THERM3D -- A boundary element computer program for transient heat conduction problems
Ingber, M.S.
1994-02-01
The computer code THERM3D implements the direct boundary element method (BEM) to solve transient heat conduction problems in arbitrary three-dimensional domains. This particular implementation of the BEM avoids performing time-consuming domain integrations by approximating a ``generalized forcing function`` in the interior of the domain with the use of radial basis functions. An approximate particular solution is then constructed, and the original problem is transformed into a sequence of Laplace problems. The code is capable of handling a large variety of boundary conditions including isothermal, specified flux, convection, radiation, and combined convection and radiation conditions. The computer code is benchmarked by comparisons with analytic and finite element results.
3-D Finite Element Heat Transfer
Energy Science and Technology Software Center (ESTSC)
1992-02-01
TOPAZ3D is a three-dimensional implicit finite element computer code for heat transfer analysis. TOPAZ3D can be used to solve for the steady-state or transient temperature field on three-dimensional geometries. Material properties may be temperature-dependent and either isotropic or orthotropic. A variety of time-dependent and temperature-dependent boundary conditions can be specified including temperature, flux, convection, and radiation. By implementing the user subroutine feature, users can model chemical reaction kinetics and allow for any type of functionalmore » representation of boundary conditions and internal heat generation. TOPAZ3D can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in the material surrounding the enclosure. Additional features include thermal contact resistance across an interface, bulk fluids, phase change, and energy balances.« less
TACO3D. 3-D Finite Element Heat Transfer Code
Mason, W.E.
1992-03-04
TACO3D is a three-dimensional, finite-element program for heat transfer analysis. An extension of the two-dimensional TACO program, it can perform linear and nonlinear analyses and can be used to solve either transient or steady-state problems. The program accepts time-dependent or temperature-dependent material properties, and materials may be isotropic or orthotropic. A variety of time-dependent and temperature-dependent boundary conditions and loadings are available including temperature, flux, convection, and radiation boundary conditions and internal heat generation. Additional specialized features treat enclosure radiation, bulk nodes, and master/slave internal surface conditions (e.g., contact resistance). Data input via a free-field format is provided. A user subprogram feature allows for any type of functional representation of any independent variable. A profile (bandwidth) minimization option is available. The code is limited to implicit time integration for transient solutions. TACO3D has no general mesh generation capability. Rows of evenly-spaced nodes and rows of sequential elements may be generated, but the program relies on separate mesh generators for complex zoning. TACO3D does not have the ability to calculate view factors internally. Graphical representation of data in the form of time history and spatial plots is provided through links to the POSTACO and GRAPE postprocessor codes.
Lilley, D.G.
1987-01-01
Analytical and numerical methods, including both finite difference and finite element techniques, are presented with applications to heat conduction problems. Numerical and analytical methods are integrated throughout the text and a variety of complexities are thoroughly treated with many problems, solutions and computer programs. This book is presented as a fundamental course suitable for senior undergraduate and first year graduate students, with end-of-chapter problems and answers included. Sample case studies and suggested projects are included.
3D Thermal Modeling for Planetary Heat Flow Measurements
NASA Astrophysics Data System (ADS)
Siegler, M. A.; Smrekar, S. E.; Platt, J.; Paige, D. A.; Williams, J.
2013-12-01
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.
Reduction of thermal conductivity by nanoscale 3D phononic crystal.
Yang, Lina; Yang, Nuo; Li, Baowen
2013-01-01
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. PMID:23378898
Reduction of Thermal Conductivity by Nanoscale 3D Phononic Crystal
Yang, Lina; Yang, Nuo; Li, Baowen
2013-01-01
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. PMID:23378898
Conduction mechanisms in 2D and 3D SIS capacitors
NASA Astrophysics Data System (ADS)
Jacqueline, Sébastien; Domengès, Bernadette; Voiron, Frédéric; Murray, Hugues
2013-04-01
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.
3D conductive nanocomposite scaffold for bone tissue engineering
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
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. PMID:24399874
3D conductive nanocomposite scaffold for bone tissue engineering.
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
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. PMID:24399874
Vahala, G.; Vahala, L.; Morrison, J.
1996-12-31
It is well known that laminar heat conduction leads to a totally inadequate gas blanket detachment region. Restricting ourselves to 2D mean toroidal flow over toroidal cavities and utilizing the K-{epsilon}, compressible turbulence code ISAAC we have shown how 3D neutral turbulence can lead to a significantly larger detachment region due to an order of magnitude increase in the heat conduction to the toroidal sidewalls. We now extend these results by incorporating the full 3D divertor geometry and consider 3D mean shear flows: Mach 1.2 toroidal flow over the cavities as well as Mach 0.2 poloidal flow towards the divertor plate. The propagation of the heat front towards the divertor plate is considered as an initial value problem. Heat loads to the toroidal sidewalls, divertor walls as well as the divertor plate will be calculated. The turbulence is (and must) be treated 3D.
He, Minhong; Zhao, Yan; Wang, Biao; Xi, Qing; Zhou, Jun; Liang, Ziqi
2015-11-01
J. Zhou, Z. Liang, and co-workers successfully apply 3D printing technology to prepare thermoelectric materials. On page 5889, such 3D-fabricated Bi0.5 Sb1.5 Te3 samples exhibit amorphous characteristics and thus show an ultralow thermal conductivity of 0.2 W m(-1) K(-1) . Of unique importance, 3D printing fabrication enables the ready generation of shaped bulk TE samples which can hardly be created by traditional hot-pressing and spark plasma sintering methods. PMID:26768070
Intermittent Dissipation and Heating in 3D Kinetic Plasma Turbulence.
Wan, M; Matthaeus, W H; Roytershteyn, V; Karimabadi, H; Parashar, T; Wu, P; Shay, M
2015-05-01
High resolution, fully kinetic, three dimensional (3D) simulation of collisionless plasma turbulence shows the development of turbulence characterized by sheetlike current density structures spanning a range of scales. The nonlinear evolution is initialized with a long wavelength isotropic spectrum of fluctuations having polarizations transverse to an imposed mean magnetic field. We present evidence that these current sheet structures are sites for heating and dissipation, and that stronger currents signify higher dissipation rates. The analyses focus on quantities such as J·E, electron, and proton temperatures, and conditional averages of these quantities based on local electric current density. Evidently, kinetic scale plasma, like magnetohydrodynamics, becomes intermittent due to current sheet formation, leading to the expectation that heating and dissipation in astrophysical and space plasmas may be highly nonuniform. Comparison with previous results from 2D kinetic simulations, as well as high frequency solar wind observational data, are discussed. PMID:25978241
Heat Transfer Boundary Conditions in the RELAP5-3D Code
Richard A. Riemke; Cliff B. Davis; Richard R. Schultz
2008-05-01
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.
Induction Heating Process: 3D Modeling and Optimisation
NASA Astrophysics Data System (ADS)
Naar, R.; Bay, F.
2011-05-01
An increasing number of problems in mechanics and physics involves multiphysics coupled problems. Among these problems, we can often find electromagnetic coupled problems. Electromagnetic couplings may be involved through the use of direct or induced currents for thermal purposes—in order to generate heat inside a work piece in order to get either a prescribed temperature field or some given mechanical or metallurgical properties through an accurate control of temperature evolution with respect to time-, or for solid or fluid mechanics purposes—in order to create magnetic forces such as in fluid mechanics (electromagnetic stirring,…) or solid mechanics (magnetoforming,…). Induction heat treatment processes is therefore quite difficult to control; trying for instance to minimize distortions generated by such a process is not easy. In order to achieve these objectives, we have developed a computational tool which includes an optimsation stage. A 3D finite element modeling tool for local quenching after induction heating processes has already been developed in our laboratory. The modeling of such a multiphysics coupled process needs taking into account electromagnetic, thermal, mechanical and metallurgical phenomenon—as well as their mutual interactions during the whole process: heating and quenching. The model developed is based on Maxwell equations, heat transfer equation, mechanical equilibrium computations, Johnson-Mehl-Avrami and Koistinen-Marburger laws. All these equations and laws may be coupled but some coupling may be neglected. In our study, we will also focus on induction heating process aiming at optimising the Heat Affected Zone (HAZ). Thus problem is formalized as an optimization problem—minimizing a cost function which measures the difference between computed and optimal temperatures—along with some constraints on process parameters. The optimization algorithms may be of two kinds—either zero-order or first-order algorithms. First-order algorithms have proved their efficiency for induction heating processes. However, zero-order algorithms—such as evolution strategy algorithms—are better at reaching global minimal values for cost functions. We use here a method based on Efficient Global Optimization algorithm developed by Jones which is an optimization procedure assisted by a meta model. We will present some results obtained with our numerical tool on the preheating of a part before forging. We will focus on the control of temperature profile at the end of induction heating stage.
Steady state heat transport in 3D heterogeneous porous media
NASA Astrophysics Data System (ADS)
Hidalgo, Juan J.; Carrera, Jess; Dentz, Marco
2009-08-01
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.
Intermittent dissipation and heating in 3D kinetic plasma turbulence
NASA Astrophysics Data System (ADS)
Wan, M.; Matthaeus, W. H.; Roytershteyn, V.; Karimabadi, H.; Parashar, T.; Wu, P.; Shay, M. A.
2014-12-01
The nature of collisionless dissipation has been hotlydebated in recent years, with alternative ideas posed interms of various wave modes, such as kinetic Alfven waves,whistlers, linear Vlasov instabilities, cyclotron resonance,and Landau damping. Here we use large scale, fully kinetic3D simulations of collisionless plasma turbulence which showthe development of turbulence characterized by sheet-likecurrent density structures spanning a range of scales.We present evidence that these structures are sites for heatingand dissipation, and that stronger current structures signifyhigher dissipation rates. The analyses focus on quantities such as J.E, electron and proton temperatures, and PVI of the magnetic field. Evidently, kinetic scale plasma,like magnetohydrodynamics, becomes intermittent due tocurrent sheet formation, leading to the expectationthat heating and dissipation in astrophysical and space plasmasmay be highly nonuniform. Comparison with previousresults from 2D kinetic simulations, as well as high frequencysolar wind observational data will also be discussed.
Coolant side heat transfer with rotation: User manual for 3D-TEACH with rotation
NASA Technical Reports Server (NTRS)
Syed, S. A.; James, R. H.
1989-01-01
This program solves the governing transport equations in Reynolds average form for the flow of a 3-D, steady state, viscous, heat conducting, multiple species, single phase, Newtonian fluid with combustion. The governing partial differential equations are solved in physical variables in either a Cartesian or cylindrical coordinate system. The effects of rotation on the momentum and enthalpy calculations modeled in Cartesian coordinates are examined. The flow of the fluid should be confined and subsonic with a maximum Mach number no larger than 0.5. This manual describes the operating procedures and input details for executing a 3D-TEACH computation.
Temperature distributions in the laser-heated diamond anvil cell from 3-D numerical modeling
Rainey, E. S. G.; Kavner, A.; Hernlund, J. W.
2013-11-28
We present TempDAC, a 3-D numerical model for calculating the steady-state temperature distribution for continuous wave laser-heated experiments in the diamond anvil cell. TempDAC solves the steady heat conduction equation in three dimensions over the sample chamber, gasket, and diamond anvils and includes material-, temperature-, and direction-dependent thermal conductivity, while allowing for flexible sample geometries, laser beam intensity profile, and laser absorption properties. The model has been validated against an axisymmetric analytic solution for the temperature distribution within a laser-heated sample. Example calculations illustrate the importance of considering heat flow in three dimensions for the laser-heated diamond anvil cell. In particular, we show that a “flat top” input laser beam profile does not lead to a more uniform temperature distribution or flatter temperature gradients than a wide Gaussian laser beam.
3D Printing of Conductive Complex Structures with In Situ Generation of Silver Nanoparticles.
Fantino, Erika; Chiappone, Annalisa; Roppolo, Ignazio; Manfredi, Diego; Bongiovanni, Roberta; Pirri, Candido Fabrizio; Calignano, Flaviana
2016-05-01
Coupling the photoreduction of a metal precursor with 3D-printing technology is shown to allow the fabrication of conductive 3D hybrid structures consisting of metal nanoparticles and organic polymers shaped in complex multilayered architectures. 3D conductive structures are fabricated incorporating silver nitrate into a photocurable oligomer in the presence of suitable photoinitiators and exposing them to a digital light system. PMID:26992060
Fabrication of Conductive 3D Gold-Containing Microstructures via Direct Laser Writing.
Blasco, Eva; Müller, Jonathan; Müller, Patrick; Trouillet, Vanessa; Schön, Markus; Scherer, Torsten; Barner-Kowollik, Christopher; Wegener, Martin
2016-05-01
3D conductive microstructures containing gold are fabricated by simultaneous photopolymerization and photoreduction via direct laser writing. The photoresist employed consists of water-soluble polymers and a gold precursor. The fabricated microstructures show good conductivity and are successfully employed for 3D connections between gold pads. PMID:26953811
NASA Technical Reports Server (NTRS)
2003-01-01
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.
3D Printing Fabrication of Amorphous Thermoelectric Materials with Ultralow Thermal Conductivity.
He, Minhong; Zhao, Yan; Wang, Biao; Xi, Qing; Zhou, Jun; Liang, Ziqi
2015-11-01
Thermoelectric materials are prepared by developing 3D printing technology. The 3D fabricated Bi0.5 Sb1.5 Te3 samples exhibit amorphous characteristics and thus show an ultralow thermal conductivity of 0.2 W m(-1) K(-1) . 3D printing fabrication readily generates bulk thermoelectric samples of any shape, which is not the case with traditional hot-pressing and spark plasma sintering methods. PMID:26448629
NASA Astrophysics Data System (ADS)
Yang, R.; Song, A.; Li, X. D.; Lu, Y.; Yan, R.; Xu, B.; Li, X.
2014-10-01
A 3D reconstruction solution to ultrasound Joule heat density tomography based on acousto-electric effect by deconvolution is proposed for noninvasive imaging of biological tissue. Compared with ultrasound current source density imaging, ultrasound Joule heat density tomography doesn't require any priori knowledge of conductivity distribution and lead fields, so it can gain better imaging result, more adaptive to environment and with wider application scope. For a general 3D volume conductor with broadly distributed current density field, in the AE equation the ultrasound pressure can't simply be separated from the 3D integration, so it is not a common modulation and basebanding (heterodyning) method is no longer suitable to separate Joule heat density from the AE signals. In the proposed method the measurement signal is viewed as the output of Joule heat density convolving with ultrasound wave. As a result, the internal 3D Joule heat density can be reconstructed by means of Wiener deconvolution. A series of computer simulations set for breast cancer imaging applications, with consideration of ultrasound beam diameter, noise level, conductivity contrast, position dependency and size of simulated tumors, have been conducted to evaluate the feasibility and performance of the proposed reconstruction method. The computer simulation results demonstrate that high spatial resolution 3D ultrasound Joule heat density imaging is feasible using the proposed method, and it has potential applications to breast cancer detection and imaging of other organs.
Manipulating thermal conductance across 3D/1D interface by impedance matching
NASA Astrophysics Data System (ADS)
Zhang, Jingjie; Polanco, Carlos; Ghosh, Avik
2014-03-01
Self-assembled monolayers (SAMs) are of special interest to nano-electronic and thermal devices, because we can tune their properties by changing the bonding strength that links the SAMs to a thin film layer. We explain how this bonding strength influence heat across this 3D-1D interfaces based on a frequency dependent broadening matrix that acts as a generalization of acoustic impedance. We demonstrate both how to build an equivalent ``impedance'' broadening matrix that captures the dimensionality mismatch at the 3D-1D transition and the ``matching'' effect of the end group on an equivalent 1D-1D interface. We calculate thermal boundary conductance (TBC) at metal/polymer interfaces with different terminal groups and polymers. The calculations are done with non-equilibrium Green's function formalism coupled with ab-initio parameters for the chemical group functionalized systems. Our results confirm that in the low frequency spectrum, the stronger the bonding the larger the TBC. Nevertheless, when we consider the whole phonon spectrum, there is a sweet spot in the bonding strength that maximizes TBC. NSF-CAREER (QMHP 1028883), NSF-IDR (CBET 1134311), XSEDE.
Fantino, Erika; Chiappone, Annalisa; Roppolo, Ignazio; Manfredi, Diego; Bongiovanni, Roberta; Pirri, Candido Fabrizio; Calignano, Flaviana
2016-05-01
On page 3712, E. Fantino, A. Chiappone, and co-workers fabricate conductive 3D hybrid structures by coupling the photo-reduction of metal precursors with 3D printing technology. The generated structures consist of metal nanoparticles embedded in a polymer matrix shaped into complex multilayered architectures. 3D conductive structures are fabricated with a digital light-processing printer incorporating silver salt into photocurable formulations. PMID:27167030
Conduction heat transfer solutions
VanSant, J.H.
1983-08-01
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.
3D Simulations of Farley-Buneman Turbulence Demonstrates Anomalous Electron Heating
NASA Astrophysics Data System (ADS)
Oppenheim, Meers; Dimant, Yakov
2012-10-01
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.
Conduction heat transfer solutions
VanSant, J.H.
1980-03-01
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.
GEO3D - Three-Dimensional Computer Model of a Ground Source Heat Pump System
James Menart
2013-06-07
This file is the setup file for the computer program GEO3D. GEO3D is a computer program written by Jim Menart to simulate vertical wells in conjunction with a heat pump for ground source heat pump (GSHP) systems. This is a very detailed three-dimensional computer model. This program produces detailed heat transfer and temperature field information for a vertical GSHP system.
Residual resistance of 2D and 3D structures and Joule heat release.
Gurevich, V L; Kozub, V I
2011-06-22
We consider a residual resistance and Joule heat release in 2D nanostructures as well as in ordinary 3D conductors. We assume that elastic scattering of conduction electrons by lattice defects is predominant. Within a rather intricate situation in such systems we discuss in detail two cases. (1) The elastic scattering alone (i.e. without regard of inelastic mechanisms of scattering) leads to a transition of the mechanical energy (stored by the electrons under the action of an electric field) into heat in a traditional way. This process can be described by the Boltzmann equation where it is possible to do the configuration averaging over defect positions in the electron-impurity collision term. The corresponding conditions are usually met in metals. (2) The elastic scattering can be considered with the help of the standard electron-impurity collision integral only in combination with some additional averaging procedure (possibly including inelastic scattering or some mechanisms of electron wavefunction phase destruction). This situation is typical for degenerate semiconductors with a high concentration of dopants and conduction electrons. Quite often, heat release can be observed via transfer of heat to the lattice, i.e. via inelastic processes of electron-phonon collisions and can take place at distances much larger than the size of the device. However, a direct heating of the electron system can be registered too by, for instance, local measurements of the current noise or direct measurement of an electron distribution function. PMID:21628783
Recent Heat Transfer Improvements to the RELAP5-3D Code
Riemke, Richard A; Davis, Cliff B; Oh, Chang
2007-05-01
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).
Compilation of 3D global conductivity model of the Earth for space weather applications
NASA Astrophysics Data System (ADS)
Alekseev, Dmitry; Kuvshinov, Alexey; Palshin, Nikolay
2015-07-01
We have compiled a global three-dimensional (3D) conductivity model of the Earth with an ultimate goal to be used for realistic simulation of geomagnetically induced currents (GIC), posing a potential threat to man-made electric systems. Bearing in mind the intrinsic frequency range of the most intense disturbances (magnetospheric substorms) with typical periods ranging from a few minutes to a few hours, the compiled 3D model represents the structure in depth range of 0-100 km, including seawater, sediments, earth crust, and partly the lithosphere/asthenosphere. More explicitly, the model consists of a series of spherical layers, whose vertical and lateral boundaries are established based on available data. To compile a model, global maps of bathymetry, sediment thickness, and upper and lower crust thicknesses as well as lithosphere thickness are utilized. All maps are re-interpolated on a common grid of 0.25×0.25 degree lateral spacing. Once the geometry of different structures is specified, each element of the structure is assigned either a certain conductivity value or conductivity versus depth distribution, according to available laboratory data and conversion laws. A numerical formalism developed for compilation of the model, allows for its further refinement by incorporation of regional 3D conductivity distributions inferred from the real electromagnetic data. So far we included into our model four regional conductivity models, available from recent publications, namely, surface conductance model of Russia, and 3D conductivity models of Fennoscandia, Australia, and northwest of the United States.
Kim, Hyun-Jun; Randriamahazaka, Hyacinthe; Oh, Il-Kwon
2014-12-29
Highly conductive, capacitive and flexible electrodes are fabricated by employing 3D graphene-nanotube-palladium nanostructures and a PEDOT:PSS conducting polymer. The fabricated flexible electrodes, without any additional metallic current collectors, exhibit increased charge mobility and good mechanical properties; they also allow greater access to the electrolyte ions and hence are suitable for flexible energy storage applications. PMID:25142299
A Simple, Low-Cost Conductive Composite Material for 3D Printing of Electronic Sensors
Leigh, Simon J.; Bradley, Robert J.; Purssell, Christopher P.; Billson, Duncan R.; Hutchins, David A.
2012-01-01
3D printing technology can produce complex objects directly from computer aided digital designs. The technology has traditionally been used by large companies to produce fit and form concept prototypes (‘rapid prototyping’) before production. In recent years however there has been a move to adopt the technology as full-scale manufacturing solution. The advent of low-cost, desktop 3D printers such as the RepRap and Fab@Home has meant a wider user base are now able to have access to desktop manufacturing platforms enabling them to produce highly customised products for personal use and sale. This uptake in usage has been coupled with a demand for printing technology and materials able to print functional elements such as electronic sensors. Here we present formulation of a simple conductive thermoplastic composite we term ‘carbomorph’ and demonstrate how it can be used in an unmodified low-cost 3D printer to print electronic sensors able to sense mechanical flexing and capacitance changes. We show how this capability can be used to produce custom sensing devices and user interface devices along with printed objects with embedded sensing capability. This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes. PMID:23185319
A simple, low-cost conductive composite material for 3D printing of electronic sensors.
Leigh, Simon J; Bradley, Robert J; Purssell, Christopher P; Billson, Duncan R; Hutchins, David A
2012-01-01
3D printing technology can produce complex objects directly from computer aided digital designs. The technology has traditionally been used by large companies to produce fit and form concept prototypes ('rapid prototyping') before production. In recent years however there has been a move to adopt the technology as full-scale manufacturing solution. The advent of low-cost, desktop 3D printers such as the RepRap and Fab@Home has meant a wider user base are now able to have access to desktop manufacturing platforms enabling them to produce highly customised products for personal use and sale. This uptake in usage has been coupled with a demand for printing technology and materials able to print functional elements such as electronic sensors. Here we present formulation of a simple conductive thermoplastic composite we term 'carbomorph' and demonstrate how it can be used in an unmodified low-cost 3D printer to print electronic sensors able to sense mechanical flexing and capacitance changes. We show how this capability can be used to produce custom sensing devices and user interface devices along with printed objects with embedded sensing capability. This advance in low-cost 3D printing with offer a new paradigm in the 3D printing field with printed sensors and electronics embedded inside 3D printed objects in a single build process without requiring complex or expensive materials incorporating additives such as carbon nanotubes. PMID:23185319
Evaluation of the RETRAN-3D Wall Friction Models and Heat Transfer Coefficient Correlations
Peterson, Craig E.; Shatford, John G.; Harrison, James F.; Agee, Lance J
2003-04-15
This paper presents an evaluation of many of the RETRAN-3D two-phase pressure drop and heat transfer models by comparing model prediction to a large body of experimental data.RETRAN-3D has been used to evaluate multiple two-phase pressure drop models utilizing an extensive experimental two-phase pressure drop database. The experimental pressure drop data cover both heated and adiabatic tests in upflow and horizontal configurations for a wide range of key parameters such as pressure, mass flux, quality, and pipe diameters. Two RETRAN-3D two-phase friction options and the Friedel two-phase friction model are tested and compared to the data. For the two-phase friction models compared herein, the modified Baroczy model available in RETRAN-3D is the best choice for all adiabatic and diabatic situations.The RETRAN-3D code has also been used to simulate a wide variety of heat transfer experiments. These heat transfer data cover single-phase and two-phase conditions over a large range of pressure, heat flux, and mass flux values. The performance of the RETRAN-3D default forced convection heat transfer coefficient correlations is evaluated. The Petukhov correlations provide comparable results for single-phase liquid, but the Dittus-Boelter model provides markedly better statistics for single-phase vapor. The RETRAN five-equation model that combines the Dittus-Boelter and Thom correlations provides the best overall subcooled and saturated boiling statistics and scatter chart behavior.
Heat Flow Partitioning Between Continents and Oceans - from 2D to 3D
NASA Astrophysics Data System (ADS)
Moresi, L. N.; Cooper, C. M.; Lenardic, A.
2010-12-01
Scalings derived from thermal network theory explain how the presence of continents can influence the Earth’s overall heat loss. Intuitively, it may seem that increasing the proportion of a planet’s surface area covered by continents would decrease the efficiency of heat transfer given that continents do not participate in convective overturn. However, this ignores the potential feedback between the insulating effect of continents and the temperature-dependent viscosity of the mantle (Lenardic et al, 2005, Cooper et al, 2007). When this feedback is considered, a clear regime exists in which the partial stagnation and insulation of the surface by buoyant continental crust can lead to an increase in heat flow compared to the uninsulated case. The numerical results used to verify the scalings have mostly been conducted in two dimensions in order to cover a very wide range of Rayleigh number, fraction of continental coverage, and continental thickness. However as more recent results show that the configuration of the crust also plays a role in determining the heat flow partitioning and global heat flow (See Lenardic et al, “Continents, Super-Continents, Mantle Thermal Mixing, and Mantle Thermal Isolation” in this session), we have begun to repeat this exhaustive and exhausting 2D study in 3D. Cooper, C.M., A. Lenardic, and L.-N. Moresi "Effects of continental insulation and the partioning of heat producing elements on the Earth's heat loss." Geophys. Res. Lett., 33 ,10.1029, 2006. Lenardic, A., L.-N. Moresi, A.M. Jellinek, and M. Manga "Continental insulation, mantle cooling, and the surface area of oceans and continents." Earth Planet. Sci. Lett., 234 ,317-333, 2005.
Estimation of the thermal conductivity of hemp based insulation material from 3D tomographic images
NASA Astrophysics Data System (ADS)
El-Sawalhi, R.; Lux, J.; Salagnac, P.
2015-09-01
In this work, we are interested in the structural and thermal characterization of natural fiber insulation materials. The thermal performance of these materials depends on the arrangement of fibers, which is the consequence of the manufacturing process. In order to optimize these materials, thermal conductivity models can be used to correlate some relevant structural parameters with the effective thermal conductivity. However, only a few models are able to take into account the anisotropy of such material related to the fibers orientation, and these models still need realistic input data (fiber orientation distribution, porosity, etc.). The structural characteristics are here directly measured on a 3D tomographic image using advanced image analysis techniques. Critical structural parameters like porosity, pore and fiber size distribution as well as local fiber orientation distribution are measured. The results of the tested conductivity models are then compared with the conductivity tensor obtained by numerical simulation on the discretized 3D microstructure, as well as available experimental measurements. We show that 1D analytical models are generally not suitable for assessing the thermal conductivity of such anisotropic media. Yet, a few anisotropic models can still be of interest to relate some structural parameters, like the fiber orientation distribution, to the thermal properties. Finally, our results emphasize that numerical simulations on 3D realistic microstructure is a very interesting alternative to experimental measurements.
Validation of Heat Transfer and Film Cooling Capabilities of the 3-D RANS Code TURBO
NASA Technical Reports Server (NTRS)
Shyam, Vikram; Ameri, Ali; Chen, Jen-Ping
2010-01-01
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.
NASA Astrophysics Data System (ADS)
Antonini Alves, Thiago; Santos, Paulo H. D.; Barbur, Murilo A.
2015-09-01
In this research, the temperatures of threedimensional (3D) protruding heaters mounted on a conductive substrate in a horizontal rectangular channel with laminar airflow are related to the independent power dissipation in each heater by using a matrix G + with invariant coefficients, which are dimensionless. These coefficients are defined in this study as the conjugate influence coefficients ( g +) caused by the forced convection- conduction nature of the heaters' cooling process. The temperature increase of each heater in the channel is quantified to clearly identify the contributions attributed to the self-heating and power dissipation in the other heaters (both upstream and downstream). The conjugate coefficients are invariant with the heat generation rate in the array of heaters when assuming a defined geometry, invariable fluid and flow rate, and constant substrate and heater conductivities. The results are numerically obtained by considering three 3D protruding heaters on a twodimensional (2D) array by ANSYS/Fluent™ 15.0 software. The conservation equations are solved by a coupled procedure within a single calculation domain comprising of solid and fluid regions and by considering a steady state laminar airflow with constant properties. Some examples are shown, indicating the effects of substrate thermal conductivity and Reynolds number on conjugate influence coefficients.
Electromagnetic Response Inversion for a 3D Distribution of Conductivity/Dielect
Energy Science and Technology Software Center (ESTSC)
2001-10-24
NLCGCS inverts electromagnetic responses for a 3D distribution of electrical conductivity and dielectric permittivity within the earth for geophysical applications using single processor computers. The software comes bundled with a graphical user interface to aid in model construction and analysis and viewing of earth images. The solution employs both dipole and finite size source configurations for harmonic oscillatory sources. A new nonlinear preconditioner is included in the solution to speed up solution convergence.
Extreme low thermal conductivity in nanoscale 3D Si phononic crystal with spherical pores.
Yang, Lina; Yang, Nuo; Li, Baowen
2014-01-01
In this work, we propose a nanoscale three-dimensional (3D) Si phononic crystal (PnC) with spherical pores, which can reduce the thermal conductivity of bulk Si by a factor up to 10,000 times at room temperature. Thermal conductivity of Si PnCs depends on the porosity, for example, the thermal conductivity of Si PnCs with porosity 50% is 300 times smaller than that of bulk Si. The phonon participation ratio spectra demonstrate that more phonons are localized as the porosity increases. The thermal conductivity is insensitive to the temperature changes from room temperature to 1100 K. The extreme-low thermal conductivity could lead to a larger value of ZT than unity as the periodic structure affects very little the electric conductivity. PMID:24559126
Zeng, Xiaoliang; Yao, Yimin; Gong, Zhengyu; Wang, Fangfang; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping
2015-12-01
Owing to the growing heat removal issue of modern electronic devices, polymer composites with high thermal conductivity have drawn much attention in the past few years. However, a traditional method to enhance the thermal conductivity of the polymers by addition of inorganic fillers usually creates composite with not only limited thermal conductivity but also other detrimental effects due to large amount of fillers required. Here, novel polymer composites are reported by first constructing 3D boron nitride nanosheets (3D-BNNS) network using ice-templated approach and then infiltrating them with epoxy matrix. The obtained polymer composites exhibit a high thermal conductivity (2.85 W m(-1) K(-1)), a low thermal expansion coefficient (24-32 ppm K(-1)), and an increased glass transition temperature (T(g)) at relatively low BNNSs loading (9.29 vol%). These results demonstrate that this approach opens a new avenue for design and preparation of polymer composites with high thermal conductivity. The polymer composites are potentially useful in advanced electronic packaging techniques, namely, thermal interface materials, underfill materials, molding compounds, and organic substrates. PMID:26479262
FURN3D: A computer code for radiative heat transfer in pulverized coal furnaces
Ahluwalia, R.K.; Im, K.H.
1992-08-01
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.
FURN3D: A computer code for radiative heat transfer in pulverized coal furnaces
Ahluwalia, R.K.; Im, K.H.
1992-08-01
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.
NASA Astrophysics Data System (ADS)
Xu, Hongmei; Wang, Huachun; Wu, Chenping; Lin, Na; Soomro, Abdul Majid; Guo, Huizhang; Liu, Chuan; Yang, Xiaodong; Wu, Yaping; Cai, Duanjun; Kang, Junyong
2015-06-01
Transparent conducting film occupies an important position in various optoelectronic devices. To replace the costly tin-doped indium oxide (ITO), promising materials, such as metal nanowires and graphene, have been widely studied. Moreover, a long-pursued goal is to consolidate these two materials together and express their outstanding properties simultaneously. We successfully achieved a direct 3D coating of a graphene layer on an interlacing Cu nanosilks network by the low pressure chemical vapor deposition method. High aspect ratio Cu nanosilks (13 nm diameter with 40 ?m length) were synthesized through the nickel ion catalytic process. Large-size, transparent conducting film was successfully fabricated with Cu nanosilks ink by the imprint method. A magnetic manipulator equipped with a copper capsule was used to produce high Cu vapor pressure on Cu nanosilks and realize the graphene 3D-coating. The coated Cu@graphene nanosilks network achieved high transparency, low sheet resistance (41 Ohm sq-1 at 95% transmittance) and robust antioxidant ability. With this technique, the transfer process of graphene is no longer needed, and a flexible, uniform and high-performance transparent conducting film could be fabricated in unlimited size.Transparent conducting film occupies an important position in various optoelectronic devices. To replace the costly tin-doped indium oxide (ITO), promising materials, such as metal nanowires and graphene, have been widely studied. Moreover, a long-pursued goal is to consolidate these two materials together and express their outstanding properties simultaneously. We successfully achieved a direct 3D coating of a graphene layer on an interlacing Cu nanosilks network by the low pressure chemical vapor deposition method. High aspect ratio Cu nanosilks (13 nm diameter with 40 ?m length) were synthesized through the nickel ion catalytic process. Large-size, transparent conducting film was successfully fabricated with Cu nanosilks ink by the imprint method. A magnetic manipulator equipped with a copper capsule was used to produce high Cu vapor pressure on Cu nanosilks and realize the graphene 3D-coating. The coated Cu@graphene nanosilks network achieved high transparency, low sheet resistance (41 Ohm sq-1 at 95% transmittance) and robust antioxidant ability. With this technique, the transfer process of graphene is no longer needed, and a flexible, uniform and high-performance transparent conducting film could be fabricated in unlimited size. Electronic supplementary information (ESI) available: Photographs, transmission spectra, Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) images. See DOI: 10.1039/c5nr01711d
Methodology for the Assessment of 3D Conduction Effects in an Aerothermal Wind Tunnel Test
NASA Technical Reports Server (NTRS)
Oliver, Anthony Brandon
2010-01-01
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.
Turbomachinery Heat Transfer and Loss Modeling for 3D Navier-Stokes Codes
NASA Technical Reports Server (NTRS)
DeWitt, Kenneth; Ameri, Ali
2005-01-01
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.
Electrical conductivity of the Iapetus Suture Zone Scotland, revisited with 3D inversion
NASA Astrophysics Data System (ADS)
Weckmann, U.; Toelg, D.; Ritter, O.
2012-12-01
The electrical conductivity structure of the crust beneath the Southern Uplands of Scotland has been investigated with electromagnetic and magneto-variational studies since the early 1970ies. The Southern Uplands formed in Ordovician and Silurian times as an accretionary prism on the Laurentian margin of the Iapetus Ocean as overthrusted wedges of sediments bounded by thrust faults. A pronounced zone of high electrical conductivity extending in northeast to southwest direction for at least 150 km was a common feature of many of these studies. The anomaly follows major structural trends of the Caledonian orogeny, such as the Southern Uplands Fault, the Orlock Bridge Fault and the Moniave Shear Zone. Graphite enrichment at mid-crustal levels trapped during the closure of the Iapetus Ocean or in detachment zones was discussed as possible causes for the high conductivity. In 1997, a high resolution MT experiment was conducted in southwestern Scotland across the most prominent faults. The station distribution, with an average spacing of 1-2km, concentrated on three parallel NW-SE profiles perpendicular to the tectonic structures and a strike parallel profile. Strike and dimensionality analyses indicated three-dimensional subsurface structures which also became evident in phases exceeding 90°. Nevertheless, 2D inversion of a sub-set of data revealed good spatial correlation of conductive zones and surface expressions of known faults. The 2D inversion results supported a mid-crustal detachment zone. However, some of the smaller profiles as well as the strike parallel profile could not be interpreted adequately with a 2D approach. Since 3D inversion algorithms are now available, we present a re-interpretation of the MT data set. We reprocessed the time series to improve estimates of the full impedance tensor for subsequent 3D inversion. 3D inversion reproduces the main features found along the published profiles. However, significant deviation from a 2D subsurface can be observed, which is mainly expressed in structures oblique to the 2D grid setup. In addition, we have focused on fitting 3D effects in the MT data such as phases >90°.
Jia, Jingjing; Sun, Xinying; Lin, Xiuyi; Shen, Xi; Mai, Yiu-Wing; Kim, Jang-Kyo
2014-06-24
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 MPam(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
3D simulation and analytical model of chemical heating during silicon wet etching in microchannels
NASA Astrophysics Data System (ADS)
Konakov, S. A.; Krzhizhanovskaya, V. V.
2016-02-01
We investigate chemical heating of a Silicon-on-Glass (SOG) chip during a highly exothermic reaction of silicon etching in potassium hydroxide (KOH) solution in a microchannel of 100-micron width inside a 1x1 cm SOG chip. Two modeling approaches have been developed, implemented and compared. (1) A detailed 3D model is based on unsteady Navier-Stokes equations, heat and mass transfer equations of a laminar flow of viscous incompressible fluid in microchannel, coupled to the heat transfer equation in the solid chip. 3D simulation results predicted temperature distributions for different KOH flow rates and silicon etching areas. Microchannels of a small diameter do not heat the chip due to the insufficient chemical heating of the cold fluid, whereas large-area etching (large channel diameter and/or length) leads to local overheating that may have negative effects on the device performance and durability. (2) A simplified analytical model solves a thermal balance equation describing the heating by chemical reactions inside the microchannel and energy loss by free convection of air around the chip. Analytical results compare well with the 3D simulations of a single straight microchannel, therefore the analytical model is suitable for quick estimation of process parameters. For complex microstructures, this simplified approach may be used as the first approximation.
Pattern transformation of heat-shrinkable polymer by three-dimensional (3D) printing technique.
Zhang, Quan; Yan, Dong; Zhang, Kai; Hu, Gengkai
2015-01-01
A significant challenge in conventional heat-shrinkable polymers is to produce controllable microstructures. Here we report that the polymer material fabricated by three-dimensional (3D) printing technique has a heat-shrinkable property, whose initial microstructure can undergo a spontaneous pattern transformation under heating. The underlying mechanism is revealed by evaluating internal strain of the printed polymer from its fabricating process. It is shown that a uniform internal strain is stored in the polymer during the printing process and can be released when heated above its glass transition temperature. Furthermore, the internal strain can be used to trigger the pattern transformation of the heat-shrinkable polymer in a controllable way. Our work provides insightful ideas to understand a novel mechanism on the heat-shrinkable effect of printed material, but also to present a simple approach to fabricate heat-shrinkable polymer with a controllable thermo-structural response. PMID:25757881
Pattern Transformation of Heat-Shrinkable Polymer by Three-Dimensional (3D) Printing Technique
Zhang, Quan; Yan, Dong; Zhang, Kai; Hu, Gengkai
2015-01-01
A significant challenge in conventional heat-shrinkable polymers is to produce controllable microstructures. Here we report that the polymer material fabricated by three-dimensional (3D) printing technique has a heat-shrinkable property, whose initial microstructure can undergo a spontaneous pattern transformation under heating. The underlying mechanism is revealed by evaluating internal strain of the printed polymer from its fabricating process. It is shown that a uniform internal strain is stored in the polymer during the printing process and can be released when heated above its glass transition temperature. Furthermore, the internal strain can be used to trigger the pattern transformation of the heat-shrinkable polymer in a controllable way. Our work provides insightful ideas to understand a novel mechanism on the heat-shrinkable effect of printed material, but also to present a simple approach to fabricate heat-shrinkable polymer with a controllable thermo-structural response. PMID:25757881
Pattern Transformation of Heat-Shrinkable Polymer by Three-Dimensional (3D) Printing Technique
NASA Astrophysics Data System (ADS)
Zhang, Quan; Yan, Dong; Zhang, Kai; Hu, Gengkai
2015-03-01
A significant challenge in conventional heat-shrinkable polymers is to produce controllable microstructures. Here we report that the polymer material fabricated by three-dimensional (3D) printing technique has a heat-shrinkable property, whose initial microstructure can undergo a spontaneous pattern transformation under heating. The underlying mechanism is revealed by evaluating internal strain of the printed polymer from its fabricating process. It is shown that a uniform internal strain is stored in the polymer during the printing process and can be released when heated above its glass transition temperature. Furthermore, the internal strain can be used to trigger the pattern transformation of the heat-shrinkable polymer in a controllable way. Our work provides insightful ideas to understand a novel mechanism on the heat-shrinkable effect of printed material, but also to present a simple approach to fabricate heat-shrinkable polymer with a controllable thermo-structural response.
Xu, Hongmei; Wang, Huachun; Wu, Chenping; Lin, Na; Soomro, Abdul Majid; Guo, Huizhang; Liu, Chuan; Yang, Xiaodong; Wu, Yaping; Cai, Duanjun; Kang, JunYong
2015-06-28
Transparent conducting film occupies an important position in various optoelectronic devices. To replace the costly tin-doped indium oxide (ITO), promising materials, such as metal nanowires and graphene, have been widely studied. Moreover, a long-pursued goal is to consolidate these two materials together and express their outstanding properties simultaneously. We successfully achieved a direct 3D coating of a graphene layer on an interlacing Cu nanosilks network by the low pressure chemical vapor deposition method. High aspect ratio Cu nanosilks (13 nm diameter with 40 μm length) were synthesized through the nickel ion catalytic process. Large-size, transparent conducting film was successfully fabricated with Cu nanosilks ink by the imprint method. A magnetic manipulator equipped with a copper capsule was used to produce high Cu vapor pressure on Cu nanosilks and realize the graphene 3D-coating. The coated Cu@graphene nanosilks network achieved high transparency, low sheet resistance (41 Ohm sq(-1) at 95% transmittance) and robust antioxidant ability. With this technique, the transfer process of graphene is no longer needed, and a flexible, uniform and high-performance transparent conducting film could be fabricated in unlimited size. PMID:26018299
A miniature microbial fuel cell with conducting nanofibers-based 3D porous biofilm
NASA Astrophysics Data System (ADS)
Jiang, Huawei; Halverson, Larry J.; Dong, Liang
2015-12-01
Miniature microbial fuel cell (MFC) technology has received growing interest due to its potential applications in high-throughput screening of bacteria and mutants to elucidate mechanisms of electricity generation. This paper reports a novel miniature MFC with an improved output power density and short startup time, utilizing electrospun conducting poly(3,4-ethylenedioxythiophene) (PEDOT) nanofibers as a 3D porous anode within a 12 μl anolyte chamber. This device results in 423 μW cm-3 power density based on the volume of the anolyte chamber, using Shewanella oneidensis MR-1 as a model biocatalyst without any optimization of bacterial culture. The device also excels in a startup time of only 1hr. The high conductivity of the electrospun nanofibers makes them suitable for efficient electron transfer. The mean pore size of the conducting nanofibers is several micrometers, which is favorable for bacterial penetration and colonization of surfaces of the nanofibers. We demonstrate that S. oneidensis can fully colonize the interior region of this nanofibers-based porous anode. This work represents a new attempt to explore the use of electrospun PEDOT nanofibers as a 3D anode material for MFCs. The presented miniature MFC potentially will provide a high-sensitivity, high-throughput tool to screen suitable bacterial species and mutant strains for use in large-size MFCs.
A Numerical Study on the Thermal Conductivity of 3D Woven C/C Composites at High Temperature
NASA Astrophysics Data System (ADS)
Shigang, Ai; Rujie, He; Yongmao, Pei
2015-12-01
Experimental data for Carbon/Carbon (C/C) constituent materials are combined with a three dimensional steady state heat transfer finite element analysis to demonstrate the average in-plane and out-of-plane thermal conductivities (TCs) of C/C composites. The finite element analysis is carried out at two distinct length scales: (a) a micro scale comparable with the diameter of carbon fibres and (b) a meso scale comparable with the carbon fibre yarns. Micro-scale model calculate the TCs at the fibre yarn scale in the three orthogonal directions ( x, y and z). The output results from the micro-scale model are then incorporated in the meso-scale model to obtain the global TCs of the 3D C/C composite. The simulation results are quite consistent with the theoretical and experimental counterparts reported in references. Based on the numerical approach, TCs of the 3D C/C composite are calculated from 300 to 2500 K. Particular attention is given in elucidating the variations of the TCs with temperature. The multi-scale models provide an efficient approach to predict the TCs of 3D textile materials, which is helpful for the thermodynamic property analysis and structure design of the C/C composites.
Variable conductance heat pipe technology
NASA Technical Reports Server (NTRS)
Marcus, B. D.; Edwards, D. K.; Anderson, W. T.
1973-01-01
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.
Mass Spectrometry of 3D-printed plastic parts under plasma and radiative heat environments
NASA Astrophysics Data System (ADS)
Rivera, W. F.; Romero-Talamas, C. A.; Bates, E. M.; Birmingham, W.; Takeno, J.; Knop, S.
2015-11-01
We present the design and preliminary results of a mass spectrometry system used to assess vacuum compatibility of 3D-printed parts, developed at the Dusty Plasma Laboratory of the University of Maryland Baltimore County (UMBC). A decrease in outgassing was observed when electroplated parts were inserted in the test chamber vs. non electroplated ones. Outgassing will also be tested under different environments such as plasma and radiative heat. Heat will be generated by a titanium getter pump placed inside a 90 degree elbow, such that titanium does not coat the part. A mirror inside the elbow will be used to throttle the heat arriving at the part. Plasma exposure of 3D printed parts will be achieved by placing the parts in a separate chamber connected to the spectrometer by a vacuum line that is differentially pumped. The signals from the mass spectrometer will be analyzed to see how the vacuum conditions fluctuate under different plasma discharges.
Modeling the transverse thermal conductivity of 3D-SICF/ SIC composites
Youngblood, Gerald E; Jones, Russell H; Yamada, Reiji
2004-06-30
Our previously developed hierarchical two-layer (H2L) model was modified to describe the effective transverse thermal conductivity (Keff) of a three-dimensional (3D) SiC/SiC composite plate made with cross-layered and Z-stitched X:Y:Z uniaxial fiber tow sub-units. As before, the model describes Keff in terms of constituent, microstructural and architectural properties that include the expected effects of fiber-matrix interfacial conductance, of high fiber packing fractions within individual tow sub-units and of the non-uniform porosity contents, shapes and orientations within these sub-units. Model predictions were obtained for two versions of a 3D-Tyranno SA/PyC/ICVI-SiC composite that had similar fiber/matrix pyrocarbon (PyC) interfaces, relatively high bulk densities (~2.88 g/cc), and an X:Y configuration with fiber content ratios 1:1. The only major difference between the two versions was their Z-stitch fiber content where the relative fiber ratios were 0.1 and 1.2 in the Z sub-units.
NASA Astrophysics Data System (ADS)
Castro, M. C.; Patriarche, D.; Goblet, P.
2004-12-01
The conceptual and practical gains achieved by expanding a 2-D finite element model [Castro and Goblet, 2003] to a true 3-D one through an application in the Carrizo aquifer and surrounding formations in southwestern Texas are investigated through a series of groundwater flow and 4He transport simulations. Such a 3-D model represents 4 formations, covers a surface area of ˜7000 km2, and comprises more than 5 million elements. 3-D simulations allow for a more detailed and accurate definition of the heterogeneities of the system, by specifically identifying and differentiating processes that directly impact the three-dimensional hydraulic conductivity field. It is shown that while hydraulic conductivity decreases exponentially along the regional groundwater flow direction, such decrease is better described as a function of depth rather than recharge distance. This relationship reflects the combined influences of differential compaction of the media as well as down-dip lithological change. The intrinsic permeability derived from this relationship agrees with field information. In addition, our relationship intrinsic permeability-depth derived from the obtained hydraulic conductivity field in the 3-D model domain for depths < 2 km is in agreement with that one proposed by Saar and Manga [2004] for the Oregon Cascades volcanic setting, as well as that proposed by Manning and Ingebritsen [1999]. These findings suggest that large-scale permeability evolution with depth is, to a large extent, independent of the type of medium. The 4He external flux value for which calibration of the 3-D transport model was achieved is 1.5×10-15 mol m-2rock s-1. Calculated hydraulic conductivities vary from 5×10-4 to 3.1×10-8 m s-1 in the Carrizo aquifer from the outcrop to the discharge area. Results also suggest that the solution for groundwater flow simulations based on calibration of hydraulic heads depends on the ratio between hydraulic conductivities of different formations, showing that an infinite number of solutions are available for calibration of 3-D groundwater flow models. Understanding how geological processes directly affect the 3-D hydraulic conductivity field at the regional scale is essential not only to hydrogeological applications, but also at improving our understanding of the Earth\\'{ }s crust and mantle dynamics by allowing for a more accurate quantification of helium and heat fluxes. Castro M. C., and Goblet P. (2003). Calibration of regional groundwater flow models - working toward a better understanding of site-specific systems. Water Resour. Res., 39(6), 1172, doi:10.1029/2002WR001653. Manning C. E., and Ingebritsen S. E. (1999). Permeability of the continental crust; implications of geothermal data and metamorphic systems. Rev. Geophys., 37(1), p. 127-150. Saar M. O., and Manga M. (2004). Depth dependence of permeability in the Oregon Cascades inferred from hydrogeologic, thermal, seismic, and magmatic modeling constraints. J. Geophys. Res., 109(B4), B04204, doi:10.1029/2003JB002855.
Nonlinear heat conduction with combustion
Galaktionov, V.A.; Kurclyumov, S.P.; Samarskiv, A.A. )
1991-01-01
This paper deals with a study of the properties of high-intensity combustion of a solid nonlinear heat conducting medium which is described by the quasilinear parabolic-type equation for nonlinear heat conduction with a source. The paper summarizes a significant range of investigations dealing with the study of high-intensity thermal processes in solid nonlinear media carried out by the authors in the past decade.
3D topographic correction of the BSR heat flow and detection of focused fluid flow
NASA Astrophysics Data System (ADS)
He, Tao; Li, Hong-Lin; Zou, Chang-Chun
2014-06-01
The bottom-simulating reflector (BSR) is a seismic indicator of the bottom of a gas hydrate stability zone. Its depth can be used to calculate the seafloor surface heat flow. The calculated BSR heat flow variations include disturbances from two important factors: (1) seafloor topography, which focuses the heat flow over regions of concave topography and defocuses it over regions of convex topography, and (2) the focused warm fluid flow within the accretionary prism coming from depths deeper than BSR. The focused fluid flow can be detected if the contribution of the topography to the BSR heat flow is removed. However, the analytical equation cannot solve the topographic effect at complex seafloor regions. We prove that 3D finite element method can model the topographic effect on the regional background heat flow with high accuracy, which can then be used to correct the topographic effect and obtain the BSR heat flow under the condition of perfectly flat topography. By comparing the corrected BSR heat flow with the regional background heat flow, focused fluid flow regions can be detected that are originally too small and cannot be detected using present-day equipment. This method was successfully applied to the midslope region of northern Cascadia subducting margin. The results suggest that the Cucumber Ridge and its neighboring area are positive heat flow anomalies, about 10%-20% higher than the background heat flow after 3D topographic correction. Moreover, the seismic imaging associated the positive heat flow anomaly areas with seabed fracture-cavity systems. This suggests flow of warm gas-carrying fluids along these high-permeability pathways, which could result in higher gas hydrate concentrations.
Yang, Renhuan; Li, Xu; Song, Aiguo; He, Bin; Yan, Ruqiang
2012-01-01
Electrical properties of biological tissues are highly sensitive to their physiological and pathological status. Thus it is of importance to image electrical properties of biological tissues. However, spatial resolution of conventional electrical impedance tomography (EIT) is generally poor. Recently, hybrid imaging modalities combining electric conductivity contrast and ultrasonic resolution based on acouto-electric effect has attracted considerable attention. In this study, we propose a novel three-dimensional (3D) noninvasive ultrasound Joule heat tomography (UJHT) approach based on acouto-electric effect using unipolar ultrasound pulses. As the Joule heat density distribution is highly dependent on the conductivity distribution, an accurate and high resolution mapping of the Joule heat density distribution is expected to give important information that is closely related to the conductivity contrast. The advantages of the proposed ultrasound Joule heat tomography using unipolar pulses include its simple inverse solution, better performance than UJHT using common bipolar pulses and its independence of any priori knowledge of the conductivity distribution of the imaging object. Computer simulation results show that using the proposed method, it is feasible to perform a high spatial resolution Joule heat imaging in an inhomogeneous conductive media. Application of this technique on tumor scanning is also investigated by a series of computer simulations. PMID:23123757
New transfer functions for probing 3-D mantle conductivity from ground and sea
NASA Astrophysics Data System (ADS)
Püthe, Christoph; Kuvshinov, Alexey; Olsen, Nils
2014-05-01
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.
Finite-Difference Algorithm for Simulating 3D Electromagnetic Wavefields in Conductive Media
NASA Astrophysics Data System (ADS)
Aldridge, D. F.; Bartel, L. C.; Knox, H. A.
2013-12-01
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.
One-Dimensional Heat Conduction
Energy Science and Technology Software Center (ESTSC)
1992-03-09
ICARUS-LLNL was developed to solve one-dimensional planar, cylindrical, or spherical conduction heat transfer problems. The IBM PC version is a family of programs including ICARUSB, an interactive BASIC heat conduction program; ICARUSF, a FORTRAN heat conduction program; PREICAR, a BASIC preprocessor for ICARUSF; and PLOTIC and CPLOTIC, interpretive BASIC and compiler BASIC plot postprocessor programs. Both ICARUSB and ICARUSF account for multiple material regions and complex boundary conditions, such as convection or radiation. In addition,more » ICARUSF accounts for temperature-dependent material properties and time or temperature-dependent boundary conditions. PREICAR is a user-friendly preprocessor used to generate or modify ICARUSF input data. PLOTIC and CPLOTIC generate plots of the temperature or heat flux profile at specified times, plots of the variation of temperature or heat flux with time at selected nodes, or plots of the solution grid. First developed in 1974 to allow easy modeling of complex one-dimensional systems, its original application was in the nuclear explosive testing program. Since then it has undergone extensive revision and been applied to problems dealing with laser fusion target fabrication, heat loads on underground tests, magnetic fusion switching tube anodes, and nuclear waste isolation canisters.« less
3D volume MR temperature mapping for HIFU heating trajectory comparisons
NASA Astrophysics Data System (ADS)
Todd, Nick; Vyas, Urvi; de Bever, Josh; Payne, Allison; Parker, Dennis L.
2012-10-01
Many areas of MR-guided thermal therapy research would benefit from temperature maps with high spatial and temporal resolution that cover a large 3-D volume. This paper describes an approach to achieve these goals that is suitable for research applications where retrospective reconstruction of the temperature maps is acceptable. The method acquires undersampled data from a modified 3-D segmented EPI sequence and creates images using a temporally constrained reconstruction algorithm. The 3-D images can be zero-filled to arbitrarily small voxel spacing in all directions and then converted into temperature maps using the standard proton resonance frequency (PRF) shift technique. During HIFU heating experiments, the proposed method was used to obtain temperature maps with 1.5×1.5×3.0 mm resolution, 288×162×78 mm field of view, and 1.7 second temporal resolution. The approach is validated to demonstrate that it can accurately capture the spatial characteristics and time dynamics of rapidly changing HIFU-induced temperature distributions. An example application is presented where the method is used to analyze and compare different HIFU volumetric heating trajectories.
Modification of divertor heat and particle flux profiles with 3-D fields in NSTX
NASA Astrophysics Data System (ADS)
Ahn, Joon-Wook
2010-11-01
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
NASA Astrophysics Data System (ADS)
Harlander, U.; Wright, G. B.; Egbers, C.
2012-04-01
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.
Parallel computing simulation of electrical excitation and conduction in the 3D human heart.
Di Yu; Dongping Du; Hui Yang; Yicheng Tu
2014-01-01
A correctly beating heart is important to ensure adequate circulation of blood throughout the body. Normal heart rhythm is produced by the orchestrated conduction of electrical signals throughout the heart. Cardiac electrical activity is the resulted function of a series of complex biochemical-mechanical reactions, which involves transportation and bio-distribution of ionic flows through a variety of biological ion channels. Cardiac arrhythmias are caused by the direct alteration of ion channel activity that results in changes in the AP waveform. In this work, we developed a whole-heart simulation model with the use of massive parallel computing with GPGPU and OpenGL. The simulation algorithm was implemented under several different versions for the purpose of comparisons, including one conventional CPU version and two GPU versions based on Nvidia CUDA platform. OpenGL was utilized for the visualization / interaction platform because it is open source, light weight and universally supported by various operating systems. The experimental results show that the GPU-based simulation outperforms the conventional CPU-based approach and significantly improves the speed of simulation. By adopting modern computer architecture, this present investigation enables real-time simulation and visualization of electrical excitation and conduction in the large and complicated 3D geometry of a real-world human heart. PMID:25570947
Heat conduction in three dimensions
NASA Technical Reports Server (NTRS)
Danza, T. M.; Fesler, L. W.; Mongan, R. D.
1980-01-01
Multidimensional heat conduction program computes transient temperature history and steady state temperatures of complex body geometries in three dimensions. Emphasis is placed on type of problems associated with Space Shuttle thermal protection system, but program could be used in thermal analysis of most three dimensional systems.
ALE3D Simulation of Heating and Violence in a Fast Cookoff Experiment with LX-10
McClelland, M A; Maienschein, J L; Howard, W M; Nichols, A L; deHaven, M R; Strand, O T
2006-06-26
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.
Variable-Conductance Heat Pipes
NASA Technical Reports Server (NTRS)
Antoniuk, D.
1986-01-01
In response to need to accurately and efficiently predict performance of variable-conductance heat pipes (VCHP's) incorporated in spacecraft thermalcontrol systems, computer code VCHPDA developed to interact with thermal analyzer programs such as SINDA (Systems Improved Numerical Differencing Analyzer). Calculates length of gas-blocked region and vapor temperature in active portion. Advantages of VCHPDA over prior programs improved accuracy, unconditional stability, and increased efficiency of solution resulting from novel approach and use of state-of-the-art numerical techniques for solving VCHP mathematical model. Code valuable tool in design and evaluation of advanced thermal-control systems using variable-conductance heat pipes. Written in FORTRAN IV for use on CDC 600 computers.
NASA Astrophysics Data System (ADS)
Lemus-Mondaca, Roberto A.; Vega-Gálvez, Antonio; Zambra, Carlos E.; Moraga, Nelson O.
2016-03-01
A 3D model considering heat and mass transfer for food dehydration inside a direct contact dryer is studied. The k- ɛ model is used to describe turbulent air flow. The samples thermophysical properties as density, specific heat, and thermal conductivity are assumed to vary non-linearly with temperature. FVM, SIMPLE algorithm based on a FORTRAN code are used. Results unsteady velocity, temperature, moisture, kinetic energy and dissipation rate for the air flow are presented, whilst temperature and moisture values for the food also are presented. The validation procedure includes a comparison with experimental and numerical temperature and moisture content results obtained from experimental data, reaching a deviation 7-10 %. In addition, this turbulent k- ɛ model provided a better understanding of the transport phenomenon inside the dryer and sample.
NASA Astrophysics Data System (ADS)
Courbet, C.; DICK, P.; Lefevre, M.; Wittebroodt, C.; Matray, J.; Barnichon, J.
2013-12-01
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.
Conductive-bridging random access memory: challenges and opportunity for 3D architecture.
Jana, Debanjan; Roy, Sourav; Panja, Rajeswar; Dutta, Mrinmoy; Rahaman, Sheikh Ziaur; Mahapatra, Rajat; Maikap, Siddheswar
2015-01-01
The performances of conductive-bridging random access memory (CBRAM) have been reviewed for different switching materials such as chalcogenides, oxides, and bilayers in different structures. The structure consists of an inert electrode and one oxidized electrode of copper (Cu) or silver (Ag). The switching mechanism is the formation/dissolution of a metallic filament in the switching materials under external bias. However, the growth dynamics of the metallic filament in different switching materials are still debated. All CBRAM devices are switching under an operation current of 0.1 μA to 1 mA, and an operation voltage of ±2 V is also needed. The device can reach a low current of 5 pA; however, current compliance-dependent reliability is a challenging issue. Although a chalcogenide-based material has opportunity to have better endurance as compared to an oxide-based material, data retention and integration with the complementary metal-oxide-semiconductor (CMOS) process are also issues. Devices with bilayer switching materials show better resistive switching characteristics as compared to those with a single switching layer, especially a program/erase endurance of >10(5) cycles with a high speed of few nanoseconds. Multi-level cell operation is possible, but the stability of the high resistance state is also an important reliability concern. These devices show a good data retention of >10(5) s at >85°C. However, more study is needed to achieve a 10-year guarantee of data retention for non-volatile memory application. The crossbar memory is benefited for high density with low power operation. Some CBRAM devices as a chip have been reported for proto-typical production. This review shows that operation current should be optimized for few microamperes with a maintaining speed of few nanoseconds, which will have challenges and also opportunities for three-dimensional (3D) architecture. PMID:25977660
Conductive-bridging random access memory: challenges and opportunity for 3D architecture
NASA Astrophysics Data System (ADS)
Jana, Debanjan; Roy, Sourav; Panja, Rajeswar; Dutta, Mrinmoy; Rahaman, Sheikh Ziaur; Mahapatra, Rajat; Maikap, Siddheswar
2015-04-01
The performances of conductive-bridging random access memory (CBRAM) have been reviewed for different switching materials such as chalcogenides, oxides, and bilayers in different structures. The structure consists of an inert electrode and one oxidized electrode of copper (Cu) or silver (Ag). The switching mechanism is the formation/dissolution of a metallic filament in the switching materials under external bias. However, the growth dynamics of the metallic filament in different switching materials are still debated. All CBRAM devices are switching under an operation current of 0.1 μA to 1 mA, and an operation voltage of ±2 V is also needed. The device can reach a low current of 5 pA; however, current compliance-dependent reliability is a challenging issue. Although a chalcogenide-based material has opportunity to have better endurance as compared to an oxide-based material, data retention and integration with the complementary metal-oxide-semiconductor (CMOS) process are also issues. Devices with bilayer switching materials show better resistive switching characteristics as compared to those with a single switching layer, especially a program/erase endurance of >105 cycles with a high speed of few nanoseconds. Multi-level cell operation is possible, but the stability of the high resistance state is also an important reliability concern. These devices show a good data retention of >105 s at >85°C. However, more study is needed to achieve a 10-year guarantee of data retention for non-volatile memory application. The crossbar memory is benefited for high density with low power operation. Some CBRAM devices as a chip have been reported for proto-typical production. This review shows that operation current should be optimized for few microamperes with a maintaining speed of few nanoseconds, which will have challenges and also opportunities for three-dimensional (3D) architecture.
North Cascadia heat flux and fluid flow from gas hydrates: Modeling 3-D topographic effects
NASA Astrophysics Data System (ADS)
Li, Hong-lin; He, Tao; Spence, George D.
2014-01-01
The 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.
Improved time-space method for 3-D heat transfer problems including global warming
Saitoh, T.S.; Wakashima, Shinichiro
1999-07-01
In this paper, the Time-Space Method (TSM) which has been proposed for solving general heat transfer and fluid flow problems was improved in order to cover global and urban warming. The TSM is effective in almost all-transient heat transfer and fluid flow problems, and has been already applied to the 2-D melting problems (or moving boundary problems). The computer running time will be reduced to only 1/100th--1/1000th of the existing schemes for 2-D and 3-D problems. However, in order to apply to much larger-scale problems, for example, global warming, urban warming and general ocean circulation, the SOR method (or other iterative methods) in four dimensions is somewhat tedious and provokingly slow. Motivated by the above situation, the authors improved the speed of iteration of the previous TSM by introducing the following ideas: (1) Timewise chopping: Time domain is chopped into small peaches to save memory requirement; (2) Adaptive iteration: Converged region is eliminated for further iteration; (3) Internal selective iteration: Equation with slow iteration speed in iterative procedure is selectively iterated to accelerate entire convergence; and (4) False transient integration: False transient term is added to the Poisson-type equation and the relevant solution is regarded as a parabolic equation. By adopting the above improvements, the higher-order finite different schemes and the hybrid mesh, the computer running time for the TSM is reduced to some 1/4600th of the conventional explicit method for a typical 3-D natural convection problem in a closed cavity. The proposed TSM will be more efficacious for large-scale environmental problems, such as global warming, urban warming and general ocean circulation, in which a tremendous computing time would be required.
Wan, Alwin Ming-Doug; Inal, Sahika; Williams, Tiffany; Wang, Karin; Leleux, Pierre; Estevez, Luis; Giannelis, Emmanuel P.; Fischbach, Claudia; Malliaras, George G.; Gourdon, Delphine
2015-01-01
We report the fabrication of three dimensional (3D) macroporous scaffolds made from poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) via an ice-templating method. The scaffolds offer tunable pore size and morphology, and are electrochemically active. When a potential is applied to the scaffolds, reversible changes take place in their electrical doping state, which in turn enables precise control over the conformation of adsorbed proteins (e.g., fibronectin). Additionally, the scaffolds support the growth of mouse fibroblasts (3T3-L1) for 7 days, and are able to electrically control cell adhesion and pro-angiogenic capability. These 3D matrix-mimicking platforms offer precise control of protein conformation and major cell functions, over large volumes and long cell culture times. As such, they represent a new tool for biological research with many potential applications in bioelectronics, tissue engineering, and regenerative medicine. PMID:26413300
The effect of anisotropic heat transport on magnetic islands in 3-D configurations
Schlutt, M. G.; Hegna, C. C.
2012-08-15
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.
NASA Astrophysics Data System (ADS)
Tao, W. Q.; Cheng, Y. P.; Lee, T. S.
2007-11-01
In this paper, a numerical investigation is performed for three-stage heat exchangers with plain plate fins and slit fins respectively, with a three-dimensional laminar conjugated model. The tubes are arranged in a staggered way, and heat conduction in fins is considered. In order to save the computer resource and speed up the numerical simulation, the numerical modeling is carried out stage by stage. In order to avoid the large pressure drop penalty in enhancing heat transfer, a slit fin is presented with the strip arrangement of “front coarse and rear dense” along the flow direction. The numerical simulation shows that, compared to the plain plate fin heat exchanger, the increase in the heat transfer in the slit fin heat exchanger is higher than that of the pressure drop, which proves the excellent performance of this slit fin. The fluid flow and heat transfer performance along the stages is also provided.
Lee, Sang-Heon; Jung, Jung-Hwan; Oh, Il-Kwon
2014-10-15
A novel 3D networked graphene-ferromagnetic hybrid can be easily fabricated using one-step microwave irradiation. By incorporating this hybrid material into shape memory polymers, the synergistic effects of fast speed and the enhancement of thermal conductivity and mechanical stiffness can be achieved. This can be broadly applicable to designing magneto-responsive shape memory polymers for multifunction applications. PMID:24912455
Electrical conduction mechanisms in PbSe and PbS nano crystals 3D matrix layer
NASA Astrophysics Data System (ADS)
Arbell, Matan; Hechster, Elad; Sarusi, Gabby
2016-02-01
A simulation study and measurements of the electrical conductance in a PbSe and PbS spherical Nano-crystal 3D matrix layer was carried out focusing on its dependences of Nano-crystal size distribution and size gradient along the layer thickness (z-direction). The study suggests a new concept of conductance enhancement by utilizing a size gradient along the layer thickness from mono-layer to the next mono-layer of the Nano-crystals, in order to create a gradient of the energy levels and thus improve directional conductance in this direction. A Monte Carlo simulation of the charge carriers path along the layer thickness of the Nano-crystals 3D matrix using the Miller-Abrahams hopping model was performed. We then compared the conductance characteristics of the gradual size 3D matrix layer to a constant-sized 3D matrix layer that was used as a reference in the simulation. The numerical calculations provided us with insights into the actual conductance mechanism of the PbSe and PbS Nano-crystals 3D matrix and explained the discrepancies in actual conductance and the variability in measured mobilities published in the literature. It is found that the mobility and thus conductance are dependent on a critical electrical field generated between two adjacent nano-crystals. Our model explains the conductance dependents on the: Cathode-Anode distance, the distance between the adjacent nano-crystals in the 3D matrix layer and the size distribution along the current direction. Part of the model (current-voltage dependence) was validated using a current-voltage measurements taken on a constant size normal distribution nano-crystals PbS layer (330nm thick) compared with the predicted I-V curves. It is shown that under a threshold bias, the current is very low, while after above a threshold bias the conductance is significantly increased due to increase of hopping probability. Once reaching the maximum probability the current tend to level-off reaching the maximal conductance available through the sequential hopping and nano crystals based layer behaves as a resistor under bias.
Raj, Kovummal Govind; Joy, Pattayil Alias
2015-06-28
The changes in the electrical transport properties and mechanism of conduction in disordered carbon, with the extent of graphitization, are studied and discussed. With heat treatment induced graphitic ordering, the electrical properties are considerably modified, inducing a crossover from strong localization to weak localization behavior. Accordingly, the conduction mechanism is modified from the 3-dimensional variable range hopping (3D VRH) model to the 2-dimensional weak localization (2D WL) model. Results show that carrier-carrier and carrier-phonon interactions play major roles in developing the weak localization behavior with the extent of graphitization. PMID:26035227
Conducting a 3D Converted Shear Wave Project to Reduce Exploration Risk at Wister, CA
Matlick, Skip; Walsh, Patrick; Rhodes, Greg; Fercho, Steven
2015-06-30
Ormat sited 2 full-size exploration wells based on 3D seismic interpretation of fractures, prior drilling results, and temperature anomaly. The wells indicated commercial temperatures (>300 F), but almost no permeability, despite one of the wells being drilled within 820 ft of an older exploration well with reported indications of permeability. Following completion of the second well in 2012, Ormat undertook a lengthy program to 1) evaluate the lack of observed permeability, 2) estimate the likelihood of finding permeability with additional drilling, and 3) estimate resource size based on an anticipated extent of permeability.
Heat Conduction of Air in Nano Spacing.
Zhang, Yao-Zhong; Zhao, Bo; Huang, Gai-Yan; Yang, Zhi; Zhang, Ya-Fei
2009-01-01
The scale effect of heat conduction of air in nano spacing (NS) is very important for nanodevices to improve their life and efficiency. By constructing a special technique, the changes of heat conduction of air were studied by means of measuring the heat conduction with heat conduction instrument in NS between the hot plate and the cooling plate. Carbon nanotubes were used to produce the nano spacing. The results show that when the spacing is small down to nanometer scale, heat conduction plays a prominent role in NS. It was found that the thickness of air is a non-linear parameter for demarcating the heat conduction of air in NS and the rate of heat conduction in unit area could be regard as a typical parameter for the heat conduction characterization at nanometer scale. PMID:20596486
Heat Conduction of Air in Nano Spacing
2009-01-01
The scale effect of heat conduction of air in nano spacing (NS) is very important for nanodevices to improve their life and efficiency. By constructing a special technique, the changes of heat conduction of air were studied by means of measuring the heat conduction with heat conduction instrument in NS between the hot plate and the cooling plate. Carbon nanotubes were used to produce the nano spacing. The results show that when the spacing is small down to nanometer scale, heat conduction plays a prominent role in NS. It was found that the thickness of air is a non-linear parameter for demarcating the heat conduction of air in NS and the rate of heat conduction in unit area could be regard as a typical parameter for the heat conduction characterization at nanometer scale. PMID:20596486
3D Bridged Carbon Nanoring/Graphene Hybrid Paper as a High-Performance Lateral Heat Spreader.
Zhang, Jianwei; Shi, Gang; Jiang, Cai; Ju, Su; Jiang, Dazhi
2015-12-01
Graphene paper (GP) has attracted great attention as a heat dissipation material due to its unique thermal transfer property exceeding the limit of graphite. However, the relatively poor thermal transfer properties in the normal direction of GP restricts its wider applications in thermal management. In this work, a 3D bridged carbon nanoring (CNR)/graphene hybrid paper is constructed by the intercalation of polymer carbon source and metal catalyst particles, and the subsequent in situ growth of CNRs in the confined intergallery spaces between graphene sheets through thermal annealing. Further investigation demonstrates that the CNRs are covalently bonded to the graphene sheets and highly improve the thermal transport in the normal direction of the CNR/graphene hybrid paper. This full-carbon architecture shows excellent heat dissipation ability and is much more efficient in removing hot spots than the reduced GP without CNR bridges. This highly thermally conductive CNR/graphene hybrid paper can be easily integrated into next generation commercial high-power electronics and stretchable/foldable devices as high-performance lateral heat spreader materials. This full-carbon architecture also has a great potential in acting as electrodes in supercapacitors or hydrogen storage devices due to the high surface area. PMID:26476622
NASA Astrophysics Data System (ADS)
Jalali, A.; Hulsen, M. A.; Norouzi, M.; Kayhani, M. H.
2013-05-01
This paper presents a numerical simulation of the developing flow and heat transfer of a viscoelastic fluid in a rectangular duct. In fully developed flow of a viscoelastic fluid in a non-circular duct, secondary flows normal to the flow direction are expected to enhance the rate of heat and mass transfer. On the other hand, properties such as viscosity, thermal conductivity, specific heat and relaxation time of the fluid are a function of temperature. Therefore, we developed a numerical model which solves the flow and energy equation simultaneously in three dimensional form. We included several equations of state to model the temperature dependency of the fluid parameters. The current paper is one of the first studies which present a 3D numerical simulation for developing viscoelastic duct flow that takes the dependency of flow parameters to the temperature into account. The rheological constitutive equation of the fluid is a common form of the Phan-Thien Tanner (PTT) model, which embodies both influences of elasticity and shear thinning in viscosity. The governing equations are discretized using the FTCS finite difference method on a staggered mesh. The marker-and-cell method is also employed to allocate the parameters on the staggered mesh, and static pressure is calculated using the artificial compressibility approach during the numerical simulation. In addition to report the results of flow and heat transfer in the developing region, the effect of some dimensionless parameters on the flow and heat transfer has also been investigated. The results are in a good agreement with the results reported by others in this field.
Severt, Sean Y; Ostrovsky-Snider, Nicholas A; Leger, Janelle M; Murphy, Amanda R
2015-11-18
Flexible and conductive biocompatible materials are attractive candidates for a wide range of biomedical applications including implantable electrodes, tissue engineering, and controlled drug delivery. Here, we demonstrate that chemical and electrochemical polymerization techniques can be combined to create highly versatile silk-conducting polymer (silk-CP) composites with enhanced conductivity and electrochemical stability. Interpenetrating silk-CP composites were first generated via in situ deposition of polypyrrole during chemical polymerization of pyrrole. These composites were sufficiently conductive to serve as working electrodes for electropolymerization, which allowed an additional layer of CP to be deposited on the surface. This sequential method was applied to both 2D films and 3D sponge-like silk scaffolds, producing conductive materials with biomimetic architectures. Overall, this two-step technique expanded the range of available polymers and dopants suitable for the synthesis of mechanically robust, biocompatible, and highly conductive silk-based materials. PMID:26544990
Effects of a radially varying electrical conductivity on 3D numerical dynamos
NASA Astrophysics Data System (ADS)
Gómez-Pérez, Natalia; Heimpel, Moritz; Wicht, Johannes
2010-07-01
The transition from liquid metal to silicate rock in the cores of the terrestrial planets is likely to be accompanied by a gradient in the composition of the outer core liquid. The electrical conductivity of a volatile-enriched liquid alloy can be substantially lower than a light-element-depleted fluid found close to the inner core boundary. In this paper, we investigate the effect of radially variable electrical conductivity on planetary dynamo action using an electrical conductivity that decreases exponentially as a function of radius. We find that numerical solutions with continuous, radially outward decreasing electrical conductivity profiles result in strongly modified flow and magnetic field dynamics, compared to solutions with homogeneous electrical conductivity. The force balances at the top of the simulated fluid determine the overall character of the flow. The relationship between Coriolis, and Lorentz forces near the outer core boundary controls the flow and magnetic field intensity and morphology of the system. Our results imply that a low conductivity layer near the top of Mercury's liquid outer core is consistent with its weak magnetic field.
NASA Astrophysics Data System (ADS)
Guerreiro, Nuno; Haberreiter, Margit; Hansteen, Viggo; Schmutz, Werner
2015-04-01
We study the properties of the small-scale heating events in the solar atmosphere in the nano flare and micro flare energy scale using 3D MHD simulations. We put forward a method to identify and track the heating events in time to study their life times, frequency distributions and spectral signatures. These results aim to better understand the observations from future space missions such as the EUI and SPICE instruments onboard Solar Orbiter and improve our knowledge of the role of small-scale heating events in the heating of the corona.
NASA Astrophysics Data System (ADS)
Malesa, M.; Kujawińska, M.; Malowany, K.; Siwek, B.
2013-04-01
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.
Brosten, T.R.; Day-Lewis, F. D.; Schultz, G.M.; Curtis, G.P.; Lane, J.W.
2011-01-01
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.
NASA Astrophysics Data System (ADS)
Sengupta, Parijat; Bellotti, Enrico
2015-10-01
The zero gap surface states of a 3D-topological insulator host highly mobile Dirac fermions with spin locked to the momentum. The high mobility attributed to the absence of back scattering is reduced in the presence of impurities on the surface. In particular, we discuss and compare scattering times for localised impurities on the surface, scattering between states of opposite helicity located on different surfaces coupled through a hybridisation potential and the role of magnetic impurities. Magnetic impurities give rise to an additional spin suppression factor. The role of warped bands and their influence on topological factors that can enhance the overall surface mobility is examined. Finally, employing a linearised Boltzmann equation approach, surface conductivity calculations for Dirac fermions in a 3D TI is outlined.
A fast technique applied to the analysis of Resistive Wall Modes with 3D conducting structures
Rubinacci, Guglielmo Liu, Yueqiang
2009-03-20
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)
Electromagnetic Scattering From a Rectangular Cavity Recessed in a 3-D Conducting Surface
NASA Technical Reports Server (NTRS)
Deshpande, M. D.; Reddy, C. J.
1995-01-01
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.
NASA Astrophysics Data System (ADS)
Gasch, Caley K.; Hengl, Tomislav; Gräler, Benedikt; Meyer, Hanna; Magney, Troy; Brown, David J.
2015-04-01
Dynamic soil data collected using automated sensor networks can facilitate our understanding of soil processes, but highly dimensional data may be difficult to analyze in a manner that incorporates correlation in properties through 3-dimensions and time (3D+T). We demonstrate two approaches to making continuous predictions of dynamic soil properties from fixed point observations. For this analysis, we used the Cook Farm data set, which includes hourly measurements of soil volumetric water content, temperature, and electrical conductivity at 42 points and five depths, collected over five years. We compare performance of two modeling frameworks. In the first framework we used random forest algorithms to fit a 3D+T regression model to make predictions of all three soil variables from 2- and 3-dimensional, temporal, and spatio-temporal covariates. In the second framework we developed a 3D+T kriging model after detrending the observations for depth-dependent seasonal effects. The results show that both models accurately predicted soil temperature, but the kriging model outperformed the regression model according to cross-validation; it explained 37%, 96%, and 16% of the variability in water content, temperature, and electrical conductivity respectively versus 34%, 93%, and 4% explained by the random forest model. The full random forest regression model had high goodness-of-fit for all variables, which was reduced in cross-validation. Temporal model components (i.e. day of the year) explained most of the variability in observations. The seamless predictions of 3D+T data produced from this analysis can assist in understanding soil processes and how they change through a season, under different land management scenarios, and how they relate to other environmental processes.
Thermal Conductivity of 3D CNT-Polymer Composites with Controlled Dispersion
NASA Astrophysics Data System (ADS)
Klittich, Mena; Wang, Xue; Dhinojwala, Ali
The high thermal conductivity of isolated carbon nanotubes (CNTs) has inspired its use as a thermal filler for insulative polymers. However, the performance of these composites has consistently been sub par. Extensive analyses of these complex systems have resulted in the conclusion that resistance at the CNT/polymer interface due to phonon mismatch and poor physical binding, as well as the weakly bonded tube-tube interactions restrict the effectiveness of CNTs in practice. Experimental comparisons of CNT treatments, coatings, functionalization, and interactions with various polymers have proved challenging, due to the interconnected nature of the composite properties. Here, we have reversed the paradigm and used a constant CNT structure that is then modified post-growth to allow for direct comparisons of polymer composites.
NASA Astrophysics Data System (ADS)
Smirnov, M. Yu.; Korja, T.; Pedersen, L. B.
2009-04-01
Two electromagnetic arrays are used in the EMMA project to study conductivity structure of the Archaean lithosphere in the Fennoscandian Shield. The first array was operated during almost one year, while the second one was running only during the summer time. Twelve 5-components magnetotelluric instruments with fluxgate magnetometers recorded simultaneously time variations of Earth's natural electromagnetic field at the sites separated by c. 30 km. To better control the source field and to obtain galvanic distortion free responses we have applied horizontal spatial gradient (HSG) technique to the data. The study area is highly inhomogeneous, thus classical HSG might give erroneous results. The method was extended to include anomalous field effects by implementing multivariate analysis. The HSG transfer functions were then used to control static shift distortions of apparent resistivities. During the BEAR experiment 1997-2002, the conductance map of entire Fennoscandia was assembled and finally converted into 3D volume resistivity model. We have used the model, refined it to get denser grid around measurement area and calculated MT transfer functions after 3D modeling. We have used trial-and-error method in order to further improve the model. The data set was also inverted using 3D code of Siripunvaraporn (2005). In the first stage we have used homogeneous halfspace as starting model for the inversion. In the next step we have used final 3D forward model as apriori model. The usage of apriori information significantly stabilizes the inverse solution, especially in case of a limited amount of data available. The results show that in the Archaean Domain a conductive layer is found in the upper/middle crust on contrary to previous results from other regions of the Archaean crust in the Fennoscandian Shield. Data also suggest enhanced conductivity at the depth of c. 100 km. Conductivity below the depth of 200-250 km is lower than that of the laboratory based estimates of dry olivine. The last finding suggests that the base of lithosphere is very deep beneath the central part of the cratonic Fennoscandia.
Karanasiou, I S; Uzunoglu, N K
2004-01-01
The capability of detecting electrical conductivity variations using focused microwave radiometry, a method used in clinical applications for temperature distribution imaging of subcutaneous tissues, is discussed in the present study. A novel microwave radiometric system operating at 3.5 GHz, including an ellipsoidal conductive wall cavity, which provides the required beamforming and focusing, is developed. The system is capable of providing distribution measurements of the product of conductivity and temperature of any object being at a temperature above the absolute zero. The implemented experimental procedure is based on the results of an electromagnetic numerical analysis using a semianalytical method which was developed in order to compute the focusing properties of the ellipsoidal reflector. Each measurement is realized by placing the region of interest in the area of the first focus of the cavity and collecting the radiation converged at the second by an almost isotropic dipole antenna connected to a sensitive radiometer. Experimental data from cylindrical shaped saline or de-ionized water filled tank phantoms in which saline solutions of different concentrations were infused, provide promising results concerning the system's ability of detecting conductivity variations. Future research is needed in order to elucidate the potential of the proposed methodology to be used for brain conductivity measurements. PMID:17272189
NASA Astrophysics Data System (ADS)
Hübert, Juliane; García Juanatey, María.; Tryggvason, Ari; Malehmir, Alireza
2010-05-01
We present results from a magnetotelluric (MT) case study in Kristineberg, a well investigated mining area in the Skellefte Ore District, Northern Sweden. The study area is known for the presence of VHMS (volcanic hosted massive sulfide) deposits and has been studied intensively using geological observations and different geophysical methods (reflection seismics, potential field methods). This study is embedded in the framework of building a crustal scale 3D geological model. During the past three years several MT measurements along three N-S running profile lines were conducted. The 2D model from the pilot study collected 2007 on the profile furthest to the West associated the main electrical features to the Revsund granites in the south, the Skellefte volcanic and metasedimentary rocks in the center of the profile and a possible sedimentary basement at 3 km depth. The model was derived from 2D determinant inversion with an assumed electrical strike direction of 75 °. The results were in good agreement with former interpretations made from reflection seismic studies. Nevertheless the complexity of the structures increases the urge to test the 2D approximation of the model with a complete 3D inversion of the impedance tensor in an array of measurement points. In 2008 and 2009 additional MT measurements in the East closer to the mine were collected. The new data shows that the 2D assumption is not consistent overall. Indicated also by the tipper the most dominant feature in the second profile is a very strong and shallow conductor. It has been associated with the contact between metasediments and volcanics and seems to be very localized to the west of profile, but is not seen in the easternmost profile. Also the presence and extension of a very strong conductor at depth, which was discovered as a major crustal anomaly already in the eighties and was recently interpreted as the reflective north dipping Bothnian basement, is further studied with the new data. To perform a 3D inversion the data coverage was improved with additional measurement points between the profiles. A 3D inversion model of the central part of the study area was derived to identify and position the off profile features. Both 2D and 3D models help to reveal the complicated geology of the area and estimate the dimensions of the lithological units at depth. They offer a vital component in the interpretation of geological observations and the seismic reflection data to improve the 3D model of the subsurface.
Xiao, Chengliang; Wang, Yaxing; Chen, Lanhua; Yin, Xuemiao; Shu, Jie; Sheng, Daopeng; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Wang, Shuao
2015-12-01
The limited long-term hydrolytic stability of rapidly emerging 3D-extended framework materials (MOFs, COFs, MOPs, etc.) is still one of major barriers for their practical applications as new solid-state electrolytes in fuel cells. To obtain hydrolytically stable materials, two H2 PO4 (-) -exchanged 3D inorganic cationic extended frameworks (CEFs) were successfully prepared by a facile anion-exchange method. Both anion-exchanged CEFs (YbO(OH)P and NDTBP) show significantly enhanced proton conductivity when compared with the original materials (YbO(OH)Cl and NDTB) with an increase of up to four orders-of-magnitude, reaching 2.36×10(-3) and 1.96×10(-2) S cm(-1) at 98 % RH and 85 °C for YbO(OH)P and NDTBP, respectively. These values are comparable to the most efficient proton-conducting MOFs. In addition, these two anion-exchanged materials are stable in boiling water, which originates from the strong electrostatic interaction between the H2 PO4 (-) anion and the cationic host framework, showing a clear advance over all the acid-impregnated materials (H2 SO4 @MIL-101, H3 PO4 @MIL-101, and H3 PO4 @Tp-Azo) as practical solid-state fuel-cell electrolytes. This work offers a new general and efficient approach to functionalize 3D-extended frameworks through an anion-exchange process and achieves water-stability with ultra-high proton conductivity above 10(-2) S cm(-1) . PMID:26489981
Tao, Yulun; Shen, Yuhua; Yang, Liangbao; Han, Bin; Huang, Fangzhi; Li, Shikuo; Chu, Zhuwang; Xie, Anjian
2012-06-21
While the number of man-made nano superstructures realized by self-assembly is growing in recent years, assemblies of conductive polymer nanocrystals, especially for superlattices, are still a significant challenge, not only because of the simplicity of the shape of the nanocrystal building blocks and their interactions, but also because of the poor control over these parameters in the fabrication of more elaborate nanocrystals. Here, we firstly report a facile and general route to a new generation of 3D layered superlattices of polyaniline doped with CSA (PANI-CSA) and show how PANI crystallize and self-assemble, in a suitable single solution environment. In cyclohexane, 1D amorphous nanofibers transformed to 1D nanorods as building blocks, and then to 2D single-crystal nanosheets with a hexagonal phase, and lastly to 3D ordered layered superlattices with the narrowest polydispersity value (M(w)/M(n) = 1.47). Remarkably, all the instructions for the hierarchical self-assembly are encoded in the layered shape in other non-polar solvents (hexane, octane) and their conductivity in the π-π stacking direction is improved to about 50 S cm(-1), which is even higher than that of the highest previously reported value (16 S cm(-1)). The method used in this study is greatly expected to be readily scalable to produce superlattices of conductive polymers with high quality and low cost. PMID:22609947
Performance of a variable conductance heat pipe heat exchanger
NASA Astrophysics Data System (ADS)
Chancelor, P. D.
1983-02-01
The performance of an air to air heat exchanger in which heat is transferred to a finned evaporator and from a finned condenser via a heat pipe was evaluated. The variable conductance heat pipe is to the condenser fins a heat source and to the evaporator fins a heat sink. The principal advantage of the variable conductance heat pipe heat exchanger is the ability to modulate power transfer independent of stream inlet conditions. This type of heat exchanger is of particular interest to the commercial aircraft industry because of its control system. The results from this research will help to provide the engineer with experimental data necessary to design a full scale prototype heat exchanger to be tested in situ.
Al-Alfy, I M; Nabih, M A
2013-03-01
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 μWm(-3) to 2.2 μWm(-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 μWm(-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
Heat conduction fronts in planetary nebulae
NASA Technical Reports Server (NTRS)
Soker, Noam
1994-01-01
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.
NASA Astrophysics Data System (ADS)
Spichak, V. V.
2011-01-01
Possibilities for three-dimensional (3D) magnetotelluric (MT) sounding of local objects contained in the Earth's crust are estimated in a case study of the magma chamber of the Vesuvius volcano. Stochastic inversion of the model MT data by the Markov Chain Monte Carlo (MCMC) method has shown that the most efficient approach is not simultaneous but successive estimation of the geometry and the depth of the anomaly and the assessment of the conductivity distribution within the anomalous region. A zone of equivalence is revealed between the a priori estimate of the depth of the anomalous zone and the a posteriori distribution of electric conductivity within it. Based on the present estimation and previous results, an algorithm for determination of the parameters of local crustal anomaly is proposed.
Sekar, Pandiaraj; Anothumakkool, Bihag; Kurungot, Sreekumar
2015-04-15
Here, we report synthesis of a 3-dimensional (3D) porous polyaniline (PANI) anchored on pillared graphene (G-PANI-PA) as an efficient charge storage material for supercapacitor applications. Benzoic acid (BA) anchored graphene, having spatially separated graphene layers (G-Bz-COOH), was used as a structure controlling support whereas 3D PANI growth has been achieved by a simple chemical oxidation of aniline in the presence of phytic acid (PA). The BA groups on G-Bz-COOH play a critical role in preventing the restacking of graphene to achieve a high surface area of 472 m(2)/g compared to reduced graphene oxide (RGO, 290 m(2)/g). The carboxylic acid (-COOH) group controls the rate of polymerization to achieve a compact polymer structure with micropores whereas the chelating nature of PA plays a crucial role to achieve the 3D growth pattern of PANI. This type of controlled interplay helps G-PANI-PA to achieve a high conductivity of 3.74 S/cm all the while maintaining a high surface area of 330 m(2)/g compared to PANI-PA (0.4 S/cm and 60 m(2)/g). G-PANI-PA thus conceives the characteristics required for facile charge mobility during fast charge-discharge cycles, which results in a high specific capacitance of 652 F/g for the composite. Owing to the high surface area along with high conductivity, G-PANI-PA displays a stable specific capacitance of 547 F/g even with a high mass loading of 3 mg/cm(2), an enhanced areal capacitance of 1.52 F/cm(2), and a volumetric capacitance of 122 F/cm(3). The reduced charge-transfer resistance (RCT) of 0.67 Ω displayed by G-PANI-PA compared to pure PANI (0.79 Ω) stands out as valid evidence of the improved charge mobility achieved by the system by growing the 3D PANI layer along the spatially separated layers of the graphene sheets. The low RCT helps the system to display capacitance retention as high as 65% even under a high current dragging condition of 10 A/g. High charge/discharge rates and good cycling stability are the other highlights of the supercapacitor system derived from this composite material. PMID:25783045
NASA Astrophysics Data System (ADS)
Tao, Yulun; Shen, Yuhua; Yang, Liangbao; Han, Bin; Huang, Fangzhi; Li, Shikuo; Chu, Zhuwang; Xie, Anjian
2012-05-01
While the number of man-made nano superstructures realized by self-assembly is growing in recent years, assemblies of conductive polymer nanocrystals, especially for superlattices, are still a significant challenge, not only because of the simplicity of the shape of the nanocrystal building blocks and their interactions, but also because of the poor control over these parameters in the fabrication of more elaborate nanocrystals. Here, we firstly report a facile and general route to a new generation of 3D layered superlattices of polyaniline doped with CSA (PANI-CSA) and show how PANI crystallize and self-assemble, in a suitable single solution environment. In cyclohexane, 1D amorphous nanofibers transformed to 1D nanorods as building blocks, and then to 2D single-crystal nanosheets with a hexagonal phase, and lastly to 3D ordered layered superlattices with the narrowest polydispersity value (Mw/Mn = 1.47). Remarkably, all the instructions for the hierarchical self-assembly are encoded in the layered shape in other non-polar solvents (hexane, octane) and their conductivity in the π-π stacking direction is improved to about 50 S cm-1, which is even higher than that of the highest previously reported value (16 S cm-1). The method used in this study is greatly expected to be readily scalable to produce superlattices of conductive polymers with high quality and low cost.While the number of man-made nano superstructures realized by self-assembly is growing in recent years, assemblies of conductive polymer nanocrystals, especially for superlattices, are still a significant challenge, not only because of the simplicity of the shape of the nanocrystal building blocks and their interactions, but also because of the poor control over these parameters in the fabrication of more elaborate nanocrystals. Here, we firstly report a facile and general route to a new generation of 3D layered superlattices of polyaniline doped with CSA (PANI-CSA) and show how PANI crystallize and self-assemble, in a suitable single solution environment. In cyclohexane, 1D amorphous nanofibers transformed to 1D nanorods as building blocks, and then to 2D single-crystal nanosheets with a hexagonal phase, and lastly to 3D ordered layered superlattices with the narrowest polydispersity value (Mw/Mn = 1.47). Remarkably, all the instructions for the hierarchical self-assembly are encoded in the layered shape in other non-polar solvents (hexane, octane) and their conductivity in the π-π stacking direction is improved to about 50 S cm-1, which is even higher than that of the highest previously reported value (16 S cm-1). The method used in this study is greatly expected to be readily scalable to produce superlattices of conductive polymers with high quality and low cost. Electronic supplementary information (ESI) available: SEM, and TEM images. See DOI: 10.1039/c2nr30743j
Coupled three-dimensional conduction and natural convection heat transfer
NASA Astrophysics Data System (ADS)
Tolpadi, Anil Kumar
1987-09-01
A numerical and experimental investigation of three-dimensional natural convection heat transfer coupled with conduction was performed. This general problem is of great importance because of its widespread applicability in areas such as compact natural convection heat exchangers, cooling of electronic equipment, and porous media flows. The determination of flow patterns and heat transfer coefficients in such situations is necessary because of its practical use in various industries. A vectorized finite difference code was developed for the Cray-2 supercomputer which has the capability of simulating a wide class of three-dimensional coupled conduction-convection problems. This program numerically solves the transient form of the complete laminar Navier-Stokes equations of motion using the vorticity-vector potential methods. Using this program, numerical solutions were obtained for 3-D natural convection from a horizontal isothermal heat exchanger tube with an attached circular cooling fin array. Experiments were performed to measure three-dimensional temperature fields using Mach-Zehnder interferometry. Software was developed to digitize and process fringe patterns and inversion algorithms used to compute the 3-D temperature field.
Evidence for two discrete fluid-flow regimes below Hydrate Ridge from 3D heat-flow modeling
NASA Astrophysics Data System (ADS)
Hornbach, M. J.; Bangs, N. L.; Berndt, C.
2010-12-01
High resolution 3D seismic data collected at the south Hydrate Ridge vent site in 2008 reveal a strong bottom-simulating reflection (BSR) that represents the base of the hydrate stability zone where free gas exist below and methane hydrate is stable above. The hydrate phase boundary is weakly dependent on pressure and strongly dependent on temperature at this depth; because of this, the depth of the BSR at Hydrate Ridge offers critical information about temperature that can be used to infer fluid flow across the region. Here, using a 3D finite-difference heat-flow model, we compare modeled steady-state diffusive heat-flow conditions with actual conditions at Hydrate Ridge based directly on BSR depth. The 3D heat-flow model, which we developed and tested at several hydrate sites, accounts fully for 3D affects including thermal refraction, hydrostatic pressure changes and variations in bottom water temperature with depth. It accurately predicts BSR depths at known low-flux environments, such as Blake Ridge, and therefore can be used to ascertain where advection or dynamic heat-flow exists below Hydrate Ridge. Comparison of model-predicted steady-state BSR depths at Hydrate Ridge with actual BSR depth reveals two anomalous zones where the BSR is 10-50 m shallower than predicted. The first BSR pull-up zone takes the shape of a narrow, ~500 m-wide, bulls-eye pattern directly below the vent at the summit of south Hydrate Ridge. This pattern indicates near-vertical fluid advection at this site in which fluids migrate through overlying strata. The second site where the BSR shallows, ~3 km northeast of the vent, indicates a very different heat-flow regime. Here, The BSR broadly shallows over several square kilometers, but abruptly terminates to the west, indicative of a sharp change in heat-flow. We attribute this abrupt lateral step in the BSR to fluid flow along dipping stratigraphic horizons that extend into the hydrate stability zone. Fluid flow at this second site therefore appears controlled primarily by stratigraphy. BSR shoaling is more extreme at this site (>50 m) suggesting a higher heat flow anomaly covering an area at least 5 times larger than the anomaly at the S. Hydrate Ridge summit. We therefore suggest that either higher or more sustained fluid flow may actually be occurring at the second site than below the vent at S. Hydrate Ridge. Whether a new vent exists, is in decline, or is developing at this second site remains unclear.
Information filtering via biased heat conduction
NASA Astrophysics Data System (ADS)
Liu, Jian-Guo; Zhou, Tao; Guo, Qiang
2011-09-01
The process of heat conduction has recently found application in personalized recommendation [Zhou , Proc. Natl. Acad. Sci. USA PNASA60027-842410.1073/pnas.1000488107107, 4511 (2010)], which is of high diversity but low accuracy. By decreasing the temperatures of small-degree objects, we present an improved algorithm, called biased heat conduction, which could simultaneously enhance the accuracy and diversity. Extensive experimental analyses demonstrate that the accuracy on MovieLens, Netflix, and Delicious datasets could be improved by 43.5%, 55.4% and 19.2%, respectively, compared with the standard heat conduction algorithm and also the diversity is increased or approximately unchanged. Further statistical analyses suggest that the present algorithm could simultaneously identify users' mainstream and special tastes, resulting in better performance than the standard heat conduction algorithm. This work provides a creditable way for highly efficient information filtering.
Information filtering via biased heat conduction.
Liu, Jian-Guo; Zhou, Tao; Guo, Qiang
2011-09-01
The process of heat conduction has recently found application in personalized recommendation [Zhou et al., Proc. Natl. Acad. Sci. USA 107, 4511 (2010)], which is of high diversity but low accuracy. By decreasing the temperatures of small-degree objects, we present an improved algorithm, called biased heat conduction, which could simultaneously enhance the accuracy and diversity. Extensive experimental analyses demonstrate that the accuracy on MovieLens, Netflix, and Delicious datasets could be improved by 43.5%, 55.4% and 19.2%, respectively, compared with the standard heat conduction algorithm and also the diversity is increased or approximately unchanged. Further statistical analyses suggest that the present algorithm could simultaneously identify users' mainstream and special tastes, resulting in better performance than the standard heat conduction algorithm. This work provides a creditable way for highly efficient information filtering. PMID:22060533
Cryogenic regenerator including sarancarbon heat conduction matrix
NASA Technical Reports Server (NTRS)
Jones, Jack A. (Inventor); Petrick, S. Walter (Inventor); Britcliffe, Michael J. (Inventor)
1989-01-01
A saran carbon matrix is employed to conduct heat through the heat storing volume of a cryogenic regenerator. When helium is adsorbed into the saran carbon matrix, the combination exhibits a volumetric specific heat much higher than previously used lead balls. A helium adsorbed saran regenerator should allow much lower refrigerator temperatures than those practically obtainable with lead based regenerators for regenerator type refrigeration systems.
3D modelling of heating of thermionic cathodes by high-pressure arc plasmas
NASA Astrophysics Data System (ADS)
Benilov, M. S.; Carpaij, M.; Cunha, M. D.
2006-05-01
Numerical investigation of steady-state interaction of a high-pressure argon plasma with a cylindrical tungsten cathode is reported. A whole 'zoo' of very diverse modes of current transfer is revealed. Detailed results are given for the first five (three-dimensional) 3D spot modes, four of them branching off from the diffuse mode and one from the first axially symmetric spot mode. Divergences in the general pattern of solutions, which have been present in preceding works, are resolved. Hypotheses on stability of steady-state solutions, available in the literature, are analysed. It is found that these hypotheses provide an explanation of the fact that the transition between diffuse and spot modes is difficult to reproduce in the experiment but they do not explain the indication that it is the low-voltage branch of the first 3D spot mode that seems to occur in the experiment. Thus, the question of stability of steady-state solutions remains open: an accurate stability analysis, as well as additional experimental information is required.
A numerical investigation of the 3-D flow in shell and tube heat exchangers
Prithiviraj, M.; Andrews, M.J.
1996-12-31
A three-dimensional computer program for simulation of the flow and heat transfer inside Shell and Tube Heat Exchangers has been developed. The simulation of shell and tube heat exchangers is based on a distributed resistance method that uses a modified two equation {kappa}-{epsilon} turbulence model along with non-equilibrium wall functions. Volume porosities and non-homogeneous surface permeabilities account for the obstructions due to the tubes and arbitrary arrangement of baffles. Sub-models are described for baffle-shell and baffle-tube leakage, shellside and tubeside heat transfer, with geometry generators for tubes, baffles, and nozzle inlets and outlets. The sub-models in HEATX use parameters that have not been altered from their published values. Computed heat transfer and pressure drop are compared with experimental data from the Delaware project (Bell, 1963). Numerically computed pressure drops are also compared for different baffle cuts, and different number of baffles with the experiments of Halle et al. (1984) which were performed in an industrial sized heat exchanger at Argonne National Labs. Discussion of the results is given with particular reference to global and local properties such as pressure drop, temperature variation, and heat transfer coefficients. Good agreement is obtained between the experiments and HEATX computations for the shellside pressure drop and outlet temperatures for the shellside and tubeside streams.
Wang, Yaxing; Tao, Zetian; Yin, Xuemiao; Shu, Jie; Chen, Lanhua; Sheng, Daopeng; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Wang, Shuao
2015-10-19
The preparation of proton-conducting materials that are functional and stable at intermediate temperatures (393-573 K) is a focal point of fuel cell development. The purely inorganic material, HNd(IO3)4, which possesses a dense 3D framework structure, can reach a maximum of 4.6 × 10(-4) S·cm(-1) at 353 K and 95% relative humidity and exhibit a high conductivity of 8.0 × 10(-5) S·cm(-1) from 373 to 553 K under the flow of wet N2. HNd(IO3)4 exhibits a variety of improvements including high thermal stability, low solubility in water, and resistance to reducing atmosphere. The proton conductivity in such a wide temperature range originates from the intrinsic liberated protons in the structure and the resulting 1D hydrogen-bonding network confirmed by bond valence sum calculation and solid-state NMR analysis. Moreover, two different activation energies are observed in different temperature regions (0.23 eV below 373 K and 0.026 eV from 373 to 553 K), indicating that two types of proton motion are responsible for proton diffusion, as further domenstrated by temperature-dependent open-circuit voltage hysteresis in a tested fuel cell assembly as well as variable-temperature and double quantum filtered solid-state NMR measurements. PMID:26444097
Aerodynamic heating on 3-D bodies including the effects of entropy-layer swallowing
NASA Technical Reports Server (NTRS)
Dejarnette, F. R.; Hamilton, H. H.
1974-01-01
A relatively simple method was developed previously (authors, 1973) for calculating laminar, transitional, and turbulent heating rates on three-dimensional bodies in hypersonic flows. This method was shown to yield reasonably accurate results for laminar heating on blunted circular and elliptical cones and an earlier version of the space shuttle vehicle. As the boundary layer along the surface grows, more and more of the inviscid-flow mass is entrained into the boundary layer, and the streamlines which passed through the nearly normal portion of the bow shock wave are 'swallowed' by the boundary layer. This phenomenon is often referred to as entropy-layer or streamline swallowing, and it can have a significant effect on the calculated heating rates. An approximate, yet simple, method for including the effects of entropy-layer swallowing in the heating-rate calculations is given.
Nakagawa, Yoshitaka; Kageyama, Hiroyuki; Matsumoto, Riho; Oaki, Yuya; Imai, Hiroaki
2015-11-28
Orientation-controlled 2D and 3D microarrays of Mn3O4 nanocuboids that were mediated by a conductive polymer were fabricated by evaporation-induced self-assembly of the oxide nanoblocks and subsequent polymerization of pyrrole in the interparticle spaces. Free-standing mesoporous polypyrroles (PPy) having chain- and square-grid-like nanovoid arrays were obtained as replicas of the composite assemblies by dissolving the oxide nanoblocks. The PPy-mediated manganese oxide arrays exhibited stable electrochemical performance as an ultrathin anode of a lithium-ion secondary battery. PMID:26508371
NASA Astrophysics Data System (ADS)
Fang, Zhufeng; Bogena, Heye; Kollet, Stefan; Vereecken, Harry
2016-05-01
In distributed hydrological modelling one often faces the problem that input data need to be aggregated to match the model resolution. However, aggregated data may be too coarse for the parametrization of the processes represented. This dilemma can be circumvented by the adjustment of certain model parameters. For instance, the reduction of local hydraulic gradients due to spatial aggregation can be partially compensated by increasing soil hydraulic conductivity. In this study, we employed the information entropy concept for the scale dependent parameterization of soil hydraulic conductivity. The loss of information content of terrain curvature as consequence of spatial aggregation was used to determine an amplification factor for soil hydraulic conductivity to compensate the resulting retardation of water flow. To test the usefulness of this approach, continuous 3D hydrological simulations were conducted with different spatial resolutions in the highly instrumented Wüstebach catchment, Germany. Our results indicated that the introduction of an amplification factor can effectively improve model performances both in terms of soil moisture and runoff simulation. However, comparing simulated soil moisture pattern with observation indicated that uniform application of an amplification factor can lead to local overcorrection of soil hydraulic conductivity. This problem could be circumvented by applying the amplification factor only to model grid cells that suffer from high information loss. To this end, we tested two schemes to define appropriate location-specific correction factors. Both schemes led to improved model performance both in terms of soil water content and runoff simulation. Thus, we anticipate that our proposed scaling approach is useful for the application of next-generation hyper-resolution global land surface models.
NASA Astrophysics Data System (ADS)
Meqbel, N. M.; Egbert, G. D.; Kelbert, A.
2011-12-01
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.
NASA Astrophysics Data System (ADS)
Umar Alkali, Adam; Lenggo Ginta, Turnad; Majdi Abdul-Rani, Ahmad
2015-04-01
This paper presents a 3D transient finite element modelling of the workpiece temperature field produced during the travelling heat sourced from oxyacetylene flame. The proposed model was given in terms of preheat-only test applicable during thermally enhanced machining using the oxyacetylene flame as a heat source. The FEA model as well as the experimental test investigated the surface temperature distribution on 316L stainless steel at scanning speed of 100mm/min, 125mm/min 160mm/min, 200mm/min and 250mm/min. The parametric properties of the heat source maintained constant are; lead distance Ld =10mm, focus height Fh=7.5mm, oxygen gas pressure Poxy=15psi and acetylene gas pressure Pacty=25psi. An experimental validation of the temperature field induced on type 316L stainless steel reveal that temperature distribution increases when the travelling speed decreases.
Modeling a Printed Circuit Heat Exchanger with RELAP5-3D for the Next Generation Nuclear Plant
Not Available
2010-12-01
The main purpose of this report is to design a printed circuit heat exchanger (PCHE) for the Next Generation Nuclear Plant and carry out Loss of Coolant Accident (LOCA) simulation using RELAP5-3D. Helium was chosen as the coolant in the primary and secondary sides of the heat exchanger. The design of PCHE is critical for the LOCA simulations. For purposes of simplicity, a straight channel configuration was assumed. A parallel intermediate heat exchanger configuration was assumed for the RELAP5 model design. The RELAP5 modeling also required the semicircular channels in the heat exchanger to be mapped to rectangular channels. The initial RELAP5 run outputs steady state conditions which were then compared to the heat exchanger performance theory to ensure accurate design is being simulated. An exponential loss of pressure transient was simulated. This LOCA describes a loss of coolant pressure in the primary side over a 20 second time period. The results for the simulation indicate that heat is initially transferred from the primary loop to the secondary loop, but after the loss of pressure occurs, heat transfers from the secondary loop to the primary loop.
3D Numerical Simulation of Turbulent Buoyant Flow and Heat Transport in a Curved Open Channel
Technology Transfer Automated Retrieval System (TEKTRAN)
A three-dimensional buoyancy-extended version of kappa-epsilon turbulence model was developed for simulating the turbulent flow and heat transport in a curved open channel. The density- induced buoyant force was included in the model, and the influence of temperature stratification on flow field was...
NASA Astrophysics Data System (ADS)
Nakagawa, Yoshitaka; Kageyama, Hiroyuki; Matsumoto, Riho; Oaki, Yuya; Imai, Hiroaki
2015-11-01
Orientation-controlled 2D and 3D microarrays of Mn3O4 nanocuboids that were mediated by a conductive polymer were fabricated by evaporation-induced self-assembly of the oxide nanoblocks and subsequent polymerization of pyrrole in the interparticle spaces. Free-standing mesoporous polypyrroles (PPy) having chain- and square-grid-like nanovoid arrays were obtained as replicas of the composite assemblies by dissolving the oxide nanoblocks. The PPy-mediated manganese oxide arrays exhibited stable electrochemical performance as an ultrathin anode of a lithium-ion secondary battery.Orientation-controlled 2D and 3D microarrays of Mn3O4 nanocuboids that were mediated by a conductive polymer were fabricated by evaporation-induced self-assembly of the oxide nanoblocks and subsequent polymerization of pyrrole in the interparticle spaces. Free-standing mesoporous polypyrroles (PPy) having chain- and square-grid-like nanovoid arrays were obtained as replicas of the composite assemblies by dissolving the oxide nanoblocks. The PPy-mediated manganese oxide arrays exhibited stable electrochemical performance as an ultrathin anode of a lithium-ion secondary battery. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05912g
N. A. Anderson; P. Sabharwall
2014-01-01
The Next Generation Nuclear Plant project is aimed at the research and development of a helium-cooled high-temperature gas reactor that could generate both electricity and process heat for the production of hydrogen. The heat from the high-temperature primary loop must be transferred via an intermediate heat exchanger to a secondary loop. Using RELAP5-3D, a model was developed for two of the heat exchanger options a printed-circuit heat exchanger and a helical-coil steam generator. The RELAP5-3D models were used to simulate an exponential decrease in pressure over a 20 second period. The results of this loss of coolant analysis indicate that heat is initially transferred from the primary loop to the secondary loop, but after the decrease in pressure in the primary loop the heat is transferred from the secondary loop to the primary loop. A high-temperature gas reactor model should be developed and connected to the heat transfer component to simulate other transients.
NASA Astrophysics Data System (ADS)
Brykina, Irina G.
2014-12-01
The three-dimensional hypersonic rarefied gas flow over blunt bodies in the transitional flow regime is studied. The 3D thin viscous shock layer equations are solved by the asymptotic method developed for low Re numbers. The simple analytical solution is obtained for heat transfer and skin friction coefficients as functions of flow parameters and body geometry parameters. The values of these coefficients approach their values in the free molecular flow at unit accommodation coefficient as Reynolds number tends to zero. Comparison with DSMC solutions is carried out.
Transient Heat Conduction Simulation around Microprocessor Die
NASA Astrophysics Data System (ADS)
Nishi, Koji
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.
NASA Astrophysics Data System (ADS)
Vinsard, G.; Dufour, S.; Saatdjian, E.; Mota, J. P. B.
2016-03-01
Chaotic advection can effectively enhance the heat transfer rate between a boundary and fluids with high Prandtl number. These fluids are usually highly viscous and thus turbulent agitation is not a viable solution since the energy required to mix the fluid would be prohibitive. Here, we analyze previously obtained results on chaotic advection and heat transfer in two similar 2-D periodic flows and on their corresponding 3-D periodic flows when an axial velocity component is superposed. The two flows studied are the flow between eccentric rotating cylinders and the flow between confocal ellipses. For both of these flows the analysis is simplified because the Stokes equations can be solved analytically to obtain a closed form solution. For both 2-D periodic flows, we show that chaotic heat transfer is enhanced by the displacement of the saddle point location during one period. Furthermore, the enhancement by chaotic advection in the elliptical geometry is approximately double that obtained in the cylindrical geometry because there are two saddle points instead of one. We also explain why, for high eccentricity ratios, there is no heat transfer enhancement in the cylindrical geometry. When an axial velocity component is added to both of these flows so that they become 3-D, previous work has shown that there is an optimum modulation frequency for which chaotic advection and heat transfer enhancement is a maximum. Here we show that the optimum modulation frequency can be derived from results without an axial flow. We also explain by physical arguments other previously unanswered questions in the published data.
Heat Transfer and Friction-Factor Methods Turbulent Flow Inside Pipes 3d Rough
Energy Science and Technology Software Center (ESTSC)
1994-01-21
Three-dimensional roughened internally enhanced tubes have been shown to be one of the most energy efficient for turbulent, forced convection applications. However, there is only one prediction method presented in the open literature and that is restricted to three-dimensional sand-grain roughness. Other roughness types are being proposed: hemispherical sectors, truncated cones, and full and truncated pyramids. There are no validated heat-transfer and friction-factor prediction methods for these different roughness shapes that can be used inmore » the transition and fully rough region. This program calculates the Nusselt number and friction factor values, for a broad range of three-dimensional roughness types such as hemispherical sectors, truncated cones, and full and truncated pyramids. Users of this program are heat-exchangers designers, enhanced tubing suppliers, and research organizations or academia who are developing or validating prediction methods.« less
Determination of the heat transfer coefficients in transient heat conduction
NASA Astrophysics Data System (ADS)
Nho Hào, Dinh; Thanh, Phan Xuan; Lesnic, D.
2013-09-01
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.
Compact pulsed laser having improved heat conductance
NASA Technical Reports Server (NTRS)
Yang, L. C. (Inventor)
1977-01-01
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.
NASA Astrophysics Data System (ADS)
Cherubini, Y.; Cacace, M.; Scheck-Wenderoth, M.
2011-12-01
Studies that quantify the influence of faults on the fluid and heat transfer in 3D are still sparse. Faults have a significant impact on physical processes controlling heat transfer and fluid motion in the subsurface as they disturb the conformal succession of geological layers. Depending on their hydraulic properties, faults can act either as preferential pathways or as barriers to fluid flow (Barton et al. 1995). It is important to understand the role of faults and their impact on the thermal field for exploitation of geothermal energy. We improved an existing 3D structural model of the geothermal site "Gross Schönebeck" (Moeck et al. 2005) to carry out coupled fluid and heat transfer simulations. The coupled non-linear partial differential equations describing fluid flow and heat transport in a saturated porous medium are numerically solved by the finite element software FEFLOW° (Diersch, 2002). Simulation results are validated with borehole data. The geological model covers an area of 55 x 50 km. It integrates 18 sedimentary layers of Carboniferous to Quaternary age and reaches down to 5 km depth. An up to 1200 m thick Upper Permian (Zechstein) salt layer decouples two fault systems. We focus on the subsalt fault system which comprises the reservoir target zone and which includes major NW-SE and minor NE-SW trending faults cutting the lower part of the model. The major intersecting faults of the subsalt system are integrated as vertical discrete elements within the numerical model. By discrimination of critically stressed and extensional faults within the current stress field, the hydraulic conductivity of the faults is assessed (Moeck et al. 2009). The impact of the main fault characterising parameters, - the permeability and effective width of the fault-, are investigated by sensitivity analyses. We present outcomes from these simulations by comparing them with results from conductive and coupled fluid and heat transfer simulations obtained from models that do not integrate faults. The results pioneer in that they treat the fault-induced transport of fluid and heat in 3D. We find that faults can strongly alter the fluid regime as well as the temperature evolution in response to their contrasting hydraulic properties with respect to the surrounding matrix.
Measurement of heat conduction through stacked screens.
Lewis, M A; Kuriyama, T; Kuriyama, F; Radebaugh, R
1998-01-01
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
Measurement of heat conduction through stacked screens
NASA Technical Reports Server (NTRS)
Lewis, M. A.; Kuriyama, T.; Kuriyama, F.; Radebaugh, R.
1998-01-01
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.
Grant L. Hawkes; James E. O'Brien; Greg Tao
2011-11-01
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.
3D crustal-scale heat-flow regimes at a developing active margin (Taranaki Basin, New Zealand)
NASA Astrophysics Data System (ADS)
Kroeger, K. F.; Funnell, R. H.; Nicol, A.; Fohrmann, M.; Bland, K. J.; King, P. R.
2013-04-01
The Taranaki Basin in the west of New Zealand's North Island has evolved from a rifted Mesozoic Gondwana margin to a basin straddling the Neogene convergent Australian-Pacific plate margin. However, given its proximity to the modern subduction front, Taranaki Basin is surprisingly cold when compared to other convergent margins. To investigate the effects of active margin evolution on the thermal regime of the Taranaki Basin we developed a 3D crustal-scale forward model using the petroleum industry-standard basin-modelling software Petromod™. The crustal structure inherited from Mesozoic Gondwana margin breakup and processes related to modern Hikurangi convergent margin initiation are identified to be the main controls on the thermal regime of the Taranaki Basin. Present-day surface heat flow across Taranaki on average is 59 mW/m2, but varies by as much as 30 mW/m2 due to the difference in crustal heat generation between mafic and felsic basement terranes alone. In addition, changes in mantle heat advection, tectonic subsidence, crustal thickening and basin inversion, together with related sedimentary processes result in variability of up to 10 mW/m2. Modelling suggests that increased heating of the upper crust due to additional mantle heat advection following the onset of subduction is an ongoing process and heating has only recently begun to reach the surface, explaining the relatively low surface heat flow. We propose that the depth of the subducted slab and related mantle convection processes control the thermal and structural regimes in the Taranaki Basin. The thermal effects of the subduction initiation process are modified and overprinted by the thickness, structure and composition of the lithosphere.
Large variable conductance heat pipe. Transverse header
NASA Technical Reports Server (NTRS)
Edelstein, F.
1975-01-01
The characteristics of gas-loaded, variable conductance heat pipes (VCHP) are discussed. The difficulties involved in developing a large VCHP header are analyzed. The construction of the large capacity VCHP is described. A research project to eliminate some of the problems involved in large capacity VCHP operation is explained.
Heat Rejection from a Variable Conductance Heat Pipe Radiator Panel
NASA Technical Reports Server (NTRS)
Jaworske, D. A.; Gibson, M. A.; Hervol, D. S.
2012-01-01
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.
Effects of anisotropic heat conduction on solidification
NASA Technical Reports Server (NTRS)
Weaver, J. A.; Viskanta, R.
1989-01-01
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).
NASA Astrophysics Data System (ADS)
Lin, Chia-Wen; Jang, Jiin-Yuh
2005-05-01
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.
Guidelines in the experimental validation of a 3D heat and fluid flow model of keyhole laser welding
NASA Astrophysics Data System (ADS)
Courtois, Mickael; Carin, Muriel; Le Masson, Philippe; Gaied, Sadok; Balabane, Mikhaël
2016-04-01
During the past few years, numerous sophisticated models have been proposed to predict in a self-consistent way the dynamics of the keyhole, together with the melt pool and vapor jet. However, these models are only partially compared to experimental data, so the reliability of these models is questionable. The present paper aims to propose a more complete experimental set-up in order to validate the most relevant results calculated by these models. A complete heat transfer and fluid flow three-dimensional (3D) model is first proposed in order to describe laser welding in keyhole regimes. The interface is tracked with a level set method and fluid flows are calculated in liquid and gas. The mechanisms of recoil pressure and keyhole creation are highlighted in a fusion line configuration chosen as a reference. Moreover, a complete validation of the model is proposed with guidelines on the variables to observe. Numerous comparisons with dedicated experiments (thermocouples, pyrometry, high-speed camera) are proposed to estimate the validity of the model. In addition to traditional geometric measurements, the main variables calculated, temperatures, and velocities in the melt pool are at the center of this work. The goal is to propose a reference validation for complex 3D models proposed over the last few years.
Application of the Finite Orbit Width Version of the CQL3D Code to NBI +RF Heating of NSTX Plasma
NASA Astrophysics Data System (ADS)
Petrov, Yu. V.; Harvey, R. W.
2015-11-01
The CQL3D bounce-averaged Fokker-Planck (FP) code has been upgraded to include Finite-Orbit-Width (FOW) effects. The calculations can be done either with a fast Hybrid-FOW option or with a slower but neoclassically complete full-FOW option. The banana regime neoclassical radial transport appears naturally in the full-FOW version by averaging the local collision coefficients along guiding center orbits, with a proper transformation matrix from local (R, Z) coordinates to the midplane computational coordinates, where the FP equation is solved. In a similar way, the local quasilinear rf diffusion terms give rise to additional radial transport of orbits. The full-FOW version is applied to simulation of ion heating in NSTX plasma. It is demonstrated that it can describe the physics of transport phenomena in plasma with auxiliary heating, in particular, the enhancement of the radial transport of ions by RF heating and the occurrence of the bootstrap current. Because of the bounce-averaging on the FPE, the results are obtained in a relatively short computational time. A typical full-FOW run time is 30 min using 140 MPI cores. Due to an implicit solver, calculations with a large time step (tested up to dt = 0.5 sec) remain stable. Supported by USDOE grants SC0006614, ER54744, and ER44649.
NASA Technical Reports Server (NTRS)
Pulicani, J. P.; Ouazzani, J.
1991-01-01
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 approximation in the periodic direction and a Chebyshev-collocation approximation in the other directions. Difficulties related to the pressure are surmounted by using the artifical compressibility method. A suitable variable change was chosen to avoid the problem of singularity at the axis generated by cylindrical coordinates. The method is first tested on an advection-diffusion equation and then on the Navier-Stokes equations. Finally, the method is illustrated by a convection problem of a differentially heated fluid.
Wang, G.L.; Chew, W.C.; Cui, T.J.; Aydiner, A.A.; Wright, D.L.; Smith, D.V.
2004-01-01
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.
2-D Finite Element Heat Conduction
Energy Science and Technology Software Center (ESTSC)
1989-10-30
AYER is a finite element program which implicitly solves the general two-dimensional equation of thermal conduction for plane or axisymmetric bodies. AYER takes into account the effects of time (transient problems), in-plane anisotropic thermal conductivity, a three-dimensional velocity distribution, and interface thermal contact resistance. Geometry and material distributions are arbitrary, and input is via subroutines provided by the user. As a result, boundary conditions, material properties, velocity distributions, and internal power generation may be mademore » functions of, e.g., time, temperature, location, and heat flux.« less
Asadi-Eydivand, Mitra; Solati-Hashjin, Mehran; Shafiei, Seyedeh Sara; Mohammadi, Sepideh; Hafezi, Masoud; Abu Osman, Noor Azuan
2016-01-01
The ability of inkjet-based 3D printing (3DP) to fabricate biocompatible ceramics has made it one of the most favorable techniques to generate bone tissue engineering (BTE) scaffolds. Calcium sulfates exhibit various beneficial characteristics, and they can be used as a promising biomaterial in BTE. However, low mechanical performance caused by the brittle character of ceramic materials is the main weakness of 3DP calcium sulfate scaffolds. Moreover, the presence of certain organic matters in the starting powder and binder solution causes products to have high toxicity levels. A post-processing treatment is usually employed to improve the physical, chemical, and biological behaviors of the printed scaffolds. In this study, the effects of heat treatment on the structural, mechanical, and physical characteristics of 3DP calcium sulfate prototypes were investigated. Different microscopy and spectroscopy methods were employed to characterize the printed prototypes. The in vitro cytotoxicity of the specimens was also evaluated before and after heat treatment. Results showed that the as-printed scaffolds and specimens heat treated at 300°C exhibited severe toxicity in vitro but had almost adequate strength. By contrast, the specimens heat treated in the 500°C–1000°C temperature range, although non-toxic, had insufficient mechanical strength, which was mainly attributed to the exit of the organic binder before 500°C and the absence of sufficient densification below 1000°C. The sintering process was accelerated at temperatures higher than 1000°C, resulting in higher compressive strength and less cytotoxicity. An anhydrous form of calcium sulfate was the only crystalline phase existing in the samples heated at 500°C–1150°C. The formation of calcium oxide caused by partial decomposition of calcium sulfate was observed in the specimens heat treated at temperatures higher than 1200°C. Although considerable improvements in cell viability of heat-treated scaffolds were observed in this study, the mechanical properties were not significantly improved, requiring further investigations. However, the findings of this study give a better insight into the complex nature of the problem in the fabrication of synthetic bone grafts and scaffolds via post-fabrication treatment of 3DP calcium sulfate prototypes. PMID:26999789
Asadi-Eydivand, Mitra; Solati-Hashjin, Mehran; Shafiei, Seyedeh Sara; Mohammadi, Sepideh; Hafezi, Masoud; Abu Osman, Noor Azuan
2016-01-01
The ability of inkjet-based 3D printing (3DP) to fabricate biocompatible ceramics has made it one of the most favorable techniques to generate bone tissue engineering (BTE) scaffolds. Calcium sulfates exhibit various beneficial characteristics, and they can be used as a promising biomaterial in BTE. However, low mechanical performance caused by the brittle character of ceramic materials is the main weakness of 3DP calcium sulfate scaffolds. Moreover, the presence of certain organic matters in the starting powder and binder solution causes products to have high toxicity levels. A post-processing treatment is usually employed to improve the physical, chemical, and biological behaviors of the printed scaffolds. In this study, the effects of heat treatment on the structural, mechanical, and physical characteristics of 3DP calcium sulfate prototypes were investigated. Different microscopy and spectroscopy methods were employed to characterize the printed prototypes. The in vitro cytotoxicity of the specimens was also evaluated before and after heat treatment. Results showed that the as-printed scaffolds and specimens heat treated at 300°C exhibited severe toxicity in vitro but had almost adequate strength. By contrast, the specimens heat treated in the 500°C-1000°C temperature range, although non-toxic, had insufficient mechanical strength, which was mainly attributed to the exit of the organic binder before 500°C and the absence of sufficient densification below 1000°C. The sintering process was accelerated at temperatures higher than 1000°C, resulting in higher compressive strength and less cytotoxicity. An anhydrous form of calcium sulfate was the only crystalline phase existing in the samples heated at 500°C-1150°C. The formation of calcium oxide caused by partial decomposition of calcium sulfate was observed in the specimens heat treated at temperatures higher than 1200°C. Although considerable improvements in cell viability of heat-treated scaffolds were observed in this study, the mechanical properties were not significantly improved, requiring further investigations. However, the findings of this study give a better insight into the complex nature of the problem in the fabrication of synthetic bone grafts and scaffolds via post-fabrication treatment of 3DP calcium sulfate prototypes. PMID:26999789
Burge, S.W.; Oberjohn, W.J. )
1993-09-30
DIAN3D describes the momentum, energy and mass transfer occurring in duct injection and spray drying processes. DIAN3D calculates the effect of atomizer spacing and wall clearance on droplet evaporation and SO2 absorption. DIAN3D has the ability to model: Multi-dimensional (2D or 3d) gas flow, Cartesian or cylindrical polar coordinate systems, Laminar or turbulent flow, Droplet dynamics using a Lagrangian approach, Heat and mass transfer between the gas phase and slurry, Droplets or inert particles, SO2 removal.
NASA Astrophysics Data System (ADS)
Natale, Giovanni; Popescu, Cristina; Tuffs, Richard
2015-08-01
A major difficulty hampering the accuracy of UV/optical star formation rate tracers is the effect of interstellar dust, absorbing and scattering light produced by both young and old stellar populations (SPs). Although empirically calibrated corrections or energy balance SED fitting are often used for fast de-reddening of galaxy stellar emission, eventually only radiative transfer calculations can provide self-consistent predictions of galaxy model spectra, taking into account important factors such as galaxy inclination, different morphological components, non-local heating of the dust and scattered radiation. In addition, dust radiative transfer can be used to determine the fraction of monochromatic dust emission which is powered by either young or old SPs. This calculation needs to take into account the different response of the dust grains to the UV and optical radiation field, depending on the grain size and composition. We determined the dust heating fractions, on both global and local scales, for high-resolution galaxy models by using our 3D ray-tracing dust radiative transfer code "DART-Ray". We will show the results obtained using this method and discuss the consequences for star formation rate indicators.
Long and high conductance helium heat pipe
NASA Astrophysics Data System (ADS)
Gully, Philippe
2014-11-01
This paper reports on the development and the thermal tests of two superfluid helium heat pipes. They feature a copper braid located inside a 6 mm outer diameter stainless tube fitted with copper ends for mechanical anchoring. The copper braid is the support of the Rollin superfluid helium film which is essential in the heat transfer. The extremely low thickness of the liquid film allows for a low filling pressure, making the technology very simple without the need for any external hot reservoir and with the possibility to easily bend the tube. We present the design and discuss the thermal performance of two heat pipes tested for several filling pressures, adverse tilt angles and in 1.4-2.0 K temperature range. A minimum filling pressure (0.6 MPa) is needed to get significant transport capacity. A 12 mW transport capacity is achieved for 3.0 MPa filling pressure. It is shown that the long heat pipe (1.2 m) and the short one (0.25 m) have similar thermal performance in adverse tilt. At 1.7 K the long heat pipe, 120 g in weight, reaches a transport capacity of 5.7 mW/4.2 mW for a tilt angle of 0 / 60° and a thermal conductance of 600 mW/K for 4 mW transferred power. When the condenser reaches the super-fluid transition temperature, the Rollin film accelerates the cool down of the evaporator down to 1.7 K with a heating power applied to the evaporator.
Microscale Heat Conduction Models and Doppler Feedback
Hawari, Ayman I.; Ougouag, Abderrafi
2015-01-22
The objective of this project is to establish an approach for providing the fundamental input that is needed to estimate the magnitude and time-dependence of the Doppler feedback mechanism in Very High Temperature reactors. This mechanism is the foremost contributor to the passive safety of gas-cooled, graphite-moderated high temperature reactors that use fuel based on Tristructural-Isotropic (TRISO) coated particles. Therefore, its correct prediction is essential to the conduct of safety analyses for these reactors. Since the effect is directly dependent on the actual temperature reached by the fuel during transients, the underlying phenomena of heat deposition, heat transfer and temperature rise must be correctly predicted. To achieve the above objective, this project will explore an approach that accounts for lattice effects as well as local temperature variations and the correct definition of temperature and related local effects.
Duan, Shasha; Yang, Ke; Wang, Zhihui; Chen, Mengting; Zhang, Ling; Zhang, Hongbo; Li, Chunzhong
2016-01-27
The combination of carbon nanomaterial with three-dimensional (3D) porous polymer substrates has been demonstrated to be an effective approach to manufacture high-performance stretchable conductive materials (SCMs). However, it remains a challenge to fabricate 3D-structured SCMs with outstanding electrical conductivity capability under large strain in a facile way. In this work, the 3D printing technique was employed to prepare 3D porous poly(dimethylsiloxane) (O-PDMS) which was then integrated with carbon nanotubes and graphene conductive network and resulted in highly stretchable conductors (OPCG). Two types of OPCG were prepared, and it has been demonstrated that the OPCG with split-level structure exhibited both higher electrical conductivity and superior retention capability under deformations, which was illustrated by using a finite element method. The specially designed split-level OPCG is capable of sustaining both large strain and repeated deformations showing huge potential in the application of next-generation stretchable electronics. PMID:26713456
Parallelized solvers for heat conduction formulations
NASA Technical Reports Server (NTRS)
Padovan, Joe; Kwang, Abel
1991-01-01
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.
NASA Astrophysics Data System (ADS)
Dorfman, S. M.; Nabiei, F.; Cantoni, M.; Badro, J.; Gaal, R.; Gillet, P.
2014-12-01
The laser-heated diamond anvil cell is a unique tool for subjecting materials to pressures over few hundreds of GPa and temperatures of thousands of Kelvins which enables us to experimentally simulate the inaccessible interiors of planets. However, small sample size, laser profile and thermally conductive diamonds cause temperature gradients of 1000s K over a few microns which also affects chemical and structural distribution of phases in the sample. We have examined samples of San Carlos olivine (Mg,Fe)2SiO3 powder melted in the diamond anvil cell by double-sided and single-sided laser heating for 3-6 minutes to ~3000 K at 35-37 GPa. Moreover, MgO is used as an insulating media in one of the sample. Recovered samples were analyzed by a combination of focused ion beam (FIB) and scanning electron microscope (SEM) equipped with energy dispersive x-ray (EDX) detector. Images and chemical maps were acquired for ~300 slices with ~70 nm depth from each sample, comprising about half of the heated zone. Detailed chemical and structural analysis by transmission electron microscopy (TEM) of lamellas prepared from the remaining section of the samples will also be presented. In all samples the heated zone included (Mg,Fe)SiO3 perovskite-structured bridgmanite (PV) phase and two (Mg, Fe)O phases, one of which, magnesiowüstite (MW), is richer in iron than the other one, ferropericlase (FP). In double-side heated samples we observe a Fe-rich quenched melt core surrounded by MW phase. Our results show that with increasing heating time, Fe migrates to the molten center of the sample. In the single-side heated sample, the Fe-rich MW phase is concentrated in the center of heated zone. In all samples a FP crust was observed around the heated zone. This crust, however, is broken in the upper part (colder part) of the single-side heated sample due the high asymmetrical temperature gradient within the sample. The results confirm the importance of double-side heating and insulating media for generating homogenous central temperature and chemical distribution.
Information filtering via weighted heat conduction algorithm
NASA Astrophysics Data System (ADS)
Liu, Jian-Guo; Guo, Qiang; Zhang, Yi-Cheng
2011-06-01
In this paper, by taking into account effects of the user and object correlations on a heat conduction (HC) algorithm, a weighted heat conduction (WHC) algorithm is presented. We argue that the edge weight of the user-object bipartite network should be embedded into the HC algorithm to measure the object similarity. The numerical results indicate that both the accuracy and diversity could be improved greatly compared with the standard HC algorithm and the optimal values reached simultaneously. On the Movielens and Netflix datasets, the algorithmic accuracy, measured by the average ranking score, can be improved by 39.7% and 56.1% in the optimal case, respectively, and the diversity could reach 0.9587 and 0.9317 when the recommendation list equals to 5. Further statistical analysis indicates that, in the optimal case, the distributions of the edge weight are changed to the Poisson form, which may be the reason why HC algorithm performance could be improved. This work highlights the effect of edge weight on a personalized recommendation study, which maybe an important factor affecting personalized recommendation performance.
NASA Astrophysics Data System (ADS)
Zhu, Weiping; Xie, Xiujuan; Yang, Huihui; Li, Laifeng; Gong, Linghui
High performance heat exchangers are critical component in many cryogenic systems and its performance is typically very sensitive to longitudinal heat conduction, parasitic heat loads and property variations. This paper gives an analytical study on 1-D model for multi-stream parallel-plate fin heat exchanger by using the method of decoupling transformations. The results obtained in the present paper are valuable for the reference on optimization for heat exchanger design.
NASA Astrophysics Data System (ADS)
Titarenko, S.; McCaig, A. M.
2014-12-01
A perennial problem in near-ridge hydrothermal circulation is that the only directly measurable data to test models is often vent fluid temperature. Surface heat flow measurements may be available but without the underlying thermal structure it is not known if they are transient and affected by local hydrothermal flow, or conductive. The Atlantis Massif oceanic core complex at 30 °N on the mid-Atlantic Ridge, offers a unique opportunity to better constrain hydrothermal circulation models. The temperature profile in gabbroic rocks of IODP Hole 1309D was measured in IODPExpedition 340T, and found to be near-conductive, but with a slight inflexion at ~750 mbsf indicating downward advection of fluid above that level. The lack of deep convection is especially remarkable given that the long-lived Lost City Hydrothermal Field (LCHF) is located only 5km to the south. We have modelled hydrothermal circulation in the Massif using Comsol Multiphysics, comparing 2-D and 3-D topographic models and using temperature-dependent conductivity to give the best estimate of heatflow into the Massif. We can constrain maximum permeability in gabbro below 750 mbsf to 5e-17 m2. The thermal gradient in the upper part of the borehole can be matched with a permeability of 3e-14 m2 in a 750 m thick layer parallel to the surface of the massif, with upflow occurring in areas of high topography and downflow at the location of the borehole. However in 3-D the precise flow pattern is quite model dependent, and the thermal structure can be matched either by downflow centred on the borehole at lower permeability or centred a few hundred metres from the borehole at higher permeability. The borehole gradient is compatible with the longevity (>120 kyr) and outflow temperature (40-90 °C) of the LCHF either with a deep more permeable (1e-14 m2 to 1e-15 m2) domain beneath the vent site in 2-D or a permeable fault slot 500 to 1000m wide and parallel to the transform fault in 3-D. In both cases topography exerts a strong control on vent location, and steep boundaries between permeable and impermeable domains stabilise long term steady venting. Work is in progress to model the thermal evolution of the massif during fault exhumation over the last 1.2 million years, comparing this with the present day heatflow estimated from measurements.
Kipp, K.L.
1987-01-01
The Heat- and Soil-Transport Program (HST3D) simulates groundwater flow and associated heat and solute transport in three dimensions. The three governing equations are coupled through the interstitial pore velocity, the dependence of the fluid density on pressure, temperature, the solute-mass fraction , and the dependence of the fluid viscosity on temperature and solute-mass fraction. The solute transport equation is for only a single, solute species with possible linear equilibrium sorption and linear decay. Finite difference techniques are used to discretize the governing equations using a point-distributed grid. The flow-, heat- and solute-transport equations are solved , in turn, after a particle Gauss-reduction scheme is used to modify them. The modified equations are more tightly coupled and have better stability for the numerical solutions. The basic source-sink term represents wells. A complex well flow model may be used to simulate specified flow rate and pressure conditions at the land surface or within the aquifer, with or without pressure and flow rate constraints. Boundary condition types offered include specified value, specified flux, leakage, heat conduction, and approximate free surface, and two types of aquifer influence functions. All boundary conditions can be functions of time. Two techniques are available for solution of the finite difference matrix equations. One technique is a direct-elimination solver, using equations reordered by alternating diagonal planes. The other technique is an iterative solver, using two-line successive over-relaxation. A restart option is available for storing intermediate results and restarting the simulation at an intermediate time with modified boundary conditions. This feature also can be used as protection against computer system failure. Data input and output may be in metric (SI) units or inch-pound units. Output may include tables of dependent variables and parameters, zoned-contour maps, and plots of the dependent variables versus time. (Lantz-PTT)
Nonintegrability and the Fourier heat conduction law
NASA Astrophysics Data System (ADS)
Chen, Shunda; Wang, Jiao; Casati, Giulio; Benenti, Giuliano
2014-09-01
We study in momentum-conserving systems, how nonintegrable dynamics may affect thermal transport properties. As illustrating examples, two one-dimensional (1D) diatomic chains, representing 1D fluids and lattices, respectively, are numerically investigated. In both models, the two species of atoms are assigned two different masses and are arranged alternatively. The systems are nonintegrable unless the mass ratio is one. We find that when the mass ratio is slightly different from one, the heat conductivity may keep significantly unchanged over a certain range of the system size and as the mass ratio tends to one, this range may expand rapidly. These results establish a new connection between the macroscopic thermal transport properties and the underlying dynamics.
The Tonga-Vanuatu Subduction Complex -- a Self-Optimized 3D Slab-Slab-Mantle Heat Pump
NASA Astrophysics Data System (ADS)
McCreary, J. A.
2008-12-01
Recently published geophysical and geochemical data and increasingly actualistic free subduction models prompted a fresh look at 2 classics hinting, in combination, that a coupled 3D slab-slab-upper mantle interaction (Scholz and Campos, 1995; full citations at URL below) might power the prodigious surface heat dissipation (Lagabrielle et al., 1997) characterizing one of Earth's most remarkable tectonomagmatic systems, the Tonga-Vanuatu Subduction Complex (TVSC). The 3D TVSC includes (1) the kinematically, magmatically, and bathymetrically distinct North Tonga (NT, 14-26° S) and South Vanuatu (SV, 16-23° S) trenches and slabs, (2) the shared NT-SV backarc, and (3) entrained mobile upper mantle (MUM). That Earth's greatest convergence, rollback, and spreading rates; most disseminated spreading (the North Fiji Basin (NFB) ridge swarm); and greatest concentration of aggregate active ridge length coincide in a 1,500 km TVSC can't be accidental. To the north and south, the respective active NT and SV trenches swing abruptly 90° counterclockwise into continuity with the Vitiaz and Hunter fossil trenches, both active in the Late Miocene but now sinistral strike-slip loci standing over long exposed PA and AU slab edges. These 2 active-fossil trench pairs bracket a hot, shallow and geophysically and geochemically exceptional TVSC interior consisting of 2 rapidly spreading backarcs set back-to-back in free sublithospheric communication: The Lau-Havre NT backarc on the east and the ridge-infested SV backarc (NFB) on the west. The NFB and adjacent North Fiji Plateau make up the unplatelike New Hebrides-Fiji Orogen (Bird, 2003). As in the western Aleutians, the NT-Vitiaz and SV-Hunter subduction-to-strike-slip transitions (SSSTs) stand above toroidal fluxes of hot, dry PA and AU MUM driven along-trench and around the free NT and SV slab edges from subslab to supraslab regions by dynamic pressure gradients powered by slab free-fall and induced viscous couplings. These edge flows must converge and mix beneath the shared TVSC backarc, which must then shed a huge advected subslab heat load by maximizing ridge length in the area available. Found at both SSSTs are adakites indicative of a TVSC source laced with slab-edge melt and boninites consistent with flux- melting of hot, dry subslab MUM on entry to the supraslab wedge. Isotopics reveal widespread source mixing of Pacific and Indian MOR end-members. Diverging NT and VS trenches rotate clockwise at extremely high rates about pinning points at and Euler poles near trench-floater intercepts: Louisville Ridge on PA, and West Torres Plateau-D'Entrecasteaux Ridge on AU. In this configuration, the spinning, free-falling NT and SV slabs form a highly coupled self-organized gravity-powered pump pulling hot subslab MUM beneath the TVSC with enough left-over head to power severe transition zone buckling of an 80+ Ma NT (PA) slab also actively extending toward its free edge. Several nonlinear couplings (e.g., temperature-dependent viscosity and slab damage at tightening upper hinges) feedback positively to pump efficiency. The TVSC is but one possible slab-mantle pump partaking of the strong self-optimizing tendency characteristic of all natural flow systems (e.g., Bejan and Lorente, 2006). Slab-mantle pump natural history is now under investigation, as such pumps may have allowed a shrinking post-Pangean Pacific with an unrelenting sublithospheric room problem to relieve itself of excess MUM by making efficient use of available circum-Pacific slab curtain porosity -- a commodity that may have been in very short supply through most of the Cretaceous.
NASA Astrophysics Data System (ADS)
Patro, Prasanta K.; Egbert, Gary D.
2008-10-01
In conjunction with the USArray component of EarthScope, long period magnetotelluric (MT) data are being acquired in a series of arrays across the continental US. Initial deployments in 2006 and 2007 acquired data (10-10,000 s) at 110 sites covering the US Pacific Northwest, distributed with the same nominal spacing as the USArray seismic transportable array (~75 km). The most striking and robust features revealed by initial three-dimensional inversion of this dataset are extensive areas of high conductivity in the lower crust beneath all of southeastern Oregon, and beneath the Cascade Mountains, contrasting with very resistive crust in Siletzia and the Columbia Embayment. Significant variations in upper mantle conductivity are also revealed by the inversions, with the most conductive mantle beneath the Washington backarc, and the most resistive corresponding to subducting oceanic mantle.
NASA Astrophysics Data System (ADS)
Chen-Wiegart, Yu-Chen Karen; Figueroa-Santos, Miriam Aileen; Petrash, Stanislas; Garcia-Miralles, Jose; Wang, Jun
2014-12-01
Conductive adhesives are found favorable in a wide range of applications including a lead-free solder in micro-chips, flexible and printable electronics and enhancing the performance of energy storage devices. Composite materials comprised of metallic fillers and a polymer matrix are of great interest to be implemented as hybrid conductive adhesives. Here we investigated a cost-effective conductive adhesive material consisting of silver-coated copper as micro-fillers using synchrotron-based three-dimensional (3D) X-ray nano-tomography. The key factors affecting the quality and performance of the material were quantitatively studied in 3D on the nanometer scale for the first time. A critical characteristic parameter, defined as a shape-factor, was determined to yield a high-quality silver coating, leading to satisfactory performance. A `stack-and-screen' mechanism was proposed to elaborate such a phenomenon. The findings and the technique developed in this work will facilitate the future advancement of conductive adhesives to have a great impact in micro-electronics and other applications.Conductive adhesives are found favorable in a wide range of applications including a lead-free solder in micro-chips, flexible and printable electronics and enhancing the performance of energy storage devices. Composite materials comprised of metallic fillers and a polymer matrix are of great interest to be implemented as hybrid conductive adhesives. Here we investigated a cost-effective conductive adhesive material consisting of silver-coated copper as micro-fillers using synchrotron-based three-dimensional (3D) X-ray nano-tomography. The key factors affecting the quality and performance of the material were quantitatively studied in 3D on the nanometer scale for the first time. A critical characteristic parameter, defined as a shape-factor, was determined to yield a high-quality silver coating, leading to satisfactory performance. A `stack-and-screen' mechanism was proposed to elaborate such a phenomenon. The findings and the technique developed in this work will facilitate the future advancement of conductive adhesives to have a great impact in micro-electronics and other applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06068g
Compact laser through improved heat conductance
NASA Technical Reports Server (NTRS)
Yang, L. C.
1975-01-01
A 16-joule-pulse laser has been developed in which a boron nitride heat-conductor enclosure is used to remove heat from the elements. Enclosure is smaller and lighter than systems in which cooling fluids are used.
NASA Astrophysics Data System (ADS)
Kuvshinov, Alexey; Semenov, Alexey
2012-06-01
We present a novel frequency-domain inverse solution to recover the 3-D electrical conductivity distribution in the mantle. The solution is based on analysis of local C-responses. It exploits an iterative gradient-type method - limited-memory quasi-Newton method - for minimizing the penalty function consisting of data misfit and regularization terms. The integral equation code is used as a forward engine to calculate responses and data misfit gradients during inversion. An adjoint approach is implemented to compute misfit gradients efficiently. Further improvements in computational load come from parallelizing the scheme with respect to frequencies, and from setting the most time-consuming part of the forward calculations - calculation of Green's tensors - apart from the inversion loop. Convergence, performance, and accuracy of our 3-D inverse solution are demonstrated with a synthetic numerical example. A companion paper applies the strategy set forth here to real data.
Wu, Xiaodong; Lu, Canhui; Xu, Haoyu; Zhang, Xinxing; Zhou, Zehang
2014-12-10
Development of novel and versatile strategies to construct conductive polymer composites with low percolation thresholds and high mechanical properties is of great importance. In this work, we report a facile and effective strategy to prepare polyaniline@cellulose nanowhiskers (PANI@CNs)/natural rubber (NR) nanocomposites with 3D hierarchical multiscale structure. Specifically, PANI was synthesized in situ on the surface of CNs biotemplate to form PANI@CNs nanohybrids with high aspect ratio and good dispersity. Then NR latex was introduced into PANI@CNs nanohybrids suspension to enable the self-assembly of PANI@CNs nanohybrids onto NR latex microspheres. During cocoagulation process, PANI@CNs nanohybrids selectively located in the interstitial space between NR microspheres and organized into a 3D hierarchical multiscale conductive network structure in NR matrix. The combination of the biotemplate synthesis of PANI and latex cocoagulation method significantly enhanced the electrical conductivity and mechanical properties of the NR-based nanocomposites simultaneously. The electrical conductivity of PANI@CNs/NR nanocomposites containing 5 phr PANI showed 11 orders of magnitude higher than that of the PANI/NR composites at the same loading fraction,; meanwhile, the percolation threshold was drastically decreased from 8.0 to 3.6 vol %. PMID:25384188
Gustavsen, Arild; Arasteh, Dariush; Jelle, Bjorn Petter; Curcija, Charlie; Kohler, Christian
2008-09-11
While window frames typically represent 20-30% of the overall window area, their impact on the total window heat transfer rates may be much larger. This effect is even greater in low-conductance (highly insulating) windows that incorporate very low-conductance glazing. Developing low-conductance window frames requires accurate simulation tools for product research and development. Based on a literature review and an evaluation of current methods of modeling heat transfer through window frames, we conclude that current procedures specified in ISO standards are not sufficiently adequate for accurately evaluating heat transfer through the low-conductance frames. We conclude that the near-term priorities for improving the modeling of heat transfer through low-conductance frames are: (1) Add 2D view-factor radiation to standard modeling and examine the current practice of averaging surface emissivity based on area weighting and the process of making an equivalent rectangular frame cavity. (2) Asses 3D radiation effects in frame cavities and develop recommendation for inclusion into the design fenestration tools. (3) Assess existing correlations for convection in vertical cavities using CFD. (4) Study 2D and 3D natural convection heat transfer in frame cavities for cavities that are proven to be deficient from item 3 above. Recommend improved correlations or full CFD modeling into ISO standards and design fenestration tools, if appropriate. (5) Study 3D hardware short-circuits and propose methods to ensure that these effects are incorporated into ratings. (6) Study the heat transfer effects of ventilated frame cavities and propose updated correlations.
Extended Development of Variable Conductance Heat Pipes
NASA Technical Reports Server (NTRS)
Antoniuk, D.; Edwards, D. K.; Luedke, E. E.
1978-01-01
A high-capacity vapor-modulated heat pipe was designed and tested. In 1977, a program was undertaken to use the aforementioned heat pipe to study protection from freezing-point failure, increase control sensitivity, and transient behavior under a wide range of operating conditions in order to determine the full performance potential of the heat pipe. A new concept, based on the vapor-induced-dry-out principle, was developed for passive feedback temperature control as a heat pipe diode. This report documents this work and describes: (1) the experimental and theoretical investigation of the performance of the vapor-modulated heat pipe; and (2) the design, fabrication and test of the heat pipe diode.
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
Until now, few sp2 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 m2/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
Control of heat source in a heat conduction problem
NASA Astrophysics Data System (ADS)
Lyashenko, V.; Kobilskaya, E.
2014-11-01
The mathematical model of thermal processes during the heat treatment of a moving axisymmetric environment, for example wire. is considered. The wire is heated by internal constantly or periodically operating heat source. It is presented in the form of initial-boundary value problem for the unsteady heat equation with internal constantly or periodically operating heat source. The purpose of the work is the definition of control parameter of temperature field of a moving area, which is heated by internal heat source. The control parameters are determined by solving a nonlocal problem for the heat equation. The problem of getting an adequate temperature distribution throughout the heating area is considered. Therefore, a problem of heat source control is solved, in particular, control by electric current. Control of the heat source allows to maintain the necessary, from a technological point of view, temperature in the heating area. In this paper, to find additional information about the source of heat. The integral condition is used in the control problem. Integral condition, which is considered in the work, determines the energy balance of the heating zone and connects the desired temperature distribution in the internal points of area with temperatures at the boundaries. Control quality in an extremum formulation of the problem is assessed using the quadratic functional. In function space, from a physical point of view, proposed functional is the absolute difference between the actual emission of energy and absorbed energy in the heating zone. The absorbed energy is calculated by solving of the boundary value problem. Methods of determining the control parameters of temperature field are proposed. The resulting problem is solved by iterative methods. At different physical conditions, numerical calculations are carried out, control parameters of the heat treatment process are obtained.
NASA Astrophysics Data System (ADS)
Meqbel, N. M.; Egbert, G. D.; Kelbert, A.
2010-12-01
Long period (10-20,000 s) magnetotelluric (MT) data are being acquired in a series of temporary arrays deployed across the continental United States through EMScope, a component of EarthScope, a multidisciplinary decade-long project to study the structure and evolution of the North American Continent. MT deployments in 2006-2010 have so far acquired data at 237 sites on an approximately regular grid, with the same nominal spacing as the USArray broadband seismic transportable array (~70 km), covering the Northwestern US, from the Oregon-Washington coast across the Rocky Mountains, into Montana and Wyoming. Preliminary 3-D inversion results (Patro and Egbert; 2008), based on data from the 110 westernmost “Cascadia” sites collected in the first two years, revealed extensive areas of high conductivity in the lower crust beneath the Northwest Basin and Range (NBR), inferred to result from fluids (including possibly partial melt at depth) associated with magmatic underplating, and beneath the Cascade Mountains, probably due to fluids released by the subducting Juan de Fuca slab. Here we extend this study, refining and further testing the preliminary results from Cascadia, and extending the inversion domain to the East, to include all of the EarthScope data. Although site spacing is very broad, distinct regional structures are clearly evident even in simple maps of apparent resistivity, phase and induction vectors. For the 3-D inversion we are using the parallelized version of our recently developed Modular Code (ModEM), which supports Non-Linear Conjugate Gradient and several Gauss-Newton type schemes. Our initial 3-D inversion results using 212 MT sites, fitting impedances and vertical field transfer functions (together and separately) suggest several conductive and resistive structures which appear to be stable and required by the measured data. These include: - A conductive structure elongated in the N-S direction underneath the volcanic arc of the Cascadia subduction zone starting at a depth of about 20-30 km. - A pronounced conductive feature at or just below the base of the crust. This coincides with the NBR conductor of Patro and Egbert (2008), but our results show that this extends (and becomes even more pronounced) further to the east, where it connects with a conductive zone in the Yellowstone “hot spot” area. - Resistive crustal structure in the coast range, and beneath the Columbia Plateau, consistent with the interpretation of Humprheys (2008) that these two sections of crust represent the accreted Siletzia terrane (broken subsequently by arc volcanism). - A clear contrast between continental and oceanic mantle, with higher conductivities to depths of at least 150 km above the subducting Juan de Fuca Plate; the highest conductivities appear to be in the back arc in northern east of Washington. - Higher deep mantle conductivity to the east, in particular beneath Yellowstone. Multiple 3-D inversion and forward modeling tests will be required to verify the resolution and stability of these and other more subtle conductive and resistive structures in our 3-D models. Our efforts in this direction will be presented at the meeting.
Johnson, Timothy C.; Versteeg, Roelof J.; Rockhold, Mark L.; Slater, Lee D.; Ntarlagiannis, Dimitrios; Greenwood, William J.; Zachara, John M.
2012-09-17
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.
Superfluid heat conduction and the cooling of magnetized neutron stars
Cirigliano, Vincenzo; Reddy, Sanjay; Sharma, Rishi; Aguilera, Deborah N
2008-01-01
We report on a new mechanism for heat conduction in the neutron star crust. We find that collective modes of superftuid neutron matter, called superfiuid phonons (sPhs), can influence heat conduction in magnetized neutron stars. They can dominate the heat conduction transverse to magnetic field when the magnetic field B {approx}> 10{sup 13} C. At density p {approx_equal} 10{sup 12}--10{sup 14} g/cm{sup 3} the conductivity due to sPhs is significantly larger than that due to lattice phonons and is comparable to electron conductivity at when temperature {approx_equal} 10{sup 8} K. This new mode of heat conduction can limit the surface anisotropy in highly magnetized neutron stars. Cooling curves of magnetized neutron stars with and without superfluid heat conduction show observationally discernible differences.
Superfluid Heat Conduction and the Cooling of Magnetized Neutron Stars
Aguilera, Deborah N.; Cirigliano, Vincenzo; Reddy, Sanjay; Sharma, Rishi; Pons, Jose A.
2009-03-06
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.
Communications technology satellite - A variable conductance heat pipe application
NASA Technical Reports Server (NTRS)
Mock, P. R.; Marcus, B. D.; Edelman, E. A.
1974-01-01
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.
Theory and design of variable conductance heat pipes
NASA Technical Reports Server (NTRS)
Marcus, B. D.
1972-01-01
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.
NASA Technical Reports Server (NTRS)
Sakai, J. I.; Zhao, J.; Nishikawa, K.-I.
1994-01-01
We have shown that a current-carrying plasma loop can be heated by magnetic pinch driven by the pressure imbalance between inside and outside the loop, using a 3-dimensional electromagnetic (EM) particle code. Both electrons and ions in the loop can be heated in the direction perpendicular to the ambient magnetic field, therefore the perpendicular temperature can be increased about 10 times compared with the parallel temperature. This temperature anisotropy produced by the magnetic pinch heating can induce a plasma instability, by which high-frequency electromagnetic waves can be excited. The plasma current which is enhanced by the magnetic pinch can also excite a kinetic kink instability, which can heat ions perpendicular to the magnetic field. The heating mechanism of ions as well as the electromagnetic emission could be important for an understanding of the coronal loop heating and the electromagnetic wave emissions from active coronal regions.
Interchangeable variable conductance heat pipes for sodium-sulfur batteries
NASA Astrophysics Data System (ADS)
Hartenstine, John R.
1991-08-01
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.
Efficient Reformulation of HOTFGM: Heat Conduction with Variable Thermal Conductivity
NASA Technical Reports Server (NTRS)
Zhong, Yi; Pindera, Marek-Jerzy; Arnold, Steven M. (Technical Monitor)
2002-01-01
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.
Niu, Xufeng; Rouabhia, Mahmoud; Chiffot, Nicolas; King, Martin W; Zhang, Ze
2015-08-01
This study was to demonstrate that an extremely thin coating of poly(3,4-ethylenedioxythiophene) (PEDOT) on nonwoven microfibrous poly(l-lactic acid) (PLLA) web is of sufficient electrical conductivity and stability in aqueous environment to sustain electrical stimulation (ES) to cultured human skin fibroblasts. The PEDOT imparted the web a surface resistivity of approximately 0.1 KΩ/square without altering the web morphology. X-ray photoelectron spectroscopy demonstrated that the surface chemistry of the PLLA/PEDOT is characteristic of both PLLA and PEDOT. The PEDOT-coated web also showed higher hydrophilicity, lower glass transition temperature and unchanged fiber crystallinity and thermal stability compared with the PLLA web. The addition of PEDOT to the web marginally increased the web's tensile strength and lowered the elongation. An electrical stability test showed that the PLLA/PEDOT structure was more stable than a polypyrrole treated PLLA fabric, showing only a slow deterioration in conductivity when exposed to culture medium. The cytotoxicity test showed that the PLLA/PEDOT scaffold was not cytotoxic and supported human dermal fibroblast adhesion, migration, and proliferation. Preliminary ES experiments have demonstrated that this conductive web mediated effective ES to fibroblasts. Therefore, this new conductive biodegradable scaffold may be used to electrically modulate cellular activity and tissue regeneration. PMID:25630631
Heat conduction errors and time lag in cryogenic thermometer installations
NASA Technical Reports Server (NTRS)
Warshawsky, I.
1973-01-01
Installation practices are recommended that will increase rate of heat exchange between the thermometric sensing element and the cryogenic fluid and that will reduce the rate of undesired heat transfer to higher-temperature objects. Formulas and numerical data are given that help to estimate the magnitude of heat-conduction errors and of time lag in response.
NASA Astrophysics Data System (ADS)
Erlekampf, J.; Seebeck, J.; Savva, P.; Meissner, E.; Friedrich, J.; Alt, N. S. A.; Schlücker, E.; Frey, L.
2014-10-01
A numerical analysis of an ammonothermal synthesis process for the bulk growth of nitride crystals was performed. The analysis includes the development of a thermal model for a lab-scale ammonothermal autoclave, which was validated by in situ temperature measurements and applied to tailor the temperature field inside the autoclave. Based on the results of the global thermal 2D simulations, a local 3D model was used to include convective phenomena in the analysis. Moreover, the influence of the baffle and different baffle shapes on the flow velocity was investigated. Fluctuations of the temperature as well as the flow velocities occur, indicating that 3D considerations are essential to accurately investigate the heat and mass transport in ammonothermal systems.
Douglas W. Marshall; Changhu Xing; Charles Folsom; Colby Jensen; Heng Ban
2014-05-01
As an important factor affecting the accuracy of the 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 due primarily 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 a 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 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.
Jang, J.Y.; Yang, J.Y.
1998-10-01
Fluid flow and heat transfer over a 4-row, elliptic, finned-tube heat exchanger having an axis ratio of 2.83:1 are studied experimentally and numerically. Three types of finned-tube configurations have been investigated under dry and wet conditions for different values of inlet frontal velocity ranging from 2 to 7 m/s: two elliptic finned tubes with staggered and in-line arrangements and one circular finned tube with staggered arrangement. The experimental results indicate that the average heat transfer coefficient of an elliptic finned tube is 35--50% of the corresponding circular finned tube having the same tube perimeter, while the pressure drop for an elliptic finned-tube bank is only 25--30% of the circular finned-tube bank configuration. Three-dimensional numerical results of a laminar model for dry coils are also presented and are compared with the experimental data.
Shen, Yu; Yang, Xu-Feng; Zhu, Hai-Bin; Zhao, Yue; Li, Wei-Si
2015-09-01
Solvothermal reaction of a TCA (TCA = 4,4',4''-tricarboxytriphenylamine) ligand with Cd(NO3)2 yielded a unique 3D 12-connected metal-organic framework of , which can be simplified as a (3,3,12)-connected 3-nodal net with a Schläfli symbol of {4(16)·6(36)·8(14)}{4(2)·6}2{4(3)}2 based on a 12-connected node of a pentanuclear Cd(ii) cluster and a three-connected organic linker of TCA. Compound exhibits both photoluminescence and proton conductivity. The luminescence properties of originate from the triphenylamine chromophore of the TCA ligand. The proton conductivity of is supposed to be relevant to the structure attributes of . On the one hand, the curved narrow channels lined with a hydrophilic pentanuclear Cd(ii) cluster in can improve the water affinity of framework and facilitate the water absorption under humid conditions. On the other hand, the coordinated water molecules within the pentanuclear Cd(ii) cluster can produce a mobile H(+) proton due to coordination activation. At 80 °C and 85% RH (relative humidity), compound shows the proton conductivity of 1.45 × 10(-6) S cm(-1). PMID:26218655
Analysis and application of variable conductance heat pipe air preheater
NASA Astrophysics Data System (ADS)
Shi, Chengming; Wang, Yang; Liao, Quan; Yang, Ying
2011-09-01
The heat transfer analysis of variable conductance heat pipe air preheater was carried out. The temperature transfer matrix was obtained for the air preheater that comprises several discrete heat transfer units with same or different heat transfer surface area in a parallel or counter flow mode. By using the temperature transfer matrix, the outlet fluid temperatures could be easily calculated for a given air preheater and inlet fluid temperatures. The active length of condenser in a variable conductance heat pipe is determined according to the flat interface model. With the same initial conditions, the comparisons between variable conductance heat-pipe air preheater and regular heat pipe air preheater has been analyzed and tested in terms of heat pipe wall temperature, heat transfer surface area and outlet fluid temperatures. Based on the real industrial applications, it has been confirmed that the variable conductance heat pipe air preheater has excellent performance of anti-corrosion and anti-ash-deposition especially at the variable working condition and the sulfur coal (5%-6% mass fraction of sulfur) condition.
NASA Astrophysics Data System (ADS)
Klinger, Carolin; Mayer, Bernhard
2016-01-01
Due to computational costs, radiation is usually neglected or solved in plane parallel 1D approximation in today's numerical weather forecast and cloud resolving models. We present a fast and accurate method to calculate 3D heating and cooling rates in the thermal spectral range that can be used in cloud resolving models. The parameterization considers net fluxes across horizontal box boundaries in addition to the top and bottom boundaries. Since the largest heating and cooling rates occur inside the cloud, close to the cloud edge, the method needs in first approximation only the information if a grid box is at the edge of a cloud or not. Therefore, in order to calculate the heating or cooling rates of a specific grid box, only the directly neighboring columns are used. Our so-called Neighboring Column Approximation (NCA) is an analytical consideration of cloud side effects which can be considered a convolution of a 1D radiative transfer result with a kernel or radius of 1 grid-box (5 pt stencil) and which does usually not break the parallelization of a cloud resolving model. The NCA can be easily applied to any cloud resolving model that includes a 1D radiation scheme. Due to the neglect of horizontal transport of radiation further away than one model column, the NCA works best for model resolutions of about 100 m or lager. In this paper we describe the method and show a set of applications of LES cloud field snap shots. Correction terms, gains and restrictions of the NCA are described. Comprehensive comparisons to the 3D Monte Carlo Model MYSTIC and a 1D solution are shown. In realistic cloud fields, the full 3D simulation with MYSTIC shows cooling rates up to -150 K/d (100 m resolution) while the 1D solution shows maximum coolings of only -100 K/d. The NCA is capable of reproducing the larger 3D cooling rates. The spatial distribution of the heating and cooling is improved considerably. Computational costs are only a factor of 1.5-2 higher compared to a 1D solution.
Cascade variable-conductance heat pipe (A0076)
NASA Technical Reports Server (NTRS)
Grote, M. G.; Calhoun, L. D., II
1984-01-01
The objective is to verify the capability of a cascade variable conductance heat pipe (CVCHP) system to provide precise temperature control of long life spacecraft without the need for a feedback heater or other power sources for temperature adjustment under conditions of widely varying power input and ambient environment. Solar energy is the heat source and space the heat sink for thermally loading two series connected variable conductance heat pipes. Electronics and power supply equipment requirements are minimal. A 7.5 V lithium battery supplies the power for thermistor type temperature sensors for monitoring system performance, and a 28 V lithium battery supplies power for valve actuation.
Zhang, Xian; Wang, Qiuran; Ma, Zhimin; He, Jianqiao; Wang, Zhe; Zheng, Chong; Lin, Jianhua; Huang, Fuqiang
2015-06-01
Two compounds with the formulas of Na4Cu32Sn12S48·4H2O and K11Cu32Sn12S48·4H2O were synthesized via flux (with thiourea as reactive flux) and hydrothermal method, respectively. The black crystals of Na4Cu32Sn12S48·4H2O and K11Cu32Sn12S48·4H2O both crystallize in the cubic space group of Fm3̅c with the cell constants a = 17.921(2) Å and a = 18.0559(6) Å, respectively. The crystal structures feature a 3D open-framework with the unique [Cu8Sn6S24](z-) (z = 13 for Na4Cu32Sn12S48·4H2O; z = 14.75 for K11Cu32Sn12S48·4H2O) clusters acting as building blocks. The [Cu8Sn6S24](z-) cluster of the Th symmetry is built up by eight [CuS3] triangles and six [SnS4] tetrahedra. The powder samples were investigated by X-ray diffraction and optical absorption measurements. Both phase-pure compounds show multiabsorption character with a main absorption edge (2.0 eV for Na4Cu32Sn12S48·4H2O and 1.9 eV for K11Cu32Sn12S48·4H2O) and an additional absorption peak (1.61 eV for Na4Cu32Sn12S48·4H2O and 1.52 eV for K11Cu32Sn12S48·4H2O), which are perfectly consistent with the first-principle calculation results. The analyses of the density of states further reveal that the two optical absorption bands in each compound are attributed to the two transitions of Cu-3d-S-3p → Sn-5s. The multiband nature of two compounds also enhances photocatalytic activity under visible light irradiation, with which the degradation of methyl blue over Na4Cu32Sn12S48·4H2O reached 100% in 3 h. The 3D open-framework features also facilitate the ionic conductivity nature of the Na4Cu32Sn12S48·4H2O compound, which achieved ∼10(-5) S/cm at room temperature. PMID:25955506
Yifat, Jonathan; Gannot, Israel
2015-03-01
Early detection of malignant tumors plays a crucial role in the survivability chances of the patient. Therefore, new and innovative tumor detection methods are constantly searched for. Tumor-specific magnetic-core nano-particles can be used with an alternating magnetic field to detect and treat tumors by hyperthermia. For the analysis of the method effectiveness, the bio-heat transfer between the nanoparticles and the tissue must be carefully studied. Heat diffusion in biological tissue is usually analyzed using the Pennes Bio-Heat Equation, where blood perfusion plays an important role. Malignant tumors are known to initiate an angiogenesis process, where endothelial cell migration from neighboring vasculature eventually leads to the formation of a thick blood capillary network around them. This process allows the tumor to receive its extensive nutrition demands and evolve into a more progressive and potentially fatal tumor. In order to assess the effect of angiogenesis on the bio-heat transfer problem, we have developed a discrete stochastic 3D model & simulation of tumor-induced angiogenesis. The model elaborates other angiogenesis models by providing high resolution 3D stochastic simulation, capturing of fine angiogenesis morphological features, effects of dynamic sprout thickness functions, and stochastic parent vessel generator. We show that the angiogenesis realizations produced are well suited for numerical bio-heat transfer analysis. Statistical study on the angiogenesis characteristics was derived using Monte Carlo simulations. According to the statistical analysis, we provide analytical expression for the blood perfusion coefficient in the Pennes equation, as a function of several parameters. This updated form of the Pennes equation could be used for numerical and analytical analyses of the proposed detection and treatment method. PMID:24462603
NASA Technical Reports Server (NTRS)
Anderson, O. L.
1985-01-01
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.
Radiative heat conduction and the magnetorotational instability
NASA Astrophysics Data System (ADS)
Araya-Góchez, Rafael A.; Vishniac, Ethan T.
2004-12-01
A photon or a neutrino gas, semicontained by a non-diffusive particle species through scattering, comprises a rather peculiar magnetohydrodynamic fluid where the magnetic field is truly frozen only to the comoving volume associated with the mass density. Although radiative diffusion precludes a formal adiabatic treatment of compressive perturbations, we cast the energy equation in quasi-adiabatic form by assuming a negligible rate of energy exchange among species on the time-scale of the perturbation. This leads to a simplified dispersion relation for toroidal, non-axisymmetric magnetorotational modes when the accretion disc has comparable stress contributions from diffusive and non-diffusive components. The properties of the modes of fastest growth are shown to depend strongly on the compressibility of the mode, with a reduction in growth rate consistent with the results of Blaes & Socrates for axisymmetric modes. A clumpy disc structure is anticipated on the basis of the polarization properties of the fastest-growing modes. This analysis is accurate in the near-hole region of locally cooled, hyper-accreting flows if the electron gas becomes moderately degenerate such that non-conductive, thermalizing processes with associated electron-positron release (i.e. neutrino annihilation and neutrino absorption on to nuclei) are effectively blocked by high occupation of the Fermi levels.
Quantum-limited heat conduction over macroscopic distances
NASA Astrophysics Data System (ADS)
Partanen, Matti; Tan, Kuan Yen; Govenius, Joonas; Lake, Russell E.; Mäkelä, Miika K.; Tanttu, Tuomo; Möttönen, Mikko
2016-05-01
The emerging quantum technological apparatuses, such as the quantum computer, call for extreme performance in thermal engineering. Cold distant heat sinks are needed for the quantized electric degrees of freedom owing to the increasing packaging density and heat dissipation. Importantly, quantum mechanics sets a fundamental upper limit for the flow of information and heat, which is quantified by the quantum of thermal conductance. However, the short distance between the heat-exchanging bodies in the previous experiments hinders their applicability in quantum technology. Here, we present experimental observations of quantum-limited heat conduction over macroscopic distances extending to a metre. We achieved this improvement of four orders of magnitude in the distance by utilizing microwave photons travelling in superconducting transmission lines. Thus, it seems that quantum-limited heat conduction has no fundamental distance cutoff. This work establishes the integration of normal-metal components into the framework of circuit quantum electrodynamics, which provides a basis for the superconducting quantum computer. Especially, our results facilitate remote cooling of nanoelectronic devices using faraway in situ-tunable heat sinks. Furthermore, quantum-limited heat conduction is important in contemporary thermodynamics. Here, the long distance may lead to ultimately efficient mesoscopic heat engines with promising practical applications.
NASA Astrophysics Data System (ADS)
von Hebel, Christian; Rudolph, Sebastian; Huisman, Johan A.; van der Kruk, Jan; Vereecken, Harry
2013-04-01
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.
NASA Astrophysics Data System (ADS)
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
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.
2013-01-01
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. PMID:24244831
NASA Astrophysics Data System (ADS)
Przybycin, Anna M.; Scheck-Wenderoth, Magdalena; Schneider, Michael
2014-05-01
The European Molasse Basin is a wedge shaped Tertiary foreland basin situated at the northern front of the European Alps. The adjoining Alps consists of tectonic nappes composed of mostly limestone, sandstone and shale stacked since the Cretaceous. This nappe structures are disrupted by uplifted crystalline cores, of which the Tauern Body is a prominent example. The basin itself, filled with clastic sediments (the Molasse), is underlain by Mesozoic sedimentary successions and a crystalline crust of Paleozoic age. The Mesozoic sediments include the Upper Jurassic karstified aquifer (Malm), which is intensively used for geothermal energy production these days. Looking on the temperature distribution in the basin area, a distinct negative thermal anomaly can be found in the southeast of Munich within the Malm aquifer, which is poorly understood so far but is of big relevance for the geothermal energy production in this area. With our study we aim to explain this thermal anomaly by investigating the structure of the basin and the temperature driving processes therein. Therefore, we used a data based lithospheric-scale 3D structural model of the basin and the adjacent Alpine area and calculated the present day conductive thermal field. Our results indicate that the pronounced negative thermal anomaly in the Malm aquifer is controlled by the position and the shape of the Tauern Body within the Alpine mass and the thermal conductivity contrast between the crystalline material of the Tauern Body and the Calcareous Alps.
Anomalous heat conduction in asymmetric graphene Y junctions
NASA Astrophysics Data System (ADS)
Li, Chenhui; Pan, Feng; Niu, Chunyao; Chen, Weiguang; Jia, Yu
2015-12-01
Through MD simulation of the transient heat pulse propagation in asymmetric Y junction, we report a novel type of controllable heat conduction in graphene nanostructure. The Y junction consists of a steam breaking into a wide branch and a narrow branch. In contrast to the classic situation where heat conductivity is proportional to the cross-sectional area of the material, the transmitted part of the heat pulse in the narrow branch is anomalously much stronger than that in the wide branch. As we increase the width ratio between the wide branch and narrow branch, transmitted coefficient in the narrow branch decreases a little, while in the wide branch, it decreases sharply. Specifically under 2:1 width ratio, transmitted coefficient of the narrow branch is three times that of the coefficient of the wide branch. Further analysis shows that the anomalous heat conduction is primarily induced by the behavior of the longitude vibrational modes.
Kohlrausch Heat Conductivity Apparatus for Intermediate or Advanced Laboratory
ERIC Educational Resources Information Center
Jensen, H. G.
1970-01-01
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)
Experimental evidence of hyperbolic heat conduction in processed meat
Mitra, K.; Kumar, S.; Vedavarz, A.; Moallemi, M.K.
1995-08-01
The objective of this paper is to present experimental evidence of the wave nature of heat propagation in processed meat and to demonstrate that the hyperbolic heat conduction model is an accurate representation, on a macroscopic level, of the heat conduction process in such biological material. The value of the characteristic thermal time of a specific material, processed bologna meat, is determined experimentally. As a part of the work different thermophysical properties are also measured. The measured temperature distributions in the samples are compared with the Fourier results and significant deviation between the two is observed, especially during the initial stages of the transient conduction process. The measured values are found to match the theoretical non-Fourier hyperbolic predictions very well. The superposition of waves occurring inside the meat sample due to the hyperbolic nature of heat conduction is also proved experimentally. 14 refs., 7 figs., 2 tabs.
Heat Conduction in Homogeneous and Heterogeneous Billiard Systems
NASA Astrophysics Data System (ADS)
Mao, Jun-Wen; Li, You-Quan; Deng, Ling-Yun
We investigate the heat conduction in a modified Lorentz gas with freely rotating disks periodically placed along one-dimensional channel. The heat conductivity is dependent on the moment of inertia η of the disks, with a power-law decay when η > 1. By plotting the Poincaré surface of the section, we observe a contraction of phase space over the range of η > 1, which is sensitive to the initial condition. We find that the power-law decay of the heat conductivity is relevant to the mixing phase space. As a possible application, we model the heterostructure by connecting the segments of different η, and predict the analytical results of the temperature profiles and the heat conductivity, which are in good agreement with the numerical ones.
NASA Astrophysics Data System (ADS)
Ohira, Katsuhide; Ota, Atsuhito; Mukai, Yasuaki; Hosono, Takumi
2012-07-01
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.
Optical sensor for heat conduction measurement in biological tissue
NASA Astrophysics Data System (ADS)
Gutierrez-Arroyo, A.; Sanchez-Perez, C.; Aleman-Garcia, N.
2013-06-01
This paper presents the design of a heat flux sensor using an optical fiber system to measure heat conduction in biological tissues. This optoelectronic device is based on the photothermal beam deflection of a laser beam travelling in an acrylic slab this deflection is measured with a fiber optic angle sensor. We measure heat conduction in biological samples with high repeatability and sensitivity enough to detect differences in tissues from three chicken organs. This technique could provide important information of vital organ function as well as the detect modifications due to degenerative diseases or physical damage caused by medications or therapies.
A variable conductance heat pipe flight experiment - Performance in space
NASA Technical Reports Server (NTRS)
Wanous, D. J.; Marcus, B. D.; Kirkpatrick, J. P.
1975-01-01
The Ames Heat Pipe Experiment (AHPE) is a variable conductance heat pipe/radiator system which was launched aboard the OAO-C spacecraft in August, 1972. All available flight data was reviewed and those from a few orbits were selected for correlation with predictions from an analytical model of the system. The principal conclusion of this study is that gas controlled variable conductance heat pipes can perform reliably for long time periods in the space environment and can effectively provide temperature stabilization for spacecraft electronics. Furthermore, the performance of such systems can be adequately predicted using existing analysis tools.
Single-photon heat conduction in electrical circuits
NASA Astrophysics Data System (ADS)
Jones, P. J.; Huhtamäki, J. A. M.; Tan, K. Y.; Möttönen, M.
2012-02-01
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.
NASA Astrophysics Data System (ADS)
Alekseev, Gennady
2016-04-01
We consider the boundary value problem for stationary magnetohydrodynamic equations of electrically and heat conducting fluid under inhomogeneous mixed boundary conditions for electromagnetic field and temperature and Dirichlet condition for the velocity. The problem describes the thermoelectromagnetic flow of a viscous fluid in 3D bounded domain with the boundary consisting of several parts with different thermo- and electrophysical properties. The global solvability of the boundary value problem is proved and the apriori estimates of the solution are derived. The sufficient conditions on the data are established which provide a local uniqueness of the solution.
Fourier analysis of conductive heat transfer for glazed roofing materials
NASA Astrophysics Data System (ADS)
Roslan, Nurhana Lyana; Bahaman, Nurfaradila; Almanan, Raja Noorliyana Raja; Ismail, Razidah; Zakaria, Nor Zaini
2014-07-01
For low-rise buildings, roof is the most exposed surface to solar radiation. The main mode of heat transfer from outdoor via the roof is conduction. The rate of heat transfer and the thermal impact is dependent on the thermophysical properties of roofing materials. Thus, it is important to analyze the heat distribution for the various types of roofing materials. The objectives of this paper are to obtain the Fourier series for the conductive heat transfer for two types of glazed roofing materials, namely polycarbonate and polyfilled, and also to determine the relationship between the ambient temperature and the conductive heat transfer for these materials. Ambient and surface temperature data were collected from an empirical field investigation in the campus of Universiti Teknologi MARA Shah Alam. The roofing materials were installed on free-standing structures in natural ventilation. Since the temperature data are generally periodic, Fourier series and numerical harmonic analysis are applied. Based on the 24-point harmonic analysis, the eleventh order harmonics is found to generate an adequate Fourier series expansion for both glazed roofing materials. In addition, there exists a linear relationship between the ambient temperature and the conductive heat transfer for both glazed roofing materials. Based on the gradient of the graphs, lower heat transfer is indicated through polyfilled. Thus polyfilled would have a lower thermal impact compared to polycarbonate.
Gas heat conduction in an evacuated tube solar collector
Beikircher, T.; Goldemund, G.; Benz, N.
1996-10-01
We investigated experimentally the pressure dependency of the gas heat conduction in an evacuated plate-in-tube solar collector. A stationary heat loss experiment was built up with an electrically heated real-size collector model. The gas pressure was varied from 10{sup -3} to 10{sup 4} Pa, the temperatures of the absorber and the casing were held at 150{degree}C (electrical heaters) and 30{degree}C (water cooling), respectively. Losses by radiation and solid conduction were determined experimentally at pressures below 0.1 Pa. At higher pressures these background losses were subtracted from the total heat losses, to receive the heat losses by gas heat conduction. The experimental results were compared with approximate theoretical models. The onset of convection is in agreement with the usual theories for parallel plates taking the largest distance between the absorber and the gas tube as the plate distance. As a first approximation the pressure dependency of the gas heat conduction is described by the usual theory for parallel plates, taking the smallest distance between the absorber and the glass tube as the plate distance. 11 refs., 3 figs.
Fourier analysis of conductive heat transfer for glazed roofing materials
Roslan, Nurhana Lyana; Bahaman, Nurfaradila; Almanan, Raja Noorliyana Raja; Ismail, Razidah; Zakaria, Nor Zaini
2014-07-10
For low-rise buildings, roof is the most exposed surface to solar radiation. The main mode of heat transfer from outdoor via the roof is conduction. The rate of heat transfer and the thermal impact is dependent on the thermophysical properties of roofing materials. Thus, it is important to analyze the heat distribution for the various types of roofing materials. The objectives of this paper are to obtain the Fourier series for the conductive heat transfer for two types of glazed roofing materials, namely polycarbonate and polyfilled, and also to determine the relationship between the ambient temperature and the conductive heat transfer for these materials. Ambient and surface temperature data were collected from an empirical field investigation in the campus of Universiti Teknologi MARA Shah Alam. The roofing materials were installed on free-standing structures in natural ventilation. Since the temperature data are generally periodic, Fourier series and numerical harmonic analysis are applied. Based on the 24-point harmonic analysis, the eleventh order harmonics is found to generate an adequate Fourier series expansion for both glazed roofing materials. In addition, there exists a linear relationship between the ambient temperature and the conductive heat transfer for both glazed roofing materials. Based on the gradient of the graphs, lower heat transfer is indicated through polyfilled. Thus polyfilled would have a lower thermal impact compared to polycarbonate.
NASA Astrophysics Data System (ADS)
Barkett, Laura Ashley
In the past, fuel elements with multiple axial coolant channels have been used in nuclear propulsion applications. A novel fuel element concept that reduces weight and increases efficiency uses a stack of grooved rings. Each fuel ring consists of a hole on the interior and grooves across the top face. Many grooved ring configurations have been modeled, and a single flow channel for each design has been analyzed. For increased efficiency, a fuel ring with a higher surface-area-to-volume ratio is ideal. When grooves are shallower and they have a lower surface area, the results show that the exit temperature is higher. By coupling the physics of fluid flow with those of heat transfer, the effects on the cooler gas flowing through the grooves of the hot, fissioning ring can be predicted. Models also show differences in velocities and temperatures after dense boundary nodes are applied. Parametric studies were done to show how a pressure drop across the length of the channels will affect the exit temperatures of the gas. Geometric optimization was done to show the temperature distributions and pressure drops that result from the manipulation of various parameters, and the effects of model scaling was also investigated. The inverse Graetz numbers are plotted against Nusselt numbers, and the results of these values suggest that the gas quickly becomes fully developed, laminar flow, rather than constant turbulent conditions.
Quantal Heating of Conducting Electrons with Discrete Spectrum
Vitkalov, S. A.; Bykov, A. A.
2011-12-23
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.
An Experiment in Heat Conduction Using Hollow Cylinders
ERIC Educational Resources Information Center
Ortuno, M.; Marquez, A.; Gallego, S.; Neipp, C.; Belendez, A.
2011-01-01
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…
An Experiment in Heat Conduction Using Hollow Cylinders
ERIC Educational Resources Information Center
Ortuno, M.; Marquez, A.; Gallego, S.; Neipp, C.; Belendez, A.
2011-01-01
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
Heat Pipe Embedded AlSiC Plates for High Conductivity - Low CTE Heat Spreaders
Johnson, Matthew ); Weyant, J.; Garner, S. ); Occhionero, M. )
2010-01-07
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.
A Global Assessment of Oceanic Heat Loss: Conductive Cooling and Hydrothermal Redistribution of Heat
NASA Astrophysics Data System (ADS)
Hasterok, D. P.; Chapman, D. S.; Davis, E. E.
2011-12-01
A new dataset of ~15000 oceanic heat flow measurements is analyzed to determine the conductive heat loss through the seafloor. Many heat flow values in seafloor younger than 60 Ma are lower than predicted by models of conductively cooled lithosphere. This heat flow deficit is caused by ventilated hydrothermal circulation discharging at crustal outcrops or through thin sedimentary cover. Globally filtering of heat flow data to retain sites with sediment cover >400 m thick and located >60 km from the nearest seamount minimizes the effect of hydrothermal ventilation. Filtered heat flow exhibit a much higher correlation coefficient with seafloor age (up to 0.95 for filtered data in contrast to 0.5 for unfiltered data) and lower variability (reduction by 30%) within an age bin. A small heat flow deficit still persists at ages <25 Ma, possibly as a result of global filtering limitations and incomplete thermal rebound following sediment burial. Detailed heat flow surveys co-located with seismic data can identify environments favoring conductive heat flow; heat flow collected in these environments is higher than that determined by the global dataset, and is more consistent with conductive cooling of the lithosphere. The new filtered data analysis and a growing number of site specific surveys both support estimates of global heat loss in the range 40-47 TW. The estimated hydrothermal deficit is consistent with estimates from geochemical studies ~7 TW, but is a few TW lower than previous estimates derived from heat flow determinations.
NASA Astrophysics Data System (ADS)
Giordani, H.; Caniaux, G.; Prieur, L.; Paci, A.
2003-04-01
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.
Spherical harmonic analysis of earth's conductive heat flow
NASA Astrophysics Data System (ADS)
Hamza, V. M.; Cardoso, R. R.; Ponte Neto, C. F.
2008-04-01
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 of the earth. Estimated heat flow values were assigned to area elements for which experimental data are not available. However, no corrections were made to account for the hypothetical effects of regional-scale convection heat transfer in areas of oceanic crust. New sets of coefficients for 12° spherical harmonic expansion were calculated on the basis of the revised and homogenized data set. Maps derived on the basis of these coefficients reveal several new features in the global heat flow distribution. The magnitudes of heat flow anomalies of the ocean ridge segments are found to have mean values of less than 150 mW/m2. Also, the mean global heat flow values for the raw and binned data are found to fall in the range of 56-67 mW/m2, down by nearly 25% compared to the previous estimate of 1993, but similar to earlier assessments based on raw data alone. To improve the spatial resolution of the heat flow anomalies, the spherical harmonic expansions have been extended to higher degrees. Maps derived using coefficients for 36° harmonic expansion have allowed identification of new features in regional heat flow fields of several oceanic and continental segments. For example, lateral extensions of heat flow anomalies of active spreading centers have been outlined with better resolution than was possible in earlier studies. Also, the characteristics of heat flow variations in oceanic crust away from ridge systems are found to be typical of conductive cooling of the lithosphere, there being little need to invoke the hypothesis of unconfined hydrothermal circulation on regional scales. Calculations of global conductive heat loss, compatible with the observational data set, are found to fall in the range of 29-34 TW, nearly 25% less than the 1993 estimate, which rely on one-dimensional conductive cooling models.
Size Dependent Heat Conduction in One-Dimensional Diatomic Lattices
NASA Astrophysics Data System (ADS)
Tejal, N. Shah; P. N., Gajjar
2016-04-01
We study the size dependency of heat conduction in one-dimensional diatomic FPU-β lattices and establish that for low dimensional material, contribution from optical phonons is found more effective to the thermal conductivity and enhance heat transport in the thermodynamic limit N → ∞. For the finite size, thermal conductivity of 1D diatomic lattice is found to be lower than 1D monoatomic chain of the same size made up of the constituent particle of the diatomic chain. For the present 1D diatomic chain, obtained value of power divergent exponent of thermal conductivity 0.428±0.001 and diffusion exponent 1.2723 lead to the conclusions that increase in the system size, increases the thermal conductivity and existence of anomalous energy diffusion. Existing numerical data supports our findings.
Variable Conductance Heat Pipe Performance after Extended Periods of Freezing
NASA Astrophysics Data System (ADS)
Ellis, Michael C.; Anderson, William G.
2009-03-01
Radiators operating in lunar or Martian environments must be designed to reject the maximum heat load at the maximum sink temperature, while maintaining acceptable temperatures at lower powers or sink temperatures. Variable Conductance Heat Pipe (VCHP) radiators can passively adjust to these changing conditions. Due to the presence of non-condensable gas (NCG) within each VCHP, the active condensing section adjusts with changes in either thermal load or sink temperature. In a Constant Conductance Heat Pipe (CCHP) without NCG, it is possible for all of the water to freeze in the condenser, by either sublimation or vaporization. With a dry evaporator, startup is difficult or impossible. Several previous studies have shown that adding NCG suppresses evaporator dryout when the condenser is frozen. These tests have been for relatively short durations, with relatively short condensers. This paper describes freeze/thaw experiments involving a VCHP with similar dimensions to the current reactor and cavity cooling radiator heat pipe designs.
Thermally conductive cementitious grout for geothermal heat pump systems
Allan, Marita
2001-01-01
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.
Hydrodynamic Modeling of Heat Conduction in Nanoscale Systems.
Dong, Yuan; Guo, Zeng-Yuan
2015-04-01
Heat conduction in nanoscale systems has different behavior from bulk materials, which is applied to develop high performance thermoelectric material. The non-trivial behavior is caused by the ballistic-diffusive transport of heat carriers such as phonons. In this paper, we use the thermomass theory and phonon hydrodynamics model to establish a hydrodynamic model for phonon transport. In nanoscale systems, a Poiseuille flow of phonon gas is formed due to the boundary scattering. The thickness of boundary layer is proportional to the mean free paths of phonon. When the boundary layer thickness is comparable with the whole flow region, strong decrease of effective thermal conductivity happens. This method can serve as a fast evaluation method for nanoscale heat conduction. PMID:26353568
Computer Program For Variable-Conductance Heat Pipes
NASA Technical Reports Server (NTRS)
Antoniuk, D.
1992-01-01
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.
Application of Genetic Algorithms in Nonlinear Heat Conduction Problems
Khan, Waqar A.
2014-01-01
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
Neutrino Heat Conduction and Inhomogeneities in the Early Universe
NASA Technical Reports Server (NTRS)
Heckler, A.; Hogan, C. J.
1993-01-01
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).
Tunable heat conduction through coupled Fermi-Pasta-Ulam chains.
Su, Ruixia; Yuan, Zongqiang; Wang, Jun; Zheng, Zhigang
2015-01-01
We conduct a study on heat conduction through coupled Fermi-Pasta-Ulam (FPU) chains by using classical molecular dynamics simulations. Our attention is dedicated to showing how the phonon transport is affected by the interchain coupling. It has been well accepted that the heat conduction could be impeded by the interchain interaction due to the interface phonon scattering. However, recent theoretical and experimental studies suggest that the thermal conductivity of nanoscale materials can be counterintuitively enhanced by the interaction with the substrate. In the present paper, by consecutively varying the interchain coupling intensity, we observed both enhancement and suppression of thermal transport through the coupled FPU chains. For weak interchain couplings, it is found that the heat flux increases with the coupling intensity, whereas in the case of strong interchain couplings, the energy transport is found to be suppressed by the interchain interaction. Based on the phonon spectral energy density method, we attribute the enhancement of the energy transport to the excited phonon modes (in addition to the intrinsic phonon modes), while the upward shift of the high-frequency phonon branch and the interface phonon-phonon scattering account for the suppressed heat conduction. PMID:25679599
Structure of fast shocks in the presence of heat conduction
NASA Astrophysics Data System (ADS)
Tsai, C. L.; Chen, H. H.; Wu, B. H.; Lee, L. C.
2007-12-01
There are three types of magnetohydrodynamic (MHD) shocks: the fast shock, intermediate shock, and slow shock. The structure of slow shocks and intermediate shocks in the presence of heat conduction has been studied earlier [C. L. Tsai, R. H. Tsai, B. H. Wu, and L. C. Lee, Phys. Plasmas 9, 1185 (2002); C. L. Tsai, B. H. Wu, and L. C. Lee, Phys. Plasmas 12, 82501 (2005)]. Based on one-dimensional MHD numerical simulations with a heat conduction term, the evolution and structure of fast shocks are studied. The fast shock will form a foreshock in the presence of heat conduction. The foreshock is formed due to the heat flow from downstream to upstream and located in the immediate upstream of the main shock. In the steady state, the value of diffusion velocity Vd in the foreshock is found to nearly equal the upstream convection velocity in the fast shock frame. It is found that the density jump across the main shock in high Mach number case can be much larger than 4 in the early simulation time. However the density jump will gradually evolve to a value smaller than 4 at steady state. By using the modified Rankine-Hugoniot relations with heat flux, the density jump across the fast shock is examined for various upstream parameters. The results show that the calculated density jump with heat flux is very close to the simulation value and the density jump can far exceed the maximum value of 4 without heat conduction. The structure of foreshock and main shock is also studied under different plasma parameters, such as the heat conductivity K0, the ratio of upstream plasma pressure to magnetic pressure β1, Alfvén Mach number MA1, and the angle θ1 between shock normal and magnetic field. It is found that as the upstream shock parameters K0, β1, and MA1 increase or θ1 decreases, the width of foreshock Ld increases. The present results can be applied to fast shocks in the solar corona, solar wind, and magnetosphere, in which the heat conduction effects are important.
High Conductance Loop Heat Pipes for Space Application
NASA Astrophysics Data System (ADS)
Semenov, Sergey Y.; Cho, Wei-Lin; Jensen, Scott M.
2006-01-01
Three high conductance Loop Heat Pipes (LHPs) for the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) were designed, fabricated and thermal vacuum tested. One LHP with ammonia working fluid was designed for heat removal from a cryocooler cold head. Two ethane LHPs were designed to reject heat from the aft and fore optics to space. Thermal performance tests were performed in a vacuum chamber with attached masses simulating actual components. Thermal tests were also conducted on the bench and in an environmental chamber. The following features of the GIFTS LHPs were observed: (a) reliable startup and steady state operation with conductance as high as 83W/°C at various temperatures; (b) precision temperature control using compensation chamber heater during thermal cycling. Heat input power and condenser temperatures were varied periodically, while evaporator was maintained at a constant temperature. Temperature of the evaporator heat input surface fluctuated only by a fraction of a degree; (c) in addition there was no thermal performance degradation after 16 month of storage. The LHPs are installed on the instrument and waiting for a launch platform.
3D Printing of Graphene Aerogels.
Zhang, Qiangqiang; Zhang, Feng; Medarametla, Sai Pradeep; Li, Hui; Zhou, Chi; Lin, Dong
2016-04-01
3D printing of a graphene aerogel with true 3D overhang structures is highlighted. The aerogel is fabricated by combining drop-on-demand 3D printing and freeze casting. The water-based GO ink is ejected and freeze-cast into designed 3D structures. The lightweight (<10 mg cm(-3) ) 3D printed graphene aerogel presents superelastic and high electrical conduction. PMID:26861680
Modelling heat conduction in polycrystalline hexagonal boron-nitride films.
Mortazavi, Bohayra; Pereira, Luiz Felipe C; Jiang, Jin-Wu; Rabczuk, Timon
2015-01-01
We conducted extensive molecular dynamics simulations to investigate the thermal conductivity of polycrystalline hexagonal boron-nitride (h-BN) films. To this aim, we constructed large atomistic models of polycrystalline h-BN sheets with random and uniform grain configuration. By performing equilibrium molecular dynamics (EMD) simulations, we investigated the influence of the average grain size on the thermal conductivity of polycrystalline h-BN films at various temperatures. Using the EMD results, we constructed finite element models of polycrystalline h-BN sheets to probe the thermal conductivity of samples with larger grain sizes. Our multiscale investigations not only provide a general viewpoint regarding the heat conduction in h-BN films but also propose that polycrystalline h-BN sheets present high thermal conductivity comparable to monocrystalline sheets. PMID:26286820
Modelling heat conduction in polycrystalline hexagonal boron-nitride films
Mortazavi, Bohayra; Pereira, Luiz Felipe C.; Jiang, Jin-Wu; Rabczuk, Timon
2015-01-01
We conducted extensive molecular dynamics simulations to investigate the thermal conductivity of polycrystalline hexagonal boron-nitride (h-BN) films. To this aim, we constructed large atomistic models of polycrystalline h-BN sheets with random and uniform grain configuration. By performing equilibrium molecular dynamics (EMD) simulations, we investigated the influence of the average grain size on the thermal conductivity of polycrystalline h-BN films at various temperatures. Using the EMD results, we constructed finite element models of polycrystalline h-BN sheets to probe the thermal conductivity of samples with larger grain sizes. Our multiscale investigations not only provide a general viewpoint regarding the heat conduction in h-BN films but also propose that polycrystalline h-BN sheets present high thermal conductivity comparable to monocrystalline sheets. PMID:26286820
Hyperbolic Heat Conduction in a Functionally Graded Hollow Sphere
NASA Astrophysics Data System (ADS)
Babaei, M. H.; Chen, Z. T.
2008-08-01
Non-Fourier hyperbolic heat conduction in a heterogeneous sphere is investigated in this article. Except for the thermal relaxation time, which is assumed to be constant, all other material properties vary continuously within the sphere in the radial direction following a power law. Boundary conditions of the sphere are assumed to be spherically symmetric, leading to a one-dimensional heat conduction problem. The problem is solved analytically in the Laplace domain, and the final results in the time domain are obtained using numerical inversion of the Laplace transform. The transient responses of temperature and heat flux are investigated for different non-homogeneity parameters and normalized thermal relaxation constants. The current results for the specific case of a homogeneous sphere are validated by results available in the literature.
Nonconventional thermodynamics, indeterminate couple stress elasticity and heat conduction
NASA Astrophysics Data System (ADS)
Alber, H.-D.; Hutter, K.; Tsakmakis, Ch.
2016-05-01
We present a phenomenological thermodynamic framework for continuum systems exhibiting responses which may be nonlocal in space and for which short time scales may be important. Nonlocality in space is engendered by state variables of gradient type, while nonlocalities over time can be modelled, e.g. by assuming the rate of the heat flux vector to enter into the heat conduction law. The central idea is to restate the energy budget of the system by postulating further balance laws of energy, besides the classical one. This allows for the proposed theory to deal with nonequilibrium state variables, which are excluded by the second law in conventional thermodynamics. The main features of our approach are explained by discussing micropolar indeterminate couple stress elasticity and heat conduction theories.
Variable conductance heat pipes from the laboratory to space
NASA Technical Reports Server (NTRS)
Kirkpatrick, J. P.
1973-01-01
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.
NASA Astrophysics Data System (ADS)
Zhang, Fan; He, Wen; He, Longbiao; Rong, Zuochao
2015-12-01
The wide concern on absolute pressure calibration of acoustic transducers at low frequencies prompts the development of the pistonphone method. At low frequencies, the acoustic properties of pistonphones are governed by the pressure leakage and the heat conduction effects. However, the traditional theory for these two effects applies a linear superposition of two independent correction models, which differs somewhat from their coupled effect at low frequencies. In this paper, acoustic properties of pistonphones at low frequencies in full consideration of the pressure leakage and heat conduction effects have been quantitatively studied, and the explicit expression for the generated sound pressure has been derived. With more practical significance, a coupled correction expression for these two effects of pistonphones has been derived. In allusion to two typical pistonphones, the NPL pistonphone and our developed infrasonic pistonphone, comparisons were done for the coupled correction expression and the traditional one, whose results reveal that the traditional one produces maximum insufficient errors of about 0.1 dB above the lower limiting frequencies of two pistonphones, while at lower frequencies, excessive correction errors with an explicit limit of about 3 dB are produced by the traditional expression. The coupled correction expression should be adopted in the absolute pressure calibration of acoustic transducers at low frequencies. Furthermore, it is found that the heat conduction effect takes a limiting deviation of about 3 dB for the pressure amplitude and a small phase difference as frequency decreases, while the pressure leakage effect remarkably drives the pressure amplitude to attenuate and the phase difference tends to be 90 as the frequency decreases. The pressure leakage effect plays a more important role on the low frequency property of pistonphones.
Thermal Conductivity of Lower Mantle Minerals and Heat Flux Across the Core-Mantle Boundary
NASA Astrophysics Data System (ADS)
Bennett, C.; Rainey, E.; Kavner, A.
2014-12-01
The thermal conductivity properties of the minerals comprising the Earth's lowermost mantle control the core-mantle boundary heat flux, and are therefore critical properties for determining the thermal state and evolution of the Earth's interior. Here we present measurements of the thermal conductivity of lower mantle oxides and silicates as a function of pressure, temperature, and iron content determined in the laser-heated diamond anvil cell using a combination of measurements and 3-D modeling. Our models and measurements demonstrate that the measured steady-state temperature and its increase with increasing laser power depend on the sample thermal conductivity as well as the experimental geometry, enabling measurements of the pressure- and temperature- dependence of lattice thermal conductivity in the laser-heated diamond anvil cell. We applied this technique to iron-bearing silicate perovskites and MgO at lower mantle pressure and temperature conditions. For MgO, we determine the increase in thermal conductivity k with density ρ to be ∂lnk/∂lnρ=4.7±0.6, which is in agreement with results obtained using other experimental and computational techniques. For (Mg0.8,Fe0.2)SiO3 perovskite, we find ∂lnk/∂lnρ=2.9±0.6. We use these values in combination with independent computational and experimental results to determine thermal conductivity of lower mantle minerals up to core-mantle boundary conditions. We combine the mineralogical thermal conductivity estimates in a composite model and include an estimate for the radiative contribution to thermal conductivity. Our new value of the thermal conductivity of the lowermost mantle is ~5-6 W/m/K and is sensitive to the details of the lower mantle assemblage, but is relatively insensitive to pressure and temperature. We combine our mantle thermal conductivity with models for the lower mantle boundary layer to generate a series of two-dimensional maps of core-mantle boundary heat flux, which emphasize the importance of lateral variations in phase and boundary layer thickness. Our values imply a total core-mantle boundary heat flow of 6-8 TW, which is sufficient to drive plumes and convection, is consistent with current geochemical estimates for mantle heat content, and permits a slow growth rate for the inner core.
Validation of a heat conduction model for finite domain, non-uniformly heated, laminate bodies
NASA Astrophysics Data System (ADS)
Desgrosseilliers, Louis; Kabbara, Moe; Groulx, Dominic; White, Mary Anne
2015-08-01
Infrared thermographic validation is shown for a closed-form analytical heat conduction model for non-uniformly heated, laminate bodies with an insulated domain boundary. Experiments were conducted by applying power to rectangular electric heaters and cooled by natural convection in air, but also apply to constant-temperature heat sources and forced convection. The model accurately represents two-dimensional laminate heat conduction behaviour giving rise to heat spreading using one-dimensional equations for the temperature distributions and heat transfer rates under steady-state and pseudo-steady-state conditions. Validation of the model with an insulated boundary (complementing previous studies with an infinite boundary) provides useful predictions of heat spreading performance and simplified temperature uniformity calculations (useful in log-mean temperature difference style heat exchanger calculations) for real laminate systems such as found in electronics heat sinks, multi-ply stovetop cookware and interface materials for supercooled salt hydrates. Computational determinations of implicit insulated boundary condition locations in measured data, required to assess model equation validation, were also demonstrated. Excellent goodness of fit was observed (both root-mean-square error and R 2 values), in all cases except when the uncertainty of low temperatures measured via infrared thermography hindered the statistical significance of the model fit. The experimental validation in all other cases supports use of the model equations in design calculations and heat exchange simulations.
High temperature electrically conducting ceramic heating element and control system
NASA Technical Reports Server (NTRS)
Halbach, C. R.; Page, R. J.
1975-01-01
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.
NASA Astrophysics Data System (ADS)
Pletinckx, D.
2011-09-01
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.
Sensitivity Equation for Transient Three-Dimensional Heat Conduction Problem with Moving Heat Source
NASA Astrophysics Data System (ADS)
Ivanovic, Ivana; Sedmak, Aleksandar
2010-09-01
Sensitivity analysis of transient three-dimensional heat conduction in a plate during process of welding is performed. Crank-Nicolson method with multi-step Douglas-Gunn Alternating Direction Implicit (ADI) method is used for the solution of heat conduction equation with convection boundary conditions at all surfaces, and with heat source at the top surface moving with a constant velocity. Sensitivity equation method (SEM) is applied for sensitivity calculations. It is shown that SEM is a set of straightforward operations in the case of heat conduction equation. Development of the sensitivity equation with respect to the power of the heat source is demonstrated and final results for this sensitivity are presented.
NASA Astrophysics Data System (ADS)
Yvonne, Cherubini; Mauro, Cacace; Scheck-Wenderoth, Magdalena
2013-04-01
Faults can provide permeable pathways for fluids at a variety of scales, from great depth in the crust to flow through fractured aquifers, geothermal fields, and hydrocarbon reservoirs (Barton et al. 1995). In terms of geothermal energy exploration, it is essential to understand the role of faults and their impact on the thermal field and fluid system. 3D numerical simulations provide a useful tool for investigating the active physical processes in the subsurface. To assess the influence of major fault zones on the thermal field and fluid system, 3D coupled fluid and heat transport simulations are carried out. The study is based on a recently published structural model of the Brandenburg area, which is located in the south-eastern part of the Northeast German Basin (NEGB) (Noack et al. 2010). Two major fault zones of the Elbe Fault System (Gardelegen and Lausitz Escarpments) vertically offset the pre-Permian basement against the Permian to Cenozoic basin fill at the southern margin by several km (Scheck et al. 2002). Within the numerical models, these two major fault zones are represented as equivalent porous media and vertical discrete elements. The coupled system of equations describing fluid flow and heat transport in saturated porous media are numerically solved by the Finite Element software FEFLOW® (Diersch, 2002). Different possible geological scenarios are modelled and compared to a simulation in which no faults are considered. In one scenario the fault zones are set as impermeable. In this case, the thermal field is similar to the no fault model. Fluid flow is redirected because the fault zones act as hydraulic barriers that prevent a lateral fluid advection into the fault zones. By contrast, modelled permeable fault zones induce a pronounced thermal signature with distinctly cooler temperatures than in the no fault model. Fluid motion within the fault is initially triggered by advection due to hydraulic head gradients, but may be even enhanced by buoyancy forces caused by density gradients mainly occurring due to differences in the temperature. References: Barton, C.A., Zoback, M.D., Moos, D., 1995. Fluid flow along potentially active faults in crystalline rock. Geology 23 (8), 683-686.
Conjugate conductive, convective, and radiative heat transfer in rocket engines
Naraghi, M.H.N.; DeLise, J.C.
1995-12-31
A comprehensive conductive, convective and radiative model for thermal analysis of rocket thrust chambers and nozzles is presented. In this model, the rocket thrust chamber and nozzle are subdivided into a number of stations along the longitudinal direction. At each station a finite element scheme is used to evaluate wall temperature distribution. The hot-gas-side convective heat transport is evaluated by numerically solving the compressible boundary layer equations and the radiative fluxes are evaluated by implementing an exchange factor scheme. The convective heat flux in the cooling channel is modeled based on the existing closed form correlations for rocket cooling channels. The conductive, convective and radiative processes are conjugated through an iterative procedure. The hot-gas-side heat transfer coefficients evaluated based on this model are compared to the experimental results reported in the literature. The computed convective heat transfer coefficients agree very well with experimental data for most of the engine except the throat where a discrepancy of approximately 20% exists. The model is applied to a typical regeneratively cooled rocket engine and the resulting wall temperature and heat flux distribution are presented.
Thermal conductivity, electrical conductivity and specific heat of copper-carbon fiber composite
NASA Technical Reports Server (NTRS)
Kuniya, Keiichi; Arakawa, Hideo; Kanai, Tsuneyuki; Chiba, Akio
1988-01-01
A new material of copper/carbon fiber composite is developed which retains the properties of copper, i.e., its excellent electrical and thermal conductivity, and the property of carbon, i.e., a small thermal expansion coefficient. These properties of the composite are adjustable within a certain range by changing the volume and/or the orientation of the carbon fibers. The effects of carbon fiber volume and arrangement changes on the thermal and electrical conductivity, and specific heat of the composite are studied. Results obtained are as follows: the thermal and electrical conductivity of the composite decrease as the volume of the carbon fiber increases, and were influenced by the fiber orientation. The results are predictable from a careful application of the rule of mixtures for composites. The specific heat of the composite was dependent, not on fiber orientation, but on fiber volume. In the thermal fatigue tests, no degradation in the electrical conductivity of this composite was observed.
Heat, Light, and Videotapes: Experiments in Heat Conduction Using Liquid Crystal Film.
ERIC Educational Resources Information Center
Bacon, Michael E.; And Others
1995-01-01
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
Heat, Light, and Videotapes: Experiments in Heat Conduction Using Liquid Crystal Film.
ERIC Educational Resources Information Center
Bacon, Michael E.; And Others
1995-01-01
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…
Heating rate controller for thermally stimulated conductivity and thermoluminescence measurements.
NASA Technical Reports Server (NTRS)
Manning, E. G.; Littlejohn, M. A.; Oakley, E. M.; Hutchby , J. A.
1972-01-01
A temperature controller is described which enables the temperature of a sample mounted on a cold finger to be varied linearly with time. Heating rates between 0.5 and 10 K/min can be achieved for temperatures between 90 and 300 K. Provision for terminating the sample heating at any temperature between these extremes is available. The temperature can be held at the terminating temperature or be reduced to the starting temperature in a matter of minutes. The controller has been used for thermally stimulated conductivity measurements and should be useful for thermoluminescence measurements as well.
Estimating interfacial thermal conductivity in metamaterials through heat flux mapping
Canbazoglu, Fatih M.; Vemuri, Krishna P.; Bandaru, Prabhakar R.
2015-04-06
The variability of the thickness as well as the thermal conductivity of interfaces in composites may significantly influence thermal transport characteristics and the notion of a metamaterial as an effective medium. The consequent modulations of the heat flux passage are analytically and experimentally examined through a non-contact methodology using radiative imaging, on a model anisotropic thermal metamaterial. It was indicated that a lower Al layer/silver interfacial epoxy ratio of ∼25 compared to that of a Al layer/alumina interfacial epoxy (of ∼39) contributes to a smaller deviation of the heat flux bending angle.
Development of a high capacity variable conductance heat pipe.
NASA Technical Reports Server (NTRS)
Kosson, R.; Hembach, R.; Edelstein, F.; Loose, J.
1973-01-01
The high-capacity, pressure-primed, tunnel-artery wick concept was used in a gas-controlled variable conductance heat pipe. A variety of techniques were employed to control the size of gas/vapor bubbles trapped within the artery. Successful operation was attained with a nominal 6-foot long, 1-inch diameter cold reservoir VCHP using ammonia working fluid and nitrogen control gas. The pipe contained a heat exchanger to subcool the liquid in the artery. Maximum transport capacity with a 46-inch effective length was 1200 watts level (more than 50,000 watt-inches) and 800 watts at 0.5-inch adverse tilt.
Heat conduction in graphene: experimental study and theoretical interpretation
NASA Astrophysics Data System (ADS)
Ghosh, S.; Nika, D. L.; Pokatilov, E. P.; Balandin, A. A.
2009-09-01
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.
Increasing Boiling Heat Transfer using Low Conductivity Materials
Mahamudur Rahman, Md; Pollack, Jordan; McCarthy, Matthew
2015-01-01
We report the counterintuitive mechanism of increasing boiling heat transfer by incorporating low-conductivity materials at the interface between the surface and fluid. By embedding an array of non-conductive lines into a high-conductivity substrate, in-plane variations in the local surface temperature are created. During boiling the surface temperature varies spatially across the substrate, alternating between high and low values, and promotes the organization of distinct liquid and vapor flows. By systematically tuning the peak-to-peak wavelength of this spatial temperature variation, a resonance-like effect is seen at a value equal to the capillary length of the fluid. Replacing ~18% of the surface with a non-conductive epoxy results in a greater than 5x increase in heat transfer rate at a given superheat temperature. This drastic and counterintuitive increase is shown to be due to optimized bubble dynamics, where ordered pathways allow for efficient removal of vapor and the return of replenishing liquid. The use of engineered thermal gradients represents a potentially disruptive approach to create high-efficiency and high-heat-flux boiling surfaces which are naturally insensitive to fouling and degradation as compared to other approaches. PMID:26281890
Increasing Boiling Heat Transfer using Low Conductivity Materials
NASA Astrophysics Data System (ADS)
Mahamudur Rahman, Md; Pollack, Jordan; McCarthy, Matthew
2015-08-01
We report the counterintuitive mechanism of increasing boiling heat transfer by incorporating low-conductivity materials at the interface between the surface and fluid. By embedding an array of non-conductive lines into a high-conductivity substrate, in-plane variations in the local surface temperature are created. During boiling the surface temperature varies spatially across the substrate, alternating between high and low values, and promotes the organization of distinct liquid and vapor flows. By systematically tuning the peak-to-peak wavelength of this spatial temperature variation, a resonance-like effect is seen at a value equal to the capillary length of the fluid. Replacing ~18% of the surface with a non-conductive epoxy results in a greater than 5x increase in heat transfer rate at a given superheat temperature. This drastic and counterintuitive increase is shown to be due to optimized bubble dynamics, where ordered pathways allow for efficient removal of vapor and the return of replenishing liquid. The use of engineered thermal gradients represents a potentially disruptive approach to create high-efficiency and high-heat-flux boiling surfaces which are naturally insensitive to fouling and degradation as compared to other approaches.
Revealing the complex conduction heat transfer mechanism of nanofluids.
Sergis, A; Hardalupas, Y
2015-12-01
Nanofluids are two-phase mixtures consisting of small percentages of nanoparticles (sub 1-10 %vol) inside a carrier fluid. The typical size of nanoparticles is less than 100 nm. These fluids have been exhibiting experimentally a significant increase of thermal performance compared to the corresponding carrier fluids, which cannot be explained using the classical thermodynamic theory. This study deciphers the thermal heat transfer mechanism for the conductive heat transfer mode via a molecular dynamics simulation code. The current findings are the first of their kind and conflict with the proposed theories for heat transfer propagation through micron-sized slurries and pure matter. The authors provide evidence of a complex new type of heat transfer mechanism, which explains the observed abnormal heat transfer augmentation. The new mechanism appears to unite a number of popular speculations for the thermal heat transfer mechanism employed by nanofluids as predicted by the majority of the researchers of the field into a single one. The constituents of the increased diffusivity of the nanoparticle can be attributed to mismatching of the local temperature profiles between parts of the surface of the solid and the fluid resulting in increased local thermophoretic effects. These effects affect the region surrounding the solid manifesting interfacial layer phenomena (Kapitza resistance). In this region, the activity of the fluid and the interactions between the fluid and the nanoparticle are elevated. Isotropic increased nanoparticle mobility is manifested as enhanced Brownian motion and diffusion effects. PMID:26058515
Revealing the complex conduction heat transfer mechanism of nanofluids
NASA Astrophysics Data System (ADS)
Sergis, A.; Hardalupas, Y.
2015-06-01
Nanofluids are two-phase mixtures consisting of small percentages of nanoparticles (sub 1-10 %vol) inside a carrier fluid. The typical size of nanoparticles is less than 100 nm. These fluids have been exhibiting experimentally a significant increase of thermal performance compared to the corresponding carrier fluids, which cannot be explained using the classical thermodynamic theory. This study deciphers the thermal heat transfer mechanism for the conductive heat transfer mode via a molecular dynamics simulation code. The current findings are the first of their kind and conflict with the proposed theories for heat transfer propagation through micron-sized slurries and pure matter. The authors provide evidence of a complex new type of heat transfer mechanism, which explains the observed abnormal heat transfer augmentation. The new mechanism appears to unite a number of popular speculations for the thermal heat transfer mechanism employed by nanofluids as predicted by the majority of the researchers of the field into a single one. The constituents of the increased diffusivity of the nanoparticle can be attributed to mismatching of the local temperature profiles between parts of the surface of the solid and the fluid resulting in increased local thermophoretic effects. These effects affect the region surrounding the solid manifesting interfacial layer phenomena (Kapitza resistance). In this region, the activity of the fluid and the interactions between the fluid and the nanoparticle are elevated. Isotropic increased nanoparticle mobility is manifested as enhanced Brownian motion and diffusion effects
Peletier, Mark A.; Redig, Frank; Vafayi, Kiamars
2014-09-01
We consider three one-dimensional continuous-time Markov processes on a lattice, each of which models the conduction of heat: the family of Brownian Energy Processes with parameter m (BEP(m)), a Generalized Brownian Energy Process, and the Kipnis-Marchioro-Presutti (KMP) process. The hydrodynamic limit of each of these three processes is a parabolic equation, the linear heat equation in the case of the BEP(m) and the KMP, and a nonlinear heat equation for the Generalized Brownian Energy Process with parameter a (GBEP(a)). We prove the hydrodynamic limit rigorously for the BEP(m), and give a formal derivation for the GBEP(a). We then formally derive the pathwise large-deviation rate functional for the empirical measure of the three processes. These rate functionals imply gradient-flow structures for the limiting linear and nonlinear heat equations. We contrast these gradient-flow structures with those for processes describing the diffusion of mass, most importantly the class of Wasserstein gradient-flow systems. The linear and nonlinear heat-equation gradient-flow structures are each driven by entropy terms of the form -log ρ; they involve dissipation or mobility terms of order ρ² for the linear heat equation, and a nonlinear function of ρ for the nonlinear heat equation.
Heating of foods in space-vehicle environments. [by conductive heat transfer
NASA Technical Reports Server (NTRS)
Bannerot, R. B.; Cox, J. E.; Chen, C. K.; Heidelbaugh, N. D.
1973-01-01
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.
Non-steady-state heat conduction in composite walls
Deconinck, Bernard; Pelloni, Beatrice; Sheils, Natalie E.
2014-01-01
The problem of heat conduction in one-dimensional piecewise homogeneous composite materials is examined by providing an explicit solution of the one-dimensional heat equation in each domain. The location of the interfaces is known, but neither temperature nor heat flux is prescribed there. Instead, the physical assumptions of their continuity at the interfaces are the only conditions imposed. The problem of two semi-infinite domains and that of two finite-sized domains are examined in detail. We indicate also how to extend the solution method to the setting of one finite-sized domain surrounded on both sides by semi-infinite domains, and on that of three finite-sized domains. PMID:24808751
A High Conductance Detachable Heat Switch for ADRs
NASA Astrophysics Data System (ADS)
Tai, C. Y.; Wong, Y.; Rodenbush, A. J.; Joshi, C. H.; Shirron, P. J.
2004-06-01
Adiabatic Demagnetization Refrigerators (ADRs) are being increasingly considered for instrumentation and detector cooling on space missions such as Constellation-X. A multistage ADR is presently under development to operate between 6 K and the detector temperature of 50 mK. Energen, Inc. has developed and demonstrated a high conductance detachable thermal link (the heat switch) for operation at sub-Kelvin temperatures using a high-force cryogenic magnetostrictive actuator. A more efficient detachable thermal link decreases the number of cooling stages, thereby reducing the weight, cost and complexity of the cooling system. This heat switch uses KelvinAll, a magnetostrictive material developed by Energen, as the active element. Unlike other magnetostrictive materials, KelvinAll operates over a broad temperature range. At cryogenic temperatures it delivers a long stroke allowing a large separation gap between the contacting surfaces when the switch is disengaged. This makes alignment and operation of the heat switch simple.
Comparative evaluation of fuel element heat conduction models
Panicker, M.; Dugan, E.T.; Anghaie, S.
1986-01-01
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.
NASA Technical Reports Server (NTRS)
Glass, David E.; Tamma, Kumar K.; Railkar, Sudhir B.
1989-01-01
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.
Schmidt, Aaron J; Chen, Xiaoyuan; Chen, Gang
2008-11-01
The relationship between pulse accumulation and radial heat conduction in pump-probe transient thermoreflectance (TTR) is explored. The results illustrate how pulse accumulation allows TTR to probe two thermal length scales simultaneously. In addition, the conditions under which radial transport effects are important are described. An analytical solution for anisotropic heat flow in layered structures is given, and a method for measuring both cross-plane and in-plane thermal conductivities of thermally anisotropic thin films is described. As verification, the technique is used to extract the cross-plane and in-plane thermal conductivities of highly ordered pyrolytic graphite. Results are found to be in good agreement with literature values. PMID:19045906
Superdiffusive heat conduction in semiconductor alloys. I. Theoretical foundations
NASA Astrophysics Data System (ADS)
Vermeersch, Bjorn; Carrete, Jesús; Mingo, Natalio; Shakouri, Ali
2015-02-01
Semiconductor alloys exhibit a strong dependence of effective thermal conductivity on measurement frequency. So far this quasiballistic behavior has only been interpreted phenomenologically, providing limited insight into the underlying thermal transport dynamics. Here, we show that quasiballistic heat conduction in semiconductor alloys is governed by Lévy superdiffusion. By solving the Boltzmann transport equation (BTE) with ab initio phonon dispersions and scattering rates, we reveal a transport regime with fractal space dimension 1 <α <2 and superlinear time evolution of mean-square energy displacement σ2(t ) ˜tβ(1 <β <2 ) . The characteristic exponents are directly interconnected with the order n of the dominant phonon scattering mechanism τ ˜ω-n(n >3 ) and cumulative conductivity spectra κΣ(τ ;Λ ) ˜(τ;Λ ) γ resolved for relaxation times or mean free paths through the simple relations α =3 -β =1 +3 /n =2 -γ . The quasiballistic transport inside alloys is no longer governed by Brownian motion, but instead is dominated by Lévy dynamics. This has important implications for the interpretation of thermoreflectance (TR) measurements with modified Fourier theory. Experimental α values for InGaAs and SiGe, determined through TR analysis with a novel Lévy heat formalism, match ab initio BTE predictions within a few percent. Our findings lead to a deeper and more accurate quantitative understanding of the physics of nanoscale heat-flow experiments.
Micro to Nano Scale Heat Conduction in Thermoelectric Materials
NASA Astrophysics Data System (ADS)
Maldovan, Martin
2011-03-01
Understanding and controlling heat transfer in solids is very important for increasing the efficiency of thermoelectric materials such as skutterudites, clatharates, superlattices, nanowires, and quantum dots. Although the mechanisms governing the thermal conductivity have been understood for years, a comprehensive theoretical method to calculate heat transfer, particularly at small scales, has not been available. This is mainly due to the complexity of anharmonic processes and phonon boundary scattering. We present a comprehensive theoretical model to calculate the thermal conductivity of thermoelectric materials at small length scales. The approach involves an exact calculation of the reduction of the phonon mean free paths due to boundary scattering and removes the need to solve the Boltzmann equation or to use adjustable terms as in the Callaway or Holland models. The analysis is based on the kinetic theory of transport processes and considers general expressions for dispersion relations, phonon mean free paths, and surface specularity parameters. The results show an excellent agreement with experiments for thin films, nanowires, and superlattices over a wide range of temperature and across multiple length scales. The theoretical approach can further be applied to a wide variety of problems involving the conduction of heat in micro/nanostructured thermoelectrics. This research was funded by the MIT Energy Initiative.
Fourier's heat conduction equation: History, influence, and connections
NASA Astrophysics Data System (ADS)
Narasimhan, T. N.
1999-02-01
The equation describing the conduction of heat in solids has, over the past two centuries, proved to be a powerful tool for analyzing the dynamic motion of heat as well as for solving an enormous array of diffusion-type problems in physical sciences, biological sciences, earth sciences, and social sciences. This equation was formulated at the beginning of the nineteenth century by one of the most gifted scholars of modern science, Joseph Fourier of France. A study of the historical context in which Fourier made his remarkable contribution and the subsequent impact his work has had on the development of modern science is as fascinating as it is educational. This paper is an attempt to present a picture of how certain ideas initially led to Fourier's development of the heat equation and how, subsequently, Fourier's work directly influenced and inspired others to use the heat diffusion model to describe other dynamic physical systems. Conversely, others concerned with the study of random processes found that the equations governing such random processes reduced, in the limit, to Fourier's equation of heat diffusion. In the process of developing the flow of ideas, the paper also presents, to the extent possible, an account of the history and personalities involved.
Multiscale Modeling of Heat Conduction in Carbon Nanotube Aerogels
NASA Astrophysics Data System (ADS)
Gong, Feng; Papavassiliou, Dimitrios; Duong, Hai
Carbon nanotube (CNT) aerogels have attracted a lot of interest due to their ultrahigh strength/weight and surface area/weight ratios. They are promising advanced materials used in energy storage systems, hydrogen storage media and weight-conscious devices such as satellites, because of their ultralight and highly porous quality. CNT aerogels can have excellent electrical conductivity and mechanical strength. However, the thermal conductivity of CNT aerogels are as low as 0.01-0.1 W/mK, which is five orders of magnitude lower than that of CNT (2000-5000 W/mK). To investigate the mechanisms for the low thermal conductivity of CNT aerogels, multiscale models are built in this study. Molecular dynamic (MD) simulations are first carried out to investigate the heat transfer between CNT and different gases (e.g. nitrogen and hydrogen), and the thermal conductance at CNT-CNT interface. The interfacial thermal resistances of CNT-gas and CNT-CNT are estimated from the MD simulations. Mesoscopic modeling of CNT aerogels are then built using an off-lattice Monte Carlo (MC) simulations to replicate the realistic CNT aerogels. The interfacial thermal resistances estimated from MD simulations are used as inputs in the MC models to predict the thermal conductivity of CNT aerogels. The volume fractions and the complex morphologies of CNTs are also quantified to study their effects on the thermal conductivity of CNT aerogels. The quantitative findings may help researchers to obtain the CNT aerogels with expected thermal conductivity.
Normal heat conductivity in two-dimensional scalar lattices
NASA Astrophysics Data System (ADS)
Savin, A. V.; Zolotarevskiy, V.; Gendelman, O. V.
2016-01-01
The paper revisits recent counterintuitive results on the divergence of the heat conduction coefficient in two-dimensional lattices. It was reported that in certain lattices with on-site potential, for which a one-dimensional chain has convergent conductivity, the latter diverges in the 2D counterpart. We demonstrate that this conclusion is an artifact caused by the insufficient size of the simulated system. To overcome computational restrictions, a ribbon of relatively small width is simulated instead of a more traditional square specimen. It is further demonstrated that the heat conduction coefficient in the “long” direction of the ribbon ceases to depend on the width, as the latter achieves only 10 to 20 chains. So, one can consider the dynamics of much longer systems, than in the traditional setting, and still can gain reliable information regarding the 2D lattice. It turns out that for all considered models, for which the conductivity is convergent in the 1D case, it is convergent also in the 2D case. At the same time, however, the length of the system, necessary to reveal the convergence in the 2D case, may be much bigger than in its 1D counterpart.
Thermal conductivity measurements of proton-heated warm dense matter
NASA Astrophysics Data System (ADS)
McKelvey, A.; Fernandez-Panella, A.; Hua, R.; Kim, J.; King, J.; Sio, H.; McGuffey, C.; Kemp, G. E.; Freeman, R. R.; Beg, F. N.; Shepherd, R.; Ping, Y.
2015-06-01
Accurate knowledge of conductivity characteristics in the strongly coupled plasma regime is extremely important for ICF processes such as the onset of hydrodynamic instabilities, thermonuclear burn propagation waves, shell mixing, and efficient x-ray conversion of indirect drive schemes. Recently, an experiment was performed on the Titan laser platform at the Jupiter Laser Facility to measure the thermal conductivity of proton-heated warm dense matter. In the experiment, proton beams generated via target normal sheath acceleration were used to heat bi-layer targets with high-Z front layers and lower-Z back layers. The stopping power of a material is approximately proportional to Z2 so a sharp temperature gradient is established between the two materials. The subsequent thermal conduction from the higher-Z material to the lower-Z was measured with time resolved streaked optical pyrometry (SOP) and Fourier domain interferometry (FDI) of the rear surface. Results will be used to compare predictions from the thermal conduction equation and the Wiedemann-Franz Law in the warm dense matter regime. Data from the time resolved diagnostics for Au/Al and Au/C Targets of 20-200 nm thickness will be presented.
Calibrated Heat Flow Model for Determining the Heat Conduction Losses in Laser Cutting of CFRP
NASA Astrophysics Data System (ADS)
Mucha, P.; Weber, R.; Speker, N.; Berger, P.; Sommer, B.; Graf, T.
Laser machining has great potential regarding automation in fabrication of CFRP (carbon-fiber-reinforced plastics) parts, due to the nearly force and tool-wear free processing at high process speeds. The high vaporization temperatures and the large heat conductivity of the carbon fibers lead to a large heat transport into the sample. This causes the formation of a heat-affected zone and a decrease of the process speed. In the present paper,an analytical heat flow model was adapted in order to understand and investigate the heat conduction losses. Thermal sensors were embedded in samples at different distances from the kerf to fit the calculated to the measured temperatures. Heat conduction losses of up to 30% of the laser power were determined. Furthermore, the energy not absorbed by the sample, the energy for sublimating the composite material in the kerf, the energy for the formation of the HAZ, and the residual heat in the sample are compared in an energy balance.
Heat conduction in multifunctional nanotrusses studied using Boltzmann transport equation
NASA Astrophysics Data System (ADS)
Dou, Nicholas G.; Minnich, Austin J.
2016-01-01
Materials that possess low density, low thermal conductivity, and high stiffness are desirable for engineering applications, but most materials cannot realize these properties simultaneously due to the coupling between them. Nanotrusses, which consist of hollow nanoscale beams architected into a periodic truss structure, can potentially break these couplings due to their lattice architecture and nanoscale features. In this work, we study heat conduction in the exact nanotruss geometry by solving the frequency-dependent Boltzmann transport equation using a variance-reduced Monte Carlo algorithm. We show that their thermal conductivity can be described with only two parameters, solid fraction and wall thickness. Our simulations predict that nanotrusses can realize unique combinations of mechanical and thermal properties that are challenging to achieve in typical materials.
Extremes of heat conduction-Pushing the boundaries of the thermal conductivity of materials
Cahill, DG
2012-09-12
Thermal conductivity is a familiar property of materials: silver conducts heat well, and plastic does not. In recent years, an interdisciplinary group of materials scientists, engineers, physicists, and chemists have succeeded in pushing back long-established limits in the thermal conductivity of materials. Carbon nanotubes and graphene are at the high end of the thermal conductivity spectrum due to their high sound velocities and relative lack of processes that scatter phonons. Unfortunately, the superlative thermal properties of carbon nanotubes have not found immediate application in composites or interface materials because of difficulties in making good thermal contact with the nanotubes. At the low end of the thermal conductivity spectrum, solids that combine order and disorder in the random stacking of two-dimensional crystalline sheets, so-called "disordered layered crystals," show a thermal conductivity that is only a factor of 2 larger than air. The cause of this low thermal conductivity may be explained by the large anisotropy in elastic constants that suppresses the density of phonon modes that propagate along the soft direction. Low-dimensional quantum magnets demonstrate that electrons and phonons are not the only significant carriers of heat. Near room temperature, the spin thermal conductivity of spin-ladders is comparable to the electronic thermal conductivities of metals. Our measurements of nanoscale thermal transport properties employ a variety of ultrafast optical pump-probe metrology tools that we have developed over the past several years. We are currently working to extend these techniques to high pressures (60 GPa), high magnetic fields (5 T), and high temperatures (1000 K).
NASA Astrophysics Data System (ADS)
Meulien Ohlmann, Odile
2013-02-01
Today the industry offers a chain of 3D products. Learning to "read" and to "create in 3D" becomes an issue of education of primary importance. 25 years professional experience in France, the United States and Germany, Odile Meulien set up a personal method of initiation to 3D creation that entails the spatial/temporal experience of the holographic visual. She will present some different tools and techniques used for this learning, their advantages and disadvantages, programs and issues of educational policies, constraints and expectations related to the development of new techniques for 3D imaging. Although the creation of display holograms is very much reduced compared to the creation of the 90ies, the holographic concept is spreading in all scientific, social, and artistic activities of our present time. She will also raise many questions: What means 3D? Is it communication? Is it perception? How the seeing and none seeing is interferes? What else has to be taken in consideration to communicate in 3D? How to handle the non visible relations of moving objects with subjects? Does this transform our model of exchange with others? What kind of interaction this has with our everyday life? Then come more practical questions: How to learn creating 3D visualization, to learn 3D grammar, 3D language, 3D thinking? What for? At what level? In which matter? for whom?
NASA Astrophysics Data System (ADS)
Sheremet, Mikhail A.; Miroshnichenko, Igor V.
2015-11-01
Three-dimensional transient natural convection in a cubic enclosure having finite thickness solid walls subject to opposing and horizontal temperature gradient has been investigated by a finite volume method. The turbulent flow considered into the volume is described mathematically by the 3D Reynolds averaged Navier-Stokes equations using the standard k-ɛ model with wall functions, including the energy equation. The velocity and temperature distributions were calculated at fixed Prandtl number, Pr = 0.7 and different values of the Rayleigh number, thermal conductivity ratio and dimensionless time. Three-dimensional velocity and temperature fields, temperature profiles at middle cross-sections and average Nusselt numbers have been presented. It has been found that an insertion of the third coordinate for the conjugate problem leads to a decrease in the average Nusselt number by 5.8 % in conditions of a stationary heat transfer mode.
Variable Conductance Heat Pipes for Radioisotope Stirling Systems
NASA Technical Reports Server (NTRS)
Anderson, William G.; Tarau, Calin
2008-01-01
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.
Fabrication and test of a variable conductance heat pipe
NASA Technical Reports Server (NTRS)
Lehtinen, A. M.
1978-01-01
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.
Variable Conductance Heat Pipe Radiators for Lunar and Martian Environments
NASA Astrophysics Data System (ADS)
Anderson, William G.; Ellis, Michael C.; Walker, Kara L.
2009-03-01
Long-term Lunar and Martian surface systems present challenges to thermal system design, including changes in thermal load, and large changes in the thermal environment between Lunar (or Martian) day and night. For example, the heat sink temperature at the Lunar equator can vary from 210 to 315 K. The radiator must be sized to reject the design power at the maximum temperature, but must also be able to accommodate both the changing heat sink temperature, as well as changes in power. Variable Conductance Heat Pipe (VCHP) radiators were examined for the main reactor of a fission surface power system, as well as the cavity cooling radiator. A VCHP radiator was designed for Lunar Equator that is capable of maintaining a 16 K temperature drop with a 4% addition to overall mass. Without the VCHP the radiator would experience a 43 K drop in temperature. This design is also capable of handling turndown on the power without an effect to the outlet temperature. At Shackleton Crater, the temperature drop for a conventional heat pipe radiator is small enough that a VCHP is not beneficial at constant power. However, a VCHP will allow turndown ratios of 5:1 or more. A conventional radiator can not be turned down more than 2:1, without valves to bypass part of the radiator. VCHPs are also easier to start than conventional radiators, since the gas-loading prevents sublimation from the evaporator when the condenser is frozen.
Sodium Variable Conductance Heat Pipe for Radioisotope Stirling Systems
NASA Technical Reports Server (NTRS)
Tarau, Calin; Anderson, William G.; Walker, Kara
2009-01-01
In a Stirling radioisotope system, heat must continually be removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the converter stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, and also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) has been designed to allow multiple stops and restarts of the Stirling convertor in an Advanced Stirling Radioisotope Generator (ASRG). When the Stirling convertor is turned off, the VCHP will activate when the temperatures rises 30 C above the setpoint temperature. A prototype VCHP with sodium as the working fluid was fabricated and tested in both gravity aided and against gravity conditions for a nominal heater head temperature of 790 C. The results show very good agreement with the predictions and validate the model. The gas front was located at the exit of the reservoir when heater head temperature was 790 C while cooling was ON, simulating an operating Advanced Stirling Converter (ASC). When cooling stopped, the temperature increased by 30 C, allowing the gas front to move past the radiator, which transferred the heat to the case. After resuming the cooling flow, the front returned at the initial location turning OFF the VCHP. The against gravity working conditions showed a colder reservoir and faster transients.
Analytical Solutions of Heat-Conduction Problems with Time-Varying Heat-Transfer Coefficients
NASA Astrophysics Data System (ADS)
Kudinov, V. A.; Eremin, A. V.; Stefanyuk, E. V.
2015-05-01
The problem on heat conduction of an infinite plate with a heat-transfer coefficient changing linearly with time for third-kind boundary conditions was solved analytically based on determination of the front of a temperature disturbance in this plate and introduction of additional boundary conditions. On the basis of the solution obtained, graphs of the distribution of isotherms in the indicated plate and the velocities of their movement along a spatial variable in it were constructed. As a result of the solution of the inverse problem on the heat conduction of the infinite plate with the use of the results of numerical calculation of the change in its temperature at any point on the indicated spatial coordinate, the Predvoditelev number was identified with an accuracy of 2%, which made it possible to determine the time dependence of the heat-transfer coefficient of the plate.
NASA Technical Reports Server (NTRS)
Kachanov, Mark
1998-01-01
Analysis of the effective thermal conductivity of ceramic coatings and its relation to the microstructure continued. Results (obtained in Task 1) for the three-dimensional problem of heat conduction in a solid containing an inclusion (or, in particular, cavity - thermal insulator) of the ellipsoidal shape, were further advanced in the following two directions: (1) closed form expressions of H tensor have been derived for special cases of ellipsoidal cavity geometry: spheroid, crack-like spheroidal cavity and needle shaped spheroidal cavity; (2) these results for one cavity have been incorporated to construct heat energy potential for a solid with many spheroidal cavities (in the approximation of non-interacting defects). This problem constitutes a basic building block for further analyses.
Scanning thermal microscopy with heat conductive nanowire probes.
Timofeeva, Maria; Bolshakov, Alexey; Tovee, Peter D; Zeze, Dagou A; Dubrovskii, Vladimir G; Kolosov, Oleg V
2016-03-01
Scanning thermal microscopy (SThM), which enables measurement of thermal transport and temperature distribution in devices and materials with nanoscale resolution is rapidly becoming a key approach in resolving heat dissipation problems in modern processors and assisting development of new thermoelectric materials. In SThM, the self-heating thermal sensor contacts the sample allowing studying of the temperature distribution and heat transport in nanoscaled materials and devices. The main factors that limit the resolution and sensitivities of SThM measurements are the low efficiency of thermal coupling and the lateral dimensions of the probed area of the surface studied. The thermal conductivity of the sample plays a key role in the sensitivity of SThM measurements. During the SThM measurements of the areas with higher thermal conductivity the heat flux via SThM probe is increased compared to the areas with lower thermal conductivity. For optimal SThM measurements of interfaces between low and high thermal conductivity materials, well defined nanoscale probes with high thermal conductivity at the probe apex are required to achieve a higher quality of the probe-sample thermal contact while preserving the lateral resolution of the system. In this paper, we consider a SThM approach that can help address these complex problems by using high thermal conductivity nanowires (NW) attached to a tip apex. We propose analytical models of such NW-SThM probes and analyse the influence of the contact resistance between the SThM probe and the sample studied. The latter becomes particularly important when both tip and sample surface have high thermal conductivities. These models were complemented by finite element analysis simulations and experimental tests using prototype probe where a multiwall carbon nanotube (MWCNT) is exploited as an excellent example of a high thermal conductivity NW. These results elucidate critical relationships between the performance of the SThM probe on one hand and thermal conductivity, geometry of the probe and its components on the other. As such, they provide a pathway for optimizing current SThM for nanothermal studies of high thermal conductivity materials. Comparison between experimental and modeling results allows us to provide direct estimates of the contact thermal resistances for various interfaces such as MWCNT-Al (5×10(-9)±1×10(-9)Km(2)W(-1)), Si3N4-Al (6×10(-8)±2.5×10(-8)Km(2)W(-1)) and Si3N4-graphene (~10(-8)Km(2)W(-1)). It was also demonstrated that the contact between the MWCNT probe and Al is relatively perfect, with a minimal contact resistance. In contrast, the thermal resistance between a standard Si3N4 SThM probe and Al is an order of magnitude higher than reported in the literature, suggesting that the contact between these materials may have a multi-asperity nature that can significantly degrade the contact resistance. PMID:26735005
Numerical modeling of thermal conductive heating in fractured bedrock.
Baston, Daniel P; Falta, Ronald W; Kueper, Bernard H
2010-01-01
Numerical modeling was employed to study the performance of thermal conductive heating (TCH) in fractured shale under a variety of hydrogeological conditions. Model results show that groundwater flow in fractures does not significantly affect the minimum treatment zone temperature, except near the beginning of heating or when groundwater influx is high. However, fracture and rock matrix properties can significantly influence the time necessary to remove all liquid water (i.e., reach superheated steam conditions) in the treatment area. Low matrix permeability, high matrix porosity, and wide fracture spacing can contribute to boiling point elevation in the rock matrix. Consequently, knowledge of these properties is important for the estimation of treatment times. Because of the variability in boiling point throughout a fractured rock treatment zone and the absence of a well-defined constant temperature boiling plateau in the rock matrix, it may be difficult to monitor the progress of thermal treatment using temperature measurements alone. PMID:20550586
Numerical Model for Conduction-Cooled Current Lead Heat Loads
White, M.J.; Wang, X.L.; Brueck, H.D.; /DESY
2011-06-10
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).
NASA Technical Reports Server (NTRS)
Anderson, W. T.; Edwards, D. K.; Eninger, J. E.; Marcus, B. D.
1974-01-01
A research and development program in variable conductance heat pipe technology is reported. The project involved: (1) theoretical and/or experimental studies in hydrostatics, (2) hydrodynamics, (3) heat transfer into and out of the pipe, (4) fluid selection, and (5) materials compatibility. The development, fabrication, and test of the space hardware resulted in a successful flight of the heat pipe experiment on the OAO-3 satellite. A summary of the program is provided and a guide to the location of publications on the project is included.
NASA Astrophysics Data System (ADS)
Yeh, Yuting
The lithium-ion battery has emerged as a common power source for portable consumer electronics since its debut two decades ago. Due to the low atomic weight and high electrochemical activity of lithium chemistry, lithium-ion battery has a higher energy density as compared to other battery systems, such as Ni-Cd, Ni-MH, and lead-acid batteries. As a result, use of lithium-ion batteries enables the size of batteries to be effectively reduced without compromising capacity. More importantly, as battery size is reduced, it enhances the applications of portable electronics, increasing the convenience of use. The 3-D battery architecture described in the dissertation is believed to be a new paradigm for future batteries. The architecture features coupled 3-D electrodes to provide better charge/discharge kinetics and a higher charge capacity per footprint area. The overarching objective of this dissertation is to implement the 3-D architecture using the lithium-ion chemistry. The 3-D lithium-ion batteries are designed to provide high areal energy density without compromising power density. The dissertation is comprised of four interrelated sections. First, a simulation was conducted to identify key battery parameters and to define an ideal three-dimensional cell structure. The second part of the research involved identifying fabrication routes to build the 3-D electrode, which was the key design element in the 3-D paradigm. The third part of the dissertation was to correlate the electrode performance with its geometric features. In particular, the influence of aspect ratio was investigated. Lastly, an electrolyte/separator was designed and fabricated based on the existing 3-D electrode configuration. This enabled 3-D battery to be assembled.
Pseudo-updated constrained solution algorithm for nonlinear heat conduction
NASA Technical Reports Server (NTRS)
Tovichakchaikul, S.; Padovan, J.
1983-01-01
This paper develops efficiency and stability improvements in the incremental successive substitution (ISS) procedure commonly used to generate the solution to nonlinear heat conduction problems. This is achieved by employing the pseudo-update scheme of Broyden, Fletcher, Goldfarb and Shanno in conjunction with the constrained version of the ISS. The resulting algorithm retains the formulational simplicity associated with ISS schemes while incorporating the enhanced convergence properties of slope driven procedures as well as the stability of constrained approaches. To illustrate the enhanced operating characteristics of the new scheme, the results of several benchmark comparisons are presented.
Combined conduction and radiation heat transfer in concentric cylindrical media
NASA Technical Reports Server (NTRS)
Pandey, D. K.
1987-01-01
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.
Hierarchical Parallelism in Finite Difference Analysis of Heat Conduction
NASA Technical Reports Server (NTRS)
Padovan, Joseph; Krishna, Lala; Gute, Douglas
1997-01-01
Based on the concept of hierarchical parallelism, this research effort resulted in highly efficient parallel solution strategies for very large scale heat conduction problems. Overall, the method of hierarchical parallelism involves the partitioning of thermal models into several substructured levels wherein an optimal balance into various associated bandwidths is achieved. The details are described in this report. Overall, the report is organized into two parts. Part 1 describes the parallel modelling methodology and associated multilevel direct, iterative and mixed solution schemes. Part 2 establishes both the formal and computational properties of the scheme.
Time fractional dual-phase-lag heat conduction equation
NASA Astrophysics Data System (ADS)
Xu, Huan-Ying; Jiang, Xiao-Yun
2015-03-01
We build a fractional dual-phase-lag model and the corresponding bioheat transfer equation, which we use to interpret the experiment results for processed meat that have been explained by applying the hyperbolic conduction. Analytical solutions expressed by H-functions are obtained by using the Laplace and Fourier transforms method. The inverse fractional dual-phase-lag heat conduction problem for the simultaneous estimation of two relaxation times and orders of fractionality is solved by applying the nonlinear least-square method. The estimated model parameters are given. Finally, the measured and the calculated temperatures versus time are compared and discussed. Some numerical examples are also given and discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11102102, 11472161, and 91130017), the Natural Science Foundation of Shandong Province, China (Grant No. ZR2014AQ015), and the Independent Innovation Foundation of Shandong University, China (Grant No. 2013ZRYQ002).
Heat conduction across monolayer and few-layer graphenes.
Koh, Yee Kan; Bae, Myung-Ho; Cahill, David G; Pop, Eric
2010-11-10
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
Homogeneous thermal cloak with constant conductivity and tunable heat localization.
Han, Tiancheng; Yuan, Tao; Li, Baowen; Qiu, Cheng-Wei
2013-01-01
Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and finite conductivity only employing naturally available materials. It is demonstrated that the thermal localization inside the coating layer can be tuned and controlled robustly by anisotropy, which enables an incomplete cloak to function perfectly. Practical realization of such homogeneous thermal cloak has been suggested by using two naturally occurring conductive materials, which provides an unprecedentedly plausible way to flexibly realize thermal cloak and manipulate heat flow with phonons. PMID:23549139
Homogeneous Thermal Cloak with Constant Conductivity and Tunable Heat Localization
Han, Tiancheng; Yuan, Tao; Li, Baowen; Qiu, Cheng-Wei
2013-01-01
Invisible cloak has long captivated the popular conjecture and attracted intensive research in various communities of wave dynamics, e.g., optics, electromagnetics, acoustics, etc. However, their inhomogeneous and extreme parameters imposed by transformation-optic method will usually require challenging realization with metamaterials, resulting in narrow bandwidth, loss, polarization-dependence, etc. In this paper, we demonstrate that thermodynamic cloak can be achieved with homogeneous and finite conductivity only employing naturally available materials. It is demonstrated that the thermal localization inside the coating layer can be tuned and controlled robustly by anisotropy, which enables an incomplete cloak to function perfectly. Practical realization of such homogeneous thermal cloak has been suggested by using two naturally occurring conductive materials, which provides an unprecedentedly plausible way to flexibly realize thermal cloak and manipulate heat flow with phonons. PMID:23549139
ERIC Educational Resources Information Center
Mayshark, Robin K.
1991-01-01
Students explore three-dimensional properties by creating red and green wall decorations related to Christmas. Students examine why images seem to vibrate when red and green pieces are small and close together. Instructions to conduct the activity and construct 3-D glasses are given. (MDH)
High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems
NASA Technical Reports Server (NTRS)
Tarau, Calin; Walker, Kara L.; Anderson, William G.
2009-01-01
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.
ERIC Educational Resources Information Center
Hastings, S. K.
2002-01-01
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)
Underground heat conduction near a spherical inhomogeneity: theory and applications
NASA Astrophysics Data System (ADS)
Rabinovich, A.; Dagan, G.; Miloh, T.
2012-04-01
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, for the first time, 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 found that an accurate solution can be achieved by a small number of terms. The results are illustrated and analyzed 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 ground surface temperature history reconstruction from borehole temperature profiles, all current methods assume one-dimensional heat conduction. We present calculations of the anomalies generated near inhomogeneities in the presence of a sudden change in surface temperature used to model climate change. 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. Reference: A. Rabinovich, G. Dagan and T. Miloh, "Heat conduction in a semi-infinite medium with a spherical inhomogeneity and time-periodic boundary temperature", International Journal of Heat and Mass Transfer, 55 (2012) 618-628.
Variable Conductance Heat Pipes for Radioisotope Stirling Systems
NASA Astrophysics Data System (ADS)
Anderson, William G.; Tarau, Calin
2008-01-01
In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) was designed to allow multiple stops and restarts of the Stirling engine. A VCHP was designed for the Advanced Stirling Radioisotope Generator, with a 850 °C heater head temperature. The VCHP turns on with a ΔT 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 ΔT was roughly 70 °C, due to distillation of the NaK in the evaporator.
Hardy, John G; Geissler, Sydney A; Aguilar, David; Villancio-Wolter, Maria K; Mouser, David J; Sukhavasi, Rushi C; Cornelison, R Chase; Tien, Lee W; Preda, R Carmen; Hayden, Rebecca S; Chow, Jacqueline K; Nguy, Lindsey; Kaplan, David L; Schmidt, Christine E
2015-11-01
Stimuli-responsive materials enabling the behavior of the cells that reside within them to be controlled are vital for the development of instructive tissue scaffolds for tissue engineering. Herein, we describe the preparation of conductive silk foam-based bone tissue scaffolds that enable the electrical stimulation of human mesenchymal stem cells (HMSCs) to enhance their differentiation toward osteogenic outcomes. PMID:26033953
NASA Astrophysics Data System (ADS)
Dimopoulos, Dimitrios; Pelekasis, Nikos A.
2014-10-01
Rayleigh-Bénard stability of a liquid metal layer of rectangular cross section is examined in the presence of a strong magnetic field that is aligned with the horizontal direction of the cross section. The latter is much longer than the vertical direction and the cross section assumes a large aspect ratio. The side walls are treated as highly conducting. Linear stability analysis is performed allowing for three-dimensional instabilities that develop along the longitudinal direction. The finite element methodology is employed for the discretization of the stability analysis formulation while accounting for the electrical conductivity of the cavity walls. The Arnoldi method provides the dominant eigenvalues and eigenvectors of the problem. In order to facilitate parallel implementation of the numerical solution at large Hartmann numbers, Ha, domain decomposition is employed along the horizontal direction of the cross section. As the Hartmann number increases a real eigenvalue emerges as the dominant unstable eigenmode, signifying the onset of thermal convection, whose major vorticity component in the core of the layer is aligned with the direction of the magnetic field. Its wavelength along the longitudinal direction of the layer is on the order of twice its height and increases as Ha increases. The critical Grashof was obtained for large Ha and it was seen to scale like Ha 2 signifying the balance between buoyancy and Lorentz forces. For well conducting side walls, the nature of the emerging flow pattern is determined by the combined conductivity of Hartmann walls and Hartmann layers, cH + Ha -1. When poor conducting Hartmann walls are considered, cH ≪ 1, the critical eigensolution is characterized by well defined Hartmann and side layers. The side layers are characterized by fast fluid motion in the magnetic field direction as a result of the electromagnetic pumping in the vicinity of the Hartmann walls. Increasing the electrical conductivity of the Hartmann walls was seen to delay the onset of thermal convection, while retaining the above scaling at criticality. Furthermore, for both conducting and insulating Hartmann walls and the entire range of Ha numbers that was examined, there was no tendency for a well defined quasi two-dimensional structure to develop owing to the convective motion in the core. A connection is made between the above findings and previous experimental investigations indicating the onset of standing waves followed by travelling waves as Gr is further increased beyond its critical value.
Thermal conductivity and specific heat of glass ceramics
NASA Astrophysics Data System (ADS)
Cahill, D. G.; Olson, J. R.; Fischer, Henry E.; Watson, S. K.; Stephens, R. B.; Tait, R. H.; Ashworth, T.; Pohl, R. O.
1991-12-01
The effect of crystallization on the lattice vibrations of two glass ceramics, a magnesium aluminosilicate (Corning Code 9606) and a lithium aluminosilicate (Corning Code 9623), is studied through measurements of the thermal conductivity and specific heat below 300 K. Because of grain boundaries and magnetic impurities, measurements below a few kelvins are of limited value. At higher temperatures, however, the experimental results show that the lattice vibrations of one of the glass ceramics (Code 9606) change from glassy to crystalline upon crystallization. Those of Code 9623, however, remain glassy even in the fully crystallized state. In contrast to the crystalline Code 9606 sample, the Code 9623 sample accommodates large concentrations of interstitial lithium and magnesium ions in its crystal lattice, and it is suggested that the glasslike lattice vibrations in the Code 9623 sample are caused by these ions.
Current fluctuations in a two dimensional model of heat conduction
NASA Astrophysics Data System (ADS)
Pérez-Espigares, Carlos; Garrido, Pedro L.; Hurtado, Pablo I.
2011-03-01
In this work we study numerically and analytically current fluctuations in the two-dimensional Kipnis-Marchioro-Presutti (KMP) model of heat conduction. For that purpose, we use a recently introduced algorithm which allows the direct evaluation of large deviations functions. We compare our results with predictions based on the Hydrodynamic Fluctuation Theory (HFT) of Bertini and coworkers, finding very good agreement in a wide interval of current fluctuations. We also verify the existence of a well-defined temperature profile associated to a given current fluctuation which depends exclusively on the magnitude of the current vector, not on its orientation. This confirms the recently introduced Isometric Fluctuation Relation (IFR), which results from the time-reversibility of the dynamics, and includes as a particular instance the Gallavotti-Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by timereversibility on the statistics of nonequilibrium fluctuations.
Development of variable conductance heat pipe at ISAC
NASA Astrophysics Data System (ADS)
Kumar, D.; Gupta, P. P.; Murthy, H. N.
A detailed study has been carried out on the performance of gas loaded nonwicked hot reservoir variable conductance heat pipes employing S.S.-Acetone-Nitrogen as envelope material, working fluid, and noncondensible gas (NCG) respectively. Effect of NCG reservoir to condenser volume ratio and NCG charge quantity on the temperature controllability and sensitivity to operating temperature level is investigated. Results indicate that the temperature controllability in the investigated range varies from about 0.56 C/W to 0.15 C/Watt depending upon NCG reservoir to condenser volume ratio and the NCG charge. It is shown that with the marginal increase in operating temperature level the temperature controllability can be improved with increase in gas charge.
Heat conductivity of copper in two-temperature state
NASA Astrophysics Data System (ADS)
Migdal, K. P.; Petrov, Yu. V.; Il`nitsky, D. K.; Zhakhovsky, V. V.; Inogamov, N. A.; Khishchenko, K. V.; Knyazev, D. V.; Levashov, P. R.
2016-04-01
Electron-ion relaxation lasts few tens of picoseconds in a submicrometer surface layer of metal after irradiation by femtosecond laser pulse of moderate intensity. During this stage, the electron temperature is many times higher than ion (lattice) temperature. The rate of this relaxation is slower for noble metals due to their small electron-ion coupling. Thus, effects caused by high electron temperature reveal more obviously for those metals. To study electron transport in noble metal nanofilms, we combine the first-principle calculations and our analytical models. The newly calculated electron-phonon coupling and heat conductivity are used in two-temperature hydrodynamics modeling. Results of such modeling are in good agreement with the experimental data and molecular dynamics simulation.
Application of the boundary element method to transient heat conduction
NASA Technical Reports Server (NTRS)
Dargush, G. F.; Banerjee, P. K.
1991-01-01
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.
High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems
NASA Astrophysics Data System (ADS)
Tarau, Calin; Walker, Kara L.; Anderson, William G.
2009-03-01
In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling converter provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling engine. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140° C while the heat losses caused by the addition of the VCHP are 1.8 W.
High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems
Tarau, Calin; Walker, Kara L.; Anderson, William G.
2009-03-16
In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling converter provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling engine. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140 deg. C while the heat losses caused by the addition of the VCHP are 1.8 W.
Heat conduction in nanoscale materials: a statistical-mechanics derivation of the local heat flux.
Li, Xiantao
2014-09-01
We derive a coarse-grained model for heat conduction in nanoscale mechanical systems. Starting with an all-atom description, this approach yields a reduced model, in the form of conservation laws of momentum and energy. The model closure is accomplished by introducing a quasilocal thermodynamic equilibrium, followed by a linear response approximation. Of particular interest is the constitutive relation for the heat flux, which is expressed nonlocally in terms of the spatial and temporal variation of the temperature. Nanowires made of copper and silicon are presented as examples. PMID:25314400
Manipulating Steady Heat Conduction by Sensu-shaped Thermal Metamaterials.
Han, Tiancheng; Bai, Xue; Liu, Dan; Gao, Dongliang; Li, Baowen; Thong, John T L; Qiu, Cheng-Wei
2015-01-01
The ability to design the control of heat flow has innumerable benefits in the design of electronic systems such as thermoelectric energy harvesters, solid-state lighting, and thermal imagers, where the thermal design plays a key role in performance and device reliability. In this work, we employ one identical sensu-unit with facile natural composition to experimentally realize a new class of thermal metamaterials for controlling thermal conduction (e.g., thermal concentrator, focusing/resolving, uniform heating), only resorting to positioning and locating the same unit element of sensu-shape structure. The thermal metamaterial unit and the proper arrangement of multiple identical units are capable of transferring, redistributing and managing thermal energy in a versatile fashion. It is also shown that our sensu-shape unit elements can be used in manipulating dc currents without any change in the layout for the thermal counterpart. These could markedly enhance the capabilities in thermal sensing, thermal imaging, thermal-energy storage, thermal packaging, thermal therapy, and more domains beyond. PMID:25974383
Manipulating Steady Heat Conduction by Sensu-shaped Thermal Metamaterials
Han, Tiancheng; Bai, Xue; Liu, Dan; Gao, Dongliang; Li, Baowen; Thong, John T. L.; Qiu, Cheng-Wei
2015-01-01
The ability to design the control of heat flow has innumerable benefits in the design of electronic systems such as thermoelectric energy harvesters, solid-state lighting, and thermal imagers, where the thermal design plays a key role in performance and device reliability. In this work, we employ one identical sensu-unit with facile natural composition to experimentally realize a new class of thermal metamaterials for controlling thermal conduction (e.g., thermal concentrator, focusing/resolving, uniform heating), only resorting to positioning and locating the same unit element of sensu-shape structure. The thermal metamaterial unit and the proper arrangement of multiple identical units are capable of transferring, redistributing and managing thermal energy in a versatile fashion. It is also shown that our sensu-shape unit elements can be used in manipulating dc currents without any change in the layout for the thermal counterpart. These could markedly enhance the capabilities in thermal sensing, thermal imaging, thermal-energy storage, thermal packaging, thermal therapy, and more domains beyond. PMID:25974383
Manipulating Steady Heat Conduction by Sensu-shaped Thermal Metamaterials
NASA Astrophysics Data System (ADS)
Han, Tiancheng; Bai, Xue; Liu, Dan; Gao, Dongliang; Li, Baowen; Thong, John T. L.; Qiu, Cheng-Wei
2015-05-01
The ability to design the control of heat flow has innumerable benefits in the design of electronic systems such as thermoelectric energy harvesters, solid-state lighting, and thermal imagers, where the thermal design plays a key role in performance and device reliability. In this work, we employ one identical sensu-unit with facile natural composition to experimentally realize a new class of thermal metamaterials for controlling thermal conduction (e.g., thermal concentrator, focusing/resolving, uniform heating), only resorting to positioning and locating the same unit element of sensu-shape structure. The thermal metamaterial unit and the proper arrangement of multiple identical units are capable of transferring, redistributing and managing thermal energy in a versatile fashion. It is also shown that our sensu-shape unit elements can be used in manipulating dc currents without any change in the layout for the thermal counterpart. These could markedly enhance the capabilities in thermal sensing, thermal imaging, thermal-energy storage, thermal packaging, thermal therapy, and more domains beyond.
NASA Astrophysics Data System (ADS)
Li, Chongxiang; Asundi, Anand K.; Fang, Zhong P.
2001-10-01
With the increasing demand for micro-products and bioengineering research, resolutions of profiles with micrometer or even nanometer scale are becoming commonplace. In addition development of large integrated manufacturing systems and the real time life science growth and adaptation need high-speed display and real-time inspection. Single point measurement is time consuming method with large area profile and micrometer resolution. Thus there is a need for a fast 3-D measurement system with high resolution. This paper presents a short overview among optical 3-D shape measurement techniques, and concentrates on the confocal method. Based on the properties analysis, a novel multi-channel 3-D topography measurement system was proposed. The feasibility and the construction of system were described A unique new structure of fiber coupled confocal system is put forth to solve present problems confronted in confocal system. This system can meet the current demand of high resolution and fast 3-D measurement.
Crandall, K.R.
1987-08-01
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.
NASA Astrophysics Data System (ADS)
Liu, D.; Medley, S. S.; Gorelenkova, M. V.; Heidbrink, W. W.; Stagner, L.
2014-10-01
A cloud of halo neutrals is created in the vicinity of beam footprint during the neutral beam injection and the halo neutral density can be comparable with beam neutral density. Proper modeling of halo neutrals is critical to correctly interpret neutral particle analyzers (NPA) and fast ion D-alpha (FIDA) signals since these signals strongly depend on local beam and halo neutral density. A 3D halo neutral model has been recently developed and implemented inside TRANSP code. The 3D halo neutral code uses a ``beam-in-a-box'' model that encompasses both injected beam neutrals and resulting halo neutrals. Upon deposition by charge exchange, a subset of the full, one-half and one-third beam energy components produce thermal halo neutrals that are tracked through successive halo neutral generations until an ionization event occurs or a descendant halo exits the box. A benchmark between 3D halo neural model in TRANSP and in FIDA/NPA synthetic diagnostic code FIDASIM is carried out. Detailed comparison of halo neutral density profiles from two codes will be shown. The NPA and FIDA simulations with and without 3D halos are applied to projections of plasma performance for the National Spherical Tours eXperiment-Upgrade (NSTX-U) and the effects of halo neutral density on NPA and FIDA signal amplitude and profile will be presented. Work supported by US DOE.
Mohan, R.S.; Kovacevic, R.; Beardsley, H.E.
1996-12-31
In abrasive waterjet (AWJ) cutting, the cutting tool is a thin stream of high velocity abrasive waterjet slurry which can be considered as a moving line heat source that increases the temperature of the narrow zone along the cut kerf wall. A suitably defined inverse heat conduction problem which uses the experimentally determined temperature histories at various points in the workpiece, is adopted to determine the heat flux at the cutting zone. Temperature distribution in the workpiece and the cutting nozzle during AWJ cutting is monitored using infrared thermography. A suitable strategy for on-line monitoring of the radial and axial wear of the AWJ nozzle based on the nozzle temperature distribution is also proposed.
Tzanos, C. P.; Dionne, B.
2011-05-23
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.
NASA Astrophysics Data System (ADS)
Maksimov, Vyacheslav I.; Nagornova, Tatiana A.; Glazyrin, Viktor P.
2016-02-01
Is solved the problem of heat transfer in the closed volume, limited by heat-conducting walls, with the local source of heat emission and the heterogeneous conditions of heat sink on the outer boundaries of solution area. The problem of convective heat transfer is solved with using a system of differential Navier-Stokes equations in the Boussinesq approximation. The simulation of turbulent flow conditions of heated air is carried out within the framework to k-ɛ model. On the basis the analysis of the obtained temperature field and the contour lines of stream functions is made conclusion about the essential transiency of the process in question. The obtained values of temperatures and speeds in different sections of region illustrate turbulence of the process. Are investigated laws governing the formation of temperature fields in closed areas with a local heat emission source under the conditions of intensive local heat sink into environment and accumulation of heat in the enclosing constructions.
Federal Register 2010, 2011, 2012, 2013, 2014
2012-07-05
... COMMISSION Certain Integrated Circuit Packages Provided With Multiple Heat- Conducting Paths and Products... with multiple heat-conducting paths and products containing same by reason of infringement of certain... integrated circuit packages provided with multiple heat-conducting paths and products containing same...
Federal Register 2010, 2011, 2012, 2013, 2014
2012-06-06
... COMMISSION Certain Integrated Circuit Packages Provided With Multiple Heat- Conducting Paths and Products... With Multiple Heat-Conducting Paths and Products Containing Same, DN 2899; the Commission is soliciting... multiple heat-conducting paths and products containing same. The complaint names as respondents...
BEAMS3D Neutral Beam Injection Model
Lazerson, Samuel
2014-04-14
With the advent of applied 3D fi elds in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous velocity reduction, and pitch angle scattering are modeled with the ADAS atomic physics database [1]. Benchmark calculations are presented to validate the collisionless particle orbits, neutral beam injection model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields.
NASA Astrophysics Data System (ADS)
Nguyen, Duy-Cuong; Tanaka, Souichirou; Nishino, Hitoshi; Manabe, Kyohei; Ito, Seigo
2013-01-01
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%.
NASA Astrophysics Data System (ADS)
Oldham, Mark
2015-01-01
Radiochromic materials exhibit a colour change when exposed to ionising radiation. Radiochromic film has been used for clinical dosimetry for many years and increasingly so recently, as films of higher sensitivities have become available. The two principle advantages of radiochromic dosimetry include greater tissue equivalence (radiologically) and the lack of requirement for development of the colour change. In a radiochromic material, the colour change arises direct from ionising interactions affecting dye molecules, without requiring any latent chemical, optical or thermal development, with important implications for increased accuracy and convenience. It is only relatively recently however, that 3D radiochromic dosimetry has become possible. In this article we review recent developments and the current state-of-the-art of 3D radiochromic dosimetry, and the potential for a more comprehensive solution for the verification of complex radiation therapy treatments, and 3D dose measurement in general.
NASA Astrophysics Data System (ADS)
Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David; Yacoby, Ran
2016-03-01
We study the conformal bootstrap for a 4-point function of fermions < ψψψψ> in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge C T . We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N . We also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.
SEP BIMOD variable conductance heat pipes acceptance and characterization tests
NASA Technical Reports Server (NTRS)
Hemminger, J. A.
1981-01-01
A series of six heat pipes, similar in design to those flown on the Comunications Technology Satellite Hermes, for use in a prototype Solar Electric Propulsion BIMOD thrust module are evaluated. The results of acceptance and characterization tests performed on the heat pipe subassemble are reported. The performance of all the heat pipes met, or exceeded, design specifications.
Regional geothermal 3D modelling in Denmark
NASA Astrophysics Data System (ADS)
Poulsen, S. E.; Balling, N.; Bording, T. S.; Nielsen, S. B.
2012-04-01
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.
NASA Astrophysics Data System (ADS)
Carson, Jeffrey J. L.; Roumeliotis, Michael; Chaudhary, Govind; Stodilka, Robert Z.; Anastasio, Mark A.
2010-06-01
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 of our 3D photoacoustic imaging approach is its inability ability to reconstruct complex objects in the field of view. This is primarily due to the relatively small number of projections used to reconstruct objects. However, in many photoacoustic imaging situations, only a few objects may be present in the field of view and these objects may have very high contrast compared to background. That is, the objects have sparse properties. Therefore, our work had two objectives: (i) to utilize mathematical tools to evaluate 3D photoacoustic imaging performance, and (ii) to test image reconstruction algorithms that prefer sparseness in the reconstructed images. Our approach was to utilize singular value decomposition techniques to study the imaging operator of the system and evaluate the complexity of objects that could potentially be reconstructed. We also compared the performance of two image reconstruction algorithms (algebraic reconstruction and l1-norm techniques) at reconstructing objects of increasing sparseness. We observed that for a 15-element detection scheme, the number of measureable singular vectors representative of the imaging operator was consistent with the demonstrated ability to reconstruct point and line targets in the field of view. We also observed that the l1-norm reconstruction technique, which is known to prefer sparseness in reconstructed images, was superior to the algebraic reconstruction technique. Based on these findings, we concluded (i) that singular value decomposition of the imaging operator provides valuable insight into the capabilities of a 3D photoacoustic imaging system, and (ii) that reconstruction algorithms which favor sparseness can significantly improve imaging performance. These methodologies should provide a means to optimize detector count and geometry for a multitude of 3D photoacoustic imaging applications.
Theory and design of variable conductance heat pipes: Steady state and transient performance
NASA Technical Reports Server (NTRS)
Edwards, D. K.; Fleischman, G. L.; Marcus, B. D.
1972-01-01
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.
NASA Astrophysics Data System (ADS)
Ndlovu, Partner; Moitsheki, Rasselo
2013-08-01
Some new conservation laws for the transient heat conduction problem for heat transfer in a straight fin are constructed. The thermal conductivity is given by a power law in one case and by a linear function of temperature in the other. Conservation laws are derived using the direct method when thermal conductivity is given by the power law and the multiplier method when thermal conductivity is given as a linear function of temperature. The heat transfer coefficient is assumed to be given by the power law function of temperature. Furthermore, we determine the Lie point symmetries associated with the conserved vectors for the model with power law thermal conductivity.
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
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
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
NASA Astrophysics Data System (ADS)
Ping, Y.; Fernandez-Panella, A.; Sio, H.; Correa, A.; Shepherd, R.; Landen, O.; London, R. A.; Sterne, P. A.; Whitley, H. D.; Fratanduono, D.; Boehly, T. R.; Collins, G. W.
2015-09-01
We propose a method for thermal conductivity measurements of high energy density matter based on differential heating. A temperature gradient is created either by surface heating of one material or at an interface between two materials by different energy deposition. The subsequent heat conduction across the temperature gradient is observed by various time-resolved probing techniques. Conceptual designs of such measurements using laser heating, proton heating, and x-ray heating are presented. The sensitivity of the measurements to thermal conductivity is confirmed by simulations.
Ping, Y.; Fernandez-Panella, A.; Sio, H.; Correa, A.; Shepherd, R.; Landen, O.; London, R. A.; Sterne, P. A.; Whitley, H. D.; Fratanduono, D.; et al
2015-09-04
We propose a method for thermal conductivity measurements of high energy density matter based on differential heating. A temperature gradient is created either by surface heating of one material or at an interface between two materials by different energy deposition. The subsequent heat conduction across the temperature gradient is observed by various time-resolved probing techniques. Conceptual designs of such measurements using laser heating, proton heating, and x-ray heating are presented. As a result, the sensitivity of the measurements to thermal conductivity is confirmed by simulations.
Heat Conduction with Flux Condition on a Free Patch
Kuttler, Kenneth L. Shillor, Meir
2004-08-15
A new free boundary or free patch problem for the heat equation is presented. In the problem a nonlinear heat flux condition is prescribed on a free portion of the boundary, the patch, the position of which depends on the solution. The existence of a weak solution is established using the theory of set-valued pseudo monotone operators.
NASA Astrophysics Data System (ADS)
Connors, M. G.; Schofield, I. S.
2012-12-01
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.
3D Ion Temperature Reconstruction
NASA Astrophysics Data System (ADS)
Tanabe, Hiroshi; You, Setthivoine; Balandin, Alexander; Inomoto, Michiaki; Ono, Yasushi
2009-11-01
The TS-4 experiment at the University of Tokyo collides two spheromaks to form a single high-beta compact toroid. Magnetic reconnection during the merging process heats and accelerates the plasma in toroidal and poloidal directions. The reconnection region has a complex 3D topology determined by the pitch of the spheromak magnetic fields at the merging plane. A pair of multichord passive spectroscopic diagnostics have been established to measure the ion temperature and velocity in the reconnection volume. One setup measures spectral lines across a poloidal plane, retrieving velocity and temperature from Abel inversion. The other, novel setup records spectral lines across another section of the plasma and reconstructs velocity and temperature from 3D vector and 2D scalar tomography techniques. The magnetic field linking both measurement planes is determined from in situ magnetic probe arrays. The ion temperature is then estimated within the volume between the two measurement planes and at the reconnection region. The measurement is followed over several repeatable discharges to follow the heating and acceleration process during the merging reconnection.
Chen, Lin; Li, Zhen; Guo, Zeng-Yuan
2009-07-15
In this paper, two modified types of polypropylene (PP) with high thermal conductivity up to 2.3 W/m K and 16.5 W/m K are used to manufacture the finned-tube heat exchangers, which are prospected to be used in liquid desiccant air conditioning, heat recovery, water source heat pump, sea water desalination, etc. A third plastic heat exchanger is also manufactured with ordinary PP for validation and comparison. Experiments are carried out to determine the thermal performance of the plastic heat exchangers. It is found that the plastic finned-tube heat exchanger with thermal conductivity of 16.5 W/m K can achieve overall heat transfer coefficient of 34 W/m{sup 2} K. The experimental results are compared with calculation and they agree well with each other. Finally, the effect of material thermal conductivity on heat exchanger thermal performance is studied in detail. The results show that there is a threshold value of material thermal conductivity. Below this value improving thermal conductivity can considerably improve the heat exchanger performance while over this value improving thermal conductivity contributes very little to performance enhancement. For the finned-tube heat exchanger designed in this paper, when the plastic thermal conductivity can reach over 15 W/m K, it can achieve more than 95% of the titanium heat exchanger performance and 84% of the aluminum or copper heat exchanger performance with the same dimension. (author)
NASA Astrophysics Data System (ADS)
Kuznetzov, G. V.; Polovnikov, V. Yu.
2012-04-01
The results of numerical investigation are reported on thermal regimes in the systems of heat transport based on the solution of the conjugative problem of conductive-convective heat transfer in the system twin-tube-channel underground heat pipeline environmental medium. It is shown that the use of the proposed approach allows one to perform the comprehensive analysis of the heating regimes in such systems.
NASA Astrophysics Data System (ADS)
Polovnikov, V. Yu.; Razumov, N. V.
2016-02-01
This paper describes the numerical modeling of a convective-conductive heat transfer the area placing of a heat pipeline under flooding conditions. We have established that the heat loss of a heat pipeline under flooding conditions increases in the range from 1.5 to 64.3%, depending on the volume fraction of water in the insulation structure.
In vitro burn model illustrating heat conduction patterns using compressed thermal papers.
Lee, Jun Yong; Jung, Sung-No; Kwon, Ho
2015-01-01
To date, heat conduction from heat sources to tissue has been estimated by complex mathematical modeling. In the present study, we developed an intuitive in vitro skin burn model that illustrates heat conduction patterns inside the skin. This was composed of tightly compressed thermal papers with compression frames. Heat flow through the model left a trace by changing the color of thermal papers. These were digitized and three-dimensionally reconstituted to reproduce the heat conduction patterns in the skin. For standardization, we validated K91HG-CE thermal paper using a printout test and bivariate correlation analysis. We measured the papers' physical properties and calculated the estimated depth of heat conduction using Fourier's equation. Through contact burns of 5, 10, 15, 20, and 30 seconds on porcine skin and our burn model using a heated brass comb, and comparing the burn wound and heat conduction trace, we validated our model. The heat conduction pattern correlation analysis (intraclass correlation coefficient: 0.846, p?heat conduction depth correlation analysis (intraclass correlation coefficient: 0.93, p?heat conduction patterns. PMID:25421614
Linear Electrical Conductivity of a Bipolar Semiconductor: Heating and Recombination
NASA Astrophysics Data System (ADS)
Lashkevych, Igor; Gurevich, Yuri G.
2016-01-01
The linear electrical conductivity of a nondegenerate bipolar semiconductor, with metal contacts at both sides, is investigated for small values of the thermal conductivity in a general case, i.e., when both nonequilibrium charge carriers (electrons and holes) and nonequilibrium temperature are present. It must be emphasized that both concentration and energy nonequilibria arise automatically when an electric current flows, even in a linear approximation with respect to perturbation. The expression for the electrical conductivity is obtained. This expression depends on electrical conductivities of electrons and holes, the thermal conductivity, the bandgap, the lifetime of charge carriers, and the surface recombination rate at the contacts of a semiconductor with a metal.
NASA Technical Reports Server (NTRS)
1992-01-01
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.
NASA Technical Reports Server (NTRS)
1997-01-01
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
Ultrafine particle emissions from desktop 3D printers
NASA Astrophysics Data System (ADS)
Stephens, Brent; Azimi, Parham; El Orch, Zeineb; Ramos, Tiffanie
2013-11-01
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.
NASA Technical Reports Server (NTRS)
1997-01-01
An area of rocky terrain near the landing site of the Sagan Memorial Station can be seen in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. This image is part of a 3D 'monster' panorama of the area surrounding the landing site.
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
Lie Symmetry Analysis of AN Unsteady Heat Conduction Problem
NASA Astrophysics Data System (ADS)
di Stefano, O.; Sammarco, S.; Spinelli, C.
2010-04-01
We consider an unsteady thermal storage problem in a body whose surface is subjected to heat transfer by convection to an external environment (with a time varying heat transfer coefficient) within the context of Lie group analysis. We determine an optimal system of two-dimensional Abelian Lie subalgebras of the admitted Lie algebra of point symmetries, and show an example of reduction to autonomous form. Also, by adding a small term to the equation, rendering it hyperbolic, we determine the first order approximate Lie symmetries, and solve a boundary value problem. The solution is compared with that of the parabolic equation.
A two-fluid model for relativistic heat conduction
López-Monsalvo, César S.
2014-01-14
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.
The program FANS-3D (finite analytic numerical simulation 3-dimensional) and its applications
NASA Technical Reports Server (NTRS)
Bravo, Ramiro H.; Chen, Ching-Jen
1992-01-01
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.
Variable Conductance Heat Pipe Cooling of Stirling Convertor and General Purpose Heat Source
NASA Technical Reports Server (NTRS)
Tarau, Calin; Schwendeman, Carl; Anderson, William G.; Cornell, Peggy A.; Schifer, Nicholas A.
2013-01-01
In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental results from integrating the VCHP with an operating Stirling convertor and describes the methodology used to achieve their successful combined operation.
NASA Astrophysics Data System (ADS)
Shrestha, R.; Lee, K. M.; Chang, W. S.; Kim, D. S.; Rhee, G. H.; Choi, T. Y.
2013-03-01
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 μm to 5 μm 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.
NASA Astrophysics Data System (ADS)
Tsuzuki, Yutaka
2015-09-01
This paper is concerned with a system of heat equations with hysteresis and Navier-Stokes equations. In Tsuzuki (J Math Anal Appl 423:877-897, 2015) an existence result is obtained for the problem in a 2-dimensional domain with the Navier-Stokes equation in a weak sense. However the result does not include uniqueness for the problem due to the low regularity for solutions. This paper establishes existence and uniqueness in 2- and 3-dimensional domains with the Navier-Stokes equation in a stronger sense. Moreover this work decides required height of regularity for the initial data by introducing the fractional power of the Stokes operator.
Heat Mirrors On Plastic Sheet Using Transparent Oxide Conducting Coatings
NASA Astrophysics Data System (ADS)
Howson, Ronald P.; Ridge, Martin I.
1982-04-01
A technique of reactive d.c. magnetron sputtering with r.f. substrate bias has been evolved to give metal oxide films which exhibit heat reflecting properties while remaining highly transparent. Films of indiumtin, indium and cadmiumtin oxide have been deposited onto plastic sheet at room temperature at rates of greater than 0.5μm min.-1 Preliminary assessments of durability with accelerated weathering with exposure to high U. V. levels and high humidities have Given very encouraging results. The properties achieved with a sinale coating of about 300 nm of oxide to a 50μm thick P.E.T. sheet are visible transmittances of over 70% with heat emissivities lower than 0.3. These properties are commensurate with them providina an energy and cost effective addition to new and existing windows.
Heat mirrors on plastic sheet using transparent oxide conducting coatings
NASA Astrophysics Data System (ADS)
Howson, R. P.; Ridge, M. I.
1982-07-01
A technique of reactive d.c. magnetron sputtering with RF substrate bias was evolved to give metal oxide films which exhibit heat reflecting properties while remaining highly transparent. Films or indium-tin, indium and cadmium-tin oxide were were deposited onto plastic sheet at room temperature at rates of greater than 0.5 microns min. Preliminary assessments of durability with accelerated weathering with exposure to high U.V. levels and high humidities gave very encouraging results. The properties achieved with a single coating of about 300 nm of oxide to a 50 microns thick P.E.T. sheet are visible transmittances of over 70% with heat emissivities lower than 0.3. These properties are commensurate with them providing an energy and cost effective addition to new and existing windows.
NASA Astrophysics Data System (ADS)
Zou, Ling
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.
NASA Astrophysics Data System (ADS)
Fathi Azarkhavarani, M. E.; Hosseini Abardeh, R.; Rahmani, M.
2015-12-01
In this study a new approach for radiation heat flux calculations by coupling the discrete ordinates method with the Leckner global model is introduced. The aim is to analyze the radiative heat transfer problem within a three-dimensional enclosure filled with non-gray gas mixture of H2O and CO2 . A computer code developed by this approach is applied to radiative calculations in three groups of well-known test cases published previously; considering homogeneous and inhomogeneous isothermal and non-isothermal participating media. All results are compared with well-known calculations based on statistical narrow band model. Also a new series of predictions for a medium with non-black walls and various mixture of H2O and CO2 is performed to demonstrate the applicability of the Leckner model. The effect of different compositions of H2O and CO2 on the radiative transfer within modern combustors is also examined. Based on the results obtained, it is believed that the discrete ordinates method coupled with the Leckner global model despite of its inherent simplicity and low computational cost is sufficiently accurate. For its convenient use, this method is suitable for a wide range of engineering calculations of participating media as well as for its link to previously written computational fluid dynamics codes.
A Simple Rate Law Experiment Using a Custom-Built Isothermal Heat Conduction Calorimeter
ERIC Educational Resources Information Center
Wadso, Lars; Li, Xi.
2008-01-01
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
Fibre orientation and the conduction of heat by a gas enclosed in ceramic layers
NASA Astrophysics Data System (ADS)
Keller, K.; Blumenberg, J.; Tomsik, J.
1988-08-01
Fibrous layers are an essential constituent of future heat protection systems. The conduction of heat by a gas enclosed in fibrous layers depends on layer and fiber density, mean fiber diameter and fiber orientation. Consideration of fiber orientation improves the correlation between model predictions and experimental results. It also permits a better explanation of the pressure dependence of convective heat transport.
A Simple Rate Law Experiment Using a Custom-Built Isothermal Heat Conduction Calorimeter
ERIC Educational Resources Information Center
Wadso, Lars; Li, Xi.
2008-01-01
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…
Numerical model for combined conductive and radiative heat transfer in annular packed beds
Kamiuto, K.; Saito, S.; Ito, K. . Dept. of Production Systems Engineering)
1993-06-01
A numerical model is developed for quantitatively analyzing combined conductive and radiative heat transfer in concentric annular packed beds. A packed bed is considered to be a continuous medium for heat transfer, but the porosity distribution within a packed bed is taken into account. To examine the validity of the proposed model, combined conductive and radiative heat transfer through annular packed beds of cordierite or porcelain beads is analyzed numerically using finite differences under conditions corresponding to heat transfer experiments of these packed beds. The resultant temperature profiles and heat transfer characteristics are compared with the experimental results.
Heat conduction in cooling flows. [in clusters of galaxies
NASA Technical Reports Server (NTRS)
Bregman, Joel N.; David, L. P.
1988-01-01
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.
Federal Register 2010, 2011, 2012, 2013, 2014
2012-12-12
..., California (collectively, ``ITRI''). 77 FR 39735 (Jul. 5, 2012). The complaint, as amended, alleges... COMMISSION Certain Integrated Circuit Packages Provided with Multiple Heat- Conducting Paths and Products... integrated circuit packages provided with multiple heat-conducting paths and products containing same...
Calculation of heat conductivity of organic liquids as function of temperature
Safarov, M.M.; Khadzhidov, Kh.
1995-12-01
Results of generalization of experimental data on heat conductivity of a series of organic liquids as a function of temperature at atmospheric pressure are presented. The approximation dependence for calculation of heat conductivity of liquid organic compounds as a function of temperature, normal boiling temperature, and molar mass is obtained.
Simulating coronal condensation dynamics in 3D
NASA Astrophysics Data System (ADS)
Moschou, S. P.; Keppens, R.; Xia, C.; Fang, X.
2015-12-01
We present numerical simulations in 3D settings where coronal rain phenomena take place in a magnetic configuration of a quadrupolar arcade system. Our simulation is a magnetohydrodynamic simulation including anisotropic thermal conduction, optically thin radiative losses, and parametrised heating as main thermodynamical features to construct a realistic arcade configuration from chromospheric to coronal heights. The plasma evaporation from chromospheric and transition region heights eventually causes localised runaway condensation events and we witness the formation of plasma blobs due to thermal instability, that evolve dynamically in the heated arcade part and move gradually downwards due to interchange type dynamics. Unlike earlier 2.5D simulations, in this case there is no large scale prominence formation observed, but a continuous coronal rain develops which shows clear indications of Rayleigh-Taylor or interchange instability, that causes the denser plasma located above the transition region to fall down, as the system moves towards a more stable state. Linear stability analysis is used in the non-linear regime for gaining insight and giving a prediction of the system's evolution. After the plasma blobs descend through interchange, they follow the magnetic field topology more closely in the lower coronal regions, where they are guided by the magnetic dips.
Cu/Diamond composite heat-conducting shims
NASA Astrophysics Data System (ADS)
Galashov, E. N.; Yusuf, A. A.; Mandrik, E. M.
2015-11-01
Composite material with high thermal conductivity was obtained by the method of thermal sintering of a diamond (50 - 75%) with a size of 20 to 250 μm in a matrix of copper.Coefficient of thermal conductivity of copper diamond composite materials was measured and is 450 - 650 W·m-1·K-1. The coefficient of thermal expansion CTE was measured and is 5.5 - 7.5 · 10-6/°C. The obtained copper diamond composite materials are promising objects for use in THz and microwave devices.
2015-04-23
A new type of graphene aerogel will make for better energy storage, sensors, nanoelectronics, catalysis and separations. Lawrence Livermore National Laboratory researchers have made graphene aerogel microlattices with an engineered architecture via a 3D printing technique known as direct ink writing. The research appears in the April 22 edition of the journal, Nature Communications. The 3D printed graphene aerogels have high surface area, excellent electrical conductivity, are lightweight, have mechanical stiffness and exhibit supercompressibility (up to 90 percent compressive strain). In addition, the 3D printed graphene aerogel microlattices show an order of magnitude improvement over bulk graphene materials and much better mass transport.
NASA Astrophysics Data System (ADS)
Kurovics, E.; Buzimov, A. Y.; Gömze, L. A.
2016-04-01
In this work some new raw material compositions from alumina, conventional brick-clays and sawdust were mixed, compacted and heat treated by the authors. Depending on raw material compositions and firing temperatures the specimens were examined on shrinkage, water absorption, heat conductivity and microstructures. The real raised experiments have shown the important role of firing temperature and raw material composition on color, heat conductivity and microstructure of the final product.
NASA Astrophysics Data System (ADS)
Yu, Y. Jun; Li, Chen-Lin; Xue, Zhang-Na; Tian, Xiao-Geng
2016-01-01
To model transiently thermal responses of numerous thermal shock issues at nano-scale, Fourier heat conduction law is commonly extended by introducing time rate of heat flux, and comes to hyperbolic heat conduction (HHC). However, solution to HHC under Dirichlet boundary condition depicts abnormal phenomena, e.g. heat conducts from the cold to the hot, and there are two temperatures at one location. In this paper, HHC model is further perfected with the aids of spatially nonlocal effect, and the exceeding temperature as well as the discontinuity at the wave front are avoided. The effect of nonlocal parameter on temperature response is discussed. From the analysis, the importance of size effect for nano-scale heat conduction is emphasized, indicating that spatial and temporal extensions should be simultaneously made to nano-scale heat conduction. Beyond that, it is found that heat flux boundary conditions should be directly given, instead of Neumann boundary condition, which does not make sense any longer for non-classical heat conductive models. And finally, it is observed that accurate solution to such problems may be obtained using Laplace transform method, especially for the time-dependent boundary conditions, e.g. heat flux boundary condition.
NASA Technical Reports Server (NTRS)
1997-01-01
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
NASA Astrophysics Data System (ADS)
Kühmstedt, Peter; Bräuer-Burchardt, Christian; Munkelt, Christoph; Heinze, Matthias; Palme, Martin; Schmidt, Ingo; Hintersehr, Josef; Notni, Gunther
2007-09-01
Here a new set-up of a 3D-scanning system for CAD/CAM in dental industry is proposed. The system is designed for direct scanning of the dental preparations within the mouth. The measuring process is based on phase correlation technique in combination with fast fringe projection in a stereo arrangement. The novelty in the approach is characterized by the following features: A phase correlation between the phase values of the images of two cameras is used for the co-ordinate calculation. This works contrary to the usage of only phase values (phasogrammetry) or classical triangulation (phase values and camera image co-ordinate values) for the determination of the co-ordinates. The main advantage of the method is that the absolute value of the phase at each point does not directly determine the coordinate. Thus errors in the determination of the co-ordinates are prevented. Furthermore, using the epipolar geometry of the stereo-like arrangement the phase unwrapping problem of fringe analysis can be solved. The endoscope like measurement system contains one projection and two camera channels for illumination and observation of the object, respectively. The new system has a measurement field of nearly 25mm × 15mm. The user can measure two or three teeth at one time. So the system can by used for scanning of single tooth up to bridges preparations. In the paper the first realization of the intraoral scanner is described.
NASA Technical Reports Server (NTRS)
1997-01-01
This area of terrain near the Sagan Memorial Station was taken on Sol 3 by the Imager for Mars Pathfinder (IMP). 3D glasses are necessary to identify surface detail.
The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.' It stands 1.8 meters above the Martian surface, and has a resolution of two millimeters at a range of two meters.
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
NASA Technical Reports Server (NTRS)
2004-01-01
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.
NASA Technical Reports Server (NTRS)
Brandon, S.; Derby, J. J.
1992-01-01
In the present investigation of crystalline phase internal radiation and heat conduction during the vertical Bridgman growth of a YAG-like oxide crystal, where transport through the melt is dominated by convection and conduction, heat is also noted to be conducted through ampoule walls via natural convection and enclosure radiation. The results of a quasi-steady-state axisymmetric Galerkin FEM indicate that heat transfer through the system is powerfully affected by the optical absorption coefficient of the crystal. The coupling of internal radiation through the crystal with conduction through the ampoule walls promotes melt/crystal interface shapes that are highly reflected near the ampoule wall.
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
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.
2013-01-01
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. PMID:23635097
The psychology of the 3D experience
NASA Astrophysics Data System (ADS)
Janicke, Sophie H.; Ellis, Andrew
2013-03-01
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.
Real-time monitoring of 3D cell culture using a 3D capacitance biosensor.
Lee, Sun-Mi; Han, Nalae; Lee, Rimi; Choi, In-Hong; Park, Yong-Beom; Shin, Jeon-Soo; Yoo, Kyung-Hwa
2016-03-15
Three-dimensional (3D) cell cultures have recently received attention because they represent a more physiologically relevant environment compared to conventional two-dimensional (2D) cell cultures. However, 2D-based imaging techniques or cell sensors are insufficient for real-time monitoring of cellular behavior in 3D cell culture. Here, we report investigations conducted with a 3D capacitance cell sensor consisting of vertically aligned pairs of electrodes. When GFP-expressing human breast cancer cells (GFP-MCF-7) encapsulated in alginate hydrogel were cultured in a 3D cell culture system, cellular activities, such as cell proliferation and apoptosis at different heights, could be monitored non-invasively and in real-time by measuring the change in capacitance with the 3D capacitance sensor. Moreover, we were able to monitor cell migration of human mesenchymal stem cells (hMSCs) with our 3D capacitance sensor. PMID:26386332
NASA Astrophysics Data System (ADS)
Miconi, C. E.; Estes, N. M.; Bowman-Cisneros, E.; Robinson, M. S.
2015-06-01
Lunaserv Global Explorer 3D is a platform independent, planetary data visualization application, which serves high resolution base-map imagery and terrain from web map service data sources, and displays it on a 3D spinning-globe interface.
Thermal Characterization for a Modular 3-D Multichip Module
NASA Technical Reports Server (NTRS)
Fan, Mark S.; Plante, Jeannette; Shaw, Harry
2000-01-01
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.
NASA Technical Reports Server (NTRS)
2009-01-01
[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 respect to the rest of the debris field had never been mapped before now.
This new insight into the structure of Cas A gained from this 3-D visualization is important for astronomers who build models of supernova explosions. Now, they must consider that the outer layers of the star come off spherically, but the inner layers come out more disk-like with high-velocity jets in multiple directions.
Gas-kinetic model of heat conduction of heterogeneous substances
NASA Astrophysics Data System (ADS)
Gladkov, S. O.
2008-07-01
A theoretical approach is proposed for calculating thermal conductivity κ of an arbitrary type of porous structures as a function of porosity ξ, temperature T, density ρ, and a number of other parameters. The general computational algorithm is based on the theory of nonequilibrium processes. Its modification in the language of gas-kinetic approximation makes it possible to derive compact relations for κ and to easily estimate the corresponding dependences. Theoretical formulas are compared to experimental results and their good agreement is demonstrated for a specific example of refractory concrete, which is a very important substance for practical applications.
Pokorny, Richard; Rice, Jarrett A.; Schweiger, Michael J.; Hrma, Pavel R.
2013-06-01
The cold cap is a layer of reacting glass batch floating on the surface of melt in an all-electric continuous glass melter. The heat needed for the conversion of the melter feed to molten glass must be transferred to and through the cold cap. Since the heat flux into the cold cap determines the rate of melting, the heat conductivity is a key property of the reacting feed. We designed an experimental setup consisting of a large cylindrical crucible with an assembly of thermocouples that monitors the evolution of the temperature field while the crucible is heated at a constant rate. Then we used two methods to calculate the heat conductivity and thermal diffusivity of the reacting feed: the approximation of the temperature field by polynomial functions and the finite-volume method coupled with least-squares analysis. Up to 680°C, the heat conductivity of the reacting melter feed was represented by a linear function of temperature.
NASA Technical Reports Server (NTRS)
Tamma, Kumar K.; Railkar, Sudhir B.
1989-01-01
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.
NASA Astrophysics Data System (ADS)
Hong, Seongik
In the 3D printing technology, the research for using various materials has been performing. In this research work, 3D printable high viscous materials are suggested as one of the solutions for problems in the traditional 3D printing technology. First, Cu-Ag coreshell was synthesized as a functional material. In terms of the reaction rate, reaction rate limiting step was defined as a fundamental research, and then prepared Cu-Ag coreshell was printed and analyzed. Second, the high viscous Cu paste was prepared and then metal 3D printed structure was fabricated by using new printing method. In the synthesis of Cu-Ag coreshell, different sizes of Cu particle, 2μm and 100nm were used, and when 2μm Cu was applied, the reaction rate was limited by film diffusion control. However, when 100nm Cu was applied, reaction rate was controlled by CuO film and the rate of the reaction, which includes removing CuO film in the solution, is limited by chemical reaction control. The shape of Cu-Ag particle is spherical in the 2μm Cu condition and dendrite shape in the 100nm Cu condition respectively. The conductivity of Cu-Ag coreshell paste increased as increasing content of coreshell particle in the paste and sintering temperature. In order to print high viscous metal paste, the high viscous Cu paste was printed by using screw extruder, and the viscosity of Cu paste was measured as a fundamental research. As increasing wt.% of Cu in the paste, the viscosity also increased. In addition, the shrinkage factor was reduced by increasing wt.% of Cu in the paste. An optimized printing condition for the high viscous material was obtained, and by using this condition, 3D metal structure was fabricated. The final product was heat treated and polished. Through these processes, a fine quality of metal 3D structure was printed.
Wei, Meilin; Wang, Xiaoxiang; Sun, Jingjing; Duan, Xianying
2013-06-01
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 (E{sub a}) of conductivity was estimated to be 1.01 eV. - Graphical abstract: A POM–MOF composite constructed by Keggin-type polyanion, Ni²⁺ and H₂bpdc shows good proton conductivities of 10⁻⁴–10⁻³ S cm⁻¹ at 100 °C under 35–98% RH. - Highlights: • A POM–MOF was constructed by combining metal N-heterocyclic multi-carboxylic acid framework and Keggin anion. • It opens a pathway for design and synthesis of multifunctional hybrid materials based on two building units. • Three types of potential proton-carriers have been assembled in the 1D hydrophilic channels of the POM–MOF. • It achieved such proton conductivities as 10⁻⁴–10⁻³ S cm⁻¹ at 100 °C in the RH range 35–98%.
Pesci, Elisabetta; Bettinetti, Laura; Fanti, Paola; Galietta, Luis J V; La Rosa, Salvatore; Magnoni, Letizia; Pedemonte, Nicoletta; Sardone, Gian Luca; Maccari, Laura
2015-12-24
Cystic fibrosis (CF) is a lethal genetic disease caused by mutations of the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) with a prevalence of the ΔF508 mutation. Whereas the detailed mechanisms underlying disease have yet to be fully elucidated, recent breakthroughs in clinical trials have demonstrated that CFTR dysfunction can be corrected by drug-like molecules. On the basis of this success, a screening campaign was carried out, seeking new drug-like compounds able to rescue ΔF508-CFTR that led to the discovery of a novel series of correctors based on a tetrahydropyrido[4,3-d]pyrimidine core. These molecules proved to be soluble, cell-permeable, and active in a disease relevant functional-assay. The series was then further optimized with emphasis on biological data from multiple cell systems while keeping physicochemical properties under strict control. The pharmacological and ADME profile of this corrector series hold promise for the development of more efficacious compounds to be explored for therapeutic use in CF. PMID:26561003
Yadav, Rana Pratap; Kumar, Sunil; Kulkarni, S V
2016-01-01
Design and developmental procedure of strip-line based 1.5 MW, 30-96 MHz, ultra-wideband high power 3 dB hybrid coupler has been presented and its applicability in ion cyclotron resonance heating (ICRH) in tokamak is discussed. For the high power handling capability, spacing between conductors and ground need to very high. Hence other structural parameters like strip-width, strip thickness coupling gap, and junction also become large which can be gone upto optimum limit where various constrains like fabrication tolerance, discontinuities, and excitation of higher TE and TM modes become prominent and significantly deteriorates the desired parameters of the coupled lines system. In designed hybrid coupler, two 8.34 dB coupled lines are connected in tandem to get desired coupling of 3 dB and air is used as dielectric. The spacing between ground and conductors are taken as 0.164 m for 1.5 MW power handling capability. To have the desired spacing, each of 8.34 dB segments are designed with inner dimension of 3.6 × 1.0 × 40 cm where constraints have been significantly realized, compensated, and applied in designing of 1.5 MW hybrid coupler and presented in paper. PMID:26827337
NASA Astrophysics Data System (ADS)
Yadav, Rana Pratap; Kumar, Sunil; Kulkarni, S. V.
2016-01-01
Design and developmental procedure of strip-line based 1.5 MW, 30-96 MHz, ultra-wideband high power 3 dB hybrid coupler has been presented and its applicability in ion cyclotron resonance heating (ICRH) in tokamak is discussed. For the high power handling capability, spacing between conductors and ground need to very high. Hence other structural parameters like strip-width, strip thickness coupling gap, and junction also become large which can be gone upto optimum limit where various constrains like fabrication tolerance, discontinuities, and excitation of higher TE and TM modes become prominent and significantly deteriorates the desired parameters of the coupled lines system. In designed hybrid coupler, two 8.34 dB coupled lines are connected in tandem to get desired coupling of 3 dB and air is used as dielectric. The spacing between ground and conductors are taken as 0.164 m for 1.5 MW power handling capability. To have the desired spacing, each of 8.34 dB segments are designed with inner dimension of 3.6 × 1.0 × 40 cm where constraints have been significantly realized, compensated, and applied in designing of 1.5 MW hybrid coupler and presented in paper.
NASA Astrophysics Data System (ADS)
Dede, Ercan M.; Nomura, Tsuyoshi; Schmalenberg, Paul; Seung Lee, Jae
2013-08-01
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.
BEAMS3D Neutral Beam Injection Model
NASA Astrophysics Data System (ADS)
McMillan, Matthew; Lazerson, Samuel A.
2014-09-01
With the advent of applied 3D fields in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous slowing down, and pitch angle scattering are modeled with the ADAS atomic physics database. Elementary benchmark calculations are presented to verify the collisionless particle orbits, NBI model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields. Notice: this manuscript has been authored by Princeton University under Contract Number DE-AC02-09CH11466 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.
NASA Astrophysics Data System (ADS)
Henke, Stephan; Gail, Hans-Peter; Trieloff, Mario
2016-04-01
Context. The construction of models for the internal constitution and temporal evolution of large planetesimals, which are the parent bodies of chondrites, requires as accurate as possible information on the heat conductivity of the complex mixture of minerals and iron metal found in chondrites. The few empirical data points on the heat conductivity of chondritic material are severely disturbed by impact-induced microcracks modifying the thermal conductivity. Aims: We attempt to evaluate the heat conductivity of chondritic material with theoretical methods. Methods: We derived the average heat conductivity of a multi-component mineral mixture and granular medium from the heat conductivities of its mixture components. We numerically generated random mixtures of solids with chondritic composition and packings of spheres. We solved the heat conduction equation in high spatial resolution for a test cube filled with such matter. We derived the heat conductivity of the mixture from the calculated heat flux through the cube. Results: For H and L chondrites, our results are in accord with empirical thermal conductivity at zero porosity. However, the porosity dependence of heat conductivity of granular material built from chondrules and matrix is at odds with measurements for chondrites, while our calculations are consistent with data for compacted sandstone. The discrepancy is traced back to subsequent shock modification of the currently available meteoritic material resulting from impacts on the parent body over the last 4.5 Ga. This causes a structure of void space made of fractures/cracks, which lowers the thermal conductivity of the medium and acts as a barrier to heat transfer. This structure is different from the structure that probably exists in the pristine material where voids are represented by pores rather than fractures. The results obtained for the heat conductivity of the pristine material are used for calculating models for the evolution of the H chondrite parent body, which are fitted to the cooling data of a number of H chondrites. The fit to the data is good; likewise the fit is good with models assuming different porosity. This is an indication that more diagnostic meteorite data are needed to distinguish between porosity models.
NASA Astrophysics Data System (ADS)
Kk, M.; Aydo?du, Y.
2007-04-01
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.
NASA Astrophysics Data System (ADS)
Zhang, Haihui; Wang, Wanlin; Zhou, Lejun
2015-10-01
A novel method for the estimation of the mold hot surface heat flux based on the measured responding temperatures from two columns of thermocouples that embedded inside the mold during continuous casting has been developed. The method includes a Two-Dimensional Inverse transient Heat Conduction Problem (2D-IHCP) model that was solved by the conjugate gradient method with Adjoint Equation. The model was validated by comparing the results with those calculated by a robust One-Dimensional Inverse transient Heat Conduction Problem (1D-IHCP). The solution of a test problem indicated that the Mean Absolute Percentage Error of the estimated heat flux calculated by the new method is about 9 to 40 pct of those calculated by the 1D-IHCP. Then, the method is applied to compute the heat flux for a mold simulator experiment. The results indicated that the heat fluxes and temperatures across mold hot surface calculated by 2D-IHCP show the same variation tendency as those calculated by 1D-IHCP. However, the heat fluxes calculated by 2D-IHCP are about 1.2 to 2 times larger than those calculated by 1D-IHCP for the locations below the liquid mold flux surface and are about 50 to 90 pct of those calculated by 1D-IHCP for the locations above the liquid mold flux surface.
NASA Astrophysics Data System (ADS)
Matcheva, K. I.; Strobel, D. F.
1998-09-01
Heating Jupiter's thermosphere by viscous dissipation of upward propagating gravity waves is evaluated with correct formulations of total energy conservation and the total wave induced vertical energy flux. In contrast to the results of Young et al. (1997, Science 276, 108-111), our calculations, with their wave amplitudes and parameters, yield a maximum thermospheric temperature of T=505 K at 680 km above the 1 bar level in comparison to the Galileo probe inferred temperature of T=900 K and therefore gravity waves may not be solely responsible for the observed steep temperature gradient just above the homopause. The large sensible heat flux associated with dissipating gravity waves generates net heating of the lower regions and net cooling of the upper regions of wave dissipation due to energy redistribution. The transition from net heating to net cooling occurs at the level of constant wave amplitude. In regions of substantial wave dissipation the local cooling rate due to sensible heat flux divergence can exceed the local heating due to convergence of the Eliassen-Palm flux to produce 1) net cooling of and 2) a distinct temperature decrease ( ~ 45 K) in the topside thermosphere. To simulate Jupiter's thermospheric temperature profile inferred from the Galileo probe data with 1) garvity wave heating only, 2) 100% conversion of wave energy to internal energy, and 3) radiative cooling by H_3(+) near-IR emission ~ 0.1 erg cm(-2}s({-1)) , gravity waves must deposit their energy high in the thermosphere with peak heating occurring near ~ 1000 km and with near saturation amplitudes at and above these heights.
The importance of electron heat conduction in the energy balance of the F-region
NASA Technical Reports Server (NTRS)
Hoegy, W. R.; Brace, L. H.
1978-01-01
Taking into account heat conduction in the analysis of electron temperature data acquired by the AE-C satellite during the daytime at middle latitudes is shown to bring theoretical electron temperature profiles in good agreement with experimental ones. Middle latitude passes were chosen because in this region the horizontal electron temperature gradient is negligible and the height variation can be approximated by the satellite data. Inclusion of heat conduction is shown to have little effect on low-latitude data.
NASA Technical Reports Server (NTRS)
Huerre, P.; Karamcheti, K.
1976-01-01
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.
3D Elevation Program—Virtual USA in 3D
Lukas, Vicki; Stoker, J.M.
2016-01-01
The U.S. Geological Survey (USGS) 3D Elevation Program (3DEP) uses a laser system called ‘lidar’ (light detection and ranging) to create a virtual reality map of the Nation that is very accurate. 3D maps have many uses with new uses being discovered all the time.
Effects of anisotropic conduction and heat pipe interaction on minimum mass space radiators
NASA Technical Reports Server (NTRS)
Baker, Karl W.; Lund, Kurt O.
1991-01-01
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.
On Thermo-viscoelasticity with Variable Thermal Conductivity and Fractional-Order Heat Transfer
NASA Astrophysics Data System (ADS)
Ezzat, M. A.; El-Karamany, A. S.; El-Bary, A. A.
2015-07-01
The equations of generalized thermo-viscoelasticity for an isotropic medium with variable thermal conductivity and fractional-order heat transfer are given. The resulting formulation is applied to a half-space subjected to arbitrary heating which is taken as a function of time and is traction free. The Laplace transform technique is used. A numerical method is employed for the inversion of the Laplace transforms. Numerical results for temperature, displacement, and stress distributions are given and illustrated graphically for the problem. The effects of the fractional order and the variable thermal conductivity for heat transfer on a viscoelastic material such as poly(methyl methacrylate) (Perspex) are discussed.
About Influence of Gravity on Heat Conductivity Process of the Planets
NASA Astrophysics Data System (ADS)
Gladkov, S. O.; Yadav, A.; Ray, Saibal; Rahaman, F.
2016-03-01
In the present study it is shown that the interaction of a quasi-static gravitational wave through density fluctuations give rise to a heat conductivity coefficient and hence rise in temperature. This fact is a very important characteristics needed to establish a heat equilibrium process of such massive body as the Earth and other Planets. To carry out this exercise, general mechanism has been provided, which makes a bridge between classical physics and quantum theory. The specific dependence of heat conductivity coefficient in wide region has also been calculated.
About Influence of Gravity on Heat Conductivity Process of the Planets
NASA Astrophysics Data System (ADS)
Gladkov, S. O.; Yadav, A.; Ray, Saibal; Rahaman, F.
2015-09-01
In the present study it is shown that the interaction of a quasi-static gravitational wave through density fluctuations give rise to a heat conductivity coefficient and hence rise in temperature. This fact is a very important characteristics needed to establish a heat equilibrium process of such massive body as the Earth and other Planets. To carry out this exercise, general mechanism has been provided, which makes a bridge between classical physics and quantum theory. The specific dependence of heat conductivity coefficient in wide region has also been calculated.
An Experimental-Numerical Evaluation of Thermal Contact Conductance in Fin-Tube Heat Exchangers
NASA Astrophysics Data System (ADS)
Kim, Chang Nyung; Jeong, Jin; Youn, Baek; Kil, Seong Ho
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.
Variable thermal properties and thermal relaxation time in hyperbolic heat conduction
NASA Technical Reports Server (NTRS)
Glass, David E.; Mcrae, D. Scott
1989-01-01
Numerical solutions were obtained for a finite slab with an applied surface heat flux at one boundary using both the hyperbolic (MacCormack's method) and parabolic (Crank-Nicolson method) heat conduction equations. The effects on the temperature distributions of varying density, specific heat, and thermal relaxation time were calculated. Each of these properties had an effect on the thermal front velocity (in the hyperbolic solution) as well as the temperatures in the medium. In the hyperbolic solutions, as the density or specific heat decreased with temperature, both the temperatures within the medium and the thermal front velocity increased. The value taken for the thermal relaxation time was found to determine the 'hyperbolicity' of the heat conduction model. The use of a time dependent relaxation time allowed for solutions where the thermal energy propagated as a high temperature wave initially, but approached a diffusion process more rapidly than was possible with a constant large relaxation time.
Thermal conductivity of cementitious grouts for geothermal heat pumps. Progress report FY 1997
Allan, M.L.
1997-11-01
Grout is used to seal the annulus between the borehole and heat exchanger loops in vertical geothermal (ground coupled, ground source, GeoExchange) heat pump systems. The grout provides a heat transfer medium between the heat exchanger and surrounding formation, controls groundwater movement and prevents contamination of water supply. Enhanced heat pump coefficient of performance (COP) and reduced up-front loop installation costs can be achieved through optimization of the grout thermal conductivity. The objective of the work reported was to characterize thermal conductivity and other pertinent properties of conventional and filled cementitious grouts. Cost analysis and calculations of the reduction in heat exchanger length that could be achieved with such grouts were performed by the University of Alabama. Two strategies to enhance the thermal conductivity of cementitious grouts were used simultaneously. The first of these was to incorporate high thermal conductivity filler in the grout formulations. Based on previous tests (Allan and Kavanaugh, in preparation), silica sand was selected as a suitable filler. The second strategy was to reduce the water content of the grout mix. By lowering the water/cement ratio, the porosity of the hardened grout is decreased. This results in higher thermal conductivity. Lowering the water/cement ratio also improves such properties as permeability, strength, and durability. The addition of a liquid superplasticizer (high range water reducer) to the grout mixes enabled reduction of water/cement ratio while retaining pumpability. Superplasticizers are commonly used in the concrete and grouting industry to improve rheological properties.
Ranganayakulu, C. ); Seetharamu, K.N. . School of Mechanical Engineering)
1999-07-01
An analysis of a crossflow plate-fin compact heat exchanger, accounting for the combined effects of two-dimensional longitudinal heat conduction through the exchanger wall and nonuniform inlet fluid flow and temperature distribution is carried out using a finite element method. A mathematical equation is developed to generate different types of fluid flow/temperature maldistribution models considering the possible deviations in fluid flow. Using these models, the exchanger effectiveness and its deterioration due to the combined effects of longitudinal heat conduction, flow nonuniformity and temperature nonuniformity are calculated for various design and operating conditions of the exchanger. It was found that the performance variations are quite significant in some typical applications.
Scoops3D: software to analyze 3D slope stability throughout a digital landscape
Reid, Mark E.; Christian, Sarah B.; Brien, Dianne L.; Henderson, Scott T.
2015-01-01
The computer program, Scoops3D, evaluates slope stability throughout a digital landscape represented by a digital elevation model (DEM). The program uses a three-dimensional (3D) method of columns approach to assess the stability of many (typically millions) potential landslides within a user-defined size range. For each potential landslide (or failure), Scoops3D assesses the stability of a rotational, spherical slip surface encompassing many DEM cells using a 3D version of either Bishop’s simplified method or the Ordinary (Fellenius) method of limit-equilibrium analysis. Scoops3D has several options for the user to systematically and efficiently search throughout an entire DEM, thereby incorporating the effects of complex surface topography. In a thorough search, each DEM cell is included in multiple potential failures, and Scoops3D records the lowest stability (factor of safety) for each DEM cell, as well as the size (volume or area) associated with each of these potential landslides. It also determines the least-stable potential failure for the entire DEM. The user has a variety of options for building a 3D domain, including layers or full 3D distributions of strength and pore-water pressures, simplistic earthquake loading, and unsaturated suction conditions. Results from Scoops3D can be readily incorporated into a geographic information system (GIS) or other visualization software. This manual includes information on the theoretical basis for the slope-stability analysis, requirements for constructing and searching a 3D domain, a detailed operational guide (including step-by-step instructions for using the graphical user interface [GUI] software, Scoops3D-i) and input/output file specifications, practical considerations for conducting an analysis, results of verification tests, and multiple examples illustrating the capabilities of Scoops3D. Easy-to-use software installation packages are available for the Windows or Macintosh operating systems; these packages install the compiled Scoops3D program, the GUI (Scoops3D-i), and associated documentation. Several Scoops3D examples, including all input and output files, are available as well. The source code is written in the Fortran 90 language and can be compiled to run on any computer operating system with an appropriate compiler.
Thermal conduction and heating by nonthermal electrons in the X-ray halo of M87
NASA Technical Reports Server (NTRS)
Tucker, W. H.; Rosner, R.
1983-01-01
A hydrostatic model for the X-ray halo around the giant elliptical galaxy M87 is presented. It is shown that by taking into account the processes of thermal conduction, and nonthermal heating by relativistic electrons in the radio lobes, a self-consistent hydrostatic model can be constructed. There is no need to invoke radiative accretion or the suppression of thermal conductivity.
Kumar, Suhas; Pickett, Matthew D; Strachan, John Paul; Gibson, Gary; Nishi, Yoshio; Williams, R Stanley
2013-11-13
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
ERIC Educational Resources Information Center
Chiou, Guo-Li; Anderson, O. Roger
2010-01-01
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
ERIC Educational Resources Information Center
Chiou, Guo-Li; Anderson, O. Roger
2010-01-01
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…
Radiative heat exchange of a meteor body in the approximation of radiant heat conduction
Pilyugin, N.N.; Chernova, T.A.
1986-07-01
The problem of the thermal and dynamic destruction of large meteor bodies moving in planetary atmospheres is fundamental for the clarification of optical observations and anomalous phenomena in the atmosphere, the determination of the physicochemical properties of meteoroids, and the explanation of the fall of remnants of large meteorites. Therefore, it is important to calculate the coefficient of radiant heat exchange (which is the determining factor under these conditions) for large meteor bodies as they move with hypersonic velocities in an atmosphere. The solution of this problem enables one to find the ablation of a meteorite during its aerodynamic heating and to determine the initial conditions for the solution of problems of the breakup of large bodies and their subsequent motion and ablation. Hypersonic flow of an inviscid gas stream over an axisymmetric blunt body is analyzed with allowance for radiative transfer in a thick-thin approximation. The gas-dynamic problem of the flow of an optically thick gas over a large body is solved by the method of asymptotic joined expansions, using a hypersonic approximation and local self-similarity. An equation is obtained for the coefficient of radiant heat exchange and the peculiarities of such heat exchange for meteor bodies of large size are noted.
Conductivity heating a subterranean oil shale to create permeability and subsequently produce oil
Van Meurs, P.; DeRouffignac, E.P.; Vinegar, H.J.; Lucid, M.F.
1989-12-12
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.
Plate Fin Heat Exchanger Model with Axial Conduction and Variable Properties
Hansen, B.J.; White, M.J.; Klebaner, A.; /Fermilab
2011-06-10
Future superconducting radio frequency (SRF) cavities, as part of Project X at Fermilab, will be cooled to superfluid helium temperatures by a cryogenic distribution system supplying cold supercritical helium. To reduce vapor fraction during the final Joule-Thomson (J-T) expansion into the superfluid helium cooling bath, counter-flow, plate-fin heat exchangers will be utilized. Due to their compact size and ease of fabrication, plate-fin heat exchangers are an effective option. However, the design of compact and high-effectiveness cryogenic heat exchangers operating at liquid helium temperatures requires consideration of axial heat conduction along the direction of flow, in addition to variable fluid properties. Here we present a numerical model that includes the effects of axial conduction and variable properties for a plate fin heat exchanger. The model is used to guide design decisions on heat exchanger material choice and geometry. In addition, the J-T expansion process is modeled with the heat exchanger to analyze the effect of heat load and cryogenic supply parameters. A numerical model that includes the effects of axial conduction and variable properties for a plate fin heat exchanger was developed and the effect of various design parameters on overall heat exchanger size was investigated. It was found that highly conductive metals should be avoided in the design of compact JT heat exchangers. For the geometry considered, the optimal conductivity is around 3.5 W/m-K and can range from 0.3-10 W/m-K without a large loss in performance. The model was implemented with an isenthalpic expansion process. Increasing the cold side inlet temperature from 2K to 2.2 K decreased the liquid fraction from 0.856 to 0.839 which corresponds to a 0.12 g/s increase in supercritical helium supply needed to maintain liquid level in the cooling bath. Lastly, it was found that the effectiveness increased when the heat load was below the design value. Therefore, the heat exchanger should be sized on the high end of the required heat load.
2013-10-30
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.
Energy Science and Technology Software Center (ESTSC)
2013-10-01
Earth3D is a computer code designed to allow fast calculation of seismic rays and travel times through a 3D model of the Earth. LLNL is using this for earthquake location and global tomography efforts and such codes are of great interest to the Earth Science community.
NASA Technical Reports Server (NTRS)
1977-01-01
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.
None
2014-02-26
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.
MT3D was first developed by Chunmiao Zheng in 1990 at S.S. Papadopulos & Associates, Inc. with partial support from the U.S. Environmental Protection Agency (USEPA). Starting in 1990, MT3D was released as a pubic domain code from the USEPA. Commercial versions with enhanced capab...
NASA Technical Reports Server (NTRS)
Chen, Ming-Ming; Faghri, Amir
1990-01-01
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.
Allan, M.L.
1996-06-01
Preliminary studies were preformed to determine whether thermal conductivity of cementitious grouts used to backfill heat exchanger loops for geothermal heat pumps could be improved, thus improving efficiency. Grouts containing selected additives were compares with conventional bentonite and cement grouts. Significant enhancement of grout alumina grit, steel fibers, and silicon carbide increased the thermal conductivity when compared to unfilled, high solids bentonite grouts and conventional cement grouts. Furthermore, the developed grouts retained high thermal conductivity in the dry state, where as conventional bentonite and cement grouts tend to act as insulators if moisture is lost. The cementitious grouts studied can be mixed and placed using conventional grouting equipment.
NASA Astrophysics Data System (ADS)
Walsh, J. R.
2004-02-01
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.
NASA Technical Reports Server (NTRS)
Walatka, Pamela P.; Buning, Pieter G.; Pierce, Larry; Elson, Patricia A.
1990-01-01
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.
Dawood, A; Marti Marti, B; Sauret-Jackson, V; Darwood, A
2015-12-01
3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery. PMID:26657435
Numerical simulation on the thermal response of heat-conducting asphalt pavements
NASA Astrophysics Data System (ADS)
Wang, Hong; Wu, Shaopeng; Chen, Mingyu; Zhang, Yuan
2010-05-01
Using asphalt pavements as a solar collector is a subject of current interest all over the world because the sun provides a cheap and abundant source of clean and renewable energy, which can be captured by black asphalt pavements. A heat-conducting device is designed to absorb energy from the sun. In order to validate what parameters are critical in the asphalt collector, a finite element model is developed to predict the thermal response of the heat-conducting device compared to the conventional asphalt mixture. Some factors that may affect the asphalt pavement collector are considered, including the coefficient of heat conductivity of the asphalt pavement, the distance between pipes with the medium, water, and the pipe's diameter. Ultimately, the finite element model can provide pavement engineers with an efficient computational tool that can be a guide to the conductive asphalt solar collector's experiment in the laboratory.
Heat Conduction through Surface Structures and Mixtures using Electric Circuits as Analogs
NASA Astrophysics Data System (ADS)
Huebner, W. F.; Boice, D. C.; Green, J. R.
1998-09-01
We present a mathematical model using electric analogs to simulate vertical and lateral conductive heat flow in surface layers of planetary bodies with topography. The model can also be used to determine average electric and thermal conductivities of small-scale granular mixtures (as opposed to molecular mixtures). The algorithm is general and applicable to complex compositions. Analogies between thermal and electric conductivities are basic and well known. The model uses Kirchhoff's rules for electric networks. If a temperature difference is maintained across a solid body, the thermal energy transported per unit time and unit area, (the vector heat current per unit area, Q), is proportional to the negative temperature gradient, such that Q = - kappa nabla T. Here kappa is the heat (or thermal) conductivity of the material. For the electric analogy we use Ohm's law. If a potential difference is maintained in a resistive (ohmic) body, the electric charge transported per unit time and unit area (the vector current density, i) is proportional to the electric field, such that i = sigma E = - sigma nabla V. Here sigma is the electric conductivity (or specific conductance) of the material and V is the electric potential. With i replacing Q and V replacing T the parallel nature of thermal and electric conductivity is established. The thermal conductivity, kappa , is a direct analog to the electric conductivity, sigma . The model will be used to verify heat flow measured through porous mixtures of ice and dust as an analog of comet matter in the laboratory. Heat flow is simulated by electric currents through a three-dimensional network of resistors with emfs representing temperatures at boundaries. We illustrate our model, for simplicity, with a two-dimensional network. Each type of material with given conductivity is represented by a corresponding value for the electric resistance. The number of each type of resistor is proportional to the relative abundance of each material type. For mixtures, resistors are selected randomly.
Evaluation of vision training using 3D play game
NASA Astrophysics Data System (ADS)
Kim, Jung-Ho; Kwon, Soon-Chul; Son, Kwang-Chul; Lee, Seung-Hyun
2015-03-01
The present study aimed to examine the effect of the vision training, which is a benefit of watching 3D video images (3D video shooting game in this study), focusing on its accommodative facility and vergence facility. Both facilities, which are the scales used to measure human visual performance, are very important factors for man in leading comfortable and easy life. This study was conducted on 30 participants in their 20s through 30s (19 males and 11 females at 24.53 ± 2.94 years), who can watch 3D video images and play 3D game. Their accommodative and vergence facility were measured before and after they watched 2D and 3D game. It turned out that their accommodative facility improved after they played both 2D and 3D games and more improved right after they played 3D game than 2D game. Likewise, their vergence facility was proved to improve after they played both 2D and 3D games and more improved soon after they played 3D game than 2D game. In addition, it was demonstrated that their accommodative facility improved to greater extent than their vergence facility. While studies have been so far conducted on the adverse effects of 3D contents, from the perspective of human factor, on the imbalance of visual accommodation and convergence, the present study is expected to broaden the applicable scope of 3D contents by utilizing the visual benefit of 3D contents for vision training.
Documentation and verification of STRES3D, Version 4.0; Yucca Mountain Site Characterization Project
Asgian, M.I.; St. John, C.M.; Hardy, M.P.; Goodrich, R.R.
1991-12-01
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.
Solar abundances and 3D model atmospheres
NASA Astrophysics Data System (ADS)
Ludwig, Hans-Günter; Caffau, Elisabetta; Steffen, Matthias; Bonifacio, Piercarlo; Freytag, Bernd; Cayrel, Roger
2010-03-01
We present solar photospheric abundances for 12 elements from optical and near-infrared spectroscopy. The abundance analysis was conducted employing 3D hydrodynamical (CO5BOLD) as well as standard 1D hydrostatic model atmospheres. We compare our results to others with emphasis on discrepancies and still lingering problems, in particular exemplified by the pivotal abundance of oxygen. We argue that the thermal structure of the lower solar photosphere is very well represented by our 3D model. We obtain an excellent match of the observed center-to-limb variation of the line-blanketed continuum intensity, also at wavelengths shortward of the Balmer jump.
NASA Technical Reports Server (NTRS)
1997-01-01
Yogi, a rock taller than rover Sojourner, is the subject of this image, taken in stereo by the deployed Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. The soil in the foreground has been the location of multiple soil mechanics experiments performed by Sojourner's cleated wheels. Pathfinder scientists were able to control the force inflicted on the soil beneath the rover's wheels, giving them insight into the soil's mechanical properties. The soil mechanics experiments were conducted after this image was taken.
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
PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITH TURB3D)
NASA Technical Reports Server (NTRS)
Buning, P.
1994-01-01
PLOT3D is an interactive graphics program designed to help scientists visualize computational fluid dynamics (CFD) grids and solutions. Today, supercomputers and CFD algorithms can provide scientists with simulations of such highly complex phenomena that obtaining an understanding of the simulations has become a major problem. Tools which help the scientist visualize the simulations can be of tremendous aid. PLOT3D/AMES offers more functions and features, and has been adapted for more types of computers than any other CFD graphics program. Version 3.6b+ is supported for five computers and graphic libraries. Using PLOT3D, CFD physicists can view their computational models from any angle, observing the physics of problems and the quality of solutions. As an aid in designing aircraft, for example, PLOT3D's interactive computer graphics can show vortices, temperature, reverse flow, pressure, and dozens of other characteristics of air flow during flight. As critical areas become obvious, they can easily be studied more closely using a finer grid. PLOT3D is part of a computational fluid dynamics software cycle. First, a program such as 3DGRAPE (ARC-12620) helps the scientist generate computational grids to model an object and its surrounding space. Once the grids have been designed and parameters such as the angle of attack, Mach number, and Reynolds number have been specified, a "flow-solver" program such as INS3D (ARC-11794 or COS-10019) solves the system of equations governing fluid flow, usually on a supercomputer. Grids sometimes have as many as two million points, and the "flow-solver" produces a solution file which contains density, x- y- and z-momentum, and stagnation energy for each grid point. With such a solution file and a grid file containing up to 50 grids as input, PLOT3D can calculate and graphically display any one of 74 functions, including shock waves, surface pressure, velocity vectors, and particle traces. PLOT3D's 74 functions are organized into five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. The Apollo implementation of PLOT3D uses some of the capabilities of Apollo's 3-dimensional graphics hardware, but does not take advantage of the shading and hidden line/surface removal capabilities of the Apollo DN10000. Although this implementation does not offer a capability for putting text on plots, it does support the use of a mouse to translate, rotate, or zoom in on views. The version 3.6b+ Apollo implementations of PLOT3D (ARC-12789) and PLOT3D/TURB3D (ARC-12785) were developed for use on Apollo computers running UNIX System V with BSD 4.3 extensions and the graphics library GMR3D Version 2.0. The standard distribution media for each of these programs is a 9-track, 6250 bpi magnetic tape in TAR format. Customers purchasing one implementation version of PLOT3D or PLOT3D/TURB3D will be given a $200 discount on each additional implementation version ordered at the same time. Version 3.6b+ of PLOT3D and PLOT3D/TURB3D are also supported for the following computers and graphics libraries: 1) generic UNIX Supercomputer and IRIS, suitable for CRAY 2/UNICOS, CONVEX, and Alliant with remote IRIS 2xxx/3xxx or IRIS 4D (ARC-12779, ARC-12784); 2) VAX computers running VMS Version 5.0 and DISSPLA Version 11.0 (ARC-12777, ARC-12781); 3) generic UNIX and DISSPLA Version 11.0 (ARC-12788, ARC-12778); and (4) Silicon Graphics IRIS 2xxx/3xxx or IRIS 4D workstations (ARC-12783, ARC-12782). Silicon Graphics Iris, IRIS 4D, and IRIS 2xxx/3xxx are trademarks of Silicon Graphics Incorporated. VAX and VMS are trademarks of Digital Electronics Corporation. DISSPLA is a trademark of Computer Associates. CRAY 2 and UNICOS are trademarks of CRAY Research, Incorporated. CONVEX is a trademark of Convex Computer Corporation. Alliant is a trademark of Alliant. Apollo and GMR3D are trademarks of Hewlett-Packard, Incorporated. UNIX is a registered trademark of AT&T.
PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITHOUT TURB3D)
NASA Technical Reports Server (NTRS)
Buning, P.
1994-01-01
PLOT3D is an interactive graphics program designed to help scientists visualize computational fluid dynamics (CFD) grids and solutions. Today, supercomputers and CFD algorithms can provide scientists with simulations of such highly complex phenomena that obtaining an understanding of the simulations has become a major problem. Tools which help the scientist visualize the simulations can be of tremendous aid. PLOT3D/AMES offers more functions and features, and has been adapted for more types of computers than any other CFD graphics program. Version 3.6b+ is supported for five computers and graphic libraries. Using PLOT3D, CFD physicists can view their computational models from any angle, observing the physics of problems and the quality of solutions. As an aid in designing aircraft, for example, PLOT3D's interactive computer graphics can show vortices, temperature, reverse flow, pressure, and dozens of other characteristics of air flow during flight. As critical areas become obvious, they can easily be studied more closely using a finer grid. PLOT3D is part of a computational fluid dynamics software cycle. First, a program such as 3DGRAPE (ARC-12620) helps the scientist generate computational grids to model an object and its surrounding space. Once the grids have been designed and parameters such as the angle of attack, Mach number, and Reynolds number have been specified, a "flow-solver" program such as INS3D (ARC-11794 or COS-10019) solves the system of equations governing fluid flow, usually on a supercomputer. Grids sometimes have as many as two million points, and the "flow-solver" produces a solution file which contains density, x- y- and z-momentum, and stagnation energy for each grid point. With such a solution file and a grid file containing up to 50 grids as input, PLOT3D can calculate and graphically display any one of 74 functions, including shock waves, surface pressure, velocity vectors, and particle traces. PLOT3D's 74 functions are organized into five groups: 1) Grid Functions for grids, grid-checking, etc.; 2) Scalar Functions for contour or carpet plots of density, pressure, temperature, Mach number, vorticity magnitude, helicity, etc.; 3) Vector Functions for vector plots of velocity, vorticity, momentum, and density gradient, etc.; 4) Particle Trace Functions for rake-like plots of particle flow or vortex lines; and 5) Shock locations based on pressure gradient. TURB3D is a modification of PLOT3D which is used for viewing CFD simulations of incompressible turbulent flow. Input flow data consists of pressure, velocity and vorticity. Typical quantities to plot include local fluctuations in flow quantities and turbulent production terms, plotted in physical or wall units. PLOT3D/TURB3D includes both TURB3D and PLOT3D because the operation of TURB3D is identical to PLOT3D, and there is no additional sample data or printed documentation for TURB3D. Graphical capabilities of PLOT3D version 3.6b+ vary among the implementations available through COSMIC. Customers are encouraged to purchase and carefully review the PLOT3D manual before ordering the program for a specific computer and graphics library. There is only one manual for use with all implementations of PLOT3D, and although this manual generally assumes that the Silicon Graphics Iris implementation is being used, informative comments concerning other implementations appear throughout the text. With all implementations, the visual representation of the object and flow field created by PLOT3D consists of points, lines, and polygons. Points can be represented with dots or symbols, color can be used to denote data values, and perspective is used to show depth. Differences among implementations impact the program's ability to use graphical features that are based on 3D polygons, the user's ability to manipulate the graphical displays, and the user's ability to obtain alternate forms of output. The Apollo implementation of PLOT3D uses some of the capabilities of Apollo's 3-dimensional graphics hardware, but does not take advantage of the shading and hidden line/surface removal capabilities of the Apollo DN10000. Although this implementation does not offer a capability for putting text on plots, it does support the use of a mouse to translate, rotate, or zoom in on views. The version 3.6b+ Apollo implementations of PLOT3D (ARC-12789) and PLOT3D/TURB3D (ARC-12785) were developed for use on Apollo computers running UNIX System V with BSD 4.3 extensions and the graphics library GMR3D Version 2.0. The standard distribution media for each of these programs is a 9-track, 6250 bpi magnetic tape in TAR format. Customers purchasing one implementation version of PLOT3D or PLOT3D/TURB3D will be given a $200 discount on each additional implementation version ordered at the same time. Version 3.6b+ of PLOT3D and PLOT3D/TURB3D are also supported for the following computers and graphics libraries: 1) generic UNIX Supercomputer and IRIS, suitable for CRAY 2/UNICOS, CONVEX, and Alliant with remote IRIS 2xxx/3xxx or IRIS 4D (ARC-12779, ARC-12784); 2) VAX computers running VMS Version 5.0 and DISSPLA Version 11.0 (ARC-12777, ARC-12781); 3) generic UNIX and DISSPLA Version 11.0 (ARC-12788, ARC-12778); and (4) Silicon Graphics IRIS 2xxx/3xxx or IRIS 4D workstations (ARC-12783, ARC-12782). Silicon Graphics Iris, IRIS 4D, and IRIS 2xxx/3xxx are trademarks of Silicon Graphics Incorporated. VAX and VMS are trademarks of Digital Electronics Corporation. DISSPLA is a trademark of Computer Associates. CRAY 2 and UNICOS are trademarks of CRAY Research, Incorporated. CONVEX is a trademark of Convex Computer Corporation. Alliant is a trademark of Alliant. Apollo and GMR3D are trademarks of Hewlett-Packard, Incorporated. UNIX is a registered trademark of AT&T.
NASA Astrophysics Data System (ADS)
Anisimov, M. V.; Rekunov, V. S.; Babuta, M. N.; Bach Lien, Nguyen Thi Hong
2016-02-01
We experimentally determined the coefficients of thermal conductivity of some ultra thin liquid composite heat insulating coatings, for sample #1 λ = 0.086 W/(m·°C), for sample #2 λ = 0.091 W/(m·°C). We performed the measurement error calculation. The actual thermal conduction coefficient of the studied samples was higher than the declared one. The manufactures of liquid coatings might have used some "ideal" conditions when defining heat conductivity in the laboratory or the coefficient was obtained by means of theoretical solution of heat conduction problem in liquid composite insulating media. However, liquid insulating coatings are of great interest to builders, because they allow to warm objects of complex geometric shapes (valve chambers, complex assemblies, etc.), which makes them virtually irreplaceable. The proper accounting of heating qualities of paints will allow to avoid heat loss increase above the specified limits in insulated pipes with heat transfer materials or building structures, as well as protect them from possible thawing in the period of subzero weather.
Thermal conductivity from hierarchical heat sinks using carbon nanotubes and graphene nanosheets.
Hsieh, Chien-Te; Lee, Cheng-En; Chen, Yu-Fu; Chang, Jeng-Kuei; Teng, Hsi-sheng
2015-11-28
The in-plane (kip) and through-plane (ktp) thermal conductivities of heat sinks using carbon nanotubes (CNTs), graphene nanosheets (GNs), and CNT/GN composites are extracted from two experimental setups within the 323-373 K temperature range. Hierarchical three-dimensional CNT/GN frameworks display higher kip and ktp values, as compared to the CNT- and GN-based heat sinks. The kip and ktp values of the CNT/GN-based heat sink reach as high as 1991 and 76 W m(-1) K(-1) at 323 K, respectively. This improved thermal conductivity is attributed to the fact that the hierarchical heat sink offers a stereo thermal conductive network that combines point, line, and plane contact, leading to better heat transport. Furthermore, the compression treatment provided an efficient route to increase both kip and ktp values. This result reveals that the hierarchical carbon structures become denser, inducing more thermal conductive area and less thermal resistivity, i.e., a reduced possibility of phonon-boundary scattering. The correlation between thermal and electrical conductivity (ε) can be well described by two empirical equations: kip = 567 ln(ε) + 1120 and ktp = 20.6 ln(ε) + 36.1. The experimental results are obtained within the temperature range of 323-373 K, suitably complementing the thermal management of chips for consumer electronics. PMID:26498343
The radiant component of steam heat conductivity at high pressures and temperatures
NASA Astrophysics Data System (ADS)
Panchenko, S. V.; Dli, M. I.; Borisov, V. V.
2015-07-01
The problem of energy transfer by heat conduction and radiation is brought to a differential equation containing temperature derivatives at the boundaries and based on the selectively gray approximation of absorbing medium. A method for analytically solving the linearized problem radiant-conductive heat transfer in a flat layer of selectively absorbing medium is proposed, using which an unsymmetrical temperature profile more accurately approximating the experimental results can be obtained. The adequacy of the solution method is demonstrated by comparing the calculation results with the experimental and the results obtained using numerical methods. The effect the intermolecular interactions have on the optical properties of highly compressed media is analyzed. A dependence for determining the integral intensity of steam bands at pressures of up to 100 MPa is obtained. Quite satisfactory agreement is obtained between the calculated values of absorption intensities at increased pressures, including those for steam. The radiant component values obtained from steam heat conductivity measurements carried out in a wide range of temperatures taking into account the absorption selectivity and deviation of heat conductivity coefficients with absorption and for a transparent gas model are presented. The study results can be used for estimating the radiant component in heat conductivity measurements of absorbing fluids.
Stretch diffusion and heat conduction in one-dimensional nonlinear lattices
NASA Astrophysics Data System (ADS)
Gao, Zhibin; Li, Nianbei; Li, Baowen
2016-03-01
For heat conduction in one-dimensional (1D) nonlinear Hamiltonian lattices, it has been known that conserved quantities play an important role in determining the actual heat conduction behavior. In closed or microcanonical Hamiltonian systems, the total energy and stretch are always conserved. Depending on the existence of external on-site potential, the total momentum can be conserved or not. All the momentum-conserving lattices have anomalous heat conduction except the 1D coupled rotator lattice. It was recently claimed that "whenever stretch (momentum) is not conserved in a 1D model, the momentum (stretch) and energy fields exhibit normal diffusion." The stretch in a coupled rotator lattice was also argued to be nonconserved due to the requirement of a finite partition function, which enables the coupled rotator lattice to fulfill this claim. In this work, we will systematically investigate stretch diffusion and heat conduction in terms of energy diffusion for typical 1D nonlinear lattices. Contrary to what was claimed, no clear connection between conserved quantities and heat conduction can be established. The actual situation might be more complicated than what was proposed.
Thermal conductivity from hierarchical heat sinks using carbon nanotubes and graphene nanosheets
NASA Astrophysics Data System (ADS)
Hsieh, Chien-Te; Lee, Cheng-En; Chen, Yu-Fu; Chang, Jeng-Kuei; Teng, Hsi-Sheng
2015-11-01
The in-plane (kip) and through-plane (ktp) thermal conductivities of heat sinks using carbon nanotubes (CNTs), graphene nanosheets (GNs), and CNT/GN composites are extracted from two experimental setups within the 323-373 K temperature range. Hierarchical three-dimensional CNT/GN frameworks display higher kip and ktp values, as compared to the CNT- and GN-based heat sinks. The kip and ktp values of the CNT/GN-based heat sink reach as high as 1991 and 76 W m-1 K-1 at 323 K, respectively. This improved thermal conductivity is attributed to the fact that the hierarchical heat sink offers a stereo thermal conductive network that combines point, line, and plane contact, leading to better heat transport. Furthermore, the compression treatment provided an efficient route to increase both kip and ktp values. This result reveals that the hierarchical carbon structures become denser, inducing more thermal conductive area and less thermal resistivity, i.e., a reduced possibility of phonon-boundary scattering. The correlation between thermal and electrical conductivity (ε) can be well described by two empirical equations: kip = 567 ln(ε) + 1120 and ktp = 20.6 ln(ε) + 36.1. The experimental results are obtained within the temperature range of 323-373 K, suitably complementing the thermal management of chips for consumer electronics.
Impedance mammograph 3D phantom studies.
Wtorek, J; Stelter, J; Nowakowski, A
1999-04-20
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
Stanton, M M; Samitier, J; Sánchez, S
2015-08-01
Three-dimensional (3D) bioprinting has recently emerged as an extension of 3D material printing, by using biocompatible or cellular components to build structures in an additive, layer-by-layer methodology for encapsulation and culture of cells. These 3D systems allow for cell culture in a suspension for formation of highly organized tissue or controlled spatial orientation of cell environments. The in vitro 3D cellular environments simulate the complexity of an in vivo environment and natural extracellular matrices (ECM). This paper will focus on bioprinting utilizing hydrogels as 3D scaffolds. Hydrogels are advantageous for cell culture as they are highly permeable to cell culture media, nutrients, and waste products generated during metabolic cell processes. They have the ability to be fabricated in customized shapes with various material properties with dimensions at the micron scale. 3D hydrogels are a reliable method for biocompatible 3D printing and have applications in tissue engineering, drug screening, and organ on a chip models. PMID:26066320
Unassisted 3D camera calibration
NASA Astrophysics Data System (ADS)
Atanassov, Kalin; Ramachandra, Vikas; Nash, James; Goma, Sergio R.
2012-03-01
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.
NASA Astrophysics Data System (ADS)
Saleeb, Noha; Dafoulas, Georgios
Evolving online virtual worlds are intensely being utilised as 3D Virtual Learning Environments (3D VLEs) by hundreds of universities worldwide. However, there is inadequate academic research depicting satisfaction of users from the environmental design factors of 3D virtual buildings used within these virtual worlds. Specifically, there is no research evidence representing satisfaction of educational facilities' users, namely students and faculty, from the architectural design characteristics of their 3D virtual university campuses. This research focuses explicitly on capturing the contentment levels of students towards specified variations of certain architectural design elements of the 3D virtual learning spaces, where educational sessions are conducted in 3D VLEs. This hence provides preliminary guidelines on how to enhance the design of these spaces to augment e-learning experiences of students within 3D VLEs; achieved by analysing survey results representing students' opinions towards different architectural features of the learning spaces within different university 3D virtual campuses.
NASA Astrophysics Data System (ADS)
Alexander, Kahrimanidis; Daniel, Wortberg; Marion, Merklein
Tailored heat treated blanks are a well-known approach to enhance the formability of 6000-series aluminum alloys. The desired strength and ductility distribution can be adjusted by laser, induction or conduction heating. The present work investigates the influence of short term conduction and induction heat treatments on the mechanical properties of AA6014 aluminum alloys. The reduction in yield strength and uniform elongation is compared with literature data from laser heating. Additionally, the homogeneity of the temperature distributions and heating rates are evaluated. The results indicate that by conduction heating the uniform elongation is less influenced as by laser and induction heating, due to a higher homogeneity of the temperature distribution.
Recovery of normal heat conduction in harmonic chains with correlated disorder
NASA Astrophysics Data System (ADS)
Herrera-González, I. F.; Izrailev, F. M.; Tessieri, L.
2015-06-01
We consider heat transport in one-dimensional harmonic chains with isotopic disorder, focusing our attention mainly on how disorder correlations affect heat conduction. Our approach reveals that long-range correlations can change the number of low-frequency extended states. As a result, with a proper choice of correlations one can control how the conductivity κ scales with the chain length N. We present a detailed analysis of the role of specific long-range correlations for which a size-independent conductivity is exactly recovered in the case of fixed boundary conditions. As for free boundary conditions, we show that disorder correlations can lead to a conductivity scaling as κ ∼ N\\varepsilon , with the scaling exponent ε being arbitrarily small (although not strictly zero), so that normal conduction is almost recovered even in this case.
Empirical evaluation of diving wet suit material heat transfer and thermal conductivity
West, P.B.
1993-10-01
This wet suit material testing program provides a quantitative thermal conductivity and heat transfer analysis, and comparison of various materials used in skin diving and SCUBA diving. Thermal resistance represents the primary subject examined, but due to compressibility of the baseline materials and its effect on heat transfer, this program also examines compression at simulated depth. This article reports the empirical heat transfer coefficients for both thermal conductivity and convection. Due to the limitations of the test apparatus, this analysis must restrict the convection evaluation to an approximately 20-cm-height, free-convection model. As a consequence, this model best simulates the overall heat transfer coefficient of a diver hovering in a horizontal position. This program also includes evaluations of some nonstandard materials in an effort to identify alternative wet suit materials.
Enhancement of heat conduction in carbon nanotubes filled with fullerene molecules.
Cui, Liu; Feng, Yanhui; Zhang, Xinxin
2015-11-01
Heat conduction in carbon nanopeapods (CNPs), i.e. carbon nanotubes (CNTs) filled with fullerene C60 molecules, is investigated using molecular dynamics simulations. The enhancement mechanisms of CNP thermal conductivity, compared with bare CNTs, are discussed via the local heat flux onto a single atom, the relative contributions of different phonon oscillation frequencies to thermal conductivity and the phonon vibrational density of states. The result shows that filled C60 can increase the CNT thermal conductivity by up to 9.6 times in the temperature range of 100-500 K. The constructive phonon mode couplings between the tube and C60 in a frequency range of 0-20 THz, especially in x-, y-direction transverse acoustic modes and the radial breath mode, are primarily responsible for the increment of thermal conductivity. In addition, filled C60 molecules in CNPs enhance the mass transfer contribution to the total heat flux. This contribution accounts for 22-58% in CNPs, much higher than 12% in CNTs. With the temperature going up, the phonon scattering increases and the contribution from mass transfer to total heat flux decreases. Therefore, the CNP thermal conductivity decreases with rising temperature. This study sheds lights on nanoscale thermal/phonon engineering by utilization of CNTs and C60. PMID:26426675
NASA Astrophysics Data System (ADS)
Chen, Gang
In this talk, we will discuss different modes of heat conduction in nanostructures. Ballistic transport happens when phonon mean free path is longer than the characteristic size of the structure. We will discuss how we compute phonon mean free path distributions based on first-principles and measure the distributions with optical pump-probe techniques by exploring ballistic phonon transport processes. In superlattice structures, ballistic phonon transport across the whole thickness of the superlattices implies phase coherence. We observed this coherent transport in GaAs/AlAs superlattices with fixed periodic thickness and varying number of periods. Simulations show that although high frequency phonons are scattering by roughness, remaining long wavelength phonons maintain their phase and traverse the superlattices ballistically. Accessing the coherent heat conduction regime opens a new venue for phonon engineering. We show further that phonon heat conduction localization happens in GaAs/AlAs superlattice by placing ErAs nanodots at interfaces. This heat-conduction localization phenomenon is confirmed by nonequilibrium atomic Green's function simulation. These ballistic and localization effects can be exploited to improve thermoelectric energy conversion materials via reducing their thermal conductivity. In another opposite, we will discuss phonon hydrodynamic transport mode in graphene via first-principle simulations. In this mode, phonons drift with an average velocity under a temperature gradient, similar to fluid flow in a pipe. Conditions for observing such phonon hydrodynamic modes will be discussed. Finally, we will talk about the one-dimensional nature of heat conduction in polymer chains. Such 1D nature can lead to divergent thermal conductivity. Inspired by simulation, we have experimentally demonstrated high thermal conductivity in ultra-drawn polyethylene nanofibers and sheets. Work supported by DOE Office of Basic Energy Sciences under Award Number: DE-SC0001299/DE-FG02-09ER46577.
Note on heat conduction in liquid metals. A comparison of laminar and turbulent flow effects
NASA Astrophysics Data System (ADS)
Talmage, G.
1994-05-01
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.
Thermodynamically compatible conservation laws in the model of heat conducting radiating gas
NASA Astrophysics Data System (ADS)
Ivanov, M. Ya.
2011-01-01
Thermodynamic compatibility of the mass, momentum, and energy conservation laws that describe the motion of heat conducting gas in the presence of radiation heat exchange is considered. The study is based on the one-velocity two-component mathematical model of continuous compressible medium with the gas and radiation components. The work uses experimental data for radiation and other experimental data of modern physics.
NASA Technical Reports Server (NTRS)
Vanevenhoven, D. E.; Antoniak, D.
1989-01-01
The application of variable conductance heat pipe technology for achieving precise temperature control to + or - 0.1 C for a space-based laser diode transmitter is described. Heat pipe theory of operation and test data are presented along with a discussion of its applicability for NASA's Direct Detection Laser Transceiver (DDLT) program. This design for the DDLT transmitter features a reduction in space radiator size and up to 42 percent reduction in prime power requirements.
Development and implementation of sensitivity coefficient equations for heat conduction problems
Blackwell, B.F.; Cochran, R.J.; Dowding, K.J.
1997-12-15
Three different methods are discussed for computing the sensitivity of the temperature field to changes in material properties and initial-boundary condition parameters for heat conduction problems. The most general method is to derive sensitivity equations by differentiating the energy equation with respect to the parameter of interest and numerically solving the resulting sensitivity equations. An example problem in which there are twelve parameters of interest is presented and the resulting sensitivity equations are derived. Numerical results are presented for thermal conductivity and volumetric heat capacity sensitivity coefficients for heat conduction in a 2-D orthotropic body. The numerical results are compared with the analytical solution to demonstrate that the numerical method is second order accurate as the mesh is refined spatially.
NASA Astrophysics Data System (ADS)
Chandrasekaran, S. K.; Bieler, T. R.; Compton, C.; Hartung, W.; Wright, N. T.
2011-03-01
The thermal conductivity of superconducting niobium varies, in a yet unknown way, due to the processing history of the ingots and manufacturing processes during fabrication into cavities. Here, a theoretically based model is used to relate thermal conductivity to the metallurgy and processing history of niobium. Parameter groups are estimated using novel parameter estimation techniques on temperature and heat flux measurements on specimens cut from niobium ingots and having different processing histories. Results indicate a strong relation of one parameter group with RRR, and another with the temperature of heat treatment. After heat treating, a mild phonon peak was observed for specimens treated at 600° C for 6 hours, while a prominent phonon peak was observed in specimens treated at 750° C or 800° C for 2 hours. No change in conductivity in the electron dominated regime was observed, nor was there an effect due to tantalum at concentrations of less than 1322 ppm.
NASA Technical Reports Server (NTRS)
Tamma, Kumar K.; D'Costa, Joseph F.
1991-01-01
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.
Highly Stable and Conductive Microcapsules for Enhancement of Joule Heating Performance.
Zheng, Zhaoliang; Jin, Jidong; Xu, Guang-Kui; Zou, Jianli; Wais, Ulrike; Beckett, Alison; Heil, Tobias; Higgins, Sean; Guan, Lunhui; Wang, Ying; Shchukin, Dmitry
2016-04-26
Nanocarbons show great promise for establishing the next generation of Joule heating systems, but suffer from the limited maximum temperature due to precociously convective heat dissipation from electrothermal system to surrounding environment. Here we introduce a strategy to eliminate such convective heat transfer by inserting highly stable and conductive microcapsules into the electrothermal structures. The microcapsule is composed of encapsulated long-chain alkanes and graphene oxide/carbon nanotube hybrids as core and shell material, respectively. Multiform carbon nanotubes in the microspheres stabilize the capsule shell to resist volume-change-induced rupture during repeated heating/cooling process, and meanwhile enhance the thermal conductance of encapsulated alkanes which facilitates an expeditious heat exchange. The resulting microcapsules can be homogeneously incorporated in the nanocarbon-based electrothermal structures. At a dopant of 5%, the working temperature can be enhanced by 30% even at a low voltage and moderate temperature, which indicates a great value in daily household applications. Therefore, the stable and conductive microcapsule may serve as a versatile and valuable dopant for varieties of heat generation systems. PMID:27002594
Highly Stable and Conductive Microcapsules for Enhancement of Joule Heating Performance
2016-01-01
Nanocarbons show great promise for establishing the next generation of Joule heating systems, but suffer from the limited maximum temperature due to precociously convective heat dissipation from electrothermal system to surrounding environment. Here we introduce a strategy to eliminate such convective heat transfer by inserting highly stable and conductive microcapsules into the electrothermal structures. The microcapsule is composed of encapsulated long-chain alkanes and graphene oxide/carbon nanotube hybrids as core and shell material, respectively. Multiform carbon nanotubes in the microspheres stabilize the capsule shell to resist volume-change-induced rupture during repeated heating/cooling process, and meanwhile enhance the thermal conductance of encapsulated alkanes which facilitates an expeditious heat exchange. The resulting microcapsules can be homogeneously incorporated in the nanocarbon-based electrothermal structures. At a dopant of 5%, the working temperature can be enhanced by 30% even at a low voltage and moderate temperature, which indicates a great value in daily household applications. Therefore, the stable and conductive microcapsule may serve as a versatile and valuable dopant for varieties of heat generation systems. PMID:27002594
NASA Astrophysics Data System (ADS)
Mutabazi, Innocent; Yoshikawa, Harunori; Peixinho, Jorge; Kahouadji, Lyes
2013-11-01
Grtler vortices appear in a flow over a concave wall as a result of centrifugal instability [Saric, Annu. Rev. Fluid Mech. 26, 379 (1994)]. They may have a strong influence on heat transfer [Momayez et al., Int. J. heat Mass transfer 47, 3783 (2004)]. The purpose of this work is to model heat transfer by Grtler vortices using a weakly nonlinear analysis of Smith &-Haj- Hariri [Phys. Fluids A 5, 2815 (1993)]. We have investigated the coupling of the convective heat transfer by the stationary vortices with the heat conduction inside the solid wall. The finite thickness and thermal conductivity of the wall enter into the boundary conditions of the problem through the ratio ? of the wall thickness to the boundary layer thickness and through the ratio K of the thermal conductivities of the fluid and the wall. The parametric dependence Nu (? , K) of the Nusselt number is performed and it is shown that found the heat transfer is quite well modified by these two parameters. The local thermal stress can be estimated in order to analyze the effects on ageing of the wall material. The authors acknowledge the financial support of the french Agence Nationale de la Recherche (ANR), through the program ``Investissements d'Avenir'' (ANR-10-LABX-09-01), LabEx EMC3.
NASA Technical Reports Server (NTRS)
Enginer, J. E.; Luedke, E. E.; Wanous, D. J.
1976-01-01
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.
Evaluation of liquid behavior in a Variable Conductance Heat Pipe by neutron radiography
NASA Astrophysics Data System (ADS)
Sugimoto, K.; Asano, H.; Murakawa, H.; Takenaka, N.; Nagayasu, T.; Ipposhi, S.
2011-09-01
A Variable Conductance Heat Pipe (VCHP) is used as a cooling device for electrical equipments. The condensation area is passively controlled by the non-condensable gas volume in the VCHP depending on the heat load. The VCHP has often a bent pipe between the evaporation and condensation area. The heat pipe performance depends much on the bent pipe shape and configuration because a liquid plug is formed in the bent pipe and disturbs the refrigerant circulation. However, the mechanism has not been clarified well. The neutron radiography system at the JRR-3 in Japan Atomic Energy Agency (JAEA) was used to visualize the refrigerant behavior in the VCHP. Effects of the thin plate inserted in the pipe, refrigerant filling ratios and heat pipe configuration were examined on the heat pipe performance. The liquid plug was formed at the bend and caused to decrease the performance. It was confirmed that the thin plate insert was effective to disturb the liquid plug formation.
Plate fin heat exchanger model with axial conduction and variable properites
NASA Astrophysics Data System (ADS)
Hansen, Benjamin Jacob; White, Michael Joseph; Klebaner, Arkadiy
2012-06-01
Future superconduction radio frequency (SRF) cavities, as part of Project X at Fermilab,will be cooled to superfluid helium temperatures by a cryogenic distribution system supplying cold supercritical helium. To reduce vapor fraction during the final Joule Thomson (J-T) expansion into the superfluid helium cooling bath, counter-flow, plate-fin heat exchanger are an effective option. However, at liquid helium temperatures requires consideration of axial heat conduction along the direction of flow, in addition to variable fluid properties. Here we present a numberical model that includes the effects of axial guide design decisions on heat exhanger material choice and geometry. In addition, the J-T expansion process is modeled with the heat exchanger to analyze the effect of heat load and cryogenic supply parameters.
NASA Astrophysics Data System (ADS)
Lee-Elkin, Forest
2008-04-01
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 that portions of the scene are sparse in elevation which reduces the number of free variables and results in a system that is simultaneously solved for scatterer heights and autofocus parameters. The proposed method extends 2-pass interferometric synthetic aperture radar (IFSAR) methods to an arbitrary number of passes allowing the consideration of scattering from multiple height locations. A specific case from the proposed autofocus framework is solved and demonstrates autofocus and coherent multipass 3D estimation across the 8 passes of the "Gotcha Volumetric SAR Data Set" X-Band radar data.
NASA Astrophysics Data System (ADS)
Yang, Xu; Zhang, Yong; Yang, Chenghua; Xu, Lu; Wang, Qiang; Zhao, Yuan
2016-06-01
Conventional three dimensional (3D) ghost imaging measures range of target based on pulse fight time measurement method. Due to the limit of data acquisition system sampling rate, range resolution of the conventional 3D ghost imaging is usually low. In order to take off the effect of sampling rate to range resolution of 3D ghost imaging, a heterodyne 3D ghost imaging (HGI) system is presented in this study. The source of HGI is a continuous wave laser instead of pulse laser. Temporal correlation and spatial correlation of light are both utilized to obtain the range image of target. Through theory analysis and numerical simulations, it is demonstrated that HGI can obtain high range resolution image with low sampling rate.
Absolute stability in a collisionless electron-heat-conducting plasma in strong magnetic fields
NASA Astrophysics Data System (ADS)
de la Torre, A.; Duhau, S.
1989-02-01
The dispersion relation obtained from a linear analysis of the hydrodynamic system of equations of Duhau is used to study the behaviour of the fast and slow magnetosonic and entropy modes in an electron-heat-flux-conducting plasma. The evolution of the hydrodynamic modes different from the Alfvén mode are studied as the electron heat flux is increased from zero as well as around the borders of overstable regions, for any anisotropy condition of the ions. The development of the domains of mirror and electron-heat-flux overstabilities are established and the regions of absolute stability are shown
NASA Technical Reports Server (NTRS)
Brennan, P. J.; Groll, M.
1976-01-01
Tests results obtained with an ATS axial groove aluminum extrusion adapted for use as a cryogenic thermal diode and/or a variable conductance heat pipe are presented. Ethane at a nominal operating temperature of 185 C was used as working fluid. In addition to both active and passive gas control, diode designs utilizing gas blockage or liquid trap were investigated. Specific requirements and performance parameters such as transient behavior, reservoir sizes, shutdown energy, etc., were evaluated. Results are also presented for tests where the liquid trap was used as a secondary heat pipe to demonstrate thermal switching with simultaneous heat pipe operation and diode shutdown.
Electrical conductivity of carbonaceous chondrites and electric heating of meteorite parent bodies
NASA Technical Reports Server (NTRS)
Duba, AL
1987-01-01
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.
Mehdizadeh, Seyedeh Neda; Eskicioglu, Cigdem; Bobowski, Jake; Johnson, Thomas
2013-09-15
Microwave (2.45 GHz, 1200 W) and conventional heating (custom pressure vessel) pretreatments were applied to dewatered municipal waste sludge (18% total solids) using identical heating profiles that span a wide range of temperatures (80-160 °C). Fourteen lab-scale semi-continuous digesters were set up to optimize the energy (methane) output and sludge retention time (SRT) requirements of untreated (control) and thermally pretreated anaerobic digesters operated under mesophilic and thermophilic temperatures. Both pretreatment methods indicated that in the pretreatment range of 80-160 °C, temperature was a statistically significant factor (p-value < 0.05) for increasing solubilization of chemical oxygen demand and biopolymers (proteins, sugars, humic acids) of the waste sludge. However, the type of pretreatment method, i.e. microwave versus conventional heating, had no statistically significant effect (p-value >0.05) on sludge solubilization. With the exception of the control digesters at a 5-d SRT, all control and pretreated digesters achieved steady state at all three SRTs, corresponding to volumetric organic loading rates of 1.74-6.96 g chemical oxygen demand/L/d. At an SRT of 5 d, both mesophilic and thermophilic controls stopped producing biogas after 20 d of operation with total volatile fatty acids concentrations exceeding 1818 mg/L at pH <5.64 for mesophilic and 2853 mg/L at pH <7.02 for thermophilic controls, while the pretreated digesters continued producing biogas. Furthermore, relative (to control) organic removal efficiencies dramatically increased as SRT was shortened from 20 to 10 and then 5 d, indicating that the control digesters were challenged as the organic loading rate was increased. Energy analysis showed that, at an elevated temperature of 160 °C, the amount of methane recovered was not enough to compensate for the energy input. Among the digesters with positive net energy productions, control and pretreated digesters at 80 °C were more favorable at an SRT of 10 d. PMID:23866153
Combinatorial 3D Mechanical Metamaterials
NASA Astrophysics Data System (ADS)
Coulais, Corentin; Teomy, Eial; de Reus, Koen; Shokef, Yair; van Hecke, Martin
2015-03-01
We present a class of elastic structures which exhibit 3D-folding motion. Our structures consist of cubic lattices of anisotropic unit cells that can be tiled in a complex combinatorial fashion. We design and 3d-print this complex ordered mechanism, in which we combine elastic hinges and defects to tailor the mechanics of the material. Finally, we use this large design space to encode smart functionalities such as surface patterning and multistability.
NASA Astrophysics Data System (ADS)
Sarman, Sten; Laaksonen, Aatto
2010-01-01
The temperature dependence of the heat conductivity has been obtained for a liquid crystal model based on the Gay-Berne fluid, from the isotropic phase at high temperatures through the nematic phase to the smectic A phase at low temperatures. The ratio of the parallel and the perpendicular components of the heat conductivity is about 2.5:1 in the nematic phase, which is similar to that of real systems. Both Green-Kubo methods and nonequilibrium molecular dynamics methods have been applied and the results agree within in a relative error of a couple of percent, but the latter method is much more efficient.
Removal of numerical instability in the solution of an inverse heat conduction problem
NASA Astrophysics Data System (ADS)
Pourgholi, R.; Azizi, N.; Gasimov, Y. S.; Aliev, F.; Khalafi, H. K.
2009-06-01
In this paper, we consider an inverse heat conduction problem (IHCP). A set of temperature measurements at a single sensor location inside the heat conduction body is required. Using a transformation, the ill-posed IHCP becomes a Cauchy problem. Since the solution of Cauchy problem, exists and is unique but not always stable, the ill-posed problem is closely approximated by a well-posed problem. For this new well-posed problem, the existence, uniqueness, and stability of the solution are proved.
Photonic heat conduction in Josephson-coupled Bardeen-Cooper-Schrieffer superconductors
NASA Astrophysics Data System (ADS)
Bosisio, R.; Solinas, P.; Braggio, A.; Giazotto, F.
2016-04-01
We investigate the photon-mediated heat flow between two Josephson-coupled Bardeen-Cooper-Schrieffer (BCS) superconductors. We demonstrate that in standard low temperature experiments involving temperature-biased superconducting quantum interference devices (SQUIDs), this radiative contribution is negligible if compared to the direct galvanic one, but it largely exceeds the heat exchanged between electrons and the lattice phonons. The corresponding thermal conductance is found to be several orders of magnitude smaller, for real experiments setup parameters, than the universal quantum of thermal conductance, κ0(T ) =π kB2T /6 ℏ .
Design and analysis of a cryogenic variable conductance axial grooved heat pipe
NASA Technical Reports Server (NTRS)
1976-01-01
An investigation to adapt axial grooved designs to the gammit of heat pipe thermal control techniques, with particular emphasis on those suited for cryogenic applications was conducted. In addition to considering both active and passive gas control, diode designs utilizing liquid or gas blockage, or a liquid trap, are evaluated. The use of the liquid trap as a secondary heat pipe for forward mode operation during diode shutdown is also studied. This latter function is basically that of a thermal switch. Finally, a system capable of hybrid functions consisting of gas-controlled variable conductance and liquid trap diode shutdown or thermal switching is defined.
NASA Technical Reports Server (NTRS)
Sonett, C. P.; Duba, A.
1975-01-01
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.
NASA Astrophysics Data System (ADS)
Wang, Cheng-An; Sadat, Hamou; Tan, Jian-Yu
2016-01-01
A diffuse approximation meshless method (DAM) is employed as a means of solving the coupled radiative and conductive heat transfer problems in semi-transparent refractive index media contained in 1D and 2D geometries. The meshless approach for radiative transfer is based on the discrete ordinates equation. Cases of combined conduction- radiation are presented, including plane parallel slab, square enclosure, and semicircular enclosure with an inner circle. The influence of the refractive index on the temperature distributions and heat fluxes is investigated. Results obtained using the proposed meshless method are compared with those reported in the literature to demonstrate the flexibility and accuracy of the method.
NASA Astrophysics Data System (ADS)
Khokhlov, V.; Korzun, I.; Dokutovich, V.; Filatov, E.
2011-03-01
This article reports the experimental data on the key thermal properties of some molten salt eutectics containing lithium, sodium, potassium, zirconium, and thorium fluorides. Their melting points, enthalpies of melting, heat capacities were measured using STA 449C Jupiter® synchronous thermal analyzer while the thermal conductivity was determined by the steady-state method of coaxial cylinders. The validity of the empirical equations proposed for estimating the isobaric heat capacity ( c p) and thermal conductivity ( λ) of the possible MSR coolants and fuels is discussed.
NASA Astrophysics Data System (ADS)
Zhang, Liqiang; Reilly, Carl; Li, Luoxing; Cockcroft, Steve; Yao, Lu
2014-07-01
The interfacial heat transfer coefficient (IHTC) is required for the accurate simulation of heat transfer in castings especially for near net-shape processes. The large number of factors influencing heat transfer renders quantification by theoretical means a challenge. Likewise experimental methods applied directly to temperature data collected from castings are also a challenge to interpret because of the transient nature of many casting processes. Inverse methods offer a solution and have been applied successfully to predict the IHTC in many cases. However, most inverse approaches thus far focus on use of in-mold temperature data, which may be a challenge to obtain in cases where the molds are water-cooled. Methods based on temperature data from the casting have the potential to be used however; the latent heat released during the solidification of the molten metal complicates the associated IHTC calculations. Furthermore, there are limits on the maximum distance the thermocouples can be placed from the interface under analysis. An inverse conduction based method have been developed, verified and applied successfully to temperature data collected from within an aluminum casting in proximity to the mold. A modified specific heat method was used to account for latent heat evolution in which the rate of change of fraction solid with temperature was held constant. An analysis conducted with the inverse model suggests that the thermocouples must be placed no more than 2 mm from the interface. The IHTC values calculated for an aluminum alloy casting were shown to vary from 1,200 to 6,200 Wm-2 K-1. Additionally, the characteristics of the time-varying IHTC have also been discussed.
Gas heat conduction in evacuated flat-plate solar collectors: Analysis and reduction
Beikircher, T.; Spirkl, W.; Benz, N.
1995-08-01
In stationary heat-loss experiments, the thermal losses by gas conduction of an evacuated flat-plate solar collector (EFPC) were experimentally determined for different values of interior gas pressure. The experiments were carried out with air and argon in the pressure range from 10{sup {minus}3} to 10{sup 4} Pa. For air, loss reduction sets in at 100 Pa, whereas at 0.1 Pa heat conduction is almost completely suppressed. Using argon as filling gas, gas conduction is reduced by 30% (compared to air) at moderate interior pressures of 1,000 Pa. With decreasing pressure this reduction is even greater (50% reduction at 10 Pa). A theory was developed to calculate thermal losses by gas conduction in an EFPC: Fourier`s stationary heat conduction equation was solved numerically (method of finite differences) for the special geometry of the collector. From kinetic gas theory a formula for the pressure dependency of the thermal conductivity was derived covering the entire pressure range. The theory has been validated experimentally for the gases air and argon. Calculations for krypton and xenon show a possible gas conduction loss reduction of 60--70% and 75--85% (with respect to air, depending on gas pressure), corresponding to a reduction of the overall collector losses of up to 40%.
3D effects in dry laser cleaning
NASA Astrophysics Data System (ADS)
Luk'yanchuk, Boris S.; Huang, Sumei; Hong, Ming Hui
2002-09-01
For 10 previous years dry laser cleaning has been analyzed in the frame of 1D model with homogeneous surface heating. This model gave qualitative description of the process and was sufficient for initial studies. Nevertheless further examinations show that 1D model is in one-two order magnitudes discrepancy with experiment. The problem is that the particle on the surface produces non-homogeneous distribution of laser intensity. For example, a small transparent particle can work as a near-field lens. This produces nonstationary 3D distribution of temperature and nonstationary 3D thermal deformations of the surface. 3D model is qualitatively different from the 1D model (the latest does not permit the inward motion of the surface). In some region of parameters 3D model predicts a result close to the experimental one (for small particles, typically smaller than 1 micrometers ). With higher particle size intensity under the surface becomes so strong that the particle is removed by the flux of evaporated material.
LDEF (Prelaunch), AO076 : Cascade Variable-Conductance Heat Pipe, Tray F09
NASA Technical Reports Server (NTRS)
1983-01-01
LDEF (Prelaunch), AO076 : Cascade Variable-Conductance Heat Pipe, Tray F09 EL-1994-00302 LDEF (Prelaunch), AO076 : Cascade Variable-Conductance Heat Pipe, Tray F09 The prelaunch photograph was taken in SAEF II at KSC prior to installation of the Cascade Variable Conductance Heat Pipe Experiment (CVCHPE) on the LDEF. The Cascade Variable Conductance Heat Pipe Experiment (CVCHPE) occupies a 6 inch deep LDEF peripheral experiment tray and consist of two series connected variable conductance heatpipes, a black chrome solar collector panel and a silvered TEFLON® radiator panel, a power source to support six thermistor-type temperature monitoring sensors and actuations of two valves. Fiberglass standoffs and internal insulation blankets thermally isolated the experiment from the experiment tray and the LDEF interior. The outside of the CVCHPE, except the collector and radiator panels, was covered with an aluminumized Kapton multilayer insulation (MLI) blanket with an outer layer of 0.076 mm thick Kapton. The two patches of thin film materials, part of Experiment S1001 by NASA GSFC, were attached to the cover of the external thermal blanket with Kapton tape. The experiment was assembled and mounted in the experiment tray with non-magnetic stainless steel fasteners.
Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data
Waite, W.F.; Gilbert, L.Y.; Winters, W.J.; Mason, D.H.
2006-01-01
Thermal diffusivity and specific heat can be estimated from thermal conductivity measurements made using a standard needle probe and a suitably high data acquisition rate. Thermal properties are calculated from the measured temperature change in a sample subjected to heating by a needle probe. Accurate thermal conductivity measurements are obtained from a linear fit to many tens or hundreds of temperature change data points. In contrast, thermal diffusivity calculations require a nonlinear fit to the measured temperature change occurring in the first few tenths of a second of the measurement, resulting in a lower accuracy than that obtained for thermal conductivity. Specific heat is calculated from the ratio of thermal conductivity to diffusivity, and thus can have an uncertainty no better than that of the diffusivity estimate. Our thermal conductivity measurements of ice Ih and of tetrahydrofuran (THF) hydrate, made using a 1.6 mm outer diameter needle probe and a data acquisition rate of 18.2 pointss, agree with published results. Our thermal diffusivity and specific heat results reproduce published results within 25% for ice Ih and 3% for THF hydrate. ?? 2006 American Institute of Physics.
Liu, Fa-Qian; Zhu, Kai; Li, Tao; Xu, Tao
2014-04-25
It has long been taken for granted that electron transport in liquid-electrolyte-based dye-sensitized solar cells (DSSCs) undergoes an ambipolar diffusive transport due to the strong coupling between electrons in the photoanode and the nearby mobile cations in liquid electrolyte, which, therefore, screens off any electric field in the photoanodes and consequently eliminates the possibility for drift transport. In this work, we demonstrate the existence of drift transport in liquid electrolyte-based DSSCs using a thin Al_{2}O_{3}-sheathed 3-dimentional (3-D) fluorinated tin oxide (FTO), as photoanodes. The electron diffusion rate in such 3-D TCO based DSSC exhibits a striking enhancement to the value of ~10^{–2} cm^{2}/s, about 10^{4} times faster than that of the TiO_{2} nanoparticle-based DSSCs. The electron diffusion coefficient is independent of the photoelectron density, while intensity modulated photocurrent spectroscopy (IMPS) suggests that the time constants of electron transport exhibit a linear dependence on the bias voltage, a strong indication of drift transport behavior in this 3-D FTO hollow nanobeads-based DSSC, despite the use of liquid I^{–}/I_{3}^{–} electrolyte.
A peridynamic formulation for transient heat conduction in bodies with evolving discontinuities
NASA Astrophysics Data System (ADS)
Bobaru, Florin; Duangpanya, Monchai
2012-04-01
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.
LASTRAC.3d: Transition Prediction in 3D Boundary Layers
NASA Technical Reports Server (NTRS)
Chang, Chau-Lyan
2004-01-01
Langley Stability and Transition Analysis Code (LASTRAC) is a general-purpose, physics-based transition prediction code released by NASA for laminar flow control studies and transition research. This paper describes the LASTRAC extension to general three-dimensional (3D) boundary layers such as finite swept wings, cones, or bodies at an angle of attack. The stability problem is formulated by using a body-fitted nonorthogonal curvilinear coordinate system constructed on the body surface. The nonorthogonal coordinate system offers a variety of marching paths and spanwise waveforms. In the extreme case of an infinite swept wing boundary layer, marching with a nonorthogonal coordinate produces identical solutions to those obtained with an orthogonal coordinate system using the earlier release of LASTRAC. Several methods to formulate the 3D parabolized stability equations (PSE) are discussed. A surface-marching procedure akin to that for 3D boundary layer equations may be used to solve the 3D parabolized disturbance equations. On the other hand, the local line-marching PSE method, formulated as an easy extension from its 2D counterpart and capable of handling the spanwise mean flow and disturbance variation, offers an alternative. A linear stability theory or parabolized stability equations based N-factor analysis carried out along the streamline direction with a fixed wavelength and downstream-varying spanwise direction constitutes an efficient engineering approach to study instability wave evolution in a 3D boundary layer. The surface-marching PSE method enables a consistent treatment of the disturbance evolution along both streamwise and spanwise directions but requires more stringent initial conditions. Both PSE methods and the traditional LST approach are implemented in the LASTRAC.3d code. Several test cases for tapered or finite swept wings and cones at an angle of attack are discussed.
NASA Astrophysics Data System (ADS)
Dima, M.; Farisato, G.; Bergomi, M.; Viotto, V.; Magrin, D.; Greggio, D.; Farinato, J.; Marafatto, L.; Ragazzoni, R.; Piazza, D.
2014-08-01
In the last few years 3D printing is getting more and more popular and used in many fields going from manufacturing to industrial design, architecture, medical support and aerospace. 3D printing is an evolution of bi-dimensional printing, which allows to obtain a solid object from a 3D model, realized with a 3D modelling software. The final product is obtained using an additive process, in which successive layers of material are laid down one over the other. A 3D printer allows to realize, in a simple way, very complex shapes, which would be quite difficult to be produced with dedicated conventional facilities. Thanks to the fact that the 3D printing is obtained superposing one layer to the others, it doesn't need any particular work flow and it is sufficient to simply draw the model and send it to print. Many different kinds of 3D printers exist based on the technology and material used for layer deposition. A common material used by the toner is ABS plastics, which is a light and rigid thermoplastic polymer, whose peculiar mechanical properties make it diffusely used in several fields, like pipes production and cars interiors manufacturing. I used this technology to create a 1:1 scale model of the telescope which is the hardware core of the space small mission CHEOPS (CHaracterising ExOPlanets Satellite) by ESA, which aims to characterize EXOplanets via transits observations. The telescope has a Ritchey-Chrétien configuration with a 30cm aperture and the launch is foreseen in 2017. In this paper, I present the different phases for the realization of such a model, focusing onto pros and cons of this kind of technology. For example, because of the finite printable volume (10×10×12 inches in the x, y and z directions respectively), it has been necessary to split the largest parts of the instrument in smaller components to be then reassembled and post-processed. A further issue is the resolution of the printed material, which is expressed in terms of layers thickness, in the Z direction, and in drop-per-inch, in X and Y directions. 3D printing is also an easy and quick production technique, which can become useful in the ad-hoc realization of mechanical components for optical setups to be used in a laboratory for new concept studies and validation, reducing the manufacturing time. With this technique, indeed, it is possible to realize in few hours custom-made mechanical parts, without any specific knowledge and expertise in tool machinery, as long as the resolution and size are compliant with the requirements.
Scramjet combustor analysis with the SHIP3D PNS code
NASA Technical Reports Server (NTRS)
Kamath, Pradep S.; Mao, Marlon M.; Mcclinton, Charles R.
1991-01-01
The SHIP3D PNS code has the capability to perform 3D computations of scramjet combustors efficiently at flight Mach numbers of 10 and above, where the combustor flow is mostly supersonic. The fast solution times make skin friction and heat transfer calculations feasible and permit the utilization of multiequation turbulence models. Application of this relatively uncomplicated methodology to compute scramjet combustor flow fields and heat transfer is presented with particular emphasis on the treatment of ramp fuel injectors.
Rice, Jarrett A.; Pokorny, Richard; Schweiger, Michael J.; Hrma, Pavel R.
2014-06-01
The heat conductivity ({lambda}) and the thermal diffusivity (a) of reacting glass batch, or melter feed, control the heat flux into and within the cold cap, a layer of reacting material floating on the pool of molten glass in an all-electric continuous waste glass melter. After previously estimating {lambda} of melter feed at temperatures up to 680 deg C, we focus in this work on the {lambda}(T) function at T > 680 deg C, at which the feed material becomes foamy. We used a customized experimental setup consisting of a large cylindrical crucible with an assembly of thermocouples, which monitored the evolution of the temperature field while the crucible with feed was heated at a constant rate from room temperature up to 1100°C. Approximating measured temperature profiles by polynomial functions, we used the heat transfer equation to estimate the {lambda}(T) approximation function, which we subsequently optimized using the finite-volume method combined with least-squares analysis. The heat conductivity increased as the temperature increased until the feed began to expand into foam, at which point the conductivity dropped. It began to increase again as the foam turned into a bubble-free glass melt. We discuss the implications of this behavior for the mathematical modeling of the cold cap.
Exploration of the influence of heat conduction on the temperature distribution in turbine blades
Eckert, E.R.G.; Simon, T.W.; Graskow, B.R.
1997-07-01
The present study aims to support the designer in the task of maximizing film cooling effectiveness of turbine blades; this is accomplished by predicting the temperature field in the blade wall as influenced by heat convection to and from the blade wall and conduction of heat within the blade wall. This study provides a general overview and some insight. It should also be useful for preliminary design studies and can serve as a starting point to a more extensive analysis. The temperature variation along a thin blade wall is described by a one-dimensional heat conduction equation with the solution presenting the dimensionless wall temperature field as a function of a Biot number, provided that the local variation of the convective heat transfer coefficient is prescribed. The thus determined wall temperature distribution exhibits two-dimensional ridges. It is of special interest to find to what degree these ridges are reduced by heat conduction in the wall. The answer to this is presented by simple expressions provided that the shapes of the ridges are approximated by sine curves for groups of ridges (as occurs in film cooling downstream of the cooling hole) or by Gaussian functions for single ridges (as occurs at the leading edge of the blade or at the streamwise location of boundary layer transition).
YouDash3D: exploring stereoscopic 3D gaming for 3D movie theaters
NASA Astrophysics Data System (ADS)
Schild, Jonas; Seele, Sven; Masuch, Maic
2012-03-01
Along with the success of the digitally revived stereoscopic cinema, events beyond 3D movies become attractive for movie theater operators, i.e. interactive 3D games. In this paper, we present a case that explores possible challenges and solutions for interactive 3D games to be played by a movie theater audience. We analyze the setting and showcase current issues related to lighting and interaction. Our second focus is to provide gameplay mechanics that make special use of stereoscopy, especially depth-based game design. Based on these results, we present YouDash3D, a game prototype that explores public stereoscopic gameplay in a reduced kiosk setup. It features live 3D HD video stream of a professional stereo camera rig rendered in a real-time game scene. We use the effect to place the stereoscopic effigies of players into the digital game. The game showcases how stereoscopic vision can provide for a novel depth-based game mechanic. Projected trigger zones and distributed clusters of the audience video allow for easy adaptation to larger audiences and 3D movie theater gaming.
Improving 3D resist profile compact modeling by exploiting 3D resist physical mechanisms
NASA Astrophysics Data System (ADS)
Fan, Yongfa; Wu, Cheng-En R.; Ren, Qian; Song, Hua; Schmoeller, Thomas
2014-03-01
3D Resist profile aware OPC has becoming increasingly important to address hot spots generated at etch processes due to the mass occurrence of non-ideal resist profile in 28nm technology node and beyond. It is therefore critical to build compact models capable of 3D simulation for OPC applications. A straightforward and simple approach is to build individual 2D models at different image depths either based on actual wafer measurement data or virtual simulation data from rigorous lithography simulators. Individual models at interested heights can be used by downstream OPC/LRC tools to account for 3D resist profile effects. However, the relevant image depths need be predetermined due to the discontinuous nature of the methodology itself. Furthermore, the physical commonality among the individual 2D models may deviate from each other as well during the separate calibration processes. To overcome the drawbacks, efforts are made in this paper to compute the whole bulk image using Hopkins equation in one shot. The bulk image is then used to build 3D resist models. This approach also opens the feasibility of including resist interface effects (for example, top or bottom out-diffusion), which are important to resist profile formation, into a compact 3D resist model. The interface effects calculations are merged into the bulk image Hopkins equation. Simulation experiments are conducted to demonstrate that resist profile heavily rely on interface conditions. Our experimental results show that those interface effects can be accurately simulated with reference to rigorous simulation results. In modeling reality, such a 3D resist model can be calibrated with data from discrete image planes but can be used at arbitrary interpolated planes. One obvious advantage of this 3D resist model approach is that the 3D model is more physically represented by a common set of resist parameters (in contrast to the individual model approach) for 3D resist profile simulation. A full model calibration test is conducted on a virtual lithography process. It is demonstrated that 3D resist profile of the process can be precisely captured by this method. It is shown that the resist model can be carried to a different lithography process with same resist setup but a different illumination source without model any accuracy degradation. In an additional test, the model is used to demonstrate the capability of resist 3D profile correction by ILT.
Behavior of entropy in non-classical heat conduction of incompressible media
NASA Astrophysics Data System (ADS)
Serdyukov, Sergey I.; Voskresenskii, Nikolai M.
2010-10-01
The behavior of entropy of a model isolated system in which there is non-classical heat conduction is considered. Within the thermodynamic formalism developed, expressions are obtained for the entropy flux and source and also for the total entropy of the isolated system. The approach proposed leads to a strictly monotonic dependence of the total entropy on time for the model system considered.
TOPAZ - a finite element heat conduction code for analyzing 2-D solids
Shapiro, A.B.
1984-03-01
TOPAZ is a two-dimensional implicit finite element computer code for heat conduction analysis. This report provides a user's manual for TOPAZ and a description of the numerical algorithms used. Sample problems with analytical solutions are presented. TOPAZ has been implemented on the CRAY and VAX computers.
An analytical solution to the one-dimensional heat conduction-convection equation in soil
Technology Transfer Automated Retrieval System (TEKTRAN)
Heat transfer in soil occurs by conduction and convection. Infiltrating water affects soil temperature distributions, and measuring soil temperature distributions below infiltrating water can provide a signal for the flux of water. In earlier work a sine wave function (hereinafter referred to as the...
Numerical study of conductive heat losses from a magmatic source at Phlegraean Fields
NASA Astrophysics Data System (ADS)
Di Maio, Rosa; Piegari, Ester; Mancini, Cecilia; Scandone, R.
2015-01-01
The thermal evolution of the Phlegraean magmatic system (southern Italy) is studied by analyzing the influence of the thermal property variations on the solution of the heat conduction equation. The aim of this paper is to verify if appropriate choices of thermal parameters can reproduce, at least to greater depths, the high temperatures measured in the geothermal wells, drilled inside the caldera, under the assumption of heat loss from a magma chamber by conduction. Since the main purpose is to verify the plausibility of such an assumption, rather simple models of the magmatic system are adopted and only major volcanic events (i.e., the Campanian Ignimbrite and the Neapolitan Yellow Tuff eruptions) are considered. The results of the simulated two-dimensional model scenarios show that by assuming an extended source region, whose emplacement time is longer than 40 ka, heat conduction mechanisms can provide temperatures as high as those measured at depths deeper than about 2000 m. On the other hand, the 1D simulations show that appropriate choices for the thermal conductivity depth profiles can reproduce the observed temperatures at depths deeper than about 1000 m. These findings question the apparent consensus that convection is the only dominant form of heat transfer at Phlegraean Fields and might motivate new research for reconstructing the thermal evolution of the Phlegraean magmatic system.
Heat Flow, Thermal Conductivity, and the Plausibility of the White Mars Hypothesis
NASA Technical Reports Server (NTRS)
Urquhart, M. L.; Gulick, V. C.
2002-01-01
Due to the low thermal conductivity of CO2 ice and clathrate vs. water ice, we find that liquid water reservoirs would not be confined to the deep subsurface as predicted by the controversial White Mars model, even assuming low global heat flow. Additional information is contained in the original extended abstract.
Enhancement and reduction of one-dimensional heat conduction with correlated mass disorder
NASA Astrophysics Data System (ADS)
Ong, Zhun-Yong; Zhang, Gang
2014-10-01
Short-range order in strongly disordered structures plays an important role in their heat conduction property. Using numerical and analytical methods, we show that short-range spatial correlation (with a correlation length of Λm) in the mass distribution of the one-dimensional (1D) alloylike random binary lattice leads to a dramatic enhancement of the high-frequency phonon transmittance but also increases the low-frequency phonon opacity. High-frequency semiextended states are formed while low-frequency modes become more localized. This results in ballistic heat conduction at finite lengths but also paradoxically higher thermal resistance that scales as √{Λm} in the L →∞ limit. We identify an emergent crossover length (Lc) below which the onset of thermal transparency appears. The crossover length is linearly dependent on but is two orders of magnitude larger than Λm. Our results suggest that the phonon transmittance spectrum and heat conduction in a disordered 1D lattice can be controlled via statistical clustering of the constituent component atoms into domains. They also imply that the detection of ballistic heat conduction in disordered 1D structures may be a signature of the intrinsic mass correlation at a much smaller length scale.
Heat transfer in a gray tube with forced convection, internal radiation and axial wall conduction
NASA Astrophysics Data System (ADS)
Chung, B. T. F.; Thompson, J. E.
1983-11-01
A method of successive approximations is employed to solve the problem of heat transfer to a transparent gas flowing through a radiating-conducting tube with turbulent forced convection between the tube wall and the gas, and with energy generation in the wall. Emphasis is given to the effect of emissivity of the wall to the tube and gas temperature profiles.
ERIC Educational Resources Information Center
Mendez, Sergio; AungYong, Lisa
2014-01-01
To help students make the connection between the concepts of heat conduction and convection to real-world phenomenon, we developed a combined experimental and computational module that can be incorporated into lecture or lab courses. The experimental system we present requires materials and apparatus that are readily accessible, and the procedure
ERIC Educational Resources Information Center
Mendez, Sergio; AungYong, Lisa
2014-01-01
To help students make the connection between the concepts of heat conduction and convection to real-world phenomenon, we developed a combined experimental and computational module that can be incorporated into lecture or lab courses. The experimental system we present requires materials and apparatus that are readily accessible, and the procedure…
NASA Astrophysics Data System (ADS)
Wang, Tao
2015-12-01
We establish an initial-boundary value problem for the compressible magnetohydrodynamic equations in one space dimension with large initial data when the heat conductivity is some positive power of the temperature. We prove that as the shear viscosity vanishes, global weak solutions convergence to a solution of the original equations with zero shear viscosity.
Effect of heat treatment time on microstructure and electrical conductivity in LATP glass ceramics
Sonigra, Dhiren E-mail: ajit.kulkarni@iitb.ac.in; Soman, Swati E-mail: ajit.kulkarni@iitb.ac.in; Kulkarni, Ajit R. E-mail: ajit.kulkarni@iitb.ac.in
2014-04-24
Glass-ceramic is prepared by heat treatment of melt quenched 14Li{sub 2}O−9Al{sub 2}O{sub 3}−38TiO{sub 2}−39P{sub 2}O{sub 5} glass in the vicinity of crystallization temperature. Growth of ceramic phase is controlled by tuning heat treatment time at fixed temperature. Ceramic phase was identified to be LiTi{sub 2}(PO{sub 4}){sub 3} from X Ray Diffraction analysis. Microstructural evolution of this phase with hold time was observed under high resolution Scanning Electron Microscope. DC conductivity is observed to increase by 4-5 orders of magnitude in this glass-ceramic compared to parent glass. However, formation of pores and cracks with very large heat treatment time seem to hinder further increase of conductivity.
Thermal conductivity and diffusivity of biomaterials measured with self-heated thermistors
NASA Astrophysics Data System (ADS)
Valvano, J. W.; Cochran, J. R.; Diller, K. R.
1985-05-01
This paper presents an experimental method to measure the thermal conductivity and thermal diffusivity of biomaterials. Self-heated thermistor probes, inserted into the tissue of interest, are used to deliver heat as well as to monitor the rate of heat removal. An empirical calibration procedure allows accurate thermal-property measurements over a wide range of tissue temperatures. Operation of the instrument in three media with known thermal properties shows the uncertainty of measurements to be about 2%. The reproducibility is 0.5% for the thermal-conductivity measurements and 2% for the thermal-diffusivity measurements. Thermal properties were measured in dog, pig, rabbit, and human tissues. The tissues included kidney, spleen, liver, brain, heart, lung, pancreas, colon cancer, and breast cancer. Thermal properties were measured for 65 separate tissue samples at 3, 10, 17, 23, 30, 37, and 45°C. The results show that the temperature coefficient of biomaterials approximates that of water.
Heat Conduction of Walls with a Monotone Temperature Change. Asymptotics and Quasi-Stationarity
NASA Astrophysics Data System (ADS)
Korshunov, O. V.
2014-07-01
Systematizing the partial solutions of the nonstationarity heat conduction problem of a flat wall in comparison with the general asymptotic solution of this problem, we have found the transverse temperature distributions with any monotone change in the ambient conditions and elucidated the heat conduction properties of the wall under these conditions. The asymptotic solution is given by semiconvergent series and definite integrals and has been investigated for power time dependences with an exponent of 0-2, which has enabled us to justify the concept of quasi-stationarity of the thermal parameters of the wall and obtain asymptotic errors and corrections defining the deviations of these parameters from their stationary values. The features of the average heat flows most resistant to thermal disturbances as to both time and amplitude have been considered.
Temperature dependence of the conductivity, thermopower, and heat capacity of TICoS2
NASA Astrophysics Data System (ADS)
Kerimova, E. M.; Mustafaeva, S. N.; Aldjanov, M. A.; Jabbarly, A. I.
2004-04-01
The temperature dependence of the conductivity and thermopower of TlCoS2 is studied over a wide range of temperatures (77-400 K). It is found that TlCoS2 is characterized by p-type conductivity in the temperature interval 77-225 K and that an inversion of the sign of the thermopower occurs at 225 K. The heat capacity of the ferromagnetic compound TlCoS2 is also measured in the temperature interval 55-300 K. It is shown that the behavior of the magnetic part of the heat capacity of TlCoS2 is typical of a quasi-low-dimensional magnet. The experimental data on the temperature dependence of the heat capacity are used to calculate the thermodynamic parameters of TlCoS2: the changes in entropy and enthalpy.
NASA Technical Reports Server (NTRS)
Tamma, Kumar K.; Railkar, Sudhir B.
1988-01-01
The present paper describes the applicability of hybrid transfinite element modeling/analysis formulations for nonlinear heat conduction problems involving phase change. The methodology is based on application of transform approaches and classical Galerkin schemes with finite element formulations to maintain the modeling versatility and numerical features for computational analysis. In addition, in conjunction with the above, the effects due to latent heat are modeled using enthalpy formulations to enable a physically realistic approximation to be dealt computationally for materials exhibiting phase change within a narrow band of temperatures. Pertinent details of the approach and computational scheme adapted are described in technical detail. Numerical test cases of comparative nature are presented to demonstrate the applicability of the proposed formulations for numerical modeling/analysis of nonlinear heat conduction problems involving phase change.
NASA Technical Reports Server (NTRS)
2002-01-01
In 1999, Genex submitted a proposal to Stennis Space Center for a volumetric 3-D display technique that would provide multiple users with a 360-degree perspective to simultaneously view and analyze 3-D data. The futuristic capabilities of the VolumeViewer(R) have offered tremendous benefits to commercial users in the fields of medicine and surgery, air traffic control, pilot training and education, computer-aided design/computer-aided manufacturing, and military/battlefield management. The technology has also helped NASA to better analyze and assess the various data collected by its satellite and spacecraft sensors. Genex capitalized on its success with Stennis by introducing two separate products to the commercial market that incorporate key elements of the 3-D display technology designed under an SBIR contract. The company Rainbow 3D(R) imaging camera is a novel, three-dimensional surface profile measurement system that can obtain a full-frame 3-D image in less than 1 second. The third product is the 360-degree OmniEye(R) video system. Ideal for intrusion detection, surveillance, and situation management, this unique camera system offers a continuous, panoramic view of a scene in real time.
NASA Astrophysics Data System (ADS)
Grądziel, sławomir
2011-12-01
The following paper presents the method for solving one-dimensional inverse boundary heat conduction problems. The method is used to estimate the unknown thermal boundary condition on inner surface of a thick-walled Y-branch. Solution is based on measured temperature transients at two points inside the element's wall thickness. Y-branch is installed in a fresh steam pipeline in a power plant in Poland. Determination of an unknown boundary condition allows for the calculation of transient temperature distribution in the whole element. Next, stresses caused by non-uniform transient temperature distribution and by steam pressure inside a Y-branch are calculated using the finite element method. The proposed algorithm can be used for thermal-strength state monitoring in similar elements, when it is not possible to determine a 3-D thermal boundary condition. The calculated temperature and stress transients can be used for the calculation of element durability. More accurate temperature and stress monitoring will contribute to a substantial decrease of maximal stresses that occur during transient start-up and shut-down processes.
3D Multifunctional Ablative Thermal Protection System
NASA Technical Reports Server (NTRS)
Feldman, Jay; Venkatapathy, Ethiraj; Wilkinson, Curt; Mercer, Ken
2015-01-01
NASA is developing the Orion spacecraft to carry astronauts farther into the solar system than ever before, with human exploration of Mars as its ultimate goal. One of the technologies required to enable this advanced, Apollo-shaped capsule is a 3-dimensional quartz fiber composite for the vehicle's compression pad. During its mission, the compression pad serves first as a structural component and later as an ablative heat shield, partially consumed on Earth re-entry. This presentation will summarize the development of a new 3D quartz cyanate ester composite material, 3-Dimensional Multifunctional Ablative Thermal Protection System (3D-MAT), designed to meet the mission requirements for the Orion compression pad. Manufacturing development, aerothermal (arc-jet) testing, structural performance, and the overall status of material development for the 2018 EM-1 flight test will be discussed.