layer over a permeable vertical cone in a porous medium saturated with non-Newtonian power-law fluid has been studied numerically. The governing equations describing the problem are transformed into a system of nonlinear ordinary differential equations by using a similarity transformation, which is solved numerically using the Chebyshev spectral method. The effects of the power-law index, blowing/suction parameter and the viscosity parameter on the temperature profiles and the local Nusselt number are discussed.

  10. Ground Loops for Heat Pumps and Refrigeration 

    E-print Network

    Braud, H. J.

    1986-01-01

    water temperature limits increase the length and cost for the ground loop. GROUND LOOP DESIGN A significant contribution to the knowledge of ground-coupled heat pump design is the new ASHRAE designldata manual by Bose, Parker and McQuistion, (1985... applications. mechanical equipment runs many hours more than in residential. Conductance values for long term operation have been reported by Psrtin (1981). Bose et el. (1985). Braud et al. (1983). and Klirnkowski (1986). Values are summarized in Table 1...

  11. Measurement of axially varying nonequilibrium in post-critical-heat-flux boiling in a vertical tube. Volume 1. Main report and Appendices A-D

    SciTech Connect

    Evans, D.G.; Webb, S.W.; Chen, J.C.

    1983-06-01

    To supplement the very limited steady-state data available, experiments have been run with quench fronts propagating slowly up into a tubular test section and measurements of all heat flux, wall temperature, and nonequilibrium vapor temperature as functions of distance beyond the quench front were obtained. Since the time required for the quench front to propagate a few millimeters corresponded to many fluid residence-time, transient convective heat tranfer theory indicates that the thermal data thus obtained are quasi-steady state. The significant experimental findings indicates a zone of two-phase fluid in thermodynamic equilibrium near the CHF location where the vaporization source intensity (GAMMA) is relatively high. This is followed by a far zone of rapidly developing non-thermodynamic equilibrium two-phase fluid where the source intensity drops off to a relatively low magnitude.

  12. Hybrid Heat Pumps Using Selective Water Sorbents (SWS)

    SciTech Connect

    Ally, M. R.

    2006-11-30

    The development of the ground-coupled and air-coupled Heating Ventilation and Air-Conditioning (HVAC) system is essential in meeting the goals of Zero Energy Houses (ZEH), a viable concept vigorously pursued under DOE sponsorship. ORNL has a large Habitat for Humanity complex in Lenoir City where modem buildings technology is incorporated on a continual basis. This house of the future is planned for lower and middle income families in the 21st century. The work undertaken in this CRADA is an integral part of meeting DOE's objectives in the Building America program. SWS technology is a prime candidate for reducing the footprint, cost and improve the performance of ground-coupled heat pumps. The efficacy of this technique to exchange energy with the ground is a topic of immense interest to DOE, builders and HVAC equipment manufacturers. If successful, the SWS concept will become part of a packaged ZEH kit for affordable and high-end houses. Lennox Industries entered into a CRADA with Oak Ridge National Laboratory in November 2004. Lennox, Inc. agreed to explore ways of using Selective Water Sorbent materials to boost the efficiency of air-coupled heat pumps whereas ORNL concentrated on ground-coupled applications. Lennox supplied ORNL with heat exchangers and heat pump equipment for use at ORNL's Habitat for Humanity site in Lenoir City, Tennessee. Lennox is focused upon air-coupled applications of SWS materials at the Product Development and Research Center in Carrollton, TX.

  13. Vertical constituent transport in the mesosphere

    NASA Technical Reports Server (NTRS)

    Strobel, Darrell F.; Summers, Michael E.; Bevilacqua, Richard M.; Deland, Matthew T.; Allen, Mark

    1987-01-01

    Ground-based microwave spectroscopy measurements of mesospheric CO and H2O vertical mixing ratio profiles are used to infer vertical mixing rates in the upper mesosphere. The CO and H2O data consistently imply vertical eddy diffusion coefficients in the 70- to 85-km region of 100,000-200,000 sq cm/s during spring through summer at midlatidues. Although chemical acceleration of vertical transport is substantial for O and O3, below the mesopause, the divergences of their associated fluxes are modest, with at most a factor of 2 effect on the concentrations of O and O3 for measured variability in gravity wave activity. Comparison of Solar Mesosphere Explorer (SME) O3 data with model results reinforces the conclusions of slow vertical mixing in the upper mesosphere as a consequence of the reduced HO(x) catalytic loss of odd oxygen. The changes in chemical rate constants recommended by Rusch and Eckman (1985), in conjunction with slow vertical mixing, yield good agreement with SME O3 data. The slow vertical mixing deduced in this study is consistent with upper limits obtained from studies of the mesospheric heat budget and could be construed as evidence for an advectively controlled mesosphere. A comparison of the vertical eddy diffusion coefficients for momentum stresses, constituent transport, and heat transport suggests that the eddy Prandtl number must be of order 10.

  14. Impacts of Soil and Pipe Thermal Conductivity on Performance of Horizontal Pipe in a Ground-source Heat Pump 

    E-print Network

    Song, Y.; Yao, Y.; Na, W.

    2006-01-01

    .75~26.25% PP-R 26.79 13.45% PB 26.57 12.53% PAP 29.37 24.38% REFERENCES [1] Bose J E, Parker J D. Ground -coupled heat pump research [J]. ASHRAE Trans, 1983, 89(2):375-390. [2] Sabau S S, Tao Y X, Liu G, Vidhuvalavan G. Effective thermal...

  15. Vertical Map Storage.

    ERIC Educational Resources Information Center

    Perry, Joanne M.

    1982-01-01

    Discusses the superiority of vertical filing of maps in compressor-style vertical units over horizontal filing in drawers, emphasizing such factors as physical protection of the collection, ease of filing and retrieval, and efficient use of space. Disadvantages of vertical filing are also reviewed. (Author/JL)

  16. Solr assisted heat pump research and development program in the United States

    SciTech Connect

    Andrews, J W

    1980-01-01

    A review of the historical progress and current status of the solar assisted heat pump research and development, supported by the United States Department of Energy, is presented. Much of this work has had as its focus the need for a better source of auxiliary or backup heat than the electric resistance which has generally been assumed in computer simulations of these systems. The two leading candidates are the use of the ground as an alternate heat source/sink or storage element (ground coupling) and the use of fossil fuel burned on site (the bivalent system). The United States program has emphasized ground coupling. Much of the analytical work and heat pump development is applicable to bivalent systems, and some results of this work are discussed. Project descriptions and technical accomplishments for the currently active projects are presented.

  17. Vertical bounce of two vertically aligned balls

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2007-11-01

    When a tennis ball rests on top of a basketball and both drop to the floor together, the tennis ball is projected vertically at high speed. A mass-spring model of the impact, as well as air track data, suggest that the tennis ball should be projected at relatively low speed. Measurements of the forces on each ball and the bounce of vertically aligned superballs are used to resolve the discrepancy.

  18. Vertical axis wind turbines

    DOEpatents

    Krivcov, Vladimir (Miass, RU); Krivospitski, Vladimir (Miass, RU); Maksimov, Vasili (Miass, RU); Halstead, Richard (Rohnert Park, CA); Grahov, Jurij (Miass, RU)

    2011-03-08

    A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

  19. Signatures of currency vertices

    E-print Network

    Holme, Petter

    2008-01-01

    Many real-world networks have broad degree distributions. For some systems, this means that the functional significance of the vertices is also broadly distributed, in other cases the vertices are equally significant, but in different ways. One example of the latter case is metabolic networks, where the high-degree vertices -- the currency metabolites -- supply the molecular groups to the low-degree metabolites, and the latter are responsible for the higher-order biological function, of vital importance to the organism. In this paper, we propose a generalization of currency metabolites to currency vertices. We investigate the network structural characteristics of such systems, both in model networks and in some empirical systems. In addition to metabolic networks, we find that a network of music collaborations and a network of e-mail exchange could be described by a division of the vertices into currency vertices and others.

  20. Vertical Axis Wind Turbine

    Energy Science and Technology Software Center (ESTSC)

    2002-04-01

    Blade fatigue life is an important element in determining the economic viability of the Vertical-Axis Wind Turbine (VAWT). VAWT-SAL Vertical Axis Wind Turbine- Stochastic Aerodynamic Loads Ver 3.2 numerically simulates the stochastic (random0 aerodynamic loads of the Vertical-Axis Wind Turbine (VAWT) created by the atomspheric turbulence. The program takes into account the rotor geometry, operating conditions, and assumed turbulence properties.

  1. Offset vertical radar profiling

    USGS Publications Warehouse

    Witten, A.; Lane, J.

    2003-01-01

    Diffraction tomography imaging was applied to VRP data acquired by vertically moving a receiving antenna in a number of wells. This procedure simulated a vertical downhole receiver array. Similarly, a transmitting antenna was sequentially moved along a series of radial lines extending outward from the receiver wells. This provided a sequence of multistatic data sets and, from each data set, a two-dimensional vertical cross-sectional image of spatial variations in wave speed was reconstructed.

  2. The Effective Vertical Advection-Diffusion Balance

    NASA Astrophysics Data System (ADS)

    Huber, M.; Tailleux, R.; Ferreira, D.; Kuhlbrodt, T.; Gregory, J. M.

    2014-12-01

    The capacity of the world ocean to transfer heat to deeper levels is a crucial factor in setting the magnitude and temporal evolution of the global temperature response under transient climate change. A traditional framework to discuss the vertical ocean heat balance is the classic upwelling-diffusive model of Munk [1966] between upwelling of cold abyssal waters and downward diffusion of warm waters. This simple framework is also often used to interpret (and predict) transient heat uptake under climate change. However, this is done in an ad-hoc manner, with little acknowledgment of the complex physics hidden behind the vertical velocity w and diffusivity k? of the classic model (advection of heat by the mean and eddy circulation, diffusion along and across surfaces of constant density, deep convection). Here, we derive an effective vertical velocity and an effective diffusivity for each advective and diffusive process from the steady-state temperature tendencies of two models, an eddy-parameterizing (HadCM3) and an eddy-permitting climate model (HiGEM). For both models, we find that both the effective vertical velocity and diffusivity change sign in mid-depth, highlighting the two physical regimes in which the residual advection is balanced by diapycnal diffusion (deep ocean) and isopycnal diffusion (upper to mid-depths). These findings are at odds with common practices which assume that w and k? are positive constants (in space and time), but is consistent with previous studies of the modeled heat balance. We further present the time-evolution of the effective quantities under an idealized transient climate change simulation. We demonstrate that these spatial and time variations are key to evaluate the transient heat uptake. Implications for the use of simple upwelling-diffusive models to interpret transient heat uptake will be discussed.

  3. Comparison of DOE-2.1E with Energyplus and TRNSYS for Ground Coupled Residential Buildings in Hot anf Humid Climates Stage 4 

    E-print Network

    Andolsun, S.; Culp, C.

    2012-01-01

    .P. Bahnfleth, Three Dimensional Modeling of Heat Transfer from Slab Floors, Ph.D. Dissertation, University of Illinois (1989). February 2012 Energy Systems Laboratory, The Texas A&M University System [7] J. Huang, N. Bourassa, F. Buhl, E. Erdem, R...

  4. Vertical two chamber reaction furnace

    DOEpatents

    Blaugher, Richard D. (Evergreen, CO)

    1999-03-16

    A vertical two chamber reaction furnace. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium-copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700.degree. and 800.degree. C.) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800.degree. to 950.degree. C. to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product.

  5. Vertical two chamber reaction furnace

    DOEpatents

    Blaugher, R.D.

    1999-03-16

    A vertical two chamber reaction furnace is disclosed. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700 and 800 C) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800 to 950 C to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product. 2 figs.

  6. Vertical axis windmill

    SciTech Connect

    Campbell, J.S.

    1980-04-08

    A vertical axis windmill is described which involves a rotatable central vertical shaft having horizontal arms pivotally supporting three sails that are free to function in the wind like the main sail on a sail boat, and means for disabling the sails to allow the windmill to be stopped in a blowing wind.

  7. Geothermal direct-heat utilization assistance. Quarterly project progress report, October--December 1993

    SciTech Connect

    Not Available

    1993-12-31

    This report consists of brief summaries of the activities of the Geo-Heat Center during the report period. Technical assistance was given to requests from 20 states in the following applications: space and district heating; geothermal heat pumps; greenhouses; aquaculture; industrial plants; electric power; resource/well; equipment; and resort/spa. Research and development activities progressed on (1) compilation of data on low-temperature resources and (2) evaluation of groundwater vs. ground-coupled heat pumps. Also summarized are technology transfer activities and geothermal progress monitoring activities.

  8. Heat transfer system

    DOEpatents

    Not Available

    1980-03-07

    A heat transfer system for a nuclear reactor is described. Heat transfer is accomplished within a sealed vapor chamber which is substantially evacuated prior to use. A heat transfer medium, which is liquid at the design operating temperatures, transfers heat from tubes interposed in the reactor primary loop to spaced tubes connected to a steam line for power generation purposes. Heat transfer is accomplished by a two-phase liquid-vapor-liquid process as used in heat pipes. Condensible gases are removed from the vapor chamber through a vertical extension in open communication with the chamber interior.

  9. Heat transfer system

    DOEpatents

    McGuire, Joseph C. (Richland, WA)

    1982-01-01

    A heat transfer system for a nuclear reactor. Heat transfer is accomplished within a sealed vapor chamber which is substantially evacuated prior to use. A heat transfer medium, which is liquid at the design operating temperatures, transfers heat from tubes interposed in the reactor primary loop to spaced tubes connected to a steam line for power generation purposes. Heat transfer is accomplished by a two-phase liquid-vapor-liquid process as used in heat pipes. Condensible gases are removed from the vapor chamber through a vertical extension in open communication with the chamber interior.

  10. Micromachined electrostatic vertical actuator

    DOEpatents

    Lee, Abraham P. (Walnut Creek, CA); Sommargren, Gary E. (Santa Cruz, CA); McConaghy, Charles F. (Livermore, CA); Krulevitch, Peter A. (Pleasanton, CA)

    1999-10-19

    A micromachined vertical actuator utilizing a levitational force, such as in electrostatic comb drives, provides vertical actuation that is relatively linear in actuation for control, and can be readily combined with parallel plate capacitive position sensing for position control. The micromachined electrostatic vertical actuator provides accurate movement in the sub-micron to micron ranges which is desirable in the phase modulation instrument, such as optical phase shifting. For example, compact, inexpensive, and position controllable micromirrors utilizing an electrostatic vertical actuator can replace the large, expensive, and difficult-to-maintain piezoelectric actuators. A thirty pound piezoelectric actuator with corner cube reflectors, as utilized in a phase shifting diffraction interferometer can be replaced with a micromirror and a lens. For any very precise and small amplitudes of motion` micromachined electrostatic actuation may be used because it is the most compact in size, with low power consumption and has more straightforward sensing and control options.

  11. Vertical neck lifting.

    PubMed

    Jacono, Andrew A; Talei, Benjamin

    2014-05-01

    The authors' vertical neck lifting procedure is an extended deep plane facelift, which elevates the skin and SMAS-platysma complex as a composite unit. The goal is to redrape cervicomental laxity vertically onto the face rather than laterally and postauricularly. The authors consider this an extended technique because it lengthens the deep plane flap from the angle of the mandible into the neck to release the cervical retaining ligaments that limit platysmal redraping. This technique does not routinely use midline platysmal surgery because it counteracts the extent of vertical redraping. A majority of aging face patients are good candidates for this procedure in isolation, but indications for combining vertical neck lifting with submental surgery are elucidated. PMID:24745389

  12. Vertical sleeve gastrectomy

    MedlinePLUS

    ... smaller stomach is about the size of a banana. It limits the amount of food you can ... staples. This creates a long vertical tube or banana-shaped stomach. The surgery does not involve cutting ...

  13. Natural Convection from Vertical Parallel Plates: An Integral Method Solution

    E-print Network

    Bahrami, Majid

    Natural Convection from Vertical Parallel Plates: An Integral Method Solution Mehran Ahmadi, Canada DOI: 10.2514/1.T4308 Steady-state external natural convection heat transfer from isothermal direction), m h = convection heat transfer coefficient, Wm2 K k = thermal conductivity, WmK L = base plate

  14. Enhancement of heat transfer

    NASA Astrophysics Data System (ADS)

    Nakayama, W.

    Recent publications on enhancement of heat transfer are reviewed, emphasizing the effects of roughness elements, fins, and porous surfaces. Enhancement of forced convective heat transfer on roughened surfaces, performance evaluation of enhanced surfaces, viscous flows in cooled tubes and tubes with swirlers, and active methods of enhancement are addressed. Aspects of pool boiling heat transfer are considered, including nucleate boiling heat transfer on rough surfaces and porous surfaces, and maximum and minimum heat fluxes. Evaporative heat transfer is discussed for thin-film evaporation on structured surfaces and liquid spray cooling of a heated surface. Condensation heat transfer on external surfaces is covered, including filmwise condensation on vertical finned and fluted surfaces and on horizontal tubes. In-tube boiling and condensation are treated, discussing their enhancement by fins and inserts, as well as critical heat flux in coiled, rifled, and corrugated tubes.

  15. Thermal Impacts of Vertical Greenery Systems

    NASA Astrophysics Data System (ADS)

    Safikhani, Tabassom; Abdullah, Aminatuzuhariah Megat; Ossen, Dilshan Remaz; Baharvand, Mohammad

    2014-12-01

    - Using vertical greenery systems to reduce heat transmission is becoming more common in modern architecture. Vertical greenery systems are divided into two main categories; green facades and living walls. This study aims to examine the thermal performance of vertical greenery systems in hot and humid climates. An experimental procedure was used to measure indoor temperature and humidity. These parameters were also measured for the gap between the vertical greenery systems and wall surfaces. Three boxes were used as small-scale rooms. Two boxes were provided with either a living wall or a green facade and one box did not have any greenery (benchmark). Blue Trumpet Vine was used in the vertical greenery systems. The data were recorded over the course of three sunny days in April 2013. An analyses of the results showed that the living wall and green facade reduced indoor temperature up to 4.0 °C and 3.0 °C, respectively. The living wall and green facade also reduced cavity temperatures by 8.0 °C and 6.5 °C, respectively.

  16. Vertical shaft windmill

    NASA Technical Reports Server (NTRS)

    Grana, D. C.; Inge, S. V., Jr. (inventors)

    1983-01-01

    A vertical shaft has several equally spaced blades mounted. Each blade consists of an inboard section and an outboard section skew hinged to the inboard section. The inboard sections automatically adjust their positions with respect to the fixed inboard sections with changes in velocity of the wind. This windmill design automatically governs the maximum rotational speed of shaft.

  17. Aiding Vertical Guidance Understanding

    NASA Technical Reports Server (NTRS)

    Feary, Michael; McCrobie, Daniel; Alkin, Martin; Sherry, Lance; Polson, Peter; Palmer, Everett; McQuinn, Noreen

    1998-01-01

    A two-part study was conducted to evaluate modern flight deck automation and interfaces. In the first part, a survey was performed to validate the existence of automation surprises with current pilots. Results indicated that pilots were often surprised by the behavior of the automation. There were several surprises that were reported more frequently than others. An experimental study was then performed to evaluate (1) the reduction of automation surprises through training specifically for the vertical guidance logic, and (2) a new display that describes the flight guidance in terms of aircraft behaviors instead of control modes. The study was performed in a simulator that was used to run a complete flight with actual airline pilots. Three groups were used to evaluate the guidance display and training. In the training, condition, participants went through a training program for vertical guidance before flying the simulation. In the display condition, participants ran through the same training program and then flew the experimental scenario with the new Guidance-Flight Mode Annunciator (G-FMA). Results showed improved pilot performance when given training specifically for the vertical guidance logic and greater improvements when given the training and the new G-FMA. Using actual behavior of the avionics to design pilot training and FMA is feasible, and when the automated vertical guidance mode of the Flight Management System is engaged, the display of the guidance mode and targets yields improved pilot performance.

  18. The effects of soil vertical discretization, soil thermal properties, and soil heat convection by liquid water transfer on the water and energy cycles in a coupled land-atmosphere model

    NASA Astrophysics Data System (ADS)

    Wang, Fuxing; Dufresne, Jean-Louis; Chéruy, Frédérique; Ducharne, Agnès

    2015-04-01

    The soil heat transfer is an important component in general circulation model (GCM), and accurate representation of subsurface thermodynamics is essential for earth system modeling. The accuracy of the soil thermodynamics simulation is affected by many factors: (1) the bottom boundary layer position used in numerical scheme; (2) the soil thermal property (heat capacity and thermal conductivity) parameterization; as well as (3) the physical processes considered in the model. However, the impact of their correct representation on the quality of the simulated climate is poorly documented, and the way state-of-the art land surface model (LSM) used for climate simulations account for them is highly variable. For instance bottom boundary layer position varies from 2 m to 10 m or even more (100 m), the parameterizations of the soil thermal properties not always account for the soil texture effects, and the soil heat convection process is neglected in most soil thermodynamics models. In this work, we revisited the soil thermodynamics model included in the ORCHIDEE LSM in order (1) to determine the soil bottom layer depth which allows for simulating the annual cycle of temperature; (2) to improve the parameterization of the soil thermal properties (thermal conductivity and heat capacity) by accounting for both soil moisture and soil texture effects on the soil thermal properties; (3) to take into account the heat generated by liquid water movement in soil thermodynamics. The developpement of the parameterizations has been done in a 1-D framework where the results of the Finite Difference Method have been compared to the analytical solution. Sensitivity experiments with the LMDZ-ORCHIDEE coupled model (atmosphere-land component of IPSL-CM model) have been then designed to evaluate the impact of the soil thermal properties and soil heat convection on the water and energy cycles of the land-atmosphere. Main results are: (1) the 8 meter soil depth is proposed as a minimum requirement for simulating the annual cycle of soil temperature; (2) the surface water and energy cycles are sensitive to the soil thermal property parameterization. A lower (higher) thermal inertia leads to smaller (larger) amplitude of surface soil heat flux. The soil temperature decreases (increases) with the decreasing (increasing) of soil heat diffusivity. The net radiation is also affected by soil thermal properties due to the variation of upward long-wave radiation (caused by surface temperature). The changing of net radiation is mainly compensated by the sensible heat flux. During the night, the air temperature is more affected by the soil thermal properties than that during the day. (3) The rain temperature is lower than the land surface temperature in most regions, which means that the rainfall cools the land surface. In daily or shorter (e.g., 3-Houly) time scales, the soil temperature (turbulent heat flux) varies about 0.05 K (+/- 6 W/m2) with the rainfall (its heat flux) equal 0-5mm/d (0-4 W/m2). The soil heat convection effects on surface turbulent heat fluxes are small (+/- 1 W/m2) on monthly scale.

  19. Vertical organic transistors

    NASA Astrophysics Data System (ADS)

    Lüssem, Björn; Günther, Alrun; Fischer, Axel; Kasemann, Daniel; Leo, Karl

    2015-11-01

    Organic switching devices such as field effect transistors (OFETs) are a key element of future flexible electronic devices. So far, however, a commercial breakthrough has not been achieved because these devices usually lack in switching speed (e.g. for logic applications) and current density (e.g. for display pixel driving). The limited performance is caused by a combination of comparatively low charge carrier mobilities and the large channel length caused by the need for low-cost structuring. Vertical Organic Transistors are a novel technology that has the potential to overcome these limitations of OFETs. Vertical Organic Transistors allow to scale the channel length of organic transistors into the 100?nm regime without cost intensive structuring techniques. Several different approaches have been proposed in literature, which show high output currents, low operation voltages, and comparatively high speed even without sub-?m structuring technologies. In this review, these different approaches are compared and recent progress is highlighted.

  20. Vertical organic transistors.

    PubMed

    Lüssem, Björn; Günther, Alrun; Fischer, Axel; Kasemann, Daniel; Leo, Karl

    2015-11-11

    Organic switching devices such as field effect transistors (OFETs) are a key element of future flexible electronic devices. So far, however, a commercial breakthrough has not been achieved because these devices usually lack in switching speed (e.g. for logic applications) and current density (e.g. for display pixel driving). The limited performance is caused by a combination of comparatively low charge carrier mobilities and the large channel length caused by the need for low-cost structuring. Vertical Organic Transistors are a novel technology that has the potential to overcome these limitations of OFETs. Vertical Organic Transistors allow to scale the channel length of organic transistors into the 100?nm regime without cost intensive structuring techniques. Several different approaches have been proposed in literature, which show high output currents, low operation voltages, and comparatively high speed even without sub-?m structuring technologies. In this review, these different approaches are compared and recent progress is highlighted. PMID:26466388

  1. EnergyPlus vs DOE-2: The Effect of Ground Coupling on Heating and Cooling Energy Consumption of a Slab-On-Grade Code House in a Cold Climate 

    E-print Network

    Andolsun, S.; Culp, C.; Haberl, J.

    2010-01-01

    , USA: National Renewable Energy Laboratory. www.nrel.gov/docs/fy03osti/33954.pdf. Huang, J., Bourassa, N., Buhl, F., Erdem, E., Hitchcock, R. 2006. Using EnergyPlus for California Title-24 Compliance Calculations. Proceedings of SimBuild 2006, 2...

  2. 'Endurance' All Around Vertical)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 360-degree view of the terrain surrounding NASA's Mars Exploration Rover Opportunity was taken on the rover's 171st sol on Mars (July 17, 2004). It was assembled from images taken by the rover's navigation camera at a position referred to as 'site 33.' Opportunity had driven 11 meters (36 feet) into 'Endurance Crater.' The view is a vertical projection with geometrical seam correction.

  3. Advanced heat pump research and development

    NASA Astrophysics Data System (ADS)

    Kuliasha, M. A.

    The Office of Building Energy Research and Development of the U.S. Department of Energy (DOE), has been funding R&D in advanced heat pumps and appliances since 1976. Much of that research has been managed for DOE by the Oak Ridge National Laboratory (ORNL). The objective of the Building Equipment Research (BER) program at ORNL has been to generate new concepts and develop a technology base for improving the energy efficiency and load characteristics of energy conversion equipment used in residential and commercial buildings. The research being pursued to achieve these objectives falls under three general areas: thermally activated heat pumps (TAHP), refrigeration systems, and building equipment systems. The TAHP work is concentrated on three technologies: (1) absorption heat pumps; (2) Stirling engine-driven heat pumps; and (3) internal combustion (IC) engine-driven heat pumps. Major project areas in refrigeration systems research include electric heat pumps, ground-coupled heat pumps, and refigerant mixtures. In the building equipment systems areas, project areas include advanced distribution systems, advanced insulation for appliances, and commercial building equipment.

  4. 'Endurance' Untouched (vertical)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This navigation camera mosaic, created from images taken by NASA's Mars Exploration Rover Opportunity on sols 115 and 116 (May 21 and 22, 2004) provides a dramatic view of 'Endurance Crater.' The rover engineering team carefully plotted the safest path into the football field-sized crater, eventually easing the rover down the slopes around sol 130 (June 12, 2004). To the upper left of the crater sits the rover's protective heatshield, which sheltered Opportunity as it passed through the martian atmosphere. The 360-degree view is presented in a vertical projection, with geometric and radiometric seam correction.

  5. Vertical combustor for particulate refuse

    NASA Astrophysics Data System (ADS)

    Chung, P. M.; Carlson, L.

    1981-03-01

    A one-dimensional model is constructed of a vertical combustor for refuse particle combustion in order to analyze it for waste energy recovery. The three components of the model, fuel particles, inert solid particles and the gaseous mixture are described by momentum, energy, and mass conservation equations, resulting in three different flow velocities and temperatures for the medium. The gaseous component is further divided into six chemical species that evolve in combustion at temperatures below about 1367 K. A detailed description is given of the fuel particle combustion through heating, devolatilization, and combustion of the volatile gas in the boundary layer, return of the flame sheet to the fuel surface, and char combustion. The solutions show the combustor to be viable for U.S. refuse which consists of combustibles that can be volatilized up to 85 to 95% below 1366 K. Char combustion, however, is found to be too slow to be attempted in the combustor, where the fuel residence time is of the order of 2 s.

  6. Vertical wind turbine

    SciTech Connect

    Danson, D.P.

    1988-08-16

    This patent describes a wind driven turbine of the vertical axis type comprising: (a) a support base; (b) a generally vertical column rotatably mounted to the support base; (c) upper and lower support means respectively mounted on the column for rotation therewith; wind driven blades connected between the upper and lower support means for rotation about the column and each blade being individually rotatable about a blade axis extending longitudinally through the blade to vary a blade angle of attach thereof relative to wind velocity during rotation about the column; and (e) control means for variably adjusting angles of attack of each blade to incident wind, the control means including a connecting rod means having drive means for rotating each blade about the associated blade axis in response to radial movement of the connecting rod means and control shaft pivotally mounted within the column and having a first shaft portion connected to the connecting rod means and a second shaft portion radially offset from the first shaft portion and pivotally connected to radially displace the first portion and thereby the connecting rod means to vary the blade angles of attack during rotation about the column.

  7. Observation of picometer vertical emittance with a vertical undulator.

    PubMed

    Wootton, K P; Boland, M J; Dowd, R; Tan, Y-R E; Cowie, B C C; Papaphilippou, Y; Taylor, G N; Rassool, R P

    2012-11-01

    Using a vertical undulator, picometer vertical electron beam emittances have been observed at the Australian Synchrotron storage ring. An APPLE-II type undulator was phased to produce a horizontal magnetic field, which creates a synchrotron radiation field that is very sensitive to the vertical electron beam emittance. The measured ratios of undulator spectral peak heights are evaluated by fitting to simulations of the apparatus. With this apparatus immediately available at most existing electron and positron storage rings, we find this to be an appropriate and novel vertical emittance diagnostic. PMID:23215388

  8. Measurement of ultralow vertical emittance using a calibrated vertical undulator

    NASA Astrophysics Data System (ADS)

    Wootton, K. P.; Boland, M. J.; Rassool, R. P.

    2014-11-01

    Very few experimental techniques are useful for the direct observation of ultralow vertical emittance in electron storage rings. In this work, quantitative measurements of ultralow (pm rad) electron beam vertical emittance using a vertical undulator are presented. An undulator radiation model was developed using the measured magnetic field of the APPLE-II type undulator. Using calibrated experimental apparatus, a geometric vertical emittance of ?y=0.9 ±0.3 pm rad has been observed. These measurements could also inform modeling of the angular distribution of undulator radiation at high harmonics, for proposed diffraction-limited storage ring light sources.

  9. Multicolored Vertical Silicon Nanowires

    SciTech Connect

    Seo, Kwanyong; Wober, Munib; Steinvurzel, P.; Schonbrun, E.; Dan, Yaping; Ellenbogen, T.; Crozier, K. B.

    2011-04-13

    We demonstrate that vertical silicon nanowires take on a surprising variety of colors covering the entire visible spectrum, in marked contrast to the gray color of bulk silicon. This effect is readily observable by bright-field microscopy, or even to the naked eye. The reflection spectra of the nanowires each show a dip whose position depends on the nanowire radii. We compare the experimental data to the results of finite difference time domain simulations to elucidate the physical mechanisms behind the phenomena we observe. The nanowires are fabricated as arrays, but the vivid colors arise not from scattering or diffractive effects of the array, but from the guided mode properties of the individual nanowires. Each nanowire can thus define its own color, allowing for complex spatial patterning. We anticipate that the color filter effect we demonstrate could be employed in nanoscale image sensor devices.

  10. ON-LINE TOOLS FOR PROPER VERTICAL POSITIONING OF VERTICAL SAMPLING INTERVALS DURING SITE ASSESSMENT

    EPA Science Inventory

    This presentation presents on-line tools for proper vertical positioning of vertical sampling intervals during site assessment. Proper vertical sample interval selection is critical for generate data on the vertical distribution of contamination. Without vertical delineation, th...

  11. Heat-pipe Earth.

    PubMed

    Moore, William B; Webb, A Alexander G

    2013-09-26

    The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics. PMID:24067709

  12. Vertical counterflow evaporative cooler

    DOEpatents

    Bourne, Richard C.; Lee, Brian Eric; Callaway, Duncan

    2005-01-25

    An evaporative heat exchanger having parallel plates that define alternating dry and wet passages. A water reservoir is located below the plates and is connected to a water distribution system. Water from the water distribution system flows through the wet passages and wets the surfaces of the plates that form the wet passages. Air flows through the dry passages, mixes with air below the plates, and flows into the wet passages before exiting through the top of the wet passages.

  13. Well-pumping issues in commercial groundwater heat pump systems

    SciTech Connect

    Rafferty, K.D.

    1998-10-01

    Groundwater flow minimizes total system power (well pump, heat pumps, loop pump) and is based upon building peak block load. Optimum flow for water temperatures in the 50 F to 70 F range is 1.25 gpm to 2.5 gpm per ton of peak block load, depending upon total pump head. Submersible pumps are likely to be the type used in most systems. Contrary to popular belief, well pumping does not result in substantially lower groundwater system performance (system EER, system COP) compared to closed-loop systems. In fact, groundwater systems, due to more favorable operating temperatures, can offer performance superior to ground-coupled systems under certain circumstances. All systems evaluated in this report employ a plate heat exchanger to isolate the heat pump from the groundwater.

  14. High-Rayleigh-Number Convection in a Vertical Channel

    NASA Astrophysics Data System (ADS)

    Gibert, M.; Pabiou, H.; Chillà, F.; Castaing, B.

    2006-02-01

    We measure the relation between convective heat flux and temperature gradient in a vertical channel filled with water, the average vertical mass flux being zero. Compared to the classical Rayleigh-Bénard case, this situation has the advantage of avoiding plates and, thus, their neighborhood, in which is usually concentrated most of the temperature gradient. Consequently, inertial processes should control the convection, with poor influence of the viscosity. This idea gives a good account of our observations, if we consider that a natural vertical length, different from the channel width, appears. Our results also suggest that heat fluxes can be deduced from velocity measurements in free convective flows. This confers to our results a wide range of applications.

  15. DISTANCES BETWEEN PAIRS OF VERTICES AND VERTICAL PROFILE IN CONDITIONED

    E-print Network

    Devroye, Luc

    DISTANCES BETWEEN PAIRS OF VERTICES AND VERTICAL PROFILE IN CONDITIONED GALTON­WATSON TREES LUC DEVROYE AND SVANTE JANSON Abstract. We consider a conditioned Galton­Watson tree and prove an estimate of a randomly labelled conditioned Galton­Watson tree converges in distribution, after suitable normalization

  16. DISTANCES BETWEEN PAIRS OF VERTICES AND VERTICAL PROFILE IN CONDITIONED

    E-print Network

    Janson, Svante

    DISTANCES BETWEEN PAIRS OF VERTICES AND VERTICAL PROFILE IN CONDITIONED GALTON--WATSON TREES LUC DEVROYE AND SVANTE JANSON Abstract. We consider a conditioned Galton--Watson tree and prove an estimate of a randomly labelled conditioned Galton--Watson tree converges in distribution, after suitable normalization

  17. 4. VIEW OF VERTICAL BORING MACHINE. (Bullard) Vertical turning lathe ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW OF VERTICAL BORING MACHINE. (Bullard) Vertical turning lathe (VTL). Machining the fixture for GE Turboshroud. G.S. O'Brien, operator. - Juniata Shops, Machine Shop No. 1, East of Fourth Avenue at Third Street, Altoona, Blair County, PA

  18. Revisiting the radiative vertical velocity paradigm in the TTL

    NASA Astrophysics Data System (ADS)

    Bolot, Maximilien; Moyer, Elisabeth

    2015-04-01

    We demonstrate that uplift rates in the TTL (tropical tropopause layer) may be commonly overestimated. The mass balance of any tracer in the TTL depends on the vertical speed of large-scale uplift and the rate of convective detrainment from overshoots. Generally, uplift velocity is retrieved from the conservation of energy, assuming that the only significant factor is radiative heating.1,2 The detrainment rate is then computed from the convergence of the uplift flux, with the assumption that detrainment dominates over entrainment in the TTL. We show that this commonly calculated 'radiative vertical velocity' and the associated rate of detrainment are necessarily flawed for either of two mutually exclusive reasons. If radiative heating is the sole diabatic term in the energy budget, then significant convective entrainment must occur at TTL levels. If detrainment dominates over entrainment, then the heat budget must include the cooling rate from the export of sensible heat deficit in overshooting convection. We illustrate the calculations using tropical values of radiative heating rates and large-scale divergence fluxes from ERA-Interim reanalysis. For undilute convection, the export of heat deficit in detrained overshoots would substantially offset radiative heating, lowering the resulting assumed vertical velocity at 16 km by a factor of three. The computed detrainment rate at this altitude also increases significantly, by a factor of five. Because these changes would alter interpretation of tracer profiles, it is important to include all terms in the heat budget in tracer studies. Conversely, tracer transport properties can be used to help constrain the impact of convection on the TTL heat budget.3 [1] Folkins, I. et al., J. Geophys. Res., 111, D23304, (2006). [2] Read, W. G. et al., Atmos. Chem. Phys., 8, 6051-6067, (2008). [3] Kuang, Z. and Bretherton, C. S., J. Atmos. Sci., 61, 2919-2927, (2004)

  19. Vertical 2D Heterostructures

    NASA Astrophysics Data System (ADS)

    Lotsch, Bettina V.

    2015-07-01

    Graphene's legacy has become an integral part of today's condensed matter science and has equipped a whole generation of scientists with an armory of concepts and techniques that open up new perspectives for the postgraphene area. In particular, the judicious combination of 2D building blocks into vertical heterostructures has recently been identified as a promising route to rationally engineer complex multilayer systems and artificial solids with intriguing properties. The present review highlights recent developments in the rapidly emerging field of 2D nanoarchitectonics from a materials chemistry perspective, with a focus on the types of heterostructures available, their assembly strategies, and their emerging properties. This overview is intended to bridge the gap between two major—yet largely disjunct—developments in 2D heterostructures, which are firmly rooted in solid-state chemistry or physics. Although the underlying types of heterostructures differ with respect to their dimensions, layer alignment, and interfacial quality, there is common ground, and future synergies between the various assembly strategies are to be expected.

  20. Heat pipe array heat exchanger

    DOEpatents

    Reimann, Robert C. (Lafayette, NY)

    1987-08-25

    A heat pipe arrangement for exchanging heat between two different temperature fluids. The heat pipe arrangement is in a ounterflow relationship to increase the efficiency of the coupling of the heat from a heat source to a heat sink.

  1. Enhanced Joule Heating in Umbral Dots

    E-print Network

    Chandan Joshi; Lokesh Bharti; S. N. A. Jaaffrey

    2007-05-10

    We present a study of magnetic profiles of umbral dots (UDs) and its consequences on the Joule heating mechanisms. Hamedivafa (2003) studied Joule heating using vertical component of magnetic field. In this paper UDs magnetic profile has been investigated including the new azimuthal component of magnetic field which might explain the relatively larger enhancement of Joule heating causing more brightness near circumference of UD.

  2. Vertical axis wind turbine airfoil

    DOEpatents

    Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich

    2012-12-18

    A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.

  3. Visualize Vertical Connectedness (Middle Ground).

    ERIC Educational Resources Information Center

    van Allen, Lanny

    1996-01-01

    Discusses the possibility of vertical connectedness in K-12 education through references to journal articles and the author's own reflections. Suggests that middle school teachers may be leaders in a movement toward eliminating redundancy and gaps between grade levels. (TB)

  4. Vertically Aligned Nanocomposite Thin Films 

    E-print Network

    Bi, Zhenxing

    2012-07-16

    Vertically aligned nanocomposite (VAN) thin films have recently stimulated significant research interest to achieve better material functionality or multifunctionalities. In VAN thin films, both phases grow epitaxially in parallel on given...

  5. Place Value: A Vertical Perspective.

    ERIC Educational Resources Information Center

    Bove, Sandra P.

    1995-01-01

    Discusses children's place-value understanding, including initial learning interference, vertical number lines, and planned discourse. Describes a learning activity that can guide children from a concrete to a symbolic understanding of place value. (11 references) (MKR)

  6. Flow reversal of fully developed double diffusive mixed convection in a vertical channel

    NASA Astrophysics Data System (ADS)

    Makhatar, Nur Asiah Mohd; Saleh, Habibis; Hashim, Ishak

    2015-10-01

    The mixed convection flow within a vertical channel having internal heat generation at a rate proportional to a power of the temperature difference is considered. The analysis is concerning the studies of occurrence of flow reversal and the effects of three dimensionless parameters, identified as the internal heat parameter (G), a mixed convection parameter (?) and the exponent (p) in the local heating term on the fully developed double diffusive mixed convection flow in a vertical channel. The governing equations are solved numerically via MAPLE. It was found that flow reversal occurs with larger values of internal heat parameter and mixed convection parameter, but smaller values of local-heating exponent. They also show that, unlike the internal heat parameter and the local-heating exponent, the mixed convection parameter do not give any significant effect on the temperature.

  7. Schlieren visualization of water natural convection in a vertical ribbed channel

    NASA Astrophysics Data System (ADS)

    Fossa, M.; Misale, M.; Tanda, G.

    2015-11-01

    Schlieren techniques are valuable tools for the qualitative and quantitative visualizations of flows in a wide range of scientific and engineering disciplines. A large number of schlieren systems have been developed and documented in the literature; majority of applications involve flows of gases, typically air. In this work, a schlieren technique is applied to visualize the buoyancy-induced flow inside vertical ribbed channels using water as convective fluid. The test section consists of a vertical plate made of two thin sheets of chrome-plated copper with a foil heater sandwiched between them; the external sides of the plate are roughened with transverse, square-cross-sectioned ribs. Two parallel vertical walls, smooth and unheated, form with the heated ribbed plate two adjacent, identical and asymmetrically heated, vertical channels. Results include flow schlieren visualizations with colour-band filters, reconstructions of the local heat transfer coefficient distributions along the ribbed surfaces and comparisons with past experiments performed using air as working fluid.

  8. Vertical Slot Convection: A linear study

    SciTech Connect

    McAllister, A.; Steinolfson, R.; Tajima, T.

    1992-11-01

    The linear stability properties of fluid convection in a vertical slot were studied. We use a Fourier-Chebychev decomposition was used to set up the linear eigenvalue problems for the Vertical Slot Convection and Benard problems. The eigenvalues, neutral stability curves, and critical point values of the Grashof number, G, and the wavenumber were determined. Plots of the real and imaginary parts of the eigenvalues as functions of G and {alpha} are given for a wide range of the Prandtl number, Pr, and special note is made of the complex mode that becomes linearly unstable above Pr {approximately} 12.5. A discussion comparing different special cases facilitates the physical understanding of the VSC equations, especially the interaction of the shear-flow and buoyancy induced physics. Making use of the real and imaginary eigenvalues and the phase properties of the eigenmodes, the eigenmodes were characterized. One finds that the mode structure becomes progressively simpler with increasing Pr, with the greatest complexity in the mid ranges where the terms in the heat equation are of roughly the same size.

  9. Vertical Slot Convection: A linear study

    SciTech Connect

    McAllister, A. ); Steinolfson, R. ); Tajima, T. . Inst. for Fusion Studies)

    1992-11-01

    The linear stability properties of fluid convection in a vertical slot were studied. We use a Fourier-Chebychev decomposition was used to set up the linear eigenvalue problems for the Vertical Slot Convection and Benard problems. The eigenvalues, neutral stability curves, and critical point values of the Grashof number, G, and the wavenumber were determined. Plots of the real and imaginary parts of the eigenvalues as functions of G and [alpha] are given for a wide range of the Prandtl number, Pr, and special note is made of the complex mode that becomes linearly unstable above Pr [approximately] 12.5. A discussion comparing different special cases facilitates the physical understanding of the VSC equations, especially the interaction of the shear-flow and buoyancy induced physics. Making use of the real and imaginary eigenvalues and the phase properties of the eigenmodes, the eigenmodes were characterized. One finds that the mode structure becomes progressively simpler with increasing Pr, with the greatest complexity in the mid ranges where the terms in the heat equation are of roughly the same size.

  10. Convective flows in enclosures with vertical temperature or concentration gradients

    NASA Technical Reports Server (NTRS)

    Wang, L. W.; Chai, A. T.; Sun, D. J.

    1988-01-01

    The transport process in the fluid phase during the growth of a crystal has a profound influence on the structure and quality of the solid phase. In vertical growth techniques the fluid phase is often subjected to vertical temperature and concentration gradients. The main objective is to obtain more experimental data on convective flows in enclosures with vertical temperature or concentration gradients. Among actual crystal systems the parameters vary widely. The parametric ranges studied for mass transfer are mainly dictated by the electrochemical system employed to impose concentration gradients. Temperature or concentration difference are maintained between two horizontal end walls. The other walls are kept insulated. Experimental measurements and observations were made of the heat transfer or mass transfer, flow patterns, and the mean and fluctuating temperature distribution. The method used to visualize the flow pattern in the thermal cases is an electrochemical pH-indicator method. Laser shadowgraphs are employed to visualize flow patterns in the solutal cases.

  11. Convective flows in enclosures with vertical temperature or concentration gradients

    NASA Technical Reports Server (NTRS)

    Wang, L. W.; Chai, A. T.; Sun, D. J.

    1989-01-01

    The transport process in the fluid phase during the growth of a crystal has a profound influence on the structure and quality of the solid phase. In vertical growth techniques the fluid phase is often subjected to vertical temperature and concentration gradients. The main objective is to obtain more experimental data on convective flows in enclosures with vertical temperature or concentration gradients. Among actual crystal systems the parameters vary widely. The parametric ranges studied for mass transfer are mainly dictated by the electrochemical system employed to impose concentration gradients. Temperature or concentration difference are maintained between two horizontal end walls. The other walls are kept insulated. Experimental measurements and observations were made of the heat transfer or mass transfer, flow patterns, and the mean and fluctuating temperature distribution. The method used to visualize the flow pattern in the thermal cases is an electrochemical pH-indicator method. Laser shadowgraphs are employed to visualize flow patterns in the solutal cases.

  12. Rewetting of hot vertical rod during jet impingement surface cooling

    NASA Astrophysics Data System (ADS)

    Agrawal, Chitranjan; Kumar, Ravi; Gupta, Akhilesh; Chatterjee, Barun

    2015-07-01

    A stainless steel (SS-316) vertical rod of 12 mm diameter at 800 ± 10 °C initial temperature was cooled by normal impinging round water jet. The surface rewetting phenomenon was investigated for a range of jet diameter 2.5-4.8 mm and jet Reynolds number 5000-24,000 using a straight tube type nozzle. The investigation were made from the stagnation point to maximum 40 mm downstream locations, simultaneously for both upside and downside directions. The cooling performance of the vertical rod was evaluated on the basis of rewetting parameters i.e. rewetting temperature, wetting delay, rewetting velocity and the maximum surface heat flux. Two separate Correlations have been proposed for the dimensionless rewetting velocity in terms of rewetting number and the maximum surface heat flux that predicts the experimental data within an error band of ±20 and ±15 % respectively.

  13. MODELING OF VERTICAL GROUND LOOP HEAT EXCHANGERS FOR GROUND SOURCE

    E-print Network

    main purposes in mind. The first application is the calculation of non-dimensional temperature response to investigate the advantages and the disadvantages of various system operating and control strategies is conducted to compare each operating and control strategy to determine the lowest cost alternative

  14. Kinematic and diabatic vertical velocity climatologies from a chemistry climate model

    NASA Astrophysics Data System (ADS)

    Hoppe, C. M.; Ploeger, F.; Konopka, P.; Müller, R.

    2015-11-01

    The representation of vertical velocity in chemistry climate models is a key element for the representation of the large scale Brewer-Dobson-Circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Messy Atmospheric Chemistry (EMAC) model. The calculation of kinematic vertical velocity is based on the continuity equation, whereas diabatic vertical velocity is computed using diabatic heating rates. Annual and monthly zonal mean climatologies of vertical velocity from a 10 year simulation are provided for both, kinematic and diabatic vertical velocity representations. In general, both vertical velocity patterns show the main features of the stratospheric circulation, namely upwelling at low latitudes and downwelling at high latitudes. The main difference in the vertical velocity pattern is a more uniform structure for diabatic and a noisier structure for kinematic vertical velocity. Diabatic vertical velocities show higher absolute values both in the upwelling branch in the inner tropics and in the downwelling regions in the polar vortices. Further, there is a latitudinal shift of the tropical upwelling branch in boreal summer between the two vertical velocity representations with the tropical upwelling region in the diabatic representation shifted southward compared to the kinematic case. Furthermore, we present mean age of air climatologies from two transport schemes in EMAC using these different vertical velocities. The age of air distributions show a hemispheric difference pattern in the stratosphere with younger air in the Southern Hemisphere and older air in the Northern Hemisphere using the transport scheme with diabatic vertical velocities. Further, the age of air climatology from the transport scheme using diabatic vertical velocities shows younger mean age of air in the inner tropical upwelling branch and older mean age in the extratopical tropopause region.

  15. Free convection over a vertical porous plate with transpiration

    NASA Technical Reports Server (NTRS)

    Parikh, P. G.; Moffat, R. J.; Kays, W. M.; Bershader, D.

    1974-01-01

    The problem of free convection over an isothermal vertical porous plate with transpiration is studied both numerically and experimentally. Numerical solutions to the variable-property transpired free-convection boundary layer equations have been obtained using the finite difference procedure of Patankar and Spalding (1967). The effects of uniform transpiration on heat transfer and on temperature and velocity profiles are predicted. Interferometrically measured nondimensional temperature profiles for the uniform wall temperature and transpiration case agreed closely with these numerical predictions.

  16. A generalized correlation for condensation on vertical fluted surfaces

    SciTech Connect

    Panchal, C.B.

    1996-03-01

    A correlation was developed for laminar film condensation on vertical fluted surfaces. The theoretical analysis of Panchal and Bell was used for defining important physical property groups. The experimental data of Combs et al. were used to validate the proposed correlation. The experimental database used in the present study included four flute geometries that could be approximated to cosine type flutes and seven fluids. The resulting correlation can predict the average condensate heat-transfer coefficient within {plus_minus} 20%.

  17. Heat emergencies

    MedlinePLUS

    Heatstroke; Heat illness ... who is in good shape can suffer heat illness if warning signs are ignored) The following make ... Heat cramps are the first stage of heat illness. If these symptoms are not treated, it can ...

  18. Vertical feed stick wood fuel burning furnace system

    DOEpatents

    Hill, Richard C. (Orono, ME)

    1982-01-01

    A stove or furnace for efficient combustion of wood fuel includes a vertical feed combustion chamber (15) for receiving and supporting wood fuel in a vertical attitude or stack. A major upper portion of the combustion chamber column comprises a water jacket (14) for coupling to a source of water or heat transfer fluid for convection circulation of the fluid. The locus (31) of wood fuel combustion is thereby confined to the refractory base of the combustion chamber. A flue gas propagation delay channel (34) extending laterally from the base of the chamber affords delayed travel time in a high temperature refractory environment sufficient to assure substantially complete combustion of the gaseous products of wood burning with forced air prior to extraction of heat in heat exchanger (16). Induced draft draws the fuel gas and air mixture laterally through the combustion chamber and refractory high temperature zone to the heat exchanger and flue. Also included are active sources of forced air and induced draft, multiple circuit couplings for the recovered heat, and construction features in the refractory material substructure and metal component superstructure.

  19. Vertical motion simulator familiarization guide

    NASA Technical Reports Server (NTRS)

    Danek, George L.

    1993-01-01

    The Vertical Motion Simulator Familiarization Guide provides a synoptic description of the Vertical Motion Simulator (VMS) and descriptions of the various simulation components and systems. The intended audience is the community of scientists and engineers who employ the VMS for research and development. The concept of a research simulator system is introduced and the building block nature of the VMS is emphasized. Individual sections describe all the hardware elements in terms of general properties and capabilities. Also included are an example of a typical VMS simulation which graphically illustrates the composition of the system and shows the signal flow among the elements and a glossary of specialized terms, abbreviations, and acronyms.

  20. Measurements of vertical bar Vcb vertical bar and vertical bar Vub vertical bar at BaBar

    SciTech Connect

    Rotondo, M.

    2005-10-12

    We report results from the BABAR Collaboration on the semileptonic B decays, highlighting the measurements of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix elements Vub and Vcb. We describe the techniques used to obtain the matrix element |Vcb| using the measurement of the inclusive B {yields} Xclv process and a large sample of exclusive B {yields} D*lv decays. The vertical bar Vub vertical bar matrix elements has been measured studying different kinematic variables of the B {yields} Xulv process, and also with the exclusive reconstruction of B {yields} {pi}({rho})lv decays.

  1. Vertical integration and market power

    SciTech Connect

    Maddigan, R.J.

    1980-01-01

    One of the continuing debates of industrial organization surrounds the importance of market structure in determining a firm's performance. This controversy develops naturally from the difficulties in measuring the relevant variables and the hazards of statistical analysis. The focus of this empirical study is the relationship between vertical integration, as an element of market structure, and market power, as a component of a firm's performance. The model presented in this paper differs from previous efforts because vertical integration is measured by the Vertical Industry Connections (VIC) index. VIC is defined as a function of the relative net interactions among the industries in which a firm operates, and is calculated by use of the national input-output tables. A linear regression model is estimated by means of a random sample of firms selected from the Standard and Poor's COMPUSTAT data base for 1963, 1967, and 1972. Combined cross-sectional, time-series methods are employed. The dependent variable is the price-cost margin; the independent variables include not only VIC, but also the concentration ratio, diversification index, value of assets, capital-output ratio, and sales growth. The results indicate that VIC is significant in increasing the price-cost margin, and thus support the hypothesis that vertical integration is a strategy to enhance market power. 1 figure, 3 tables.

  2. Fast reactor power plant design having heat pipe heat exchanger

    DOEpatents

    Huebotter, P.R.; McLennan, G.A.

    1984-08-30

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the reactor deck and being directly submerged in the primary coolant. A U-tube or line passes through each heat pipe, extended over most of the length of the heat pipe and having its walls spaced from but closely proximate to and generally facing the surrounding walls of the heat pipe. The water/steam coolant loop includes each U-tube and the steam expansion device. A heat transfer medium (such as mercury) fills each of the heat pipes. The thermal energy from the primary coolant is transferred to the water coolant by isothermal evaporation-condensation of the heat transfer medium between the heat pipe and U-tube walls, the heat transfer medium moving within the heat pipe primarily transversely between these walls.

  3. Fast reactor power plant design having heat pipe heat exchanger

    DOEpatents

    Huebotter, Paul R. (Western Springs, IL); McLennan, George A. (Downers Grove, IL)

    1985-01-01

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the reactor deck and being directly submerged in the primary coolant. A U-tube or line passes through each heat pipe, extended over most of the length of the heat pipe and having its walls spaced from but closely proximate to and generally facing the surrounding walls of the heat pipe. The water/steam coolant loop includes each U-tube and the steam expansion device. A heat transfer medium (such as mercury) fills each of the heat pipes. The thermal energy from the primary coolant is transferred to the water coolant by isothermal evaporation-condensation of the heat transfer medium between the heat pipe and U-tube walls, the heat transfer medium moving within the heat pipe primarily transversely between these walls.

  4. Vertical Sextants give Good Sights

    NASA Astrophysics Data System (ADS)

    Dixon, Mark

    Many texts stress the need for marine sextants to be held precisely vertical at the instant that the altitude of a heavenly body is measured. Several authors lay particular emphasis on the technique of the instrument in a small arc about the horizontal axis to obtain a good sight. Nobody, to the author's knowledge, however, has attempted to quantify the errors involved, so as to compare them with other errors inherent in determining celestial position lines. This paper sets out to address these issues and to pose the question: what level of accuracy of vertical alignment can reasonably be expected during marine sextant work at sea ?When a heavenly body is brought to tangency with the visible horizon it is particularly important to ensure that the sextant is held in a truly vertical position. To this end the instrument is rocked gently about the horizontal so that the image of the body describes a small arc in the observer's field of vision. As Bruce Bauer points out, tangency with the horizon must be achieved during the process of rocking and not a second or so after rocking has been discontinued. The altitude is recorded for the instant that the body kisses the visible horizon at the lowest point of the rocking arc, as in Fig. 2. The only other visual clue as to whether the sextant is vertical is provided by the right angle made by the vertical edge of the horizon glass mirror with the horizon. There may also be some input from the observer's sense of balance and his hand orientation.

  5. Graphene vertical hot-electron terahertz detectors

    SciTech Connect

    Ryzhii, V.; Satou, A.; Otsuji, T.; Ryzhii, M.; Mitin, V.; Shur, M. S.

    2014-09-21

    We propose and analyze the concept of the vertical hot-electron terahertz (THz) graphene-layer detectors (GLDs) based on the double-GL and multiple-GL structures with the barrier layers made of materials with a moderate conduction band off-set (such as tungsten disulfide and related materials). The operation of these detectors is enabled by the thermionic emissions from the GLs enhanced by the electrons heated by incoming THz radiation. Hence, these detectors are the hot-electron bolometric detectors. The electron heating is primarily associated with the intraband absorption (the Drude absorption). In the frame of the developed model, we calculate the responsivity and detectivity as functions of the photon energy, GL doping, and the applied voltage for the GLDs with different number of GLs. The detectors based on the cascade multiple-GL structures can exhibit a substantial photoelectric gain resulting in the elevated responsivity and detectivity. The advantages of the THz detectors under consideration are associated with their high sensitivity to the normal incident radiation and efficient operation at room temperature at the low end of the THz frequency range. Such GLDs with a metal grating, supporting the excitation of plasma oscillations in the GL-structures by the incident THz radiation, can exhibit a strong resonant response at the frequencies of several THz (in the range, where the operation of the conventional detectors based on A{sub 3}B{sub 5} materials, in particular, THz quantum-well detectors, is hindered due to a strong optical phonon radiation absorption in such materials). We also evaluate the characteristics of GLDs in the mid- and far-infrared ranges where the electron heating is due to the interband absorption in GLs.

  6. Film boiling on the inside of vertical tubes with upward flow of the fluid at low qualities

    E-print Network

    Dougall, R. S.

    1963-01-01

    Flow regimes, local heat transfer coefficients, and temperature distributions along the wall have been studied for film boiling inside a vertical tube with upward flow of a saturated liquid. The area of interest has been ...

  7. Heat Without Heat

    NASA Astrophysics Data System (ADS)

    Lubkin, Elihu

    1997-04-01

    Logic of the Second Law of Thermodynamics demands acquisition of naked entropy. Accordingly, the leanest liaison between systems is not a diathermic membrane, it is a purely informational tickler, leaking no appreciable energy. The subsystem here is a thermodynamic universe, which gets `heated' entropically, yet without gaining calories. Quantum Mechanics graciously supports that(Lubkin, E. and Lubkin, T., International Journal of Theoretical Physics,32), 933-943 (1993) (at a cost of about 1 bit) through entanglement---across this least permeable of membranes---with what is beyond that universe. Heat without heat(Also v. forthcoming Proceedings of the 4th Drexel University Conference of September 1994) is the aspirin for Boltzmann's headache, conserving entropy in mechanical isolation, even while increasing entropy in thermodynamic isolation.

  8. Performance prediction of a sub-slab heat exchanger for geothermal heat pumps

    SciTech Connect

    Den Braven, K.; Nielson, E.

    1998-11-01

    A large portion of the installation cost of a ground-coupled heat pump system is for the excavation necessary for ground coil placement. One possible method of reducing this cost is to place the ground coils beneath the slab floor of the building. This configuration of ground coil placement has not been specifically addressed in previous research. Freezing of the soil must be avoided in such a system. To simulate the temperature response of the surrounding soil to heat pump operation, a computer model was developed which incorporates line source theory in the form of a system of rings. The fluid temperature change along the length of the coil was used to determine the distribution of the ground load throughout the ring system. The model includes an adiabatic upper boundary, seasonal soil temperature variation, and thermal interference throughout the system. Using these results, the minimum soil temperature over a season was predicted. Based on these results, design recommendations for ground coil installation are provided based on available area, soil type, heat extraction rate, depth of coil beneath the slab floor, and depth of slab floor below grade. These include recommendations for pipe spacing, flow direction, and a method to determine whether this type of system is feasible for installation in a particular location.

  9. Vertically Integrated Circuits at Fermilab

    SciTech Connect

    Deptuch, Grzegorz; Demarteau, Marcel; Hoff, James; Lipton, Ronald; Shenai, Alpana; Trimpl, Marcel; Yarema, Raymond; Zimmerman, Tom; /Fermilab

    2009-01-01

    The exploration of the vertically integrated circuits, also commonly known as 3D-IC technology, for applications in radiation detection started at Fermilab in 2006. This paper examines the opportunities that vertical integration offers by looking at various 3D designs that have been completed by Fermilab. The emphasis is on opportunities that are presented by through silicon vias (TSV), wafer and circuit thinning and finally fusion bonding techniques to replace conventional bump bonding. Early work by Fermilab has led to an international consortium for the development of 3D-IC circuits for High Energy Physics. The consortium has submitted over 25 different designs for the Fermilab organized MPW run organized for the first time.

  10. Kinematic Fitting of Detached Vertices

    SciTech Connect

    Paul Mattione

    2007-05-01

    The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the $\\Xi_{5}$ pentaquarks and investigate the excited $\\Xi$ states. Specifically, the exotic $\\Xi_{5}^{--}$ pentaquark will be sought by first reconstructing the $\\Xi^{-}$ particle through its weak decays, $\\Xi^{-}\\to\\pi^{-}\\Lambda$ and $\\Lambda\\to\\pi^{-}$. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction $\\gamma D\\rightarrow pp\\pi^{-}$ was studied in order to correct the track measurements and covariance matrices of the charged particles. The $\\Lambda\\rightarrow p\\pi^{-}$ and $\\Xi^{-}\\to\\pi^{-}\\Lambda$ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly.

  11. Towards a New Vertical Datum

    NASA Astrophysics Data System (ADS)

    Roman, D. R.; Li, X.; Holmes, S. A.; Childers, V. A.; Wang, Y.

    2012-12-01

    The National Geodetic Survey (NGS) is responsible for maintaining and improving the National Spatial Reference System. This paper particularly focuses on developments leading to a new vertical datum to replace the existing North American Vertical Datum of 1988 (NAVD 88). This new model will be developed from a combination of satellite, airborne, and terrestrial gravity data to define a gravimetric geoid height model. In particular, the aerogravity data collected as a part o the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project are intended to help achieve the goal of a cm-level accurate geoid model to serve as the new vertical datum. The different data sources have been melded into a single gravity field model consistent across the entire spectrum to about 2 km resolution. A previous comparison developed a localized model over just the southern Texas region, where the Geoid Slope Validation Study for 2011 (GSVS 11) demonstrated that it was possible to achieve the desired accuracy. This new model was developed using methodology consistent at regional to national scales following techniques used to make USGG2009 and USGG2012, but now incorporating aerogravity. This new model proves out the basic concepts behind GRAV-D in that the aeorgravity bridge the spectral gap between satellite and terrestrial data and provide the requisite improvements to the derived gravimetric geoid height model - all without artificially targeting a solution to a specific test area. Additional comparisons were made to tidal bench mark data observed by GPS in combination with ocean topography models to validate the behavior of the model in the coastal regions.

  12. NASA-Ames vertical gun

    NASA Technical Reports Server (NTRS)

    Schultz, P. H.

    1984-01-01

    A national facility, the NASA-Ames vertical gun range (AVGR) has an excellent reputation for revealing fundamental aspects of impact cratering that provide important constraints for planetary processes. The current logistics in accessing the AVGR, some of the past and ongoing experimental programs and their relevance, and the future role of this facility in planetary studies are reviewed. Publications resulting from experiments with the gun (1979 to 1984) are listed as well as the researchers and subjects studied.

  13. Vertically aligned carbon based varactors

    NASA Astrophysics Data System (ADS)

    Ghavanini, Farzan A.; Enoksson, Peter; Bengtsson, Stefan; Lundgren, Per

    2011-07-01

    This paper gives an assessment of vertically aligned carbon based varactors and validates their potential for future applications. The varactors discussed here are nanoelectromechanical devices which are based on either vertically aligned carbon nanofibers or vertically aligned carbon nanotube arrays. A generic analytical model for parallel plate nanoelectromechanical varactors based on previous works is developed and is used to formulate a universal expression for their voltage-capacitance relation. Specific expressions for the nanofiber based and the nanotube based varactors are then derived separately from the generic model. This paper also provides a detailed review on the fabrication of carbon based varactors and pays special attention to the challenges in realizing such devices. Finally, the performance of the carbon based varactor is assessed in accordance with four criteria: the static capacitance, the tuning ratio, the quality factor, and the operating voltage. Although the reported performance is still far inferior to other varactor technologies, our prognosis which stems from the analytical model shows a promise of a high quality factor as well as a potential for high power handling for carbon based varactors.

  14. Turbulent natural and mixed convection along a vertical plate

    SciTech Connect

    Abu-Mulaweh, H.I.; Armaly, B.F.; Chen, T.S.; Zhao, J.Z.

    1997-07-01

    Measurements of turbulent boundary-layer air flow in natural and mixed convection adjacent to an isothermal vertical flat plate are reported. Laser-Doppler velocimeter and cold wire anemometer were used, respectively, to measure simultaneously the mean turbulent velocity and temperature distributions were measured for a temperature difference, {Delta}T, of 30 C between the heated wall and the free stream air at a fixed location x = 3 m (with a corresponding Grashof number Gr{sub x} = 8.55 x 10{sup 10}), and for a range of free stream velocities 0 m/s {le} U{sub {infinity} } {le} 0.41 m/s. The effect of small free stream velocity on the turbulent natural convection is examined. These results reveal that the introduction of small free stream velocity on turbulent natural convection flow suppresses turbulence and decreases the heat transfer rate from the heated wall.

  15. Heat Pipes

    ERIC Educational Resources Information Center

    Lewis, J.

    1975-01-01

    Describes the construction, function, and applications of heat pipes. Suggests using the heat pipe to teach principles related to heat transfer and gives sources for obtaining instructional kits for this purpose. (GS)

  16. Heat Illness

    MedlinePLUS

    ... dangerous levels and you can develop a heat illness. Most heat illnesses occur from staying out in ... Heat-related illnesses include Heatstroke - a life-threatening illness in which body temperature may rise above 106° ...

  17. Vertical Integration and Technology: Theory and Evidence

    E-print Network

    Acemoglu, Daron

    We study the determinants of vertical integration. We first derive a number of predictions regarding the relationship between technology intensity and vertical integration from a simple incomplete contracts model. Then, ...

  18. Vertical silicon nanowire arrays for gas sensing

    E-print Network

    Zhao, Hangbo

    2014-01-01

    The goal of this research was to fabricate and characterize vertically aligned silicon nanowire gas sensors. Silicon nanowires are very attractive for gas sensing applications and vertically aligned silicon nanowires are ...

  19. Macrobiotic Vertical Transport of Litter Derived Carbon

    E-print Network

    Post, Wilfred M.

    Macrobiotic Vertical Transport of Litter Derived Carbon (Earthworm Phase) Mac Callaham Corey Babb in each treatment Sampling #12;Macrobiotic Vertical Transport of Litter Derived Carbon (millipede phase) Plans for the Future: #12;

  20. Macrobiotic Vertical Transport of Litter Derived Carbon

    E-print Network

    Post, Wilfred M.

    Macrobiotic Vertical Transport of Litter Derived Carbon (UPDATE) Mac Callaham Corey Babb Paul vertical transport of litter derived carbon-millipede phase More germane to upland sites Sampled uplands for worms (and found one) Plans for the Future: #12;

  1. Vertical feed stick wood fuel burning furnace system

    DOEpatents

    Hill, Richard C. (Orono, ME)

    1984-01-01

    A new and improved stove or furnace for efficient combustion of wood fuel including a vertical feed combustion chamber for receiving and supporting wood fuel in a vertical attitude or stack, a major upper portion of the combustion chamber column comprising a water jacket for coupling to a source of water or heat transfer fluid and for convection circulation of the fluid for confining the locus of wood fuel combustion to the bottom of the vertical gravity feed combustion chamber. A flue gas propagation delay channel extending from the laterally directed draft outlet affords delayed travel time in a high temperature environment to assure substantially complete combustion of the gaseous products of wood burning with forced air as an actively induced draft draws the fuel gas and air mixture laterally through the combustion and high temperature zone. Active sources of forced air and induced draft are included, multiple use and circuit couplings for the recovered heat, and construction features in the refractory material substructure and metal component superstructure.

  2. Vertical velocity spectra from a Doppler Sodar

    SciTech Connect

    Underwood, K.H.; Coulter, R.L.

    1983-01-01

    The capability of Acoustic Doppler Radars or sodars to describe local vertical velocity statistics was evaluated. Sodar was used to monitor the local vertical velocity field to altitudes of 1000 meters in an attempt to study the vertical velocity field associated with cloud formation, maintenance and decay. 5 reference, 6 figures. (ACR)

  3. 46 CFR 108.160 - Vertical ladders.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Vertical ladders. 108.160 Section 108.160 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Means of Escape § 108.160 Vertical ladders. (a) Each vertical ladder must...

  4. 46 CFR 108.160 - Vertical ladders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Vertical ladders. 108.160 Section 108.160 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Means of Escape § 108.160 Vertical ladders. (a) Each vertical ladder must have rungs that are— (1) At least...

  5. Vertically aligned nanostructure scanning probe microscope tips

    DOEpatents

    Guillorn, Michael A.; Ilic, Bojan; Melechko, Anatoli V.; Merkulov, Vladimir I.; Lowndes, Douglas H.; Simpson, Michael L.

    2006-12-19

    Methods and apparatus are described for cantilever structures that include a vertically aligned nanostructure, especially vertically aligned carbon nanofiber scanning probe microscope tips. An apparatus includes a cantilever structure including a substrate including a cantilever body, that optionally includes a doped layer, and a vertically aligned nanostructure coupled to the cantilever body.

  6. Carbothermic reduction with parallel heat sources

    DOEpatents

    Troup, Robert L. (Murrysville, PA); Stevenson, David T. (Washington Township, Washington County, PA)

    1984-12-04

    Disclosed are apparatus and method of carbothermic direct reduction for producing an aluminum alloy from a raw material mix including aluminum oxide, silicon oxide, and carbon wherein parallel heat sources are provided by a combustion heat source and by an electrical heat source at essentially the same position in the reactor, e.g., such as at the same horizontal level in the path of a gravity-fed moving bed in a vertical reactor. The present invention includes providing at least 79% of the heat energy required in the process by the electrical heat source.

  7. ?Vertical Sextants give Good Sights?

    NASA Astrophysics Data System (ADS)

    Richey, Michael

    Mark Dixon suggests (Forum, Vol. 50, 137) that nobody thus far has attempted to quantify the errors from tilt that arise while observing with the marine sextant. The issue in fact, with the related problem of what exactly is the axis about which the sextant is rotated whilst being (to define the vertical), was the subject of a lively controversy in the first two volumes of this Journal some fifty years ago. Since the consensus of opinion seems to have been that the maximum error does not necessarily occur at 45 degrees, whereas Dixon's table suggests that it does, some reiteration of the arguments may be in order.

  8. Granular segregation under vertical tapping

    E-print Network

    M. Pica Ciamarra; M. D. De Vizia; A. Fierro; M. Tarzia; A. Coniglio; M. Nicodemi

    2006-01-13

    We present extensive Molecular Dynamics simulations on species segregation in a granular mixture subject to vertical taps. We discuss how grain properties, e.g., size, density, friction, as well as, shaking properties, e.g., amplitude and frequency, affect such a phenomenon. Both Brazil Nut Effect (larger particles on the top, BN) and the Reverse Brazil Nut Effect (larger particles on the bottom, RBN) are found and we derive the system comprehensive ``segregation diagram'' and the BN to RBN crossover line. We also discuss the role of friction and show that particles which differ only for their frictional properties segregate in states depending on the tapping acceleration and frequency.

  9. Neighbourly polytopes with few vertices

    SciTech Connect

    Devyatov, Rostislav A

    2011-10-31

    A family of neighbourly polytopes in R{sup 2d} with N=2d+4 vertices is constructed. All polytopes in the family have a planar Gale diagram of a special type, namely, with exactly d+3 black points in convex position. These Gale diagrams are parametrized by 3-trees (trees with a certain additional structure). For all polytopes in the family, the number of faces of dimension m containing a given vertex A depends only on d and m. Bibliography: 7 titles.

  10. ATLAS LTCS Vertically Challenged System Lessons Learned

    NASA Technical Reports Server (NTRS)

    Patel, Deepak; Garrison, Matt; Ku, Jentung

    2014-01-01

    Re-planning of LTCS TVAC testing and supporting RTA (Receiver Telescope Assembly) Test Plan and Procedure document preparation. The Laser Thermal Control System (LTCS) is designed to maintain the lasers onboard Advanced Topographic Laser Altimeter System (ATLAS) at their operational temperatures. In order to verify the functionality of the LTCS, a thermal balance test of the thermal hardware was performed. During the first cold start of the LTCS, the Loop Heat Pipe (LHP) was unable to control the laser mass simulators temperature. The control heaters were fully on and the loop temperature remained well below the desired setpoint. Thermal analysis of the loop did not show these results. This unpredicted behavior of the LTCS was brought up to a panel of LHP experts. Based on the testing and a review of all the data, there were multiple diagnostic performed in order to narrow down the cause. The prevailing theory is that gravity is causing oscillating flow within the loop, which artificially increased the control power needs. This resulted in a replan of the LTCS test flow and the addition of a GSE heater to allow vertical operation.

  11. An experimental investigation of critical heat flux in subcooled internal flow 

    E-print Network

    Shatto, Donald Patrick

    1997-01-01

    An experimental investigation has been conducted to determine the critical heat flux for subcooled refrigerant-11 and refrigerant-113 flowing upward in a vertical cylindrical tube. Critical heat flux (CHF) values are ...

  12. A visualization comparison of convective flow boiling heat transfer augmentation devices 

    E-print Network

    Lundy, Brian Franklin

    1998-01-01

    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 ...

  13. Heating Safety

    MedlinePLUS

    Heating Safety Heating equipment is a leading cause of home fire deaths. Almost half of home heating equipment fires are reported during the months of ... and February. Some simple steps can prevent most heating-related fires from happening. Safety Tips • Keep anything ...

  14. The generation of vertical thermospheric winds and gravity waves at auroral latitudes. I - Observations of vertical winds

    NASA Astrophysics Data System (ADS)

    Rees, D.; Charleton, P. J.; Lloyd, N.; Smith, R. W.; McCormac, F. G.; Steen, A.

    1984-06-01

    Vertical winds of tens of meters/sec or more are a ubiquitous feature of the upper thermosphere's wind field in those polar regions that are under the direct influence of magnetospheric energy and momentum sources. In periods of moderate geomagnetic activity, there are regions of systematic vertical winds which exhibit a diurnal variation. Such winds, and large systematic downward winds at times of large disturbances on the poleward boundary of the afternoon auroral oval, appear to be associated with downward divergences or upward convergences of the ion drag-induced horizontal winds acting in addition to the variety of high latitudinal heat sources. Much stronger upward winds which are observed in association with the expansion phase of geomagnetic disturbances are strongly timeand space-dependent and have to be placed in the context of very large disturbances of the horizontal wind field.

  15. Laser tracking for vertical control

    NASA Technical Reports Server (NTRS)

    Dunn, Peter; Torrence, Mark; Pavlis, Erricos; Kolenkiewicz, Ron; Smith, David

    1993-01-01

    The Global Laser Tracking Network has provided LAGEOS ranging data of high accuracy since the first MERIT campaign in late 1983 and we can now resolve centimeter-level three dimensional positions of participating observatories at monthly intervals. In this analysis, the station height estimates have been considered separately from the horizontal components, and can be determined by the strongest stations with a formal standard error of 2 mm using eight years of continuous observations. The rate of change in the vertical can be resolved to a few mm/year, which is at the expected level of several geophysical effects. In comparing the behavior of the stations to that predicted by recent models of post-glacial rebound, we find no correlation in this very small effect. Particular attention must be applied to data and survey quality control when measuring the vertical component, and the survey observations are critical components of the geodynamic results. Seasonal patterns are observed in the heights of most stations, and the possibility of secular motion at the level of several millimeters per year cannot be excluded. Any such motion must be considered in the interpretation of horizontal inter-site measurements, and can help to identify mechanisms which can cause variations which occur linearly with time, seasonally, or abruptly.

  16. Heat budget estimates for Lake Ikeda, Japan

    NASA Astrophysics Data System (ADS)

    Momii, Kazuro; Ito, Yuji

    2008-11-01

    SummaryHeat budget studies of lakes are essential components of efficient lake water management as they give direct information on evaporation and thus the lake water budget. A one-dimensional heat transfer model which includes vertical turbulent mixing in lake water and heat exchange between the lake and the atmosphere was developed and applied to estimate heat budget of Lake Ikeda from 1981 to 2005. The lake is in southern Japan, has a mean water depth of 125 m, and is an important water resource for agriculture, municipal water supply, and fisheries. The computed lake water temperatures were in good agreement with observed temperatures. The model reproduced both the thermal stratification characteristics and the uniform vertical 10 °C temperature profile that occurs in Lake Ikeda every February. When the storage heat was suitably quantified, the latent heat computed on a monthly basis by the model also agreed well with those calculated by both the Bowen ratio and Priestley-Taylor methods. Analysis of the heat budget for a 25-year period from 1981 to 2005 showed that the lake accumulates heat from March to August and releases it through latent and sensible heat under a small net radiation condition from September to February. Maximum latent heat occurs in October and minimum latent heat in April. The annual average evaporation is 938 mm and the autumn evaporation from September to November accounts for about 40% of the total annual evaporation.

  17. Thermoelectrical model for vertical cavity surface emitting lasers and arrays

    NASA Astrophysics Data System (ADS)

    Boiko, D. L.; Guerrero, G.; Kapon, E.

    2006-11-01

    An analytical model of thermal and electrical characteristics of vertical cavity surface emitting lasers (VCSELs) and VCSEL arrays is presented. The model is based on analytical expressions for the thermal resistance and for the I-V curve of the devices and incorporates only a few macroscopic parameters. It accounts for three-dimensional current and heat flows and provides thermo-electrical self-consistency. Good agreement between the model's predictions and the measured characteristics of InGaAs /AlGaAs VCSEL arrays is obtained.

  18. Heat Pipes For Alyeska

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The heat pipes job is to keep the arctic ground frozen. The permafrost soil alternately freezes and thaws with seasonal temperature changes causing surface dislocations and problems for the builders. In winter, a phenomenon called frost-heaving uplifts the soil. It is something like the creation of highway potholes by the freezing of rainwater below the roadbed, but frost-heaving exerts a far greater force. Thawing of the frost in the summer causes the soil to settle unevenly. Therefore it is necessary to keep the soil in a continually frozen state so the pipeline won't rupture. To solve this problem, McDonnell Douglas Corp. applied heat pipe principles in the design of the vertical supports that hold up the pipeline.

  19. Heating Saturn's Clumpy Rings

    NASA Astrophysics Data System (ADS)

    Turner, Neal J.; Morishima, Ryuji; Spilker, Linda J.

    2015-11-01

    We model Cassini CIRS data using a Monte Carlo radiative transfer -- thermal balance technique first developed for protostellar disks, with the goals of:1. Exploring whether the A- and B-ring temperatures' variation with viewing angle is consistent with the wake structures suggested by the observed azimuthal asymmetry in optical depth, by analytic arguments, and by numerical N-body modeling.2. Better constraining the shape, size, spacing and optical depths of substructure in the A-ring, using the unexpectedly high temperatures observed at equinox. If the wake features have high enough contrast, Saturn-shine may penetrate the gaps between the wakes and heat thering particles both top and bottom.3. Determining how much of the heating of the A- and B-rings' unlit sides is due to radiative transport and how much is due to particle motions, especially vertical motions. This will help in constraining the rings' surface densities and masses.

  20. Heating Structures Derived from Satellite

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Adler, R.; Haddad, Z.; Hou, A.; Kakar, R.; Krishnamurti, T. N.; Kummerow, C.; Lang, S.; Meneghini, R.; Olson, W.

    2004-01-01

    Rainfall is a key link in the hydrologic cycle and is a primary heat source for the atmosphere. The vertical distribution of latent-heat release, which is accompanied by rainfall, modulates the large-scale circulations of the tropics and in turn can impact midlatitude weather. This latent heat release is a consequence of phase changes between vapor, liquid, and solid water. The Tropical Rainfall Measuring Mission (TRMM), a joint U.S./Japan space project, was launched in November 1997. It provides an accurate measurement of rainfall over the global tropics which can be used to estimate the four-dimensional structure of latent heating over the global tropics. The distributions of rainfall and inferred heating can be used to advance our understanding of the global energy and water cycle. This paper describes several different algorithms for estimating latent heating using TRMM observations. The strengths and weaknesses of each algorithm as well as the heating products are also discussed. The validation of heating products will be exhibited. Finally, the application of this heating information to global circulation and climate models is presented.

  1. On the Vertical Structuring of Gigantic Jets

    NASA Astrophysics Data System (ADS)

    Da Silva, C.; Pasko, V. P.

    2013-12-01

    Gigantic Jets (GJs) are large-scale electrical discharges between the thundercloud tops and the lower ionosphere. It is estimated that an individual GJ can contribute as much as cloud-to-ground lightning in discharging a thunderstorm system, transferring hundreds of coulombs from thundercloud to the ionosphere [Cummer et al., Nat. Geosci., 2, 617-620, 2009]. GJs are initiated deep inside the thundercloud as intracloud lightning discharges. Owing to a charge imbalance, meaning the upper charge center is depleted with respect to the midlevel charge center, the upward-directed lightning leaders manage to escape through the thundercloud top to form GJs [Krehbiel et al., Nat. Geosci., 1, 233-237, 2008]. As a GJ leader crosses the stratosphere its streamer zone becomes longer and longer, due to the dynamics of streamer growth in a medium with exponentially-decreasing air density, such as in the Earth's atmosphere [Raizer et al., GRL, 33, L23801, 2006]. The speed at which a leader propagates is limited by the air heating of every newly formed leader section, rate of which is slower at upper altitudes in the Earth's atmosphere [da Silva and Pasko, GRL, 39, L13805, 2012]. Despite the expected deceleration of an upward-directed leader, GJs are observed to accelerate as they approach the ionosphere. To address this issue, we propose a simple time-dynamic model for GJ propagation that simulates the upward propagation of a leader discharge accounting for the effects of the expansion of its streamer zone. We propose that the GJ acceleration is a consequence of its vertical structuring and, therefore, can be used to trace the transition altitude between the leader and streamer zone sections of GJs [da Silva and Pasko, GRL, 40, 12, 3315-3319, 2013]. Leaders and streamers are very different electrical discharges in terms of the degree of ionization, temperature, and composition of the plasma inside their channels. A correct description of the vertical structuring of GJs is of fundamental importance for evaluation of their effects in the stratosphere and mesosphere.

  2. Meridional heat transport at the onset of winter stratospheric warming

    NASA Technical Reports Server (NTRS)

    Conte, M.

    1981-01-01

    A continuous vertical flow of energy toward high altitude was verified. This process produced a dynamic instability of the stratospheric polar vortex. A meridional heat transport ws primed toward the north, which generated a warming trend.

  3. Entirely passive heat pipe apparatus capable of operating against gravity

    DOEpatents

    Koenig, Daniel R. (Santa Fe, NM)

    1982-01-01

    The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 meters and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.

  4. Plasma vertical stabilisation in ITER

    NASA Astrophysics Data System (ADS)

    Gribov, Y.; Kavin, A.; Lukash, V.; Khayrutdinov, R.; Huijsmans, G. T. A.; Loarte, A.; Snipes, J. A.; Zabeo, L.

    2015-07-01

    This paper describes the progress in analysis of the ITER plasma vertical stabilisation (VS) system since its design review in 2007-2008. Two indices characterising plasma VS were studied. These are (1) the maximum value of plasma vertical displacement due to free drift that can be stopped by the VS system and (2) the maximum root mean square value of low frequency noise in the dZ/dt measurement signal used in the VS feedback loop. The first VS index was calculated using the PET code for 15 MA plasmas with the nominal position and shape. The second VS index was studied with the DINA code in the most demanding simulations for plasma magnetic control of 15 MA scenarios with the fastest plasma current ramp-up and early X-point formation, the fastest plasma current ramp-down in a divertor configuration, and an H to L mode transition at the current flattop. The studies performed demonstrate that the VS in-vessel coils, adopted recently in the baseline design, significantly increase the range of plasma controllability in comparison with the stabilising systems VS1 and VS2, providing operating margins sufficient to achieve ITER's goals specified in the project requirements. Additionally two sets of the DINA code simulations were performed with the goal of assessment of the capability of the PF system with the VS in-vessel coils: (i) to control the position of runaway electrons generated during disruptions in 15 MA scenarios and (ii) to trigger ELMs in H-mode plasmas of 7.5 MA/2.65 T scenarios planned for the early phase of ITER operation. It was also shown that ferromagnetic structures of the vacuum vessel (ferromagnetic inserts) and test blanket modules insignificantly affect the plasma VS.

  5. Numerical Simulation of Liquid Nitrogen Chilldown of a Vertical Tube

    NASA Technical Reports Server (NTRS)

    Darr, Samuel; Hu, Hong; Schaeffer, Reid; Chung, Jacob; Hartwig, Jason; Majumdar, Alok

    2015-01-01

    This paper presents the results of a one-dimensional numerical simulation of the transient chilldown of a vertical stainless steel tube with liquid nitrogen. The direction of flow is downward (with gravity) through the tube. Heat transfer correlations for film, transition, and nucleate boiling, as well as critical heat flux, rewetting temperature, and the temperature at the onset of nucleate boiling were used to model the convection to the tube wall. Chilldown curves from the simulations were compared with data from 55 recent liquid nitrogen chilldown experiments. With these new correlations the simulation is able to predict the time to rewetting temperature and time to onset of nucleate boiling to within 25% for mass fluxes ranging from 61.2 to 1150 kg/(sq m s), inlet pressures from 175 to 817 kPa, and subcooled inlet temperatures from 0 to 14 K below the saturation temperature.

  6. Natural convection in a vertical enclosure with internal permeable screen

    SciTech Connect

    Zhang, Z.; Bejan, A.; Lage, J.L. )

    1991-05-01

    This paper documents the thermal insulation effect of a screen installed inside a vertical rectangular enclosure (e.g., double-glazed window). The screen is a venetian blind system made out of horizontal strips that can be rotated. The focus is on the closed position, where the strips almost touch. The effect of this permeable screen on the temperature field, the flow field, and the overall heat transfer rate is determined numerically. The study shows that there exists a ceiling (critical) conductance for the air leakage through the screen, above which the screen does not cause a significant drop in the overall heat transfer rate. A numerical example shows how this critical conductance can be used to calculate the critical spacing that can be tolerated between two consecutive strips in the screen.

  7. Monitoring soil water content by vertical temperature variations.

    PubMed

    Bechkit, Mohamed Amine; Flageul, Sébastien; Guerin, Roger; Tabbagh, Alain

    2014-01-01

    The availability of high sensitivity temperature sensors (0.001 K sensitivity platinum resistors), which can be positioned at intervals of a few centimeters along a vertical profile in the unsaturated zone, allows short-term in situ determinations-one day or even less-of the thermal diffusivity. The development of high data storage capabilities also makes this possible over long periods and the relative variations in thermal diffusivity allow the monitoring of the variations in water content. The processing of temperature measurements recorded at different depths is achieved by solving the heat equation, using the finite elements method, with both conductive and convective heat transfers. A first set of measurements has allowed this approach to be validated. Water content variations derived from thermal diffusivity values are in excellent agreement with TDR measurements carried out on the experimental site at Boissy-le-Châtel (Seine et Marne, France). PMID:23834312

  8. Induction electrohydrodynamic pump in a vertical configuration: Part 1 - Theory

    SciTech Connect

    Seyed-Yagoobi, J. ); Chato, J.C.; Crowley, J.M.; Krein, P.T. )

    1989-08-01

    An induction electrohydrodynamic (EHD) pump in an axisymmetric, vertical configuration is studied theoretically. The model includes the effect of entrance conditions, buoyancy effects, secondary flow, and Joule heating. Primarily the forward (cooled wall) and to a lesser extent the backward (heated wall) modes are investigated. A finite difference technique is used to obtain the numerical solutions. A set of these solutions is presented to show the influence of the controlling factors of operating an induction EHD pump. The results indicate that the entrance temperature profile plays an important role in the operation of the pump because steeper profiles produce higher velocities. The pump must be operated at an optimum frequency, wavelength, and electric conductivity level.

  9. The vertical file enters the electronic age.

    PubMed

    Carleton, M O; Cheves, C G

    1989-01-01

    Vertical files are revered institutions in many libraries. The reference staff at the Spencer S. Eccles Health Sciences Library at the University of Utah automated their vertical file and made the information in it accessible via the Library's Integrated Library System. Medical Subject Headings (MeSH) were applied to vertical files and simple records leading to them were entered in the Library's online catalog. Electronic access to the vertical file increases the availability of concepts too new to be in medical books and permits the Library to meet the needs of lay patrons searching for basic information on popular health care topics. PMID:10296845

  10. Energy, Exergy and Uncertainty Analyses of the Thermal Response Test for a Ground Heat Exchanger

    E-print Network

    Al-Shayea, Naser Abdul-Rahman

    1 Energy, Exergy and Uncertainty Analyses of the Thermal Response Test for a Ground Heat Exchanger response test of a ground heat exchanger. In this study, a vertical U-shaped ground heat exchanger with 80 of the ground heat exchanger. The thermal response test was carried out four times at different thermal loads

  11. 10 CFR 431.92 - Definitions concerning commercial air conditioners and heat pumps.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... applications; rated for sensible coefficient of performance (SCOP) and tested in accordance with 10 CFR 431.96... utilizes reverse cycle refrigeration as its prime heat source, that has a supplementary heat source..., but may not include reverse cycle refrigeration as a heating means. Single package vertical heat...

  12. On the conservation of the vertical action on galactic disks

    E-print Network

    Vera-Ciro, Carlos

    2015-01-01

    We employ high-resolution N-body simulations of isolated spiral galaxy models, from low-amplitude multi-armed to Milky Way-like disks to estimate the vertical action of ensembles of stars in an axisymmetrical potential. In the multi-armed galaxy the low-amplitude arms represent tiny perturbations of the potential, hence the vertical action for a set of stars is conserved, although after several orbital periods of revolution the conservation degrades significantly. For a Milky Way-like galaxy with vigorous spiral activity and the formation of a bar, our results show that the potential is far from steady, implying that the action is not a constant of motion. Furthermore, because of the presence of high-amplitude arms and the bar, considerable in-plane and vertical heating occurs that forces stars to deviate from near-circular orbits, challenging the validity of the epicycle approximation not only for individual stars, in agreement with previous results, but also for ensembles of stars. If confirmed, this result...

  13. Convective instabilities in a rotating vertical Hele-Shaw cell

    NASA Astrophysics Data System (ADS)

    Zhang, Keke; Liao, Xinhao; Zhan, Xiaoya; Zhu, Rixiang

    2006-12-01

    Convective instabilities driven by vertical buoyancy in a Boussinesq fluid in a rotating vertical Hele-Shaw cell, a long channel with rectangular cross section of finite height h and small width ?h with ? ?1, are investigated both analytically and numerically. The problem is characterized by the Taylor number T, the Rayleigh number R, and the aspect ratio ?. Explicit asymptotic solutions describing convective instabilities are derived for ?T1/6?1, where T is assumed to be large compared to unity. Comparison between the asymptotic and fully numerical solutions shows a satisfactory quantitative agreement. It is found that an overall condition for convective instabilities becomes optimal when ?T1/6=O (1). Direct three-dimensional simulations for strongly nonlinear convection are also carried out in the regime 0<(R-Rc)/Rc?O(10), where Rc denotes the critical Rayleigh number. As a consequence of both the geometric and dynamic constraints imposed by the narrow channel (geometric) and rapid rotation (dynamic), the nonlinear flow remains temporally stationary and spatially simple and is comprised primarily of vertically long thin convection cells that transport heat all the way from the bottom to the top of the channel.

  14. Modeling and experimental study of nucleate boiling on a vertical array of horizontal plain tubes

    SciTech Connect

    Ribatski, Gherhardt; Saiz Jabardo, Jose M.

    2008-09-15

    An investigation of nucleate boiling on a vertical array of horizontal plain tubes is presented in this paper. Experiments were performed with refrigerant R123 at reduced pressures varying from 0.022 to 0.64, tube pitch to diameter ratios of 1.32, 1.53 and 2.00, and heat fluxes from 0.5 to 40 kW/m{sup 2}. Brass tubes with external diameters of 19.05 mm and average roughness of 0.12 {mu}m were used in the experiments. The effect of the tube spacing on the local heat transfer coefficient along the tube array was negligible within the present range of experimental conditions. For partial nucleate boiling, characterized by low heat fluxes, and low reduced pressures, the tube positioning shows a remarkable effect on the heat transfer coefficient. Based on these data, a general correlation for the prediction of the nucleate boiling heat transfer coefficient on a vertical array of horizontal tubes under flooded conditions was proposed. According to this correlation, the ratio between the heat transfer coefficients of a given tube and the lowest tube in the array depends only on the tube row number, the reduced pressure and the heat flux. By using the proposed correlation, most of the experimental heat transfer coefficients obtained in the present study were predicted within {+-}15%. The new correlation compares reasonably well with independent data from the literature. (author)

  15. Vertical diffusivities of active and passive tracers

    NASA Astrophysics Data System (ADS)

    Canuto, V. M.; Cheng, Y.; Howard, A. M.

    The climate models that include a carbon-cycle need the vertical diffusivity of a passive tracer. Since an expression for the latter is not available, it has been common practice to identify it with that of salt. The identification is questionable since T, S are active, not passive tracers. We present the first derivation of the diffusivity of a passive tracer in terms of Ri (Richardson number) and R ? (density ratio, ratio of salinity over temperature z-gradients). The following results have emerged: The passive tracer diffusivity is an algebraic function of Ri, R ?. In doubly stable regimes (DS, ? T/?z > 0, ?S/? z < 0), the passive scalar diffusivity is nearly the same as that of salt/heat for any values of R ? < 0 and Ri > 0. In DC regimes (diffusive convection, ? T/? z < 0, ? S/? z < 0, R ? > 1), the passive scalar diffusivity is larger than that of salt. At Ri = O(1), it can be more than twice as large. In SF regimes (salt fingers, ? T/? z > 0, ? S/? z > 0, R ? < 1), the passive scalar diffusivity is smaller than that of salt. At Ri = O(1), it can be less than half of it. The passive tracer diffusivity predicted at the location of NATRE (North Atlantic Tracer Release Experiment) is discussed. Perhaps the most relevant conclusion is that the common identification of the tracer diffusivity with that of salt is valid only in DS regimes. In the Southern Ocean, where there is the largest CO 2 absorption, the dominant regime is diffusive convection discussed in (c) above.

  16. Vertical Diffusivities of Active and Passive Tracers

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Cheng, Y.; Howard, A. M.

    2010-01-01

    The climate models that include a carbon-cycle need the vertical diffusivity of a passive tracer. Since an expression for the latter is not available, it has been common practice to identify it with that of salt. The identification is questionable since T, S are active, not passive tracers. We present the first derivation of the diffusivity of a passive tracer in terms of Ri (Richardson number) and Rq (density ratio, ratio of salinity over temperature z-gradients). The following results have emerged: (a) The passive tracer diffusivity is an algebraic function of Ri, Rq. (b) In doubly stable regimes (DS, partial derivative of T with respect to z > 0, partial derivative of S with respect to z < 0), the passive scalar diffusivity is nearly the same as that of salt/heat for any values of Rq < 0 and Ri > 0. (c) In DC regimes (diffusive convection, partial derivative of T with respect to z < 0, partial derivative of S with respect to z < 0, Rq > 1), the passive scalar diffusivity is larger than that of salt. At Ri = O(1), it can be more than twice as large. (d) In SF regimes (salt fingers, partial derivative of T with respect to z > 0, partial derivative of S with respect to z > 0, Rq < 1), the passive scalar diffusivity is smaller than that of salt. At Ri = O(1), it can be less than half of it. (e) The passive tracer diffusivity predicted at the location of NATRE (North Atlantic Tracer Release Experiment) is discussed. (f) Perhaps the most relevant conclusion is that the common identification of the tracer diffusivity with that of salt is valid only in DS regimes. In the Southern Ocean, where there is the largest CO2 absorption, the dominant regime is diffusive convection discussed in (c) above.

  17. Heat Pipes

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Phoenix Refrigeration Systems, Inc.'s heat pipe addition to the Phoenix 2000, a supermarket rooftop refrigeration/air conditioning system, resulted from the company's participation in a field test of heat pipes. Originally developed by NASA to control temperatures in space electronic systems, the heat pipe is a simple, effective, heat transfer system. It has been used successfully in candy storage facilities where it has provided significant energy savings. Additional data is expected to fully quantify the impact of the heat pipes on supermarket air conditioning systems.

  18. Vertical Structure of Magnetized Accretion Disks Around Young Stars

    NASA Astrophysics Data System (ADS)

    Tapia, Carlos; Lizano, Susana

    2016-01-01

    We model the vertical structure of magnetized accretion disks subject to viscous and resistive heating, and irradiation by the central star. We apply our formalism to the radial structure of magnetized accretion disks threaded by a poloidal magnetic field dragged during the process of star formation developed by Shu and coworkers. We consider disks around low mass protostars, T Tauri, and FU Orionis stars. We consider two levels of disk magnetization, ?sys = 4 (strongly magnetized disks), and ?sys = 12 (weakly magnetized disks). The rotation rates of strongly magnetized disks have large deviations from Keplerian rotation. In these models, resistive heating dominates the thermal structure for the FU Ori disk. The T Tauri disk is very thin and cold because it is strongly compressed by magnetic pressure; it may be too thin compared with observations. Instead, in the weakly magnetized disks, rotation velocities are close to Keplerian, and resistive heating is always less than 7% of the viscous heating. In these models, the T Tauri disk has a larger aspect ratio, consistent with that inferred from observations. All the disks have spatially extended hot atmospheres where the irradiation flux is absorbed, although most of the mass (~ 90 - 95 %) is in the disk midplane.

  19. INVESTIGATING THERMODYNAMICS OF VERTICAL ATMOSPHERIC ENERGY TRANSPORT

    E-print Network

    INVESTIGATING THERMODYNAMICS OF VERTICAL ATMOSPHERIC ENERGY TRANSPORT Wei Wu and Yangang Liu National Laboratory P.O. Box, Upton, NY www.bnl.gov ABSTRACT Thermodynamics of vertical atmospheric energy. Potential thermodynamic constraint(s) for the Earth's climate system are also explored from these simple

  20. A Vertically Resolved Planetary Boundary Layer

    NASA Technical Reports Server (NTRS)

    Helfand, H. M.

    1984-01-01

    Increase of the vertical resolution of the GLAS Fourth Order General Circulation Model (GCM) near the Earth's surface and installation of a new package of parameterization schemes for subgrid-scale physical processes were sought so that the GLAS Model GCM will predict the resolved vertical structure of the planetary boundary layer (PBL) for all grid points.

  1. Cooling Requirements for the Vertical Shear Instability in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Lin, Min-Kai; Youdin, Andrew N.

    2015-09-01

    The vertical shear instability (VSI) offers a potential hydrodynamic mechanism for angular momentum transport in protoplanetary disks (PPDs). The VSI is driven by a weak vertical gradient in the disk’s orbital motion, but must overcome vertical buoyancy, a strongly stabilizing influence in cold disks, where heating is dominated by external irradiation. Rapid radiative cooling reduces the effective buoyancy and allows the VSI to operate. We quantify the cooling timescale tc needed for efficient VSI growth, through a linear analysis of the VSI with cooling in vertically global, radially local disk models. We find the VSI is most vigorous for rapid cooling with {t}{{c}}\\lt {{{? }}}{{K}}-1h| q| /(? -1) in terms of the Keplerian orbital frequency, {{{? }}}{{K}}, the disk’s aspect-ratio, h\\ll 1, the radial power-law temperature gradient, q, and the adiabatic index, ?. For longer tc, the VSI is much less effective because growth slows and shifts to smaller length scales, which are more prone to viscous or turbulent decay. We apply our results to PPD models where tc is determined by the opacity of dust grains. We find that the VSI is most effective at intermediate radii, from ?5 to ?50 AU with a characteristic growth time of ?30 local orbital periods. Growth is suppressed by long cooling times both in the opaque inner disk and the optically thin outer disk. Reducing the dust opacity by a factor of 10 increases cooling times enough to quench the VSI at all disk radii. Thus the formation of solid protoplanets, a sink for dust grains, can impede the VSI.

  2. Absorption of Water Vapor by LiBr Aqueous Solution in a Vertical Smooth Tube

    NASA Astrophysics Data System (ADS)

    Takamatsu, Hiroshi; Yamashiro, Hikaru; Takata, Nobuo; Nakayama, Takeru; Honda, Hiroshi

    Heat and mass transfer in a vertical in-tube absorber is studied experimentally using LiBr aqueous solution. The water vapor is absorbed by the liquid falling inside a smooth copper tube (16.05 mm I.D.,400 mm long) that is cooled on its outside with water flowing counter-currently. The presented results include the effect of solution flow rate, solution subcooling and cooling water temperature on the heat transfer rate, absorption rate and pressure drop in the absorber. Discussion is also presented on the heat and mass transfer coefficients that are defined by estimated temperature and concentration at the vapor-liquid interface.

  3. Thermal interaction between free convection and forced convection along a vertical conducting wall

    E-print Network

    Shu, Jian-Jun

    2015-01-01

    A theoretical study is presented in this paper to investigate the conjugate heat transfer across a vertical finite wall separating two forced and free convection flows at different temperatures. The heat conduction in the wall is in the transversal direction and countercurrent boundary layers are formed on the both sides of the wall. The governing equations of this problem and their corresponding boundary conditions are all cast into a dimensionless form by using a non-similarity transformation. These resultant equations with multiple singular points are solved numerically using a very efficient singular perturbation method. The effects of the resistance parameters and Prandtl numbers on heat transfer characteristics are investigated.

  4. Inclusion of Vertical Dynamics in Vertically-integrated Models for CO2 Storage

    NASA Astrophysics Data System (ADS)

    Guo, B.; Bandilla, K.; Celia, M. A.

    2012-12-01

    Mathematical models of different complexity are needed to answer a range of questions for geological sequestration of carbon dioxide (CO2). One category of simplified models is based on vertical integration, which reduces the three-dimensional problem to two dimensions. Usually, these models assume that brine and CO2 are in vertical equilibrium. This type of model is useful and accurate for simulation times that are large relative to the time for buoyant segregation. But, vertical-equilibrium models are inappropriate in some situations, for instance, in the early stage of injection, when brine and CO2 have not fully segregated. Therefore, for these situations, the vertical equilibrium assumption needs to be relaxed and vertical dynamics needs to be included in the governing equations. To avoid significant increases of computational effort due to the inclusion of vertical dynamics, a multi-scale algorithm can be constructed where the vertically integrated equations are still used to model the (dominant) horizontal flow processes with the vertical reconstruction included as a dynamic problem. Such an approach allows each vertical column of grid cells to be solved independently, as a one-dimensional problem, during the dynamic reconstruction step. Because the top and bottom boundaries usually correspond to impermeable caprock, the total flow for these one-dimensional problems is zero and counter-current flow driven only by buoyancy and capillarity is involved. Solutions for this kind of problem are relatively simple and require little computational effort. With careful coupling between the vertical calculations and the horizontally integrated equations, an efficient algorithm can be developed to simulate a fairly wide range of problems including those with significant vertical dynamics. When vertical dynamics become insignificant, then usual vertical equilibrium reconstruction is used in the vertically integrated models. This new algorithm provides an intermediate choice in model complexity between full three-dimensional models and vertical-equilibrium two-dimensional models.

  5. Role of vertical mixing originating from small vertical scale structures above and within the equatorial thermocline in an OGCM

    NASA Astrophysics Data System (ADS)

    Sasaki, Wataru; Richards, Kelvin J.; Luo, Jing-Jia

    2012-11-01

    Recent high vertical resolution measurements show small vertical scale structures (SVSs) are present in the flow above and within the equatorial thermocline and that these structures contribute significantly to ocean mixing. The SVSs are typically unresolved in OGCMs and thus their impact needs to be parameterized. We investigate the impact of the mixing induced by the SVSs on the state of the equatorial Pacific in an ocean general circulation model (OGCM). As a first step to determine the importance of the SVS induced mixing we introduce an enhanced mixing within and above the equatorial thermocline. It is found that this enhanced mixing reduces the stratification above the thermocline, and sharpens the thermocline through the Phillips effect. The sharpened thermocline limits the exchange of heat across the thermocline and traps the surface heating above the thermocline. The reduced stratification leads to less cooling of the mixed layer through entrainment, a reduced annual cycle and an increase in the annual mean of the sea surface temperature (SST) in the eastern equatorial cold tongue. The depth dependency in enhanced SVS mixing is crucial to its impact; when the enhanced mixing is applied throughout the depth of the ocean (as has been done usually in previous studies,) the cold tongue SST is cooled further. In the western equatorial Pacific, where the thermocline is deeper, SVS enhanced mixing induces a colder SST. We also find that the SVS mixing reduces the eddy kinetic energy associated with the tropical instability waves through a reduction of the meridional and vertical shear of the equatorial currents and temperature gradient.

  6. Dust vertical profile impact on global radiative forcing estimation using a coupled chemical-transport-radiative-transfer model

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Li, Q. B.; Gu, Y.; Liou, K. N.; Meland, B.

    2013-07-01

    Atmospheric mineral dust particles exert significant direct radiative forcings and are important drivers of climate and climate change. We used the GEOS-Chem global three-dimensional chemical transport model (CTM) coupled with the Fu-Liou-Gu (FLG) radiative transfer model (RTM) to investigate the dust radiative forcing and heating rate based on different vertical profiles for April 2006. We attempt to actually quantify the sensitivities of radiative forcing to dust vertical profiles, especially the discrepancies between using realistic and climatological vertical profiles. In these calculations, dust emissions were constrained by observations of aerosol optical depth (AOD). The coupled calculations utilizing a more realistic dust vertical profile simulated by GEOS-Chem minimize the physical inconsistencies between 3-D CTM aerosol fields and the RTM. The use of GEOS-Chem simulated vertical profile of dust extinction, as opposed to the FLG prescribed vertical profile, leads to greater and more spatially heterogeneous changes in the estimated radiative forcing and heating rate produced by dust. Both changes can be attributed to a different vertical structure between dust and non-dust source regions. Values of the dust vertically resolved AOD per grid level (VRAOD) are much larger in the middle troposphere, though smaller at the surface when the GEOS-Chem simulated vertical profile is used, which leads to a much stronger heating rate in the middle troposphere. Compared to the FLG vertical profile, the use of GEOS-Chem vertical profile reduces the solar radiative forcing at the top of atmosphere (TOA) by approximately 0.2-0.25 W m-2 over the African and Asian dust source regions. While the Infrared (IR) radiative forcing decreases 0.2 W m-2 over African dust belt, it increases 0.06 W m-2 over the Asian dust belt when the GEOS-Chem vertical profile is used. Differences in the solar radiative forcing at the surface between the use of the GEOS-Chem and FLG vertical profiles are most significant over the Gobi desert with a value of about 1.1 W m-2. The radiative forcing effect of dust particles is more pronounced at the surface over the Sahara and Gobi deserts by using FLG vertical profile, while it is less significant over the downwind area of Eastern Asia.

  7. Elevated aerosols and role of circulation parameters in aerosol vertical distribution

    NASA Astrophysics Data System (ADS)

    Prijith, S. S.; Aloysius, Marina; Mohan, Mannil; Rao, P. V. N.

    2016-01-01

    The study examines aerosol loading in different vertical layers of the atmosphere and explores the role of atmospheric circulation parameters in vertical distribution of aerosols and in its seasonal variability. Aerosol vertical distribution over the globe is examined, using long term satellite observations, by considering aerosol loading in different layers of atmosphere upto ?6 km altitudes from surface and fractional contribution of each of these layers to total columnar aerosol loading. Aerosols are observed residing close to the surface in most of the oceanic environments, except over certain regions which are in the close proximity of continents where upper level winds are conducive for long range aerosol transport. In contrast, considerable vertical spread in aerosol distribution with strong seasonal variability, minimum occurring in winter months and maximum in summer, is observed over the continental regions. Vertical spread in aerosol distribution is observed highest over north eastern and north western parts of Africa during northern hemispheric summer, when the convection activity peaks over these regions due to large solar insolation and associated surface heating. Seasonal variation of aerosol vertical spread over both of these regions is observed in phase with variation in atmospheric convergence and vorticity. During summer months, when the aerosol vertical spread is highest, strong surface level convergence and associated cyclonic vorticity is observed along with an upper level (700-600 hPa) divergence. The surface level convergence and upper level divergence together induce an upward flow of air which carries aerosols from ground to higher altitudes. This mechanism of aerosol vertical transport is further corroborated through the correlation and regression relations of surface convergence/vorticity with aerosol loading above different elevations and hence the study reveals role of circulation parameters in aerosol vertical distribution.

  8. Advanced Si solid phase crystallization for vertical channel in vertical NANDs

    SciTech Connect

    Lee, Sangsoo; Son, Yong-Hoon; Hwang, Kihyun; Shin, Yoo Gyun; Yoon, Euijoon

    2014-07-01

    The advanced solid phase crystallization (SPC) method using the SiGe/Si bi-layer structure is proposed to obtain high-mobility poly-Si thin-film transistors in next generation vertical NAND (VNAND) devices. During the SPC process, the top SiGe thin film acts as a selective nucleation layer to induce surface nucleation and equiaxial microstructure. Subsequently, this SiGe thin film microstructure is propagated to the underlying Si thin film by epitaxy-like growth. The initial nucleation at the SiGe surface was clearly observed by in situ transmission electron microscopy (TEM) when heating up to 600?°C. The equiaxial microstructures of both SiGe nucleation and Si channel layers were shown in the crystallized bi-layer plan-view TEM measurements. Based on these experimental results, the large-grained and less-defective Si microstructure is expected to form near the channel region of each VNAND cell transistor, which may improve the electrical characteristics.

  9. Advanced Si solid phase crystallization for vertical channel in vertical NANDs

    NASA Astrophysics Data System (ADS)

    Lee, Sangsoo; Son, Yong-Hoon; Hwang, Kihyun; Shin, Yoo Gyun; Yoon, Euijoon

    2014-07-01

    The advanced solid phase crystallization (SPC) method using the SiGe/Si bi-layer structure is proposed to obtain high-mobility poly-Si thin-film transistors in next generation vertical NAND (VNAND) devices. During the SPC process, the top SiGe thin film acts as a selective nucleation layer to induce surface nucleation and equiaxial microstructure. Subsequently, this SiGe thin film microstructure is propagated to the underlying Si thin film by epitaxy-like growth. The initial nucleation at the SiGe surface was clearly observed by in situ transmission electron microscopy (TEM) when heating up to 600 °C. The equiaxial microstructures of both SiGe nucleation and Si channel layers were shown in the crystallized bi-layer plan-view TEM measurements. Based on these experimental results, the large-grained and less-defective Si microstructure is expected to form near the channel region of each VNAND cell transistor, which may improve the electrical characteristics.

  10. Sonic Anemometer Vertical Wind Speed Measurement Errors

    NASA Astrophysics Data System (ADS)

    Kochendorfer, J.; Horst, T. W.; Frank, J. M.; Massman, W. J.; Meyers, T. P.

    2014-12-01

    In eddy covariance studies, errors in the measured vertical wind speed cause errors of a similar magnitude in the vertical fluxes of energy and mass. Several recent studies on the accuracy of sonic anemometer measurements indicate that non-orthogonal sonic anemometers used in eddy covariance studies underestimate the vertical wind speed. It has been suggested that this underestimation is caused by flow distortion from the interference of the structure of the anemometer itself on the flow. When oriented ideally with respect to the horizontal wind direction, orthogonal sonic anemometers that measure the vertical wind speed with a single vertically-oriented acoustic path may measure the vertical wind speed more accurately in typical surface-layer conditions. For non-orthogonal sonic anemometers, Horst et al. (2014) proposed that transducer shadowing may be a dominant factor in sonic flow distortion. As the ratio of sonic transducer diameter to path length and the zenith angle of the three transducer paths decrease, the effects of transducer shadowing on measurements of vertical velocity will decrease. An overview of this research and some of the methods available to correct historical data will be presented.

  11. Curved motions in horizontal and vertical orientations.

    PubMed

    Phillips, J G; Ogeil, R P

    2010-10-01

    A consideration of handwriting demonstrates that motions can be remarkably constant, even when performed with different effectors. Nevertheless, the transposition of writing from horizontal to vertical orientations, as occurs when writing on blackboards, poses additional problems for the constraint of movement. Motions in horizontal and vertical planes potentially challenge the mechanisms responsible for motor constancy. Gravitational fields impose different accelerative forces on vertical (up/down) compared with horizontal (left/right) motions. A 1/3 power law linking tangential velocity and radius of curvature is sometimes invoked to explain how equivalent motions can be performed by different effectors. To evaluate the operation of the power law when movements are performed in different orientations, 12 participants drew ellipses in horizontal and vertical planes at about 1 or 2 Hz. Mean tangential velocity, radius of curvature and the strength of the 1/3 power law were analyzed. The power law was strongest for curved motions at faster speeds. The power law was weakest at slower speeds in the vertical orientation. As participants controlled their movement periodicity, this placed tighter constraints upon curvature in the vertical orientations than the horizontal orientations. Speed of motion had a greater effect upon curvatures in the horizontal than the vertical orientation. The data offer insights into variations in the strength of the power law under different orientations, and indicate a limited role for the 1/3 power law in motor constancy. PMID:20800304

  12. Mesospheric heating due to intense tropospheric convection

    NASA Technical Reports Server (NTRS)

    Taylor, L. L.

    1979-01-01

    A series of rocket measurements made twice daily at Wallops Island, Va., revealed a rapid heating of the mesosphere on the order of 10 K on days when thunderstorms or squall lines were in the area. This heating is explained as the result of frictional dissipation of vertically propagating internal gravity waves generated by intense tropospheric convection. Ray-tracing theory is used to determine the spectrum of gravity wave groups that actually reach mesospheric heights. This knowledge is used in an equation describing the spectral energy density of a penetrative convective element to calculate the fraction of the total energy initially available to excite those waves that do reach the level of heating. This value, converted into a vertical velocity, is used as the lower boundary condition for a multilayer model used to determine the detailed structure of the vertically propagating waves. The amount of frictional dissipation produced by the waves is calculated from the solutions of the frictionless model by use of a vertically varying eddy viscosity coefficient. The heating produced by the dissipation is then calculated from the thermodynamic equation.

  13. Evaluation of Generation Mechanism of Vertical Cracks in Top Coat of TBCs During APS Deposition by Laser AE Method

    NASA Astrophysics Data System (ADS)

    Ito, K.; Kuriki, H.; Araki, H.; Kuroda, S.; Enoki, M.

    2015-06-01

    Vertical cracks can be generated in the top coat of thermal barrier coatings (TBCs) deposited by atmospheric plasma spraying (APS). Since they are known to improve the durability of TBCs such as in the case of dense vertically cracked TBC, clarification of the mechanism and the criteria of cracking are very important. In this study, generation of such vertical cracks was monitored during APS process by laser acoustic emission (AE) method, which is an in situ, non-contact, and non-destructive technique. Temperature was also monitored inside and on the surface of a specimen during APS process for estimation of the temperature field in the top coat. Results of the AE and temperature monitoring were combined to evaluate the relationship between cracking and thermal stress in the top coat. Most of the AE events due to the generation of vertical cracks were detected during rapid heating of the surface of the top coat by the heat flux from the torch. It showed that the vertical cracks were induced due to the tensile stress caused by the temperature difference in the top coat from the rapid heating. Furthermore, the estimated critical thermal stress for vertical cracking from the monitoring results was consistent with a previously reported strength of YSZ coating deposited by thermal spray.

  14. Effects of vertical rotation on Arabidopsis development

    NASA Technical Reports Server (NTRS)

    Brown, A. H.; Chapman, D. K.; Dahl, A. O.

    1975-01-01

    Various gross morphological end points of Arabidopsis development are examined in an attempt to separate the effects of growth on the horizontal clinostat into a component caused by rotation alone and another component caused by the altered position with respect to the direction of the g-vector. In a series of tests which involved comparisons between vertical stationary plants, vertical rotated plants, and plants rotated on clinostats, certain characters were consistently influenced by vertical rotation alone. The characters for which this effect was statistically significant were petiole length and leaf blade width.

  15. Study of the Heat-Transfer Processes of Tubular Elements of Ground Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Kusaiynov, K.; Shuyushbayeva, N. N.; Shaimerdenova, K. M.; Nurgalieva, Zh. G.; Omarov, N. N.

    2015-05-01

    In this paper, consideration is given to the efficiency of utilization of the low-potential heat of the ground. Also, the advantages and distinctive features of polyethylene tubes used in vertical tubular elements of heat pumps are described. This paper gives the results of investigation of the heat transfer of tubular elements of ground heat exchangers. The dependences of the temperature distributions in the ground in the vicinity of a tube and the change in the temperature with time in dry and moist grounds are determined.

  16. Response of the mesoscale atmosphere to diabatic heating

    NASA Technical Reports Server (NTRS)

    Robertson, F. R.

    1985-01-01

    A study was initiated to determine the influence of convective latent heat release/diabatic heating on the production of kinetic energy during AVE/SESAME I. The primary focus has been on the relative importance of thermally forced modification of the wind field through thickness and height gradient changes versus inertial-advective effects via the diabatic component of vertical motion. Preliminary results have shown that because of the strong vertical shear over the convective region, ageostrophic response is primarily caused by the latter process. The diagnostic parameterization of convective heating has been extended for use in conjunction with satellite precipitation estimates in data-poor oceanic regions. An initial application was made to a mesoscale convective system embedded in the South Pacific convergence zone. Comparison to the heating field diagnosed as a residual in the thermodynamic equation using the ECMWF III-b analyses showed that the methodology will be useful in explaining the observed heating fields and determining the relative contribution of moist processes to the total diabatic heating. Research activities are now concentrated in the following areas: (1) Determining the sensitivity of vertical heating profiles to partitioning of gridscale versus convective precipitation; (2) assessing the possible effects of incorrect analyzed gridscale vertical motions on residuals in the heat budgets computed with the ECMWF III-b data sets.

  17. Heating and Large Scale Dynamics of the Solar Corona

    NASA Technical Reports Server (NTRS)

    Schnack, Dalton D.

    2000-01-01

    The effort was concentrated in the areas: coronal heating mechanism, unstructured adaptive grid algorithms, numerical modeling of magnetic reconnection in the MRX experiment: effect of toroidal magnetic field and finite pressure, effect of OHMIC heating and vertical magnetic field, effect of dynamic MESH adaption.

  18. Investigation of the heat pipe arrays for convective electronic cooling 

    E-print Network

    Howard, Alicia Ann Harris

    1993-01-01

    A combined experimental and analytical investigation was conducted to evaluate a heat pipe convective cooling device consisting of sixteen small copper/water heat pipes mounted vertically in a 4x4 array 25.4 mm square. The analytical portion...

  19. Heat stroke.

    PubMed

    Leon, Lisa R; Bouchama, Abderrezak

    2015-04-01

    Heat stroke is a life-threatening condition clinically diagnosed as a severe elevation in body temperature with central nervous system dysfunction that often includes combativeness, delirium, seizures, and coma. Classic heat stroke primarily occurs in immunocompromised individuals during annual heat waves. Exertional heat stroke is observed in young fit individuals performing strenuous physical activity in hot or temperature environments. Long-term consequences of heat stroke are thought to be due to a systemic inflammatory response syndrome. This article provides a comprehensive review of recent advances in the identification of risk factors that predispose to heat stroke, the role of endotoxin and cytokines in mediation of multi-organ damage, the incidence of hypothermia and fever during heat stroke recovery, clinical biomarkers of organ damage severity, and protective cooling strategies. Risk factors include environmental factors, medications, drug use, compromised health status, and genetic conditions. The role of endotoxin and cytokines is discussed in the framework of research conducted over 30 years ago that requires reassessment to more clearly identify the role of these factors in the systemic inflammatory response syndrome. We challenge the notion that hypothalamic damage is responsible for thermoregulatory disturbances during heat stroke recovery and highlight recent advances in our understanding of the regulated nature of these responses. The need for more sensitive clinical biomarkers of organ damage is examined. Conventional and emerging cooling methods are discussed with reference to protection against peripheral organ damage and selective brain cooling. PMID:25880507

  20. Heat Problems.

    ERIC Educational Resources Information Center

    Connors, G. Patrick

    Heat problems and heat cramps related to jogging can be caused by fluid imbalances, medications, dietary insufficiency, vomiting or diarrhea, among other factors. If the condition keeps reoccurring, the advice of a physician should be sought. Some preventive measures that can be taken include: (1) running during the cooler hours of the day; (2)…

  1. On the vertical thermal structure of Io's atmosphere

    NASA Technical Reports Server (NTRS)

    Strobel, Darrell F.; Zhu, Xun; Summers, Michael F.

    1994-01-01

    A radiative-thermal conduction model for the vertical thermal structure of Io's atmosphere is developed with solar heating by SO2 absorption in UV and near-IR bands and non-local thermodynamic equilibrium (LTE) cooling by SO2 nu(sub 1), nu(sub 2), nu(sub 3), vibrational bands and rotational lines. The model predicts the existence of a mesopause in Io's atmosphere when the surface pressure exceeds approximately 10 nbar. The radiative time constant for establishing a mesosphere/mesopause on Io is only approximately 20 min, whereas the thermospheric radiative time constant is about 1 hr. These time constants are significantly shorter than the diurnal time scale and competitive with dynamic time scales. In the thermosphere when solar UV heating dominates, the asymptotic thermospheric temperature is approximately 270 K, only 140 K greater than the surface temperature because at high altiudes non-LTE cooling by SO2 rotation lines exceeds cooling in the nu(sub 2) virbrational band. Solar-heating-only modles are incapable of generating warm enough atmospheres to satisfy the observational inferences from UV and especially millimeter-wave meausrements. Joule heating driven by the penetration of Jupiter's corotational electric field into Io's conducting ionosphere is demonstrated to be the dominant heating mechanism in the subnanobar regions of Io's atmosphere with tempertures ranging from 150 to 1000 K as a function of decreasing pressure from 1 to 0.1 nbar, The asymoptotic thermospheric temperature can attain a value as high as 1800 K.

  2. Heat transfer characteristics of two-phase thermosyphon heat pipe. I - Boiling heat transfer correlation in heating section

    NASA Astrophysics Data System (ADS)

    Kaminaga, Fumito; Okamoto, Yoshizo

    1992-08-01

    A correlation for the boiling heat transfer coefficient in the heating section of a two-phase thermosyphon heat pipe is developed in comparison with experimental data. The experiments are conducted for a vertically oriented thermosyphon pipe using three kinds of working fluid, water, Feron R 113, and ethanol, at a wide pressure range of 0.1 to 20 bar and a fill charge rate of 0.3 to 0.9. The correlation is obtained by modification of Kutateladze's nucleate boiling correlation in terms of an additional two parameters, the density ratio of liquid and vapor and the surface roughness. The correlation is shown to be in good agreement with the experimental data at a system pressure above 1 bar. The experiments also indicate that the adiabatic wall temperature is less than the saturation temperature corresponding to the system pressure in the pipe.

  3. Nonlinear Saturation of Vertically Propagating Rossby Waves

    E-print Network

    Giannitsis, Constantine

    The interaction between vertical Rossby wave propagation and wave breaking is studied in the idealized context of a beta-plane channel model. Considering the problem of propagation through a uniform zonal flow in an ...

  4. Vertical Glider Robots for Subsea Equipment Delivery

    E-print Network

    Reed, Brooks L.

    2011-01-01

    We have developed an underwater vehicle that offers significant performance improvements over existing sub sea elevators. Our Vertical Glider Robot falls under its own weight to a precise location on the seafloor, employing ...

  5. Subsurface imaging with reverse vertical seismic profiles

    E-print Network

    Krasovec, Mary L. (Mary Lee), 1972-

    2001-01-01

    This thesis presents imaging results from a 3D reverse vertical seismic profile (RVSP) dataset measured at a hydrocarbon bearing pinnacle reef in northern Michigan. The study presented many challenges in seismic data ...

  6. 30. BEARING SHOE / VERTICAL / DIAGONAL / UPPER AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. BEARING SHOE / VERTICAL / DIAGONAL / UPPER AND LOWER CHORD DETAIL OF DECK TRUSS. VIEW TO NORTHEAST. - Abraham Lincoln Memorial Bridge, Spanning Missouri River on Highway 30 between Nebraska & Iowa, Blair, Washington County, NE

  7. 23. INCLINED END POST / VERTICAL / DIAGONAL / PORTAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. INCLINED END POST / VERTICAL / DIAGONAL / PORTAL BRACING DETAIL. VIEW TO SOUTHEAST. - Abraham Lincoln Memorial Bridge, Spanning Missouri River on Highway 30 between Nebraska & Iowa, Blair, Washington County, NE

  8. Vertical Axis Wind Turbine Foundation parameter study

    SciTech Connect

    Lodde, P.F.

    1980-07-01

    The dynamic failure criterion governing the dimensions of prototype Vertical Axis Wind Turbine Foundations is treated as a variable parameter. The resulting change in foundation dimensions and costs is examined.

  9. Vertical-axis wind-turbine program

    SciTech Connect

    Braasch, R.H.

    1981-01-01

    During the interval since the Fourth Biennial Wind Energy Conference, the vertical axis wind turbine program has experienced significant progress. The purpose of this paper is to review that progress in aerodynamics research, structural dynamics research, and machine development.

  10. Vertically Aligned Nanocomposites in Magnetic Thin Films 

    E-print Network

    Abdel-Raziq, Haron

    2013-02-11

    With the advent of ferromagnetic materials for magnetic memory among other applications, increased attention has been given to understanding the properties of these ferromagnets. Here, a vertically aligned nanocomposite (VAN) system is examined...

  11. GROUND WATER PROTECTION ISSUES WITH GEOTHERMAL HEAT PUMPS

    SciTech Connect

    ALLAN,M.L.; PHILIPPACOPOULOS,A.J.

    1999-10-01

    Closed loop vertical boreholes used with geothermal heat pumps are grouted to facilitate heat transfer and prevent ground water contamination. The grout must exhibit suitable thermal conductivity as well as adequate hydraulic sealing characteristics. Permeability and infiltration tests were performed to assess the ability of cementitious grout to control vertical seepage in boreholes. It was determined that a superplasticized cement-sand grout is a more effective borehole sealant than neat cement over a range of likely operational temperatures. The feasibility of using non-destructive methods to verify bonding in heat exchangers is reviewed.

  12. Vertical Motions of Oceanic Volcanoes

    NASA Astrophysics Data System (ADS)

    Clague, D. A.; Moore, J. G.

    2006-12-01

    Oceanic volcanoes offer abundant evidence of changes in their elevations through time. Their large-scale motions begin with a period of rapid subsidence lasting hundreds of thousands of years caused by isostatic compensation of the added mass of the volcano on the ocean lithosphere. The response is within thousands of years and lasts as long as the active volcano keeps adding mass on the ocean floor. Downward flexure caused by volcanic loading creates troughs around the growing volcanoes that eventually fill with sediment. Seismic surveys show that the overall depression of the old ocean floor beneath Hawaiian volcanoes such as Mauna Loa is about 10 km. This gross subsidence means that the drowned shorelines only record a small part of the total subsidence the islands experienced. In Hawaii, this history is recorded by long-term tide-gauge data, the depth in drill holes of subaerial lava flows and soil horizons, former shorelines presently located below sea level. Offshore Hawaii, a series of at least 7 drowned reefs and terraces record subsidence of about 1325 m during the last half million years. Older sequences of drowned reefs and terraces define the early rapid phase of subsidence of Maui, Molokai, Lanai, Oahu, Kauai, and Niihau. Volcanic islands, such as Maui, tip down toward the next younger volcano as it begins rapid growth and subsidence. Such tipping results in drowned reefs on Haleakala as deep as 2400 m where they are tipped towards Hawaii. Flat-topped volcanoes on submarine rift zones also record this tipping towards the next younger volcano. This early rapid subsidence phase is followed by a period of slow subsidence lasting for millions of years caused by thermal contraction of the aging ocean lithosphere beneath the volcano. The well-known evolution along the Hawaiian chain from high to low volcanic island, to coral island, and to guyot is due to this process. This history of rapid and then slow subsidence is interrupted by a period of minor uplift lasting a few hundred thousand years as the island migrates over a broad flexural arch related to isostatic compensation of a nearby active volcano. The arch is located about 190±30 km away from the center of volcanic activity and is also related to the rejuvenated volcanic stage on the islands. Reefs on Oahu that are uplifted several tens of m above sea level are the primary evidence for uplift as the islands over-ride the flexural arch. At the other end of the movement spectrum, both in terms of magnitude and length of response, are the rapid uplift and subsidence that occurs as magma is accumulated within or erupted from active submarine volcanoes. These changes are measured in days to years and are of cm to m variation; they are measured using leveling surveys, tiltmeters, EDM and GPS above sea level and pressure gauges and tiltmeters below sea level. Other acoustic techniques to measure such vertical movement are under development. Elsewhere, evidence for subsidence of volcanoes is also widespread, ranging from shallow water carbonates on drowned Cretaceous guyots, to mapped shoreline features, to the presence of subaerially-erupted (degassed) lavas on now submerged volcanoes. Evidence for uplift is more limited, but includes makatea islands with uplifted coral reefs surrounding low volcanic islands. These are formed due to flexural uplift associated with isostatic loading of nearby islands or seamounts. In sum, oceanic volcanoes display a long history of subsidence, rapid at first and then slow, sometimes punctuated by brief periods of uplift due to lithospheric loading by subsequently formed nearby volcanoes.

  13. 47 CFR 73.160 - Vertical plane radiation characteristics, f(?).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Vertical plane radiation characteristics, f(θ). 73.160...Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

  14. 47 CFR 73.160 - Vertical plane radiation characteristics, f(?).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Vertical plane radiation characteristics, f(θ). 73.160...Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

  15. 47 CFR 73.160 - Vertical plane radiation characteristics, f(?).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Vertical plane radiation characteristics, f(θ). 73.160...Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

  16. 47 CFR 73.160 - Vertical plane radiation characteristics, f(?).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Vertical plane radiation characteristics, f(θ). 73.160...Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

  17. 47 CFR 73.160 - Vertical plane radiation characteristics, f(?).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Vertical plane radiation characteristics, f(θ). 73.160...Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane radiation characteristics show the...

  18. Rate limits in silicon sheet growth - The connections between vertical and horizontal methods

    NASA Technical Reports Server (NTRS)

    Thomas, Paul D.; Brown, Robert A.

    1987-01-01

    Meniscus-defined techniques for the growth of thin silicon sheets fall into two categories: vertical and horizontal growth. The interactions of the temperature field and the crystal shape are analyzed for both methods using two-dimensional finite-element models which include heat transfer and capillarity. Heat transfer in vertical growth systems is dominated by conduction in the melt and the crystal, with almost flat melt/crystal interfaces that are perpendicular to the direction of growth. The high axial temperature gradients characteristic of vertical growth lead to high thermal stresses. The maximum growth rate is also limited by capillarity which can restrict the conduction of heat from the melt into the crystal. In horizontal growth the melt/crystal interface stretches across the surface of the melt pool many times the crystal thickness, and low growth rates are achievable with careful temperature control. With a moderate axial temperature gradient in the sheet a substantial portion of the latent heat conducts along the sheet and the surface of the melt pool becomes supercooled, leading to dendritic growth. The thermal supercooling is surpressed by lowering the axial gradient in the crystal; this configuration is the most desirable for the growth of high quality crystals. An expression derived from scaling analysis relating the growth rate and the crucible temperature is shown to be reliable for horizontal growth.

  19. Nanofluid impingement jet heat transfer

    PubMed Central

    2012-01-01

    Experimental investigation to study the heat transfer between a vertical round alumina-water nanofluid jet and a horizontal circular round surface is carried out. Different jet flow rates, jet nozzle diameters, various circular disk diameters and three nanoparticles concentrations (0, 6.6 and 10%, respectively) are used. The experimental results indicate that using nanofluid as a heat transfer carrier can enhance the heat transfer process. For the same Reynolds number, the experimental data show an increase in the Nusselt numbers as the nanoparticle concentration increases. Size of heating disk diameters shows reverse effect on heat transfer. It is also found that presenting the data in terms of Reynolds number at impingement jet diameter can take into account on both effects of jet heights and nozzle diameter. Presenting the data in terms of Peclet numbers, at fixed impingement nozzle diameter, makes the data less sensitive to the percentage change of the nanoparticle concentrations. Finally, general heat transfer correlation is obtained verses Peclet numbers using nanoparticle concentrations and the nozzle diameter ratio as parameters. PMID:22340669

  20. Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Detail, Vertical Cross Bracing-End Detail - Cumberland Covered Bridge, Spanning Mississinewa River, Matthews, Grant County, IN

  1. Heating in the tropical atmosphere: what level of detail is critical for accurate MJO simulations in GCMs?

    E-print Network

    Heating in the tropical atmosphere: what level of detail is critical for accurate MJO simulations processes that affect heating in some facet. In this study, we examine various heating adjustments in Community Atmospheric Model version 4 (CAM4) to determine what the vertical and horizontal heating

  2. Heat collector

    DOEpatents

    Merrigan, M.A.

    1981-06-29

    A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.

  3. Heat collector

    DOEpatents

    Merrigan, Michael A. (Santa Cruz, NM)

    1984-01-01

    A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.

  4. Method and apparatus for producing tar sand deposits containing conductive layers having little or no vertical communication

    SciTech Connect

    Glandt, C.A.; Vinegar, H.J.; Gardner, J.W.

    1991-10-29

    This patent describes a process for recovering hydrocarbons from hydrocarbon-bearing deposits containing thin highly conductive layers adjacent to at least one hydrocarbon rich zone. It comprises selecting a hydrocarbon-bearing deposit which contains a thin highly conductive layer within the deposit; installing at least one pair of horizontal electrodes spanning the highly conductive layer and dividing the layer into electrically heated and non-electrically heated zones; providing at least one vertical injection well for hot fluid injection into the hydrocarbon rich zone; providing at least one vertical production well for production of hydrocarbons; electrically heating the thin highly conductive layer to form a preheated zone immediately adjacent to the thin highly conductive layer while simultaneously stimulating the wells with steam; injecting the hot fluid into the deposit adjacent to the thin highly conductive layer and within the thin preheated zone to displace the hydrocarbons to the production wells; and recovering hydrocarbons from the production wells. This patent also describes an apparatus for recovering hydrocarbons from tar sand deposits containing highly conductive layers. It comprises at least two pairs of horizontal electrodes which span the highly conductive layer and divide the highly conductive layer into at least two horizontally displaced electrically heated zones separated by non-electrically heated zones; at least one vertical injection well; and at least one vertical production well.

  5. Corrosive resistant heat exchanger

    DOEpatents

    Richlen, Scott L. (Annandale, VA)

    1989-01-01

    A corrosive and errosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is conveyed through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium.

  6. Natural convection mass transfer behavior of long vertical annuli

    SciTech Connect

    Zaki, M.M.; Nirdosh, I.; Sedahmed, G.H.

    2000-04-01

    The natural convection mass transfer behavior of the inner cylinder of a vertical annulus was studied by measuring the limiting current of the cathodic deposition of copper from acidified copper sulfate solution. Active cylinder height and copper sulfate concentration were varied to provide a (Sc.Gr) range of 1.8 x 10{sup 10}--3.3 x 10{sup 14}; under these conditions which lie in the transition region, the data were found to fit the equation: Sh = 0.325(Sc.Gr){sup 0.28} Comparison between the present data and previous related data in mass and heat transfer confirmed the fact that the product Sc.Gr is not the sole criterion for laminar-turbulent transition but the value of Sc or Pr plays also an important role.

  7. Vertical distribution of structural components in corn stover

    DOE PAGESBeta

    Johnson, Jane M. F.; Karlen, Douglas L.; Gresham, Garold L.; Cantrell, Keri B.; Archer, David W.; Wienhold, Brian J.; Varvel, Gary E.; Laird, David A.; Baker, John; Ochsner, Tyson E.; et al

    2014-11-17

    In the United States, corn (Zea mays L.) stover has been targeted for second generation fuel production and other bio-products. Our objective was to characterize sugar and structural composition as a function of vertical distribution of corn stover (leaves and stalk) that was sampled at physiological maturity and about three weeks later from multiple USA locations. A small subset of samples was assessed for thermochemical composition. Concentrations of lignin, glucan, and xylan were about 10% greater at grain harvest than at physiological maturity, but harvestable biomass was about 25% less due to stalk breakage. Gross heating density above the earmore »averaged 16.3 ± 0.40 MJ kg?¹, but with an alkalinity measure of 0.83 g MJ?¹, slagging is likely to occur during gasification. Assuming a stover harvest height of 10 cm, the estimated ethanol yield would be >2500 L ha?¹, but it would be only 1000 L ha?¹ if stover harvest was restricted to the material from above the primary ear. Vertical composition of corn stover is relatively uniform; thus, decision on cutting height may be driven by agronomic, economic and environmental considerations.« less

  8. Vertical distribution of structural components in corn stover

    SciTech Connect

    Jane M. F. Johnson; Douglas L. Karlen; Garold L. Gresham; Keri B. Cantrell; David W. Archer; Brian J. Wienhold; Gary E. Varvel; David A. Laird; John Baker; Tyson E. Ochsner; Jeff M. Novak; Ardell D. Halvorson; Francisco Arriaga; David T. Lightle; Amber Hoover; Rachel Emerson; Nancy W. Barbour

    2014-11-01

    In the United States, corn (Zea mays L.) stover has been targeted for second generation fuel production and other bio-products. Our objective was to characterize sugar and structural composition as a function of vertical distribution of corn stover (leaves and stalk) that was sampled at physiological maturity and about three weeks later from multiple USA locations. A small subset of samples was assessed for thermochemical composition. Concentrations of lignin, glucan, and xylan were about 10% greater at grain harvest than at physiological maturity, but harvestable biomass was about 25% less due to stalk breakage. Gross heating density above the ear averaged 16.3 ± 0.40 MJ kg?¹, but with an alkalinity measure of 0.83 g MJ?¹, slagging is likely to occur during gasification. Assuming a stover harvest height of 10 cm, the estimated ethanol yield would be >2500 L ha?¹, but it would be only 1000 L ha?¹ if stover harvest was restricted to the material from above the primary ear. Vertical composition of corn stover is relatively uniform; thus, decision on cutting height may be driven by agronomic, economic and environmental considerations.

  9. Vertical distribution of structural components in corn stover

    SciTech Connect

    Johnson, Jane M. F.; Karlen, Douglas L.; Gresham, Garold L.; Cantrell, Keri B.; Archer, David W.; Wienhold, Brian J.; Varvel, Gary E.; Laird, David A.; Baker, John; Ochsner, Tyson E.; Novak, Jeff M.; Halvorson, Ardell D.; Arriaga, Francisco; Lightle, David T.; Hoover, Amber; Emerson, Rachel; Barbour, Nancy W.

    2014-11-17

    In the United States, corn (Zea mays L.) stover has been targeted for second generation fuel production and other bio-products. Our objective was to characterize sugar and structural composition as a function of vertical distribution of corn stover (leaves and stalk) that was sampled at physiological maturity and about three weeks later from multiple USA locations. A small subset of samples was assessed for thermochemical composition. Concentrations of lignin, glucan, and xylan were about 10% greater at grain harvest than at physiological maturity, but harvestable biomass was about 25% less due to stalk breakage. Gross heating density above the ear averaged 16.3 ± 0.40 MJ kg?¹, but with an alkalinity measure of 0.83 g MJ?¹, slagging is likely to occur during gasification. Assuming a stover harvest height of 10 cm, the estimated ethanol yield would be >2500 L ha?¹, but it would be only 1000 L ha?¹ if stover harvest was restricted to the material from above the primary ear. Vertical composition of corn stover is relatively uniform; thus, decision on cutting height may be driven by agronomic, economic and environmental considerations.

  10. Thermal analysis of the vertical bridgman semiconductor crystal growth technique. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Jasinski, T. J.

    1982-01-01

    The quality of semiconductor crystals grown by the vertical Bridgman technique is strongly influenced by the axial and radial variations of temperature within the charge. The relationship between the thermal parameters of the vertical Bridgman system and the thermal behavior of the charge are examined. Thermal models are developed which are capable of producing results expressable in analytical form and which can be used without recourse to extensive computer work for the preliminary thermal design of vertical Bridgman crystal growth systems. These models include the effects of thermal coupling between the furnace and the charge, charge translation rate, charge diameter, thickness and thermal conductivity of the confining crucible, thermal conductivity change and liberation of latent heat at the growth interface, and infinite charge length. The hot and cold zone regions, considered to be at spatially uniform temperatures, are separated by a gradient control region which provides added thermal design flexibility for controlling the temperature variations near the growth interface.

  11. Triaxial thermopile array geo-heat-flow sensor

    DOEpatents

    Carrigan, Charles R. (Tracy, CA); Hardee, Harry C. (Albuquerque, NM); Reynolds, Gerald D. (Tijeras, NM); Steinfort, Terry D. (Tijeras, NM)

    1992-01-01

    A triaxial thermopile array geothermal heat flow sensor is designed to measure heat flow in three dimensions in a reconstituted or unperturbed subsurface regime. Heat flow can be measured in conductive or permeable convective media. The sensor may be encased in protective pvc tubing and includes a plurality of thermistors and an array of heat flow transducers arranged in a vertical string. The transducers produce voltage proportional to heat flux along the subsurface regime and permit direct measurement of heat flow in the subsurface regime. The presence of the thermistor array permits a comparison to be made between the heat flow estimates obtained from the transducers and heat flow calculated using temperature differences and Fourier's Law. The device is extremely sensitive with an accuracy of less than 0.1 Heat Flow Units (HFU) and may be used for long term readings.

  12. Temporal variability of vertical export flux at the DYFAMED time-series station (Northwestern Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

    Heimbürger, Lars-Eric; Lavigne, Héloïse; Migon, Christophe; D'Ortenzio, Fabrizio; Estournel, Claude; Coppola, Laurent; Miquel, Juan-Carlos

    2013-12-01

    The temporal evolution of the vertical export flux at the DYFAMED time-series station (Ligurian Sea) over the last 20 years reveals a strong interannual variability. Winter convection allows particulate (and dissolved) matter to be vertically exported (“flush-down” effect). The efficiency of this process determines also the concentration of nutrients brought to surface waters and, therefore, the intensity of the subsequent phytoplankton bloom. The sequence “convection-bloom” is the main driving force of vertical export flux in this region. The present work attempts to better identify the parameters that control vertical export flux dynamics by observing a 20 year time-series in relation with the temporal variability of mixed layer depth and surface primary production. The consequences of a more stratified water column in the future on biological productivity and vertical export flux are pointed out. In winter, the cooling of surface water, combined with evaporation, increases its density and determines the vertical convection. This allows for a rapid downward transfer of dissolved and particulate matter, yielding high vertical export flux. This “flush-down effect” results from a combination of convection and gravitational flux, since the diving of dense surface waters breaks the stratification of the water column and carries all material (particulate + dissolved) accumulated in the surface layer to depth. The rapid downward transfer of dissolved and particulate matter by this “flush-down effect” yields high vertical export fluxes. The magnitude of these fluxes may vary according to the amount of atmospheric material accumulated in surface waters during the preceding stratified period. In the present data set, highest vertical export fluxes were observed in 1999, 2003 and 2004. In those years, the MLD was greater (Fig. 2), suggesting a causal relationship between the efficiency of vertical mixing and the subsequent vertical export flux. In spring, nutrients brought to surface waters by the vertical mixing trigger phytoplankton blooms, which generate new material for the vertical transfer of dissolved and particulate matter. Maximum Chl-a occurs shortly after the MLD maximum. Ga?i? et al. (2002) observed a marked seasonal variability of POC fluxes in the Adriatic Sea. Spring maxima are associated with phytoplankton blooms. In spite of interannual variations in the intensity of the phytoplankton blooms, their seasonal distribution and biomass abundance are reproducible (Marty et al., 2002), with maximum values of carbon assimilation in March and April (Marty and Chiavérini, 2002; Fig. 2). Indeed, high vertical export fluxes were observed within the present dataset in spring, as a result of biological productivity (e.g. 2000). In summer and fall, the heating of the sea surface results in a stratified water column with a shallow ML which is rapidly exhausted of nutrients. During such oligotrophic conditions (June to November), the concentrations of biogenic matter in the photic layer are minimal. Therefore, owing to insignificant transfer of POC, atmospherically-transported individual particles presumably do not sink (or sink with negligible sinking velocity), according to Stokesian settling calculations (Stokes, 1901). In the absence of packaging into large biogenic material (adsorption onto phytoplanktonic debris or incorporation into fecal pellets), atmospheric particles thus accumulate in the surface ML. In addition, dissolved atmospheric matter (e.g., from atmospheric wet deposition) is not removed from surface waters via its assimilation by phytoplankton, and it accumulates in the surface ML (e.g. dissolved organic matter (DOM); (Copin-Montégut and Avril, 1993)). Consequently, the lowest vertical export fluxes are observed during this period of the year. For example, years 2003 and 2004 exhibited minimal vertical export fluxes during summer and fall (Fig. 2). However, summer 2002 was unusual, with relatively a high vertical export flux. This resulted from the combination of particularly strong summer

  13. Correspondence Reply to comment on: "Estimates of heat flow from Cenozoic

    E-print Network

    Sandwell, David T.

    an estimate of the global Cenozoic heat flow that was largely independent of the sometimes- biased conductive, is density, is the volumetric coefficient of thermal expansion, Cp is the heat capacity, and qs diffusion. The vertical heat transport mechanism is irrelevant so the thermal conductivity or diffusivity do

  14. 1 Copyright 2012 by ASME Proceedings of the ASME 2012 Summer Heat Transfer Conference

    E-print Network

    Bahrami, Majid

    , #12;2 Copyright © 2012 by ASME is convective heat transfer coefficient and is thermal conductivity1 Copyright © 2012 by ASME Proceedings of the ASME 2012 Summer Heat Transfer Conference HT2012 July CONVECTIVE HEAT TRANSFER FROM VERTICALLY-MOUNTED RECTANGULAR INTERRUPTED FINS Golnoosh Mostafavi MASc

  15. Pushing the Limits of Natural Convection Heat Transfer from the Heatsinks

    E-print Network

    Bahrami, Majid

    Pushing the Limits of Natural Convection Heat Transfer from the Heatsinks by Mehran Ahmadi M of Natural Convection Heat Transfer from the Heatsinks Examining Committee: Chair: Kevin Oldknow Lecturer Systems companies, aims to push the current limits of natural convection heat transfer from vertical

  16. Up-down asymmetry in vertical vection.

    PubMed

    Seya, Yasuhiro; Shinoda, Hiroyuki; Nakaura, Yoshiya

    2015-12-01

    To investigate whether up-down asymmetry similar to that reported in vertical optokinetic nystagmus (OKN), that is, larger OKN responses for upward motion than for downward motion, would appear in vertical vection, we conducted three experiments. In all three experiments, participants viewed a vertically moving random-dot pattern. In Experiments 1 and 2, participants reported vection using a joystick. After each trial, they were also asked to rate the vection magnitude experienced during the stimulus presentation. In Experiment 3, eye movements and vection magnitude (rated after each trial) in response to the stimulus were measured. The results of Experiment 1 showed larger vection magnitude for the upward motion of the stimulus than for the downward motion of it. However, vection onset latency did not change much with stimulus motion direction. Experiment 2 revealed that the up-down asymmetry in vection manifested progressively during the latter part of the stimulus presentation period. Experiment 3 showed clear up-down asymmetry in both OKN and vection magnitude. These results not only indicate that up-down asymmetry similar to that reported in vertical OKN appears in vertical vection, but they also support the notion that the mechanisms underlying vection and OKN are closely related to each other. PMID:26518744

  17. Modular Heat Exchanger With Integral Heat Pipe

    NASA Technical Reports Server (NTRS)

    Schreiber, Jeffrey G.

    1992-01-01

    Modular heat exchanger with integral heat pipe transports heat from source to Stirling engine. Alternative to heat exchangers depending on integrities of thousands of brazed joints, contains only 40 brazed tubes.

  18. Heat exchangers and solar heating

    SciTech Connect

    Fuller, D.L.

    1980-01-22

    A heat exchanger and a solar heating unit incorporating the heat exchanger and described. The heat exchanger is constructed with an outer tubular member closed at its ends and provided with a fluid inlet at one end and a fluid outlet at the other end, and an inner tubular member of different cross-sectional shape to the cross-sectional shape of the outer tubular member but positioned and dimensioned so as to provide a plurality of longitudinal points of contact between the outer member inner surface and the inner member outer surface and a plurality of fluid ducts defined by the longitudinal wall portions of the outer and inner tubular members between said points of contact.

  19. Binocular contributions to linear vertical vection.

    PubMed

    Allison, Robert S; Ash, April; Palmisano, Stephen

    2014-01-01

    Compelling illusions of self-motion, known as vection, can be produced in a stationary observer by visual stimulation alone. The role of binocular vision and stereopsis in these illusions was explored in a series of three experiments. Previous research had provided evidence of stereoscopic enhancements for linear vection in depth (e.g., Palmisano, 1996, 2002). Here we examined for the first time the effects of binocular vision and stereopsis on linear vertical vection. Vertical vection was induced by the upward or downward translation of large stereoscopic surfaces. These surfaces were horizontally oriented depth corrugations produced by disparity modulation of patterns of persistent or short lifetime dot elements. We found that binocular viewing of such surfaces significantly increased the magnitudes and decreased the onset delays of vertical vection. Experiments utilizing short lifetime dot stereograms demonstrated that these particular binocular enhancements of vection were due to the motion of stereoscopically defined features. PMID:25761282

  20. Purification process for vertically aligned carbon nanofibers

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V.; Delziet, Lance; Matthews, Kristopher; Chen, Bin; Meyyappan, M.

    2003-01-01

    Individual, free-standing, vertically aligned multiwall carbon nanotubes or nanofibers are ideal for sensor and electrode applications. Our plasma-enhanced chemical vapor deposition techniques for producing free-standing and vertically aligned carbon nanofibers use catalyst particles at the tip of the fiber. Here we present a simple purification process for the removal of iron catalyst particles at the tip of vertically aligned carbon nanofibers derived by plasma-enhanced chemical vapor deposition. The first step involves thermal oxidation in air, at temperatures of 200-400 degrees C, resulting in the physical swelling of the iron particles from the formation of iron oxide. Subsequently, the complete removal of the iron oxide particles is achieved with diluted acid (12% HCl). The purification process appears to be very efficient at removing all of the iron catalyst particles. Electron microscopy images and Raman spectroscopy data indicate that the purification process does not damage the graphitic structure of the nanotubes.

  1. Vertical gradients of sunspot magnetic fields

    NASA Technical Reports Server (NTRS)

    Hagyard, M. J.; Teuber, D.; West, E. A.; Tandberg-Hanssen, E.; Henze, W., Jr.; Beckers, J. M.; Bruner, M.; Hyder, C. L.; Woodgate, B. E.

    1983-01-01

    The results of a Solar Maximum Mission (SMM) guest investigation to determine the vertical gradients of sunspot magnetic fields for the first time from coordinated observations of photospheric and transition-region fields are described. Descriptions are given of both the photospheric vector field of a sunspot, derived from observations using the NASA Marshall Space Flight Center vector magnetograph, and of the line-of-sight component in the transition region, obtained from the SMM Ultraviolet Spectrometer and Polarimeter instrument. On the basis of these data, vertical gradients of the line-of-sight magnetic field component are calculated using three methods. It is found that the vertical gradient of Bz is lower than values from previous studies and that the transition-region field occurs at a height of approximately 4000-6000 km above the photosphere.

  2. Vertical vibration analysis for elevator compensating sheave

    NASA Astrophysics Data System (ADS)

    Watanabe, Seiji; Okawa, Takeya; Nakazawa, Daisuke; Fukui, Daiki

    2013-07-01

    Most elevators applied to tall buildings include compensating ropes to satisfy the balanced rope tension between the car and the counter weight. The compensating ropes receive tension by the compensating sheave, which is installed at the bottom space of the elevator shaft. The compensating sheave is only suspended by the compensating ropes, therefore, the sheave can move vertically while the car is traveling. This paper shows the elevator dynamic model to evaluate the vertical motion of the compensating sheave. Especially, behavior in emergency cases, such as brake activation and buffer strike, was investigated to evaluate the maximum upward motion of the sheave. The simulation results were validated by experiments and the most influenced factor for the sheave vertical motion was clarified.

  3. Mixed convection nanofluid flow in a vertical channel with boundary conditions of the third kind

    NASA Astrophysics Data System (ADS)

    Makhatar, Nur Asiah Mohd; Siddheshwar, P. G.; Saleh, Habibis; Hashim, Ishak

    2015-09-01

    A numerical investigation is carried out into the heat transfer within a fully-developed mixed convection flow of Al2O3 - water, CuO - water and TiO2 - water nanoliquids in a vertical channel with boundary condition of third kind. The effects of Brinkman number, Br and mixed convection parameter, GR on the velocity distribution and temperature distribution are the focus of this study. The built-in routine, dsolve in MAPLE is applied for the numerical computation. It was found that, greater value of GR and lower value of Br greatly affected the heat transfer performance and resulted the occurrence of reversal flow.

  4. Heating System Specification Specification of Heating System

    E-print Network

    Day, Nancy

    Appendix A Heating System Specification /* Specification of Heating System (loosely based */ requestHeat : Room ­? bool; 306 #12; APPENDIX A. HEATING SYSTEM SPECIFICATION 307 /* user inputs */ livingPattern : Room ­? behaviour; setTemp : Room ­? num; heatSwitchOn, heatSwitchOff, userReset : simple

  5. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...

  6. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...

  7. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...

  8. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...

  9. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...

  10. Turbulence in vertical axis wind turbine canopies

    NASA Astrophysics Data System (ADS)

    Kinzel, Matthias; Araya, Daniel B.; Dabiri, John O.

    2015-11-01

    Experimental results from three different full scale arrays of vertical-axis wind turbines (VAWTs) under natural wind conditions are presented. The wind velocities throughout the turbine arrays are measured using a portable meteorological tower with seven, vertically staggered, three-component ultrasonic anemometers. The power output of each turbine is recorded simultaneously. The comparison between the horizontal and vertical energy transport for the different turbine array sizes shows the importance of vertical transport for large array configurations. Quadrant-hole analysis is employed to gain a better understanding of the vertical energy transport at the top of the VAWT arrays. The results show a striking similarity between the flows in the VAWT arrays and the adjustment region of canopies. Namely, an increase in ejections and sweeps and decrease in inward and outward interactions occur inside the turbine array. Ejections are the strongest contributor, which is in agreement with the literature on evolving and sparse canopy flows. The influence of the turbine array size on the power output of the downstream turbines is examined by comparing a streamwise row of four single turbines with square arrays of nine turbine pairs. The results suggest that a new boundary layer forms on top of the larger turbine arrays as the flow adjusts to the new roughness length. This increases the turbulent energy transport over the whole planform area of the turbine array. By contrast, for the four single turbines, the vertical energy transport due to turbulent fluctuations is only increased in the near wake of the turbines. These findings add to the knowledge of energy transport in turbine arrays and therefore the optimization of the turbine spacing in wind farms.

  11. Top-down vertical itemset mining

    NASA Astrophysics Data System (ADS)

    Sohrabi, Mohammad Karim; Ghods, Vahid

    2015-03-01

    Vertical itemset mining is an important frequent pattern mining problem with broad applications. It is challenging since one may need to examine a combinatorial explosive number of possible patterns of items of a dataset in a traditional horizontal algorithm. Since high dimensional datasets typically contain a large number of columns and a small number of rows, vertical itemset mining algorithms, which extract the frequent itemsets of dataset by producing all combination of rows ids, are a good alternative for horizontal algorithms in mining frequent itemsets from high dimensional dataset. Since a rowset can be simply produced from its subsets by adding a new row id to a sub rowset, many bottom up vertical itemset mining algorithms are designed and represented in the literature. However, bottom up vertical mining algorithms suffer from a main drawback. Bottom-up algorithms start the process of generating and testing of rowsets from the small rowsets and go on to the larger rowsets, whereas the small rowsets cannot produce a frequent itemsets because they contain less than minimum support threshold number of rows. In this paper, we described a new efficient vertical top down algorithm called VTD (Vertical Top Down) to conduct mining of frequent itemsets in high dimensional datasets. Our top down approach employed the minimum support threshold to prune the rowsets which any itemset could not be extracted from them. Several experiments on real bioinformatics datasets showed that VTD is orders of magnitude better than previous closed pattern mining algorithms. Our performance study showed that this algorithm outperformed substantially the best former algorithms.

  12. European Vertical Reference System Influence in Latvia

    NASA Astrophysics Data System (ADS)

    Celms, A.; Re?e, I.; Ratkevi?s, A.

    2015-11-01

    Till 1 December, 2014, in Latvia the heights were determined in Baltic Normal Height System 1977. The national height system is determined by the Cabinet of Ministers and internal laws. Now for the change of the national height system to reconcile it with the European Vertical Reference System, amendments to the laws and regulations have been developed, but so far only the amendment to the Geospatial Information Law is in force, the amendment to the regulation of the Cabinet of Ministers is still not approved. This amendment declares the Latvia Height System based on the European Vertical Reference System in Latvia as the national height system. For height transformation, there is a transformation formula for each European country. After calculations it is seen that height difference between Baltic Normal Height System 1977 and European Vertical Reference System depends on point location in the territory (coordinates). This unequal height difference between both height systems will cause unequal height values on border connection points between Baltic countries. The aim of the research is to evaluate the European Vertical Reference System in Latvia. To reach the aim the following tasks are set: 1) to evaluate the components of transformation formulas; 2) using the transformation formulas to calculate height differences between Baltic Normal Height System 1977 and the European Vertical Reference System realization EVRF2007 for the territory of Latvia and also between Baltic Normal Height System 1977 and the Latvia Normal Height System; 3) to get height differences in the European Vertical Reference System on the borderlines of Latvia - Estonia and Latvia - Lithuania.

  13. Heat Pipes

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Bobs Candies, Inc. produces some 24 million pounds of candy a year, much of it 'Christmas candy.' To meet Christmas demand, it must produce year-round. Thousands of cases of candy must be stored a good part of the year in two huge warehouses. The candy is very sensitive to temperature. The warehouses must be maintained at temperatures of 78-80 degrees Fahrenheit with relative humidities of 38- 42 percent. Such precise climate control of enormous buildings can be very expensive. In 1985, energy costs for the single warehouse ran to more than $57,000 for the year. NASA and the Florida Solar Energy Center (FSEC) were adapting heat pipe technology to control humidity in building environments. The heat pipes handle the jobs of precooling and reheating without using energy. The company contacted a FSEC systems engineer and from that contact eventually emerged a cooperative test project to install a heat pipe system at Bobs' warehouses, operate it for a period of time to determine accurately the cost benefits, and gather data applicable to development of future heat pipe systems. Installation was completed in mid-1987 and data collection is still in progress. In 1989, total energy cost for two warehouses, with the heat pipes complementing the air conditioning system was $28,706, and that figures out to a cost reduction.

  14. Photochemistry and vertical mixing. [in Uranus atmosphere

    NASA Technical Reports Server (NTRS)

    Atreya, S. K.; Sandel, B. R.; Romani, P. N.

    1991-01-01

    Earth-based observations relevant to the question of photochemistry and vertical mixing are discussed. Phytolysis of methane, the only known photochemically active volatile in the Uranian atmosphere, produces heavier hydrocarbons, the most abundant of which are ethane, acetylene, and the polyacetylenes. Unlike Jupiter and Saturn, these hydrocarbon products condense at the low temperatures prevalent in the middle atmosphere. Contrary to the pre-Voyager notion that the atmosphere of Uranus is remarkable clear, it is found that the aerosols are widely and extensively distributed. Despite its photodestruction, methane remains stable in the Uranian atmosphere. The vertical mixing on Uranus is found to be the least efficient of any of the planetary atmospheres.

  15. CIRSS vertical data integration, San Bernardino study

    NASA Technical Reports Server (NTRS)

    Hodson, W.; Christenson, J.; Michel, R. (principal investigators)

    1982-01-01

    The creation and use of a vertically integrated data base, including LANDSAT data, for local planning purposes in a portion of San Bernardino County, California are described. The project illustrates that a vertically integrated approach can benefit local users, can be used to identify and rectify discrepancies in various data sources, and that the LANDSAT component can be effectively used to identify change, perform initial capability/suitability modeling, update existing data, and refine existing data in a geographic information system. Local analyses were developed which produced data of value to planners in the San Bernardino County Planning Department and the San Bernardino National Forest staff.

  16. Concepts for generating optimum vertical flight profiles

    NASA Technical Reports Server (NTRS)

    Sorensen, J. A.

    1979-01-01

    Algorithms for generating optimum vertical profiles are derived and examined. These algorithms form the basis for the design of onboard flight management concepts. The variations in the optimum vertical profiles (resulting from these concepts) due to variations in wind, takeoff weight, and range-to-destination are presented. Further considerations for mechanizing two different onboard methods of computing near-optimum flight profiles are then outlined. Finally, the results are summarized, and recommendations are made for further work. Technical details of optimum trajectory design, steering requirements for following these trajectories, and off-line computer programs for testing the concepts are included.

  17. Vertical group III-V nanowires on si, heterostructures, flexible arrays and fabrication

    DOEpatents

    Wang, Deli; Soci, Cesare; Bao, Xinyu; Wei, Wei; Jing, Yi; Sun, Ke

    2015-01-13

    Embodiments of the invention provide a method for direct heteroepitaxial growth of vertical III-V semiconductor nanowires on a silicon substrate. The silicon substrate is etched to substantially completely remove native oxide. It is promptly placed in a reaction chamber. The substrate is heated and maintained at a growth temperature. Group III-V precursors are flowed for a growth time. Preferred embodiment vertical Group III-V nanowires on silicon have a core-shell structure, which provides a radial homojunction or heterojunction. A doped nanowire core is surrounded by a shell with complementary doping. Such can provide high optical absorption due to the long optical path in the axial direction of the vertical nanowires, while reducing considerably the distance over which carriers must diffuse before being collected in the radial direction. Alloy composition can also be varied. Radial and axial homojunctions and heterojunctions can be realized. Embodiments provide for flexible Group III-V nanowire structures. An array of Group III-V nanowire structures is embedded in polymer. A fabrication method forms the vertical nanowires on a substrate, e.g., a silicon substrate. Preferably, the nanowires are formed by the preferred methods for fabrication of Group III-V nanowires on silicon. Devices can be formed with core/shell and core/multi-shell nanowires and the devices are released from the substrate upon which the nanowires were formed to create a flexible structure that includes an array of vertical nanowires embedded in polymer.

  18. Vertical structures induced by embedded moonlets in Saturn's rings: the gap region

    E-print Network

    Hoffmann, Holger; Seiß, Martin

    2012-01-01

    We study the vertical extent of propeller structures in Saturn's rings. Our focus lies on the gap region of the propeller and on non-inclined propeller moonlets. In order to describe the vertical structure of propellers we extend the model of Spahn and Sremcevic (2000) to include the vertical direction. We find that the gravitational interaction of ring particles with the non-inclined moonlet does not induce considerable vertical excursions of ring particles, but causes a considerable thermal motion in the ring plane. We expect ring particle collisions to partly convert the lateral induced thermal motion into vertical excursions of ring particles. For the gap region of the propeller, we calculate gap averaged propeller heights on the order of 0.7 Hill radii, which is of the order of the moonlet radius. In our model the propeller height decreases exponentially until viscous heating and collisional cooling balance. We estimate Hill radii of 370m and 615m for the propellers Earhart and Bleriot. Our model predict...

  19. Heat exchanger

    NASA Technical Reports Server (NTRS)

    Holmes, R. F.; Keller, E. E. (inventors)

    1976-01-01

    An improved lightweight heat exchanger particularly suited for use in systems having low volume flow, high longitudinal gradient and high effectiveness requirements is described. The heat exchanger is characterized by a shell of an annular configuration, an endless plate of minimal thickness and of a substantially uniformly convoluted configuration disposed within the annular shell for defining a plurality of endless, juxtaposed passages, each having a low Reynold's number and being of an annular configuration. A pair of manifolds disposed 180 deg apart is mounted on the shell in communication with the passages through which counterflowing fluids are simultaneously introduced and extracted from the passageways for achieving a continuous transfer of heat through the convoluted plate.

  20. Light efficient parallel interconnect using integrated planar free-space optics and vertical cavity surface emitting laser diodes

    E-print Network

    Jahns, Jürgen

    Light efficient parallel interconnect using integrated planar free-space optics and vertical cavity and for imaging. From a systems point of view, high light efficiency and large data throughput of the interconnect heat and a lower bandwidth. The issue of light efficiency is related to the realization of the optical

  1. Heat exchanger

    SciTech Connect

    Drury, C.R.

    1988-02-02

    A heat exchanger having primary and secondary conduits in heat-exchanging relationship is described comprising: at least one serpentine tube having parallel sections connected by reverse bends, the serpentine tube constituting one of the conduits; a group of open-ended tubes disposed adjacent to the parallel sections, the open-ended tubes constituting the other of the conduits, and forming a continuous mass of contacting tubes extending between and surrounding the serpentine tube sections; and means securing the mass of tubes together to form a predetermined cross-section of the entirety of the mass of open-ended tubes and tube sections.

  2. Thermal Conduction in Vertically Aligned Copper Nanowire Arrays and Composites.

    PubMed

    Barako, Michael T; Roy-Panzer, Shilpi; English, Timothy S; Kodama, Takashi; Asheghi, Mehdi; Kenny, Thomas W; Goodson, Kenneth E

    2015-09-01

    The ability to efficiently and reliably transfer heat between sources and sinks is often a bottleneck in the thermal management of modern energy conversion technologies ranging from microelectronics to thermoelectric power generation. These interfaces contribute parasitic thermal resistances that reduce device performance and are subjected to thermomechanical stresses that degrade device lifetime. Dense arrays of vertically aligned metal nanowires (NWs) offer the unique combination of thermal conductance from the constituent metal and mechanical compliance from the high aspect ratio geometry to increase interfacial heat transfer and device reliability. In the present work, we synthesize copper NW arrays directly onto substrates via templated electrodeposition and extend this technique through the use of a sacrificial overplating layer to achieve improved uniformity. Furthermore, we infiltrate the array with an organic phase change material and demonstrate the preservation of thermal properties. We use the 3? method to measure the axial thermal conductivity of freestanding copper NW arrays to be as high as 70 W m(-1) K(-1), which is more than an order of magnitude larger than most commercial interface materials and enhanced-conductivity nanocomposites reported in the literature. These arrays are highly anisotropic, and the lateral thermal conductivity is found to be only 1-2 W m(-1) K(-1). We use these measured properties to elucidate the governing array-scale transport mechanisms, which include the effects of morphology and energy carrier scattering from size effects and grain boundaries. PMID:26284489

  3. The Effect of Vertical Temperature Gradient on the Propagation of Three-dimensional Waves in a Protoplanetary Disk

    E-print Network

    Lee, Wing-Kit

    2015-01-01

    Excitation and propagation of waves in a thermally stratified disk with an arbitrary vertical temperature profile are studied. Previous analytical studies of three-dimensional waves had been focused on either isothermal or polytropic vertical disk structures. However, at the location in a protoplanetary disk where the dominant heating source is stellar irradiation, the temperature gradient may become positive in the vertical direction. We extend the analysis to study the effects of the vertical temperature structure on the waves that are excited at the Lindblad resonances. For a hotter disk atmosphere, the $f$-mode contributes less to the torque and remains confined near the midplane as it propagates away from the resonances. On the other hand, the excitation of the $g$-modes is stronger. As they propagate, they channel to the top of disk atmosphere and their group velocities decrease. The differences compared to previous studies may have implications in understanding the wave dynamics in a realistic disk str...

  4. The Effect of Vertical Temperature Gradient on the Propagation of Three-dimensional Waves in a Protoplanetary Disk

    NASA Astrophysics Data System (ADS)

    Lee, Wing-Kit; Gu, Pin-Gao

    2015-11-01

    Excitation and propagation of waves in a thermally stratified disk with an arbitrary vertical temperature profile are studied. Previous analytical studies of three-dimensional waves had been focused on either isothermal or polytropic vertical disk structures. However, at the location in a protoplanetary disk where the dominant heating source is stellar irradiation, the temperature gradient may become positive in the vertical direction. We extend the analysis to study the effects of the vertical temperature structure on the waves that are excited at the Lindblad resonances. For a hotter disk atmosphere, the f-mode contributes less to the torque and remains confined near the midplane as it propagates away from the resonances. On the other hand, the excitation of the g-modes is stronger. As they propagate, they channel to the top of disk atmosphere and their group velocities decrease. The differences compared to previous studies may have implications in understanding the wave dynamics in a realistic disk structure.

  5. Analysis of vertical precipitation characteristics using by Vertical Pointing Radar and Optical Disdrometer in Korea

    NASA Astrophysics Data System (ADS)

    cha, J.; Chang, K.; Choi, Y.; Yum, S. S.

    2011-12-01

    The objective of this study is to understand the vertical precipitation structure by using the vertical pointing radar (MRR, Micro Rain Radar, OTT Inc.) and optical disdrometer (PARSIVEL, PARticle SIze and VELocity, METEK Inc.) set, established in the coastal and mountainous regions of South Korea. The observational factors measured by both instruments are precipitation drop size distribution (DSD), rain rate, and liquid water content. The MRR's DSD at its low level shows good agreement with that of PARSIVEL. We retrieve the vertical rain rate and liquid water content from MRR under melting layer, calculated by Cha et al's method, in Daegwallyeong (37°41' N,128°45' E, 843 m ASL, mountain area) and Haenam (34°33' N,126°34' E, 4.6 m ASL, coast area). The vertical variations of rain rate and liquid water content in Daegwallyeong are smaller than those in Haenam. We think that this different vertical rain rate characteristic for both sites is due to the vertical different cloud type (convective and stratiform cloud seem dominant at Haenam and Daegwallyeong, respectively). This suggests that the statistical precipitation DSD model, for the application of weather radar and numerical simulation of precipitation processes, be considered differently for the region. More detailed analysis of vertical DSD and microphysical structure of precipitation measured by MRR will be presented at the conference.

  6. Higher Education Vertical Infrastructure Maintenance Planning.

    ERIC Educational Resources Information Center

    Weidner, Theodore J.

    To assist higher education facility officers in documenting their financial needs for renewing and renovating existing physical facilities, this study examined the accuracy against observed conditions of the tools used to identify vertical infrastructure maintenance needs in a large public university. Data developed for U.S. Army facilities is…

  7. Vertical distribution of natural radionuclides in soils

    NASA Astrophysics Data System (ADS)

    Blanco Rodríguez, P.; Tomé, F. Vera; Lozano, J. C.

    2012-04-01

    Low-level alpha spectrometry techniques using semiconductor detectors (PIPS) and liquid scintillation counters (LKB Quantulus 1220™) were used in order to determine the activity concentration of 238U, 232Th, 234U, 230Th, 226Ra, and 210Pb in soil samples. The soils were collected from an old disused uranium mine located in southwest Spain. The soils were selected with different levels of influence from the installation, in such a way that they had different levels of radioactive contamination. The vertical profiles in the soils (down to 40 cm depth) were studied in order to evaluate the vertical distribution of the natural radionuclides. The possible contamination of subsurface waters depends strongly on vertical migration, and the transfer to plants (herbs, shrubs, and trees) also will depend on the distribution of the radionuclides in the root zone. The study of the activity ratios between radionuclides belonging to the same series allowed us to assess the differing behaviour of the radionuclides involved. The vertical profiles for these radionuclides were different at each sampling point, showing the local impact of the installation. However, the profiles per point were similar for the long-lived radionuclides of the 238TJ series (238U, 234U, 230Th, and 226Ra). Also, a major disequilibrium was observed between 210Pb and 226Ra in the surface layer, due to 222Rn emanation and subsequent surface deposition of 210Pb.

  8. A Vertical Approach to Math Instruction

    ERIC Educational Resources Information Center

    Gojak, Linda

    2012-01-01

    In the current era of mathematics standards, whether they are Common Core State Standards or other state standards, effective vertical mathematics teams offer an opportunity for teachers to grow professionally through shared experiences, for leadership to grow among the faculty, and for the school to change its perspective on the teaching and…

  9. Viewing Vertical Objects with an Overhead Projector.

    ERIC Educational Resources Information Center

    Wild, R. L.

    1988-01-01

    Discusses the use of an overhead projector for the deflection of a vertical image to a screen. Describes three demonstrations: magnetizing of a steel ball bearing and paper clip; convection currents of a hot liquid within a cold liquid; and oscillation of concentrated salt solution into fresh water. (YP)

  10. Vertical pump with free floating check valve

    DOEpatents

    Lindsay, Malcolm (O'Hara Township, Allegheny County, PA)

    1980-01-01

    A vertical pump with a bottom discharge having a free floating check valve isposed in the outlet plenum thereof. The free floating check valve comprises a spherical member with a hemispherical cage-like member attached thereto which is capable of allowing forward or reverse flow under appropriate conditions while preventing reverse flow under inappropriate conditions.

  11. Hinged-Blade, Vertical-Shaft Windmill

    NASA Technical Reports Server (NTRS)

    Shultz, B., Jr.

    1985-01-01

    Vertical-shaft windmill concept calls for hinged, flapping blades to increase energy-conversion efficiency by reducing wind-energy loss. Hinged Blade Halves unfold to catch wind when moving with it, then fold away from wind when moving against it.

  12. Food Supply Chains with Vertical Integration

    E-print Network

    Nagurney, Anna

    Food Supply Chains with Vertical Integration SOM 822 Research Paper Diogo Souza-Monteiro Dep. of Resource Economics 05/10/2004 #12;Introduction Food Supply chains are becoming increasingly complex in different tiers of food chains. Barkena and Drabenstott (1995) claim that contracts are quickly taking

  13. Electrostatic comb drive for vertical actuation

    SciTech Connect

    Lee, A. P., LLNL

    1997-07-10

    The electrostatic comb finger drive has become an integral design for microsensor and microactuator applications. This paper reports on utilizing the levitation effect of comb fingers to design vertical-to-the-substrate actuation for interferometric applications. For typical polysilicon comb drives with 2 {micro}m gaps between the stationary and moving fingers, as well as between the microstructures and the substrate, the equilibrium position is nominally 1-2 {micro}m above the stationary comb fingers. This distance is ideal for many phase shifting interferometric applications. Theoretical calculations of the vertical actuation characteristics are compared with the experimental results, and a general design guideline is derived from these results. The suspension flexure stiffnesses, gravity forces, squeeze film damping, and comb finger thicknesses are parameters investigated which affect the displacement curve of the vertical microactuator. By designing a parallel plate capacitor between the suspended mass and the substrate, in situ position sensing can be used to control the vertical movement, providing a total feedback-controlled system. Fundamentals of various capacitive position sensing techniques are discussed. Experimental verification is carried out by a Zygo distance measurement interferometer.

  14. Vertical root fractures and their management

    PubMed Central

    Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj

    2014-01-01

    Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502

  15. A Simple Vertical Slab Gel Electrophoresis Apparatus.

    ERIC Educational Resources Information Center

    Carter, J. B.; And Others

    1983-01-01

    Describes an inexpensive, easily constructed, and safe vertical slab gel kit used routinely for sodium dodecyl sulphate-polyacrylamide gel electrophoresis research and student experiments. Five kits are run from a single transformer. Because toxic solutions are used, students are given plastic gloves and closely supervised during laboratory…

  16. Vertical nanopillars for highly localized fluorescence imaging

    E-print Network

    Cui, Yi

    of observation volume is required. Here, we demonstrate the use of vertically aligned silicon dioxide nanopillars much smaller than the wavelength of visible light, a transparent silicon dioxide nanopillar embedded-diffraction nano-bio interface The rapidly evolving field of nanotechnology creates new frontiers for biological

  17. Infrared Heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    IR heating was first industrially used in the 1930s for automotive curing applications and rapidly became a widely applied technology in the manufacturing industry. Contrarily, a slower pace in the development of IR technologies for processing foods and agricultural products was observed, due to lim...

  18. Latent Heating from TRMM Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Smith, E.; Olson, W.

    2005-01-01

    Rainfall production is a fundamental process within the Earth;s hydrological cycle because it represents both a principal forcing term in surface water budgets, and its energetics corollary, latent heating, is the principal source of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The properties of the vertical distribution of latent heat release modulate large-scale meridional and zonal circulations with the Tropics - as well as modify the energetic efficiencies of mid-latitude weather systems. This paper highlights the retrieval of observatory, which was launched in November 1997 as a joint American-Japanese space endeavor. Since then, TRMM measurements have been providing an accurate four-dimensional amount of rainfall over the global Tropics and sub-tropics - information which can be used to estimate the spacetime structure of latent heating across the Earth's low latitudes. A set of algorithm methodologies has and continues to be developed to estimate latent heating based on rain rate profile retrievals obtained from TRMM measurements. These algorithms are briefly described followed by a discussion of the foremost latent heating products that can be generate from them. The investigation then provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, concluding with remarks intended to stimulate further research on latent heating retrieval from satellites.

  19. SURFACE HEAT FLUX DERIVED FROM SODAR AMPLITUDE AND FREQUENCY DATA: A COMPARISON

    EPA Science Inventory

    Sensible heat flux measurements were made in an agricultural setting near Champaign, Illinois by using doppler sodar, eddy correlations and profile methods during convective conditions during an experimental study called VOICE, (Vertical Observations Involving Convective Exchange...

  20. Bayonet heat exchangers in heat-assisted Stirling heat pump

    SciTech Connect

    Yagyu, S.; Fukuyama, Y.; Morikawa, T.; Isshiki, N.; Satoh, I.; Corey, J.; Fellows, C.

    1998-07-01

    The Multi-Temperature Heat Supply System is a research project creating a city energy system with lower environmental load. This system consists of a gas-fueled internal combustion engine and a heat-assisted Stirling heat pump utilizing shaft power and thermal power in a combination of several cylinders. The heat pump is mainly driven by engine shaft power and is partially assisted by thermal power from engine exhaust heat source. Since this heat pump is operated by proportioning the two energy sources to match the characteristics of the driving engine, the system is expected to produce cooling and heating water at high COP. This paper describes heat exchanger development in the project to develop a heat-assisted Stirling heat pump. The heat pump employs the Bayonet type heat exchangers (BHX Type I) for supplying cold and hot water and (BHX Type II) for absorbing exhaust heat from the driving engine. The heat exchanger design concepts are presented and their heat transfer and flow loss characteristics in oscillating gas flow are investigated. The main concern in the BHX Type I is an improvement of gas side heat transfer and the spirally finned tubes were applied to gas side of the heat exchanger. For the BHX Type II, internal heat transfer characteristics are the main concern. Shell-and-tube type heat exchangers are widely used in Stirling machines. However, since brazing is applied to the many tubes for their manufacturing processes, it is very difficult to change flow passages to optimize heat transfer and loss characteristics once they have been made. The challenge was to enhance heat transfer on the gas side to make a highly efficient heat exchanger with fewer parts. It is shown that the Bayonet type heat exchanger can have good performance comparable to conventional heat exchangers.

  1. Entirely passive heat-pipe apparatus capable of operating against gravity

    DOEpatents

    Koenig, D.R.

    1981-02-11

    The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.

  2. The atmospheric heat budget over the western part of the Tibetan plateau during MONEX, 1979

    NASA Technical Reports Server (NTRS)

    Feng, Z.; Reiter, E. R.; Chen, L.

    1985-01-01

    The heat sources over the western part of the Tibetan Plateau for the period from May 19-August 31, 1979 are calculated. The use of the direct method to compute the total atmospheric heat source is examined. The values for the heat source over western, northwestern, and southwestern Tibet are presented. It is concluded that the atmospheric heat source is smaller during the summer than had been previously estimated; this difference is due to reduced drag coefficients. The northwestern and southwestern heat source values are compared, and it is observed that the northwestern heat source is independent on sensible heating and the southwestern heat source relates to the latent heat (LH). The calculated values correlate with the surface hydrology of these two regions. Time series analyses of the heat source components over the southwestern region reveal that LH is the primary modulator of the total atmospheric heat sources. The relation between the vertical heat distribution and Indian summer monsoons is studied.

  3. The vertical-mill stage : design of a vertical movement stage for surface machining

    E-print Network

    Herrera, Juan, Jr

    2007-01-01

    To allow the widespread use of three dimensional patterns on walls, the manufacturing cost must be reduced. The goal of this project is to design a machine for vertical axis movement which can be measured and controlled. ...

  4. Heat transfer coefficients of dilute flowing gas-solids suspensions

    NASA Technical Reports Server (NTRS)

    Kane, R. S.; Pfeffer, R.

    1973-01-01

    Heat transfer coefficients of air-glass, argon-glass, and argon-aluminum suspensions were measured in horizontal and vertical tubes. The glass, 21.6 and 36.0 micron diameter particles, was suspended at gas Reynolds numbers between 11,000 and 21,000 and loading ratios between 0 and 2.5. The presence of particles generally reduced the heat transfer coefficient. The circulation of aluminum powder in the 0.870 inch diameter closed loop system produced tenacious deposits on protuberances into the stream. In the vertical test section, the Nusselt number reduction was attributed to viscous sublayer thickening; in the horizontal test section to particle deposition.

  5. Solar heat plant

    SciTech Connect

    Tani, T.; Morita, M.; Nakamoto, Y.; Sakuta, K.; Sawata, S.; Sekiya, H.; Tanaka, T.; Yamagata, N.

    1984-05-22

    A solar heat plant comprises a first system including a high temperature heat collector for changing solar energy to high temperature heat energy under usual sunshine and to low temperature heat energy under poor sunshine to supply the heat energy to a high temperature heat medium, a high temperature heat load which works under usual sunshine using the heat energy supplied to the high temperature heat medium, a second system including a low temperature heat collector for changing solar energy to low temperature heat energy under usual or poor sunshine to supply the heat energy to a low temperature heat medium, and a low temperature heat load which works under usual sunshine using the heat energy supplied to the low temperature heat medium and also works under poor sunshine using the heat energies supplied to the high and low temperature heat media.

  6. Geothermal district heating systems

    SciTech Connect

    Budney, G.S.; Childs, F.

    1982-01-01

    Ten district heating demonstration projects and their present status are described. The projects are Klamath County YMCA, Susanville District Heating, Klamath Falls District Heating, Reno Salem Plaza Condominium, El Centro Community Center Heating/Cooling, Haakon School and Business District Heating, St. Mary's Hospital, Diamond Ring Ranch, Pagosa Springs District Heating, and Boise District Heating.

  7. Geothermal district heating systems

    NASA Astrophysics Data System (ADS)

    Budney, G. S.; Childs, F.

    1982-06-01

    Ten district heating demonstration projects and their present status are described. The projects are Klamath County YMCA, Susanville District Heating, Klamath Falls District Heating, Reno Salem Plaza Condominium, El Centro Community Center Heating/Cooling, Haakon School and Business District Heating, St. Mary's Hospital, Diamond Ring Ranch, Pagosa Springs District Heating, and Boise District Heating.

  8. Habitat Demonstration Unit (HDU) Vertical Cylinder Habitat

    NASA Technical Reports Server (NTRS)

    Howe, Alan; Kennedy, Kriss J.; Gill, Tracy R.; Tri, Terry O.; Toups, Larry; Howard, Robert I.; Spexarth, Gary R.; Cavanaugh, Stephen; Langford, William M.; Dorsey, John T.

    2014-01-01

    NASA's Constellation Architecture Team defined an outpost scenario optimized for intensive mobility that uses small, highly mobile pressurized rovers supported by portable habitat modules that can be carried between locations of interest on the lunar surface. A compact vertical cylinder characterizes the habitat concept, where the large diameter maximizes usable flat floor area optimized for a gravity environment and allows for efficient internal layout. The module was sized to fit into payload fairings for the Constellation Ares V launch vehicle, and optimized for surface transport carried by the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) mobility system. Launch and other loads are carried through the barrel to a top and bottom truss that interfaces with a structural support unit (SSU). The SSU contains self-leveling feet and docking interfaces for Tri-ATHLETE grasping and heavy lift. A pressurized module needed to be created that was appropriate for the lunar environment, could be easily relocated to new locations, and could be docked together in multiples for expanding pressurized volume in a lunar outpost. It was determined that horizontally oriented pressure vessels did not optimize floor area, which takes advantage of the gravity vector for full use. Hybrid hard-inflatable habitats added an unproven degree of complexity that may eventually be worked out. Other versions of vertically oriented pressure vessels were either too big, bulky, or did not optimize floor area. The purpose of the HDU vertical habitat module is to provide pressurized units that can be docked together in a modular way for lunar outpost pressurized volume expansion, and allow for other vehicles, rovers, and modules to be attached to the outpost to allow for IVA (intra-vehicular activity) transfer between them. The module is a vertically oriented cylinder with a large radius to allow for maximal floor area and use of volume. The modular, 5- m-diameter HDU vertical habitat module consists of a 2-m-high barrel with 0.6-mhigh end domes forming the 56-cubicmeter pressure vessel, and a 19-squaremeter floor area. The module has up to four docking ports located orthogonally from each other around the perimeter, and up to one docking port each on the top or bottom end domes. In addition, the module has mounting trusses top and bottom for equipment, and to allow docking with the ATHLETE mobility system. Novel or unique features of the HDU vertical habitat module include the nodelike function with multiple pressure hatches for docking with other versions of itself and other modules and vehicles; the capacity to be carried by an ATHLETE mobility system; and the ability to attach inflatable 'attic' domes to the top for additional pressurized volume.

  9. Performance of various RANS eddy-viscosity models for turbulent natural convection in tall vertical cavities

    NASA Astrophysics Data System (ADS)

    El Moutaouakil, L.; Zrikem, Z.; Abdelbaki, A.

    2014-08-01

    The present study is dedicated to the identification of turbulence models that are accurate and numerically economic for computing the natural air-flow and heat transfer by convection in tall cavities with differentially heated vertical walls. The eddy-viscosity models (EVM) are among the simplest to implement and the most economical to treat this problem. This study evaluated the dynamic, thermal and computational performances of twenty EVM turbulence models with one, two or three-equation closure. All the models were first implemented in several in-house codes using the finite volume method. The predictions of the retained models in terms of profiles of velocity, temperature and vertical velocity fluctuations in the cavity have been compared with those of experimental or numerical studies. The obtained results were used to identify the turbulence models that are accurate and numerically economic in predicting natural convection in vertical cavities with a high aspect ratio. The EVM models with three-equation (v2-f and ?-f) provide the most accurate mean and fluctuating quantities, followed by the k-? RNG (ReNormalization Group) and k-? SST (Shear Stress Transport) models. The computing time of these four models is higher than that of the 2L (two-layer) and q-? models, which provide fairly accurate results especially for the mean heat transfer between the vertical active walls. The other one-equation (Spalart and Allmaras model) and two-equation (k-?, k-? and hybrid models) turbulence models tested in this work, have a high computing time and/or predictions that are not sufficiently precise simultaneously for both velocity and temperature fields.

  10. Vertical structure of Arctic haze observed by lidar

    NASA Technical Reports Server (NTRS)

    Hoff, R. M.

    1986-01-01

    In the study of the Arctic Haze phenomenon, understanding the vertical structure of the haze aerosol is crucial in defining mechanisms of haze transport. Questions have also arisen concerning the representativeness of surface observations of Arctic Haze. Due to the strongly stratified nature of the Arctic troposphere, the mechanisms which transport aerosol to the surface from the transport altitudes of the lower troposphere are not obvious. In order to examine these questions, a Mie scattering lidar was installed at Alert, NWT, Canada. Lidar observes atmospheric aerosols and hydrymeteors as they appear in nature, unmodified by sampling effects. As such the results obtained are more realistic of the light scattering characteristics of the in situ aerosol than are those obtained by integrating nephelometers, for example, which heat the aerosol and dry it before measurement. With this lidar, a pulse was transmitted vetically through an evacuated tube in the roof of a building at Alert. The receiver consisted of a 20cm diameter Fresnel telescope, neutral density and polarizing filters, and RCA C31000A PMT, Analog Modules LA-90-P logarithmic amplifier and a Lecroy TR8827 32 MHz digitizer. The lidar equation was solved for the backscattering coefficient of the aerosol assuming no two way transmission losses in the signal. The lidar results have shown that intercomparison between lidar obtained visibilities and observer visibilities are in much better agreement than for other optical or aerosol monitors. Three new effects were identified in the lidar profiles which contribute to the vertical transport of haze. These effects are briefly discussed.

  11. Magnetic induced heating for ferritic metal annealing

    SciTech Connect

    De Witt, G.L.; Huber, D.J.

    1987-03-24

    A method is described for annealing the wall of a nuclear reactor vessel, including, positioning an electromagnet within a vertically positioned nuclear reactor vessel by lowering the electromagnet into the vessel, supplying power to the electromagnet to generate substantially uniform heat in the vessel wall, maintaining the power to the electromagnet for a predetermined length of time which will anneal the vessel wall, and removing the electromagnet.

  12. Orientation mount for a solar heating module

    SciTech Connect

    Lhenry, B.

    1984-07-10

    The present invention relates to an elevation orientation mount for a parabolic mirror reflector of a solar heating module. The altazimuthal orientation mount according to the invention is adapted to a solar heating module comprising a parabolic mirror reflector orientable around a horizontal axis by a jack actuating unit whose cylinder is a turret and whose rod is articulated to the reflector. The jack is equipped for return and locking tending to extend the rod and to lock it at the stroke-end where the reflector occupies a position such that its axis of revolution is vertical.

  13. Heat pump system

    DOEpatents

    Swenson, Paul F. (Cleveland, OH); Moore, Paul B. (Fedhaurn, FL)

    1982-01-01

    An air heating and cooling system for a building includes an expansion-type refrigeration circuit and a heat engine. The refrigeration circuit includes two heat exchangers, one of which is communicated with a source of indoor air from the building and the other of which is communicated with a source of air from outside the building. The heat engine includes a heat rejection circuit having a source of rejected heat and a primary heat exchanger connected to the source of rejected heat. The heat rejection circuit also includes an evaporator in heat exchange relation with the primary heat exchanger, a heat engine indoor heat exchanger, and a heat engine outdoor heat exchanger. The indoor heat exchangers are disposed in series air flow relationship, with the heat engine indoor heat exchanger being disposed downstream from the refrigeration circuit indoor heat exchanger. The outdoor heat exchangers are also disposed in series air flow relationship, with the heat engine outdoor heat exchanger disposed downstream from the refrigeration circuit outdoor heat exchanger. A common fluid is used in both of the indoor heat exchanges and in both of the outdoor heat exchangers. In a first embodiment, the heat engine is a Rankine cycle engine. In a second embodiment, the heat engine is a non-Rankine cycle engine.

  14. Lunar vertical-shaft mining system

    NASA Technical Reports Server (NTRS)

    Introne, Steven D. (editor); Krause, Roy; Williams, Erik; Baskette, Keith; Martich, Frederick; Weaver, Brad; Meve, Jeff; Alexander, Kyle; Dailey, Ron; White, Matt

    1994-01-01

    This report proposes a method that will allow lunar vertical-shaft mining. Lunar mining allows the exploitation of mineral resources imbedded within the surface. The proposed lunar vertical-shaft mining system is comprised of five subsystems: structure, materials handling, drilling, mining, and planning. The structure provides support for the exploration and mining equipment in the lunar environment. The materials handling subsystem moves mined material outside the structure and mining and drilling equipment inside the structure. The drilling process bores into the surface for the purpose of collecting soil samples, inserting transducer probes, or locating ore deposits. Once the ore deposits are discovered and pinpointed, mining operations bring the ore to the surface. The final subsystem is planning, which involves the construction of the mining structure.

  15. Coupled Resonator Vertical Cavity Laser Diode

    SciTech Connect

    CHOQUETTE, KENT D.; CHOW, WENG W.; FISCHER, ARTHUR J.; GEIB, KENT M.; HOU, HONG Q.

    1999-09-16

    We report the operation of an electrically injected monolithic coupled resonator vertical cavity laser which consists of an active cavity containing In{sub x}Ga{sub 1{minus}x}As quantum wells optically coupled to a passive GaAs cavity. This device demonstrates novel modulation characteristics arising from dynamic changes in the coupling between the active and passive cavities. A composite mode theory is used to model the output modulation of the coupled resonator vertical cavity laser. It is shown that the laser intensity can be modulated by either forward or reverse biasing the passive cavity. Under forward biasing, the modulation is due to carrier induced changes in the refractive index, while for reverse bias operation the modulation is caused by field dependent cavity enhanced absorption.

  16. Ultimately short ballistic vertical graphene Josephson junctions

    PubMed Central

    Lee, Gil-Ho; Kim, Sol; Jhi, Seung-Hoon; Lee, Hu-Jong

    2015-01-01

    Much efforts have been made for the realization of hybrid Josephson junctions incorporating various materials for the fundamental studies of exotic physical phenomena as well as the applications to superconducting quantum devices. Nonetheless, the efforts have been hindered by the diffusive nature of the conducting channels and interfaces. To overcome the obstacles, we vertically sandwiched a cleaved graphene monoatomic layer as the normal-conducting spacer between superconducting electrodes. The atomically thin single-crystalline graphene layer serves as an ultimately short conducting channel, with highly transparent interfaces with superconductors. In particular, we show the strong Josephson coupling reaching the theoretical limit, the convex-shaped temperature dependence of the Josephson critical current and the exceptionally skewed phase dependence of the Josephson current; all demonstrate the bona fide short and ballistic Josephson nature. This vertical stacking scheme for extremely thin transparent spacers would open a new pathway for exploring the exotic coherence phenomena occurring on an atomic scale. PMID:25635386

  17. Vertically Integrated Multiple Nanowire Field Effect Transistor.

    PubMed

    Lee, Byung-Hyun; Kang, Min-Ho; Ahn, Dae-Chul; Park, Jun-Young; Bang, Tewook; Jeon, Seung-Bae; Hur, Jae; Lee, Dongil; Choi, Yang-Kyu

    2015-12-01

    A vertically integrated multiple channel-based field-effect transistor (FET) with the highest number of nanowires reported ever is demonstrated on a bulk silicon substrate without use of wet etching. The driving current is increased by 5-fold due to the inherent vertically stacked five-level nanowires, thus showing good feasibility of three-dimensional integration-based high performance transistor. The developed fabrication process, which is simple and reproducible, is used to create multiple stiction-free and uniformly sized nanowires with the aid of the one-route all-dry etching process (ORADEP). Furthermore, the proposed FET is revamped to create nonvolatile memory with the adoption of a charge trapping layer for enhanced practicality. Thus, this research suggests an ultimate design for the end-of-the-roadmap devices to overcome the limits of scaling. PMID:26544156

  18. Industrial Waste Heat Recovery Using Heat Pipes 

    E-print Network

    Ruch, M. A.

    1981-01-01

    For almost a decade now, heat pipes with secondary finned surfaces have been utilized in counter flow heat exchangers to recover sensible energy from industrial exhaust gases. Over 3,000 such heat exchangers are now in service, recovering...

  19. Water and Space Heating Heat Pumps 

    E-print Network

    Kessler, A. F.

    1985-01-01

    fossil fired heating units or electric resistance water heaters. When electric resistance water heaters are utilized there are three alternative electric heating concepts available to reduce home energy consumption. They are desuperheaters, dedicated heat...

  20. Latent Heating from TRMM Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Smith, E. A.; Adler, R.; Haddad, Z.; Hou, A.; Iguchi, T.; Kakar, R.; Krishnamurti, T.; Kummerow, C.; Lang, S.

    2004-01-01

    Rainfall production is the fundamental variable within the Earth's hydrological cycle because it is both the principal forcing term in surface water budgets and its energetics corollary, latent heating, is the principal source of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The properties of the vertical distribution of latent heat release modulate large-scale meridional and zonal circulations within the tropics - as well as modifying the energetic efficiencies of midlatitude weather systems. This paper focuses on the retrieval of latent heat release from satellite measurements generated by the Tropical Rainfall Measuring Mission (TRMM) satellite observatory, which was launched in November 1997 as a joint American-Japanese space endeavor. Since then, TRMM measurements have been providing an accurate four-dimensional account of rainfall over the global tropics and sub-tropics, information which can be used to estimate the space-time structure of latent heating across the Earth's low latitudes. The paper examines how the observed TRMM distribution of rainfall has advanced an understanding of the global water and energy cycle and its consequent relationship to the atmospheric general circulation and climate via latent heat release. A set of algorithm methodologies that are being used to estimate latent heating based on rain rate retrievals from the TRMM observations are described. The characteristics of these algorithms and the latent heating products that can be generated from them are also described, along with validation analyses of the heating products themselves. Finally, the investigation provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, concluding with remarks intended to stimulate further research on latent heating retrieval from satellites.

  1. The distinctive vertical heterophoria of dyslexics

    PubMed Central

    Quercia, Patrick; Quercia, Madeleine; Feiss, Léonard J; Allaert, François

    2015-01-01

    In this study, we looked for the presence of vertical heterophoria (VH) in 42 dyslexic children (22 males and 20 females) aged 118.5±12.9 months who were compared with a control group of 22 nondyslexic children (eleven males and eleven females) aged 112±9.8 months. Dyslexics presented a low-level (always <1 prism diopter) VH combined with torsion. This oculomotor feature clearly separates the dyslexic group from the normal readers group. It is independent of the type of dyslexia. The essential feature of this VH is a lability that appears during specific stimulation of sensory receptors involved in postural regulation. This lability is demonstrated using a vertical Maddox test conducted under very specific conditions in which postural sensors are successively stimulated in a predetermined order. A quantitative variation in this VH may be seen during the Bielchowsky Head Tilt Test, which reveals hypertonia of the lower or upper oblique muscles. Vertical orthophoria can be achieved by placing low-power prisms asymmetrically within the direction of action of the superior or inferior oblique muscles. The selection of power and axis is not only guided by elements of the eye examination but also from observation of postural muscle tone. All these elements suggest that the VH could be of postural origin and somehow related to the vertical action of the oblique muscles. VH and torsion are not harmful per se. There is no statistical relationship between their level and the various parameters used to assess the reading skills of dyslexic children. VH and torsion could be a clinical marker of global proprioceptive dysfunction responsible for high-level multisensory disturbances secondary to poor spatial localization of visual and auditory information. This dysfunction might also explain the motor disorders concomitant to dyslexia. PMID:26445526

  2. Present day vertical deformation in New Zealand

    NASA Astrophysics Data System (ADS)

    Hreinsdóttir, Sigrún; Wallace, Laura; Litchfield, Nicola; D'Anastasio, Elisabetta; Denys, Paul; Pearson, Christopher

    2014-05-01

    New Zealand is tectonically very active. It lies along the oblique convergent plate boundary between the Pacific and Australian plate. In the North Island active tectonics is dominated by westward subduction of the Pacific Plate beneath the eastern North Island at the Hikurangi Trench, strike-slip faulting in the upper plate, and back-arc rifting in the central North Island. A series of very large strike-slip faults run through the South Island (Marlborough Fault System and the Alpine Fault) connecting with the Puysegur subduction zone in the south. The present day uplift rates are evaluated by analyzing data from continuous GPS stations in New Zealand. The up to 20 years of continuous GPS gives us a snapshot into the deformation rate. The average velocity is corrected for significant coseismic offsets, but the data can also be influenced by postseismic deformation, slow slip events along the Hikurangi subduction zone, volcanic deformation, as well as none tectonic local affects such as water extraction. We evaluate the interseismic vertical rate. We exclude data significantly affected by postseismic deformation from recent earthquakes and provide vertical rates both with and without correcting for slow slip events. Outside the Taupo rift zone the vertical rates are range from -6 to +6 mm/yr with uplift observed across the Alpine fault, few mm/yr uplift around the Raukumara Peninsula, northeast North Island, and subsidence along the southeast North Island, reflecting variation in plate locking. We compare the present day vertical deformation to the long-term motion along the coast determined primarily from 125,000 years old marine geological markers. The largest proportion of the New Zealand coastline (45%) is undergoing long-term tectonic uplift. Small stretches of the coastline (15%) are undergoing long-term subsidence. Areas farthest from the plate boundary (northern North Island and southeastern South Island) are assessed to be tectonically stable, in agreement with the continuous GPS data.

  3. The distinctive vertical heterophoria of dyslexics.

    PubMed

    Quercia, Patrick; Quercia, Madeleine; Feiss, Léonard J; Allaert, François

    2015-01-01

    In this study, we looked for the presence of vertical heterophoria (VH) in 42 dyslexic children (22 males and 20 females) aged 118.5±12.9 months who were compared with a control group of 22 nondyslexic children (eleven males and eleven females) aged 112±9.8 months. Dyslexics presented a low-level (always <1 prism diopter) VH combined with torsion. This oculomotor feature clearly separates the dyslexic group from the normal readers group. It is independent of the type of dyslexia. The essential feature of this VH is a lability that appears during specific stimulation of sensory receptors involved in postural regulation. This lability is demonstrated using a vertical Maddox test conducted under very specific conditions in which postural sensors are successively stimulated in a predetermined order. A quantitative variation in this VH may be seen during the Bielchowsky Head Tilt Test, which reveals hypertonia of the lower or upper oblique muscles. Vertical orthophoria can be achieved by placing low-power prisms asymmetrically within the direction of action of the superior or inferior oblique muscles. The selection of power and axis is not only guided by elements of the eye examination but also from observation of postural muscle tone. All these elements suggest that the VH could be of postural origin and somehow related to the vertical action of the oblique muscles. VH and torsion are not harmful per se. There is no statistical relationship between their level and the various parameters used to assess the reading skills of dyslexic children. VH and torsion could be a clinical marker of global proprioceptive dysfunction responsible for high-level multisensory disturbances secondary to poor spatial localization of visual and auditory information. This dysfunction might also explain the motor disorders concomitant to dyslexia. PMID:26445526

  4. Vertical Carbon Nanotube Device in Nanoporous Templates

    NASA Technical Reports Server (NTRS)

    Maschmann, Matthew Ralph (Inventor); Fisher, Timothy Scott (Inventor); Sands, Timothy (Inventor); Bashir, Rashid (Inventor)

    2014-01-01

    A modified porous anodic alumina template (PAA) containing a thin CNT catalyst layer directly embedded into the pore walls. CNT synthesis using the template selectively catalyzes SWNTs and DWNTs from the embedded catalyst layer to the top PAA surface, creating a vertical CNT channel within the pores. Subsequent processing allows for easy contact metallization and adaptable functionalization of the CNTs and template for a myriad of applications.

  5. Spirit 360-Degree View, Sol 388 (vertical)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Mars Exploration Rover Spirit used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on Spirit's 388th martian day, or sol (Feb. 4, 2005). Spirit had driven about 13 meters (43 feet) uphill toward 'Cumberland Ridge' on this sol. This location is catalogued as Spirit's Site 102, Position 513. The view is presented in a vertical projection with geometric and brightness seam correction.

  6. Inverse scattering problem for quantum graph vertices

    E-print Network

    Taksu Cheon; Pavel Exner; Ondrej Turek

    2011-04-06

    We demonstrate how the inverse scattering problem of a quantum star graph can be solved by means of diagonalization of Hermitian unitary matrix when the vertex coupling is of the scale invariant (or F\\"ul\\H{o}p-Tsutsui) form. This enables the construction of quantum graphs with desired properties in a tailor-made fashion. The procedure is illustrated on the example of quantum vertices with equal transmission probabilities.

  7. Centro-lateral subperiosteal vertical midface lift

    PubMed Central

    Hönig, Johannes Franz; Knutti, Daniel; Hasse, Frank Michael

    2014-01-01

    The use of fiberendoscopic video-assisted technique in facial rejuvenation is one of the most advances in aesthetic plastic surgery of the face. It substitutes the coronal incision without the necessity of skin resection and allows a vertical reposition of the mobile soft tissue of the midface in indicated cases. It can easily be done through a small incision of the scalp just behind the coronal incision and in the temporal area. PMID:26504715

  8. Engineering high-performance vertical cavity lasers

    SciTech Connect

    Lear, K.L.; Hou, H.Q.; Hietala, V.M.; Choquette, K.D.; Schneider, R.P. Jr.

    1996-12-31

    The cw and high-speed performance of vertical cavity surface emitting laser diodes (VCSELs) are affected by both electrical and optical issues arising from the geometry and fabrication of these devices. Structures with low resistance semiconductor mirrors and Al-oxide confinement layers address these issues and have produced record performance including 50% power conversion efficiency and modulation bandwidths up to 20 GHz at small bias currents.

  9. Electrically floating, near vertical incidence, skywave antenna

    DOEpatents

    Anderson, Allen A.; Kaser, Timothy G.; Tremblay, Paul A.; Mays, Belva L.

    2014-07-08

    An Electrically Floating, Near Vertical Incidence, Skywave (NVIS) Antenna comprising an antenna element, a floating ground element, and a grounding element. At least part of said floating ground element is positioned between said antenna element and said grounding element. The antenna is separated from the floating ground element and the grounding element by one or more electrical insulators. The floating ground element is separated from said antenna and said grounding element by one or more electrical insulators.

  10. Inverse scattering problem for quantum graph vertices

    SciTech Connect

    Cheon, Taksu; Turek, Ondrej; Exner, Pavel

    2011-06-15

    We demonstrate how the inverse scattering problem of a quantum star graph can be solved by means of diagonalization of the Hermitian unitary matrix when the vertex coupling is of the scale-invariant (or Fueloep-Tsutsui) form. This enables the construction of quantum graphs with desired properties in a tailor-made fashion. The procedure is illustrated on the example of quantum vertices with equal transmission probabilities.

  11. Radially Magnetized Protoplanetary Disk: Vertical Profile

    NASA Astrophysics Data System (ADS)

    Russo, Matthew; Thompson, Christopher

    2015-11-01

    This paper studies the response of a thin accretion disk to an external radial magnetic field. Our focus is on protoplanetary disks (PPDs), which are exposed during their later evolution to an intense, magnetized wind from the central star. A radial magnetic field is mixed into a thin surface layer, wound up by the disk shear, and pushed downward by a combination of turbulent mixing and ambipolar and ohmic drift. The toroidal field reaches much greater strengths than the seed vertical field that is usually invoked in PPD models, even becoming superthermal. Linear stability analysis indicates that the disk experiences the magnetorotational instability (MRI) at a higher magnetization than a vertically magnetized disk when both the effects of ambipolar and Hall drift are taken into account. Steady vertical profiles of density and magnetic field are obtained at several radii between 0.06 and 1 AU in response to a wind magnetic field Br ? (10?4–10?2)(r/ AU)?2 G. Careful attention is given to the radial and vertical ionization structure resulting from irradiation by stellar X-rays. The disk is more strongly magnetized closer to the star, where it can support a higher rate of mass transfer. As a result, the inner ?1 AU of a PPD is found to evolve toward lower surface density. Mass transfer rates around 10?8 M? yr?1 are obtained under conservative assumptions about the MRI-generated stress. The evolution of the disk and the implications for planet migration are investigated in the accompanying paper.

  12. Vertical flight path steering system for aircraft

    NASA Technical Reports Server (NTRS)

    Lambregts, Antonius A. (Inventor)

    1983-01-01

    Disclosed is a vertical flight path angle steering system for aircraft, utilizing a digital flight control computer which processes pilot control inputs and aircraft response parameters into suitable elevator commands and control information for display to the pilot on a cathode ray tube. The system yields desirable airplane control handling qualities and responses as well as improvements in pilot workload and safety during airplane operation in the terminal area and under windshear conditions.

  13. Vertical leaf pressure filter LVAzh 225

    SciTech Connect

    Fomichev, V.I.; Abramov, V.P.; Gutin, Y.V.

    1984-01-01

    A new vertical lead pressure filter LVAzh 225 has been developed with an arrangement for hydraulic coke removal. Industrial trials of the filter, however, showed the service life of the rubber seals of the butterfly valves to be short, so that butterfly valves were replaced by shut-off valves with a pneumatic drive. The prototype of the LVAzh 225 leaf filter has been recommended for series production.

  14. Heat-Exchanger/Heat-Pipe Interface

    NASA Technical Reports Server (NTRS)

    Snyder, H. J.; Van Hagan, T. H.

    1987-01-01

    Monolithic assembly reliable and light in weight. Heat exchanger and evaporator ends of heat pipes integrated in monolithic halves welded together. Interface assembly connects heat exchanger of furnace, reactor, or other power source with heat pipes carrying heat to radiator or power-consuming system. One of several concepts proposed for nuclear power supplies aboard spacecraft, interface useful on Earth in solar thermal power systems, heat engines, and lightweight cooling systems.

  15. Orthogonal Thin Film Photovoltaics on Vertical Nanostructures.

    PubMed

    Ahnood, Arman; Zhou, H; Suzuki, Y; Sliz, R; Fabritius, T; Nathan, Arokia; Amaratunga, G A J

    2015-12-01

    Decoupling paths of carrier collection and illumination within photovoltaic devices is one promising approach for improving their efficiency by simultaneously increasing light absorption and carrier collection efficiency. Orthogonal photovoltaic devices are core-shell type structures consisting of thin film photovoltaic stack on vertical nanopillar scaffolds. These types of devices allow charge collection to take place in the radial direction, perpendicular to the path of light in the vertical direction. This approach addresses the inherently high recombination rate of disordered thin films, by allowing semiconductor films with minimal thicknesses to be used in photovoltaic devices, without performance degradation associated with incomplete light absorption. This work considers effects which influence the performance of orthogonal photovoltaic devices. Illumination non-uniformity as light travels across the depth of the pillars, electric field enhancement due to the nanoscale size and shape of the pillars, and series resistance due to the additional surface structure created through the use of pillars are considered. All of these effects influence the operation of orthogonal solar cells and should be considered in the design of vertically nanostructured orthogonal photovoltaics. PMID:26676997

  16. Radially Magnetized Protoplanetary Disk: Vertical Profile

    E-print Network

    Russo, Matthew

    2015-01-01

    This paper studies the response of a thin accretion disk to an external radial magnetic field. Our focus is on protoplanetary disks (PPDs), which are exposed during their later evolution to an intense, magnetized wind from the central star. A radial magnetic field is mixed into a thin surface layer, is wound up by the disk shear, and is pushed downward by a combination of turbulent mixing and ambipolar and Ohmic drift. The toroidal field reaches much greater strengths than the seed vertical field that is usually invoked in PPD models, even becoming superthermal. Linear stability analysis indicates that the disk experiences the magnetorotational instability (MRI) at a higher magnetization than a vertically magnetized disk when both the effects of ambipolar and Hall drift are taken into account. Steady vertical profiles of density and magnetic field are obtained at several radii between 0.06 and 1 AU in response to a wind magnetic field $B_r \\sim (10^{-4}$-$10^{-2})(r/{\\rm AU})^{-2}$ G. Careful attention is giv...

  17. Human sensitivity to vertical self-motion.

    PubMed

    Nesti, Alessandro; Barnett-Cowan, Michael; Macneilage, Paul R; Bülthoff, Heinrich H

    2014-01-01

    Perceiving vertical self-motion is crucial for maintaining balance as well as for controlling an aircraft. Whereas heave absolute thresholds have been exhaustively studied, little work has been done in investigating how vertical sensitivity depends on motion intensity (i.e., differential thresholds). Here we measure human sensitivity for 1-Hz sinusoidal accelerations for 10 participants in darkness. Absolute and differential thresholds are measured for upward and downward translations independently at 5 different peak amplitudes ranging from 0 to 2 m/s(2). Overall vertical differential thresholds are higher than horizontal differential thresholds found in the literature. Psychometric functions are fit in linear and logarithmic space, with goodness of fit being similar in both cases. Differential thresholds are higher for upward as compared to downward motion and increase with stimulus intensity following a trend best described by two power laws. The power laws' exponents of 0.60 and 0.42 for upward and downward motion, respectively, deviate from Weber's Law in that thresholds increase less than expected at high stimulus intensity. We speculate that increased sensitivity at high accelerations and greater sensitivity to downward than upward self-motion may reflect adaptations to avoid falling. PMID:24158607

  18. Convection effects on radial segregation and crystal melt interface in vertical Bridgman growth

    NASA Technical Reports Server (NTRS)

    Tanveer, S.

    1993-01-01

    We analytically study the influence of convection caused by horizontal heat transfer through the sides of a vertical Bridgman apparatus. We consider the case when the heat transfer across the side walls is small so that the resulting interfacial deformation and fluid velocities are also small. This allows us to linearize the Navier-Stokes equations and express the interfacial conditions about a planar interface through a Taylor expansion. Using a no tangential stress conditions on the side walls, asymptotic expressions for both the interfacial slope, and radial segregation at the crystal-melt interface are obtained in closed form in the limit of large thermal Rayleigh number. It is suggested that these can be reduced by appropriately controlling a specific heat transfer property at the edge of the insulation zone in the solid side.

  19. Interface Shape Control Using Localized Heating during Bridgman Growth

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Mazuruk, K.; Aggarwal, M. D.; Croll, A.

    2008-01-01

    Numerical calculations were performed to assess the effect of localized radial heating on the melt-crystal interface shape during vertical Bridgman growth. System parameters examined include the ampoule, melt and crystal thermal conductivities, the magnitude and width of localized heating, and the latent heat of crystallization. Concave interface shapes, typical of semiconductor systems, could be flattened or made convex with localized heating. Although localized heating caused shallower thermal gradients ahead of the interface, the magnitude of the localized heating required for convexity was less than that which resulted in a thermal inversion ahead of the interface. A convex interface shape was most readily achieved with ampoules of lower thermal conductivity. Increasing melt convection tended to flatten the interface, but the amount of radial heating required to achieve a convex interface was essentially independent of the convection intensity.

  20. Heating systems for heating subsurface formations

    DOEpatents

    Nguyen, Scott Vinh (Houston, TX); Vinegar, Harold J. (Bellaire, TX)

    2011-04-26

    Methods and systems for heating a subsurface formation are described herein. A heating system for a subsurface formation includes a sealed conduit positioned in an opening in the formation and a heat source. The sealed conduit includes a heat transfer fluid. The heat source provides heat to a portion of the sealed conduit to change phase of the heat transfer fluid from a liquid to a vapor. The vapor in the sealed conduit rises in the sealed conduit, condenses to transfer heat to the formation and returns to the conduit portion as a liquid.

  1. Heat pipe waste heat recovery boilers

    NASA Astrophysics Data System (ADS)

    Littwin, D. A.; McCurley, J.

    The use of heat pipes as transport devices in waste heat recovery boilers is examined. Test results show that heat pipes can efficiently extract heat from the hot gas stream and transfer it inside the pressure vessel for the steam generation process. The benefits of incorporating heat pipes into the design of waste heat recovery boilers include a highly compact package, a significant reduction in thermally induced stresses, double isolation of the steam from the heat source, an extended surface for improved efficiency in heat extraction, improved circulation and stability in the boiling regime, easy cleaning, individually replaceable tubes, and low flue gas pressure drop.

  2. The Vertical Structure of Second-Order Turbulence Moments in the Stable Boundary Layer from SABLES98 Observations

    NASA Astrophysics Data System (ADS)

    Tampieri, F.; Yagüe, C.; Viana, S.

    2015-10-01

    Observations of the stable boundary layer (SBL) obtained during the SABLES98 experiment are analyzed in order to investigate the vertical variations of the momentum flux , the heat flux (0 in stable conditions) and the turbulent kinetic energy . The traditional SBL is identified on the basis of the momentum and heat fluxes respectively decreasing and increasing with height; the vertical scales obtained from the profiles of , and give indications about the depth of the boundary layer, and are shown to be different for the different statistical moments. The upside-down SBL cases are defined by the momentum flux and the turbulent kinetic energy increasing with height, while the heat flux can increase or decrease with height. Also in this case the vertical scales differ for the different statistical moments. The observations show that the stability (evaluated from the gradient Richardson number or the Obukhov length) is not a univocal index that discriminates between traditional and upside-down cases. The scales allow a compact description of the vertical structure of the traditional and upside-down SBL in terms of the considered statistical moments and of the gradient Richardson number, and are used to interpret the variation of the Obukhov length with height.

  3. ostglacial rebound from VLBI Geodesy: On Establishing Vertical Reference

    NASA Technical Reports Server (NTRS)

    Argus, Donald .

    1996-01-01

    I propose that a useful reference frame for vertical motions is that found by minimizing differences between vertical motions observed with VLBI [Ma and Ryan, 1995] and predictions from postglacial rebound predictions [Peltier, 1995].

  4. Performance of a well with lateral and vertical wellbores 

    E-print Network

    Abdat, Toriq

    2002-01-01

    angles only up to 60°. Further increasing the well angle will not make the well performance better than a vertical well. We have modeled and analyzed performance of combination wells. We compared the performance of vertical, slanted, and combination...

  5. A Vertical Grid Module for Baroclinic Models of the Atmosphere

    SciTech Connect

    Drake, John B

    2008-04-01

    The vertical grid of an atmospheric model assigns dynamic and thermo- dynamic variables to grid locations. The vertical coordinate is typically not height but one of a class of meteorological variables that vary with atmo- spheric conditions. The grid system is chosen to further numerical approx- imations of the boundary conditions so that the system is terrain following at the surface. Lagrangian vertical coordinates are useful in reducing the numerical errors from advection processes. That the choices will effect the numercial properties and accuracy is explored in this report. A MATLAB class for Lorentz vertical grids is described and applied to the vertical struc- ture equation and baroclinic atmospheric circulation. A generalized meteo- rolgoical coordinate system is developed which can support ?, isentropic ? vertical coordinate, or Lagrangian vertical coordinates. The vertical atmo- spheric column is a MATLAB class that includes the kinematic and ther- modynamic variables along with methods for computing geopoentials and terms relevant to a 3D baroclinc atmospheric model.

  6. Signal Threshold Adaptation for Vertical Handoff in Heterogeneous Wireless Networks

    E-print Network

    Liang, Ben

    Signal Threshold Adaptation for Vertical Handoff in Heterogeneous Wireless Networks Ahmed H. Zahran. Keywords: heterogeneous wireless networks, seamless integration, vertical handoff, application signal in heterogeneous wireless system Mobility management is a main challenge in the converged network. It ad- dresses

  7. Functionality Tuning in Vertically Aligned Nanocomposite Thin Films 

    E-print Network

    Chen, Aiping

    2013-04-04

    Vertically aligned nanocomposite (VAN) oxide thin films are unique nanostructures with two-phase self-assembled, heteroepitaxially grown on single-crystal substrates. Both phases tend to grow vertically and simultaneously ...

  8. Vertical axis wind turbine with continuous blade angle adjustment

    E-print Network

    Weiss, Samuel Bruce

    2010-01-01

    The author presents a concept for a vertical axis wind turbine that utilizes each blade's entire rotational cycle for power generation. Each blade has its own vertical axis of rotation and is constrained to rotate at the ...

  9. Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Joint, Vertical Cross Bracing End Detail - Ceylon Covered Bridge, Limberlost Park, spanning Wabash River at County Road 900 South, Geneva, Adams County, IN

  10. High power heat pipe heat exchanger development

    SciTech Connect

    Fale, J.E.; Zuo, Z.J.; Gernert, N.J.; Goryca, M.L.

    1998-07-01

    This paper presents the results of a recently completed SBIR Phase 2 program by Thermacore, Inc. to develop a 350kW heat pipe radiator for the M109 A6 Howitzer engine cooling. After a brief discussion of operating principles and unique advantages of heat pipe heat exchangers, the paper focuses on the development of high power heat pipe heat exchangers. Design and manufacturing issues associated with high power heat pipe heat exchangers, such as non-uniform heat load distribution, redundancy/damage resistance, and seals between the two fluid streams, are addressed. Test results of segment and full scale heat pipe radiators are presented. Heat pipe heat exchanger applications, including the potential applications in the turbine industry and the food and pharmaceutical industry, are discussed.

  11. Retrievals Of Vertical Motion in Convective Precipitating Systems: an ARM Perspective

    NASA Astrophysics Data System (ADS)

    Collis, S. M.; Giangrande, S. E.; North, K.; Protat, A.; Kumar, V.; Helmus, J.; Kollias, P.

    2013-12-01

    Vertical motions in the atmosphere link many processes, controlling processes such as accretion rates, species transport (water vapor, aerosols) and radiative properties of detrained cloud anvils, and being strongly influenced my many scales of dynamical forcing, latent heat feedbacks and entrainment. Due to this, statistical properties of vertical motion can act as an observational target for fine scale (eg LES, CRM) models. Determining the veracity of processes in such models is vital as these are commonly used to asses processes in Single column and global models. However retrievals of vertical motions in these systems is complicated by many factors including sampling, the veracity of constraints and boundary and initial conditions used in the retrieval. Therefore a multi-scale approach is needed, using a mix of independent measurements and retrieval techniques to build an understanding of the vertical velocity spectrum in these systems. This presentation will cover work across the ARM facility including retrievals from the Darwin Tropical West Pacific (Australia) and the Oklahoma, Southern Great Plains (USA) site. By initially focusing on Intensive Observational Periods such as TWP-ICE and MC3E retrieval efforts can dovetail with model intercomparison projects and ongoing work in parameterization and model development. In addition to ongoing work paths towards building single radar based retrievals leveraging microphysical insight from polarimetric radars will be discussed.

  12. Unraveling the growth of vertically aligned multi-walled carbon nanotubes by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Ramirez, A.; Royo, C.; Latorre, N.; Mallada, R.; Tiggelaar, R. M.; Monzón, A.

    2014-12-01

    The interaction between the main operational variables during the growth of vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) by catalytic chemical vapor deposition is studied. In this contribution, we report the influence of the carbon source (i.e. acetylene, ethylene and propylene), the reaction/activation temperature, the rate of heating, the reaction time, the metal loading, and the metallic nanoparticle size and distribution on the growth and alignment of carbon nanotubes. Fe/Al thin films deposited onto silicon samples by electron-beam evaporation are used as catalyst. A phenomenological growth mechanism is proposed to explain the interaction between these multiple factors. Three different outcomes of the synthesis process are found: i) formation of forests of non-aligned, randomly oriented multi-walled carbon nanotubes, ii) growth of vertically aligned tubes with a thin and homogeneous carbonaceous layer on the top, and iii) formation of vertically aligned carbon nanotubes. This carbonaceous layer (ii) has not been reported before. The main requirements to promote vertically aligned carbon nanotube growth are determined.

  13. Heat exchanger

    DOEpatents

    Brackenbury, Phillip J. (Richland, WA)

    1986-01-01

    A heat exchanger comparising a shell attached at its open end to one side of a tube sheet and a detachable head connected to the other side of said tube sheet. The head is divided into a first and second chamber in fluid communication with a nozzle inlet and nozzle outlet, respectively, formed in said tube sheet. A tube bundle is mounted within said shell and is provided with inlets and outlets formed in said tube sheet in communication with said first and second chambers, respectively.

  14. Heat exchanger

    SciTech Connect

    Saperstein, Z.P.; Awe, R.C.; Costello, N.F.; Larrabee, S.R.

    1986-10-07

    A heat exchanger is described which consists of: spaced generally parallel header and tank constructions; each of the header and tank constructions having elongated, spaced, tube receiving holes in a header surface thereof; the holes in one header surface being aligned with and facing corresponding holes in the other header surface; and elongated open ended, flattened tubes extending between and into the header and tank constructions through aligned ones of the holes; the portions of each header surface between the holes including exteriorly convex domes defined by compound curves to thereby provide increased resistance to deformation as a result of force exerted by a pressurized fluid within the header and tank construction.

  15. Heat exchanger

    DOEpatents

    Brackenbury, P.J.

    1983-12-08

    A heat exchanger comparising a shell attached at its open end to one side of a tube sheet and a detachable head connected to the other side of said tube sheet. The head is divided into a first and second chamber in fluid communication with a nozzle inlet and nozzle outlet, respectively, formed in said tube sheet. A tube bundle is mounted within said shell and is provided with inlets and outlets formed in said tube sheet in communication with said first and second chambers, respectively.

  16. Modular heat exchanger

    DOEpatents

    Giardina, Angelo R. [Marple Township, Delaware County, PA

    1981-03-03

    A shell and tube heat exchanger having a plurality of individually removable tube bundle modules. A lattice of structural steel forming rectangular openings therein is placed at each end of a cylindrical shell. Longitudinal structural members are placed in the shell between corners of the rectangular openings situated on opposite ends of the shell. Intermediate support members interconnect the longitudinal supports so as to increase the longitudinal supports rigidity. Rectangular parallelpiped tube bundle moldules occupy the space defined by the longitudinal supports and end supports and each include a rectangular tube sheet situated on each end of a plurality of tubes extending therethrough, a plurality of rectangular tube supports located between the tube sheets, and a tube bundle module stiffening structure disposed about the bundle's periphery and being attached to the tube sheets and tube supports. The corners of each tube bundle module have longitudinal framework members which are mateable with and supported by the longitudinal support members. Intermediate support members constitute several lattice, each of which is situate d in a plane between the end support members. The intermediate support members constituting the several lattice extend horizontally and vertically between longitudinal supports of adjacent tube module voids. An alternative embodiment for intermediate support members constitute a series of structural plates situated at the corners of the module voids and having recesses therein for receiving the respective longitudinal support members adjacent thereto, protrusions separating the recesses, and a plurality of struts situated between protrusions of adjacent structural plates.

  17. Modular heat exchanger

    DOEpatents

    Giardina, A.R.

    1981-03-03

    A shell and tube heat exchanger is described having a plurality of individually removable tube bundle modules. A lattice of structural steel forming rectangular openings therein is placed at each end of a cylindrical shell. Longitudinal structural members are placed in the shell between corners of the rectangular openings situated on opposite ends of the shell. Intermediate support members interconnect the longitudinal supports so as to increase the longitudinal supports rigidity. Rectangular parallelepiped tube bundle modules occupy the space defined by the longitudinal supports and end supports and each include a rectangular tube sheet situated on each end of a plurality of tubes extending there through, a plurality of rectangular tube supports located between the tube sheets, and a tube bundle module stiffening structure disposed about the bundle's periphery and being attached to the tube sheets and tube supports. The corners of each tube bundle module have longitudinal framework members which are mateable with and supported by the longitudinal support members. Intermediate support members constitute several lattices, each of which is situated in a plane between the end support members. The intermediate support members constituting the several lattices extend horizontally and vertically between longitudinal supports of adjacent tube module voids. An alternative embodiment for intermediate support members constitute a series of structural plates situated at the corners of the module voids and having recesses therein for receiving the respective longitudinal support members adjacent thereto, protrusions separating the recesses, and a plurality of struts situated between protrusions of adjacent structural plates. 12 figs.

  18. Relation between geoidal undulation, deflection of the vertical and vertical gravity gradient revisited

    NASA Astrophysics Data System (ADS)

    Bouman, Johannes

    2012-04-01

    The vertical gradients of gravity anomaly and gravity disturbance can be related to horizontal first derivatives of deflection of the vertical or second derivatives of geoidal undulations. These are simplified relations of which different variations have found application in satellite altimetry with the implicit assumption that the neglected terms—using remove-restore—are sufficiently small. In this paper, the different simplified relations are rigorously connected and the neglected terms are made explicit. The main neglected terms are a curvilinear term that accounts for the difference between second derivatives in a Cartesian system and on a spherical surface, and a small circle term that stems from the difference between second derivatives on a great and small circle. The neglected terms were compared with the dynamic ocean topography (DOT) and the requirements on the GOCE gravity gradients. In addition, the signal root-mean-square (RMS) of the neglected terms and vertical gravity gradient were compared, and the effect of a remove-restore procedure was studied. These analyses show that both neglected terms have the same order of magnitude as the DOT gradient signal and may be above the GOCE requirements, and should be accounted for when combining altimetry derived and GOCE measured gradients. The signal RMS of both neglected terms is in general small when compared with the signal RMS of the vertical gravity gradient, but they may introduce gradient errors above the spherical approximation error. Remove-restore with gravity field models reduces the errors in the vertical gravity gradient, but it appears that errors above the spherical approximation error cannot be avoided at individual locations. When computing the vertical gradient of gravity anomaly from satellite altimeter data using deflections of the vertical, the small circle term is readily available and can be included. The direct computation of the vertical gradient of gravity disturbance from satellite altimeter data is more difficult than the computation of the vertical gradient of gravity anomaly because in the former case the curvilinear term is needed, which is not readily available.

  19. 47 CFR 73.160 - Vertical plane radiation characteristics, f(?).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Vertical plane radiation characteristics, f(θ). 73.160 Section 73.160 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.160 Vertical plane radiation characteristics, f(?). (a) The vertical plane...

  20. Multispectral imaging with vertical silicon Hyunsung Park & Kenneth B. Crozier

    E-print Network

    of PDMS-embedded vertical silicon nanowires is attached to a monochrome image sensor (Fig. 1a). The unitMultispectral imaging with vertical silicon nanowires Hyunsung Park & Kenneth B. Crozier School the demonstration of a compact multispectral imaging system that uses vertical silicon nanowires to realize a filter

  1. ORIGINAL ARTICLE Metabolic and Mechanical Energy Costs of Reducing Vertical

    E-print Network

    because of greater mechanical work performed at the hip, knee, and ankle joints. Thus, reducing vertical in joint work associated with increasing and decreasing vertical COM move- ment during gait. Design vertical and lateral COM displace- ments, joint torques, and work. In addition, we collected oxy- gen

  2. Marine vertical cable multiple attenuation beyond up/down separation 

    E-print Network

    Tran, Andre

    2001-01-01

    fixed vertical receiver arrays as for VSP. A small vessel carries only the source and is very flexible. The vertical cable receivers are in a quiet environment, which can explain the data quality. One main concern with vertical cable data is to remove...

  3. Vertical Velocity from LADCP Data A. M. Thurnherr

    E-print Network

    Thurnherr, Andreas

    Vertical Velocity from LADCP Data A. M. Thurnherr Division of Ocean and Climate Physics Lamont--Vertical velocity is important for ocean dynamics on a vast range of scales, from isotropic turbulence to the global, vertical- velocity measurements in the ocean are scarce. In an effort to remedy this situation, a new

  4. 49 CFR 179.14 - Coupler vertical restraint system.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Coupler vertical restraint system. 179.14 Section... General Design Requirements § 179.14 Coupler vertical restraint system. (a) Performance standard. Each... be equipped with couplers having this vertical restraint capability. (b) Test verification. Except...

  5. 49 CFR 179.14 - Coupler vertical restraint system.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Coupler vertical restraint system. 179.14 Section... General Design Requirements § 179.14 Coupler vertical restraint system. (a) Performance standard. Each... be equipped with couplers having this vertical restraint capability. (b) Test verification. Except...

  6. 49 CFR 179.14 - Coupler vertical restraint system.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Coupler vertical restraint system. 179.14 Section... General Design Requirements § 179.14 Coupler vertical restraint system. (a) Performance standard. Each... be equipped with couplers having this vertical restraint capability. (b) Test verification. Except...

  7. 49 CFR 179.14 - Coupler vertical restraint system.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Coupler vertical restraint system. 179.14 Section... TANK CARS General Design Requirements § 179.14 Coupler vertical restraint system. (a) Performance... not be equipped with couplers having this vertical restraint capability. (b) Test verification....

  8. 49 CFR 179.14 - Coupler vertical restraint system.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Coupler vertical restraint system. 179.14 Section... General Design Requirements § 179.14 Coupler vertical restraint system. (a) Performance standard. Each... be equipped with couplers having this vertical restraint capability. (b) Test verification. Except...

  9. Diel Vertical Migration Thresholds of Karenia brevis (Dinophyceae).

    EPA Science Inventory

    Light and nutrient availability change throughout dinoflagellate diel vertical migration (DVM) and/or with subpopulation location in the water column along the west Florida shelf. Typically, the vertical depth of the shelf is greater than the distance a subpopulation can vertical...

  10. Vertical heterostructure of two-dimensional MoS? and WSe? with vertically aligned layers.

    PubMed

    Yu, Jung Ho; Lee, Hye Ryoung; Hong, Seung Sae; Kong, Desheng; Lee, Hyun-Wook; Wang, Haotian; Xiong, Feng; Wang, Shuang; Cui, Yi

    2015-02-11

    Two-dimensional (2D) layered materials consist of covalently bonded 2D atomic layers stacked by van der Waals interactions. Such anisotropic bonding nature gives rise to the orientation-dependent functionalities of the 2D layered materials. Different from most studies of 2D materials with their atomic layers parallel to substrate, we have recently developed layer vertically aligned 2D material nanofilms. Built on these developments, here, we demonstrate the synthesis of vertical heterostructure of n-type MoS2 and p-type WSe2 with vertically aligned atomic layers. Thin film of MoS2/WSe2 vertical structure was successfully synthesized without significant alloy formation. The heterostructure synthesis is scalable to a large area over 1 cm(2). We demonstrated the pn junction diode behavior of the heterostructure device. This novel device geometry opens up exciting opportunities for a variety of electronic and optoelectronic devices, complementary to the recent interesting vertical heterostructures with horizontal atomic layers. PMID:25590995

  11. Solar-heated swimming school--Wilmington, Delaware

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Report describes operation, installation, and performance of solar-energy system which provides alternative to natural gas pool heating. System is comprised of 2,500 square feet of liquid flat-plate collectors connected to 3,600 galloon; gallongalloon storage tank, with microcomputer-based controls. Extension of building incorporates vertical-wall, passive collection system which provides quarter of heated fresh air for office.

  12. Experimental Study of Combined Forced and Free Laminar Convection in a Vertical Tube

    NASA Technical Reports Server (NTRS)

    Hallman, Theodore M.

    1961-01-01

    An apparatus was built to verify an analysis of combined forced and free convection in a vertical tube with uniform wall heat flux and to determine the limits of the analysis. The test section was electrically heated by resistance heating of the tube wall and was instrumented with thermocouples in such a way that detailed thermal entrance heat-transfer coefficients could be obtained for both upflow and downflow and any asymmetry in wall temperature could be detected. The experiments showed that fully developed heat-transfer results, predicted by a previous analysis, were confirmed over the range of Rayleigh numbers investigated. The concept of "locally fully developed" heat transfer was established. This concept involves the assumption that the fully developed heat-transfer analysis can be applied locally even though the Rayleigh number is varying along the tube because of physical-property variations with temperature. Thermal entrance region data were obtained for pure forced convection and for combined forced and free convection. The analysis of laminar pure forced convection in the thermal entrance region conducted by Siegel, Sparrow, and Hallman was experimentally confirmed. A transition to an eddy motion, indicated by a fluctuation in wall temperature was found in many of the upflow runs. A stability correlation was found. The fully developed Nusselt numbers in downflow were below those for pure forced convection but fell about 10 percent above the analytical curve. Quite large circumferential variations in wall temperature were observed in downflow as compaired with those encountered in upflow, and the fully developed Nussalt numbers reported are based on average wall temperatures determined by averaging the readings of two diametrically opposite wall thermocouples at each axial position. With larger heating rates in downflow the wall temperature distributions strongly suggested a cell flow near the bottom. At still larger heating rates the wall temperatures varied in a periodic way.

  13. Influence of the wetting state of a heated surface on heat transfer and pressure loss in an evaporator tube

    SciTech Connect

    Koehler, W; Hein, D

    1986-09-01

    The influence of the wetting state of a heated surface on heat transfer and pressure loss in an evaporator tube was investigated for a parameter range occurring in fossil-fired steam generators. Included in the analysis are quantities which determine the wetting state in steady and transient flow. The experimental work consists of the following: Occurrence of critical heat flux (CHF) and post-CHF heat transfer in a vertical upflow evaporator tube; influence of pressure and enthalpy transients on heat transfer in the unwetted region; influence of pipe orientation on heat transfer; and two phase flow pressure loss in wetted and unwetted region. Based on these experiments a method of predicting CHF for a vertical upflow evaporator tube was developed. The heat transfer in the unwetted region was newly formulated taking into account thermal nonequilibrium between the water and steam phases. Wall temperature excursions during pressure and enthalpy transients are interpreted with the help of the boiling curve and the Leidenfrost phenomenon. A method is developed by means of which it is possible to determine the influence of the pipe orientation on the location of the boiling crisis as well as on the heat transfer in the unwetted region. The influence of the wetting state of the heated surface on the two phase flow pressure loss is interpreted as ''Wall effect'' and is calculated using a simplified computer model. 68 refs., 83 figs.

  14. Heat Rash or Prickly Heat (Miliaria Rubra)

    MedlinePLUS

    newsletter | contact Share | Heat Rash or Prickly Heat (Miliaria Rubra) A parent's guide to condition and treatment information A A A This child with miliaria ... itchy bumps in area of redness. Overview Heat rash (miliaria rubra), also known as prickly heat, is ...

  15. Latent Heat in Soil Heat Flux Measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

  16. Segmented heat exchanger

    DOEpatents

    Baldwin, Darryl Dean (Lafayette, IN); Willi, Martin Leo (Dunlap, IL); Fiveland, Scott Byron (Metamara, IL); Timmons, Kristine Ann (Chillicothe, IL)

    2010-12-14

    A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

  17. Heat recovery method

    SciTech Connect

    Richarts, F.

    1985-04-16

    Heat is recovered by combining a heat transfer system including heat exchangers interconnected in a circulatory system, with a heat pump system. The heat pump system is preferably operated in accordance with the Lorenz-Principle. It is not necessary to divide the heat carrier circuit of the heat pump into two or three separate circulatory circuits. The heat carrier circuit of the heat pump can thus continue to operate unchanged even if the heat pump is switched off. For this purpose the warm heat carrier coming from a discharge fluid cooler, is heated further in a condenser of the heat pump and the cold heat carrier coming from a preheater or cooler group, is cooled further in an evaporator of the heat pump.

  18. Fluidized bed heat exchanger with water cooled air distributor and dust hopper

    SciTech Connect

    Jukkola, Walfred W.; Leon, Albert M.; Van Dyk, Jr., Garritt C.; McCoy, Daniel E.; Fisher, Barry L.; Saiers, Timothy L.; Karstetter, Marlin E.

    1981-11-24

    A fluidized bed heat exchanger is provided in which air is passed through a bed of particulate material containing fuel. A steam-water natural circulation system is provided for heat exchange and the housing of the heat exchanger has a water-wall type construction. Vertical in-bed heat exchange tubes are provided and the air distributor is water-cooled. A water-cooled dust hopper is provided in the housing to collect particulates from the combustion gases and separate the combustion zone from a volume within said housing in which convection heat exchange tubes are provided to extract heat from the exiting combustion gases.

  19. Transient natural convection in heated inclined tubes

    SciTech Connect

    McEligot, D.M. . Oceanic Div.); Denbow, D.A. ); Murphy, H.D. )

    1990-05-01

    To simulate natural convection flow patterns in directionally drilled wellbores, experiments and analyses were conducted for a circular tube with length-to-diameter (L/D) ratio of 36 at angles of 0{degree}, 20{degree}, and 35{degree} from the vertical. The tube was heated at the bottom and cooled at the top, and the insulation was adjusted so that approximately one- to two-thirds of the power dissipated was transferred through the tube wall to the surroundings. An aqueous solution of polyvinyl alcohol was employed as the working fluid in order to obtain low Rayleigh numbers corresponding to conditions in geothermal wellbores. Results were primarily qualitative but were useful in providing insight into the phenomena occurring. Steady-state temperature distributions were measured for the three orientations and for several heating rates to demonstrate the effects of tube angle and Rayleigh number. transient measurements of the temperature distribution were obtained during cooling from a higher temperature without a heat source to calibrate the heat losses. With the electrical heat source, temporal data were taken during heating to examine the approach to steady state. Quasi-steady flow conditions were approached rapidly, but the overall time constant of the apparatus was of the order of one-third of a day. Predictions with the three-dimensional TEMPEST code were first tested by comparison with simple conduction analyses. Comparison with actual data showed good agreement of the predicted temperature levels for the maximum inclination, 35{degree}, and slightly poorer agreement for the other limit, a vertical tube. Trends of temperature level and Nusselt number with heating rate or Rayleigh number were reasonable, but the predicted variation of the end Nusselt number versus inclination was in the opposite direction from the experiment. 75 refs., 20 figs., 8 tabs.

  20. Vertical deformation at western part of Sumatra

    NASA Astrophysics Data System (ADS)

    Febriyani, Caroline; Prijatna, Kosasih; Meilano, Irwan

    2015-04-01

    This research tries to make advancement in GPS signal processing to estimate the interseismic vertical deformation field at western part of Sumatra Island. The data derived by Continuous Global Positioning System (CGPS) from Badan Informasi Geospasial (BIG) between 2010 and 2012. GPS Analyze at Massachusetts Institute of Technology (GAMIT) software and Global Kalman Filter (GLOBK) software are used to process the GPS signal to estimate the vertical velocities of the CGPS station. In order to minimize noise due to atmospheric delay, Vienna Mapping Function 1 (VMF1) is used as atmospheric parameter model and include daily IONEX file provided by the Center for Orbit Determination in Europe (CODE) as well. It improves GAMIT daily position accuracy up to 0.8 mm. In a second step of processing, the GLOBK is used in order to estimate site positions and velocities in the ITRF08 reference frame. The result shows that the uncertainties of estimated displacement velocity at all CGPS stations are smaller than 1.5 mm/yr. The subsided deformation patterns are seen at the northern and southern part of west Sumatra. The vertical deformation at northern part of west Sumatra indicates postseismic phase associated with the 2010 and 2012 Northern Sumatra earthquakes and also the long-term postseismic associated with the 2004 and 2005 Northern Sumatra earthquakes. The uplifted deformation patterns are seen from Bukit Tinggi to Seblat which indicate a long-term interseismic phase after the 2007 Bengkulu earthquake and 2010 Mentawai earthquake. GANO station shows a subsidence at rate 12.25 mm/yr, indicating the overriding Indo-Australia Plate which is dragged down by the subducting Southeast Asian Plate.

  1. Centropages behaviour: Swimming and vertical migration

    NASA Astrophysics Data System (ADS)

    Alcaraz, Miguel; Saiz, Enric; Calbet, Albert

    2007-02-01

    The evolutionary success of any species living in a variable environment depends on its capacity to enhance the probability of finding food and mates, and escaping predators. In the case of copepods of the genus Centropages, as in all planktonic copepods, their swimming behaviour is closely tied to these vital aspects, and shows a high degree of plasticity and adaptive capacity. Swimming mechanisms of Centropages change radically during development, mainly in the transition between naupliar stages to the 1st copepodite; nauplii do not produce feeding currents, whereas copepodites do. Adults and late developmental stages of C. typicus, C. hamatus and C. velificatus spend most of the time in slow swimming and resting breaks, with occasional and brief fast swimming (escape reactions) and grooming events. Slow swimming is closely related to the creation of feeding currents, and results from the beating of the cephalic appendages in a “fling and clap” manner. The proportion of time allocated to the different swimming activities depends on sensory cues like type and concentration of food, presence of potential mates, light intensity, hydrodynamic flow, etc. The responses of Centropages to changes in flow velocity fluctuations (small-scale turbulence) are similar to the escape responses (fast swimming) triggered by the presence of potential predators. Centropages generally have standard nocturnal vertical migration patterns involving considerable vertical displacements. This behaviour is closely related to the narrow spectral sensitivity and the low intensity threshold of the genus, and has important consequences for the active vertical transport of matter and energy. The variety of responses of Centropages to environmental changes, and in general all the aspects related to its swimming behaviour seem to be controlled by the trade-off between energetic gains (food intake), losses (swimming energy expenditure), and predation risk. Behavioural plasticity and adaptation appear to be the most relevant characteristics for the success of the genus in a wide range of marine environments.

  2. Vertical deformation at western part of Sumatra

    SciTech Connect

    Febriyani, Caroline Prijatna, Kosasih Meilano, Irwan

    2015-04-24

    This research tries to make advancement in GPS signal processing to estimate the interseismic vertical deformation field at western part of Sumatra Island. The data derived by Continuous Global Positioning System (CGPS) from Badan Informasi Geospasial (BIG) between 2010 and 2012. GPS Analyze at Massachusetts Institute of Technology (GAMIT) software and Global Kalman Filter (GLOBK) software are used to process the GPS signal to estimate the vertical velocities of the CGPS station. In order to minimize noise due to atmospheric delay, Vienna Mapping Function 1 (VMF1) is used as atmospheric parameter model and include daily IONEX file provided by the Center for Orbit Determination in Europe (CODE) as well. It improves GAMIT daily position accuracy up to 0.8?mm. In a second step of processing, the GLOBK is used in order to estimate site positions and velocities in the ITRF08 reference frame. The result shows that the uncertainties of estimated displacement velocity at all CGPS stations are smaller than 1.5?mm/yr. The subsided deformation patterns are seen at the northern and southern part of west Sumatra. The vertical deformation at northern part of west Sumatra indicates postseismic phase associated with the 2010 and 2012 Northern Sumatra earthquakes and also the long-term postseismic associated with the 2004 and 2005 Northern Sumatra earthquakes. The uplifted deformation patterns are seen from Bukit Tinggi to Seblat which indicate a long-term interseismic phase after the 2007 Bengkulu earthquake and 2010 Mentawai earthquake. GANO station shows a subsidence at rate 12.25?mm/yr, indicating the overriding Indo-Australia Plate which is dragged down by the subducting Southeast Asian Plate.

  3. Apparatus For Linewidth Reduction in Distributed Feedback or Distributed Bragg Reflector Semiconductor Lasers Using Vertical Emission

    NASA Technical Reports Server (NTRS)

    Cook, Anthony L. (Inventor); Hendricks, Herbert D. (Inventor)

    2000-01-01

    The linewidth of a distributed feedback semiconductor laser or a distributed Bragg reflector laser having one or more second order gratings is reduced by using an external cavity to couple the vertical emission back into the laser. This method and device prevent disturbance of the main laser beam, provide unobstructed access to laser emission for the formation of the external cavity, and do not require a very narrow heat sink. Any distributed Bragg reflector semiconductor laser or distributed feedback semiconductor laser that can produce a vertical emission through the epitaxial material and through a window in the top metallization can be used. The external cavity can be formed with an optical fiber or with a lens and a mirror or grating.

  4. Design and testing of CRBRP insulated horizontal and vertical pipe clamps

    SciTech Connect

    Pollono, L.P.; Mello, R.M.

    1980-01-01

    The Clinch River Breeder Reactor Plant (CRBRP) Primary Heat Transport system piping may be characterized as large-diameter, thin-wall piping which transports liquid sodium at high temperatures. The piping is arranged in accord with the elevated loop concept, consisting of large horizontal inplane, expansion loops and long, vertical runs of piping. These characteristics and the postulated thermal transient and seismic loads, which are imposed on the piping, dictate pipe clamp designs that are substantially different from standard off the shelf pipe clamp designs. The design features of the CRBRP horizontal and vertical pipe clamps for the large sodium piping, the various test programs used to verify the clamp designs, and the results of this testing are presented.

  5. Vertical thinking in blue light emitting diodes: GaN-on-graphene technology

    NASA Astrophysics Data System (ADS)

    Bayram, C.; Kim, J.; Cheng, C.-W.; Ott, J.; Reuter, K. B.; Bedell, S. W.; Sadana, D. K.; Park, H.; Dimitrakopoulos, C.

    2014-03-01

    In this work, we show that a 2D cleave layer (such as epitaxial graphene on SiC) can be used for precise release of GaNbased light emitting diodes (LEDs) from the LED-substrate interface. We demonstrate the thinnest GaN-based blue LED and report on the initial electrical and optical characteristics. Our LED device employs vertical architecture: promising excellent current spreading, improved heat dissipation, and high light extraction with respect to the lateral one. Compared to conventional LED layer release techniques used for forming vertical LEDs (such as laser-liftoff and chemical lift-off techniques), our process distinguishes itself with being wafer-scalable (large area devices are possible) and substrate reuse opportunity.

  6. Characterization of fracture permeability with high-resolution vertical flow measurements during borehole pumping.

    USGS Publications Warehouse

    Paillet, F.L.; Hess, A.E.; Cheng, C.H.; Hardin, E.

    1987-01-01

    The distribution of fracture permeability in granitic rocks was investigated by measuring the distribution of vertical flow in boreholes during periods of steady pumping. Pumping tests were conducted at two sites chosen to provide examples of moderately fractured rocks near Mirror Lake, New Hampshire and intensely fractured rocks near Oracle, Arizona. A sensitive heat-pulse flowmeter was used for accurate measurements of vertical flow as low as 0.2 liter per minute. Results indicate zones of fracture permeability in crystalline rocks are composed of irregular conduits that cannot be approximated by planar fractures of uniform aperture, and that the orientation of permeability zones may be unrelated to the orientation of individual fractures within those zones.-Authors

  7. Long-Term Mean Vertical Motion over the Tropical Pacific: Wind-Profiling Doppler Radar Measurements.

    PubMed

    Gage, K S; McAfee, J R; Carter, D A; Ecklund, W L; Riddle, A C; Reid, G C; Balsley, B B

    1991-12-20

    Measurement from Christmas Island (2 degrees N, 157 degrees W) of long-term mean vertical motions in the tropical atmosphere using very-high-frequency wind-profiling Doppler radar show that there is a transition from downward motion in the free troposphere to upward motion in the upper troposphere and lower stratosphere. The observations in the free troposphere are consistent with a balance between adiabatic and diabatic heating and cooling rates in a clear atmosphere. Comparison of the results at Christmas Island during El Niño and non-El Niño conditions with earlier results obtained for stratiform rain conditions over Pohnpei, Federated States of Micronesia, show that cirrus clouds in the vicinity of the tropopause likely play an important role in determining the sense and magnitude of vertical motions in this region. These results have implications for the exchange of mass between the troposphere and stratosphere over the tropics. PMID:17829241

  8. Bifurcation and stability of low-order steady flows in horizontally and vertically forced convection

    NASA Technical Reports Server (NTRS)

    Yost, D. A.; Shirer, H. N.

    1982-01-01

    A nonlinear spectral model of two-dimensional, shallow Boussinesq convection which responds to heating in both the horizontal and vertical directions is examined. The governing partial differential system is converted to an infinite set of ordinary differential equations and truncated to a small set to permit detailed study of the number and types of transitions from one flow configuration to another. The Hadley number and the Rayleigh number are defined as the horizontal and vertical thermal forcing mechanisms, respectively, for inclusion in the nonlinear spectral model, which is composed of three equations. The model is then used to describe steady states, linearly stable solutions, and balancing factors in unstable stratification. The number and the distribution of the steady states are found to be qualitatively independent of the aspect ratio and the Prandtl number.

  9. Heat Budget estimation of the Eastern Arabian Sea using Simple Ocean Data Assimilation Techniques

    NASA Astrophysics Data System (ADS)

    Fernandez, D. R.; Shenoi, S. S.; Shankar, D.

    2004-12-01

    Estimation of the monthly climatological heat budget of the Eastern Arabian Sea (6°N to 24°N and 68°E to 78°E ) is carried out for the top 50 m using oceanographic data from Simple Ocean Data Assimilation (SODA) model output and atmospheric surface heating fluxes over the air sea interface using Southampton Oceanographic Centre Climatology (SOC) for the periods 1990 ? 2001. We address the various roles played by the net surface heat flux and the local and remote ocean dynamics of the near surface heat budget in the eastern Arabian sea. A rough balance between the rate of change of heat and the fluxes of heat across the regional boundaries owing to advective and non advective processes is observed. During the summer monsoon oceanic processes play a major role in removing heat from the eastern Arabian Sea region of which horizontal advection is a major contributor. During the (NE) winter monsoon excess heat is downwelled by vertical velocity components (SODA) thus cooling the control volume. The accuracy of the vertical components of velocities is tested in balancing the heat budget. At 100 m depth a better closure is attained when vertical velocities components derived from mass balance were used in the heat equation. From the analysis of these datasets, this paper shows the ability of these datasets for estimating the heat budget of the eastern Arabian Sea.

  10. Vertical Isolation for Photodiodes in CMOS Imagers

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata

    2008-01-01

    In a proposed improvement in complementary metal oxide/semi conduct - or (CMOS) image detectors, two additional implants in each pixel would effect vertical isolation between the metal oxide/semiconductor field-effect transistors (MOSFETs) and the photodiode of the pixel. This improvement is expected to enable separate optimization of the designs of the photodiode and the MOSFETs so as to optimize their performances independently of each other. The purpose to be served by enabling this separate optimization is to eliminate or vastly reduce diffusion cross-talk, thereby increasing sensitivity, effective spatial resolution, and color fidelity while reducing noise.

  11. Flow effects in a vertical CVD reactor

    NASA Technical Reports Server (NTRS)

    Young, G. W.; Hariharan, S. I.; Carnahan, R.

    1992-01-01

    A model is presented to simulate the non-Boussinesq flow in a vertical, two-dimensional, chemical vapor deposition reactor under atmospheric pressure. Temperature-dependent conductivity, mass diffusivity, viscosity models, and reactive species mass transfer to the substrate are incorporated. In the limits of small Mach number and small aspect ratio, asymptotic expressions for the flow, temperature, and species fields are developed. Soret diffusion effects are also investigated. Analytical solutions predict an inverse relationship between temperature field and concentration field due to Soret effects. This finding is consistent with numerical simulations, assisting in the understanding of the complex interactions amongst the flow, thermal, and species fields in a chemically reacting system.

  12. Numerical modeling of vertical cavity semiconductor lasers

    SciTech Connect

    Chow, W.W.; Hadley, G.R.

    1996-08-01

    A vertical cavity surface emitting laser (VCSEL) is a diode laser whose optical cavity is formed by growing or depositing DBR mirror stacks that sandwich an active gain region. The resulting short cavity supports lasing into a single longitudinal mode normal to the wafer, making these devices ideal for a multitude of applications, ranging from high-speed communication to high-power sources (from 2D arrays). This report describes the development of a numerical VCSEL model, whose goal is to both further their understanding of these complex devices and provide a tool for accurate design and data analysis.

  13. Long wavelength vertical cavity surface emitting laser

    DOEpatents

    Choquette, Kent D.; Klem, John F.

    2005-08-16

    Selectively oxidized vertical cavity lasers emitting near 1300 nm using InGaAsN quantum wells are reported for the first time which operate continuous wave below, at and above room temperature. The lasers employ two n-type Al.sub.0.94 Ga.sub.0.06 As/GaAs distributed Bragg reflectors each with a selectively oxidized current aperture adjacent to the active region, and the top output mirror contains a tunnel junction to inject holes into the active region. Continuous wave single mode lasing is observed up to 55.degree. C.

  14. Vertical engine for walk behind lawn mower

    SciTech Connect

    Isaka, Y.; Oguri, K.

    1988-03-01

    This patent describes a lawn mower or other similar walk behind type of implement that is designed to be operated in a normally erect position and which is tilted to the side for servicing. An engine is provided for the lawn mower having an output shaft rotatable about a vertically extending axis. The engine includes a lubricating system incorporating a crankcase in which the engine output shaft rotates and a crankcase ventilating system. The crankcase ventilating system is designed so as to prevent lubricant from flowing into the induction system when the engine is tilted on its side.

  15. Propulsion systems for vertical flight aircraft

    SciTech Connect

    Brooks, A.

    1990-01-01

    The present evaluation of VTOL airframe/powerplant integration configurations combining high forward flight speed with safe and efficient vertical flight identifies six configurations that can be matched with one of three powerplant types: turboshafts, convertible-driveshaft lift fans, and gas-drive lift fans. The airframes configurations are (1) tilt-rotor, (2) folded tilt-rotor, (3) tilt-wing, (4) rotor wing/disk wing, (5) lift fan, and (6) variable-diameter rotor. Attention is given to the lift-fan VTOL configuration. The evaluation of these configurations has been conducted by both a joint NASA/DARPA program and the NASA High Speed Rotorcraft program. 7 refs.

  16. Wicking and flooding of liquids on vertical porous sheets

    NASA Astrophysics Data System (ADS)

    Kim, Seong Jin; Choi, Jin Woo; Moon, Myoung-Woon; Lee, Kwang-Ryeol; Chang, Young Soo; Lee, Dae-Young; Kim, Ho-Young

    2015-03-01

    When one brings a wet paintbrush into contact with a vertical watercolor paper, the paint may wick into the porous sheet completely or run down to ruin the art. We study a simple model of this spreading dynamics of liquids on hydrophilic porous sheets under the effects of gravity, using a capillary as a liquid source and thin fabrics of non-woven polyethylene terephthalate. Upon finding the maximum flow rate, Qw, that can be absorbed into the fabric, we show that the model can be used to obtain an estimate of the in-plane permeability of fabrics in a simpler manner than the conventional schemes. The shape of a wetting area that grows when the flow rate exceeds Qw to lead to rivulet formation is also theoretically given. The nose shape of the wetting front is shown to be time-invariant, while its profile depends on the properties of the liquid and the fabric. This study can be applied to understand and improve the liquid absorption behavior of hygiene items, heating, ventilation, and air-conditioning equipments, and fuel cell membranes in addition to elucidating the mundane painting activity.

  17. Conjugate natural convection flow over a vertical surface with radiation

    NASA Astrophysics Data System (ADS)

    Siddiqa, Sadia; Hossain, Md. Anwar; Gorla, Rama Subba Reddy

    2015-07-01

    Numerical study of conjugate natural convection flow over a finite vertical surface with radiation is reported in this article. Rosseland diffusion approximation is used to express the radiative heat flux term. The governing boundary-layer equations are made dimensionless by means of a suitable form of non-similarity transformation. These equations are obtained in three regimes: (1) upstream (when ? ? 0 ), (2) downstream (when ? ? ? ) and (3) entire regime and are solved numerically. The solutions in the upstream and downstream regimes are obtained via shooting method whereas two-point implicit finite difference method is used to get the solutions for the entire regime. It is seen that asymptotic solutions give accurate results when compared with the numerical solution of the entire regime. The results indicate that the flow field and the temperature distributions are greatly influenced by thermal radiation parameter , R_d , surface temperature parameter, ? _w and Prandtl number Pr. It is established from the analysis that recirculation occurs in the flow specifically for R_d=1.5 .

  18. Effect of dry large-scale vertical motions on initial MJO convective onset

    NASA Astrophysics Data System (ADS)

    Powell, Scott W.; Houze, Robert A.

    2015-05-01

    Anomalies of eastward propagating large-scale vertical motion with ~30 day variability at Addu City, Maldives, move into the Indian Ocean from the west and are implicated in Madden-Julian Oscillation (MJO) convective onset. Using ground-based radar and large-scale forcing data derived from a sounding array, typical profiles of environmental heating, moisture sink, vertical motion, moisture advection, and Eulerian moisture tendency are computed for periods prior to those during which deep convection is prevalent and those during which moderately deep cumulonimbi do not form into deep clouds. Convection with 3-7 km tops is ubiquitous but present in greater numbers when tropospheric moistening occurs below 600 hPa. Vertical eddy convergence of moisture in shallow to moderately deep clouds is likely responsible for moistening during a 3-7 day long transition period between suppressed and active MJO conditions, although moistening via evaporation of cloud condensate detrained into the environment of such clouds may also be important. Reduction in large-scale subsidence, associated with a vertical velocity structure that travels with a dry eastward propagating zonal wavenumbers 1-1.5 structure in zonal wind, drives a steepening of the lapse rate below 700 hPa, which supports an increase in moderately deep moist convection. As the moderately deep cumulonimbi moisten the lower troposphere, more deep convection develops, which itself moistens the upper troposphere. Reduction in large-scale subsidence associated with the eastward propagating feature reinforces the upper tropospheric moistening, helping to then rapidly make the environment conducive to formation of large stratiform precipitation regions, whose heating is critical for MJO maintenance.

  19. Visualization on flow patterns during condensation of R410A in a vertical rectangular channel

    NASA Astrophysics Data System (ADS)

    Xu, Wenyun; Jia, Li

    2014-06-01

    The visualization experiments on HFC R410A condensation in a vertical rectangular channel (14.34mm hydraulic diameter, 160mm length) were investigated. The flow patterns and heat transfer coefficients of condensation in the inlet region were presented in this paper. Better heat transfer performance can be obtained in the inlet region, and flow regime transition in other regions of the channel was also observed. Condensation experiments were carried out at different mass fluxes ( from 1.6 kg/h to 5.2 kg/h) and at saturation temperature 28°C. It was found that the flow patterns were mainly dominated by gravity at low mass fluxes. The effects of interfacial shear stress on condensate fluctuation are significant for the film condensation at higher mass flux in vertical flow, and consequently, the condensation heat transfer coefficient increases with the mass flux in the experimental conditions. The drop formation and growth process of condensation were also observed at considerably low refrigerant vapor flow rate.

  20. Numerical investigation of buoyancy effects in vertical ITER-TF-CICC at normal operating conditions

    NASA Astrophysics Data System (ADS)

    Pasler, Volker

    2006-07-01

    Increasing the size of an experimental fusion device is an important factor towards achieving plasma ignition conditions; this could however generate new problems such as the build up of buoyancy flow in long, vertical parts of cable-in-conduit conductors (CICC). In this article, the impact of buoyancy effects to the conductor cooling behaviour is simulated for a conductor part at an inner leg of an ITER TF coil. The MAGS code system had to be extended by a two-channel thermohydraulic model based on the model of the MITHRANDIR code. Additionally, gravity was included. Using realistic nuclear heating assumptions, buoyancy flow shows no significant impact to the coil operation temperature margins, even if the thermal coupling is restricted to convective heat transfer between hole and bundle. The time constant of the buoyancy flow build up is of the same order of magnitude of a typical ITER cycle. An example with artificially enhanced nuclear heating by a factor of four is also included for the illustration of consequences of buoyancy effects to CICC vertical flow.