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1

2D divertor heat flux distribution using a 3D heat conduction solver in National Spherical Torus Experiment.  

PubMed

The divertor heat flux footprint in tokamaks is often observed to be non-axisymmetric due to intrinsic error fields, applied 3D magnetic fields or during transients such as edge localized modes. Typically, only 1D radial heat flux profiles are analyzed; however, analysis of the full 2D divertor measurements provides opportunities to study the asymmetric nature of the deposited heat flux. To accomplish this an improved 3D Fourier analysis method has been successfully applied in a heat conduction solver (TACO) to determine the 2D heat flux distribution at the lower divertor surface in the National Spherical Torus Experiment (NSTX) tokamak. This advance enables study of helical heat deposition onto the divertor. In order to account for heat transmission through poorly adhered surface layers on the divertor plate, a heat transmission coefficient, defined as the surface layer thermal conductivity divided by the thickness of the layer, was introduced to the solution of heat conduction equation. This coefficient is denoted as ? and a range of values were tested in the model to ensure a reliable heat flux calculation until a specific value of ? led to the constant total deposited energy in the numerical solution after the end of discharge. A comparison between 1D heat flux profiles from TACO and from a 2D heat flux calculation code, THEODOR, shows good agreement. Advantages of 2D heat flux distribution over the conventional 1D heat flux profile are also discussed, and examples of 2D data analysis in the study of striated heat deposition pattern as well as the toroidal degree of asymmetry of peak heat flux and heat flux width are demonstrated. PMID:23464209

Gan, K F; Ahn, J-W; Park, J-W; Maingi, R; McLean, A G; Gray, T K; Gong, X; Zhang, X D

2013-02-01

2

2D divertor heat flux distribution using a 3D heat conduction solver in National Spherical Torus Experiment  

NASA Astrophysics Data System (ADS)

The divertor heat flux footprint in tokamaks is often observed to be non-axisymmetric due to intrinsic error fields, applied 3D magnetic fields or during transients such as edge localized modes. Typically, only 1D radial heat flux profiles are analyzed; however, analysis of the full 2D divertor measurements provides opportunities to study the asymmetric nature of the deposited heat flux. To accomplish this an improved 3D Fourier analysis method has been successfully applied in a heat conduction solver (TACO) to determine the 2D heat flux distribution at the lower divertor surface in the National Spherical Torus Experiment (NSTX) tokamak. This advance enables study of helical heat deposition onto the divertor. In order to account for heat transmission through poorly adhered surface layers on the divertor plate, a heat transmission coefficient, defined as the surface layer thermal conductivity divided by the thickness of the layer, was introduced to the solution of heat conduction equation. This coefficient is denoted as ? and a range of values were tested in the model to ensure a reliable heat flux calculation until a specific value of ? led to the constant total deposited energy in the numerical solution after the end of discharge. A comparison between 1D heat flux profiles from TACO and from a 2D heat flux calculation code, THEODOR, shows good agreement. Advantages of 2D heat flux distribution over the conventional 1D heat flux profile are also discussed, and examples of 2D data analysis in the study of striated heat deposition pattern as well as the toroidal degree of asymmetry of peak heat flux and heat flux width are demonstrated.

Gan, K. F.; Ahn, J.-W.; Park, J.-W.; Maingi, R.; McLean, A. G.; Gray, T. K.; Gong, X.; Zhang, X. D.

2013-02-01

3

Temperature and entropy generation behavior in rectangular ducts with 3-D heat transfer coupling (conduction and convection)  

Microsoft Academic Search

Temperature and entropy generation fields are evaluated for 3-D heat transfer coupling (conduction and convection) using a mathematical and computational model. Results are obtained from numerical simulation and analyzed for conditions of fully developed laminar flow inside rectangular ducts. Thermal boundary conditions, at the walls cross section and axial direction, are non-uniform and not imposed. A numerical method of modified

R. L. Silva; E. C. Garcia

2008-01-01

4

Analysis of Transient Heat Conduction in 3D Anisotropic Functionally Graded Solids, by the MLPG Method  

Microsoft Academic Search

A meshless method based on the local Petrov-Galerkin approach is proposed for the solution of steady-state and transient heat conduction problems in a continuously non- homogeneous anisotropic medium. The Laplace transform is used to treat the time dependence of the variables for transient problems. The an- alyzed domain is covered by small subdomains with a simple geometry. A weak formulation

J. Sladek; V. Sladek; C. L. Tan; S. N. Atluri

2008-01-01

5

Study of non-axisymmetric divertor footprints using 2-D IR and visible cameras and a 3-D heat conduction solver in NSTX  

NASA Astrophysics Data System (ADS)

Toroidally non-axisymmetric divertor profiles during the 3-D field application and for ELMs are studied with simultaneous observation by a new wide angle visible camera and a high speed IR camera. A newly implemented 3-D heat conduction code, TACO, is used to obtain divertor heat flux. The wide angle camera data confirmed the previously reported result on the validity of vacuum field line tracing on the prediction of split strike point pattern by 3-D fields as well as the phase locking of ELM heat flux to the 3-D fields. TACO calculates the 2-D heat flux distribution allowing assessment of toroidal asymmetry of peak heat flux and heat flux width. The degree of asymmetry (?DA) is defined to quantify the asymmetric heat deposition on the divertor surface and is found to have a strong positive dependence on peak heat flux.

Ahn, J.-W.; Gan, K. F.; Scotti, F.; Lore, J. D.; Maingi, R.; Canik, J. M.; Gray, T. K.; McLean, A. G.; Roquemore, A. L.; Soukhanovskii, V. A.

2013-07-01

6

Development of a measurement technique for highly conductive CVD diamonds and analysis of uncertanties due to 3D heat losses  

Microsoft Academic Search

Thermal spreaders have been of interest over the last few decades. Heat pipes, Thermal Pyrolytic Graphite (TPG), and other graphite-based materials have been commonly used for enhancing the thermal performance. This study will start for a discussion of Chemical Vapor Deposition (CVD) of diamond manufacturing to enable high conductivity plates for heat spreading. Later attention will be turned to absolute

Mehmet Arik; Ri Li; Kristian Andreini; Jared Crosby; Dave Shaddock; Huseyin Kizil

2010-01-01

7

Investigation into the effect of heat treatment on the thermal conductivity of 3-D carbon\\/carbon fiber composites  

Microsoft Academic Search

The material used in this study was a carbon-carbon fiber composite manufactured from precursor yarn and petroleum based pitch through a process of repetitive densification of a woven preform. The resultant high temperature-high strength material exhibits relatively high thermal conductivity and is thus of interest to the fusion energy, plasma materials interactions (PMI) and plasma facing components (PFC) communities. Carbon-carbon

R. B. Dinwiddie; T. D. Burchell; C. F. Baker

1991-01-01

8

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

9

3D Thermal Modeling for Planetary Heat Flow Measurements  

NASA Astrophysics Data System (ADS)

We report on a variety of new modeling approaches for interpreting Lunar and Martian geothermal heat flow data. Heat Flow measurements aim to inform us of the global radiogenic composition, but are often complicated by local and regional effects. Interpretation of the Apollo Heat Flow measurements, new geothermal heat flow constraints from LRO, and the upcoming InSight mission to Mars depend heavily on our ability to model 3-dimensional heat transport through the crust. Past modeling of these problems has relied on analytic approximations and 1-dimensional studies. Recent computing developments, such as 3D finite element models, allow us to re-examine some of these problems in unprecedented detail. In this presentation, we hope to provide an overview of the need for and utility of such modeling in interpreting heat flow on terrestrial bodies. We will present on progress using 3D conduction models examining the Apollo Heat Flow Experiment. This includes a study of the cause of a slow steady warming in the Apollo Heat Flow Experiment data that has been unresolved for nearly 40 years (Langseth et al., 1976; Grott et al., 2010). We will examine the implications for the composition of the lunar interior (Siegler et al., 2013). We will examine the ability to derive new heat flow values from recent Diviner Lunar Radiometer measurements in the polar regions of the Moon (Siegler et al., 2012). Once deemed impossible due to our inability to separate the effects of lateral heat flux (Lachenbruch, 1965), interpretation of these measurements require a detailed understanding of lateral heat flow from nearby warmer regions. Finally, we will present on 3D thermal modeling of the InSight landing site on both a regional and local scale. Near the crustal dichotomy boundary and one of the largest igneous provinces on Mars, interpretation of InSight heat flow values will depend greatly on our understanding of regional effects on 3D heat flow. Additionally, we introduce efforts toward examining effects of local heat disturbances (such as shadowing and removal of dust) caused by the lander itself and how these may affect our first geothermal measurements from Mars.

Siegler, M. A.; Smrekar, S. E.; Platt, J.; Paige, D. A.; Williams, J.

2013-12-01

10

Analytical solution for the 3D steady state conduction in a solid subjected to a moving rectangular heat source and surface cooling  

Microsoft Academic Search

Heating of solids, e.g. by friction or welding, plays an important role in the thermomechanical behaviour of materials. An analytical model to compute the three-dimensional temperature distribution in a solid, subjected to a moving rectangular heat source with surface cooling is proposed in this article. A frequential integral transform and a finite cosine Fourier integral transform are used to solve

Talaat Osman; Abderrahmane Boucheffa

2009-01-01

11

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

12

Conduction mechanisms in 2D and 3D SIS capacitors  

NASA Astrophysics Data System (ADS)

In this paper, we present a study of conduction mechanisms observed in high performance SIS capacitors (semiconductor-insulator-semiconductor) fabricated on bulk silicon. The combination of high aspect ratio 3D patterns and thin dielectric layers enables amazing capacitance density values. Electrical measurement and modeling of leakage currents have been associated with structural analysis in order to characterize different oxide-nitride stacks, and thus, to scale the layers and reach even higher capacitance densities. Conduction mechanisms are relevant of Fowler-Nordheim tunneling and Poole-Frenkel emission.

Jacqueline, Sébastien; Domengès, Bernadette; Voiron, Frédéric; Murray, Hugues

2013-04-01

13

3D conductive nanocomposite scaffold for bone tissue engineering  

PubMed Central

Bone healing can be significantly expedited by applying electrical stimuli in the injured region. Therefore, a three-dimensional (3D) ceramic conductive tissue engineering scaffold for large bone defects that can locally deliver the electrical stimuli is highly desired. In the present study, 3D conductive scaffolds were prepared by employing a biocompatible conductive polymer, ie, poly(3,4-ethylenedioxythiophene) poly(4-styrene sulfonate) (PEDOT:PSS), in the optimized nanocomposite of gelatin and bioactive glass. For in vitro analysis, adult human mesenchymal stem cells were seeded in the scaffolds. Material characterizations using hydrogen-1 nuclear magnetic resonance, in vitro degradation, as well as thermal and mechanical analysis showed that incorporation of PEDOT:PSS increased the physiochemical stability of the composite, resulting in improved mechanical properties and biodegradation resistance. The outcomes indicate that PEDOT:PSS and polypeptide chains have close interaction, most likely by forming salt bridges between arginine side chains and sulfonate groups. The morphology of the scaffolds and cultured human mesenchymal stem cells were observed and analyzed via scanning electron microscope, micro-computed tomography, and confocal fluorescent microscope. Increasing the concentration of the conductive polymer in the scaffold enhanced the cell viability, indicating the improved microstructure of the scaffolds or boosted electrical signaling among cells. These results show that these conductive scaffolds are not only structurally more favorable for bone tissue engineering, but also can be a step forward in combining the tissue engineering techniques with the method of enhancing the bone healing by electrical stimuli.

Shahini, Aref; Yazdimamaghani, Mostafa; Walker, Kenneth J; Eastman, Margaret A; Hatami-Marbini, Hamed; Smith, Brenda J; Ricci, John L; Madihally, Sundar V; Vashaee, Daryoosh; Tayebi, Lobat

2014-01-01

14

Heat Transfer Boundary Conditions in the RELAP5-3D Code  

SciTech Connect

The heat transfer boundary conditions used in the RELAP5-3D computer program have evolved over the years. Currently, RELAP5-3D has the following options for the heat transfer boundary conditions: (a) heat transfer correlation package option, (b) non-convective option (from radiation/conduction enclosure model or symmetry/insulated conditions), and (c) other options (setting the surface temperature to a volume fraction averaged fluid temperature of the boundary volume, obtaining the surface temperature from a control variable, obtaining the surface temperature from a time-dependent general table, obtaining the heat flux from a time-dependent general table, or obtaining heat transfer coefficients from either a time- or temperature-dependent general table). These options will be discussed, including the more recent ones.

Richard A. Riemke; Cliff B. Davis; Richard R. Schultz

2008-05-01

15

Steady state heat transport in 3D heterogeneous porous media  

NASA Astrophysics Data System (ADS)

Heat is transported in aquifers by advection and conduction. Spatial variability of hydraulic conductivity causes fluctuations in small scale advection, whose effect can be represented by a dispersion term. However, the use of this term is still subject to controversy among modelers. The effect of heterogeneity on the heat plume generated by a groundwater heat exchanger (GHE) in a three-dimensional aquifer under steady state conditions is examined. Transverse dispersion is estimated using a stochastic approach in which a distinction between effective and ensemble dispersion coefficients is made. The former quantifies the typical width of the heat plume and the latter takes into account the uncertainty of the lateral plume position. Simulations show that transverse dispersion is proportional to the variance and correlation length of the log-conductivity field. On the one hand, the ensemble transverse dispersion coefficient, which can be used for risk analysis to find the mean temperature and the potential plume spread, is high near the heat source and then decreases. On the other hand, the effective transverse dispersion coefficient, the one required to simulate actual temperature values and plume width, displays a less marked dependence on the distance from the source. For modeling purposes it can be approximated as ?T?0.02?lnK2Lx, where ?lnK2 is the variance of the log-conductivity field and Lx its correlation length in the mean flow direction. However, a zero dispersion should be used to compute the energy dissipated by the GHE.

Hidalgo, Juan J.; Carrera, Jesús; Dentz, Marco

2009-08-01

16

Conducting the Heat  

NASA Technical Reports Server (NTRS)

Heat conduction plays an important role in the efficiency and life span of electronic components. To keep electronic components running efficiently and at a proper temperature, thermal management systems transfer heat generated from the components to thermal surfaces such as heat sinks, heat pipes, radiators, or heat spreaders. Thermal surfaces absorb the heat from the electrical components and dissipate it into the environment, preventing overheating. To ensure the best contact between electrical components and thermal surfaces, thermal interface materials are applied. In addition to having high conductivity, ideal thermal interface materials should be compliant to conform to the components, increasing the surface contact. While many different types of interface materials exist for varying purposes, Energy Science Laboratories, Inc. (ESLI), of San Diego, California, proposed using carbon velvets as thermal interface materials for general aerospace and electronics applications. NASA s Johnson Space Center granted ESLI a Small Business Innovation Research (SBIR) contract to develop thermal interface materials that are lightweight and compliant, and demonstrate high thermal conductance even for nonflat surfaces. Through Phase II SBIR work, ESLI created Vel-Therm for the commercial market. Vel-Therm is a soft, carbon fiber velvet consisting of numerous high thermal conductivity carbon fibers anchored in a thin layer of adhesive. The velvets are fabricated by precision cutting continuous carbon fiber tows and electrostatically flocking the fibers into uncured adhesive, using proprietary techniques.

2003-01-01

17

On calculation of 3-D eddy currents in conducting and magnetic shells  

SciTech Connect

The impedance type boundary conditions are derived for 3-D eddy currents in conducting and magnetic shells. These boundary conditions are then represented only in terms of magnetic field. This leads to a new magnetic scalar potential formulation for 3-D eddy currents in conducting and magnetic shells. This scalar potential formulation is reduced to weak Galerkin forms. The finite element discretization of these forms results in volume and surface ``stiffness`` matrices.

Mayergoyz, I.D. [Univ. of Maryland, College Park, MD (United States)] [Univ. of Maryland, College Park, MD (United States); Bedrosian, G. [GE Corporate Research and Development, Schenectady, NY (United States)] [GE Corporate Research and Development, Schenectady, NY (United States)

1995-05-01

18

Thermally Induced Apoptosis, Necrosis, and Heat Shock Protein Expression in 3D Culture.  

PubMed

This study was conducted to compare the heat shock responses of cells grown in 2D and 3D culture environments as indicated by the level of heat shock protein 70 expression and the incidence of apoptosis and necrosis of prostate cancer cell lines in response to graded hyperthermia. PC3 cells were stably transduced with a dual reporter system composed of two tandem expression cassettes-a conditional heat shock protein promoter driving the expression of green fluorescent protein (HSPp-GFP) and a cytomegalovirus (CMV) promoter controlling the constitutive expression of a "beacon" red fluorescent protein (CMVp-RFP). Two-dimensional and three-dimensional cultures of PC3 prostate cancer cells were grown in 96-well plates for evaluation of their time-dependent response to supraphysiological temperature. To induce controlled hyperthermia, culture plates were placed on a flat copper surface of a circulating water manifold that maintained the specimens within ±0.1?°C of a target temperature. Hyperthermia protocols included various combinations of temperature, ranging from 37?°C to 57?°C, and exposure times of up to 2 h. The majority of protocols were focused on temperature and time permutations, where the response gradient was greatest. Post-treatment analysis by flow cytometry analysis was used to measure the incidences of apoptosis (annexin V-FITC stain), necrosis (propidium iodide (PI) stain), and HSP70 transcription (GFP expression). Cells grown in 3D compared with 2D culture showed reduced incidence of apoptosis and necrosis and a higher level of HSP70 expression in response to heat shock at the temperatures tested. Cells responded differently to hyperthermia when grown in 2D and 3D cultures. Three-dimensional culture appears to enhance survival plausibly by activating protective processes related to enhanced-HSP70 expression. These differences highlight the importance of selecting physiologically relevant 3D models in assessing cellular responses to hyperthermia in experimental settings. PMID:24658653

Song, Alfred S; Najjar, Amer M; Diller, Kenneth R

2014-07-01

19

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. 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. Each problem is concisely described by geometry and condition statements, and many times a descriptive sketch is also included. The introduction presents a synopsis on the theory, differential equations, and boundary conditions for conduction heat transfer. Some discussion is given on the use and interpretation of solutions. Supplementary data such as mathematical functions, convection correlations, and thermal properties are included for aiding the user in computing numerical values from the solutions. 155 figs., 92 refs., 9 tabs.

VanSant, J.H.

1983-08-01

20

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

21

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

22

Experimental justification for using 3D conductivity reconstructions in electrical impedance tomography.  

PubMed

Conductivity imaging of the breast using electrical impedance tomography (EIT) is a three-dimensional (3D) problem since the induced currents are free to travel through the entire tissue volume. It is therefore necessary to determine the effect this 3D current flow has on the image reconstruction problem and to ascertain how much benefit is gained by using a more appropriate 3D model to estimate the conductivity distribution. In addition, it is important to consider how much is gained if measurements are collected from multiple circular arrays of electrodes positioned around the breast as opposed to just a single plane of electrodes. We used a 64 electrode EIT system to collect data from a series of high contrast saline phantoms to determine the benefits gained by using a 3D model and the incorporation of out-of-plane measurements. We found that it is preferable to use a 3D mesh even when looking only at a single plane through the object of interest and that this 3D mesh should extend in the axial direction at least one radius away from the plane of interest. Further, out-of-plane measurements enhance axial information and improve the quantification of reconstructed inclusions by a factor of 2.2 in the particular case presented here. These findings should ultimately be incorporated to clinical imaging with EIT when circular electrode arrays are employed. PMID:17664629

Halter, Ryan J; Hartov, Alex; Paulsen, Keith D

2007-07-01

23

Superlow thermal conductivity 3D carbon nanotube network for thermoelectric applications.  

PubMed

Electrical and thermal transportation properties of a novel structured 3D CNT network have been systematically investigated. The 3D CNT net work maintains extremely low thermal conductivity of only 0.035 W/(m K) in standard atmosphere at room temperature, which is among the lowest compared with other reported CNT macrostructures. Its electrical transportation could be adjusted through a convenient gas-fuming doping process. By potassium (K) doping, the original p-type CNT network converted to n-type, whereas iodine (I(2)) doping enhanced its electrical conductivity. The self-sustainable homogeneous network structure of as-fabricated 3D CNT network made it a promising candidate as the template for polymer composition. By in situ nanoscaled composition of 3D CNT network with polyaniline (PANI), the thermoelectric performance of PANI was significantly improved, while the self-sustainable and flexible structure of the 3D CNT network has been retained. It is hoped that as-fabricated 3D CNT network will contribute to the development of low-cost organic thermoelectric area. PMID:22132803

Chen, Jikun; Gui, Xuchun; Wang, Zewei; Li, Zhen; Xiang, Rong; Wang, Kunlin; Wu, Dehai; Xia, Xugui; Zhou, Yanfei; Wang, Qun; Tang, Zikang; Chen, Lidong

2012-01-01

24

Kinetic simulations of 3-D Farley-Buneman turbulence and anomalous electron heating  

NASA Astrophysics Data System (ADS)

Electric fields map from the magnetosphere to the E region ionosphere where they drive the intense currents of the auroral electrojet. Particularly during geomagnetic storms and substorms, these currents become sufficiently intense to develop Farley-Buneman (FB) streaming instabilities and become turbulent. This leads to anomalous electron heating which can raise the electron temperature from 300 K to as much as 4000 K and, also, modifies auroral conductivities. This paper describes the first fully kinetic 3-D simulations of electric field-driven turbulence in the electrojet and compares the results with 2-D simulations and observations. These simulations show that 3-D turbulence can dramatically elevate electron temperatures, enough to explain the observed heating. They also show the saturated amplitude of the waves; coupling between linearly growing modes and damped modes; the propagation of the dominant modes at phase velocities near the acoustic velocity, slower than in 2-D simulations; and anomalous cross-field electron transport, leading to a greatly increased E region Pedersen conductivity. These simulations provide information useful in accurately modeling FB turbulence and represent significant progress in understanding the electrojet.

Oppenheim, M. M.; Dimant, Y. S.

2013-03-01

25

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

26

Coronal heating above active regions - 3D MHD model versus multi-spacecraft observations  

NASA Astrophysics Data System (ADS)

The plasma heating mechanism in the Solar corona is a puzzle since decades. Today high-performance computing together with multi-spacecraft observations offer new insights. We conducted a high-resolution simulation of the corona above an active region and compare synthetic emission deduced from the model with co-temporal observations. Photospheric observations act as a boundary condition for our model that drives magnetic-field braiding by advection and generates a net upwards Poynting flux. In particular, we do not only get a sufficient energy input to the base of the corona, but we also reproduce the observed coronal loops: the 3D structure of the hot AR loops system in the model compares well to joint STEREO-A/-B and Hinode observations. The plasma flows along these loops are similar to observed Doppler maps. Draining and siphon flows along magnetic structures at different temperatures offer a new alternative explanation for the average Doppler red-shifts in the transition region and coronal blue-shifts. This match between model and observations indicates a realistic distribution of the coronal heating in time and space and shows that our 3D MHD model of the corona captures the relevant processes involved.

Bourdin, Philippe-A.; Bingert, Sven; Peter, Hardi

2014-05-01

27

3D fabrication of all-polymer conductive microstructures by two photon polymerization.  

PubMed

A technique to fabricate electrically conductive all-polymer 3D microstructures is reported. Superior conductivity, high spatial resolution and three-dimensionality are achieved by successive application of two-photon polymerization and in situ oxidative polymerization to a bi-component formulation, containing a photosensitive host matrix and an intrinsically conductive polymer precursor. By using polyethylene glycol diacrylate (PEG-DA) and 3,4-ethylenedioxythiophene (EDOT), the conductivity of 0.04 S/cm is reached, which is the highest value for the two-photon polymerized all-polymer microstructures to date. The measured electrical conductivity dependency on the EDOT concentration indicates percolation phenomenon and a three-dimensional nature of the conductive pathways. Tunable conductivity, biocompatibility, and environmental stability are the characteristics offered by PEG-DA/EDOT blends which can be employed in biomedicine, MEMS, microfluidics, and sensorics. PMID:24514677

Kurselis, Kestutis; Kiyan, Roman; Bagratashvili, Victor N; Popov, Vladimir K; Chichkov, Boris N

2013-12-16

28

Validation of Heat Transfer and Film Cooling Capabilities of the 3-D RANS Code TURBO  

NASA Technical Reports Server (NTRS)

The capabilities of the 3-D unsteady RANS code TURBO have been extended to include heat transfer and film cooling applications. The results of simulations performed with the modified code are compared to experiment and to theory, where applicable. Wilcox s k-turbulence model has been implemented to close the RANS equations. Two simulations are conducted: (1) flow over a flat plate and (2) flow over an adiabatic flat plate cooled by one hole inclined at 35 to the free stream. For (1) agreement with theory is found to be excellent for heat transfer, represented by local Nusselt number, and quite good for momentum, as represented by the local skin friction coefficient. This report compares the local skin friction coefficients and Nusselt numbers on a flat plate obtained using Wilcox's k-model with the theory of Blasius. The study looks at laminar and turbulent flows over an adiabatic flat plate and over an isothermal flat plate for two different wall temperatures. It is shown that TURBO is able to accurately predict heat transfer on a flat plate. For (2) TURBO shows good qualitative agreement with film cooling experiments performed on a flat plate with one cooling hole. Quantitatively, film effectiveness is under predicted downstream of the hole.

Shyam, Vikram; Ameri, Ali; Chen, Jen-Ping

2010-01-01

29

Methodology for the Assessment of 3D Conduction Effects in an Aerothermal Wind Tunnel Test  

NASA Technical Reports Server (NTRS)

This slide presentation reviews a method for the assessment of three-dimensional conduction effects during test in a Aerothermal Wind Tunnel. The test objectives were to duplicate and extend tests that were performed during the 1960's on thermal conduction on proturberance on a flat plate. Slides review the 1D versus 3D conduction data reduction error, the analysis process, CFD-based analysis, loose coupling method that simulates a wind tunnel test run, verification of the CFD solution, Grid convergence, Mach number trend, size trends, and a Sumary of the CFD conduction analysis. Other slides show comparisons to pretest CFD at Mach 1.5 and 2.16 and the geometries of the models and grids.

Oliver, Anthony Brandon

2010-01-01

30

3D Conditional Fractal Simulation of Hydraulic Conductivity at the MADE Site  

NASA Astrophysics Data System (ADS)

Conventional characterization methods can be combined with Gaussian geostatistical methods to develop 3D hydraulic conductivity (K) fields for sites with low levels of heterogeneity. Parameterization of K fields for flow and transport modeling in highly heterogeneous aquifers, however, remains challenging. Novel stochastic and geostatistical methods have been proposed to improve simulations of highly heterogeneous K fields, but these generally rely on in-situ measurement methods that are invasive, provide limited spatial sampling, and have large support volumes with unknown geometries. We present fully conditional fractal simulations to faithfully synthesize 3D non-Gaussian K fields at the Macro Dispersion Experiment (MADE) site. Full-resolution ground penetrating radar data were used for soft conditioning, to separate hydrologically distinct facies. High-resolution K data from a novel Direct Push tool were then used for hard conditioning and estimation of required facies parameters, including fractal dimensions and correlation lengths. The resulting 3D K fields were used in a flow and transport model. These simulations reproduced the long tailed behavior of observed concentration histories, characteristic of tracer tests at the MADE site.

Dogan, M.; Meerschaert, M. M.; Benson, D. A.; Hyndman, D. W.; Van Dam, R. L.; Butler, J. J.; Bohling, G.

2011-12-01

31

Exceptional Electrical Conductivity and Fracture Resistance of 3D Interconnected Graphene Foam/Epoxy Composites.  

PubMed

Cellular-structured graphene foam (GF)/epoxy composites are prepared based on a three-step fabrication process involving infiltration of epoxy into the porous GF. The three-dimensional (3D) GF is grown on a Ni foam template via chemical vapor deposition. The 3D interconnected graphene network serves as fast channels for charge carriers, giving rise to a remarkable electrical conductivity of the composite, 3 S/cm, with only 0.2 wt % GF. The corresponding flexural modulus and strength increase by 53 and 38%, respectively, whereas the glass transition temperature increases by a notable 31 °C, compared to the solid neat epoxy. The GF/epoxy composites with 0.1 wt % GF also deliver an excellent fracture toughness of 1.78 MPa·m(1/2), 34 and 70% enhancements against their "porous" epoxy and solid epoxy counterparts, respectively. These observations signify the unrivalled effectiveness of 3D GF relative to 1D carbon nanotubes or 2D functionalized graphene sheets as reinforcement for polymer composites without issues of nanofiller dispersion and functionalization prior to incorporation into the polymer. PMID:24848106

Jia, Jingjing; Sun, Xinying; Lin, Xiuyi; Shen, Xi; Mai, Yiu-Wing; Kim, Jang-Kyo

2014-06-24

32

Characterization of 3D interconnected microstructural network in mixed ionic and electronic conducting ceramic composites.  

PubMed

The microstructure and connectivity of the ionic and electronic conductive phases in composite ceramic membranes are directly related to device performance. Transmission electron microscopy (TEM) including chemical mapping combined with X-ray nanotomography (XNT) have been used to characterize the composition and 3-D microstructure of a MIEC composite model system consisting of a Ce0.8Gd0.2O2 (GDC) oxygen ion conductive phase and a CoFe2O4 (CFO) electronic conductive phase. The microstructural data is discussed, including the composition and distribution of an emergent phase which takes the form of isolated and distinct regions. Performance implications are considered with regards to the design of new material systems which evolve under non-equilibrium operating conditions. PMID:24615571

Harris, William M; Brinkman, Kyle S; Lin, Ye; Su, Dong; Cocco, Alex P; Nakajo, Arata; DeGostin, Matthew B; Chen-Wiegart, Yu-chen Karen; Wang, Jun; Chen, Fanglin; Chu, Yong S; Chiu, Wilson K S

2014-05-01

33

Characterization of 3D interconnected microstructural network in mixed ionic and electronic conducting ceramic composites  

NASA Astrophysics Data System (ADS)

The microstructure and connectivity of the ionic and electronic conductive phases in composite ceramic membranes are directly related to device performance. Transmission electron microscopy (TEM) including chemical mapping combined with X-ray nanotomography (XNT) have been used to characterize the composition and 3-D microstructure of a MIEC composite model system consisting of a Ce0.8Gd0.2O2 (GDC) oxygen ion conductive phase and a CoFe2O4 (CFO) electronic conductive phase. The microstructural data is discussed, including the composition and distribution of an emergent phase which takes the form of isolated and distinct regions. Performance implications are considered with regards to the design of new material systems which evolve under non-equilibrium operating conditions.The microstructure and connectivity of the ionic and electronic conductive phases in composite ceramic membranes are directly related to device performance. Transmission electron microscopy (TEM) including chemical mapping combined with X-ray nanotomography (XNT) have been used to characterize the composition and 3-D microstructure of a MIEC composite model system consisting of a Ce0.8Gd0.2O2 (GDC) oxygen ion conductive phase and a CoFe2O4 (CFO) electronic conductive phase. The microstructural data is discussed, including the composition and distribution of an emergent phase which takes the form of isolated and distinct regions. Performance implications are considered with regards to the design of new material systems which evolve under non-equilibrium operating conditions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06684c

Harris, William M.; Brinkman, Kyle S.; Lin, Ye; Su, Dong; Cocco, Alex P.; Nakajo, Arata; Degostin, Matthew B.; Chen-Wiegart, Yu-Chen Karen; Wang, Jun; Chen, Fanglin; Chu, Yong S.; Chiu, Wilson K. S.

2014-04-01

34

Variable conductance heat pipe technology  

NASA Technical Reports Server (NTRS)

Research and development programs in variable conductance heat pipe technology were conducted. The treatment has been comprehensive, involving theoretical and/or experimental studies in hydrostatics, hydrodynamics, heat transfer into and out of the pipe, fluid selection, and materials compatibility, in addition to the principal subject of variable conductance control techniques. Efforts were not limited to analytical work and laboratory experimentation, but extended to the development, fabrication and test of spacecraft hardware, culminating in the successful flight of the Ames Heat Pipe Experiment on the OAO-C spacecraft.

Marcus, B. D.; Edwards, D. K.; Anderson, W. T.

1973-01-01

35

FURN3D: A computer code for radiative heat transfer in pulverized coal furnaces  

SciTech Connect

A computer code FURN3D has been developed for assessing the impact of burning different coals on heat absorption pattern in pulverized coal furnaces. The code is unique in its ability to conduct detailed spectral calculations of radiation transport in furnaces fully accounting for the size distributions of char, soot and ash particles, ash content, and ash composition. The code uses a hybrid technique of solving the three-dimensional radiation transport equation for absorbing, emitting and anisotropically scattering media. The technique achieves an optimal mix of computational speed and accuracy by combining the discrete ordinate method (S[sub 4]), modified differential approximation (MDA) and P, approximation in different range of optical thicknesses. The code uses spectroscopic data for estimating the absorption coefficients of participating gases C0[sub 2], H[sub 2]0 and CO. It invokes Mie theory for determining the extinction and scattering coefficients of combustion particulates. The optical constants of char, soot and ash are obtained from dispersion relations derived from reflectivity, transmissivity and extinction measurements. A control-volume formulation is adopted for determining the temperature field inside the furnace. A simple char burnout model is employed for estimating heat release and evolution of particle size distribution. The code is written in Fortran 77, has modular form, and is machine-independent. The computer memory required by the code depends upon the number of grid points specified and whether the transport calculations are performed on spectral or gray basis.

Ahluwalia, R.K.; Im, K.H.

1992-08-01

36

FURN3D: A computer code for radiative heat transfer in pulverized coal furnaces  

SciTech Connect

A computer code FURN3D has been developed for assessing the impact of burning different coals on heat absorption pattern in pulverized coal furnaces. The code is unique in its ability to conduct detailed spectral calculations of radiation transport in furnaces fully accounting for the size distributions of char, soot and ash particles, ash content, and ash composition. The code uses a hybrid technique of solving the three-dimensional radiation transport equation for absorbing, emitting and anisotropically scattering media. The technique achieves an optimal mix of computational speed and accuracy by combining the discrete ordinate method (S{sub 4}), modified differential approximation (MDA) and P, approximation in different range of optical thicknesses. The code uses spectroscopic data for estimating the absorption coefficients of participating gases C0{sub 2}, H{sub 2}0 and CO. It invokes Mie theory for determining the extinction and scattering coefficients of combustion particulates. The optical constants of char, soot and ash are obtained from dispersion relations derived from reflectivity, transmissivity and extinction measurements. A control-volume formulation is adopted for determining the temperature field inside the furnace. A simple char burnout model is employed for estimating heat release and evolution of particle size distribution. The code is written in Fortran 77, has modular form, and is machine-independent. The computer memory required by the code depends upon the number of grid points specified and whether the transport calculations are performed on spectral or gray basis.

Ahluwalia, R.K.; Im, K.H.

1992-08-01

37

Analytical Solutions for Heat Conduction.  

National Technical Information Service (NTIS)

Green's functions are found for steady state heat conduction in a composite rectangular parallelepiped (RPP) and in a composite right circular cylinder (RCC) assuming no contact resistance. These Green's functions may then be used to provide analytical so...

S. K. Fraley

1976-01-01

38

Heating properties of non-invasive hyperthermia treatment for abdominal deep tumors by 3-D FEM.  

PubMed

This paper discusses the heating properties of a new type of hyperthermia system composed of a re-entrant type resonant cavity applicator for deep tumors of the abdominal region. In this method, a human body is placed in the gap of two inner electrodes and is non-invasively heated with electromagnetic fields stimulated in the cavity. Here, we calculated temperature distributions of a simple human abdominal phantom model that we constructed to examine the heating properties of the developed hyperthermia system. First, the proposed heating method and a simple abdominal model to calculate the temperature distribution are presented. Second, the computer simulation results of temperature distribution by 3-D FEM are presented. From these results, it was found that the proposed simple human abdominal phantom model composed of muscle, fat and lung was useful to test the heating properties of our heating method. Our heating method was also effective to non-invasively heat abdominal deep tumors. PMID:19963800

Morita, E; Kato, K; Ono, S; Shindo, Y; Tsuchiya, K; Kubo, M

2009-01-01

39

Turbomachinery Heat Transfer and Loss Modeling for 3D Navier-Stokes Codes  

NASA Technical Reports Server (NTRS)

This report's contents focus on making use of NASA Glenn on-site computational facilities,to develop, validate, and apply models for use in advanced 3D Navier-Stokes Computational Fluid Dynamics (CFD) codes to enhance the capability to compute heat transfer and losses in turbomachiney.

DeWitt, Kenneth; Ameri, Ali

2005-01-01

40

Experimental investigation and 3D finite element prediction of the heat affected zone during laser assisted machining of Ti6Al4V alloy  

Microsoft Academic Search

An experimental study was conducted to characterize the heat affected zone produced when laser heating a Ti6Al4V alloy plate workpiece. The emissivity and absorptivity of the Ti6Al4V alloy were determined experimentally. A 3D transient finite element method for a moving Gaussian laser heat source was developed to predict the depth and width of the heat affected zone on the Ti6Al4V

Jihong Yang; Shoujin Sun; Milan Brandt; Wenyi Yan

2010-01-01

41

New transfer functions for probing 3-D mantle conductivity from ground and sea  

NASA Astrophysics Data System (ADS)

The C-response is a conventional transfer function in global electromagnetic induction research and is classically determined from local observations of magnetic variations in the vertical and the horizontal components. Its estimation and interpretation rely on the assumptions that the source of the considered variations is well approximated by a large-scale symmetric (magnetospheric) ring current that can be described by a single spherical harmonic, P10, and that conductivity in the Earth is only a function of depth. However, there is growing evidence for a more complex structure of the magnetospheric source. We investigate the variability of C-responses due to non-P10 contributions to the source. We show that this variability, which we denote as 'source effect' (as opposed to the well-known ocean effect), is significant and persists at all periods. If inverting estimated C-responses for mantle conductivity, this source effect will inevitably be mistaken for conductivity anomalies. To overcome the problem connected with the assumptions for deriving C-responses, we introduce new transfer functions that relate the local vertical component of the magnetic variation to different spherical harmonic coefficients describing the magnetospheric source. The latter are derived from observations of magnetic variations in the horizontal components. The new transfer functions are subsequently estimated with a robust multivariate data analysis tool. By analyzing 16 years of data, collected at the global network of geomagnetic observatories, we demonstrate that the new transfer functions exhibit a significant increase in coherence compared to C-responses, especially at high latitudes. The concept is easily extended to other data types. For example, by relating the voltage variations in abandoned submarine telecommunication cables to spherical harmonic coefficients in the same way as described above, one can define yet another array of transfer functions. In spite of the fact that the newly introduced transfer functions allow for a consistent treatment of a complex spatial structure of the source, the sparse and irregular distribution of geomagnetic observatories and submarine cables impedes a reliable inversion of these data for 3-D mantle conductivity on a global scale. However, in combination with matrix Q-responses estimated from Swarm satellite data, the new transfer functions can be used to probe the 3-D conductivity structure of Earth's mantle.

Püthe, Christoph; Kuvshinov, Alexey; Olsen, Nils

2014-05-01

42

Elastic properties and heat capacity of opal matrices and related 3D-nanocomposite materials  

NASA Astrophysics Data System (ADS)

The elastic properties of opal matrices and related 3D-nanocomposites, as well as their heat capacity, have been investigated. The velocities and attenuation coefficients of longitudinal and transverse waves have been measured at room temperature. The Debye temperature has been calculated from the velocities of ultrasound. The temperature dependence of the heat capacity of the opal matrix has been studied. It has been shown that the low-temperature part of this dependence contains contributions proportional to the first and third powers of the temperature. It has been found that the Debye temperatures determined from the velocities of ultrasound and those obtained from the heat capacity differ significantly.

Rinkevich, A. B.; Perov, D. V.; Samoilovich, M. I.; Kleshcheva, S. M.

2010-12-01

43

Finite-Difference Algorithm for Simulating 3D Electromagnetic Wavefields in Conductive Media  

NASA Astrophysics Data System (ADS)

Electromagnetic (EM) wavefields are routinely used in geophysical exploration for detection and characterization of subsurface geological formations of economic interest. Recorded EM signals depend strongly on the current conductivity of geologic media. Hence, they are particularly useful for inferring fluid content of saturated porous bodies. In order to enhance understanding of field-recorded data, we are developing a numerical algorithm for simulating three-dimensional (3D) EM wave propagation and diffusion in heterogeneous conductive materials. Maxwell's equations are combined with isotropic constitutive relations to obtain a set of six, coupled, first-order partial differential equations governing the electric and magnetic vectors. An advantage of this system is that it does not contain spatial derivatives of the three medium parameters electric permittivity, magnetic permeability, and current conductivity. Numerical solution methodology consists of explicit, time-domain finite-differencing on a 3D staggered rectangular grid. Temporal and spatial FD operators have order 2 and N, where N is user-selectable. We use an artificially-large electric permittivity to maximize the FD timestep, and thus reduce execution time. For the low frequencies typically used in geophysical exploration, accuracy is not unduly compromised. Grid boundary reflections are mitigated via convolutional perfectly matched layers (C-PMLs) imposed at the six grid flanks. A shared-memory-parallel code implementation via OpenMP directives enables rapid algorithm execution on a multi-thread computational platform. Good agreement is obtained in comparisons of numerically-generated data with reference solutions. EM wavefields are sourced via point current density and magnetic dipole vectors. Spatially-extended inductive sources (current carrying wire loops) are under development. We are particularly interested in accurate representation of high-conductivity sub-grid-scale features that are common in industrial environments (borehole casing, pipes, railroad tracks). Present efforts are oriented toward calculating the EM responses of these objects via a First Born Approximation approach. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Aldridge, D. F.; Bartel, L. C.; Knox, H. A.

2013-12-01

44

Dust emission from inhomogeneous interstellar clouds: Radiative transfer in 3D with transiently heated particles  

Microsoft Academic Search

Due to the complexity of their structure, the theoretical study of interstellar clouds must be based on three-dimensional models. It is already possible to estimate the distribution of equilibrium dust temperature in fairly large 3D models and, therefore, also to predict the resulting far-infrared and sub-mm emission. Transiently heated particles introduce, however, a significant complication and direct calculation of emission

M. Juvela; P. Padoan

2003-01-01

45

Quasi-3D model to predict temperature distribution in SSC magnets due to 3D heat loads.  

National Technical Information Service (NTIS)

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 hea...

B. Archer R. Schermer G. Snitchler H. Kohli

1993-01-01

46

Models based experimentation: numerical modelling of 3D basin scale architecture heat & fluid flow  

NASA Astrophysics Data System (ADS)

Across all sciences there is trend towards data assimilation of observables into models for prediction and analysis. Within recent years funding agencies have supported significant amounts of research infrastructure primarily purposed to generate data. Geosciences is no exception. Hence, modern practices see a shift from interpretation of geological observations only, to a workflow of models incorporating large data acquisition, geological observations, automated & human architectural interpretations and engineering-style analysis. Autonomous assimilation of observational data into architecture models is still an active research area, however, 3D architecture models as developed by researchers and the surveys, form an acceptable experiment assumption for prediction. The results of a numerical based prediction on an architecture model is a model itself, and hence we create iteratively value-added models. The approach has been applied to heat and fluid flow modelling of basin-scale 3D architecture models of several geological provenances in Australia. The outcome is a basin-by-basin contribution to nation-wide and reservoir 3D heat flow understanding. It includes an iIterative experiment environment, where models (architecture and numerical) are refined as more data is assimilated and questioning increases in complexity.

Quenette, S. M.; Moresi, L. N.

2010-12-01

47

Reconstruction of the 3D flow field in a differentially heated rotating annulus laboratory experiment  

NASA Astrophysics Data System (ADS)

In the earth's atmosphere baroclinic instability is responsible for the heat and momentum transport from low to high latitudes. In the fifties, Raymond Hide used a rather simple laboratory experiment to study such vortices in the lab. The experiment is comprised by a cooled inner and heated outer cylinder mounted on a rotating platform, which mimics the heated tropical and cooled polar regions of the earth's atmosphere. The experiment shows rich dynamics that have been studied by varying the radial temperature difference and the rate of annulus revolution. At the Brandenburg University of Technology (BTU) Cottbus the differentially heated rotating annulus is a reference experiment of the DFG priority program 'MetStröm'. The 3D structure of the annulus flow field has been numerically simulated but, to our knowledge, has not been measured in the laboratory. In the present paper we use novel interpolation techniques to reconstruct the 3D annulus flow field from synchronous Particle Image Velocimetry (PIV) and Infrared Thermography (IRT) measurements. The PIV system is used to measure the horizontal velocity components at 40, 60, 80, 100, and 120 mm above the bottom. The uppermost level is thus 15 mm below the fluid's surface. The surface temperature is simultaneously measured by an infrared (IR) camera. The PIV and infrared cameras have been mounted above the annulus and they co-rotate with the annulus. From the PIV observations alone a coherent 3D picture of the flow cannot be constructed since the PIV measurements have been taken at different instants of time. Therefore a corresponding IR image has been recorded for each PIV measurement. These IR images can be used to reconstruct the correct phase of the measured velocity fields. Each IR and PIV image for which t>0 is rotated back to the position at t=0. Then all surface waves have the same phase. In contrast, the PIV velocity fields generally have different phases since they have been taken at different vertical levels. From these rotated fields, a 3D flow field can be reconstructed that is an approximation to the true 3D flow. The PIV measurements of the horizontal velocity fields do not line up on a nice grid. We therefore use a mesh-free reconstruction method based on radial basis functions (RBFs). Additionally, we employ a filtering strategy for dealing with the noise in the measured velocity fields.

Harlander, U.; Wright, G. B.; Egbers, C.

2012-04-01

48

Modification of divertor heat and particle flux profiles with 3-D fields in NSTX  

NASA Astrophysics Data System (ADS)

Externally imposed non-axisymmetric magnetic perturbations produce multiple local peaks and valleys in the divertor heat and particle flux profiles [1] in NBI-heated plasmas in the National Spherical Torus Experiment (NSTX) with Bt = 0.4T, Ip = 800kA, ?t ˜10%. The addition of 3-D fields causes pronounced lobes to form near the separatrix X-point, which leads to the ``strike point splitting'' [2, 3] and flux striations observed in experiments. ITER may rely on 3--D resonant magnetic perturbation (RMP) fields for ELM suppression, and non-axisymmetric heat and particle deposition and an increase of peak values could pose additional engineering constraints. In NSTX, the radial location and spacing of the divertor striations produced by 3-D fields are reproduced well using vacuum field tracing of the superposition of vacuum 3-D fields and 2-D equilibrium fields [1]. The applied n=3 fields can also trigger ELMs [4]. The ELM heat flux profiles (measured with a new fast IR camera [5]) appear to be phase locked to the n=3 field structure, as also reported in DIII-D experiments [3]. The inclusion of the response of the plasma inside the separatrix (calculated with IPEC [6]) as the base equilibrium for field line tracing did not alter the computed structure of striations significantly compared to the vacuum modeling. This suggests that vacuum field line tracing alone may predict the effect of 3-D fields on divertor profiles even in rapidly rotating, high-? plasmas. This work was supported in part by US DOE, DE-AC05-00OR22725 and DE-AC02-09CH11466.[4pt] [1] J-W. Ahn, et al, Nucl. Fusion 50 (2010) 045010[0pt] [2] T.E. Evans, et al, J. Phy.: Conf. Series 7 (2005) 174[0pt] [3] M.W. Jakubowski, et al, Nucl. Fusion 49 (2009) 095013, and references therein[0pt] [4] J.M. Canik, et al, Phys. Rev. Letts. 104 (2010) 045001[0pt] [5] J-W. Ahn, et al, Rev. Sci. Intrum. 81 (2010) 023501[0pt] [6] J.-K. Park, et al, Phys. Plasmas 14 (2007) 052110

Ahn, Joon-Wook

2010-11-01

49

Prediction of thermal conductivity of air voided-fiber-reinforced composite laminates part II: 3D simulation  

Microsoft Academic Search

Applying the fundamental definition of thermal conductivity to a unit cell of unidirectional fiber reinforced composite with air voids, one can deduce simple empirical formula to predict the thermal conductivity of the composite material with estimated air void volume percent. The inherent 3-D problem is modeled using finite element analysis. The model is tested at different fiber to resin volume

Yagoub N. Al-Nassar

2006-01-01

50

Estimating Hydraulic Conductivities in a Fractured Shale Formation from Pressure Pulse Testing and 3d Modeling  

NASA Astrophysics Data System (ADS)

In the framework of its research on the deep disposal of radioactive waste in shale formations, the French Institute for Radiological Protection and Nuclear Safety (IRSN) has developed a large array of in situ programs concerning the confining properties of shales in their underground research laboratory at Tournemire (SW France). One of its aims is to evaluate the occurrence and processes controlling radionuclide migration through the host rock, from the disposal system to the biosphere. Past research programs carried out at Tournemire covered mechanical, hydro-mechanical and physico-chemical properties of the Tournemire shale as well as water chemistry and long-term behaviour of the host rock. Studies show that fluid circulations in the undisturbed matrix are very slow (hydraulic conductivity of 10-14 to 10-15 m.s-1). However, recent work related to the occurrence of small scale fractures and clay-rich fault gouges indicate that fluid circulations may have been significantly modified in the vicinity of such features. To assess the transport properties associated with such faults, IRSN designed a series of in situ and laboratory experiments to evaluate the contribution of both diffusive and advective process on water and solute flux through a clay-rich fault zone (fault core and damaged zone) and in an undisturbed shale formation. As part of these studies, Modular Mini-Packer System (MMPS) hydraulic testing was conducted in multiple boreholes to characterize hydraulic conductivities within the formation. Pressure data collected during the hydraulic tests were analyzed using the nSIGHTS (n-dimensional Statistical Inverse Graphical Hydraulic Test Simulator) code to estimate hydraulic conductivity and formation pressures of the tested intervals. Preliminary results indicate hydraulic conductivities of 5.10-12 m.s-1 in the fault core and damaged zone and 10-14 m.s-1 in the adjacent undisturbed shale. Furthermore, when compared with neutron porosity data from borehole logging, porosity varies by a factor of 2.5 whilst hydraulic conductivity varies by 2 to 3 orders of magnitude. In addition, a 3D numerical reconstruction of the internal structure of the fault zone inferred from borehole imagery has been built to estimate the permeability tensor variations. First results indicate that hydraulic conductivity values calculated for this structure are 2 to 3 orders of magnitude above those measured in situ. Such high values are due to the imaging method that only takes in to account open fractures of simple geometry (sine waves). Even though improvements are needed to handle more complex geometry, outcomes are promising as the fault damaged zone clearly appears as the highest permeability zone, where stress analysis show that the actual stress state may favor tensile reopening of fractures. Using shale samples cored from the different internal structures of the fault zone, we aim now to characterize the advection and diffusion using laboratory petrophysical tests combined with radial and through-diffusion experiments.

Courbet, C.; DICK, P.; Lefevre, M.; Wittebroodt, C.; Matray, J.; Barnichon, J.

2013-12-01

51

Mapping 3-D mantle electrical conductivity from space: a new 3-D inversion scheme based on analysis of matrix Q-responses  

NASA Astrophysics Data System (ADS)

We present a novel 3-D frequency-domain inversion scheme to recover 3-D mantle conductivity from satellite magnetic data, for example, provided by the Swarm mission. The scheme is based on the inversion of a new set of electromagnetic transfer functions, which form an array that we denote as matrix Q-response and which relate external (inducing) and internal (induced) coefficients of the spherical harmonic expansion of the time-varying magnetic field of magnetospheric origin. This concept overcomes the problems associated with source determination inherent to recent schemes based on direct inversion of internal coefficients. Matrix Q-responses are estimated from time-series of external and internal coefficients with a newly elaborated multivariate analysis scheme. An inversion algorithm that deals with matrix Q-responses has been developed. In order to make the inversion tractable, we elaborated an adjoint approach to compute the data misfit gradient and parallelized the numerical code with respect to frequencies and elementary sources, which describe the external part of the magnetic field of magnetospheric origin. Both parts of the scheme have been verified with realistic test data. Special attention is given to the issue of correlated noise due to undescribed sources.

Püthe, Christoph; Kuvshinov, Alexey

2014-05-01

52

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

2013-04-01

53

Role of 3d-dispersive Alfven waves in coronal heating  

NASA Astrophysics Data System (ADS)

Coronal heating is one of the unresolved puzzles in solar physics from decades. In the present paper we have investigated the dynamics of vortices to apprehend coronal heating problem. A three dimensional (3d) model has been developed to study propagation of dispersive Alfvén waves (DAWs) in presence of ion acoustic waves which results in excitation of DAW and evolution of vortices. Taking ponderomotive nonlinearity into account, development of these vortices has been studied. There are observations of such vortices in the chromosphere, transition region and also in the lower solar corona. These structures may play an important role in transferring energy from lower solar atmosphere to corona and result in coronal heating. Nonlinear interaction of these waves is studied in view of recent simulation work and observations of giant magnetic tornadoes in solar corona and lower atmosphere of sun by solar dynamical observatory (SDO).

Sharma, R. P.; Yadav, N.; Pathak, N.

2014-05-01

54

ALE3D Simulation of Heating and Violence in a Fast Cookoff Experiment with LX-10  

SciTech Connect

We performed a computational and experimental analysis of fast cookoff of LX-10 (94.7% HMX, 5.3% Viton A) confined in a 2 kbar steel tube with reinforced end caps. A Scaled-Thermal-Explosion-eXperiment (STEX) was completed in which three radiant heaters were used to heat the vessel until ignition, resulting in a moderately violent explosion after 20.4 minutes. Thermocouple measurements showed tube temperatures as high as 340 C at ignition and LX-10 surface temperatures as high as 279 C, which is near the melting point of HMX. Three micro-power radar systems were used to measure mean fragment velocities of 840 m/s. Photonics Doppler Velocimeters (PDVs) showed a rapid acceleration of fragments over 80 {micro}s. A one-dimensional ALE3D cookoff model at the vessel midplane was used to simulate the heating, thermal expansion, LX-10 decomposition composition, and closing of the gap between the HE (High Explosive) and vessel wall. Although the ALE3D simulation terminated before ignition, the model provided a good representation of heat transfer through the case and across the dynamic gap to the explosive.

McClelland, M A; Maienschein, J L; Howard, W M; Nichols, A L; deHaven, M R; Strand, O T

2006-06-26

55

Development of Scientific Simulation 3D Full Wave ICRF Code; for Stellarators and Heating\\/CD Scenarios Development  

Microsoft Academic Search

In this report we describe theory and 3D full wave code description for the wave excitation, propagation and absorption in 3-dimensional (3D) stellarator equilibrium high beta plasma in ion cyclotron frequency range (ICRF). This theory forms a basis for a 3D code creation, urgently needed for the ICRF heating scenarios development for the operated LHD, constructed W7-X, NCSX and projected

Vdovin V. L

2005-01-01

56

Dielectric Conduction Mechanisms of Advanced Interconnects: Evidence for Thermally- Induced 3D \\/2 D Transition  

Microsoft Academic Search

Electrical, electro-optical, mechanical and microstructural characterizations explain why the leakage currents in advanced Cu\\/ultra-low K interconnects can change from bulk (3D) to mostly interfacial (2D) above 150degC. A physical model consistent with all these results is proposed

C. Guedj; N. Claret; V. Arnal; M. Aimadeddine; J. P. Barnes; J. C. Barbe; L. Arnaud; G. Reimbold; J. Torres; G. Passemard; F. Boulanger

2006-01-01

57

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

NASA Astrophysics Data System (ADS)

We propose and develop a variational formulation dedicated to the simulation of parallel convective heat exchangers that handles possibly complex input/output conditions as well as connection between pipes. It is based on a spectral method that allows to re-cast three-dimensional heat exchangers into a two-dimensional eigenvalue problem, named the generalized Graetz problem. Our formulation handles either convective, adiabatic, or prescribed temperature at the entrance or at the exit of the exchanger. This formulation is robust to mode truncation, offering a huge reduction in computational cost, and providing insights into the most contributing structure to exchanges and transfer. Several examples of heat exchangers are analyzed, their numerical convergence is tested and the numerical efficiency of the approach is illustrated in the case of Poiseuille flow in tubes.

Pierre, Charles; Bouyssier, Julien; de Gournay, Frédéric; Plouraboué, Franck

2014-07-01

58

North Cascadia heat flux and fluid flow from gas hydrates: Modeling 3-D topographic effects  

NASA Astrophysics Data System (ADS)

bottom-simulating reflector (BSR) of gas hydrate is well imaged from two perpendicular seismic grids in the region of a large carbonate mound, informally called Cucumber Ridge off Vancouver Island. We use a new method to calculate 3-D heat flow map from the BSR depths, in which we incorporate 3-D topographic corrections after calibrated by the drilling results from nearby (Integrated) Ocean Drilling Program Site 889 and Site U1327. We then estimate the associated fluid flow by relating it to the topographically corrected heat flux anomalies. In the midslope region, a heat flux anomaly of 1 mW/m2 can be associated with an approximate focused fluid flow rate of 0.09 mm/yr. Around Cucumber Ridge, high rates of focused fluid flow were observed at steep slopes with values more than double the average regional diffusive fluid discharge rate of 0.56 mm/yr. As well, in some areas of relatively flat seafloor, the focused fluid flow rates still exceeded 0.5 mm/yr. On the seismic lines the regions of focused fluid flow were commonly associated with seismic blanking zones above the BSR and sometimes with strong reflectors below the BSR, indicating that the faults/fractures provide high-permeability pathways for fluids to carry methane from BSR depths to the seafloor. These high fluid flow regions cover mostly the western portion of our area with gas hydrate concentration estimations of ~6% based on empirical correlations from Hydrate Ridge in south off Oregon, significantly higher than previously recognized values of ~2.5% in the eastern portion determined from Site U1327.

Li, Hong-lin; He, Tao; Spence, George D.

2014-01-01

59

Investigation of broadband electromagnetic induction scattering by highly conductive, permeable, arbitrarily shaped 3-D objects  

Microsoft Academic Search

Operating as low as tens of hertz and as high as hundreds of kilohertz, new broadband electromagnetic induction (EMI) sensors have shown promise for classification of unseen buried metallic objects. The three-dimensional (3-D) and bodies-of-revolution (BOR) numerical studies reported here are designed to explain key scattering sensitivities that may either be useful in or may limit object classification capability. The

F. Shubitidze; K. O'Neill; Keli Sun; K. D. Paulsen

2004-01-01

60

A meshless local boundary integral equation method for heat conduction analysis in nonhomogeneous solids  

Microsoft Academic Search

A local boundary integral equation method (LBIEM) with meshless approximation for heat conduction analysis in non?homogeneous solids is presented. A review of recent developments in advanced meshless LBIEM for 2?d, 3?d axisymmetric problems and microwave heating analysis is given. Both stationary and transient heat conduction problems are investigated in the paper. For transient problems both the Laplace transform technique and

Jan Sladek; Vladimir Sladek; Chuanzeng Zhang

2004-01-01

61

Heat Conduction of Air in Nano Spacing  

Microsoft Academic Search

The scale effect of heat conduction of air in nano spacing (NS) is very important for nanodevices to improve their life and\\u000a efficiency. By constructing a special technique, the changes of heat conduction of air were studied by means of measuring\\u000a the heat conduction with heat conduction instrument in NS between the hot plate and the cooling plate. Carbon nanotubes

Yao-Zhong Zhang; Bo Zhao; Gai-Yan Huang; Zhi Yang; Ya-Fei Zhang

2009-01-01

62

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

63

Microscale heat conduction in dielectric thin films  

Microsoft Academic Search

Starting from fundamental principles, it is shown that heat conduction by phonons can be analyzed in radiative transfer. A general theory of heat conduction is developed, showing that the Fourier law is a limiting case for steady-state macroscale heat transport. Two cases of heat transport across and along a thin film are considered. For the transient case, the theory shows

A. Majumdar

1993-01-01

64

Can we estimate wave heating with fully kinetic 3-D simulations of the Farley-Buneman Instability?  

NASA Astrophysics Data System (ADS)

The Farley-Buneman (FB) instability is a collisional two-stream plasma instability observed in the electrojet of the E region ionosphere. This instability develops when the polarization electric field across this region causes electrons to E? × B? drift substantially faster than the sound speed. This instability causes much of the common E-region radar reflections, allowing probing of this region. In the auroral electrojet, it also modifies electrojet conductivity by heating and transporting electrons across the geomagnetic field [Foster, Geophys. Res. Lett, 2000 and Oppenheim, Ann. Geophys., 1997]. In this paper, we will present the first fully 3-D kinetic simulations of a saturated FB and use them to explore the physics of electron heating and transport. In the last the last decade numerical simulations have become an important tool in exploring the nonlinear behavior of this instability. However, these simulations have been limited to 2-D and generally have represented electron dynamics with a fluid model while resolving ions kinetically with a particle-in-cell method (PIC) [see Oppenheim, et. al., Geophys. Res. Lett., 1996] or they have failed to reach saturation [Janhunen, J. Geophys. Res., 1994]. Taking advantage of a new generation of massively parallel, supercomputers, we can represent electron dynamics using a fully kinetic PIC algorithm. This allows us to simulate electron temperature variations as well as kinetic effects instead of making a simplifying set of assumptions about electron evolution. We will compare the simulated evolution of the 3-D FB instability with those calculated by 2-D kinetic and hybrid simulations. Further, we will evaluate electron heating effects and the implications for the ionosphere.

Oppenheim, M. M.; Dimant, Y.; Dyrud, L. P.

2006-05-01

65

3D multifields FEM computation of transverse flux induction heating for moving-strips  

Microsoft Academic Search

The numerical and experimental studies on induction heating of continuously moving strips in a transverse field are presented in this paper. The induced eddy current and its coupled thermal field in moving media is computed with FEM. The adopted mathematical model consists of a Fourier thermal conduction equation and a set of differential equations, which describes the steady-state eddy current

Z. Wang; W. Huang; W. Jia; Q. Zhao; Y. Wang; W. Yan; D. Schulze; G. Martin; U. Luedtke

1999-01-01

66

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

67

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

68

Polymer interconnections for 3D-chip stacking technology: directional volume patterning of flexible substrates with conducting polymer wires  

NASA Astrophysics Data System (ADS)

Research in 3D interconnection technology involves the functional modeling of complex biological processing structures with high-density 3D connections (such as the visual cortex). We propose a simple multi-chip stack structure, with through-chip connections and conducting polymer wires between layers. Self-assembled polymer wires based on polypyrrole have been produced by a directional electropolymerization process which permits the directional volume patterning of flexible substrates such as polycarbonate filtration membranes and gel layers. We have designed and fabricated successfully a two-chip stack with a perfect vertical electrical transfer between layers without any appearance of cross-talk. The measured values of conductivity for the polymer-based wires were as high as 0.5 S cm-1. Furthermore we could demonstrate the feasibility of a three-chip stack by using two intermediate polymer-based patterned layers and a special middle chip with through-chip metal connections.

Videlot, C.; Ackermann, J.; Fages, F.; Nguyen, T. N.; Wang, L.; Sarro, P. M.; Crawley, D.; Nikolic, K.; Forshaw, M.

2004-12-01

69

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

Microsoft Academic Search

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

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

2000-01-01

70

Prediction of thermal conductivity of air voided-fiber-reinforced composite laminates part II: 3D simulation  

NASA Astrophysics Data System (ADS)

Applying the fundamental definition of thermal conductivity to a unit cell of unidirectional fiber reinforced composite with air voids, one can deduce simple empirical formula to predict the thermal conductivity of the composite material with estimated air void volume percent. The inherent 3-D problem is modeled using finite element analysis. The model is tested at different fiber to resin volume ratios and various fibers to resin thermal conductivity ratios for three different air void volume percent. The air voids are modeled as cylindrical shapes with different lengths aligned with fiber direction. Two prediction schemes have been developed through the present work. One is to predict the longitudinal thermal conductivity and the other is to predict the transverse thermal conductivity of the fibers. Also, the model can be used to estimate the voids volume percent if the fiber thermal conductivity has been provided. Such expression can, also, serve as useful guides for quality and perfect bonding for material development.

Al-Nassar, Yagoub N.

2006-12-01

71

Atypical stoichiometry for a 3D bimetallic oxalate-based long-range ordered magnet exhibiting high proton conductivity.  

PubMed

The reproducible formation of a 3D oxalate based coordination compound of formula (NH4)5[Mn(II)2Cr(III)3(ox)9]·10H2O, with an unusual Mn(II)/Cr(III) ratio, is presented. The original topology of the anionic network leads to antiferromagnetic long-range ordering whereas its guests favour high humidity-dependent proton conductivity. PMID:24728206

Maxim, Catalin; Ferlay, Sylvie; Tokoro, Hiroko; Ohkoshi, Shin-Ichi; Train, Cyrille

2014-04-29

72

A 3D TCAD simulation of a thermoelectric module configured for thermoelectric power generation, cooling and heating  

NASA Astrophysics Data System (ADS)

This paper documents the 3D modeling and simulation of a three couple thermoelectric module using the Synopsys Technology Computer Aided Design (TCAD) semiconductor simulation software. Simulation results are presented for thermoelectric power generation, cooling and heating, and successfully demonstrate the basic thermoelectric principles. The 3D TCAD simulation model of a three couple thermoelectric module can be used in the future to evaluate different thermoelectric materials, device structures, and improve the efficiency and performance of thermoelectric modules.

Gould, C. A.; Shammas, N. Y. A.; Grainger, S.; Taylor, I.; Simpson, K.

2012-06-01

73

The optical conductivity of quasicrystals: evidence of a Weyl semimetal with 3D Dirac spectrum  

NASA Astrophysics Data System (ADS)

The optical conductivity of quasicrystals is characterized by an absence of the Drude peak and a conductivity that rises linearly over a wide range of frequencies. The absence of the Drude peak has been attributed to a pseudogap at the Fermi surface but a detailed explanation of the linear behavior has not been found. This unusual behavior is seen in all icosahedral quasicrystal families and their periodic approximants. A simple model that assumes that the entire Fermi surface is gapped, with the exception at a finite set of Dirac points, fits the data. There is no evidence of a semiconducting gap in any of the materials suggesting that the massless Dirac spectrum is protected by topology leading to a Weyl semimetal. The model gives rise to a linear conductivity with only one parameter, the Fermi velocity. In accord with this picture decagonal quasicrystals should have a frequency independent conductivity, without a Drude peak. This is in accord with the experimental data as well.

Timusk, Thomas; Carbotte, Jules; Homes, Christopher; Basov, Dimitri; Sharapov, Sergei

2013-03-01

74

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

75

Inversion of multi-frequency electromagnetic induction data for 3D characterization of hydraulic conductivity  

USGS Publications Warehouse

Electromagnetic induction (EMI) instruments provide rapid, noninvasive, and spatially dense data for characterization of soil and groundwater properties. Data from multi-frequency EMI tools can be inverted to provide quantitative electrical conductivity estimates as a function of depth. In this study, multi-frequency EMI data collected across an abandoned uranium mill site near Naturita, Colorado, USA, are inverted to produce vertical distribution of electrical conductivity (EC) across the site. The relation between measured apparent electrical conductivity (ECa) and hydraulic conductivity (K) is weak (correlation coefficient of 0.20), whereas the correlation between the depth dependent EC obtained from the inversions, and K is sufficiently strong to be used for hydrologic estimation (correlation coefficient of -0.62). Depth-specific EC values were correlated with co-located K measurements to develop a site-specific ln(EC)-ln(K) relation. This petrophysical relation was applied to produce a spatially detailed map of K across the study area. A synthetic example based on ECa values at the site was used to assess model resolution and correlation loss given variations in depth and/or measurement error. Results from synthetic modeling indicate that optimum correlation with K occurs at ~0.5m followed by a gradual correlation loss of 90% at 2.3m. These results are consistent with an analysis of depth of investigation (DOI) given the range of frequencies, transmitter-receiver separation, and measurement errors for the field data. DOIs were estimated at 2.0??0.5m depending on the soil conductivities. A 4-layer model, with varying thicknesses, was used to invert the ECa to maximize available information within the aquifer region for improved correlations with K. Results show improved correlation between K and the corresponding inverted EC at similar depths, underscoring the importance of inversion in using multi-frequency EMI data for hydrologic estimation. ?? 2011.

Brosten, T. R.; Day-Lewis, F. D.; Schultz, G. M.; Curtis, G. P.; Lane, J. W.

2011-01-01

76

Inversion of multi-frequency electromagnetic induction data for 3D characterization of hydraulic conductivity  

NASA Astrophysics Data System (ADS)

Electromagnetic induction (EMI) instruments provide rapid, noninvasive, and spatially dense data for characterization of soil and groundwater properties. Data from multi-frequency EMI tools can be inverted to provide quantitative electrical conductivity estimates as a function of depth. In this study, multi-frequency EMI data collected across an abandoned uranium mill site near Naturita, Colorado, USA, are inverted to produce vertical distribution of electrical conductivity ( EC) across the site. The relation between measured apparent electrical conductivity ( ECa) and hydraulic conductivity ( K) is weak (correlation coefficient of 0.20), whereas the correlation between the depth dependent EC obtained from the inversions, and K is sufficiently strong to be used for hydrologic estimation (correlation coefficient of - 0.62). Depth-specific EC values were correlated with co-located K measurements to develop a site-specific ln( EC)-ln( K) relation. This petrophysical relation was applied to produce a spatially detailed map of K across the study area. A synthetic example based on ECa values at the site was used to assess model resolution and correlation loss given variations in depth and/or measurement error. Results from synthetic modeling indicate that optimum correlation with K occurs at ~ 0.5 m followed by a gradual correlation loss of 90% at 2.3 m. These results are consistent with an analysis of depth of investigation (DOI) given the range of frequencies, transmitter-receiver separation, and measurement errors for the field data. DOIs were estimated at 2.0 ± 0.5 m depending on the soil conductivities. A 4-layer model, with varying thicknesses, was used to invert the ECa to maximize available information within the aquifer region for improved correlations with K. Results show improved correlation between K and the corresponding inverted EC at similar depths, underscoring the importance of inversion in using multi-frequency EMI data for hydrologic estimation.

Brosten, Troy R.; Day-Lewis, Frederick D.; Schultz, Gregory M.; Curtis, Gary P.; Lane, John W., Jr.

2011-04-01

77

Heat Conduction in Three Dimensions.  

National Technical Information Service (NTIS)

An applications-oriented numerical solution to the heat diffusion equation in three dimensions, with local temperature dependence in the thermal parameters and including phase changes, has been developed. Comparisons with exact one-dimensional solutions a...

S. T. Hanley

1976-01-01

78

A fast technique applied to the analysis of Resistive Wall Modes with 3D conducting structures  

SciTech Connect

This paper illustrates the development of a 'fast' technique for the analysis of Resistive Wall Modes (RWMs) in fusion devices with three-dimensional conducting structures, by means of the recently developed CarMa code. Thanks to its peculiar features, the computational cost scales almost linearly with the number of discrete unknowns. Some large scale problems are solved in configurations of interest for the International Thermonuclear Experimental Reactor (ITER)

Rubinacci, Guglielmo [Ass. EURATOM/ENEA/CREATE, DIEL, Universita degli Studi di Napoli, Federico II (Italy); Ventre, Salvatore [Ass. EURATOM/ENEA/CREATE, DAEIMI, Universita degli Studi di Cassino, Via Di Biasio 43, 03043 Cassino (Italy); Villone, Fabio [Ass. EURATOM/ENEA/CREATE, DAEIMI, Universita degli Studi di Cassino, Via Di Biasio 43, 03043 Cassino (Italy)], E-mail: villone@unicas.it; Liu, Yueqiang [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

2009-03-20

79

Electromagnetic Scattering From a Rectangular Cavity Recessed in a 3-D Conducting Surface  

NASA Technical Reports Server (NTRS)

The problem of electromagnetic (EM) scattering from an aperture backed by a rectangular cavity recessed in a three-dimensional conducting body is analyzed using the coupled field integral equation approach. Using the free-space Green's function, EM fields scattered outside the cavity are determined in terms of (1) an equivalent electric surface current density flowing on the three-dimensional conducting surface of the object including the cavity aperture and (2) an equivalent magnetic surface current density flowing over the aperture only. The EM fields inside the cavity are determined using the waveguide modal expansion functions. Making the total tangential electric and magnetic fields across the aperture continuous and subjecting the total tangential electric field on the outer conducting three-dimensional surface of the object to zero, a set of coupled integral equations is obtained. The equivalent electric and magnetic surface currents are then obtained by solving the coupled integral equation using the Method of Moments. The numerical results on scattering from rectangular cavities embedded in various three-dimensional objects are compared with the results obtained by other numerical techniques.

Deshpande, M. D.; Reddy, C. J.

1995-01-01

80

Development of Scientific Simulation 3D Full Wave ICRF Code for Stellarators and Heating/CD Scenarios Development  

SciTech Connect

In this report we describe theory and 3D full wave code description for the wave excitation, propagation and absorption in 3-dimensional (3D) stellarator equilibrium high beta plasma in ion cyclotron frequency range (ICRF). This theory forms a basis for a 3D code creation, urgently needed for the ICRF heating scenarios development for the operated LHD, constructed W7-X, NCSX and projected CSX3 stellarators, as well for re evaluation of ICRF scenarios in operated tokamaks and in the ITER . The theory solves the 3D Maxwell-Vlasov antenna-plasma-conducting shell boundary value problem in the non-orthogonal flux coordinates ({Psi}, {theta}, {var_phi}), {Psi} being magnetic flux function, {theta} and {var_phi} being the poloidal and toroidal angles, respectively. All basic physics, like wave refraction, reflection and diffraction are self consistently included, along with the fundamental ion and ion minority cyclotron resonances, two ion hybrid resonance, electron Landau and TTMP absorption. Antenna reactive impedance and loading resistance are also calculated and urgently needed for an antenna -generator matching. This is accomplished in a real confining magnetic field being varying in a plasma major radius direction, in toroidal and poloidal directions, through making use of the hot dense plasma wave induced currents with account to the finite Larmor radius effects. We expand the solution in Fourier series over the toroidal ({var_phi}) and poloidal ({theta}) angles and solve resulting ordinary differential equations in a radial like {Psi}-coordinate by finite difference method. The constructed discretization scheme is divergent-free one, thus retaining the basic properties of original equations. The Fourier expansion over the angle coordinates has given to us the possibility to correctly construct the ''parallel'' wave number k{sub //}, and thereby to correctly describe the ICRF waves absorption by a hot plasma. The toroidal harmonics are tightly coupled with each other due to magnetic field inhomogeneity of stellarators in toroidal direction. This is drastically different from axial symmetric plasma of the tokamaks. The inclusion in the problem major radius variation of magnetic field can strongly modify earlier results obtained for the straight helical, especially for high beta plasma, due to location modification of the two ion hybrid resonance layers. For the NCSX, LHD, W7-AS and W7-X like magnetic field topology inclusion in our theory of a major radius inhomogeneity of the magnetic field is a key element for correct description of RF power deposition profiles at all. The theory is developed in a manner that includes tokamaks and magnetic mirrors as the particular cases through general metric tensor (provided by an equilibrium solver) treatment of the wave equations. We describe that newly developed stellarator ICRF 3D full wave code PSTELION, based on theory described in this report. Applications to tokamaks, ITER, stellarators and benchmarking with 2D TORIC and 3D AORSA codes are given in included subreports

Vdovin V.L.

2005-08-15

81

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

82

Diagnostic of structures in heat and power generating industries with utilization of 3D digital image correlation  

NASA Astrophysics Data System (ADS)

In the paper we present implementation of 3D DIC method for in-situ diagnostic measurements of expansion bellows in heating chambers. The simultaneous measurements of a supply and a return pipeline were carried out in a heating chamber in Warsaw at the peak of the heating season in cooperation with Dalkia Warszawa. Results of the measurements enabled assessment of the risk of failure of expansion bellows. In-situ measurements were preceded by feasibility tests carried out in the Institute of Heat Engineering of Warsaw University of Technology. Potential implementations and a direction of future works are discussed in conclusions.

Malesa, M.; Kujawi?ska, M.; Malowany, K.; Siwek, B.

2013-04-01

83

Heat conduction fronts in planetary nebulae  

NASA Technical Reports Server (NTRS)

We present arguments which suggest that many of the x-ray, some optical, and some UV observations of planetary nebulae, can be explained by the presence of heat conduction fronts. The heat flows from the hot bubble formed by the shocked fast wind to the cool shell and halo. Heat conduction fronts are likely to account for emission of x rays from plasma at lower temperature than the expected temperature of the hot bubble. In the presence of magnetic fields, only a small fraction of the fast wind luminosity emerges as radiation. Heat conduction fronts can naturally produce some unusual line flux ratios, which are observed in some planetary nebulae. Heat conduction fronts may heat the halo and cause some material at the inner surface of the shell to expand slower than the rest of the shell. In the presence of an asymmetrical magnetic field, this flow, the x-ray intensity, and the emission lines, may acquire asymmetrical structure as well.

Soker, Noam

1994-01-01

84

The Relationship between Oxygen A-band Photon Pathlength Distributions and 3D Structures of Heating Rate Profiles  

NASA Astrophysics Data System (ADS)

Broadband heating directly drives the global atmospheric and oceanic circulation and its vertical profiles strongly depend upon cloud three-dimensional (3D) structures. Due to the complexity of cloud 3D problems and the difficulties in observations of broadband heating rate profiles (BBHRP), there are still large uncertainties in the relationship of clouds, radiation and climate feedback. Oxygen A-band photon pathlength distributions (PPLD) contain rich information about the 3D structures of clouds and BBHRP and can be observed by both ground based and space based measurements. Therefore, it is meaningful to explore the possibility of connecting A-band PPLD and BBHRP and consequently to describe the internal relationship between them together with the cloud 3D effects on BBHRP. A 3D Monte Carlo radiative transfer model is applied to simulate solar broadband heating rate profiles and oxygen A-band photon pathlength distributions of several ideal cloud fields and two typical cloud fields generated by cloud resolving model (CRM). Principal components (PCs) and the first four moments are selected to represent the vertical structures of BBHRP and PPLD, respectively. In ideal cloud fields, the moments show clear constraint to PCs of BBHRP. The results demonstrate the feasibility to describe the vertical structures of BBHRP by PPLD. The relationship between moments and PCs turns complicated in CRM cloud fields due to the composition of various 3D effects. However, detailed analysis still show that the moments, the PCs and total cloud optical depth are effective factors in defining BBHRP, especially for the vertical structures of relative low clouds. Further, a statistical fitting between the PCs and the moments by a two-layer neural network is applied to provide a quantitative representation of the linkages.

Song, L.; Min, Q.

2012-12-01

85

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

2013-03-01

86

3D stacked flip chip packaging with through silicon vias and copper plating or conductive adhesive filling  

Microsoft Academic Search

Three dimensional packaging is emerging as the solution for microelectronics development toward system on chip (SOC) and system in package (SIP). 3D flip chip structures with through silicon vias (TSVs) have very good potential for the implementation of 3D packaging. In this study, a prototype of 3D stacked flip chip packaging with TSVs is designed and fabricated. Fundamental techniques for

S. W. R. Lee; R. Hon; S. X. D. Zhang; C. K. Wong

2005-01-01

87

Asymmetric Heat Conduction in Nonlinear Systems  

NASA Astrophysics Data System (ADS)

Heat conduction is an old yet important problem. Since Fourier introduced the law bearing his name two hundred years ago, a first-principle derivation of this law from statistical mechanics is still lacking. Worse still, the validity of this law in low dimensions, and the necessary and sufficient conditions for its validity are still far from clear. In this talk I'll give a review of recent works done on this subject. I'll also report our latest work on asymmetric heat conduction in nonlinear systems. The study of heat condution is not only of theoretical interest but also of practical interest. The study of electric conduction has led to the invention of such important electric devices such as electric diodes and transistors. The study of heat conduction may also lead to the invention of thermal diodes and transistors in the future. Note from Publisher: This article contains the abstract only.

Hu, Bambi

2008-12-01

88

A correction scheme for thermal conductivity measurement using the comparative cut-bar technique based on 3D numerical simulation  

NASA Astrophysics Data System (ADS)

As an important factor affecting the accuracy of thermal conductivity measurement, systematic (bias) error in the guarded comparative axial heat flow (cut-bar) method was mostly neglected by previous researches. This bias is primarily due to the thermal conductivity mismatch between sample and meter bars (reference), which is common for a sample of unknown thermal conductivity. A correction scheme, based on finite element simulation of the measurement system, was proposed to reduce the magnitude of the overall measurement uncertainty. This scheme was experimentally validated by applying corrections on four types of sample measurements in which the specimen thermal conductivity is much smaller, slightly smaller, equal and much larger than that of the meter bar. As an alternative to the optimum guarding technique proposed before, the correction scheme can be used to minimize the uncertainty contribution from the measurement system with non-optimal guarding conditions. It is especially necessary for large thermal conductivity mismatches between sample and meter bars.

Xing, Changhu; Folsom, Charles; Jensen, Colby; Ban, Heng; Marshall, Douglas W.

2014-05-01

89

Heat Conductivity of Pure Oxide Ceramics.  

National Technical Information Service (NTIS)

The values of lamda (heat conductivity) for dense specimens of ceramics made from Al2O3, MgO, and BeO, measured by the methods of stationary and regular heat regimes, differ within the limits of experimental error. The lamda of specimens with similar dens...

I. G. Duderov D. N. Poluboyarinov

1969-01-01

90

Contact conductivity of cryogenic heat insulation materials  

Microsoft Academic Search

Results are presented of an experimental investigation by the method of the electrothermal analogy for the contact heat transfer in different kinds of cryogenic thermal insulation and empirical dependences are obtained that permit execution of a qualitative, and in a number of cases, even a quantitative estimate of the contribution of the contact conductivity to the total heat transport through

S. B. Mil'Man; M. G. Velikanova

1991-01-01

91

Coupled boundary element method and finite difference method for the heat conduction in laser processing  

Microsoft Academic Search

This paper is presented as a way to model transient heat conduction in a 3-D axisymmetric case where large rates of heat fluxes are applied on the surfaces as done in the case of laser processing. This would result in large temperature gradients in a small area irradiated by the laser on the incident surface that could also reach melting

Sirilath J. DeSilva; Cho Lik Chan

2008-01-01

92

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

93

Electrical-Thermal Co-Simulation of 3D Integrated Systems With Micro-Fluidic Cooling and Joule Heating Effects  

Microsoft Academic Search

In this paper, the electrical-thermal co-simulation of 3DsystemswithJouleheating,fluidiccoolingandairconvectionef- fectsisproposed.Thefinite-volumemethodformulationsofvoltage distribution equation, heat equations for both fluid flow and solid medium with nonuniform mesh are explained in detail. Based on the proposed iterativeco-simulation method,package temperature distributionandvoltagedropwithJouleheatingandfluidiccooling effects can be estimated. Several packaging examples are simu- lated and the results show that with micro-channel fluidic cooling in high power density 3D integrated

Jianyong Xie; Madhavan Swaminathan

2011-01-01

94

Initial version of an integrated thermal hydraulics and neutron kinetics 3D code X3D  

Microsoft Academic Search

A theoretical concept for the description of 3D nuclear kinetics, heat conduction and the thermal-hydraulic single and two-phase flow phenomena in a 3D light water reactor core simulated by parallel channels is presented. The heat generation within each fuel element is described by a 3D core kinetics code employing a two-group diffusion theory model. Finite differences are used to approximate

S. Jewer; A. Thompson; A. Hoeld; P. A. Beeley

2006-01-01

95

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

96

Liquid cooling performance for a 3-D multichip module and miniature heat sink  

Microsoft Academic Search

Measured thermal performance is presented for a single phase liquid-cooled module. Tape automated bonded (TAB) thermal test chips and their associated substrates are stacked in a compact, 3-D liquid-tight module. A dielectric liquid, polyalphaolefin (PAO), is forced to flow past the active and inactive sides of TAB chips. At a volumetric flowrate of 0.05 gallons per minute (gpm) and an

Marlin R. Vogel

1995-01-01

97

The 3D numerical simulation of waste heat inside the end-pumped DPAL  

NASA Astrophysics Data System (ADS)

The thermal effect produced by quantum defect is an important factor that affects the performance of DPAL. We report on 3D simulation results of temperature distribution inside the alkali gain medium. The results show a high and non-uniform temperature rise under CW pumped condition, and the current models that assume uniform alkali density distribution needs to be modified. A convective cooling scheme should be applied for high power DPALs.

Hua, Weihong; Yang, Zining; Wang, Hongyan

2012-01-01

98

Constructing a model of 3D radiogenic heat production in Ireland  

NASA Astrophysics Data System (ADS)

Heat production values in the crust and mantle rock inform heat flow density data to provide crucial information about the structure of the Earth's lithosphere. In addition, accurate models of horizontal and vertical distribution of heat production can help to define geothermal exploration targets. Low-enthalpy district scale space heating and Enhanced Geothermal Systems (EGS) using hot, dry rock may provide sustainable energy resources in regions currently perceived as having low geothermal energy potential. Ireland is located within stable lithosphere, unaffected by recent tectonism and volcanism, and has an estimated heat flow range below the measured global continental average. Nevertheless, borehole data indicate that heat production is variable across the island, with anomalously high rates observed, for example, in Cavan, Meath and Antrim. Data coverage is, however, poor. Radioactive isotopic decay generates heat in rock. By using established heat production constants and known concentrations of unstable isotopes of uranium, thorium and potassium, along with rock density values, a heat production rate in ?W m -3 is obtained. With the objective of compiling the first comprehensive database of information about the Irish lithosphere, in three dimensions, the authors present here initial results obtained from published and unpublished whole-rock major and trace element analyses. The presence of systematic trends correlating heat production to properties such as age and lithology are also investigated. Offering insight into the vertical component of heat production distribution, Irish xenoliths emplaced in Lower Carboniferous volcanics are regarded as a reliable proxy for the present-day lower crust. Their geochemical composition gives heat production values that are higher than expected for the depths indicated by their thermobarometric data, suggesting that heat production rates do not simply reduce with depth.

Willmot Noller, N. M.; Daly, J. S.

2012-04-01

99

Transient Heat Conduction Simulation around Microprocessor Die  

NASA Astrophysics Data System (ADS)

This paper explains about fundamental formula of calculating power consumption of CMOS (Complementary Metal-Oxide-Semiconductor) devices and its voltage and temperature dependency, then introduces equation for estimating power consumption of the microprocessor for notebook PC (Personal Computer). The equation is applied to heat conduction simulation with simplified thermal model and evaluates in sub-millisecond time step calculation. In addition, the microprocessor has two major heat conduction paths; one is from the top of the silicon die via thermal solution and the other is from package substrate and pins via PGA (Pin Grid Array) socket. Even though the dominant factor of heat conduction is the former path, the latter path - from package substrate and pins - plays an important role in transient heat conduction behavior. Therefore, this paper tries to focus the path from package substrate and pins, and to investigate more accurate method of estimating heat conduction paths of the microprocessor. Also, cooling performance expression of heatsink fan is one of key points to assure result with practical accuracy, while finer expression requires more computation resources which results in longer computation time. Then, this paper discusses the expression to minimize computation workload with a practical accuracy of the result.

Nishi, Koji

100

Local effects of longitudinal heat conduction in plate heat exchangers  

Microsoft Academic Search

In a plate heat exchanger, heat transfer from the hot to the cold fluid is a multi-dimensional conjugate problem, in which longitudinal heat conduction (LHC) along the dividing walls often plays some role and can not be neglected. Large-scale, or end-to-end, LHC is always detrimental to the exchanger’s effectiveness. On the contrary, if significant non-uniformities exist in the distribution of

Michele Ciofalo

2007-01-01

101

A transient 3-D inverse problem in imaging the time-dependent local heat transfer coefficients for plate fin  

Microsoft Academic Search

The local time-dependent surface heat transfer coefficients for plate finned-tube heat exchangers are estimated in a three-dimensional inverse heat conduction problem. The inverse algorithm utilizing the steepest descent method (SDM) and a general purpose commercial code CFX4.4 is applied successfully in this study in accordance with the simulated measured temperature distributions on fin surface by infrared thermography. Two different heat

Cheng-Hung Huang; Yao-Long Tsai

2005-01-01

102

Asymmetric heat conduction in nonlinear lattices.  

PubMed

In this Letter, we conduct an extensive study of the two-segment Frenkel-Kontorova model. We show that the rectification effect of the heat flux reported in recent literature is possible only in the weak interfacial coupling limit. The rectification effect will be reversed when the properties of the interface and the system size change. These two types of asymmetric heat conduction are governed by different mechanisms though both are induced by nonlinearity. An intuitive physical picture is proposed to interpret the reversal of the rectification effect. Since asymmetric heat conduction depends critically on the properties of the interface and the system size, it is probably not an easy task to fabricate a thermal rectifier or thermal diode in practice. PMID:17025972

Hu, Bambi; Yang, Lei; Zhang, Yong

2006-09-22

103

Compact pulsed laser having improved heat conductance  

NASA Technical Reports Server (NTRS)

A highly efficient, compact pulsed laser having high energy to weight and volume ratios is provided. The laser utilizes a cavity reflector that operates as a heat sink and is essentially characterized by having a high heat conductivity, by being a good electrical insulator and by being substantially immune to the deleterious effects of ultra-violet radiation. Manual portability is accomplished by eliminating entirely any need for a conventional circulating fluid cooling system.

Yang, L. C. (inventor)

1977-01-01

104

Measurement of heat conduction through stacked screens  

NASA Technical Reports Server (NTRS)

This paper describes the experimental apparatus for the measurement of heat conduction through stacked screens as well as some experimental results taken with the apparatus. Screens are stacked in a fiberglass-epoxy cylinder, which is 24.4 mm in diameter and 55 mm in length. The cold end of the stacked screens is cooled by a Gifford-McMahon (GM) cryocooler at cryogenic temperature, and the hot end is maintained at room temperature. Heat conduction through the screens is determined from the temperature gradient in a calibrated heat flow sensor mounted between the cold end of the stacked screens and the GM cryocooler. The samples used for these experiments consisted of 400-mesh stainless steel screens, 400-mesh phosphor bronze screens, and two different porosities of 325-mesh stainless steel screens. The wire diameter of the 400-mesh stainless steel and phosphor bronze screens was 25.4 micrometers and the 325-mesh stainless steel screen wire diameters were 22.9 micrometers and 27.9 micrometers. Standard porosity values were used for the experimental data with additional porosity values used on selected experiments. The experimental results showed that the helium gas between each screen enhanced the heat conduction through the stacked screens by several orders of magnitude compared to that in vacuum. The conduction degradation factor is the ratio of actual heat conduction to the heat conduction where the regenerator material is assumed to be a solid rod of the same cross sectional area as the metal fraction of the screen. This factor was about 0.1 for the stainless steel and 0.022 for the phosphor bronze, and almost constant for the temperature range of 40 to 80 K at the cold end.

Lewis, M. A.; Kuriyama, T.; Kuriyama, F.; Radebaugh, R.

1998-01-01

105

Measurement of heat conduction through stacked screens.  

PubMed

This paper describes the experimental apparatus for the measurement of heat conduction through stacked screens as well as some experimental results taken with the apparatus. Screens are stacked in a fiberglass-epoxy cylinder, which is 24.4 mm in diameter and 55 mm in length. The cold end of the stacked screens is cooled by a Gifford-McMahon (GM) cryocooler at cryogenic temperature, and the hot end is maintained at room temperature. Heat conduction through the screens is determined from the temperature gradient in a calibrated heat flow sensor mounted between the cold end of the stacked screens and the GM cryocooler. The samples used for these experiments consisted of 400-mesh stainless steel screens, 400-mesh phosphor bronze screens, and two different porosities of 325-mesh stainless steel screens. The wire diameter of the 400-mesh stainless steel and phosphor bronze screens was 25.4 micrometers and the 325-mesh stainless steel screen wire diameters were 22.9 micrometers and 27.9 micrometers. Standard porosity values were used for the experimental data with additional porosity values used on selected experiments. The experimental results showed that the helium gas between each screen enhanced the heat conduction through the stacked screens by several orders of magnitude compared to that in vacuum. The conduction degradation factor is the ratio of actual heat conduction to the heat conduction where the regenerator material is assumed to be a solid rod of the same cross sectional area as the metal fraction of the screen. This factor was about 0.1 for the stainless steel and 0.022 for the phosphor bronze, and almost constant for the temperature range of 40 to 80 K at the cold end. PMID:11543366

Lewis, M A; Kuriyama, T; Kuriyama, F; Radebaugh, R

1998-01-01

106

Heat transfer in 3-D serpentine channels with right-angle turns  

SciTech Connect

Laminar flow and heat transfer in square serpentine channels with right-angle turns, which have applications in heat exchangers, were numerically studied. A finite volume code in FORTRAN was developed to solve this problem. For solving the flow field, a colocated-grid formulation was used, as opposed to the staggered-grid formulation, and the SIMPLE algorithm was used to link the velocity and pressure. The line-by-line method was used to solve the algebraic equations. The temperature field was solved for the uniform-wall-heat-flux boundary condition. The developed numerical code was validated by solving for fully developed flow and heat transfer in a square straight channel. The grid-independent solution was established for a reference case of serpentine channel with the highest Reynolds number. Periodically fully developed flow and heat transfer fields in serpentine channels were solved for different geometry parameters, for different Reynolds numbers, and for two different Prandtl numbers (for air and water, respectively). The enhancement of the heat transfer mechanism was explained by studying the plotted flow-field velocity vectors in different planes. The heat transfer performance of serpentine channels is better than that for straight channels for Pr = 7.0 and is worse than that for straight channels for Pr = 0.7.

Chintada, S.; Ko, K.H.; Anand, N.K.

1999-12-01

107

Determination of the heat transfer coefficients in transient heat conduction  

NASA Astrophysics Data System (ADS)

The determination of the space- or time-dependent heat transfer coefficient which links the boundary temperature to the heat flux through a third-kind Robin boundary condition in transient heat conduction is investigated. The reconstruction uses average surface temperature measurements. In both cases of the space- or time-dependent unknown heat transfer coefficient the inverse problems are nonlinear and ill posed. Least-squares penalized variational formulations are proposed and new formulae for the gradients are derived. Numerical results obtained using the nonlinear conjugate gradient method combined with a boundary element direct solver are presented and discussed.

Nho Hào, Dinh; Thanh, Phan Xuan; Lesnic, D.

2013-09-01

108

3-D Slug Flow Heat Transfer Analysis of Coupled Coolant Cells in Finite LMFBR Bundles.  

National Technical Information Service (NTIS)

A three-dimensional single region slug flow heat transfer analysis for finite LMFBR rod bundles using a classical analytical solution method has been performed. According to the isolated single cell analysis, the results show that the peripheral clad temp...

C. N. Wong L. Wolf

1978-01-01

109

Development of a 3-D urbanization index using digital terrain models for surface urban heat island effects  

NASA Astrophysics Data System (ADS)

This study assesses surface urban heat island (SUHI) effects during heat waves in subtropical areas. Two cities in northern Taiwan, Taipei metropolis and its adjacent medium-sized city, Yilan, were selected for this empirical study. Daytime and night time surface temperature and SUHI intensity of both cities in five heat wave cases were obtained from MODIS Land-Surface Temperature (LST) and compared. In order to assess SUHI in finer spatial scale, an innovated three-dimensional Urbanization Index (3DUI) with a 5-m spatial resolution was developed to quantify urbanization from a 3-D perspective using Digital Terrain Models (DTMs). The correlation between 3DUI and surface temperatures were also assessed. The results obtained showed that the highest SUHI intensity in daytime was 10.2 °C in Taipei and 7.5 °C in Yilan. The SUHI intensity was also higher than that in non-heat-wave days (about 5 °C) in Taipei. The difference in SUHI intensity of both cities could be as small as only 1.0 °C, suggesting that SUHI intensity was enhanced in both large and medium-sized cities during heat waves. Moreover, the surface temperatures of rural areas in Taipei and Yilan were elevated in the intense heat wave cases, suggesting that the SUHI may reach a plateau when the heat waves get stronger and last longer. In addition, the correlation coefficient between 3DUI and surface temperature was greater than 0.6. The innovative 3DUI can be employed to assess the spatial variation of temperatures and SUHI intensity in much finer spatial resolutions than measurements obtained from remote sensing and weather stations. In summary, the empirical results demonstrated intensified SUHI in large and medium-sized cities in subtropical areas during heat waves which could result in heat stress risks of residents. The innovative 3DUI can be employed to identify vulnerable areas in fine spatial resolutions for formulation of heat wave adaptation strategies.

Wu, Chih-Da; Lung, Shih-Chun Candice; Jan, Jihn-Fa

2013-07-01

110

Signatures of small-scale heating events in EUV spectral lines as modeled from 3D MHD simulations  

NASA Astrophysics Data System (ADS)

We aim at understanding the implications of small scale heating events in the solar atmosphere for the variations of the solar spectral irradiance. We present a technique for identification and characterization of these events in 3D simulations of the solar atmosphere. An accurate property determination of these events in time and space will help us to understand how spectral lines, in particular in the EUV, respond to them and which kind of spectral signatures one would expect to find in observations as from SOHO/SUMER and eventually from future space missions, as for example observations by SPICE on board Solar Orbiter.

Guerreiro, Nuno; Haberreiter, Margit; Hansteen, Viggo; Curdt, Werner; Schmutz, Werner

2014-05-01

111

Effects of anisotropic heat conduction on solidification  

NASA Technical Reports Server (NTRS)

Two-dimensional solidification influenced by anisotropic heat conduction has been considered. The interfacial energy balance was derived to account for the heat transfer in one direction (x or y) depending on the temperature gradient in both the x and y directions. A parametric study was made to determine the effects of the Stefan number, aspect ratio, initial superheat, and thermal conductivity ratios on the solidification rate. Because of the imposed boundary conditions, the interface became skewed and sometimes was not a straight line between the interface position at the upper and lower adiabatic walls (spatially nonlinear along the height). This skewness depends on the thermal conductivity ratio k(yy)/k(yx). The nonlinearity of the interface is influenced by the solidification rate, aspect ratio, and k(yy/k(yx).

Weaver, J. A.; Viskanta, R.

1989-01-01

112

3D CFD ELECTROCHEMICAL AND HEAT TRANSFER MODEL OF AN INTERNALLY MANIFOLDED SOLID OXIDE ELECTROLYSIS CELL  

Microsoft Academic Search

A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in an internally manifolded planar solid oxide electrolysis cell (SOEC) stack. This design is being evaluated at the Idaho National Laboratory for hydrogen production from nuclear power and process heat. Mass, momentum, energy, and species conservation and transport are provided

Grant L. Hawkes; James E. OBrien; Greg Tao

2011-01-01

113

A 3-D INVERSE PROBLEM IN ESTIMATING THE TIME-DEPENDENT HEAT TRANSFER COEFFICIENTS FOR PLATE FINS  

Microsoft Academic Search

The local time-dependent surface heat transfer coefficients for plate finned-tube heat exchangers are estimated in a three-dimensional inverse heat conduction problem. The inverse algorithm utilizing the Steepest Descent Method (SDM) and a general purpose commercial code CFX4.4 is applied successfully in this study in accordance with the simulated measured temperature distributions on the fin surface by infrared thermography. Two different

C.-H. Huang; Y.-L. Tsai; H.-M. Chen

114

Heat Rejection from a Variable Conductance Heat Pipe Radiator Panel  

NASA Technical Reports Server (NTRS)

A titanium-water heat pipe radiator having an innovative proprietary evaporator configuration was evaluated in a large vacuum chamber equipped with liquid nitrogen cooled cold walls. The radiator was manufactured by Advanced Cooling Technologies, Inc. (ACT), Lancaster, PA, and delivered as part of a Small Business Innovative Research effort. The radiator panel consisted of five titanium-water heat pipes operating as thermosyphons, sandwiched between two polymer matrix composite face sheets. The five variable conductance heat pipes were purposely charged with a small amount of non-condensable gas to control heat flow through the condenser. Heat rejection was evaluated over a wide range of inlet water temperature and flow conditions, and heat rejection was calculated in real-time utilizing a data acquisition system programmed with the Stefan-Boltzmann equation. Thermography through an infra-red transparent window identified heat flow across the panel. Under nominal operation, a maximum heat rejection value of over 2200 Watts was identified. The thermal vacuum evaluation of heat rejection provided critical information on understanding the radiator s performance, and in steady state and transient scenarios provided useful information for validating current thermal models in support of the Fission Power Systems Project.

Jaworske, D. A.; Gibson, M. A.; Hervol, D. S.

2012-01-01

115

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

116

Time-Resolved Measurement of Radiatively Heated Iron 2p-3d Transmission Spectra  

Microsoft Academic Search

An experimental measurement of radiatively heated iron plasma transmission spectra was performed on Shenguang II laser facility. In the measurement, the self-emission spectrum, the backlighting spectrum, and the absorption spectrum were imaged with a flat filed grating and recorded on a gated micro channel plate detector to obtain the time-resolved transmission spectra in the range 10-20 Å (approximately 0.6-1.3keV). Experimental

Yang Zhao; Wan-Li Shang; Gang Xiong; Feng-Tao Jin; Zhi-Min Hu; Min-Xi Wei; Guo-Hong Yang; Ji-Yan Zhang; Jia-Min Yang

2010-01-01

117

ALE3D Simulation of Heating and Violence in a Fast Cookoff Experiment with LX10  

Microsoft Academic Search

We performed a computational and experimental analysis of fast cookoff of LX-10 (94.7% HMX, 5.3% Viton A) confined in a 2 kbar steel tube with reinforced end caps. A Scaled-Thermal-Explosion-eXperiment (STEX) was completed in which three radiant heaters were used to heat the vessel until ignition, resulting in a moderately violent explosion after 20.4 minutes. Thermocouple measurements showed tube temperatures

M A McClelland; J L Maienschein; W M Howard; A L Nichols; M R deHaven; O T Strand

2006-01-01

118

3-D simulation of macroscopic erosion of CFC under ITER off-normal heat loads  

Microsoft Academic Search

Carbon fiber composites, CFC, newly developed for the divertor armor of the future tokamak ITER, have a rather complex structure of fiber framework and carbon matrix, allowing CFC to match the thermal conductivity requirements for the tokamak stationary regimes. But for the ITER off-normal events, their behavior is still not investigated in detail. Recent experiments on electron beam facilities simulating

S. Pestchanyi; H. Wuerz

2003-01-01

119

3D CFD ELECTROCHEMICAL AND HEAT TRANSFER MODEL OF AN INTERNALLY MANIFOLDED SOLID OXIDE ELECTROLYSIS CELL  

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 an internally manifolded planar solid oxide electrolysis cell (SOEC) stack. This design is being evaluated at the Idaho National Laboratory for hydrogen production from nuclear power and process heat. 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, operating potential, steam-electrode gas composition, oxygen-electrode gas composition, current density and hydrogen production over a range of stack operating conditions. Single-cell and five-cell results will be presented. Flow distribution through both models is discussed. Flow enters from the bottom, distributes through the inlet plenum, flows across the cells, gathers in the outlet plenum and flows downward making an upside-down ''U'' shaped flow pattern. Flow and concentration variations exist downstream of the inlet holes. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Effects of variations in operating temperature, gas flow rate, oxygen-electrode and steam-electrode current density, and contact resistance from the base case are presented. Contour plots of local electrolyte temperature, current density, and Nernst potential indicate 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 L. Hawkes; James E. O'Brien; Greg Tao

2011-11-01

120

3D near-to-surface conductivity reconstruction by inversion of VETEM data using the distorted Born iterative method  

USGS Publications Warehouse

Three-dimensional (3D) subsurface imaging by using inversion of data obtained from the very early time electromagnetic system (VETEM) was discussed. The study was carried out by using the distorted Born iterative method to match the internal nonlinear property of the 3D inversion problem. The forward solver was based on the total-current formulation bi-conjugate gradient-fast Fourier transform (BCCG-FFT). It was found that the selection of regularization parameter follow a heuristic rule as used in the Levenberg-Marquardt algorithm so that the iteration is stable.

Wang, G. L.; Chew, W. C.; Cui, T. J.; Aydiner, A. A.; Wright, D. L.; Smith, D. V.

2004-01-01

121

LavaSIM: the effect of heat transfer in 3D on lava flow characteristics (Invited)  

NASA Astrophysics Data System (ADS)

Characteristics of lava flow are governed by many parameters like lava viscosity, effusion rate, ground topography, etc. The accuracy and applicability of lava flow simulation code is evaluated whether the numerical simulation can reproduce these features quantitatively, which is important from both strategic and scientific points of views. Many lava flow simulation codes are so far proposed, and they are classified into two categories, i.e., the deterministic and the probabilistic models. LavaSIM is one of the former category models, and has a disadvantage of time consuming. But LavaSIM can solves the equations of continuity, motion, energy by step and has an advantage in the calculation of three-dimensional analysis with solid-liquid two phase flow, including the heat transfer between lava, solidified crust, air, water and ground, and three-dimensional convection in liquid lava. In other word, we can check the detailed structure of lava flow by LavaSIM. Therefore, this code can produce both channeled and fan-dispersive flows. The margin of the flow is solidified by cooling and these solidified crusts control the behavior of successive lava flow. In case of a channel flow, the solidified margin supports the stable central main flow and elongates the lava flow distance. The cross section of lava flow shows that the liquid lava flows between solidified crusts. As for the lava extrusion flow rate, LavaSIM can include the time function as well as the location of the vents. In some cases, some parts of the solidified wall may be broken by the pressure of successive flow and/or re-melting. These mechanisms could characterize complex features of the observed lava flows at many volcanoes in the world. To apply LavaSIM to the benchmark tests organized by V-hub is important to improve the lava flow evaluation technique.

Fujita, E.

2013-12-01

122

3D THERMOGRAPHY FOR QUANTIFICATION OF HEAT GENERATION RESULTING FROM INFLAMMATION THERMOGRAPHIE 3D POUR LA QUANTIFICATION DE LA CHALEUR PRODUITE PAR UNE INFLAMMATION  

Microsoft Academic Search

We aim to develop a non-invasive imaging technology to allow early, accurate and quantitative detection of inflammation. Thermography has been used for decades by biologists and clinicians to isolate main sites of body heat loss and to assist with diagnosis of biomechanical problems. However, thermography is still viewed as an accessory to conventional clinical examination procedures because it only provides

Jean-Christophe Nebel

123

3D Numerical heat transfer and fluid flow analysis in plate-fin and tube heat exchangers with electrohydrodynamic enhancement  

NASA Astrophysics Data System (ADS)

Three-dimensional laminar fluid flow and heat transfer over a four-row plate-fin and tube heat exchanger with electrohydrodynamic (EHD) wire electrodes are studied numerically. The effects of different electrode arrangements (square and diagonal), tube pitch arrangements (in-line and staggered) and applied voltage (VE=0-16 kV) are investigated in detail for the Reynolds number range (based on the fin spacing and frontal velocity) ranging from 100 to 1,000. It is found that the EHD enhancement is more effective for lower Re and higher applied voltage. The case of staggered tube pitch with square wire electrode arrangement gives the best heat transfer augmentation. For VE=16 kV and Re = 100, this study identifies a maximum improvement of 218% in the average Nusselt number and a reduction in fin area of 56% as compared that without EHD enhancement.

Lin, Chia-Wen; Jang, Jiin-Yuh

2005-05-01

124

Parallelized solvers for heat conduction formulations  

NASA Technical Reports Server (NTRS)

Based on multilevel partitioning, this paper develops a structural parallelizable solution methodology that enables a significant reduction in computational effort and memory requirements for very large scale linear and nonlinear steady and transient thermal (heat conduction) models. Due to the generality of the formulation of the scheme, both finite element and finite difference simulations can be treated. Diverse model topologies can thus be handled, including both simply and multiply connected (branched/perforated) geometries. To verify the methodology, analytical and numerical benchmark trends are verified in both sequential and parallel computer environments.

Padovan, Joe; Kwang, Abel

1991-01-01

125

Calculations of Temperature, Conductive Heat Flux, and Heat Wave Velocities Due to Radiant Heating of Opaque Materials.  

National Technical Information Service (NTIS)

The analytic solutions of the one-dimensional Fourier conductive heat flux law and corresponding transient heat transfer equation have been used to calculate temperature, conductive heat flux, and their trajectories due to radiant heating of opaque materi...

A. Cohen

2011-01-01

126

Heat conduction in heterogeneous media and volumetric heating of oil shales by magnetic methods  

Microsoft Academic Search

The problem of volumetric heating of oil shales by electromagnetic methods is studied theoretically. This study includes both a detailed examination of heat conduction in composite media, and the development of a numerical model to describe the heating process. The effects of layering on heat conduction in oil shale materials is studied theoretically. A new solution to a heat conduction

Baker-Jarvis

1984-01-01

127

Induction heating of electrically conductive porous asphalt concrete  

Microsoft Academic Search

In this research, an electrically conductive porous asphalt concrete, used for induction heating, was prepared by adding electrically conductive filler (steel fibers and steel wool) to the mixture. The main purpose of this paper is to examine the electrical conductivity and the indirect tensile strength of this conductive porous asphalt concrete and prove that it can be heated via induction

Quantao Liu; Erik Schlangen; Álvaro García; Martin van de Ven

2010-01-01

128

Variable-Conductance Heat-Transfer Module  

NASA Technical Reports Server (NTRS)

Working lengths of heat pipes electronically controlled. Rate of heat transfer controlled by electrical heaters shorten effective working lengths of heat pipes. Concept not limited to right circular cylindrical shape. Concept adaptable to terrestrial instruments or processes in which atmospheres or fluids must be cooled and returned to instruments or processes at fixed lower temperatures.

Hewitt, D. R.

1984-01-01

129

The peridynamic formulation for transient heat conduction  

Microsoft Academic Search

In bodies where discontinuities, like cracks, emerge and interact, the classical equations for heat and mass transfer are not well suited. We propose a peridynamic model for transient heat (or mass) transfer which is valid when the body undergoes damage or evolving cracks. We use a constructive approach to find the peridynamic formulation for heat transfer and test the numerical

Florin Bobaru; Monchai Duangpanya

2010-01-01

130

Porous 3D graphene-based bulk materials with exceptional high surface area and excellent conductivity for supercapacitors.  

PubMed

Until now, few sp(2) carbon materials simultaneously exhibit superior performance for specific surface area (SSA) and electrical conductivity at bulk state. Thus, it is extremely important to make such materials at bulk scale with those two outstanding properties combined together. Here, we present a simple and green but very efficient approach using two standard and simple industry steps to make such three-dimensional graphene-based porous materials at the bulk scale, with ultrahigh SSA (3523 m(2)/g) and excellent bulk conductivity. We conclude that these materials consist of mainly defected/wrinkled single layer graphene sheets in the dimensional size of a few nanometers, with at least some covalent bond between each other. The outstanding properties of these materials are demonstrated by their superior supercapacitor performance in ionic liquid with specific capacitance and energy density of 231 F/g and 98 Wh/kg, respectively, so far the best reported capacitance performance for all bulk carbon materials. PMID:23474952

Zhang, Long; Zhang, Fan; Yang, Xi; Long, Guankui; Wu, Yingpeng; Zhang, Tengfei; Leng, Kai; Huang, Yi; Ma, Yanfeng; Yu, Ao; Chen, Yongsheng

2013-01-01

131

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

132

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

133

Some observations on the historical development of conduction heat transfer  

NASA Astrophysics Data System (ADS)

An attempt is made to obtain historical perspectives on the development of the mathematical theory of heat conduction considering Newton's law of cooling (1701) and its close connection with Fourier's work from 1807 to 1822 resulting in his epoch-making treatise on "The Analytical Theory of Heat". Fourier was the principal architect of the heat conduction theory. Fourier's work established a new methodology for the formulation and solution of physical problems, based on partial differential equations and marked a major turning point in the history of physics. The developments in the periods 1822 to 1900 and 1900 to 1950 are also briefly reviewed as are the classical (analytical) and numerical methods of solution for heat conduction problems. The analogy in heat, momentum, and mass transfer for transport phenomena is discussed. A list of recent conduction heat transfer books is presented to show the scope of recent developments. Some observations on conduction heat transfer are noted.

Cheng, Kwo Chang

134

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 superfluid neutron matter, called superfluid phonons, can influence heat conduction in magnetized neutron stars. They can dominate the heat conduction transverse to the magnetic field when the magnetic field B > or approx. 10{sup 13} G. At a density of {rho}{approx_equal}10{sup 12}-10{sup 14} g/cm{sup 3}, the conductivity due to superfluid phonons is significantly larger than that due to lattice phonons and is comparable to electron conductivity when the 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 could show observationally discernible differences.

Aguilera, Deborah N. [Tandar Laboratory, Comision Nacional de Energia Atomica, Avenida Gral. Paz 1499, 1650 San Martin, Buenos Aires (Argentina); Cirigliano, Vincenzo; Reddy, Sanjay; Sharma, Rishi [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Pons, Jose A. [Department of Applied Physics, University of Alicante, Apartado de Correos 99, E-03080 Alicante (Spain)

2009-03-06

135

Theory and design of variable conductance heat pipes  

NASA Technical Reports Server (NTRS)

A comprehensive review and analysis of all aspects of heat pipe technology pertinent to the design of self-controlled, variable conductance devices for spacecraft thermal control is presented. Subjects considered include hydrostatics, hydrodynamics, heat transfer into and out of the pipe, fluid selection, materials compatibility and variable conductance control techniques. The report includes a selected bibliography of pertinent literature, analytical formulations of various models and theories describing variable conductance heat pipe behavior, and the results of numerous experiments on the steady state and transient performance of gas controlled variable conductance heat pipes. Also included is a discussion of VCHP design techniques.

Marcus, B. D.

1972-01-01

136

Efficient Reformulation of HOTFGM: Heat Conduction With Variable Thermal Conductivity  

NASA Technical Reports Server (NTRS)

Functionally graded materials (FGMs) have become one of the major research topics in the mechanics of materials community during the past fifteen years. FGMs are heterogeneous materials, characterized by spatially variable microstructure, and thus spatially variable macroscopic properties, introduced to enhance material or structural performance. The spatially variable material properties make FGMs challenging to analyze. The review of the various techniques employed to analyze the thermodynamical response of FGMs reveals two distinct and fundamentally different computational strategies, called uncoupled macromechanical and coupled micromechanical approaches by some investigators. The uncoupled macromechanical approaches ignore the effect of microstructural gradation by employing specific spatial variations of material properties, which are either assumed or obtained by local homogenization, thereby resulting in erroneous results under certain circumstances. In contrast, the coupled approaches explicitly account for the micro-macrostructural interaction, albeit at a significantly higher computational cost. The higher-order theory for functionally graded materials (HOTFGM) developed by Aboudi et al. is representative of the coupled approach. However, despite its demonstrated utility in applications where micro-macrostructural coupling effects are important, the theory's full potential is yet to be realized because the original formulation of HOTFGM is computationally intensive. This, in turn, limits the size of problems that can be solved due to the large number of equations required to mimic realistic material microstructures. Therefore, a basis for an efficient reformulation of HOTFGM, referred to as user-friendly formulation, is developed herein, and subsequently employed in the construction of the efficient reformulation using the local/global conductivity matrix approach. In order to extend HOTFGM's range of applicability, spatially variable thermal conductivity capability at the local level is incorporated into the efficient reformulation. Analytical solutions to validate both the user-friendly and efficient reformulations am also developed. Volume discretization sensitivity and validation studies, as well as a practical application of the developed efficient reformulation are subsequently carried out. The presented results illustrate the accuracy and implementability of both the user-friendly formulation and the efficient reformulation of HOTFGM.

Zhong, Yi; Pindera, Marek-Jerzy; Arnold, Steven M. (Technical Monitor)

2002-01-01

137

Communications technology satellite - A variable conductance heat pipe application  

NASA Technical Reports Server (NTRS)

A variable-conductance heat pipe system (VCHPS) has been designed to provide thermal control for a transmitter experiment package (TEP) to be flown on the Communications Technology Satellite. The VCHPS provides for heat rejection during TEP operation and minimizes the heat leak during power down operations. The VCHPS described features a unique method of aiding priming of arterial heat pipes and a novel approach to balancing heat pipe loads by staggering their control ranges.

Mock, P. R.; Marcus, B. D.; Edelman, E. A.

1974-01-01

138

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

139

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

140

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

141

HOWFIC: A Finite Difference Program for Analysis of Heat Conduction and Ground Water Movement in Rock Mass Surrounding Underground Caverns.  

National Technical Information Service (NTIS)

HOWFIC is a finite difference program for analysis of heat conduction and water flow in rock mass around caverns and is discussed in the report. The program can solve both 2-D and 3-D, steady-state and transient problems. Various boundary and initial cond...

M. Lu

1991-01-01

142

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

143

Spherical harmonic analysis of earth's conductive heat flow  

Microsoft Academic Search

A reappraisal of the international heat flow database has been carried out and the corrected data set was employed in spherical harmonic analysis of the conductive component of global heat flow. Procedures used prior to harmonic analysis include analysis of the heat flow data and determination of representative mean values for a set of discretized area elements of the surface

V. M. Hamza; R. R. Cardoso; C. F. Ponte Neto

2008-01-01

144

A Fourier-Chebyshev pseudospectral method for solving steady 3-D Navier-Stokes and heat equations in cylindrical cavities  

Microsoft Academic Search

A Fourier-Chebyshev pseudospectral method for solving steady 3D Navier-Stokes equations in cylindrical cavities is presented and discussed. The general method is pseudo-unsteady and uses a semi-implicit finite difference scheme for the time discretization. The generalized ADI (Alternating Direction Implicit) procedure is then applied to reduce the problem to a successive solution of one-dimensional problems. The spatial approximation uses a Fourier-Galerkin

J. P. Pulicani; J. Ouazzani

1991-01-01

145

Numerical modelling of 3D plastic flow and heat transfer during friction stir welding of stainless steel  

Microsoft Academic Search

Three-dimensional (3D) viscoplastic flow and temperature field during friction stir welding (FSW) of 304 austenitic stainless steel were mathematically modelled. The equations of conservation of mass, momentum and energy were solved in three dimensions using spatially variable thermophysical properties using a methodology adapted from well established previous work in fusion welding. Non-Newtonian viscosity for the metal flow was calculated considering

R. Nandan; G. G. Roy; T. J. Lienert; T. DebRoy

2006-01-01

146

Phononic Heat Conduction in Disordered Crystals  

Microsoft Academic Search

We investigate the question as to whether disordered harmonic crystals in two and three dimensions have a finite thermal conductivity. A heuristic argument using localization theory and kinetic theory is given to estimate the system size dependence of the current. Numerical results testing these predictions are then discussed. The numerical studies are based on the Landauer formula using phonon transmission

Abhishek Dhar

2011-01-01

147

Combined 3-D Flow and Heat Transfer Measurements in a 2Pass Internal Coolant Passage of Gas Turbine Airfoils  

Microsoft Academic Search

A study of the flow and heat transfer in a stationary model of a two-pass internal coolant passage is presented, which focuses on the flow characteristic effects on the wall heat transfer distribution. Results are given in the upstream fully developed region. Heat transfer measurements were made with a transient technique using thermochromic liquid crystal technique to measure a surface

D. Chanteloup; Y. Juaneda; A. Bo?lcs

2002-01-01

148

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

149

A criterion of applicability of the parabolic heat conduction equation  

NASA Astrophysics Data System (ADS)

A criterion ( K MCV) of applicability of the parabolic heat conduction equation to isotropic materials is proposed that quantitatively determines the conditional boundary between linear and nonlinear regimes of nonequilibrium thermodynamics in the one-dimensional formulation of some heat transfer problems. The criterion is related to the heat flux relaxation time ?r. Once this characteristic time is known, the condition K MCV = 0 implies validity of the parabolic heat conduction equation. If ?r is unknown, the adequacy of the parabolic heat conduction model can be judged from the absence of a temporal variation of the K MCV/?r ratio under the main condition that the heat source power is independent of the time.

Kostanovskiy, A. V.; Kostanovskaya, M. E.

2008-06-01

150

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

151

Heat conduction in deformable Frenkel-Kontorova lattices: Thermal conductivity and negative differential thermal resistance  

NASA Astrophysics Data System (ADS)

Heat conduction through the Frenkel-Kontorova lattices is numerically investigated in the presence of a deformable substrate potential. It is found that the deformation of the substrate potential has a strong influence on heat conduction. The thermal conductivity as a function of the shape parameter is nonmonotonic. The deformation can enhance thermal conductivity greatly, and there exists an optimal deformable value at which thermal conductivity takes its maximum. Remarkably, we also find that the deformation can facilitate the appearance of the negative differential thermal resistance.

Ai, Bao-Quan; Hu, Bambi

2011-01-01

152

Heat conduction in deformable Frenkel-Kontorova lattices: thermal conductivity and negative differential thermal resistance.  

PubMed

Heat conduction through the Frenkel-Kontorova lattices is numerically investigated in the presence of a deformable substrate potential. It is found that the deformation of the substrate potential has a strong influence on heat conduction. The thermal conductivity as a function of the shape parameter is nonmonotonic. The deformation can enhance thermal conductivity greatly, and there exists an optimal deformable value at which thermal conductivity takes its maximum. Remarkably, we also find that the deformation can facilitate the appearance of the negative differential thermal resistance. PMID:21405685

Ai, Bao-quan; Hu, Bambi

2011-01-01

153

Geometrically Unidimensional Heat Conduction in Melting and Solidification.  

National Technical Information Service (NTIS)

An analytical approximation method is given for the solution of one-dimensional heat-conduction problems involving simultaneous phase change in melting and solidification processes. The starting point is a polynomial expression for the temperature distrib...

F. Megerlin

1968-01-01

154

Kohlrausch Heat Conductivity Apparatus for Intermediate or Advanced Laboratory  

ERIC Educational Resources Information Center

Describes student experiment in measuring heat conductivity according to Kohlrausch's method. Theory, apparatus design, and experimental procedure is outlined. Results for copper are consistent to within 2 percent. (LC)

Jensen, H. G.

1970-01-01

155

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

156

Sequential Regularization Solution of the Inverse Heat Conduction Problem.  

National Technical Information Service (NTIS)

The Inverse Heat Conduction Problem (IHCP) is defined and a sequential regularization solution is presented. Although the algorithm is developed specifically for the first-order regularization procedure, it can be extended to any order. Example calculatio...

J. V. Beck B. F. Blackwell C. R. St. Clair

1985-01-01

157

Monte Carlo Heat Conduction Using the Transport Equation Approximation.  

National Technical Information Service (NTIS)

The use of Monte Carlo radiation transport codes to solve heat conduction problems was shown to be applicable to steady state and time dependent multi-media problems. An improved method for treating problems with given surface temperature distributions is...

S. K. Fraley

1977-01-01

158

Ballistic heat conduction and mass disorder in one dimension.  

PubMed

It is well-known that in the disordered harmonic chain, heat conduction is subballistic and the thermal conductivity (?) scales asymptotically as [Formula: see text] where L is the chain length. However, using the nonequilibrium Green's function (NEGF) method and analytical modelling, we show that there exists a critical crossover length scale (LC) below which ballistic heat conduction [Formula: see text] can coexist with mass disorder. This ballistic-to-subballistic heat conduction crossover is connected to the exponential attenuation of the phonon transmittance function ? i.e. ?(?, L) = exp[-L/?(?)], where ? is the frequency-dependent attenuation length. The crossover length can be determined from the minimum attenuation length, which depends on the maximum transmitted frequency. We numerically determine the dependence of the transmittance on frequency and mass composition as well as derive a closed form estimate, which agrees closely with the numerical results. For the length-dependent thermal conductance, we also derive a closed form expression which agrees closely with numerical results and reproduces the ballistic to subballistic thermal conduction crossover. This allows us to characterize the crossover in terms of changes in the length, mass composition and temperature dependence, and also to determine the conditions under which heat conduction enters the ballistic regime. We describe how the mass composition can be modified to increase ballistic heat conduction. PMID:25077430

Ong, Zhun-Yong; Zhang, Gang

2014-08-20

159

Spherical harmonic analysis of earth’s conductive heat flow  

Microsoft Academic Search

A reappraisal of the international heat flow database has been carried out and the corrected data set was employed in spherical\\u000a harmonic analysis of the conductive component of global heat flow. Procedures used prior to harmonic analysis include analysis\\u000a of the heat flow data and determination of representative mean values for a set of discretized area elements of the surface

V. M. Hamza; R. R. Cardoso; C. F. Ponte Neto

2008-01-01

160

Use of Spreadsheets in Solving Heat Conduction Problems in Fins  

NSDL National Science Digital Library

Excel is an effective and inexpensive tool available on all computers equipped with Microsoft Office. This software has the necessary functions for solving a large class of engineering problems, including those related to heat transfer. This paper provides several examples to demonstrate the application of Excel in solving problems involving one-dimensional heat conduction in various fin configurations. It provides formulas for the temperature distribution and heat transfer for several different fin profiles.

Karimi, Amir

2011-04-04

161

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

162

Heat characteristic analysis of a conduction cooling toroidal-type SMES magnet  

NASA Astrophysics Data System (ADS)

This paper analyzed the heat characteristics of a conduction cooling toroidal-type SMES magnet. The authors designed and manufactured a conduction cooling toroidal-type SMES magnet which consists of 30 double pancake coils. One (a single pancake coil) of a double pancake coil is arranged at an angle of 6° from each other. The shape of the toroidal-type SMES magnet was designed by a 3D CAD program. The heat invasion was investigated under no-load condition and the thermal characteristic of the toroidal-type SMES magnet was analyzed using the Finite Elements Method program. Both the analyzed and the experiment results are compared and discussed in detail.

Kim, K. M.; Kim, A. R.; Kim, J. G.; Kim, D. W.; Park, M.; Yu, I. K.; Eom, B. Y.; Sim, K.; Kim, S. H.; Shon, M. H.; Kim, H. J.; Bae, H. J.; Seong, K. C.

2010-11-01

163

Normal heat conductivity in chains capable of dissociation  

NASA Astrophysics Data System (ADS)

The paper considers the highly debated problem of convergence of heat conductivity in one-dimensional chains with asymmetric nearest-neighbor potential. We conjecture that the convergence may be promoted not by the mere asymmetry of the potential, but due to the possibility that the chain dissociates. In other terms, the attractive part of the potential function should approach a finite value as the distance between the neighbors grows. To clarify this point, we study the simplest model of this sort —a chain of linearly elastic rods with finite size. If the distance between the rod centers exceeds their size, the rods cease to interact. Formation of gaps between the rods is the only possible mechanism for scattering of the elastic waves. Heat conduction in this system turns out to be convergent. Moreover, an asymptotic behavior of the heat conduction coefficient for the case of large densities and relatively low temperatures obeys a simple Arrhenius-type law. In the limit of low densities, the heat conduction coefficient converges due to triple rod collisions. Numeric observations in both limits are grounded by analytic arguments. In a chain with Lennard-Jones nearest-neighbor potential the heat conductivity also saturates in a thermodynamic limit and the coefficient also scales according to the Arrhenius law for low temperatures. This finding points on a universal role played by the possibility of dissociation, as convergence of the heat conduction coefficient is considered.

Gendelman, O. V.; Savin, A. V.

2014-05-01

164

Design and development of ultra-wideband 3 dB hybrid coupler for Ion cyclotron resonance frequency heating in tokamak.  

PubMed

Design and development of a high power ultra-wideband, 3 dB tandem hybrid coupler is presented and its application in ICRF heating of the tokamak is discussed. In order to achieve the desired frequency band of 38-112 MHz and 200 kW power handling capability, the 3 dB hybrid coupler is developed using two 3-element 8.34 ± 0.2 dB coupled lines sections in tandem. In multi-element coupled lines, junctions are employed for the joining of coupled elements that produce the undesirable reactance called junction discontinuity effect. The effect becomes prominent in the high power multi-element coupled lines for high frequency (HF) and very high frequency(VHF) applications because of larger structural dimensions. Junction discontinuity effect significantly deteriorates coupling and output performance from the theoretical predictions. For the analysis of junction discontinuity effect and its compensation, a theoretical approach has been developed and generalized for n-element coupled lines section. The theory has been applied in the development of the 3 dB hybrid coupler. The fabricated hybrid coupler has been experimentally characterized using vector network analyzer and obtained results are found in good agreement with developed theory. PMID:24784637

Yadav, Rana Pratap; Kumar, Sunil; Kulkarni, S V

2014-04-01

165

Single-photon heat conduction in electrical circuits  

NASA Astrophysics Data System (ADS)

We study photonic heat conduction between two resistors coupled weakly to a single superconducting microwave cavity. At low enough temperature, the dominant part of the heat exchanged between the resistors is transmitted by single-photon excitations of the fundamental mode of the cavity. This manifestation of single-photon heat conduction should be experimentally observable with the current state of the art. Our scheme can possibly be utilized in remote interference-free temperature control of electric components and environment engineering for superconducting quantum bits coupled to cavities.

Jones, P. J.; Huhtamäki, J. A. M.; Tan, K. Y.; Möttönen, M.

2012-02-01

166

Conduction phase change beneath insulated heated or cooled structures  

NASA Astrophysics Data System (ADS)

The problem of thawing beneath heated structures on permafrost (or cooled structures in non-permafrost zones) must be addressed if safe engineering designs are to be conceived. In general, there are no exact solutions to the problem of conduction heat transfer with phase change for practical geometries. The quasi-steady approximation is used here to solve the conductive heat transfer problem with phase change for insulated geometries including infinite strips, rectangular buildings, circular storage tanks, and buried pipes. Analytical solutions are presented and graphed for a range of parameters of practical importance.

Lunardini, V. J.

1982-08-01

167

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

168

Verification for transient heat conduction calculation of multilayer building constructions  

Microsoft Academic Search

Validation and verification of building simulation programs and load calculation programs is of continuing interest. Dynamic thermal behavior data, including conduction transfer function (CTF) coefficients, thermal response factors and periodic response factors, are used to calculate transient heat conduction through building constructions. Computational inaccuracy sometimes occurs in calculating CTF coefficients and response factors. In this paper, a method for verification

Youming Chen; Juan Zhou; Jeffrey D. Spitler

2006-01-01

169

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

170

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

171

Numerical simulation of heat transfer and flow structure in 3-D turbulent boundary layer with imbedded longitudinal vortex  

SciTech Connect

Heat transfer characteristics and flow structure in turbulent flows through a flat plate three-dimensional turbulent boundary layer containing built-in vortex generators have been analyzed by means of the space marching Crank-Nicolson finite difference method. The method solves the slender flow approximation of the steady three-dimensional Navier-Stokes and energy equations. This study used the eddy diffusivity model and standard {kappa}-{epsilon} model to predict heat transfer and flow field in the turbulent flow with imbedded longitudinal vortex. The results show boundary layer distortion due to vortices, such as strong spanwise flow divergence and boundary layer thinning. The heat transfer and skin friction show relatively good results in comparison with experimental data. The vortex core moves slightly away from the wall and grows slowly; consequently, the vortex influences the flow over a very long distance downstream. The enhancement of the heat transfer in the vicinity of the wall is due to the increasing spanwise separation of the vortices as they develop in the streamwise direction.

Jeong, J.Y.; Ryou, H.S. [Chung-Ang Univ., Seoul (Korea, Republic of). Dept. of Mechanical Engineering

1997-03-01

172

Thermal conductivity of metal cloth heat pipe wicks  

NASA Astrophysics Data System (ADS)

Experimental results on heat conduction through a metal cloth wick saturated with a liquid are determined and compared to results from both a new mean-gap-conductance model, based on the wick geometry, and the simple series model. The mean-gap-conductance model includes three-dimensional and contact conductance effects, and it evaluates the effects of the mesh geometry in addition to predicting the effective conductivity. This new model predicts the experimental data to within 10 percent, while the series model may be more than 40 percent in error. The present model is used to determine theoretical limits on the maximum and minimum conductivity enhancement as a function of geometric parameters, and to establish guidelines for the design of heat pipe wicks.

Phillips, J. R.; Chow, L. C.; Grosshandler, W. L.

1987-08-01

173

Joint inversion of steady-state hydrologic and self-potential data for 3D hydraulic conductivity distribution at the Boise Hydrogeophysical Research Site  

NASA Astrophysics Data System (ADS)

SummaryWe combine sedimentological, hydraulic and geophysical information to characterize the 3D distribution of transport properties of an heterogeneous aquifer. We focus on the joint inversion of hydraulic head and self-potential measurements collected during an extensive experimental campaign performed at the Boise Hydrogeophysical Research Site (BHRS), Boise, Idaho, and involving a series of dipole tests. While hydraulic head data obtained from piezometric readings in open wells represent a depth-averaged value, self-potential signals provide an estimate of the water table location. The aquifer is conceptualized as a multiple-continuum, where the volumetric fraction of a geo-material within a cell of the numerical flow model is calculated by Multiple Indicator Kriging. The latter is implemented on the basis of available sedimentological information. The functional format of the indicator variograms and associated parameters are estimated on the basis of formal model identification criteria. Self-potential and hydraulic head data have been embedded jointly within a three-dimensional inverse model of groundwater flow at the site. Each identified geo-material (category) is assumed to be characterized by a constant hydraulic conductivity. The latter constitute the set of model parameters. The hydraulic conductivity associated with a numerical block is then calculated as a weighted average of the conductivities of the geo-materials which are collocated in the block by means of Multiple Indicator Kriging. Model parameters are estimated by a Maximum Likelihood fit between measured and modeled state variables, resulting in a spatially heterogeneous distribution of hydraulic conductivity. The latter is effectively constrained on the sedimentological data and conditioned on both self-potential and borehole hydraulic head readings. Minimization of the Maximum Likelihood objective function allows estimating the relative weight of measurement errors associated with self-potential and borehole-based head data. The procedure adopted allowed a reconstruction of the heterogeneity of the site with a level of details, which was not obtained in previous studies and with relatively modest computational efforts. Further validation against dipole tests which were not used in the inversion procedure supports the robustness of the results.

Straface, Salvatore; Chidichimo, Francesco; Rizzo, Enzo; Riva, Monica; Barrash, Warren; Revil, André; Cardiff, Michael; Guadagnini, Alberto

2011-09-01

174

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

175

Numerical 3D modeling of heat transfer in human tissues for microwave radiometry monitoring of brown fat metabolism  

NASA Astrophysics Data System (ADS)

Background: Brown adipose tissue (BAT) plays an important role in whole body metabolism and could potentially mediate weight gain and insulin sensitivity. Although some imaging techniques allow BAT detection, there are currently no viable methods for continuous acquisition of BAT energy expenditure. We present a non-invasive technique for long term monitoring of BAT metabolism using microwave radiometry. Methods: A multilayer 3D computational model was created in HFSSTM with 1.5 mm skin, 3-10 mm subcutaneous fat, 200 mm muscle and a BAT region (2-6 cm3) located between fat and muscle. Based on this model, a log-spiral antenna was designed and optimized to maximize reception of thermal emissions from the target (BAT). The power absorption patterns calculated in HFSSTM were combined with simulated thermal distributions computed in COMSOL® to predict radiometric signal measured from an ultra-low-noise microwave radiometer. The power received by the antenna was characterized as a function of different levels of BAT metabolism under cold and noradrenergic stimulation. Results: The optimized frequency band was 1.5-2.2 GHz, with averaged antenna efficiency of 19%. The simulated power received by the radiometric antenna increased 2-9 mdBm (noradrenergic stimulus) and 4-15 mdBm (cold stimulus) corresponding to increased 15-fold BAT metabolism. Conclusions: Results demonstrated the ability to detect thermal radiation from small volumes (2-6 cm3) of BAT located up to 12 mm deep and to monitor small changes (0.5 °C) in BAT metabolism. As such, the developed miniature radiometric antenna sensor appears suitable for non-invasive long term monitoring of BAT metabolism.

Rodrigues, Dario B.; Maccarini, Paolo F.; Salahi, Sara; Colebeck, Erin; Topsakal, Erdem; Pereira, Pedro J. S.; Limão-Vieira, Paulo; Stauffer, Paul R.

2013-02-01

176

Numerical 3D modeling of heat transfer in human tissues for microwave radiometry monitoring of brown fat metabolism  

PubMed Central

Background Brown adipose tissue (BAT) plays an important role in whole body metabolism and could potentially mediate weight gain and insulin sensitivity. Although some imaging techniques allow BAT detection, there are currently no viable methods for continuous acquisition of BAT energy expenditure. We present a non-invasive technique for long term monitoring of BAT metabolism using microwave radiometry. Methods A multilayer 3D computational model was created in HFSS™ with 1.5 mm skin, 3–10 mm subcutaneous fat, 200 mm muscle and a BAT region (2–6 cm3) located between fat and muscle. Based on this model, a log-spiral antenna was designed and optimized to maximize reception of thermal emissions from the target (BAT). The power absorption patterns calculated in HFSS™ were combined with simulated thermal distributions computed in COMSOL® to predict radiometric signal measured from an ultra-low-noise microwave radiometer. The power received by the antenna was characterized as a function of different levels of BAT metabolism under cold and noradrenergic stimulation. Results The optimized frequency band was 1.5–2.2 GHz, with averaged antenna efficiency of 19%. The simulated power received by the radiometric antenna increased 2–9 mdBm (noradrenergic stimulus) and 4–15 mdBm (cold stimulus) corresponding to increased 15-fold BAT metabolism. Conclusions Results demonstrated the ability to detect thermal radiation from small volumes (2–6 cm3) of BAT located up to 12 mm deep and to monitor small changes (0.5 °C) in BAT metabolism. As such, the developed miniature radiometric antenna sensor appears suitable for non-invasive long term monitoring of BAT metabolism.

Rodrigues, Dario B.; Maccarini, Paolo F.; Salahi, Sara; Colebeck, Erin; Topsakal, Erdem; Pereira, Pedro J. S.; Limao-Vieira, Paulo; Stauffer, Paul R.

2013-01-01

177

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

NASA Technical Reports Server (NTRS)

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.

1985-01-01

178

Prediction of 3D airflow and temperature field in an indoor ice rink with radiant heat sources  

Microsoft Academic Search

Three dimensional mixed convection in an ice rink heated by radiant heaters was simulated numerically using the standard k-? model with wall functions. This large building was first modelled under steady state conditions by considering or not surface-to-surface\\u000a radiation between the internal surfaces and with the radiant heaters ON or OFF. After those four basic scenarios the transient\\u000a behaviour was

Mohamed Omri; Nicolas Galanis

2010-01-01

179

Heat conduction in the Frenkel-Kontorova model.  

PubMed

Heat conduction is an old yet important problem. Since Fourier introduced the law bearing his name almost 200 years ago, a first-principle derivation of this simple law from statistical mechanics is still lacking. Worse still, the validity of this law in low dimensions, and the necessary and sufficient conditions for its validity are far from clear. In this paper we will review recent works on heat conduction in a simple nonintegrable model called the Frenkel-Kontorova model. The thermal conductivity of this model has been found to be finite. We will study the dependence of the thermal conductivity on the temperature and other parameters of the model such as the strength and the periodicity of the external potential. We will also discuss other related problems such as phase transitions and finite-size effects. The study of heat conduction is not only of theoretical interest but also of practical interest. We will show various recent designs of thermal rectifiers and thermal diodes by coupling nonlinear chains together. The study of heat conduction in low dimensions is also important to the understanding of the thermal properties of carbon nanotubes. PMID:15836296

Hu, Bambi; Yang, Lei

2005-03-01

180

Heat transfer in axially conducting flow and periodically contacting solids  

NASA Astrophysics Data System (ADS)

The effects of axial heat conduction on the temperature distribution and local Nusselt number in a fluid for forced convection in a circular tube subjected to various boundary conditions are investigated theoretically. Fully developed laminar flow inside a tube with an insulated upstream region followed by a uniformly heated downstream region. Two independent analytical methods are developed for the solution of this problem. The techniques are extended to solve problems with convective boundaries for the upstream and downstream regions. The cases of both a laminar and slug flow velocity model are considered. The results show that the axial heat conduction in the fluid significantly effects the bulk and wall temperatures and local Nusselt number in the thermal entrance region, with the effects becoming more pronounced at lower Peclet numbers. Also the results obtained with convective boundary conditions show that the external heat transfer coefficients significantly effect the temperature distribution, and hence the Nusselt number, in the thermal entrance region.

Vick, B.

1981-08-01

181

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

182

NON-FOURIER HEAT CONDUCTION PHENOMENA IN POROUS MATERIAL HEATED BY MICROSECOND LASER PULSE  

Microsoft Academic Search

Experiments on porous material heated by a microsecond laser pulse and the corresponding theoretical analysis are carried out. Some non-Fourier heat conduction phenomena are observed in the experimental sample. The experimental results indicate that only if the thermal disturbance is strong enough (i.e., the pulse duration is short enough and the pulse heat flux is great enough) is it possible

Fangming Jiang

2003-01-01

183

Mechanical control of heat conductivity in molecular chains.  

PubMed

We discuss a possibility to control heat conductivity in molecular chains by means of external mechanical loads. To illustrate such possibilities we consider first well-studied one-dimensional chain with degenerate double-well potential of the nearest-neighbor interaction. We consider varying lengths of the chain with fixed number of particles. Number of possible energetically degenerate ground states strongly depends on the overall length of the chain, or, in other terms, on average length of the link between neighboring particles. These degenerate states correspond to mechanical equilibria; therefore, one can say that formation of such structures mimics a process of plastic deformation. We demonstrate that such modification of the chain length can lead to quite profound (almost fivefold) reduction of the heat conduction coefficient. Even more profound effect is revealed for a model with a single-well nonconvex potential. It is demonstrated that in a certain range of constant external forcing, this model becomes effectively double-well and has a multitude of possible states of equilibrium for fixed value of the external load. Due to this degeneracy, the heat-conduction coefficient can be reduced by two orders of magnitude. We suggest a mechanical model of a chain with periodic double-well potential, which allows control of the heat transport. The models considered may be useful for description of heat transfer in biological macromolecules and for control of the heat transport in microsystems. The possibility of the heat transport control in more realistic three-dimensional systems is illustrated by simulation of a three-dimensional model of polymer ?-helix. In this model, the mechanical stretching also brings about the structural inhomogeneity and, in turn, to essential reduction of the heat conductivity. PMID:24580199

Savin, A V; Gendelman, O V

2014-01-01

184

Numerical study of flow and heat-transfer characteristics of cryogenic slush fluid in a horizontal circular pipe (SLUSH-3D)  

NASA Astrophysics Data System (ADS)

Cryogenic slush fluids, such as slush hydrogen and slush nitrogen, are two-phase, single-component fluids containing solid particles in a liquid. Since their density and refrigerant capacity are greater than those of liquid-state fluids alone, there are high expectations for use of slush fluids as functionally thermal fluids in various applications, such as fuels for spacecraft engines, clean energy fuels to improve the efficiency of transportation and storage, and as refrigerants for high-temperature superconducting equipment. In this research, a three-dimensional numerical simulation code (SLUSH-3D), including the gravity effect based on the thermal non-equilibrium, two-fluid model, was constructed to clarify the flow and heat-transfer characteristics of cryogenic slush fluids in a horizontal circular pipe. The calculated results of slush nitrogen flow performed using the numerical code were compared with the authors' experimental results obtained using the PIV method. As a result of these comparisons, the numerical code was verified, making it possible to analyze the flow and heat-transfer characteristics of slush nitrogen with sufficient accuracy. The numerical results obtained for the flow and heat-transfer characteristics of slush nitrogen and slush hydrogen clarified the effects of the pipe inlet velocity, solid fraction, solid particle size, and heat flux on the flow pattern, solid-fraction distribution, turbulence energy, pressure drop, and heat-transfer coefficient. Furthermore, it became clear that the difference of the flow and heat-transfer characteristics between slush nitrogen and slush hydrogen were caused to a large extent by their thermo-physical properties, such as the solid-liquid density ratio, liquid viscosity, and latent heat of fusion.

Ohira, Katsuhide; Ota, Atsuhito; Mukai, Yasuaki; Hosono, Takumi

2012-07-01

185

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

186

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

187

Heat conduction in one-dimensional aperiodic quantum Ising chains.  

PubMed

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 J{m} between the nearest-neighbor spins takes the two values J{A} and J{B} 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. PMID:21517475

Li, Wenjuan; Tong, Peiqing

2011-03-01

188

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

189

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

190

Application of genetic algorithms in nonlinear heat conduction problems.  

PubMed

Genetic algorithms are employed to optimize dimensionless temperature in nonlinear heat conduction problems. Three common geometries are selected for the analysis and the concept of minimum entropy generation is used to determine the optimum temperatures under the same constraints. The thermal conductivity is assumed to vary linearly with temperature while internal heat generation is assumed to be uniform. The dimensionless governing equations are obtained for each selected geometry and the dimensionless temperature distributions are obtained using MATLAB. It is observed that GA gives the minimum dimensionless temperature in each selected geometry. PMID:24695517

Kadri, Muhammad Bilal; Khan, Waqar A

2014-01-01

191

Neutrino Heat Conduction and Inhomogeneities in the Early Universe  

NASA Technical Reports Server (NTRS)

Constraints on parameters of inhomogeneous nucteosynthesis, namely, the overdensity and size of baryon lumps, are found by calculatig the blackbody neutrino heat conduction into the lumps, which tends to inflate them away. The scale size for efficient heat conduction is determined by the mean free path lambda of the neutrino, and so we compute lambda in our case of a high-temperature plasma with low chemical potential, and find a general result that many-body effects are unimportant, simplifying the calculation. We find that in the region of interest for nucleosynthesis, neutrino inflation is important for overdensities greater than 10(exp 4).

Heckler, A.; Hogan, C. J.

1993-01-01

192

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

193

Computer Program For Variable-Conductance Heat Pipes  

NASA Technical Reports Server (NTRS)

VCHPDA provides accurate mathematical models of transient as well as steady-state performance of variable-conductance heat pipes over wide range of operating conditions. Applies to heat pipes with either cold, wicked or hot, nonwicked gas reservoirs and uses ideal-gas law and "flat-front" (negligible vapor diffusion) gas theory. Calculates length of gas-blocked region and temperature of vapor in active portion of heat pipe by solving set of nonlinear equations for conservation of energy and mass. Written in FORTRAN 77.

Antoniuk, D.

1992-01-01

194

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

195

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

196

3D input for 3D worlds  

Microsoft Academic Search

Virtual Worlds present a 3D space to the user. However, input devices are typically 2D. This unnatural mapping reduces the engagement of the experience. We are exploring using Wii controllers to provide 3D gesture-based input to the 3D virtual world, Second Life. By evaluating its usability, we found that gesture-based interfaces are appealing and natural for hand gestures such as

Sreeram Sreedharan; Edmund S. Zurita; Beryl Plimmer

2007-01-01

197

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

198

Influence of heat bath on the heat conductivity in disordered anharmonic chain  

NASA Astrophysics Data System (ADS)

We study heat conduction in a one-dimensional disordered anharmonic chain with arbitrary heat bath by using extended Ford, Kac and Mazur (FKM) formulation, which satisfy the fluctuation-dissipation theorem. A simple formal expression for the heat conductivity ? is obtained, from which the asymptotic system-size (N) dependence is extracted. It shows ?˜N?. As a special case we give the expression that ?˜N1/2 for free boundaries, and ?˜ N-1/2 for fixed boundaries, from which we can get the conclusion that the momentum conservation is a key factor of the anomalous heat conduction. Comparing with different ?T, the heat conductivity shows large difference between the linear system and the nonlinear system.

Zhao, H.; Yi, L.; Liu, F.; Xu, B.

2006-11-01

199

Heat Conductivity of Polyatomic and Polar Gases and Gas Mixtures  

Microsoft Academic Search

A theory is presented which can be used for the practical calculation of the heat conductivity of polyatomic and polar gases and gas mixtures. For pure gases, the results are based on the Wang Chang—Uhlenbeck equations and involve no approximations, provided that a suitable definition of an internal diffusion coefficient is employed. This is compared with the known results for

L. Monchick; A. N. G. Pereira; E. A. Mason

1965-01-01

200

Thin-Film Conducting Microgrids as Transparent Heat Mirrors.  

National Technical Information Service (NTIS)

A new type of transparent heat mirror for solar-energy applications has been fabricated by chemically etching a Sn-doped In2O3 film to form a transparent conducting microgrid. For square openings 2.5 micrometers on a side, separated by lines 0.6 micromete...

J. C. Fan F. J. Bachner R. A. Murphy

1975-01-01

201

Identification of unknown parameters for heat conductivity equations  

Microsoft Academic Search

An algorithm for identification of unknown parameters of nonlinear heat conductivity equations is proposed. Solutions of equations observed with an error are input data of the algorithm. Finite dimensional approximations of input signals and their derivatives are used. The algorithm utilizes the idea of the direct minimization of the residual of equations written in an appropriate variational form. The convergence

N. D. Botkin

1995-01-01

202

Equivalence transformations and symmetries for a heat conduction model  

Microsoft Academic Search

In the framework of Extended Thermodynamics, we consider the unidimensional case of a non-linear system of partial differential equations describing the heat conduction in a rigid body and removing the well known paradox of thermal pulses propagating with infinite speed. Because of the strong non-linearity of the model we look for an invariant classification via equivalence transformations. Some general results

M. Torrisi; R. Tracinà

1998-01-01

203

A one year 3D oceanic simulation in the North-East Atlantic: application to heat budgets and subduction during the POMME experiment  

NASA Astrophysics Data System (ADS)

A 3D oceanic model derived from a 1D turbulent mixing parameterization (Gaspar et al., 1990) was built in order to evaluate separately the impacts of the different processes on the oceanic mixed layer heat budget and the detrainment-entrainment rates in the Northeastern Atlantic during the POMME experiment (September 2000 - September 2001). The original feature of this model is that the geostrophic dynamics are prescribed from independent altimetric and analyses data. This model is forced by daily surface heat and momentum fluxes derived from satellite data, model outputs and surface turbulent fluxes parameterization. This model is initialized from the hydrological networks collected during the POMME experiment. Two annual cycles (without and with surface fluxes corrections) were simulated between POMME0 (28/09/00) and POMME3 (29/09/01) including two restarts at POMME1 (13/02/01) and POMME2 (04/04/01). Annual heat and subduction budgets are presented. A particular attention is made in regions where strong interactions occur between fronts and eddies and eddies themselves. Particularly, it is shown that subduction can be induced by the evolution of the mesoscale structures.

Giordani, H.; Caniaux, G.; Prieur, L.; Paci, A.

2003-04-01

204

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

205

Variable conductance heat pipes from the laboratory to space  

NASA Technical Reports Server (NTRS)

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) or as a thermal diode that allows heat to be transferred in one direction only. To establish flight level confidence in these basic control techniques, the Ames Heat Pipe Experiment (AHPE) was launched in August 1972 and the Advanced Thermal Control Flight Experiment (ATFE) is scheduled for launch in May 1973. The major efforts of the technology development, initial flight results of the AHPE, and ground test data of the ATFE are discussed.

Kirkpatrick, J. P.

1973-01-01

206

High temperature electrically conducting ceramic heating element and control system  

NASA Technical Reports Server (NTRS)

Improvements were made in both electrode technology and ceramic conductor quality to increase significantly the lifetime and thermal cycling capability of electrically conducting ceramic heater elements. These elements were operated in vacuum, inert and reducing environments as well as oxidizing atmospheres adding to the versatility of the conducting ceramic as an ohmic heater. Using stabilized zirconia conducting ceramic heater elements, a furnace was fabricated and demonstrated to have excellent thermal response and cycling capability. The furnace was used to melt platinum-20% rhodium alloy (melting point 1904 C) with an isothermal ceramic heating element having a nominal working cavity size of 2.5 cm diameter by 10.0 cm long. The furnace was operated to 1940 C with the isothermal ceramic heating element. The same furnace structure was fitted with a pair of main heater elements to provide axial gradient temperature control over a working cavity length of 17.8 cm.

Halbach, C. R.; Page, R. J.

1975-01-01

207

Two-dimensional heat conduction in metal, fluid composites  

NASA Astrophysics Data System (ADS)

Because the size and weight of main propulsion and auxiliary systems are inversely proportional to the ease in which heat or energy is exchanged, a major thrust of the research and development program of the U.S. Navy is toward the design and development of equipment that perform at higher efficiency with a reduction in size and weight. In particular, one area of great interest is the reduction in size and weight of steam condensers. The heat-transfer effectiveness is governed by the amount of surface and the overall resistance to the flow of heat. Filmwise condensation of steam on externally-finned tubes is a very complex process. Recent experiments have shown that enhancement ratios (ratio of steam-side heat-transfer coefficient to that of a smooth tube having the same diameter) exceeded the area enhancement produced by the fins. Moreover, the enhancement ratios for fully flooded tubes exceed the values predicted by a simple, one-dimensional conduction model by a factor of 2 to 4. A new two-dimensional conduction model was developed, which showed that the one-dimensional model overpredicted the two-dimensional results for high conductivity tube-metals such as copper by as much as 13%. The two-dimensional model also showed that variations in fin thickness or spacing can result in an overprediction by the one-dimensional model of the two-dimensional results by as much as twenty-two percent.

Gomori, M. A.

1985-12-01

208

Heat conduction in graphene: experimental study and theoretical interpretation  

NASA Astrophysics Data System (ADS)

We review the results of our experimental investigation of heat conduction in suspended graphene and offer a theoretical interpretation of its extremely high thermal conductivity. The direct measurements of the thermal conductivity of graphene were performed using a non-contact optical technique and special calibration procedure with bulk graphite. The measured values were in the range of ~3000-5300 W mK-1 near room temperature and depended on the lateral dimensions of graphene flakes. We explain the enhanced thermal conductivity of graphene as compared to that of bulk graphite basal planes by the two-dimensional nature of heat conduction in graphene over the whole range of phonon frequencies. Our calculations show that the intrinsic Umklapp-limited thermal conductivity of graphene grows with the increasing dimensions of graphene flakes and can exceed that of bulk graphite when the flake size is on the order of a few micrometers. The detailed theory, which includes the phonon-mode-dependent Gruneisen parameter and takes into account phonon scattering on graphene edges and point defects, gives numerical results that are in excellent agreement with the measurements for suspended graphene. Superior thermal properties of graphene are beneficial for all proposed graphene device applications.

Ghosh, S.; Nika, D. L.; Pokatilov, E. P.; Balandin, A. A.

2009-09-01

209

Heat, Light, and Videotapes: Experiments in Heat Conduction Using Liquid Crystal Film.  

ERIC Educational Resources Information Center

Presents a range of experiments in heat conduction suitable for upper-level undergraduate laboratories that make use of heat sensitive liquid crystal film to measure temperature contours. Includes experiments mathematically described by Laplace's equation, experiments theoretically described by Poisson's equation, and experiments that involve…

Bacon, Michael E.; And Others

1995-01-01

210

Heat conductance is strongly anisotropic for pristine silicon nanowires.  

PubMed

We compute atomistically the heat conductance for ultrathin pristine silicon nanowires (SiNWs) with diameters ranging from 1 to 5 nm. The room temperature thermal conductance is found to be highly anisotropic: wires oriented along the <110> direction have 50-75% larger conductance than wires oriented along the <100> and <111> directions. We show that the anisotropies can be qualitatively understood and reproduced from the bulk phonon band structure. Ab initio density functional theory (DFT) is used to study the thinnest wires, but becomes computationally prohibitive for larger diameters, where we instead use the Tersoff empirical potential model (TEP). For the smallest wires, the thermal conductances obtained from DFT and TEP calculations agree within 10%. The presented results could be relevant for future phonon-engineering of nanowire devices. PMID:18811212

Markussen, Troels; Jauho, Antti-Pekka; Brandbyge, Mads

2008-11-01

211

Europeana and 3D  

NASA Astrophysics Data System (ADS)

The current 3D hype creates a lot of interest in 3D. People go to 3D movies, but are we ready to use 3D in our homes, in our offices, in our communication? Are we ready to deliver real 3D to a general public and use interactive 3D in a meaningful way to enjoy, learn, communicate? The CARARE project is realising this for the moment in the domain of monuments and archaeology, so that real 3D of archaeological sites and European monuments will be available to the general public by 2012. There are several aspects to this endeavour. First of all is the technical aspect of flawlessly delivering 3D content over all platforms and operating systems, without installing software. We have currently a working solution in PDF, but HTML5 will probably be the future. Secondly, there is still little knowledge on how to create 3D learning objects, 3D tourist information or 3D scholarly communication. We are still in a prototype phase when it comes to integrate 3D objects in physical or virtual museums. Nevertheless, Europeana has a tremendous potential as a multi-facetted virtual museum. Finally, 3D has a large potential to act as a hub of information, linking to related 2D imagery, texts, video, sound. We describe how to create such rich, explorable 3D objects that can be used intuitively by the generic Europeana user and what metadata is needed to support the semantic linking.

Pletinckx, D.

2011-09-01

212

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

213

An eigenvalue method for solving transient heat conduction problems  

NASA Technical Reports Server (NTRS)

The eigenvalue method, which has been used by researchers in structure mechanics, is applied to problems in heat conduction. Its formulation is decribed in terms of an examination of transient heat conduction in a square slab. Taking advantage of the availability of the exact solution, we compare the accuracy and other numerical properties of the eigenvalue method with those of existing numerical schemes. The comparsion shows that, overall, the eigenvalue method appears to be fairly attractive. Furthermore, only a few dominant eigenvalues and their corresponding eigenvectors need to be computed and retained to yield reasonably high accuracy. Greater savings are attained in the computation time for a transient problem with long time duration and a large computational domain.

Shih, T. M.; Skladany, J. T.

1983-01-01

214

Comparative evaluation of fuel element heat conduction models  

SciTech Connect

Computer codes that predict thermal-hydraulic performance in light water reactors are found to employ a variety of conduction heat transfer models for the determination of the temperature distribution within fuel elements. The objective of this study was to evaluate, in a consistent manner, the relative merits of these various fuel element conduction heat transfer models by comparing accuracy, speed, and computer storage requirements for calculations performed on selected reference or benchmark problems. Methods of particular interest include: (1) implicit finite difference method (FDM) in COBRA-IIIC; (2) weighted residuals method (WRM) in COBRA-IV; (3) nodal integral method (NIM) in TRAC-PF1; and (4) control volume method (CVM) in RELAP5/MOD1.

Panicker, M.; Dugan, E.T.; Anghaie, S.

1986-01-01

215

Development of a high performance variable conductance heat pipe  

NASA Astrophysics Data System (ADS)

An all stainless steel bendable gas controlled variable conductance heat pipe (VCHP) has been developed and submitted to adverse environments, including life test. The heat carrier is ammonia, the capillary system a homogeneous wick structure, temperature control involves a cold wicked reservoir. This design presents excellent potential for high performance since, within a one centimeter diameter tube, a heat transport capability of 100 watt metre has been demonstrated. Its performance does not degrade when control gas is added to the working fluid. The gas control was designed to achieve a 5 degree temperature range, which was finally demonstrated after improvement of the VCHP design. Environmental and life tests demonstrated the rugginess of the developed VCHP.

Mathieu, J.-P.; Moschetti, B.; Savage, C. J.

1980-07-01

216

Low-temperature specific heat and thermal conductivity of glycerol  

Microsoft Academic Search

We have measured the thermal conductivity of glassy glycerol between 1.5 and 100 K, as well as the specific heat of both glassy and crystalline phases of glycerol between 0.5 and 25 K. We discuss both low-temperature properties of this typical molecular glass in terms of the soft-potential model. Our finding of an excellent agreement between its predictions and experimental

C. Talón; Q. W. Zou; M. A. Ramos; R. Villar; S. Vieira

2002-01-01

217

Heating of foods in space-vehicle environments. [by conductive heat transfer  

NASA Technical Reports Server (NTRS)

In extended space missions, foods will be heated to enhance the psychological as well as the physiological well-being of the crew. In the low-gravity space environment natural convection is essentially absent so that the heat transfer within the food is by conduction alone. To prevent boiling in reduced pressure environments the maximum temperature of the heating system is severely limited. The Skylab food-heating system utilizes a tray with receptables for the food containers. The walls of the receptacles are lined with thermally controlled, electrical-resistance, blanket-type heating elements. A finite difference model is employed to perform parametric studies on the food-heating system. The effects on heating time of the (1) thermophysical properties of the food, (2) heater power level, (3) initial food temperatures, (4) container geometry, and (5) heater control temperature are presented graphically. The optimal heater power level and container geometry are determined.

Bannerot, R. B.; Cox, J. E.; Chen, C. K.; Heidelbaugh, N. D.

1973-01-01

218

Conjugate mixed convection-conduction heat transfer in porous media  

NASA Astrophysics Data System (ADS)

This dessertation studies analytically the conjugate mixed-convection conduction heat transfer in porous media. Solutions for mixed convection flows about vertical plate and cylindrical fins embedded in a porous medium have been obtained by including the effects of interactions between the conduction in the solid boundaries (fins) and the convection in the boundary layer. It has been found that the governing parameters are the Prandtl number Pr, buoyancy force parameter Omega, convection conduction parameter Ncc, and the surface curvature parameter lambda. Extensive results for heat transfer characteristics are presented graphically and in tabular forms for the following ranges of parameters: 0.05 or = Pr or = 7.5, 0.0 or = omega or = 20.0, 0.0 or = Ncc 2.0 and 0.5 or = lambda or = 5.0. Many results were found to have trends similar to those for classical fluids. In particular, the local heat transfer coefficients for mixed convection flows were found not to decrease monotonically as usual, but instead, the coefficients decreased first, attained a minimum value and then increased with increasing streamwise distance. This behavior is attributable to an enhanced buoyancy force resulting from an increase in the wall-to-fluid temperature difference along the streamwise direction.

Lin, J. Y.

1985-12-01

219

Thermal heat transport characterization for macroscale, microscale, and nanoscale heat conduction  

NASA Astrophysics Data System (ADS)

Several theoretical and experimental methods for predicting the thermal conductivity of thin dielectric films and carbon nanotubes are presented based on two schools of thought: (1) the physics of the Boltzmann Transport Equation (BTE), and (2) Molecular Dynamics (MD) simulations. First, in relation to models based on the BTE, this thesis highlights temporal and spatial scale issues by looking at a unified theory that bridges physical aspects presented in the Fourier and Cattaneo models. This newly developed unified model is the so called C- and F-Processes heat conduction model. The model introduces the dimensionless heat conduction model number which is the ratio of thermal conductivity of the fast heat carrier F-Processes to the total thermal conductivity comprised of both fast F-processes and slow heat carrier C-processes. Prior work has claimed that macroscopic heat transfer models cannot explain microscale heat transfer. First, this dissertation provides arguments by showing how the C-F model is able to extend the use of "macroscopic" constitutive relations for the prediction of thermal conductivity at the "microscopic" level for thin films, multilayer structures, and includes both dielectrics and metals. Second, the influence of external mechanical strain on the thermal conductivity of single-wall carbon nanotubes is studied using direct molecular dynamics simulations with Tersoff-Brenner potential for C-C interactions. Three types of external mechanical strain, namely, axial compression, tension, and torsion are studied. In all three cases, the thermal conductivity does not degrade much, i.e., it remains within 10% of the pristine nanotube values for lower applied strain below the values required for structural collapse. At higher applied strain, structural collapse occurs, and major reductions in the observed thermal conductivity for axially compressed and torsionally twisted tubes are observed.

Anderson, Christianne Vanessa Duim Ribeiro

220

Numerical simulation of hyperbolic heat conduction with convection boundary conditions and pulse heating effects  

NASA Technical Reports Server (NTRS)

The paper describes the numerical simulation of hyperbolic heat conduction with convection boundary conditions. The effects of a step heat loading, a sudden pulse heat loading, and an internal heat source are considered in conjunction with convection boundary conditions. Two methods of solution are presened for predicting the transient behavior of the propagating thermal disturbances. In the first method, MacCormack's predictor-corrector method is employed for integrating the hyperbolic system of equations. Next, the transfinite element method, which employs specially tailored elements, is used for accurately representing the transient response of the propagating thermal wave fronts. The agreement between the results of various numerical test cases validate the representative behavior of the thermal wave fronts. Both methods represent hyperbolic heat conduction behavior by effectively modeling the sharp discontinuities of the propagating thermal disturbances.

Glass, David E.; Tamma, Kumar K.; Railkar, Sudhir B.

1989-01-01

221

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.

222

3D photoacoustic imaging  

Microsoft Academic Search

Our group has concentrated on development of a 3D photoacoustic imaging system for biomedical imaging research. The technology employs a sparse parallel detection scheme and specialized reconstruction software to obtain 3D optical images using a single laser pulse. With the technology we have been able to capture 3D movies of translating point targets and rotating line targets. The current limitation

Jeffrey J. L. Carson; Michael Roumeliotis; Govind Chaudhary; Robert Z. Stodilka; Mark A. Anastasio

2010-01-01

223

Fabrication and test of a variable conductance heat pipe  

NASA Technical Reports Server (NTRS)

A variable conductance heat pipe (VCHP) with feedback control was fabricated with a reservoir-condenser volume ratio of 10 and an axially grooved action section. Tests of the heat transport capability were greater than or equal to the analytical predictions for the no gas case. When gas was added, the pipe performance degraded by 18% at zero tilt as was expected. The placement of the reservoir heater and the test fixture cooling fins are believed to have caused a superheated vapor condition in the reservoir. Erroneously high reservoir temperature indications resulted from this condition. The observed temperature gradients in the reservoir lend support to this theory. The net result was higher than predicted reservoir temperatures. Also, significant increases in minimum heat load resulted for controller set point temperatures higher than 0 C. At 30 C, control within the tolerance band was maintained, but high reservoir heater power was required. Analyses showed that control is not possible for reasonably low reservoir heater power. This is supported by the observation of a significant reservoir heat leak through the condenser.

Lehtinen, A. M.

1978-01-01

224

Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Technical Reports Server (NTRS)

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 turns on with a delta 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 delta T was roughly 70 C, due to distillation of the NaK in the evaporator.

Anderson, William G.; Tarau, Calin

2008-01-01

225

DSMC Convergence for Microscale Gas-Phase Heat Conduction  

NASA Astrophysics Data System (ADS)

The convergence of Bird's Direct Simulation Monte Carlo (DSMC) method is investigated for gas-phase heat conduction at typical microscale conditions. A hard-sphere gas is confined between two fully accommodating walls of unequal temperature. Simulations are performed for small system and local Knudsen numbers, so continuum flow exists outside the Knudsen layers. The ratio of the DSMC thermal conductivity to the Chapman-Enskog value in the central region is determined for over 200 combinations of time step, cell size, and number of computational molecules per cell. In the limit of vanishing error, this ratio approaches 1.000 to within the correlation uncertainty. In the limit of infinite computational molecules per cell, the difference from unity depends quadratically on time step and cell size as these quantities become small. The coefficients of these quadratic terms are in good agreement with Green-Kubo values found by Hadjiconstantinou, Garcia, and co-workers. These results demonstrate that DSMC can accurately simulate microscale gas-phase heat conduction. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Rader, D. J.; Gallis, M. A.; Torczynski, J. R.

2004-11-01

226

Numerical Model for Conduction-Cooled Current Lead Heat Loads  

SciTech Connect

Current leads are utilized to deliver electrical power from a room temperature junction mounted on the vacuum vessel to a superconducting magnet located within the vacuum space of a cryostat. There are many types of current leads used at laboratories throughout the world; however, conduction-cooled current leads are often chosen for their simplicity and reliability. Conduction-cooled leads have the advantage of using common materials, have no superconducting/normal state transition, and have no boil-off vapor to collect. This paper presents a numerical model for conduction-cooled current lead heat loads. This model takes into account varying material and fluid thermal properties, varying thicknesses along the length of the lead, heat transfer in the circumferential and longitudinal directions, electrical power dissipation, and the effect of thermal intercepts. The model is validated by comparing the numerical model results to ideal cases where analytical equations are valid. In addition, the XFEL (X-Ray Free Electron Laser) prototype current leads are modeled and compared to the experimental results from testing at DESY's XFEL Magnet Test Stand (XMTS) and Cryomodule Test Bench (CMTB).

White, M.J.; Wang, X.L.; /Fermilab; Brueck, H.D.; /DESY

2011-06-10

227

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

228

Specific heat and thermal conductivity of solid fullerenes  

NASA Astrophysics Data System (ADS)

Evidence is presented that the lattice vibrations of compacted C60/C70 fullerite microcrystals consist predominantly of localized modes. Vibrational motions of the rigid molecules ('buckyballs') have been identified as well as their internal vibrations. Debye waves play only a relatively minor role, except below about 4 K. By comparison with other crystalline materials, for these materials the Einstein model of the specific heat and thermal conductivity of solids, which is based on the assumption of atoms (in this case, buckyballs) vibrating with random phases, is in much better agreement with the measurements than the Debye model, which is based on collective excitations.

Olson, J. R.; Topp, K. A.; Pohl, R. O.

1993-02-01

229

Specific heat and thermal conductivity of solid fullerenes  

SciTech Connect

Evidence is presented that the lattice vibrations of compacted C[sub 60]/C[sub 70] fullerite microcrystals consist predominantly of localized modes. Vibrational motions of the rigid molecules (buckyballs) have been identified as well as their internal vibrations. Debye waves play only a relatively minor role, except below [approximately]4 kelvin. By comparison with other crystalline materials, for these materials the Einstein model of the specific heat and thermal conductivity of solids, which is based on the assumption of atoms (in this case, buckyballs) vibrating with random phases, is in much better agreement with the measurements than the Debye model, which is based on collective excitations.

Olson, J.R.; Topp, K.A.; Pohl, R.O. (Lab. of Atomic and Solid State Physics, Cornell Univ., Ithaca, NY (United States))

1993-02-19

230

Low-temperature specific heat and thermal conductivity of glycerol  

NASA Astrophysics Data System (ADS)

We have measured the thermal conductivity of glassy glycerol between 1.5 and 100 K, as well as the specific heat of both glassy and crystalline phases of glycerol between 0.5 and 25 K. We discuss both low-temperature properties of this typical molecular glass in terms of the soft-potential model. Our finding of an excellent agreement between its predictions and experimental data for these two independent measurements constitutes a robust proof of the capabilities of the soft-potential model to account for the low-temperature properties of glasses in a wide temperature range.

Talón, C.; Zou, Q. W.; Ramos, M. A.; Villar, R.; Vieira, S.

2002-01-01

231

A simple optical probe of transient heat conduction  

NASA Astrophysics Data System (ADS)

We use a laser beam and a stopwatch to investigate transient heat conduction in Plexiglas and glycerol samples chilled by ice water. The deflection of the laser beam is proportional to the thermal gradient in the sample. Measurements of the beam deflection allow us to calculate the thermal gradient as a function of time. Our empirical results fit the theoretical predictions very well and show an initial increase in the thermal gradient followed by a gradual decrease as the entire sample approaches the temperature of ice water. The procedure is simple and can be used as a lecture demonstration, an afternoon's experiment, or an extended investigation in an advanced laboratory course.

Brody, Jed; Andreae, Phillip; Robinson, C. Andrew

2010-05-01

232

Tunable single-photon heat conduction in electrical circuits  

NASA Astrophysics Data System (ADS)

We build on the study of single-photon heat conduction in electronic circuits taking into account the back-action of the superconductor-insulator-normal-metal thermometers. In addition, we show that placing capacitors, resistors, and superconducting quantum interference devices (SQUIDs) into a microwave cavity can severely distort the spatial current profile which, in general, should be accounted for in circuit design. The introduction of SQUIDs also allows for in situ tuning of the photonic power transfer which could be utilized in experiments on superconducting quantum bits.

Jones, P. J.; Huhtamäki, J. A. M.; Partanen, M.; Tan, K. Y.; Möttönen, M.

2012-07-01

233

Combined conduction and radiation heat transfer in concentric cylindrical media  

NASA Technical Reports Server (NTRS)

The exact radiative transfer expressions for gray and nongray gases which are absorbing, emitting and nonscattering, contained between infinitely long concentric cylinders with black surfaces, are given in local thermodynamic equilibrium. Resulting energy equations due to the combination of conduction and radiation modes of heat transfer, under steady state conditions for gray and nongray media, are solved numerically using the undetermined parameters method. A single 4.3-micron band of CO2 is considered for the nongray problems. The present solutions for gray and nongray gases obtained in the plane-parallel limit (radius ratio approaches to one) are compared with the plane-parallel results reported in the literature.

Pandey, D. K.

1987-01-01

234

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

235

Heat conduction across monolayer and few-layer graphenes.  

PubMed

We report the thermal conductance G of Au/Ti/graphene/SiO(2) interfaces (graphene layers 1 ? n ? 10) typical of graphene transistor contacts. We find G ? 25 MW m(-2) K(-1) at room temperature, four times smaller than the thermal conductance of a Au/Ti/SiO(2) interface, even when n = 1. We attribute this reduction to the thermal resistance of Au/Ti/graphene and graphene/SiO(2) interfaces acting in series. The temperature dependence of G from 50 ? T ? 500 K also indicates that heat is predominantly carried by phonons through these interfaces. Our findings suggest that metal contacts can limit not only electrical transport but also thermal dissipation from submicrometer graphene devices. PMID:20923234

Koh, Yee Kan; Bae, Myung-Ho; Cahill, David G; Pop, Eric

2010-11-10

236

Homogeneous Thermal Cloak with Constant Conductivity and Tunable Heat Localization  

PubMed Central

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

2013-01-01

237

Long life heat conductive body for utilization of solar heat energy and water heater for making use of same  

SciTech Connect

A heat conductive body for use in apparatus for the heating of liquid by way of solar radiation incident on the conductive body is formed of a mixture of sand iron with a fiber-reinforced formable plastic material. A heater apparatus uses the inventive conductive body for maintaining a supply of heated water.

Sakamoto, Y.

1983-01-18

238

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Technical Reports Server (NTRS)

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 convertor 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 convertor. 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.

2009-01-01

239

3D Model Retrieval  

Microsoft Academic Search

The topic of this paper is content-based retrieval of 3D models that are represented as triangle meshes. An object from some 3D geometry database can traditionally be accessed using attached structural information such as textual annotation. However, there are frequent requirements for a content-based retrieval of various multimedia contents. A content-based 3D model retrieval system has been implemented and this

D. Saupe

240

3D with Kinect  

Microsoft Academic Search

We analyze Kinect as a 3D measuring device, experimentally investigate depth measurement resolution and error properties and make a quantitative comparison of Kinect accuracy with stereo reconstruction from SLR cameras and a 3D-TOF camera. We propose Kinect geometrical model and its calibration procedure providing an accurate calibration of Kinect 3D measurement and Kinect cameras. We demonstrate the functionality of Kinect

Jan Smisek; Michal Jancosek; Tomas Pajdla

2011-01-01

241

Experience gained from using a computer program implementing the 3D zone-wise method for calculating heat transfer in the furnace chambers of the coal-fired boilers of 350- and 575-MW power units  

NASA Astrophysics Data System (ADS)

We describe the experience gained from more than 10 years of using the computer program imple-menting the 3D zone-wise method for calculating heat transfer in the furnace chambers of 350- and 575-MW power units installed at thermal power stations of Israel.

Karasina, E. S.; Livshits, B. N.; Chudnovskii, B. R.; Talanker, A. E.

2010-10-01

242

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

243

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

244

3D Shapes Video  

NSDL National Science Digital Library

This upbeat music video reviews 3D shapes including the sphere, cylinder, cube, and cone. As each 3D shape is presented, examples of things we see every day that have the same shape are also shown for reinforcement. (Length: 3:18)

Kindergarten, Harry

2011-06-17

245

3D Shape Synthesis.  

National Technical Information Service (NTIS)

We present a novel approach to 3D shape synthesis of closed surfaces. A curved or polyhedral 3D object of genus zero is represented by a curvature distribution on a spherical mesh that has nearly uniform distribution with known connectivity among mesh nod...

H. Y. Shum M. Hebert K. Ikeuchi

1995-01-01

246

3D Shape Similarity.  

National Technical Information Service (NTIS)

We study the 3D shape similarity between closed surfaces. We represent a curved or polyhedral 3D object of genus zero using a mesh representation that has nearly uniform distribution with known connectivity among mesh nodes. We define a shape similarity m...

H. Y. Shum M. Hebert K. Ikeuchi

1995-01-01

247

Cyberchase 3D Builder  

NSDL National Science Digital Library

This Cyberchase iOS geometry app ($) enables students to use 2D nets to create 3D shapes. The app includes eight levels which increase in difficulty; increasing the complexity of the nets and combining different 3D shapes together.

Kids, Pbs

2014-01-21

248

3D virtual colonoscopy  

Microsoft Academic Search

The authors present here a method called 3D virtual colonoscopy, which is an alternative method to existing procedures of imaging the mucosal surface of the colon. Using 3D reconstruction of helical CT data and volume visualization techniques, the authors generate images of the inner surface of the colon as if the viewer's eyes were inside the colon. They also create

Lichan Hong; Arie Kaufman; Yi-Chih Wei; Ajay Viswambharan; M. Wax; Zhengrong Liangs

1995-01-01

249

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

250

3D silicon detectors  

NASA Astrophysics Data System (ADS)

Significant process in 3D detectors has taken place since Sherwood parker proposed the 3D silicon detector in 1997. The 3D detector was conceived as a method to overcome the radiation induced reduction in carrier lifetime in heavily irradiated silicon detectors via the use of advanced MEMS device fabrication techniques. This paper reviews the state of the art in 3D detectors. Work performed within the major fabrication institutes will be discussed, including modifications to the original design to reduce complexity and increase device yield. Characterization of 3D detectors up to the maximum radiation fluence expected at the high luminosity LHC operation will be presented. Results from both strip and pixel devices will be shown using characterization methods that include 90-Sr betas, focused laser and high-energy pions.

Bates, R. L.

2012-08-01

251

Application of sensitivity coefficients for heat conduction problems  

SciTech Connect

In parameter estimation considerable insight is provided by examining sensitivity coefficients. This paper focuses on the use of sensitivity coefficients in connection with estimating thermal properties in the heat conduction equation. A general methodology for computing sensitivity coefficients can be an important design tool. The use of such a tool is demonstrated in this paper. A control volume, finite element program is used, and briefly described, to implement numerical sensitivity coefficient calculations. In this approach general problems can be studied. Several example problems are presented to demonstrate the insight gained from sensitivity coefficients. The problems are selected from experimental studies to characterize the thermal properties of carbon-carbon composite. Sensitivity coefficients show that in an experiment that is not well designed, additional materials in the experimental configuration can have a larger impact on the temperature than the material of interest. Two-dimensional configurations demonstrate that there can be isolated areas of insensitivity and the difficulty of estimating multiple parameters.

Dowding, K.J.; Blackwell, B.F.; Cochran, R.J.

1998-02-01

252

ICARUS: A general one-dimensional heat conduction code  

NASA Astrophysics Data System (ADS)

A computer code for calculating one dimensional planar, cylindrical or spherical conduction heat transfer is described. The model can account for material phase change (solidification or melting, multiple material regions, temperature dependent material properties and time or temperature dependent boundary conditions. Finite difference techniques are used to discretize the differential equations. The resulting system of tri-diagonal equations are solved using a standard tri-diagonal reduction method. The equations are formulated so that the solution can be fully implicit, fully explicit or a user specified degree of mix. Six sample problems that compare numerical predictions to analytical solutions are discussed. Operation of the computer code and all input variables are described. Input file listings and typical edits for the six sample problems are given.

Sutton, S. B.

1984-07-01

253

Application of the boundary element method to transient heat conduction  

NASA Technical Reports Server (NTRS)

An advanced boundary element method (BEM) is presented for the transient heat conduction analysis of engineering components. The numerical implementation necessarily includes higher-order conforming elements, self-adaptive integration and a multiregion capability. Planar, three-dimensional and axisymmetric analyses are all addressed with a consistent time-domain convolution approach, which completely eliminates the need for volume discretization for most practical analyses. The resulting general purpose algorithm establishes BEM as an attractive alternative to the more familiar finite difference and finite element methods for this class of problems. Several detailed numerical examples are included to emphasize the accuracy, stability and generality of the present BEM. Furthermore, a new efficient treatment is introduced for bodies with embedded holes. This development provides a powerful analytical tool for transient solutions of components, such as casting moulds and turbine blades, which are cumbersome to model when employing the conventional domain-based methods.

Dargush, G. F.; Banerjee, P. K.

1991-01-01

254

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

255

Efficient linear and nonlinear heat conduction with a quadrilateral element  

NASA Technical Reports Server (NTRS)

A method is presented for performing efficient and stable finite element calculations of heat conduction with quadrilaterals using one-point quadrature. The stability in space is obtained by using a stabilization matrix which is orthogonal to all linear fields and its magnitude is determined by a stabilization parameter. It is shown that the accuracy is almost independent of the value of the stabilization parameter over a wide range of values; in fact, the values 3, 2, and 1 for the normalized stabilization parameter lead to the 5-point, 9-point finite difference, and fully integrated finite element operators, respectively, for rectangular meshes and have identical rates of convergence in the L2 norm. Eigenvalues of the element matrices, which are needed for stability limits, are also given. Numerical applications are used to show that the method yields accurate solutions with large increases in efficiency, particularly in nonlinear problems.

Liu, W. K.; Belytschko, T.

1983-01-01

256

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

257

Incompressible Perturbations in Uniformally Stratified Viscous Heat-Conducting Fluid  

NASA Astrophysics Data System (ADS)

One-component model of dissipative medium with two-parametric equation of state allows us to formulate a simple model of a stratified viscous heat-conducting fluid. At local thermodynamic equilibrium description and the simplifying assumption of constancy of the kinetic coefficients the complete system of equations of a viscous fluid can be written in the form of the equations of conservation of mass, momentum balance, entropy balance and state equation. Consequence of the equation of state is a linear relationship between changes in density and changes in pressure and entropy. In the case of an incompressible fluid change in the density does not occur when the pressure changes. This corresponds to an infinite speed of sound. As a result, change in the density is proportional to the temperature change and thermal expansion coefficient. Accordingly, the velocity of fluid flow is not solenoidal. At the constant heat capacity the entropy balance equation reduces to the heat equation, which in turn takes the form of the evolution equation of the density. This equation completes the equation of conservation of mass and the equation of fluid motion. We assume that fluid flow occurs in the gravity field and is caused by small external forces, a small source of mass and small thermal source. Let the initial state of the fluid is rest with the vertical coordinate-dependent density distribution. For simplicity it is assumed also that the stratification is uniform, i.e. the buoyancy frequency is constant. Then the weak current caused by the sources will be described by the linearized equations with constant coefficients in Boussinesq approximation. In this approximation, square of buoyancy frequency, the density at a fixed level and the transport coefficients are the basic constant coefficients of the equations. Gravity selects the vertical direction, and therefore it is convenient to divide vector characteristics of the perturbation in the horizontal and vertical parts. In turn, the horizontal components of vectors is conveniently represented by pairs of scalar potentials using the Helmholtz decomposition. Taking into account these relations complete system of equations for small perturbations can be reduced to separate equations for the characteristics of the perturbations. As a result, small perturbations of density, pressure and vectors of velocity and vorticity can be expressed in the form of various derivatives of the five quasipotentials. Four of these quasipotentials obey the same equation of sixth order with the mass, force and heat sources, respectively, on the right side. The operator left-hand side of these equations reflects the behavior of internal waves, as well as viscous and thermal relaxation. In addition to the viscosity this operator includes the kinetic coefficient, which is directly proportional to the coefficient of thermal conductivity and is inversely proportional to the specific heat. In this case the vertical componen

Gorodtsov, V. A.

2012-04-01

258

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

259

Prolonged bone-conducted vibration in superior semicircular canal dehiscence and in otosclerosis: comparison of the 3D eye movement evaluation  

PubMed Central

Summary Vibration-induced nystagmus, as clinical sign, was recently introduced in outpatient clinical practice for the study and evaluation of otoneurological patients. This response, which can only be evoked by bone conducted vibratory stimulation in the mastoid region or at the location on the forehead in the midline at the hairline, was essentially designed for patients with persistent unilateral vestibular deficit and was interpreted as the result of excitatory functional activity of the vestibular system on the non-affected side. Vibratory stimulation is, in fact, considered to reach both systems, which in the case of functional asymmetry, respond asymmetrically with greater excitatory activation on the more responsive side. On the other hand, little information is available concerning vibration-induced nystagmus in subjects with symmetrical vestibular function. The limited experience with this recently proposed test and incomplete knowledge regarding its mechanisms suggest that it must be investigated in clinical conditions, having a known pathophysiological basis: the responses obtained could help provide insight into the potential of this test and contribute to the diagnostic definition of the superior semicircular canal dehiscence or otosclerosis. Analysis of Vibration-induced nystagmus, recently proposed to study transmission of excitatory stimuli by bone conduction, may be appropriate for altered input caused by defects of the labyrinthine capsule. This promises to be an interesting new field of research.

Manzari, L

2009-01-01

260

Cn3D  

NSDL National Science Digital Library

Introduction to Cn3D for retrieving and viewing individual biomolecular structures and structure alignments. Additional topics include sequence imports and conservation, annotating a structure, saving structures and images, and advanced topics.

National Center for Biotechnology Information (NCBI)

261

3D Plasmon Ruler  

SciTech Connect

In this animation of a 3D plasmon ruler, the plasmonic assembly acts as a transducer to deliver optical information about the structural dynamics of an attached protein. (courtesy of Paul Alivisatos group)

None

2011-01-01

262

The 3-D Universe  

NSDL National Science Digital Library

This Moveable Museum article, available as a printable PDF file, looks at how astronomers use data to create 3-D models of the universe. Explore these concepts further using the recommended resources mentioned in this reading selection.

263

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.

264

Underground heat conduction near a spherical inhomogeneity: theory and applications  

NASA Astrophysics Data System (ADS)

A large underground inhomogeneity, such as a salt dome or cavity, is known to disturb the subsurface temperature field. Such anomalies appear in many geophysical surveys. Detection and knowledge of the magnitude of these disturbances is the objective of both near surface and deep borehole temperature surveys aimed at delineating the inhomogeneities. It also impacts surface temperature history analysis which reconstructs past climate change in an effort to study the recent global warming. This work is aimed at quantifying these effects by solving a problem of heat conduction in Earth's subsurface in the presence of a spherical inhomogeneity. Both the steady state temperature field pertaining to the constant geothermal gradient and the time dependent field caused by a surface jump in temperature are solved. A solution is derived for both cases as an infinite series of spherical harmonics and Bessel functions (in the Laplace domain) for the steady and unsteady problems, respectively. It is shown that an accurate solution can be achieved by a small number of terms. The results are illustrated and analysed for a given accuracy and for a few values of the governing parameters. The general solution can be simplified considerably for asymptotic values of the parameters. Comparison with the exact solution shows that these approximations are accurate for a wide range of parameter values. Some examples of applying the solution to the geophysical methods stated above are discussed. In the case of surface temperature surveys, an example showing good agreement between theoretical and measured heat flux above a salt diapir is given. Though the sphere is an idealized shape, the simplicity of the solution makes possible a general analysis toward gaining a better understanding of the process. Furthermore, it can be employed for preliminary assessment of the impact of a body and may serve as a benchmark for numerical solutions.

Rabinovich, A.; Dagan, G.; Miloh, T.

2012-06-01

265

Heat transport by conduction in the deep mantle  

NASA Astrophysics Data System (ADS)

At high mantle temperatures, the phonon (vibrational or lattice) component of thermal diffusivity is independent of T. Laser flash measurements, which isolate phonon transport, of mineral families show that the complex silicates (olivines, orthopyroxenes, clinopyroxenes, garnets) have D asymptoting to 0.7 mm2/s whereas simple oxides (spinel, MgO, quartz) have slightly higher values of 1 to 1.5 mm2/s, such that the impurites lower Dsat. Values in the lower mantle are hence controlled by pressure. Multiple measurements of olivine and MgO give d(ln D)/dP near 3%/GPa which are compatible with the damped harmonic oscillator model. This model predicts d(ln D)/dP = 1.7%/GPa for incompressible phases like perovskite. Data and model constrain values of D and k = density X heat capacity X D for the lower mantle. High temperatures also provide radiative transfer, for which the strong dependence on temperature, Fe-content, and grain-size supercede its weak pressure dependence. However, the small expected grainsize of ca 1 mm makes scattering important and calculated values of krad are similar for olivine, perovskite and garnet, despite the variation in absorption spectra. Roughly, krad is 0.5 W/m-K in the lower mantle increasing to 3 W/m-K the lowest mantle (layer D"), which is dwarfed by 60 W/m-K for klat of a perovskite dominated lower mantle. Magnesiowustite, if present, would further increase klat. Thus layer D" can carry immense power (100 TW) over a steep temperature gradient (1000 K over 200 km) and 3 TW, which is a likely value for core production, over an adiabatic D" layer. Thus, the efficiency of phonons in diffusing heat allows the lower mantle to conduct: convection in the lower mantle is not likely, other than in the form of weak Hadley-type unicells.

Hofmeister, A. M.

2008-05-01

266

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

267

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

268

HEAT TRANSFER TO AN ELECTRICALLY CONDUCTING FLUID FLOWING IN A CHANNEL WITH A TRANSVERSE MAGNETIC FIELD  

Microsoft Academic Search

An analysis is made of forced-convection heat transfer to laminar flow ; of an incompressible electrically conducting fluid between parallel plates. The ; plates are heated (or cooled) with a uniform wall heat flux, and heating within ; the fluid is present from viscous and electrical dissipations. The fluid enters ; the heated section of the channel with a uniform

M. Perlmutter; R. Siegel

1961-01-01

269

3-D Simulations  

NSDL National Science Digital Library

Three-dimensional (3-D) rendering and animation technology is not only used for entertainment, but also for research and educational purposes. The technology can be used for purposes of scientific simulation in fields such as physics, biology, or chemistry. For example, Stanford University's Folding@home project (1) uses 3-D simulations and distributed computing to study protein folding, misfolding, aggregation, and related diseases. Three-D simulations can also be used to observe phenomena that would normally be impossible to scrutinize in detail, as is demonstrated on this website on Nanorobotics (2). This next website describes work by the Robotics Research Group (3) in using 3-D simulations to enhance undergraduate and graduate engineering education. The EdCenter (4) makes available several compressed files of 3-D simulations that model earthquake data, Mars, a San Diego Fly Through, and more. On this website (5 ), Martin Baker provides "all you need to know about 3D theory" and this website (6) provides access to a free open-source software package which "makes it easy to build 3-D simulations of decentralized systems and artificial life." This last article from Cyberbotics, Ltd. (7) discusses how mobile robotics simulation programs can be used to design robots.

270

3-D solar cells by electrochemical-deposited Se layer as extremely-thin absorber and hole conducting layer on nanocrystalline TiO2 electrode  

PubMed Central

A three-dimensional selenium solar cell with the structure of Au/Se/porous TiO2/compact TiO2/fluorine-doped tin oxide-coated glass plates was fabricated by an electrochemical deposition method of selenium, which can work for the extremely thin light absorber and the hole-conducting layer. The effect of experimental conditions, such as HCl and H2SeO3 in an electrochemical solution and TiO2 particle size of porous layers, was optimized. This kind of solar cell did not use any buffer layer between an n-type electrode (porous TiO2) and a p-type absorber layer (selenium). The crystallinity of the selenium after annealing at 200°C for 3 min in the air was significantly improved. The cells with a selenium layer deposited at concentrations of HCl?=?11.5 mM and H2SeO3?=?20 mM showed the best performance, resulting in 1- to 2-nm thickness of the Se layer, short-circuit photocurrent density of 8.7 mA/cm2, open-circuit voltage of 0.65 V, fill factor of 0.53, and conversion efficiency of 3.0%.

2013-01-01

271

3-D solar cells by electrochemical-deposited Se layer as extremely-thin absorber and hole conducting layer on nanocrystalline TiO2 electrode  

NASA Astrophysics Data System (ADS)

A three-dimensional selenium solar cell with the structure of Au/Se/porous TiO2/compact TiO2/fluorine-doped tin oxide-coated glass plates was fabricated by an electrochemical deposition method of selenium, which can work for the extremely thin light absorber and the hole-conducting layer. The effect of experimental conditions, such as HCl and H2SeO3 in an electrochemical solution and TiO2 particle size of porous layers, was optimized. This kind of solar cell did not use any buffer layer between an n-type electrode (porous TiO2) and a p-type absorber layer (selenium). The crystallinity of the selenium after annealing at 200°C for 3 min in the air was significantly improved. The cells with a selenium layer deposited at concentrations of HCl = 11.5 mM and H2SeO3 = 20 mM showed the best performance, resulting in 1- to 2-nm thickness of the Se layer, short-circuit photocurrent density of 8.7 mA/cm2, open-circuit voltage of 0.65 V, fill factor of 0.53, and conversion efficiency of 3.0%.

Nguyen, Duy-Cuong; Tanaka, Souichirou; Nishino, Hitoshi; Manabe, Kyohei; Ito, Seigo

2013-01-01

272

Systems analysis of the inverse heat conduction problem  

NASA Astrophysics Data System (ADS)

The groundwork necessary for frequency domain analysis of solutions to the inverse heat conduction problem, using Laplace and z-transform techniques is presented. The solution is traced back through the direct solution methods used to generate the inverse solution, and draws heavily upon tranfer function concepts. Transformation methods from continuous time ladder network models to discrete time models are developed. The mathematical relationship between ladder network models and finite difference models is derived. In addition, a new procedure for generating errorless discrete time models from Fourier series solutions is presented. The frequency response of direct discrete time solutions and the impact on the stability and noise performance of inverse algorithms arising from these direct solutions is presented. Inverse algorithm methods are generalized according to their frequency domain structure, rather than time domain, which effectively decouples the algorithm classification from a direct solution. Precompensation filter concepts are introduced, and a frequency domain test for inverse algorithm stability is developed. Examples of Stolz's method and Beck's method are included. Results are discussed.

Manner, David Bruce

273

Statistical analysis as approach to conductive heat transfer modelling  

NASA Astrophysics Data System (ADS)

The main inspiration for article was the problem of high investment into installation of the building insulation. The question of its effectiveness and reliability also after the period of 10 or 15 years was the topic of the international research project carried out at the University of Prešov in Prešov and Vienna University of Technology entitled "Detection and Management of Risk Processes in Building Insulation" and numbered SRDA SK-AT-0008-10. To detect especially the moisture problem as risk process in the space between the wall and insulation led to construction new measuring equipment to test the moisture and temperature without the insulation destruction and this way to describe real situation in old buildings too. The further investigation allowed us to analyse the range of data in the amount of 1680 measurements and express conductive heat transfer using the methods of statistical analysis. Modelling comprises relationships of the environment properties inside the building, in the space between the wall and insulation and in ambient surrounding of the building. Radial distribution function also characterizes the connection of the temperature differences.

Antonyová, A.; Antony, P.

2013-04-01

274

Theory and design of variable conductance heat pipes: Steady state and transient performance  

NASA Technical Reports Server (NTRS)

Heat pipe technology pertinent to the design and application of self-controlled, variable conductance heat pipes for spacecraft thermal control is discussed. Investigations were conducted to: (1) provide additional confidence in existing design tools, (2) to generate new design tools, and (3) to develop superior variable conductance heat pipe designs. A computer program for designing and predicting the performance of the heat pipe systems was developed.

Edwards, D. K.; Fleischman, G. L.; Marcus, B. D.

1972-01-01

275

D3-D research operations  

NASA Astrophysics Data System (ADS)

This paper discusses research at the D3-D tokamak reactor. The topics covered under the general heading of research program/scientific progress are: confinement, boundary physics, beta and stability, rf heating, and current drive. The operations section includes: tokamak operations, neutral beam operations, ECH/ICH operations, and shielding radiation studies. Program development focuses on: transport diagnostics, advanced divertor, 110 GHz ECH system, fast wave current drive, pellet injector. Collaborative work on D3-D and international cooperation are addressed and the following topics are covered under support services: quality assurance, planning and control, computer operations, and safety. ITER/CIT contributions are also covered and a list of FY89 publications is presented.

Politzer, P.

1990-04-01

276

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

277

First 3D Printout  

Microsoft Academic Search

\\u000a I didn’t want to keep you waiting for too long, so in this chapter you’ll print your first 3D model using the Shapeways Creator\\u000a and Co-Creator. “What? I thought this book was about using SketchUp to develop models for 3D printing!” Well, you aren’t done\\u000a with SketchUp yet. You’ll be learning how to develop custom models using SketchUp starting in

Sandeep Singh

278

A vectorized 3-D finite element model for transient simulation of two-phase heat transport with phase transformation and a moving interface  

Microsoft Academic Search

The implementation of a fully vectorized 3-D finite element model on the CRAY X-MP\\/Y-MP architecture is presented. Issues involved in vectorizing the computationally intensive modules of the finite element model are discussed. Fully vectorized numerical integration coupled with a preconditioned conjugate gradient linear system solver results in an application performance of 140 MFLOPS with the linear system solver achieving 162

Mark Christon

1990-01-01

279

Thermal management of 3D IC integration with TSV (through silicon via)  

Microsoft Academic Search

Thermal performances of 3D stacked TSV (through silicon via) chips filled with copper are investigated based on heat-transfer CFD (computational fluid dynamic) analyses. Emphases are placed on the determination of (1) empirical equations for the equivalent thermal conductive of chips with various copper-filled TSV diameters, pitches, and aspect ratios, (2) the junction temperature and thermal resistance of 3D stacking of

John H. Lau; Tang Gong Yue

2009-01-01

280

Heat flow in the laser-heated diamond anvil cell and the thermal conductivity of iron-bearing oxides and silicates at lower mantle pressures and temperatures  

NASA Astrophysics Data System (ADS)

The thermal conductivity of minerals in the lowermost mantle controls the total heat flow across the core-mantle boundary and is critical for the thermal evolution of the Earth. However, lower mantle thermal conductivity values and their pressure, temperature, and compositional dependencies are not well known. Here we present our recent progress combining 3D models of heat flow in the laser-heated diamond cell (LHDAC) with laboratory measurements of hotspot temperature distributions to assess the thermal conductivity of lower mantle minerals as a function of pressure and temperature. Using our numerical model of heat flow in the LHDAC, central hotspot temperature and radial and axial temperature gradients are calculated as a function of laser power, sample thermal conductivity, and sample geometry. For a given geometry, the relationship between peak sample temperature and laser power depends on the sample thermal conductivity. However, quantifying the experimental parameters sufficiently to precisely determine an absolute value of sample thermal conductivity is difficult. But relative differences in thermal conductivity are easily inferred by comparing the slopes of differing temperature vs. laser power curves measured on the same system. This technique can be used to measure the pressure dependence of thermal conductivity for minerals at lower mantle conditions. We confirm the effectiveness of this approach by measuring the pressure slope of thermal conductivity for MgO between 10 and 30 GPa. MgO retains the B1 phase throughout the experimental pressure range, and existing experimental measurements and theoretical calculations are in good agreement on the pressure- and temperature- dependence of the thermal conductivity of MgO. We also use this technique to measure the relative thermal conductivity of high pressure assemblages created from San Carlos olivine starting material. Both MgO and (Mg,Fe)2SiO4 materials show a shallower temperature vs. laser power slope as a function of pressure as expected for increasing thermal conductivity. In addition, olivine undergoes a series of phase transformations which changes its thermal behavior at upper mantle conditions (10-20 GPa) where olivine and wadsleyite are stable compared with lower mantle (25-30 GPa) conditions where the olivine transforms to a perovskite + oxide assemblage.

Rainey, E. S.; Kavner, A.; Hernlund, J. W.; Pilon, L.; Veitch, M.

2012-12-01

281

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

282

THERMIC: a 2-D finite-element tool to solve conductive and advective heat transfer problems in Earth Sciences  

NASA Astrophysics Data System (ADS)

We present a C-language program, THERMIC, that solves the 2-dimensional (pseudo 3D for axi-symmetric cases) conductive and advective heat-transfer equation. THERMIC uses a finite-element method that takes into account realistic geometries, heterogeneous material properties and various boundary and initial conditions. As it also allows for latent heat (heat production due to crystallisation) and for thermal properties, such as thermal conductivity, to be dependent on temperature, it is particularly suited to heat transfer problems encountered in the Earth Sciences. We present sample applications from the various problems already treated by THERMIC (cooling of magma chambers and dykes, the study of a granitic magma ascent or of pore water flow in sedimentary basins). Successfully tested on SUN® and SGI® UNIX workstations and on Microsoft Windows 95®, 98® and NT® 4.0 system based PCs, the THERMIC package can be downloaded from the web (THERMIC home page: http://www.ipgp.jussieu.fr/UFP/thermic/html/Thermic_home.html) and contains source files, makefiles and environment files as well as executable files for both systems and an html directory with help and example files.

Bonneville, Alain; Capolsini, Patrick

1999-12-01

283

Multiviewer 3D monitor  

Microsoft Academic Search

Physical Optics Corporation has developed an advanced 3-D virtual reality system for use with simulation tools for training technical and military personnel. This system avoids such drawbacks of other virtual reality (VR) systems as eye fatigue, headaches, and alignment for each viewer, all of which are due to the need to wear special VR goggles. The new system is based

Andrew A. Kostrzewski; Tin M. Aye; Dai Hyun Kim; Vladimir Esterkin; Gajendra D. Savant

1998-01-01

284

3D Shape Match  

NSDL National Science Digital Library

This interactive Flash applet provides a Concentration-type game (called pelmanism in the UK) in which students must discern the properties of three-dimensional solids and their colors in order to match them in pairs. Spheres, cones, prisms and other standard 3-D shapes are hidden face down on cards. Time and number of trials needed to solve are recorded.

Bunker, Dan

2011-01-01

285

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

286

The Effects of Axial Conduction in the Wall on Heat Transfer with Laminar Flow.  

National Technical Information Service (NTIS)

Wall conduction effects on steady-state laminar flow heat-transfer experiments are examined, and an analysis of heat transfer with axial conduction in the wall bounding a fluid in laminar flow is developed to determine the effects of the conduction in the...

E. J. Davis W. N. Gill

1969-01-01

287

Nongrey Radiant Heat Transfer Corrections to Thermal Conductivity Measurements.  

National Technical Information Service (NTIS)

A numerical investigation is presented to determine the influence of radiative transfer on experimental thermal conductivity measurements. The analysis is simplified by approximating the thermal conductivity test cell configuration by a parallel plate mod...

R. J. Latko W. Leidenfrost

1969-01-01

288

Multi-mode opto-thermo-mechanical stretching system for determination of 3D refractive index along the axis of stretched and/or heated fibres  

NASA Astrophysics Data System (ADS)

A multi-mode opto-thermo-mechanical stretching system was modified to study the changes in the 3D of optical and structural properties of stretched fibre along its axis. The structural deformation of isotactic Polypropylene, (iPP), fibres was studied at different draw ratios. The modified system coupled with Pluta polarising interference microscope was used to determine the variation of the birefringence in three dimensions during stretching process. Using this modified system, the multi-necking was detected. Subfringe analysis technique was used to determine the phase distribution of the obtained microinterferograms, which were given for illustration.

Sokkar, T. Z. N.; El-Tonsy, M. M.; El-Morsy, M. A.; El-Khateep, S. M.; Raslan, M. I.

2011-10-01

289

SPH Numerical Modeling for Ballistic-Diffusive Heat Conduction  

Microsoft Academic Search

The classic Fourier heat diffusion theory, in general, does not apply to micro\\/nanoscale or ultrafast thermal processes, where the mean free path of the heat carriers is comparable to the system size and\\/or typical times are comparable to the carrier relaxation time. For these processes, the ballistic-diffusive equation is a good alternative. In this context, the smoothed particle hydrodynamics (SPH)

Fangming Jiang; Antonio C. M. Sousa

2006-01-01

290

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

291

An analysis of the vapor flow and the heat conduction through the liquid-wick and pipe wall in a heat pipe with single or multiple heat sources  

Microsoft Academic Search

A numerical analysis is presented for the overall performance of heat pipes with single or multiple heat sources. The analysis includes the heat conduction in the wall and liquid-wick regions as well as the compressibility effect of the vapor inside the heat pipe. The two-dimensional elliptic governing equations in conjunction with the thermodynamic equilibrium relation and appropriate boundary conditions are

Ming-Ming Chen; Amir Faghri

1990-01-01

292

Electrical Conductivity Beneath the Payún Matrú Volcanic Field in the Andean Back-arc of Argentina near 36.5S: Insights into the Magma Source and Results of 3D Modeling  

NASA Astrophysics Data System (ADS)

Southern Mendoza and northern Neuquen Provinces, south of the Nazca flat slab in western Argentina, have widespread, geologically young basaltic volcanism, but no historic activity. The youngest basalts, erupted in the vicinity of the large Payún Matrú volcanic center have essentially no arc signature. Kay, et al. (2006) and Folguera, et al. (2006) argue that this back-arc igneous province is the result of extension due to trench roll-back following steepening of a flat slab that existed in the middle to late Miocene. Magnetotelluric data collected in 2005 at 18 sites along an east-west profile from 70W to 67W have been used to probe the source of the Payún Matrú basalts. These data imply significantly 3D structure. However, preliminary analysis of an arguably 2D region at the center of the profile allows tentative identification of a conductive mantle plume surfacing at Payún Matrú that rises from below 200 km depth. This suggests that Payún Matrú Volcanic Field is sampling mantle deeper than 200 km, perhaps just above the subducted Nazca slab or perhaps from the mantle transition near where the Nazca slab penetrates into it at 400 km. The 2008 fieldwork extends the earlier profile to a spatial array extending from Laguna Llancanelo north of Payún Matrú to beyond the Cortaderas Lineament that bounds the basaltic province to the south. These 19 new sites consist of 5 to 10 days of 4 Hz horizontal electric and 3-component magnetic field time- series. Data processing in the field suggests that the deep crust or upper mantle has northwest-southeast striking structure increases in conductivity to the southwest of Payún Matrú. This underlies shallow structure with north-south strike between Payún Matrú and the Colorado River. This complexity explains our initial difficulty with 2D interpretation. We will display a preliminary 3D interpretation of these new data.

Burd, A.; Booker, J.; Larsen, J.; Pomposiello, C.; Favetto, A.

2008-12-01

293

Smithsonian X 3D  

NSDL National Science Digital Library

Would you like to explore a wooly mammoth skeleton in great detail? How about some ceremonial masks created by Pacific Northwest Native Americans? The Smithsonian X 3D project makes all of this possible for visitors from all over the world. This site was created by the Smithsonian's Digitization Program Office and currently visitors can examine twelve digitized models, including a fossilized dolphin skull and the gun of noted explorer, David Livingston. The Video Gallery is a great addition as it contains short films that discuss the project's conservation work, along with a great film titled "What is 3D digitization?" Moving on, the Educators area contains a wonderful set of classroom resources that can be used in conjunction with some of the objects. Finally, the Tours area contains dozens of short films demonstrating these objects, including Seeing Around the Remnant of a Supernova, and Carving and Painting the Cosmic Buddha.

294

3-D Grab!  

NASA Astrophysics Data System (ADS)

Modern technologies in imaging greatly extend the potential to present visual information. With recently developed software tools, the perception of the third dimension can not only dramatically enhance presentation, but also allow spatial data to be better encoded. 3-D images can be taken for many subjects with only one camera, carefully moved to generate a stereo pair. Color anaglyph viewing now can be very effective using computer screens, and active filter technologies can enhance visual effects with ever-decreasing cost. We will present various novel results of 3-D imaging, including those from the auroral observations of the new twinned Athabasca University Geophysical Observatories.; Single camera stereo image for viewing with red/cyan glasses.

Connors, M. G.; Schofield, I. S.

2012-12-01

295

Calc3D Pro  

NSDL National Science Digital Library

The calculator can do statistics, best fits, function plotting, integration. It handles vectors, matrices, complex numbers, quaternions, coordinates, regular polygons and intersections. For point, line, plane, sphere, circle Calc 3D calculates distances, intersections, and some additional information like volume and area. Cartesian, spherical and cylindrical coordinates can be transformed into each other. Carthesian plot, polar plot, parametric plot, best fit, fast fourier transformation, histogram, smooth, and others.

296

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

297

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

298

Steady heat conduction-based thermal conductivity measurement of single walled carbon nanotubes thin film using a micropipette thermal sensor.  

PubMed

In this paper, we describe the thermal conductivity measurement of single-walled carbon nanotubes thin film using a laser point source-based steady state heat conduction method. A high precision micropipette thermal sensor fabricated with a sensing tip size varying from 2 ?m to 5 ?m and capable of measuring thermal fluctuation with resolution of ±0.01 K was used to measure the temperature gradient across the suspended carbon nanotubes (CNT) film with a thickness of 100 nm. We used a steady heat conduction model to correlate the temperature gradient to the thermal conductivity of the film. We measured the average thermal conductivity of CNT film as 74.3 ± 7.9 W m(-1) K(-1) at room temperature. PMID:23556837

Shrestha, R; Lee, K M; Chang, W S; Kim, D S; Rhee, G H; Choi, T Y

2013-03-01

299

The program FANS-3D (finite analytic numerical simulation 3-dimensional) and its applications  

NASA Technical Reports Server (NTRS)

In this study, the program named FANS-3D (Finite Analytic Numerical Simulation-3 Dimensional) is presented. FANS-3D was designed to solve problems of incompressible fluid flow and combined modes of heat transfer. It solves problems with conduction and convection modes of heat transfer in laminar flow, with provisions for radiation and turbulent flows. It can solve singular or conjugate modes of heat transfer. It also solves problems in natural convection, using the Boussinesq approximation. FANS-3D was designed to solve heat transfer problems inside one, two and three dimensional geometries that can be represented by orthogonal planes in a Cartesian coordinate system. It can solve internal and external flows using appropriate boundary conditions such as symmetric, periodic and user specified.

Bravo, Ramiro H.; Chen, Ching-Jen

1992-01-01

300

Constant of thermal heat conduction and stabilization of the bus bar conductor for superconducting accelerators  

SciTech Connect

Using the one-dimensional, time-independent conduction state, a constant of thermal heating conduction is given that brings about the known stabilization theorem and a closed expression for the bus bar to be cryogenically stable in superconducting accelerators.

Lopez, G.

1993-07-01

301

3d And 2d Automatic Inverse Modelling Of Sedimentary Basin Formation  

NASA Astrophysics Data System (ADS)

We present 3D and 2D forward models (TECMOD2D and 3D), which numerically simulate sedimentary basin formation and are coupled with automatic inversion algo- rithms. The forward models are based on depth-dependent kinematic stretching and/or asymmetric extension along faults. The inversion algorithm iteratively finds the opti- mal set of thinning factors or fault offsets (which fit any observed basin stratigraphy best) in such a way that symmetric versus asymmetric mode of extension is not as- sumed a priori. The inversion algorithms are able to fit thinning factors that corre- spond to multiple, finite rifting events. The 2D inversion algorithms generally find the optimal set of thinning factors within 10 to 20 iterations for given initial condi- tions. For 3D applications, the inversion algorithm has to fit the horizontal stretching direction in addition to the thinning factors. Necessary modifications of the 2D inver- sion algorithms for 3D applications are discussed. The 3D forward model includes the effects of finite rift duration, thermal sediment blanketing, sediment compaction, radiogenic heat production, lateral heat conduction and advection, flexural isostasy and depth of necking. The 2D model additionally includes faulting and new oceanic crust formation. A 3D forward run with a numerical resolution of 41x41x51 nodes and 28 time steps takes around 15 minutes on a standard PC (1.3 GHz). The influ- ence of finite rift duration, thermal sediment blanketing and lateral heat conduction on the basin subsidence is evaluated. The coupled forward/inverse models are applied to restore the palaeo heat flow at the basement-sediment contact using observed basin stratigraphies. The effects of thermal sediment blanketing and lateral heat conduction in combination with radiogenic heat production are shown to strongly influence the palaeo heat flow reconstructions.

Schmalholz, S. M.; Podladchikov, Yu. Yu.; Schmid, D.; Kaus, B. J. P.

302

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

2013-01-01

303

Glass-Like Heat Conduction in Crystalline Semiconductors  

SciTech Connect

The thermal conductivity and structural properties of polycrystalline and single crystal semiconductor type-1 germanium clathrates are reported. Germanium clathrates exhibit thermal conductivities that are typical of amorphous materials. This behavior occurs in spite of their well-defined crystalline structure. The authors employ temperature dependent neutron diffraction data in investigating the displacements of the caged strontium atoms in Sr{sub 8}Ga{sub 16}Ge{sub 30} and their interaction with the polyhedral cages that entrap them. Their aim is to investigate the correlation between the structural properties and the low, glass-like thermal conductivity observed in this compound.

Nolas, G.S.; Cohn, J.L.; Chakoumakos, B.C.; Slack, G.A.

1999-06-13

304

A two-fluid model for relativistic heat conduction  

NASA Astrophysics Data System (ADS)

Three years ago it was presented in these proceedings the relativistic dynamics of a multi-fluid system together with various applications to a set of topical problems [1]. In this talk, I will start from such dynamics and present a covariant formulation of relativistic thermodynamics which provides us with a causal constitutive equation for the propagation of heat in a relativistic setting.

López-Monsalvo, César S.

2014-01-01

305

Approximate Method of Solving Nonlinear Heat Conduction Problems.  

National Technical Information Service (NTIS)

A method of solving nonlinear problems of high-temperature heat transfer is presented; it is based on the linearization of the basic process equation, starting from the condition of minimum rms error due to violating nonlinearity; in this, the nonlinear b...

V. V. Salomatov

1973-01-01

306

Software quality assurance plan for PORFLOW-3D.  

National Technical Information Service (NTIS)

This plan describes the steps taken by the Idaho National Engineering Laboratory Subsurface and Environmental Modeling Unit personnel to implement software quality assurance procedures for the PORFLOW-3D computer code. PORFLOW-3D was used to conduct radio...

S. J. Maheras

1993-01-01

307

3D Audio System  

NASA Technical Reports Server (NTRS)

Ames Research Center research into virtual reality led to the development of the Convolvotron, a high speed digital audio processing system that delivers three-dimensional sound over headphones. It consists of a two-card set designed for use with a personal computer. The Convolvotron's primary application is presentation of 3D audio signals over headphones. Four independent sound sources are filtered with large time-varying filters that compensate for motion. The perceived location of the sound remains constant. Possible applications are in air traffic control towers or airplane cockpits, hearing and perception research and virtual reality development.

1992-01-01

308

Twin Peaks - 3D  

NASA Technical Reports Server (NTRS)

The two hills in the distance, approximately one to two kilometers away, have been dubbed the 'Twin Peaks' and are of great interest to Pathfinder scientists as objects of future study. 3D glasses are necessary to identify surface detail. The white areas on the left hill, called the 'Ski Run' by scientists, may have been formed by hydrologic processes.

The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.

Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

1997-01-01

309

3D-Imaging  

NASA Astrophysics Data System (ADS)

Trotz steigender Verkehrsdichte ist die Zahl der Verkehrsunfälle mit Personenschäden in den letzten Jahren gesunken. Um zukünftige Fahrzeuge sowohl für die Insassen als auch für andere Verkehrsteilnehmer noch sicherer zu machen, wird eine zuneh-mend dreidimensionale Umfelderfassung durch das Fahrzeug notwendig. Eine entsprechende 3D-Sen-sorik ist in der Lage, gefährliche Situationen vorausschauend zu erkennen, den Fahrer bestmöglich zu unterstützen und somit Unfälle zu vermeiden. Aber auch im Falle eines nicht mehr zu vermeidenden Unfalls lässt sich das Verletzungsrisiko für alle Beteiligten minimieren.

Buxbaum, Bernd; Lange, Robert; Ringbeck, Thorsten

310

3D Face Recognition  

Microsoft Academic Search

\\u000a Three-dimensional human facial surface information is a powerful biometric modality that has potential to improve the identification\\u000a and\\/or verification accuracy of face recognition systems under challenging situations. In the presence of illumination, expression\\u000a and pose variations, traditional 2D image-based face recognition algorithms usually encounter problems. With the availability\\u000a of three-dimensional (3D) facial shape information, which is inherently insensitive to illumination

Berk Gökberk; Albert Ali Salah; Lale Akarun; Remy Etheve; Daniel Riccio; Jean-Luc Dugelay; D. Petrovska-Delacrètaz; G. Chollet; B. Dorizzi

2008-01-01

311

3D Modeling  

Microsoft Academic Search

\\u000a Blender (GNU\\/Linux, Windows, Mac) is a Free Software 3D graphics program with animation, video compositing, and game creation\\u000a features. This program is also available on two UNIX platforms: SGI Irix, which was popular for high-end graphics work before\\u000a the GNU\\/Linux desktop came along, and Sun Solaris. On Ubuntu, you can install Blender using the Add\\/Remove Applications tool.\\u000a Other GNU\\/Linux distributions

Daniel James

312

Experimental study on subcooled flow boiling on heating surfaces with different thermal conductivities  

NASA Astrophysics Data System (ADS)

Subcooled flow boiling is generally characterized by high heat transfer capacity and low wall superheat, which is essential for cooling applications requiring high heat transfer rate, such as nuclear reactors and fossil boilers. In this study, subcooled flow boiling on copper and stainless steel heating surfaces was experimentally investigated from both macroscopic and microscopic points of view. Flow boiling heat flux and heat transfer coefficient were experimentally measured on both surfaces under different conditions, such as pressure, flow rate and inlet subcooling. Significant boiling heat transfer coefficient differences were found between the copper and the stainless steel heating surfaces. To explain the different flow boiling behaviors on these two heating surfaces, nucleation site density and bubble dynamics were visually observed and measured at different experimental conditions utilizing a high-speed digital video camera. These two parameters are believed to be keys in determining flow boiling heat flux. Wall superheat, critical cavity size and wall heat flux were used to correlate with nucleation site density data. Among them, wall heat flux shows the best correlation for eliminating both pressure and surface property effects. The observed nucleation site distribution shows a random distribution. When compared to the spatial Poisson distribution, similarity between them was found, while the measured nucleation site distribution is more uniform. From experimental observations, for the two surface materials investigated, which have similar surface wettability but sharply different thermal properties, bubble dynamics displayed fairly similar behavior. The obtained experimental results indicate that thermal conductivity of heating surface material plays an important role in boiling heat transfer. This is due to thermal conductivity having a significant impact on the lateral heat conduction at the heating surface and consequently temperature uniformity of the heating surface. A model was then developed and solved numerically for heat conduction at the heating surface when bubbles are present. Several key parameters which impact lateral heat conduction and surface temperature profile were studied. These parameters include material thermal conductivity, bubble size, heating surface thickness, etc. Numerical results show that, temperature profile on the heating surface tends to be more uniform and have a lower average value on a heating surface with higher thermal conductivity, which agrees well with the experimental observation.

Zou, Ling

313

On the heat conduction problem and a design principle for plasma arc furnace  

Microsoft Academic Search

In this paper a plane heat conduction problem with variable coefficients of heat conductivity K(T) is analysed with given electric power supplied to the plasma arc. The governing equation for unknown temperature distribution is a nonlinear one with a ? function as its nonhomogeneous term. To make the problem attractable by the method of separation of variables, a set of

Rong Sheng

1984-01-01

314

A new stochastic approach to transient heat conduction modeling with uncertainty  

Microsoft Academic Search

We present a generalized polynomial chaos algorithm for the solution of transient heat conduction subject to uncertain inputs, i.e. random heat conductivity and capacity. The stochastic input and solution are represented spectrally by the orthogonal polynomial functionals from the Askey scheme, as a generalization of the original polynomial chaos idea of Wiener [Am. J. Math. 60 (1938) 897]. A Galerkin

Dongbin Xiu; George Em Karniadakis

2003-01-01

315

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

316

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 simultaneously…

Wadso, Lars; Li, Xi.

2008-01-01

317

Heat Transfer with Axial Conduction in Triangular Ducts Filled with Saturated Porous Materials  

Microsoft Academic Search

The study reports the contribution of axial conduction in heat transfer to flow passing through triangular porous passages. The problem under consideration uses the H2 boundary condition; that is, locally constant wall heat flux. Because of the geometrical asymmetry, nonorthogonal boundary conditions can exist and this makes the determination of heat transfer more demanding. The porous medium is fully saturated

Abhishek Banerjee; A. Haji-Sheikh; Seiichi Nomura

2012-01-01

318

Heat conduction in cooling flows. [in clusters of galaxies  

NASA Technical Reports Server (NTRS)

It has been suggested that electron conduction may significantly reduce the accretion rate (and star foramtion rate) for cooling flows in clusters of galaxies. A numerical hydrodynamics code was used to investigate the time behavior of cooling flows with conduction. The usual conduction coefficient is modified by an efficiency factor, mu, to realize the effects of tangled magnetic field lines. Two classes of models are considered, one where mu is independent of position and time, and one where inflow stretches the field lines and changes mu. In both cases, there is only a narrow range of initial conditions for mu in which the cluster accretion rate is reduced while a significant temperature gradient occurs. In the first case, no steady solution exists in which both conditions are met. In the second case, steady state solutions occur in which both conditions are met, but only for a narrow range of initial values where mu = 0.001.

Bregman, Joel N.; David, L. P.

1988-01-01

319

Canvas 3D JS library  

Microsoft Academic Search

Web browsers do not have a standard method of creating\\/delivering 3D content. The Canvas 3D add-on for Firefox 3, which will become part of the browser in a future release, allows the delivery of 3D content via the canvas element. However, 3D is a complex problem. This paper proposes a library built on top of the Canvas 3D that will

Catherine Leung; Andor Salga; Andrew Smith

2008-01-01

320

3D video performance segmentation  

Microsoft Academic Search

We present a novel approach that achieves segmentation of subject body parts in 3D videos. 3D video consists in a free-viewpoint video of real-world subjects in motion immersed in a virtual world. Each 3D video frame is composed of one or several 3D models. A topology dictionary is used to cluster 3D video sequences with respect to the model topology

Tony Tung; Takashi Matsuyama

2010-01-01

321

3D molecular interconnection technology  

NASA Astrophysics Data System (ADS)

For the functional modeling of complex biological processing structures with high-density 3D connections (such as the visual cortex), we propose a simple multi-chip stack structure, with through-chip connections and molecular wires between the layers. We have designed and fabricated a two-chip stack, and molecular wiring materials have been examined: chemically and electrochemically grown conductive polymers. The next experimental stage will be to fabricate a three-chip stack. We have calculated the rate at which electrical signals can be transmitted through the layer and down a molecular wire. The measured values of conductivity for the polymer-based wires lie in the range sigma = 1 - 100 S m-1, which would allow bandwidths up to 100 Mbits s-1 per connection.

Crawley, D.; Nikolic, K.; Forshaw, M.; Ackermann, J.; Videlot, C.; Nguyen, T. N.; Wang, L.; Sarro, P. M.

2003-09-01

322

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

NASA Technical Reports Server (NTRS)

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

Brandon, S.; Derby, J. J.

1992-01-01

323

Bem Solution to Transient Free Convective Heat Transfer in a Viscous, Electrically Conducting, and Heat Generating Fluid  

Microsoft Academic Search

The nonlinear partial differential equations for the transient free convective heat transfer in a viscous, electrically conducting, and heat-generating fluid past a vertical porous plate in the presence of free stream oscillations are solved by the boundary element method (BEM). Time-dependent fundamental solutions are employed in a time marching scheme to resolve the field variables. Numerical results are compared with

K. Vajravelu; A. Kassab; A. Hadjinicolaou

1996-01-01

324

DYNAMIC RESPONSE OF A ROD DUE TO A MOVING HEAT SOURCE UNDER THE HYPERBOLIC HEAT CONDUCTION MODEL  

Microsoft Academic Search

The dynamic thermal and elastic behavior of a rod due to a moving heat source are investigated. The hyperbolic heat conduction model is used for the prediction of the temperature history. Thermally induced displacements and stresses are determined. An analytical–numerical technique based on the Laplace transformation and the Riemann-sum approximation is used to calculate the temperature, displacement and stress distributions

N. S. AL-HUNITI; M. A. AL-NIMR; M. NAJI

2001-01-01

325

A new angular discretization scheme of the finite volume method for 3-D radiative heat transfer in absorbing, emitting and anisotropically scattering media  

Microsoft Academic Search

This paper presents a new angular discretization scheme, FTn, of the finite volume method (FVM) in three-dimensional radiative heat transfer. The FTn FVM is applied to absorbing, emitting and anisotropically scattering media with variable optical thickness in a rectangular enclosure. Results show that the FTn FVM performs better than the discrete ordinate method (DOM) and the FVM with N?×N? uniform

Seung Hyun Kim; Kang Y. Huh

2000-01-01

326

3D analysis and calculation of stator temperature field of hydrogenerator in the case of sudden short circuit  

Microsoft Academic Search

Sudden short circuit is a serious transient process though it is short in time. In this paper, 3D transient equations of heat conduction as well as its equivalent functional equation are presented. Short circuit current of stator is performed. Sudden short current and heat of the stator are analyzed and calculated. Base on the construction symmetry of ventilating system in

Fan Yadong; Wen Xishan; Xu Shaohua; Deng Wei

2006-01-01

327

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

328

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.

329

The psychology of the 3D experience  

NASA Astrophysics Data System (ADS)

With 3D televisions expected to reach 50% home saturation as early as 2016, understanding the psychological mechanisms underlying the user response to 3D technology is critical for content providers, educators and academics. Unfortunately, research examining the effects of 3D technology has not kept pace with the technology's rapid adoption, resulting in large-scale use of a technology about which very little is actually known. Recognizing this need for new research, we conducted a series of studies measuring and comparing many of the variables and processes underlying both 2D and 3D media experiences. In our first study, we found narratives within primetime dramas had the power to shift viewer attitudes in both 2D and 3D settings. However, we found no difference in persuasive power between 2D and 3D content. We contend this lack of effect was the result of poor conversion quality and the unique demands of 3D production. In our second study, we found 3D technology significantly increased enjoyment when viewing sports content, yet offered no added enjoyment when viewing a movie trailer. The enhanced enjoyment of the sports content was shown to be the result of heightened emotional arousal and attention in the 3D condition. We believe the lack of effect found for the movie trailer may be genre-related. In our final study, we found 3D technology significantly enhanced enjoyment of two video games from different genres. The added enjoyment was found to be the result of an increased sense of presence.

Janicke, Sophie H.; Ellis, Andrew

2013-03-01

330

Symmetry analysis of a heat conduction model for heat transfer in a longitudinal rectangular fin of a heterogeneous material  

NASA Astrophysics Data System (ADS)

We consider a heat conduction model arising in transient heat transfer through longitudinal fins of a heterogeneous (functionally graded) material. In this case, the thermal conductivity depends on the spatial variable. The heat transfer coefficient depends on the temperature and is given by the power law function. The resulting nonlinear partial differential equation is analyzed using both classical and nonclassical symmetry techniques. Both the transient state and the steady state result in a number of exotic symmetries being admitted by the governing equation. Furthermore, nonclassical symmetries are also admitted. Both classical and nonclassical symmetry analysis results in some useful reductions and some remarkable exact solutions are constructed.

Moitsheki, Raseelo J.; Bradshaw-Hajek, Bronwyn H.

2013-09-01

331

Specially tailored transfinite-element formulations for hyperbolic heat conduction involving non-Fourier effects  

NASA Technical Reports Server (NTRS)

The phenomenon of hyperbolic heat conduction in contrast to the classical (parabolic) form of Fourier heat conduction involves thermal energy transport that propagates only at finite speeds, as opposed to an infinite speed of thermal energy transport. To accommodate the finite speed of thermal wave propagation, a more precise form of heat flux law is involved, thereby modifying the heat flux originally postulated in the classical theory of heat conduction. As a consequence, for hyperbolic heat conduction problems, the thermal energy propagates with very sharp discontinuities at the wave front. Accurate solutions are found for a class of one-dimensional hyperbolic heat conduction problems involving non-Fourier effects that can be used effectively for representative benchmark tests and for validating alternate schemes. Modeling/analysis formulations via specially tailored hybrid computations are provided for accurately modeling the sharp discontinuities of the propagating thermal wave front. Comparative numerical test models are presented for various hyperbolic heat conduction models involving non-Fourier effects to demonstrate the present formulations.

Tamma, Kumar K.; Railkar, Sudhir B.

1989-01-01

332

Numerical simulation of heat conduction in a random ballistic deposited grain aggregate  

NASA Astrophysics Data System (ADS)

A numerical simulation of heat conduction in a grain aggregate is carried out to determine the packing fraction (the spatial fraction occupied by grains or 1-porosity) dependence of the thermal conductivity of the aggregate. Arrangements of grains are given by random ballistic deposition. It is found that the packing fraction dependence is well approximated by an exponential function. The number of contacts between grains is the crucial quantity in the conduction, and its packing fraction dependence is exponential. Heat conduction is found to be anisotropic, where the conduction along the deposition direction is more efficient than that perpendicular to the deposition direction.

Sirono, Sin-Iti

2014-01-01

333

Thermal Characterization for a Modular 3-D Multichip Module  

NASA Technical Reports Server (NTRS)

NASA Goddard Space Flight Center has designed a high-density modular 3-D multichip module (MCM) for future spaceflight use. This MCM features a complete modular structure, i.e., each stack can be removed from the package without damaging the structure. The interconnection to the PCB is through the Column Grid Array (CGA) technology. Because of its high-density nature, large power dissipation from multiple layers of circuitry is anticipated and CVD diamond films are used in the assembly for heat conduction enhancement. Since each stacked layer dissipates certain amount of heat, designing effective heat conduction paths through each stack and balancing the heat dissipation within each stack for optimal thermal performance become a challenging task. To effectively remove the dissipated heat from the package, extensive thermal analysis has been performed with finite element methods. Through these analyses, we are able to improve the thermal design and increase the total wattage of the package for maximum electrical performance. This paper provides details on the design-oriented thermal analysis and performance enhancement. It also addresses issues relating to contact thermal resistance between the diamond film and the metallic heat conduction paths.

Fan, Mark S.; Plante, Jeannette; Shaw, Harry

2000-01-01

334

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

335

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

336

Heat conduction in driven Frenkel-Kontorova lattices: thermal pumping and resonance.  

PubMed

Heat conduction through the Frenkel-Kontorova chain under the influence of an ac driving force applied locally at one boundary is studied by nonequilibrium molecular dynamics simulations. We observe the occurrence of thermal resonance, namely, there exists a value of the driving frequency at which the heat flux takes its maximum value. The resonance frequency is determined by the dynamical parameters of the model, which has been numerically explored. Remarkably, the heat can be pumped from the low-temperature heat bath to the high temperature one by suitably adjusting the frequency of the ac driving force. By examining effects of the driving amplitude on heat conduction, we show that the amplitude threshold for nonlinear supratransmission is absent when the system is in contact with heat baths, namely, the heat flux smoothly increases with the increasing of amplitude. PMID:20365714

Ai, Bao-quan; He, Dahai; Hu, Bambi

2010-03-01

337

Heat conduction in driven Frenkel-Kontorova lattices: Thermal pumping and resonance  

NASA Astrophysics Data System (ADS)

Heat conduction through the Frenkel-Kontorova chain under the influence of an ac driving force applied locally at one boundary is studied by nonequilibrium molecular dynamics simulations. We observe the occurrence of thermal resonance, namely, there exists a value of the driving frequency at which the heat flux takes its maximum value. The resonance frequency is determined by the dynamical parameters of the model, which has been numerically explored. Remarkably, the heat can be pumped from the low-temperature heat bath to the high temperature one by suitably adjusting the frequency of the ac driving force. By examining effects of the driving amplitude on heat conduction, we show that the amplitude threshold for nonlinear supratransmission is absent when the system is in contact with heat baths, namely, the heat flux smoothly increases with the increasing of amplitude.

Ai, Bao-Quan; He, Dahai; Hu, Bambi

2010-03-01

338

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

339

3D Printed Bionic Ears  

PubMed Central

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 precise 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.

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

2013-01-01

340

Heat flux cloaking, focusing, and reversal in ultra-thin composites considering conduction-convection effects  

NASA Astrophysics Data System (ADS)

Experimental results are presented for heat flux cloaking, focusing, and reversal in ultra-thin anisotropic composites. A two-material system is utilized in the device design, which features an annular region for heat flow control. The effective thermal conductivity layout of the composite is specified through logical combination of the base material constituents. Heat transfer considering conduction-convection is numerically predicted and experimentally verified via infrared thermography. A Biot number analysis reveals the significance of high rates of convection for large-area planar devices, while the experimental results indicate the feasibility of such heat flow control techniques for advanced electronics applications involving natural convection.

Dede, Ercan M.; Nomura, Tsuyoshi; Schmalenberg, Paul; Seung Lee, Jae

2013-08-01

341

Heat transport and conduction layers in gravity-assisted heat pipes  

NASA Astrophysics Data System (ADS)

The steady state performance and the limiting heat transport capability of gravity-assisted screen-wicked heat pipes with a liquid overfill are discussed in the present work. A semi-empirical correlation between the maximum heat flux density, or maximum heat transport rate, and various influence parameters, viz. tilt angle, fill charge, number of screen mesh layers, screen mesh size, operating temperature, heat pipe diameter and evaporator length, is derived. Moreover, the heat transfer phenomenon within the heat pipe as well as the effect of the screen structure on the bubble growth process is thoroughly investigated. Finally, the work confirms the complexity of the influence of screen mesh size and of the multiple-layer screen mesh configuration on the wall superheat required for the nucleation of the first bubbles, on the capillary force and on the wick porosity.

Nguyen-Chi, H.

1980-02-01

342

Prominent rocks - 3D  

NASA Technical Reports Server (NTRS)

Many prominent rocks near the Sagan Memorial Station are featured in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. Wedge is at lower left; Shark, Half-Dome, and Pumpkin are at center. Flat Top, about four inches high, is at lower right. The horizon in the distance is one to two kilometers away.

Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

1997-01-01

343

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.

344

'Diamond' in 3-D  

NASA Technical Reports Server (NTRS)

This 3-D, microscopic imager mosaic of a target area on a rock called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

The image mosaic is about 6 centimeters (2.4 inches) across.

2004-01-01

345

Experimental Thermal Conductivity, Thermal Diffusivity, and Specific Heat Values of Argon and Nitrogen.  

National Technical Information Service (NTIS)

Experimental measurements of thermal conductivity and thermal diffusivity as obtained in a transient hot-wire apparatus for argon and nitrogen are reported. Values of the specific heat are calculated from these measured values and the density associated w...

H. M. Roder R. A. Perkins C. A. Nieto de Castro

1988-01-01

346

Thermal conductivity of cementitious grouts for geothermal heat pumps. progress report fy 1997.  

National Technical Information Service (NTIS)

The thermal conductivity of cementitious grouts was investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pump systems. In addition, other relevant physical and mechanical properties we...

Allan

1997-01-01

347

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

348

[Effect of an ultrahigh-frequency electromagnetic field on the heat conductivity of experimental biological tissue].  

PubMed

It has been established that heat conductivity was markedly increased after UHF-irradiation. The combined use of UHF-irradiation and cryogenic destruction is 30-40 times as effective as cryogenic destruction alone. PMID:3337877

Ten, Iu V; Shafranov, V V; Repalov, V A; Kozhevnikov, V A; Mazokhin, V N

1988-01-01

349

Effects of friction and heat conduction on sound propagation in ducts. [analyzing complex aerodynamic noise problems  

NASA Technical Reports Server (NTRS)

The theory of sound propagation is examined in a viscous, heat-conducting fluid, initially at rest and in a uniform state, and contained in a rigid, impermeable duct with isothermal walls. Topics covered include: (1) theoretical formulation of the small amplitude fluctuating motions of a viscous, heat-conducting and compressible fluid; (2) sound propagation in a two dimensional duct; and (3) perturbation study of the inplane modes.

Huerre, P.; Karamcheti, K.

1976-01-01

350

Specific heat and thermal conductivity of superionic conductors in the superionic phase  

Microsoft Academic Search

The temperature dependences of the specific heat and the thermal conductivity of crystalline superionic conductors LnF3 (Ln = La, Ce, Pr), Li2B4O7 and ?-LiIO3 in the superionic phase have been investigated experimentally. The specific heat C\\u000a p and the thermal conductivity K are observed to increase monotonically over a wide range of temperatures above the Debye temperature ?D. This increase

A. É. Aliev; V. F. Krivorotov; P. K. Khabibullaev

1997-01-01

351

Effect of heat treatment on the thermal conductivity of plasma-sprayed thermal barrier coatings  

Microsoft Academic Search

The effect of heat treatment on the thermal conductivity of plasma-sprayed Y2O3 stabilized ZrO2 (YSZ) and Al2O3 coatings was investigated. A heat treatment of 1300 °C in flowing argon for 50 h was found to significantly increase the\\u000a thermal conductivity of the coatings when compared to measurements in the assprayed condition. Transmission electron microscopy\\u000a (TEM) examination of the microstructures of

Rollie Dutton; Robert Wheeler; K. S. Ravichandran; K. An

2000-01-01

352

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

353

Identification of a moving boundary for a heat conduction problem in a multilayer medium  

Microsoft Academic Search

In this paper, we give a uniqueness theorem for the moving boundary of a heat problem in a composite medium. Through solving\\u000a the Cauchy problem of heat equation in each subdomain, we finally find an approximation to the moving boundary for one-dimensional\\u000a heat conduction problem in a multilayer medium. The numerical scheme is based on the use of the method

Y. S. LiT; T. Wei

2010-01-01

354

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

355

NUMERICAL ANALYSIS OF TWO DIMENSIONAL HEAT CONDUCTIVITY IN STEADY STATE REGIME  

Microsoft Academic Search

Solving the differential equation of the heat conduction the temperature in each point of the body can be determined. However, in the case of bodies with boundary surface of sophisticated geometry no analytic method can be used. In this case the use of numerical methods becomes necessary. The finite element method is based on the integral equation of the heat

Ioan SÂRBU

356

Longwave ultrasound and conductive heating increase functional ankle mobility in asymptomatic subjects  

Microsoft Academic Search

AimsThis study aimed to compare the thermal effects of longwave ultrasound (LWUS) and conductive heating (hot water bottle—HWB) on ankle mobility using a non-injured Achilles tendon (AT) model. These two modalities represent a clinical and a home variation of heat treatment.

Adam Meakins; Tim Watson

2006-01-01

357

Spectral Element Approach for Coupled Radiative and Conductive Heat Transfer in Semitransparent Medium  

Microsoft Academic Search

A spectral element method is presented to solve coupled radiative and conductive heat transfer problems in multidimensional semitransparent medium. The solution of radiative energy source is based on a second order radiative transfer equation. Both the second order radiative transfer equation and the heat diffusion equation are discretized by spec- tral element approach. Four various test problems are taken as

J. M. Zhao; L. H. Liu

2007-01-01

358

Transient heat conduction analysis in functionally graded materials by the meshless local boundary integral equation method  

Microsoft Academic Search

Advanced computational method for transient heat conduction analysis in continuously nonhomogeneous functionally graded materials (FGM) is proposed. The method is based on the local boundary integral equations with moving least square approximation of the temperature and heat flux. The initial-boundary value problem is solved by the Laplace transform technique. Both Papoulis and Stehfest algorithms are applied for the numerical Laplace

J. Sladek; V. Sladek; Ch. Zhang

2003-01-01

359

Convective mechanism for inhibition of heat conduction in laser produced plasmas  

SciTech Connect

In laser-produced plasmas, the laser energy is absorbed only below and up to the critical density. For laser fusion applications, this energy must be transported beyond the corona via electron thermal conduction towards colder, higher density regions of the target to heat up material and cause ablation, which in turn generates an inward pressure to compress the fusion fuel. If the heat conduction is inhibited, the consequences will be a weaker ablation and therefore a weaker implosion. For many years now, the inhibition of heat conduction, i.e., the reduction of heat conduction relative to classical conduction, in laser-produced plasmas at relevant irradiances has been apparent from the large body of experimental evidence. Many mechanisms, such as dc magnetic fields, ion acoustic turbulence, and Weibel instabilities, have been proposed to be the cause of inhibition of heat conduction. Even improved calculations of the classical heat flux have been carried out to solve this problem. Nevertheless, no single one of the above mentioned mechanisms can explain the large inhibition observed in the experiments.

Lee, P.H.Y.; Willi, O.; Trainor, R.J.

1984-06-27

360

Effects of anisotropic conduction and heat pipe interaction on minimum mass space radiators  

NASA Technical Reports Server (NTRS)

Equations are formulated for the two dimensional, anisotropic conduction of heat in space radiator fins. The transverse temperature field was obtained by the integral method, and the axial field by numerical integration. A shape factor, defined for the axial boundary condition, simplifies the analysis and renders the results applicable to general heat pipe/conduction fin interface designs. The thermal results are summarized in terms of the fin efficiency, a radiation/axial conductance number, and a transverse conductance surface Biot number. These relations, together with those for mass distribution between fins and heat pipes, were used in predicting the minimum radiator mass for fixed thermal properties and fin efficiency. This mass is found to decrease monotonically with increasing fin conductivity. Sensitivities of the minimum mass designs to the problem parameters are determined.

Baker, Karl W.; Lund, Kurt O.

1991-01-01

361

New Insights Into the Heat Sources of Mantle Plumes, or: Where Does all the Heat Come From, Heat Producing Elements, Advective or Conductive Heat Flow?  

NASA Astrophysics Data System (ADS)

Melting anomalies in the Earth's upper mantle have often been attributed to the presence of mantle plumes that may originate in the lower mantle, possibly from the core-mantle boundary. Globally, mantle plumes exhibit a large range in buoyancy flux that which is proportional to their temperature and volume. Plumes with higher buoyancy fluxes should have higher temperatures and experience higher degrees of partial melting. Excess heat in mantle plumes could reflect either a) an enrichment of the heat producing elements (HPE: U, Th, K) in their mantle source leading to an increase of heat production by radioactive decay or b) advective or conductive heat transport across the core-mantle boundary. The advective transport of heat may result in a physical contribution of material from the core to the lower mantle. If core material is incorporated into the lower mantle, mantle plumes with a higher buoyancy flux should have higher core tracers, e.g. increased 186Os and Fe concentrations. Geophysical and dynamic modelling indicate that at least Afar, Easter, Hawaii, Louisville and Samoa may all originate at the core-mantle boundary. These plumes encompass the whole range of known buoyancy fluxes from 1.2 Mgs -1(Afar) to 6.5 Mgs -1 (Hawaii) providing evidence that the buoyancy flux is largely independent of other geophysical parameters. In an effort to explore whether the heat producing elements are the cause of excess heat we looked for correlations between fractionation corrected concentrations of the HPE and buoyancy flux. Our results suggest that there is no correlation between HPE concentrations and buoyancy flux (with and without an additional correction for variable degrees of partial melting). As anticipated, K, Th and U are positively correlated with each other (e.g. Hawaii, Iceland and Galapagos have significantly lower concentrations than e.g. Tristan da Cunha, the Canary Islands and the Azores). We also find no correlation between currently available Fe concentration data and buoyancy flux. The apparent lack of correlation suggests that excess heat may be a result of conductive heat contribution from the core. Additional precise 186Os and Fe data are needed to further assess these conclusions.

Rushmer, T.; Beier, C.; Turner, S.

2007-12-01

362

Supernova Remnant in 3-D  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Click on the image for the movie

For the first time, a multiwavelength three-dimensional reconstruction of a supernova remnant has been created. This stunning visualization of Cassiopeia A, or Cas A, the result of an explosion approximately 330 years ago, uses data from several telescopes: X-ray data from NASA's Chandra X-ray Observatory, infrared data from NASA's Spitzer Space Telescope and optical data from the National Optical Astronomy Observatory 4-meter telescope at Kitt Peak, Ariz., and the Michigan-Dartmouth-MIT 2.4-meter telescope, also at Kitt Peak. In this visualization, the green region is mostly iron observed in X-rays. The yellow region is a combination of argon and silicon seen in X-rays, optical, and infrared including jets of silicon plus outer debris seen in the optical. The red region is cold debris seen in the infrared. Finally, the blue reveals the outer blast wave, most prominently detected in X-rays.

Most of the material shown in this visualization is debris from the explosion that has been heated by a shock moving inwards. The red material interior to the yellow/orange ring has not yet encountered the inward moving shock and so has not yet been heated. These unshocked debris were known to exist because they absorb background radio light, but they were only recently discovered in infrared emission with Spitzer. The blue region is composed of gas surrounding the explosion that was heated when it was struck by the outgoing blast wave, as clearly seen in Chandra images.

To create this visualization, scientists took advantage of both a previously known phenomenon the Doppler effect and a new technology that bridges astronomy and medicine. When elements created inside a supernova, such as iron, silicon and argon, are heated they emit light at certain wavelengths. Material moving towards the observer will have shorter wavelengths and material moving away will have longer wavelengths. Since the amount of the wavelength shift is related to the speed of motion, one can determine how fast the debris are moving in either direction. Because Cas A is the result of an explosion, the stellar debris is expanding radially outwards from the explosion center. Using simple geometry, the scientists were able to construct a 3-D model using all of this information. A program called 3-D Slicer modified for astronomical use by the Astronomical Medicine Project at Harvard University in Cambridge, Mass. was used to display and manipulate the 3-D model. Commercial software was then used to create the 3-D fly-through.

The blue filaments defining the blast wave were not mapped using the Doppler effect because they emit a different kind of light synchrotron radiation that does not emit light at discrete wavelengths, but rather in a broad continuum. The blue filaments are only a representation of the actual filaments observed at the blast wave.

This visualization shows that there are two main components to this supernova remnant: a spherical component in the outer parts of the remnant and a flattened (disk-like) component in the inner region. The spherical component consists of the outer layer of the star that exploded, probably made of helium and carbon. These layers drove a spherical blast wave into the diffuse gas surrounding the star. The flattened component that astronomers were unable to map into 3-D prior to these Spitzer observations consists of the inner layers of the star. It is made from various heavier elements, not all shown in the visualization, such as oxygen, neon, silicon, sulphur, argon and iron.

High-velocity plumes, or jets, of this material are shooting out from the explosion in the plane of the disk-like component mentioned above. Plumes of silicon appear in the northeast and southwest, while those of iron are seen in the southeast and north. These jets were already known and Doppler velocity measurements have been made for these structures, but their orientation and position with resp

2009-01-01

363

Microwave absorption in powders of small conducting particles for heating applications.  

PubMed

In microwave chemistry there is a common misconception that small, highly conducting particles heat profusely when placed in a large microwave electric field. However, this is not the case; with the simple physical explanation that the electric field (which drives the heating) within a highly conducting particle is highly screened. Instead, it is the magnetic absorption associated with induction that accounts for the large experimental heating rates observed for small metal particles. We present simple principles for the effective heating of particles in microwave fields from calculations of electric and magnetic dipole absorptions for a range of practical values of particle size and conductivity. For highly conducting particles, magnetic absorption dominates electric absorption over a wide range of particle radii, with an optimum absorption set by the ratio of mean particle radius a to the skin depth ? (specifically, by the condition a = 2.41?). This means that for particles of any conductivity, optimized magnetic absorption (and hence microwave heating by magnetic induction) can be achieved by simple selection of the mean particle size. For weakly conducting samples, electric dipole absorption dominates, and is maximized when the conductivity is approximately ? ? 3??(0) ? 0.4 S m(-1), independent of particle radius. Therefore, although electric dipole heating can be as effective as magnetic dipole heating for a powder sample of the same volume, it is harder to obtain optimized conditions at a fixed frequency of microwave field. The absorption of sub-micron particles is ineffective in both magnetic and electric fields. However, if the particles are magnetic, with a lossy part to their complex permeability, then magnetic dipole losses are dramatically enhanced compared to their values for non-magnetic particles. An interesting application of this is the use of very small magnetic particles for the selective microwave heating of biological samples. PMID:23321957

Porch, Adrian; Slocombe, Daniel; Edwards, Peter P

2013-02-28

364

The effects of heat conduction on the vaporization of liquid invading superheated permeable rock  

SciTech Connect

We examine the role of conductive and convective heat transfer in the vaporization of liquid as it slowly invades a superheated permeable rock. For very slow migration, virtually all of the liquid vaporizes. As the liquid supply rate increases beyond the rate of heat transfer by thermal conduction, a decreasing fraction of the liquid can vaporize. Indeed, for sufficiently high flow rates, the fraction vaporizing depends solely on the superheat of the rock, and any heat transfer from the superheated region is negligible. These results complement earlier studies of vaporization under very high injection rates, in which case the dynamic vapour pressure reduces the mass fraction vaporizing to very small values.

Woods, Andrew, W.; Fitzgerald, Shaun D.

1996-01-24

365

Combined heat transfer of radiation and conduction in stacked radiation shields for vacuum insulation panels  

Microsoft Academic Search

Combined heat transfer of radiation and conduction considering depthwise conduction phenomena in stacked radiation shields for vacuum insulation panels (VIPs) having an artificial core structure is investigated. The purpose of this study is to establish a reliable analysis method for actual shield design. A one-dimensional problem is first analyzed. Actual two-dimensional problem is simplified for theoretical modeling and the depthwise

Choonghyo Jang; Jongmin Kim; Tae-Ho Song

2011-01-01

366

COMBINED CONDUCTION AND RADIATION HEAT TRANSFER IN PLANE-PARALLEL PACKED BEDS WITH VARIABLE POROSITY  

Microsoft Academic Search

The primary concern of this study deals with the prediction of thermal performance of packed beds with variable porosity. Combined conduction and radiation heat transfer in plane-parallel packed beds of spherical particles was investigated numerically. The effects of variable porosity, effective thermal conductivity, and thermal radiation were taken into account. The method for radiative transfer equation was based on the

JHY-WEN WU; HSIN-SEN CHU

1999-01-01

367

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

368

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

369

Local temperature redistribution and structural transition during joule-heating-driven conductance switching in VO2.  

PubMed

Joule-heating induced conductance-switching is studied in VO2 , a Mott insulator. Complementary in situ techniques including optical characterization, blackbody microscopy, scanning transmission X-ray microscopy (STXM) and numerical simulations are used. Abrupt redistribution in local temperature is shown to occur upon conductance-switching along with a structural phase transition, at the same current. PMID:23868142

Kumar, Suhas; Pickett, Matthew D; Strachan, John Paul; Gibson, Gary; Nishi, Yoshio; Williams, R Stanley

2013-11-13

370

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

371

Meshless approach for coupled radiative and conductive heat transfer in one-dimensional graded index medium  

NASA Astrophysics Data System (ADS)

A meshless local Petrov Galerkin (MLPG) approach is employed for solving the coupled radiative and conductive heat transfer in a one-dimensional slab with graded index media. The angular distribution term in discrete ordinate equation of radiative transfer within a one-dimensional graded index slab is discretized by a step scheme, and the meshless approach for radiative transfer is based on the discrete ordinate equation. A moving least-squares approximation is used to construct the shape function. Two particular test cases for coupled radiative and conductive heat transfer within a one-dimensional graded index slab are examined to verify this new approximate method. The temperatures and the radiative heat fluxes are obtained. The results are compared with the other benchmark approximate solutions. By comparison, the results show that the MLPG approach has a good accuracy in solving the coupled radiative and conductive heat transfer in one-dimensional graded index media.

Liu, L. H.; Tan, J. Y.; Li, B. X.

2006-09-01

372

An Experimental-Numerical Evaluation of Thermal Contact Conductance in Fin-Tube Heat Exchangers  

NASA Astrophysics Data System (ADS)

The contact between fin collar and tube surface of a fin-tube heat exchanger is secured through mechanical expansion of tubes. However, the characteristics of heat transfer through the interfaces between the tubes and fins have not been clearly understood because the interfaces consist partially of metal-to-metal contact and partially of air. The objective of the present study is to develop a new method utilizing an experimental-numerical method for the estimation of the thermal contact resistance between the fin collar and tube surface and to evaluate the factors affecting the thermal contact resistance in a fin-tube heat exchanger. In this study, heat transfer characteristics of actual heat exchanger assemblies have been tested in a vacuum chamber using water as an internal fluid, and a finite difference numerical scheme has been employed to reduce the experimental data for the evaluation of the thermal contact conductance. The present study has been conducted for fin-tube heat exchangers of tube diameter of 7mm with different tube expansion ratios, fin spacings, and fin types. The results show, with an appropriate error analysis, that these parameters as well as hydrophilic fin coating affect notably the thermal contact conductance. It has been found out that the thermal contact resistance takes fairly large portion of the total thermal resistance in a fin-tube heat exchanger and it turns out that careful consideration is needed in a manufacturing process of heat exchangers to reduce the thermal contact resistance.

Kim, Chang Nyung; Jeong, Jin; Youn, Baek; Kil, Seong Ho

373

Two-phase numerical model for thermal conductivity and convective heat transfer in nanofluids.  

PubMed

Due to the numerous applications of nanofluids, investigating and understanding of thermophysical properties of nanofluids has currently become one of the core issues. Although numerous theoretical and numerical models have been developed by previous researchers to understand the mechanism of enhanced heat transfer in nanofluids; to the best of our knowledge these models were limited to the study of either thermal conductivity or convective heat transfer of nanofluids. We have developed a numerical model which can estimate the enhancement in both the thermal conductivity and convective heat transfer in nanofluids. It also aids in understanding the mechanism of heat transfer enhancement. The study reveals that the nanoparticle dispersion in fluid medium and nanoparticle heat transport phenomenon are equally important in enhancement of thermal conductivity. However, the enhancement in convective heat transfer was caused mainly due to the nanoparticle heat transport mechanism. Ability of this model to be able to understand the mechanism of convective heat transfer enhancement distinguishes the model from rest of the available numerical models. PMID:21711746

Kondaraju, Sasidhar; Lee, Joon Sang

2011-01-01

374

Two-phase numerical model for thermal conductivity and convective heat transfer in nanofluids  

PubMed Central

Due to the numerous applications of nanofluids, investigating and understanding of thermophysical properties of nanofluids has currently become one of the core issues. Although numerous theoretical and numerical models have been developed by previous researchers to understand the mechanism of enhanced heat transfer in nanofluids; to the best of our knowledge these models were limited to the study of either thermal conductivity or convective heat transfer of nanofluids. We have developed a numerical model which can estimate the enhancement in both the thermal conductivity and convective heat transfer in nanofluids. It also aids in understanding the mechanism of heat transfer enhancement. The study reveals that the nanoparticle dispersion in fluid medium and nanoparticle heat transport phenomenon are equally important in enhancement of thermal conductivity. However, the enhancement in convective heat transfer was caused mainly due to the nanoparticle heat transport mechanism. Ability of this model to be able to understand the mechanism of convective heat transfer enhancement distinguishes the model from rest of the available numerical models.

2011-01-01

375

Effect of aggregation on thermal conductivity and heat transfer in hybrid nanocomposite phase change colloidal suspensions  

NASA Astrophysics Data System (ADS)

This study aims to investigate the role of aggregation of the hybrid nanocomposite particles on thermal conductivity and heat transfer of the phase change colloidal suspensions. It is observed that the incorporation of the hybrid nanocomposite particles substantially enhances thermal conductivity of such suspensions up to 42.4% and effectively reduces their freezing time by 19.5%. The predictions and the experimental results supports the fact that the aggregation of the hybrid nanocomposite particles largely involve in the eventual thermal conductivity enhancements and heat transfer of the phase change colloidal suspensions, with a sufficiently lesser effects realized from the nanoparticles Brownian motion.

Parameshwaran, R.; Kalaiselvam, S.

2013-11-01

376

The role of percolation and sheet dynamics during heat conduction in poly-dispersed graphene nanofluids  

NASA Astrophysics Data System (ADS)

A thermal transport mechanism leading to the enhanced thermal conductivity of graphene nanofluids has been proposed. The graphene sheet size is postulated to be the key to the underlying mechanism. Based on a critical sheet size derived from Stokes-Einstein equation for the poly-dispersed nanofluid, sheet percolation and Brownian motion assisted sheet collisions are used to explain the heat conduction. A collision dependant dynamic conductivity considering Debye approximated volumetric specific heat due to phonon transport in graphene has been incorporated. The model has been found to be in good agreement with experimental data.

Dhar, Purbarun; Sen Gupta, Soujit; Chakraborty, Saikat; Pattamatta, Arvind; Das, Sarit K.

2013-04-01

377

Modeling 3D Artificial Ionospheric Ducts  

NASA Astrophysics Data System (ADS)

The injection of powerful HF waves into the ionosphere leads to strong electron heating followed by a depletion of electrons in the heated region. This can create a pressure perturbation which propagates along the entire magnetic field line, enhancing refractive indices and acting as a waveguide to whistler-range waves. These perturbations are known as artificial ducts. Duct formation due to HF heating has previously been studied using a version of Sami2 is Another Model of the Ionosphere (SAMI2) modified to include a flexible source of HF heating. We extend this study to look at the formation of artificial ducts by HF heating in a 3D model using a similarly modified version of SAMI3. We examine how heating over Arecibo can create interhemispheric ducts along magnetic field lines. Acknowledgements: This work was sponsored by the Office of Naval Research.

Zawdie, K. A.; Huba, J. D.; Joyce, G. R.; Wu, T.

2011-12-01

378

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

379

3D Emotional Agent Architecture  

Microsoft Academic Search

\\u000a This chapter presents architecture to design emotional agents evolving in an artificial 3D environment. The agent behavior\\u000a and environment emulator are independent of implementation. To achieve this, a Language of Interface for Animations in 3D\\u000a called LIA-3D, is presented. The agent and environment simulator uses LIA to establish communication with each other.

Félix F. Ramos; Luis Razo; Alma V. Martinez; Fabiel Zúñiga; H. Ivan Piza

2005-01-01

380

Autofocus for 3D imaging  

Microsoft Academic Search

Three dimensional (3D) autofocus remains a significant challenge for the development of practical 3D multipass radar imaging. The current 2D radar autofocus methods are not readily extendable across sensor passes. We propose a general framework that allows a class of data adaptive solutions for 3D auto-focus across passes with minimal constraints on the scene contents. The key enabling assumption is

Forest Lee-Elkin

2008-01-01

381

Documentation and verification of STRES3D, Version 4.0; Yucca Mountain Site Characterization Project  

SciTech Connect

STRES3D is a thermomechanical analysis code for predicting transient temperatures, stresses and displacements in an infinite and semi-infinite, conducting, homogeneous, elastic medium. The heat generated at the sources can be constant or decay exponentially with time. Superposition is used to integrate the effect of heat sources distributed in space and time to simulate the thermomechanical effect of placement of heat generating nuclear waste canisters in an underground repository. Heat sources can be defined by point, lines or plates with numerical integration of the kernal point source solution used to develop the line and plate sources. STRES3D is programmed using FORTRAN77 and is suitable for use on micro or larger computer systems.

Asgian, M.I.; St. John, C.M.; Hardy, M.P.; Goodrich, R.R. [Agapito (J.F.T.) and Associates, Inc., Grand Junction, CO (United States)] [Agapito (J.F.T.) and Associates, Inc., Grand Junction, CO (United States)

1991-12-01

382

Simple heat treatment for fabrication of carbonaceous layer-coated microelectrodes and conductive stainless steels  

NASA Astrophysics Data System (ADS)

A simple heat treatment was used to fabricate carbonaceous layer-coated electrodes: micro-ring electrodes and conductive stainless steel. Substrates of sharpened quartz capillaries or type-316 stainless steel plates were put in an alumina boat with powder of petroleum pitch A240F separately and heated at 1073-1273 K in a flow of nitrogen or argon. By this treatment, both of the substrates were coated with a uniform carbonaceous layer of several hundred nano-meters in thickness. The electric conductivity of the layer was improved by increases in temperature and period of the heating. The quartz glass-capillary covered with the conductive layer was modified to a needle-type microelectrode by coating with an insulating polymer and baring the tip. At least a dozen carbon micro-ring electrodes with an outer radius of about 1 ?m were successfully prepared by the simple heat treatment. On the other hand, the carbonaceous layer formed on type-316 stainless steel showed relatively poor conductivity due to the formation of oxides in the layer. However, the conductivity was improved by electroplating of nickel on the substrate before the heating. The carbonaceous layer-coated stainless steel showed good corrosion resistance in sulphuric acid.

Fushimi, K.; Ono, A.; Matsushita, K.; Kumagai, H.; Konno, H.

2011-07-01

383

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

384

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

385

An analysis of the vapor flow and the heat conduction through the liquid-wick and pipe wall in a heat pipe with single or multiple heat sources  

NASA Technical Reports Server (NTRS)

A numerical analysis is presented for the overall performance of heat pipes with single or multiple heat sources. The analysis includes the heat conduction in the wall and liquid-wick regions as well as the compressibility effect of the vapor inside the heat pipe. The two-dimensional elliptic governing equations in conjunction with the thermodynamic equilibrium relation and appropriate boundary conditions are solved numerically. The solutions are in agreement with existing experimental data for the vapor and wall temperatures at both low and high operating temperatures.

Chen, Ming-Ming; Faghri, Amir

1990-01-01

386

High heat flux Kapitza conductance of technical copper with several different surface preparations  

NASA Astrophysics Data System (ADS)

Kapitza conductance values of technical copper with different surface treatments and for heat fluxes of up to 6 W cm -2 are reported. Five different surface preparations were studied: a, polished with 0.3 ?m alumina powder; b, oxidized at room temperature in air for a period of one month; c, oxidized in air at 200°C for 40 min; d, coated with 50-50 PbSn solder; e, coated with a layer of GE7031 varnish. The variation of surface temperature with heat flux as well as the limiting values of Kapitza conductance for small temperature difference are determined. Relative to the polished samples, it is observed that the baked and solder coated samples have higher conductances and that the samples oxidized in the atmosphere show lower conductances. The surface temperature of the varnished samples is controlled mostly by the low thermal conductivity of the varnish.

Kashani, A.; Van Sciver, S. W.

387

3D World Building System  

ScienceCinema

This video provides an overview of the Sandia National Laboratories developed 3-D World Model Building capability that provides users with an immersive, texture rich 3-D model of their environment in minutes using a laptop and color and depth camera.

None

2014-02-26

388

Market study: 3-D eyetracker  

NASA Technical Reports Server (NTRS)

A market study of a proposed version of a 3-D eyetracker for initial use at NASA's Ames Research Center was made. The commercialization potential of a simplified, less expensive 3-D eyetracker was ascertained. Primary focus on present and potential users of eyetrackers, as well as present and potential manufacturers has provided an effective means of analyzing the prospects for commercialization.

1977-01-01

389

3D World Building System  

ScienceCinema

This video provides an overview of the Sandia National Laboratories developed 3-D World Model Building capability that provides users with an immersive, texture rich 3-D model of their environment in minutes using a laptop and color and depth camera.

390

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

391

3D World Building System  

SciTech Connect

This video provides an overview of the Sandia National Laboratories developed 3-D World Model Building capability that provides users with an immersive, texture rich 3-D model of their environment in minutes using a laptop and color and depth camera.

None

2013-10-30

392

3-D Drawing and Geometry  

NSDL National Science Digital Library

A Math Forum Summer 1998 Institute project that uses examples of paintings, architecture, etc. to analyze different types of 3-D drawings, and teaches students how to create them. Careers in 3-D drawing that use these techniques, from architecture to movies, are also illustrated. Types include isometric, oblique, and perspective drawings. A drawing project for students is outlined and submissions are invited.

Forum, Math; Sanders, Cathi

2001-01-01

393

Thermal characterization of micro/nanoscale conductive and non-conductive wires based on optical heating and electrical thermal sensing  

NASA Astrophysics Data System (ADS)

In this work, a technique based on optical heating and electrical thermal sensing (OHETS) is developed to characterize the thermophysical properties of one-dimensional micro/nanoscale conductive and non-conductive wires. In this method, the to-be-measured thin wire is suspended over two electrodes and is irradiated with a periodically modulated laser beam. The laser beam induces a periodical temperature variation in the wire/tube, which will lead to a periodical change in its electrical resistance. A dc current is applied to the sample, and the resulting periodical voltage variation over the wire is measured and used to extract the thermophysical properties of the wire/tube. A 25.4 µm thick platinum wire is used as the reference sample to verify this technique. Sound agreement is obtained between the measured thermal conductivity and the reference value. Applying the OHETS technique, the thermal diffusivity of conductive single-wall carbon nanotube (SWCNT) bundles and non-conductive human hair and cloth fibres are measured. For non-conductive wires, a thin (~nm) metallic film is coated at the outside of the wire for electrical thermal sensing. The measured thermal diffusivities for three different SWCNT bundles are 2.98 × 10-5 m2 s-1, 4.41 × 10-5 m2 s-1 and 6.64 × 10-5 m2 s-1. These values are much less than the thermal diffusivity of graphite in the layer direction. For human hair and microscale cloth fibres, our experiments show that their thermal diffusivities are at the level of 10-6 m2 s-1.

Hou, Jinbo; Wang, Xinwei; Guo, Jiaqi

2006-08-01

394

Heat diode effect and negative differential thermal conductance across nanoscale metal-dielectric interfaces  

NASA Astrophysics Data System (ADS)

Controlling heat flow by phononic nanodevices has received significant attention recently because of its fundamental and practical implications. Elementary phononic devices such as thermal rectifiers, transistors, and logic gates are essentially based on two intriguing properties: heat diode effect and negative differential thermal conductance. However, little is known about these heat transfer properties across metal-dielectric interfaces, especially at nanoscale. Here we analytically resolve the microscopic mechanism of the nonequilibrium nanoscale energy transfer across metal-dielectric interfaces, where the inelastic electron-phonon scattering directly assists the energy exchange. We demonstrate the emergence of heat diode effect and negative differential thermal conductance in nanoscale interfaces and explain why these novel thermal properties are usually absent in bulk metal-dielectric interfaces. These results will generate exciting prospects for the nanoscale interfacial energy transfer, which should have important implications in designing hybrid circuits for efficient thermal control and open up potential applications in thermal energy harvesting with low-dimensional nanodevices.

Ren, Jie; Zhu, Jian-Xin

2013-06-01

395

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

396

Impedance mammograph 3D phantom studies.  

PubMed

The results obtained using the Technical University of Gdansk Electroimpedance Mammograph (TUGEM) of a 3D phantom study are presented. The TUGEM system is briefly described. The hardware contains the measurement head and DSP-based identification modules controlled by a PC computer. A specially developed reconstruction algorithm, Regulated Correction Frequency Algebraic Reconstruction Technique (RCFART), is used to obtain 3D images. To visualize results, the Advance Visualization System (AVS) is used. It allows a powerful image processing on a fast workstation or on a high-performance computer. Results of three types of 3D conductivity perturbations used in the study (aluminum, Plexiglas, and cucumber) are shown. The relative volumes of perturbations less than 2% of the measurement chamber are easily evidenced. PMID:10372188

Wtorek, J; Stelter, J; Nowakowski, A

1999-04-20

397

PLOT3D user's manual  

NASA Technical Reports Server (NTRS)

PLOT3D is a computer graphics program designed to visualize the grids and solutions of computational fluid dynamics. Seventy-four functions are available. Versions are available for many systems. PLOT3D can handle multiple grids with a million or more grid points, and can produce varieties of model renderings, such as wireframe or flat shaded. Output from PLOT3D can be used in animation programs. The first part of this manual is a tutorial that takes the reader, keystroke by keystroke, through a PLOT3D session. The second part of the manual contains reference chapters, including the helpfile, data file formats, advice on changing PLOT3D, and sample command files.

Walatka, Pamela P.; Buning, Pieter G.; Pierce, Larry; Elson, Patricia A.

1990-01-01

398

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

SciTech Connect

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 {center dot} m{sup {minus}1} {center dot} K{sup {minus}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. (Univ. of Delaware, Newark (USA))

1989-09-01

399

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

NASA Astrophysics Data System (ADS)

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 of the thermal contact conductance. Two sets of very good data are analyzed. One set of steady-state data was obtained by Antonetti and Eid (1987). The other set was obtained by Moses and Johnson (1986) under transient conditions for periodic contact. Both sets of data are used to illustrate parameter, function, and combined estimation. It is demonstrated that the proposed methods are more powerful then commonly accepted methods. Many other heat transfer problems can be treated using the proposed techniques.

Beck, J. V.

1988-11-01

400

Heat transfer through a multifoil insulation system by radiation and gaseous conduction - Analytical and experimental investigations  

NASA Astrophysics Data System (ADS)

Heat transfer through a 302-stainless steel multifoil insulation system under the flight conditions similar to that of an Unmanned Hypersonic Vehicle (UHV) was examined by both analysis and experiment. The analytical model considered both thermal radiation between two adjacent foils and gaseous heat conduction through the gas medium contained in the foil spacing. Temperature predictions from the pretest analysis agreed well with the test data under vacuum environment and gas pressures greater than 1.0 mm Hg. For intermediate pressures around 0.2 mm Hg, however, the pretest analytical model was found to slightly overpredict thermal radiation and underpredict gaseous heat conduction. The radiation and gaseous conduction parameters were therefore correlated using the test data. With the new correlations, agreement with the test and computed temperatures was excellent for all pressures.

Kang, C. S.; Hinton, J. F.; McNamara, R. C.

1989-01-01

401

Transient modeling/analysis of hyperbolic heat conduction problems employing mixed implicit-explicit alpha method  

NASA Technical Reports Server (NTRS)

This paper describes the evaluation of mixed implicit-explicit finite element formulations for hyperbolic heat conduction problems involving non-Fourier effects. In particular, mixed implicit-explicit formulations employing the alpha method proposed by Hughes et al. (1987, 1990) are described for the numerical simulation of hyperbolic heat conduction models, which involves time-dependent relaxation effects. Existing analytical approaches for modeling/analysis of such models involve complex mathematical formulations for obtaining closed-form solutions, while in certain numerical formulations the difficulties include severe oscillatory solution behavior (which often disguises the true response) in the vicinity of the thermal disturbances, which propagate with finite velocities. In view of these factors, the alpha method is evaluated to assess the control of the amount of numerical dissipation for predicting the transient propagating thermal disturbances. Numerical test models are presented, and pertinent conclusions are drawn for the mixed-time integration simulation of hyperbolic heat conduction models involving non-Fourier effects.

Tamma, Kumar K.; D'Costa, Joseph F.

1991-01-01

402

Transient heat transfer measurements using thermochromic liquid crystal: lateral-conduction error  

Microsoft Academic Search

Thermochromic liquid crystal (TLC) can be used to measure the surface temperature in transient heat transfer experiments. Knowing the time at which the TLC changes colour, hence knowing the surface temperature at that time, it is possible to calculate the heat transfer coefficient, h, and the analytical one-dimensional solution of Fourier’s conduction equation for a semi-infinite wall is often used

James R. Kingsley-Rowe; Gary D. Lock; J. Michael Owen

2005-01-01

403

Specific heat and thermal conductivity of ionic conductors and chalcogenide glasses at low temperatures  

Microsoft Academic Search

Measurements of specific heat in the temperature range 1–40 K for four chalcogen amorphous alloys (Se1-x-Tex)1-ySby and of thermal conductivity for three samples of superionic glasses (AgI)x (Ag2O2B2O3)1-x between 1 and 10 K are reported. The anomalous measured specific heat is interpreted in terms of phonon localization. The values obtained for the parameter L characterizing the length of this localization

A. Avogadro; S. Aldrovandi; G. Carini; A. Siri

1989-01-01

404

Note on heat conduction in liquid metals. A comparison of laminar and turbulent flow effects  

NASA Astrophysics Data System (ADS)

The difference between heat transfer in liquid metals with electric currents and magnetic fields on the one hand and heat transfer in electrically insulating fluids and in conducting solids on the other is pointed out. Laminar and turbulent flow effects in liquid metal sliding electric contacts for homopolar machines are considered. Large temperature gradients can develop within a small region of liquid metal. A model of a liquid-metal sliding electrical contact is developed and analyzed.

Talmage, G.

1994-05-01

405

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

NASA Astrophysics Data System (ADS)

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 independent of the diameter and chirality of nanotubes.

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

2004-05-01

406

Atomic dynamics and heat conduction of metal-dielectric and metal-semiconductor nano-interfaces  

NASA Astrophysics Data System (ADS)

The propagation of acoustic waves through interface of two crystals is studied on microscopic level using the discrete lattice model. It is considered phonon transmission through intercalated layer between two semi-infinite lattices. The general expressions for energy fluxes and impedances are proposed. Resonance transmission of phonons through the interface of the 3D pressure made KBr-Cu and Si-Cu point contact was studied using the discrete model of crystal lattice. We show that anomalous behavior of the reduced heat flux in the temperature range 1K

Feher, Alexander; Syrkin, Yevgen S.; Shkorbatov, Alexandre G.; Polyakov, Mihael L.; Minayev, Paul A.

2008-03-01

407

Equilibration and Universal Heat Conduction in Fermi-Pasta-Ulam Chains  

NASA Astrophysics Data System (ADS)

It is shown numerically that for Fermi-Pasta-Ulam (FPU) chains with alternating masses and heat baths at slightly different temperatures at the ends, the local temperature (LT) on small scales behaves paradoxically in steady state. This expands the long established problem of equilibration of FPU chains. A well-behaved LT appears to be achieved for equal mass chains; the thermal conductivity is shown to diverge with chain length N as N1/3, relevant for the much debated question of the universality of one-dimensional heat conduction. The reason why earlier simulations have obtained systematically higher exponents is explained.

Mai, Trieu; Dhar, Abhishek; Narayan, Onuttom

2007-05-01

408

Conducting-probe AFM nanoscale joule heating yields charge-density-wave transition detection.  

PubMed

Several layered transition-metal dichalcogenides are studied using conducting probe AFM aiming to investigate the probe-mediated thermal processes likely to arise in the probe-substrate vicinity due to the high-current densities involved. A signature of local heating is found in the shape of current-potential (i/V) curves. The latter allows straightforward detection of a charge-density-wave (CDW) transition for 1T-TaSe(2) samples exhibiting it above room temperature. This is an illustration of a new use of conducting probe AFM to investigate solid-state bulk characteristics owing to a distinctive nanoscale Joule heating. PMID:16706457

Schneegans, Olivier; Moradpour, Alec; Wang, Kang; Leblanc, Annie; Molinié, Philippe

2006-05-25

409

Basic Inquiry: Radiation and Heat Transfer by Conduction (title provided or enhanced by cataloger)  

NSDL National Science Digital Library

This activity consists of two parts in which students investigate heat transfer by radiation and by conduction. In the first part, students design and conduct an experiment to test the effect of color on an object's ability to radiate energy (heat). In the second part, they investigate the transfer of energy from a hotter object to a cooler one, in this case, containers of hot and cold water. In both experiments, they are required to state a hypothesis, make a list of materials and procedures needed for the experiment, collect and graph data, and state a conclusion. Each experiment is accompanied by a set of analysis and conclusion questions.

Robison, David

410

Lunar temperature and global heat flux from laboratory electrical conductivity and lunar magnetometer data  

NASA Technical Reports Server (NTRS)

Three-layer monotonic electrical conductivity models for the lunar interior to a depth of 600 km are used in conjunction with laboratory measurements of the electrical conductivity of olivine and pyroxene to estimate a temperature-depth profile. The temperatures calculated for depths of 400-600 km are consistent with attenuation of the seismic shear wave. The temperature calculated at a depth of 100-250 km yields a heat flow that is in good agreement with the directly measured lunar heat flow. The temperature, however, is sufficiently close to melting that mascon anisostasy would not be maintained. Thus a better conductor is required at this depth.

Sonett, C. P.; Duba, A.

1975-01-01

411

Flight data analysis and further development of variable-conductance heat pipes. [for aircraft control  

NASA Technical Reports Server (NTRS)

Continuing efforts in large gains in heat-pipe performance are reported. It was found that gas-controlled variable-conductance heat pipes can perform reliably for long periods in space and effectively provide temperature stabilization for spacecraft electronics. A solution was formulated that allows the control gas to vent through arterial heat-pipe walls, thus eliminating the problem of arterial failure under load, due to trace impurities of noncondensable gas trapped in an arterial bubble during priming. This solution functions well in zero gravity. Another solution was found that allows priming at a much lower fluid charge. A heat pipe with high capacity, with close temperature control of the heat source and independent of large variations in sink temperature was fabricated.

Enginer, J. E.; Luedke, E. E.; Wanous, D. J.

1976-01-01

412

Electrical conductivity of carbonaceous chondrites and electric heating of meteorite parent bodies  

NASA Technical Reports Server (NTRS)

Electromagnetic heating of rock-forming materials most probably was an important process in the early history of the solar system. Electrical conductivity experiments of representative materials such as carbonaceous chondrites are necessary to obtain data for use in electromagnetic heating models. With the assumption that carbon was present at grain boundaries in the material that comprised the meteorite parent bodies, the electrical heating of such bodies was calculated as a function of body size and solar distance using the T-Tauri model of Sonett and Herbert (1977). The results are discussed.

Duba, AL

1987-01-01

413

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

414

Coupling of wall conduction with natural convection from heated cylinders in a rectangular enclosure  

SciTech Connect

A numerical study has been conducted for natural convection heat transfer for air from two vertically separated horizontal heated cylinders confined to a rectangular enclosure having vertical walls of finite conductances and horizontal walls at the heat sink temperature. The interaction between convection in the fluid filled cavity and conduction in the vertical walls is investigated. Results have been obtained for Rayleigh numbers, Ra, between 10{sup 3} and 10{sup 6}, dimensionless wall-fluid thermal conductivity ratio {alpha} between 0.2 and 1,000.0 and dimensionless wall thickness {bar W} between 0.25 and 1.375. Results indicate that the Nusselt number along the vertical wall-fluid interface is a complex function of both Ra and {bar {alpha}}. In general, the relative heat removal contribution by conduction in the wall through the top horizontal surface {eta}{sub N} decreases with Ra while that for the bottom surface {eta}{sub S} increases. For 0.2 {le} {alpha} {le} 5.0, {eta}{sub S} is nearly independent of Ra. Moreover, for Ra {ge} 10{sup 5}, 0.2 {le} {bar {alpha}} {le} 5.0 and 0.25 {le} {bar W} {le} 1.375, {eta}{sub S} is independent of {bar {alpha}} while {eta}{sub N} tends to zero with increasing {bar {alpha}}.

Lacroix, M.; Joyeux, A. [Univ. de Sherbrooke, Quebec (Canada). Dept. de Genie Mecanique] [Univ. de Sherbrooke, Quebec (Canada). Dept. de Genie Mecanique

1996-01-01

415

3D Shape from Unorganized 3D Point Clouds  

Microsoft Academic Search

\\u000a We present a framework to automatically infer topology and geometry from an unorganized 3D point cloud obtained from a 3D\\u000a scene. If the cloud is not oriented, we use existing methods to orient it prior to recovering the topology. We develop a quality\\u000a measure for scoring a chosen topology\\/orientation. The topology is used to segment the cloud into manifold components

George Kamberov; Gerda Kamberova; Amit Jain

2005-01-01

416

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

417

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

1989-01-01

418

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

419

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

420

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

421

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

422

Applied multifocus 3D microscopy  

NASA Astrophysics Data System (ADS)

The depth from focus measurement principle relies on the detection of the optimal focusing distance for measuring the depth map of an object and finding its 3D shape. The principle is most effective at microscopic ranges where it is usually found implemented around a z-controlled microscope and sometimes named multifocus 3D microscopy. As such, the method competes with many other 3D measurement methods showing both advantages and disadvantages. Multifocus 3D microscopy is presented and compared to chromatic aberation, confocal microscopy, white light interferometry. Then, this paper discusses two applications of multifocus 3D microscopy for measuring wood respectively metallic parts in the sub-millimeter range. The first application aims at measuring the topography of wood samples for surface quality control. The wood samples surface topography is evaluated with data obtained from both confocal microscopy and multifocus 3D microscopy. The profiles and a standard roughness factor are compared. The second application concerns the measurement of burrs on metallic parts. Possibilities and limits of multifocus 3D microscopy are presented and discussed.

Zamofing, Thierry; Hügli, Heinz

2004-02-01

423

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

424

Thermal conductivity and elastic modulus evolution of thermal barrier coatings under high heat flux conditions  

Microsoft Academic Search

Laser high heat flux test approaches have been established to obtain critical properties of ceramic thermal barrier coatings\\u000a (TBCs) under near-realistic temperature and thermal gradients that may be encountered in advanced engine systems. Thermal\\u000a conductivity change kinetics of a thin ceramic coating were continuously monitored in real time at various test temperatures.\\u000a A significant thermal conductivity increase was observed during

Dongming Zhu; Robert A. Miller

2000-01-01

425

A meshless model for transient heat conduction in functionally graded materials  

Microsoft Academic Search

A meshless numerical model is developed for analyzing transient heat conduction in non-homogeneous functionally graded materials\\u000a (FGM), which has a continuously functionally graded thermal conductivity parameter. First, the analog equation method is used\\u000a to transform the original non-homogeneous problem into an equivalent homogeneous one at any given time so that a simpler fundamental\\u000a solution can be employed to take the

H. Wang; Q. H. Qin; Y. L. Kang

2006-01-01

426

Development of an Algorithm to Predict Vertical Heat Transfer Through Ceiling\\/Floor Conduction  

Microsoft Academic Search

This paper describes a new algorithm of the Consolidated Fire Growth and Smoke Transport (CFAST) fire model and compares the results with data from real-scale fire tests conducted aboard the ex-USS Shadwell, the U.S. Navy's Research and Development Damage Control Platform. The new phenomenon modeled in this work is the conduction of heat in the vertical direction. The Shadwell tests

J. L. Bailey; W. W. Jones; P. A. Tatem; G. P. Forney

1998-01-01

427

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

428