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1

Assessing the RELAPS-3D Heat Conduction Enclosure Model  

SciTech Connect

Three heat conduction problems that have exact solutions are modeled with RELAP5-3D using the conduction enclosure model. These comparisons are designed to be used in the RELAP5-3D development assessment scheduled to be completed in 2009. It is shown that with proper input choices and adequate model detail the exact solutions can be matched. In addition, this analysis identified an error and the required correction in the cylindrical and spherical heat conductor models in RELAP5-3D which will be corrected in a future version of RELAP5-3D.

McCann, Larry D.

2008-09-30

2

THERM3D -- A boundary element computer program for transient heat conduction problems  

SciTech Connect

The computer code THERM3D implements the direct boundary element method (BEM) to solve transient heat conduction problems in arbitrary three-dimensional domains. This particular implementation of the BEM avoids performing time-consuming domain integrations by approximating a ``generalized forcing function`` in the interior of the domain with the use of radial basis functions. An approximate particular solution is then constructed, and the original problem is transformed into a sequence of Laplace problems. The code is capable of handling a large variety of boundary conditions including isothermal, specified flux, convection, radiation, and combined convection and radiation conditions. The computer code is benchmarked by comparisons with analytic and finite element results.

Ingber, M.S. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Mechanical Engineering

1994-02-01

3

Reduction of Thermal Conductivity by Nanoscale 3D Phononic Crystal  

PubMed Central

We studied how the period length and the mass ratio affect the thermal conductivity of isotopic nanoscale three-dimensional (3D) phononic crystal of Si. Simulation results by equilibrium molecular dynamics show isotopic nanoscale 3D phononic crystals can significantly reduce the thermal conductivity of bulk Si at high temperature (1000?K), which leads to a larger ZT than unity. The thermal conductivity decreases as the period length and mass ratio increases. The phonon dispersion curves show an obvious decrease of group velocities in 3D phononic crystals. The phonon's localization and band gap is also clearly observed in spectra of normalized inverse participation ratio in nanoscale 3D phononic crystal.

Yang, Lina; Yang, Nuo; Li, Baowen

2013-01-01

4

Conductance through step junctions in 3D topological insulators  

NASA Astrophysics Data System (ADS)

An effective continuous model for low-energy surface states of a 3D topological insulator was presented by Zhang et al., Nat. Phys. 5, 438 (2009). We present a general solution for this 3D model in a surface different from the standard (111)-surface. In our solution, surface states consist of a single Dirac cone with a Fermi velocity different from the one in (111)-surfaces, and the energy has an elliptical dispersion in k-space. We then study transport through a step junction composed of a (111)-surface -- side-surface -- (111)-surface and predict that the conductance saturates at 2/3 G0, independent of eccentricity and velocity mismatch at the interfaces. We compare our model with a junction in a plane with only (111)-states where conductance saturation does depend on velocity mismatch. We also analyze the Fano factor and highlight experimentally relevant situations where our predictions could be tested.

Alos-Palop, Mireia; Tiwari, Rakesh P.; Blaauboer, Miriam

2012-02-01

5

Effective Thermal Conductivity of Composite Materials with 3-D Microstructures and Interfacial Thermal Resistance  

Microsoft Academic Search

This article presents a numerical scheme, based on an isoparametric second-order finite-element discretization of the unit cell heat conduction problem, to calculate the effective thermal conductivity of composite materials with general 3-D microstructures and interfacial thermal resistance. Representative numerical results for the effective conductivity of ordered arrays of spheres, prolate ellipsoids of revolution, and finite-length circular cylinders are presented and,

Carlos F. Matt; Manuel E. Cruz

2008-01-01

6

Mapping a 3-D conductivity anomaly using a vertical electric source: Field results  

Microsoft Academic Search

A method for monitoring an enhanced oil recovery (EOR) process is the mapping of electrical conductivity changes due to injection of steam or other fluids. Since the conductivity change will be three-dimensional (3-D) in character, it is necessary to develop techniques to map 3-D conductivity distributions. At the Richmond test site, near Berkeley California, we conducted a field experiment to

L. C. Bartel; G. A. Newman

1991-01-01

7

Heat conduction in conducting polyaniline nanofibers  

NASA Astrophysics Data System (ADS)

Thermal conductivity and specific heat of conducting polyaniline nanofibers are measured to identify the nature of heat carrying modes combined with their inhomogeneous structure. The low temperature thermal conductivity results reveal crystalline nature while the high temperature data confirm the amorphous nature of the material suggesting heterogeneous model for conducting polyaniline. Extended acoustic phonons dominate the low temperature (<100 K) heat conduction, while localized optical phonons hopping, assisted by the extended acoustic modes, account for the high temperature (>100 K) heat conduction.

Nath, Chandrani; Kumar, A.; Syu, K.-Z.; Kuo, Y.-K.

2013-09-01

8

3D heat and air transport model for predicting the thermal resistances of insulated wall assemblies  

Microsoft Academic Search

A wall energy rating (WER) system has been proposed to account for simultaneous thermal conduction and air leakage heat losses through a full-scale insulated wall system. Determining WER requires performing two standard tests on a full-scale wall specimen: a thermal resistance test and an air leakage test. A 3D model representation of the wall specimen is developed to combine the

Hamed H. Saber; Wahid Maref; Hakim Elmahdy; Michael C. Swinton; Rock Glazer

2012-01-01

9

3D heat and air transport model for predicting the thermal resistances of insulated wall assemblies  

Microsoft Academic Search

A wall energy rating (WER) system has been proposed to account for simultaneous thermal conduction and air leakage heat losses through a full-scale insulated wall system. Determining WER requires performing two standard tests on a full-scale wall specimen: a thermal resistance test and an air leakage test. A 3D model representation of the wall specimen is developed to combine the

Hamed H. Saber; Wahid Maref; Hakim Elmahdy; Michael C. Swinton; Rock Glazer

2011-01-01

10

A quasi-3D model to predict temperature distribution in SSC magnets due to 3D heat loads  

SciTech Connect

Hadronic and electromagnetic cascades in the vicinity of the interaction regions deposit energy into the final focusing superconducting magnets as a heat load that varies radially, azimuthally, and axially. The helium used to cool the magnets convects heat axially as it flows, thus, the temperature distribution at any point in the magnet depends on the previous history of the helium. A detailed map of the temperature distribution of the superconducting coils is required to determine the cooling is sufficient to prevent the magnet from quenching. A three-dimensional model is required to analyze the magnet temperature distribution due to the 3D heat load and the axial helium flow A 3D finite element thermal model of a 15 m magnet is not practical due to the large amount of CPU time that would be required. Therefore, a quasi-3D model has been developed that divides the magaet into a large number of segments axially, then calculates the temperature distribution for each segment using a 2D finite element model with boundary conditions derived from the previous segment by conservation of energy.

Archer, B.; Schermer, R.; Snitchler, G. (Superconducting Super Collider Lab., Dallas, TX (United States)); Kohli, H. (Texas Univ., Austin, TX (United States). Dept. of Engineering Mechanics)

1993-04-01

11

Conduction heat transfer solutions  

SciTech Connect

This text is a collection of solutions to a variety of heat conduction problems found in numerous publications, such as textbooks, handbooks, journals, reports, etc. Its purpose is to assemble these solutions into one source that can facilitate the search for a particular problem solution. Generally, it is intended to be a handbook on the subject of heat conduction. This material is useful for engineers, scientists, technologists, and designers of all disciplines, particularly those who design thermal systems or estimate temperatures and heat transfer rates in structures. More than 500 problem solutions and relevant data are tabulated for easy retrieval. There are twelve sections of solutions which correspond with the class of problems found in each. Geometry, state, boundary conditions, and other categories are used to classify the problems. A case number is assigned to each problem for cross-referencing, and also for future reference. Each problem is concisely described by geometry and condition statements, and many times a descriptive sketch is also included. At least one source reference is given so that the user can review the methods used to derive the solutions. Problem solutions are given in the form of equations, graphs, and tables of data, all of which are also identified by problem case numbers and source references.

VanSant, J.H.

1980-03-01

12

3D Simulations of Farley-Buneman Turbulence Demonstrates Anomalous Electron Heating  

NASA Astrophysics Data System (ADS)

Field aligned currents flow from the magnetosphere to the E-region ionosphere where they drive auroral electrojets. These currents often cause Farley-Buneman (FB) instabilities to develop and become turbulent. These irregularities substantially affect ionospheric conductivity, temperatures, and VHF and UHF radio wave propagation. Many of the observed characteristics of radar measurements of this region result from the nonlinear behavior of this unstable plasma. Supercomputers now allow Particle-In-Cell (PIC) codes, to run simulations with enormous meshes in either 2-D or 3-D. This talk will present recent 3-D PIC simulations showing anomalous electron heating due to FB turbulence, a phenomenon clearly observed by radars. The resulting temperatures can rise over an order of magnitude. These simulations also show the saturated amplitude of the waves; coupling between linearly growing modes and damped modes; the evolution of the system from shorter to longer wavelengths; and phase velocities close to the acoustic speed. These simulations reproduce many of the observational characteristics of type-1 radar echoes. As predicted by theory, the 3-D simulations show the development of modes with a small electric field component parallel to the geomagnetic field and this field causes the majority of the anomalous electron heating.

Oppenheim, Meers; Dimant, Yakov

2012-10-01

13

A Simple, Low-Cost Conductive Composite Material for 3D Printing of Electronic Sensors  

PubMed Central

3D printing technology can produce complex objects directly from computer aided digital designs. The technology has traditionally been used by large companies to produce fit and form concept prototypes (‘rapid prototyping’) before production. In recent years however there has been a move to adopt the technology as full-scale manufacturing solution. The advent of low-cost, desktop 3D printers such as the RepRap and Fab@Home has meant a wider user base are now able to have access to desktop manufacturing platforms enabling them to produce highly customised products for personal use and sale. This uptake in usage has been coupled with a demand for printing technology and materials able to print functional elements such as electronic sensors. Here we present formulation of a simple conductive thermoplastic composite we term ‘carbomorph’ and demonstrate how it can be used in an unmodified low-cost 3D printer to print electronic sensors able to sense mechanical flexing and capacitance changes. We show how this capability can be used to produce custom sensing devices and user interface devices along with printed objects with embedded sensing capability. This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes.

Leigh, Simon J.; Bradley, Robert J.; Purssell, Christopher P.; Billson, Duncan R.; Hutchins, David A.

2012-01-01

14

A simple, low-cost conductive composite material for 3D printing of electronic sensors.  

PubMed

3D printing technology can produce complex objects directly from computer aided digital designs. The technology has traditionally been used by large companies to produce fit and form concept prototypes ('rapid prototyping') before production. In recent years however there has been a move to adopt the technology as full-scale manufacturing solution. The advent of low-cost, desktop 3D printers such as the RepRap and Fab@Home has meant a wider user base are now able to have access to desktop manufacturing platforms enabling them to produce highly customised products for personal use and sale. This uptake in usage has been coupled with a demand for printing technology and materials able to print functional elements such as electronic sensors. Here we present formulation of a simple conductive thermoplastic composite we term 'carbomorph' and demonstrate how it can be used in an unmodified low-cost 3D printer to print electronic sensors able to sense mechanical flexing and capacitance changes. We show how this capability can be used to produce custom sensing devices and user interface devices along with printed objects with embedded sensing capability. This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes. PMID:23185319

Leigh, Simon J; Bradley, Robert J; Purssell, Christopher P; Billson, Duncan R; Hutchins, David A

2012-11-21

15

Recent Heat Transfer Improvements to the RELAP5-3D Code  

SciTech Connect

The heat transfer section of the RELAP5-3D computer program has been recently improved. The improvements are as follows: (1) the general cladding rupture model was modified (more than one heat structure segment connected to the hydrodynamic volume and heat structure geometry’s internal gap pressure), (2) the cladding rupture model was modified for reflood, and (3) the heat transfer minor edits/plots were extended to include radiation/enclosure heat flux and generation (internal heat source).

Riemke, Richard A; Davis, Cliff B; Oh, Chang

2007-05-01

16

Heat source parameter estimation from scanned 3D thermal models  

Microsoft Academic Search

Thermal imaging is a non-invasive, non-contact functional imaging method used in temperature measurements. It provides an insight to metabolic and other processes within human body. In this paper a general simulation model that can be used to estimate the depth and size of the heat source embedded underneath the surface of an object is presented. Simulations are performed on two

Ivan Sovic; Lomislav Lipic; Luko Gjenero; Ivan Grubisic; Karolj Skala

2011-01-01

17

Rapid prototyping of electrically conductive components using 3D printing technology  

Microsoft Academic Search

A method of rapid prototyping of electrically conductive components is described. The method is based on 3D printing technology. The prototyped model is made of plaster-based powder bound layer-by-layer by an inkjet printing of a liquid binder. The resulting model is highly porous and can be impregnated by various liquids. In a standard prototyping process, the model is impregnated by

J. Czy?ewski; P. Burzy?ski; K. Gawe?; J. Meisner

2009-01-01

18

Modeling induction heating and 3-D heat transfer for growth of rectangular crystals using FIDAP  

SciTech Connect

We are developing a process to grow large rectangular crystals for use as solid state lasers by a Bridgman-like method. The process is based on induction heating of two graphite susceptors which transfer energy to an ampoule containing the melt and crystal. The induction heating version of FIDAP developed by Gresho and Derby is applied to this system to determine the power deposition profile in electrically conducting regions. The calculated power is subsequently used as a source term in the heat equation to calculate the temperature profile. Results are presented which examine the sensitivity of the system to electrical and thermal conductivities, and design modifications are illustrated which could improve the temperature field for crystal growth applications. 6 refs., 29 figs., 2 tabs.

Atherton, L.J.; Martin, R.W.

1988-09-19

19

Regional Hydraulic Conductivity Field Inferred From Joint Calibrations of 3-D Groundwater Flow and 4He Transport Models  

NASA Astrophysics Data System (ADS)

The conceptual and practical gains achieved by expanding a 2-D finite element model [Castro and Goblet, 2003] to a true 3-D one through an application in the Carrizo aquifer and surrounding formations in southwestern Texas are investigated through a series of groundwater flow and 4He transport simulations. Such a 3-D model represents 4 formations, covers a surface area of ˜7000 km2, and comprises more than 5 million elements. 3-D simulations allow for a more detailed and accurate definition of the heterogeneities of the system, by specifically identifying and differentiating processes that directly impact the three-dimensional hydraulic conductivity field. It is shown that while hydraulic conductivity decreases exponentially along the regional groundwater flow direction, such decrease is better described as a function of depth rather than recharge distance. This relationship reflects the combined influences of differential compaction of the media as well as down-dip lithological change. The intrinsic permeability derived from this relationship agrees with field information. In addition, our relationship intrinsic permeability-depth derived from the obtained hydraulic conductivity field in the 3-D model domain for depths < 2 km is in agreement with that one proposed by Saar and Manga [2004] for the Oregon Cascades volcanic setting, as well as that proposed by Manning and Ingebritsen [1999]. These findings suggest that large-scale permeability evolution with depth is, to a large extent, independent of the type of medium. The 4He external flux value for which calibration of the 3-D transport model was achieved is 1.5×10-15 mol m-2rock s-1. Calculated hydraulic conductivities vary from 5×10-4 to 3.1×10-8 m s-1 in the Carrizo aquifer from the outcrop to the discharge area. Results also suggest that the solution for groundwater flow simulations based on calibration of hydraulic heads depends on the ratio between hydraulic conductivities of different formations, showing that an infinite number of solutions are available for calibration of 3-D groundwater flow models. Understanding how geological processes directly affect the 3-D hydraulic conductivity field at the regional scale is essential not only to hydrogeological applications, but also at improving our understanding of the Earth\\'{ }s crust and mantle dynamics by allowing for a more accurate quantification of helium and heat fluxes. Castro M. C., and Goblet P. (2003). Calibration of regional groundwater flow models - working toward a better understanding of site-specific systems. Water Resour. Res., 39(6), 1172, doi:10.1029/2002WR001653. Manning C. E., and Ingebritsen S. E. (1999). Permeability of the continental crust; implications of geothermal data and metamorphic systems. Rev. Geophys., 37(1), p. 127-150. Saar M. O., and Manga M. (2004). Depth dependence of permeability in the Oregon Cascades inferred from hydrogeologic, thermal, seismic, and magmatic modeling constraints. J. Geophys. Res., 109(B4), B04204, doi:10.1029/2003JB002855.

Castro, M. C.; Patriarche, D.; Goblet, P.

2004-12-01

20

MODELING THE TRANSVERSE THERMAL CONDUCTIVITY OF 3D-SICF/SIC COMPOSITES  

SciTech Connect

Our previously developed hierarchical two-layer (H2L) model was modified to describe the effective transverse thermal conductivity (Keff) of a three-dimensional (3D) SiC/SiC composite plate made with cross-layered and Z-stitched X:Y:Z uniaxial fiber tow sub-units. As before, the model describes Keff in terms of constituent, microstructural and architectural properties that include the expected effects of fiber-matrix interfacial conductance, of high fiber packing fractions within individual tow sub-units and of the non-uniform porosity contents, shapes and orientations within these sub-units. Model predictions were obtained for two versions of a 3D-Tyranno SA?/PyC/ICVI-SiC composite that had similar fiber/matrix pyrocarbon (PyC) interfaces, relatively high bulk densities (~2.88 g/cc), and an X:Y configuration with fiber content ratios 1:1. The only major difference between the two versions was their Z-stitch fiber content where the relative fiber ratios were 0.1 and 1.2 in the Z sub-units.

Youngblood, Gerald E.; Jones, Russell H.; Yamada, Reiji

2004-06-30

21

Temporal changes of saturated hydraulic conductivity - 3D transient modeling using MRI and CT data  

NASA Astrophysics Data System (ADS)

The temporal changes of saturated hydraulic conductivity caused by occurrence of air phase discontinuities play an important role in water flow and solute transport studies. Laboratory recurrent ponded infiltration experiment on undisturbed soil sample reveals significant flow instability characterized by a decrease of the steady state flow rates between the first infiltration run conducted into drier soil and the second infiltration run into wet soil. It is hypothesized that the decrease is due to a random blocking of preferential pathways by residual air. The entrapped air distribution and its impact on flow were studied combining magnetic resonance (MR) imaging data and numerical simulations. Internal structure of the soil sample elaborated from X-ray computed tomography images via scaling factors was implemented into the 3D water flow simulation model based on Richards' equation. MR relaxometry data were used to derive 3D maps of entrapped air. The distribution of water content within the sample was evaluated using MR imaging. Simulation results describe measured outflow rates and pressure heads quite well and at the same time reproduce reliably heterogeneous field of water content as visualized by MR imaging. The assumption that the observed decrease of the outflow rate could be caused by entrapped air in large pores of the soil sample was approved at this case. The research has been supported by Czech Science Foundation under grant No. 103/08/1552 and by MZP CR under grant No. SP/2E7/229/07.

Cislerova, M.; Jelinkova, V.; Dohnal, M.; Snehota, M.; Brezina, J.; Dusek, J.

2011-12-01

22

The surface conductivity effects on the structure of Mercury's magnetosphere: a 3D hybrid simulation study  

NASA Astrophysics Data System (ADS)

Mercury's magnetosphere is a poor known system which couples directly to the surface but is hardly affected by the tenuous ionosphere. As a terrestrial moon-like body, the closure of the field-aligned currents (FACs) remains a critical issue for the study of the magnetosphere. We performed a 3D hybrid model to simulate the Hermean system without injecting any planetary ions and treated the surface of Mercury with small resisitivity (10-3 S/m) and large resistivity (10-7 S/m) for comparison. While the surface conductivity has equivalent functions as a substantial ionosphere, the magnetosphere could be taken as a mini-size of Earth-like structure. However, as the surface resistivity increases to avoid the FACs from completion, the plasma flow would be modified as a feedback. The plasma environment and the magnetic distribution around Mercury were examined and the effect of the surface conductivity on the morphology of Mercury's magnetosphere could be acquainted more closely through the inspection.

Wang, Yung-Ching; Ip, Wing-Huen; Mueller, Joachim; Motschmann, Uwe

2010-05-01

23

A hybrid, infrared thermography: heat diffusion equation, method for the 3D air-temperature measurement  

NASA Astrophysics Data System (ADS)

The question of how to map the 3D indoor temperature by infrared thermography is solved by a hybrid method which is a combination of infrared thermography and the well known heat diffusion equation. The idea is to use infrared thermography to get the surface temperature of each frontier of the 3D domain of interest. A suitable procedure is devoted to this, allowing an automatic scanning of the whole frontier, the registration of data and computation. These surface temperatures constitute the boundary conditions of the heat equation solved in the domain of interest. The solution of the heat equation allows analyzing and controlling the temperature of every point belonging to the considered domain. This temperature distribution is controlled over the time with a period of the same order than the necessary time to obtain the frontier temperatures and at the end to contribute to the analysis of the thermal comfort. The study is done for the steady-state conditions under various weather situations. In this case the temperature depends only on space coordinates. With such procedure, we can have an idea about the time necessary to reach thermal equilibrium; time which has a great impact on the thermal comfort sensation. The results yielded by this method are compared with those given by others techniques used for temperature measurement. Finally, the method is used to access 3D temperature distribution for various geometric shapes.

Djupkep Dizeu, F. B.; Maldague, X.; Bendada, A.; Grinzato, E.; Bison, P.

2011-05-01

24

Performance of a variable conductance heat pipe heat exchanger  

Microsoft Academic Search

The performance of an air to air heat exchanger in which heat is transferred to a finned evaporator and from a finned condenser via a heat pipe was evaluated. The variable conductance heat pipe is to the condenser fins a heat source and to the evaporator fins a heat sink. The principal advantage of the variable conductance heat pipe heat

P. D. Chancelor

1983-01-01

25

Properties of the magmatic system that feeds Yellowstone inferred from 3-D electrical conductivity model  

NASA Astrophysics Data System (ADS)

We have performed a set of three dimensional inversions of magnetotelluric data in the Snake River Plain and Yellowstone areas. We used a total of 73 sites from Earthscope MT Transportable Array (Idaho, Montana and Wyoming areas) and a subset of 19 sites from an earlier long-period MT survey in the Snake River Plain (SRP). Data for 14 periods from 7.3 secs to 5.2 hours were inverted for 3D inverse conductivity models on 7 and 14 km grids, fitting both the impedances (with 5% error floors) and the vertical magnetic transfer functions to an RMS of 2.3 (14 km grid) and 2.7 (7 km grid). The images reveal the presence of a large, interconnected conductive body beneath the Eastern and central SRP. The lithospheric (40-100 km depths) anomaly extends to at least 200 km southwest of Yellowstone, roughly parallel to the direction of North America absolute motion. The anomaly connects to the near-surface in several locations along and to the North of the SRP, as well as directly beneath the Yellowstone caldera. There, highly conductive (~ 1 S/m) shallow anomalies are to be found. This leads us to believe that the complex lithospheric feature beneath the SRP represents a magma reservoir, rich in volatile constituents, that feeds the Yellowstone hotspot. Additionally, in several locations beneath the Eastern SRP very high conductivities (a few S/m) are imaged at or near the base of the lower crust. These can probably be explained by a combination of partial melt, and highly saline fluids exsolved during magmatic underplating. We also see a weaker (~ 0.02 S/m) deep mantle conductor centered around Yellowstone that broadens with depth, extending all the way to the transition zone or deeper. Plausibly this reflects the seismically imaged thermal anomaly (Yuan and Duecker, 2005; Smith et al,, 2009), poorly resolved by the MT data, which are much more strongly impacted by partial melt and fluids present at shallower depths. The lateral spatial extent of the mantle conductive anomalies correlates well with low velocity anomalies in the upper mantle imaged teleseismically (e.g., Humphreys et al, 2000; Tian et al, 2009; Smith et al, 2009), and with surface wave tomography (Schutt et al., 2008). Overall our images are quite consistent with interpretations that emphasize the role of local convection and lithospheric interaction to explain patterns of progressive magmatism along the Yellowstone "hot spot" track (Humphreys et al, 2000; Christiansen et al., 2002; Leeman et al, 2009).

Kelbert, A.; Egbert, G. D.; Degroot-Hedlin, C. D.; Meqbel, N.

2010-12-01

26

3D volume MR temperature mapping for HIFU heating trajectory comparisons  

NASA Astrophysics Data System (ADS)

Many areas of MR-guided thermal therapy research would benefit from temperature maps with high spatial and temporal resolution that cover a large 3-D volume. This paper describes an approach to achieve these goals that is suitable for research applications where retrospective reconstruction of the temperature maps is acceptable. The method acquires undersampled data from a modified 3-D segmented EPI sequence and creates images using a temporally constrained reconstruction algorithm. The 3-D images can be zero-filled to arbitrarily small voxel spacing in all directions and then converted into temperature maps using the standard proton resonance frequency (PRF) shift technique. During HIFU heating experiments, the proposed method was used to obtain temperature maps with 1.5×1.5×3.0 mm resolution, 288×162×78 mm field of view, and 1.7 second temporal resolution. The approach is validated to demonstrate that it can accurately capture the spatial characteristics and time dynamics of rapidly changing HIFU-induced temperature distributions. An example application is presented where the method is used to analyze and compare different HIFU volumetric heating trajectories.

Todd, Nick; Vyas, Urvi; de Bever, Josh; Payne, Allison; Parker, Dennis L.

2012-10-01

27

Modeling of radiative heat transfer in 3D complex boiler with non-gray sooting media  

NASA Astrophysics Data System (ADS)

The radiative heat transfer problem is solved for 3D complex industrial boiler with five baffles containing a mixture of carbon dioxide and water vapor for non-uniform temperature fields. A numerical formulation using the FTn finite volume method coupled with the bounded high-order resolution CLAM scheme, the blocked-off-region procedure and the narrow-band based weighted-sum-of-gray-gases (WSGG) [Kim OJ, Song T-H. Data base of WSGGM-based spectral model for radiation properties of combustion products, JQSRT 2000; 64: 379 94] model is adapted. The effect of soot volumetric fraction, particle temperature and uniform particle concentration on the radiative heat flux and radiative heat source is investigated and discussed. Also the advantages, in non-gray media, of the FTnFVM compared to the classical FVM are highlighted.

Borjini, Mohamed Naceur; Guedri, Kamel; Saïd, Rachid

2007-06-01

28

3D modelling of coupled mass and heat transfer of a convection-oven roasting process.  

PubMed

A 3D mathematical model of coupled heat and mass transfer describing oven roasting of meat has been developed from first principles. The proposed mechanism for the mass transfer of water is modified and based on a critical literature review of the effect of heat on meat. The model equations are based on a conservation of mass and energy, coupled through Darcy's equations of porous media - the water flow is mainly pressure-driven. The developed model together with theoretical and experimental assessments were used to explain the heat and water transport and the effect of the change in microstructure (permeability, water binding capacity and elastic modulus) that occur during the meat roasting process. The developed coupled partial differential equations were solved by using COMSOL Multiphysics®3.5 and state variables are predicted as functions of both position and time. The proposed mechanism was partially validated by experiments in a convection oven where temperatures were measured online. PMID:23305831

Feyissa, Aberham Hailu; Gernaey, Krist V; Adler-Nissen, Jens

2012-12-10

29

Heat conduction of symmetric lattices.  

PubMed

Heat conduction of symmetric Frenkel-Kontorova (FK) lattices with a coupling displacement was investigated. Through simplifying the model, we derived analytical expression of thermal current of the system in the overdamped case. By means of numerical calculations, the results indicate that: (i) As the coupling displacement d equals to zero, temperature oscillations of the heat baths linked with the lattices can control magnitude and direction of the thermal current; (ii) Whether there is a temperature bias or not, the thermal current oscillates periodically with d, whose amplitudes become greater and greater; (iii) As d is not equal to zero, the thermal current monotonically both increases and decreases with temperature oscillation amplitude of the heat baths, dependent on values of d; (iv) The coupling displacement also induces nonmonotonic behaviors of the thermal current vs spring constant of the lattice and coupling strength of the lattices; (v) These dynamical behaviors come from interaction of the coupling displacement with periodic potential of the FK lattices. Our results have the implication that the coupling displacement plays a crucial role in the control of heat current. PMID:23848662

Nie, Linru; Yu, Lilong; Zheng, Zhigang; Shu, Changzheng

2013-06-28

30

Global 3-D EM inversion of Sq variations based on simultaneous source and conductivity determination: concept validation and resolution studies  

NASA Astrophysics Data System (ADS)

We present a novel global 3-D electromagnetic (EM) inverse solution that allows to work in a unified and consistent manner with frequency-domain data that originate from ionospheric and magnetospheric sources irrespective of their spatial complexity. The main idea behind the approach is simultaneous determination of the source and conductivity distribution in the Earth. Such a determination is implemented in our solution as a looped sequential procedure that involves two steps: (1) determination of the source using a fixed 3-D conductivity model and (2) recovery of a 3-D conductivity model using a fixed source. We focus in this paper on analysis of Sq data and numerically verify each step separately and combined using data synthesized from 3-D models of the Earth induced by a realistic Sq source. To determine the source we implement an approach that makes use of a known conductivity structure of the Earth with non-uniform oceans. Based on model studies we show that this approach outperforms the conventional potential method. As for recovery of 3-D conductivity in the mantle, our inverse scheme relies on a regularized least-square formulation, exploits a limited-memory quasi-Newton optimization method and makes use of the adjoint source approach to calculate efficiently the misfit gradient. We perform resolution studies with checkerboard conductivity structures at depths between 10 and 1600 km for different inverse setups and conclude from these studies that: (1) inverting Z component gives much better results than inverting all (X, Y and Z) components; (2) data from the Sq source allows for resolving 3-D structures in depth range between 100 and 520 km; (3) the best resolution is achieved in the depth range of 100-250 km.

Koch, Stephan; Kuvshinov, Alexey

2013-10-01

31

Magnetotelluric source effect due to 3D ionospheric current systems using the complex image method for 1D conductivity structures  

Microsoft Academic Search

The complex image method (CIM) is an efficient tool to calculate the electromagnetic field at the earth's surface produced by 3D ionospheric current systems when the earth has a layered conductivity structure. The calculations are applicable to the estimation of source effects on magnetotelluric data. In this paper CIM is used in connection with some typical high-latitude ionospheric events: a

Ari Viljanen; Risto Pirjola; Olaf Amm

1999-01-01

32

Anisotropic heat transport in integrable and chaotic 3-D magnetic fields  

SciTech Connect

A study of anisotropic heat transport in 3-D chaotic magnetic fields is presented. The approach is based on the recently proposed Lagrangian-Green s function (LG) method in Ref. [1] that allows an efficient and accurate integration of the parallel transport equation applicable to general magnetic fields with local or non-local parallel flux closures. We focus on reversed shear magnetic field configurations known to exhibit separatrix reconnection and shearless transport barriers. The role of reconnection and magnetic field line chaos on temperature transport is studied. Numerical results are presented on the anomalous relaxation of radial temperature gradients in the presence of shearless Cantori partial barri- ers. Also, numerical evidence of non-local effective radial temperature transport in chaotic fields is presented. Going beyond purely parallel transport, the LG method is generalized to include finite perpendicular diffusivity, and the problem of temperature flattening inside a magnetic island is studied.

Del-Castillo-Negrete, Diego B [ORNL; Blazevski, D. [University of Texas, Austin; Chacon, Luis [ORNL

2012-01-01

33

The effect of anisotropic heat transport on magnetic islands in 3-D configurations  

SciTech Connect

An analytic theory of nonlinear pressure-induced magnetic island formation using a boundary layer analysis is presented. This theory extends previous work by including the effects of finite parallel heat transport and is applicable to general three dimensional magnetic configurations. In this work, particular attention is paid to the role of finite parallel heat conduction in the context of pressure-induced island physics. It is found that localized currents that require self-consistent deformation of the pressure profile, such as resistive interchange and bootstrap currents, are attenuated by finite parallel heat conduction when the magnetic islands are sufficiently small. However, these anisotropic effects do not change saturated island widths caused by Pfirsch-Schlueter current effects. Implications for finite pressure-induced island healing are discussed.

Schlutt, M. G.; Hegna, C. C. [University of Wisconsin-Madison, 1500 Engineering Drive, 510 ERB, Madison, Wisconsin 53706 (United States)

2012-08-15

34

The effect of anisotropic heat transport on magnetic islands in 3-D configurations  

NASA Astrophysics Data System (ADS)

An analytic theory of nonlinear pressure-induced magnetic island formation using a boundary layer analysis is presented. This theory extends previous work by including the effects of finite parallel heat transport and is applicable to general three dimensional magnetic configurations. In this work, particular attention is paid to the role of finite parallel heat conduction in the context of pressure-induced island physics. It is found that localized currents that require self-consistent deformation of the pressure profile, such as resistive interchange and bootstrap currents, are attenuated by finite parallel heat conduction when the magnetic islands are sufficiently small. However, these anisotropic effects do not change saturated island widths caused by Pfirsch-Schlüter current effects. Implications for finite pressure-induced island healing are discussed.

Schlutt, M. G.; Hegna, C. C.

2012-08-01

35

A Non-Linear Inversion for the Global 3-D Electrical Conductivity Distribution in the Upper to Mid-Mantle  

NASA Astrophysics Data System (ADS)

The case for substantial heterogeneity in mantle conductivity has stimulated the development of methods for solving Maxwell's equations in a heterogeneous conducting sphere. A global 3-D frequency domain forward solver has been devised (Uyeshima & Schultz, 2000), accurate and efficient enough to be an attractive kernel of a practical inverse method. The solver employs a staggered-grid finite difference formulation in spherical coordinates. The induced fields are found as a solution to the integral form of Maxwell's equations, while the system is solved using stabilised biconjugate gradient methods. A single, accurate forward solution takes approx. 4 minutes on 5 GFLOP (peak) processor. The aim of our present research is to produce an inverse solver, to be applied to the Fujii & Schultz (2002) data set of globally-distributed EM response functions, which would reconstruct the 3-D electrical conductivity distribution in the upper to mid-mantle. Geophysical inversion is an ill-posed problem, therefore the aim is to apply suitable parameter constraints and a nonlinear search algorithm to identify candidate minima, then to apply local gradient methods around those minima. Our specific target involves designing a fast enough global optimisation routine that would allow us to produce at least one fully 3-D starting model, optimal with respect to the RMS misfit between the data and the forward solutions. A new and very flexible inverse solver has been developed utilizing parallel optimisation routines to obtain a starting model that satisfies the data. 3-D simulations have been run, the parametrization based on a spherical harmonic representation of a chess board model of varying degree and order. The inversion has demonstrated accurate fidelity in reproducing resolvable features of the test model. A study has been made of the reduction in fidelity as the number and distribution of observatory sites on the Earth's surface is degraded. An inversion of the Fujii & Schultz (2002) geomagnetic data set is underway. We also discuss implementing a linearised sensitivity analysis as part of the inversion.

Kelbert, A.; Schultz, A.

2004-12-01

36

3D modeling of the heating of a metal sheet by a moving arc: application to aircraft lightning protection  

NASA Astrophysics Data System (ADS)

Within the framework of the study of the aircraft structural material lightning, we present a work concerning the heating of metal sheets under the action of a moving electric arc. A 2D and 3D modeling of thermal phenomena occurring in the heated electrodes are used in order to study the influence of the arc root velocity and of the power and the surface power density brought by the arc roots on the electrode heating.

Testé, Ph.; Leblanc, T.; Uhlig, F.; Chabrerie, J.-P.

2000-09-01

37

Effect of Weaving Direction of Conductive Yarns on Electromagnetic Performance of 3D Integrated Microstrip Antenna  

NASA Astrophysics Data System (ADS)

A three-dimensionally integrated microstrip antenna (3DIMA) is a microstrip antenna woven into the three-dimensional woven composite for load bearing while functioning as an antenna. In this study, the effect of weaving direction of conductive yarns on electromagnetic performance of 3DIMAs are investigated by designing, simulating and experimental testing of two microstrip antennas with different weaving directions of conductive yarns: one has the conductive yarns along the antenna feeding direction (3DIMA-Exp1) and the other has the conductive yarns perpendicular the antenna feeding direction (3DIMA-Exp2). The measured voltage standing wave ratio (VSWR) of 3DIMA-Exp1 was 1.4 at the resonant frequencies of 1.39 GHz; while that of 3DIMA-Exp2 was 1.2 at the resonant frequencies of 1.35 GHz. In addition, the measured radiation pattern of the 3DIMA-Exp1 has smaller back lobe and higher gain value than those of the 3DIMA-Exp2. This result indicates that the waving direction of conductive yarns may have a significant impact on electromagnetic performance of textile structural antennas.

Xu, Fujun; Yao, Lan; Zhao, Da; Jiang, Muwen; Qiu, Yipping

2013-10-01

38

Heat Conduction in Bismuth Telluride  

Microsoft Academic Search

The Lorenz number of the semiconductor Bi2Te3 has been evaluated, for the range of partial degeneracy, from data provided by the measurements of electrical conductivity and thermoelectric power. The calculated electronic component of the thermal conductivity, for p-type material, has been found to agree with the experimental results, assuming the lattice thermal conductivity to be independent of the electrical conductivity.

H J Goldsmid

1958-01-01

39

A three-dimensional inverse heat conduction problem in estimating surface heat flux by conjugate gradient method  

Microsoft Academic Search

In the present study a three-dimensional (3-D) transient inverse heat conduction problem is solved using the conjugate gradient method (CGM) and the general purpose commercial code CFX4.2-based inverse algorithm to estimate the unknown boundary heat flux in any 3-D irregular domain.The advantage of calling CFX4.2 as a subroutine in the present inverse calculation lies in that many difficult but practical

Cheng-Hung Huang; Shao-Pei Wang

1999-01-01

40

Remote Sensing of 3-D Conducting Objects in a Layered Medium Using Electromagnetic Surface Waves  

Microsoft Academic Search

Antennas that are located on or near the boundary between two electrically different media, such as air and earth, or seawater and rock, are used as prospective tools for remote sensing and geophysical exploration. As an example, this letter examines the electromagnetic (EM) response of a metallic object that is submerged in a conducting layer of seawater that is situated

Marius Birsan

2007-01-01

41

Parallel 3D Poisson solver for a charged beam in a conducting pipe  

Microsoft Academic Search

In this paper, we present a parallel three-dimensional Poisson solver for the electrostatic potential of a charged beam in a round or rectangular conducting pipe with open-end boundary conditions. This solver uses an eigenfunction expansion in the transverse direction and a finite difference method in the longitudinal direction. The computational domain in the longitudinal direction contains only the beam since

J. Qiang; Robert D. Ryne

2001-01-01

42

Solid State Conductivity and Catalytic Activity of Hexacyanoferrate(II)–Thiosemicarbazide Complexes of 3 d Metals  

Microsoft Academic Search

The temperature dependence of the resistivity of tablets of hexacyanoferrate(II)–thiosemicarbazide complexes of chromium(III), manganese(II), iron(III), cobalt(III), nickel(II), copper(II), and zinc(II) was measured in the range 20-90 °C. A relationship between the conductivity of a substance and the rate constant for the catalytic decomposition of hydrogen peroxide is established.

T. V. Koksharova; A. A. Ptashchenko; N. V. Masleeva; S. V. Fel'dman; N. N. Pasternak; S. A. Stukalov

2002-01-01

43

Electromagnetic mini arrays (EMMA project). 3D modeling/inversion for mantle conductivity in the Archaean of the Fennoscandian Shield  

NASA Astrophysics Data System (ADS)

Two electromagnetic arrays are used in the EMMA project to study conductivity structure of the Archaean lithosphere in the Fennoscandian Shield. The first array was operated during almost one year, while the second one was running only during the summer time. Twelve 5-components magnetotelluric instruments with fluxgate magnetometers recorded simultaneously time variations of Earth's natural electromagnetic field at the sites separated by c. 30 km. To better control the source field and to obtain galvanic distortion free responses we have applied horizontal spatial gradient (HSG) technique to the data. The study area is highly inhomogeneous, thus classical HSG might give erroneous results. The method was extended to include anomalous field effects by implementing multivariate analysis. The HSG transfer functions were then used to control static shift distortions of apparent resistivities. During the BEAR experiment 1997-2002, the conductance map of entire Fennoscandia was assembled and finally converted into 3D volume resistivity model. We have used the model, refined it to get denser grid around measurement area and calculated MT transfer functions after 3D modeling. We have used trial-and-error method in order to further improve the model. The data set was also inverted using 3D code of Siripunvaraporn (2005). In the first stage we have used homogeneous halfspace as starting model for the inversion. In the next step we have used final 3D forward model as apriori model. The usage of apriori information significantly stabilizes the inverse solution, especially in case of a limited amount of data available. The results show that in the Archaean Domain a conductive layer is found in the upper/middle crust on contrary to previous results from other regions of the Archaean crust in the Fennoscandian Shield. Data also suggest enhanced conductivity at the depth of c. 100 km. Conductivity below the depth of 200-250 km is lower than that of the laboratory based estimates of dry olivine. The last finding suggests that the base of lithosphere is very deep beneath the central part of the cratonic Fennoscandia.

Smirnov, M. Yu.; Korja, T.; Pedersen, L. B.

2009-04-01

44

Global 3-D imaging of mantle conductivity based on inversion of observatory C-responses—II. Data analysis and results  

NASA Astrophysics Data System (ADS)

The global 3-D electrical conductivity distribution in the mantle (in the depth range between 400 and 1600 km) is imaged by inverting C-responses estimated on a global net of geomagnetic observatories. Very long time-series (up to 51 years; 1957-2007) of hourly means of three components of the geomagnetic field from 281 geomagnetic observatories are collected and analysed. Special attention is given to data processing in order to obtain unbiased C-responses with trustworthy estimates of experimental errors in the period range from 2.9 to 104.2 d. After careful inspection of the obtained C-responses the data from 119 observatories are chosen for the further analysis. Squared coherency is used as a main quality indicator to detect (and then to exclude from consideration) observatories with a large noise-to-signal ratio. During this analysis we found that—along with the C-responses from high-latitude observatories (geomagnetic latitudes higher than 58°)—the C-responses from all low-latitude observatories (geomagnetic latitudes below 11°) also have very low squared coherencies, and thus cannot be used for global induction studies. We found that the C-responses from the selected 119 mid-latitude observatories show a huge variability both in real and imaginary parts, and we investigated to what extent the ocean effect can explain such a scatter. By performing the systematic model calculations we conclude that: (1) the variability due to the ocean effect is substantial, especially at shorter periods, and it is seen for periods up to 40 d or so; (2) the imaginary part of the C-responses is to a larger extent influenced by the oceans; (3) two types of anomalous C-response behaviour associated with the ocean effect can be distinguished; (4) to accurately reproduce the ocean effect a lateral resolution of 1°× 1° of the conductance distribution is needed, and (5) the ocean effect alone does not explain the whole variability of the observed C-responses. We also detected that part of the variability in the real part of the C-responses is due to the auroral effect. In addition we discovered that the auroral effect in the C-responses reveals strong longitudinal variability, at least in the Northern Hemisphere. Europe appears to be the region with smallest degree of distortion compared with North America and northern Asia. We found that the imaginary part of the C-responses is weakly affected by the auroral source, thus confirming the fact that in the considered period range the electromagnetic (EM) induction from the auroral electrojet is small. Assuming weak dependence of the auroral signals on the Earth's conductivity at considered periods, and longitudinal variability of the auroral effect, we developed a scheme to correct the experimental C-responses for this effect. With these developments and findings in mind we performed a number of regularized 3-D inversions of our experimental data in order to detect robust features in the recovered 3-D conductivity images. Although differing in details, all our 3-D inversions reveal a substantial level of lateral heterogeneity in the mantle at the depths between 410 and 1600 km. Conductivity values vary laterally by more than one order of magnitude between resistive and conductive regions. The maximum lateral variations of the conductivity have been detected in the layer at depths between 670 and 900 km. By comparing our global 3-D results with the results of independent global and semi-global 3-D conductivity studies, we conclude that 3-D conductivity mantle models produced so far are preliminary as different groups obtain disparate results, thus complicating quantitative comparison with seismic tomography or/and geodynamic models. In spite of this, our 3-D EM study and most other 3-D EM studies reveal at least two robust features: reduced conductivity beneath southern Europe and northern Africa, and enhanced conductivity in northeastern China.

Semenov, Alexey; Kuvshinov, Alexey

2012-12-01

45

Coherent phonon heat conduction in superlattices.  

PubMed

The control of heat conduction through the manipulation of phonons as coherent waves in solids is of fundamental interest and could also be exploited in applications, but coherent heat conduction has not been experimentally confirmed. We report the experimental observation of coherent heat conduction through the use of finite-thickness superlattices with varying numbers of periods. The measured thermal conductivity increased linearly with increasing total superlattice thickness over a temperature range from 30 to 150 kelvin, which is consistent with a coherent phonon heat conduction process. First-principles and Green's function-based simulations further support this coherent transport model. Accessing the coherent heat conduction regime opens a new venue for phonon engineering for an array of applications. PMID:23161996

Luckyanova, Maria N; Garg, Jivtesh; Esfarjani, Keivan; Jandl, Adam; Bulsara, Mayank T; Schmidt, Aaron J; Minnich, Austin J; Chen, Shuo; Dresselhaus, Mildred S; Ren, Zhifeng; Fitzgerald, Eugene A; Chen, Gang

2012-11-16

46

Coherent Phonon Heat Conduction in Superlattices  

NASA Astrophysics Data System (ADS)

The control of heat conduction through the manipulation of phonons as coherent waves in solids is of fundamental interest and could also be exploited in applications, but coherent heat conduction has not been experimentally confirmed. We report the experimental observation of coherent heat conduction through the use of finite-thickness superlattices with varying numbers of periods. The measured thermal conductivity increased linearly with increasing total superlattice thickness over a temperature range from 30 to 150 kelvin, which is consistent with a coherent phonon heat conduction process. First-principles and Green’s function-based simulations further support this coherent transport model. Accessing the coherent heat conduction regime opens a new venue for phonon engineering for an array of applications.

Luckyanova, Maria N.; Garg, Jivtesh; Esfarjani, Keivan; Jandl, Adam; Bulsara, Mayank T.; Schmidt, Aaron J.; Minnich, Austin J.; Chen, Shuo; Dresselhaus, Mildred S.; Ren, Zhifeng; Fitzgerald, Eugene A.; Chen, Gang

2012-11-01

47

New Global 3D Upper to Mid-mantle Electrical Conductivity Model Based on Observatory Data with Realistic Auroral Sources  

NASA Astrophysics Data System (ADS)

Poleward of 45-50 degrees (geomagnetic) observatory data are influenced significantly by auroral ionospheric current systems, invalidating the simplifying zonal dipole source assumption traditionally used for long period (T > 2 days) geomagnetic induction studies. Previous efforts to use these data to obtain the global electrical conductivity distribution in Earth's mantle have omitted high-latitude sites (further thinning an already sparse dataset) and/or corrected the affected transfer functions using a highly simplified model of auroral source currents. Although these strategies are partly effective, there remain clear suggestions of source contamination in most recent 3D inverse solutions - specifically, bands of conductive features are found near auroral latitudes. We report on a new approach to this problem, based on adjusting both external field structure and 3D Earth conductivity to fit observatory data. As an initial step towards full joint inversion we are using a two step procedure. In the first stage, we adopt a simplified conductivity model, with a thin-sheet of variable conductance (to represent the oceans) overlying a 1D Earth, to invert observed magnetic fields for external source spatial structure. Input data for this inversion are obtained from frequency domain principal components (PC) analysis of geomagnetic observatory hourly mean values. To make this (essentially linear) inverse problem well-posed we regularize using covariances for source field structure that are consistent with well-established properties of auroral ionospheric (and magnetospheric) current systems, and basic physics of the EM fields. In the second stage, we use a 3D finite difference inversion code, with source fields estimated from the first stage, to further fit the observatory PC modes. We incorporate higher latitude data into the inversion, and maximize the amount of available information by directly inverting the magnetic field components of the PC modes, instead of transfer functions such as C-responses used previously. Recent improvements in accuracy and speed of the forward and inverse finite difference codes (a secondary field formulation and parallelization over frequencies) allow us to use finer computational grid for inversion, and thus to model finer scale features, making full use of the expanded data set. Overall, our approach presents an improvement over earlier observatory data interpretation techniques, making better use of the available data, and allowing to explore the trade-offs between complications in source structure, and heterogeneities in mantle conductivity. We will also report on progress towards applying the same approach to simultaneous source/conductivity inversion of shorter period observatory data, focusing especially on the daily variation band.

Kelbert, A.; Egbert, G. D.; Sun, J.

2011-12-01

48

Albedo and heat transport in 3-D model simulations of the early Archean climate  

NASA Astrophysics Data System (ADS)

At the beginning of the Archean eon (ca. 3.8 billion years ago), the Earth's climate state was significantly different from today due to the lower solar luminosity, smaller continental fraction, higher rotation rate and, presumably, significantly larger greenhouse gas concentrations. All these aspects play a role in solutions to the "faint young Sun paradox" which must explain why the ocean surface was not fully frozen at that time. Here, we present 3-D model simulations of climate states that are consistent with early Archean boundary conditions and have different CO2 concentrations, aiming at an understanding of the fundamental characteristics of the early Archean climate system. In order to do so, we have appropriately modified an intermediate complexity climate model that couples a statistical-dynamical atmosphere model (involving parameterizations of the dynamics) to an ocean general circulation model and a thermodynamic-dynamic sea-ice model. We focus on three states: one of them is ice-free, one has the same mean surface air temperature of 288 K as today's Earth and the third one is the coldest stable state in which there is still an area with liquid surface water (i.e. the critical state at the transition to a "snowball Earth"). We find a reduction in meridional heat transport compared to today, which leads to a steeper latitudinal temperature profile and has atmospheric as well as oceanic contributions. Ocean surface velocities are largely zonal, and the strength of the atmospheric meridional circulation is significantly reduced in all three states. These aspects contribute to the observed relation between global mean temperature and albedo, which we suggest as a parameterization of the ice-albedo feedback for 1-D model simulations of the early Archean and thus the faint young Sun problem.

Kienert, H.; Feulner, G.; Petoukhov, V.

2013-08-01

49

Thermal design tool for outdoor spaces based on heat balance simulation using a 3D-CAD system  

Microsoft Academic Search

This paper focuses on the development of a thermal design tool for use in planning outdoor spaces by combining a heat balance simulation for urban surfaces, including buildings, the ground and greenery, with a 3D-CAD system that can be run on a personal computer. The newly developed tool is constructed by improving the previous simulation model, which uses the geographic

Takashi Asawa; Akira Hoyano; Kazuaki Nakaohkubo

2008-01-01

50

Power transformer thermal analysis by using an advanced coupled 3D heat transfer and fluid flow FEM model  

Microsoft Academic Search

Thermal performance in oil-immersed power transformers is governed by the flow of oil, acting both as an electrical insulator and a medium for the transfer of heat generated in the core and windings toward the tank and the surrounding air. This paper presents the development of an advanced three-dimensional (3D) finite element model for the coupled solution of heat transfer

Marina A. Tsili; Eleftherios I. Amoiralis; Antonios G. Kladas; Athanassios T. Souflaris

51

Ballistic-Diffusive Heat-Conduction Equations  

Microsoft Academic Search

We present new heat-conduction equations, named ballistic-diffusive equations, which are derived from the Boltzmann equation. We show that the new equations are a better approximation than the Fourier law and the Cattaneo equation for heat conduction at the scales when the device characteristic length, such as film thickness, is comparable to the heat-carrier mean free path and\\/or the characteristic time,

Gang Chen; Gang

2001-01-01

52

Coupled three-dimensional conduction and natural convection heat transfer  

NASA Astrophysics Data System (ADS)

A numerical and experimental investigation of three-dimensional natural convection heat transfer coupled with conduction was performed. This general problem is of great importance because of its widespread applicability in areas such as compact natural convection heat exchangers, cooling of electronic equipment, and porous media flows. The determination of flow patterns and heat transfer coefficients in such situations is necessary because of its practical use in various industries. A vectorized finite difference code was developed for the Cray-2 supercomputer which has the capability of simulating a wide class of three-dimensional coupled conduction-convection problems. This program numerically solves the transient form of the complete laminar Navier-Stokes equations of motion using the vorticity-vector potential methods. Using this program, numerical solutions were obtained for 3-D natural convection from a horizontal isothermal heat exchanger tube with an attached circular cooling fin array. Experiments were performed to measure three-dimensional temperature fields using Mach-Zehnder interferometry. Software was developed to digitize and process fringe patterns and inversion algorithms used to compute the 3-D temperature field.

Tolpadi, Anil Kumar

1987-09-01

53

Hierarchical self-assembly of hexagonal single-crystal nanosheets into 3D layered superlattices with high conductivity  

NASA Astrophysics Data System (ADS)

While the number of man-made nano superstructures realized by self-assembly is growing in recent years, assemblies of conductive polymer nanocrystals, especially for superlattices, are still a significant challenge, not only because of the simplicity of the shape of the nanocrystal building blocks and their interactions, but also because of the poor control over these parameters in the fabrication of more elaborate nanocrystals. Here, we firstly report a facile and general route to a new generation of 3D layered superlattices of polyaniline doped with CSA (PANI-CSA) and show how PANI crystallize and self-assemble, in a suitable single solution environment. In cyclohexane, 1D amorphous nanofibers transformed to 1D nanorods as building blocks, and then to 2D single-crystal nanosheets with a hexagonal phase, and lastly to 3D ordered layered superlattices with the narrowest polydispersity value (Mw/Mn = 1.47). Remarkably, all the instructions for the hierarchical self-assembly are encoded in the layered shape in other non-polar solvents (hexane, octane) and their conductivity in the ?-? stacking direction is improved to about 50 S cm-1, which is even higher than that of the highest previously reported value (16 S cm-1). The method used in this study is greatly expected to be readily scalable to produce superlattices of conductive polymers with high quality and low cost.While the number of man-made nano superstructures realized by self-assembly is growing in recent years, assemblies of conductive polymer nanocrystals, especially for superlattices, are still a significant challenge, not only because of the simplicity of the shape of the nanocrystal building blocks and their interactions, but also because of the poor control over these parameters in the fabrication of more elaborate nanocrystals. Here, we firstly report a facile and general route to a new generation of 3D layered superlattices of polyaniline doped with CSA (PANI-CSA) and show how PANI crystallize and self-assemble, in a suitable single solution environment. In cyclohexane, 1D amorphous nanofibers transformed to 1D nanorods as building blocks, and then to 2D single-crystal nanosheets with a hexagonal phase, and lastly to 3D ordered layered superlattices with the narrowest polydispersity value (Mw/Mn = 1.47). Remarkably, all the instructions for the hierarchical self-assembly are encoded in the layered shape in other non-polar solvents (hexane, octane) and their conductivity in the ?-? stacking direction is improved to about 50 S cm-1, which is even higher than that of the highest previously reported value (16 S cm-1). The method used in this study is greatly expected to be readily scalable to produce superlattices of conductive polymers with high quality and low cost. Electronic supplementary information (ESI) available: SEM, and TEM images. See DOI: 10.1039/c2nr30743j

Tao, Yulun; Shen, Yuhua; Yang, Liangbao; Han, Bin; Huang, Fangzhi; Li, Shikuo; Chu, Zhuwang; Xie, Anjian

2012-05-01

54

Use of 2D and 3D Resistivity Methods to Monitor Dilution of a Conductive Plume in Fractured Basalt  

NASA Astrophysics Data System (ADS)

2D cross-borehole and 3D surface electrical resistance tomography (ERT) methods have been shown to be useful in delineating conductive plume migration in porous media. However, their application in fractured basalt, and to monitoring in situ dilution of conductive plumes has been largely uninvestigated. The objective of this study was to monitor the dilution of a conductive plume by more resistive water to delineate the spatial distribution of resistivity changes over time. Eight wells were drilled for the hydrogeophysical experiments. A KCl solution was injected into the partially saturated, fractured basalt via a centrally located injection well for 76 days prior to this dilution experiment. Tap water was then injected into the injection well for 34 days. ERT was used to monitor the dilution and displacement of the KCl plume during tap water injection, and during a subsequent 62-day monitoring period. Data were collected between the wells and at land surface. The ERT data collected during the investigation show the spatial distribution of resistivity changes caused by the influx of diluting water. 3D images of surface ERT results delineate broad areas of increased resistivity due to dilution/displacement of the KCl plume. Cross-borehole ERT data delineate specific locations of water influx. Injection-well resistivities delineate specific locations where tap water seeped from the injection well via preferential flow paths determined by time-dependent resistivity increases at different elevations. Monitoring- well resistivities delineate specific fracture locations and clustered areas of resistivity changes due to the dilution and displacement of the KCl solution. The experimental results presented herein illustrate the application of combined ERT methods to delineate spatially distributed dilution in fractured rock.

Nimmer, R. E.; Osiensky, J. L.; Binley, A. M.; Sprenke, K. F.; Williams, B. C.

2006-12-01

55

Performance of a Variable Conductance Heat Pipe Heat Exchanger.  

National Technical Information Service (NTIS)

The primary objective of the work is to evaluate the performance of an air to air variable conductance heat pipe heat exchanger (VCHPHX). This type of heat exchanger is of particular interest to the commercial aircraft industry because of its unique contr...

P. D. Chancelor

1983-01-01

56

3D slicing of radiogenic heat production in Bahariya Formation, Tut oil field, North-Western Desert, Egypt.  

PubMed

A 3D block of radiogenic heat production was constructed from the subsurface total gamma ray logs of Bahariya Formation, Western Desert, Egypt. The studied rocks possess a range of radiogenic heat production varying from 0.21 ?Wm(-3) to 2.2 ?Wm(-3). Sandstone rocks of Bahariya Formation have higher radiogenic heat production than the average for crustal sedimentary rocks. The high values of density log of Bahariya Formation indicate the presence of iron oxides which contribute the uranium radioactive ores that increase the radiogenic heat production of these rocks. The average radiogenic heat production produced from the study area is calculated as 6.3 kW. The histogram and cumulative frequency analyses illustrate that the range from 0.8 to 1.2 ?Wm(-3) is about 45.3% of radiogenic heat production values. The 3D slicing of the reservoir shows that the southeastern and northeastern parts of the study area have higher radiogenic heat production than other parts. PMID:23291561

Al-Alfy, I M; Nabih, M A

2012-12-20

57

Heat conductivity of the DNA double helix  

NASA Astrophysics Data System (ADS)

Thermal conductivity of isolated single molecule DNA fragments is of importance for nanotechnology, but has not yet been measured experimentally. Theoretical estimates based on simplified (1D) models predict anomalously high thermal conductivity. To investigate thermal properties of single molecule DNA we have developed a 3D coarse-grained (CG) model that retains the realism of the full all-atom description, but is significantly more efficient. Within the proposed model each nucleotide is represented by six particles or grains; the grains interact via effective potentials inferred from classical molecular dynamics (MD) trajectories based on a well-established all-atom potential function. Comparisons of 10 ns long MD trajectories between the CG and the corresponding all-atom model show similar root-mean-square deviations from the canonical B-form DNA, and similar structural fluctuations. At the same time, the CG model is 10 to 100 times faster depending on the length of the DNA fragment in the simulation. Analysis of dispersion curves derived from the CG model yields longitudinal sound velocity and torsional stiffness in close agreement with existing experiments. The computational efficiency of the CG model makes it possible to calculate thermal conductivity of a single DNA molecule not yet available experimentally. For homogeneous (polyG-polyC) DNA, the estimated conductivity coefficient is 0.3 W/mK which is half the value of thermal conductivity for water. This result is in stark contrast with estimates of thermal conductivity for simplified, effectively 1D chains (“beads on a spring”) that predict anomalous (infinite) thermal conductivity. Thus, the full 3D character of DNA double-helix retained in the proposed model appears to be essential for describing thermal properties of DNA at a single molecule level.

Savin, Alexander V.; Mazo, Mikhail A.; Kikot, Irina P.; Manevitch, Leonid I.; Onufriev, Alexey V.

2011-06-01

58

Three dimensional electrical conductivity model of the Northwestern US derived from 3-D inversion of USArray magnetotelluric data  

NASA Astrophysics Data System (ADS)

Long period (10-20,000 s) magnetotelluric (MT) data are being acquired in a series of temporary arrays deployed across the continental United States through the EMScope component of EarthScope. MT deployments in 2006-2011 have acquired data at 325 sites on an approximately regular grid, with the same nominal spacing as the USArray broadband seismic transportable array (~70 km). The MT sites span a rectangular area from NW Washington to NW Colorado. Here we present results of a 3-D inversion of the full data set. A number of conductive and resistive features appear consistently in the crust and upper mantle in essentially all of a large suite of 3-D inverse solutions. Extensive areas of high conductivity are found in the lower crust (up to a depth of ~ 40 km) beneath the Basin & Range in southeastern Oregon, as imaged by Patro and Egbert (2008). In our new model, this feature extends further to the south and to the east, where it merges with somewhat deeper (uppermost mantle) conductivities beneath the Yellowstone-Snake River Plain. This deeper feature, which extends from Yellowstone to the SW into northeastern Nevada, coincides with the track of the Yellowstone hotspot discussed e.g., in Smith et. al. (2008). The lower crust and the uppermost mantle in the northeastern part of the domain, covering the area from eastern Washington to Montana and continuing south to Wyoming, is generally resistive, with a few localized exceptions. This resistive zone coincides with high velocities discussed and interpreted, e.g., by Yang et. al. (2008) as thick, stable Proterozoic lithosphere. A number of large-scale anomalous features also appear consistently in the upper mantle, at depths of ~ 50 km to 300 km. Most striking is a zone of high resistivity on the western edge of the domain, beneath western Oregon, Washington and northern California in the area occupied by oceanic lithosphere of the Juan de Fuca Plate, which has subducted beneath the relatively more conductive continental mantle. Another striking feature is a layer of relatively high conductivity at an average depth of ~ 170 km extending from the back-arc of the subduction zone to cover almost the entire eastern portion of the model domain. We interpret this layer as the electrical asthenosphere. The inferred asthenosphere shallows significantly to the west, rising to very shallow depths in the back-arc, and appearing to connect into high conductivities in the upper mantle (and lower crust) found beneath the Cascade arc. Shallow back-arc conductivities are highest in Washington state, where conductivities peak near a depth of ~ 70 km and continue dipping to the SE, ultimately connecting into the broader asthenospheric conductive layer. Overall this anomaly is consistent with models suggesting the presence of shallow convecting asthenosphere in the Washington back-arc. Two elliptical "holes", with locally higher resistivities, appear in the broad asthenospheric conductor. Interestingly, one of these encircles the modern Yellowstone caldera, centered near where slow seismic anomalies have been interpreted as evidence for a deep mantle plume (e.g., Yuan and Dueker, 2005). The second, less pronounced asthenospheric "hole" lies beneath the border between Idaho and Nevada.

Meqbel, N. M.; Egbert, G. D.; Kelbert, A.

2011-12-01

59

Analysis of induction heating eddy current distribution based on 3D FEM  

Microsoft Academic Search

In some applications, travelling wave induction heating (TWIH) could make this kind of heating more profitable in comparison with other known systems. In this paper a three-dimensional single-coil model of transverse flux induction heating inductors (TFIH) and TWIH has been simulated by ANSYS. The different eddy current densities in the metal strip also have been analyzed when the circle loop

Wang Youhua; Wang Junhua; Li Jiangui; Li Haohua

2008-01-01

60

Testing Nonuniform Heating RTV-Type Models of Coronal Loops with 3D Differential Emission Measure Tomography  

NASA Astrophysics Data System (ADS)

In non-uniform RTV-type loop models, the heating rate is at its maximum at the loop footpoints and decreases exponentially according to the heating scale height h. Here we use a potential field source surface model to generate the loop structures. Then we trace the temperature from 3D Differential Emission Measure Tomography (DEMT) along the loop to get the temperature profile. We will compare this temperature profile with that given by RTV-type models. This is repeated for hundreds of loops and statistical descriptions of the results are given.

Huang, Z.; Frazin, R. A.; Manchester, W. B.

2010-12-01

61

EFFECTS OF GROUNDWATER FLOW DIRECTION ON PERFORMANCE OF GROUND HEAT EXCHANGER BOREFIELD IN GEOTHERMAL HEAT PUMP SYSTEMS USING 3-D FINITE DIFFERENCE METHOD  

Microsoft Academic Search

The effects of groundwater direction on performance of geothermal heat pump systems were analyzed using a 3-D finite difference method with rectangular meshes. Each borehole was approximated by a square column with the actual circular borehole section circumscribing the approximated square section. The fluid temperatures inside each borehole were calculated by discretizing borehole vertically into different segments. Simulations made on

C K Lee; H N Lam

2007-01-01

62

muTHETA: Simulation Program for 3D Fluid and Heat Flow in Porous Media.  

National Technical Information Service (NTIS)

MuTHETA is a computer simulation model for 3-dimensional fluid and heat flow in porous media. The numerical solution is based on a finite difference approximation (FDM). For convective heat transport, an upwind scheme is used. The program code comprises a...

M. T. Kangas P. D. Lund

1989-01-01

63

Regional Hydraulic Conductivity Field Inferred From Joint Calibrations of 3-D Groundwater Flow and 4He Transport Models  

Microsoft Academic Search

The conceptual and practical gains achieved by expanding a 2-D finite element model [Castro and Goblet, 2003] to a true 3-D one through an application in the Carrizo aquifer and surrounding formations in southwestern Texas are investigated through a series of groundwater flow and 4He transport simulations. Such a 3-D model represents 4 formations, covers a surface area of ˜7000

M. C. Castro; D. Patriarche; P. Goblet

2004-01-01

64

Single-mode heat conduction by photons.  

PubMed

The thermal conductance of a single channel is limited by its unique quantum value G(Q), as was shown theoretically in 1983. This result closely resembles the well-known quantization of electrical conductance in ballistic one-dimensional conductors. Interestingly, all particles-irrespective of whether they are bosons or fermions-have the same quantized thermal conductance when they are confined within dimensions that are small compared to their characteristic wavelength. The single-mode heat conductance is particularly relevant in nanostructures. Quantized heat transport through submicrometre dielectric wires by phonons has been observed, and it has been predicted to influence cooling of electrons in metals at very low temperatures due to electromagnetic radiation. Here we report experimental results showing that at low temperatures heat is transferred by photon radiation, when electron-phonon as well as normal electronic heat conduction is frozen out. We study heat exchange between two small pieces of normal metal, connected to each other only via superconducting leads, which are ideal insulators against conventional thermal conduction. Each superconducting lead is interrupted by a switch of electromagnetic (photon) radiation in the form of a DC-SQUID (a superconducting loop with two Josephson tunnel junctions). We find that the thermal conductance between the two metal islands mediated by photons indeed approaches the expected quantum limit of G(Q) at low temperatures. Our observation has practical implications-for example, for the performance and design of ultra-sensitive bolometers (detectors of far-infrared light) and electronic micro-refrigerators, whose operation is largely dependent on weak thermal coupling between the device and its environment. PMID:17093446

Meschke, Matthias; Guichard, Wiebke; Pekola, Jukka P

2006-11-01

65

Heat Conduction in Novel Electronic Films  

NASA Astrophysics Data System (ADS)

Heat conduction in novel electronic films influences the performance and reliability of micromachined transistors, lasers, sensors, and actuators. This article reviews experimental and theoretical research on heat conduction in single-crystal semiconducting and superconducting films and superlattices, polycrystalline diamond films, and highly disordered organic and oxide films. The thermal properties of these films can differ dramatically from those of bulk samples owing to the dependence of the material structure and purity on film processing conditions and to the scattering of heat carriers at material boundaries. Predictions and data show that phonon scattering and transmission at boundaries strongly influence the thermal conductivities of single-crystal films and superlattices, although more work is needed to resolve the importance of strain-induced lattice defects. For polycrystalline films, phonon scattering on grain boundaries and associated defects causes the thermal conductivity to be strongly anisotropic and nonhomogeneous. For highly disordered films, preliminary studies have illustrated the influences of impurities on the volumetric heat capacity and, for the case of organic films, molecular orientation on the conductivity anisotropy. More work on disordered films needs to resolve the interplay among atomic-scale disorder, porosity, partial crystallinity, and molecular orientation.

Goodson, Kenneth E.; Ju, Y. Sungtaek

1999-08-01

66

Modeling a Printed Circuit Heat Exchanger with RELAP5-3D for the Next Generation Nuclear Plant  

SciTech Connect

The main purpose of this report is to design a printed circuit heat exchanger (PCHE) for the Next Generation Nuclear Plant and carry out Loss of Coolant Accident (LOCA) simulation using RELAP5-3D. Helium was chosen as the coolant in the primary and secondary sides of the heat exchanger. The design of PCHE is critical for the LOCA simulations. For purposes of simplicity, a straight channel configuration was assumed. A parallel intermediate heat exchanger configuration was assumed for the RELAP5 model design. The RELAP5 modeling also required the semicircular channels in the heat exchanger to be mapped to rectangular channels. The initial RELAP5 run outputs steady state conditions which were then compared to the heat exchanger performance theory to ensure accurate design is being simulated. An exponential loss of pressure transient was simulated. This LOCA describes a loss of coolant pressure in the primary side over a 20 second time period. The results for the simulation indicate that heat is initially transferred from the primary loop to the secondary loop, but after the loss of pressure occurs, heat transfers from the secondary loop to the primary loop.

Not Available

2010-12-01

67

Heat Conductivity of Polyatomic and Polar Gases  

Microsoft Academic Search

The formal kinetic theory of Wang Chang and Uhlenbeck and of Taxman has been used to derive explicit expressions for the heat conductivity of polyatomic and polar gases. By systematic inclusion of terms involving inelastic collisions the usual modified Eucken expression is derived as a first approximation, and as a second approximation an expression involving the relaxation times for various

E. A. Mason; L. Monchick

1962-01-01

68

Control of faults on the 3D coupled fluid and heat transport in a geothermal site (Gross Schönebeck, NE-German Basin)  

NASA Astrophysics Data System (ADS)

Studies that quantify the influence of faults on the fluid and heat transfer in 3D are still sparse. Faults have a significant impact on physical processes controlling heat transfer and fluid motion in the subsurface as they disturb the conformal succession of geological layers. Depending on their hydraulic properties, faults can act either as preferential pathways or as barriers to fluid flow (Barton et al. 1995). It is important to understand the role of faults and their impact on the thermal field for exploitation of geothermal energy. We improved an existing 3D structural model of the geothermal site "Gross Schönebeck" (Moeck et al. 2005) to carry out coupled fluid and heat transfer simulations. The coupled non-linear partial differential equations describing fluid flow and heat transport in a saturated porous medium are numerically solved by the finite element software FEFLOW° (Diersch, 2002). Simulation results are validated with borehole data. The geological model covers an area of 55 x 50 km. It integrates 18 sedimentary layers of Carboniferous to Quaternary age and reaches down to 5 km depth. An up to 1200 m thick Upper Permian (Zechstein) salt layer decouples two fault systems. We focus on the subsalt fault system which comprises the reservoir target zone and which includes major NW-SE and minor NE-SW trending faults cutting the lower part of the model. The major intersecting faults of the subsalt system are integrated as vertical discrete elements within the numerical model. By discrimination of critically stressed and extensional faults within the current stress field, the hydraulic conductivity of the faults is assessed (Moeck et al. 2009). The impact of the main fault characterising parameters, - the permeability and effective width of the fault-, are investigated by sensitivity analyses. We present outcomes from these simulations by comparing them with results from conductive and coupled fluid and heat transfer simulations obtained from models that do not integrate faults. The results pioneer in that they treat the fault-induced transport of fluid and heat in 3D. We find that faults can strongly alter the fluid regime as well as the temperature evolution in response to their contrasting hydraulic properties with respect to the surrounding matrix.

Cherubini, Y.; Cacace, M.; Scheck-Wenderoth, M.

2011-12-01

69

3-D TRANSIENT SIMULATION OF A FLAT CAPPILARY HEAT PIPE VIA AN INTERFACE TRACKING METHOD  

Microsoft Academic Search

In capillary and micro heat pipes the internal porous media is replaced by a capillary groove, yielding a meniscus formed by the liquid phase. The meniscus height varies along the groove length, from the condenser section to the evaporator section, and the difference between the pressures in each extremity is responsible for pumping the liquid. Such devices have been employed

H. A. Machado

70

APPLICATION OF A 3-D HEAT FLOW MODEL TO TREAT LASER DRILLING OF CARBON FIBRE COMPOSITES  

Microsoft Academic Search

Fine holes have been laser drilled in thin sheets of metal and of carbon fibre-reinforced thermoplastic. A numerical finite difference heat flow model has been developed, allowing prediction of the hole size and shape, for given irradiation conditions. Good general agreement is observed between measured and predicted hole dimensions, for a range of cases. The major source of error is

CF Cheng; YC Tsui; TW Clyne

71

PIPE. Heat Transfer and Friction-Factor Methods Turbulent Flow Inside Pipes 3d Rough  

SciTech Connect

Three-dimensional roughened internally enhanced tubes have been shown to be one of the most energy efficient for turbulent, forced convection applications. However, there is only one prediction method presented in the open literature and that is restricted to three-dimensional sand-grain roughness. Other roughness types are being proposed: hemispherical sectors, truncated cones, and full and truncated pyramids. There are no validated heat-transfer and friction-factor prediction methods for these different roughness shapes that can be used in the transition and fully rough region. This program calculates the Nusselt number and friction factor values, for a broad range of three-dimensional roughness types such as hemispherical sectors, truncated cones, and full and truncated pyramids. Users of this program are heat-exchangers designers, enhanced tubing suppliers, and research organizations or academia who are developing or validating prediction methods.

Taylor, R.P.; Hodge, B.K. [Mississippi State University, MS (United States)

1992-02-01

72

3-D numerical modeling of heat transfer between two sliding bodies: temperature and thermal contact resistance  

Microsoft Academic Search

A three-dimensional numerical model using the finite volume method was developed to calculate the steady-state temperatures and the thermal contact resistance between two sliding bodies: one is rough and stationary, the other is smooth and moving at a velocity V. The roughness is represented by square-shaped asperities characterized by a parameter ?. Heat transfers through interstitial gaps are not taken

B. Salti; N. Laraqi

1999-01-01

73

Characteristics of divertor heat and particle deposition with intrinsic and applied 3-D fields in NSTX H-mode plasmas  

SciTech Connect

Divertor heat and particle flux profiles are modified by externally imposed non-axisymmetric magnetic perturbations in the National Spherical Torus Experiment. The applied 3-D field causes strike point splitting that is represented as local peaks and valleys in the divertor profiles. The plasma response in an ideal perturbed equilibrium approach was included in the field line tracing by taking account of the B-field generated by the plasma current up to a certain fraction of normalized flux inside the separatrix and being superposed to the vacuum field. The inclusion of this type of plasma response does not significantly affect the location and spacing of the split strike points at the divertor surface. A modest level of divertor profile modification is found to occur even without the application of 3-D fields in certain high triangularity (delta = 0.65-0.8) discharges, with the location of local peaks and valleys same before and after the application. The intrinsic error field from the non-circularity of PF5 coil is known to have primarily n = 3 component in NSTX and was modeled to be included in the vacuum field line tracing. The produced puncture plot of the field line along with the connection length profile shows that the radial location of local peaks agrees well with the measurement, identifying intrinsic error field as a possible source of intrinsic strike point splitting. The radial location of local peaks in the profiles during the triggered ELM by the applied n = 3 field is the same before and after the 3-D field application. This shows that the heat flux from the triggered ELMs appears to follow the imposed n = 3 field structure.

Ahn, J.W. [Oak Ridge National Laboratory (ORNL); Canik, John [ORNL; Maingi, Rajesh [ORNL; Gray, Travis K [ORNL; Lore, Jeremy D [ORNL; McLean, Adam G [ORNL; Park, J.-K. [Princeton Plasma Physics Laboratory (PPPL); Roquemore, A. L. [Princeton Plasma Physics Laboratory (PPPL); Soukhanovskii, V. A. [Lawrence Livermore National Laboratory (LLNL)

2011-01-01

74

Geothermal heat flux anomaly due to a 3D prismoid situated in the second layer of a three-layered Earth  

NASA Astrophysics Data System (ADS)

We present mathematical modelling of the stationary geothermal field for the three-layered earth which includes a three-dimensional perturbing body below the first layer (over the halfspace substratum). The unperturbed temperature field corresponds to the uniform vertical heat flux. The perturbing body is in the form of 3D prismoid with sloping side faces, while its upper and lower face are rectangles at the planes z = z1, z2. The theoretical formulae are based on the generalized theory of the double-layer potential and boundary integral equation (BIE). Special attention is paid to the quadrilateral prismoids bounded by planar skew faces. The numerical calculations were performed for the 3D prismoids (blocks), the thermal conductivity of which was greater than that in the ambient second layer, while the upper face of the prismoid may be in contact with the upper layer and the lower face may touch the bottom halfspace. Numerous graphs are shown for the disturbance of the temperature and heat flow distribution on the surface of the Earth or inside all three layers.

Hvoždara, Milan; Majcin, Dušan

2013-03-01

75

Monte Carlo solution of anisotropic heat conduction  

SciTech Connect

Based on the fixed-step random walk procedure a Monte Carlo algorithm for the solution of anisotropic heat conduction is presented. It is shown that the Monte Carlo solution is attainable only for a specified range of solid thermal conductivities. It is also illustrated that by following two simple clues considerable reduction in computation time may be achieved. Finally, steady-state temperature distribution, obtained by the Monte Carlo calculations, is presented for a two-dimensional anisotropic solid having simple geometry and boundary conditions.

Kowsary, F.; Arabi, M.

1999-11-01

76

3D model for laser heating of a heterogeneous turbid medium  

NASA Astrophysics Data System (ADS)

In order to better understand the interaction of laser light with biological tissue, a light-transport model is integrated with a heat-transport model. The outputs include temperature as a function of position and time, given the illumination conditions and the optical and thermal properties of the tissue. The optical portion of the algorithm is based on the theory of radiative transfer through a turbid medium. Our computer program models multiple scattering in three dimensions using seven discrete irradiances which approximate the radiative transport equation. The distribution of absorbed light in the tissue is calculated and used as the source term in a discrete approximation to the thermal diffusion equation. Recently, we have been using the model to better understand the laser-heating of heterogeneous tissue. Rather than modeling a homogeneous mixture having properties given by weighted averages of those of tissue and blood, we model this medium as an array of blood vessels in a bloodless dermis background. We are currently analyzing temporal and spatial variations of temperature in homogeneous and heterogeneous tissue having identical blood concentrations. A particular application of the model is to the study of laser coagulation tonsillectomy.

Rossacci, Michael J.; Dimarzio, Charles A.; Lindberg, Scott C.; Pankratov, Michail M.

1997-05-01

77

3D crustal-scale heat-flow regimes at a developing active margin (Taranaki Basin, New Zealand)  

NASA Astrophysics Data System (ADS)

The Taranaki Basin in the west of New Zealand's North Island has evolved from a rifted Mesozoic Gondwana margin to a basin straddling the Neogene convergent Australian-Pacific plate margin. However, given its proximity to the modern subduction front, Taranaki Basin is surprisingly cold when compared to other convergent margins. To investigate the effects of active margin evolution on the thermal regime of the Taranaki Basin we developed a 3D crustal-scale forward model using the petroleum industry-standard basin-modelling software Petromod™.The crustal structure inherited from Mesozoic Gondwana margin breakup and processes related to modern Hikurangi convergent margin initiation are identified to be the main controls on the thermal regime of the Taranaki Basin. Present-day surface heat flow across Taranaki on average is 59 mW/m2, but varies by as much as 30 mW/m2 due to the difference in crustal heat generation between mafic and felsic basement terranes alone. In addition, changes in mantle heat advection, tectonic subsidence, crustal thickening and basin inversion, together with related sedimentary processes result in variability of up to 10 mW/m2. Modelling suggests that increased heating of the upper crust due to additional mantle heat advection following the onset of subduction is an ongoing process and heating has only recently begun to reach the surface, explaining the relatively low surface heat flow. We propose that the depth of the subducted slab and related mantle convection processes control the thermal and structural regimes in the Taranaki Basin. The thermal effects of the subduction initiation process are modified and overprinted by the thickness, structure and composition of the lithosphere.

Kroeger, K. F.; Funnell, R. H.; Nicol, A.; Fohrmann, M.; Bland, K. J.; King, P. R.

2013-04-01

78

Heat conduction of laser vanadate crystals  

SciTech Connect

The heat conduction of laser vanadate crystals GdVO{sub 4} and YVO{sub 4} and their solid solutions is measured in the temperature interval from 50 to 350 K. Mixed rare-earth vanadates have the common chemical formula Re'{sub 1-x}Re''{sub x}VO{sub 4}, where Re' and Re'' are two or more types of ions from a series La{sup 3+}, Pr{sup 3+}, Nd{sup 3+}, Sm{sup 3+}, Eu{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}, Ho{sup 3+}, Er{sup 3+}, Tm{sup 3+}, Yb{sup 3+}, Lu{sup 3+}, Sc{sup 3+}, Y{sup 3+}. The heat conduction of Nd:YVO{sub 4} measured at room temperature proved to be more than twice higher than that reported in the literature and in certificate characteristics of laser Nd:YVO{sub 4} elements manufactured by numerous commercial companies. The empirical dependences of the heat conduction along the crystallographic axes <100> and <001> on the composition of rare-earth vanadates Re'{sub 1-x}Re''{sub x}VO{sub 4}, are obtained in the temperature interval from 200 to 350 K. (active media)

Zagumennyi, A I; Zavartsev, Yu D; Kutovoi, S A; Shcherbakov, I A [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Popov, P A [Acad. I. G. Petrovskii Bryansk State University, Bryansk (Russian Federation); Zerouk, F [Zecotek Medical Systems Ltd (Singapore)

2008-03-31

79

A Domain Decomposition Based Algorithm For Non-linear 2D Inverse Heat Conduction Problems  

Microsoft Academic Search

Inverse heat conduction problems (IHCPs) appear in many important scientic and technological elds. Hence analysis, design, implementation and testing of inverse algorithms are also of great scientic and technological interest. The numerical simulation of 2-D and 3-D inverse (or even direct) problems involves a considerable amount of computation. Therefore, the investigation and exploitation of parallel properties of such algorithms are

Charaka J. Palansuriya; Choi-Hong Lai; Constantinos S. Ierotheou; Koulis A. Pericleous

80

Exploring Geothermal Energy Potential in Ireland through 3-D Geophysical-Petrological Modelling of Surface Heat-Flow and Crustal and Upper-Mantle Structure  

NASA Astrophysics Data System (ADS)

Little is known of Ireland's deep, low-enthalpy geothermal resources and the potential for space heating and/or electricity generation based on geothermal energy to displace Ireland's significant reliance on carbon-based fuels. IRETHERM (www.iretherm.ie) is a four-and-a-half year, all-island, academic-government-industry collaborative project, initiated in 2011, with the overarching objective of developing a strategic and holistic understanding of Ireland's geothermal energy potential through integrated modelling of new and existing geophysical and geological data. One of the challenges in searching for deep geothermal resources in the relatively unexplored setting of Ireland lies in identifying those areas most likely to support significantly elevated temperatures at depth. Available borehole data, although sparse and clustered around areas of mineral and hydrocarbon interest, suggest a marked regional increase in surface heat-flow across Ireland, from ~40 mW/m2 in the south to >80 mW/m2 in the north. The origins of both the observed regional heat-flow trend and local temperature anomalies have not been investigated and are not currently understood. Although variations in the structure of the crust and lithosphere have been revealed by a number of active-source seismic and teleseismic experiments, their effects on surface heat-flow have not been modelled. Bulk 3-D variation in crustal heat-production across Ireland, which may contribute significantly to the observed regional and local temperature variations, has also not been determined. We investigate the origins of Ireland's regional heat-flow trend and regional and local temperature variations using the software package LitMod. This software combines petrological and geophysical modelling of the lithosphere and sub-lithospheric upper mantle within an internally consistent thermodynamic-geophysical framework, where all relevant properties are functions of temperature, pressure and chemical composition. The major regional controls on surface heat-flow and crustal temperatures are (a) crustal thickness, (b) crustal heat-production and (c) lithospheric thickness. These unknown geological variables are modelled in LitMod3D against geophysical observations at surface - heat-flow, topography, gravity and geoid data - to identify a crustal and lithospheric-mantle model that satisfies and accounts for all the observations at surface (most importantly in our context, heat-flow). We present a range of 3-D crustal and lithospheric-mantle models that satisfy all observable constraints and account for the regional sources of heat in Ireland. These models provide the basis for isolating local temperature anomalies and for assessing the extent to which local lithological variation in heat-production and thermal conductivity affects the distribution of temperatures in our target depth range of 2000 - 6000 m. Significant, well defined temperature anomalies that emerge from this work will be targeted for further assessment during IRETHERM's planned field program of magnetotelluric and controlled source electromagnetic surveys.

Fullea, J.; Muller, M. R.; Jones, A. G.

2012-04-01

81

Silicon nanopillars based 3D stacked microchannel heat sinks concept for enhanced heat dissipation applications in MEMS packaging  

Microsoft Academic Search

In this paper, a novel design of silicon micro\\/nanopillars based multilayer water-cooled heat sink is presented, which enhances the overall thermal performance of electronics\\/MEMS components by a noteworthy amount. Heat dissipation rate of electronic devices is significantly increased by the silicon micro\\/nanopillars, which are grown in the microchannels by utilizing the micromasking effect in deep reactive ion etching. Due to

Pradeep Dixit; Nay Lin; Jianmin Miao; Wai Kwan Wong; Teo Kiat Choon

2008-01-01

82

Analytical, numerical and analog methods in problems of heat conductivity  

Microsoft Academic Search

Consideration is given to heat-conduction problems for regions of complex geometry, nonlinear problems of heat conduction, fluid flow, filtration and oscillations, and the optimization of thermal processes. Particular papers are presented on the solution of the first and second boundary value problems of heat conduction for the outside of an elliptical cylinder, determination of the temperature field of a heat-radiating

I. A. Lukovskii

1977-01-01

83

Turbulent Convection Heat Transfer in Longitudinally Conducting, Externally Finned Pipes  

Microsoft Academic Search

A numerical investigation is conducted of turbulent convection in a longitudinally conducting, externally finned pipe. Results reveal significant enhancement in heat transfer due to finning. The heat transfer rate to the fluid increases with increasing thermal conductivity of the pipe wall, with increasing values of the external heat transfer coefficient, and with decreasing interfin spacing. Heat transfer is underestimated by

F. Moukalled; J. Kasamani; S. Acharya

1992-01-01

84

Evaluation of the thermal and hydraulic performances of a very thin sintered copper flat heat pipe for 3D microsystem packages  

Microsoft Academic Search

The reported research work presents numerical studies validated by experimental results of a flat micro heat pipe with sintered copper wick structure. The objectives of this research were to produce and demonstrate the efficiency of the passive cooling technology (heat pipe) integrated in a very thin electronic substrate that is a part of a multifunctional 3-D electronic package. The enhanced

Slaska Tzanova; Lora Kamenova; Yvan Avenas; Christian Schaeffer

2008-01-01

85

Role of hydrophobic hydration in protein stability: a 3D water-explicit protein model exhibiting cold and heat denaturation.  

PubMed

We investigate the microscopic mechanism of cold and heat denaturation using a 3D lattice model of a hydrated protein in which water is represented explicitly. The water model, which incorporates directional bonding and tetrahedral geometry, captures many aspects of water thermodynamics and properly describes hydrophobic hydration around apolar solutes because the hydrogen bonding rules in the model were gleaned from off-lattice atomistic simulations of water around representative protein structures. By incorporating local chain stiffness in the protein model, a homopolymer can fold into a ?-hairpin. It is shown that the homopolymer can be folded by either attractive interactions between the monomers or as a direct consequence of the entropic cost of forming interfacial hydrogen bonds in the solvent. However, cold denaturation is not observed if the collapse transition is induced by intramolecular attractions. We further find that it is the changes in hydrophobic hydration with decreasing temperature that drive cold unfolding and that the overall process is enthalpically driven, whereas heat denaturation is entropically driven. PMID:22725973

Matysiak, Silvina; Debenedetti, Pablo G; Rossky, Peter J

2012-07-10

86

Study on the non-fourier heat conduction.  

National Technical Information Service (NTIS)

Heat conduction problem in many engineering situations has been analyzed by using the heat conduction equation based on the classical Fourier model. However, Fourier's law implies that any thermal disturbances on a body is instantaneously felt throughout ...

K. Woo-Seung

1994-01-01

87

Digital simulation of transient heat conduction with polynomial variable thermal conductivity and specific heat  

NASA Astrophysics Data System (ADS)

The transient thermal responses observed in a slab, the thermal conductivity and specific heat of which showed polynomial temperature dependence, were simulated digitally by means of the network method. A general network model for this process is proposed regardless of the polynomial degree, which includes initial and boundary conditions. With this network model and using the electrical circuit simulation program PSPICE, time-dependent temperature and heat flow profiles at any location can be obtained. This approach allows us to solve this conduction problem at a moderate cost in computer time, without the necessity of considering numerical and programming aspects. The results are compared with those obtained by other methods for a particular case.

González-Fernández, C. F.; Alhama, F.; Alarcón, M.; López-Sánchez, J. F.

1998-06-01

88

The Tonga-Vanuatu Subduction Complex -- a Self-Optimized 3D Slab-Slab-Mantle Heat Pump  

NASA Astrophysics Data System (ADS)

Recently published geophysical and geochemical data and increasingly actualistic free subduction models prompted a fresh look at 2 classics hinting, in combination, that a coupled 3D slab-slab-upper mantle interaction (Scholz and Campos, 1995; full citations at URL below) might power the prodigious surface heat dissipation (Lagabrielle et al., 1997) characterizing one of Earth's most remarkable tectonomagmatic systems, the Tonga-Vanuatu Subduction Complex (TVSC). The 3D TVSC includes (1) the kinematically, magmatically, and bathymetrically distinct North Tonga (NT, 14-26° S) and South Vanuatu (SV, 16-23° S) trenches and slabs, (2) the shared NT-SV backarc, and (3) entrained mobile upper mantle (MUM). That Earth's greatest convergence, rollback, and spreading rates; most disseminated spreading (the North Fiji Basin (NFB) ridge swarm); and greatest concentration of aggregate active ridge length coincide in a 1,500 km TVSC can't be accidental. To the north and south, the respective active NT and SV trenches swing abruptly 90° counterclockwise into continuity with the Vitiaz and Hunter fossil trenches, both active in the Late Miocene but now sinistral strike-slip loci standing over long exposed PA and AU slab edges. These 2 active-fossil trench pairs bracket a hot, shallow and geophysically and geochemically exceptional TVSC interior consisting of 2 rapidly spreading backarcs set back-to-back in free sublithospheric communication: The Lau-Havre NT backarc on the east and the ridge-infested SV backarc (NFB) on the west. The NFB and adjacent North Fiji Plateau make up the unplatelike New Hebrides-Fiji Orogen (Bird, 2003). As in the western Aleutians, the NT-Vitiaz and SV-Hunter subduction-to-strike-slip transitions (SSSTs) stand above toroidal fluxes of hot, dry PA and AU MUM driven along-trench and around the free NT and SV slab edges from subslab to supraslab regions by dynamic pressure gradients powered by slab free-fall and induced viscous couplings. These edge flows must converge and mix beneath the shared TVSC backarc, which must then shed a huge advected subslab heat load by maximizing ridge length in the area available. Found at both SSSTs are adakites indicative of a TVSC source laced with slab-edge melt and boninites consistent with flux- melting of hot, dry subslab MUM on entry to the supraslab wedge. Isotopics reveal widespread source mixing of Pacific and Indian MOR end-members. Diverging NT and VS trenches rotate clockwise at extremely high rates about pinning points at and Euler poles near trench-floater intercepts: Louisville Ridge on PA, and West Torres Plateau-D'Entrecasteaux Ridge on AU. In this configuration, the spinning, free-falling NT and SV slabs form a highly coupled self-organized gravity-powered pump pulling hot subslab MUM beneath the TVSC with enough left-over head to power severe transition zone buckling of an 80+ Ma NT (PA) slab also actively extending toward its free edge. Several nonlinear couplings (e.g., temperature-dependent viscosity and slab damage at tightening upper hinges) feedback positively to pump efficiency. The TVSC is but one possible slab-mantle pump partaking of the strong self-optimizing tendency characteristic of all natural flow systems (e.g., Bejan and Lorente, 2006). Slab-mantle pump natural history is now under investigation, as such pumps may have allowed a shrinking post-Pangean Pacific with an unrelenting sublithospheric room problem to relieve itself of excess MUM by making efficient use of available circum-Pacific slab curtain porosity -- a commodity that may have been in very short supply through most of the Cretaceous.

McCreary, J. A.

2008-12-01

89

Low temperature bonding of 30um pitch micro bump interconnection for 3D IC stacking using non-conductive adhesive  

Microsoft Academic Search

For evaluating the feasibility of adhesive bonding by NCF (non-conductive film) in micro bump joints, three types of micro joints were adopted in this study. The structure of the type I micro joints was Cu\\/Ni\\/Au while that of the type II micro joints was Cu\\/Ni\\/Au micro bump joined with Cu\\/Sn solder micro bump. Both the type I and type II

Yu-Min Lin; Chau-Jie Zhan; Yu-wei Huang; Su-Ching Chung; Chia-Wen Fan; Su-Mei Chen; Yu-Lan Lu; Tai-Hong Chen

2011-01-01

90

Experimental evidence of hyperbolic heat conduction in processed meat  

Microsoft Academic Search

The objective of this paper is to present experimental evidence of the wave nature of heat propagation in processed meat and to demonstrate that the hyperbolic heat conduction model is an accurate representation, on a macroscopic level, of the heat conduction process in such biological material. The value of the characteristic thermal time of a specific material, processed bologna meat,

K. Mitra; S. Kumar; A. Vedavarz; M. K. Moallemi

1995-01-01

91

Non-conductive heat transfer associated with frozen soils  

Microsoft Academic Search

The assertion that pure conductive heat transfer always dominates in cold climates is at odds with decades of research in soil physics which clearly demonstrate that non-conductive heat transfer by water and water vapor are significant, and frequently are for specific periods the dominant modes of heat transfer near the ground surface. The thermal regime at the surface represents the

Douglas L Kane; Kenneth M Hinkel; Douglas J Goering; Larry D Hinzman; Samuel I Outcalt

2001-01-01

92

Regional conductivity structures of the northwestern segment of the North American Plate derived from 3-D inversion of USArray magnetotelluric data  

NASA Astrophysics Data System (ADS)

Long period (10-20,000 s) magnetotelluric (MT) data are being acquired in a series of temporary arrays deployed across the continental United States through EMScope, a component of EarthScope, a multidisciplinary decade-long project to study the structure and evolution of the North American Continent. MT deployments in 2006-2010 have so far acquired data at 237 sites on an approximately regular grid, with the same nominal spacing as the USArray broadband seismic transportable array (~70 km), covering the Northwestern US, from the Oregon-Washington coast across the Rocky Mountains, into Montana and Wyoming. Preliminary 3-D inversion results (Patro and Egbert; 2008), based on data from the 110 westernmost “Cascadia” sites collected in the first two years, revealed extensive areas of high conductivity in the lower crust beneath the Northwest Basin and Range (NBR), inferred to result from fluids (including possibly partial melt at depth) associated with magmatic underplating, and beneath the Cascade Mountains, probably due to fluids released by the subducting Juan de Fuca slab. Here we extend this study, refining and further testing the preliminary results from Cascadia, and extending the inversion domain to the East, to include all of the EarthScope data. Although site spacing is very broad, distinct regional structures are clearly evident even in simple maps of apparent resistivity, phase and induction vectors. For the 3-D inversion we are using the parallelized version of our recently developed Modular Code (ModEM), which supports Non-Linear Conjugate Gradient and several Gauss-Newton type schemes. Our initial 3-D inversion results using 212 MT sites, fitting impedances and vertical field transfer functions (together and separately) suggest several conductive and resistive structures which appear to be stable and required by the measured data. These include: - A conductive structure elongated in the N-S direction underneath the volcanic arc of the Cascadia subduction zone starting at a depth of about 20-30 km. - A pronounced conductive feature at or just below the base of the crust. This coincides with the NBR conductor of Patro and Egbert (2008), but our results show that this extends (and becomes even more pronounced) further to the east, where it connects with a conductive zone in the Yellowstone “hot spot” area. - Resistive crustal structure in the coast range, and beneath the Columbia Plateau, consistent with the interpretation of Humprheys (2008) that these two sections of crust represent the accreted Siletzia terrane (broken subsequently by arc volcanism). - A clear contrast between continental and oceanic mantle, with higher conductivities to depths of at least 150 km above the subducting Juan de Fuca Plate; the highest conductivities appear to be in the back arc in northern east of Washington. - Higher deep mantle conductivity to the east, in particular beneath Yellowstone. Multiple 3-D inversion and forward modeling tests will be required to verify the resolution and stability of these and other more subtle conductive and resistive structures in our 3-D models. Our efforts in this direction will be presented at the meeting.

Meqbel, N. M.; Egbert, G. D.; Kelbert, A.

2010-12-01

93

On the second harmonic electron cyclotron resonance heating and current drive experiments on T-10 and D3-D  

Microsoft Academic Search

Studies of electron cyclotron current drive at the second harmonic resonance have been performed both on the D3-D and T-10 tokamaks at injected power levels of approximately 0.5 MW. The D3-D experiment used high held launch of the extraordinary mode at an angle of 15 deg to the radial. In this experiment, with pulse lengths approximately equal to 500 msec,

J. Lohr; C. B. Forest; Y. R. Lin-Liu; T. C. Luce; R. W. Harvey; E. A. Downs; R. A. James; A. A. Bagdasarov; A. A. Borshegovskii; V. V. Chistyakov; M. M. Dremin; A. V. Gorshkov; Y. A. Gorelov; Y. V. Esipchuk; N. V. Ivanov; A. Y. Kislov; D. A. Kislov; S. E. Lysenko; A. A. Medvedev; V. Y. Mirenskii; G. E. Notkin; V. V. Parail; Y. D. Pavlov; K. A. Razumova; I. N. Roi; P. V. Savrukhin; V. V. Sannikov; A. V. Sushkov; V. M. Trukhin; N. L. Vasin; V. V. Volkov; G. G. Denisov; M. I. Petelin; V. A. Flyagin

1993-01-01

94

Methodology for comparison of inverse heat conduction methods  

Microsoft Academic Search

The inverse heat conduction problem involves the calculation of the surface heat flux from transient measured temperatures inside solids. The deviation of the estimated heat flux from the true heat flux due to stabilization procedures is called the deterministic bias. This paper defines two test problems that show the tradeoff between deterministic bias and sensitivity to measurement errors of inverse

M. Raynaud; J. V. Beck

1988-01-01

95

Conjugate forced convection–conduction heat transfer analysis of a heat generating vertical cylinder  

Microsoft Academic Search

Conjugate heat transfer by forced convection over a vertical cylinder without heat generation has been a subject of many investigations in the recent past. In the present work, the radial heat conduction along with heat generation in a vertical cylinder is considered for analysis. The steady two-dimensional conduction equation for the heat generating cylinder and steady two-dimensional laminar boundary layer

G Jilani; S Jayaraj; M Adeel Ahmad

2002-01-01

96

Heat conduction in graphite-nanoplatelet-reinforced polymer nanocomposites  

Microsoft Academic Search

Heat transport in polymer nanocomposites reinforced with graphite nanoplatelets (GNPs) is studied using high-precision thermal conductivity measurements. The resistance to heat conduction across interfaces between GNPs and the polymer matrix has a strong effect on energy transport in the nanocomposites. The thermal conductivity is observed to increase when GNPs are pretreated with nitric acid to improve interfacial bonding. The improvement

M.-T. Hung; O. Choi; Y. S. Ju; H. T. Hahn

2006-01-01

97

Characterization of a contaminated wellfield using 3D electrical resistivity tomography implemented with geostatistical, discontinuous boundary, and known conductivity constraints  

SciTech Connect

Continuing advancements in subsurface electrical resistivity tomography (ERT) are giving the method increasing capability for understanding shallow subsurface properties and processes. The inability of ERT imaging data to uniquely resolve subsurface structure and the corresponding need include constraining information remains one of the greatest limitations, and provides one of the greatest opportunities, for further advancing the utility of the method. In this work we describe and demonstrate a method of incorporating constraining information into an ERT imaging algorithm in the form on discontinuous boundaries, known values, and spatial covariance information. We demonstrate the approach by imaging a uranium-contaminated wellfield at the Hanford Site in southwestern Washington State, USA. We incorporate into the algorithm known boundary information and spatial covariance structure derived from the highly resolved near-borehole regions of a regularized ERT inversion. The resulting inversion provides a solution which fits the ERT data (given the estimated noise level), honors the spatial covariance structure throughout the model, and is consistent with known bulk-conductivity discontinuities. The results are validated with core-scale measurements, and display a significant improvement in accuracy over the standard regularized inversion, revealing important subsurface structure known influence flow and transport at the site.

Johnson, Timothy C.; Versteeg, Roelof J.; Rockhold, Mark L.; Slater, Lee D.; Ntarlagiannis, Dimitrios; Greenwood, William J.; Zachara, John M.

2012-09-17

98

Temperature distribution of a tokamak with a constant heat conductivity.  

National Technical Information Service (NTIS)

An analytical expression of the detached plasma radius in and ohmically heated tokamak plasma was obtained. The assumption was made that the (anomalous) heat conductivity is constant and independent of minor radius, r. The resultant nonlinear differential...

S. Yoshikawa

1990-01-01

99

The conduction of heat from sliding solids  

Microsoft Academic Search

Ah&act-The large scale restrictions to heat flow from two sliding solids can have a significant effect on the temperature field near the interface. It is shown that a practical system can be approximated to two semi-intinite solids whose temperatures at infinity are related to the heat flow rates through them. A number of existing semi-infinite solid solutions am generalised to

J. R. BARBER

1970-01-01

100

Superfluid heat conduction and the cooling of magnetized neutron stars  

SciTech Connect

We report on a new mechanism for heat conduction in the neutron star crust. We find that collective modes of superftuid neutron matter, called superfiuid phonons (sPhs), can influence heat conduction in magnetized neutron stars. They can dominate the heat conduction transverse to magnetic field when the magnetic field B {approx}> 10{sup 13} C. At density p {approx_equal} 10{sup 12}--10{sup 14} g/cm{sup 3} the conductivity due to sPhs is significantly larger than that due to lattice phonons and is comparable to electron conductivity at when temperature {approx_equal} 10{sup 8} K. This new mode of heat conduction can limit the surface anisotropy in highly magnetized neutron stars. Cooling curves of magnetized neutron stars with and without superfluid heat conduction show observationally discernible differences.

Cirigliano, Vincenzo [Los Alamos National Laboratory; Reddy, Sanjay [Los Alamos National Laboratory; Sharma, Rishi [Los Alamos National Laboratory; Aguilera, Deborah N [BUENOS AIRES

2008-01-01

101

Interchangeable variable conductance heat pipes for sodium-sulfur batteries  

NASA Astrophysics Data System (ADS)

Sodium-sulfur batteries can provide electrical power to satellite instrumentation operating in geosynchronous-earth-orbit (GEO) and low-earth-orbit (LEO) conditions. While on orbit, the sodium-sulfur battery requires thermal management as the battery is cycled between discharge in solar eclipse and recharge in sunlight. As the battery discharges in solar eclipse waste heat is generated and the battery requires cooling. During recharge in sunlight the battery temperature needs to be maintained above 320 C. In this Phase 1 program, Thermacore developed and demonstrated a dual titanium/cesium heat pipe to provide passive, lightweight management of the battery during orbital cycling. The dual heat pipe concept uses both constant and variable conductance heat pipes. Constant conductance heat pipes are inserted between sodium-sulfur cells. The cells radiate to the constant conductance heat pipes and this energy is transferred to a variable conductance heat pipe and radiated to deep space.

Hartenstine, John R.

1991-08-01

102

Effect of Heat Treatment Temperature on Binder Thermal Conductivities.  

National Technical Information Service (NTIS)

The effect of heat treatment on the thermal conductivities of a pitch and a polyfurfuryl alcohol binder residue was investigated. Graphites specially prepared with these two binders were used for the experiments. Measured thermal conductivities were treat...

P. Wagner

1975-01-01

103

A survey of heat conduction problems  

Microsoft Academic Search

Several forms of thermal conductivity apparatus are described which have been devised for the study of diverse materials ranging from a sheet of mica to a wall section weighing half a ton. The materials are broadly classified into four groups:(1) Materials of very low thermal conductivity, such as cold storage insulators. (2) Materials supplied in the form of thin sheets

Ezer Griffiths

1928-01-01

104

Mitigating heat dissipation and thermo-mechanical stress challenges in 3-D IC using thermal through silicon via (TTSV)  

Microsoft Academic Search

Thermal modeling of a 3-D IC stack consists of three IC layers bonded back-to-face (or face up) is performed. Significant temperature rise in the top layers is projected with the presence of dielectric isolation films between the IC layers. It is found that by inserting electrically isolated thermal through silicon via (TTSV) having Cu core and oxide liner that extends

Santhosh Onkaraiah; Chuan Seng Tan

2010-01-01

105

Heat Pipe Embedded AlSiC Plates for High Conductivity: Low CTE Heat Spreaders.  

National Technical Information Service (NTIS)

Heat pipe embedded aluminum silicon carbide (AlSiC) plates are innovative heat spreaders that provide high thermal conductivity and low coefficient of thermal expansion (CTE). Since heat pipes are two phase devices, they demonstrate effective thermal cond...

J. Weyant M. Johnson M. Occhionero S. Garner

2010-01-01

106

Comparison of some inverse heat conduction methods using experimental data  

Microsoft Academic Search

This paper compares several methods of finding the surface heat flux using transient temperature measurements inside a heat-conducting body. Experimental data is used with a known heat flux history. The methods include function specification with several future approximations, Tikhonov regularization, iterative regularization and specified functions over large time regions with Green's functions. The first three methods are used with the

A. Haji-Sheikh

1996-01-01

107

Challenges in microscale conductive and radiative heat transfer  

Microsoft Academic Search

This work addresses challenges in the emerging field of microlength scale radiative and conductive heat transfer in solids and recommends specific directions of future research. Microlength scale heat transfer involves thermal energy transport processes in which heat carrier characteristic lengths become comparable to each other or the characteristic device dimension. Identification of these characteristic lengths leads to the definition of

C. L. Tien; G. Chen

1994-01-01

108

Manufacture of high heat conductivity resistant clay bricks containing perlite  

Microsoft Academic Search

Different methods have been investigated for achieving heat insulation in the buildings. Manufacturing of high heat conductivity resistant construction materials is an important part of these research efforts. Perlite is an extremely useful material for heat insulation and 70% of the world reserves are located in Turkey. Nearly 65% of the perlite produced today is consumed by the construction industry.

?lker Bekir Topçu; Burak I??kda?

2007-01-01

109

Heat conduction equation in fractional-order derivatives  

NASA Astrophysics Data System (ADS)

Based on the heat conduction equation in fractional-order derivatives, the influence of the nonlocality of the heat conduction equation in time and space on temperature distribution in media with fractal structure is investigated. The cases of an infinite and semibounded straight line are considered.

Alkhasov, A. B.; Meilanov, R. P.; Shabanova, M. R.

2011-03-01

110

Estimation of heat conduction losses in laser cutting  

Microsoft Academic Search

Numerical models of laser cutting are essential for an improved understanding of the process. In order for the models to closely represent real physics the heat lost by conduction during cutting has to be incorporated into them. This paper outlines the details of a mathematical model that is used to estimate heat conduction losses in laser cutting by employing integral

Joseph M. Prusa; Girish Venkitachalam; Palaniappa A. Molian

1999-01-01

111

Thermal conductivity enhancement in a latent heat storage system  

Microsoft Academic Search

Latent heat storage systems especially those employing organic materials have been reported to exhibit a rather slow thermal response. This is mainly due to the relatively low thermal conductivity of organic latent heat materials. In this study, experiments were carried out to investigate a method of enhancing the thermal conductivity of paraffin wax by embedding aluminum powder in it. The

Eman-Bellah S. Mettawee; Ghazy M. R. Assassa

2007-01-01

112

Formulation of Gyarmati's principle for heat conduction equation  

NASA Astrophysics Data System (ADS)

Gyarmati's principle is formulated in various pictures for the heat conduction phenomenon in solid. Since the heat current density and the internal energy function can be given in three different pictures for heat conduction phenomena, we get the nine forms of the principle from which the heat conduction equation can be derived. This formulation has been shown using the generalized Gamma picture. In the subsequent section the principle is formulated in proper Gamma picture from which three proper pictures namely Fourier, entropy and energy follow.

Singh, P.

1980-03-01

113

Heat conductivity in relativistic systems investigated using a partonic cascade  

NASA Astrophysics Data System (ADS)

Motivated by the classical picture of heat flow, we construct a stationary temperature gradient in a relativistic microscopic transport model. Employing the relativistic Navier-Stokes ansatz, we extract the heat conductivity ? for a massless Boltzmann gas using only binary collisions with isotropic cross sections. We compare the numerical results to analytical expressions from different theories and discuss the final results. The directly extracted value for the heat conductivity can be referred to as a literature reference within the numerical uncertainties.

Greif, M.; Reining, F.; Bouras, I.; Denicol, G. S.; Xu, Z.; Greiner, C.

2013-03-01

114

Phonon Heat Conduction In A Semiconductor Nanowire  

Microsoft Academic Search

Abstract: ic phonondispersion due to spatial confinement, and (ii) change in the nonequilibrium phonondistribution due to partially diffuse boundary scattering. Numerical simulation isperformed for a silicon nanowire with boundaries characterized by different interfaceroughness. Phonon confinement and boundary scattering lead to a significant decrease ofthe lattice thermal conductivity. The value of this decrease and its interface roughnessand temperature dependence are different

Joe Zou; Alexander Balandin

2000-01-01

115

Analysis and application of variable conductance heat pipe air preheater  

Microsoft Academic Search

The heat transfer analysis of variable conductance heat pipe air preheater was carried out. The temperature transfer matrix\\u000a was obtained for the air preheater that comprises several discrete heat transfer units with same or different heat transfer\\u000a surface area in a parallel or counter flow mode. By using the temperature transfer matrix, the outlet fluid temperatures could\\u000a be easily calculated

Chengming Shi; Yang Wang; Quan Liao; Ying Yang

2011-01-01

116

INVERSE HEAT CONDUCTION PROBLEM OF SIMULTANEOUSLY ESTIMATING SPATIALLY VARYING THERMAL CONDUCTIVITY AND HEAT CAPACITY PER UNIT VOLUME  

Microsoft Academic Search

An inverse heat conduction method for simultaneously estimating spatially varying thermal conductivity and heat capacity per unit volume under the conditions of a flash method type of experiment is developed. The unknown thermal properties are assumed to vary only in the space dimension normal to the slab sample and are modeled with piecewise linear representations. Lacking in the literature are

G. P. Flach; M. N. Özi?ik

1989-01-01

117

A 3D POM-MOF composite based on Ni(??) ion and 2,2?-bipyridyl-3,3?-dicarboxylic acid: Crystal structure and proton conductivity  

NASA Astrophysics Data System (ADS)

We have succeeded in constructing a 3D POM-MOF, {H[Ni(Hbpdc)(H2O)2]2[PW12O40]·8H2O}n (H2bpdc=2,2?-bipyridyl-3,3?-dicarboxylic acid), by the controllable self-assembly of H2bpdc, Keggin-anions and Ni2+ ions based on the electrostatic and coordination interactions. Interestingly, Hbpdc- as polydentate organic ligands and Keggin-anion as polydentate inorganic ligands are covalently linked transition-metal nickel at the same time. The title complex represents a new example of introducing the metal N-heterocyclic multi-carboxylic acid frameworks into POMs chemistry. Based on Keggin-anions being immobilized as part of the metal N-heterocyclic multi-carboxylic acid framework, the title complex realizes four approaches in the 1D hydrophilic channel used to engender proton conductivity in MOFs. Its water adsorption isotherm at room temperature and pressure shows that the water content in it was 31 cm3 g-1 at the maximum allowable humidity, corresponding to 3.7 water molecules per unit formula. It exhibits good proton conductivities (10-4-10-3 S cm-1) at 100 °C in the relative humidity range 35-98%. The corresponding activation energy (Ea) of conductivity was estimated to be 1.01 eV.

Wei, Meilin; Wang, Xiaoxiang; Sun, Jingjing; Duan, Xianying

2013-06-01

118

Heat pipe embedded AlSiC plates for high conductivity - low CTE heat spreaders  

Microsoft Academic Search

Heat pipe embedded aluminum silicon carbide (AlSiC) plates are innovative heat spreaders that provide high thermal conductivity and low coefficient of thermal expansion (CTE). Since heat pipes are two phase devices, they demonstrate effective thermal conductivities ranging between 10,000 and 200,000 W\\/m-K, depending on the heat pipe length. Installing heat pipes into an AlSiC plate dramatically increases the plate's effective

J. Weyant; S. Garner; M. Johnson; M. Occhionero

2010-01-01

119

Cascade variable-conductance heat pipe (A0076)  

NASA Astrophysics Data System (ADS)

The objective is to verify the capability of a cascade variable conductance heat pipe (CVCHP) system to provide precise temperature control of long life spacecraft without the need for a feedback heater or other power sources for temperature adjustment under conditions of widely varying power input and ambient environment. Solar energy is the heat source and space the heat sink for thermally loading two series connected variable conductance heat pipes. Electronics and power supply equipment requirements are minimal. A 7.5 V lithium battery supplies the power for thermistor type temperature sensors for monitoring system performance, and a 28 V lithium battery supplies power for valve actuation.

Grote, M. G.; Calhoun, L. D., II

1984-02-01

120

The Cattaneo type space-time fractional heat conduction equation  

NASA Astrophysics Data System (ADS)

The classical heat conduction equation is generalized using a generalized heat conduction law. In particular, we use the space-time Cattaneo heat conduction law that contains the Caputo symmetrized fractional derivative instead of gradient {{partial_x}} and fractional time derivative instead of the first order partial time derivative {{partial_t}} . The existence of the unique solution to the initial-boundary value problem corresponding to the generalized model is established in the space of distributions. We also obtain explicit form of the solution and compare it numerically with some limiting cases.

Atanackovi?, Teodor; Konjik, Sanja; Oparnica, Ljubica; Zorica, Dušan

2012-11-01

121

From 1D-Multi-Layer-Conductivity-Inversion to Pseudo-3D-Imaging of Quantified Electromagnetic Induction Data Acquired at a Heterogeneous Test Site  

NASA Astrophysics Data System (ADS)

Electromagnetic induction (EMI) systems enable the non-invasive spatial characterization of soil structural and hydrogeological variations, since the measured apparent electrical conductivity (ECa) can be related to changes in soil moisture, soil water, clay content and/or salinity. Due to the contactless operation, ECa maps of relatively large areas, i.e. field to (small) catchment scale, can be measured in reasonably short times. A multi-configuration EMI system with one electromagnetic field transmitter and various receivers with different offsets provide simultaneous ECa measurements that are representative of different sensing depths. Unfortunately, measured ECa values can only be considered as qualitative values due to external influences like the operator, cables or other metal objects. Of course, a better vertical characterization of the subsurface is possible when quantitative measurement values could be obtained. To obtain such quantitative ECa values, the measured EMI apparent conductivities are calibrated using a linear regression approach with predicted apparent conductivities obtained from a Maxwell-based full-solution forward model using inverted electrical resistivity tomography (ERT) data as input. These calibrated apparent conductivities enable a quantitative multi-layer-inversion to resolve for the electrical conductivity of certain layers. To invert for a large scale three-layer model, a one-dimensional (1D) shuffled-complex-evolution inversion scheme was parallelized and run on JUROPA - one of the supercomputers of the Forschungszentrum Jülich. This novel inversion routine was applied to calibrated electromagnetic induction data acquired at the Selhausen test site (Germany), which has a size of about 190 x 70 m. The test site is weakly inclined and a distinct gradient in soil texture is present with considerably higher gravel content at the upper part of the field. Parallel profiles with approximately three meter distance were measured using three different coil offsets in HCP and VCP measurement modes. This resulted in six high spatial resolution data sets of approximately 60000 measurements with different sensing depths. A 5 m block-kriging was applied to all six data sets to re-grid the sampling points on the same regular grid. For each grid node, the six measured apparent conductivities were used in a three-layer inversion. The three-layer inversion results of electrical conductivity thus obtained were used to derive a three-dimensional (3D) model of subsurface heterogeneity, which clearly indicated lateral and vertical conductivity changes of the subsurface that are related to changes in soil texture and soil water content.

von Hebel, Christian; Rudolph, Sebastian; Huisman, Johan A.; van der Kruk, Jan; Vereecken, Harry

2013-04-01

122

Electrical conductivity of rocks in the heating and cooling cycle  

Microsoft Academic Search

Summary The values of the electrical conductivity, recorded during the heating and cooling cycle, of eclogites and basalts are compared. The observed difference in the values is explained by reversible and irreversible changes which take place in the samples.

Marcela Lastovicková; F. Janák

1978-01-01

123

The influence of heat conduction on acoustic streaming  

Microsoft Academic Search

Summary The influence of heat conduction on acoustic streaming is considered including the effect of variable tube wall temperature. The calculations are carried out in the limiting case when the boundary layer is thin compared to the tube radius.

Nikolaus Rott

1974-01-01

124

Experimental evidence of hyperbolic heat conduction in processed meat  

SciTech Connect

The objective of this paper is to present experimental evidence of the wave nature of heat propagation in processed meat and to demonstrate that the hyperbolic heat conduction model is an accurate representation, on a macroscopic level, of the heat conduction process in such biological material. The value of the characteristic thermal time of a specific material, processed bologna meat, is determined experimentally. As a part of the work different thermophysical properties are also measured. The measured temperature distributions in the samples are compared with the Fourier results and significant deviation between the two is observed, especially during the initial stages of the transient conduction process. The measured values are found to match the theoretical non-Fourier hyperbolic predictions very well. The superposition of waves occurring inside the meat sample due to the hyperbolic nature of heat conduction is also proved experimentally. 14 refs., 7 figs., 2 tabs.

Mitra, K.; Kumar, S.; Vedavarz, A.; Moallemi, M.K. [Polytechnic Univ., Brooklyn, NY (United States)

1995-08-01

125

Enhanced anisotropic heat conduction in multi-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Anisotropy of heat conduction in multi-walled carbon nanotubes (MWNTs) is investigated by measuring heat flows in a pristine MWNT and in a MWNT with defects. The in- and out-of-shell thermal conductivities of each MWNT graphite shell are determined, and differences of more than four orders of magnitude are obtained because of the inter-shell gaps. This enhanced anisotropy reduces the conductance by 74% compared with that of the pristine MWNT because of the presence of outer shell defects, which comprise only 2.8% volume ratio. Furthermore, the anisotropy-assisted length dependence of thermal conductivity is demonstrated, even though there is no ballistic phonon transport.

Hayashi, Hiroyuki; Ikuta, Tatsuya; Nishiyama, Takashi; Takahashi, Koji

2013-01-01

126

Assessment of a 3-D Boundary Layer Analysis to Predict Heat Transfer and Flow Field in a Turbine Passage.  

National Technical Information Service (NTIS)

An assessment was made of the applicability of a three dimensional boundary layer analysis of heat transfer, total pressure losses, and streamline flow patterns on the surfaces of both stationary and rotating turbine passages. In support of this effort, a...

O. L. Anderson

1985-01-01

127

Unsteady droplet combustion with droplet heating. II. Conduction limit  

Microsoft Academic Search

The spherically-symmetric, thin-flame combustion of a pure component droplet is analyzed by assuming quasi-steady gas-phase processes and conduction being the only heat transfer mechanism within the droplet. Exact numerical, and an approximate analytical, solutions are presented. Results show that droplet heating is the dominant heat utilization mode for the initial 10 to 20 percent of the droplet lifetime, during which

C. K. Law; W. A. Sirignono

1977-01-01

128

Tolerance averaging of heat conduction in transversally graded laminates  

Microsoft Academic Search

It is considered a heat conduction in a layer made of two conductors distributed in the form of laminas with varied thicknesses.\\u000a Macroscopic (averaged) properties of the layer are continuously “transversally” graded across its thickness (TGL layer), cf.\\u000a Fig. 1. The aim of the paper is to present and apply an averaged model of the heat conduction, obtained within the tolerance

Jaros?aw J?drysiak; Alina Radzikowska

129

Heat Conduction in Fine Scale Mixtures With Interfacial Contact Resistance  

Microsoft Academic Search

Heat conduction in a fine scale mixture of two conductors is examined in the presenceof a contact resistance between phases. The problem is studied rigorously in the contextof periodic homogenization. Unlike the case of perfect heat transmission between phases,the temperature fields studied here may converge weakly in L2to the homogenizedtemperature. The temperature gradients converge weakly as Radon measures. Thestrict ellipticity

Robert Lipton

1998-01-01

130

Electron Heat Conduction in the Phaedrus Tandem Mirror  

Microsoft Academic Search

Experiments to investigate electron heat conduction have been performed on the University of Wisconsin tandem mirror Phaedrus. Electron temperature differences along the magnetic field were generated using a mircowave heat pulse. Probe techniques were developed for the continuous measurement of local electron temperatures with a time resolution of less than one microsecond. Parameter studies indicated that the temperature differences were

Donna Lynn Smatlak

1982-01-01

131

Efficient sequential solution of the nonlinear inverse heat conduction problem  

Microsoft Academic Search

A solution to the nonlinear inverse heat conduction problem is offered which employs a sequential procedure for the calculation of surface heat fluxes and temperatures from measured interior temperatures in opaque solids having temperature-variable thermal properties. The nonlinear problem is linearized, and through the elimination of iteration, computation time can be reduced by a factor of 3 or 4. The

J. V. Beck; B. Litkouhi; C. R. Saint Clair Jr.

1982-01-01

132

Variable Conductance Heat Pipes from the Laboratory to Space.  

National Technical Information Service (NTIS)

Heat pipes were developed which can be used as (1) a variable conductance link between a heat source and sink which provides temperature stability; (2) a feedback control mechanism that acts to directly maintain the source at a constant temperature; (3) o...

J. P. Kirkpatrick

1973-01-01

133

Heat conduction losses in laser cutting of metals  

Microsoft Academic Search

Using the model of a cylinder-type heat source, the power loss owing to heat conduction in laser cutting and welding of metals is calculated analytically. The case of laser cutting is described by taking into account the influence of the generated cutting kerf using numerical calculations. Both the analytical and the numerical solution for the power loss deposited into the

W. Schulz; D. Becker; J. Franke; R. Kemmerling; G. Herziger

1993-01-01

134

Radiation-conduction heat transfer in fibrous heat-resistant insulation under thermal effect  

Microsoft Academic Search

The conjugate diffusion model of radiation transfer and the approximation of radiant thermal conductivity are used to investigate\\u000a the radiation-conduction heat transfer in a flat layer of fibrous heat-resistant insulation under the effect of fire. The\\u000a results of calculation of the characteristics of unsteady-state heat transfer and of the duration of heat resistance of the\\u000a substrate demonstrate the accuracy of

V. G. Zverev; V. D. Gol’din; V. A. Nazarenko

2008-01-01

135

Magnonic domain wall heat conductance in ferromagnetic wires.  

PubMed

We present a theoretical study of magnon-mediated heat transport in electrically insulating ferromagnetic wires containing a domain wall (DW). In the regime of validity of continuum micromagnetism, a DW is found to have no effect on the heat conductance. However, spin waves are found to be reflected by DWs with widths of a few lattice spacings, which is associated with emergence of an additional spin wave bound state. The resulting DW heat conductance should be significant for thin films of yttrium iron garnet with sharply defined magnetic domains. PMID:23002771

Yan, Peng; Bauer, Gerrit E W

2012-08-21

136

Optical sensor for heat conduction measurement in biological tissue  

NASA Astrophysics Data System (ADS)

This paper presents the design of a heat flux sensor using an optical fiber system to measure heat conduction in biological tissues. This optoelectronic device is based on the photothermal beam deflection of a laser beam travelling in an acrylic slab this deflection is measured with a fiber optic angle sensor. We measure heat conduction in biological samples with high repeatability and sensitivity enough to detect differences in tissues from three chicken organs. This technique could provide important information of vital organ function as well as the detect modifications due to degenerative diseases or physical damage caused by medications or therapies.

Gutierrez-Arroyo, A.; Sanchez-Perez, C.; Aleman-Garcia, N.

2013-06-01

137

Magnonic Domain Wall Heat Conductance in Ferromagnetic Wires  

NASA Astrophysics Data System (ADS)

We present a theoretical study of magnon-mediated heat transport in electrically insulating ferromagnetic wires containing a domain wall (DW). In the regime of validity of continuum micromagnetism, a DW is found to have no effect on the heat conductance. However, spin waves are found to be reflected by DWs with widths of a few lattice spacings, which is associated with emergence of an additional spin wave bound state. The resulting DW heat conductance should be significant for thin films of yttrium iron garnet with sharply defined magnetic domains.

Yan, Peng; Bauer, Gerrit E. W.

2012-08-01

138

Experimental and 3-D numerical analysis of the thermal-Hydraulic characteristics of elliptic finned-tube heat exchangers  

SciTech Connect

Fluid flow and heat transfer over a 4-row, elliptic, finned-tube heat exchanger having an axis ratio of 2.83:1 are studied experimentally and numerically. Three types of finned-tube configurations have been investigated under dry and wet conditions for different values of inlet frontal velocity ranging from 2 to 7 m/s: two elliptic finned tubes with staggered and in-line arrangements and one circular finned tube with staggered arrangement. The experimental results indicate that the average heat transfer coefficient of an elliptic finned tube is 35--50% of the corresponding circular finned tube having the same tube perimeter, while the pressure drop for an elliptic finned-tube bank is only 25--30% of the circular finned-tube bank configuration. Three-dimensional numerical results of a laminar model for dry coils are also presented and are compared with the experimental data.

Jang, J.Y.; Yang, J.Y. [National Cheng-Kung Univ., Tainan (Taiwan, Province of China). Dept. of Mechanical Engineering

1998-10-01

139

Gas heat conduction in an evacuated tube solar collector  

SciTech Connect

We investigated experimentally the pressure dependency of the gas heat conduction in an evacuated plate-in-tube solar collector. A stationary heat loss experiment was built up with an electrically heated real-size collector model. The gas pressure was varied from 10{sup -3} to 10{sup 4} Pa, the temperatures of the absorber and the casing were held at 150{degree}C (electrical heaters) and 30{degree}C (water cooling), respectively. Losses by radiation and solid conduction were determined experimentally at pressures below 0.1 Pa. At higher pressures these background losses were subtracted from the total heat losses, to receive the heat losses by gas heat conduction. The experimental results were compared with approximate theoretical models. The onset of convection is in agreement with the usual theories for parallel plates taking the largest distance between the absorber and the gas tube as the plate distance. As a first approximation the pressure dependency of the gas heat conduction is described by the usual theory for parallel plates, taking the smallest distance between the absorber and the glass tube as the plate distance. 11 refs., 3 figs.

Beikircher, T.; Goldemund, G. [Ludwig-Maximilians-Universitaet Muenchen (Germany); Benz, N. [ZAE Bayern, Muenchen (Germany)

1996-10-01

140

An Experiment in Heat Conduction Using Hollow Cylinders  

ERIC Educational Resources Information Center

|An experimental apparatus was designed and built to allow students to carry out heat conduction experiments in hollow cylinders made of different materials, as well as to determine the thermal conductivity of these materials. The evolution of the temperature difference between the inner and outer walls of the cylinder as a function of time is…

Ortuno, M.; Marquez, A.; Gallego, S.; Neipp, C.; Belendez, A.

2011-01-01

141

Orthotropic thermal conductivity effect on cylindrical pin fin heat transfer  

Microsoft Academic Search

Analytical equations for temperature distribution and heat transfer rate from a cylindrical pin fin with orthotropic thermal conductivity, encountered in the use of thermally enhanced polymer composites, are derived and validated using detailed finite-element results. The thermal performance of such fins was found to depart from the classical fin solution with increasing radial conductivity-based Biot number. The in depth analysis

Raj Bahadur; Avram Bar-Cohen

2007-01-01

142

Effective heat conduction in a configuration with nonoverlapped magnetic islands  

SciTech Connect

The effective radial heat conduction {kappa}{sub eff} in a plasma configuration with nonoverlapped magnetic island chains is assessed by applying an ''optimal path'' method. This approach implies that heat is transported predominantly along paths rendering the minimum temperature variation and is related to the principle of minimum entropy production. Paths combined of up to three radial sections and two segments aligned along magnetic field lines are considered. It is demonstrated that the enhancement of {kappa}{sub eff} over the level of perpendicular heat conduction {kappa}{sub perpendicular} arising due to flows along magnetic field lines is controlled only by the Chirikov parameter and by the value 4b{sub r}{sup 2}{kappa}{sub parallel}/{kappa}{sub perpendicular}, where b{sub r} is the relative amplitude of the radial field resonant harmonic and {kappa}{sub parallel} is the parallel heat conduction.

Gupta, A.; Tokar, M. Z. [Institut fuer Energieforschung - Plasmaphysik, Forschungszentrum Juelich, Association EURATOM-FZJ, Trilateral Euregio Cluster, Juelich (Germany)

2008-03-15

143

Quantal Heating of Conducting Electrons with Discrete Spectrum  

SciTech Connect

Usually heating of conducting electrons by dc electric field results in an increase of electron temperature. In this paper we show that the dc heating of 2D electrons, placed in quantized magnetic fields, results in a peculiar electron distribution, which has the same broadening or an effective 'temperature' as the unbiased electron system. The quantal heating, however, violates strongly the Ohm's Law. In the conducting system with discrete electron spectrum the quantal heating results in spectacular decrease of electron resistance and transition of the electrons into a state with zero differential resistance (ZDR). Finally the heating leads to apparent dc driven metal-insulator transition, which correlates with the transition into the ZDR state. The correlation is very unexpected and is not understood.

Vitkalov, S. A. [Department of Physics, The City College of New York, New York, NY 10031 (United States); Bykov, A. A. [Institute of Semiconductor Physics, 630090 Novosibirsk (Russian Federation)

2011-12-23

144

Quantification of the 3-D electromagnetic power absorption rate in tissue during transurethral prostatic microwave thermotherapy using heat transfer model  

Microsoft Academic Search

Experiments were performed in a tissue microwave-equivalent phantom gel to quantitatively examine the volumetric heating produced by a microwave antenna with a peripheral cooling system for the transurethral prostatic thermotherapy. Based on previous research, expression for the specific absorption rate (SAR) of microwave energy in the gel was extended to three dimensions, which includes its dependence on radial, angular, and

Liang Zhu; Lisa X. Xu; Norbert Chencinski

1998-01-01

145

Body Segment Differences in Surface Area, Skin Temperature and 3D Displacement and the Estimation of Heat Balance during Locomotion in Hominins  

PubMed Central

The conventional method of estimating heat balance during locomotion in humans and other hominins treats the body as an undifferentiated mass. This is problematic because the segments of the body differ with respect to several variables that can affect thermoregulation. Here, we report a study that investigated the impact on heat balance during locomotion of inter-segment differences in three of these variables: surface area, skin temperature and rate of movement. The approach adopted in the study was to generate heat balance estimates with the conventional method and then compare them with heat balance estimates generated with a method that takes into account inter-segment differences in surface area, skin temperature and rate of movement. We reasoned that, if the hypothesis that inter-segment differences in surface area, skin temperature and rate of movement affect heat balance during locomotion is correct, the estimates yielded by the two methods should be statistically significantly different. Anthropometric data were collected on seven adult male volunteers. The volunteers then walked on a treadmill at 1.2 m/s while 3D motion capture cameras recorded their movements. Next, the conventional and segmented methods were used to estimate the volunteers' heat balance while walking in four ambient temperatures. Lastly, the estimates produced with the two methods were compared with the paired t-test. The estimates of heat balance during locomotion yielded by the two methods are significantly different. Those yielded by the segmented method are significantly lower than those produced by the conventional method. Accordingly, the study supports the hypothesis that inter-segment differences in surface area, skin temperature and rate of movement impact heat balance during locomotion. This has important implications not only for current understanding of heat balance during locomotion in hominins but also for how future research on this topic should be approached.

Cross, Alan; Collard, Mark; Nelson, Andrew

2008-01-01

146

Pulse accumulation, radial heat conduction, and anisotropic thermal conductivity in pump-probe transient thermoreflectance  

Microsoft Academic Search

The relationship between pulse accumulation and radial heat conduction in pump-probe transient thermoreflectance (TTR) is explored. The results illustrate how pulse accumulation allows TTR to probe two thermal length scales simultaneously. In addition, the conditions under which radial transport effects are important are described. An analytical solution for anisotropic heat flow in layered structures is given, and a method for

Aaron J. Schmidt; Xiaoyuan Chen; Gang Chen

2008-01-01

147

Macroscopic effects of E-region turbulence: Anomalous plasma heating and conductivity  

NASA Astrophysics Data System (ADS)

During periods of intense geomagnetic activity, strong electric fields penetrate from the Earth's magnetosphere to the high-latitude E-region ionosphere where they form electrojets and excite plasma instabilities. These instabilities give rise to plasma density turbulence coupled to electrostatic field fluctuations, causing a nonlinear current and anomalous heating. These two effects increase ionospheric conductivities that play an important role in magnetosphere-ionosphere coupling. A quantitative understanding of turbulent conductivities and energy conversion is important to accurately model magnetic storms and substorms. Our theoretical analysis, supported by fully kinetic 3-D particle-in-cell simulations, allows one to quantify energy budget in the electrojet, anomalous plasma heating and conductivities. Our recent theoretical analysis and computer simulations allow one to quantify the energy deposition in the ionosphere, particle heating, and effects of the anomalous conductivities. Our estimates show that during strong geomagnetic storms the inclusion of the instability-induced anomalous effects may nearly double the total Pedersen conductance. This helps explain why existing global MHD codes developed for predictive modeling of space weather systematically overestimate the cross-polar cap potentials by approximately a factor of two.

Dimant, Yakov; Oppenheim, Meers

2011-11-01

148

Heat Pipe Embedded AlSiC Plates for High Conductivity - Low CTE Heat Spreaders  

SciTech Connect

Heat pipe embedded aluminum silicon carbide (AlSiC) plates are innovative heat spreaders that provide high thermal conductivity and low coefficient of thermal expansion (CTE). Since heat pipes are two phase devices, they demonstrate effective thermal conductivities ranging between 50,000 and 200,000 W/m-K, depending on the heat pipe length. Installing heat pipes into an AlSiC plate dramatically increases the plate’s effective thermal conductivity. AlSiC plates alone have a thermal conductivity of roughly 200 W/m-K and a CTE ranging from 7-12 ppm/ deg C, similar to that of silicon. An equivalent sized heat pipe embedded AlSiC plate has effective thermal conductivity ranging from 400 to 500 W/m-K and retains the CTE of AlSiC.

Johnson, Matthew (DOE/NNSA Kansas City Plant (United States)); Weyant, J.; Garner, S. (Advanced Cooling Technologies, Inc. (Lancaster, PA (United States)); Occhionero, M. (CPS Technologies Corporation, Norton, MA (United States))

2010-01-07

149

Assessment of a 3-D boundary layer analysis to predict heat transfer and flow field in a turbine passage  

NASA Astrophysics Data System (ADS)

An assessment was made of the applicability of a three dimensional boundary layer analysis of heat transfer, total pressure losses, and streamline flow patterns on the surfaces of both stationary and rotating turbine passages. In support of this effort, an analysis was developed to calculate a general nonorthogonal surface coordinate system for arbitrary three dimensional surfaces and also to calculate the boundary layer edge conditions for compressible flow using the surface Euler equations and experimental pressure distributions. Calculations are presented for the pressure, endwall, and suction surfaces of a stationary cascade and for the pressure surface of a rotating turbine blade. The results strongly indicate that the three dimensional boundary layer analysis can give good predictions of the flow field, loss, and heat transfer on the pressure, suction, and endwall surface of a gas turbine passage.

Anderson, O. L.

1985-08-01

150

A novel three-component one-pot synthesis of pyrano[2,3- d]pyrimidines and pyrido[2,3- d]pyrimidines using microwave heating in the solid state  

Microsoft Academic Search

Microwave-assisted three-component cyclocondensation of barbituric acids 1, benzaldehyde 2 and alkyl nitriles 3 proceeds in the absence or presence of triethylamine to afford pyrano[2,3-d]pyrimidines 4 and 6-aminouracils 5 or 6-hydroxyaminouracils 6 react with 2 and 3 under identical conditions to yield pyrido[2,3-d]pyrimidines 7, all in high yields.

Ipsita Devi; B. S. D Kumar; Pulak J Bhuyan

2003-01-01

151

Dipolar DC Collisional Activation in a "Stretched" 3-D Ion Trap: The Effect of Higher Order Fields on rf-Heating  

NASA Astrophysics Data System (ADS)

Applying dipolar DC (DDC) to the end-cap electrodes of a 3-D ion trap operated with a bath gas at roughly 1 mTorr gives rise to `rf-heating' and can result in collision-induced dissociation (CID). This approach to ion trap CID differs from the conventional single-frequency resonance excitation approach in that it does not rely on tuning a supplementary frequency to coincide with the fundamental secular frequeny of the precursor ion of interest. Simulations using the program ITSIM 5.0 indicate that application of DDC physically displaces ions solely in the axial (inter end-cap) dimension whereupon ion acceleration occurs via power absorption from the drive rf. Experimental data shows that the degree of rf-heating in a stretched 3-D ion trap is not dependent solely on the ratio of the dipolar DC voltage/radio frequency (rf) amplitude, as a model based on a pure quadrupole field suggests. Rather, ion temperatures are shown to increase as the absolute values of the dipolar DC and rf amplitude both decrease. Simulations indicate that the presence of higher order multi-pole fields underlies this unexpected behavior. These findings have important implications for the use of DDC as a broad-band activation approach in multi-pole traps.

Prentice, Boone M.; McLuckey, Scott A.

2012-04-01

152

3-D Numerical Analysis for Heat Transfer from a Flat Plate in a Duct with Contractions Filled with Pressurized he II  

NASA Astrophysics Data System (ADS)

A computer code of three-dimensional heat transfer in superfluid helium named SUPER-3D was developed based on the two-fluid model. Critical heat fluxes (CHFs) on a flat plate located at one end of rectangular ducts having contractions with different rectangular open area were calculated by using the SUPER-3D for the liquid temperatures from 1.8 K to 2.1 K in pressurized He II. The analyses were made for the ducts with one contraction (Case A) and with two contractions (Case B). In case A, effects of the open mouth area and distance of the contraction from the flat plate were clarified. The solutions of CHF for the various open mouth areas agreed well with the experimental data. In Case B, the solutions of CHF for the two contractions with the same open areas were affected by the combination of open mouth figures. It was found from the analysis that several vortices are generated around the contractions and play an important role in determining the CHF. Three dimensional analyses are necessary to evaluate the CHF accurately.

Doi, D.; Shirai, Y.; Shiotsu, M.

2008-03-01

153

Electro-conductive sensors and heating elements based on conductive polymer composites  

Microsoft Academic Search

Purpose – The need for sensors and actuators is an important issue in the field of smart textiles and garments. Important developments in sensing and heating textile elements consist in using non-metallic yarns, for instance carbon containing fibres, directly in the textile fabric. Another solution is to use electro-conductive materials based on conductive polymer composites (CPCs) containing carbon or metallic

V. Koncar; C. Cochrane; M. Lewandowski; F. Boussu; C. Dufour

2009-01-01

154

Implicit continuum mechanics approach to heat conduction in granular materials  

SciTech Connect

In this paper, we derive a properly frame-invariant implicit constitutive relationship for the heat flux vector for a granular medium (or a density-gradient-type fluid). The heat flux vector is commonly modeled by Fourier’s law of heat conduction, and for complex materials such as nonlinear fluids, porous media, or granular materials, the coefficient of thermal conductivity is generalized by assuming that it would depend on a host of material and kinematic parameters such as temperature, shear rate, porosity, concentration, etc. In this paper, we extend the approach of Massoudi [Massoudi, M. Math. Methods Appl. Sci. 2006, 29, 1585; Massoudi, M. Math. Methods Appl. Sci. 2006, 29, 1599], who provided explicit constitutive relations for the heat flux vector for flowing granular materials; in order to do so, we use the implicit scheme suggested by Fox [Fox, N. Int. J. Eng. Sci. 1969, 7, 437], who obtained implicit relations in thermoelasticity.

Massoudi, M.; Mehrabadi, M.

2010-01-01

155

The estimation of the strength of the heat source in the heat conduction problems  

Microsoft Academic Search

A general method is proposed to determine the strength of the heat source in the Fourier and non-Fourier heat conduction problems. A finite difference method, the concept of the future time and a modified Newton–Raphson method are adopted in the problem. The undetermined heat source at each time step is formulated as an unknown variable in a set of equations

David T. W. Lin; Ching-yu Yang

2007-01-01

156

A Global Assessment of Oceanic Heat Loss: Conductive Cooling and Hydrothermal Redistribution of Heat  

NASA Astrophysics Data System (ADS)

A new dataset of ~15000 oceanic heat flow measurements is analyzed to determine the conductive heat loss through the seafloor. Many heat flow values in seafloor younger than 60 Ma are lower than predicted by models of conductively cooled lithosphere. This heat flow deficit is caused by ventilated hydrothermal circulation discharging at crustal outcrops or through thin sedimentary cover. Globally filtering of heat flow data to retain sites with sediment cover >400 m thick and located >60 km from the nearest seamount minimizes the effect of hydrothermal ventilation. Filtered heat flow exhibit a much higher correlation coefficient with seafloor age (up to 0.95 for filtered data in contrast to 0.5 for unfiltered data) and lower variability (reduction by 30%) within an age bin. A small heat flow deficit still persists at ages <25 Ma, possibly as a result of global filtering limitations and incomplete thermal rebound following sediment burial. Detailed heat flow surveys co-located with seismic data can identify environments favoring conductive heat flow; heat flow collected in these environments is higher than that determined by the global dataset, and is more consistent with conductive cooling of the lithosphere. The new filtered data analysis and a growing number of site specific surveys both support estimates of global heat loss in the range 40-47 TW. The estimated hydrothermal deficit is consistent with estimates from geochemical studies ~7 TW, but is a few TW lower than previous estimates derived from heat flow determinations.

Hasterok, D. P.; Chapman, D. S.; Davis, E. E.

2011-12-01

157

Combined conduction and radiation heat transfer in porous materials heated by intense solar radiation  

Microsoft Academic Search

An analysis is presented to predict the heat transfer characteristics of a plane layer of a semitransparent, high-temperature, porous material which is irradiated by an intense solar flux. A transient, combined conduction and radiation heat transfer model, which is based on a two-flux approximation for the radiation, is used to predict the temperature distribution and heat transfer in the material.

L. K. Matthews; F. P. Incropera; R. Viskanta

1985-01-01

158

Performance degradation due to longitudinal heat conduction in very high NTU counterflow heat exchangers  

Microsoft Academic Search

High effectiveness heat exchangers are employed in most cryogenic systems. In some systems such as cryocoolers employed in space, the NTU of the heat exchangers employed is quite large. The effectiveness of all such exchangers is largely controlled by the longitudinal heat conduction through the walls. In this paper, we present a closed form expression for the effectiveness of very

S. Pradeep Narayanan; G. Venkatarathnam

1998-01-01

159

Thermally conductive cementitious grout for geothermal heat pump systems  

DOEpatents

A thermally conductive cement-sand grout for use with a geothermal heat pump system. The cement sand grout contains cement, silica sand, a superplasticizer, water and optionally bentonite. The present invention also includes a method of filling boreholes used for geothermal heat pump systems with the thermally conductive cement-sand grout. The cement-sand grout has improved thermal conductivity over neat cement and bentonite grouts, which allows shallower bore holes to be used to provide an equivalent heat transfer capacity. In addition, the cement-sand grouts of the present invention also provide improved bond strengths and decreased permeabilities. The cement-sand grouts can also contain blast furnace slag, fly ash, a thermoplastic air entraining agent, latex, a shrinkage reducing admixture, calcium oxide and combinations thereof.

Allan, Marita (Old Field, NY)

2001-01-01

160

Inverse Hyperbolic Heat Conduction in Fins with Arbitrary Profiles  

Microsoft Academic Search

This study aims to estimate unknown base temperature distribution in different non-Fourier fins. The Cattaneo–Vernotte (CV) heat model is used to predict the heat conduction behavior in these fins. This inverse problem is solved by the function-estimation version of the Adjoint conjugate gradient method (ACGM) based on boundary temperature measurements. The ACGM includes direct, sensitivity, and adjoint problems. For each

Aziz Azimi; Keivan Bamdad; Hossein Ahmadikia

2012-01-01

161

Heat conduction in one-dimensional aperiodic quantum Ising chains  

NASA Astrophysics Data System (ADS)

The heat conductivity of nonperiodic quantum Ising chains whose ends are connected with heat baths at different temperatures are studied numerically by solving the Lindblad master equation. The chains are subjected to a uniform transverse field h, while the exchange coupling Jm between the nearest-neighbor spins takes the two values JA and JB arranged in Fibonacci, generalized Fibonacci, Thue-Morse, and period-doubling sequences. We calculate the energy-density profile and energy current of the resulting nonequilibrium steady states to study the heat-conducting behavior of finite but large systems. Although these nonperiodic quantum Ising chains are integrable, it is clearly found that energy gradients exist in all chains and the energy currents appear to scale as the system size ~N?. By increasing the ratio of couplings, the exponent ? can be modulated from ?>-1 to ?<-1 corresponding to the nontrivial transition from the abnormal heat transport to the heat insulator. The influences of the temperature gradient and the magnetic field to heat conduction have also been discussed.

Li, Wenjuan; Tong, Peiqing

2011-03-01

162

Effect of crosslink formation on heat conduction in amorphous polymers  

NASA Astrophysics Data System (ADS)

We performed molecular dynamics (MD) simulations on amorphous polyethylene (PE) and polystyrene (PS) in order to elucidate the effect of crosslinks between polymer chains on heat conduction. In each polymer system, thermal conductivities were measured for a range of crosslink concentration by using nonequilibrium MD techniques. PE comprised of 50 carbon atom long chains exhibited slightly higher conductivity than that of 250 carbon atom long chains at the standard state. In both cases for PE, crosslinking significantly increased conductivity and the increase was more or less proportional to the crosslink density. On the other hand, in the PS case, although the thermal conductivity increased with the crosslinking, the magnitude of change in thermal conductivity was relatively small. We attribute this difference to highly heterogeneous PS based network including phenyl side groups. In order to elucidate the mechanism for the increase of thermal conductivity with the crosslink concentration, we decomposed energy transfer into modes associated with various bonded and non-bonded interactions.

Kikugawa, Gota; Desai, Tapan G.; Keblinski, Pawel; Ohara, Taku

2013-07-01

163

Spectroscopic Evidence for the Formation of 3-D Crystallites During Isothermal Heating of Amorphous Ice on PT(111)  

SciTech Connect

The formation of crystalline ice through isothermal heating of 80 layers amorphous ice on Pt(111) at 150 K is studied using X-ray photoelectron spectroscopy and infrared reflection absorption spectroscopy. An early indicator for inhomogeneous crystallization is provided by the uncharacteristically high Pt 4f photoelectron peak for crystalline ice compared with the corresponding uniformly thick amorphous case. O 1s photoelectron spectra unambiguously show that the first monolayer is exposed after crystallization at multilayer total coverage. Using the relative intensities between the first monolayer and multilayer contributions to the O 1s photoelectron spectra, we estimated that -46% and -80% of the first monolayer is exposed to vacuum with an average crystallite height of -41 and -31 layers for an equivalent total coverage of -23 and -7 layers, respectively.

Waluyo, I.; Nordlund, D.; Naslund, L.-A.; Ogasawara, H.; Pettersson, L.G.M.; Nilsson, A.

2009-05-26

164

3D CFD Electrochemical and Heat Transfer Model of an Integrated-Planar Solid Oxide Electrolysis Cells  

SciTech Connect

A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in a new novel integrated planar porous-tube supported solid oxide electrolysis cell (SOEC). The model is of several integrated planar cells attached to a ceramic support tube. This design is being evaluated with modeling at the Idaho National Laboratory. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, activation over-potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean per-cell area-specific-resistance (ASR) values decrease with increasing current density. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Effects of variations in operating temperature, gas flow rate, cathode and anode exchange current density, and contact resistance from the base case are presented. Contour plots of local electrolyte temperature, current density, and Nernst potential indicated the effects of heat transfer, reaction cooling/heating, and change in local gas composition. Results are discussed for using this design in the electrolysis mode. Discussion of thermal neutral voltage, enthalpy of reaction, hydrogen production, cell thermal efficiency, cell electrical efficiency, and Gibbs free energy are discussed and reported herein.

Grant Hawkes; James E. O'Brien

2008-10-01

165

Using Markov Chain Monte Carlo Simulation for Heat Conduction Problems  

NASA Astrophysics Data System (ADS)

In our Damped Heat Wave (DHW) algorithm for calculation of temperature distribution in a one-dimensional finite medium, the space and time is discretized using N nodal points with steps ?x and ?t. Heat propagates through the medium due to temperature differences between divisions. At any instant of time a certain portion (given by the inner heat transfer coefficient) of the excessive heat energy moves from one division to its neighbour division thus lowering temperature difference between those two divisions. We will show that our DHW algorithm represents a special case of time-space Markov Chain Monte Carlo (MCMC) simulation with a simple random number generator for the redistribution sequence. This is a very unique and distinctive feature. All today existing numerical methods used in heat conduction calculations (e.g. explicit or implicit finite differences method, finite elements methods, etc.) are Markov Chains in time, but not simultaneously in space. We will show that in a general case, when we choose a different random number generator for the redistribution sequence, with randomly chosen neighbor, with the inner heat transfer coefficient also a random number drawn from Gaussian distribution, the MCMC simulation is rapidly converging to the analytical solution of transient heat conduction equation.

Gembarovic, Jozef

2011-10-01

166

Full scale 3D-modelling of the coupled gas migration and heat dissipation in a planned repository for radioactive waste in the Callovo-Oxfordian clay  

NASA Astrophysics Data System (ADS)

An important question related to the long-term safety performance of a repository for long-lived medium and high-level radioactive waste in the Callovo-Oxfordian clay unit is the impact of heat and gas generated in the waste emplacement areas on the gas and water pressure and on the water saturation in the backfilled repository and in the host rock.The current design of such a repository consists of a multitude of different underground structures, such as emplacement drifts for waste canisters and other types of waste packages, access and ventilation drifts, and access shafts in the central part of the repository. The individual underground structures exhibit different thermo-hydraulic and geometrical properties yielding a large and complex system for the flow and transport of gas, water and heat.A detailed 3D modelling of the entire repository would require a tremendous computational effort, even when using high performance simulator codes. A newly developed method (Poller et al., 2011) allows for the 3D modelling of the two-phase gas-water flow and thermal evolution in the entire repository/host-rock system in a simplified manner. Besides accounting for both the detailed structures at local scale and the global geometry of the drift network, it also allows for an assessment of the gas phase pressure as well as the hydrogen and heat fluxes developing over the complete lifetime of the repository system.In this paper, the results of a reference scenario are presented. The assessment focuses on the two dominant processes, i.e. the dissolution and diffusion of the generated hydrogen, and the advective migration of the forming hydrogen gas phase in space and time (up to 1 million years). Further, the main findings of a sensitivity analysis on different features, physical processes and parameter uncertainty are presented.

Enssle, Carl Philipp; Croisé, Jean; Poller, Andreas; Mayer, Gerhard; Wendling, Jacques

167

Effect of Component-Level Heat Conduction on Reflow Soldering Failures  

Microsoft Academic Search

In this paper a 3D conduction model and its possible calculation methods are presented. Our 3D model is based on the thermal (central) node theory. It means that all elements of the circuit contain a central node, to which all of the thermal mass of that area of the assembly is assigned. The model can describe and compute the conduction

Balazs Illes; O. Krammer; G. Harsanyi; Z. Illyefalvi-Vitez; A. Szabo

2006-01-01

168

Structure of fast shocks in the presence of heat conduction  

SciTech Connect

There are three types of magnetohydrodynamic (MHD) shocks: the fast shock, intermediate shock, and slow shock. The structure of slow shocks and intermediate shocks in the presence of heat conduction has been studied earlier [C. L. Tsai, R. H. Tsai, B. H. Wu, and L. C. Lee, Phys. Plasmas 9, 1185 (2002); C. L. Tsai, B. H. Wu, and L. C. Lee, Phys. Plasmas 12, 82501 (2005)]. Based on one-dimensional MHD numerical simulations with a heat conduction term, the evolution and structure of fast shocks are studied. The fast shock will form a foreshock in the presence of heat conduction. The foreshock is formed due to the heat flow from downstream to upstream and located in the immediate upstream of the main shock. In the steady state, the value of diffusion velocity V{sub d} in the foreshock is found to nearly equal the upstream convection velocity in the fast shock frame. It is found that the density jump across the main shock in high Mach number case can be much larger than 4 in the early simulation time. However the density jump will gradually evolve to a value smaller than 4 at steady state. By using the modified Rankine-Hugoniot relations with heat flux, the density jump across the fast shock is examined for various upstream parameters. The results show that the calculated density jump with heat flux is very close to the simulation value and the density jump can far exceed the maximum value of 4 without heat conduction. The structure of foreshock and main shock is also studied under different plasma parameters, such as the heat conductivity K{sub 0}, the ratio of upstream plasma pressure to magnetic pressure {beta}{sub 1}, Alfven Mach number M{sub A1}, and the angle {theta}{sub 1} between shock normal and magnetic field. It is found that as the upstream shock parameters K{sub 0}, {beta}{sub 1}, and M{sub A1} increase or {theta}{sub 1} decreases, the width of foreshock L{sub d} increases. The present results can be applied to fast shocks in the solar corona, solar wind, and magnetosphere, in which the heat conduction effects are important.

Tsai, C. L.; Chen, H. H.; Wu, B. H.; Lee, L. C. [Earth Dynamic System Research Center and Department of Physics, National Cheng Kung University, Tainan, 701 Taiwan and Institute of Space Science, National Central University, Jhongli, 320 Taiwan (China); Department of Physics, National Cheng Kung University, Tainan, 701 Taiwan and Institute of Space Science, National Central University, Jhongli, 320 Taiwan (China); National Space Organization, Hsinchu, 300 Taiwan (China); Institute of Space Science, National Central University, Jhongli, 320 Taiwan (China)

2007-12-15

169

Self assembled structures for 3D integration  

NASA Astrophysics Data System (ADS)

Three dimensional (3D) micro-scale structures attached to a silicon substrate have various applications in microelectronics. However, formation of 3D structures using conventional micro-fabrication techniques are not efficient and require precise control of processing parameters. Self assembly is a method for creating 3D structures that takes advantage of surface area minimization phenomena. Solder based self assembly (SBSA), the subject of this dissertation, uses solder as a facilitator in the formation of 3D structures from 2D patterns. Etching a sacrificial layer underneath a portion of the 2D pattern allows the solder reflow step to pull those areas out of the substrate plane resulting in a folded 3D structure. Initial studies using the SBSA method demonstrated low yields in the formation of five different polyhedra. The failures in folding were primarily attributed to nonuniform solder deposition on the underlying metal pads. The dip soldering method was analyzed and subsequently refined. A modified dip soldering process provided improved yield among the polyhedra. Solder bridging referred as joining of solder deposited on different metal patterns in an entity influenced the folding mechanism. In general, design parameters such as small gap-spacings and thick metal pads were found to favor solder bridging for all patterns studied. Two types of soldering: face and edge soldering were analyzed. Face soldering refers to the application of solder on the entire metal face. Edge soldering indicates application of solder only on the edges of the metal face. Mechanical grinding showed that face soldered SBSA structures were void free and robust in nature. In addition, the face soldered 3D structures provide a consistent heat resistant solder standoff height that serve as attachments in the integration of dissimilar electronic technologies. Face soldered 3D structures were developed on the underlying conducting channel to determine the thermo-electric reliability of face soldered structures.

Rao, Madhav

170

Heat conduction in partial vacuum. Final technical progress report  

SciTech Connect

Methods developed for computing conduction heat losses from evacuated solar collectors are reported. Results of such calculations are given, including the minimum vacuum necessary to effectively eliminate conduction. Experiments performed at Owens-Illinois, Inc. to assess helium penetration rates into evacuated collectors are analyzed, and estimates are given as to the likely penetration rate of atmospheric helium. Conclusions are drawn as to the probable effect of helium penetration on the lifetimes of evacuated solar collectors.

Thomas, J R

1980-09-01

171

3 omega method for specific heat and thermal conductivity measurements  

Microsoft Academic Search

We present a 3 omega method for simultaneously measuring the specific heat\\u000aand thermal conductivity of a rod- or filament-like specimen using a way\\u000asimilar to a four-probe resistance measurement. The specimen in this method\\u000aneeds to be electrically conductive and with a temperature-dependent\\u000aresistance, for acting both as a heater to create a temperature fluctuation and\\u000aas a sensor

L. Lu; W. Yi; D. L. Zhang

2002-01-01

172

3omega method for specific heat and thermal conductivity measurements  

Microsoft Academic Search

We present a 3omega method for simultaneously measuring the specific heat and thermal conductivity of a rod- or filament-like specimen using a way similar to a four-probe resistance measurement. The specimen in this method needs to be electrically conductive and with a temperature-dependent resistance, for acting both as a heater to create a temperature fluctuation and as a sensor to

L. Lu; W. Yi; D. L. Zhang

2001-01-01

173

High Conductance Loop Heat Pipes for Space Application  

NASA Astrophysics Data System (ADS)

Three high conductance Loop Heat Pipes (LHPs) for the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) were designed, fabricated and thermal vacuum tested. One LHP with ammonia working fluid was designed for heat removal from a cryocooler cold head. Two ethane LHPs were designed to reject heat from the aft and fore optics to space. Thermal performance tests were performed in a vacuum chamber with attached masses simulating actual components. Thermal tests were also conducted on the bench and in an environmental chamber. The following features of the GIFTS LHPs were observed: (a) reliable startup and steady state operation with conductance as high as 83W/°C at various temperatures; (b) precision temperature control using compensation chamber heater during thermal cycling. Heat input power and condenser temperatures were varied periodically, while evaporator was maintained at a constant temperature. Temperature of the evaporator heat input surface fluctuated only by a fraction of a degree; (c) in addition there was no thermal performance degradation after 16 month of storage. The LHPs are installed on the instrument and waiting for a launch platform.

Semenov, Sergey Y.; Cho, Wei-Lin; Jensen, Scott M.

2006-01-01

174

Phase transitions and heat conduction in post-glacial rebound  

NASA Astrophysics Data System (ADS)

We have developed a method for including phase boundary conditions into post-glacial rebound models that allows for conduction of latent heat away from the boundary. This method returns the chemical boundary results if latent heat conducts away from the phase boundary too slowly to allow the transition to proceed, as is commonly argued. This is not necessarily the case, however. For example, the secular change of the geoid and the vertical uplift rates for phase boundaries with latent heat conduction can differ from the chemical boundary results by up to 10 and 15 per cent, respectively. When modelling the phase transition, we consider two scenarios: the latent heat is released either at a narrow boundary that separates the two phases or over a thick mixed region of the two phases. In the case where the phase transition occurs over a thick enough region (5-10 km), the final results are close to the results obtained by considering a phase boundary that ignores the release of latent heat completely. This thick boundary formulation also suggest that the phase boundaries could respond nearly instantaneously, changing both the elastic load and body Love numbers. However, we have not considered kinetics, the energetics of the mechanisms of the phase transitions, in this formulation. This work suggests a greater knowledge of the kinetics near equilibrium phase transitions is required. A naive calculation indicates that the kinetics will not be a significant factor for post-glacial rebound but will be a limiting factor for earth tides.

Tamisiea, M. E.; Wahr, J. M.

2002-05-01

175

Plane Tricalorimetric Method for Measuring Thermal Conductivity of Poor Heat Conductors.  

National Technical Information Service (NTIS)

Equations were derived for the estimation of heat conductivity using the method of the flat tricalorimeter which permits the fast and simple determination of the heat conductivity of powder, fibrous and other insulation materials. The heat conductivity of...

Y. M. Naziev

1972-01-01

176

77 FR 39735 - Certain Integrated Circuit Packages Provided With Multiple Heat-Conducting Paths and Products...  

Federal Register 2010, 2011, 2012, 2013

...Packages Provided With Multiple Heat- Conducting Paths and Products Containing...packages provided with multiple heat-conducting paths and products containing...packages provided with multiple heat-conducting paths and products...

2012-07-05

177

Heat Conduction in Graphene Flakes of Arbitrary Geometry  

NASA Astrophysics Data System (ADS)

It was reported that the values of the room temperature thermal conductivity of graphene exceed those of carbon nanotubes [1-2]. The measurements of the thermal conductivity of graphene utilized a technique where the excitation laser initiated a heat wave. The data extraction procedure assumed plane heat waves. Realistic graphene flakes have variations in their width, and the heat wave front may deviate from the plane wave depending on the geometry of the flake. We report a numerical study of heat propagation in graphene flakes of arbitrary geometry. The thermal conduction was simulated using the finite element method. It was found that both the shape of the flake and the temperature distribution in the hot spot affect the extracted values. At the same time, for the flakes with the relatively constant width and the hot spot of the size comparable to the flake width, the thermal conductivity obtained within the simple plane-wave approximation give close values to our simulations. [1] A.A. Balandin, et al., Nano Letters, 8, 902 (2008) [2] S. Ghosh, et al., Appl. Phys. Lett., 92, 151911 (2008).

Subrina, Samia; Kotchetkov, Dmitri; Balandin, Alexander

2009-03-01

178

Models for the Specific Heat and Thermal Conductivity of Garlic  

Microsoft Academic Search

The proximate composition of garlic (cv. Early Californian) was determined and compared to values reported in the literature. The specific heat and thermal conductivity were determined using the method of mixtures and a modified Fitch apparatus, respectively and both approaches proved sufficiently accurate for such purposes. An analysis of variance revealed that moisture content had a highly significant effect on

PONCIANO S. MADAMBA; ROBERT H. DRISCOLL; KENNETH A. BUCKLE

1995-01-01

179

REVIEW OF THERMAL CONDUCTIVITY AND HEAT TRANSFER IN UOâ  

Microsoft Academic Search

The theories of heal transfer in insulators are viewed and discussed ; relevant to UOâ. As the rate of heat transfer from a reactor core is ; determined largely by the thermal conductivity of the fuuel, this coefficient is ; of paramount importance in improving the efficiency of an installation. There is ; no theoretical basis to expect small or

Tennery

1958-01-01

180

Equivalent inclusion method for steady state heat conduction in composites  

Microsoft Academic Search

The equivalent inclusion method is proposed to solve the steady state heat conduction problems in composites. This method is analogous to Eshelby's equivalent inclusion method in elasticity. Thus, the solution procedure by this method is very simple, involving only algebraic operations. The equivalent inclusion method developed here is also applicable to the case of high concentrations of ellipsoidal inhomogeneities. As

H Hiroshi; M. Taya

1986-01-01

181

Regularized numerical solution of nonlinear inverse heat-conduction problem  

Microsoft Academic Search

The construction of an algorithm for a numerical solution of the nonlinear inverse problem is discussed for the case of a generalized one-dimensional heat-conduction equation in a region with moving boundaries. The algorithm is regularized in the Tikhonov manner.

O. M. Alifanov; E. A. Artyukhin

1975-01-01

182

Group classification of heat conductivity equations with a nonlinear source  

Microsoft Academic Search

We suggest a systematic procedure for classifying partial differential equations (PDEs) invariant with respect to low-dimensional Lie algebras. This procedure is a proper synthesis of the infinitesimal Lie method, the technique of equivalence transformations and the theory of classification of abstract low-dimensional Lie algebras. As an application, we consider the problem of classifying heat conductivity equations in one variable with

R. Z. Zhdanov; V. I. Lahno

1999-01-01

183

Heat transfer analysis of low thermal conductivity solar energy absorbers  

Microsoft Academic Search

Polymers have been proven to be high potential low-cost materials for the design and mass production not only for ordinary solar water heaters but also for very simple large size, modular solar collectors, suitable for easy erection of large solar heating plants. Their major drawback for solar–thermal conversion applications is their low thermal conductivity, which prohibits their use unless an

P. T. Tsilingiris

2000-01-01

184

Ecoulements eau-vapeur. Modele de transfert thermique local en paroi pour un code Eulerien 3D. (Boiling water flows. A local wall heat transfer model for use in an Eulerian 3-D computer code).  

National Technical Information Service (NTIS)

Electricite de France is currently developing a 3-D computer code for the Eulerian simulation of two-phase flows. This code, named ASTRID, is based on the six-equation two-fluid model. Boiling water flows are among the main applications of ASTRID, especia...

P. Freydier O. Chen J. Boree J. Fabre G. Charnay

1993-01-01

185

Modeling of microconvection in a fluid between heat conducting solids  

NASA Astrophysics Data System (ADS)

Unsteady convection in a fluid under weak gravity is modeled. Convection in a rectangular domain elongated in the direction of gravity and enclosed between two heat-conducting solids is investigated in the case of heat insulation of the ends of the rectangle and the periodic heat flow through the outer boundaries of the solids. In this case, the condition of zero total heat flux is satisfied. Convective fluid motions are described using two mathematical models: the classical Oberbeck-Boussinesq model and the microconvection model for an isothermally incompressible fluid. Results of the numerical studies confirm the quantitative and qualitative differences between the flow characteristics calculated using the two convection models. Fluid particle trajectories are presented. Effects due to various physical characteristics of the problem are studied.

Goncharova, O. N.

2011-01-01

186

Comparison of Results for Ten Analytical Heat Conduction Problems as Solved by the General Heat Transfer Code HEATING5 (Heat Engineering and Transfer in Nine Geometries).  

National Technical Information Service (NTIS)

This report documents the results of the verification effort recently completed for the general heat conduction code HEATING5. Objective was to verify HEATING5 for use in estimating the temperature distribution around a waste package after it is emplaced ...

J. W. Insalaco

1987-01-01

187

Sensitivity Equation for Transient Three-Dimensional Heat Conduction Problem with Moving Heat Source  

NASA Astrophysics Data System (ADS)

Sensitivity analysis of transient three-dimensional heat conduction in a plate during process of welding is performed. Crank-Nicolson method with multi-step Douglas-Gunn Alternating Direction Implicit (ADI) method is used for the solution of heat conduction equation with convection boundary conditions at all surfaces, and with heat source at the top surface moving with a constant velocity. Sensitivity equation method (SEM) is applied for sensitivity calculations. It is shown that SEM is a set of straightforward operations in the case of heat conduction equation. Development of the sensitivity equation with respect to the power of the heat source is demonstrated and final results for this sensitivity are presented.

Ivanovic, Ivana; Sedmak, Aleksandar

2010-09-01

188

Direct liquid thermal management of 3D chip stacks  

Microsoft Academic Search

Chip stacks are a crucial building block in advanced 3D microsystem architectures and can accommodate shorter interconnect distances between devices, reduced power dissipation, and improved electrical performance. Although enhanced conduction can serve to transfer the dissipated heat to the top and sides of the package and\\/or down to the underlying PCB, effective thermal management of stacked chips remains a most

A. Bar-Cohen; K. J. L. Geisler; E. Rahim

2009-01-01

189

Pulse accumulation, radial heat conduction, and anisotropic thermal conductivity in pump-probe transient thermoreflectance.  

PubMed

The relationship between pulse accumulation and radial heat conduction in pump-probe transient thermoreflectance (TTR) is explored. The results illustrate how pulse accumulation allows TTR to probe two thermal length scales simultaneously. In addition, the conditions under which radial transport effects are important are described. An analytical solution for anisotropic heat flow in layered structures is given, and a method for measuring both cross-plane and in-plane thermal conductivities of thermally anisotropic thin films is described. As verification, the technique is used to extract the cross-plane and in-plane thermal conductivities of highly ordered pyrolytic graphite. Results are found to be in good agreement with literature values. PMID:19045906

Schmidt, Aaron J; Chen, Xiaoyuan; Chen, Gang

2008-11-01

190

The thermal-aware floorplanning for 3D ICs using Carbon Nanotube  

Microsoft Academic Search

Heat dissipation becomes one of the most serious challenges in three dimensional integrated circuits (3D ICs) designs. The through-silicon vias (TSVs) are effective on improving the thermal conductivity of 3D ICs. Many previous works have proposed thermal model for 3D ICs with TSVs, and formulated the TSV planning as a convex programming problem. On the other hand, besides excellent electrical

Shengqing Shi; Xi Zhang; Rong Luo

2010-01-01

191

Heat conduction nanocalorimeter for pl-scale single cell measurements  

NASA Astrophysics Data System (ADS)

An ultrasensitive nanocalorimeter for use with pl-scale biological samples using silicon microfabrication technology has been developed in which a 720 pl reaction vessel, a calibration heater, and a thermoelectric transducer of 125 ?K sensitivity were integrated into a single multilayer thin-film configuration. The resolution of the system ranged from 10 to 25 nW depending on the heat capacity, conductance and power density of the samples studied. The device has been used in heat conduction measurements of the energy released from the enzyme catalyzed hydrolysis of hydrogen peroxide using purified catalase, and for the determination of the catalase activity within a single mouse hepatocyte. The nanocalorimeter has the potential for integration in a high-density array format, where the change in temperature from ultralow volume cellular assays could be used as a generic analytical tool for high throughput screening of bioactive compounds.

Johannessen, E. A.; Weaver, J. M. R.; Cobbold, P. H.; Cooper, J. M.

2002-03-01

192

A general theory of heat conduction with finite wave speeds  

Microsoft Academic Search

The classical linear theory of heat conduction for homogeneous and isotropie media is based on the equation AO=b O0 where O=O(x, t) is the absolute temperature, 0=~T-, A is the Laplacian, and > 0 is a constant. This equation, which is parabolic, has a very unpleasant feature: a thermal disturbance at any point in the body is felt instantly at

Morton E. Gurtin; A. C. Pipkin

1968-01-01

193

When does a crystal conduct heat like a glass?  

Microsoft Academic Search

Semiconducting crystalline materials that are poor conductors of heat are important as thermoelectric materials and for technological applications involving thermal management. A combination of neutron scattering, low- temperature ultrasonic attenuation and thermal conductivity measurements are reported on single crystals of the semiconductors Sr 8Ga16Ge30 and Ba8Ga16Ge30. Taken together, these measurements suggest speci® c structural features that result in a crystal

V. KEPPENS; B. C. SALES; D. MANDRUS; B. C. CHAKOUMAKOS; C. LAERMANS

194

3D-AQS  

NASA Astrophysics Data System (ADS)

Over the last thirty years, we have come to understand that the atmosphere is quite dynamic, leading to transport of pollutants over wide areas including continent-to-continent motions. In order to understand the importance of local versus long-range transport, the vertical third dimension needs to be understood to assess source/receptor relationships. Our group has combined lidar at UMBC with measurements from spaceborne platforms to provide views of aerosol pollution in ways that weren't possible even ten years ago. As a result of the initial lidar/AOD work, we have recently been funded to create a Three Dimensional Air Quality System (3D-AQS) under the NASA Integrated Systems Solutions solicitation. This paper will review some of our recent studies on air pollution in the Baltimore-Washington region and describe the work to be conducted under 3D-AQS. We see this as the beginning of a new vision for NASA, NOAA, EPA and the Centers for Disease Control to combine systems under the Global Earth Observing Systems of Systems (GEOSS) approach to better determine the effects of aerosols on human health.

Hoff, R.; Chu, A.; Prados, A.; Wayland, C.; Kittaka, C.; Dimmick, F.; Al-Saadi, J.; Szykman, J.; Engel-Cox, J.; McCann, K.; Torres, O.; Kondragunta, S.; Ackerman, S.; Wimmers, T.; Boothe, V.

2006-05-01

195

Comparison of results for ten analytical heat conduction problems as solved by the general heat transfer code HEATING5 (Heat Engineering and Transfer in Nine Geometries)  

SciTech Connect

This report documents the results of the verification effort recently completed for the general heat conduction code HEATING5. Objective was to verify HEATING5 for use in estimating the temperature distribution around a waste package after it is emplaced in a repository. The approach taken in verifying HEATING5 was to compare the solutions obtained with HEATING5 to the analytical solutions for a series of problems for which analytical solutions existed. Ten analytical problems and one sample problem from the original source of HEATING5, the Radiation Shielding and Information Center, were chosen to verify HEATING5's capability to solve steady-state and transient heat conduction, including problems with an applied surface temperature or heat flux, constant or time-dependent thermal conductivity, and constant or time-dependent heat generation. This study did not attempt to verify HEATING5 for problems that involve convection, radiation, or anisotropic thermal properties.

Insalaco, J.W.

1987-07-01

196

Java 3D  

NSDL National Science Digital Library

Java3D is a low level 3D scene-graph based graphics programming API for the java language. It does not form part of the core APIs required by the Java specification. The class libraries exist under the javax.media.j3d top level package as well as utility classes provided in javax.vecmath.

197

Variable Conductance Heat Pipe Radiators for Lunar and Martian Environments  

NASA Astrophysics Data System (ADS)

Long-term Lunar and Martian surface systems present challenges to thermal system design, including changes in thermal load, and large changes in the thermal environment between Lunar (or Martian) day and night. For example, the heat sink temperature at the Lunar equator can vary from 210 to 315 K. The radiator must be sized to reject the design power at the maximum temperature, but must also be able to accommodate both the changing heat sink temperature, as well as changes in power. Variable Conductance Heat Pipe (VCHP) radiators were examined for the main reactor of a fission surface power system, as well as the cavity cooling radiator. A VCHP radiator was designed for Lunar Equator that is capable of maintaining a 16 K temperature drop with a 4% addition to overall mass. Without the VCHP the radiator would experience a 43 K drop in temperature. This design is also capable of handling turndown on the power without an effect to the outlet temperature. At Shackleton Crater, the temperature drop for a conventional heat pipe radiator is small enough that a VCHP is not beneficial at constant power. However, a VCHP will allow turndown ratios of 5:1 or more. A conventional radiator can not be turned down more than 2:1, without valves to bypass part of the radiator. VCHPs are also easier to start than conventional radiators, since the gas-loading prevents sublimation from the evaporator when the condenser is frozen.

Anderson, William G.; Ellis, Michael C.; Walker, Kara L.

2009-03-01

198

Numerical modeling of thermal conductive heating in fractured bedrock.  

PubMed

Numerical modeling was employed to study the performance of thermal conductive heating (TCH) in fractured shale under a variety of hydrogeological conditions. Model results show that groundwater flow in fractures does not significantly affect the minimum treatment zone temperature, except near the beginning of heating or when groundwater influx is high. However, fracture and rock matrix properties can significantly influence the time necessary to remove all liquid water (i.e., reach superheated steam conditions) in the treatment area. Low matrix permeability, high matrix porosity, and wide fracture spacing can contribute to boiling point elevation in the rock matrix. Consequently, knowledge of these properties is important for the estimation of treatment times. Because of the variability in boiling point throughout a fractured rock treatment zone and the absence of a well-defined constant temperature boiling plateau in the rock matrix, it may be difficult to monitor the progress of thermal treatment using temperature measurements alone. PMID:20550586

Baston, Daniel P; Falta, Ronald W; Kueper, Bernard H

199

Radiative Cooling and Heating and Thermal Conduction in M87  

NASA Astrophysics Data System (ADS)

The crisis of the standard cooling flow model brought about by Chandra and XMM-Newton observations of galaxy clusters has led to the development of several models that explore different heating processes in order to assess whether they can quench the cooling flow. Among the most appealing mechanisms are thermal conduction and heating through buoyant gas deposited in the intracluster medium (ICM) by active galactic nuclei (AGNs). We combine Virgo/M87 observations of three satellites (Chandra, XMM-Newton, and BeppoSAX) to inspect the dynamics of the ICM in the center of the cluster. Using the spectral deprojection technique, we derive the physical quantities describing the ICM and determine the extra heating needed to balance the cooling flow, assuming that thermal conduction operates at a fixed fraction of the Spitzer value. We assume that the extra heating is due to buoyant gas, and we fit the data using the model developed by Ruszkowski and Begelman. We derive a scale radius for the model of ~5 kpc, which is comparable with the M87 AGN jet extension, and a required luminosity of the AGN of afew×1042ergss-1, which is comparable to the observed AGN luminosity. We discuss a scenario in which the buoyant bubbles are filled with relativistic particles and magnetic field, which are responsible for the radio emission in M87. The AGN is supposed to be intermittent and to inject populations of buoyant bubbles through a succession of outbursts. We also study the X-ray-cool component detected in the radio lobes and suggest that it is structured in blobs that are tied to the radio buoyant bubbles.

Ghizzardi, Simona; Molendi, Silvano; Pizzolato, Fabio; De Grandi, Sabrina

2004-07-01

200

Magnetogasdynamic shock waves in a nonideal gas with heat conduction and radiation heat flux  

NASA Astrophysics Data System (ADS)

The purpose of this study is to obtain a self-similar solution of the problem of propagation of a magnetogasdynamic shock wave in a nonideal gas with heat conduction and radiation heat flux in the presence of a spatially decreasing azimuthal magnetic field strength. The initial density of the medium is assumed to be constant. The heat conduction is expressed in terms of Fourier's law, and the radiation is considered to be of a diffusion type for an optically thick gray gas model. The thermal conductivity and absorption coefficients are assumed to vary with temperature and density. The shock is assumed to be driven by a piston moving with a variable velocity. Similarity solutions are obtained, and the effects of variation of the gas nonidealness parameter and Alfven-Mach number on the flow field behind the shock are investigated.

Singh, K. K.; Nath, B.

2012-09-01

201

Homogeneous thermal cloak with constant conductivity and tunable heat localization.  

PubMed

Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and finite conductivity only employing naturally available materials. It is demonstrated that the thermal localization inside the coating layer can be tuned and controlled robustly by anisotropy, which enables an incomplete cloak to function perfectly. Practical realization of such homogeneous thermal cloak has been suggested by using two naturally occurring conductive materials, which provides an unprecedentedly plausible way to flexibly realize thermal cloak and manipulate heat flow with phonons. PMID:23549139

Han, Tiancheng; Yuan, Tao; Li, Baowen; Qiu, Cheng-Wei

2013-01-01

202

Homogeneous Thermal Cloak with Constant Conductivity and Tunable Heat Localization  

NASA Astrophysics Data System (ADS)

Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and finite conductivity only employing naturally available materials. It is demonstrated that the thermal localization inside the coating layer can be tuned and controlled robustly by anisotropy, which enables an incomplete cloak to function perfectly. Practical realization of such homogeneous thermal cloak has been suggested by using two naturally occurring conductive materials, which provides an unprecedentedly plausible way to flexibly realize thermal cloak and manipulate heat flow with phonons.

Han, Tiancheng; Yuan, Tao; Li, Baowen; Qiu, Cheng-Wei

2013-04-01

203

3-D lithium ion microbattery  

NASA Astrophysics Data System (ADS)

The lithium-ion battery has emerged as a common power source for portable consumer electronics since its debut two decades ago. Due to the low atomic weight and high electrochemical activity of lithium chemistry, lithium-ion battery has a higher energy density as compared to other battery systems, such as Ni-Cd, Ni-MH, and lead-acid batteries. As a result, use of lithium-ion batteries enables the size of batteries to be effectively reduced without compromising capacity. More importantly, as battery size is reduced, it enhances the applications of portable electronics, increasing the convenience of use. The 3-D battery architecture described in the dissertation is believed to be a new paradigm for future batteries. The architecture features coupled 3-D electrodes to provide better charge/discharge kinetics and a higher charge capacity per footprint area. The overarching objective of this dissertation is to implement the 3-D architecture using the lithium-ion chemistry. The 3-D lithium-ion batteries are designed to provide high areal energy density without compromising power density. The dissertation is comprised of four interrelated sections. First, a simulation was conducted to identify key battery parameters and to define an ideal three-dimensional cell structure. The second part of the research involved identifying fabrication routes to build the 3-D electrode, which was the key design element in the 3-D paradigm. The third part of the dissertation was to correlate the electrode performance with its geometric features. In particular, the influence of aspect ratio was investigated. Lastly, an electrolyte/separator was designed and fabricated based on the existing 3-D electrode configuration. This enabled 3-D battery to be assembled.

Yeh, Yuting

204

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Astrophysics Data System (ADS)

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling converter provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling engine. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140° C while the heat losses caused by the addition of the VCHP are 1.8 W.

Tarau, Calin; Walker, Kara L.; Anderson, William G.

2009-03-01

205

Application of inverse heat conduction problem on temperature measurement  

NASA Astrophysics Data System (ADS)

For regenerative cooling devices, such as G-M refrigerator, pulse tube cooler or thermoacoustic cooler, the gas oscillating bring about temperature fluctuations inevitably, which is harmful in many applications requiring high stable temperatures. To find out the oscillating mechanism of the cooling temperature and improve the temperature stability of cooler, the inner temperature of the cold head has to be measured. However, it is difficult to measure the inner oscillating temperature of the cold head directly because the invasive temperature detectors may disturb the oscillating flow. Fortunately, the outer surface temperature of the cold head can be measured accurately by invasive temperature measurement techniques. In this paper, a mathematical model of inverse heat conduction problem is presented to identify the inner surface oscillating temperature of cold head according to the measured temperature of the outer surface in a GM cryocooler. Inverse heat conduction problem will be solved using control volume approach. Outer surface oscillating temperature could be used as input conditions of inverse problem and the inner surface oscillating temperature of cold head can be inversely obtained. A simple uncertainty analysis of the oscillating temperature measurement also will be provided.

Zhang, X.; Zhou, G.; Dong, B.; Li, Q.; Liu, L. Q.

2013-09-01

206

3D Motifs  

Microsoft Academic Search

Three-dimensional (3D) motifs are patterns of local structure associated with function, typically based on residues in binding\\u000a or catalytic sites. Protein structures of unknown function can be annotated by comparing them to known 3D motifs. Many methods\\u000a have been developed for identifying 3D motifs and for searching structures for their occurrence. Approaches vary in the type\\u000a and amount of input

Elaine C. Meng; Benjamin J. Polacco; Patricia C. Babbitt

207

Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Astrophysics Data System (ADS)

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) was designed to allow multiple stops and restarts of the Stirling engine. A VCHP was designed for the Advanced Stirling Radioisotope Generator, with a 850 °C heater head temperature. The VCHP turns on with a ?T of 30 °C, which is high enough to not risk standard ASRG operation but low enough to save most heater head life. This VCHP has a low mass, and low thermal losses for normal operation. In addition to the design, a proof-of-concept NaK VCHP was fabricated and tested. While NaK is normally not used in heat pipes, it has an advantage in that it is liquid at the reservoir operating temperature, while Na or K alone would freeze. The VCHP had two condensers, one simulating the heater head, and the other simulating the radiator. The experiments successfully demonstrated operation with the simulated heater head condenser off and on, while allowing the reservoir temperature to vary over 40 to 120 °C, the maximum range expected. In agreement with previous NaK heat pipe tests, the evaporator ?T was roughly 70 °C, due to distillation of the NaK in the evaporator.

Anderson, William G.; Tarau, Calin

2008-01-01

208

TNF\\/S C3\\/D CONDUCT: A simulation model of the Army's command, control, communications, and intelligence (C3I) process  

Microsoft Academic Search

A computer model (CONDUCT) has been developed that simulates corps and subordinate command, control, communications, and intelligence C3I functions with particular emphasis on the integration of the new generation of intelligence, surveillance, and target-acquisition systems within the developing 1982 and 1986 force structure. CONDUCT is an event-by-event simulation model written in GPSS-V (General Purpose Simulation System), representing the combat and

T. V. Noon; E. Marx

1981-01-01

209

Microbeam Beam Heating Analysis of Thin Foils Using Heat Conduction Theory  

Microsoft Academic Search

The temperature distribution in and near the scan region of an ion microbeam is estimated using heat conduction theory. In the calculation, the energy deposited by a beam spot on a thin foil is treated as a point energy source. The spatial and time dependent temperature contributions from energy deposited by the ion beam rastering in a square scan pattern

B. Lovelace; A. W. Haberl; H. Bakhru; J. C. Kimball; R. E. Benenson

2009-01-01

210

3D Imaging.  

ERIC Educational Resources Information Center

|Discusses 3 D imaging as it relates to digital representations in virtual library collections. Highlights include X-ray computed tomography (X-ray CT); the National Science Foundation (NSF) Digital Library Initiatives; output peripherals; image retrieval systems, including metadata; and applications of 3 D imaging for libraries and museums. (LRW)|

Hastings, S. K.

2002-01-01

211

3D seismic inversion.  

National Technical Information Service (NTIS)

The research results from the 3D inversion have been made into products already available on the market. The new products are used both within the EU and in the rest of the world. The two partners in the 3D inversion project have launched two different pr...

K. Bolding Rasmussen J. Moerch Pedersen S. Gluck E. Juve

1997-01-01

212

3D Imaging.  

ERIC Educational Resources Information Center

Discusses 3 D imaging as it relates to digital representations in virtual library collections. Highlights include X-ray computed tomography (X-ray CT); the National Science Foundation (NSF) Digital Library Initiatives; output peripherals; image retrieval systems, including metadata; and applications of 3 D imaging for libraries and museums. (LRW)

Hastings, S. K.

2002-01-01

213

Holographic 3-D printer  

Microsoft Academic Search

This paper proposes a holographic printer, which produces 3-D hard copies of computer processed objects. For the purpose of automatic making of 3-D hard copies of distortion free, a new method to synthesize holographic stereogram is proposed. It is is flat format and lippmann type holographic stereogram which can be printed by one optical step. The proposed hologram has not

Masahiro Yamaguchi; Nagaaki Ohyama; Toshio Honda

1990-01-01

214

3D Slicer  

Microsoft Academic Search

To be applied to practical clinical research problems, medical image computing software requires infrastructure including routines to read and write various file formats, manipulate 2D and 3D coordinate systems, and present a consistent user interface paradigm and visualization metaphor. At the same time, research software needs to be flexible to facilitate implementation of new ideas. 3D Slicer is a project

Stephen D. Pieper; Michael Halle; Ron Kikinis

2004-01-01

215

Current fluctuations in a two dimensional model of heat conduction  

NASA Astrophysics Data System (ADS)

In this work we study numerically and analytically current fluctuations in the two-dimensional Kipnis-Marchioro-Presutti (KMP) model of heat conduction. For that purpose, we use a recently introduced algorithm which allows the direct evaluation of large deviations functions. We compare our results with predictions based on the Hydrodynamic Fluctuation Theory (HFT) of Bertini and coworkers, finding very good agreement in a wide interval of current fluctuations. We also verify the existence of a well-defined temperature profile associated to a given current fluctuation which depends exclusively on the magnitude of the current vector, not on its orientation. This confirms the recently introduced Isometric Fluctuation Relation (IFR), which results from the time-reversibility of the dynamics, and includes as a particular instance the Gallavotti-Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by timereversibility on the statistics of nonequilibrium fluctuations.

Pérez-Espigares, Carlos; Garrido, Pedro L.; Hurtado, Pablo I.

2011-03-01

216

THERM: A three-dimensional transient heat conduction computer program  

SciTech Connect

THERM is a three-dimensional finite-element computer program for solving transient heat conduction problems. This report presents the techniques used to develop THERM. The theory described consists of a governing equation, boundary conditions, and an equivalent variational principle. The matrix equations used in THERM are derived using both vector and tensor analysis. These equations used finite-element approximations for the geometry and a finite-difference approximation for the time. THERM has finite-element formulations using both Cartesian or cylindrical coordinates. Several example problems are included to demonstrate that the THERM formulations are correct and that THERM can be used to solve meaningful problems. 7 refs., 4 figs., 6 tabs.

Cook, W.A.

1991-10-01

217

A casting based process to fabricate 3D alginate scaffolds and to investigate the influence of heat transfer on pore architecture during fabrication  

Microsoft Academic Search

The fabrication of 3-dimensional (3D) tissue scaffolds is a competitive approach to engineered tissues. An ideal tissue scaffold must be highly porous, biocompatible, biodegradable, easily processed and cost-effective, and have adequate mechanical properties. A casting based process has been developed in this study to fabricate 3D alginate tissue scaffolds. The alginate\\/calcium gluconate hydrogel was quenched in a glass mold and

W. M. Parks; Y. B. Guo

2008-01-01

218

Endogenic heat from Enceladus' south polar fractures: New observations, and models of conductive surface heating  

NASA Astrophysics Data System (ADS)

Linear features dubbed “tiger stripes” in the south polar region of Enceladus have anomalously high heat fluxes and are the apparent source of the observed plume. Several explanations for the observed activity have been proposed, including venting from a subsurface reservoir of liquid water, sublimation of surface ice, dissociation of clathrates, and shear heating. Thermal modeling presented in this work, coupled with observations from the Cassini Composite Infrared Spectrometer (CIRS) instrument, seeks to elucidate the underlying physical mechanism by constraining vent temperatures and thermal emission sources, using a model in which the observed thermal signature results primarily from conductive heating of the surface by warm subsurface fractures. The fractures feed surface vents, which may themselves contribute to the observed thermal emission. Model variables include vent temperature, presence of a surface insulating layer, vent width, time-variable heat input, and heat sources other than the central vent. Results indicate that CIRS spectra are best fitted with a model in which the surface is heated by narrow vents at temperatures as high as 223 K. Although equally good fits can be obtained for vent temperatures in the range of 130 to 155 K if the vents are wider (180 m and 22 m respectively) and dominate the emission spectrum, these models are probably less realistic because vents with these temperatures and widths cannot supply the observed H2O vapor flux. The lack of emission angle dependence of the thermal emission when July 2005 and November 2006 CIRS observations are compared also argues against thermal emission being dominated by the vents themselves. Thus, results favor high-temperature models, possibly venting from a subsurface liquid water reservoir. However, a fracture filled with liquid water near the surface would produce significantly higher radiances than were detected unless masked by a thermally insulating surface layer. Models that best match the CIRS data are characterized by small fractions of the surface at high temperatures, which strengthens the case for the vents and/or their conductively-heated margins being the primary heat source. Models where the thermal emission is dominated by conductive heating of the surface from below by a laterally-extensive buried heat source cannot reproduce the observed spectrum. Models with a 10 cm thick upper insulating layer produce a poor match to the CIRS spectra, suggesting high thermal inertias near the tiger stripes. Finally, tiger stripe thermal emission measured by CIRS varied by less than 15% over the 16 month period from July 2005 to November 2006.

Abramov, Oleg; Spencer, John R.

2009-01-01

219

A continuum voxel approach to model flow in 3D fault networks: A new way to obtain up-scaled hydraulic conductivity tensors of grid cells  

NASA Astrophysics Data System (ADS)

An accurate mapping of discrete fracture networks onto a regular mesh is obtained.A full hydraulic conductivity tensor in each mesh is needed to model fracture fluxes.Hydraulic properties preserve continuity of fluxes between neighbouring meshes.Various hydraulic behaviour at fracture intersections can be modelled.

Fourno, André; Grenier, Christophe; Benabderrahmane, Abdelhakim; Delay, Frederick

2013-06-01

220

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

SciTech Connect

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling converter provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling engine. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140 deg. C while the heat losses caused by the addition of the VCHP are 1.8 W.

Tarau, Calin; Walker, Kara L.; Anderson, William G. [Advanced Cooling Technologies, Inc. 1046 New Holland Ave. Lancaster, PA 17601 (United States)

2009-03-16

221

77 FR 74027 - Certain Integrated Circuit Packages Provided with Multiple Heat-Conducting Paths and Products...  

Federal Register 2010, 2011, 2012, 2013

...Integrated Circuit Packages Provided with Multiple Heat- Conducting Paths and Products Containing Same; Commission Determination...integrated circuit packages provided with multiple heat-conducting paths and products containing same by reason of...

2012-12-12

222

Computational fluid dynamics analyses of lateral heat conduction, coolant azimuthal mixing and heat transfer predictions in a BR2 fuel assembly geometry.  

SciTech Connect

To support the analyses related to the conversion of the BR2 core from highly-enriched (HEU) to low-enriched (LEU) fuel, the thermal-hydraulics codes PLTEMP and RELAP-3D are used to evaluate the safety margins during steady-state operation (PLTEMP), as well as after a loss-of-flow, loss-of-pressure, or a loss of coolant event (RELAP). In the 1-D PLTEMP and RELAP simulations, conduction in the azimuthal and axial directions is not accounted. The very good thermal conductivity of the cladding and the fuel meat and significant temperature gradients in the lateral directions (axial and azimuthal directions) could lead to a heat flux distribution that is significantly different than the power distribution. To evaluate the significance of the lateral heat conduction, 3-D computational fluid dynamics (CFD) simulations, using the CFD code STAR-CD, were performed. Safety margin calculations are typically performed for a hot stripe, i.e., an azimuthal region of the fuel plates/coolant channel containing the power peak. In a RELAP model, for example, a channel between two plates could be divided into a number of RELAP channels (stripes) in the azimuthal direction. In a PLTEMP model, the effect of azimuthal power peaking could be taken into account by using engineering factors. However, if the thermal mixing in the azimuthal direction of a coolant channel is significant, a stripping approach could be overly conservative by not taking into account this mixing. STAR-CD simulations were also performed to study the thermal mixing in the coolant. Section II of this document presents the results of the analyses of the lateral heat conduction and azimuthal thermal mixing in a coolant channel. Finally, PLTEMP and RELAP simulations rely on the use of correlations to determine heat transfer coefficients. Previous analyses showed that the Dittus-Boelter correlation gives significantly more conservative (lower) predictions than the correlations of Sieder-Tate and Petukhov. STAR-CD 3-D simulations were performed to compare heat transfer predictions from CFD and the correlations. Section III of this document presents the results of this analysis.

Tzanos, C. P.; Dionne, B. (Nuclear Engineering Division)

2011-05-23

223

INFLUENCE OF MASHED POTATO DIELECTRIC PROPERTIES AND CIRCULATING WATER ELECTRIC CONDUCTIVITY ON RADIO FREQUENCY HEATING  

Microsoft Academic Search

Experiments and computer simulations were conducted to systematically investigate the influence of mashed potato dielectric properties and circulating water electric conductivity on electromagnetic field distribution, heating rate, and heating pattern in packaged food during radio frequency (RF) heating processes in a 6 kW, 27 MHz laboratory scale RF heating system. Both experimental and simulation results indicated that for the selected

Jian Wang; Robert G. Olsen; Juming Tang; Zhongwei Tang

224

An experimental and numerical study of an air-to-air heat exchanger using liquid reservoir variable conductance heat pipes  

Microsoft Academic Search

This report documents a study of a prototype air-to-air heat exchanger of which the thermal conductivity is governed by the reservoir temperature of the heat pipes. The work is introduced with a brief review of the basic operating principles of heat pipes and of the various existing schemes for variable conductance. An experimental facility, incorporating a computerized data acquisition system,

S. Drouilhet; J. M. Buchlin

1982-01-01

225

Autostereoscopic 3D Display  

NASA Astrophysics Data System (ADS)

Display technology has made big advances in last years. Displays are flat, offer high resolution, are bright, fast and almost free of flicker. Apart from new technologies that make displays still more affordable the major direction of development turns to applications, especially TV. In this consolidation process new features are sought. Still lacking is the 3D display capability most obvious compared to viewing real-world scenes. In the last decades a lot of new 3D technologies have been proposed, developed and only few have reached the commercial market. A breakthrough into the mass market has been prevented for technical as well as commercial reasons. Most natural viewing is provided by holography. Unfortunately, even the technical challenges are so demanding that the 3D research community turned to the stereoscopic technology known for more than a century. Many technologies have been proposed and the shutter technique has already matured to a commercial product. But the mass market requires 3D viewing without using additional viewing aids. Currently, these Autostereoscopic 3D Displays still cannot meet the quality standard and comfort of today's 2D displays. In our opinion 3D displays should first of all match all of today's 2D demands and additionally be capable of 3D displaying.

Schwerdtner, Armin

2006-02-01

226

77 FR 33486 - Certain Integrated Circuit Packages Provided With Multiple Heat-Conducting Paths and Products...  

Federal Register 2010, 2011, 2012, 2013

...Packages Provided With Multiple Heat- Conducting Paths and Products...Packages Provided With Multiple Heat-Conducting Paths and Products...packages provided with multiple heat-conducting paths and products...confidence must request confidential treatment. All such requests should...

2012-06-06

227

Generalized heat conduction laws based on thermomass theory and phonon hydrodynamics  

Microsoft Academic Search

The Fourier's law of heat conduction is invalid in extreme conditions, such as the second sound in solids and anomalous heat conduction in nanosystems. The generalized heat conduction law with nonlinear and nonlocal effects is derived from both macroscopic thermomass theory and microscopic phonon Boltzmann method in this paper. The coincidence between thermomass theory and phonon hydrodynamics is also analyzed

Yuan Dong; Bing-Yang Cao; Zeng-Yuan Guo

2011-01-01

228

Constructal trees of circular fins for conductive and convective heat transfer  

Microsoft Academic Search

This paper extends to three dimensions and to convective heat transfer the constructal method of minimizing the thermal resistance between a volume and one point. In the first part of the paper, the heat flow mechanism is conduction, and the heat generating volume is occupied by low conductivity material (k0) and high conductivity inserts (kp). At the elemental-volume level the

A. Alebrahim; A. Bejan

1999-01-01

229

The effect of correlations on the non-ohmic behavior of the small-polaron hopping conductivity in 1D and 3D disordered systems.  

PubMed

According to percolation theory the investigation of charge transport in disordered systems is equivalent to the study of the possibility of the passage of the carriers through a random network of impedances which interconnect the different lattice sites. When the site energies are not the same, the energy of a site affects the incoming as well as the outgoing impedances connected to the given site and this gives rise to correlations between neighboring impedances. This new condition characterizes the transport process and imposes the evaluation of the average number of sites accessible by a bond from a given site for all possible configurations of sites that satisfy the percolation condition. The generalized molecular crystal model, appropriate for the study of small-polaron hopping transport in disordered systems, and the Kubo formula permit the evaluation of these impedances. Taking correlations into account, theoretical percolation considerations applicable to one-dimensional and three-dimensional disordered systems, lead to analytical expressions for the temperature and electric field dependence of the DC conductivity at high (multi-phonon-assisted hopping) and low (few-phonon-assisted hopping) temperatures. The theoretical analysis reveals the effect of correlations on the non-ohmic behavior of the small-polaron hopping conductivity and permits the evaluation of the maximum hopping distance. Quantitative estimates of this effect are presented comparing the theoretical results, including correlations with those ignoring them, previously reported, applying them to recent experimental data for a wide temperature range and from low up to moderate electric fields. PMID:21403284

Dimakogianni, M; Triberis, G P

2010-08-13

230

The conjugate conduction–natural convection heat transfer along a thin vertical plate with non-uniform internal heat generation  

Microsoft Academic Search

The steady state heat transfer characteristics of a thin vertical strip with internal heat generation is studied in this work. The nondimensional temperature distribution in the strip is obtained as a function of the following parameters: (a) the intensity and distribution of the internal heat sources, (b) the aspect ratio of the strip, (c) the longitudinal heat conductance of the

F Méndez; C Treviño

2000-01-01

231

Accuracy in thermal contact conductance experiments - the effect of heat losses to the surroundings  

Microsoft Academic Search

A major source of uncertainty in contact heat transfer experiments is the heat loss from the specimens to the surroundings by convection, conduction and radiation. A detailed analysis is presented comparing the resistance to heat transfer across the joint to the resistance to heat flow from the specimens to the surroundings. It is shown that the heat losses may be

C. V. Madhusudana

2000-01-01

232

Enhanced electron extraction from template-free 3D nanoparticulate transparent conducting oxide (TCO) electrodes for dye-sensitized solar cells.  

PubMed

The semiconducting metal oxide-based photoanodes in the most efficient dye-sensitized solar cells (DSSCs) desires a low doping level to promote charge separation, which, however, limits the subsequent electron extraction in the slow diffusion regime. These conflicts are mitigated in a new photoanode design that decouples the charge separation and extraction functions. A three-dimensional highly doped fluorinated SnO(2) (FTO) nanoparticulate film serves as conductive core for low-resistance and drift-assisted charge extraction while a thin, low-doped conformal TiO(2) shell maintains a large resistance to recombination (and therefore long charge lifetime). EIS reveals that the electron transit time is reduced by orders of magnitude, whereas the recombination resistance remains in the range of traditional nanoparticle TiO(2) photoelectrodes. PMID:22834639

Yang, Zhenzhen; Gao, Shanmin; Li, Tao; Liu, Fa-Qian; Ren, Yang; Xu, Tao

2012-08-03

233

3D Transmographer  

NSDL National Science Digital Library

Build your own polygon and transform it in the Cartesian coordinate system. Experiment with reflections across any line, revolving around any line (which yields a 3-D image), rotations about any point, and translations in any direction.

234

Thermal conductivity of cementitious grouts and impact on heat exchanger length design for ground source heat pumps  

Microsoft Academic Search

Design length and performance of heat exchangers for ground source heat pumps strongly depend on the thermal conductivity of the backfill material. Laboratory studies were undertaken to determine means of improving thermal conductivity of cementitious backfill grouts. The influence of fillers and admixtures was examined. Significant improvement of grout thermal conductivity was readily achieved through appropriate materials selection and mix

M. L. Allan; S. P. Kavanaugh

2000-01-01

235

Thermal Conductivity of Cementitious Grouts and Impact On Heat Exchanger Length Design for Ground Source Heat Pumps  

Microsoft Academic Search

Design length and performance of heat exchangers for ground source heat pumps strongly depend on the thermal conductivity of the backfill material. Laboratory studies were undertaken to determine means of improving thermal conductivity of cementitious backfill grouts. The influence of fillers and admixtures was examined. Significant improvement of grout thermal conductivity was readily achieved through appropriate materials selection and mix

Marita L. Allan; Steve P. Kavanaugh

1999-01-01

236

TRACE 3-D documentation  

SciTech Connect

TRACE 3-D is an interactive beam-dynamics program that calculates the envelopes of a bunched beam, including linear space-charge forces, through a user-defined transport system. TRACE 3-D provides an immediate graphics display of the envelopes and the phase-space ellipses and allows nine types of beam-matching options. This report describes the beam-dynamics calculations and gives detailed instruction for using the code. Several examples are described in detail.

Crandall, K.R.

1987-08-01

237

3D Video Recorder  

Microsoft Academic Search

We present the 3D Video Recorder, a system capable of recording, processing, and playing three-dimensional video from multiple points of view. We first record 2D video streams from several synchronized digital video cameras and store pre-processed images to disk. An off-line process- ing stage converts these images into a time-varying three- dimensional hierarchical point-based data structure and stores this 3D

Stephan Würmlin; Edouard Lamboray; Oliver G. Staadt; Markus H. Gross

2002-01-01

238

DYNA3D  

Microsoft Academic Search

DYNA3D is an explicit, three-dimensional, finite element program for analyzing the large deformation dynamic response of inelastic solids and structures. DYNA3D contains 30 material models and 10 equations of state (EOS) to cover a wide range of material behavior. The material models implemented are: elastic, orthotropic elastic, kinematic\\/isotropic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, Blatz-Ko rubber, high explosive

1989-01-01

239

Multiplatform 3-D Graphics  

Microsoft Academic Search

The focus of our research is enabling the users to interact with three-dimensional (3-D) graphics and interactive applications with the same content, appearance, and interaction paradigm on different platforms [Internet, television (TV), and mobile devices]. The main contribution of this article is the design and implementation of a platform-dependent architecture for 3-D graphics and content, validated in the entertainment and

Maria del Puy Carretero; Amalia Ortiz; David Oyarzun; Isabel Torre; Maria Linaza; Alejandro Garcia-Alonso

2010-01-01

240

Infrared nerve stimulation: modelling of photon transport and heat conduction  

NASA Astrophysics Data System (ADS)

Infrared neural stimulation (INS) is a novel technique for stimulating neurons with infrared light, rather than the traditional electrical means. There has been significant discussion in the literature on the mechanisms behind INS, while recent work has shown that infrared light stimulates neurons by causing a reversible change in their membrane capacitance. Nevertheless, the effect of different laser parameters on neuronal responses is still not well understood. To better understand this and to assist in designing light delivery systems, modelling of spatial and temporal characteristics of light delivery during INS has been performed. Monte Carlo modelling of photon transport in tissue allows the spatial characteristics of light to be determined during INS and allows comparisons of varying geometries and fibre designs. Finite element analysis of heat conduction can then be used to reveal the behavior of different pulse durations and the resulting temperature decay. The combination of the two methods allows for further insights into the mechanisms of INS and assists in understanding different mechanisms which promote INS. The model suggests there may be two regimes of INS, namely temperature limited for pulses under 100 ?s and temperature gradient limited for longer pulses. this is compatible with previously published data, but requires further experimentation for confirmation. The model also provides a tool for optimising the design of emitters and implants.

Thompson, Alexander C.; Wade, Scott A.; Cadusch, Peter J.; Brown, William G. A.; Stoddart, Paul R.

2013-02-01

241

Examination of Up-Down Asymmetry Effects on CQL3D Calculation of ECCD and Multi-Species FW Heating in the DIII-D Tokamak  

NASA Astrophysics Data System (ADS)

The CQL3D Fokker-Planck code [1] which calculates the 3D (r, v, v//), time-dependent electron and ion distributions has been recently upgraded to include effects of non-up-down symmetry, and also to simulate simultaneous quasilinear diffusion of multiple ion species. We make applications to two types of previous modeling of the DIII-D experiment: (1) ECCD, now particularly as regards effects on up-down asymmetric equilibria; and (2) D/minority-H modeling of a canonical DIII-D fast wave shot. Code modification issues, and results for ECCD and the effects of minority-H on the higher harmonic ion absorption of the FW, are presented. [4pt] [1] R.W. Harvey and M. McCoy, The CQL3D Fokker Planck Code, Proceedings of the IAEA Technical Committee Meeting on Simulation and Modeling of Thermonuclear Plasmas, Montreal, Canada, 1992; also, http://www.compxco.com/cql3d.html.

Harvey, R. W.; Prater, R.; Jaeger, E. F.

2009-11-01

242

Regional geothermal 3D modelling in Denmark  

NASA Astrophysics Data System (ADS)

In the pursuit of sustainable and low carbon emission energy sources, increased global attention has been given to the exploration and exploitation of geothermal resources within recent decades. In 2009 a national multi-disciplinary geothermal research project was established. As a significant part of this project, 3D temperature modelling is to be carried out, with special emphasis on temperatures of potential geothermal reservoirs in the Danish area. The Danish subsurface encompasses low enthalpy geothermal reservoirs of mainly Triassic and Jurassic age. Geothermal plants at Amager (Copenhagen) and Thisted (Northern Jutland) have the capacity of supplying the district heating network with up to 14 MW and 7 MW, respectively, by withdrawing warm pore water from the Gassum (Lower Jurassic/Upper Triassic) and Bunter (Lower Triassic) sandstone reservoirs, respectively. Explorative studies of the subsurface temperature regime typically are based on a combination of observations and modelling. In this study, the open-source groundwater modelling code MODFLOW is modified to simulate the subsurface temperature distribution in three dimensions by taking advantage of the mathematical similarity between saturated groundwater flow (Darcy flow) and heat conduction. A numerical model of the subsurface geology in Denmark is built and parameterized from lithological information derived from joint interpretation of seismic surveys and borehole information. Boundary conditions are constructed from knowledge about the heat flow from the Earth's interior and the shallow ground temperature. Matrix thermal conductivities have been estimated from analysis of high-resolution temperature logs measured in deep wells and porosity-depth relations are included using interpreted main lithologies. The model takes into account the dependency of temperature and pressure on thermal conductivity. Moreover, a transient model based correction of the paleoclimatic thermal disturbance caused by the Weichselian glaciation is included in the model procedure. The ability of MODFLOW for simulating heat conduction is demonstrated in simple test cases. The regional geothermal model is then utilized for modelling the subsurface temperature distribution and contouring updated temperature maps for geothermal reservoirs in Denmark.

Poulsen, S. E.; Balling, N.; Bording, T. S.; Nielsen, S. B.

2012-04-01

243

Heat removal of in-tube viscous flows to air with the assistance of arrays of plate fins Part I: theoretical aspects involving 3-D, 2-D and 1-D models  

Microsoft Academic Search

A detailed comparative study of the heat transfer augmentation of in-tube flows accounting for an array of equally-spaced plate fins attached at the outer surface is undertaken. The aim of the paper is to critically examine the thermal response of this kind of finned tubes to three different mathematical models: a complete 3-D distributed model, a reduced 2-D distributed\\/lumped hybrid

Antonio Campo

2000-01-01

244

Simulation-based analysis of the Heat-Affected Zone during target preparation by pulsed- laser ablation through stacked silicon dies in 3D integrated System-in-Packages  

Microsoft Academic Search

The trends of 3D integration and System-in-Package (SiP) require the adaptation of target preparation methods for failure analysis of these complex integrated devices. Recent improvements in laser-based target preparation make laser cross-sections through several stacked silicon dies possible with remarkably small visible Heat-Affected Zones (HAZs). The distinct removal of Molding Compound (MC), silicon dies, and metal interconnects with a single

S. Martens; M. Fink; W. Mack; F. Voelklein; J. Wilde

2010-01-01

245

3D SLAM for planetary worksite mapping  

Microsoft Academic Search

In this paper, we present a robust framework suitable for conducting three-dimensional Simultaneous Lo- calization and Mapping (3D SLAM) in a planetary worksite environment. By utilizing a laser rangefinder mounted on a rover platform, we have demonstrated an approach that is able to create globally consistent maps of natural, unstructured 3D terrain. The framework presented in this paper utilizes a

Chi Hay Tong; Timothy D. Barfoot; Erick Dupuis

2011-01-01

246

Microbeam Beam Heating Analysis of Thin Foils Using Heat Conduction Theory  

SciTech Connect

The temperature distribution in and near the scan region of an ion microbeam is estimated using heat conduction theory. In the calculation, the energy deposited by a beam spot on a thin foil is treated as a point energy source. The spatial and time dependent temperature contributions from energy deposited by the ion beam rastering in a square scan pattern were then computed. The results showed that for poor conductors, the temperature of the material under the scan region can rise rapidly by up to two orders of magnitude, while that of good conductors remains virtually unchanged. The calculated results were consistent with experimental data where Mylar foils were scanned using an He microbeam and the time for melt through was measured. Radiational cooling effects were also investigated and found to contribute little to the heat losses at typical microbeam beam powers.

Lovelace, B.; Haberl, A. W. [Ion Beam Laboratory, University at Albany, 1400 Washington Ave., Albany NY 12222 (United States); Bakhru, H. [College of Nanoscale Science and Engineering, University at Albany, 1400 Washington Ave., Albany NY 12203 (United States); Kimball, J. C.; Benenson, R. E. [Physics Department, University at Albany, 1400 Washington Ave., Albany NY 12222 (United States)

2009-03-10

247

Temperature dependent electrical conductivities of fruit purees during ohmic heating  

Microsoft Academic Search

Ohmic heating takes its name from Ohm’s law; the food material switched between electrodes has a role of resistance in the circuit. In this study, the apricot and peach purees were heated on a laboratory scale static ohmic heater by applying voltage gradients in the range of 20–70 V\\/cm. The voltage gradient was statistically significant on the ohmic heating rates

Filiz Icier; Coskan Ilicali

2005-01-01

248

3-D Terrain Corrections to Heat Flow Data, Topographically-Driven Groundwater Flow, and the Strength of the San Andreas Fault at Parkfield, CA  

Microsoft Academic Search

The lack of a detectable heat flow anomaly along the San Andreas Fault (SAF) constitutes one important piece of evidence used to argue that the fault supports low shear stresses (<20 MPa averaged over the upper 10 km). However, key uncertainties in existing heat flow data, such as the effects of heat advection by topographically-driven groundwater flow, topographic refraction (terrain

P. M. Fulton; D. M. Saffer; B. A. Bekins; R. N. Harris

2003-01-01

249

Enhancement of Heat Transfer with Porous\\/Solid Insert for Laminar Flow of a Participating Gas in a 3-D Square Duct  

Microsoft Academic Search

In recent years, porous or solid insert has been used in a duct for enhancing heat transfer in high temperature thermal equipment, where both convective and radiative heat transfer play a major role. In the present work, the study of heat transfer enhancement is carried out for flow through a square duct with a porous or a solid insert. Most

P. Parthasarathy; Prabal Talukdar; V. Ratna Kishore

2009-01-01

250

Thermal flywheel effects on the time varying conduction heat transfer through structural walls  

Microsoft Academic Search

Wall time varying conduction heat transfer investigations are very important for the prediction of heating and cooling loads in air conditioning practice and absolutely essential to the passive solar heating design. The walls store heat, absorb and dissipate a fraction of it and transmit the rest into the conditioned space at a later time, which depends on the wall thermal

P. T Tsilingiris

2003-01-01

251

Performance of a variable conductance heat pipe heat exchanger. Final scientific report, 15 May 1982-14 February 1983  

Microsoft Academic Search

The primary objective of the work is to evaluate the performance of an air to air variable conductance heat pipe heat exchanger (VCHPHX). This type of heat exchanger is of particular interest to the commercial aircraft industry because of its unique control system. The results from this research will help to provide the engineer with experimental data necessary to design

Chancelor

1983-01-01

252

Application of CESE method to simulate non-Fourier heat conduction in finite medium with pulse surface heating  

Microsoft Academic Search

This study employs the space–time conservation element and solution element (CESE) method to simulate the temperature and heat flux distributions in a finite medium subject to various non-Fourier heat conduction models. The simulations consider three specific cases, namely a single phase lag (SPL) thermal wave model with a pulsed temperature condition, a SPL model with a surface heat flux input,

Yin Chou; Ruey-Jen Yang

2008-01-01

253

Mechanical behavior of bolted joints under steady heat conduction  

Microsoft Academic Search

Bolted joints in heat exchangers, cylinder heads in combustion engines, and so on are subjected in heat fluxes. It is necessary to examine the mechanical behavior of such bolted joints under thermal changes in order to establish an optimal design. This paper deals with mechanical behavior of bolted joints, in which two hollow cylinders and two rectangular thick plates made

H. Kumano; T. Sawa; T. Hirose

1994-01-01

254

3-D Cardboard Busts.  

ERIC Educational Resources Information Center

Provides a lesson for a high school art course on three-dimensional design. Based on a portrait bust by Naum Gabo, the project involves the construction of a 3-D portrait bust using railroad board. Describes techniques that students will need to be taught before beginning. (DSK)

Payne, Debra

1998-01-01

255

3D reservoir visualization  

SciTech Connect

This paper shows how some simple 3D computer graphics tools can be combined to provide efficient software for visualizing and analyzing data obtained from reservoir simulators and geological simulations. The animation and interactive capabilities of the software quickly provide a deep understanding of the fluid-flow behavior and an accurate idea of the internal architecture of a reservoir.

Van, B.T.; Pajon, J.L.; Joseph, P. (Inst. Francais du Petrole (FR))

1991-11-01

256

Experimental investigation of plastic finned-tube heat exchangers, with emphasis on material thermal conductivity  

SciTech Connect

In this paper, two modified types of polypropylene (PP) with high thermal conductivity up to 2.3 W/m K and 16.5 W/m K are used to manufacture the finned-tube heat exchangers, which are prospected to be used in liquid desiccant air conditioning, heat recovery, water source heat pump, sea water desalination, etc. A third plastic heat exchanger is also manufactured with ordinary PP for validation and comparison. Experiments are carried out to determine the thermal performance of the plastic heat exchangers. It is found that the plastic finned-tube heat exchanger with thermal conductivity of 16.5 W/m K can achieve overall heat transfer coefficient of 34 W/m{sup 2} K. The experimental results are compared with calculation and they agree well with each other. Finally, the effect of material thermal conductivity on heat exchanger thermal performance is studied in detail. The results show that there is a threshold value of material thermal conductivity. Below this value improving thermal conductivity can considerably improve the heat exchanger performance while over this value improving thermal conductivity contributes very little to performance enhancement. For the finned-tube heat exchanger designed in this paper, when the plastic thermal conductivity can reach over 15 W/m K, it can achieve more than 95% of the titanium heat exchanger performance and 84% of the aluminum or copper heat exchanger performance with the same dimension. (author)

Chen, Lin; Li, Zhen; Guo, Zeng-Yuan [Department of Engineering Mechanics, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China)

2009-07-15

257

Constructal-theory network of conducting paths for cooling a heat generating volume  

Microsoft Academic Search

This paper develops a solution to the fundamental problem of how to collect and ‘channel’ to one point the heat generated volumetrically in a low conductivity volume of given size. The amount of high conductivity material that is available for building channels (high conductivity paths) through the volume is fixed. The total heat generation rate is also fixed. The solution

Adrian Bejan

1997-01-01

258

Transient heat conduction in one-dimensional composite slab. A ‘natural’ analytic approach  

Microsoft Academic Search

The transient response of one-dimensional multilayered composite conducting slabs to sudden variations of the temperature of the surrounding fluid is analysed. The solution is obtained applying the method of separation of variables to the heat conduction partial differential equation. In separating the variables, the thermal diffusivity is retained on the side of the modified heat conduction equation where the time-dependent

F. de Monte

2000-01-01

259

Numerical Methods to Solve the Two-Dimensional Heat Conduction Equation.  

National Technical Information Service (NTIS)

A class of numerical methods, called 'Hopscotch Algorithms', was used to solve the heat conduction equation in cylindrical geometry. Using a time dependent heat source, the temperature versus time behaviour of cylindric rod was analysed. Numerical simulat...

R. S. dos Santos

1981-01-01

260

A method of measuring the thermal conductivity of poor heat conductors under monotonic conditions  

Microsoft Academic Search

A method of measuring the thermal conductivity of poor heat conductors under monotonic conditions is described which enables one to make measurements on large specimens at different rates of heating and over a wide temperature range.

E. A. Tombasov; V. Ya. Cherepanov; P. S. Glazyrin; G. P. Polukeev; V. E. Chelmodeev

1978-01-01

261

Electrical conductivity of fruits and meats during ohmic heating  

Microsoft Academic Search

The design of effective ohmic heaters depends on the electrical conductivity of foods. Electrical conductivities of six different fresh fruits (red apple, golden apple, peach, pear, pineapple and strawberry) and several different cuts of three types of meat (chicken, pork and beef) were determined from room temperature through to the sterilization temperature range (25–140°C). In all cases, conductivities increased linearly

Sanjay Sarang; Sudhir K. Sastry; Lynn Knipe

2008-01-01

262

MPML3D: Scripting Agents for the 3D Internet.  

PubMed

The aim of this paper is two-fold. First, it describes a scripting language for specifying communicative behavior and interaction of computer-controlled agents ("bots") in the popular three-dimensional (3D) multi-user online world of "Second Life" and the emerging "OpenSimulator" project. While tools for designing avatars and in-world objects in Second Life exist, technology for non-programmer content creators of scenarios involving scripted agents is currently missing. Therefore, we have implemented new client software that controls bots based on the Multimodal Presentation Markup Language 3D (MPML3D), a highly expressive XML-based scripting language for controlling the verbal and non-verbal behavior of interacting animated agents. Second, the paper compares Second Life and OpenSimulator platforms and discusses the merits and limitations of each from the perspective of agent control. Here, we also conducted a small study that compares the network performance of both platforms. PMID:20479495

Prendinger, Helmut; Ullrich, Sebastian; Nakasone, Arturo; Ishizuka, Mitsuru

2010-04-30

263

Interactives: 3D Shapes  

NSDL National Science Digital Library

How much liquid can that glass hold? What are the dimensions of that package that's heading off to a friend overseas? Answers to both of those questions (and many more) can be found in this lovely interactive feature on 3D shapes created by experts at the Annenberg Media group. Visitors to this site will learn about three-dimensional geometric shapes by examining a number of objects through a number of interactive exercises and games. The materials are divided into four sections, which include "3D Shapes", "Surface Area & Volume", and "Platonic Solids". The "Platonic Solids" area is quite a bit of fun, as visitors will get the opportunity to print out foldable shapes such as a tetrahedron. A short fifteen question quiz that tests the materials covered by these various activities rounds out the site.

264

Ultrafine particle emissions from desktop 3D printers  

NASA Astrophysics Data System (ADS)

The development of low-cost desktop versions of three-dimensional (3D) printers has made these devices widely accessible for rapid prototyping and small-scale manufacturing in home and office settings. Many desktop 3D printers rely on heated thermoplastic extrusion and deposition, which is a process that has been shown to have significant aerosol emissions in industrial environments. However, we are not aware of any data on particle emissions from commercially available desktop 3D printers. Therefore, we report on measurements of size-resolved and total ultrafine particle (UFP) concentrations resulting from the operation of two types of commercially available desktop 3D printers inside a commercial office space. We also estimate size-resolved (11.5 nm-116 nm) and total UFP (<100 nm) emission rates and compare them to emission rates from other desktop devices and indoor activities known to emit fine and ultrafine particles. Estimates of emission rates of total UFPs were large, ranging from ˜2.0 × 1010 # min-1 for a 3D printer utilizing a polylactic acid (PLA) feedstock to ˜1.9 × 1011 # min-1 for the same type of 3D printer utilizing a higher temperature acrylonitrile butadiene styrene (ABS) thermoplastic feedstock. Because most of these devices are currently sold as standalone devices without any exhaust ventilation or filtration accessories, results herein suggest caution should be used when operating in inadequately ventilated or unfiltered indoor environments. Additionally, these results suggest that more controlled experiments should be conducted to more fundamentally evaluate particle emissions from a wider arrange of desktop 3D printers.

Stephens, Brent; Azimi, Parham; El Orch, Zeineb; Ramos, Tiffanie

2013-11-01

265

Intraoral 3D scanner  

Microsoft Academic Search

Here a new set-up of a 3D-scanning system for CAD\\/CAM in dental industry is proposed. The system is designed for direct scanning of the dental preparations within the mouth. The measuring process is based on phase correlation technique in combination with fast fringe projection in a stereo arrangement. The novelty in the approach is characterized by the following features: A

Peter Kühmstedt; Christian Bräuer-Burchardt; Christoph Munkelt; Matthias Heinze; Martin Palme; Ingo Schmidt; Josef Hintersehr; Gunther Notni

2007-01-01

266

3D microscope  

NASA Astrophysics Data System (ADS)

In order to circumvent the fact that only one observer can view the image from a stereoscopic microscope, an attachment was devised for displaying the 3D microscopic image on a large LCD monitor for viewing by multiple observers in real time. The principle of operation, design, fabrication, and performance are presented, along with tolerance measurements relating to the properties of the cellophane half-wave plate used in the design.

Iizuka, Keigo

2008-02-01

267

3-D Wave Simulation  

NSDL National Science Digital Library

This applet is a 3D simulation of wave motion due to different types of sources. The simulation can be rotated and/or frozen and viewed on a 2D slice. Among the possible simulations are point, line, slit, quadrapole and plane sources. The intensity can be shown, or the view limited to the sides of the box. The frequency, source separation, phase difference and balance are adjustable when necessary. The page also includes directions in English and German, and the source.

Falstad, Paul

2004-07-23

268

3D Bridge Construction  

Microsoft Academic Search

In the field of architecture, tangible virtual reality interfaces allow architects to design and construct large complex structures in a three-dimensional space, and interact with the 3D models using the most natural means of computer human interaction: the two-handed system. The main goal of this project is to design and create an interactive, tangible, virtual reality interface for constructing various

Yuan Xie; Peter Schröder; Steven Schkolne

269

DYNA3D  

SciTech Connect

DYNA3D is an explicit, three-dimensional, finite element program for analyzing the large deformation dynamic response of inelastic solids and structures. DYNA3D contains 30 material models and 10 equations of state (EOS) to cover a wide range of material behavior. The material models implemented are: elastic, orthotropic elastic, kinematic/isotropic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, Blatz-Ko rubber, high explosive burn, hydrodynamic without deviatoric stresses, elastoplastic hydrodynamic, temperature-dependent elastoplastic, isotropic elastoplastic, isotropic elastoplastic with failure, soil and crushable foam with failure, Johnson/Cook plasticity model, pseudo TENSOR geological model, elastoplastic with fracture, power law isotropic plasticity, strain rate dependent plasticity, rigid, thermal orthotropic, composite damage model, thermal orthotropic with 12 curves, piecewise linear isotropic plasticity, inviscid two invariant geologic cap, orthotropic crushable model, Moonsy-Rivlin rubber, and resultant plasticity. The hydrodynamic material models determine only the deviatoric stresses. Pressure is determined by one of 10 equations of state including linear polynomial, JWL high explosive, Sack 'Tuesday' high explosive, Gruneisen, ratio of polynomials, linear polynomial with energy deposition, ignition and growth of reaction in HE, tabulated compaction, tabulated, and TENSOR pore collapse. DYNA3D generates three binary output databases. One contains information for complete states at infrequent intervals; 50 to 100 states is typical. The second contains information for a subset of nodes and elements at frequent intervals; 1,000 to 10,000 states is typical. The last contains interface data for contact surfaces.

Kennedy, T. (IBM Corporation, Armonk, NY (United States))

1989-05-01

270

On the heat conduction in a high-temperature plasma in solar flares  

NASA Astrophysics Data System (ADS)

We have developed three types of mathematical models to describe the mechanisms of plasma heating in the corona by intense heat fluxes from a super-hot ( T e ? 108 K) reconnecting current layer in connection with the problem of energy transport in solar flares. We show that the heat fluxes calculated within the framework of self-similar solutions using Fourier's classical law exceed considerably the real energy fluxes known from present-day multi-wavelength observations of flares. This is because the conditions for the applicability of ordinary heat conduction due to Coulomb collisions of thermal plasma electrons are violated. Introducing anomalous heat conduction due to the interaction of thermal runaway electrons with ion-acoustic turbulence does not give a simple solution of the problem, because it produces unstable temperature profiles. Themodels incorporating the effect of collisional heat flux relaxation describe better the heat transport in flares than Fourier's law and anomalous heat conduction.

Oreshina, A. V.; Somov, B. V.

2011-10-01

271

Non-Fourier heat conduction in a single-walled carbon nanotube: Classical molecular dynamics simulations  

SciTech Connect

Nonstationary heat conduction in a single-walled carbon nanotube was investigated by applying a local heat pulse with duration of subpicoseconds. The investigation was based on classical molecular dynamics simulations, where the heat pulse was generated as coherent fluctuations by connecting a thermostat to the local cell for a short duration. The heat conduction through the nanotube was observed in terms of spatiotemporal temperature profiles. Results of the simulations exhibit non-Fourier heat conduction where a distinct amount of heat is transported in a wavelike form. The geometry of carbon nanotubes allows us to observe such a phenomenon in the actual scale of the material. The resulting spatiotemporal profile was compared with the available macroscopic equations, the so-called non-Fourier heat conduction equations, in order to investigate the applicability of the phenomenological models to a quasi-one-dimensional system. The conventional hyperbolic diffusion equation fails to predict the heat conduction due to the lack of local diffusion. It is shown that this can be remedied by adopting a model with dual relaxation time. Further modal analyses using wavelet transformations reveal a significant contribution of the optical phonon modes to the observed wavelike heat conduction. The result suggests that, in carbon nanotubes with finite length where the long-wavelength acoustic phonons behave ballistically, even optical phonons can play a major role in the non-Fourier heat conduction.

Shiomi, Junichiro; Maruyama, Shigeo [Department of Mechanical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2006-05-15

272

A 3D analysis of flight behavior of Anopheles gambiae sensu stricto malaria mosquitoes in response to human odor and heat.  

PubMed

Female mosquitoes use odor and heat as cues to navigate to a suitable landing site on their blood host. The way these cues affect flight behavior and modulate anemotactic responses, however, is poorly understood. We studied in-flight behavioral responses of females of the nocturnal malaria mosquito Anopheles gambiae sensu stricto to human odor and heat. Flight-path characteristics in a wind tunnel (flow 20 cm/s) were quantified in three dimensions. With wind as the only stimulus (control), short and close to straight upwind flights were recorded. With heat alone, flights were similarly short and direct. The presence of human odor, in contrast, caused prolonged and highly convoluted flight patterns. The combination of odor+heat resulted in longer flights with more landings on the source than to either cue alone. Flight speed was greatest (mean groundspeed 27.2 cm/s) for odor+heat. Odor alone resulted in decreased flight speed when mosquitoes arrived within 30 cm of the source whereas mosquitoes exposed to odor+heat maintained a high flight speed while flying in the odor plume, until they arrived within 15 cm of the source. Human odor evoked an increase in crosswind flights with an additive effect of heat at close range (<15 cm) to the source. This was found for both horizontal and vertical flight components. However, mosquitoes nevertheless made upwind progress when flying in the odor+heat generated plume, suggesting that mosquitoes scan their environment intensively while they progress upwind towards their host. These observations may help to improve the efficacy of trapping systems for malaria mosquitoes by (1) optimizing the site of odor release relative to trap entry and (2) adding a heat source which enhances a landing response. PMID:23658792

Spitzen, Jeroen; Spoor, Cornelis W; Grieco, Fabrizio; ter Braak, Cajo; Beeuwkes, Jacob; van Brugge, Sjaak P; Kranenbarg, Sander; Noldus, Lucas P J J; van Leeuwen, Johan L; Takken, Willem

2013-05-02

273

ALE3D Rolling Simulations  

SciTech Connect

Hot rolling is a problem involving large deformations during the process of turning an ingot into a thin sheet. As a result of the large deformations inherent in the process, significant amounts of energy are put into the ingot mechanically, most of which results in heat generation. Therefore, in order to predict the results of rolling both the mechanical and the thermal factors must accurately represent the real conditions. The factors which must be properly tuned include interface friction, mass scaling to decrease computation times, heat transfer at the interface, convective heat transfer from the ingot, and convective heat transfer from the roll. Since these parameters are generally not measurable the correct values must be derived by tuning the parameters so that solutions match some other measurable result. The interface friction will be tuned using an ALE3D input deck which has been set up to output the torque applied to the roll during the pass. The friction coefficient will be adjusted so that the computed torque matches the measured value. The various heat transfer coefficients are dependent on each other, and are tuned based on measured roll surface temperatures, ingot exit temperatures, and the energy input through the mechanical deformation of the ingot. The heat transfer coefficient at the interface has been found to be approximately 1.25 x 10{sup 5} W/m{sup 2}K, based on estimates of how much heat can be taken from the roll surface by coolant and matching a roll surface temperature. The convection coefficient on the ingot surface has been assumed to be 100 W/m{sup 2}K, on the high end for convection to air. However, this convection coefficient is low enough that the ingot should cool uniformly through its thickness as it would with a lower convection coefficient. Also necessary in accurate modeling is a good description of material behavior. In order to aid the development of an accurate material model an ALE3D input deck which simulates compression tests with temperature gradients has been developed. The model output engineering stress-strain curves which can be compared to the experimentally collected data. Also, comparisons of the deformed shapes can be made. The model has been tuned using MTS parameters for AA 5182 and will be ready for use when parameters for AA 2024 are experimentally developed. Currently, more work is needed to properly tune all the model parameters. A parameterized three dimensional geometry and mesh has been created so that once the parameters are tuned the transition to three dimensional simulations should be quick.

Riordan, T

2006-07-27

274

HEAT CONDUCTION THROUGH THE SUPPORT PILLARS IN VACUUM GLAZING  

Microsoft Academic Search

Vacuum glazing consists of two glass sheets with a narrow internal evacuated space. The separation of the sheets under the influence of atmospheric pressure is maintained by an array of small support pillars. The thermal resistances associated with the heat flow through individual pillars, and through the pillar array, are calculated using a simple analytic method, and by more complex

C. F Wilson; T. M Simko; R. E Collins

1998-01-01

275

Heat conduction in ablative material under intense laser radiation  

Microsoft Academic Search

Fusion and vaporization of solid material under intense laser radiation is studied assuming a semi-infinite body and unidimensional equation. The heat propagation equation is solved numerically to calculate the time evolution of the temperature profile. Two energy absorption modes are considered. In the first the surface is assumed opaque to radiation; in the second the de Beer absorption law is

B. Gautier

1976-01-01

276

Glasslike Heat Conduction in High-Mobility Crystalline Semiconductors  

Microsoft Academic Search

The thermal conductivity of polycrystalline semiconductors with type-I\\u000aclathrate hydrate crystal structure is reported. Ge clathrates (doped with Sr\\u000aand\\/or Eu) exhibit lattice thermal conductivities typical of amorphous\\u000amaterials. Remarkably, this behavior occurs in spite of the well-defined\\u000acrystalline structure and relatively high electron mobility ($\\\\sim 100\\u000acm^2\\/Vs$). The dynamics of dopant ions and their interaction with the\\u000apolyhedral cages

J. L. Cohn; G. S. Nolas; V. Fessatidis; T. H. Metcalf; G. A. Slack

1999-01-01

277

Elongating axial conduction path design to enhance performance of cryogeinc compact pche (printed circuit heat exchanger)  

NASA Astrophysics Data System (ADS)

PCHE (Printed Circuit Heat Exchanger) is one of the promising cryogenic compact heat exchangers due to its compactness, high NTU and robustness. The essential procedure for fabricating PCHE is chemical etching and diffusion bonding. These technologies can create sufficiently large heat transfer area for a heat exchanger with numerous micro channels (Dh<1 mm). However, PCHE shows disadvantages of high pressure drop and large axial conduction loss. Axial conduction is a critical design issue of a cryogenic heat exchanger when it is operated with a large temperature difference. Elongating the heat conduction path is implemented to reduce axial conduction in PCHE in this study. Two PCHEs with identical channel configuration are fabricated, for comparison, one of which is modified to have longer heat conduction path. Both heat exchangers are tested in cryogenic environment (300~70 K), and the modified PCHE shows better performance with significantly reduced axial conduction. The experimental results indicate that the modification of the heat conduction path is effective to increase the performance of PCHE. This paper discusses and analyses the thermal characteristics of the modified PCHE obtained experimentally.

Baek, Seungwhan; Kim, Jinhyuck; Hwang, Gyuwan; Jeong, Sangkwon

2012-06-01

278

Simple 3D Drawing  

NSDL National Science Digital Library

Developed by Barbara Kaskosz of the University of Rhode Island and Doug Ensley of Shippensburg University, this resource from The Mathematical Association of America's Digital Classroom Resources collection will prove quite valuable for educators and anyone with an interest in computer graphics or geometry. Through this resource, visitors will learn how to draw and rotate 3D objects via a series of short tutorials. Along the way, users will learn about the mathematics behind manipulating cubes, the geometry involved with the manipulation of cubes, and they will also get a chance to work on their own structures. Overall, it's a fine resource and it offers insights for students in several different disciplines

279

3D and beyond  

NASA Astrophysics Data System (ADS)

This conference on physiology and function covers a wide range of subjects, including the vasculature and blood flow, the flow of gas, water, and blood in the lung, the neurological structure and function, the modeling, and the motion and mechanics of organs. Many technologies are discussed. I believe that the list would include a robotic photographer, to hold the optical equipment in a precisely controlled way to obtain the images for the user. Why are 3D images needed? They are to achieve certain objectives through measurements of some objects. For example, in order to improve performance in sports or beauty of a person, we measure the form, dimensions, appearance, and movements.

Fung, Y. C.

1995-05-01

280

An Input Estimation Approach to On-Line Two-Dimensional Inverse Heat Conduction Problems  

Microsoft Academic Search

An on-line methodology to solve two-dimensional inverse heat conduction problems (IHCP) is presented. A new input estimation approach based on the Kalman filtering technique is developed to estimate the two separate unknown heat flux inputs on the two boundaries in real time. A recursive relation between the observed value of the residual sequence with unknown heat flux and the theoretical

Pan-Chio Tuan; Ching-China Ji; Li-Wei Fong; Wen-Tang Huang

1996-01-01

281

Importance of electron heat conduction in the energy balance of the F-region  

Microsoft Academic Search

Further analysis of the ionospheric electron heat balance using measurements of Atmosphere Explorer C has shown that electron heat conduction is important not only in the upper F-region but throughout the lower ionosphere as well. The discrepancy between local heating and cooling rates reported by Brace, et al., using similar AE-C data, has been removed in the present study by

Walter R. Hoegy; Larry H. Brace

1978-01-01

282

A Simple Rate Law Experiment Using a Custom-Built Isothermal Heat Conduction Calorimeter  

ERIC Educational Resources Information Center

|Most processes (whether physical, chemical, or biological) produce or consume heat: measuring thermal power (the heat production rate) is therefore a typical method of studying processes. Here we describe the design of a simple isothermal heat conduction calorimeter built for use in teaching; we also provide an example of its use in…

Wadso, Lars; Li, Xi.

2008-01-01

283

Initial stage of the evolution of dynamic perturbations in a nonlinearly heat-conducting gas  

NASA Astrophysics Data System (ADS)

The problem considered here concerns intense heating of a nonlinearly heat-conducting ideal gas. It is shown that intense heating gives rise to a weak discontinuity in the dynamic variables (gas density and velocity). The weak discontinuity exists only for a short period of time, after which it becomes a strong discontinuity (i.e., a shock wave).

Romanov, A. S.; Stytsyna, A. A.

1988-08-01

284

Finite element formulation of the heat conduction equation in general orthogonal curvilinear coordinates  

Microsoft Academic Search

A general approach to the finite element solution of heat conduction problems in orthogonal curvilinear coordinates is presented. The quasi-variational approach is used to determine the functional which yields as an Euler equation the heat conduction equation in general orthogonal curvilinear coordinates and which accounts for boundary condition specification in a curvilinear frame. During the development, the time derivative of

G. E. Schneider

1975-01-01

285

EFFECT OF A CENTERED CONDUCTING BODY ON NATURAL CONVECTION HEAT TRANSFER IN AN ENCLOSURE  

Microsoft Academic Search

The effect of a centered, square, heat-conducting body on natural convection in a vertical square enclosure was examined numerically. The analysis reveals that the fluid flow and heat transfer processes are governed by the Rayleigh and Prandtl numbers, the dimensionless body size, and the ratio of the thermal conductivity of the body to that of the fluid. For Pr =

John M. House; Christoph Beckermann; Theodore F. Smith

1990-01-01

286

Simultaneous measurements of thermal conductivity, thermal diffusivity and specific heat by nuclear magnetic resonance imaging  

Microsoft Academic Search

The feasibility of measuring the thermal conductivity (?), thermal diffusivity (?) and specific heat (cp) of an aqueous gel noninvasively by nuclear magnetic resonance (NMR) imaging is presented. NMR images acquired with high spatial and temporal resolutions provide the means for a direct evaluation of Fourier's heat conduction relation and the simultaneous measurement of ?, ? and cp in a

David H. Gultekin; John C. Gore

2011-01-01

287

Solving an inverse heat conduction problem using a non-integer identified model  

Microsoft Academic Search

An inverse heat conduction problem in a system is solved using a non-integer identified model as the direct model for the estimation procedure. This method is efficient when some governing parameters of the heat transfer equations, such as thermal conductivity or thermal resistance, are not known precisely. Reliability of the inversion depends on the precision of the identified model. From

J.-L. Battaglia; O. Cois; L. Puigsegur; A. Oustaloup

2001-01-01

288

Combined parameter and function estimation in heat transfer with application to contact conductance  

Microsoft Academic Search

This paper discusses parameter estimation, function estimation, and a combination of the two. An example of parameter estimation is the determination of thermal conductivity of solids from transient temperature measurements. An example of function estimation is the inverse heat conduction problem, which uses transient temperature measurements to determine the surface heat flux history. The examples used herein involve the determination

J. V. Beck

1988-01-01

289

Measurement of Thermal Conductivity Using TMDSC: Solution to the Heat Flow Problem  

Microsoft Academic Search

The dependence of the apparent heat capacity obtained from quasi-isothermal temperature-modulated differential scanning calorimetry (TM DS C) experiments and the thermal conductivity is determined for several cases. The relationships are based on the solution of the heat conduction equation which gives the temperature profile in the TM DS C sample. The temperature profile is then used to calculated the sinusoidal

SINDEE L. SIMON; GREGORY B. McKENNA

290

Theory of combustion of a condensed propellant with a flat heat-conducting element  

Microsoft Academic Search

A theoretical analysis of the rate of combustion of a condensed propellant with heat-conducting elements is a complex problem associated with the solution of nonuniform equations of heat conduction. Hence, the known theoretical papers (see [2] and and references in it) contain a number of assumptions facilitating the solution of the problem but not permitting any construction of a closed

S. S. Rybanin; L. N. Stesik

1974-01-01

291

Dynamic technique for measurement of the thermal conductivity and the specific heat: Application to silica aerogels  

Microsoft Academic Search

We describe a dynamic technique for measuring both the thermal conductivity and the specific heat of poor thermal conductors in a single measurement. The technique is an extension of the widely applied thermal-relaxation technique. In the case of a sample having a thermal conductance comparable to the rate at which heat is removed from the sample, the observed temperature behavior

A. Bernasconi; T. Sleator; D. Posselt; H. R. Ott

1990-01-01

292

An inverse problem in simultaneously measuring temperature-dependent thermal conductivity and heat capacity  

Microsoft Academic Search

An inverse analysis utilizing the conjugate gradient method of minimization and the adjoint equation is used for simultaneously estimating the temperature-dependent thermal conductivity and heat capacity per unit volume of a material. No prior information is used for the functional forms of the unknown thermal conductivity and heat capacity in the present study, thus, it is classified as the function

Cheng-Hung Huang; Yan Jan-Yuan

1995-01-01

293

Transient combined radiation and conduction heat transfer in fibrous media with temperature and flux boundary conditions  

Microsoft Academic Search

Transient radiative and conductive heat transfer in a fibrous medium with anisotropic optical properties is investigated. Two different kinds of boundary conditions are treated: when the temperatures imposed on the boundaries vary with time and when the medium is subject to a radiation source which varies with time. A one dimensional case is considered. The non-linear transient Heat Conduction Equation

Fatmir Asllanaj; Gérard Jeandel; Jean Rodolphe Roche; David Lacroix

2004-01-01

294

Integration of finite element analysis program for conduction heat transfer with computer analysis language  

Microsoft Academic Search

The Finite Element Analysis Program (FEAP) was modified and integrated with the Naval Postgraduate School version of the Computer Analysis Language (CAL-NPS). This enables the solution of linear and non-linear, two and three dimensional heat conduction problems in an interactive mode. The usual types of boundary conditions, including radiation, may be specified. The heat conduction group includes prompts for user

W. L. Roberts

1982-01-01

295

Interchangeable variable conductance heat pipes for sodium-sulfur batteries  

Microsoft Academic Search

Sodium-sulfur batteries can provide electrical power to satellite instrumentation operating in geosynchronous-earth-orbit (GEO) and low-earth-orbit (LEO) conditions. While on orbit, the sodium-sulfur battery requires thermal management as the battery is cycled between discharge in solar eclipse and recharge in sunlight. As the battery discharges in solar eclipse waste heat is generated and the battery requires cooling. During recharge in sunlight

John R. Hartenstine

1991-01-01

296

Unsteady heat conduction by internal-energy waves in solids  

Microsoft Academic Search

The propagation of thermal waves at finite speed is analyzed both for processes which fulfill the local equilibrium hypothesis and for processes which do not fulfill this hypothesis. A modified form of the Cattaneo-Vernotte constitutive equation for the heat-flux-density vector is proposed. The constitutive equation does not require the definition of a thermodynamic temperature field for local nonequilibrium states and,

A. Barletta; E. Zanchini

1997-01-01

297

Phonon heat conduction in nano and microporous thin films  

NASA Astrophysics Data System (ADS)

In this dissertation, the phonon size effect in the experimental and theoretical studies of random and periodic porous media are reported. First, a literature review on the past modeling studies on porous media are presented that covers both the earlier works that use the traditional effective medium approach and the few existing recent works that consider the low-dimensional effects. Next, the experimental characterization of the cross-plane thermal conductivity of randomly nano-porous bismuth thin films is presented. Fabricated in search for more efficient thermoelectric materials, the nanoporous bismuth films use nano-scale pores to impede phonon transport more than electron transport. Their cross-plane thermal conductivity characterization using the differential 3o technique revealed an order-of-magnitude reduction in the thermal conductivity values of the porous bismuth over those of non-porous bismuth films and a potential for the independent tuning of their electrical conductivity and thermal conductivity, but the defect-laden structure was difficult to model. Therefore, a new study was undertaken that focused on simpler periodic micro-porous single-crystal silicon membranes. A batch of such membranes were fabricated from both a plain silicon wafer and a silicon-on-insulator wafer using MEMS techniques, including bulk chemical etching and deep-reactive ion etching. The resulting samples contained periodically arranged pores of controlled dimension and orientation, but the pore dimension and orientation was varied from sample to sample to experimentally isolate the phonon size effect due to pore boundary scattering. The in-plane thermal conductivity of the microporous silicon membranes is characterized by a modified version of Volklein's DC method. The resulting thermal conductivity reduction in porous films compared to the solid silicon film strongly suggest phonon size effect. The three-dimensional phonon transport in porous silicon membranes were modeled using the Monte Carlo method to yield an equivalent solution to the three-dimensional Boltzmann transport equation. Since the focus of the modeling is the effect of pore boundary scattering on phonon transport, a simplified view of gray-body medium is studied. The thermal conductivity result predicts a thermal conductivity reduction in porous silicon films compared to solid silicon films by an amount beyond that predicted from porosity and comparable to that observed in experiments.

Song, David Won-Jun

298

Estimation of the temperature-dependent thermal conductivity in inverse heat conduction problems  

Microsoft Academic Search

An iterative approach is presented to determine the temperature-dependent thermal conductivity from the temperature measurements taken at one side of boundary. On the basis of the proposed method, the undetermined thermal conductivity is first denoted as the unknown variables in a set of nonlinear equations, which are formulated from the measured temperature and the calculated temperature. Then, a linearization method

Ching-yu Yang

1999-01-01

299

Uncertainty analysis of heat flux measurements estimated using a one-dimensional, inverse heat-conduction program.  

SciTech Connect

The measurement of heat flux in hydrocarbon fuel fires (e.g., diesel or JP-8) is difficult due to high temperatures and the sooty environment. Un-cooled commercially available heat flux gages do not survive in long duration fires, and cooled gages often become covered with soot, thus changing the gage calibration. An alternate method that is rugged and relatively inexpensive is based on inverse heat conduction methods. Inverse heat-conduction methods estimate absorbed heat flux at specific material interfaces using temperature/time histories, boundary conditions, material properties, and usually an assumption of one-dimensional (1-D) heat flow. This method is commonly used at Sandia.s fire test facilities. In this report, an uncertainty analysis was performed for a specific example to quantify the effect of input parameter variations on the estimated heat flux when using the inverse heat conduction method. The approach used was to compare results from a number of cases using modified inputs to a base-case. The response of a 304 stainless-steel cylinder [about 30.5 cm (12-in.) in diameter and 0.32-cm-thick (1/8-in.)] filled with 2.5-cm-thick (1-in.) ceramic fiber insulation was examined. Input parameters of an inverse heat conduction program varied were steel-wall thickness, thermal conductivity, and volumetric heat capacity; insulation thickness, thermal conductivity, and volumetric heat capacity, temperature uncertainty, boundary conditions, temperature sampling period; and numerical inputs. One-dimensional heat transfer was assumed in all cases. Results of the analysis show that, at the maximum heat flux, the most important parameters were temperature uncertainty, steel thickness and steel volumetric heat capacity. The use of a constant thermal properties rather than temperature dependent values also made a significant difference in the resultant heat flux; therefore, temperature-dependent values should be used. As an example, several parameters were varied to estimate the uncertainty in heat flux. The result was 15-19% uncertainty to 95% confidence at the highest flux, neglecting multidimensional effects.

Nakos, James Thomas; Figueroa, Victor G.; Murphy, Jill E. (Worcester Polytechnic Institute, Worcester, MA)

2005-02-01

300

Diffusive-Ballistic Heat Conduction of Carbon Nanotubes and Nanographene Ribbons  

NASA Astrophysics Data System (ADS)

Investigations of diffusive-ballistic heat conduction of finite-length single- walled carbon nanotubes and nanographene ribbons at room temperature have been carried out by using non-equilibrium molecular dynamics simulations. The length dependences of the thermal conductivity reveal the variation of the balance between ballistic and diffusive heat conductions. For both systems, the profile indicates a significant contribution of the ballistic phonon transport even with a length of about a micrometer. Comparison of the length effects of single-walled carbon nanotubes and nanographene ribbons highlights the roles of phonon dispersions and the extent of phonon scattering on diffusive-ballistic heat conduction.

Shiomi, Junichiro; Maruyama, Shigeo

2010-10-01

301

Ground thermal response to heat conduction in a power transmission tower foundation  

Microsoft Academic Search

An analytical formulation is developed to predict transient heat conduction in a semi-infinite medium with a vertical finite\\u000a line heat source, which represents a buried tower of a power transmission line foundation. Unlike past studies with a constant\\u000a line heat source, the current model develops a time-dependent variable heating strength, as well as a time varying surface\\u000a temperature of the

Xili Duan; Greg F. Naterer

2008-01-01

302

On the Role of Hall and Pedersen Conductivities in Determination of Ionospheric Joule Heating  

NASA Astrophysics Data System (ADS)

Ionospheric Joule heating is defined as the frictional heating which results from the collisions between the neutrals and charged particles at the ionospheric heights. These collisional processes gain importance around 120 km in the E and F regions of the ionosphere where there are more neutral atoms, and particularly at the auroral altitudes, where Hall and Pedersen conductivities are comparable to each other. The most conventional ways of calculating ionospheric Joule heating relies on the relationship between electric field and Pedersen conductivity. The role of Hall conductivity in the calculation of Joule heating still remains unclear, and in general its contribution is accepted to be minor when compared to the Pedersen currents at the first approximation. However, results from the MHD simulations show that Joule heating is reduced in the regions where Hall conductivity is close to or higher than Pedersen conductivity. These local variations also modify the global Joule heating pattern and distribution. MHD models take into account the magnetosphere and ionosphere interaction and incorporate with the ionospheric modules which include the interaction between the neutral winds and charged paricles. In this study, we have selected two isolated substorm events that occurred in March, 2008 to investigate the effects of Hall conductivity on the Joule heating. We run NASA/CCMC MHD models, e.g. SWMF/BATSRUS, during these times under concurrent solar wind and IMF conditions. The outputs from the models will be used to calculate Joule heating with the Hall conductivity effects properly included. In this presentation, we will show our preliminary results on the Joule heating rates from the models, quantify the degree of Pedersen and Hall conductivity contributions on the Joule heating, and address on their contributions on the global distribution of the Joule heating. We will also compare and discuss our findings with those available in the literature.

Ceren Kalafatoglu, Emine; Kaymaz, Zerefsan

2013-04-01

303

Heat-sensitive conduction block in ulnar neuropathy at the elbow  

Microsoft Academic Search

Objectives: To study the effects of elbow heating on conduction block (CB) and across-elbow conduction velocity (CV) in patients with ulnar neuropathy at the elbow (UNE).Methods: We studied 15 patients with UNE, performing motor nerve conduction studies at 32°C and after heating the elbow to 42°C.Results: At 32°C, mean response amplitude and area with above-elbow (AE) stimulation were 20.4 and

Seward B Rutkove; Margot A Geffroy; Seth H Lichtenstein

2001-01-01

304

Entourage3D  

NSDL National Science Digital Library

From charettes to ateliers, architectural education is dedicated to collaborative learning environments. In recent years, some of these activities have migrated to the web, and along the way a number of forward-thinking individuals have seen fit to create online resources that might be of use to students working in this field. Created by the Design Machine Group at the University of Washington's Department of Architecture, the entourage 3D database includes "building blocks, complete models, and finishing touches for users to download and use." Visitors will appreciate the fact that they can browse these resources by such categories as building component, lighting element, office furniture, or street furniture. Visitors will need to complete a free registration before looking at the various designs and plans available here, but this only takes a few moments.

305

Phonon Transport in Graphene: Umklapp Quenching and Heat Conduction  

NASA Astrophysics Data System (ADS)

Since its exfoliation, graphene attracted tremendous attention of the research community. Graphene, which consists of a single atomic plane of carbon atoms, revealed many unique properties including extremely high electron mobility. In this talk I will show that unusual properties of graphene are not limited to electrons alone. Phonons also behave differently in two-dimensional (2D) system such as graphene. We have recently discovered experimentally that thermal conductivity of suspended graphene layers is extremely high and exceeds that of diamond or graphite [2-3]. We explained our results theoretically by considering the Umklapp and edge scattering of phonons in graphene [3]. Unlike in bulk graphite, the phonon transport in graphene is pure 2D for all phonon energies. As a result, the thermal conductivity of graphene can become extremely high. The extraordinary high thermal conductivity of graphene can be used for thermal management of nanoscale electronic devices. This work was supported by SRC-DARPA Functional Engineered Nano Architectonics (FENA) center and Interconnect Focus Center (IFC). [1] A.A. Balandin, et al. Nano Letters, 8, 902 (2008); S. Ghosh, et al., Appl. Phys. Lett., 92, 151911 (2008). [2] D.L. Nika, et al., Phys. Rev. B, 79, 155413 (2009); D.L. Nika et al., Appl. Phys. Lett., 94, 203103 (2009)

Balandin, Alexander

2009-11-01

306

Stellar Aberration 3D  

NSDL National Science Digital Library

The EJS Stellar Aberration 3D Model illustrates the phenomenon known as the aberration of starlight, first reported by James Bradley in 1729. Aberration occurs because light has a finite speed, and thus light from a star takes a finite amount of time to travel through the tube of a telescope. During this time, the telescope moves as a result of Earth's rotational and orbital motions (in this case, the orbital motion is more important because it is faster). Therefore, if the telescope is pointed directly at the star the starlight will hit the sides of the tube before reaching the eyepiece. To see the star the telescope must be pointed forward (ie in the direction of Earth's motion) very slightly. As a result the apparent location of the star on the sky is different from its true location. The simulation illustrates the effects of aberration for a star at any location in the sky, during any time of year. A 3D view shows the Earth orbiting the sun, the star, and the apparent position of the star on the Celestial Sphere. This view can also display vectors detailing how the velocity of Earth combines with the velocity of light from the star to produce a new relative velocity vector that indicates the apparent location of the star. A separate 2D view shows the "true" location of the star as well as the apparent location for an observer looking up from Earth. Note that some features have been simplified or exaggerated. The Earth's orbit is treated as a circle. The size of Earth, Sun, and Earth's orbit are greatly exaggerated compared to the distance to the star. The speed controls allow the user to set Earth's orbital speed to an appreciable fraction of light speed, which is not realistic. Finally, the simulation illustrates the "classical" aberration effect, not the (more correct) relativistic aberration.

Timberlake, Todd

2011-05-18

307

The influence of heat conduction on evaporation from sunken pans in hot, dry environment  

NASA Astrophysics Data System (ADS)

Lateral heat conduction across a large circular sunken pan located in a hot, dry environment is evaluated using a numerical procedure. Heat flow across the sunken pan—adjacent soil boundary is calculated using a two-dimensional soil plane. Calculations show that a large temperature differential across the pan—substrate boundary develops during the entire diurnal cycle during January and July, leading to consistently positive heat flow from the soil towards the sunken pan. Heat conduction across the pan—substrate boundary represents 10 and 34% of net radiation over the sunken pan during July and January, respectively. This additional heat source, which is not available for shallow lakes, increases annual evaporation from the sunken pan by about 5 8% in July and January, respectively. In hot arid environments, a sunken pan will overestimate evaporation from a nearby shallow lake/dam due to a larger surface roughness and consistently positive conduction heat flow across the pan—substrate boundary.

Oroud, I. M.

1998-09-01

308

Thermal expansion effects and heat conduction in granular materials.  

PubMed

In this paper, we report results and analysis on a simulation study of the effects of thermal expansion in granular systems. We show that these effects impact the force distribution inside a two-dimensional system of disks that are subject to thermal heating under two different boundary conditions. A significant increase in the average force is observed for steel particles confined within a box with fixed walls at temperature rises of 50 degrees C and 100 degrees C, respectively. As previously noted in the literature, thermal expansion also induces compaction. The results show that a systematic and controllable increase in granular packing can be induced by simply raising and then lowering the temperature, without the input of mechanical energy in agreement with previous experimental observations. We find that the evolution of the packing fraction is well described by a fractional relaxation model, which follows the Mittag-Leffler law. PMID:17994975

Vargas, Watson L; McCarthy, J J

2007-10-16

309

Soil profile method for soil thermal diffusivity, conductivity and heat flux: Comparison to soil heat flux plates  

NASA Astrophysics Data System (ADS)

Diffusive heat flux at the soil surface is commonly determined as a mean value over a time period using heat flux plates buried at some depth (e.g., 5-8 cm) below the surface with a correction to surface flux based on the change in heat storage during the corresponding time period in the soil layer above the plates. The change in heat storage is based on the soil temperature change in the layer over the time period and an estimate of the soil thermal heat capacity that is based on soil water content, bulk density and organic matter content. One- or multiple-layer corrections using some measure of mean soil temperature over the layer depth are common; and in some cases the soil water content has been determined, although rarely. Several problems with the heat flux plate method limit the accuracy of soil heat flux values. An alternative method is presented and this flux gradient method is compared with soil heat flux plate measurements. The method is based on periodic (e.g., half-hourly) water content and temperature sensing at multiple depths within the soil profile and a solution of the Fourier heat flux equation. A Fourier sine series is fit to the temperature at each depth and the temperature at the next depth below is simulated with a sine series solution of the differential heat flux equation using successive approximation of the best fit based on changing the thermal diffusivity value. The best fit thermal diffusivity value is converted to a thermal conductivity value using the soil heat capacity, which is based on the measured water content and bulk density. A statistical analysis of the many data resulting from repeated application of this method is applied to describe the thermal conductivity as a function of water content and bulk density. The soil heat flux between each pair of temperature measurement depths is computed using the thermal conductivity function and measured water contents. The thermal gradient method of heat flux calculation compared well to values determined using heat flux plates and calorimetric correction to the soil surface; and it provided better representation of the surface spatiotemporal variation of heat flux and more accurate heat flux values. The overall method resulted in additional important knowledge including the water content dynamics in the near-surface soil profile and a soil-specific function relating thermal conductivity to soil water content and bulk density.

Evett, Steven R.; Agam, Nurit; Kustas, William P.; Colaizzi, Paul D.; Schwartz, Robert C.

2012-12-01

310

Effect of sand addition on the specific heat and thermal conductivity of cement  

Microsoft Academic Search

Sand addition was found to decrease the specific heat and increase the thermal conductivity of cement, in contrast to the opposite effects of silica fume addition. The thermal conductivity increase due to sand addition was much greater when silica fume was present. The thermal conductivity decrease due to silica fume addition was much smaller when sand was present.

Yunsheng Xu; D. D. L. Chung

2000-01-01

311

Heat transfer enhancement in laminar slurry pipe flows with power law thermal conductivities  

Microsoft Academic Search

Generalized theoretical results for heat transfer in laminar pipe flow with power law varying thermal conductivities are presented. The study is motivated by experimental observations that above a threshold shear rate the effective thermal conductivity for disperse two-phase mixtures increases with shear rate. Using a relatively general three parameter power law model for conductivity as a function of shear rate,

C. W. Sohn; M. M. Chen

1984-01-01

312

3D Lowest Landau Level Theory Applied to YBCO Magnetization and Specific Heat Data: Implications for the Critical Behavior in the HT Plane  

Microsoft Academic Search

We study the applicability of magnetization and specific heat equations\\u000aderived from a lowest-Landau-level (LLL) calculation, to the high-temperature\\u000asuperconducting (HTSC) materials of the YBa$_2$Cu$_3$O$_{7-\\\\delta}$ (YBCO)\\u000afamily. We find that significant information about these materials can be\\u000aobtained from this analysis, even though the three-dimensional LLL functions\\u000aare not quite as successful in describing them as the corresponding\\u000atwo-dimensional functions

Stephen W. Pierson; Oriol T. Valls; Zlatko Teÿsanovic; Michael A. Lindemann

1997-01-01

313

3D printed bionic ears.  

PubMed

The ability to three-dimensionally interweave biological tissue with functional electronics could enable the creation of bionic organs possessing enhanced functionalities over their human counterparts. Conventional electronic devices are inherently two-dimensional, preventing seamless multidimensional integration with synthetic biology, as the processes and materials are very different. Here, we present a novel strategy for overcoming these difficulties via additive manufacturing of biological cells with structural and nanoparticle derived electronic elements. As a proof of concept, we generated a bionic ear via 3D printing of a cell-seeded hydrogel matrix in the anatomic geometry of a human ear, along with an intertwined conducting polymer consisting of infused silver nanoparticles. This allowed for in vitro culturing of cartilage tissue around an inductive coil antenna in the ear, which subsequently enables readout of inductively-coupled signals from cochlea-shaped electrodes. The printed ear exhibits enhanced auditory sensing for radio frequency reception, and complementary left and right ears can listen to stereo audio music. Overall, our approach suggests a means to intricately merge biologic and nanoelectronic functionalities via 3D printing. PMID:23635097

Mannoor, Manu S; Jiang, Ziwen; James, Teena; Kong, Yong Lin; Malatesta, Karen A; Soboyejo, Winston O; Verma, Naveen; Gracias, David H; McAlpine, Michael C

2013-06-12

314

Coupled radiative and conductive heat transfer across honeycomb panels and through single cells  

NASA Astrophysics Data System (ADS)

In the absence of natural convection, heat flows through a gas-filled honeycomb by conduction and radiation. For the parameter ranges of interest in a plastic honeycomb inside a flat plate solar collector, the conduction and radiation are strongly coupled. The total heat transfer across the panel was studied experimentally and theoretically. The experimental approach precisely measured the total heat transfer under varying conditions. The theoretical approach proposed several models, established their governing equations, and solved the equations by either numerical or analytical methods. A model based on grey surfaces, specular sidewalls, and one-dimensional conduction yielded results within 6 percent of measurements.

Hollands, K. G. T.; Raithby, G. D.; Russell, F. B.; Wilkinson, R. G.

1984-11-01

315

Thermal conductivity, heat capacity, and thermal diffusivity of selected commercial AlN substrates  

NASA Astrophysics Data System (ADS)

The thermal transport properties of four commercially available AlN substrates have been investigated using a combination of steady-state and transient techniques. Measurements of thermal conductivity using a guarded longitudinal heat flow apparatus are in good agreement with published room temperature data (in the range 130 170 W · m-1 · K-1). Laser flash diffusivity measurements combined with heat capacity data yielded anomalously low results. This was determined to be an experimental effect for which a method of correction is presented. Low-temperature measurements of thermal conductivity and heat capacity are used to probe the mechanisms that limit the thermal conductivity in AlN.

Dinwiddie, R. B.; Whittaker, A. J.; Onn, D. G.

1989-09-01

316

Geometry in 3-D  

NSDL National Science Digital Library

This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. The online resources featured in Geometry in 3-D actively engage students in exploring a variety of geometric shapes, at times through lessons that involve building models or creating paper nets that fold into three-dimensional shapes; at other times, through technology that allows students to rotate and zoom in on figures, noting their attributes and complexity. Other lessons offer problems on surface area and volume, a part of every middle school curriculum. The problems, each with a different twist on the subject, challenge students to reconsider their understanding of how to measure solids. Activities for developing spatial sense, another primary objective in teaching geometry, are also featured. Finally, there are online galleries of geometric solids, included for the rare opportunity they offer to show your students the beauty in mathematics. In Background Information, you will find workshop sessions developed for teachers and other materials that may interest you as a professional. Each resource deals specifically with three-dimensional geometry topics that align with the geometry and measurement standards recommended by NCTM.

Herrera, Terese

2006-09-01

317

Architect Studio 3D  

NSDL National Science Digital Library

When one thinks of the vast number of influential architects the world has seen during the past centuries, one is reminded of Dies van der Rohe, Walter Gropius, Le Corbusier, and of course, that Master from the Midwest, Frank Lloyd Wright. It's hard to imagine that a website would be able to conjure up the spirit of this famous and controversial architect, but it does just that. With the assistance of a user-friendly interface, the Architect Studio 3D site allows users to build a model home for a number of clients and their very specific needs. With a small icon of the master residing in the bottom of the left-hand corner of the screen, visitors will get the chance to create their own building for one of these clients, and then submit it to a design gallery for consideration by others. For those visitors who may be less familiar with the world of architecture, there is a handy section titled "About Architecture". Here they will find a glossary of terms that provide brief descriptions of such important concepts and design elements as site, wall, client, roof, and exterior material. Of course, no such site would be complete without a brief biography of the man himself, and as such, a nice overview of his work and life is provided here as well.

318

Heat Exchangers for Heavy Vehicles Utilizing High Thermal Conductivity Graphite Foams  

SciTech Connect

Approximately two thirds of the world's energy consumption is wasted as heat. In an attempt to reduce heat losses, heat exchangers are utilized to recover some of the energy. A unique graphite foam developed at the Oak Ridge National Laboratory (ORNL) and licensed to Poco Graphite, Inc., promises to allow for novel, more efficient heat exchanger designs. This graphite foam, Figure 1, has a density between 0.2 and 0.6 g/cm 3 and a bulk thermal conductivity between 40 and 187 W/m{center_dot}K. Because the foam has a very accessible surface area (> 4 m 2 /g) and is open celled, the overall heat transfer coefficients of foam-based heat exchangers can be up to two orders of magnitude greater than conventional heat exchangers. As a result, foam-based heat exchangers could be dramatically smaller and lighter.

James Klett, Ron Ott; April McMillan

2000-06-19

319

3D video capturing for multiprojection type 3D display  

NASA Astrophysics Data System (ADS)

We have already developed glasses-free three-dimensional (3-D) displays using multi-projectors and a special diffuser screen that results in a highly realistic communication system. The system can display 70-200 inch large-sized 3-D images with full high-definition video image quality. The displayed 3-D images were, however, only computergenerated graphics or still images of actual objects. In this work, we studied a 3-D video capturing method for our multiprojection 3-D display. We analyzed the optimal arrangement of cameras for the display, and the image quality as influenced by calibration error. In the experiments, we developed a prototype multi-camera system using 30 highdefinition video cameras. The captured images were corrected via image processing optimized for the display. We successfully captured and displayed, for the first time, 3-D video of actual moving objects in our glasses-free 3-D video system.

Kawakita, Masahiro; Gurbuz, Sabri; Iwasawa, Shoichiro; Lopez-Gulliver, Roberto; Yano, Sumio; Ando, Hiroshi; Inoue, Naomi

2011-05-01

320

A Technique for Locally Increasing Surface Heat Spreading and through-Thickness Thermal Conductivity of Graphite\\/Epoxy Laminates  

Microsoft Academic Search

The polymer matrix composite through-thickness thermal conductivity is particularly important in applications such as composite spaceborne electronics enclosures where the heat dissipation is primarily dependent on thermal conduction to a heat sink. The spreading of heat at the composite surface and subsequent localized conduction in the through-thickness direction down to high thermal conductivity fiber may be the key to designing

Jack C. Roberts; Mark H. Luesse; Thomas C. Magee

1996-01-01

321

Heat and Current Propagation in Buffered Superconducting and Hyper- conducting Wire.  

National Technical Information Service (NTIS)

This research models and analyzes the distribution of heat and current in a buffered superconducting or hyper-conducting wire that shows potential for use in different capacities in multiple Air Force systems including the Active Denial System. The thesis...

J. L. Lynn

2009-01-01

322

Response-Coefficient Method for Heat-Conduction Transients with Time-Dependent Inputs.  

National Technical Information Service (NTIS)

A theoretical overview of the response coefficient method for heat conduction transients with time-dependent input forcing functions is presented with a number of illustrative applications. The method may be the most convenient and economical if the same ...

T. Ceylan

1993-01-01

323

Numerical Identification of Boundary Conditions on Nonlinearly Radiating Inverse Heat Conduction Problems.  

National Technical Information Service (NTIS)

An explicit and unconditionally stable finite difference method for the solution of the transient inverse heat conduction problem in a semi-infinite or finite slab mediums subject to nonlinear radiation boundary conditions is presented. After measuring tw...

D. A. Murio

1991-01-01

324

The Thermal Conductivity Measurements of Solid Samples by Heat Flux Differantial Scanning Calorimetry  

NASA Astrophysics Data System (ADS)

The thermal conductivity of polyvinylchloride (PVC), polysytrene (PS) and polypropylene (PP) were measured by heat flux DSC. Our results are in good agreement with the results observed by different methods.

Kök, M.; Aydo?du, Y.

2007-04-01

325

Astronomical Parallax 3D  

NSDL National Science Digital Library

This Astronomical Parallax 3D Model illustrates the phenomenon of annual stellar parallax in astronomy. Parallax is the apparent displacement of an object relative to the background that is caused by the motion of the observer (rather than the motion of the object itself, or of the background). This simulation illustrates the parallax of an object in space that results from the Earth's annual orbital motion. The Space View window shows the Earth (blue point) orbiting the Sun (organe point). The white point represents a stationary star. The open white circle shows the location of the object on the celestial sphere as seen from the Sun. The magenta point shows the location of the star on the celestial sphere as seen by an observer on the orbiting Earth. Various options allow the user to display the line of sight from Earth through the star, the line from the Sun through the star, cardinal direction arrows, the trace of the star's apparent motion, the trace of Earth's orbit, and the planes and axes of the celestial equator and ecliptic. Controls allow the user to adjust the distance to the star as well as its celestial coordinates (as seen from the Sun). Another menu allows the user to select a particular day (equinox or solstice) of the year. The Sky View window shows the apparent location of the star on the sky as seen by an Earth observer. The "true location" (the location as seen from the Sun) is shown as an open white circle, while the apparent location is shown as a magenta disk. Note that some features have been simplified or exaggerated. The Earth's orbit is treated as a circle. The distances to the "star" are vastly smaller than the distance to any real star (at the distance to the nearest real star the annual parallax would be imperceptible in this simulation). The size of the Earth, sun, and star are exaggerated so as to make them visible on the scale of the simulation.

Timberlake, Todd

2011-05-18

326

Mixed convection in an enclosure with a heat-conducting body  

Microsoft Academic Search

Summary Combined free convection and forced convection in a square enclosure with a finite-size heat source is studied numerically. A square heat-conducting body is located somewhere within the enclosure. The present study simulates a practical system, such as an air-cooled electronic equipment with heat components or an oven with heaters. Emphasis is placed on the influences of the configurations and

T. H. Hsu; S. P. How

1999-01-01

327

HEAT TRANSFER OF SOLID–LIQUID PHASECHANGE MATERIAL SUSPENSIONS IN CIRCULAR PIPES: EFFECTS OF WALL CONDUCTION  

Microsoft Academic Search

This article considers the problem of conjugate heat transfer in circular pipes with finite heated length to examine the effects of wall conduction on the heat transfer characteristics of solid–liquid phase-change material suspension flow. A mixture continuum approach is adopted in the formulation of the energy equation, with an approximate enthalpy model describing the phase-change process in the phase-change material

C. J. Ho; J. F. Lin; S. Y. Chiu

2004-01-01

328

A Simple Relation Between Thermal Conductivity, Specific Heat and Absolute Temperature  

Microsoft Academic Search

A relation of the form kaC=K1T+K2, between thermal conductivity k, atomic heat (aC), and absolute temperature T, is shown to hold for zinc, sodium, lithium, copper, lead, aluminum and mercury. The possibility is indicated of an equation of this sort based on the assumption of a double mechanism of heat conduction-an atomic lattice along which energy is transmitted as elastic

C. C. Bidwell

1928-01-01

329

Subgrid-scale modeling of compressible magnetohydrodynamic turbulence in heat-conducting plasma  

SciTech Connect

A large-eddy simulation (LES) approach for compressible magnetohydrodynamic (MHD) turbulence in heat-conducting plasma is developed for the first time. Subgrid-scale models for new terms appearing due to the presence of magnetic field are suggested. Results of modeling for decaying compressible MHD turbulence are presented. Comparison and testing with results obtained by direct numerical simulation are made. The efficiency of the developed LES technique for compressible MHD turbulence in heat-conducting plasma is shown.

Chernyshov, A. A.; Karelsky, K. V.; Petrosyan, A. S. [Theoretical Section, Space Research Institute of the Russian Academy of Sciences, Profsoyuznaya 84/32, 117997 Moscow (Russian Federation)

2006-10-15

330

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

Microsoft Academic Search

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

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

1996-01-01

331

Predicting heat conduction during solidification of a food inside a freezer due to natural convection  

Microsoft Academic Search

A new mathematical model for numerical simulation of two dimensional food freezing due to natural convection is presented. Fluid mechanics and heat transfer by natural convection between air and a solid food in a freezer are predicted along with the heat conduction inside a plate shaped food. The mathematical model used includes continuity, linear momentum and energy partial differential equations

Nelson O. Moraga; Hernán G. Barraza

2003-01-01

332

The solution heat and conductance of some azomethines nonaqueous solutions at 308.15 K  

NASA Astrophysics Data System (ADS)

Some new azomethines have been synthesized and their characterization was done by IR, 1H NMR, mass spectra and CHN analysis. Further, some physicochemical properties such as heat of solution and conductance have been studied for these synthesized compounds in different solvents at 308.15 K. The heat of solution was also determined at different temperatures.

Baluja, S.; Bhatt, M.

2009-12-01

333

Spinothalamic tract conduction velocity estimated using contact heat evoked potentials: What needs to be considered  

Microsoft Academic Search

ObjectiveLaser-evoked potentials have been shown to be clinically useful for the electrophysiological assessment of nociceptive pathways. Contact heat evoked potentials (CHEP) are less established but might be advantageous for clinical purposes. This study aimed at determining the conduction velocity (CV) of central pain (spinothalamic tract, STT) pathways using contact heat stimulation in order to replicate previous findings using laser stimulation.

Susanne Wydenkeller; Regula Wirz; Pascal Halder

2008-01-01

334

Specific heat and quantized thermal conductance of single-walled boron nitride nanotubes  

Microsoft Academic Search

The thermal properties of single-walled boron nitride nanotubes are calculated. It is found that boron nitride nanotubes have a larger specific heat than that of carbon nanotubes. The fitting formulas for diameter and chirality dependence of specific heat at 300 K are given. Moreover, thermal conductance of single-walled boron nitride nanotubes exhibits a universal quantization at low temperature, which is

Y. Xiao; X. H. Yan; J. X. Cao; J. W. Ding; Y. L. Mao; J. Xiang

2004-01-01

335

Finite element formulation for two-dimensional inverse heat conduction analysis  

Microsoft Academic Search

This paper presents a finite element algorithm for two-dimensional nonlinear inverse heat conduction analysis. The proposed method is capable of handling both unknown surface heat flux and unknown surface temperature of solids using temperature histories measured at a few discrete points. The proposed algorithms were used in the study of the thermofracture behavior of leaking pipelines with experimental verifications.

T. R. Hsu; N. S. Sun; G. G. Chen; Z. L. Gong

1992-01-01

336

Hyperbolic heat conduction equation for materials with a nonhomogeneous inner structure  

Microsoft Academic Search

The physical meaning of the constant Ï in Cattaneo and Vernotte's equation for materials with a nonhomogeneous inner structure has been considered. An experimental determination of the constant Ï has been proposed and some values for selected products have been given. The range of differences in the description of heat transfer by parabolic and hyperbolic heat conduction equations has been

W. Kaminski

1990-01-01

337

On the Truly Meshless Solution of Heat Conduction Problems in Heterogeneous Media  

Microsoft Academic Search

A truly meshless method based on the weighted least-squares (WLS) approximation and the method of point collocation is proposed to solve heat conduction problems in heterogeneous media. It is shown that, in the case of strong heterogeneity, accurate and smooth solutions for temperature and heat flux can be obtained by applying the WLS approximation in each homogeneous domain and using

Jiannong Fang; Gao-Feng Zhao; Jian Zhao; Aurele Parriaux

2009-01-01

338

On the examination of the heat conduction phenomena of low-pressure gases  

Microsoft Academic Search

The authors determine the energy trasferred by heat condution from the cathode of low-pressure gas discharge. They indicate\\u000a for various gases under given discharge conditions the quantity of energy transmitted from the unit surface area of the cathode\\u000a by heat conduction of the gas.

G. Lakatos; J. Bitó

1966-01-01

339

Conducting and heat-insulating paintwork materials based on nickel-plated glass spheres  

Microsoft Academic Search

It is established that nickel-plated hollow glass microspheres can be used as conducting and heat-insulating fillers for paintwork\\u000a material serving as a basis for coatings with low resistivity and good heat-insulating properties.

E. V. Shinkareva; A. M. Safonova

2006-01-01

340

Conductive heat flow anomalies over a hot spot in a moving medium  

Microsoft Academic Search

In the model the hot spot is represented by a point source of heat in an infinite half space moving uniformly in the x direction with velocity U (z is positive downward; y is horizontal and normal to motion). Only steady state conductive heat transfer is considered. The upper boundary condition, zero surface temperature, is satisfied by addition of a

Francis S. Birch

1975-01-01

341

Regularities of unsteady radiative–conductive heat transfer in evaporating semitransparent liquid droplets  

Microsoft Academic Search

The numerical investigation method of unsteady transfer processes in evaporating droplets in radiating media is introduced, evaluating the dependence of optical spectral properties of material upon temperature. The distribution of temperature and heat fluxes regularities in heating and simultaneously evaporating water droplets has been investigated. It is shown that as a cause of interaction of radiation and conduction processes, the

G. Miliauskas

2001-01-01

342

Thermodynamic characterization of the diffusive transport to wave propagation transition in heat conducting thin films  

NASA Astrophysics Data System (ADS)

In this paper, we undertake the thermodynamical analysis of the diffusive transport to wave propagation transition in heat conducting thin films. Several constitutive equations have been conceived to describe heat transport but most fail at the nanometric length scales, where size effects must be taken into account or at time scales in the order of magnitude of heat carriers relaxation time, as for example when a laser pulse is applied to the system. The analysis is based on Jeffrey's model since it allows a jointed description of Fourier and Cattaneo heat conduction mechanisms. Jeffrey's model is complemented with a size dependent heat conductivity derived from Boltzmann transport equation. We study the diffusive transport to wave propagation transition in terms of the group and phase velocity of propagating modes, the system's effective thermodynamic susceptibility, the statistical properties of heat flux fluctuations, and the entropy produced in a thin heat conducting film. Jeffrey's model predicts a kind of discontinuity in the entropy production for thickness film of the order of magnitude of heat carrier mean free path which is corroborated by simulations results from the literature.

Vázquez, F.; del Río, J. A.

2012-12-01

343

Transient coupled radiative–conductive heat transfer in a gray planar medium with anisotropic scattering  

Microsoft Academic Search

Transient radiative and conductive heat transfer in an absorbing, emitting and anisotropically scattering gray slab is investigated. The medium is confined within parallel walls and is excited by a heat pulse stimulation on the front face. The phase function corresponds to a second-degree anisotropic scattering and includes isotropic, linearly anisotropic and Rayleigh modes of scattering. The semi-analytical approach, based on

M. Lazard; S. Andre; D. Maillet

2001-01-01

344

Endogenic heat from Enceladus' south polar fractures: New observations, and models of conductive surface heating  

Microsoft Academic Search

Linear features dubbed “tiger stripes” in the south polar region of Enceladus have anomalously high heat fluxes and are the apparent source of the observed plume. Several explanations for the observed activity have been proposed, including venting from a subsurface reservoir of liquid water, sublimation of surface ice, dissociation of clathrates, and shear heating. Thermal modeling presented in this work,

Oleg Abramov; John R. Spencer

2009-01-01

345

Numerical simulation of a latent heat thermal energy storage system with enhanced heat conduction  

Microsoft Academic Search

A latent heat storage system has been designed to take advantage of the off-peak electrical energy for space heating. Using an enthalpy formation and a fully implicit finite difference method, the thermal performance of such a storage system with and without fins has been analysed. For the one-dimensional simulation model, calculations have been made for the melt fraction and energy

M. Costa; D. Buddhi; A. Oliva

1998-01-01

346

On the Conduction and Convection Heat Transfer From Lightweight Advanced Heat Sinks  

Microsoft Academic Search

Seamless advancements in the electronics industry lead to high heat fluxes from very limited thermal real estates. Use of natural convection air cooling is of interest to meet some of the low flux cooling needs, while active cooling techniques via liquid or forced convection are the methods of choice. In natural convection heat transfer applications, the components used for cooling

M. Baris Dogruoz; Mehmet Arik

2010-01-01

347

Effects of wall conduction, internal heat sources and an internal baffle on natural convection heat transfer in a rectangular enclosure  

Microsoft Academic Search

Conjugate natural convection heat transfer in a two-dimensional, air-filled enclosure containing discrete internal heat sources and an internal baffle is examined. The enclosure formed of finite conductive walls is designed to simulate the behavior of an experimental window calorimeter in order to correct for losses from the calorimeter. The equations are solved using a finite-volume method for a wide range

A. F. Emery

1997-01-01

348

Strain effect on lattice vibration, heat capacity, and thermal conductivity of graphene  

NASA Astrophysics Data System (ADS)

First-principle calculation based on density functional theory is performed to study the lattice vibration, heat capacity, and thermal conductivity of graphene under strain. Two degenerate optical branches in the phonon dispersion curves split near the G points due to the reduced crystal symmetry, and the frequencies of the optical phonon modes shift down thus inducing more phonon modes at a given temperature. The heat capacity is increased, but the thermal conductivity is reduced because of enhanced Umklapp scattering among more phonons. This phenomenon should be considered when determining the heat management of graphene-based devices.

Ma, F.; Zheng, H. B.; Sun, Y. J.; Yang, D.; Xu, K. W.; Chu, Paul K.

2012-09-01

349

Thermoelasticity of thin shells based on the time-fractional heat conduction equation  

NASA Astrophysics Data System (ADS)

The time-nonlocal generalizations of Fourier's law are analyzed and the equations of the generalized thermoelasticity based on the time-fractional heat conduction equation with the Caputo fractional derivative of order 0 < ? ? 2 are presented. The equations of thermoelasticity of thin shells are obtained under the assumption of linear dependence of temperature on the coordinate normal to the median surface of a shell. The conditions of Newton's convective heat exchange between a shell and the environment have been assumed. In the particular case of classical heat conduction (? = 1) the obtained equations coincide with those known in the literature.

Povstenko, Yuriy

2013-06-01

350

Fracture mechanics associated with non-classical heat conduction in thermoelastic media  

NASA Astrophysics Data System (ADS)

This paper studies the thermoelastic fracture in a solid under non-classical Fourier heat conduction. The temperature field and the associated thermal stresses are solved by the dual integral equation technique. Both thermally insulated crack and heated crack are considered. It is found that the crack tip thermal stress is singular and can be expressed in terms of the thermal stress intensity factor in a closed-form. Numerical results show that the crack considerably amplifies the local thermal stresses, confirming the significance of the effect of non-classical heat conduction on the thermoelastic fracture mechanics of materials.

Wang, BaoLin; Han, JieCai

2012-03-01

351

Thermoelasticity of thin shells based on the time-fractional heat conduction equation  

NASA Astrophysics Data System (ADS)

The time-nonlocal generalizations of Fourier's law are analyzed and the equations of the generalized thermoelasticity based on the time-fractional heat conduction equation with the Caputo fractional derivative of order 0 < ? ? 2 are presented. The equations of thermoelasticity of thin shells are obtained under the assumption of linear dependence of temperature on the coordinate normal to the median surface of a shell. The conditions of Newton's convective heat exchange between a shell and the environment have been assumed. In the particular case of classical heat conduction ( ? = 1) the obtained equations coincide with those known in the literature.

Povstenko, Yuriy

2013-06-01

352

3D constraint effect on 3D fatigue crack propagation  

Microsoft Academic Search

As typical examples, tensile round bars with elliptical surface cracks are used to illustrate the three-dimensional (3D) constraint effect and the characteristics of 3D fatigue crack propagation. Based on the latest plastic constraint theory and the concept of equivalent thickness Beq, a practical 3D crack closure model, which can be as well used to obtain material da\\/dN??Keff curves, is developed

Haijun Shen; Wanlin Guo

2005-01-01

353

SB3D User Manual, Santa Barbara 3D Radiative Transfer Model  

SciTech Connect

SB3D is a three-dimensional atmospheric and oceanic radiative transfer model for the Solar spectrum. The microphysics employed in the model are the same as used in the model SBDART. It is assumed that the user of SB3D is familiar with SBDART and IDL. SB3D differs from SBDART in that computations are conducted on media in three-dimensions rather than a single column (i.e. plane-parallel), and a stochastic method (Monte Carlo) is employed instead of a numerical approach (Discrete Ordinates) for estimating a solution to the radiative transfer equation. Because of these two differences between SB3D and SBDART, the input and running of SB3D is more unwieldy and requires compromises between model performance and computational expense. Hence, there is no one correct method for running the model and the user must develop a sense to the proper input and configuration of the model.

O'Hirok, William

1999-01-01

354

Analysis of a Bayonet-Type Counterflow Heat Exchanger with Axial Conduction and Radiative Heat Loss  

Microsoft Academic Search

A counterflow heat exchanger model, based on a bayonet-type configuration, has been developed for predicting the performance of small-scale thermal systems. The purpose of the model is to predict how well a counterflow heat exchanger works for isolating high temperatures for devices that might act as miniature combustors, fuel reformers, or micro-reactors. Three thermal loss mechanisms are considered: (1) flow

Richard B. Peterson; John A. Vanderhoff

2001-01-01

355

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

SciTech Connect

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.

Allan, M.L.

1997-11-01

356

Analysis of the Conduction Heat Transfer in Cantilevers under Steady State Cryogenic Conditions  

Microsoft Academic Search

An accurate analysis of the conduction heat transfer in a cryogenic flask is made and some useful formulae are derived. Taking into account the temperature dependence of conductivity and tensile strength of the supporting rods for a helium cryostat, these formulae may provide more exact results than the the formulae based on simpler models. This allows the design of the

Sever Spanulescu

2009-01-01

357

A Multi-Dimensional Cognitive Analysis of Undergraduate Physics Students' Understanding of Heat Conduction  

ERIC Educational Resources Information Center

This study proposes a multi-dimensional approach to investigate, represent, and categorize students' in-depth understanding of complex physics concepts. Clinical interviews were conducted with 30 undergraduate physics students to probe their understanding of heat conduction. Based on the data analysis, six aspects of the participants' responses…

Chiou, Guo-Li; Anderson, O. Roger

2010-01-01

358

Thermal diffusivity, thermal conductivity, and specific heat of flax fiber–HDPE biocomposites at processing temperatures  

Microsoft Academic Search

There is increasing work on the use of flax fibers as reinforcement for manufacturing composites because of their lower cost and environmental benefit. During manufacturing of such natural fiber–plastic composites, heat transfer is involved, but information about the thermal conductivity and thermal diffusivity at the processing temperatures is not available. In this study, the thermal conductivity, thermal diffusivity, and specific

Xue Li; Lope G. Tabil; Ikechukwuka N. Oguocha; Satyanarayan Panigrahi

2008-01-01

359

Modelling heat capacity, thermal expansion, and thermal conductivity of dioxide components of inert matrix fuel  

Microsoft Academic Search

Based on a simplified model of the phonon spectrum, on the statistical thermodynamics, and on the generalised Klemens model for thermal conductivity, some useful relationships bounding the specific heat capacity, the thermal expansion coefficient, the bulk modulus and the thermal conductivity of dioxides, often used as components in inert matrix fuel, were deduced in a quasi-harmonic approximation. The developed models

V. Sobolev; S. Lemehov

2006-01-01

360

Collisionless conductivity and stochastic heating of the plasma sheet in the geomagnetic tail  

Microsoft Academic Search

The chaotic single particle orbits in the geomagnetic tail are used to calculate the collisionless conductivity. It is shown that the stochasticity from inhomogeneous magnetic fields leads to a power law decay of the single particle correlation function similar to an elastic collisional process. The height-integrated dissipative part of the collisionless conductivity governs the irreversible stochastic heating of the plasma

Wendell Horton; T. Tajima

1991-01-01

361

Electrical Conductivity during XPS of Heated PMMA: Detection of Core Line and Valence Band Tacticity Effects.  

National Technical Information Service (NTIS)

Electrical conductivity during the XPS of approximately 100 nm thick films of PMMA on silicon was induced by heating to above 100 degrees C. Rapid x-ray induced depolymerization set in at about the same temperature. The electrical conductivity allowed acq...

G. Beamson D. T. Clark D. S. L. Law

1998-01-01

362

Meshless Local Petrov-Galerkin Method for Nonlinear Heat Conduction Problems  

Microsoft Academic Search

The meshless local Petrov-Galerkin (MLPG) method is an effective meshless method to solve partial differential equations. In this article, the MLPG method is used to solve nonlinear steady and transient heat conduction problems. The essential boundary condition is enforced by the method of direct interpolation. The moving least-squares (MLS) method is used for interpolation. Thermal conductivity of the material is

Harishchandra Thakur; K. M. Singh; P. K. Sahoo

2010-01-01

363

Fundamental solutions to time-fractional heat conduction equations in two joint half-lines  

NASA Astrophysics Data System (ADS)

Heat conduction in two joint half-lines is considered under the condition of perfect contact, i.e. when the temperatures at the contact point and the heat fluxes through the contact point are the same for both regions. The heat conduction in one half-line is described by the equation with the Caputo time-fractional derivative of order ?, whereas heat conduction in another half-line is described by the equation with the time derivative of order ?. The fundamental solutions to the first and second Cauchy problems as well as to the source problem are obtained using the Laplace transform with respect to time and the cos-Fourier transform with respect to the spatial coordinate. The fundamental solutions are expressed in terms of the Mittag-Leffler function and the Mainardi function.

Povstenko, Yuriy

2013-07-01

364

Artificial Ionospheric Heating Experiments Conducted by a Magnetosphere-Ionosphere Coupling Model  

NASA Astrophysics Data System (ADS)

This presentation discusses computational dynamics and results of artificial heating in the ionosphere. The results are then compared to experiments including a geophysical experiment conducted at the Polar Aeronomy and Radio Science Summer School (PARS) in conjunction with the High Frequency Active Auroral Research Program (HAARP) The computational model includes the following terms: ion inertia, Ohm's law (Hall term, electron pressure term, electron neutral and electron ion collisions), ionization, recombination, electron energy (heat advection, conduction, heating through ionization, ohmic heating, gravity, energy loss to neutrals and ions), as well as parameterized collisions frequencies, and a height resolved neutral atmosphere. Atmospheric conditions for the time of the experiment (plasma density, temperature, etc) are used as initial conditions. The power and frequency of the heater facility are then used to compute the heating of the ionosphere. Data processing for the experiment and model are ongoing.

Stevens, R. J.; Otto, A.; Krzykowski, M.; Solie, D.

2007-12-01

365

The contact heat conductance at diamond-OFHC copper interface with GaIn eutectic as a heat transfer medium  

SciTech Connect

Results of an experimental study of the contact heat conductance across a single diamond crystal interface with OFHC copper (Cu) are reported. Gallium-indium (GaIn) eutectic was used as an interstitial material. Contact conductance data are important in the design and the prediction of the performance of x-ray diamond monochromators under high-heat-load conditions. Two sets of experiments were carried out. In one, the copper surface in contact with diamond was polished and then electroless plated with 1 {mu}m of nickel, while in the other, the copper contact surface was left as machined. Measured average interface heat conductances are 44.7 {plus_minus}8 W/cm{sup 2}{minus}K for nonplated copper and 23.0 {plus_minus}3 W/cm{sup 2}{minus}K for nickel-plated copper. For reference, the thermal contact conductances at a copper-copper interface (without diamond) were also measured, and the results are reported. A typical diamond monochromator, 0.2 mm thick, will absorb about 44 W under a standard undulator beam at the Advanced Photon Source. The measured conductance for nickel-plated copper suggests that the temperature drop across the interface of diamond and nickel-plated copper, with a 20 mm{sup 2} contact area, will be about 10{degree}C. Therefore temperature rises are rather modest, and the accuracy of the measured contact conductances presented here are sufficient for design purposes.

Assoufid, L.; Khounsary, A.M.

1996-01-01

366

Plate Fin Heat Exchanger Model with Axial Conduction and Variable Properties  

SciTech Connect

Future superconducting radio frequency (SRF) cavities, as part of Project X at Fermilab, will be cooled to superfluid helium temperatures by a cryogenic distribution system supplying cold supercritical helium. To reduce vapor fraction during the final Joule-Thomson (J-T) expansion into the superfluid helium cooling bath, counter-flow, plate-fin heat exchangers will be utilized. Due to their compact size and ease of fabrication, plate-fin heat exchangers are an effective option. However, the design of compact and high-effectiveness cryogenic heat exchangers operating at liquid helium temperatures requires consideration of axial heat conduction along the direction of flow, in addition to variable fluid properties. Here we present a numerical model that includes the effects of axial conduction and variable properties for a plate fin heat exchanger. The model is used to guide design decisions on heat exchanger material choice and geometry. In addition, the J-T expansion process is modeled with the heat exchanger to analyze the effect of heat load and cryogenic supply parameters. A numerical model that includes the effects of axial conduction and variable properties for a plate fin heat exchanger was developed and the effect of various design parameters on overall heat exchanger size was investigated. It was found that highly conductive metals should be avoided in the design of compact JT heat exchangers. For the geometry considered, the optimal conductivity is around 3.5 W/m-K and can range from 0.3-10 W/m-K without a large loss in performance. The model was implemented with an isenthalpic expansion process. Increasing the cold side inlet temperature from 2K to 2.2 K decreased the liquid fraction from 0.856 to 0.839 which corresponds to a 0.12 g/s increase in supercritical helium supply needed to maintain liquid level in the cooling bath. Lastly, it was found that the effectiveness increased when the heat load was below the design value. Therefore, the heat exchanger should be sized on the high end of the required heat load.

Hansen, B.J.; White, M.J.; Klebaner, A.; /Fermilab

2011-06-10

367

Conductivity heating a subterranean oil shale to create permeability and subsequently produce oil  

SciTech Connect

This patent describes an improvement in a process in which oil is produced from a subterranean oil shale deposit by extending at least one each of heat-injecting and fluid-producing wells into the deposit, establishing a heat-conductive fluid-impermeable barrier between the interior of each heat-injecting well and the adjacent deposit, and then heating the interior of each heat-injecting well at a temperature sufficient to conductively heat oil shale kerogen and cause pyrolysis products to form fractures within the oil shale deposit through which the pyrolysis products are displaced into at least one production well. The improvement is for enhancing the uniformity of the heat fronts moving through the oil shale deposit. Also described is a process for exploiting a target oil shale interval, by progressively expanding a heated treatment zone band from about a geometric center of the target oil shale interval outward, such that the formation or extension of vertical fractures from the heated treatment zone band to the periphery of the target oil shale interval is minimized.

Van Meurs, P.; DeRouffignac, E.P.; Vinegar, H.J.; Lucid, M.F.

1989-12-12

368

Nonlinear conductivity of lower-hybrid-wave heated plasma in the presence of an electric field  

Microsoft Academic Search

A new conductivity for lower-hybrid-wave heated plasmas is derived. This induced conductivity shows a nonlinear behavior in the presence of an electric field and can represent the plasma as an active element. The role of runaway electrons produced is important on this nonlinear conductivity. The new expression may be important for radio frequency current drive ramp-up and current drive efficiency

E. Farshi; K. N. Sato

2001-01-01

369

Convection Heat and Mass Transfer in an Electrical Conducting Power Law Flow over a Heated Vertical Porous Plate  

Microsoft Academic Search

This paper investigates convection heat and mass transfer flow in an electrically conducting power law fluid past a vertical porous plate in presence of a transverse magnetic field, thermal radiation, and thermal diffusion. The non–linear partial differential equations governing the flow are transformed into ordinary differential equations using the usual similarity method and the resulting similarity equations are solved numerically

B. I. Olajuwon

2010-01-01

370

Static 3D image space  

Microsoft Academic Search

As three-dimensional (3D) techniques continue to evolve from their humble beginnings-nineteenth century stereo photographs and twentieth century movies and holographs, the urgency for advancement in 3D display is escalating, as the need for widespread application in medical imaging, baggage scanning, gaming, television and movie display, and military strategizing increases. The most recent 3D developments center upon volumetric display, which generate

Badia Koudsi; Jim J. Sluss Jr.

2010-01-01

371

3D Spectroscopy in Astronomy  

NASA Astrophysics Data System (ADS)

Preface; Acknowledgements; 1. Introductory review and technical approaches Martin M. Roth; 2. Observational procedures and data reduction James E. H. Turner; 3. 3D Spectroscopy instrumentation M. A. Bershady; 4. Analysis of 3D data Pierre Ferruit; 5. Science motivation for IFS and galactic studies F. Eisenhauer; 6. Extragalactic studies and future IFS science Luis Colina; 7. Tutorials: how to handle 3D spectroscopy data Sebastian F. Sánchez, Begona García-Lorenzo and Arlette Pécontal-Rousset.

Mediavilla, Evencio; Arribas, Santiago; Roth, Martin; Cepa-Nogué, Jordi; Sánchez, Francisco

2011-09-01

372

Color 3D reverse engineering  

Microsoft Academic Search

This paper presents a principle and a method of color 3D laser scanning measurement, based on the fundamental of monochrome 3D measurement study. A new color 3D measurement model was derived, and a rapid calibrating method to measure the system parameters was proposed—the optical plane equation calibrating method. A calibrating drone was made. This paper also advances an auto-merging method

Z. Q Xu; S. H Ye; G. Z Fan

2002-01-01

373

Spherical 3D isotropic wavelets  

NASA Astrophysics Data System (ADS)

Context. Future cosmological surveys will provide 3D large scale structure maps with large sky coverage, for which a 3D spherical Fourier-Bessel (SFB) analysis in spherical coordinates is natural. Wavelets are particularly well-suited to the analysis and denoising of cosmological data, but a spherical 3D isotropic wavelet transform does not currently exist to analyse spherical 3D data. Aims: The aim of this paper is to present a new formalism for a spherical 3D isotropic wavelet, i.e. one based on the SFB decomposition of a 3D field and accompany the formalism with a public code to perform wavelet transforms. Methods: We describe a new 3D isotropic spherical wavelet decomposition based on the undecimated wavelet transform (UWT) described in Starck et al. (2006). We also present a new fast discrete spherical Fourier-Bessel transform (DSFBT) based on both a discrete Bessel transform and the HEALPIX angular pixelisation scheme. We test the 3D wavelet transform and as a toy-application, apply a denoising algorithm in wavelet space to the Virgo large box cosmological simulations and find we can successfully remove noise without much loss to the large scale structure. Results: We have described a new spherical 3D isotropic wavelet transform, ideally suited to analyse and denoise future 3D spherical cosmological surveys, which uses a novel DSFBT. We illustrate its potential use for denoising using a toy model. All the algorithms presented in this paper are available for download as a public code called MRS3D at http://jstarck.free.fr/mrs3d.html

Lanusse, F.; Rassat, A.; Starck, J.-L.

2012-04-01

374

Vection with large screen 3D imagery  

Microsoft Academic Search

Vection is the illusory impression of self motion that can be obtained when an observer views a I,arge screen display containing a rotating or translating pattern. To aid in our construction of an interactive large screen interface to virtual 3D environments, we conducted studies to determine the factors which induce a sense of vection. We found that having a foreground

Kathy Lowther; Colin Ware

1996-01-01

375

3-D Diamond MCM Technology Development Program.  

National Technical Information Service (NTIS)

3-D Diamond MCMs is an enabling technology to support chip-to-chip and module-to-module highconductivity of diamond, coupled with its electrically insulating nature, makes it an ideal choice...

D. A. Schaefer

1998-01-01

376

Conduction heating of objects of simple shape in a fluid with finite heat capacity  

SciTech Connect

A unifed analytical solution and an approximate method are presented for calculating the time to cool or heat an object of simple shape to a given mean temperature, using a fluid with finite heat capacity in batch, parallel-flow, or counterflow modes. In the approximate method, an equivalent constant fluid temperature is calculated, which would give the same log-mean temperature difference. The cooling time at this equivalent temperature is found by conventional methods, then multiplied by a correction factor calculated from a simple regression equation.

Pham, Q.T. (Meat Industry Research Institute of New Zealand, Inc., Hamilton (New Zealand))

1988-08-01

377

3D gaze tracking system for NVidia 3D Vision(®).  

PubMed

Inappropriate parallax setting in stereoscopic content generally causes visual fatigue and visual discomfort. To optimize three dimensional (3D) effects in stereoscopic content by taking into account health issue, understanding how user gazes at 3D direction in virtual space is currently an important research topic. In this paper, we report the study of developing a novel 3D gaze tracking system for Nvidia 3D Vision(®) to be used in desktop stereoscopic display. We suggest an optimized geometric method to accurately measure the position of virtual 3D object. Our experimental result shows that the proposed system achieved better accuracy compared to conventional geometric method by average errors 0.83 cm, 0.87 cm, and 1.06 cm in X, Y, and Z dimensions, respectively. PMID:24110407

Wibirama, Sunu; Hamamoto, Kazuhiko

2013-07-01

378

Surface Heat Loss on Venus due to the Heat Capacities of Thermal Conductivity and Hot-Spot/Corona Volcanism  

NASA Astrophysics Data System (ADS)

A lot of different approaches have been performed in the literature to estimate the surface heat flow on Venus. Estimates based on parameterized convection solutions resulted in values between 15 and 50 mW m-2, in contrast to global scaling from Earth, which results in a distinctively higher amount of heat loss (between ca. 60 and 70 mW m-2) as shown by Phillips R. J. et al. (1997). In our estimate we have considered the capacities of main lithospheric heat transport mechanisms on Venus. On Earth their contribution to the total heat loss is small, because plate-recycling is the most dominant factor. But since the MAGELLAN radar surface mapping mission and theoretical calculations which have shown that presently plate-recycling is not able to be operative on Venus (Leitner J. J. and Firneis M. G. (2005)), the Venusian surface heat loss is only characterized by thermal conductivity and hot-spot/Corona volcanism. Under consideration of the different thermic parameters of the Venusian interior we have calculated the amount of heat loss due to thermal conductivity to be 33.5 mW m-2. The present contribution of hot-spot volcanism, which we have found on Venus to be manifested in the form of Corona-volcanism (under consideration of presumably active or at least in the recent past active sources), yields a quota of 6.0 ± 1.4 mW m-2. A result, which corresponds well with the estimation of the quota of Corona heat loss on Venus given by Stofan E. R. al el. (2001). With this prior estimate we were able to determine the present heat loss on Venus to be 39.5 ± 3.0 mW m-2.

Leitner, J. J.; Firneis, M. G.

2005-04-01

379

Stochastic heat conduction analysis of a functionally graded annular disc with spatially random heat transfer coefficients  

Microsoft Academic Search

The mean and variance of the temperature are analytically obtained in a functionally graded annular disc with spatially random heat transfer coefficients (HTCs) on the upper and lower surfaces. This annular disc has arbitrary variations in the HTCs (i.e., arbitrary thermal interaction with the surroundings) and gradient material composition only along the radial direction and is subjected to deterministic axisymmetrical

Ryoichi Chiba

2009-01-01

380

An Analytical Study on a Model Describing Heat Conduction in Rectangular Radial Fin with Temperature-Dependent Thermal Conductivity  

NASA Astrophysics Data System (ADS)

The coupling of the homotopy perturbation method (HPM) and the variational iteration method (VIM) is a strong technique for solving higher dimensional initial boundary value problems. In this article, after a brief explanation of the mentioned method, the coupled techniques are applied to one-dimensional heat transfer in a rectangular radial fin with a temperature-dependent thermal conductivity to show the effectiveness and accuracy of the method in comparison with other methods. The graphical results show the best agreement of the three methods; however, the amount of calculations of each iteration for the combination of HPM and VIM was reduced markedly for multiple iterations. It was found that the variation of the dimensionless temperature strongly depends on the dimensionless small parameter {\\varepsilon_1}. Moreover, as the dimensionless length increases, the thermal conductivity of the fin decreases along the fin.

Hedayati, F.; Ganji, D. D.; Hamidi, S. M.; Malvandi, A.

2012-06-01

381

On the correlation of electrical conductivity and heat flow in Middle Valley, Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

The near-surface electrical conductivity has been mapped within an area of Middle Valley, a sediment-filled axial valley at the northern end of the Juan de Fuca ridge. The conductivity in the uppermost 20 m of sediment was determined by analyzing the magnetic field signal transmitted between a source coil and a receiver that were towed along the seafloor. The instrument is a version of a time domain electromagnetic (TDEM) sounding system. The heat flow pattern within Middle Valley, with a large central anomaly above a basement high, is reproduced by the conductivity measurements, the result of enhanced pore fluid electrical conductivity due to higher near-surface temperatures in the high heat flow regions. The high correlation between heat flow and conductivity requires that porosity as inferred from Archie's law must be nearly uniform in the central part of the study area. Porosities derived from the conductivity measurements are in close agreement with measurements from the Ocean Drilling Project (ODP) boreholes. Higher near-surface porosities are required in the eastern part of the valley to match the observed heat flow, consistent with the higher porosity seen at ODP site 855. A small region of apparently lower porosity was detected to the west of the center of the valley.

Webb, Spahr C.; Edwards, R. Nigel

1995-11-01

382

Modular 3-D Transport model  

EPA Science Inventory

MT3D was first developed by Chunmiao Zheng in 1990 at S.S. Papadopulos & Associates, Inc. with partial support from the U.S. Environmental Protection Agency (USEPA). Starting in 1990, MT3D was released as a pubic domain code from the USEPA. Commercial versions with enhanced capab...

383

JavaSound3D  

NSDL National Science Digital Library

This java application allows the user to look at the waveform of WAV files or microphone inputs in detail. One can see a graph of the fast fourier transform (FFT) of the data in the window in a 2D or 3D graph. The 3D graph shows how the FFT changes over time.

Bliss, Jennifer; Steele, Brad; Mechtly, Bruce

2008-07-29

384

Computing 3D Periodic Triangulations  

Microsoft Academic Search

Abstract: This work is motivated by the need for software computing 3D periodic triangula- tions in numerous domains including astronomy, material engineering, biomedical computing, fluid dynamics etc. We design an algorithmic test to check whether a partition of the 3D flat torus into tetrahedra forms a triangulation (which subsumes that it is a simplicial complex). We propose an incremental algorithm

Manuel Caroli; Monique Teillaud

2009-01-01

385

Transient thermal cracking associated with non-classical heat conduction in cylindrical coordinate system  

NASA Astrophysics Data System (ADS)

This paper studies the fracture behavior of a thermoelastic cylinder subjected to a sudden temperature change on its outer surface within the framework of non-classical heat conduction. The heat conduction equation is solved by separation of variable technique. Closed form solution for the temperature field and the associated thermal stress are established. The critical parameter governing the level of the transient thermal stress is identified. Exact expression for the transient stress intensity factor is obtained for a crack in the cylinder. The difference between the non-classical solutions and the classical solution are discussed. It is found that the traditional classical heat conduction considerably underestimates the transient thermal stress and thermal stress intensity factor.

Wang, Bao-Lin

2013-04-01

386

Simultaneous Measurement of Thermal Conductivity, Thermal Diffusivity, and Specific Heat of Nanofluids  

Microsoft Academic Search

Effective thermal conductivity, effective thermal diffusivity, and effective specific heat of nanofluids were simultaneously measured by using a transient double hot-wire technique. Several types of nanofluids were prepared by suspending different volume percentages (1 to 5%) of titanium dioxide (TiO2), aluminum oxide (Al2O3) and aluminum (Al) nanoparticles in ethylene glycol and engine oil. While effective specific heats of these nanofluids

S. M. SOHEL MURSHED

2012-01-01

387

A modified sequential function specification finite element-based method for parabolic inverse heat conduction problems  

Microsoft Academic Search

A method for enhancing the stability of parabolic inverse heat conduction problems (IHCP) is presented. The investigation extends recent work on non-iterative finite element-based IHCP algorithms which, following Beck’s two-step approach, first derives a discretized standard form equation relating the instantaneous global temperature and surface heat flux vectors, and then formulates a least squares-based linear matrix normal equation in the

R. G. Keanini; Xianwu Ling; H. P. Cherukuri

2005-01-01

388

A Spatially-Analytical Scheme for Surface Temperatures and Conductive Heat Fluxes in Urban Canopy Models  

Microsoft Academic Search

In the urban environment, surface temperatures and conductive heat fluxes through solid media (roofs, walls, roads and vegetated\\u000a surfaces) are of paramount importance for the comfort of residents (indoors) and for microclimatic conditions (outdoors).\\u000a Fully discrete numerical methods are currently used to model heat transfer in these solid media in parametrisations of built\\u000a surfaces commonly used in weather prediction models.

Zhi-Hua Wang; Elie Bou-Zeid; James A. Smith

2011-01-01

389

Transient conjugated heat transfer in pipes involving two-dimensional wall and axial fluid conduction  

Microsoft Academic Search

This paper presents an analysis for an unsteady conjugated heat transfer problem in thermally developing laminar pipe flow, involving two-dimensional wall and fluid axial conduction. The problem is solved numerically by a finite-difference method for a thick-walled, infinitely long, two-regional pipe which is initially isothermal with a step change in the constant outside temperature of the heated downstream section. A

?efik Bilir

2002-01-01

390

Euro3D Science Conference  

NASA Astrophysics Data System (ADS)

The Euro3D RTN is an EU funded Research Training Network to foster the exploitation of 3D spectroscopy in Europe. 3D spectroscopy is a general term for spectroscopy of an area of the sky and derives its name from its two spatial + one spectral dimensions. There are an increasing number of instruments which use integral field devices to achieve spectroscopy of an area of the sky, either using lens arrays, optical fibres or image slicers, to pack spectra of multiple pixels on the sky (``spaxels'') onto a 2D detector. On account of the large volume of data and the special methods required to reduce and analyse 3D data, there are only a few centres of expertise and these are mostly involved with instrument developments. There is a perceived lack of expertise in 3D spectroscopy spread though the astronomical community and its use in the armoury of the observational astronomer is viewed as being highly specialised. For precisely this reason the Euro3D RTN was proposed to train young researchers in this area and develop user tools to widen the experience with this particular type of data in Europe. The Euro3D RTN is coordinated by Martin M. Roth (Astrophysikalisches Institut Potsdam) and has been running since July 2002. The first Euro3D science conference was held in Cambridge, UK from 22 to 23 May 2003. The main emphasis of the conference was, in keeping with the RTN, to expose the work of the young post-docs who are funded by the RTN. In addition the team members from the eleven European institutes involved in Euro3D also presented instrumental and observational developments. The conference was organized by Andy Bunker and held at the Institute of Astronomy. There were over thirty participants and 26 talks covered the whole range of application of 3D techniques. The science ranged from Galactic planetary nebulae and globular clusters to kinematics of nearby galaxies out to objects at high redshift. Several talks were devoted to reporting recent observations with newly completed 3D instruments - CIRPASS, GMOS, PMAS and SPIFFI. Work on 3D software, being developed as part of the Euro3D RTN, was also described and demonstrated. This proceedings volume, consisting of carefully refereed and edited manuscripts, represents the bulk of the talks at the conference and amply demonstrates that 3D spectroscopy is a lively and burgeoning field of optical observation.

Walsh, J. R.

2004-02-01

391

Evaluation of liquid behavior in a Variable Conductance Heat Pipe by neutron radiography  

NASA Astrophysics Data System (ADS)

A Variable Conductance Heat Pipe (VCHP) is used as a cooling device for electrical equipments. The condensation area is passively controlled by the non-condensable gas volume in the VCHP depending on the heat load. The VCHP has often a bent pipe between the evaporation and condensation area. The heat pipe performance depends much on the bent pipe shape and configuration because a liquid plug is formed in the bent pipe and disturbs the refrigerant circulation. However, the mechanism has not been clarified well. The neutron radiography system at the JRR-3 in Japan Atomic Energy Agency (JAEA) was used to visualize the refrigerant behavior in the VCHP. Effects of the thin plate inserted in the pipe, refrigerant filling ratios and heat pipe configuration were examined on the heat pipe performance. The liquid plug was formed at the bend and caused to decrease the performance. It was confirmed that the thin plate insert was effective to disturb the liquid plug formation.

Sugimoto, K.; Asano, H.; Murakawa, H.; Takenaka, N.; Nagayasu, T.; Ipposhi, S.

2011-09-01

392

Remarks on the thermal conductivity and heat flow density of the Indian Craton  

NASA Astrophysics Data System (ADS)

The virtual or effective thermal conductivity (ETC) of the Indian subcontinental crust model is calculated from geochemical/geothermal data on the mean radiogenic heat production and on the real thermal conductivity (TC) of crystalline rocks of India. This ETC, amounting to about 3.45 W/m·K, is 1.4 time greater than the mean real TC value (about 2.5 W/m·K). This is in good agreement with the empirical relation between the surface heat flow density and the Curie depth for the Indian Craton.

Maj, S?awomir

2008-12-01

393

The temperature dependence of the heat conductivity of a liquid crystal studied by molecular dynamics simulation  

NASA Astrophysics Data System (ADS)

The temperature dependence of the heat conductivity has been obtained for a liquid crystal model based on the Gay-Berne fluid, from the isotropic phase at high temperatures through the nematic phase to the smectic A phase at low temperatures. The ratio of the parallel and the perpendicular components of the heat conductivity is about 2.5:1 in the nematic phase, which is similar to that of real systems. Both Green-Kubo methods and nonequilibrium molecular dynamics methods have been applied and the results agree within in a relative error of a couple of percent, but the latter method is much more efficient.

Sarman, Sten; Laaksonen, Aatto

2010-01-01

394

Conjugate conduction/convection/nucleate-boiling heat transfer with a high-speed boundary layer  

NASA Astrophysics Data System (ADS)

A space-marching boundary-layer program has been extensively modified to model conjugate conduction/convection heat transfer for the case of coflowing high-speed gas and liquid coolant. Solid body conduction is modeled as one-dimensional, constant property heat transfer. The coolant is modeled empirically as a bulk fluid with combined forced convection and nucleate boiling. The flow solver was modified to solve the group of conjugate boundary equations simultaneously and implicitly with the existing momentum and energy equations for the gas. The code has been applied to analysis of a backside water-cooled nozzle for a high-enthalpy, supersonic wind tunnel.

Shope, Frederick L.

1991-12-01

395

Determination of In-Situ Thermal Conductivity, Thermal Diffusivity, Volumetric Specific Heat and Isobaric Specific Heat of Selected Foods Under Pressure  

Microsoft Academic Search

Thermal conductivity, thermal diffusivity, volumetric specific heat, and isobaric specific heat of tomato puree, soy protein isolate, soybean oil, guacamole, honey, cream cheese, and sucrose solution under pressure was determined using a dual needle probe from 0.1 to 600 MPa at 25°C. Thermal conductivity and thermal diffusivity of tested materials increased with applied pressure, while the isobaric specific heat decreased

V. M. Balasubramaniam; S. K. Sastry

2012-01-01

396

Nonlinear transient heat conduction analysis of functionally graded materials in the presence of heat sources using an improved meshless radial point interpolation method  

Microsoft Academic Search

An improved meshless radial point interpolation method, for the analysis of nonlinear transient heat conduction problems is proposed. This method is implemented for the heat conduction analysis of functionally graded materials (FGMs) with non-homogenous and\\/or temperature dependent heat sources. The conventional meshless RPIM is an appropriate numerical technique for the analysis of engineering problems. One advantage of this method is

A. Khosravifard; M. R. Hematiyan; L. Marin

2011-01-01

397

Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data  

USGS Publications Warehouse

Thermal diffusivity and specific heat can be estimated from thermal conductivity measurements made using a standard needle probe and a suitably high data acquisition rate. Thermal properties are calculated from the measured temperature change in a sample subjected to heating by a needle probe. Accurate thermal conductivity measurements are obtained from a linear fit to many tens or hundreds of temperature change data points. In contrast, thermal diffusivity calculations require a nonlinear fit to the measured temperature change occurring in the first few tenths of a second of the measurement, resulting in a lower accuracy than that obtained for thermal conductivity. Specific heat is calculated from the ratio of thermal conductivity to diffusivity, and thus can have an uncertainty no better than that of the diffusivity estimate. Our thermal conductivity measurements of ice Ih and of tetrahydrofuran (THF) hydrate, made using a 1.6 mm outer diameter needle probe and a data acquisition rate of 18.2 pointss, agree with published results. Our thermal diffusivity and specific heat results reproduce published results within 25% for ice Ih and 3% for THF hydrate. ?? 2006 American Institute of Physics.

Waite, W. F.; Gilbert, L. Y.; Winters, W. J.; Mason, D. H.

2006-01-01

398

3-D Video Processing for 3-D TV  

NASA Astrophysics Data System (ADS)

One of the most desirable ways of realizing high quality information and telecommunication services has been called "The Sensation of Reality," which can be achieved by visual communication based on 3-D (Three-dimensional) images. These kinds of 3-D imaging systems have revealed potential applications in the fields of education, entertainment, medical surgery, video conferencing, etc. Especially, three-dimensional television (3-D TV) is believed to be the next generation of TV technology. Figure 13.1 shows how TV's display technologies have evolved , and Fig. 13.2 details the evolution of TV broadcasting as forecasted by the ETRI (Electronics and Telecommunications Research Institute). It is clear that 3-D TV broadcasting will be the next development in this field, and realistic broadcasting will soon follow.

Sohn, Kwanghoon; Kim, Hansung; Kim, Yongtae

399

An investigation on the conduction and convection heat transfer from advanced heat sinks  

Microsoft Academic Search

In natural convection applications, the components used for cooling may represent a significant portion of the overall weight of the system. Consequently, advanced materials are of interest in such applications, as they may substantially reduce the total size and the weight of the system. Many of these advanced materials have anisotropic thermo physical properties, hence the control of thermal conductivity

M. Baris Dogruoz; M. Arik

2008-01-01

400

Metropole-3D: a rigorous 3D topography simulator  

NASA Astrophysics Data System (ADS)

We have extended the capability of a vector 3D lithography simulator METROPOLE-3D from a photomask simulator to become a full 3D photolithography simulator. It is designed to run moderately fast on conventional engineering workstations. METROPOLE-3D solves Maxwell's equations rigorously in three dimensions to model how non-vertically incident light is scattered and transmitted in non-planar structures. METROPOLE- 3D consists of several simulation modules: photomask simulator which models the aerial image of any mask pattern (including phase-shifting masks); exposure simulator which models light intensity distribution within the photoresist and arbitrary underlying non-planar substrate structures; post-exposure baking module which models the photo-active compound diffusion, chemically amplified (CA) photoresist cross-linking and de-protection processes; and finally, 3D development module which models the photoresist development process using the level-set algorithm. This simulator has a wide range of applications in studying the pressing engineering problems encountered in state-of-the-art VLSI fabrication processes. The simulator has been applied to the layout printability/manufacturability analysis to study the dominant physical phenomena in lithography, deposition, CMP and etching processes that affect the transfer of mask patterns to the final etched structures on the wafers. Using this new 3D rigorous photolithography simulator, optical proximity effects have been studied. A reflective notching problem caused by the reflective substrate structure has been thoroughly studied, and an anti-reflective coating (ARC) solution to this notching problem has been optimized by the simulations. Finally, a 3D contamination to defect transformation study was successfully performed using our rigorous simulator.

Li, Xiaolei; Lucas, Kevin D.; Swecker, Aaron L.; Strojwas, Andrzej J.

1998-06-01

401

DYNA3D. Explicit 3-d Hydrodynamic FEM Program  

Microsoft Academic Search

DYNA3D is an explicit, three-dimensional, finite element program for analyzing the large deformation dynamic response of inelastic solids and structures. DYNA3D contains 30 material models and 10 equations of state (EOS) to cover a wide range of material behavior. The material models implemented are: elastic, orthotropic elastic, kinematic\\/isotropic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, Blatz-Ko rubber, high explosive

R. Chu; M. Amakai; H. C. Lung; T. Ishigai

1989-01-01

402

DYNA3D; Explicit 3-d Hydrodynamic FEM Program  

Microsoft Academic Search

DYNA3D is an explicit, three-dimensional, finite element program for analyzing the large deformation dynamic response of inelastic solids and structures. DYNA3D contains 30 material models and 10 equations of state (EOS) to cover a wide range of material behavior. The material models implemented are: elastic, orthotropic elastic, kinematic\\/isotropic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, Blatz-Ko rubber, high explosive

Whirley

1989-01-01

403

DYNA3D. Explicit 3-d Hydrodynamic FEM Program  

Microsoft Academic Search

DYNA3D is an explicit, three-dimensional, finite element program for analyzing the large deformation dynamic response of inelastic solids and structures. DYNA3D contains 30 material models and 10 equations of state (EOS) to cover a wide range of material behavior. The material models implemented are: elastic, orthotropic elastic, kinematic\\/isotropic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, Blatz-Ko rubber, high explosive

R. G. Whirley; B. E. Englemann

1993-01-01

404

DYNA3D. Explicit 3-D Hydrodynamic FEM Program  

Microsoft Academic Search

DYNA3D is an explicit, three-dimensional, finite element program for analyzing the large deformation dynamic response of inelastic solids and structures. DYNA3D contains 30 material models and 10 equations of state (EOS) to cover a wide range of material behavior. The material models implemented are: elastic, orthotropic elastic, kinematic\\/isotropic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, Blatz-Ko rubber, high explosive

Whirley

1989-01-01

405

DYNA3D. Explicit 3-D Hydrodynamic FEM Program  

Microsoft Academic Search

DYNA3D is an explicit, three-dimensional, finite element program for analyzing the large deformation dynamic response of inelastic solids and structures. DYNA3D contains 30 material models and 10 equations of state (EOS) to cover a wide range of material behavior. The material models implemented are: elastic, orthotropic elastic, kinematic\\/isotropic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, Blatz-Ko rubber, high explosive

R. G. Whirley; B. E. Englemann

1993-01-01

406

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

NASA Astrophysics Data System (ADS)

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

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

407

Unassisted 3D camera calibration  

NASA Astrophysics Data System (ADS)

With the rapid growth of 3D technology, 3D image capture has become a critical part of the 3D feature set on mobile phones. 3D image quality is affected by the scene geometry as well as on-the-device processing. An automatic 3D system usually assumes known camera poses accomplished by factory calibration using a special chart. In real life settings, pose parameters estimated by factory calibration can be negatively impacted by movements of the lens barrel due to shaking, focusing, or camera drop. If any of these factors displaces the optical axes of either or both cameras, vertical disparity might exceed the maximum tolerable margin and the 3D user may experience eye strain or headaches. To make 3D capture more practical, one needs to consider unassisted (on arbitrary scenes) calibration. In this paper, we propose an algorithm that relies on detection and matching of keypoints between left and right images. Frames containing erroneous matches, along with frames with insufficiently rich keypoint constellations, are detected and discarded. Roll, pitch yaw , and scale differences between left and right frames are then estimated. The algorithm performance is evaluated in terms of the remaining vertical disparity as compared to the maximum tolerable vertical disparity.

Atanassov, Kalin; Ramachandra, Vikas; Nash, James; Goma, Sergio R.

2012-02-01

408

A peridynamic formulation for transient heat conduction in bodies with evolving discontinuities  

NASA Astrophysics Data System (ADS)

We introduce a multidimensional peridynamic formulation for transient heat-transfer. The model does not contain spatial derivatives and uses instead an integral over a region around a material point. By construction, the formulation converges to the classical heat transfer equations in the limit of the horizon (the nonlocal region around a point) going to zero. The new model, however, is suitable for modeling, for example, heat flow in bodies with evolving discontinuities such as growing insulated cracks. We introduce the peridynamic heat flux which exists even at sharp corners or when the isotherms are not smooth surfaces. The peridynamic heat flux coincides with the classical one in simple cases and, in general, it converges to it in the limit of the peridynamic horizon going to zero. We solve test problems and compare results with analytical solutions of the classical model or with other numerical solutions. Convergence to the classical solutions is seen in the limit of the horizon going to zero. We then solve the problem of transient heat flow in a plate in which insulated cracks grow and intersect thus changing the heat flow patterns. We also model heat transfer in a fiber-reinforced composite and observe transient but steep thermal gradients at the interfaces between the highly conductive fibers and the low conductivity matrix. Such thermal gradients can lead to delamination cracks in composites from thermal fatigue. The formulation may be used to, for example, evaluate effective thermal conductivities in bodies with an evolving distribution of insulating or permeable, possibly intersecting, cracks of arbitrary shapes.

Bobaru, Florin; Duangpanya, Monchai

2012-04-01

409

A numerical study of performance of a slider bearing with heat conduction to the pad  

Microsoft Academic Search

A numerical study of thermohydrodynamic performance of a high-speed slider bearing with conduction to a stationary pad has been analyzed. The partial differential equations governing the fluid-film mass, momentum and energy conservations coupled with the heat conduction equation for the solid stationary pad assuming temperature-dependent density and viscosity, are solved using streamline upwind Petrov–Galerkin finite element method to yield various

B. V. Rathish Kumar; P. Srinivasa Rao; Prawal Sinha

2001-01-01

410

Rapid Measurement of Thermal Conductivity by Transient Heating of a Fine ThermoJunction  

Microsoft Academic Search

Transient methods of measuring thermal conductivities of poor conductors are very rapid and can be applied to small systems. By recording the temperature of an electrically heated wire, the conductivity of the environment can be determined in a fraction of a second. Thus with a wire of radius 10-2 cm the measuring time is less than 10-1s and the effective

R. A. W. Hill

1957-01-01

411

Radiative heat transfer in transient hot-wire measurements of thermal conductivity  

Microsoft Academic Search

New measurements of the thermal conductivity of liquid toluene between 300 and 550 K have been used to study the importance of radiative heat transfer when using the transient hot-wire technique. The experimental data were used to obtain the radiation correction to the hot-wire temperature rises. Radiationcorrected values of thermal conductivity are reported. This study shows that the transient hot-wire

C. A. Nieto de Castro; R. A. Perkins; H. M. Roder

1991-01-01

412

Effective Thermal Conductivity Measurement and Heat Transfer Enhancement of Metal Hydride Bed for Heat Driven Type Refrigerator  

NASA Astrophysics Data System (ADS)

A series of study has been performed on the metal hydride beds of Ti0.15Zr0.85Cr0.9Fe0.6Ni0.2Mn0.3Cu0.05 (MH-1, using for heat source), Ti0.73Zr0.27Cr1.2Fe0.3Ni0.1Mn0.4Cu0.05 (MH-2, using for cooling load) to measure the effective thermal conductivities. The effective thermal conductivities of MH alloy bed in hydrogen and helium have been examined. Experiment results show that pressure has great influence on effective thermal conductivity in low pressure range. And that influence decreases rapidly with increase of gas pressure. The reason is at low pressure, the mean free path of gas becomes greater than effective thickness of gas film which is important to the heat transfer mechanism. Then, carbon fiber has been used to try to enhance the poor thermal conductivity of MH alloy bed. Three types, two insert methods and three weight percentages of carbon fiber have been examined and compared. The highest effective thermal conductivity has been reached with carbon fiber which has second higher thermal conductivity, and highest weight percentage. This method has acquired 5.4 times higher thermal conductivity than pure metal hydride beds with quite low quantity of additives, only 1.7 wt % of carbon fiber. This is a good result comparing to other method which can reach higher effective thermal conductivity but needs much higher percentage of additives too.

Bae, Sang-Chul; Matsuishi, Yukino; Monde, Masanori; Katsuta, Masafumi

413

Magnetosphere-ionosphere coupling through E region turbulence: 2. Anomalous conductivities and frictional heating  

NASA Astrophysics Data System (ADS)

Global magnetospheric MHD codes using ionospheric conductances based on laminar models systematically overestimate the cross-polar cap potential during storm time by up to a factor of 2. At these times, strong DC electric fields penetrate to the E region and drive plasma instabilities that create turbulence. This plasma density turbulence induces nonlinear currents, while associated electrostatic field fluctuations result in strong anomalous electron heating. These two effects will increase the global ionospheric conductance. On the basis of the theory of nonlinear currents developed by Dimant and Oppenheim [2011], this paper derives the correction factors describing turbulent conductivities and calculates turbulent frictional heating rates. Estimates show that during strong geomagnetic storms the inclusion of anomalous conductivity can double the total Pedersen conductance. This may help explain the overestimation of the cross-polar cap potentials by existing MHD codes. The turbulent conductivities and frictional heating presented in this paper should be included in global magnetospheric codes developed for predictive modeling of space weather.

Dimant, Y. S.; Oppenheim, M. M.

2011-09-01

414

Conductivity  

NSDL National Science Digital Library

Students make a simple conductivity tester using a battery and light bulb. They learn the difference between conductors and insulators of electrical energy as they test a variety of materials for their ability to conduct electricity.

Integrated Teaching And Learning Program

415

Conductive heating and microwave hydrolysis under identical heating profiles for advanced anaerobic digestion of municipal sludge.  

PubMed

Microwave (2.45 GHz, 1200 W) and conventional heating (custom pressure vessel) pretreatments were applied to dewatered municipal waste sludge (18% total solids) using identical heating profiles that span a wide range of temperatures (80-160 °C). Fourteen lab-scale semi-continuous digesters were set up to optimize the energy (methane) output and sludge retention time (SRT) requirements of untreated (control) and thermally pretreated anaerobic digesters operated under mesophilic and thermophilic temperatures. Both pretreatment methods indicated that in the pretreatment range of 80-160 °C, temperature was a statistically significant factor (p-value < 0.05) for increasing solubilization of chemical oxygen demand and biopolymers (proteins, sugars, humic acids) of the waste sludge. However, the type of pretreatment method, i.e. microwave versus conventional heating, had no statistically significant effect (p-value >0.05) on sludge solubilization. With the exception of the control digesters at a 5-d SRT, all control and pretreated digesters achieved steady state at all three SRTs, corresponding to volumetric organic loading rates of 1.74-6.96 g chemical oxygen demand/L/d. At an SRT of 5 d, both mesophilic and thermophilic controls stopped producing biogas after 20 d of operation with total volatile fatty acids concentrations exceeding 1818 mg/L at pH <5.64 for mesophilic and 2853 mg/L at pH <7.02 for thermophilic controls, while the pretreated digesters continued producing biogas. Furthermore, relative (to control) organic removal efficiencies dramatically increased as SRT was shortened from 20 to 10 and then 5 d, indicating that the control digesters were challenged as the organic loading rate was increased. Energy analysis showed that, at an elevated temperature of 160 °C, the amount of methane recovered was not enough to compensate for the energy input. Among the digesters with positive net energy productions, control and pretreated digesters at 80 °C were more favorable at an SRT of 10 d. PMID:23866153

Mehdizadeh, Seyedeh Neda; Eskicioglu, Cigdem; Bobowski, Jake; Johnson, Thomas

2013-06-07

416

Propagation of a cylindrical shock wave in a rotating dusty gas with heat conduction and radiation heat flux  

NASA Astrophysics Data System (ADS)

A self-similar solution for the propagation of a cylindrical shock wave in a dusty gas with heat conduction and radiation heat flux, which is rotating about the axis of symmetry, is investigated. The shock is assumed to be driven out by a piston (an inner expanding surface) and the dusty gas is assumed to be a mixture of non-ideal gas and small solid particles. The density of the ambient medium is assumed to be constant. The heat conduction is expressed in terms of Fourier's law and radiation is considered to be of diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient ?R are assumed to vary with temperature and density. Similarity solutions are obtained, and the effects of variation of the parameter of non-idealness of the gas in the mixture, the mass concentration of solid particles and the ratio of density of solid particles to the initial density of the gas are investigated.

Vishwakarma, J. P.; Nath, G.

2010-04-01

417

LETTER: Normal heat conductivity in a strongly pinned chain of anharmonic oscillators  

Microsoft Academic Search

We consider a chain of coupled and strongly pinned anharmonic oscillators subject to a non-equilibrium random forcing. Assuming that the stationary state is approximately Gaussian, we first derive a stationary Boltzmann equation. By localizing the involved resonances and identifying the umklapp processes, we next invert the linearized collision operator and compute the heat conductivity. In particular, we show that the

Raphael Lefevere; Alain Schenkel

2006-01-01

418

Measurement of thermal conductivity and heat capacity in an undergraduate physics laboratory  

Microsoft Academic Search

An undergraduate laboratory course experiment on thermal properties of low diffusivity materials is fully described. The experimental setup is of simple construction, not requiring the use of vacuum techniques nor temperature controllers. From the transient regime data, thermal conductivity as well as specific heat capacity can be determined.

J. H. Talpe; V. I. Bekeris; C. E. Acha

1990-01-01

419

Specific heat and thermal conductivity of UCu4+ x Al8- x compounds  

NASA Astrophysics Data System (ADS)

We report on thermal conductivity and specific heat measurements for eight UCu4+ x Al8- x compounds (0 ? x ? 2.0) as a function of temperature and magnetic field. For this series of compounds, previous magnetic and transport studies indicated a transition from magnetic to a non-magnetic heavy fermion state near x cr ? 1.15. This paper presents supplementary specific heat and thermal conductivity studies. The ratio of the specific heat over temperature C/T data on the non magnetic compound with x cr ? 1.15 show logarithmic dependence with T, a hallmark of non-Fermi liquid (NFL) behavior due to the proximity of a quantum critical point. Compounds with higher Cu content ( x > x cr ) exhibit unusual temperature scaling in the specific heat possibly due to an increase in disorder between Cu and Al. Thermal conductivity data show stark contrast in the behaviors between the magnetic ( x = 0.5) and non-magnetic compound ( x = 1.75). Our results confirm that a simple free-electron picture is inadequate for the description of the low-temperature thermal conductivity properties in non-magnetic UCu4+ x Al8- x compounds.

Nasreen, F.; Torikachvili, M. S.; Kothapalli, K.; Kohama, Y.; Zapf, V. S.; Nakotte, H.

2013-05-01

420

Stability in the Linear Theory of Heat Conducting, Chemically Reacting Media.  

National Technical Information Service (NTIS)

Using the method of energy integrals, the asymptotic behavior of solutions for large time is studied in the context of the linear theory of heat conducting, chemically reacting media. Stability is established for the initial-value problem in the general c...

R. R. Nachlinger J. W. Nunziato

1975-01-01

421

Homogenization and Upscaling for Diffusion, Heat Conduction, and Wave Propagation in Heterogeneous Materials  

Microsoft Academic Search

We present a general homogenization method for diffusion, heat conduction, and wave propagation in a periodic heterogeneous material with piecewise constants. The method is relevant to the frequently encountered upscaling issues for heterogeneous materials. The dispersion relation for each problem is first expressed in the general form where the frequency ? (or wavenumber k) is expanded in terms of the

Xu Zhi-Jie

2012-01-01

422

Theoretical and experimental investigation of heat conduction for large temperature differences at arbitrary Knudsen number  

Microsoft Academic Search

The plane steady-state heat conduction in monatomic gases at large temperature differences was studied. An approximate solution of the Boltzman equation, based on a two-sided Maxwellian velocity distribution function and the model of Maxwellian molecules, was investigated. This solution, obtained by using Maxwell's moment method, can be used to determine macroscopic quantities of state for arbitrary Knudsen numbers. A plane

D. Braun

1976-01-01

423

LOCAL THEORY IN CRITICAL SPACES FOR COMPRESSIBLE VISCOUS AND HEAT-CONDUCTIVE GASES  

Microsoft Academic Search

We are concerned with local existence and uniqueness of solutions for a general model of viscous and heat-conductive gases with low regularity assumptions on the initial data (the velocity and the temperature may be discontinuous). Local well-posedness is showed to hold in spaces which are critical with respect to the scaling of the equations, provided that the initial density is

Raphaël Danchin

2001-01-01

424

On homogenization of a quasilinear elliptic equation connected with heat conductivity 1  

Microsoft Academic Search

Homogenization of a quasilinear elliptic equation with periodic coecien ts is studied. The problem describes heat conductivity in the magnetic cores of large transformers. Coecien ts of the corresponding partial dieren tial equation depend on temperature and are anisotropic due to the laminated structure of the material from which magnetic cores are made. The existence and uniqueness of solutions to

Josef Mal

425

Finite element approximation of a nonlinear heat conduction problem in anisotropic media  

Microsoft Academic Search

This paper is a survey of results which we have obtained in solving a stationary nonlinear heat conduction problem by the finite element method. In particular, we present uniqueness theorems for the classical and weak solutions, a comparison theorem, existence theorems for the weak and finite element solutions, approximation of a curved boundary and numerical integration, a discrete maximum principle,

M. Krízek; L. Liu

1998-01-01

426

Prediction of local thermal contact conductance in plate finned-tube heat exchangers  

Microsoft Academic Search

An inverse problem utilizing the conjugate gradient method (CGM) of minimization with adjoint equation is used successfully to estimate the temporally and circumferentially varying thermal contact conductance of a plate finned-tube heat exchanger by reading the transient temperature measurement data from the thermocouples located on the plate and around the tube.It is assumed that no prior information is available on

Cheng-Hung Huang; Duen-Min Wang; Hsi-Mei Chen

1999-01-01

427

On thermoelastic transients in a general theory of heat conduction with finite wave speeds  

Microsoft Academic Search

Summary The linear Chen-Gurtin-Pipkin theory of heat conduction in a deformable material is employed to study the one dimensional problem of a homogeneous thermoelastic half space subjected to thermal and mechanical disturbances at its boundary. A ray series approach is used to generate asymptotic wavefront expansions for the temperature, strain, and stress response of the medium to the disturbances. General

R. P. Sawatzky; T. B. Moodie

1985-01-01

428

INSTABILITIES ASSOCIATED WITH HEAT CONDUCTION IN THE SOLAR WIND AND THEIR CONSEQUENCES  

Microsoft Academic Search

Associated with the large heat conduction in the solar wind is a skewing of the ion and electron distribution functions. It is shown that this collisional skewing of the electron distribution function can linearly excite collisionless ion-acoustic, electrostatic ion cyclotron, magnetoacoustic, and ion cyclotron waves in the steady-state solar wind even though the net equilibrium current parallel to B is

D. W. Forslund

1970-01-01

429

ADI method for heat conduction problems in an orthogonal coordinate system. [Alternating Direction Implicit scheme  

Microsoft Academic Search

A mathematical model has been developed for the time-dependent heat conduction process in a region of arbitrary geometry. An alternating direction implicit (ADI) scheme has been worked out for the computer solution of the problem in three space dimensions. The time and nodal propagation of the errors are depicted graphically. Also included in the computer software is a subroutine for

K. N. Shukla; D. Ghosh

2009-01-01

430

An apparatus for the rapid determination of the heat conductivity of poor conductors  

Microsoft Academic Search

A method is described of measuring the thermal conductivity of a small sample by bringing it into contact with a hot copper bar and recording the temperature developed at the interfacial contact. A steady temperature is reached in about 30 seconds with samples having a volume of about 10 cm3. This steady temperature value is directly related to the heat

H. Zierfuss

1963-01-01

431

Effect of sidewall conductance on heat-transport measurements for turbulent Rayleigh-Bénard convection  

Microsoft Academic Search

For measurements of turbulent heat transport in Rayleigh-Bénard convection the correction for the sidewall conductance is usually neglected or based on measurements or estimates for the empty cell. It is argued that the lateral thermal coupling between the fluid and the wall can invalidate these approaches, and that corrections based on calculations of the two-dimensional temperature fields are required in

Guenter Ahlers

2001-01-01

432

Review and Comparison of Nanofluid Thermal Conductivity and Heat Transfer Enhancements  

Microsoft Academic Search

This study provides a detailed literature review and an assessment of results of the research and development work forming the current status of nanofluid technology for heat transfer applications. Nanofluid technology is a relatively new field, and as such, the supporting studies are not extensive. Specifically, experimental results were reviewed in this study regarding the enhancement of the thermal conductivity

Wenhua Yu; David M. France; Jules L. Routbort

2008-01-01

433

Analysis of conductive and convective heat transfer in a sedimentary basin, demonstrated for the Rheingraben  

Microsoft Academic Search

SUMMARY The identification and quantification of conductive and convective components in the heat transfer of a sedimentary basin is demonstrated for the Rheingraben. Three different methods of varying complexity as well as three independent data sets are employed: (1) energy budget considerations based on hydraulically perturbed thermal data from shallow boreholes (<500m), (2) 1-D vertical Peclet number analysis of thermal

C. Clauser; H. Villinger

1990-01-01

434

Conduction-dominated heat transport of the annual temperature signal in soil  

Microsoft Academic Search

(1) Conductive heat transport of temperature signals into the subsurface is a central assumption of ground surface temperature (GST) reconstructions derived from present- day temperatures in deep boreholes. Here we test this assumption and its implications for annual relationships between GST and surface air temperature (SAT) by analyzing two decades of shallow soil temperature (0.01-11.7 m) and SAT time series

Jason E. Smerdon; Henry N. Pollack; John W. Enz; Matthew J. Lewis

2003-01-01

435

Effect of carbon-fiber brushes on conductive heat transfer in phase change materials  

Microsoft Academic Search

Brushes made of carbon fibers are used to improve the thermal conductivities of phase change materials packed around heat transfer tubes. The transient thermal responses measured in brush\\/n-octadecane composites essentially improve as the volume fraction of the fibers and the brush diameter increase. However, there is a critical diameter above which further improvement is not expected due to thermal resistance

Jun Fukai; Yuichi Hamada; Yoshio Morozumi; Osamu Miyatake

2002-01-01

436

Simultaneous radiation and conduction heat transfer in a graded index semitransparent slab with gray boundaries  

Microsoft Academic Search

The simultaneous radiation and conduction heat transfer in a semitransparent slab of absorbing–emitting gray medium is solved in this paper. The refractive index of the medium spatially varies in a linear relationship, and the two boundary walls are diffuse and gray. A curved ray tracing technique in combination with a pseudo-source adding method is employed to deduce the radiative intensities

Xin-Lin Xia; Yong Huang; He-Ping Tan; Xiao-Bin Zhang

2002-01-01

437

DIRECT INTEGRATION APPROACH FOR SIMULTANEOUSLY ESTIMATING TEMPERATURE DEPENDENT THERMAL CONDUCTIVITY AND HEAT CAPACITY  

Microsoft Academic Search

One of the difficulties in the solution of inverse heat conduction problems is that of making sufficiently accurate initial guesses for the unknowns in order to start the iterations. In this work a direct integration method is developed for determining good initial guesses for the unknown property coefficients within about 10% error. The Levenberg-Marquardt method is then applied to refine

C. H. Huang; M. N. Özi?ik

1991-01-01

438

Existence of Nonequilibrium Steady State for a Simple Model of Heat Conduction  

NASA Astrophysics Data System (ADS)

This paper contains rigorous results for a simple stochastic model of heat conduction similar to the KMP (Knipnis-Marchiori-Presutti) model but with possibly energy-dependent interaction rates. We prove the existence and uniqueness of nonequilibrium steady states, their relation to Lebesgue measure, and exponential convergence to steady states from suitable initial conditions.

Li, Yao; Young, Lai-Sang

2013-09-01

439

Numerical Simulation of Heat Conduction to Liquids from a Thin Vertical Cylinder  

Microsoft Academic Search

The paper presents numerical simulations of heat conduction around a circular vertical cylinder immersed in liquids. A finite volume formulation is used, and the numerical analysis is performed in unsteady state with an explicit scheme. The numerical predictions are compared with experiments performed on liquids to find the temperature inside the cylinder, where a thermocouple is located, and at the

F. Gori; M. G. Serranò

2003-01-01

440

On the interaction of the electromagnetic field with heat conducting deformable semiconductors  

Microsoft Academic Search

The differential equations and boundary conditions describing the behavior of a finitely deformable, polarizable and magnetizable heat conducting and electrically semiconducting continuum in interaction with the electromagnetic field are derived by means of a systematic application of the laws of continuum physics to a well-defined macroscopic model. The model consists of five suitably defined interpenetrating continua. The relative displacement of

H. G. Delorenzi; H. F. Tiersten

1974-01-01

441

Model of heating and ignition of conductive polydisperse powder in electrostatic discharge  

Microsoft Academic Search

Heating of a conductive polydisperse powder by electrostatic discharge (ESD) is modelled numerically. Powder packing is described using a discrete element model; powder resistance is defined by geometry of particle contacts and properties of plasma produced by electrical breakdown between neighbour particles. A set of parametric calculations in combination with experimental data is used to determine necessary adjustable model parameters.

E. Beloni; E. L. Dreizin

2012-01-01

442

Soliton mechanism of the uranium nitride microdynamics and heat conductivity at high temperatures  

SciTech Connect

The microdynamics of soliton waves and localized modes of nonlinear acoustic and optical oscillations in uranium nitride has been investigated. It is shown that, upon heating, the energies of solitons in the gap between the optical and acoustic phonon bands increase, while the energies of local modes decrease. The experimentally observed quasi-resonance features, which are shifted in the gap with a change in temperature, can be manifestations of the revealed soliton waves and local modes. The microdynamics of uranium nitride heat conductivity with the stochastic generation of the observed solitons and local modes at remote energy absorption have been investigated. The temperature dependence of the heat conductivity coefficient has been determined from the temperature gradient and energy flux within the standard approach (which is to be generalized).

Semenov, V. A.; Dubovsky, O. A., E-mail: dubov@ippe.ru; Orlov, A. V. [State Scientific Center of the Russian Federation Leipunsky Institute for Physics and Power Engineering (Russian Federation)

2011-12-15

443

Heat conduction in systems with Kolmogorov-Arnold-Moser phase space structure.  

PubMed

We study heat conduction in a billiard channel formed by two sinusoidal walls and the diffusion of particles in the corresponding channel of infinite length; the latter system has an infinite horizon, i.e., a particle can travel an arbitrary distance without colliding with the rippled walls. For small ripple amplitudes, the dynamics of the heat carriers is regular and analytical results for the temperature profile and heat flux are obtained using an effective potential. The study also proposes a formula for the temperature profile that is valid for any ripple amplitude. When the dynamics is regular, ballistic conductance and ballistic diffusion are present. The Poincaré plots of the associated dynamical system (the infinitely long channel) exhibit the generic transition to chaos as ripple amplitude is increased. When no Kolmogorov-Arnold-Moser (KAM) curves are present to forbid the connection of all chaotic regions, the mean square displacement grows asymptotically with time t as tln(t). PMID:23030897

Herrera-González, I F; Pérez-Aguilar, H I; Mendoza-Suárez, A; Tututi, E S

2012-09-25

444

3D flash lag illusion.  

PubMed

Objective of this research is to study the presence of 3D flash lag illusion created by a moving object that has a motion-in-depth and a flash object. An object consisting of two thin sticks was simulated to approach the subject who observed it with a stereoscope. In the process of approaching, another stick was briefly presented in the middle of the moving sticks. Five human subjects took part in our experiments and all perceived 3D flash lag illusion. The perceived depth created by 3D flash lag illusion was measured by two different psychophysical experiments, by use of a vernier caliper and by a method of nulling with another depth cue. We studied relation between the perceived depth and the presentation distance. The experimental results indicate that the perceived gap by 3D flash lag illusion is independent from the presentation distance. PMID:15149831

Ishii, Masahiro; Seekkuarachchi, Himali; Tamura, Hiroki; Tang, Zheng

2004-01-01

445

Q3D Elemental Impurities  

Center for Biologics Evaluation and Research (CBER)

Text VersionPage 1. Q3D Elemental Impurities This draft guidance, when finalized, will represent the Food and Drug Administration's ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

446

Experiments on phase transitions of 3D dust clusters  

SciTech Connect

The melting transition for finite 3D Yukawa clusters is studied experimentally. Therefore a cluster with N = 25 particles is heated by a random laser beam. The order breaks down in two steps: At lower heating one finds angular melting. At higher heating also the radial order is destroyed.

Miksch, T.; Schella, A.; Melzer, A. [Institut fuer Physik, Universitaet Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany); Schablinski, J.; Block, D. [Institut fuer Experimentelle und Angewandte Physik, Universitaet Kiel, Olshausenstr. 40-60, 24098 Kiel (Germany)

2011-11-29

447

ESTIMATION OF COOLING FLUXES IN BOILING CONVECTION BY INVERSE HEAT CONDUCTION ON A ROTATING CYLINDER : FEASIBILITY STUDY  

Microsoft Academic Search

A theoretical study of heat exchange during the cooling of a rotating cylinder by an im- pinging jet is carried out. The temperature eld is bidimensional - the longitudinal heat conduction being neglected - and is obtained by solving the heat equation using Laplace and Fourier transforms. In order to assess the external heat ux condition, an inverse method using

F. VOLLE; M. LEBOUCHE; M. GRADECK; D. MAILLET

448

3-D Vector Field Simulation  

NSDL National Science Digital Library

This simulation illustrates a wide range of 3D vector fields, including spherical, radial, and linear. The fields can be displayed as vectors, particle trajectories, equipotentials, and other options. The number of particles, vectors, or streamlines, and the field strength are adjustable. Directions and source code are also included. This is an extension of a 3D Electric and Magnetic Field viewer from the same author.

Falstad, Paul

2004-07-13

449

Fundamentals of 3D halftoning  

Microsoft Academic Search

3D halftoning is a new technique that allows the approximation of digital volumetric objects of varying material density e.g.\\u000a porous media for example, by an ensemble of binary material volume elements called vels. In theory, 3D halftoning is basically\\u000a an extension of the well known 2D halftoning process, as widely used in binary printing applications. In practice, however,\\u000a the development

Qun Lou; Peter Stucki

450

3D Topographic Map Simulation  

NSDL National Science Digital Library

This interactive simulation illustrates how topographic maps are created and used to depict landforms and changes in elevation. Students can sculpt mountains and valleys using a 3-D model and see the changes to the corresponding topographic map, or make alterations to the map and see how the 3-D terrain model changes. The display can be tilted, rotated, or enlarged to view changes to the map and/or terrain model.

2011-04-25

451

Modeling of conductive and convective heat transfers in retinal laser treatments  

NASA Astrophysics Data System (ADS)

Tumor thermo treatment such as photodynamic therapy (PDT) or transpupillary thermotherapy (TTT) deal with long term and large laser spot exposures. The induced temperature increase is not exactly known [1]. Under these conditions convective heat transfers due to the blood flow in the choroid and the choriocapillaris must be considered in addition to the usually calculated heat conduction. From an existing analytical model defining a unique convective term for the whole fundus irradiated with Gaussian irradiance distribution lasers [2], we developed a numerical one allowing a precise modelling of convection and calculating heating evolution and temperature profiles of the fundus of the eye. The aim of this study is to present the modelling and several comparisons between experimental results [3] and numerical ones concerning the convective heat transfers inside the fundus of the eye.

Sandeau, Julien; Caillibotte, Georges; Kandulla, Jochen; Birngruber, Reginald; Apiou-Sbirlea, Gabriela

2006-03-01