Comparison of vibrational conductivity and radiative energy transfer methods
Le Bot, A.
2005-05-01
This paper is concerned with the comparison of two methods well suited for the prediction of the wideband response of built-up structures subjected to high-frequency vibrational excitation. The first method is sometimes called the vibrational conductivity method and the second one is rather known as the radiosity method in the field of acoustics, or the radiative energy transfer method. Both are based on quite similar physical assumptions i.e. uncorrelated sources, mean response and high-frequency excitation. Both are based on analogies with some equations encountered in the field of heat transfer. However these models do not lead to similar results. This paper compares the two methods. Some numerical simulations on a pair of plates joined along one edge are provided to illustrate the discussion.
Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface
Gruenewald, Marco
2015-02-11
We investigate the prototypical hybrid interface formed between PTCDA and conductive n-doped ZnO films by means of complementary optical and electronic spectroscopic techniques. We demonstrate that shallow donors in the vicinity of the ZnO surface cause an integer charge transfer to PTCDA, which is clearly restricted to the first monolayer. By means of DFT calculations, we show that the experimental signatures of the anionic PTCDA species can be understood in terms of strong hybridization with localized states (the shallow donors) in the substrate and charge back-donation, resulting in an effectively integer charge transfer across the interface. Charge transfer is thus not merely a question of locating the Fermi level above the PTCDA electron-transport level but requires rather an atomistic understanding of the interfacial interactions. The study reveals that defect sites and dopants can have a significant influence on the specifics of interfacial coupling and thus on carrier injection or extraction.
Evaluation of heat transfer in acupuncture needles: convection and conduction approaches.
Tzou, Chieh-Han John; Yang, Tzyy-Yih; Chung, Ya-Chien
2015-04-01
Originating in ancient China, acupuncture using needles has been developed for thousands of years and has received attention for its reported medical remedies, such as pain relief and chronic disease treatment. Heat transfer through the needles, which might have effects on the biomechanism of acupuncture, providing a stimulus and regulating homeostasis, has never been studied. This article analyzes the significance of heat transfer through needles via convection and conduction, approached by means of computational analysis. The needle is a cylindrical body, and an axis symmetrical steady-state heat-transfer model that viscosity and static pressure was not applied. This article evaluates heat transfer via acupuncture needles by using five metal materials: silver, copper, brass, iron, and stainless steel. A silver needle of the type extensively applied in acupuncture can dissipate more than seven times as much heat as a stainless steel needle of the same type. Heat transfer through such a needle is significant, compared to natural body-energy consumption over a range of ambient temperatures. The mechanism by which heat flows in or out of the body through the needles may be crucial in the remedial efficacy of acupuncture. Copyright © 2015. Published by Elsevier B.V.
Charge-transfer mobility and electrical conductivity of PANI as conjugated organic semiconductors.
Zhang, Yahong; Duan, Yuping; Song, Lulu; Zheng, Daoyuan; Zhang, Mingxing; Zhao, Guangjiu
2017-09-21
The intramolecular charge transfer properties of a phenyl-end-capped aniline tetramer (ANIH) and a chloro-substituted derivative (ANICl) as organic semiconductors were theoretically studied through the first-principles calculation based on the Marcus-Hush theory. The reorganization energies, intermolecular electronic couplings, angular resolution anisotropic mobilities, and density of states of the two crystals were evaluated. The calculated results demonstrate that both ANIH and ANICl crystals show the higher electron transfer mobilities than the hole-transfer mobilities, which means that the two crystals should prefer to function as n-type organic semiconductors. Furthermore, the angle dependence mobilities of the two crystals show remarkable anisotropic character. The maximum mobility μ max of ANIH and ANICl crystals is 1.3893 and 0.0272 cm 2 V -1 s -1 , which appear at the orientation angles near 176°/356° and 119°/299° of a conducting channel on the a-b reference plane. It is synthetically evaluated that the ANIH crystal possesses relatively lower reorganization energy, higher electronic coupling, and electron transfer mobility, which means that the ANIH crystal may be the more ideal candidate as a high performance n-type organic semiconductor material. The systematic theoretical studies on organic crystals should be conducive to evaluating the charge-transport properties and designing higher performance organic semiconductor materials.
Thermal conductivity and heat transfer in superlattices
Energy Technology Data Exchange (ETDEWEB)
Chen, G; Neagu, M; Borca-Tasciuc, T
1997-07-01
Understanding the thermal conductivity and heat transfer processes in superlattice structures is critical for the development of thermoelectric materials and devices based on quantum structures. This work reports progress on the modeling of thermal conductivity of superlattice structures. Results from the models established based on the Boltzmann transport equation could explain existing experimental results on the thermal conductivity of semiconductor superlattices in both in plane and cross-plane directions. These results suggest the possibility of engineering the interfaces to further reduce thermal conductivity of superlattice structures.
Fourier analysis of conductive heat transfer for glazed roofing materials
Energy Technology Data Exchange (ETDEWEB)
Roslan, Nurhana Lyana; Bahaman, Nurfaradila; Almanan, Raja Noorliyana Raja; Ismail, Razidah [Faculty of Computer and Mathematical Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Zakaria, Nor Zaini [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)
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.
Analytical Evalution of Heat Transfer Conductivity with Variable Properties
DEFF Research Database (Denmark)
Rahimi, Masoume; Hosseini, Mohammad Javad; Barari, Amin
2011-01-01
The homotopy analysis method (HAM) as a new technique which is powerful and easy-to-use, is applied to solve heat transfer problems. In this paper, we use HAM for heat transfer conductivity equation with variable properties which may contain highly nonlinear terms. The obtained results are also...
Mean free path dependent phonon contributions to interfacial thermal conductance
Energy Technology Data Exchange (ETDEWEB)
Tao, Yi; Liu, Chenhan; Chen, Weiyu; Cai, Shuang; Chen, Chen; Wei, Zhiyong; Bi, Kedong; Yang, Juekuan; Chen, Yunfei, E-mail: yunfeichen@seu.edu.cn
2017-06-15
Interfacial thermal conductance as an accumulation function of the phonon mean free path is rigorously derived from the thermal conductivity accumulation function. Based on our theoretical model, the interfacial thermal conductance accumulation function between Si/Ge is calculated. The results show that the range of mean free paths (MFPs) for phonons contributing to the interfacial thermal conductance is far narrower than that for phonons contributing to the thermal conductivity. The interfacial thermal conductance is mainly contributed by phonons with shorter MFPs, and the size effects can be observed only for an interface constructed by nanostructures with film thicknesses smaller than the MFPs of those phonons mainly contributing to the interfacial thermal conductance. This is why most experimental measurements cannot detect size effects on interfacial thermal conductance. A molecular dynamics simulation is employed to verify our proposed model. - Highlights: • A model to account for the interfacial thermal conductance as an accumulation function of phonon mean free path is proposed; • The model predicts that the range of mean free paths (MFPs) for phonons contributing to the interfacial thermal conductance is far narrower than that contributing to the thermal conductivity; • This model can be conveniently implemented to estimate the size effects on the interfacial thermal conductance for the interfaces formed by a nanostructure contacting a substrate.
MEANING TRANSFER ANALYSIS OF BALINESE ARTS TERMS INTO ENGLISH AND FRENCH: A COMPARATIVE STUDY
Directory of Open Access Journals (Sweden)
Putu Weddha Savitri
2015-11-01
Full Text Available In order to show and promote Balinese culture to the incoming tourists, many specific terms, especially in arts terms, must be well translated. This paper aims at analyzing the meaning transfer of Balinese Arts Terms into English and French found in Tourism Promotion Book published by Bali Government Tourism Department in two languages versions. The analysis focused on the techniques or procedures applied in transferring Balinese art terms into English (TL1 and French (TL2. Besides, it is also to figure out the most common technique used by the translator in transferring the meanings. The findings showed that there are three techniques used to transfer the meaning of the SL into the TL 1, those are descriptive, transcription, and functional equivalence, meanwhile, there are three translation techniques: transcription, functional equivalence, and formal equivalence and one translation procedure: cultural equivalence used in transferring the SL meaning to TL 2. Transcription technique, usually called borrowing was mostly used by the translator in the meaning transfer from the SL to both the target languages in order to retain the SL meaning in the TL.
Homogenization of a Conductive-Radiative Heat Transfer Problem
Directory of Open Access Journals (Sweden)
Habibi Zakaria
2012-04-01
Full Text Available This paper focuses on the contribution of the second order corrector in periodic homogenization applied to a conductive-radiative heat transfer problem. Especially, for a heat conduction problem in a periodically perforated domain with a non-local boundary condition modelling the radiative heat transfer, if this model contains an oscillating thermal source and a thermal exchange with the perforations, the second order corrector helps us to model the gradients which appear between the source area and the perforations. Ce papier est consacré à montrer l’influence du correcteur de second ordre en homogénéisation périodique. Dans l’homogénéisation d’un problème de conduction rayonnement dans un domaine périodiquement perforé par plusieurs trous, on peut voir une contribution non négligeable de ce correcteur lors de la présence d’une source thermique oscillante et d’un échange thermique dans les perforations. Ce correcteur nous permet de modéliser les gradients qui apparaissent entre la zone de la source thermique et les perforations.
Conduction mechanism studies on electron transfer of disordered system
Institute of Scientific and Technical Information of China (English)
徐慧; 宋祎璞; 李新梅
2002-01-01
Using the negative eigenvalue theory and the infinite order perturbation theory, a new method was developed to solve the eigenvectors of disordered systems. The result shows that eigenvectors change from the extended state to the localized state with the increase of the site points and the disordered degree of the system. When electric field is exerted, the electrons transfer from one localized state to another one. The conductivity is induced by the electron transfer. The authors derive the formula of electron conductivity and find the electron hops between localized states whose energies are close to each other, whereas localized positions differ from each other greatly. At low temperature the disordered system has the character of the negative differential dependence of resistivity and temperature.
Product Meaning, Affective Use Evaluation, and Transfer: A Preliminary Study
Directory of Open Access Journals (Sweden)
Sacha Helfenstein
2005-01-01
Full Text Available The first part of this investigation explored the multidimensional nature of product meaning, referring to the variety of connotations and functions a consumer associates with a particular product category. The subsequent experiment examined the moderation effects of product meaning and other attributes of the user on (a the affective evaluation of an obstructed use interaction, and (b the transfer of emotion between devices presented as being either of the same or a different brand. Although the failure experience essentially caused frustration, this reaction varied substantially among consumers depending on product meaning, age, and gender. The results also showed that the emotion dimensions of pleasure, arousal, and dominance were affected in distinct ways, and that, in addition to the consumer variables, transfer was mainly dependent on the brand relation. Nevertheless, user frustration did not cause general brand aversion, indicating that poor designs do not unconditionally threaten the customer relationship.
Electron Transfer between Electrically Conductive Minerals and Quinones
Directory of Open Access Journals (Sweden)
Olga Taran
2017-07-01
Full Text Available Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well-known, but the impact of abiotic currents across naturally occurring conductive and semiconductive minerals is poorly understood. In this paper I use cyclic voltammetry to explore electron transfer between electrodes made of common iron minerals (magnetite, hematite, pyrite, pyrrhotite, mackinawite, and greigite, and hydroquinones—a class of organic molecules found in carbon-rich sediments. Of all tested minerals, only pyrite and magnetite showed an increase in electric current in the presence of organic molecules, with pyrite showing excellent electrocatalytic performance. Pyrite electrodes performed better than commercially available glassy carbon electrodes and showed higher peak currents, lower overpotential values and a smaller separation between oxidation and reduction peaks for each tested quinone. Hydroquinone oxidation on pyrite surfaces was reversible, diffusion controlled, and stable over a large number of potential cycles. Given the ubiquity of both pyrite and quinones, abiotic electron transfer between minerals and organic molecules is likely widespread in Nature and may contribute to several different phenomena, including anaerobic respiration of a wide variety of microorganisms in temporally anoxic zones or in the proximity of hydrothermal vent chimneys, as well as quinone cycling and the propagation of anoxic zones in organic rich waters. Finally, interactions between pyrite and quinones make use of electrochemical gradients that have been suggested as an important source of energy for the origins of life on Earth. Ubiquinones and iron sulfide clusters are common redox cofactors found in electron transport chains across all domains
Electron Transfer Between Electrically Conductive Minerals and Quinones
Taran, Olga
2017-07-01
Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well known, but the impact of abiotic currents across naturally occurring conductive and semiconducitve minerals is poorly understood. In this paper I use cyclic voltammetry to explore electron transfer between electrodes made of common iron minerals (magnetite, hematite, pyrite, pyrrhotite, mackinawite and greigite), and hydroquinones - a class of organic molecules found in carbon-rich sediments. Of all tested minerals, only pyrite and magnetite showed an increase in electric current in the presence of organic molecules, with pyrite showing excellent electrocatalytic performance. Pyrite electrodes performed better than commercially available glassy carbon electrodes and showed higher peak currents, lower overpotential values and a smaller separation between oxidation and reduction peaks for each tested quinone. Hydroquinone oxidation on pyrite surfaces was reversible, diffusion controlled, and stable over a large number of potential cycles. Given the ubiquity of both pyrite and quinones, abiotic electron transfer between minerals and organic molecules is likely widespread in Nature and may contribute to several different phenomena, including anaerobic respiration of a wide variety of microorganisms in temporally anoxic zones or in the proximity of hydrothermal vent chimneys, as well as quinone cycling and the propagation of anoxic zones in organic rich waters. Finally, interactions between pyrite and quinones make use of electrochemical gradients that have been suggested as an important source of energy for the origins of life on Earth. Ubiquinones and iron sulfide clusters are common redox cofactors found in electron transport chains across all domains of life and
Microbial interspecies electron transfer via electric currents through conductive minerals
Kato, Souichiro; Hashimoto, Kazuhito; Watanabe, Kazuya
2012-01-01
In anaerobic biota, reducing equivalents (electrons) are transferred between different species of microbes [interspecies electron transfer (IET)], establishing the basis of cooperative behaviors and community functions. IET mechanisms described so far are based on diffusion of redox chemical species and/or direct contact in cell aggregates. Here, we show another possibility that IET also occurs via electric currents through natural conductive minerals. Our investigation revealed that electrically conductive magnetite nanoparticles facilitated IET from Geobacter sulfurreducens to Thiobacillus denitrificans, accomplishing acetate oxidation coupled to nitrate reduction. This two-species cooperative catabolism also occurred, albeit one order of magnitude slower, in the presence of Fe ions that worked as diffusive redox species. Semiconductive and insulating iron-oxide nanoparticles did not accelerate the cooperative catabolism. Our results suggest that microbes use conductive mineral particles as conduits of electrons, resulting in efficient IET and cooperative catabolism. Furthermore, such natural mineral conduits are considered to provide ecological advantages for users, because their investments in IET can be reduced. Given that conductive minerals are ubiquitously and abundantly present in nature, electric interactions between microbes and conductive minerals may contribute greatly to the coupling of biogeochemical reactions. PMID:22665802
Near-field radiative heat transfer under temperature gradients and conductive transfer
Energy Technology Data Exchange (ETDEWEB)
Jin, Weiliang; Rodriguez, Alejandro W. [Princeton Univ., NJ (United States). Dept. of Electrical Engineering; Messina, Riccardo [CNRS-Univ. de Montpellier (France). Lab. Charles Coulomb
2017-05-01
We describe a recently developed formulation of coupled conductive and radiative heat transfer (RHT) between objects separated by nanometric, vacuum gaps. Our results rely on analytical formulas of RHT between planar slabs (based on the scattering-matrix method) as well as a general formulation of RHT between arbitrarily shaped bodies (based on the fluctuating-volume current method), which fully captures the existence of temperature inhomogeneities. In particular, the impact of RHT on conduction, and vice versa, is obtained via self-consistent solutions of the Fourier heat equation and Maxwell's equations. We show that in materials with low thermal conductivities (e.g. zinc oxides and glasses), the interplay of conduction and RHT can strongly modify heat exchange, exemplified for instance by the presence of large temperature gradients and saturating flux rates at short (nanometric) distances. More generally, we show that the ability to tailor the temperature distribution of an object can modify the behaviour of RHT with respect to gap separations, e.g. qualitatively changing the asymptotic scaling at short separations from quadratic to linear or logarithmic. Our results could be relevant to the interpretation of both past and future experimental measurements of RHT at nanometric distances.
The Social Meaning of Inherited Financial Assets. Moral Ambivalences of Intergenerational Transfers
Directory of Open Access Journals (Sweden)
Merlin Schaeffer
2013-11-01
Full Text Available What do inherited financial assets signify to heirs and testators and how does this shape their conduct? Based on grounded theory methodology and twenty open, thematically structured interviews with US heirs, future heirs and testators, this article explicates a theoretical account that proposes a moral ambivalence as the core category to understand the social meaning of inherited financial assets. In particular, the analysis reveals that the social meaning of inherited assets is a contingent, individual compromise between seeing inherited assets as unachieved wealth and seeing them as family means of support. Being the lifetime achievement of another person, inheritances are, on the one hand, morally dubious and thus difficult to appropriate. Yet in terms of family solidarity, inheritances are "family money," which is used when need arises. Taken from this angle, inheriting is not the transfer of one individual's privately held property to another person, but rather the succession of the social status as support-giver along with the resources that belong to this status to the family's next generation. Heirs need to find a personal compromise between these poles, which always leaves room for interpretation. http://nbn-resolving.de/urn:nbn:de:0114-fqs1401131
Convective and conduction heat transfer study on a mig-type electron gun
International Nuclear Information System (INIS)
Patire Junior, H.; Barroso, J.J.
1996-01-01
A convective and conducting heat transfer study of a magnetron injection electron gun has been made to minimize the temperature distribution in the gun elements while keeping the required operating temperature at 1000 0 C of the emitter. Appropriate materials were selected to reduce thermal losses and to improve the gun design from a constructional point of view aiming at extending the capabilities of the electron gun. A thermal probe to determine the air velocity and the convective heat transfer coefficient has been constructed to determine the external boundary condition of the ceramic shell and external flanges. A study the contact resistance for all the gun elements has been made to minimize the conduction thermal losses. A software has been used to simulate a thermal model considering the three processes of thermal transfer, namely, conduction, convection and radiation and the influence of the physical properties of the materials used. (author). 7 refs., 5 figs., 1 tab
Means for transferring knowledge in the relocation of manufacturing units
DEFF Research Database (Denmark)
Madsen, Erik Skov; Yang, Cheng; Liangsiri, Jirapha
2008-01-01
) Scenarios on real systems, 3) Prototypes and games, and 4) Emulation. These means are evaluated based on the parameters in the framework and proper means are positioned in the framework. This framework can be used to support learning to develop knowledge in the new manufacturing unit....... on the situations which are extracted from the cases. Two parameters are used to classify the situation: the complexity of knowledge, and the environment for transferring the knowledge. Four different groups of means are identified from the case studies; 1) Documents or manuals and peer-to-peer training, 2...
Product meaning, affective use evaluation, and transfer : a preliminary study
Helfenstein, Sacha
2005-01-01
The first part of this investigation explored the multidimensional nature of product meaning, referring to the variety of connotations and functions a consumer associates with a particular product category. The subsequent experiment examined the moderation effects of product meaning and other attributes of the user on (a) the affective evaluation of an obstructed use interaction, and (b) the transfer of emotion between devices presented as being either of the same or a different brand. Althou...
Enhancing SERS by Means of Supramolecular Charge Transfer
Wong, Eric; Flood, Amar; Morales, Alfredo
2009-01-01
In a proposed method of sensing small quantities of molecules of interest, surface enhanced Raman scattering (SERS) spectroscopy would be further enhanced by means of intermolecular or supramolecular charge transfer. There is a very large potential market for sensors based on this method for rapid detection of chemical and biological hazards. In SERS, the Raman signals (vibrational spectra) of target molecules become enhanced by factors of the order of 108 when those molecules are in the vicinities of nanostructured substrate surfaces that have been engineered to have plasmon resonances that enhance local electric fields. SERS, as reported in several prior NASA Tech Briefs articles and elsewhere, has remained a research tool and has not yet been developed into a practical technique for sensing of target molecules: this is because the short range (5 to 20 nm) of the field enhancement necessitates engineering of receptor molecules to attract target molecules to the nanostructured substrate surfaces and to enable reliable identification of the target molecules in the presence of interferants. Intermolecular charge-transfer complexes have been used in fluorescence-, photoluminescence-, and electrochemistry-based techniques for sensing target molecules, but, until now, have not been considered for use in SERS-based sensing. The basic idea of the proposed method is to engineer receptor molecules that would be attached to nanostructured SERS substrates and that would interact with the target molecules to form receptor-target supramolecular charge-transfer complexes wherein the charge transfer could be photoexcited.
Physical meaning of conductivity spectra for ZnO ceramics
Institute of Scientific and Technical Information of China (English)
Cheng Peng-Fei; Li Sheng-Tao; Li Jian-Ying; Ding Can; Yang Yan
2012-01-01
With the help of broadband dielectric spectroscopy in a wide temperature and frequency range,the conductivity spectra of ZnO polycrystalline ceramics are measured and the direct-current-like (DC-like) conductivity and relaxation polarization conductivity are observed successively along the frequency axis.According to the classical Debye theory and Cole-Cole equation,the physical meanings of the two conductivities are discussed.It is found that the DC-like conductivity corresponds to electron transportation over the Schottky barrier at the grainboundary.The relaxation polarization conductivity corresponds to electronic trap relaxation of intrinsic point defects (zinc interstitial and oxygen vacancy).When in the high frequency region,the relaxation conductivity obeys the universal law with the index n equal to the index α in the Cole-Cole equation as an indictor of disorder degree.
Magnetohydrodynamic flow and heat transfer around a heated cylinder of arbitrary conductivity
Tassone, A.; Nobili, M.; Caruso, G.
2017-11-01
The interaction of the liquid metal with the plasma confinement magnetic field constitutes a challenge for the design of fusion reactor blankets, due to the arise of MHD effects: increased pressure drops, heat transfer suppression, etc. To overcome these issues, a dielectric fluid can be employed as coolant for the breeding zone. A typical configuration involves pipes transverse to the liquid metal flow direction. This numerical study is conducted to assess the influence of pipe conductivity on the MHD flow and heat transfer. The CFD code ANSYS CFX was employed for this purpose. The fluid is assumed to be bounded by rectangular walls with non-uniform thickness and subject to a skewed magnetic field with the main component aligned with the cylinder axis. The simulations were restricted to Re = (20; 40) and M = (10; 50). Three different scenarios for the obstacle were considered: perfectly insulating, finite conductivity and perfectly conducting. The electrical conductivity was found to affect the channel pressure penalty due to the obstacle insertion only for M = 10 and just for the two limiting cases. A general increment of the heat transfer with M was found due to the tendency of the magnetic field to equalize the flow rate between the sub-channels individuated by the pipe. The best results were obtained with the insulating pipe, due to the reduced electromagnetic drag. The generation of counter-rotating vortices close to the lateral duct walls was observed for M = 50 and perfectly conducting pipe as a result of the modified currents distribution.
Directory of Open Access Journals (Sweden)
Ryoichi Chiba
2018-01-01
Full Text Available An analytical solution is derived for one-dimensional transient heat conduction in a composite slab consisting of n layers, whose heat transfer coefficient on an external boundary is an arbitrary function of time. The composite slab, which has thermal contact resistance at n-1 interfaces, as well as an arbitrary initial temperature distribution and internal heat generation, convectively exchanges heat at the external boundaries with two different time-varying surroundings. To obtain the analytical solution, the shifting function method is first used, which yields new partial differential equations under conventional types of external boundary conditions. The solution for the derived differential equations is then obtained by means of an orthogonal expansion technique. Numerical calculations are performed for two composite slabs, whose heat transfer coefficient on the heated surface is either an exponential or a trigonometric function of time. The numerical results demonstrate the effects of temporal variations in the heat transfer coefficient on the transient temperature field of composite slabs.
International Nuclear Information System (INIS)
Son, Hyung M.; Suh, Kune Y.
2012-01-01
Highlights: ► Performed experiment for the upward SCO 2 flow surrounded by highly conducting metal. ► Selected dimensionless groups representing the property variations and buoyancy. ► Developed the heat transfer correlation for the mixed thermal boundary condition. ► Wrote a finite element heat transfer code to find the appropriate correlation. ► Coupled the 1D convection and 2D heat conduction via heat transfer coefficient. - Abstract: This paper presents heat transfer characteristics of supercritical carbon dioxide flow inside vertical circular pipe surrounded by highly conducting material, and develops an adequate tool to test the performance of available heat transfer correlations with. The possible situations are illustrated for the nuclear power plant to which the above-mentioned geometric configuration might be applicable. An experimental loop with vertical circular geometry is designed and constructed to test the upward flow in supercritical state when the axial heat transfer is enhanced by the surrounding metals, resulting in a wall boundary condition between the constant heat flux and temperature. The set of correlations and important findings are critically reviewed from extensive literature survey. Incorporating nondimensional groups resorting to past insights from the available literature, a convective heat transfer correlation is proposed. The optimization procedure is described which utilizes a random walk method along with the in-house finite element heat transfer code to determine the coefficients of the proposed heat transfer correlation. The proposed methodology can be applied to evaluation of heat transfer when the heat transfer coefficient data cannot directly be determined from the experiment.
Efficiency analysis of straight fin with variable heat transfer coefficient and thermal conductivity
International Nuclear Information System (INIS)
Sadri, Somayyeh; Raveshi, Mohammad Reza; Amiri, Shayan
2012-01-01
In this study, one type of applicable analytical method, differential transformation method (DTM), is used to evaluate the efficiency and behavior of a straight fin with variable thermal conductivity and heat transfer coefficient. Fins are widely used to enhance heat transfer between primary surface and the environment in many industrial applications. The performance of such a surface is significantly affected by variable thermal conductivity and heat transfer coefficient, particularly for large temperature differences. General heat transfer equation related to the fin is derived and dimensionalized. The concept of differential transformation is briefly introduced, and then this method is employed to derive solutions of nonlinear equations. Results are evaluated for several cases such as: laminar film boiling or condensation, forced convection, laminar natural convection, turbulent natural convection, nucleate boiling, and radiation. The obtained results from DTM are compared with the numerical solution to verify the accuracy of the proposed method. The effects of design parameters on temperature and efficiency are evaluated by some figures. The major aim of the present study, which is exclusive for this article, is to find the effect of the modes of heat transfer on fin efficiency. It has been shown that for radiation heat transfer, thermal efficiency reaches its maximum value
Thermal conductivity of granular materials
Energy Technology Data Exchange (ETDEWEB)
Buyevich, Yu A
1974-01-01
Stationary heat transfer in a granular material consisting of a continuous medium containing spherical granules of other substances is considered under the assumption that the spatial distribution of granules is random. The effective thermal conductivity characterizing macroscopic heat transfer in such a material is expressed as a certain function of the conductivities and volume fractions of the medium and dispersed substances. For reasons of mathematical analogy, all the results obtained for the thermal conductivity are valid while computing the effective diffusivity of some admixture in granular materials as well as for evaluation of the effective electric conductivity or the mean dielectric and magnetic permeabilities of granular conductors and dielectrics. (23 refs.)
Energy Technology Data Exchange (ETDEWEB)
De Beer, M., E-mail: maritz.db@gmail.com [School of Mechanical and Nuclear Engineering, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Du Toit, C.G., E-mail: Jat.DuToit@nwu.ac.za [School of Mechanical and Nuclear Engineering, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Rousseau, P.G., E-mail: pieter.rousseau@uct.ac.za [Department of Mechanical Engineering, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa)
2017-04-01
Highlights: • The radiation and conduction components of the effective thermal conductivity are separated. • Near-wall effects have a notable influence on the effective thermal conductivity. • Effective thermal conductivity is a function of the macro temperature gradient. • The effective thermal conductivity profile shows a characteristic trend. • The trend is a result of the interplay between conduction and radiation. - Abstract: The effective thermal conductivity represents the overall heat transfer characteristics of a packed bed of spheres and must be considered in the analysis and design of pebble bed gas-cooled reactors. During depressurized loss of forced cooling conditions the dominant heat transfer mechanisms for the passive removal of decay heat are radiation and conduction. Predicting the value of the effective thermal conductivity is complex since it inter alia depends on the temperature level and temperature gradient through the bed, as well as the pebble packing structure. The effect of the altered packing structure in the wall region must therefore also be considered. Being able to separate the contributions of radiation and conduction allows a better understanding of the underlying phenomena and the characteristics of the resultant effective thermal conductivity. This paper introduces a purpose-designed test facility and accompanying methodology that combines physical measurements with Computational Fluid Dynamics (CFD) simulations to separate the contributions of radiation and conduction heat transfer, including the wall effects. Preliminary results obtained with the methodology offer important insights into the trends observed in the experimental results and provide a better understanding of the interplay between the underlying heat transfer phenomena.
International Nuclear Information System (INIS)
Sarkar, J.; Bhattacharyya, Souvik
2007-01-01
In the present study, the overall conductance and the overall heat transfer area per unit capacity of refrigeration and heat pump systems have been minimized analytically considering both internal and external irreversibilities with variable temperature (finite capacity) heat reservoirs. Hot and cold side refrigerant temperatures, conductance and heat transfer area ratios have been optimized to attain this goal. The results have been verified with the more elaborate numerical optimization results obtained for ammonia based vapour compression refrigeration and heat pump systems working with variable temperature reservoirs. It is observed that the analytical results for optimum refrigerant temperatures, minimum overall conductance and heat transfer area deviate marginally from the numerically optimized results (within 1%), if one assumes a constant heat rejection temperature. The deviation of minimum overall conductance and heat transfer area is more (about 20%), if one considers both the desuperheating and condensation regions separately. However, in the absence of complex and elaborate numerical models, the simple analytical results obtained here can be used as reasonably accurate preliminary guidelines for optimization of refrigeration and heat pump systems
A multilevel method for conductive-radiative heat transfer
Energy Technology Data Exchange (ETDEWEB)
Banoczi, J.M.; Kelley, C.T. [North Carolina State Univ., Raleigh, NC (United States)
1996-12-31
We present a fast multilevel algorithm for the solution of a system of nonlinear integro-differential equations that model steady-state combined radiative-conductive heat transfer. The equations can be formulated as a compact fixed point problem with a fixed point map that requires both a solution of the linear transport equation and the linear heat equation for its evaluation. We use fast transport solvers developed by the second author, to construct an efficient evaluation of the fixed point map and then apply the Atkinson-Brakhage, method, with Newton-GMRES as the coarse mesh solver, to the full nonlinear system.
Polymer-inorganic hybrid proton conductive membranes: Effect of the interfacial transfer pathways
International Nuclear Information System (INIS)
Chen, Pingping; Hao, Lie; Wu, Wenjia; Li, Yifan; Wang, Jingtao
2016-01-01
Highlights: • A series of hybrid membranes are prepared using fillers with different structures. • The fillers (0-D, 1-D, and 2-D) are sulfonated to ensure close surface component. • The effect of filler’s structure on microstructure of hydrid membrane is explored. • For single-kind filler series, 2-D filler has the strongest conduction promotion. • The synergy effect of different kinds of fillers is systematacially investigated. - Abstract: For hybrid membrane, the polymer-inorganic interface along filler surface can be facilely created to be distinctive and controllable pathway for mass transfer. Herein, three kinds of fillers are used as inorganic additives including zero-dimensional silica (0-D, SiO_2), one-dimensional halloysite nanotube (1-D, HNT), and two-dimensional graphene oxide (2-D, GO), which are functionalized by sulfonated polymer layer to ensure close surface component. Then the fillers are incorporated into two types of polymer matrixes (phase-separated sulfonated poly(ether ether ketone) and non-phase-separated chitosan) to prepare three series of hybrid membranes with single-kind filler, double-kinds fillers, or triple-kinds fillers, respectively. The microstructures, physicochemical properties, and proton conduction properties (under hydrated and anhydrous conditions) of the membranes are extensively investigated. It is found that (i) for the single-kind filler-filled membranes, 2-D filler has the strongest promotion ability for proton conductivity of membrane due to the constructed wide and long-range pathways for proton transfer; (ii) while for the hybrid membranes with double-kinds fillers, instead of synergistic promotion effect, the fillers cause more tortuous transfer pathways within membranes and then decrease proton conductivity; (iii) the hybrid membranes with triple-kinds fillers exhibit similar behavior but a little higher conductivity than the membranes with double-kinds fillers.
Laminar forced convective/conductive heat transfer by finite element method
International Nuclear Information System (INIS)
Kushwaha, H.S.; Kakodkar, A.
1982-01-01
The present study is directed at developing a finite element computer program for solution of decoupled convective/conductive heat transfer problems. Penalty function formulation has been used to solve momentum equations and subsequently transient energy equation is solved using modified Crank-Nicolson method. The optimal upwinding scheme has been employed in energy equation to remove oscillations at high Peclet number. (author)
Directory of Open Access Journals (Sweden)
Amirah Diniaty
2014-07-01
Full Text Available Undergraduate students should take 4 credits for counseling practice subject in Counseling Department of State Islamic University of Riau. The subject is taken by seventh semester students who conduct counseling practice at senior high school for 3 months. Based on prelimenary study, majority of students acknowledged that they felt nervous to follow this programme. Thus, the problem of transference and counter transference issue for undergraduate students counseling practice must be answered by their supervisions. The result showed that a total of 93% of respondents had positive transference, while 7% of them had negative one. It means that majority of respondents felt positive transference, while internship students faced identification counter transference. It was proved that internship students did not need to have negative thinking of being rejected by the schools. The finding also showed that 97.3% of interenship students faced identification counter transference, while 2,7% of them experienced for unidentification of transfenece. It means that there were a few of them should be supervised to have good counter transference. Supervision format that done by supervisor (university teacher and tutor (high school teacher was by conducting monthly meeting and by following up counseling result and writing report. It is recommended that a professional discussion is conducted to discuss problems faced by internship students.
Transfer of alien genes by means of induced translocation in oats and other crop species
International Nuclear Information System (INIS)
Thomas, H.; Taing Aung
1977-01-01
Some of the best sources of resistance to mildew, which is the most important disease of the oat crop in the United Kingdom, occur in related weed species. The mildew resistance found in a genotype of the tetraploid species Avena barbata has been transferred into the germ plasm of the cultivated hexaploid species A. sativa by means of an induced translocation. The procedures adopted to isolate the desirable translocation and to determine its breeding behaviour are described. A number of alien genes have been transferred into wheat by means of induced translocations and genetic induction, but their successful introduction into commercial varieties has been limited. In this paper, the use and limitations of alien transfers as breeding material are discussed. (author)
Energy Technology Data Exchange (ETDEWEB)
Donne, M.D.; Piazza, G. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany). Inst. fuer Neutronenphysik und Reaktortechnik; Goraieb, A.; Sordon, G.
1998-01-01
The four ITER partners propose to use binary beryllium pebble bed as neutron multiplier. Recently this solution has been adopted for the ITER blanket as well. In order to study the heat transfer in the blanket the effective thermal conductivity and the wall heat transfer coefficient of the bed have to be known. Therefore at Forschungszentrum Karlsruhe heat transfer experiments have been performed with a binary bed of beryllium pebbles and the results have been correlated expressing thermal conductivity and wall heat transfer coefficients as a function of temperature in the bed and of the difference between the thermal expansion of the bed and of that of the confinement walls. The comparison of the obtained correlations with the data available from the literature show a quite good agreement. (author)
Kovtanyuk, Andrey E.; Botkin, Nikolai D.; Hoffmann, Karl-Heinz
2012-01-01
Radiative-conductive heat transfer in a medium bounded by two reflecting and radiating plane surfaces is considered. This process is described by a nonlinear system of two differential equations: an equation of the radiative heat transfer
DEFF Research Database (Denmark)
Zhou, Mingdong; Alexandersen, Joe; Sigmund, Ole
2016-01-01
This paper presents an industrial application of topology optimization for combined conductive and convective heat transfer problems. The solution is based on a synergy of computer aided design and engineering software tools from Dassault Systemes. The considered physical problem of steady......-state heat transfer under convection is simulated using SIMULIA-Abaqus. A corresponding topology optimization feature is provided by SIMULIA-Tosca. By following a standard workflow of design optimization, the proposed solution is able to accommodate practical design scenarios and results in efficient...
Energy Technology Data Exchange (ETDEWEB)
Berour, Nacer; Lacroix, David E-mail: david.lacroix@lemta.uhp-nancy.fr; Boulet, Pascal; Jeandel, Gerard
2004-06-01
This paper deals with heat transfer in nongrey media which scatter, absorb and emit radiation. Considering a two dimensional geometry, radiative and conductive phenomena through the medium have been taken into account. The radiative part of the problem was solved using the discrete ordinate method with classical S{sub n} quadratures. The absorption and scattering coefficients involved in the radiative transfer equation (RTE) were obtained from the Mie theory. Conduction inside the medium was linked to the RTE through the energy conservation. Validation of the model has been achieved with several simulation of water spray curtains used as fire protection walls.
Constructal entransy dissipation minimization for 'volume-point' heat conduction
International Nuclear Information System (INIS)
Chen Lingen; Wei Shuhuan; Sun Fengrui
2008-01-01
The 'volume to point' heat conduction problem, which can be described as to how to determine the optimal distribution of high conductivity material through the given volume such that the heat generated at every point is transferred most effectively to its boundary, has became the focus of attention in the current constructal theory literature. In general, the minimization of the maximum temperature difference in the volume is taken as the optimization objective. A new physical quantity, entransy, has been identified as a basis for optimizing heat transfer processes in terms of the analogy between heat and electrical conduction recently. Heat transfer analyses show that the entransy of an object describes its heat transfer ability, just as the electrical energy in a capacitor describes its charge transfer ability. Entransy dissipation occurs during heat transfer processes, as a measure of the heat transfer irreversibility with the dissipation related thermal resistance. By taking equivalent thermal resistance (it corresponds to the mean temperature difference), which reflects the average heat conduction effect and is defined based on entransy dissipation, as an optimization objective, the 'volume to point' constructal problem is re-analysed and re-optimized in this paper. The constructal shape of the control volume with the best average heat conduction effect is deduced. For the elemental area and the first order construct assembly, when the thermal current density in the high conductive link is linear with the length, the optimized shapes of assembly based on the minimization of entransy dissipation are the same as those based on minimization of the maximum temperature difference, and the mean temperature difference is 2/3 of the maximum temperature difference. For the second and higher order construct assemblies, the thermal current densities in the high conductive link are not linear with the length, and the optimized shapes of the assembly based on the
Wolter, J
1999-01-01
Pavlovian conditioning in animals is often evaluated by means of transfer of control experiments. With human subjects, however, only very few studies have been conducted and the outcomes were often not in accordance with theoretical explanations based on studies with animals. A theoretical framework is presented that tries to integrate the results of the human conditioning paradigm and the animal conditioning paradigm as well, with reference to the well-known Yerkes-Dodson law. The experimental study with human subjects (N = 24) confirmed the predictions out of this framework, when a procedure similar to animal research is applied.
Kovtanyuk, Andrey E.
2012-01-01
Radiative-conductive heat transfer in a medium bounded by two reflecting and radiating plane surfaces is considered. This process is described by a nonlinear system of two differential equations: an equation of the radiative heat transfer and an equation of the conductive heat exchange. The problem is characterized by anisotropic scattering of the medium and by specularly and diffusely reflecting boundaries. For the computation of solutions of this problem, two approaches based on iterative techniques are considered. First, a recursive algorithm based on some modification of the Monte Carlo method is proposed. Second, the diffusion approximation of the radiative transfer equation is utilized. Numerical comparisons of the approaches proposed are given in the case of isotropic scattering. © 2011 Elsevier Ltd. All rights reserved.
Ratto, Luca; Satta, Francesca; Tanda, Giovanni
2018-06-01
This paper presents an experimental and numerical investigation of heat transfer in the endwall region of a large scale turbine cascade. The steady-state liquid crystal technique has been used to obtain the map of the heat transfer coefficient for a constant heat flux boundary condition. In the presence of two- and three-dimensional flows with significant spatial variations of the heat transfer coefficient, tangential heat conduction could lead to error in the heat transfer coefficient determination, since local heat fluxes at the wall-to-fluid interface tend to differ from point to point and surface temperatures to be smoothed out, thus making the uniform-heat-flux boundary condition difficult to be perfectly achieved. For this reason, numerical simulations of flow and heat transfer in the cascade including the effect of tangential heat conduction inside the endwall have been performed. The major objective of numerical simulations was to investigate the influence of wall heat conduction on the convective heat transfer coefficient determined during a nominal iso-flux heat transfer experiment and to interpret possible differences between numerical and experimental heat transfer results. Results were presented and discussed in terms of local Nusselt number and a convenient wall heat flux function for two values of the Reynolds number (270,000 and 960,000).
Heat transfer in the thermal entrance region of a circular tube with axial heat conduction
International Nuclear Information System (INIS)
Zhang Changquan.
1985-01-01
This paper recounts the effects of axial heat conduction and convective boundary conditions on the heat transfer in the thermal entrance region of a circular tube under uniform flow, and the corresponding calculation is made. It will be profitable for the heat transfer studies on the pipe entrance region of low Prandtl number (liquid metal), or flow of low Peclet number. (author)
Linhart, S. Mike; Nania, Jon F.; Sanders, Curtis L.; Archfield, Stacey A.
2012-01-01
The U.S. Geological Survey (USGS) maintains approximately 148 real-time streamgages in Iowa for which daily mean streamflow information is available, but daily mean streamflow data commonly are needed at locations where no streamgages are present. Therefore, the USGS conducted a study as part of a larger project in cooperation with the Iowa Department of Natural Resources to develop methods to estimate daily mean streamflow at locations in ungaged watersheds in Iowa by using two regression-based statistical methods. The regression equations for the statistical methods were developed from historical daily mean streamflow and basin characteristics from streamgages within the study area, which includes the entire State of Iowa and adjacent areas within a 50-mile buffer of Iowa in neighboring states. Results of this study can be used with other techniques to determine the best method for application in Iowa and can be used to produce a Web-based geographic information system tool to compute streamflow estimates automatically. The Flow Anywhere statistical method is a variation of the drainage-area-ratio method, which transfers same-day streamflow information from a reference streamgage to another location by using the daily mean streamflow at the reference streamgage and the drainage-area ratio of the two locations. The Flow Anywhere method modifies the drainage-area-ratio method in order to regionalize the equations for Iowa and determine the best reference streamgage from which to transfer same-day streamflow information to an ungaged location. Data used for the Flow Anywhere method were retrieved for 123 continuous-record streamgages located in Iowa and within a 50-mile buffer of Iowa. The final regression equations were computed by using either left-censored regression techniques with a low limit threshold set at 0.1 cubic feet per second (ft3/s) and the daily mean streamflow for the 15th day of every other month, or by using an ordinary-least-squares multiple
The log mean heat transfer rate method of heat exchanger considering the influence of heat radiation
International Nuclear Information System (INIS)
Wong, K.-L.; Ke, M.-T.; Ku, S.-S.
2009-01-01
The log mean temperature difference (LMTD) method is conventionally used to calculate the total heat transfer rate of heat exchangers. Because the heat radiation equation contains the 4th order exponential of temperature which is very complicate in calculations, thus LMTD method neglects the influence of heat radiation. From the recent investigation of a circular duct in some practical situations, it is found that even in the situation of the temperature difference between outer duct surface and surrounding is low to 1 deg. C, the heat radiation effect can not be ignored in the situations of lower ambient convective heat coefficient and greater surface emissivities. In this investigation, the log mean heat transfer rate (LMHTR) method which considering the influence of heat radiation, is developed to calculate the total heat transfer rate of heat exchangers.
Naya, Daniel E.; Spangenberg, Lucía; Naya, Hugo; Bozinovic, Francisco
2013-01-01
Thermal conductance measures the ease with which heat leaves or enters an organism's body. Although the analysis of this physiological variable in relation to climatic and ecological factors can be traced to studies by Scholander and colleagues, only small advances have occurred ever since. Here, we analyse the relationship between minimal thermal conductance estimated during summer (Cmin) and several ecological, climatic and geographical factors for 127 rodent species, in order to identify the exogenous factors that have potentially affected the evolution of thermal conductance. In addition, we evaluate whether there is compensation between Cmin and basal metabolic rate (BMR)—in such a way that a scale-invariant ratio between both variables is equal to one—as could be expected from the Scholander–Irving model of heat transfer. Our major findings are (i) annual mean temperature is the best single predictor of mass-independent Cmin. (ii) After controlling for the effect of body mass, there is a strong positive correlation between log10 (Cmin) and log10 (BMR). Further, the slope of this correlation is close to one, indicating an almost perfect compensation between both physiological variables. (iii) Structural equation modelling indicated that Cmin values are adjusted to BMR values and not the other way around. Thus, our results strongly suggest that BMR and thermal conductance integrate a coordinated system for heat regulation in endothermic animals and that summer conductance values are adjusted (in an evolutionary sense) to track changes in BMRs. PMID:23902915
Naya, Daniel E; Spangenberg, Lucía; Naya, Hugo; Bozinovic, Francisco
2013-09-22
Thermal conductance measures the ease with which heat leaves or enters an organism's body. Although the analysis of this physiological variable in relation to climatic and ecological factors can be traced to studies by Scholander and colleagues, only small advances have occurred ever since. Here, we analyse the relationship between minimal thermal conductance estimated during summer (Cmin) and several ecological, climatic and geographical factors for 127 rodent species, in order to identify the exogenous factors that have potentially affected the evolution of thermal conductance. In addition, we evaluate whether there is compensation between Cmin and basal metabolic rate (BMR)-in such a way that a scale-invariant ratio between both variables is equal to one-as could be expected from the Scholander-Irving model of heat transfer. Our major findings are (i) annual mean temperature is the best single predictor of mass-independent Cmin. (ii) After controlling for the effect of body mass, there is a strong positive correlation between log10 (Cmin) and log10 (BMR). Further, the slope of this correlation is close to one, indicating an almost perfect compensation between both physiological variables. (iii) Structural equation modelling indicated that Cmin values are adjusted to BMR values and not the other way around. Thus, our results strongly suggest that BMR and thermal conductance integrate a coordinated system for heat regulation in endothermic animals and that summer conductance values are adjusted (in an evolutionary sense) to track changes in BMRs.
Improved heat transfer on condensers with Ti tubes by means of granulate spheres
International Nuclear Information System (INIS)
Multer, I.
1985-01-01
Swedish power plants are located on the Baltic Sea coast and on the West coast. The cooling water is of high quality with low to medium impurity concentrations. In spite of this, pipe leakages occurred after a short period of operation, and the SoMs tubes had to be replaced by Ti tubes. Contrary to expectations, the heat transfer coefficient was higher by 10 to 20% with Ti tubes. This improvement is assumed to be due to the fact that Ti tube condensers are easier to clean by means of foamed rubber balls. As it was impossible to obtain a heat transfer coefficient of 100% with foamed rubber balls, experiments were carried out with granulate balls developed by Taprogge. In 6 series of experiments the overall heat transfer coefficient could be raised by 8%. Further experiments will follow. (orig.) [de
International Nuclear Information System (INIS)
Hadgu, T.; Webb, S.; Itamura, M.
2004-01-01
Yucca Mountain, Nevada has been designated as the nation's high-level radioactive waste repository and the U.S. Department of Energy has been approved to apply to the U.S. Nuclear Regulatory Commission for a license to construct a repository. Heat transfer in the Yucca Mountain Project (YMP) drift enclosures is an important aspect of repository waste emplacement. Canisters containing radioactive waste are to be emplaced in tunnels drilled 500 m below the ground surface. After repository closure, decaying heat is transferred from waste packages to the host rock by a combination of thermal radiation, natural convection and conduction heat transfer mechanism?. Current YMP mountain-scale and drift-scale numerical models often use a simplified porous medium code to model fluid and heat flow in the drift openings. To account for natural convection heat transfer, the thermal conductivity of the air was increased in the porous medium model. The equivalent thermal conductivity, defined as the ratio of total heat flow to conductive heat flow, used in the porous media models was based on horizontal concentric cylinders. Such modeling does not effectively capture turbulent natural convection in the open spaces as discussed by Webb et al. (2003) yet the approach is still widely used on the YMP project. In order to mechanistically model natural convection conditions in YMP drifts, the computational fluid dynamics (CFD) code FLUENT (Fluent, Incorporated, 2001) has been used to model natural convection heat transfer in the YMP emplacement drifts. A two-dimensional (2D) model representative of YMP geometry (e.g., includes waste package, drip shield, invert and drift wall) has been developed and numerical simulations made (Francis et al., 2003). Using CFD simulation results for both natural convection and conduction-only heat transfer in a single phase, single component fluid, equivalent thermal conductivities have been calculated for different Rayleigh numbers. Correlation
High-conductance states in a mean-field cortical network model
Lerchner, A; Hertz, J
2004-01-01
Measured responses from visual cortical neurons show that spike times tend to be correlated rather than exactly Poisson distributed. Fano factors vary and are usually greater than 1 due to the tendency of spikes being clustered into bursts. We show that this behavior emerges naturally in a balanced cortical network model with random connectivity and conductance-based synapses. We employ mean field theory with correctly colored noise to describe temporal correlations in the neuronal activity. Our results illuminate the connection between two independent experimental findings: high conductance states of cortical neurons in their natural environment, and variable non-Poissonian spike statistics with Fano factors greater than 1.
Lienhard, John H
2011-01-01
This introduction to heat transfer offers advanced undergraduate and graduate engineering students a solid foundation in the subjects of conduction, convection, radiation, and phase-change, in addition to the related topic of mass transfer. A staple of engineering courses around the world for more than three decades, it has been revised and updated regularly by the authors, a pair of recognized experts in the field. The text addresses the implications, limitations, and meanings of many aspects of heat transfer, connecting the subject to its real-world applications and developing students' ins
Moisture Transfer in Concrete: Numerical Determination of the Capillary Conductivity Coefficient
Directory of Open Access Journals (Sweden)
Simo Elie
2017-03-01
Full Text Available We numerically investigated moisture transfer in buildings made of concrete. We considered three types of concrete: normal concrete, pumice concrete and cellular concrete. We present the results of a 1-D liquid water flow in such materials. We evaluated the moisture distribution in building materials using the Runge-Kutta fourth-and-fifth-order method. The DOPRI5 code was used as an integrator. The model calculated the resulting moisture content and other moisture-dependent physical parameters. The moisture curves were plotted. The dampness data obtained was utilized for the numerical computation of the coefficient of the capillary conductivity of moisture. Different profiles of this coefficient are represented. Calculations were performed for four different values of the outdoor temperature: -5°C, 0°C, 5°C and 10°C. We determined that the curves corresponding to small time intervals of wetting are associated with great amplitudes of the capillary conductivity . The amplitudes of the coefficient of the capillary conductivity decrease as the time interval increases. High outdoor temperatures induce high amplitudes of the coefficient of the capillary conductivity.
High-conductance states in a mean-field cortical network model
DEFF Research Database (Denmark)
Lerchner, Alexander; Ahmadi, Mandana; Hertz, John
2004-01-01
cortical network model with random connectivity and conductance-based synapses. We employ mean-field theory with correctly colored noise to describe temporal correlations in the neuronal activity. Our results illuminate the connection between two independent experimental findings: high-conductance states......Measured responses from visual cortical neurons show that spike times tend to be correlated rather than exactly Poisson distributed. Fano factors vary and are usually greater than 1, indicating a tendency toward spikes being clustered. We show that this behavior emerges naturally in a balanced...... of cortical neurons in their natural environment, and variable non-Poissonian spike statistics with Fano factors greater than 1. (C) 2004 Elsevier B.V. All rights reserved....
Hartnett, James P; Cho, Young I; Greene, George A
2001-01-01
Heat transfer is the exchange of heat energy between a system and its surrounding environment, which results from a temperature difference and takes place by means of a process of thermal conduction, mechanical convection, or electromagnetic radiation. Advances in Heat Transfer is designed to fill the information gap between regularly scheduled journals and university-level textbooks by providing in-depth review articles over a broader scope than is allowable in either journals or texts.
Directory of Open Access Journals (Sweden)
Raúl García
2015-06-01
Full Text Available We describe the synthesis and single-molecule electrical transport properties of a molecular wire containing a π-extended tetrathiafulvalene (exTTF group and its charge-transfer complex with F4TCNQ. We form single-molecule junctions using the in situ break junction technique using a homebuilt scanning tunneling microscope with a range of conductance between 10 G0 down to 10−7 G0. Within this range we do not observe a clear conductance signature of the neutral parent molecule, suggesting either that its conductance is too low or that it does not form a stable junction. Conversely, we do find a clear conductance signature in the experiments carried out on the charge-transfer complex. Due to the fact we expected this species to have a higher conductance than the neutral molecule, we believe this supports the idea that the conductance of the neutral molecule is very low, below our measurement sensitivity. This idea is further supported by theoretical calculations. To the best of our knowledge, these are the first reported single-molecule conductance measurements on a molecular charge-transfer species.
Directory of Open Access Journals (Sweden)
Vongsetskul Thammasit
2017-01-01
Full Text Available Graphene oxide-loaded shortening (GOS, an environmentally friendly heat transfer fluid with high thermal conductivity, was successfully prepared by mixing graphene oxide (GO with a shortening. Scanning electron microscopy revealed that GO particles, prepared by the modified Hummer’s method, dispersed well in the shortening. In addition, the latent heat of GOS decreased while their viscosity and thermal conductivity increased with increasing the amount of loaded GO. The thermal conductivity of the GOS with 4% GO was higher than that of pure shortening of ca. three times, from 0.1751 to 0.6022 W/mK, and increased with increasing temperature. The GOS started to be degraded at ca. 360°C. After being heated and cooled at 100°C for 100 cycles, its viscosity slightly decreased and no chemical degradation was observed. Therefore, the prepared GOS is potentially used as environmentally friendly heat transfer fluid at high temperature.
Stanis, Ronald J.; Lambert, Timothy N.
2016-12-06
An apparatus of an aspect includes a fuel cell catalyst layer. The fuel cell catalyst layer is operable to catalyze a reaction involving a fuel reactant. A fuel cell gas diffusion layer is coupled with the fuel cell catalyst layer. The fuel cell gas diffusion layer includes a porous electrically conductive material. The porous electrically conductive material is operable to allow the fuel reactant to transfer through the fuel cell gas diffusion layer to reach the fuel cell catalyst layer. The porous electrically conductive material is also operable to conduct electrons associated with the reaction through the fuel cell gas diffusion layer. An electrically conductive polymer material is coupled with the fuel cell gas diffusion layer. The electrically conductive polymer material is operable to limit transfer of the fuel reactant to the fuel cell catalyst layer.
Effect of wall conductances on hydromagnetic flow and heat transfer in a rotating channel
International Nuclear Information System (INIS)
Mazumder, B.S.
1977-01-01
Wall conductance effects on the hydromagnetic flow and heat transfer between two parallel plates in a rotating frame of reference has been studied when the liquid is permeated by a transverse magnetic field. An exact solution of the governing equation has been obtained. It is found that the velocity current density and the temperature depend only on the sum of the wall conductances phi 1 + phi 2 = phi but magnetic field depends on the individual values of phi 1 and phi 2 where phi 1 and phi 2 are respectively the wall conductance ratios of the upper and lower walls. (Auth.)
International Nuclear Information System (INIS)
Dauvois, Yann
2016-01-01
In the present work, the effective heat transfer properties of fibrous medium are determined by taking into account a coupling of heat conduction and radiation. A virtual, statistically homogeneous, two-phase fibrous sample has been built by stacking finite absorbing cylinders in vacuum. These cylinders are dispersed according to prescribed distribution functions defining the cylinder positions and orientations. Cylinder overlappings are allowed. Extinction, absorption and scattering are characterised by radiative statistical functions which allow the Beerian behaviour of a medium to be assessed (or not). They are accurately determined with a Monte Carlo method. Whereas the gaseous phase exhibits a Beerian behaviour, the fibre phase is strongly non Beerian. The radiative power field deposited within the fibrous material is calculated by resolving a model which couples a Generalized Radiative Transfer Equation (GRTE) and a classic Radiative Transfer Equation (RTE). The model of conduction transfer is based on a random walk method without meshing. The simulation of Brownian motion of walkers in fibres allows the energy equation to be solved. The idea of the method is to characterize the temperature in an elementary volume by the density of walkers, which roam the medium. The problem is governed by boundary conditions; A constant concentration of walkers (or a constant flux) is associated with a fixed temperature (or flux). (author) [fr
International Nuclear Information System (INIS)
Jeanne, T.
1990-03-01
A conduction model and a radiation model are proposed for the calculation of heat transfer. A multiphase multicomponent medium is considered. The conduction model allows the calculation of heat exchanges between two configurations. The heat flow from each component can be obtained. This model is well adapted to the calculation of thermal shocks in an ensemble of materials. The radiation model shows how the radiative transfers can be calculated in a cylinder composed of two opaque surfaces, with the same axis of rotation, and separated by a transparent medium. The form factors are obtained from Herman and Nusselt methods. The parts of the face-to-face surfaces which are seen and not seen are evaluated [fr
Heat transfer and thermal stress analysis in grooved tubes
Indian Academy of Sciences (India)
Heat transfer and thermal stresses, induced by temperature differencesin the internally grooved tubes of heat transfer equipment, have been analysed numerically. The analysis has been conducted for four different kinds of internally grooved tubes and three different mean inlet water velocities. Constant temperature was ...
International Nuclear Information System (INIS)
Mishra, Subhash C.; Roy, Hillol K.
2007-01-01
The lattice Boltzmann method (LBM) was used to solve the energy equation of a transient conduction-radiation heat transfer problem. The finite volume method (FVM) was used to compute the radiative information. To study the compatibility of the LBM for the energy equation and the FVM for the radiative transfer equation, transient conduction and radiation heat transfer problems in 1-D planar and 2-D rectangular geometries were considered. In order to establish the suitability of the LBM, the energy equations of the two problems were also solved using the FVM of the computational fluid dynamics. The FVM used in the radiative heat transfer was employed to compute the radiative information required for the solution of the energy equation using the LBM or the FVM (of the CFD). To study the compatibility and suitability of the LBM for the solution of energy equation and the FVM for the radiative information, results were analyzed for the effects of various parameters such as the scattering albedo, the conduction-radiation parameter and the boundary emissivity. The results of the LBM-FVM combination were found to be in excellent agreement with the FVM-FVM combination. The number of iterations and CPU times in both the combinations were found comparable
International Nuclear Information System (INIS)
Manca, Michele; Malara, Francesco; Martiradonna, Luigi; De Marco, Luisa; Giannuzzi, Roberto; Cingolani, Roberto; Gigli, Giuseppe
2010-01-01
A thin anatase titanium dioxide compact film was deposited by electron beam evaporation as buffer layer between the conductive transparent electrode and the porous TiO 2 -based photoelectrode in dye-sensitized solar cells. The effect of such a buffer layer on the back transfer reaction of electrons to tri-iodide ions in liquid electrolyte-based cells has been studied by means of both electrochemical impedance spectroscopy and open circuit photovoltage decay analysis. The influence of the thickness has been also investigated and an increment in overall quantum conversion efficiency η as high as + 31% with respect to the standard cell - fabricated onto an uncoated conductive glass - has been revealed in the case of a 120 nm thick buffer layer.
Direct Electron Transfer of Enzymes in a Biologically Assembled Conductive Nanomesh Enzyme Platform.
Lee, Seung-Woo; Lee, Ki-Young; Song, Yong-Won; Choi, Won Kook; Chang, Joonyeon; Yi, Hyunjung
2016-02-24
Nondestructive assembly of a nanostructured enzyme platform is developed in combination of the specific biomolecular attraction and electrostatic coupling for highly efficient direct electron transfer (DET) of enzymes with unprecedented applicability and versatility. The biologically assembled conductive nanomesh enzyme platform enables DET-based flexible integrated biosensors and DET of eight different enzyme with various catalytic activities. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Energy Technology Data Exchange (ETDEWEB)
Penrod, S.R. [Martin Marietta Energy Systems, Inc., KY (United States)
1991-12-31
This paper describes the initial planning and actual field activities associated with the implementation of {open_quotes}Conduct of Operations{close_quotes}. Conduct of Operations is an operating philosophy that was developed through the Institute of Nuclear Power Operations (INPO). Conduct of Operations covers many operating practices and is intended to provide formality and discipline to all aspects of plant operation. The implementation of these operating principles at the UF{sub 6} Sampling and Transfer Facility resulted in significant improvements in facility operations.
Energy Technology Data Exchange (ETDEWEB)
Penrod, S.R. [Martin Marietta Energy Systems, Inc., KY (United States)
1991-12-31
This paper describes the initial planning and actual field activities associated with the implementation of {open_quotes}Conduct of Operations{close_quotes}, Conduct of Operations is an operating philosophy that was developed through the Institute of Nuclear Power Operations (INPO). Conduct of Operations covers many operating practices and is intended to provide formality and discipline to all aspects of plant operation. The implementation of these operating principles at the UF{sub 6} Sampling and Transfer Facility resulted in significant improvements in facility operations.
Ohara, Taku; Yuan, Tan Chia; Torii, Daichi; Kikugawa, Gota; Kosugi, Naohiro
2011-07-21
In this paper, the molecular mechanisms which determine the thermal conductivity of long chain polymer liquids are discussed, based on the results observed in molecular dynamics simulations. Linear n-alkanes, which are typical polymer molecules, were chosen as the target of our studies. Non-equilibrium molecular dynamics simulations of bulk liquid n-alkanes under a constant temperature gradient were performed. Saturated liquids of n-alkanes with six different chain lengths were examined at the same reduced temperature (0.7T(c)), and the contributions of inter- and intramolecular energy transfer to heat conduction flux, which were identified as components of heat flux by the authors' previous study [J. Chem. Phys. 128, 044504 (2008)], were observed. The present study compared n-alkane liquids with various molecular lengths at the same reduced temperature and corresponding saturated densities, and found that the contribution of intramolecular energy transfer to the total heat flux, relative to that of intermolecular energy transfer, increased with the molecular length. The study revealed that in long chain polymer liquids, thermal energy is mainly transferred in the space along the stiff intramolecular bonds. This finding implies a connection between anisotropic thermal conductivity and the orientation of molecules in various organized structures with long polymer molecules aligned in a certain direction, which includes confined polymer liquids and self-organized structures such as membranes of amphiphilic molecules in water.
ANALYSIS, OPTIMAL CONTROL, AND SIMULATION OF CONDUCTIVE-RADIATIVE HEAT TRANSFER
Directory of Open Access Journals (Sweden)
Peter Philip
2011-01-01
Full Text Available This article surveys recent results regarding the existence of weaksolutions to quasilinear partial differential equations(PDEcouplednonlocally by the integral operator of the radiosity equation, modeling conductive-radiative heat transfer. Both the stationary and the transient case are considered. For the stationary case, an optimal control problem with control constraints is presented withfirst-order necessary optimality conditions, where recent results on the solution theory of the linearized state equation allow to close a previous gap.Afinite volume scheme for the discretization of the stationary system is described and, based on this scheme, a numerical computation of the temperaturefield(solution of the state equationis shown as well as the numerical solution to a realistic control problem in the context of industrial applications in crystal growth.
Lu, Sen; Ren, Tusheng; Lu, Yili; Meng, Ping; Zhang, Jinsong
2017-01-05
The thermal conductivity of dry soils is related closely to air pressure and the contact areas between solid particles. In this study, the thermal conductivity of two-phase soil systems was determined under reduced and increased air pressures. The thermal separation of soil particles, i.e., the characteristic dimension of the pore space (d), was then estimated based on the relationship between soil thermal conductivity and air pressure. Results showed that under both reduced and increased air pressures, d estimations were significantly larger than the geometrical mean separation of solid particles (D), which suggested that conductive heat transfer through solid particles dominated heat transfer in dry soils. The increased air pressure approach gave d values lower than that of the reduced air pressure method. With increasing air pressure, more collisions between gas molecules and solid surface occurred in micro-pores and intra-aggregate pores due to the reduction of mean free path of air molecules. Compared to the reduced air pressure approach, the increased air pressure approach expressed more micro-pore structure attributes in heat transfer. We concluded that measuring thermal conductivity under increased air pressure procedures gave better-quality d values, and improved soil micro-pore structure estimation.
Kenjeres, S.
2016-01-01
In the present paper we give a concise review of some recent highlights of our research dealing with electromagnetic control of flow, mixing and heat transfer of electrically conductive or magnetized fluids. We apply a combination of state-of-art numerical (DNS and LES) and experimental (PIV and
International Nuclear Information System (INIS)
Draoui, Abdeslam
1989-01-01
The works we present here are on numerical approaches of heat transfer coupling radiation-conduction and radiation-convection within semi-transparent two-dimensional medium. The first part deals with a review of equations of radiative transfer and introduces three numerical methods (Pl, P3, Hottel's zones) which enable one to solve this problem in a two-dimensional environment. After comparing the three methods in the case where radiation is the only mode of transfer, we introduce in the second chapter a study of the coupling of radiation with conduction. So, a fourth method is used to solve this problem. These comparisons lead us to various methods which enable us to show the interest of the spherical harmonics approximations. In the third part, the Pl approximation is kept because it is simple to use, moreover it enables us to introduce both the coupling of radiative transfers with laminar convective equations in a thermally driven two-dimensional cavity. The results show a significant influence of the radiative participation of the fluid on heat and dynamic transfer we met in this type of problem. (author) [fr
Multiregional coupled conduction--convection model for heat transfer in an HTGR core
International Nuclear Information System (INIS)
Giles, G.E. Jr.; Childs, K.W.; Sanders, J.P.
1978-01-01
HEXEREI is a three-dimensional, coupled conduction-convection heat transfer and multichannel fluid dynamic analysis computer code with both steady-state and transient capabilities. The program was developed to provide thermal-fluid dynamic analysis of a core following the general design for high-temperature gas-cooled reactors (HTGRs); its purpose was to provide licensing evaluations for the U.S. Nuclear Regulatory Commission. In order to efficiently model the HTGR core, the nodal geometry of HEXEREI was chosen as a regular hexagonal array perpendicular to the axis of and bounded by a right circular cylinder. The cylindrical nodal geometry surrounds the hexagonal center portion of the mesh; these two different types of nodal geometries must be connected by interface nodes to complete the accurate modeling of the HTGR core. HEXEREI will automatically generate a nodal geometry that will accurately model a complex assembly of hexagonal and irregular prisms. The accuracy of the model was proven by a comparison of computed values with analytical results for steady-state and transient heat transfer problems. HEXEREI incorporates convective heat transfer to the coolant in many parallel axial flow channels. Forced and natural convection (which permits different flow directions in parallel channels) is included in the heat transfer and fluid dynamic models. HEXEREI incorporates a variety of steady-state and transient solution techniques that can be matched with a particular problem to minimize the computational time. HEXEREI was compared with a code of similar capabilities that was based on a Cartesian mesh. This code modeled only one specific core design, and the mesh spacing was closer than that generated by HEXEREI. Good agreement was obtained with the detail provided by the representations
Directory of Open Access Journals (Sweden)
Victor ANJO
2012-08-01
Full Text Available The solidification of molten metal during the casting process involves heat transfer from the molten metal to the mould, then to the atmosphere. The mechanical properties and grain size of metals are determined by the heat transfer process during solidification. The aim of this study is to numerically stimulate the steady conduction heat transfer during the solidification of aluminum in green sand mould using finite difference analysis 2D. The properties of materials used are industrial AI 50/60 AFS green sand mould, pure aluminum and MATLAB 7.0.1. for the numerical simulation. The method includes; the finite difference analysis of the heat conduction equation in steady (Laplaces and transient states and using MATLAB to numerically stimulate the thermal flow and cooling curve. The results obtained are: the steady state thermal flow in 2D and transient state cooling curve of casting. The results obtain were consider relevant in the control of the grain size and mechanical properties of the casting.
Intergenic and intragenic conjugal transfer of multiple antibiotic ...
African Journals Online (AJOL)
Conjugation process was conducted to determine the means of transferring ... In this study, it was surprisingly observed that tetracycline resistant gene was ... among pathogenic bacteria, particularly since antibiotics are indiscriminately used in ...
Energy Technology Data Exchange (ETDEWEB)
Dyrboel, Susanne
1998-05-01
Fibrous materials are some of the most widely used materials for thermal insulation. In this project the focus of interest has been on fibrous materials for building application. Interest in improving the thermal properties of insulation materials is increasing as legislation is being tightened to reduce the overall energy consumption. A knowledge of the individual heat transfer mechanisms - whereby heat is transferred within a particular material is an essential tool to improve continuously the thermal properties of the material. Heat is transferred in fibrous materials by four different transfer mechanisms: conduction through air, conduction through fibres, thermal radiation and convection. In a particular temperature range the conduction through air can be regarded as a constant, and conduction through fibres is an insignificant part of the total heat transfer. Radiation, however, constitutes 25-40% of the total heat transfer in light fibrous materials. In Denmark and a number of other countries convection in fibrous materials is considered as non-existent when calculating heat transmission as well as when designing building structures. Two heat transfer mechanisms have been the focus of the current project: radiation heat transfer and convection. The radiation analysis serves to develop a model that can be used in further work to gain a wider knowledge of the way in which the morphology of the fibrous material, i.e. fibre diameter distribution, fibre orientation distribution etc., influences the radiation heat transfer under different conditions. The convection investigation serves to examine whether considering convection as non-existent is a fair assumption to use in present and future building structures. The assumption applied in practically is that convection makes a notable difference only in very thick insulation, at external temperatures below -20 deg. C, and at very low densities. For lager thickness dimensions the resulting heat transfer through the
Heat transfer monitoring in solids by means of finite element analysis software
International Nuclear Information System (INIS)
Hernandez W, J.; Suarez, V.; Guarachi, J.; Calderon, A.; Juarez, A. G.; Rojas T, J. B.; Marin, E.
2012-10-01
We study the radial heat transfer in a homogeneous and isotropic substance with a heat linear source in its axial axis. For this, we used hot wire photothermal technique in order to obtain the temperature distribution as a function of radial distance and time exposure. Also, the solution of the transient heat transport equation for this problem was obtained with appropriate boundary conditions, by means of finite element technique. The comparison of the experimental and simulated results shows a good agree, which demonstrate the utility of this methodology in the investigation of the thermal response of substances, in the radial configuration. (Author)
Nonlinear heat conduction equations with memory: Physical meaning and analytical results
Artale Harris, Pietro; Garra, Roberto
2017-06-01
We study nonlinear heat conduction equations with memory effects within the framework of the fractional calculus approach to the generalized Maxwell-Cattaneo law. Our main aim is to derive the governing equations of heat propagation, considering both the empirical temperature-dependence of the thermal conductivity coefficient (which introduces nonlinearity) and memory effects, according to the general theory of Gurtin and Pipkin of finite velocity thermal propagation with memory. In this framework, we consider in detail two different approaches to the generalized Maxwell-Cattaneo law, based on the application of long-tail Mittag-Leffler memory function and power law relaxation functions, leading to nonlinear time-fractional telegraph and wave-type equations. We also discuss some explicit analytical results to the model equations based on the generalized separating variable method and discuss their meaning in relation to some well-known results of the ordinary case.
Conductive silver ink printing through the laser-induced forward transfer technique
International Nuclear Information System (INIS)
Florian, C.; Caballero-Lucas, F.; Fernández-Pradas, J.M.; Artigas, R.; Ogier, S.; Karnakis, D.; Serra, P.
2015-01-01
Highlights: • We have devised a strategy which allows eliminating the bulging problem during the LIFT of conductive lines. • The strategy consists of the alternate deposition of two sets of non-overlapping droplets with an intermediate drying step. • The process allows mitigating capillary flows along the printed line which are responsible for bulging and line breakup. • Conductivity measurements of laser cured lines prove the feasibility of the technique for the fabrication of interconnects. - Abstract: Laser induced forward transfer (LIFT) is a technique which allows printing a wide variety of materials. It presents several advantages over inkjet printing, such as a potentially higher resolution, being free from clogging issues, and the possibility to work with a much broader range of viscosities. LIFT appears, therefore, as an interesting alternative in all those fields where miniaturization is a major requirement, as in the microelectronics industry. The fabrication of electronic devices requires the printing of small, narrow and thin conductive lines, and in this work we investigate the printing of continuous lines of conductive silver ink on glass substrates through LIFT. Lines are initially formed through sequentially printing adjacent droplets with different overlaps. We show that above a certain overlap continuous lines can be obtained, but unfortunately they show bulging, a problem which compromises the functionality of the lines. In order to solve the problem, other printing strategies are tested; they consist in printing adjacent droplets in alternate sequences. It is found that the alternate printing of two overlapping sets of droplets with an intermediate drying step allows obtaining functional continuous lines without bulging
Conductive silver ink printing through the laser-induced forward transfer technique
Energy Technology Data Exchange (ETDEWEB)
Florian, C.; Caballero-Lucas, F.; Fernández-Pradas, J.M. [Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Artigas, R. [Sensofar-Tech S.L., Parc Audiovisual de Catalunya, Crta. BV1274 Km1, E-08225 Terrassa (Spain); Ogier, S. [Center for Process Innovation Ltd, The Wilton Centre, TS10 4RF Cleveland (United Kingdom); Karnakis, D. [Oxford Lasers Ltd, Unit 8 Moorbrook Park, OX11 7HP Didcot (United Kingdom); Serra, P., E-mail: pserra@ub.edu [Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain)
2015-05-01
Highlights: • We have devised a strategy which allows eliminating the bulging problem during the LIFT of conductive lines. • The strategy consists of the alternate deposition of two sets of non-overlapping droplets with an intermediate drying step. • The process allows mitigating capillary flows along the printed line which are responsible for bulging and line breakup. • Conductivity measurements of laser cured lines prove the feasibility of the technique for the fabrication of interconnects. - Abstract: Laser induced forward transfer (LIFT) is a technique which allows printing a wide variety of materials. It presents several advantages over inkjet printing, such as a potentially higher resolution, being free from clogging issues, and the possibility to work with a much broader range of viscosities. LIFT appears, therefore, as an interesting alternative in all those fields where miniaturization is a major requirement, as in the microelectronics industry. The fabrication of electronic devices requires the printing of small, narrow and thin conductive lines, and in this work we investigate the printing of continuous lines of conductive silver ink on glass substrates through LIFT. Lines are initially formed through sequentially printing adjacent droplets with different overlaps. We show that above a certain overlap continuous lines can be obtained, but unfortunately they show bulging, a problem which compromises the functionality of the lines. In order to solve the problem, other printing strategies are tested; they consist in printing adjacent droplets in alternate sequences. It is found that the alternate printing of two overlapping sets of droplets with an intermediate drying step allows obtaining functional continuous lines without bulging.
Directory of Open Access Journals (Sweden)
Yubai Li
2017-07-01
Full Text Available In this paper, we study the effects of the Lorentz force and the induced anisotropic thermal conductivity due to a magnetic field on the flow and the heat transfer of a ferro-nanofluid. The ferro-nanofluid is modeled as a single-phase fluid, where the viscosity depends on the concentration of nanoparticles; the thermal conductivity shows anisotropy due to the presence of the nanoparticles and the external magnetic field. The anisotropic thermal conductivity tensor, which depends on the angle of the applied magnetic field, is suggested considering the principle of material frame indifference according to Continuum Mechanics. We study two benchmark problems: the heat conduction between two concentric cylinders as well as the unsteady flow and heat transfer in a rectangular channel with three heated inner cylinders. The governing equations are made dimensionless, and the flow and the heat transfer characteristics of the ferro-nanofluid with different angles of the magnetic field, Hartmann number, Reynolds number and nanoparticles concentration are investigated systematically. The results indicate that the temperature field is strongly influenced by the anisotropic behavior of the nanofluids. In addition, the magnetic field may enhance or deteriorate the heat transfer performance (i.e., the time-spatially averaged Nusselt number in the rectangular channel depending on the situations.
International Nuclear Information System (INIS)
Rustad, James R.; Rosso, Kevin M.; Felmy, Andrew R.
2004-01-01
We present a molecular model for ferrous-ferric electron transfer in an aqueous solution that accounts for electronic polarizability and exhibits spontaneous cation hydrolysis. An extended Lagrangian technique is introduced for carrying out calculations of electron-transfer barriers in polarizable systems. The model predicts that the diabatic barrier to electron transfer increases with increasing pH, due to stabilization of the Fe 3+ by fluctuations in the number of hydroxide ions in its first coordination sphere, in much the same way as the barrier would increase with increasing dielectric constant in the Marcus theory. We have also calculated the effect of pH on the potential of mean force between two hydrolyzing ions in aqueous solution. As expected, increasing pH reduces the potential of mean force between the ferrous and ferric ions in the model system. The magnitudes of the predicted increase in diabatic transfer barrier and the predicted decrease in the potential of mean force nearly cancel each other at the canonical transfer distance of 0.55 nm. Even though hydrolysis is allowed in our calculations, the distribution of reorganization energies has only one maximum and is Gaussian to an excellent approximation, giving a harmonic free energy surface in the reorganization energy F(ΔE) with a single minimum. There is thus a surprising amount of overlap in electron-transfer reorganization energies for Fe 2+ -Fe(H 2 O) 6 3+ , Fe 2+ -Fe(OH)(H 2 O) 5 2+ , and Fe 2+ -Fe(OH) 2 (H 2 O) + couples, indicating that fluctuations in hydrolysis state can be viewed on a continuum with other solvent contributions to the reorganization energy. There appears to be little justification for thinking of the transfer rate as arising from the contributions of different hydrolysis states. Electronic structure calculations indicate that Fe(H 2 O) 6 2+ -Fe(OH) n (H 2 O) 6-n (3-n)+ complexes interacting through H 3 O 2 - bridges do not have large electronic couplings
Conductive silver ink printing through the laser-induced forward transfer technique
Florian, C.; Caballero-Lucas, F.; Fernández-Pradas, J. M.; Artigas, R.; Ogier, S.; Karnakis, D.; Serra, P.
2015-05-01
Laser induced forward transfer (LIFT) is a technique which allows printing a wide variety of materials. It presents several advantages over inkjet printing, such as a potentially higher resolution, being free from clogging issues, and the possibility to work with a much broader range of viscosities. LIFT appears, therefore, as an interesting alternative in all those fields where miniaturization is a major requirement, as in the microelectronics industry. The fabrication of electronic devices requires the printing of small, narrow and thin conductive lines, and in this work we investigate the printing of continuous lines of conductive silver ink on glass substrates through LIFT. Lines are initially formed through sequentially printing adjacent droplets with different overlaps. We show that above a certain overlap continuous lines can be obtained, but unfortunately they show bulging, a problem which compromises the functionality of the lines. In order to solve the problem, other printing strategies are tested; they consist in printing adjacent droplets in alternate sequences. It is found that the alternate printing of two overlapping sets of droplets with an intermediate drying step allows obtaining functional continuous lines without bulging.
International Nuclear Information System (INIS)
Wang, Lang Chen.
1990-01-01
A semi-implicit coupling technique (treating only the fluid temperature in the energy source term implicitly) of fluid heat-transfer to conduction slabs is presently used in TRAC-PF1. In this study, a fully implicit coupling scheme between the flow field and conduction slab for the one-dimensional capability of TRAC-PF1 has been developed. The new methods treat the heat-transfer coefficient and wall temperature in the energy source term of both the convection and the conduction equation implicitly. In order to test the accuracy of the standard TRAC coupling method and the new methods used in TRAC-PF1, a series of simple tube experiments were modeled with TRAC-PF1 version 3.9B. Additional studies showed the current TRAC-PF1 convergence variables (pressure fraction change and temperature change) and the current convergence criteria are not appropriate for obtaining an accurate result. Use of these values would produce non-physical double values or would adversely affect results in the reflood calculation. Another study also had been done to determine the importance of each HTC variable on computational accuracy and speed by using the non-linear oterative method. It is found that the heat-transfer correlations have a strong dependency on the local void fraction rather than on fluid velocity, fluid temperature, and wall surface temperature in the film boiling heat-transfer regime. At the beginning of a cooldown transient, the old time void fraction is always higher than the new time void fraction in the same time step. The old time void fraction evaluates a lower heat-transfer coefficient for that cell and initiates cooldown later and more slowly. This then leads to a longer quench time and lowers the fluid temperature and the wall temperature plateau for the downstream control volumes
Cloud, Michelle; Kritsonis, William Allan
2007-01-01
The intent of this article is to illustrate the effectiveness of using the tenets described in the Ways of Knowing Through the Realms of Meaning by Dr. William Allan Kritsonis (2007) to improve ethical conduct. Ten recommendations to implement the Ways of Knowing Through the Realms of Meaning for the improvement of ethical conduct are provided.…
Indian Academy of Sciences (India)
First page Back Continue Last page Overview Graphics. Heat transfer. Heat conduction in solid slab. Convective heat transfer. Non-linear temperature. variation due to flow. HEAT FLUX AT SURFACE. conduction/diffusion.
Potential of mean force for electrical conductivity of dense plasmas
Starrett, C. E.
2017-12-01
The electrical conductivity in dense plasmas can be calculated with the relaxation-time approximation provided that the interaction potential between the scattering electron and the ion is known. To date there has been considerable uncertainty as to the best way to define this interaction potential so that it correctly includes the effects of ionic structure, screening by electrons and partial ionization. Current approximations lead to significantly different results with varying levels of agreement when compared to bench-mark calculations and experiments. We present a new way to define this potential, drawing on ideas from classical fluid theory to define a potential of mean force. This new potential results in significantly improved agreement with experiments and bench-mark calculations, and includes all the aforementioned physics self-consistently.
Energy Technology Data Exchange (ETDEWEB)
Lyczkowski, R. W.; Solbrig, C. W.; Gidaspow, D.
1980-01-01
A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions which may arise in nuclear waste repository ventilation corridors. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Simplifications are made to decouple the convective heat transfer problem for the far field conduction problem, but peripheral conduction is retained. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition. Nusselt numbers for the case of constant temperature on the top and bottom walls and constant heat flux on the side walls exhibited unexpected behavior.
International Nuclear Information System (INIS)
Chen, Chih-Sheng; Hsieh, Chien-Kuo
2014-01-01
In this study, we develop a low-cost method for transferring a large-scale graphene film onto a flexible transparent substrate. An easily accessible method for home-made chemical vapor deposition (CVD) and a commercial photograph laminator were utilized to fabricate the low-cost graphene-based transparent conductive flexible substrate. The graphene was developed based on CVD growth on nickel foil using a carbon gas source, and the graphene thin film was easily transferred onto the laminating film via a heated photograph laminator. Field emission scanning electron microscopy and atomic force microscopy were utilized to examine the morphological characteristics of the graphene surface. Raman spectroscopy and transmission electron microscopy were utilized to examine the microstructure of the graphene. The optical–electronic properties of the transferred graphene flexible thin film were measured by ultraviolet–visible spectrometry and a four-point probe. The advantage of this method is that large-scale graphene-based thin films can be easily obtained. We provide an economical method for fabricating a graphene-based transparent conductive flexible substrate. - Highlight: • We synthesized the large-scale graphene by thermal CVD method. • A low-cost commercial photograph laminator was used to transfer graphene. • A large-scale transparent and flexible graphene substrate was obtained easily
Energy Technology Data Exchange (ETDEWEB)
Chen, Chih-Sheng; Hsieh, Chien-Kuo, E-mail: jack_hsieh@mail.mcut.edu.tw
2014-11-03
In this study, we develop a low-cost method for transferring a large-scale graphene film onto a flexible transparent substrate. An easily accessible method for home-made chemical vapor deposition (CVD) and a commercial photograph laminator were utilized to fabricate the low-cost graphene-based transparent conductive flexible substrate. The graphene was developed based on CVD growth on nickel foil using a carbon gas source, and the graphene thin film was easily transferred onto the laminating film via a heated photograph laminator. Field emission scanning electron microscopy and atomic force microscopy were utilized to examine the morphological characteristics of the graphene surface. Raman spectroscopy and transmission electron microscopy were utilized to examine the microstructure of the graphene. The optical–electronic properties of the transferred graphene flexible thin film were measured by ultraviolet–visible spectrometry and a four-point probe. The advantage of this method is that large-scale graphene-based thin films can be easily obtained. We provide an economical method for fabricating a graphene-based transparent conductive flexible substrate. - Highlight: • We synthesized the large-scale graphene by thermal CVD method. • A low-cost commercial photograph laminator was used to transfer graphene. • A large-scale transparent and flexible graphene substrate was obtained easily.
International Nuclear Information System (INIS)
Robinson, J.A.; Windebank, S.R.
1988-01-01
Condensation heat transfer coefficients have been measured in a pressurised chamber containing a mixture of saturated steam and air. They were determined as a function of the air-steam ratio in nominally stagnant conditions. The effect of pressure is assessed and preliminary measurements with a forced convective component of velocity are presented. A novel measurement technique was adopted, namely to use a vertical heat pipe whose conductance could easily be varied. It transported heat from an evaporator located inside the chamber to a condenser section outside, at which the heat flow was measured. Heat flux at the evaporator could then be determined and a condensation heat transfer coefficient derived. The range of coefficients covered was from 150 W/m 2 0 K at high air-steam ratios to 20,000 W/m 2 0 K in pure steam. Results show that increasing either total pressure or velocity enhances condensation heat transfer over the range of air/steam ratios considered. (author)
Development and adaptation of conduction and radiation heat-transfer computer codes for the CFTL
International Nuclear Information System (INIS)
Conklin, J.C.
1981-08-01
RODCON and HOTTEL are two computational methods used to calculate thermal and radiation heat transfer for the Core Flow Test Loop (CFTL) analysis efforts. RODCON was developed at ORNL to calculate the internal temperature distribution of the fuel rod simulator (FRS) for the CFTL. RODCON solves the time-dependent heat transfer equation in two-dimensional (R angle) cylindrical coordinates at an axial plane with user-specified radial material zones and time- and position-variant surface conditions at the FRS periphery. Symmetry of the FRS periphery boundary conditions is not necessary. The governing elliptic, partial differential heat equation is cast into a fully implicit, finite-difference form by approximating the derivatives with a forward-differencing scheme with variable mesh spacing. The heat conduction path is circumferentially complete, and the potential mathematical problem at the rod center can be effectively ignored. HOTTEL is a revision of an algorithm developed by C.B. Baxi at the General Atomic Company (GAC) to be used in calculating radiation heat transfer in a rod bundle enclosed in a hexagonal duct. HOTTEL uses geometric view factors, surface emissivities, and surface areas to calculate the gray-body or composite view factors in an enclosure having multiple reflections in a nonparticipating medium
Second law analysis of coupled conduction-radiation heat transfer with phase change
International Nuclear Information System (INIS)
Makhanlall, D.; Liu, L.H.
2010-01-01
This work considers an exergy-based analysis of two-dimensional solid-liquid phase change processes in a square cavity enclosure. The phase change material (PCM) concerns a semi-transparent absorbing, emitting and anisotropically scattering medium with constant thermodynamic properties. The enthalpy-based energy equation is solved numerically using computational fluid dynamics. Once the energy equation is solved, local exergy loss due to heat conduction and radiative heat transfer during the phase change process is calculated by post processing procedures. In this work, the radiation exergy loss in the medium and at the enclosure boundary is taken into consideration. It is found that radiation exergy loss is significant in the high-temperature phase change process. Parametric investigation is also carried out to study the effects of Stefan number, Biot number, Planck number, single scattering albedo and wall emissivity on exergy loss. The results show that the total exergy loss increases with Biot number, single scattering albedo and wall emissivity. The second law effects of the conduction-radiation coupling in the energy equation are also shown in this work. (authors)
Thermal conductance of heat transfer interfaces for conductively cooled superconducting magnets
International Nuclear Information System (INIS)
Cooper, T.L.; Walters, J.D.; Fikse, T.H.
1996-01-01
Minimizing thermal resistances across interfaces is critical for efficient thermal performance of conductively cooled superconducting magnet systems. Thermal conductance measurements have been made for a flexible thermal coupling, designed to accommodate magnet-to-cryocooler and cryocooler-to-shield relative motion, and an interface incorporating Multilam designed as a sliding thermal connector for cryocoolers. Temperature changes were measured across each interface as a function of heat input. Thermal conductances have been calculated for each interface, and the impact of each interface on conductively cooled magnet systems will be discussed
Kenjeres, S.
2016-09-01
In the present paper we give a concise review of some recent highlights of our research dealing with electromagnetic control of flow, mixing and heat transfer of electrically conductive or magnetized fluids. We apply a combination of state-of-art numerical (DNS and LES) and experimental (PIV and LIF) techniques to provide fundamental insights into the complex phenomena of interactions between imposed (or induced) electromagnetic fields and underlying fluid flow. Our analysis covers an extensive range of working fluids, i.e. weakly- and highly-electrically-conductive, as well as magnetized fluids. These interactions are defined through the presence of different types of body forces acting per volume of fluid. A fully closed system of governing equations containing an extended set of the Navier-Stokes and a simplified set of the Maxwell equations is presented. The four characteristic examples are selected: the electromagnetic control of self-sustained jet oscillations, the electromagnetic enhancement of heat transfer in thermal convection, the wake interactions behind magnetic obstacles and finally, the thermo-magnetic convection in differentially heated cubical enclosure. The comparative assessment between experimental and numerical results is presented. It is concluded that generally good agreement between simulations and experiments is obtained for all cases considered, proving the concept of electromagnetic modulation, which can be used in numerous technological applications.
Conductive properties of methanogenic biofilms.
Li, Cheng; Lesnik, Keaton Larson; Liu, Hong
2018-02-01
Extracellular electron transfer between syntrophic partners needs to be efficiently maintained in methanogenic environments. Direct extracellular electron transfer via electrical current is an alternative to indirect hydrogen transfer but requires construction of conductive extracellular structures. Conductive mechanisms and relationship between conductivity and the community composition in mixed-species methanogenic biofilms are not well understood. The present study investigated conductive behaviors of methanogenic biofilms and examined the correlation between biofilm conductivity and community composition between different anaerobic biofilms enriched from the same inoculum. Highest conductivity observed in methanogenic biofilms was 71.8±4.0μS/cm. Peak-manner response of conductivity upon changes over a range of electrochemical potentials suggests that electron transfer in methanogenic biofilms occurs through redox driven super-exchange. The strong correlation observed between biofilm conductivity and Geobacter spp. in the metabolically diverse anaerobic communities suggests that the efficiency of DEET may provide pressure for microbial communities to select for species that can produce electrical conduits. Copyright © 2017 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Dyrboel, Susanne
1998-05-01
Fibrous materials are some of the most widely used materials for thermal insulation. In this project the focus of interest has been on fibrous materials for building application. Interest in improving the thermal properties of insulation materials is increasing as legislation is being tightened to reduce the overall energy consumption. A knowledge of the individual heat transfer mechanisms - whereby heat is transferred within a particular material is an essential tool to improve continuously the thermal properties of the material. Heat is transferred in fibrous materials by four different transfer mechanisms: conduction through air, conduction through fibres, thermal radiation and convection. In a particular temperature range the conduction through air can be regarded as a constant, and conduction through fibres is an insignificant part of the total heat transfer. Radiation, however, constitutes 25-40% of the total heat transfer in light fibrous materials. In Denmark and a number of other countries convection in fibrous materials is considered as non-existent when calculating heat transmission as well as when designing building structures. Two heat transfer mechanisms have been the focus of the current project: radiation heat transfer and convection. The radiation analysis serves to develop a model that can be used in further work to gain a wider knowledge of the way in which the morphology of the fibrous material, i.e. fibre diameter distribution, fibre orientation distribution etc., influences the radiation heat transfer under different conditions. The convection investigation serves to examine whether considering convection as non-existent is a fair assumption to use in present and future building structures. The assumption applied in practically is that convection makes a notable difference only in very thick insulation, at external temperatures below -20 deg. C, and at very low densities. For large thickness dimensions the resulting heat transfer through the
Directory of Open Access Journals (Sweden)
Taras Pukhalskyi
2016-09-01
Full Text Available The article deals with the means of conducting and choral disciplines, which help the efficiency of training of future music teachers. Taking into consideration training and educational components of formation process of professional competence, the means of conducting and choral disciplines are classified as knowledge and skills integration, the organizational and pedagogical skills development, the communicative skills development, the realization of individual approach, the performing skills development, the educational influence and creative self- efficacy. It was established that the effective implementation of these means in the formation of music teachers’ professional competence is possible in close cooperation of choral disciplines (choir disciplines, choral conducting, choral arrangements, choral class and practical work with the choir is organized.
International Nuclear Information System (INIS)
Kitagawa, Takuya; Oka, Takashi; Demler, Eugene
2012-01-01
In this paper, we study the full conductance statistics of a disordered 1D wire under the application of light. We develop the transfer matrix method for periodically driven systems to analyze the conductance of a large system with small frequency of light, where coherent photon absorptions play an important role to determine not only the average but also the shape of conductance distributions. The average conductance under the application of light results from the competition between dynamic localization and effective dimension increase, and shows non-monotonic behavior as a function of driving amplitude. On the other hand, the shape of conductance distribution displays a crossover phenomena in the intermediate disorder strength; the application of light dramatically changes the distribution from log-normal to normal distributions. Furthermore, we propose that conductance of disordered systems can be controlled by engineering the shape, frequency and amplitude of light. Change of the shape of driving field controls the time-reversals symmetry and the disordered system shows analogous behavior as negative magneto-resistance known in static weak localization. A small change of frequency and amplitude of light leads to a large change of conductance, displaying giant opto-response. Our work advances the perspective to control the mean as well as the full conductance statistics by coherently driving disordered systems. - Highlights: ► We study conductance of disordered systems under the application of light. ► Full conductance distributions are obtained. ► A transfer matrix method is developed for driven systems. ► Conductances are dramatically modified upon the application of light. ► Time-reversal symmetry can also be controlled by light application.
Lee, Kwanghee; Janssen, R.A.J.; Sariciftci, N.S.; Heeger, A.J.
1994-01-01
We report direct spectral evidence of photoinduced electron transfer from the excited state of conducting polymer onto C60 by infrared photoexcitation spectroscopy, from 0.01 eV (100 cm-1) to 1.3 eV (11,000 cm-1). The photoinduced absorption spectra of poly(3-octylthiophene) (P30T) and
International Nuclear Information System (INIS)
Satoh, Isao; Kurosaki, Yasuo
1987-01-01
This paper dealt with the numerical calculations of the heat transfer of a tube partially heated on its circumference, considering two-dimensional heat conduction within the wall. The contribution of the unheated region of the tube wall to heat tranfer of the heated region was explained by the term of 'fin efficiency of psuedo-fin', it was clarified that the fin efficiency of the unheated region was little affected by the temperature difference between the inner and outer surfaces of the wall, and could be approximated by the fin efficency of a rectangular fin. Both the circumferential and radial heat conductions within the wall affected the temperature difference between the inner and outer surfaces of the heated region; however, the effect of the temperature difference on the circumferentially average Nusselt number could be obtained by using the analytical solution of radially one-dimensional heat conduction. Using these results, a diagram showing the effect of wall conduction on heat transfer, which is useful for designing the circumferentially nonuniformly heated coolant passages, was obtained. (author)
Directory of Open Access Journals (Sweden)
Li Zhai
2018-04-01
Full Text Available The high dv/dt and di/dt outputs from power devices in a high-low voltage DC-DC converter on electric vehicles (EVs can always introduce the unwanted conducted electromagnetic interference (EMI emissions. A conducted EMI prediction and mitigation strategy that is based on transfer function for the high-low voltage DC-DC converter in EVs are proposed. A complete test for the DC-DC converter is conducted to obtain the conducted EMI from DC power cables in the frequency band of 150 kHz-108 MHz. The equivalent circuit with high-frequency parasitic parameters of the DC-DC converter is built`1 based on the measurement results to acquire the characteristics of the conducted EMI of the DC power cables. The common mode (CM and differential mode (DM propagation coupling paths are determined, and the corresponding transfer functions of the DM interference and CM interference are established. The simulation results of the conducted EMI can be obtained by software Matlab and Computer Simulation Technology (CST. By analyzing the transfer functions and the simulation results, the dominated interference is the CM interference, which is the main factor of the conducted EMI. A mitigation strategy for the design of the CM interference filter based on the dominated CM interference is proposed. Finally, the mitigation strategy of the conducted EMI is verified by performing the conducted voltage experiment. From the experiment results, the conducted voltage of the DC power cables is decreased, respectively, by 58 dBμV, 55 dBμV, 65 dBμV, 53 dBμV, and 54 dBμV at frequency 200 kHz, 400 kHz, 600 kHz, 1.4 MHz, and 50 MHz. The conduced voltage in the frequency band of 150 kHz–108 MHz can be mitigated by adding the CM interference filters, and the values are lower than the limit level-3 of CISPR25 standard (GB/T 18655-2010.
Experimental observation for the heat transfer in fluids
International Nuclear Information System (INIS)
Salinas R, G.A.
1996-01-01
The heat transfer that occurs into a cavity with a relation 2/1 with constant heat supply in a vertical wall and on the opposed wall at constant temperature is studied. The energy transfer process causes the heat convection that occurs mainly due to energy transport that is present by means of the motion of the fluid itself. Also the heat conduction process by molecular exchange is obtained. During the fluid particle displacements, the high energy regions take contact with the low energy regions resulting by this way the free convection by density differences. The flow can be followed by means of tracers and the changes of density can be registered by optical techniques like interferometry. (Author)
International Nuclear Information System (INIS)
Wu, Chun-Chang; Hsu, Steve Lien-Chung; Chiu, Ching-Wei; Wu, Jung-Tang
2013-01-01
In this work, we have developed novel methods to fabricate conductive silver tracks and dots directly from silver nitrate solution by transfer-printing and nanoimprinting lithography techniques, which are inexpensive and can be scaled down to the nanometer scale. The silver nitrate precursor can be reduced in ethylene glycol vapor to form silver at low temperatures. Energy dispersive spectrometric analysis results indicate that the silver nitrate has been converted to silver completely. In order to obtain smooth and continuous conductive patterned silver features with high resolution, the silver lines with widths of a few tens of micrometers to nanometers were patterned by using a spin-coating approach. Using a 14 M silver nitrate solution, continuous silver conductive lines with a resistivity of 8.45 × 10 −5 Ω cm has been produced. (paper)
Court interpreting and pragmatic meaning
DEFF Research Database (Denmark)
Jacobsen, Bente
In Denmark, court interpreters are required to deliver verbatim translations of speakers' originals and to refrain from transferring pragmatic meaning. Yet, as this paper demonstrates, pragmatic meaning is central to courtroom interaction.......In Denmark, court interpreters are required to deliver verbatim translations of speakers' originals and to refrain from transferring pragmatic meaning. Yet, as this paper demonstrates, pragmatic meaning is central to courtroom interaction....
A charge transfer complex nematic liquid crystalline gel with high electrical conductivity
International Nuclear Information System (INIS)
Bhargavi, R.; Nair, Geetha G.; Krishna Prasad, S.; Majumdar, R.; Bag, Braja G.
2014-01-01
We describe the rheological, dielectric and elastic properties of a nematic liquid crystal gel created using an anthrylidene derivative of arjunolic acid, a chiral triterpenoid, obtained from the extracts of the wood of Terminalia arjuna. In this novel gel, having the electron-donor and acceptor components as minority constituents, the gelation and strengthening of charge-transfer complex (CTC) formation are seen to be occurring concomitantly. In addition to being mechanically strong with a large storage modulus, the gel with the maximized CTC exhibits Frank bend elastic constant values that approach nanonewton levels. The highlight of the study is the observation of 4–5 orders of magnitude increase in electrical conductivity for this gel, a value that is higher than even in the CT complexes of 2-d ordered columnar structures. A further important advantage of the present system over the columnar complex is that the high conductivity is seen for ac probing also, and owing to the nematic nature can be switched between its anisotropic limits. Some of these features are ascribed to a specific molecular packing architecture, which reduces the trapping of the charge carriers.
A charge transfer complex nematic liquid crystalline gel with high electrical conductivity
Bhargavi, R.; Nair, Geetha G.; Krishna Prasad, S.; Majumdar, R.; Bag, Braja G.
2014-10-01
We describe the rheological, dielectric and elastic properties of a nematic liquid crystal gel created using an anthrylidene derivative of arjunolic acid, a chiral triterpenoid, obtained from the extracts of the wood of Terminalia arjuna. In this novel gel, having the electron-donor and acceptor components as minority constituents, the gelation and strengthening of charge-transfer complex (CTC) formation are seen to be occurring concomitantly. In addition to being mechanically strong with a large storage modulus, the gel with the maximized CTC exhibits Frank bend elastic constant values that approach nanonewton levels. The highlight of the study is the observation of 4-5 orders of magnitude increase in electrical conductivity for this gel, a value that is higher than even in the CT complexes of 2-d ordered columnar structures. A further important advantage of the present system over the columnar complex is that the high conductivity is seen for ac probing also, and owing to the nematic nature can be switched between its anisotropic limits. Some of these features are ascribed to a specific molecular packing architecture, which reduces the trapping of the charge carriers.
Evaluation of Regression and Neuro_Fuzzy Models in Estimating Saturated Hydraulic Conductivity
Directory of Open Access Journals (Sweden)
J. Behmanesh
2015-06-01
Full Text Available Study of soil hydraulic properties such as saturated and unsaturated hydraulic conductivity is required in the environmental investigations. Despite numerous research, measuring saturated hydraulic conductivity using by direct methods are still costly, time consuming and professional. Therefore estimating saturated hydraulic conductivity using rapid and low cost methods such as pedo-transfer functions with acceptable accuracy was developed. The purpose of this research was to compare and evaluate 11 pedo-transfer functions and Adaptive Neuro-Fuzzy Inference System (ANFIS to estimate saturated hydraulic conductivity of soil. In this direct, saturated hydraulic conductivity and physical properties in 40 points of Urmia were calculated. The soil excavated was used in the lab to determine its easily accessible parameters. The results showed that among existing models, Aimrun et al model had the best estimation for soil saturated hydraulic conductivity. For mentioned model, the Root Mean Square Error and Mean Absolute Error parameters were 0.174 and 0.028 m/day respectively. The results of the present research, emphasises the importance of effective porosity application as an important accessible parameter in accuracy of pedo-transfer functions. sand and silt percent, bulk density and soil particle density were selected to apply in 561 ANFIS models. In training phase of best ANFIS model, the R2 and RMSE were calculated 1 and 1.2×10-7 respectively. These amounts in the test phase were 0.98 and 0.0006 respectively. Comparison of regression and ANFIS models showed that the ANFIS model had better results than regression functions. Also Nuro-Fuzzy Inference System had capability to estimatae with high accuracy in various soil textures.
International Nuclear Information System (INIS)
Lajoie, D.; Raffourt, C.; Wendling, J.
2010-01-01
radiation to the external walls of the cell. The main part of the heat retrieved by the injected air is transported up to the end of the cell where it is evacuated through the global ventilation system. The other part is lost by forced convection to concrete walls that are initially colder. The heat transfer towards external walls is a long term phenomenon. Surrounding concrete walls and geological medium store heat that is progressively transferred outside by conduction. Consequently, temperature at the concrete wall of the cells progressively increases while heat losses toward surrounding geological environment decrease. But, in the mean time, the heat release from storage packages slowly decreases. As a result, temperature the cell begins to raise in the first months of storage reaches a peak value and then decreases progressively as long as the heat release decreases. It is shown that the maximum of temperature is reached after one year of full storage in the cell. Heat fluxes through the geological medium are not spatially homogeneous, due to stratification effects in the cell. This drives to thermal gradients in concrete walls and surrounding geological medium. But, magnitudes of gradients are much lower than those simulated with adiabatic hypothesis. The external environment, that is thermally very inert, acts as a regulator that smoothes vertical thermal stratifications. Such results show interactions between stratified fluid flows and heat conduction through surrounding media. (authors)
An immersed-boundary method for conjugate heat transfer analysis
Energy Technology Data Exchange (ETDEWEB)
Song, Jeong Chul; Lee, Joon Sik [Seoul National University, Seoul (Korea, Republic of); Ahn, Joon [Kookmin University, Seoul (Korea, Republic of)
2017-05-15
An immersed-boundary method is proposed for the analysis of conjugate problems of convective heat transfer in conducting solids. In- side the solid body, momentum forcing is applied to set the velocity to zero. A thermal conductivity ratio and a heat capacity ratio, between the solid body and the fluid, are introduced so that the energy equation is reduced to the heat diffusion equation. At the solid fluid interface, an effective conductivity is introduced to satisfy the heat flux continuity. The effective thermal conductivity is obtained by considering the heat balance at the interface or by using a harmonic mean formulation. The method is first validated against the analytic solution to the heat transfer problem in a fully developed laminar channel flow with conducting solid walls. Then it is applied to a laminar channel flow with a heated, block-shaped obstacle to show its validity for geometry with sharp edges. Finally the validation for a curvilinear solid body is accomplished with a laminar flow through arrayed cylinders.
Measurement of local two-phase flow parameters of nanofluids using conductivity double-sensor probe.
Park, Yu Sun; Chang, Soon Heung
2011-04-04
A two-phase flow experiment using air and water-based γ-Al2O3 nanofluid was conducted to observe the basic hydraulic phenomenon of nanofluids. The local two-phase flow parameters were measured with a conductivity double-sensor two-phase void meter. The void fraction, interfacial velocity, interfacial area concentration, and mean bubble diameter were evaluated, and all of those results using the nanofluid were compared with the corresponding results for pure water. The void fraction distribution was flattened in the nanofluid case more than it was in the pure water case. The higher interfacial area concentration resulted in a smaller mean bubble diameter in the case of the nanofluid. This was the first attempt to measure the local two-phase flow parameters of nanofluids using a conductivity double-sensor two-phase void meter. Throughout this experimental study, the differences in the internal two-phase flow structure of the nanofluid were identified. In addition, the heat transfer enhancement of the nanofluid can be resulted from the increase of the interfacial area concentration which means the available area of the heat and mass transfer.
Energy Technology Data Exchange (ETDEWEB)
Lyczkowski, R. W. [Institute of Gas Technology, Chicago, IL (United States); Solbrig, C. W. [Commonwealth Edison Co., Chicago, IL (United States); Gidaspow, D. [Illinois Inst. of Technology, Chicago, IL (United States)
1980-01-01
A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition.
International Nuclear Information System (INIS)
Chaabane, Raoudha; Askri, Faouzi; Ben Nasrallah, Sassi
2011-01-01
In this paper, the lattice Boltzmann method (LBM) is applied to solve the energy equation of a transient conduction-radiation heat transfer problem in a two-dimensional cylindrical enclosure filled with an emitting, absorbing and scattering media. The control volume finite element method (CVFEM) is used to obtain the radiative information. To demonstrate the workability of the LBM in conjunction with the CVFEM to conduction-radiation problems in cylindrical media, the energy equation of the same problem is also solved using the finite difference method (FDM). The effects of different parameters, such as the grid size, the scattering albedo, the extinction coefficient and the conduction-radiation parameter on temperature distribution within the medium are studied. Results of the present work are compared with those available in the literature. LBM-CVFEM results are also compared with those given by the FDM-CVFEM. In all cases, good agreement has been obtained.
Theory of Periodic Conjugate Heat Transfer
Zudin, Yuri B
2012-01-01
This book presents the theory of periodic conjugate heat transfer in a detailed way. The effects of thermophysical properties and geometry of a solid body on the commonly used and experimentally determined heat transfer coefficient are analytically presented from a general point of view. The main objective of the book is a simplified description of the interaction between a solid body and a fluid as a boundary value problem of the heat conduction equation for the solid body. At the body surface, the true heat transfer coefficient is composed of two parts: the true mean value resulting from the solution of the steady state heat transfer problem and a periodically variable part, the periodic time and length to describe the oscillatory hydrodynamic effects. The second edition is extended by (i) the analysis of stability boundaries in helium flow at supercritical conditions in a heated channel with respect to the interaction between a solid body and a fluid; (ii) a periodic model and a method of heat transfer sim...
Heavy carriers, non-drude optical conductivity and transfer of spectral weight in MnSi
International Nuclear Information System (INIS)
Mena, F.P.; Damascelli, A.; Marel, D. van der; Fath, M.; Menovsky, A.A.; Mydosh, J.A.
2004-01-01
The optical properties of the weak magnetic metal MnSi were determined using reflectance at 80 deg. (2-800 meV) and ellipsometry (0.8-4.5 eV). At low frequencies in the magnetic phase we observe a departure of the optical conductivity from Drude behavior: m*(ω)/m is strongly frequency dependent and 1/τ(ω) is approximately linear in frequency. In fact, we show that σ(ω)/σ(0)=(1+iω/Γ) -0.5 . Moreover, in the magnetic phase, the plasma frequency shifts to the red indicating that spectral weight is transferred to high frequencies. This is opposite to the effect recently seen in other magnetic compounds
International Nuclear Information System (INIS)
Nisha, M R; Philip, J
2013-01-01
Polymeric nanofluids of TiO 2 /PVA (polyvinyl alcohol) and Cu/PVA have been prepared by dispersing nanoparticles of TiO 2 or metallic copper in PVA. The thermal diffusivities and thermal conductivities of these nanofluids have been measured as a function of particle loading following a thermal wave interference technique in a thermal wave resonant cavity. It is found that in both cases thermal conductivity increases with particle concentration, with Cu/PVA nanofluids showing a much larger increase. The results have been compared with the corresponding values calculated following different theoretical models. Comparison of the results with model-based calculations shows that the thermal conductivity variations in these nanofluids are within the framework of the classical mean field theory including the formation of thin interfacial adsorption layers around nanoparticles. Although the molecular weight of PVA is very high, it is found that the adsorption layer thickness is limited by the hydrodynamic radius of the nanoparticles. It is found that particle clustering followed by interfacial layering accounts for the larger increase in thermal conductivity found for Cu/PVA compared to TiO 2 /PVA. (paper)
Asmara, T C; Annadi, A; Santoso, I; Gogoi, P K; Kotlov, A; Omer, H M; Motapothula, M; Breese, M B H; Rübhausen, M; Venkatesan, T; Ariando; Rusydi, A
2014-04-14
In condensed matter physics the quasi two-dimensional electron gas at the interface of two different insulators, polar LaAlO3 on nonpolar SrTiO3 (LaAlO3/SrTiO3) is a spectacular and surprising observation. This phenomenon is LaAlO3 film thickness dependent and may be explained by the polarization catastrophe model, in which a charge transfer of 0.5e(-) from the LaAlO3 film into the LaAlO3/SrTiO3 interface is expected. Here we show that in conducting samples (≥ 4 unit cells of LaAlO3) there is indeed a ~0.5e(-) transfer from LaAlO3 into the LaAlO3/SrTiO3 interface by studying the optical conductivity in a broad energy range (0.5-35 eV). Surprisingly, in insulating samples (≤ 3 unit cells of LaAlO3) a redistribution of charges within the polar LaAlO3 sublayers (from AlO2 to LaO) as large as ~0.5e(-) is observed, with no charge transfer into the interface. Hence, our results reveal the different mechanisms for the polarization catastrophe compensation in insulating and conducting LaAlO3/SrTiO3 interfaces.
International Nuclear Information System (INIS)
Poblete Pulgar, Victor; Pilleux Cepeda, Mauricio; Fuenzalida Escobar, Victor; Alvarez Vargas, Mariela
2002-01-01
The nanocomposites synthesis of copper-methyl metacritate is made using copper spheres from 80 to 120 diameter nm, suspended in a methyl metacrilato (MMA) matrix, for different concentrations (5% to 30% of copper-v/v). The polymerization is carried out by means of gamma radiation, with 16 kGy dose applied 'in situ'. A high homogenous samples were obtained. The morphology and formation of the composite was studied by means of scanning electronic microscopy (SEM). The observed electric resistance is analyzed in function of the distance among electric contacts, meeting a strong dependence of the resistance with the homogeneous distribution of the metal in the composite. The obtained specific resistivities, in function of the concentration of the conductive metal, they are in the order of 42 Ωm for 10% v/v, being this critical concentration, the percolation threshold of the system. The obtained results show a material that is able to conserve principally the mechanical properties of the polymer and the electric properties of the conductive metal (author)
Wu, Jianlan; Silbey, Robert J; Cao, Jianshu
2013-05-17
An asymptotic scaling theory is presented using the conceptual basis of trapping-free subspace (i.e., orthogonal subspace) to establish the generic mechanism of optimal efficiency of excitation energy transfer in light-harvesting systems. A quantum state orthogonal to the trap will exhibit noise-assisted transfer, clarifying the significance of initial preparation. For such an initial state, the efficiency is enhanced in the weak damping limit (⟨t⟩ ∼ 1/Γ), and suppressed in the strong damping limit (⟨t⟩ ∼ Γ), analogous to Kramers turnover in classical rate theory. An interpolating expression ⟨t⟩ = A/Γ + B + CΓ quantitatively describes the trapping time over the entire range of the dissipation strength, and predicts the optimal efficiency at Γ(opt) ∼ J for homogenous systems. In the presence of static disorder, the scaling law of transfer time with respect to dephasing rate changes from linear to square root, suggesting a weaker dependence on the environment. The prediction of the scaling theory is verified in a symmetric dendrimer system by numerically exact quantum calculations. Though formulated in the context of excitation energy transfer, the analysis and conclusions apply in general to open quantum processes, including electron transfer, fluorescence emission, and heat conduction.
78 FR 72813 - Definitions of Transmittal of Funds and Funds Transfer
2013-12-04
... means (e.g., electronic terminal, telephone, computer, online banking, magnetic tape, etc.) for the... Compliance Section, (202) 973- 6163, Division of Banking Supervision and Regulation, or Clinton Chen... purchase or sale of certain securities or commodities.\\18\\ Wire or other similar transfers conducted...
Liang, X. S.
2016-02-01
Central at the processes of mean-eddy-turbulence interaction, e.g., mesoscale eddy shedding, relaminarization, etc., is the transfer of energy among different scales. The existing classical transfers, however, do not take into account the issue of energy conservation and, therefore, are not faithful representations of the real interaction processes, which are fundamentally a redistribution of energy among scales. Based on a new analysis machinery, namely, multiscale window transform (Liang and Anderson, 2007), we were able to obtain a formula for this important processes, with the property of energy conservation a naturally embedded property. This formula has a form reminiscent of the Poisson bracket in Hamiltonian dynamics. It has been validated with many benchmark processes, and, particularly, has been applied with success to control the eddy shedding behind a bluff body. Presented here will be an application study of the instabilities and mean-eddy interactions in the Kuroshio Extension (KE) region. Generally, it is found that the unstable KE jet fuels the mesoscale eddies, but in the offshore eddy decaying region, the cause-effect relation reverses: it is the latter that drive the former. On the whole the eddies act to decelerate the jet in the upstream, whereas accelerating it downstream.
Heat transfer analysis in internally-cooled fuel elements by means of a conformal mapping approach
International Nuclear Information System (INIS)
Sarmiento, G.S.; Laura, P.A.A.
1981-01-01
The present paper deals with an approximate solution of the steady-state heat conduction problem in internally cooled fuel elements of fast breeder reactors. Explicit expressions for the dimensionless temperature distribution in terms of the governing physical and geometrical parameters are determined by means of a coupled conformal mapping-variational approach. The results obtained are found to be in very good agreement with those calculated by means of a finite element code. (orig.)
Investigating wireless power transfer
St John, Stuart A.
2017-09-01
Understanding Physics is a great end in itself, but is also crucial to keep pace with developments in modern technology. Wireless power transfer, known to many only as a means to charge electric toothbrushes, will soon be commonplace in charging phones, electric cars and implanted medical devices. This article outlines how to produce and use a simple set of equipment to both demonstrate and investigate this phenomenon. It presents some initial findings and aims to encourage Physics educators and their students to conduct further research, pushing the bounds of their understanding.
International Nuclear Information System (INIS)
Salem, Ahmed M.
2007-01-01
The problem of flow and heat transfer of an electrically conducting viscoelastic fluid over a continuously stretching sheet in the presence of a uniform magnetic field is analyzed for the case of power-law variation in the sheet temperature. The fluid viscosity and thermal conductivity are assumed to vary as a function of temperature. The basic equations comprising the balance laws of mass, linear momentum, and energy modified to include the electromagnetic force effect, the viscous dissipation, internal heat generation or absorption and work due to deformation are solved numerically
International Nuclear Information System (INIS)
Narayan Prabhu, K.; Ravishankar, B.N.
2003-01-01
For successful modelling of the solidification process, a reliable heat transfer boundary condition data is required. These boundary conditions are significantly influenced by the casting and mould parameters. In the present work, the effect of sodium modification melt treatment on casting/chill interfacial heat transfer during upward solidification of an Al-13% Si alloy against metallic chills is investigated using thermal analysis and inverse modelling techniques. In the presence of chills, modification melt treatment resulted in an increase in the cooling rate of the solidifying casting near the casting/chill interfacial region. The corresponding interfacial heat flux transients and electrical conductivities are also found to be higher. This is attributed to (i) improvement in the casting/chill interfacial thermal contact condition brought about by the decrease in the surface tension of the liquid metal on addition of sodium and (ii) increase in the electronic heat conduction in the initial solidified shell due to change in the morphology of silicon from a acicular type to a fine fibrous structure and increase in the ratio of the modification rating to the secondary dendrite arm spacing
Determination of transference numbers in ionic conductors by the EMF method with active load
International Nuclear Information System (INIS)
Gorelov, V.P.
1988-01-01
Method for determining transference numbers in ionic conductors by means of measuring EMF of concentration cell with accout of polarization resistance of electrodes is suggested. The method enables to determine easily very small transference numbers of electron component against the background of predominating ionic conductivity. To illustrate the method there were determined transference numbers for the sample of industrial solid electrolyte in the cell; O 2 Pt|0.91ZrO 2 +0.09Y 2 O 3 |Pt, air
Orr, Jonathan J.; Hulse-Killacky, Diana
2006-01-01
Concepts of voice, meaning, mutual construction of knowledge, and transfer of learning are presented in this paper as critical ingredients that support the teaching of group work from an ecological perspective. Examples of these concepts are given to illustrate their application in group work classes. (Contains 1 table.)
Menezes de Oliveira, Marilia; Wen, Peng; Ahfock, Tony
2016-09-01
This paper focuses on electroconvulsive therapy (ECT) and head models to investigate temperature profiles arising when anisotropic thermal and electrical conductivities are considered in the skull layer. The aim was to numerically investigate the threshold for which this therapy operates safely to the brain, from the thermal point of view. A six-layer spherical head model consisting of scalp, fat, skull, cerebro-spinal fluid, grey matter and white matter was developed. Later on, a realistic human head model was also implemented. These models were built up using the packages from COMSOL Inc. and Simpleware Ltd. In these models, three of the most common electrode montages used in ECT were applied. Anisotropic conductivities were derived using volume constraint and included in both spherical and realistic head models. The bio-heat transferring problem governed by Laplace equation was solved numerically. The results show that both the tensor eigenvalues of electrical conductivity and the electrode montage affect the maximum temperature, but thermal anisotropy does not have a significant influence. Temperature increases occur mainly in the scalp and fat, and no harm is caused to the brain by the current applied during ECT. The work assures the thermal safety of ECT and also provides a numerical method to investigate other non-invasive therapies. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Local heat transfer coefficient in a fluidized bed
International Nuclear Information System (INIS)
Al-Busoul, A. M.
1999-01-01
This paper presents an experimental study for the local heat transfer coefficient. The experiments was conducted inside a reactor with inner diameter (I D = 142mm) at atmospheric conditions (temperature mean value = 29 deg.) The bed was heated by means of a parochial electric heater with a diameter of (d h = 29 mm) and a constant power of 5W. The following factors varied: particles type and diameter, fluid velocity, bed height and heater position inside the reactor. The results were presented and discussed. (author). 15 refs., 7 figs
Denys, S; Van Loey, A M; Hendrickx, M E
2000-01-01
A numerical heat transfer model for predicting product temperature profiles during high-pressure thawing processes was recently proposed by the authors. In the present work, the predictive capacity of the model was considerably improved by taking into account the pressure dependence of the latent heat of the product that was used (Tylose). The effect of pressure on the latent heat of Tylose was experimentally determined by a series of freezing experiments conducted at different pressure levels. By combining a numerical heat transfer model for freezing processes with a least sum of squares optimization procedure, the corresponding latent heat at each pressure level was estimated, and the obtained pressure relation was incorporated in the original high-pressure thawing model. Excellent agreement with the experimental temperature profiles for both high-pressure freezing and thawing was observed.
Liu, Gaisheng; Zheng, Chunmiao; Gorelick, Steven M.
2007-01-01
This paper evaluates the dual‐domain mass transfer (DDMT) model to represent transport processes when small‐scale high‐conductivity (K) preferential flow paths (PFPs) are present in a homogenous porous media matrix. The effects of PFPs upon solute transport were examined through detailed numerical experiments involving different realizations of PFP networks, PFP/matrix conductivity contrasts varying from 10:1 to 200:1, different magnitudes of effective conductivities, and a range of molecular diffusion coefficients. Results suggest that the DDMT model can reproduce both the near‐source peak and the downstream low‐concentration spreading observed in the embedded dendritic network when there are large conductivity contrasts between high‐K PFPs and the low‐K matrix. The accuracy of the DDMT model is also affected by the geometry of PFP networks and by the relative significance of the diffusion process in the network‐matrix system.
The monophasic action potential upstroke: a means of characterizing local conduction.
Levine, J H; Moore, E N; Kadish, A H; Guarnieri, T; Spear, J F
1986-11-01
The upstrokes of monophasic action potentials (MAPs) recorded with an extracellular pressure electrode were characterized in isolated canine tissue preparations in vitro. The characteristics of the MAP upstroke were compared with those of the local action potential foot as well as with the characteristics of approaching electrical activation during uniform and asynchronous conduction. The upstroke of the MAP was exponential during uniform conduction. The time constant of rise of the MAP upstroke (TMAP) correlated with that of the action potential foot (Tfoot): TMAP + 1.01 Tfoot + 0.50; r2 = .80. Furthermore, changes in Tfoot with alterations in cycle length were associated with similar changes in TMAP: Tfoot = 1.06 TMAP - 0.11; r2 = .78. In addition, TMAP and Tfoot both deviated from exponential during asynchronous activation; the inflections that developed in the MAP upstroke correlated in time with intracellular action potential upstrokes that were asynchronous in onset in these tissues. Finally, the field of view of the MAP was determined and was found to be dependent in part on tissue architecture and the space constant. Specifically, the field of view of the MAP was found to be greater parallel compared with transverse to fiber orientation (6.02 +/- 1.74 vs 3.03 +/- 1.10 mm; p less than .01). These data suggest that the MAP upstroke may be used to define and characterize local electrical activation. The relatively large field of view of the MAP suggests that this technique may be a sensitive means to record focal membrane phenomena in vivo.
Voltage tunability of thermal conductivity in ferroelectric materials
Ihlefeld, Jon; Hopkins, Patrick Edward
2016-02-09
A method to control thermal energy transport uses mobile coherent interfaces in nanoscale ferroelectric films to scatter phonons. The thermal conductivity can be actively tuned, simply by applying an electrical potential across the ferroelectric material and thereby altering the density of these coherent boundaries to directly impact thermal transport at room temperature and above. The invention eliminates the necessity of using moving components or poor efficiency methods to control heat transfer, enabling a means of thermal energy control at the micro- and nano-scales.
Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface
Gruenewald, Marco; Schirra, Laura K.; Winget, Paul; Kozlik, Michael; Ndione, Paul F.; Sigdel, Ajaya K.; Berry, Joseph J.; Forker, Roman; Bredas, Jean-Luc; Fritz, Torsten; Monti, Oliver L. A.
2015-01-01
with localized states (the shallow donors) in the substrate and charge back-donation, resulting in an effectively integer charge transfer across the interface. Charge transfer is thus not merely a question of locating the Fermi level above the PTCDA electron
International Nuclear Information System (INIS)
Lyczkowski, R.W.; Solbrig, C.W.; Gidaspow, D.
1982-01-01
A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions which may arise in nuclear waste repository ventilation corridors. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Simplifications are made to decouple the convective heat transfer problem from the far field conduction problem, but peripheral conduction is retained. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionsless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition. Nusselt numbers for the case of constant temperature on the top and bottom walls and constant heat flux on the side walls exhibited unexpected behavior. (orig.)
International Nuclear Information System (INIS)
Lyczkowski, R.W.; Solbrig, C.W.; Gidaspow, D.
1980-01-01
A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions which may arise in nuclear waste repository ventilation corridors. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Simplifications are made to decouple the convective heat transfer problem for the far field conduction problem, but peripheral conduction is retained. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition. Nusselt numbers for the case of constant temperature on the top and bottom walls and constant heat flux on the side walls exhibited unexpected behavior
Energy Technology Data Exchange (ETDEWEB)
Lyczkowski, R W [Institute of Gas Technology, Chicago, IL (USA); Solbrig, C W [EG and G Idaho, Inc., Idaho Falls (USA); Gidaspow, D [Illinois Inst. of Tech., Chicago (USA). Dept. of Chemical Engineering
1982-02-01
A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions which may arise in nuclear waste repository ventilation corridors. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Simplifications are made to decouple the convective heat transfer problem from the far field conduction problem, but peripheral conduction is retained. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionsless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition. Nusselt numbers for the case of constant temperature on the top and bottom walls and constant heat flux on the side walls exhibited unexpected behavior.
Bai, Shengchi; Wang, Haifeng; Yang, Hui; Zhang, He; Guo, Xingzhong
2018-02-01
Silver nanowires (AgNWs)-polyurethane (PU) composite transparent conductive films were fabricated via transfer method using AgNWs conductive inks and polyurethane as starting materials, and the effects of post-treatments including heat treatment, NaCl solution bath and HCl solution bath for AgNWs film on the sheet resistance and transmittance of the composite films were respectively investigated in detail. AgNWs networks are uniformly embedded in the PU layer to improve the adhesion and reduce the surface roughness of AgNWs-PU composite films. Heat treatment can melt and weld the nanowires, and NaCl and HCl solution baths promote the dissolution and re-deposition of silver and the dissolving of the polymer, both which form conduction pathways and improve contact of AgNWs for reducing the sheet resistance. Smooth and flexible AgNWs-PU composite film with a transmittance of 85% and a sheet resistance of 15 Ω · sq‑1 is obtained after treated in 0.5 wt% HCl solution bath for 60 s, and the optoelectronic properties of the resultant composite film can maintain after 1000 cycles of bending and 100 days.
Hata, K.; Fukuda, K.; Masuzaki, S.
2018-04-01
Twisted-tape-induced swirl-flow heat transfer due to exponentially increasing heat inputs with various exponential periods ( Q = Q 0 exp(t/τ), τ = 6.04 to 23.07 s) and twisted-tape-induced pressure drop was systematically measured for various mass velocities ( G = 4115 to 13,656 kg/m2 s), inlet liquid temperatures ( T in = 285.88 to 299.09 K), and inlet pressures ( P in = 847.45 to 943.29 kPa) using an experimental water loop flow. Measurements were made over a 59.2-mm effective length and three sections (upper, middle, and lower positions), within which four potential taps were spot-welded onto the outer surface of a 6-mm-inner-diameter, 69.6-mm-heated length, 0.4-mm-thickness platinum circular test tube. Type SUS304 twisted tapes with a width w = 5.6 mm, a thickness δ T = 0.6 mm, a total length l = 372 mm, and twist ratios y = 2.39 and 4.45 were employed in this study. The RANS equations (Reynolds Averaged Navier-Stokes Simulation) with a k-ɛ turbulence model for a circular tube 6 mm in diameter and 636 mm in length were numerically solved for heating of water with a heated section 6 mm in diameter and 70 mm in length using the CFD code, under the same conditions as the experimental ones and considering the temperature dependence of the thermo-physical properties concerned. The theoretical values of surface heat flux q on the circular tubes with twisted tapes with twist ratios y of 2.39 and 4.45 were found to be almost in agreement with the corresponding experimental values of heat flux q, with deviations of less than 30% for the range of temperature difference between the average heater inner surface temperature and the liquid bulk mean temperature ΔT L [ = T s,av - T L , T L = ( T in + T out )/2] considered in this study. The theoretical values of the local surface temperature T s , local average liquid temperature T f,av , and local liquid pressure drop ΔP x were found to be within almost 15% of the corresponding experimental ones. The thickness of the
Lee, Jung-Yeol; Park, Jeong-Hoon; Park, Hee-Deung
2017-10-01
Direct interspecies electron transfer (DIET) between exoelectrogenic bacteria and methanogenic archaea via conductive materials is reported as an efficient method to produce methane in anaerobic organic waste digestion. A voltage can be applied to the conductive materials to accelerate the DIET between two groups of microorganisms to produce methane. To evaluate this hypothesis, two sets of anaerobic serum bottles with and without applied voltage were used with a pair of graphite rods as conductive materials to facilitate DIET. Initially, the methane production rate was similar between the two sets of serum bottles, and later the serum bottles with an applied voltage of 0.39V showed a 168% higher methane production rate than serum bottles without an applied voltage. In cyclic voltammograms, the characteristic redox peaks for hydrogen and acetate oxidation were identified in the serum bottles with an applied voltage. In the microbial community analyses, hydrogenotrophic methanogens (e.g. Methanobacterium) were observed to be abundant in serum bottles with an applied voltage, while methanogens utilizing carbon dioxide (e.g., Methanosaeta and Methanosarcina) were dominant in serum bottles without an applied voltage. Taken together, the applied voltage on conductive materials might not be effective to promote DIET in methane production. Instead, it appeared to generate a condition for hydrogenotrophic methanogenesis. Copyright © 2017 Elsevier Ltd. All rights reserved.
Zhang, Shuo; Chang, Jiali; Lin, Chao; Pan, Yiran; Cui, Kangping; Zhang, Xiaoyuan; Liang, Peng; Huang, Xia
2017-12-01
To understand how granular activated carbon (GAC) promotes methanogenesis, batch tests of CH 4 production potential in anaerobic serum bottles with addition of GAC or not were conducted. Tests showed that GAC promoted methanogenesis remarkably, but the non-conductive zeolite did not. The qPCR demonstrated that the biomass on GAC contributed little to the promotion. High-throughput sequencing data implied that promotion was related with direct interspecies electron transfer between Geobacteraceae and Methanosaetaceae. According to the c-type cytochromes (c-Cyts) response to the supplement of GAC, it was speculated that GAC may play the role of c-Cyts' substitution. In the undefined cultures, the phenomenon that c-Cyts were repressed by GAC was first observed. This research provided new evidence to microbial mechanism of promoting methanogenesis via GAC. Copyright © 2017 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Grigull, U.; Sandner, H.
1984-01-01
Included are discussions of rates of heat transfer by conduction, the effects of varying and changing properties, thermal explosions, distributed heat sources, moving heat sources, and non-steady three-dimensional conduction processes. Throughout, the importance of thinking both numerically and symbolically is stressed, as this is essential to the development of the intuitive understanding of numerical values needed for successful designing. Extensive tables of thermophysical properties, including thermal conductivity and diffusivity, are presented. Also included are exact and approximate solutions to many of the problems that arise in practical situations
Conjugate heat transfer for turbulent flow in a thick walled plain pipe
Directory of Open Access Journals (Sweden)
Canli Eyub
2018-01-01
Full Text Available Laminar and turbulent flow have their own characteristics in respect of heat transfer in pipes. While conjugate heat transfer is a major concern for a thick walled pipe with laminar flow inside it, there are limited studies about a turbulent flow in a thick walled plain pipe considering the conjugate heat transfer. In order to conduct such a work by means of in-house developed code, it was desired to make a preliminary investigation with commercially available CFD codes. ANSYS CFD was selected as the tool since it has a positive reputation in the literature for reliability. Defined heat transfer problem was solved with SIMPLE and Coupled Schemes for pressure velocity coupling and results are presented accordingly.
Heat transfer monitoring by means of the hot wire technique and finite element analysis software.
Hernández Wong, J; Suarez, V; Guarachi, J; Calderón, A; Rojas-Trigos, J B; Juárez, A G; Marín, E
2014-01-01
It is reported the study of the radial heat transfer in a homogeneous and isotropic substance with a heat linear source in its axial axis. For this purpose, the hot wire characterization technique has been used, in order to obtain the temperature distribution as a function of radial distance from the axial axis and time exposure. Also, the solution of the transient heat transport equation for this problem was obtained under appropriate boundary conditions, by means of finite element technique. A comparison between experimental, conventional theoretical model and numerical simulated results is done to demonstrate the utility of the finite element analysis simulation methodology in the investigation of the thermal response of substances. Copyright © 2013 Elsevier Ltd. All rights reserved.
Combined convective heat transfer of liquid sodium flowing across tube banks
International Nuclear Information System (INIS)
Ma, Ying; Sugiyama, Ken-ichiro; Ishiguro, Ryoji
1989-01-01
In order to clarify the heat transfer characteristics of combined convection of liquid sodium, a numerical analysis is performed for liquid sodium which flows through a single horizontal row of tubes in the direction of gravity. The correlation of heat transfer characteristics between liquid sodium and ordinary fluids is also discussed. The heat transfer characteristics at large Reynolds numbers are improved when the Richardson number is increased, and the improvement rate is enlarged with increase in p/d value, since convection effect is relatively large. However heat transfer coefficients do not differ from those of forced convection at small Reynolds numbers even when the Richardson number reaches a high value because of conduction effect. A good consistence of heat transfer characteristics of combined convection between liquid sodium and air is obtained at the same Peclet number and Richardson number. This means that the fundamental heat transfer characteristics of combined convection of liquid sodium can be investigated with ordinary fluids. (author)
Directory of Open Access Journals (Sweden)
Vasyl Chekurin
2017-01-01
Full Text Available The mathematical model for describing combined conductive-radiative heat transfer in a dielectric layer, which emits, absorbs, and scatters IR radiation both in its volume and on the boundary, has been considered. A nonlinear stationary boundary-value problem for coupled heat and radiation transfer equations for the layer, which exchanges by energy with external medium by convection and radiation, has been formulated. In the case of optically thick layer, when its thickness is much more of photon-free path, the problem becomes a singularly perturbed one. In the inverse case of optically thin layer, the problem is regularly perturbed, and it becomes a regular (unperturbed one, when the layer’s thickness is of order of several photon-free paths. An iterative method for solving of the unperturbed problem has been developed and its convergence has been tested numerically. With the use of the method, the temperature field and radiation fluxes have been studied. The model and method can be used for development of noncontact methods for temperature testing in dielectrics and for nondestructive determination of its radiation properties on the base of the data obtained by remote measuring of IR radiation emitted by the layer.
Stay connected: Electrical conductivity of microbial aggregates.
Li, Cheng; Lesnik, Keaton Larson; Liu, Hong
2017-11-01
The discovery of direct extracellular electron transfer offers an alternative to the traditional understanding of diffusional electron exchange via small molecules. The establishment of electronic connections between electron donors and acceptors in microbial communities is critical to electron transfer via electrical currents. These connections are facilitated through conductivity associated with various microbial aggregates. However, examination of conductivity in microbial samples is still in its relative infancy and conceptual models in terms of conductive mechanisms are still being developed and debated. The present review summarizes the fundamental understanding of electrical conductivity in microbial aggregates (e.g. biofilms, granules, consortia, and multicellular filaments) highlighting recent findings and key discoveries. A greater understanding of electrical conductivity in microbial aggregates could facilitate the survey for additional microbial communities that rely on direct extracellular electron transfer for survival, inform rational design towards the aggregates-based production of bioenergy/bioproducts, and inspire the construction of new synthetic conductive polymers. Copyright © 2017 Elsevier Inc. All rights reserved.
77 FR 72783 - Notice of Proposed Rulemaking: Definitions of Transmittal of Funds and Funds Transfer
2012-12-06
... through electronic means (electronic terminal, telephone, computer, online banking, magnetic tape, etc... Financial Analyst, (202) 973- 6163, Division of Banking Supervision and Regulation, or Dena L. Milligan... of certain securities or commodities.\\17\\ Wire or other similar transfers conducted through Fedwire...
International Nuclear Information System (INIS)
Mahapatra, S.K.; Dandapat, B.K.; Sarkar, A.
2006-01-01
The current study addresses the mathematical modeling aspects of coupled conductive and radiative heat transfer in the presence of absorbing, emitting and isotropic scattering gray medium within two-dimensional square enclosure. A blended method where the concepts of modified differential approximation employed by combining discrete ordinate method and spherical harmonics method, has been developed for modeling the radiative transport equation. The gray participating medium is bounded by isothermal walls of two-dimensional enclosure which are considered to be opaque, diffuse and gray. The effect of various influencing parameters i.e., radiation-conduction parameter, surface emissivity, single scattering albedo and optical thickness has been illustrated. The adaptability of the present method has also been addressed
Sinthiptharakoon, K.; Sapcharoenkun, C.; Nuntawong, N.; Duong, B.; Wutikhun, T.; Treetong, A.; Meemuk, B.; Kasamechonchung, P.; Klamchuen, A.
2018-05-01
The semicontinuous gold film, enabling various electronic applications including development of surface-enhanced Raman scattering (SERS) substrate, is investigated using conductive atomic force microscopy (CAFM) and Kelvin probe force microscopy (KPFM) to reveal and investigate local electronic characteristics potentially associated with SERS generation of the film material. Although the gold film fully covers the underlying silicon surface, CAFM results reveal that local conductivity of the film is not continuous with insulating nanoislands appearing throughout the surface due to incomplete film percolation. Our analysis also suggests the two-step photo-induced charge transfer (CT) play the dominant role in the enhancement of SERS intensity with strong contribution from free electrons of the silicon support. Silicon-to-gold charge transport is illustrated by KPFM results showing that Fermi level of the gold film is slightly inhomogeneous and far below the silicon conduction band. We propose that inhomogeneity of the film workfunction affecting chemical charge transfer between gold and Raman probe molecule is associated with the SERS intensity varying across the surface. These findings provide deeper understanding of charge transfer mechanism for SERS which can help in design and development of the semicontinuous gold film-based SERS substrate and other electronic applications.
International Nuclear Information System (INIS)
Meuschke, R.E.; Harper, M.J.; Stefko, D.J.
1991-01-01
This paper describes a nuclear power plant having an auxiliary building, a containment building having the wall, a track extending through a transfer tube within the containment wall, and a fuel transfer system for moving fuel assemblies along the track between the auxiliary building side and the containment building side of the containment wall. It comprises: a car having wheels for movement along spaced rails of the track and further having a carrying basket for one or more fuel assemblies; winch means located on the auxiliary building side of the containment wall and above the water level existing over the track during refueling operations to drive the car along the track; first cable means and second cable means extending substantially vertically downward from the winch means to the tack level; first sheave means for directing the first and the second cable means substantially in the horizontal direction along the track; means for securing the first cable means to the car so that winch pulling force on the first cable means drives the car away from the containment building; second sheave means located near the containment end of the transfer tube
Web Transfer Over Satellites Being Improved
Allman, Mark
1999-01-01
Extensive research conducted by NASA Lewis Research Center's Satellite Networks and Architectures Branch and the Ohio University has demonstrated performance improvements in World Wide Web transfers over satellite-based networks. The use of a new version of the Hypertext Transfer Protocol (HTTP) reduced the time required to load web pages over a single Transmission Control Protocol (TCP) connection traversing a satellite channel. However, an older technique of simultaneously making multiple requests of a given server has been shown to provide even faster transfer time. Unfortunately, the use of multiple simultaneous requests has been shown to be harmful to the network in general. Therefore, we are developing new mechanisms for the HTTP protocol which may allow a single request at any given time to perform as well as, or better than, multiple simultaneous requests. In the course of study, we also demonstrated that the time for web pages to load is at least as short via a satellite link as it is via a standard 28.8-kbps dialup modem channel. This demonstrates that satellites are a viable means of accessing the Internet.
International Nuclear Information System (INIS)
Frederick, K.; Foote, L.; Ciborowski, J.
2010-01-01
Algal biofilms are a fundamental contributor to wetland productivity. The films maintain high turnover rates, nutrient uptake and storage capacities are prevalent in shallow water as well as over large littoral zones. This study investigated biofilm transfer techniques as a means of accelerating carbon capture, plant production, and colonization in reclaimed oil sand wetlands affected by process water. The study examined the productivity of transferred biofilms and their ability to accelerate succession; methods of transferring biofilms; and the community composition of algae in relation to other substrates. Microcosms with 4 types of substrates were submersed in experimental trenches containing either process water or natural water. Dissolved oxygen, chlorophyll, and biomass standing crop sampling was conducted at intervals throughout a 1-year period. Analysis of variance (ANOVA) was conducted to compare the substrate types. Results of the study will be used to assess the impacts of oil sands process affected materials (OSPM) on benthic biofilm productivity and the initial carbon accumulation process.
Energy Technology Data Exchange (ETDEWEB)
Frederick, K.; Foote, L. [Alberta Univ., Edmonton, AB (Canada); Ciborowski, J. [Windsor Univ., ON (Canada)
2010-07-01
Algal biofilms are a fundamental contributor to wetland productivity. The films maintain high turnover rates, nutrient uptake and storage capacities are prevalent in shallow water as well as over large littoral zones. This study investigated biofilm transfer techniques as a means of accelerating carbon capture, plant production, and colonization in reclaimed oil sand wetlands affected by process water. The study examined the productivity of transferred biofilms and their ability to accelerate succession; methods of transferring biofilms; and the community composition of algae in relation to other substrates. Microcosms with 4 types of substrates were submersed in experimental trenches containing either process water or natural water. Dissolved oxygen, chlorophyll, and biomass standing crop sampling was conducted at intervals throughout a 1-year period. Analysis of variance (ANOVA) was conducted to compare the substrate types. Results of the study will be used to assess the impacts of oil sands process affected materials (OSPM) on benthic biofilm productivity and the initial carbon accumulation process.
International Nuclear Information System (INIS)
Saad, M.A.
1985-01-01
Heat transfer takes place between material systems as a result of a temperature difference. The transmission process involves energy conversions governed by the first and second laws of thermodynamics. The heat transfer proceeds from a high-temperature region to a low-temperature region, and because of the finite thermal potential, there is an increase in entropy. Thermodynamics, however, is concerned with equilibrium states, which includes thermal equilibrium, irrespective of the time necessary to attain these equilibrium states. But heat transfer is a result of thermal nonequilibrium conditions, therefore, the laws of thermodynamics alone cannot describe completely the heat transfer process. In practice, most engineering problems are concerned with the rate of heat transfer rather than the quantity of heat being transferred. Resort then is directed to the particular laws governing the transfer of heat. There are three distinct modes of heat transfer: conduction, convection, and radiation. Although these modes are discussed separately, all three types may occur simultaneously
Experimental Study of Flow Boiling Heat Transfer in a Horizontal Microfin Tube
Yu, Jian; Koyama, Shigeru; Momoki, Satoru
1995-01-01
An experimental study on flow boiling heat transfer in a horizontal microfin tube is conducted with pure refrigerants HFC134a, HCFC123 and HCFC22 using a water-heated double-tube type test section. The test microfin tube is a copper tube having the following dimensions: 8.37mm mean inside diameter, 0.168mm fin height, 60fin number and 18 degree of helix angle. The local heat transfer coefficients for both counter and parallel flows are measured in a range of heat flux of 1 to 93W/m^2, mass ve...
High-temperature thermal conductivity of uranium chromite and uranium niobate
International Nuclear Information System (INIS)
Fedoseev, D.V.; Varshavskaya, I.G.; Lavrent'ev, A.V.; Oziraner, S.N.; Kuznetsova, D.G.
1979-01-01
The technique of determining thermal conductivity coefficient of uranium niobate and uranium chromite on heating with laser radiation is described. Determined is the coefficient of free-convective heat transfer (with provision for a conduction component) by means of a standard specimen. The thermal conductivity coefficients of uranium chromite and niobate were measured in the 1300-1700 K temperature range. The results are presented in a diagram form. It has been calculated, that the thermal conductivity coefficient for uranium niobate specimens is greater in comparison with uranium chromite specimens. The thermal conductivity coefficients of the materials mentioned depend on temperature very slightly. Thermal conductivity of the materials considerably depends on their porosity. The specimens under investigation were fabricated by the pressing method and had the following porosity: uranium chromite - 30 %, uranium niobate - 10 %. Calculation results show, that thermal conductivity of dense uranium chromite is higher than thermal conductivity of dense uranium niobate. The experimental error equals approximately 20 %, that is mainly due to the error of measuring the temperature equal to +-25 deg, with a micropyrometer
Benefit Transfer Studies: Myths, Pragmatism, and Idealism
Boyle, Kevin J.; Bergstrom, John C.
1992-03-01
Benefit transfer has been an ongoing, practical analysis for years in legal proceedings and government policy analyses where timely benefit estimates are critically dependent on the use of existing data. Most benefit transfer studies to date have been conducted behind closed doors and have not been open to scholarly review, and no systematic research agenda has been established to determine whether benefit transfer estimates are valid for public policy analyses. In this paper we propose a systematic, conceptual foundation for conducting benefit transfer studies, and suggest a research agenda to identify conditions under which valid benefit transfer estimates can be derived. We conclude, however, that this research agenda must be accompanied by improved conduct and reporting of original valuation studies before benefit transfer can become a widely used tool in public policy analyses.
Energy Technology Data Exchange (ETDEWEB)
Nechtschein, M. [Commissariat a l' energie atomique et aux energies alternatives - CEA, Laboratoire de Resonance Magnetique (France)
1963-07-01
As some organic bodies simultaneously display semi-conducting properties and a paramagnetism, this report addresses the study of conduction in organic bodies. The author first briefly recalls how relationships between conductibility and Electron Paramagnetic Resonance (EPR) can be noticed in a specific case (mineral and metallic semiconductors). He discusses published results related to paramagnetism and conductibility in organic bodies. He reviews various categories of organic bodies in which both properties are simultaneously present. He notably addresses radical molecular crystals, non-radical molecular crystals, charge transfer complexes, pyrolyzed coals, and pseudo-ferromagnetic organic structures. He discusses the issue of relationships between conduction (charge transfer by electrons) and ERP (which reveals the existence of non-paired electrons which provide free spins)
Madhusudana, Chakravarti V
2013-01-01
The work covers bothÂ theoretical and practical aspects of thermal contact conductance. The theoretical discussionÂ focuses onÂ heat transfer through spots, joints, and surfaces, as well as the role of interstitial materials (both planned and inadvertent). The practical discussion includes formulae and data that can be used in designing heat-transfer equipment for a variety of joints, including special geometries and configurations. All of the material has been updated to reflect the latest advances in the field.
Controlled Environment Specimen Transfer
DEFF Research Database (Denmark)
Damsgaard, Christian Danvad; Zandbergen, Henny W.; Hansen, Thomas Willum
2014-01-01
an environmental transmission electron microscope to an in situ X-ray diffractometer through a dedicated transmission electron microscope specimen transfer holder, capable of sealing the specimen in a gaseous environment at elevated temperatures. Two catalyst material systems have been investigated; Cu/ZnO/Al2O3...... transferred in a reactive environment to the environmental transmission electron microscope where further analysis on the local scale were conducted. The Co/Al2O3 catalyst was reduced in the environmental microscope and successfully kept reduced outside the microscope in a reactive environment. The in situ......Specimen transfer under controlled environment conditions, such as temperature, pressure, and gas composition, is necessary to conduct successive complementary in situ characterization of materials sensitive to ambient conditions. The in situ transfer concept is introduced by linking...
International Nuclear Information System (INIS)
Groshev, A.I.; Anisimov, V.V.; Kashcheev, V.M.; Khudasko, V.V.; Yur'ev, Yu.S.
1987-01-01
The effect of wall material on convective heat transfer of turbulent gas flow in an annular tube with account of longitudinal diffusion both in the wall and in the liquid is studied numerically. The conjugated problem is solved for P r =0.7 (Re=10 4 -10 6 ). Based on numerical calculations it is stated that thermal conductivity of the wall and gas essentially affects the degree of preliminary heating of liquid in the range of a non-heated section
Control of the electrode metal transfer by means of the welding current pulse generator
Knyaz'kov, A.; Pustovykh, O.; Verevkin, A.; Terekhin, V.; Shachek, A.; Knyaz'kov, S.; Tyasto, A.
2016-04-01
The paper presents a generator of welding current pulses to transfer an electrode metal into the molten pool. A homogeneous artificial line is used to produce near rectangular pulses. The homogeneous artificial line provides the minimum heat input with in the pulse to transfer the electrode metal, and it significantly decreases the impact of disturbances affecting this transfer. The pulse frequency does not exceed 300 Hz, and the duration is 0.6 ÷ 0.9 ms.
SUNDÉN, B
2012-01-01
Presenting the basic mechanisms for transfer of heat, Introduction to Heat Transfer gives a deeper and more comprehensive view than existing titles on the subject. Derivation and presentation of analytical and empirical methods are provided for calculation of heat transfer rates and temperature fields as well as pressure drop. The book covers thermal conduction, forced and natural laminar and turbulent convective heat transfer, thermal radiation including participating media, condensation, evaporation and heat exchangers.
Effect of conducting polypyrrole on the transport properties of carbon nanotube yarn
International Nuclear Information System (INIS)
Foroughi, Javad; Kimiaghalam, Bahram; Ghorbani, Shaban Reza; Safaei, Farzad; Abolhasan, Mehran
2012-01-01
Experiments were conducted to measure the electrical conductivity in three types of pristine and carbon nanotube-polypyrrole (CNT-PPy) composite yarns and its dependence on over a wide temperature range. The experimental results fit well with the analytical models developed. The effective energy separation between localized states of the pristine CNT yarn is larger than that for both the electrochemically and chemically prepared CNT-PPy yarns. It was found that all samples are in the critical regime in the insulator–metal transition, or close to the metallic regime at low temperature. The electrical conductivity results are in good agreement with a Three Dimensional Variable Range Hopping model at low temperatures, which provides a strong indication that electron hopping is the main means of current transfer in CNT yarns at T < 100 K. We found that the two shell model accurately describes the electronic properties of CNT and CNT-PPy composite yarns in the temperature range of 5–350 K. - Highlights: ► We developed hybrid carbon nanotube conducting polypyrrole composite yarns. ► The main current transfer scheme in yarn is via three dimensional electrons hopping. ► Two shell model describes well electronic properties of yarns in range of 5-350 K.
DEFF Research Database (Denmark)
Rode, Carsten
1998-01-01
Analytical theory of transient heat conduction.Fourier's law. General heat conducation equation. Thermal diffusivity. Biot and Fourier numbers. Lumped analysis and time constant. Semi-infinite body: fixed surface temperature, convective heat transfer at the surface, or constant surface heat flux...
The influence of porosity on the thermal conductivity of irradiated UO2 fuel
International Nuclear Information System (INIS)
Bakker, K.; Kwast, H.; Cordfunke, E.H.P.
1994-12-01
The influence of porosity on the thermal conductivity of irradiated UO 2 fuel has been determined with the Finite Element Method (FEM). Light-microscopy photographs were made of the fuel. The pore shape and the pore distribution are entered in the FEM program from these photographs. The two dimensional (2D) thermal conductivity in the plane of the photograph is obtained from the FEM calculations. The 2D thermal conductivity, that has no physical meaning itself, is the lower limit of the three dimensional (3D) thermal conductivity. For three well defined pore shapes the relation is determined between the 2D thermal conductivity and the 3D thermal conductivity. From these computations a simple relation is obtained that transfers the 2D thermal conductivity into the 3D thermal conductivity, independent of the pore shape. The influence of porosity on the 3D thermal conductivity of irradiated UO 2 fuel and UO 2 fuel doped with Nb 2 O 5 was computed with the FEM. (orig.)
Heat transfer 1990. Proceedings of the ninth international heat transfer conference
International Nuclear Information System (INIS)
Hetsroni, G.
1990-01-01
This book contains the proceedings of the Ninth International Heat Transfer Conference. Included in Volume 3 are the following chapters: Refrigerant vapor condensation on a horizontal tube bundle. Local heat transfer in a reflux condensation inside a closed two-phase thermosyphon and surface temperature by means of a pulsed photothermal effects
Visualization of human heart conduction system by means of fluorescence spectroscopy
Venius, Jonas; Bagdonas, Saulius; Žurauskas, Edvardas; Rotomskis, Ricardas
2011-10-01
The conduction system of the heart is a specific muscular tissue, where a heartbeat signal originates and initiates the depolarization of the ventricles. The muscular origin makes it complicated to distinguish the conduction system from the surrounding tissues. A surgical intervention can lead to the accidental harm of the conduction system, which may eventually result in a dangerous obstruction of the heart functionality. Therefore, there is an immense necessity for developing a helpful method to visualize the conduction system during the operation time. The specimens for the spectroscopic studies were taken from nine diverse human hearts. The localization of distinct types of the tissue was preliminary marked by the pathologist and approved histologically after the spectral measurements. Variations in intensity, as well as in shape, were detected in autofluorescence spectra of different heart tissues. The most distinct differences were observed between the heart conduction system and the surrounding tissues under 330 and 380 nm excitation. The spectral region around 460 nm appeared to be the most suitable for an unambiguous differentiation of the human conduction system avoiding the absorption peak of blood. The visualization method, based on the intensity ratios calculated for two excitation wavelengths, was also demonstrated.
Does the atrioventricular node conduct?
Meijler, F.L.; Fisch, C.
1989-01-01
It is difficult to be certain wh en the term "conduction" was first applied to the transfer of atrial activation to the ventricles .' In 1894, Engelmann used the word "Leitung", which can be translated as "connection" or as "conduction" .2 In 1906, Tawara described the atrioventricular node,
Radiation and gas conduction heat transport across a helium dewer multilayer insulation system
Energy Technology Data Exchange (ETDEWEB)
Green, M.A. [Lawrence Berkeley Lab., CA (United States)
1995-02-01
This report describes a method for calculating mixed heat transfer through the multilayer insulation used to insulated a 4K liquid helium cryostat. The method described permits one to estimate the insulation potential for a multilayer insulation system from first principles. The heat transfer regimes included are: radiation, conduction by free molecule gas conduction, and conduction through continuum gas conduction. Heat transfer in the transition region between the two gas conduction regimes is also included.
New transfer functions for probing 3-D mantle conductivity from ground and sea
DEFF Research Database (Denmark)
Püthe, C.; Kuvshinov, A.; Olsen, Nils
2014-01-01
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...... 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...... 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...
Effective Thermal Conductivity For Drift-Scale Models Used In TSPA-SR
Energy Technology Data Exchange (ETDEWEB)
N.D. Francis
2001-01-25
The objective of this calculation is to develop a time dependent in-drift effective thermal conductivity parameter that will approximate heat conduction, thermal radiation, and natural convection heat transfer using a single mode of heat transfer (heat conduction). In order to reduce the physical and numerical complexity of the heat transfer processes that occur (and must be modeled) as a result of the emplacement of heat generating wastes, a single parameter will be developed that approximates all forms of heat transfer from the waste package surface to the drift wall (or from one surface exchanging heat with another). Subsequently, with this single parameter, one heat transfer mechanism (e.g., conduction heat transfer) can be used in the models. The resulting parameter is to be used as input in the drift-scale process-level models applied in total system performance assessments for the site recommendation (TSPA-SR). The format of this parameter will be a time-dependent table for direct input into the thermal-hydrologic (TH) and the thermal-hydrologic-chemical (THC) models.
Effective Thermal Conductivity For Drift-Scale Models Used In TSPA-SR
International Nuclear Information System (INIS)
N.D. Francis
2001-01-01
The objective of this calculation is to develop a time dependent in-drift effective thermal conductivity parameter that will approximate heat conduction, thermal radiation, and natural convection heat transfer using a single mode of heat transfer (heat conduction). In order to reduce the physical and numerical complexity of the heat transfer processes that occur (and must be modeled) as a result of the emplacement of heat generating wastes, a single parameter will be developed that approximates all forms of heat transfer from the waste package surface to the drift wall (or from one surface exchanging heat with another). Subsequently, with this single parameter, one heat transfer mechanism (e.g., conduction heat transfer) can be used in the models. The resulting parameter is to be used as input in the drift-scale process-level models applied in total system performance assessments for the site recommendation (TSPA-SR). The format of this parameter will be a time-dependent table for direct input into the thermal-hydrologic (TH) and the thermal-hydrologic-chemical (THC) models
DEFF Research Database (Denmark)
Bateman, I.J.; Brouwer, R.; Ferrini, S.
We develop and test guidance principles for benefits transfers. These argue that when transferring across relatively similar sites, simple mean value transfers are to be preferred but that when sites are relatively dissimilar then value function transfers will yield lower errors. The paper also...... provides guidance on the appropriate specification of transferable value functions arguing that these should be developed from theoretical rather than ad-hoc statistical principles. These principles are tested via a common format valuation study of water quality improvements across five countries. Results...... support our various hypotheses providing a set of principles for future transfer studies. The application also considers new ways of incorporating distance decay, substitution and framing effects within transfers and presents a novel water quality ladder....
International Nuclear Information System (INIS)
Lee, Jia-Mou; Yang, Dong-Chin; Lee, Ching-Ming; Ye, Lin-Xiu; Chang, Yao-Jen; Wu, Te-ho; Lee, Yen-Chi; Wu, Jong-Ching
2013-01-01
We present an alternative method of spin-transfer-induced magnetization switching for magnetic tunnel junctions (MTJs) using a conductive atomic force microscope (CAFM) with pulsed current. The nominal MTJ cells' dimensions were 200 × 400 nm 2 . The AFM probes were coated with a Pt layer via sputtering to withstand up to several milliamperes. The pulsed current measurements, with pulse duration varying from 5 to 300 ms, revealed a magnetoresistance ratio of up to 120%, and an estimated intrinsic switching current density, based on the thermal activation model, of 3.94 MA cm −2 . This method demonstrates the potential skill to characterize nanometre-scale magnetic devices. (paper)
Paramagnetic resonance and electronic conduction in organic semiconductors
International Nuclear Information System (INIS)
Nechtschein, M.
1963-01-01
As some organic bodies simultaneously display semi-conducting properties and a paramagnetism, this report addresses the study of conduction in organic bodies. The author first briefly recalls how relationships between conductibility and Electron Paramagnetic Resonance (EPR) can be noticed in a specific case (mineral and metallic semiconductors). He discusses published results related to paramagnetism and conductibility in organic bodies. He reviews various categories of organic bodies in which both properties are simultaneously present. He notably addresses radical molecular crystals, non-radical molecular crystals, charge transfer complexes, pyrolyzed coals, and pseudo-ferromagnetic organic structures. He discusses the issue of relationships between conduction (charge transfer by electrons) and ERP (which reveals the existence of non-paired electrons which provide free spins)
Energy Technology Data Exchange (ETDEWEB)
Ji, Pengfei; Zhang, Yuwen, E-mail: zhangyu@missouri.edu [Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, Missouri 65211 (United States); Yang, Mo [College of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China)
2013-12-21
The structural, dynamic, and vibrational properties during heat transfer process in Si/Ge superlattices are studied by analyzing the trajectories generated by the ab initio Car-Parrinello molecular dynamics simulation. The radial distribution functions and mean square displacements are calculated and further discussions are made to explain and probe the structural changes relating to the heat transfer phenomenon. Furthermore, the vibrational density of states of the two layers (Si/Ge) are computed and plotted to analyze the contributions of phonons with different frequencies to the heat conduction. Coherent heat conduction of the low frequency phonons is found and their contributions to facilitate heat transfer are confirmed. The Car-Parrinello molecular dynamics simulation outputs in the work show reasonable thermophysical results of the thermal energy transport process and shed light on the potential applications of treating the heat transfer in the superlattices of semiconductor materials from a quantum mechanical molecular dynamics simulation perspective.
International Nuclear Information System (INIS)
Ji, Pengfei; Zhang, Yuwen; Yang, Mo
2013-01-01
The structural, dynamic, and vibrational properties during heat transfer process in Si/Ge superlattices are studied by analyzing the trajectories generated by the ab initio Car-Parrinello molecular dynamics simulation. The radial distribution functions and mean square displacements are calculated and further discussions are made to explain and probe the structural changes relating to the heat transfer phenomenon. Furthermore, the vibrational density of states of the two layers (Si/Ge) are computed and plotted to analyze the contributions of phonons with different frequencies to the heat conduction. Coherent heat conduction of the low frequency phonons is found and their contributions to facilitate heat transfer are confirmed. The Car-Parrinello molecular dynamics simulation outputs in the work show reasonable thermophysical results of the thermal energy transport process and shed light on the potential applications of treating the heat transfer in the superlattices of semiconductor materials from a quantum mechanical molecular dynamics simulation perspective
Ji, Pengfei; Zhang, Yuwen; Yang, Mo
2013-12-01
The structural, dynamic, and vibrational properties during heat transfer process in Si/Ge superlattices are studied by analyzing the trajectories generated by the ab initio Car-Parrinello molecular dynamics simulation. The radial distribution functions and mean square displacements are calculated and further discussions are made to explain and probe the structural changes relating to the heat transfer phenomenon. Furthermore, the vibrational density of states of the two layers (Si/Ge) are computed and plotted to analyze the contributions of phonons with different frequencies to the heat conduction. Coherent heat conduction of the low frequency phonons is found and their contributions to facilitate heat transfer are confirmed. The Car-Parrinello molecular dynamics simulation outputs in the work show reasonable thermophysical results of the thermal energy transport process and shed light on the potential applications of treating the heat transfer in the superlattices of semiconductor materials from a quantum mechanical molecular dynamics simulation perspective.
International Nuclear Information System (INIS)
Luknarova, M.; Veis, S.
1976-01-01
The DC conductivity of a thermally produced plasma in a plasma diode has been measured in pure potassium vapour. The plasma diode consists of two tungsten electrodes heated to a temperature of 2200 K. A simple theory for determining the influence of the plasma sheaths on the measured conductivity was developed and experimental conditions were established under which the potential drops across the sheaths could be neglected. By measuring the DC conductivity of the plasma at temperatures ranging from 1250 to 1600 K the potassium momentum-transfer cross section has been obtained. The measured cross section (2.37 +- 0.24) x 10 -14 cm 2 at 1500 K is in good agreement with results of other workers. Results for the work function of tungsten in potassium vapour were also obtained. (author)
Wang, Zhaojie; Alaniz, Joseph E; Jang, Wanyoung; Garay, Javier E; Dames, Chris
2011-06-08
The thermal conductivity reduction due to grain boundary scattering is widely interpreted using a scattering length assumed equal to the grain size and independent of the phonon frequency (gray). To assess these assumptions and decouple the contributions of porosity and grain size, five samples of undoped nanocrystalline silicon have been measured with average grain sizes ranging from 550 to 64 nm and porosities from 17% to less than 1%, at temperatures from 310 to 16 K. The samples were prepared using current activated, pressure assisted densification (CAPAD). At low temperature the thermal conductivities of all samples show a T(2) dependence which cannot be explained by any traditional gray model. The measurements are explained over the entire temperature range by a new frequency-dependent model in which the mean free path for grain boundary scattering is inversely proportional to the phonon frequency, which is shown to be consistent with asymptotic analysis of atomistic simulations from the literature. In all cases the recommended boundary scattering length is smaller than the average grain size. These results should prove useful for the integration of nanocrystalline materials in devices such as advanced thermoelectrics.
Simple fabrication of active electrodes using direct laser transference
International Nuclear Information System (INIS)
Cavallo, P.; Coneo Rodriguez, R.; Broglia, M.; Acevedo, D.F.; Barbero, C.A.
2014-01-01
Highlights: •Electroactive materials can be transferred using a single pulse of laser light. •The transfer is made in air using a 6 ns pulse of Nd-YAG laser (532 or 1064 nm). •Conducting polymers films can be transferred maintaining the electroactivity. •Conducting polymer multilayers can be deposited using successive pulses. •Metallic (Au, Pt) transferred micro/nanoparticles are electrocatalytic. -- Abstract: Direct laser transference (DLT) method is applied to obtain electrodes modified with thin films of conducting polymers (CPs) or catalytic metals. A short (6–10 ns) pulse of laser light (second harmonic of Nd-YAG Laser, λ = 532 nm) is shined on the backside of a thin (<200 nm) film of the material to be transferred, which is deposited on a transparent substrate. The illuminated region heats up and the material (conducting polymer or metal) is thermally transferred to a solid target placed at short distance in air. In that ways, CPs are transferred onto polypropylene, glass, indium doped tin oxide (ITO), glassy carbon and gold films. In the same manner, electrocatalytic metals (platinum or gold) are transferred onto conductive substrates (glassy carbon or ITO films on glass). The films have been characterized by scanning electron microscopy, cyclic voltammetry, atomic force microscopy, UV-visible and Fourier Transform Infrared spectroscopies. The chemical, electrical and redox properties of the polymeric materials transferred remain unaltered after the transfer. Moreover, CP multilayers can be built applying DLT several times onto the same substrate. Besides polyaniline, it is shown that it is also possible to transfer functionalized polyanilines. The electrode modified with transferred Pt shows electrocatalytic activity toward methanol oxidation while ferricyanide shows a quasireversible behavior on electrodes modified with transferred Au. The method is simple and fast, works in air without complex environmental conditions and can produce active
International Nuclear Information System (INIS)
Mazon Matanzo, M.P.; Fernandez Gonzalez, J.
1976-01-01
A method based on the measurement of the electrical conductivity of potato tubers is described. By means of this method irradiated tubers can be distinguished from IPC treated tubers and control tubers. The values of conductivity in the control and INC treated tubers were about 0,2 millimhos/cm, while those in the irradiated tubers oscillated about 0,17 millimhos/cm. (author) [es
Submersible canned motor transfer pump
International Nuclear Information System (INIS)
Guardiani, R.F.; Pollick, R.D.; Nyilas, C.P.; Denmeade, T.J.
1997-01-01
A transfer pump is described which is used in a waste tank for transferring high-level radioactive liquid waste from a waste tank and having a column assembly, a canned electric motor means, and an impeller assembly with an upper impeller and a lower impeller connected to a shaft of a rotor assembly. The column assembly locates a motor housing with the electric motor means adjacent to the impeller assembly which creates an hydraulic head, and which forces the liquid waste, into the motor housing to cool the electric motor means and to cool and/or lubricate the radial and thrust bearing assemblies. Hard-on-hard bearing surfaces of the bearing assemblies and a ring assembly between the upper impeller and electric motor means grind large particles in the liquid waste flow. Slots in the static bearing member of the radial bearing assemblies further grind down the solid waste particles so that only particles smaller than the clearances in the system can pass there through, thereby resisting damage to and the interruption of the operation of the transfer pump. The column assembly is modular so that sections can be easily assembled, disassembled and/or removed. A second embodiment employs a stator jacket which provides an alternate means for cooling the electric motor means and lubricating and/or cooling the bearing assemblies, and a third embodiment employs a variable level suction device which allows liquid waste to be drawn into the transfer pump from varying and discrete levels in the waste tank. 17 figs
International Nuclear Information System (INIS)
Huang, Xingyi; Wang, Shen; Zhu, Ming; Yang, Ke; Jiang, Pingkai; Bando, Yoshio; Golberg, Dmitri; Zhi, Chunyi
2015-01-01
Thermally conductive and electrically insulating polymer/boron nitride (BN) nanocomposites are highly attractive for various applications in many thermal management fields. However, so far most of the preparation methods for polymer/BN nanocomposites have usually caused difficulties in the material post processing. Here, an in situ grafting approach is designed to fabricate thermally conductive, electrically insulating and post-melt processable polystyrene (PS)/BN nanosphere (BNNS) nanocomposites by initiating styrene (St) on the surface functionalized BNNSs via reversible addition fragmentation chain transfer polymerization. The nanocomposites exhibit significantly enhanced thermal conductivity. For example, at a St/BN feeding ratio of 5:1, an enhancement ratio of 1375% is achieved in comparison with pure PS. Moreover, the dielectric properties of the nanocomposites show a desirable weak dependence on frequency, and the dielectric loss tangent of the nanocomposites remains at a very low level. More importantly, the nanocomposites can be subjected to multiple melt processing to form different shapes. Our method can become a universal approach to prepare thermally conductive, electrically insulating and melt-processable polymer nanocomposites with diverse monomers and nanofillers. (paper)
John F. Hunt; Hongmei Gu
2006-01-01
The anisotropy of wood complicates solution of heat and mass transfer problems that require analyses be based on fundamental material properties of the wood structure. Most heat transfer models use average thermal properties across either the radial or tangential direction and do not differentiate the effects of cellular alignment, earlywood/latewood differences, or...
Barforoush, M. S. M.; Saedodin, S.
2018-01-01
This article investigates the thermal performance of convective-radiative annular fins with a step reduction in local cross section (SRC). The thermal conductivity of the fin's material is assumed to be a linear function of temperature, and heat transfer coefficient is assumed to be a power-law function of surface temperature. Moreover, nonzero convection and radiation sink temperatures are included in the mathematical model of the energy equation. The well-known differential transformation method (DTM) is used to derive the analytical solution. An exact analytical solution for a special case is derived to prove the validity of the obtained results from the DTM. The model provided here is a more realistic representation of SRC annular fins in actual engineering practices. Effects of many parameters such as conduction-convection parameters, conduction-radiation parameter and sink temperature, and also some parameters which deal with step fins such as thickness parameter and dimensionless parameter describing the position of junction in the fin on the temperature distribution of both thin and thick sections of the fin are investigated. It is believed that the obtained results will facilitate the design and performance evaluation of SRC annular fins.
Effects of variable specific heat on energy transfer in a high-temperature supersonic channel flow
Chen, Xiaoping; Li, Xiaopeng; Dou, Hua-Shu; Zhu, Zuchao
2018-05-01
An energy transfer mechanism in high-temperature supersonic turbulent flow for variable specific heat (VSH) condition through turbulent kinetic energy (TKE), mean kinetic energy (MKE), turbulent internal energy (TIE) and mean internal energy (MIE) is proposed. The similarities of energy budgets between VSH and constant specific heat (CSH) conditions are investigated by introducing a vibrational energy excited degree and considering the effects of fluctuating specific heat. Direct numerical simulation (DNS) of temporally evolving high-temperature supersonic turbulent channel flow is conducted at Mach number 3.0 and Reynolds number 4800 combined with a constant dimensional wall temperature 1192.60 K for VSH and CSH conditions to validate the proposed energy transfer mechanism. The differences between the terms in the two kinetic energy budgets for VSH and CSH conditions are small; however, the magnitude of molecular diffusion term for VSH condition is significantly smaller than that for CSH condition. The non-negligible energy transfer is obtained after neglecting several small terms of diffusion, dissipation and compressibility related. The non-negligible energy transfer involving TIE includes three processes, in which energy can be gained from TKE and MIE and lost to MIE. The same non-negligible energy transfer through TKE, MKE and MIE is observed for both the conditions.
Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation
Daryabeigi, Kamran; Cunnington, George R.; Knutson, Jeffrey R.
2012-01-01
Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.
International Nuclear Information System (INIS)
Guzman-Vargas, L; Reyes-Ramirez, I; Sanchez, N
2005-01-01
In a recent paper (Santillan et al 2001 J. Phys. D: Appl. Phys. 34 2068-72) the local stability of a Curzon-Ahlborn-Novikov (CAN) engine with equal conductances in the coupling with thermal baths was analysed. In this work, we present a local stability analysis of an endoreversible engine operating at maximum power output, for common heat transfer laws, and for different heat conductances α and β, in the isothermal couplings of the working substance with the thermal sources T 1 and T 2 (T 1 > T 2 ). We find that the relaxation times, in the cases analysed here, are a function of α, β, the heat capacity C, T 1 and T 2 . Besides, the eigendirections in a phase portrait are also functions of τ = T 1 /T 2 and the ratio β/α. From these findings, phase portraits for the trajectories after a small perturbation over the steady-state values of internal temperatures are presented, for some significant situations. Finally, we discuss the local stability and energetic properties of the endoreversible CAN heat engine
Fundamental principles of heat transfer
Whitaker, Stephen
1977-01-01
Fundamental Principles of Heat Transfer introduces the fundamental concepts of heat transfer: conduction, convection, and radiation. It presents theoretical developments and example and design problems and illustrates the practical applications of fundamental principles. The chapters in this book cover various topics such as one-dimensional and transient heat conduction, energy and turbulent transport, forced convection, thermal radiation, and radiant energy exchange. There are example problems and solutions at the end of every chapter dealing with design problems. This book is a valuable int
Properties of a local dust storm on Mars' Atlantis Chaos by means of radiative transfer modeling.
Oliva, Fabrizio; Altieri, Francesca; Geminale, Anna; Bellucci, Giancarlo; D'Aversa, Emiliano; Carrozzo, Giacomo; Sindoni, Giuseppe; Grassi, Davide
2017-04-01
In this study we present the analysis of the dust properties in a local storm imaged in the Atlantis Chaos region on Mars by the OMEGA spectrometer (Bibring et al., 2004) on March 2nd 2005 (ORB1441_5). By means of an inverse radiative transfer code we study the dust properties across the region and try to infer the connection be-tween the local storm dynamics and the orography. OMEGA is a visible and near-IR mapping spectrometer, operating in the spectral range 0.38-5.1 μm with three separate channels with different spectral resolution. The instrument's IFOV is 1.2 mrad. To analyze the storm properties we have used the inverse radiative transfer model MITRA (Oliva et al., 2016; Sindoni et al., 2013) to retrieve the effective radius reff, the optical depth at 880 nm τ880 and the top pressure tp of the dust layer. We used the Mars Climate Database (MCD, Forget et al., 1999) to obtain the atmospheric properties of the studied region to be used as input in our model. Moreover we used the optical constants from Wolff et al. (2009) to describe the dust composition. The properties from the surface have been obtained by ap-plying the SAS method (Geminale et al., 2015) to observations of the same region relatively clear from dust. All retrievals have been performed in the spectral range 500 ÷ 2500 nm. Here we describe the result from our analysis carried out on selected regions of the storm and characterized by a different optical depth of the dust. Aknowledgements: This study has been performed within the UPWARDS project and funded in the context of the European Union's Horizon 2020 Programme (H2020-Compet-08-2014), grant agreement UPWARDS-633127. References: Bibring, J-P. et al., 2004. OMEGA: Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité. Mars Express: the scientific payload, Ed. by Andrew Wilson, scientific coordination: Agustin Chicarro. ESA SP-1240, Noordwijk, Netherlands: ESA Publications Division, ISBN 92-9092-556-6, 2004, p. 37 - 49. Forget
Wang, Jing; Wang, Huatao; Zhang, Wenying; Yang, Xinyi; Wen, Guangwu; Wang, Yijie; Zhou, Weiwei
2017-02-17
Titanium (Ti) and its alloys are widely applied in many high strength, light weight applications, but their thermal conductivity is lower compared to that of other metals, which limits their further applications. In this paper, we demonstrated experimentally that rGO-Ti-rGO heterogeneous substrates with higher thermal conductivity, up to ∼38.8% higher than Ti, could be fabricated by electrochemical depositing rGO on their surface. The rGO layers are grown on the surface of Ti substrates, with appearance of bedclothes on the beds. The thickness of rGO layers is around 300-500 nm and around 600-1000 nm when deposited for 5 cycles and 10 cycles, respectively. According to the cooling experiment results, as-prepared Ti + rGO substrates can present excellent thermal conduction performance, and reduce the chip temperature close to 3.2 °C-13.1 °C lower than Ti alloy substrates with the heat flow density of 0.4-3.6 W cm -2 . Finally, the approach to electro-chemically deposit hundreds of nanometer rGO layers on the surface of Ti substrates can improve their thermal conductivity and heat transfer performance, which may have further application in the increasing thermal conduction of other metal-alloys, ceramics and polymers.
Bands dispersion and charge transfer in β-BeH2
Trivedi, D. K.; Galav, K. L.; Joshi, K. B.
2018-04-01
Predictive capabilities of ab-initio method are utilised to explore bands dispersion and charge transfer in β-BeH2. Investigations are carried out using the linear combination of atomic orbitals method at the level of density functional theory. The crystal structure and related parameters are settled by coupling total energy calculations with the Murnaghan equation of state. Electronic bands dispersion from PBE-GGA is reported. The PBE-GGA, and PBE0 hybrid functional, show that β-BeH2 is a direct gap semiconductor with 1.18 and 2.40 eV band gap. The band gap slowly decreases with pressure and beyond l00 GPa overlap of conduction and valence bands at the r point is observed. Charge transfer is studied by means of Mullikan population analysis.
Base fluid in improving heat transfer for EV car battery
Bin-Abdun, Nazih A.; Razlan, Zuradzman M.; Shahriman, A. B.; Wan, Khairunizam; Hazry, D.; Ahmed, S. Faiz; Adnan, Nazrul H.; Heng, R.; Kamarudin, H.; Zunaidi, I.
2015-05-01
This study examined the effects of base fluid (as coolants) channeling inside the heat exchanger in the process of the increase in thermal conductivity between EV car battery and the heat exchanger. The analysis showed that secondary cooling system by means of water has advantages in improving the heat transfer process and reducing the electric power loss on the form of thermal energy from batteries. This leads to the increase in the efficiency of the EV car battery, hence also positively reflecting the performance of the EV car. The present work, analysis is performed to assess the design and use of heat exchanger in increasing the performance efficiency of the EV car battery. This provides a preface to the use this design for nano-fluids which increase and improve from heat transfer.
DEFF Research Database (Denmark)
Chernyy, Sergey
2012-01-01
strategies for initiator grafting, physicochemical properties of polymer brushes and basic principles of quartz crystal microbalance technique (QCM) are discussed. In Chapter 2 various ATRP conditions are probed. The effects of solvent polarity, monomer concentration, initiator surface density, ligand nature......Atom transfer radical polymerization initiated from a surface of various substrates (SI-ATRP) has become a progressively popular technique for obtaining thin polymer films with predetermined properties. The present work addresses the main features of SI-ATRP with respect to the controllability...... and temperature on the kinetics of methyl methacrylate polymerization are elucidated. The strategy was based on the observation of dry polymer thickness versus time evolution by means of ellipsometry, profilometry and IR spectroscopy. An alternative approach, constituting Chapter 3, was based on optimization...
Direct geoelectrical evidence of mass transfer at the laboratory scale
Swanson, Ryan D.; Singha, Kamini; Day-Lewis, Frederick D.; Binley, Andrew; Keating, Kristina; Haggerty, Roy
2012-10-01
Previous field-scale experimental data and numerical modeling suggest that the dual-domain mass transfer (DDMT) of electrolytic tracers has an observable geoelectrical signature. Here we present controlled laboratory experiments confirming the electrical signature of DDMT and demonstrate the use of time-lapse electrical measurements in conjunction with concentration measurements to estimate the parameters controlling DDMT, i.e., the mobile and immobile porosity and rate at which solute exchanges between mobile and immobile domains. We conducted column tracer tests on unconsolidated quartz sand and a material with a high secondary porosity: the zeolite clinoptilolite. During NaCl tracer tests we collected nearly colocated bulk direct-current electrical conductivity (σb) and fluid conductivity (σf) measurements. Our results for the zeolite show (1) extensive tailing and (2) a hysteretic relation between σf and σb, thus providing evidence of mass transfer not observed within the quartz sand. To identify best-fit parameters and evaluate parameter sensitivity, we performed over 2700 simulations of σf, varying the immobile and mobile domain and mass transfer rate. We emphasized the fit to late-time tailing by minimizing the Box-Cox power transformed root-mean square error between the observed and simulated σf. Low-field proton nuclear magnetic resonance (NMR) measurements provide an independent quantification of the volumes of the mobile and immobile domains. The best-fit parameters based on σf match the NMR measurements of the immobile and mobile domain porosities and provide the first direct electrical evidence for DDMT. Our results underscore the potential of using electrical measurements for DDMT parameter inference.
Bivalve aquaculture transfers in Atlantic Europe. Part A: Transfer activities and legal framework
DEFF Research Database (Denmark)
Muehlbauer, F.; Fraser, D.; Brenner, M.
2014-01-01
environment and address economic considerations remains unanswered. This study provides the first overview of bivalve transfer activities for aquaculture purposes along the European Atlantic coast. Existing international and EU legislation is described, and potential weaknesses in the existing legislative......Intentional transfers of numerous bivalve species have had a long tradition and are commonly conducted along the European Atlantic coast. However numerous studies have concluded that intentional transfer of species for aquaculture purposes is one of the most principal vectors for the introduction...... frameworks are discussed. Recommendations for the development of integrated risk assessment methods are given. These may help to minimize the intrinsic threats of transfer activities in marine environments. The resulting impacts and effects of transfer activities of bivalves for aquaculture purpose...
Hou, Jie
2015-01-01
Two types of proton-blocking composites, La2NiO4+δ-LaNi0.6Fe0.4O3-δ (LNO-LNF) and Sm0.2Ce0.8O2-δ-LaNi0.6Fe0.4O3-δ (SDC-LNF), were evaluated as cathode materials for proton-conducting solid oxide fuel cells (H-SOFCs) based on the BaZr0.1Ce0.7Y0.2O3-δ (BZCY) electrolyte, in order to compare and investigate the influence of two different oxygen transfer mechanism on the performance of the cathode for H-SOFCs. The X-ray diffraction (XRD) results showed that the chemical compatibility of the components in both compounds was excellent up to 1000°C. Electrochemical studies revealed that LNO-LNF showed lower area specific polarization resistances in symmetrical cells and better electrochemical performance in single cell tests. The single cell with LNO-LNF cathode generated remarkable higher maximum power densities (MPDs) and lower interfacial polarization resistances (Rp) than that with SDC-LNF cathode. Correspondingly, the MPDs of the single cell with the LNO-LNF cathode were 490, 364, 266, 180 mW cm-2 and the Rp were 0.103, 0.279, 0.587, 1.367 Ω cm2 at 700, 650, 600 and 550°C, respectively. Moreover, after the single cell with LNO-LNF cathode optimized with an anode functional layer (AFL) between the anode and electrolyte, the power outputs reached 708 mW cm-2 at 700°C. These results demonstrate that the LNO-LNF composite cathode with the interstitial oxygen transfer mechanism is a more preferable alternative for H-SOFCs than SDC-LNF composite cathode with the oxygen vacancy transfer mechanism.
Directory of Open Access Journals (Sweden)
Janaina Cardoso Brum
2017-11-01
Full Text Available In March 2016, the former president Lula was conducted through a coercive way by the Federal Police in order to depose about his involvement in suspect activities related to Operation Lava Jato. The shooting or any other register of this coercive conduction have been forbidden, thus the national media began to work in the verge of this “denied image”. In this paper, we investigate the process of meaning production about this “absent image” through other images and materialities that circulate in the media discourse game regarding the destabilization/ stabilization of evidence about the March fourth current events. Therefore, the concept of lack, excess and strangeness, established by Ernst, were fundamental. We started with the hypothesis that, answering the lack of imagetic register, it was established a profusion of other imagetic, audiovisual and/or verbal discourses.
International Nuclear Information System (INIS)
Bocquet, M.; Micaud, G.
1962-01-01
An apparatus was developed for measuring the thermal conductivity coefficient K of irradiated or non-irradiated graphite. The measurement of K at around room temperature with an accuracy of about 6% is possible. The study specimen is placed in a vacuum between a hot and a cold source which create a temperature gradient ΔΘ/ Δx in the steady state. The amount of heat transferred, Q, is deduced from the electrical power dissipated at the hot source, after allowing for heat losses. The thermal conductivity coefficient is defined as: K = Q/S. Δx/ΔΘ, S being the cross section of the sample. Systematic studies have made it possible to determine the mean values of the thermal conductivity. (authors) [fr
Axial flow heat exchanger devices and methods for heat transfer using axial flow devices
Koplow, Jeffrey P.
2016-02-16
Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.
Economics and industry do not mean ethical conduct in clinical trials.
Lexchin, Joel
2013-01-01
Clinical trials present an ethical dilemma for pharmaceutical companies. While companies may want to undertake and report these trials in an ethical manner, negative results can significantly affect product sales. There is accumulating evidence that company-financed trials are biased in favor of the product that the company makes. Ethical conduct in this article is defined as whether the trials are conducted in the best interests of the participants and/or reported in the best interests of patients. Nine examples of how clinical trials are violating multiple articles in the Declaration of Helsinki are discussed using concrete case reports from the literature. The recognition of ethical problems in company run trials is not something new, but to date no meaningful action has been taken to resolve this issue. What is necessary is to separate the financing of clinical trials from their conduct.
Thermally Conductive Metal-Tube/Carbon-Composite Joints
Copeland, Robert J.
2004-01-01
An improved method of fabricating joints between metal and carbon-fiber-based composite materials in lightweight radiators and heat sinks has been devised. Carbon-fiber-based composite materials have been used in such heat-transfer devices because they offer a combination of high thermal conductivity and low mass density. Metal tubes are typically used to carry heat-transfer fluids to and from such heat-transfer devices. The present fabrication method helps to ensure that the joints between the metal tubes and the composite-material parts in such heat-transfer devices have both (1) the relatively high thermal conductances needed for efficient transfer of heat and (2) the flexibility needed to accommodate differences among thermal expansions of dissimilar materials in operation over wide temperature ranges. Techniques used previously to join metal tubes with carbon-fiber-based composite parts have included press fitting and bonding with epoxy. Both of these prior techniques have been found to yield joints characterized by relatively high thermal resistances. The present method involves the use of a solder (63 percent Sn, 37 percent Pb) to form a highly thermally conductive joint between a metal tube and a carbon-fiber-based composite structure. Ordinarily, the large differences among the coefficients of thermal expansion of the metal tube, solder, and carbon-fiber-based composite would cause the solder to pull away from the composite upon post-fabrication cooldown from the molten state. In the present method, the structure of the solder is modified (see figure) to enable it to deform readily to accommodate the differential thermal expansion.
International Nuclear Information System (INIS)
Rhodes, C.A.
1984-12-01
This report describes the computer program COXPRO-II, which was written for performing thermal analyses of irradiated fuel assemblies in a gaseous environment with no forced cooling. The heat transfer modes within the fuel pin bundle are radiation exchange among fuel pin surfaces and conduction by the stagnant gas. The array of parallel cylindrical fuel pins may be enclosed by a metal wrapper or shroud. Heat is dissipated from the outer surface of the fuel pin assembly by radiation and convection. Both equilateral triangle and square fuel pin arrays can be analyzed. Steady-state and unsteady-state conditions are included. Temperatures predicted by the COXPRO-II code have been validated by comparing them with experimental measurements. Temperature predictions compare favorably to temperature measurements in pressurized water reactor (PWR) and liquid-metal fast breeder reactor (LMFBR) simulated, electrically heated fuel assemblies. Also, temperature comparisons are made on an actual irradiated Fast-Flux Test Facility (FFTF) LMFBR fuel assembly
Visualisation of heat transfer in laminar flows
Speetjens, M.F.M.; Steenhoven, van A.A.
2009-01-01
Heat transfer in fluid flows traditionally is examined in terms of temperature field and heat-transfer coefficients at non-adiabatic walls. However, heat transfer may alternatively be considered as the transport of thermal energy by the total convective-conductive heat flux in a way analogous to the
Proton solvation and proton transfer in chemical and electrochemical processes
International Nuclear Information System (INIS)
Lengyel, S.; Conway, B.E.
1983-01-01
This chapter examines the proton solvation and characterization of the H 3 O + ion, proton transfer in chemical ionization processes in solution, continuous proton transfer in conductance processes, and proton transfer in electrode processes. Topics considered include the condition of the proton in solution, the molecular structure of the H 3 O + ion, thermodynamics of proton solvation, overall hydration energy of the proton, hydration of H 3 O + , deuteron solvation, partial molal entropy and volume and the entropy of proton hydration, proton solvation in alcoholic solutions, analogies to electrons in semiconductors, continuous proton transfer in conductance, definition and phenomenology of the unusual mobility of the proton in solution, solvent structure changes in relation to anomalous proton mobility, the kinetics of the proton-transfer event, theories of abnormal proton conductance, and the general theory of the contribution of transfer reactions to overall transport processes
Homogenized thermal conduction model for particulate foods
Chinesta , Francisco; Torres , Rafael; Ramón , Antonio; Rodrigo , Mari Carmen; Rodrigo , Miguel
2002-01-01
International audience; This paper deals with the definition of an equivalent thermal conductivity for particulate foods. An homogenized thermal model is used to asses the effect of particulate spatial distribution and differences in thermal conductivities. We prove that the spatial average of the conductivity can be used in an homogenized heat transfer model if the conductivity differences among the food components are not very large, usually the highest conductivity ratio between the foods ...
Heat transfer investigations within dry spent fuel casks
International Nuclear Information System (INIS)
Nitsche, F.
1986-07-01
For studying the heat transfer processes and predicting the maximum spent fuel element surface temperature in a spent fuel assembly (SFA) transported in a dry cask, model experiments have been performed with a gas-filled model cask containing a simplified electrically heated model of a WWER-type SFA with 90 fuel elements. The temperature distribution of the SFA model is measured for different heat rates under vacuum in the model cask, and under normal pressure and overpressure (0.1 ... 0.7 MPa) for several cooling gases (air, argon, helium) in order to separately investigate heat transfer processes by radiation and convection/conduction. The measuring results were compared with the calculations. Computer programmes as well as simplified calculation methods for temperature prediction were developed and checked. The results obtained are also useful for thermal analyses in the field of the dry storage of SFAs in a cask or can. Specifically it was found that: The heat removal from the SFA can be considerably improved by increasing the internal cask pressure or by using helium as coolant. The radiant heat exchange in the SFA model can be calculated with sufficient accuracy by means of a computer programme developed in 1978 or by means of a simplified analytical representation shown in the final report. Both methods are directly applicable to the original SFA and useful in order to approximately calculate the maximum SFE surface temperature under normal pressure, if the fraction of heat transferred by radiation is allowed for. For the calculation of the total heat transfer a computer programme was developed and verified, which completely permits the temperature prediction of the SFA model in dependence on heat rate, type of gaseous coolant and coolant pressure. This computer programme can be directly applied to the original SFA for the calculation of the maximum SFE surface temperature
Discussion on the thermal conductivity enhancement of nanofluids
2011-01-01
Increasing interests have been paid to nanofluids because of the intriguing heat transfer enhancement performances presented by this kind of promising heat transfer media. We produced a series of nanofluids and measured their thermal conductivities. In this article, we discussed the measurements and the enhancements of the thermal conductivity of a variety of nanofluids. The base fluids used included those that are most employed heat transfer fluids, such as deionized water (DW), ethylene glycol (EG), glycerol, silicone oil, and the binary mixture of DW and EG. Various nanoparticles (NPs) involving Al2O3 NPs with different sizes, SiC NPs with different shapes, MgO NPs, ZnO NPs, SiO2 NPs, Fe3O4 NPs, TiO2 NPs, diamond NPs, and carbon nanotubes with different pretreatments were used as additives. Our findings demonstrated that the thermal conductivity enhancements of nanofluids could be influenced by multi-faceted factors including the volume fraction of the dispersed NPs, the tested temperature, the thermal conductivity of the base fluid, the size of the dispersed NPs, the pretreatment process, and the additives of the fluids. The thermal transport mechanisms in nanofluids were further discussed, and the promising approaches for optimizing the thermal conductivity of nanofluids have been proposed. PMID:21711638
Gas transfer in a bubbly wake flow
Karn, A.; Gulliver, J. S.; Monson, G. M.; Ellis, C.; Arndt, R. E. A.; Hong, J.
2016-05-01
The present work reports simultaneous bubble size and gas transfer measurements in a bubbly wake flow of a hydrofoil, designed to be similar to a hydroturbine blade. Bubble size was measured by a shadow imaging technique and found to have a Sauter mean diameter of 0.9 mm for a reference case. A lower gas flow rate, greater liquid velocities, and a larger angle of attack all resulted in an increased number of small size bubbles and a reduced weighted mean bubble size. Bubble-water gas transfer is measured by the disturbed equilibrium technique. The gas transfer model of Azbel (1981) is utilized to characterize the liquid film coefficient for gas transfer, with one scaling coefficient to reflect the fact that characteristic turbulent velocity is replaced by cross-sectional mean velocity. The coefficient was found to stay constant at a particular hydrofoil configuration while it varied within a narrow range of 0.52-0.60 for different gas/water flow conditions.
Liquid metal MHD and heat transfer in a tokamak blanket slotted coolant channel
International Nuclear Information System (INIS)
Reed, C.B.; Hua, T.Q.; Black, D.B.; Kirillov, I.R.; Sidorenkov, S.I.; Shapiro, A.M.; Evtushenko, I.A.
1993-01-01
A liquid metal MHD (Magnetohydrodynamic)/heat transfer test was conducted at the ALEX (Argonne Liquid Metal Experiment) facility of ANL (Argonne National Laboratory), jointly between ANL and NIIEFA (Efremov Institute). The test section was a rectangular slotted channel geometry (meaning the channel has a high aspect ratio, in this case 10:1, and the long side is parallel to the applied magnetic field). Isothermal and heat transfer data were collected. A heat flux of ∼9 W/cm 2 was applied to the top horizontal surface (the long side) of the test section. Hartmann Numbers to 1050 (2 Tesla), interaction parameters to 9 x 10 3 , Peclet numbers of 10--200, based on the half-width of the small dimension (7mm), and velocities of 1--75 cm/sec. were achieved. The working fluid was NaK (sodium potassium eutectic). All four interior walls were bare, 300-series stainless steel, conducting walls
Rod Bundle Heat Transfer: Steady-State Steam Cooling Experiments
International Nuclear Information System (INIS)
Spring, J.P.; McLaughlin, D.M.
2006-01-01
Through the joint efforts of the Pennsylvania State University and the United States Nuclear Regulatory Commission, an experimental rod bundle heat transfer (RBHT) facility was designed and built. The rod bundle consists of a 7 x 7 square pitch array with spacer grids and geometry similar to that found in a modern pressurized water reactor. From this facility, a series of steady-state steam cooling experiments were performed. The bundle inlet Reynolds number was varied from 1 400 to 30 000 over a pressure range from 1.36 to 4 bars (20 to 60 psia). The bundle inlet steam temperature was controlled to be at saturation for the specified pressure and the fluid exit temperature exceeded 550 deg. C in the highest power tests. One important quantity of interest is the local convective heat transfer coefficient defined in terms of the local bulk mean temperature of the flow, local wall temperature, and heat flux. Steam temperatures were measured at the center of selected subchannels along the length of the bundle by traversing miniaturized thermocouples. Using an analogy between momentum and energy transport, a method was developed for relating the local subchannel centerline temperature measurement to the local bulk mean temperature. Wall temperatures were measured using internal thermocouples strategically placed along the length of each rod and the local wall heat flux was obtained from an inverse conduction program. The local heat transfer coefficient was calculated from the data at each rod thermocouple location. The local heat transfer coefficients calculated for locations where the flow was fully developed were compared against several published correlations. The Weisman and El-Genk correlations were found to agree best with the RBHT steam cooling data, especially over the range of turbulent Reynolds numbers. The effect of spacer grids on the heat transfer enhancement was also determined from instrumentation placed downstream of the spacer grid locations. The local
International Nuclear Information System (INIS)
Stolwijk, Nicolaas A.; Kösters, Johannes; Wiencierz, Manfred; Schönhoff, Monika
2013-01-01
The degree of ion association in polymer electrolytes is often characterized by the Nernst–Einstein deviation parameter Δ, which quantifies the relative difference between the true ionic conductivity directly measured by electrical methods and the hypothetical maximum conductivity calculated from the individual ionic self-diffusion coefficients. Despite its unambiguous definition, the parameter Δ is a global quantity with limited explanatory power. Similar is true for the cation transport number t cat * , which relies on the same ionic diffusion coefficients usually measured by nuclear magnetic resonance or radiotracer methods. Particularly in cases when neutral ion pairs dominate over higher-order aggregates, more specific information can be extracted from the same body of experimental data that is used for the calculation of Δ and t cat * . This information concerns the pair contributions to the diffusion coefficient of cations and anions. Also the true cation transference number based on charged species only can be deduced. We present the basic theoretical framework and some pertinent examples dealing with ion pairing in polymer electrolytes
Hol C Y; Chen, B C; Tsai, Y H; Ma, C; Wen, M Y
2015-11-01
This paper investigates the thermal transport in hollow microscale and nanoscale spheres subject to electrical heat source using nontraditional thermal transport model. Working as supercapacitor electrodes, carbon hollow micrometer- and nanometer-sized spheres needs excellent heat transfer characteristics to maintain high specific capacitance, long cycle life, and high power density. In the nanoscale regime, the prediction of heat transfer from the traditional heat conduction equation based on Fourier's law deviates from the measured data. Consequently, the electrical heat source-induced heat transfer characteristics in hollow micrometer- and nanometer-sized spheres are studied using nontraditional thermal transport model. The effects of parameters on heat transfer in the hollow micrometer- and nanometer-sized spheres are discussed in this study. The results reveal that the heat transferred into the spherical interior, temperature and heat flux in the hollow sphere decrease with the increasing Knudsen number when the radius of sphere is comparable to the mean free path of heat carriers.
Devices with extended area structures for mass transfer processing of fluids
TeGrotenhuis, Ward E.; Wegeng, Robert S.; Whyatt, Greg A.; King, David L.; Brooks, Kriston P.; Stenkamp, Victoria S.
2009-04-21
A microchannel device includes several mass transfer microchannels to receive a fluid media for processing at least one heat transfer microchannel in fluid communication with a heat transfer fluid defined by a thermally conductive wall, and at several thermally conductive fins each connected to the wall and extending therefrom to separate the mass transfer microchannels from one another. In one form, the device may optionally include another heat transfer microchannel and corresponding wall that is positioned opposite the first wall and has the fins and the mass transfer microchannels extending therebetween.
Caesium contamination in human milk and transfer factor from diet
International Nuclear Information System (INIS)
Risica, S.; Campos Venuti, G.; Rogani, A.; Baronciani, D.; Petrone, M.
1992-01-01
A study on caesium contamination in human milk, as a consequence of the Chernobyl fallout, was conducted in 1989 on a group of women from one of the areas of northern Italy most heavily affected by the radioactive fallout. Their diet was studied, and the caesium intake was calculated by using the mean food activity concentration in that area. The caesium transfer factor was evaluated both as the ratio of caesium concentration in mother's milk to the daily intake, and by using a simplified milk compartment model. (author)
Cooling permafrost embankment by enhancing oriented heat conduction in asphalt pavement
International Nuclear Information System (INIS)
Yinfei, Du; Shengyue, Wang; Shuangjie, Wang; Jianbing, Chen
2016-01-01
Highlights: • Solar radiation heat was prevented from entering the embankment in summer. • The downward heat transfer efficiency in asphalt pavement and embankment reduced. • The net heat accumulation in the embankment decreased. - Abstract: In this paper, a new method was proposed to decrease the heat accumulation in permafrost embankment by controlling an oriented heat transfer in asphalt pavement. Two highly oriented heat-induced structures, named G-OHIS (only gradient thermal conductivity) and G+R-OHIS (combined gradient thermal conductivity and heat reflective layer), were designed by using two indexes of summertime daily heat absorption and annual net heat accumulation on the top of embankment. The results showed that the heat absorptions on the top of embankments of the G-OHIS and G+R-OHIS in summer decreased by 9.9% and 23.2% respectively. The annual net heat accumulation on the top of embankment decreased by 6.2% for the G-OHIS and 37.9% for the G+R-OHIS. Moreover, the summertime mean daily temperatures on the top of embankments of the G-OHIS and G+R-OHIS reduced by 0.74 °C and 1.66 °C respectively. The annual temperature difference on the top of embankment reduced by 1.07 °C for the G-OHIS and 1.96 °C for the G+R-OHIS. The effectiveness of the G-OHIS in reducing pavement temperature was validated by an indoor irradiation test. It is expected to reduce permafrost thawing and other pavement distresses caused by permafrost thawing by controlling an oriented heat transfer in asphalt pavement.
Development of Chinese HTR-PM pebble bed equivalent conductivity test facility
Energy Technology Data Exchange (ETDEWEB)
Ren, Cheng; Yang, Xingtuan; Jiang, Shengyao [Tsinghua Univ., Beijing (China). Inst. of Nuclear and New Energy Technology
2016-01-15
The first two 250-MWt high-temperature reactor pebble bed modules (HTR-PM) have been installing at the Shidaowan plant in Shandong Province, China. The values of the effective thermal conductivity of the pebble bed core are essential parameters for the design. For their determination, Tsinghua University in China has proposed a full-scale heat transfer experiment to conduct comprehensive thermal transfer tests in packed pebble bed and to determine the effective thermal conductivity.
Case studies of heat conduction in rotary drums with L-shaped lifters via DEM
Directory of Open Access Journals (Sweden)
Qiang Xie
2018-03-01
Full Text Available Rotary drums are widely used in numerous processes in industry to handle granular materials. In present work, heat transfer processes in drums with L-shaped lifters have been investigated by coupling the discrete element method (DEM with heat transfer model. Effects of both operational and structural parameters have been analyzed. It is found that increasing rotational speed could improve heat transfer to a certain extent, however, just in relatively low speed stage. When lifter number increases, the heat transfer speed slightly decreases. An increasing lifter height could promote heat transfer first and then reduces it, but the amplitude of variation keeps small. The heat transfer rate descends with increasing lifter width. The heat transfer mechanisms have also been discussed by comparing mixing rates, total contact areas for thermal conduction, time constants (TC indicating apparent heat transfer rate and effective heat transfer coefficients(HTC. It is concluded that dynamic conduction due to particle flow is dominated in all cases. The L-shaped lifers are turned out not a good choice when heat conduction between particles is prominent.
Thermal effects in microfluidics with thermal conductivity spatially modulated
Vargas Toro, Agustín.
2014-05-01
A heat transfer model on a microfluidic is resolved analytically. The model describes a fluid at rest between two parallel plates where each plate is maintained at a differentially specified temperature and the thermal conductivity of the microfluidic is spatially modulated. The heat transfer model in such micro-hydrostatic configuration is analytically resolved using the technique of the Laplace transform applying the Bromwich Integral and the Residue theorem. The temperature outline in the microfluidic is presented as an infinite series of Bessel functions. It is shown that the result for the thermal conductivity spatially modulated has as a particular case the solution when the thermal conductivity is spatially constant. All computations were performed using the computer algebra software Maple. It is claimed that the analytical obtained results are important for the design of nanoscale devices with applications in biotechnology. Furthermore, it is suggested some future research lines such as the study of the heat transfer model in a microfluidic resting between coaxial cylinders with radially modulated thermal conductivity in order to achieve future developments in this area.
Functional check of telescoping transfer pumps
International Nuclear Information System (INIS)
Sharpe, C.L.
1994-01-01
Activities are defined which constitute a functional check of a telescoping transfer pump (TTP). This report is written to the Procedures group of HLW and particularly applies to those TTP's which are the sole means of emergency transfer from a HLW waste tank
peng, cheng
2015-01-01
Celebrity endorsement strategy is widely used by marketers for the purpose of increasing sales and extending the market shares. Celebrity endorsers have proved with positive impacts on purchase intention by many researchers. However, the current findings about the effects of celebrity endorsement on purchase intention are still equivocal, owing to several different dimensions of celebrity endorsement. For example, source credibility of celebrity, celebrity congruency and meaning transfer of c...
Heat transfer in heterogeneous propellant combustion systems
International Nuclear Information System (INIS)
Brewster, M.Q.
1992-01-01
This paper reports that heat transfer plays an important role in several critical areas of heterogeneous, solid-propellant combustion systems. These areas include heat feedback to the propellant surface, heat transfer between burning aluminum droplets and their surroundings, heat transfer to internal insulation systems, and heat transfer to aft-end equipment. Gas conduction dominates heat feedback to the propellant surface in conventional ammonium perchlorate (AP) composite propellants, although particle radiative feedback also plays a significant role in combustion of metalized propellants. Particle radiation plays a dominant role in heat transfer to internal insulation, compared with that of convection. However, conduction by impingement of burning aluminum particles, which has not been extensively studied, may also be significant. Radiative heat loss plays an important role in determining the burning rate of molten aluminum particles due to a highly luminous, oxide particle-laden, detached flame envelope. Radiation by aluminum oxide smoke particles also plays a dominant role in heat transfer from the exhaust plume to aft-end equipment. Uncertainties in aluminum oxide particle-size distribution and optical properties still make it difficult to predict radiative plume heat transfer accurately from first principles
Variable Thermal Conductivity on Compressible Boundary Layer ...
African Journals Online (AJOL)
In this paper, variable thermal conductivity on heat transfer over a circular cylinder is presented. The concept of assuming constant thermal conductivity on materials is however not efficient. Hence, the governing partial differential equation is reduced using non-dimensionless variables into a system of coupled non-linear ...
Ahn, Hojin
1989-12-01
Granular materials flowing down an inclined chute were studied experimentally and analytically. Characteristics of convective heat transfer to granular flows were also investigated experimentally and numerically. Experiments on continuous, steady flows of granular materials in an inclined chute were conducted with the objectives of understanding the characteristics of chute flows and of acquiring information on the rheological behavior of granular material flow. Existing constitutive equations and governing equations were used to solve for fully developed chute flows of granular materials, and thus the boundary value problem was formulated with two parameters (the coefficient of restitution between particles, and the chute inclination) and three boundary values at the chute base wall (the values of solid fraction, granular temperature, and mean velocity at the wall). The boundary value problem was numerically solved by the shooting method. These analytical results were also compared with the present experimental values and with the computer simulations by other investigators in their literature. Experiments on heat transfer to granular flows over a flat heating plate were conducted with three sizes of glass beads, polystyrene beads, and mustard seeds. A modification on the existing model for the convective heat transfer was made using the effective Nusselt number and the effective Peclet number, which include the effects of solid fraction variations. The slightly modified model could describe the heat transfer characteristics of both fast and slow flows (supercritical and subcritical). A numerical analysis of the transfer to granular flows was also performed. The results were compared with the present experimental data, and reasonable agreement was found in the comparison.
Numerical simulation of heat transfer process in automotive brakes
Gonzalo Voltas, David
2013-01-01
This master thesis concerns the theoretical investigations of the heat transfer process in automotive brakes. The process of heat generation and heat transfer to ambient air in automotive brake was presented. The two–dimensional, axi-symmetrical model of transient heat conduction for the brake was applied. The relevant boundary conditions, that describe the heat generated in the brake and the heat transferred to ambient air, were used. The unsteady heat conduction problem was solved by the...
Tunable heat transfer with smart nanofluids.
Bernardin, Michele; Comitani, Federico; Vailati, Alberto
2012-06-01
Strongly thermophilic nanofluids are able to transfer either small or large quantities of heat when subjected to a stable temperature difference. We investigate the bistability diagram of the heat transferred by this class of nanofluids. We show that bistability can be exploited to obtain a controlled switching between a conductive and a convective regime of heat transfer, so as to achieve a controlled modulation of the heat flux.
Liquefied Natural Gas Transfer
1980-01-01
Chicago Bridge & Iron Company's tanks and associated piping are parts of system for transferring liquefied natural gas from ship to shore and storing it. LNG is a "cryogenic" fluid meaning that it must be contained and transferred at very low temperatures, about 260 degrees below Fahrenheit. Before the LNG can be pumped from the ship to the storage tanks, the two foot diameter transfer pipes must be cooled in order to avoid difficulties associated with sharp differences of temperature between the supercold fluid and relatively warm pipes. Cooldown is accomplished by sending small steady flow of the cryogenic substance through the pipeline; the rate of flow must be precisely controlled or the transfer line will be subjected to undesirable thermal stress.
Numerical simulations of thermal conductivity in dissipative two-dimensional Yukawa systems.
Khrustalyov, Yu V; Vaulina, O S
2012-04-01
Numerical data on the heat transfer constants in two-dimensional Yukawa systems were obtained. Numerical study of the thermal conductivity and diffusivity was carried out for the equilibrium systems with parameters close to conditions of laboratory experiments with dusty plasma. For calculations of heat transfer constants the Green-Kubo formulas were used. The influence of dissipation (friction) on the heat transfer processes in nonideal systems was investigated. The approximation of the coefficient of thermal conductivity is proposed. Comparison of the obtained results to the existing experimental and numerical data is discussed.
Directory of Open Access Journals (Sweden)
Wenzheng Cui
2015-09-01
Full Text Available Nanofluids are a new generation of high-efficiency refrigerant with abnormal increased thermal conductivity and convective heat transfer properties. In view of the paucity of research work on the contribution of nanoparticle Brownian motion for the thermal conductivity augmentation, the present paper carries out a series of MD simulations to explorer the order of magnitude of nanoparticle Brownian motion and discusses the effect of nanoparticle Brownian motion for thermal conductivity enhancement of nanofluids. Various influence factors including nanoparticle shapes, sizes, and materials are considered. The Brownian motion of nanoparticles is decomposed into rotation and migration and calculated by MD simulation. By means of Peclet number, the effect of nanoparticle Brownian motion for thermal conductivity enhancement of nanofluids is discussed.
Andreopoulos, Dimitrios; Damigos, Dimitrios
2017-01-01
The attempt to design cost-effective adaptation policies incorporating non-market values to inhibit climate change impacts on water resources may increase the interest in applying the Benefit Transfer method. Benefit Transfer is a practical way to consider non-market values using functions and estimates acquired through primary valuation methods from other sites. Among the primary methods, Choice Experiments appear to particularly accommodate Benefit Transfer. Nevertheless, validity and reliability of international value transfers obtained from Choice Experiments have not been adequately examined. To this end, two identical Choice Experiments were conducted in Greece and Italy in the context of river services adaptation, testing validity and reliability of Benefit Transfer. The application of validity and reliability tests for different types of transfers is supportive for the use of Benefit Transfer, at least for the value transfer types. In particular the reliability of value transfer was higher when income adjustments were taken into account. Overall, Benefit Transfer can be attentively considered to evaluate cost-effective adaptation policies across countries experiencing similar climate change trends. The latter gains more importance given that an international Benefit Transfer setting as regards the non-market benefits of adaptation to climate change for river services is absent in the relevant literature. Copyright © 2016 Elsevier Ltd. All rights reserved.
Visualisation of heat transfer in unsteady laminar flows
Speetjens, M.F.M.; Steenhoven, van A.A.
2011-01-01
Heat transfer in fluid flows traditionally is examined in terms of temperature fields and heat-transfer coefficients. However, heat transfer may alternatively be considered as the transport of thermal energy by the total convective-conductive heat flux in a way analogous to the transport of fluid by
On free jejunal and colon transfer for pharyngo-esophageal reconstruction
International Nuclear Information System (INIS)
Fukui, Kiyoko; Annraku, Kuniaki; Ikenoya, Shintaro; Makino, Sachio; Ito, Kazuyuki; Takubo, Kenji; Kaji, Shogo
2013-01-01
Free jejunal transfer is a common procedure for hypopharyngo-esophageal reconstruction. We reviewed our experience with patients who underwent free jejunal and colon transfer surgery for hypopharyngo-esophageal reconstruction in the last 20 years in our institute. A retrospective review was conducted for 31 cases of reconstruction with free jejunal and colon transfer performed at Japanese Red Cross Matsue Hospital during the period of 20 years from January 1992 to December 2011. The mean age of the patients was 66 years. There were 30 patients with hypopharynx cancer and one patient with larynx cancer. Thirty patients had received preoperative radiotherapy and chemotherapy. The average time of surgery for free jejunal transfer reconstruction was 8.8 hours, including extraction of the hypopharynx, pharynx and cervical esophagus, debridment of pars hemi-cervicalis, and grafting procedure of free jejunum. The most common recipient vessels were the transverse cervical artery and external jugular vein, but recently, vessels of free flaps are often chosen to be anastomosed with the superior thyroid artery and internal jugular vein. The free jejunal and colon grafts for reconstruction took successfully in all patients. The complication rate was 52% (16/31 cases). Complications often occurred in cases of total esophagectomy, recurrence after full-dose chemoradiotherapy, and radiation therapy administered postoperatively. (author)
Merenda, Lisa A.; Rutter, Laure; Curran, Kimberly; Kozin, Scott H.
2012-01-01
Background: Tendon transfer surgery can restore elbow extension in approximately 70% of persons with tetraplegia and often results in antigravity elbow extension strength. However, we have noted an almost 15% rupture/attenuation rate. Objective: This investigation was conducted to analyze potential causes in adolescents/young adults with spinal cord injury (SCI) who experienced tendon rupture or attenuation after biceps-to-triceps transfer. Methods: Medical charts of young adults with SCI who underwent biceps-to-triceps transfer and experienced tendon rupture or attenuation were reviewed. Data collected by retrospective chart review included general demographics, surgical procedure(s), use and duration of antibiotic treatment, time from tendon transfer surgery to rupture/attenuation, and method of diagnosis. Results: Twelve subjects with tetraplegia (mean age, 19 years) who underwent biceps-to-triceps reconstruction with subsequent tendon rupture or attenuation were evaluated. Mean age at time of tendon transfer was 18 years (range, 14-21 years). A fluoroquinolone was prescribed for 42% (n=5) of subjects. Tendon rupture was noted in 67% (n=8), and attenuation was noted in 33% (n=4). Average length of time from surgery to tendon rupture/attenuation was 5.7 months (range, 3-10 months). Conclusion: Potential contributing causes of tendon rupture/attenuation after transfer include surgical technique, rehabilitation, co-contraction of the transfer, poor patient compliance, and medications. In this cohort, 5 subjects were prescribed fluoroquinolones that have a US Food and Drug Administration black box concerning tendon ruptures. Currently, all candidates for upper extremity tendon transfer reconstruction are counseled on the effects of fluoroquinolones and the potential risk for tendon rupture. PMID:23459326
Problems of heat transfer and hydraulics of two-phase media
Kutateladze, S S
1969-01-01
Problems of Heat Transfer and Hydraulics of Two-Phase Media presents the theory of heat transfer and hydrodynamics. This book discusses the various aspects of heat transfer and the flow of two-phase systems. Organized into two parts encompassing 22 chapters, this book starts with an overview of the laws of similarity for heat transfer to or from a flowing liquid with various physical properties and allowed for variation in viscosity and thermal conductivity. This book then explores the general functional relationship that exists between viscosity and thermal conductivity for thermodynamically
Modeling the overall heat conductive and convective properties of open-cell graphite foam
International Nuclear Information System (INIS)
Tee, C C; Yu, N; Li, H
2008-01-01
This work develops analytic models on the overall thermal conductivity, pressure drop and overall convective heat transfer coefficient of graphite foam. The models study the relationship between the overall heat conductive and convective properties, and foam microstructure, temperature, foam surface friction characteristics and cooling fluid properties. The predicted thermal conductivity, convective heat transfer coefficient and pressure drop agree well with experimental data
Wang, Xiaowei; Li, Huiping; Li, Zhichao
2018-04-01
The interfacial heat transfer coefficient (IHTC) is one of the most important thermal physical parameters which have significant effects on the calculation accuracy of physical fields in the numerical simulation. In this study, the artificial fish swarm algorithm (AFSA) was used to evaluate the IHTC between the heated sample and the quenchant in a one-dimensional heat conduction problem. AFSA is a global optimization method. In order to speed up the convergence speed, a hybrid method which is the combination of AFSA and normal distribution method (ZAFSA) was presented. The IHTC evaluated by ZAFSA were compared with those attained by AFSA and the advanced-retreat method and golden section method. The results show that the reasonable IHTC is obtained by using ZAFSA, the convergence of hybrid method is well. The algorithm based on ZAFSA can not only accelerate the convergence speed, but also reduce the numerical oscillation in the evaluation of IHTC.
Mixed conductivity in erbia-stabilized bismuth oxide
Vinke, I.C.; Vinke, I.C.; Boukamp, Bernard A.; de Vries, K.J.; de Vries, Karel Jan; Burggraaf, Anthonie; Burggraaf, A.J.
1992-01-01
The mixed conducting solid solution 0.75Bi2O3−0.25Tb4O7 (BT40) was studied by impedance techniques using ionically blocking electrodes. These measurements confirmed the p-type electronic conductivity suggested in literature. In air at temperatures between 600 and 900 K the ionic transference number
Triple vacuum glazing: Heat transfer and basic mechanical design constraints
Energy Technology Data Exchange (ETDEWEB)
Manz, H.; Brunner, S.; Wullschleger, L. [Swiss Federal Laboratories for Materials Testing and Research (EMPA), Laboratory for Applied Physics in Building, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)
2006-12-15
Given the major role played by windows with regard to energy losses from buildings in cold climates, low thermal transmittance is an indispensable property of glazing in low-energy buildings. Evacuation offers the only means of achieving negligible gaseous conduction in glazing cavities. Application of low-emittance coatings to glass sheet surfaces inside the cavity reduces the radiative heat transfer. The feasibility of double vacuum glazing using arrays of support pillars between the glass sheets has been shown by other authors. This type of glazing is commercially manufactured today. Based on these achievements, our study set out to investigate heat transfer in triple vacuum glazing by means of (i) an analytical thermal network model and (ii) a numerical finite difference model. The study focused on the impact of the following parameters on thermal transmittance: emittances of glass sheet surfaces inside the cavity, support pillar radius, support pillar separation and thermal conductivity of support pillar material. The design procedure for triple vacuum glazing taking into account not only thermal but also mechanical stresses due to atmospheric pressure, i.e., to enable identification of favourable parameter sets, is presented. Our findings suggest that use of the triple vacuum glazing concept can significantly reduce the thermal transmittances achieved by the best insulation glazing units currently on the market. E.g., a centre-of-glazing thermal transmittance of less than 0.2Wm{sup -2}K{sup -1} is achievable using stainless steel support pillars, 6mm/4mm/6mm sheets of untempered soda-lime glass and four low-emittance coatings ({epsilon}=0.03). (author)
Directory of Open Access Journals (Sweden)
H. R. Ehteram
2016-01-01
Full Text Available In this paper the effect of using various models for conductivity and viscosity considering Brownian motion of nanoparticles is investigated. This study is numerically conducted inside a cavity full of Water-Al2O3 nanofluid at the case of mixed convection heat transfer. The effect of some parameters such as the nanoparticle volume fraction, Rayleigh, Richardson and Reynolds numbers has been examined. The governing equations with specified boundary conditions has been solved using finite volume method. A computer code has been prepared for this purpose. The results are presented in form of stream functions, isotherms, Nusselt number and the flow power with and without the Brownian motion taken into consideration. The results show that for all the applied models the stream functions and isotherm have approximately same patterns and no considerable difference has been observed. In all the studied models when considering the Brownian motion, the average Nusselt number is higher than not taking this effect into account. The models of Koo-Kleinstreuer and Li-Kleinstreuer give almost same values for the maximum stream function and average Nusselt number. It is also true about the models of Vajjha-Das and Xiao et al.
Near-field radiative heat transfer between clusters of dielectric nanoparticles
International Nuclear Information System (INIS)
Dong, J.; Zhao, J.M.; Liu, L.H.
2017-01-01
In this work, we explore the near-field radiative heat transfer between two clusters of silicon carbide (SiC) nanoparticles using the many-body radiative heat transfer theory. The effects of fractal dimension of clusters, many-body interaction between nanoparticles and relative orientation of clusters on the thermal conductance are studied. Meanwhile, the applicability of the equivalent volume spheres (EVS) approximation for near-field radiative heat transfer between clusters is examined. It is observed that the thermal conductance is larger for clusters with larger fractal dimension, which is more significant in the near-field. The thermal conductance of EVS resembles that of the clusters, but EVS overestimates the conductance of clusters, especially in the near-field. Compared to the case of two nanoparticles, the conductance of nanoparticle clusters decays much slower with increasing distance in the near-field, but shares similar dependence on the distance in the far-field. The thermal conductance of SiC nanoparticle clusters is inhibited by the many-body interaction when surface phonon polariton is supported but enhanced at frequencies close to the resonance frequency. The total thermal conductance is decreased due to many-body interaction among particles in the cluster. The relative orientation between the clusters is also an important factor in the near-field, especially for clusters with lower fractal dimension. - Highlights: • Near-field radiative heat transfer between clusters of nanoparticles is studied. • The many-body radiative heat transfer theory is applied for rigorous analysis. • The accuracy of equivalent volume spheres approximation is examined. • Clusters with larger fractal dimension have larger radiative thermal conductance. • Many-body interaction inhibits the total radiative thermal conductance.
The Wilkes subglacial basin eastern margin electrical conductivity anomaly
Rizzello, Daniele; Armadillo, Egidio; Ferraccioli, Fausto; Caneva, Giorgio
2014-05-01
We have analyzed the deep conductivity structure at the transition between the Transantarctic Mountains (TAM) and the eastern margin of the WSB in NVL, by means of the GDS (Geomagnetic Deep Sounding) technique, in order to constrain the geodynamical interpretation of this antarctic sector. The TAM form the uplifted flank of the Mesozoic and Cenozoic West Antarctic Rift System. Structure of the TAM rift flank has been partially investigated with different geophysical approaches.The Wilkes Subglacial Basin is a broad depression over 400 km wide at the George V Coast and 1200 km long. Geology, lithospheric structure and tectonics of the Basin are only partially known because the Basin is buried beneath the East Antarctic Ice Sheet and is located in a remote region which makes geophysical exploration logistically challenging. Different authors have proposed contrasting hypothesis regarding the origin of the WSB: it could represent a region of rifted continental crust, or it may have a flexural origin or might represent an "extended terrane". Recently aerogeophysical investigations have demonstrated a strong structural control on the margin. Magnetovariational studies carried out at high geomagnetic latitudes are often hampered by source effects, mainly due to the closeness to the Polar Electrojet currents systems (PEJ). Its presence, in fact, makes the uniform magnetic field assumption, on which the magnetovariational methods are based on, often invalid, which outcome is a bias in the GDS transfer functions and to compromise the reliability of the inverted models. Data from the aforementioned campaigns have been then processed under the ISEE project (Ice Sheet Electromagnetic Experiment), aimed at evaluate and mitigate the bias effect of the PEJ on geomagnetic an magnetotelluric transfer functions at high geomagnetic latitudes, by means of suitable processing algorithms, developed upon a statistical analysis study on PEJ effects (Rizzello et al. 2013). Recent results
Effective method for construction of low-dimensional models for heat transfer process
Energy Technology Data Exchange (ETDEWEB)
Blinov, D.G.; Prokopov, V.G.; Sherenkovskii, Y.V.; Fialko, N.M.; Yurchuk, V.L. [National Academy of Sciences of Ukraine, Kiev (Ukraine). Inst. of Engineering Thermophysics
2004-12-01
A low-dimensional model based on the method of proper orthogonal decomposition (POD) and the method of polyargumental systems (MPS) for thermal conductivity problems with strongly localized source of heat has been presented. The key aspect of these methods is that they enable to avoid weak points of other projection methods, which consists in a priori choice of basis functions. It enables us to use the MPS method and the POD method as convenient means to construct low-dimensional models of heat and mass transfer problems. (Author)
Thermal signal propagation in soils in Romania: conductive and non-conductive processes
Directory of Open Access Journals (Sweden)
C. Demetrescu
2007-11-01
Full Text Available Temperature data recorded in 2002 and 2003 at 10 stations out of the 70 available in the Romanian automatic weather stations network are presented and analyzed in terms of the heat transfer from air to underground. The air temperature at 2 m, the soil temperatures at 0, 5, 10, 20, 50 and 100 cm below the surface as well as rain fall and snow cover thickness have been monitored. The selected locations sample various climate environments in Romania. Preliminary analytical modelling shows that soil temperatures track air temperature variations at certain locations and, consequently, the heat transfer is by conduction, while at other stations processes such as soil freezing and/or solar radiation heating play an important part in the heat flux balance at the air/soil interface. However, the propagation of the annual thermal signal in the uppermost one meter of soil is mainly by conduction; the inferred thermal diffusivity for 8 stations with continuous time series at all depth levels ranges from 3 to 10×10^{−7} m^{2} s^{−1}.
International Nuclear Information System (INIS)
Suarez, V.; Hernandez W, J.; Calderon, A.; Rojas T, J. B.; Juarez, A. G.; Marin, E.; Castaneda, A.
2012-10-01
We investigate the heat transfer through a homogeneous and isotropic solid exited by periodic light beam on its front surface. For this, we use the infrared photothermal radiometry in order to obtain the evolution of the temperature difference on the rear surface of the silicon sample as a function of the exposure time. Also, we solved the heat conduction equation for this problem with the boundary conditions congruent with the physical situation, by means of application the Com sol multi physics software and the heat transfer module. Our results show a good agree between the experimental and simulated results, which demonstrate the utility of this methodology in the study of the thermal response in solids. (Author)
Electrical conductivity sensors as a means to quantify hydrologic connectivity of desert riverscapes
Jaeger, K. L.; Olden, J. D.
2010-12-01
Fundamental to addressing issues in the emerging fields of landscape conservation biogeography and genetics is an understanding of the physical processes, in particular hydrologic processes, under which that landscape is operating. In arid and semi-arid landscapes, however, quantifying the considerable spatial and temporal variability of streamflow patterns historically has been limited by the substantial physical effort and monetary cost required to install monitoring equipment. Recently, internally-recording temperature sensors have been modified to measure relative conductivity as an indicator for the onset and cessation of streamflow, providing an inexpensive method of quantifying the timing, duration, and frequency of surface flow that can be implemented at a broad spatial scale. In this study, we characterize surface water connectivity across several mountain watersheds as a means to understanding landscape-scale hydrologic connectivity important to aquatic biota, in particular, amphibians. In the semi-arid Huachuca mountain range of southeastern Arizona, USA, a total of 44 conductivity sensors were installed at approximately 2-km intervals throughout 8 canyons underlain by granite, limestone, and other sedimentary geologic units. Sensor locations represent a range of hydrologic and geomorphic settings including perennial, intermittent, and ephemeral reaches within bedrock, travertine, sand-bedded and coarser-grained channel morphologies. Sensors were deployed in early April 2010 at a 15-minute logging interval and data from 31 sensors were retrieved in mid-August 2010; a time period representing the cessation of the spring snow runoff period and approximately the middle of the North American monsoon period. Cessation and onset of surface flow were identified by a large negative or positive increase in the slope (first derivative) of the data record, respectively. The sensors indicate a distinct springtime stream drying (mid-April to early May 2010
International Nuclear Information System (INIS)
Tzanos, C.P.; Dionne, B.
2011-01-01
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
Mojahedi, Mahdi; Shekoohinejad, Hamidreza
2018-02-01
In this paper, temperature distribution in the continuous and pulsed end-pumped Nd:YAG rod crystal is determined using nonclassical and classical heat conduction theories. In order to find the temperature distribution in crystal, heat transfer differential equations of crystal with consideration of boundary conditions are derived based on non-Fourier's model and temperature distribution of the crystal is achieved by an analytical method. Then, by transferring non-Fourier differential equations to matrix equations, using finite element method, temperature and stress of every point of crystal are calculated in the time domain. According to the results, a comparison between classical and nonclassical theories is represented to investigate rupture power values. In continuous end pumping with equal input powers, non-Fourier theory predicts greater temperature and stress compared to Fourier theory. It also shows that with an increase in relaxation time, crystal rupture power decreases. Despite of these results, in single rectangular pulsed end-pumping condition, with an equal input power, Fourier theory indicates higher temperature and stress rather than non-Fourier theory. It is also observed that, when the relaxation time increases, maximum amounts of temperature and stress decrease.
Technology transfer quality assurance
International Nuclear Information System (INIS)
Hood, F.C.
1991-03-01
The results of research conducted at Pacific Northwest Laboratory (PNL) for the DOE are regularly transferred from the laboratory to the private sector. The principal focus of PNL is on environmental research and waste management technology; other programs of emphasis include molecular science research. The technology transfer process is predicated on Quality to achieve its objectives effectively. Total quality management (TQM) concepts and principles readily apply to the development and translation of new scientific concepts into commercial products. The concept of technology transfer epitomizes the TQM tenet of continuous improvement: always striving for a better way to do things and always satisfying the customer. A successful technology transfer process adds value to society by providing new or enhanced processes, products, and services to government and commercial customers, with a guarantee of product pedigree and process validity. 2 refs
Modeling microscale heat transfer using Calore.
Energy Technology Data Exchange (ETDEWEB)
Gallis, Michail A.; Rader, Daniel John; Wong, Chung-Nin Channy; Bainbridge, Bruce L.; Torczynski, John Robert; Piekos, Edward Stanley
2005-09-01
Modeling microscale heat transfer with the computational-heat-transfer code Calore is discussed. Microscale heat transfer problems differ from their macroscopic counterparts in that conductive heat transfer in both solid and gaseous materials may have important noncontinuum effects. In a solid material, three noncontinuum effects are considered: ballistic transport of phonons across a thin film, scattering of phonons from surface roughness at a gas-solid interface, and scattering of phonons from grain boundaries within the solid material. These processes are modeled for polycrystalline silicon, and the thermal-conductivity values predicted by these models are compared to experimental data. In a gaseous material, two noncontinuum effects are considered: ballistic transport of gas molecules across a thin gap and accommodation of gas molecules to solid conditions when reflecting from a solid surface. These processes are modeled for arbitrary gases by allowing the gas and solid temperatures across a gas-solid interface to differ: a finite heat transfer coefficient (contact conductance) is imposed at the gas-solid interface so that the temperature difference is proportional to the normal heat flux. In this approach, the behavior of gas in the bulk is not changed from behavior observed under macroscopic conditions. These models are implemented in Calore as user subroutines. The user subroutines reside within Sandia's Source Forge server, where they undergo version control and regression testing and are available to analysts needing these capabilities. A Calore simulation is presented that exercises these models for a heated microbeam separated from an ambient-temperature substrate by a thin gas-filled gap. Failure to use the noncontinuum heat transfer models for the solid and the gas causes the maximum temperature of the microbeam to be significantly underpredicted.
Proton-transfer doping of polyacetylene
Energy Technology Data Exchange (ETDEWEB)
Tolbert, L.M.; Schomaker, J.A. (School of Chemistry and Biochemistry, Georgia Inst. of Tech., Atlanta (USA))
1991-04-30
Exhaustive deprotonation of films of poly(acetylene-co-1,3-butadiene) (PAB) fails to produce a conductive film. In contrast, deprotonation of segmented polyacetylene (SPA) produces a conductive material with similar characteristics to n-doped polyacetylene. Thus the feasibility of a proton-transfer approach to doping of polyacetylene has been demonstrated. (orig.).
Papaleo, Enrico; Pagliardini, Luca; Vanni, Valeria Stella; Delprato, Diana; Rubino, Patrizia; Candiani, Massimo; Viganò, Paola
2017-01-01
A cost analysis covering direct healthcare costs relating to IVF freeze-all policy was conducted. Normal- and high- responder patients treated with a freeze-all policy (n = 63) compared with fresh transfer IVF (n = 189) matched by age, body mass index, duration and cause of infertility, predictive factors for IVF (number of oocytes used for fertilization) and study period, according to a 1:3 ratio were included. Total costs per patient (€6952 versus €6863) and mean costs per live birth were similar between the freeze-all strategy (€13,101, 95% CI 10,686 to 17,041) and fresh transfer IVF (€15,279, 95% CI 13,212 to 18,030). A mean per live birth cost-saving of €2178 (95% CI -1810 to 6165) resulted in a freeze-all strategy owing to fewer embryo transfer procedures (1.29 ± 0.5 versus 1.41 ± 0.7); differences were not significant. Sensitivity analysis revealed that the freeze-all strategy remained cost-effective until the live birth rate is either higher or only slightly lower (≥-0.59%) in the freeze-all group compared with fresh cycles. A freeze-all policy does not increase costs compared with fresh transfer, owing to negligible additional expenses, i.e. vitrification, endometrial priming and monitoring, against fewer embryo transfer procedures required to achieve pregnancy. Copyright © 2016 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.
Finite element simulation of heat transfer
Bergheau, Jean-Michel
2010-01-01
This book introduces the finite element method applied to the resolution of industrial heat transfer problems. Starting from steady conduction, the method is gradually extended to transient regimes, to traditional non-linearities, and to convective phenomena. Coupled problems involving heat transfer are then presented. Three types of couplings are discussed: coupling through boundary conditions (such as radiative heat transfer in cavities), addition of state variables (such as metallurgical phase change), and coupling through partial differential equations (such as electrical phenomena).? A re
Transferring Data from Smartwatch to Smartphone through Mechanical Wave Propagation
Directory of Open Access Journals (Sweden)
Seung-Chan Kim
2015-08-01
Full Text Available Inspired by the mechanisms of bone conduction transmission, we present a novel sensor and actuation system that enables a smartwatch to securely communicate with a peripheral touch device, such as a smartphone. Our system regards hand structures as a mechanical waveguide that transmits particular signals through mechanical waves. As a signal, we used high-frequency vibrations (18.0–20.0 kHz so that users cannot sense the signals either tactually or audibly. To this end, we adopted a commercial surface transducer, which is originally developed as a bone-conduction actuator, for mechanical signal generation. At the receiver side, a piezoelement was adopted for picking up the transferred mechanical signals. Experimental results have shown that the proposed system can successfully transfer data using mechanical waves. We also validate dual-frequency actuations under which high-frequency signals (18.0–20.0 kHz are generated along with low-frequency (up to 250 Hz haptic vibrations. The proposed method has advantages in terms of security in that it does not reveal the signals outside the body, meaning that it is not possible for attackers to eavesdrop on the signals. To further illustrate the possible application spaces, we conclude with explorations of the proposed approach.
Transferring Data from Smartwatch to Smartphone through Mechanical Wave Propagation.
Kim, Seung-Chan; Lim, Soo-Chul
2015-08-28
Inspired by the mechanisms of bone conduction transmission, we present a novel sensor and actuation system that enables a smartwatch to securely communicate with a peripheral touch device, such as a smartphone. Our system regards hand structures as a mechanical waveguide that transmits particular signals through mechanical waves. As a signal, we used high-frequency vibrations (18.0-20.0 kHz) so that users cannot sense the signals either tactually or audibly. To this end, we adopted a commercial surface transducer, which is originally developed as a bone-conduction actuator, for mechanical signal generation. At the receiver side, a piezoelement was adopted for picking up the transferred mechanical signals. Experimental results have shown that the proposed system can successfully transfer data using mechanical waves. We also validate dual-frequency actuations under which high-frequency signals (18.0-20.0 kHz) are generated along with low-frequency (up to 250 Hz) haptic vibrations. The proposed method has advantages in terms of security in that it does not reveal the signals outside the body, meaning that it is not possible for attackers to eavesdrop on the signals. To further illustrate the possible application spaces, we conclude with explorations of the proposed approach.
Industrial furnace with improved heat transfer
Energy Technology Data Exchange (ETDEWEB)
Hoetzl, M.; Lingle, T.M.
1992-07-07
This patent describes an industrial furnace for heating work which emits volatiles during heating. It comprises a generally cylindrical, closed end furnace section defining a sealable heat transfer chamber for heating work disposed therein; fan means for directing furnace atmosphere as a swirling wind mass about the interior of the furnace section over a portion thereof; heat means for heating the wind mass within the fan chamber; and an incineration track formed as a circumferentially extending groove about the exterior of the furnace section and in heat transfer relationship with and situated at least to extend about a portion of the fan chamber.
Conductance of single-atom platinum contacts: Voltage dependence of the conductance histogram
DEFF Research Database (Denmark)
Nielsen, S.K.; Noat, Y.; Brandbyge, Mads
2003-01-01
The conductance of a single-atom contact is sensitive to the coupling of this contact atom to the atoms in the leads. Notably for the transition metals this gives rise to a considerable spread in the observed conductance values. The mean conductance value and spread can be obtained from the first...... peak in conductance histograms recorded from a large set of contact-breaking cycles. In contrast to the monovalent metals, this mean value for Pt depends strongly on the applied voltage bias and other experimental conditions and values ranging from about 1 G(0) to 2.5 G(0) (G(0)=2e(2)/h) have been...... reported. We find that at low bias the first peak in the conductance histogram is centered around 1.5 G(0). However, as the bias increases past 300 mV the peak shifts to 1.8 G(0). Here we show that this bias dependence is due to a geometric effect where monatomic chains are replaced by single-atom contacts...
International Nuclear Information System (INIS)
Muresan, Cristian; Vaillon, Rodolphe; Menezo, Christophe; Morlot, Rodolphe
2004-01-01
The coupled conductive radiative heat transfer in a two-layer slab with Fresnel interfaces subject to diffuse and obliquely collimated irradiation is solved. The collimated and diffuse components problems are treated separately. The solution for diffuse radiation is obtained by using a composite discrete ordinates method and includes the development of adaptive directional quadratures to overcome the difficulties usually encountered at the interfaces. The complete radiation numerical model is validated against the predictions obtained by using the Monte Carlo method
An analysis of the inter-project knowledge transfer in the petrochemical industry
Directory of Open Access Journals (Sweden)
Marcelo Müller Beuren
2015-02-01
Full Text Available This paper presents a knowledge transfer (KT analysis in an operational project management environment of the petrochemical industry. The main objective of this paper is to identify the major barriers and to suggest improvements activities aiming to foster the KT process. To this end, interviews with members of the project department were conducted by means of a questionnaire. Results were analyzed to identify the most problematic barriers and to propose improvements. The study concluded that the greatest difficulties are related to the transfer of tacit knowledge between different teams. The main contribution of this paper is that it presents an analysis of an unexplored environment and it proposes an improvement of the adapted method for KT study, by using a relationship matrix between the questionnaire and the barriers, so that problems can be identified in an easier manner.
Taha, T.J.; Thakur, D.B.; van der Meer, Theodorus H.
2012-01-01
In this work, heat transfer surface modification and heat transfer measurement technique is developed. Heat transfer investigation was aimed to study the effect of carbon nano fibers (extremely high thermal conductive material) on the enhancement level in heat transfer. Synthesis of these carbon
Directory of Open Access Journals (Sweden)
Alistair R D McLean
Full Text Available During pregnancy, immunoglobulin G (IgG is transferred from the mother to the fetus, providing protection from disease in early infancy. Plasmodium falciparum infections may reduce maternofetal antibody transfer efficiency, but mechanisms remain unclear.Mother-cord paired serum samples collected at delivery from Papua New Guinea (PNG and the Thailand-Myanmar Border Area (TMBA were tested for IgG1 and IgG3 to four P. falciparum antigens and measles antigen, as well as total serum IgG. Multivariable linear regression was conducted to assess the association of peripheral P. falciparum infection during pregnancy or placental P. falciparum infection assessed at delivery with maternofetal antibody transfer efficiency. Path analysis assessed the extent to which associations between P. falciparum infection and antibody transfer were mediated by gestational age at delivery or levels of maternal total serum IgG.Maternofetal antibody transfer efficiency of IgG1 and IgG3 was lower in PNG compared to TMBA (mean difference in cord antibody levels (controlling for maternal antibody levels ranged from -0.88 to 0.09, median of -0.20 log2 units. Placental P. falciparum infections were associated with substantially lower maternofetal antibody transfer efficiency in PNG primigravid women (mean difference in cord antibody levels (controlling for maternal antibody levels ranged from -0.62 to -0.10, median of -0.36 log2 units, but not multigravid women. The lower antibody transfer efficiency amongst primigravid women with placental infection was only partially mediated by gestational age at delivery (proportion indirect effect ranged from 0% to 18%, whereas no mediation effects of maternal total serum IgG were observed.Primigravid women may be at risk of impaired maternofetal antibody transport with placental P. falciparum infection. Direct effects of P. falciparum on the placenta, rather than earlier gestational age and elevated serum IgG, are likely responsible for
Rise of mean multiplicity depending on transverse momentum
International Nuclear Information System (INIS)
Troshin, S.M.
1977-01-01
Dependence of mean multiplicity on the transversal momentum transfer is studied. In framework of the model in view, based on possible probabilitic interpretation of the unitarity condition, and assuming a weak correlation between the recoil particle momenta in the intermediate n-particle state, it is shown that mean multiplicity increases linearly with rise of the transversal momentum. Behaviour of the mean multiplicity depending on the impact parameter is also studied
The Clean Development Mechanism and Technology Transfer
DEFF Research Database (Denmark)
Aggarwal, Aradhna
2017-01-01
This study assesses the impact of the Clean Development Mechanism (CDM) on the transfer of clean technology in India. The reason this study is unique is because firstly, it adopts an outcome-oriented approach to define ‘technology transfer’, which means that technology transfer occurs if firms...
Groenewoud, Eva R.; Cantineau, Astrid E. P.; Kollen, Boudewijn J.; Macklon, Nick S.; Cohlen, Ben J.
2013-01-01
Frozenthawed embryo transfer (FET) enables surplus embryos derived from IVF or IVF-ICSI treatment to be stored and transferred at a later date. In recent years the number of FET cycles performed has increased due to transferring fewer embryos per transfer and improved laboratory techniques.
Deterioration in effective thermal conductivity of aqueous magnetic nanofluids
Altan, C.L.; Gurten, B.; Sommerdijk, N.A.J.M.; Bucak, S.
2014-01-01
Common heat transfer fluids have low thermal conductivities, which decrease their efficiency in many applications. On the other hand, solids have much higher thermal conductivity values. Previously, it was shown that the addition of different nanoparticles to various base fluids increases the
An introduction to heat transfer. 2. rev. ed.
International Nuclear Information System (INIS)
Hell, F.
1979-01-01
This book represents a fundamental introduction to heat transfer. Practical problems and tables make the book useful for engeneers and students. The chapters include detailed informations together with exercises of convection, radiat heat transfer, thermal conduction and condensation. (CDS)
DEFF Research Database (Denmark)
Shrestha, Pravin; Malvankar, Nikhil S.; Werner, Jeffrey
2014-01-01
Prior investigation of an upflow anaerobic sludge blanket (UASB) reactor treating brewery wastes suggested that direct interspecies electron transfer (DIET) significantly contributed to interspecies electron transfer to methanogens. To investigate DIET in granules further, the electrical conducti......Prior investigation of an upflow anaerobic sludge blanket (UASB) reactor treating brewery wastes suggested that direct interspecies electron transfer (DIET) significantly contributed to interspecies electron transfer to methanogens. To investigate DIET in granules further, the electrical...... conductivity and bacterial community composition of granules in fourteen samples from four different UASB reactors treating brewery wastes were investigated. All of the UASB granules were electrically conductive whereas control granules from ANAMMOX (ANaerobic AMMonium OXidation) reactors and microbial...... granules from an aerobic bioreactor designed for phosphate removal were not. There was a moderate correlation (r = 0.67) between the abundance of Geobacter species in the UASB granules and granule conductivity, suggesting that Geobacter contributed to granule conductivity. These results, coupled...
Batzias, Dimitris F.; Ifanti, Konstantina
2012-12-01
Process simulation models are usually empirical, therefore there is an inherent difficulty in serving as carriers for knowledge acquisition and technology transfer, since their parameters have no physical meaning to facilitate verification of the dependence on the production conditions; in such a case, a 'black box' regression model or a neural network might be used to simply connect input-output characteristics. In several cases, scientific/mechanismic models may be proved valid, in which case parameter identification is required to find out the independent/explanatory variables and parameters, which each parameter depends on. This is a difficult task, since the phenomenological level at which each parameter is defined is different. In this paper, we have developed a methodological framework under the form of an algorithmic procedure to solve this problem. The main parts of this procedure are: (i) stratification of relevant knowledge in discrete layers immediately adjacent to the layer that the initial model under investigation belongs to, (ii) design of the ontology corresponding to these layers, (iii) elimination of the less relevant parts of the ontology by thinning, (iv) retrieval of the stronger interrelations between the remaining nodes within the revised ontological network, and (v) parameter identification taking into account the most influential interrelations revealed in (iv). The functionality of this methodology is demonstrated by quoting two representative case examples on wastewater treatment.
Heat transfer correlations in mantle tanks
DEFF Research Database (Denmark)
Furbo, Simon; Knudsen, Søren
2005-01-01
on calculations with a CFD-model, which has earlier been validated by means of experiments. The CFD-model is used to determine the heat transfer between the solar collector fluid in the mantle and the walls surrounding the mantle in all levels of the mantle as well as the heat transfer between the wall...... transfer correlations are suitable as input for a detailed simulation model for mantle tanks. The heat transfer correlations determined in this study are somewhat different from previous reported heat transfer correlations. The reason is that this study includes more mantle tank designs and operation......Small solar domestic hot water systems are best designed as low flow systems based on vertical mantle tanks. Theoretical investigations of the heat transfer in differently designed vertical mantle tanks during different operation conditions have been carried out. The investigations are based...
Experience transfer in Norwegian oil and gas industry: Approaches and organizational mechanisms
Energy Technology Data Exchange (ETDEWEB)
Aase, Karina
1997-12-31
The main objective of this thesis has been to explore how experience transfer works in Norwegian oil and gas industry. This includes how the concept of experience transfer is defined, what the barriers to achieve experience transfer are, how the oil and gas companies address experience transfer, and how these approaches work. The thesis is organized in five papers: (1) describes how organizational members perceive experience transfer and then specifies the organizational and structural barriers that must be overcome to achieve efficient transfer. (2) discusses the organizational means an oil company implements to address experience transfer. (3) describes a process of improving and using requirement and procedure handbooks for experience transfer. (4) explores how the use of information technology influences experience transfer. (5) compares organizational members` perceptions of experience transfer means in an oil company and an engineering company involved in offshore development projects. 277 refs., 3 figs., 29 tabs.
Experience transfer in Norwegian oil and gas industry: Approaches and organizational mechanisms
Energy Technology Data Exchange (ETDEWEB)
Aase, Karina
1998-12-31
The main objective of this thesis has been to explore how experience transfer works in Norwegian oil and gas industry. This includes how the concept of experience transfer is defined, what the barriers to achieve experience transfer are, how the oil and gas companies address experience transfer, and how these approaches work. The thesis is organized in five papers: (1) describes how organizational members perceive experience transfer and then specifies the organizational and structural barriers that must be overcome to achieve efficient transfer. (2) discusses the organizational means an oil company implements to address experience transfer. (3) describes a process of improving and using requirement and procedure handbooks for experience transfer. (4) explores how the use of information technology influences experience transfer. (5) compares organizational members` perceptions of experience transfer means in an oil company and an engineering company involved in offshore development projects. 277 refs., 3 figs., 29 tabs.
Graphite curtain vacuum outgassing and heat transfer. Final report
International Nuclear Information System (INIS)
Fivel, H.J.; Lang, G.P.; Kipp, H.W.
1976-12-01
Thermal conductivity of a bundle of high conductivity graphite fibers (T-50) was measured as a function of temperature, density and fiber orientation at pressures of 10 -4 to 10 -5 torr. All 3 variables had a significant influence on thermal conductivity. The highest conductivity fiber bundle tested had a conductivity significantly less than dense, bulk nuclear grade graphite. The incorporation of heat pipes into a graphite spectral shaper will permit a 2-fold thicker shaper. Heat pipes not only increase the transport of heat within the spectral shaper but can increase heat transfer at the shaper-first wall interface and potentially serve as a means of attaching shaper modules to the first wall. A heat pipe using a liquid metal working fluid was fabricated and tested in magnetic fields of 1 and 2 Tesla. Liquid metal heat pipes can be used in a magnetic field of at least up to 2 Tesla. Much more work needs to be done to establish the capabilities for high performance heat pipes when used in magnetic fields. Four different types of graphite fibers were exposed in EBR-II to a neutron fluence of 3.5 x 10 21 cm -2 EFF at 470 0 C. Large axial shrinkages of 6.6 to 8.6% resulted
48 CFR 970.2770-3 - Technology transfer and patent rights.
2010-10-01
... cooperative research and development agreements with public and private entities for purposes of conducting research and development and transferring technology to the private sector. In implementing the NCTTA, DOE....2770-3 Technology transfer and patent rights. The National Competitiveness Technology Transfer Act of...
A two-parameter nondiffusive heat conduction model for data analysis in pump-probe experiments
Ma, Yanbao
2014-12-01
Nondiffusive heat transfer has attracted intensive research interests in last 50 years because of its importance in fundamental physics and engineering applications. It has unique features that cannot be described by the Fourier law. However, current studies of nondiffusive heat transfer still focus on studying the effective thermal conductivity within the framework of the Fourier law due to a lack of a well-accepted replacement. Here, we show that nondiffusive heat conduction can be characterized by two inherent material properties: a diffusive thermal conductivity and a ballistic transport length. We also present a two-parameter heat conduction model and demonstrate its validity in different pump-probe experiments. This model not only offers new insights of nondiffusive heat conduction but also opens up new avenues for the studies of nondiffusive heat transfer outside the framework of the Fourier law.
Further evidence for a fluid pathway during bone conduction auditory stimulation.
Sohmer, Haim; Freeman, Sharon
2004-07-01
This study was designed to evaluate the suggestion that during bone vibrator stimulation on skull bone (bone conduction auditory stimulation), a major connection between the site of the bone vibrator and the inner ear is a fluid pathway. A series of experiments were conducted on pairs of animals (rats or guinea pigs). The cranial cavities of each pair of animals were coupled by means of a saline filled plastic tube sealed into a craniotomy in the skull of each animal. In response to bone conduction click stimulation to the skull bone of animal I, auditory nerve-brainstem evoked responses could be recorded in animal II. Various procedures showed that these responses were initiated in animal II in response to audio-frequency sound pressures generated within the cranial cavity of animal I by the bone conduction stimulation and transferred to the cranial cavity of animal II through the fluid in the plastic tube: they were not responses to air conducted sounds generated by the bone vibrator, were not induced in animal II by vibrations conveyed to it by the plastic tube and were not electrically conducted activity from animal I. Exposing the fluid in the tube to air was not accompanied by any change in threshold. These experiments confirm that during bone conduction stimulation on the skull, audio-frequency sound pressures (alternating condensations and rarefactions) can be conveyed by a fluid pathway to the cochlea and stimulate it.
Interhospital transfer delays emergency abdominal surgery and prolongs stay.
Limmer, Alexandra M; Edye, Michael B
2017-11-01
Interhospital transfer of patients requiring emergency surgery is common practice. It has the potential to delay surgical intervention, increase rate of complications and thus length of hospital stay. A retrospective cohort study was conducted of adult patients who underwent emergency surgery for abdominal pain at a large metropolitan hospital in New South Wales (Hospital A) in 2013. The impact of interhospital transfer on time to surgical intervention, post-operative length of stay and overall length of stay was assessed. Of the 910 adult patients who underwent emergency surgery for abdominal pain at Hospital A in 2013, 31.9% (n = 290) were transferred by road ambulance from a local district hospital (Hospital B). The leading surgical procedures performed were appendicectomy (n = 299, 32.9%), cholecystectomy (n = 174, 19.1%), gastrointestinal endoscopy (n = 95, 10.4%), cystoscopy (n = 86, 9.5%), hernia repair (n = 45, 4.9%), salpingectomy (n = 19, 2.1%) and oversewing of perforated peptic ulcer (n = 13, 1.4%). Overall, interhospital transfer (n = 290, 31.9%) was associated with increases in mean time to surgical intervention (14.2 h, P < 0.001), post-operative length of stay (1.1 days, P = 0.001) and overall length of stay (1.6 days, P < 0.001). Delayed surgical intervention was observed across all procedure types except surgery for perforated peptic ulcer, where transferred patients underwent surgery within a comparable timeframe to direct admissions. Interhospital transfer delays surgical intervention and increases length of hospital stay. This mandates attention due to the implications for patient outcomes and added burden to the healthcare system. The system did, however, show capability to appropriately expedite surgery for acutely life-threatening cases. © 2016 Royal Australasian College of Surgeons.
Thermal conductivity of crushed salt
International Nuclear Information System (INIS)
Kuehn, K.
Heat transfer through an annular space filled with crushed salt depends primarily on the thermal conductivity, lambda, of the material. This report gives a formula with which lambda can be computed. The formula includes two quantities that can be influenced through screening of the salt smalls: the porosity, psi, and the fraction, alpha, of the more highly resistive heat-flow paths. The report computes and presents graphically the thermal conductivities for various values of psi and alpha. Heat-transfer properties are computed and compared for an annular space filled with crushed salt and for an air gap. The comparison shows that the properties of the annular space are larger only up to a certain temperature, because the properties of the air gap increase exponentially while those f the annular space increase only in an approximately linear way. Experimental results from Project Salt Vault in the U.S. are in good agreement with the calculations performed. Trials in Temperature Experimental Field 2 at the Asse II salt mine will provide an additional check on the calculations. 3 figures, 3 tables
Elementary heat transfer analysis
Whitaker, Stephen; Hartnett, James P
1976-01-01
Elementary Heat Transfer Analysis provides information pertinent to the fundamental aspects of the nature of transient heat conduction. This book presents a thorough understanding of the thermal energy equation and its application to boundary layer flows and confined and unconfined turbulent flows. Organized into nine chapters, this book begins with an overview of the use of heat transfer coefficients in formulating the flux condition at phase interface. This text then explains the specification as well as application of flux boundary conditions. Other chapters consider a derivation of the tra
Bach, Aaron J E; Stewart, Ian B; Disher, Alice E; Costello, Joseph T
2015-01-01
Skin temperature assessment has historically been undertaken with conductive devices affixed to the skin. With the development of technology, infrared devices are increasingly utilised in the measurement of skin temperature. Therefore, our purpose was to evaluate the agreement between four skin temperature devices at rest, during exercise in the heat, and recovery. Mean skin temperature ([Formula: see text]) was assessed in thirty healthy males during 30 min rest (24.0 ± 1.2°C, 56 ± 8%), 30 min cycle in the heat (38.0 ± 0.5°C, 41 ± 2%), and 45 min recovery (24.0 ± 1.3°C, 56 ± 9%). [Formula: see text] was assessed at four sites using two conductive devices (thermistors, iButtons) and two infrared devices (infrared thermometer, infrared camera). Bland-Altman plots demonstrated mean bias ± limits of agreement between the thermistors and iButtons as follows (rest, exercise, recovery): -0.01 ± 0.04, 0.26 ± 0.85, -0.37 ± 0.98°C; thermistors and infrared thermometer: 0.34 ± 0.44, -0.44 ± 1.23, -1.04 ± 1.75°C; thermistors and infrared camera (rest, recovery): 0.83 ± 0.77, 1.88 ± 1.87°C. Pairwise comparisons of [Formula: see text] found significant differences (p heat and recovery. These results indicate poor agreement between conductive and infrared devices at rest, during exercise in the heat, and subsequent recovery. Infrared devices may not be suitable for monitoring [Formula: see text] in the presence of, or following, metabolic and environmental induced heat stress.
Daryabeigi, Kamran; Cunnington, George R.; Miller, Steve D.; Knutson, Jeffry R.
2010-01-01
Combined radiation and conduction heat transfer through various high-temperature, high-porosity, unbonded (loose) fibrous insulations was modeled based on first principles. The diffusion approximation was used for modeling the radiation component of heat transfer in the optically thick insulations. The relevant parameters needed for the heat transfer model were derived from experimental data. Semi-empirical formulations were used to model the solid conduction contribution of heat transfer in fibrous insulations with the relevant parameters inferred from thermal conductivity measurements at cryogenic temperatures in a vacuum. The specific extinction coefficient for radiation heat transfer was obtained from high-temperature steady-state thermal measurements with large temperature gradients maintained across the sample thickness in a vacuum. Standard gas conduction modeling was used in the heat transfer formulation. This heat transfer modeling methodology was applied to silica, two types of alumina, and a zirconia-based fibrous insulation, and to a variation of opacified fibrous insulation (OFI). OFI is a class of insulations manufactured by embedding efficient ceramic opacifiers in various unbonded fibrous insulations to significantly attenuate the radiation component of heat transfer. The heat transfer modeling methodology was validated by comparison with more rigorous analytical solutions and with standard thermal conductivity measurements. The validated heat transfer model is applicable to various densities of these high-porosity insulations as long as the fiber properties are the same (index of refraction, size distribution, orientation, and length). Furthermore, the heat transfer data for these insulations can be obtained at any static pressure in any working gas environment without the need to perform tests in various gases at various pressures.
Essentially Optimal Universally Composable Oblivious Transfer
DEFF Research Database (Denmark)
Damgård, Ivan Bjerre; Nielsen, Jesper Buus; Orlandi, Claudio
2009-01-01
. Communication complexity: it communicates O(1) group elements to transfer one out of two group elements. The Big-O notation hides 32, meaning that the communication is probably not optimal, but is essentially optimal in that the overhead is at least constant. Our construction is based on pairings, and we assume......Oblivious transfer is one of the most important cryptographic primitives, both for theoretical and practical reasons and several protocols were proposed during the years. We provide the first oblivious transfer protocol which is simultaneously optimal on the following list of parameters: Security...
Debugging Data Transfers in CMS
Bagliesi, G; Bloom, K; Bockelman, B; Bonacorsi, D; Fisk, I; Flix, J; Hernandez, J; D'Hondt, J; Kadastik, M; Klem, J; Kodolova, O; Kuo, C M; Letts, J; Maes, J; Magini, N; Metson, S; Piedra, J; Pukhaeva, N; Tuura, L; Sonajalg, S; Wu, Y; Van Mulders, P; Villella, I; Wurthwein, F
2010-01-01
The CMS experiment at CERN is preparing for LHC data taking in several computing preparation activities. In early 2007 a traffic load generator infrastructure for distributed data transfer tests called the LoadTest was designed and deployed to equip the WLCG sites that support CMS with a means for debugging, load-testing and commissioning data transfer routes among CMS computing centres. The LoadTest is based upon PhEDEx as a reliable, scalable data set replication system. The Debugging Data Transfers (DDT) task force was created to coordinate the debugging of the data transfer links. The task force aimed to commission most crucial transfer routes among CMS sites by designing and enforcing a clear procedure to debug problematic links. Such procedure aimed to move a link from a debugging phase in a separate and independent environment to a production environment when a set of agreed conditions are achieved for that link. The goal was to deliver one by one working transfer routes to the CMS data operations team...
International Nuclear Information System (INIS)
Assy, Ali; Lefèvre, Stéphane; Chapuis, Pierre-Olivier; Gomès, Séverine
2014-01-01
Quantitative measurements of local nanometer-scale thermal measurements are difficult to achieve because heat flux may be transferred from the heated sensor to the cold sample through various elusive mixed thermal channels. This paper addresses one of these channels, the water meniscus at the nano-contact between a heated atomic force microscopy probe and a hydrophilic sample. This heat transfer mechanism is found to depend strongly on the probe temperature. The analysis of the pull-off forces as a function of temperature indicates that the water film almost vanishes above a probe mean temperature between 120 and 150 ºC. In particular, a methodology that allows for correlating the thermal conductance of the water meniscus to the capillary forces is applied. In the case of the standard scanning thermal microscopy Wollaston probe, values of this thermal conductance show that the water meniscus mechanism is not dominant in the thermal interaction between the probe and the sample, regardless of probe temperature. (fast track communication)
Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters
Energy Technology Data Exchange (ETDEWEB)
Day-Lewis, Frederick David [US Geological Survey, Storrs, CT (United States); Singha, Kamini [Colorado School of Mines, Golden, CO (United States); Johnson, Timothy C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Haggerty, Roy [Oregon State Univ., Corvallis, OR (United States); Binley, Andrew [Lancaster Univ. (United Kingdom); Lane, John W. [US Geological Survey, Storrs, CT (United States)
2014-11-25
Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3
Bai, Yu; Zhang, Jing; Wang, Yinghui; Zhang, Min; Wang, Peng
2011-04-19
Lithium ions are known for their potent function in modulating the energy alignment at the oxide semiconductor/dye/electrolyte interface in dye-sensitized solar cells (DSCs), offering the opportunity to control the associated multichannel charge-transfer dynamics. Herein, by optimizing the lithium iodide content in 1-ethyl-3-methylimidazolium dicyanamide-based ionic liquid electrolytes, we present a solvent-free DSC displaying an impressive 8.4% efficiency at 100 mW cm(-2) AM1.5G conditions. We further scrutinize the origins of evident impacts of lithium ions upon current density-voltage characteristics as well as photocurrent action spectra of DSCs based thereon. It is found that, along with a gradual increase of the lithium content in ionic liquid electrolytes, a consecutive diminishment of the open-circuit photovoltage arises, primarily owing to a noticeable downward movement of the titania conduction band edge. The conduction band edge displacement away from vacuum also assists the formation of a more favorable energy offset at the titania/dye interface, and thereby leads to a faster electron injection rate and a higher exciton dissociation yield as implied by transient emission measurements. We also notice that the adverse influence of the titania conduction band edge downward shift arising from lithium addition upon photovoltage is partly compensated by a concomitant suppression of the triiodide involving interfacial charge recombination. © 2011 American Chemical Society
International Nuclear Information System (INIS)
Torabi, Mohsen; Zhang, Kaili
2015-01-01
Highlights: • First and second laws of thermodynamics have been investigated in a composite wall. • Convective–radiative heat transfer is assumed on both surfaces. • Optimum interface location is calculated to minimize the total entropy generation rate. • Thermal conductivities ratio has great effects on the temperature and entropy generation. - Abstract: Composite geometries have numerous applications in industry and scientific researches. This work investigates the temperature distribution, and local and total entropy generation rates within two-layer composite walls using conjugate convection and radiation boundary conditions. Thermal conductivities of the materials of walls are assumed temperature-dependent. Temperature-dependent internal heat generations are also incorporated into the modeling. The differential transformation method (DTM) is used as an analytical technique to tackle the highly nonlinear system of ordinary differential equations. Thereafter, the local and total entropy generation rates are calculated using the DTM formulated temperature distribution. An exact analytical solution, for the temperature-independent model without radiation effect, is also derived. The correctness and accuracy of the DTM solution are checked against the exact solution. After verification, effects of thermophysical parameters such as location of the interface, convection–conduction parameters, radiation–conduction parameters, and internal heat generations, on the temperature distribution, and both local and total entropy generation rates are examined. To deliver the minimum total entropy generation rate, optimum values for some parameters are also found. Since composite walls are widely used in many fields, the abovementioned investigation is a beneficial tool for many engineering industries and scientific fields to minimize the entropy generation, which is the exergy destruction, of the system
The conducting shell stellarator: A simple means for producing complicated fields
International Nuclear Information System (INIS)
Sheffield, G.V.
1997-01-01
One of the main characteristics of stellarators, both helical and modular, is that their coil sets must take difficult shapes in order to produce the complicated stellarator magnetic fields. The complex coil shapes make fabrication difficult and costly compared to say the toroidal field, TF, coil set of a tokamak. The conducting shell stellarator, CSS, configuration described in this report shows that complicated stellarator fields can be produced by inducing eddy currents in a conducting shell from a simple TF coil set (a field that varies like 1/R). This technique is applicable not only to a pulsed system at room or cryogenic temperatures, but can be implemented for a superconducting TF with a superconducting shell in a stellarator reactor. The CSS has the added benefit that within this device the metallic shell which can be made up of discrete plates can be changed out and replaced with new plates to create a different stellarator configuration within the same TF coil set. The work of creating the complicated magnetics is done by the passive conductor reshaping the simple TF field
Efficient formulation of the finite element method for heat conduction in solids
International Nuclear Information System (INIS)
Sandsmark, N.; Aamodt, B.; Medonos, S.
1977-01-01
The purpose of the paper is to describe efficient methods and computer programs for analysis of heat conduction problems related to design and control of components of nuclear power plants and similar structures where thermal problems are of interest. A short presentation of basic equations and the finite element formulation of three-dimensional stationary and transient heat conduction is given. The finite element types that are used are isoparametric hexahedrons with eight or twenty nodes. The use of consistent as well as diagonal capacity matrices is discussed. Reduction of the transient heat conduction problem may be accomplished by means of the 'master-slave' technique. Furthermore, the superelement technique is discussed for both stationary and transient heat conduction. For the solution of transient problems, the trapezoidal time integration scheme is used. The methods and principles outlined in the paper are materialized in a computer program, NV615, which is one of the application programs in the program system SESAM-69. A brief description is given of NV615. Furthermore, attention is given to combined heat conduction and subsequent thermal stress analysis. Data representing geometry, calculated temperature distribution etc. may be transferred automatically from the heat conduction program to stress analysis programs. As an example of practical application the temperature distribution versus time in a turbine wheel during start up is analysed. Thermal stresses are calculated at selected time instants
An introduction to heat transfer principles and calculations
Ede, A J; Ower, E
1967-01-01
An Introduction to Heat Transfer Principles and Calculations is an introductory text to the principles and calculations of heat transfer. The theory underlying heat transfer is described, and the principal results and formulae are presented. Available techniques for obtaining rapid, approximate solutions to complicated problems are also considered. This book is comprised of 12 chapters and begins with a brief account of some of the concepts, methods, nomenclature, and other relevant information about heat transfer. The reader is then introduced to radiation, conduction, convection, and boiling
Energy Technology Data Exchange (ETDEWEB)
Perez Galindo, Jose Arturo; Garcia Gutierrez, Alonso [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)
1986-12-31
This work describes the experimental technique for the sublimation of naphthalene in air which measures heat transfer coefficients through the use of the analogy between the transference phenomena of heat and mass. The technique used to substitute the experimental measurements of heat transfer, in which it is difficult to control the border thermal conditions, when they are dimmed by the omnipresent problem of heat conduction through the walls of the transference surfaces. Two examples are included of the application technique and its potential is outlined. [Espanol] En este trabajo se describe la tecnica experimental de la sublimacion de naftalina en aire mediante la que se miden coeficientes de transferencia de masa. Los datos asi obtenidos pueden convertirse en coeficientes de transferencia de calor a traves del uso de la analogia entre los fenomenos de transferencia de calor y masa. La tecnica se utiliza para substituir las mediciones experimentales de transferencia de calor, en las que es dificil controlar las condiciones termicas de frontera, cuando las empana el problema omnipresente de la conduccion de calor a traves de las paredes de las superficies de transferencia. Se incluyen dos ejemplos de la aplicacion de la tecnica y se destaca su potencial.
Energy Technology Data Exchange (ETDEWEB)
Perez Galindo, Jose Arturo; Garcia Gutierrez, Alonso [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)
1985-12-31
This work describes the experimental technique for the sublimation of naphthalene in air which measures heat transfer coefficients through the use of the analogy between the transference phenomena of heat and mass. The technique used to substitute the experimental measurements of heat transfer, in which it is difficult to control the border thermal conditions, when they are dimmed by the omnipresent problem of heat conduction through the walls of the transference surfaces. Two examples are included of the application technique and its potential is outlined. [Espanol] En este trabajo se describe la tecnica experimental de la sublimacion de naftalina en aire mediante la que se miden coeficientes de transferencia de masa. Los datos asi obtenidos pueden convertirse en coeficientes de transferencia de calor a traves del uso de la analogia entre los fenomenos de transferencia de calor y masa. La tecnica se utiliza para substituir las mediciones experimentales de transferencia de calor, en las que es dificil controlar las condiciones termicas de frontera, cuando las empana el problema omnipresente de la conduccion de calor a traves de las paredes de las superficies de transferencia. Se incluyen dos ejemplos de la aplicacion de la tecnica y se destaca su potencial.
The electrical conductivity of sodium polysulfide melts
Energy Technology Data Exchange (ETDEWEB)
Meihui Wang.
1992-06-01
The sodium polysulfide melt has been described by a macroscopic model. This model considers the melt to be composed of sodium cations, monosulfide anions, and neutral sulfur solvent. The transport equations of concentrated-solution theory are used to derived the governing equations for this binaryelectrolyte melt model. These equations relate measurable transport properties to fundamental transport parameters. The focus of this research is to measure the electrical conductivity of sodium polysulfide melts and calculate one of fundamental transport parameters from the experimental data. The conductance cells used in the conductivity measurements are axisymmetric cylindrical cells with a microelectrode. The electrode effects, including double-layer capacity, charge transfer resistance, and concentration overpotential, were minimized by the use of the alternating current at an adequately high frequency. The high cell constants of the conductance cells not only enhanced the experimental accuracy but also made the electrode effects negligible. The electrical conductivities of sodium polysulfide Na{sub 2}S{sub 4} and Na{sub 2}S{sub 5} were measured as a function of temperature (range: 300 to 360{degree}C). Variations between experiments were only up to 2%. The values of the Arrhenius activation energy derived from the experimental data are about 33 kJ/mol. The fundamental transport parameter which quantifies the interaction within sodium cations and monosulfide anions are of interest and expected to be positive. Values of it were calculated from the experimental conductivity data and most of them are positive. Some negative values were obtained probably due to the experimental errors of transference number, diffusion coefficient, density or conductivity data.
Transfer coefficients in elliptical tubes and plate fin heat exchangers
International Nuclear Information System (INIS)
Saboya, S.M.
1979-09-01
Mean transfer coefficients in elliptical tubes and plate fin heat exchangers were determined by application of heat and mass transfer analogy in conjunction with the naphthalene sublimation technique. The transfer coefficients are presented in a dimensionless form as functions of the Reynolds number. By using the least squares method analytical expressions for the transfer coefficients were determined with low scattering. (E.G.) [pt
Transfer coefficients for plate fin and elliptical tube heat exchangers
International Nuclear Information System (INIS)
Saboya, S.M.; Saboya, F.E.M.
1981-01-01
In order to determine transfer coefficients for plate fin and elliptical tube exchangers, mass transfer experiments have been performed using the naphthalene sublimation technique. By means of the heat-mass transfer analogy, the results can be converted to heat transfer results. The transfer coefficients were compared with those for circular tube exchangers and the comparison revealed no major differences. This is a positive outcome, since the use of elliptical tubes may reduce substantially the pressure drop, without affecting the transfer characteristics.(Author) [pt
Chouaib, Wafa; Alila, Younes; Caldwell, Peter V.
2018-05-01
The need for predictions of flow time-series persists at ungauged catchments, motivating the research goals of our study. By means of the Sacramento model, this paper explores the use of parameter transfer within homogeneous regions of similar climate and flow characteristics and makes comparisons with predictions from a priori parameters. We assessed the performance using the Nash-Sutcliffe (NS), bias, mean monthly hydrograph and flow duration curve (FDC). The study was conducted on a large dataset of 73 catchments within the eastern US. Two approaches to the parameter transferability were developed and evaluated; (i) the within homogeneous region parameter transfer using one donor catchment specific to each region, (ii) the parameter transfer disregarding the geographical limits of homogeneous regions, where one donor catchment was common to all regions. Comparisons between both parameter transfers enabled to assess the gain in performance from the parameter regionalization and its respective constraints and limitations. The parameter transfer within homogeneous regions outperformed the a priori parameters and led to a decrease in bias and increase in efficiency reaching a median NS of 0.77 and a NS of 0.85 at individual catchments. The use of FDC revealed the effect of bias on the inaccuracy of prediction from parameter transfer. In one specific region, of mountainous and forested catchments, the prediction accuracy of the parameter transfer was less satisfactory and equivalent to a priori parameters. In this region, the parameter transfer from the outsider catchment provided the best performance; less-biased with smaller uncertainty in medium flow percentiles (40%-60%). The large disparity of energy conditions explained the lack of performance from parameter transfer in this region. Besides, the subsurface stormflow is predominant and there is a likelihood of lateral preferential flow, which according to its specific properties further explained the reduced
Spray characteristics and spray cooling heat transfer in the non-boiling regime
International Nuclear Information System (INIS)
Cheng, Wen-Long; Han, Feng-Yun; Liu, Qi-Nie; Fan, Han-Lin
2011-01-01
Spray cooling is an effective method for dissipating high heat fluxes in the field of electronics thermal control. In this study, experiments were performed with distilled water as a test liquid to study the spray cooling heat transfer in non-boiling regime. A Phase Doppler Anemometry (PDA) was used to study the spray characteristics. The effects of spray flow rate, spray height, and inlet temperature on spray cooling heat transfer were investigated. It was found that the parameters affect heat transfer of spray cooling in non-boiling regime by the spray characteristics and working fluid thermophysical properties. Then the corresponding droplet axial velocity and Sauter mean diameter (SMD) were successfully correlated with mean absolute error of 15%, which were based upon the orifice diameter, the Weber and Reynolds numbers of the orifice flow prior to liquid breakup, dimensionless spray height and spray cross-section radius. The heat transfer in non-boiling regime was correlated with a mean absolute error of 7%, which was mainly associated with the working fluid thermophysical properties, the Weber and Reynolds numbers hitting the heating surface, dimensionless heating surface temperature and diameter. -- Highlights: → The spray flow rate, spray height, and inlet temperature affect heat transfer of spray cooling in non-boiling regime by the spray characteristics and the working fluid thermophysical properties. → Then the corresponding droplet axial velocity and Sauer mean diameter (SMD) were successfully correlated with mean absolute error of 15%. → The heat transfer in non-boiling regime was correlated with a mean absolute error of 7%.
An ecofriendly graphene-based nanofluid for heat transfer applications
DEFF Research Database (Denmark)
Mehrali, Mohammad; Sadeghinezhad, Emad; Akhiani, Amir Reza
2016-01-01
including chemical stability, viscosity, wettability, electrical conductivity and thermal conductivity were investigated in a comprehensive manner. A significant thermal conductivity enhancement amounting to 45.1% was obtained for a volume fraction of 4%. In addition, the convective heat transfer...... that the generated nanofluid will open a new avenue in the pursuit of ecofriendly thermal conductors for heat transfer applications....... coefficient of the nanofluid in a laminar flow regime with uniform wall heat flux was investigated to estimate its cooling capabilities. These results, firmly confirm that the generated graphene-based nanofluid is a formidable transporter of heat and yet ecofriendly. Therefore, it's anticipate...
Castro, Erin L.; Cortez, Edén
2017-01-01
This qualitative study examines the experiences of six Mexican community college transfer students attending a research-intensive institution in the Pacific Northwest. Using semi-structured interviews, the objectives of this study were to 1) understand how Mexican students made meaning of their transfer experiences and 2) how those experiences…
Conductivity of ion dielectrics during the mean flux-density electron- and X-ray pulse radiation
International Nuclear Information System (INIS)
Vajsburd, D.I.; Mesyats, G.A.; Naminov, V.L.; Tavanov, Eh.G.
1982-01-01
Conductivity of ion dielectrics under electron and X-ray pulse radiation is investigated. Investigations have been conducted in the range of average beam densities in which extinction of low-energy conductivity takes place. Thin plates of alkali-halogen crystals have been used as samples. Small-dimensional accelerator with controlled beam parameters: 1-20 ns, 0.1-2000 A/cm 2 , 0.3-0.5 MeV has been used for radiation. Temperature dependence of conductivity current pulse is determined. Time resolution of 10 - 10 s is achieved. In the 70-300 K range it practically coincides with radiation pulse. An essential inertial constituent is observed below 300 K. It is shown that at average beam densities a comparable contribution into fast conductivity is made by intracentre conductivity independent of temperature and high-temperature conductivity which decreases with temperature with activation energy equal to the energy of short-wave background. That is why amplitude of fast constituent decreases with temperature slower than high-energy conductivity
Radiation-induced conductivity of polynaphthoyl benzimidazole
Energy Technology Data Exchange (ETDEWEB)
Tiutnev, A P; Berlin, A M; Saenko, V S; Rusanov, A L; Korshak, V V
1985-01-01
The nonstationary radiation-induced conductivity of polynaphthoyl benzimidazole, synthesized by single-stage high-temperature catalytic polycondensation, is investigated experimentally. It is shown that the radiation-induced conductivity of this material is characterized by an anomalous (non-Gaussian) transfer of excess charge carriers. The activation energy of the delayed component (0.1 ms after pulse termination) is determined to be 0.12 eV; the volt-ampere characteristic of this component is nonlinear, with the coefficient of nonlinearity increasing with the intensity of the external electric field. Experimental results are interpreted on the basis of the phenomenological theory of jump conductivity proposed by Zviagin. 15 references.
Mass transfer measurements in foams
International Nuclear Information System (INIS)
Leblond, J.G.; Fournel, B.
2004-01-01
Full text of publication follows:This study participates to the elaboration of a method for decontamination of the inside surfaces of steel structures (pipes, tanks,...). The solution which has been chosen is to attack the surface of the structure by a dipping solution. In order to reduce the quantity of product to be recovered and treated at the end of the cleaning process, the active solution will be introduced as a foam. During its free or forced drainage the foam supplies an active liquid film along the structure surfaces. It was important to know if the transfers of the dipping liquid inside the foam and between foam and wall film are sufficient to allow a correct supplying of the active liquid at the wall and a correct dragging of the dipped products. The objective of this work is to develop a numerical model which simulates the various transfers. However such a modeling cannot be performed without a thorough knowledge of the different transfer parameters in the foam and in the film. The following study has been performed on a model foam (foaming water + air) held in a smooth vertical glass pipe and submitted to a forced drainage by the foaming water (water + surfactants). The liquid transfer involves the dispersion of the drainage liquid inside the foam and the transfer between the foam and the liquid film flowing down at the wall. The different transfers has been analyzed by NMR using a PFGSE-NMR sequence, which allows to determine the propagator, i.e., the probability density of the liquid particle displacements during a given time interval Δt, along a selected direction. This study allowed to measure, firstly, the mean liquid and the liquid dispersion in the foam along the vertical and horizontal direction, and secondly, the vertical mean velocity in the parietal liquid film. (authors)
International Nuclear Information System (INIS)
Mehta, Siddharth; Chauhan, K. Prashanth; Kanagaraj, S.
2011-01-01
Nanofluid is an innovative heat transfer fluid with superior potential for enhancing the heat transfer performance of conventional fluids. Though many attempts have been made to investigate the abnormal high thermal conductivity of nanofluids, the existing models cannot precisely predict the same. An attempt has been made to develop a model for predicting the thermal conductivity of different types of nanofluids. The model presented here is derived based on the fact that thermal conductivity of nanofluids depends on thermal conductivity of particle and fluid as well as micro-convective heat transfer due to Brownian motion of nanoparticles. Novelty of the article lies in giving a unique equation which predicts thermal conductivity of nanofluids for different concentrations and particle sizes which also correctly predicts the trends observed in experimental data over a wide range of particle sizes, temperatures, and particle concentrations.
A model for gap conductance in nuclear fuel rods
International Nuclear Information System (INIS)
Loyalka, S.K.
1982-01-01
Computation of nuclear reactor fuel behavior under normal and off-normal conditions is influenced by gap conductance models. These models should provide accurate results for heat transfer for arbitrary gap widths and gas mixtures and should be based on considerations of the kinetic theory of gases. There has been considerable progress in the study of heat transfer in a simple gas for arbitrary Knudsen numbers (Kn = l/similar to d, where l is a meanfree-path and similar d is the gap width) in recent years. Using these recent results, a simple expression for heat transfer in a gas mixture (enclosed between parallel plates) for an arbitrary Knudsen number has been constructed, and a new model for gap conductance has been proposed. The latter reproduces the free molecular (small gap, Kn >> 1) and the jump limits (large gaps, Kn << 1) correctly, and it provides fairly accurate results for arbitrary gap widths. The new model is suitable for use in large fuel behavior computer programs
Ozone mass transfer and kinetics experiments
International Nuclear Information System (INIS)
Bollyky, L.J.; Beary, M.M.
1981-12-01
Experiments were conducted at the Hanford Site to determine the most efficient pH and temperature levels for the destruction of complexants in Hanford high-level defense waste. These complexants enhance migration of radionuclides in the soil and inhibit the growth of crystals in the evaporator-crystallizer. Ozone mass transfer and kinetics tests have been outlined for the determination of critical mass transfer and kinetics parameters of the ozone-complexant reaction
TRANSFER PRICES IN ROMANIAN ECONOMY
Directory of Open Access Journals (Sweden)
ANDREEA-LAVINIA CAZACU (NEAMTU
2016-10-01
Full Text Available Transfer prices are a delicate subject and of major importance in jurisdictions to which they belong, as they are often used as a means of exploiting tax legislation. In proceedings of tax inspection and financial control carried out by the tax authorities, a special place is occupied by the transactions between affiliated entities with Romanian companies. The purpose of the tax inspection is: combating tax evasion and tracking these transactions to be carried out at market prices. The article aims to present how transfer prices affect the value of an enterprise, but also the methodological aspects relating to tax inspection and the necessary documents in order to deciphering the mode of transfer pricing in Romania.
Ortega-Llebaria, Marta; Colantoni, Laura
2014-01-01
Although there is consistent evidence that higher levels of processing, such as learning the form-meaning associations specific to the second language (L2), are a source of difficulty in acquiring L2 speech, no study has addressed how these levels interact in shaping L2 perception and production of intonation. We examine the hypothesis of whether…
Heat transfer direction dependence of heat transfer coefficients in annuli
Prinsloo, Francois P. A.; Dirker, Jaco; Meyer, Josua P.
2018-04-01
In this experimental study the heat transfer phenomena in concentric annuli in tube-in-tube heat exchangers at different annular Reynolds numbers, annular diameter ratios, and inlet fluid temperatures using water were considered. Turbulent flow with Reynolds numbers ranging from 15,000 to 45,000, based on the average bulk fluid temperature was tested at annular diameter ratios of 0.327, 0.386, 0.409 and 0.483 with hydraulic diameters of 17.00, 22.98, 20.20 and 26.18 mm respectively. Both heated and cooled annuli were investigated by conducting tests at a range of inlet temperatures between 10 °C to 30 °C for heating cases, and 30 °C to 50 °C for cooling cases. Of special interest was the direct measurement of local wall temperatures on the heat transfer surface, which is often difficult to obtain and evasive in data-sets. Continuous verification and re-evaluation of temperatures measurements were performed via in-situ calibration. It is shown that inlet fluid temperature and the heat transfer direction play significant roles on the magnitude of the heat transfer coefficient. A new adjusted Colburn j-factor definition is presented to describe the heating and cooling cases and is used to correlate the 894 test cases considered in this study.
"Nanotechnology Enabled Advanced Industrial Heat Transfer Fluids"
Energy Technology Data Exchange (ETDEWEB)
Dr. Ganesh Skandan; Dr. Amit Singhal; Mr. Kenneth Eberts; Mr. Damian Sobrevilla; Prof. Jerry Shan; Stephen Tse; Toby Rossmann
2008-06-12
ABSTRACT Nanotechnology Enabled Advanced industrial Heat Transfer Fluids” Improving the efficiency of Industrial Heat Exchangers offers a great opportunity to improve overall process efficiencies in diverse industries such as pharmaceutical, materials manufacturing and food processing. The higher efficiencies can come in part from improved heat transfer during both cooling and heating of the material being processed. Additionally, there is great interest in enhancing the performance and reducing the weight of heat exchangers used in automotives in order to increase fuel efficiency. The goal of the Phase I program was to develop nanoparticle containing heat transfer fluids (e.g., antifreeze, water, silicone and hydrocarbon-based oils) that are used in transportation and in the chemical industry for heating, cooling and recovering waste heat. Much work has been done to date at investigating the potential use of nanoparticle-enhanced thermal fluids to improve heat transfer in heat exchangers. In most cases the effect in a commercial heat transfer fluid has been marginal at best. In the Phase I work, we demonstrated that the thermal conductivity, and hence heat transfer, of a fluid containing nanoparticles can be dramatically increased when subjected to an external influence. The increase in thermal conductivity was significantly larger than what is predicted by commonly used thermal models for two-phase materials. Additionally, the surface of the nanoparticles was engineered so as to have a minimal influence on the viscosity of the fluid. As a result, a nanoparticle-laden fluid was successfully developed that can lead to enhanced heat transfer in both industrial and automotive heat exchangers
A literature survey on numerical heat transfer
Shih, T. M.
1982-12-01
Technical papers in the area of numerical heat transfer published from 1977 through 1981 are reviewed. The journals surveyed include: (1) ASME Journal of Heat Transfer, (2) International Journal of Heat and Mass Transfer, (3) AIAA Journal, (4) Numerical Heat Transfer, (5) Computers and Fluids, (6) International Journal for Numerical Methods in Engineering, (7) SIAM Journal of Numerical Analysis, and (8) Journal of Computational Physics. This survey excludes experimental work in heat transfer and numerical schemes that are not applied to equations governing heat transfer phenomena. The research work is categorized into the following areas: (A) conduction, (B) boundary-layer flows, (C) momentum and heat transfer in cavities, (D) turbulent flows, (E) convection around cylinders and spheres or within annuli, (F) numerical convective instability, (G) radiation, (H) combustion, (I) plumes, jets, and wakes, (J) heat transfer in porous media, (K) boiling, condensation, and two-phase flows, (L) developing and fully developed channel flows, (M) combined heat and mass transfer, (N) applications, (O) comparison and properties of numerical schemes, and (P) body-fitted coordinates and nonuniform grids.
Kargel, J. S.; Furfaro, R.
2013-12-01
Thermal gradients within conductive layers of icy satellite and asteroids depend partly on heat flow, which is related to the secular decay of radioactive isotopes, to heat released by chemical phase changes, by conversion of gravitational potential energy to heat during differentiation, tidal energy dissipation, and to release of heat stored from prior periods. Thermal gradients are also dependent on the thermal conductivity of materials, which in turn depends on their composition, crystallinity, porosity, crystal fabric anisotropy, and details of their mixture with other materials. Small impurities can produce lattice defects and changes in polymerization, and thereby have a huge influence on thermal conductivity, as can cage-inclusion (clathrate) compounds. Heat flow and thermal gradients can be affected by fluid phase advection of mass and heat (in oceans or sublimating upper crusts), by refraction related to heterogeneities of thermal conductivity due to lateral variations and composition or porosity. Thermal profiles depend also on the surface temperature controlled by albedo and climate, surface relief, and latitude, orbital obliquity and surface insolation, solid state greenhouses, and endogenic heating of the surface. The thermal state of icy moon interiors and thermal gradients can be limited at depth by fluid phase advection of heat (e.g., percolating meteoric methane or gas emission), by the latent heat of phase transitions (melting, solid-state transitions, and sublimation), by solid-state convective or diapiric heat transfer, and by foundering. Rapid burial of thick volatile deposits can also affect thermal gradients. For geologically inactive or simple icy objects, most of these controls on heat flow and thermal gradients are irrelevant, but for many other icy objects they can be important, in some cases causing large lateral and depth variations in thermal gradients, large variations in heat flow, and dynamically evolving thermal states. Many of
Experimental study of thermal conductivity of pyrolysised materials by means of a flat layer
Vaniushkin, V. D.; Popov, S. K.; Sidenkov, D. V.
2017-11-01
Recycling of tires is currently a very important task. One of the areas of recycling tires is their low-temperature pyrolysis to produce marketable products - liquid fraction and a solid coke residue. For the development of the pyrolysis installation it is important to know the thermal conductivity of the coke residue at different temperatures of pyrolysis of initial material. As a property of matter, thermal conductivity depends in general on temperature and pressure. For materials with some structure, such as porous materials, the thermal conductivity depends on the characteristics of the structure. The thermal conductivity of the porous coke residue at pyrolysis temperatures of 300 0C, 400 0C, 500 0C and atmospheric pressure was studied experimentally at the laboratory unit of the department of “Theoretical basis of heat engineering” using the method of the flat layer in the temperature range 5…100 0C. Experimentally proved temperature dependencies of the coefficient of thermal conductivity of the coke residue are built to improve the accuracy of calculations of constructive and regime parameters of the pyrolysis installation.
CASKETSS-HEAT: a finite difference computer program for nonlinear heat conduction problems
International Nuclear Information System (INIS)
Ikushima, Takeshi
1988-12-01
A heat conduction program CASKETSS-HEAT has been developed. CASKETSS-HEAT is a finite difference computer program used for the solution of multi-dimensional nonlinear heat conduction problems. Main features of CASKETSS-HEAT are as follows. (1) One, two and three-dimensional geometries for heat conduction calculation are available. (2) Convection and radiation heat transfer of boundry can be specified. (3) Phase change and chemical change can be treated. (4) Finned surface heat transfer can be treated easily. (5) Data memory allocation in the program is variable according to problem size. (6) The program is a compatible heat transfer analysis program to the stress analysis program SAP4 and SAP5. (7) Pre- and post-processing for input data generation and graphic representation of calculation results are available. In the paper, brief illustration of calculation method, input data and sample calculation are presented. (author)
Directory of Open Access Journals (Sweden)
Davood Domairry Ganji
2011-01-01
Full Text Available In this paper, homotopy perturbation method has been used to evaluate the temperature distribution of annular fin with temperature-dependent thermal conductivity and to determine the temperature distribution within the fin. This method is useful and practical for solving the nonlinear heat transfer equation, which is associated with variable thermal conductivity condition. The homotopy perturbation method provides an approximate analytical solution in the form of an infinite power series. The annular fin heat transfer rate with temperature-dependent thermal conductivity has been obtained as a function of thermo-geometric fin parameter and the thermal conductivity parameter describing the variation of the thermal conductivity.
40 CFR 52.787 - Gasoline transfer vapor control.
2010-07-01
... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Gasoline transfer vapor control. 52.787... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Indiana § 52.787 Gasoline transfer vapor control. (a) Gasoline means any petroleum distillate having a Reid vapor pressure of 4 pounds or greater...
Heat transfer and thermal stress analysis in fluid-structure coupled field
International Nuclear Information System (INIS)
Li, Ming-Jian; Pan, Jun-Hua; Ni, Ming-Jiu; Zhang, Nian-Mei
2015-01-01
In this work, three-dimensional simulation on conjugate heat transfer in a fluid-structure coupled field was carried out. The structure considered is from the dual-coolant lithium-lead (DCLL) blanket, which is the key technology of International Thermo-nuclear Experimental Reactor (ITER). The model was developed based on finite element-finite volume method and was employed to investigate mechanical behaviours of Flow Channel Insert (FCI) and heat transfer in the blanket under nuclear reaction. Temperature distribution, thermal deformation and thermal stresses were calculated in this work, and the effects of thermal conductivity, convection heat transfer coefficient and flow velocity were analyzed. Results show that temperature gradients and thermal stresses of FCI decrease when FCI has better heat conductivity. Higher convection heat transfer coefficient will result in lower temperature, thermal deformations and stresses in FCI. Analysis in this work could be a theoretical basis of blanket optimization. - Highlights: • We use FVM and FEM to investigate FCI structural safety considering heat transfer and FSI effects. • Higher convective heat transfer coefficient is beneficial for the FCI structural safety without much affect to bulk flow temperature. • Smaller FCI thermal conductivity can better prevent heat leakage into helium, yet will increase FCI temperature gradient and thermal stress. • Three-dimensional simulation on conjugate heat transfer in a fluid-structure coupled field was carried out
Fuel element transfer cask modelling using MCNP technique
International Nuclear Information System (INIS)
Rosli Darmawan
2009-01-01
Full text: After operating for more than 25 years, some of the Reaktor TRIGA PUSPATI (RTP) fuel elements would have been depleted. A few addition and fuel reconfiguration exercises have to be conducted in order to maintain RTP capacity. Presently, RTP spent fuels are stored at the storage area inside RTP tank. The need to transfer the fuel element outside of RTP tank may be prevalence in the near future. The preparation shall be started from now. A fuel element transfer cask has been designed according to the recommendation by the fuel manufacturer and experience of other countries. A modelling using MCNP code has been conducted to analyse the design. The result shows that the design of transfer cask fuel element is safe for handling outside the RTP tank according to recent regulatory requirement. (author)
Fuel Element Transfer Cask Modelling Using MCNP Technique
International Nuclear Information System (INIS)
Darmawan, Rosli; Topah, Budiman Naim
2010-01-01
After operating for more than 25 years, some of the Reaktor TRIGA Puspati (RTP) fuel elements would have been depleted. A few addition and fuel reconfiguration exercises have to be conducted in order to maintain RTP capacity. Presently, RTP spent fuels are stored at the storage area inside RTP tank. The need to transfer the fuel element outside of RTP tank may be prevalence in the near future. The preparation shall be started from now. A fuel element transfer cask has been designed according to the recommendation by the fuel manufacturer and experience of other countries. A modelling using MCNP code has been conducted to analyse the design. The result shows that the design of transfer cask fuel element is safe for handling outside the RTP tank according to recent regulatory requirement.
Debugging data transfers in CMS
International Nuclear Information System (INIS)
Bagliesi, G; Belforte, S; Bloom, K; Bockelman, B; Bonacorsi, D; Fisk, I; Flix, J; Hernandez, J; D'Hondt, J; Maes, J; Kadastik, M; Klem, J; Kodolova, O; Kuo, C-M; Letts, J; Magini, N; Metson, S; Piedra, J; Pukhaeva, N; Tuura, L
2010-01-01
The CMS experiment at CERN is preparing for LHC data taking in several computing preparation activities. In early 2007 a traffic load generator infrastructure for distributed data transfer tests was designed and deployed to equip the WLCG tiers which support the CMS virtual organization with a means for debugging, load-testing and commissioning data transfer routes among CMS computing centres. The LoadTest is based upon PhEDEx as a reliable, scalable data set replication system. The Debugging Data Transfers (DDT) task force was created to coordinate the debugging of the data transfer links. The task force aimed to commission most crucial transfer routes among CMS tiers by designing and enforcing a clear procedure to debug problematic links. Such procedure aimed to move a link from a debugging phase in a separate and independent environment to a production environment when a set of agreed conditions are achieved for that link. The goal was to deliver one by one working transfer routes to the CMS data operations team. The preparation, activities and experience of the DDT task force within the CMS experiment are discussed. Common technical problems and challenges encountered during the lifetime of the taskforce in debugging data transfer links in CMS are explained and summarized.
Heat Transfer Performance of Functionalized Graphene Nanoplatelet Aqueous Nanofluids
Directory of Open Access Journals (Sweden)
Roberto Agromayor
2016-06-01
Full Text Available The low thermal conductivity of fluids used in many industrial applications is one of the primary limitations in the development of more efficient heat transfer systems. A promising solution to this problem is the suspension of nanoparticles with high thermal conductivities in a base fluid. These suspensions, known as nanofluids, have great potential for enhancing heat transfer. The heat transfer enhancement of sulfonic acid-functionalized graphene nanoplatelet water-based nanofluids is addressed in this work. A new experimental setup was designed for this purpose. Convection coefficients, pressure drops, and thermophysical properties of various nanofluids at different concentrations were measured for several operational conditions and the results are compared with those of pure water. Enhancements in thermal conductivity and in convection heat transfer coefficient reach 12% (1 wt % and 32% (0.5 wt %, respectively. New correlations capable of predicting the Nusselt number and the friction factor of this kind of nanofluid as a function of other dimensionless quantities are developed. In addition, thermal performance factors are obtained from the experimental convection coefficient and pressure drop data in order to assess the convenience of replacing the base fluid with designed nanofluids.
Thermal radiation heat transfer
Howell, John R; Mengüç, M Pinar
2011-01-01
Providing a comprehensive overview of the radiative behavior and properties of materials, the fifth edition of this classic textbook describes the physics of radiative heat transfer, development of relevant analysis methods, and associated mathematical and numerical techniques. Retaining the salient features and fundamental coverage that have made it popular, Thermal Radiation Heat Transfer, Fifth Edition has been carefully streamlined to omit superfluous material, yet enhanced to update information with extensive references. Includes four new chapters on Inverse Methods, Electromagnetic Theory, Scattering and Absorption by Particles, and Near-Field Radiative Transfer Keeping pace with significant developments, this book begins by addressing the radiative properties of blackbody and opaque materials, and how they are predicted using electromagnetic theory and obtained through measurements. It discusses radiative exchange in enclosures without any radiating medium between the surfaces-and where heat conduction...
Vélez, Maria Isabel; Blessent, Daniela; Córdoba, Sebastián; López-Sánchez, Jacqueline; Raymond, Jasmin; Parra-Palacio, Eduardo
2018-01-01
This work presents an estimation of the geothermal potential of the Nevado del Ruiz (NDR) volcano, bridging the knowledge gap to develop geothermal energy in Colombia and improve resource estimates in South America. Field work, laboratory measurements, geological interpretations, 2D numerical modeling, and uncertainty analysis were conducted to the northwest of the NDR to assess temperature at depth and define thermal energy content. About 60 rock samples were collected at outcrops to measure thermal conductivity with a needle probe. A 2D numerical model, built from an inferred geological cross-section, was developed with the software OpenGeoSys to simulate the underground temperature distribution and then estimate the geothermal potential of a 1 km2 area with sufficient temperature, assuming a recovery factor equal to 2.4% and a 30 years exploitation time. Coupled groundwater flow and heat transfer were simulated in steady-state considering two different thermal conductivity scenarios. Results show that the average estimated potential is 1.5 × 10-2 MWt m-1 of the reservoir thickness, considering temperatures greater than 150 °C located at a depth of approximately 2 km, in a selected area situated outside of the Los Nevados National Natural Park (NNP), to avoid any direct intervention on this protected area. According to a Monte Carlo analysis considering pessimist and optimist scenarios of thermal conductivity, the estimated geothermal power was 1.54 × 10-2 MW m-1 (σ = 2.91 × 10-3 MW m-1) and 1.88 × 10-2 MW/m (σ = 2.91 × 10-3 MW m-1) for the two modeling scenario considered.
The role of benefit transfer in ecosystem service valuation
Richardson, Leslie A.; Loomis, John; Kroeger, Timm; Casey, Frank
2015-01-01
The demand for timely monetary estimates of the economic value of nonmarket ecosystem goods and services has steadily increased over the last few decades. This article describes the use of benefit transfer to generate monetary value estimates of ecosystem services specifically. The article provides guidance for conducting such benefit transfers and summarizes advancements in benefit transfer methods, databases and analysis tools designed to facilitate its application.
Directory of Open Access Journals (Sweden)
Saiedeh Bahrampouri
2013-08-01
Full Text Available Introduction: Stroke is main cause of death and disability in worldwide and emergency care can decrease complications. Emergency Medical System transferred half of stroke patients to hospital, so improve accuracy of diagnosis may accelerated treatment. This study aimed to determine diagnosis status and, transfer time of stroke patients transferred by prehospital Emergency Medical System to hospital in Arak City. Methods: This study was descriptive -analytic study and all 43 patient’s records with a diagnosis of stroke that transferred by Emergency Medical System to hospital in Arak City was selected. The study Checklist was contained information about age, sex, type of accident prehospital, response time, scene time, transfer time and total time from inpatients records and Emergency Center statistics .Regarding data analysis,SPSS19 software and descriptive statistical tests were used. Results: Mean (SD of age all patients were 73/7±3/8 and 51/2% were women. Ambulance paramedics' stroke diagnosis was correct in 15 (34/9%,20(46/5%of false and 8(18/6% not diagnosed for stroke patients who initially presented to them. The most common non stroke conditions were confusion. Mean response time and scene time, transfer time and total time were 6/9,16/9,9/1 and 35/3 minutes, respectively. In patients with correct diagnose stroke, mean response, scene, transfer and total time were 7,17/1,3/9 and 35/7 minutes. The people with the wrong diagnosis or no diagnosis of stroke by emergency medical personnel were taken to hospital, Mean response, scene, transfer and total time were 6/9, 16/8,9/7 and 33/5 minutes. Conclusions: The results of this study showed that, the correct diagnosis by EMS personnel could be resulted faster transferring patient to definite treatment center.It is recommended to develop prehospital diagnosis tool of stroke, which is contextually adapted and appropriate to facilitate diagnose of strokes and improve the quality of care.
A sewing-enabled stitch-and-transfer method for robust, ultra-stretchable, conductive interconnects
International Nuclear Information System (INIS)
Rahimi, Rahim; Ochoa, Manuel; Yu, Wuyang; Ziaie, Babak
2014-01-01
Fabricating highly stretchable and robust electrical interconnects at low-cost remains an unmet challenge in stretchable electronics. Previously reported stretchable interconnects require complicated fabrication processes with resulting devices exhibiting limited stretchability, poor reliability, and large gauge factors. Here, we demonstrate a novel sew-and-transfer method for rapid fabrication of low-cost, highly stretchable interconnects. Using a commercial sewing machine and double-thread stitch with one of the threads being water soluble polyvinyl alcohol (PVA), thin zigzag-pattern metallic wires are sewn into a polymeric film and are subsequently transferred onto a stretchable elastomeric substrate by dissolving PVA in warm water. The resulting structures exhibit extreme stretchability (exceeding 500% strain for a zigzag angle of 18 °) and robustness (capable of withstanding repeated stretch-and-release cycles of 15000 at 110% strain, 50000 at 55% strain, and > 120000 at 30% strain without any noticeable change in resistance even at maximum strain levels). Using this technique, we demonstrate a stretchable inductive strain sensor for monitoring balloon expansion in a Foley urinary catheter capable of detecting the balloon diameter change from 9 mm to 38 mm with an average sensitivity of 4 nH/mm. (paper)
The electrical conductivity of sodium polysulfide melts
Energy Technology Data Exchange (ETDEWEB)
Wang, Meihui [Univ. of California, Berkeley, CA (United States)
1992-06-01
The sodium polysulfide melt has been described by a macroscopic model. This model considers the melt to be composed of sodium cations, monosulfide anions, and neutral sulfur solvent. The transport equations of concentrated-solution theory are used to derived the governing equations for this binaryelectrolyte melt model. These equations relate measurable transport properties to fundamental transport parameters. The focus of this research is to measure the electrical conductivity of sodium polysulfide melts and calculate one of fundamental transport parameters from the experimental data. The conductance cells used in the conductivity measurements are axisymmetric cylindrical cells with a microelectrode. The electrode effects, including double-layer capacity, charge transfer resistance, and concentration overpotential, were minimized by the use of the alternating current at an adequately high frequency. The high cell constants of the conductance cells not only enhanced the experimental accuracy but also made the electrode effects negligible. The electrical conductivities of sodium polysulfide Na_{2}S_{4} and Na_{2}S_{5} were measured as a function of temperature (range: 300 to 360°C). Variations between experiments were only up to 2%. The values of the Arrhenius activation energy derived from the experimental data are about 33 kJ/mol. The fundamental transport parameter which quantifies the interaction within sodium cations and monosulfide anions are of interest and expected to be positive. Values of it were calculated from the experimental conductivity data and most of them are positive. Some negative values were obtained probably due to the experimental errors of transference number, diffusion coefficient, density or conductivity data.
Geometric model for softwood transverse thermal conductivity. Part I
Hong-mei Gu; Audrey Zink-Sharp
2005-01-01
Thermal conductivity is a very important parameter in determining heat transfer rate and is required for developing of drying models and in industrial operations such as adhesive cure rate. Geometric models for predicting softwood thermal conductivity in the radial and tangential directions were generated in this study based on obervation and measurements of wood...
Experimental determination of the key heat transfer mechanisms in pharmaceutical freeze-drying.
Ganguly, Arnab; Nail, Steven L; Alexeenko, Alina
2013-05-01
The study is aimed at quantifying the relative contribution of key heat transfer modes in lyophilization. Measurements of vial heat transfer rates in a laboratory-scale freeze-dryer were performed using pure water, which was partially sublimed under various conditions. The separation distance between the shelf and the vial was systematically varied, and sublimation rates were determined gravimetrically. The heat transfer rates were observed to be independent of separation distance between the vial and the shelf and linearly dependent on pressure in the free molecular flow limit, realized at low pressures (120 mTorr), heat transfer rates were independent of pressure and inversely proportional to separation distance. Previous heat transfer studies in conventional freeze-drying cycles have attributed a dominant portion of the total heat transfer to radiation, the rest to conduction, whereas convection has been found to be insignificant. Although the measurements reported here confirm the significance of the radiative and gas conduction components, the convective component has been found to be comparable to the gas conduction contribution at pressures greater than 100 mTorr. The current investigation supports the conclusion that the convective component of the heat transfer cannot be ignored in typical laboratory-scale freeze-drying conditions. Copyright © 2013 Wiley Periodicals, Inc.
CVD transfer-free graphene for sensing applications.
Schiattarella, Chiara; Vollebregt, Sten; Polichetti, Tiziana; Alfano, Brigida; Massera, Ettore; Miglietta, Maria Lucia; Di Francia, Girolamo; Sarro, Pasqualina Maria
2017-01-01
The sp 2 carbon-based allotropes have been extensively exploited for the realization of gas sensors in the recent years because of their high conductivity and large specific surface area. A study on graphene that was synthetized by means of a novel transfer-free fabrication approach and is employed as sensing material is herein presented. Multilayer graphene was deposited by chemical vapour deposition (CVD) mediated by CMOS-compatible Mo. The utilized technique takes advantage of the absence of damage or contamination of the synthesized graphene, because there is no need for the transfer onto a substrate. Moreover, a proper pre-patterning of the Mo catalyst allows one to obtain graphene films with different shapes and dimensions. The sensing properties of the material have been investigated by exposing the devices to NO 2 , NH 3 and CO, which have been selected because they are well-known hazardous substances. The concentration ranges have been chosen according to the conventional monitoring of these gases. The measurements have been carried out in humid N 2 environment, setting the flow rate at 500 sccm, the temperature at 25 °C and the relative humidity (RH) at 50%. An increase of the conductance response has been recorded upon exposure towards NO 2 , whereas a decrease of the signal has been detected towards NH 3 . The material appears totally insensitive towards CO. Finally, the sensing selectivity has been proven by evaluating and comparing the degree of adsorption and the interaction energies for NO 2 and NH 3 on graphene. The direct-growth approach for the synthesis of graphene opens a promising path towards diverse applicative scenarios, including the straightforward integration in electronic devices.
CVD transfer-free graphene for sensing applications
Directory of Open Access Journals (Sweden)
Chiara Schiattarella
2017-05-01
Full Text Available The sp2 carbon-based allotropes have been extensively exploited for the realization of gas sensors in the recent years because of their high conductivity and large specific surface area. A study on graphene that was synthetized by means of a novel transfer-free fabrication approach and is employed as sensing material is herein presented. Multilayer graphene was deposited by chemical vapour deposition (CVD mediated by CMOS-compatible Mo. The utilized technique takes advantage of the absence of damage or contamination of the synthesized graphene, because there is no need for the transfer onto a substrate. Moreover, a proper pre-patterning of the Mo catalyst allows one to obtain graphene films with different shapes and dimensions. The sensing properties of the material have been investigated by exposing the devices to NO2, NH3 and CO, which have been selected because they are well-known hazardous substances. The concentration ranges have been chosen according to the conventional monitoring of these gases. The measurements have been carried out in humid N2 environment, setting the flow rate at 500 sccm, the temperature at 25 °C and the relative humidity (RH at 50%. An increase of the conductance response has been recorded upon exposure towards NO2, whereas a decrease of the signal has been detected towards NH3. The material appears totally insensitive towards CO. Finally, the sensing selectivity has been proven by evaluating and comparing the degree of adsorption and the interaction energies for NO2 and NH3 on graphene. The direct-growth approach for the synthesis of graphene opens a promising path towards diverse applicative scenarios, including the straightforward integration in electronic devices.
40 CFR 52.255 - Gasoline transfer vapor control.
2010-07-01
... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Gasoline transfer vapor control. 52.255... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS California § 52.255 Gasoline transfer vapor control. (a) “Gasoline” means any petroleum distillate having a Reid vapor pressure of 4 pounds or greater...
A way to visualise heat transfer in 3D unsteady flows
Speetjens, M.F.M.
2009-01-01
Heat transfer in fluid flows traditionally is examined in terms of temperature field and heat-transfer coefficients. However, heat transfer may alternatively be considered as the transport of thermal energy by the total convective-conductive heat flux in a way analogous to the transport of fluid by
Do Materialism, Intrinsic Aspirations, and Meaning in Life Predict Students' Meanings of Education?
Henderson-King, Donna; Mitchell, Amanda M.
2011-01-01
Though there is a deep literature on factors that predict college attendance and on the effects of college attendance on students' development, there has been little research on what education actually means to students themselves. This study was conducted to examine whether materialism, intrinsic aspirations, and the search for meaning in life…
Understanding Transfer of Training.
Brown, Mark G.
1983-01-01
Stresses the difficulty of "maintenance" of newly learned behaviors by reinforcement and feedback on the job and proposes an alternative means of promoting transfer of training--establishing rule-governed behavior. Some ways of establishing rules in training are listed and discussed, including use of behavior-modeling and other…
Mechanisms of proton conductance in polymer electrolyte membranes
DEFF Research Database (Denmark)
Eikerling, M.; Kornyshev, A. A.; Kuznetsov, A. M.
2001-01-01
We provide a phenomenological description of proton conductance in polymer electrolyte membranes, based on contemporary views of proton transfer processes in condensed media and a model for heterogeneous polymer electrolyte membrane structure. The description combines the proton transfer events...... in a single pore with the total pore-network performance and, thereby, relates structural and kinetic characteristics of the membrane. The theory addresses specific experimentally studied issues such as the effect of the density of proton localization sites (equivalent weight) of the membrane material...
Vertex corrections to the mean-field electrical conductivity in disordered electron systems
Czech Academy of Sciences Publication Activity Database
Pokorný, Vladislav; Janiš, Václav
2013-01-01
Roč. 25, č. 17 (2013), "175502-1"-"175502-10" ISSN 0953-8984 Institutional support: RVO:68378271 Keywords : disordered electron systems * electrical conductivity * vertex corrections Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.223, year: 2013
International Nuclear Information System (INIS)
Zarkova, L.P.
1976-01-01
A general-purpose experimental setup is made to measure thermal conductivity coefficients lambda of inert gases and metal vapours in the range 1000-2500 K by means of the differential method. The setup can also be used to measure lambda of plasmas and reacting gases as well as the dependence of lambda on magnetic fields. A simple and reliable procedure to determine the filament temperature using values of the measured current and wire diameter is suggested. The influence of different factors such as the temperature jump at the boundary gas-filament, convective heat transfer, thermal expansion, excentricity and cold ends of filament on the measured values of the thermal conductivity is considered in details. A formula is deduced to calculate the temperature jump correction taking into account the dependence of the mean free path on the temperature. Expressions are also given to calculate the corrections for thermal expansion, eccentricity and cold ends of the filament. Thermal conductivity coefficients of inert gases are measured to check the method: Ne in the range 1100-2200 K, Ar in the range 1000-2200 K, Kr in the range 1300-2300 K and Xe in the range 1100-2200 K. The data for Ne and Xe in the range 1500 to 2200 K and for Kr at T=2000-2300 K are original. The thermal conductivity coefficient of monoatomic mercury vapour is measured in the range 1000-2300 K with 3% error. The thermal conductivity coefficient of monoatomic cesium vapour is also measured in the range 1000-1600 K with 4% error. (I.P.)
Natural convection heat transfer from a vertical circular tube sheet
International Nuclear Information System (INIS)
Dharne, S.P.; Gaitonde, U.N.
1996-01-01
Experiments were conducted to determine natural convection heat transfer coefficients (a) on a plain vertical circular plate, and (b) on a similar plate with a square array of non-conducting tubes fixed in it. The experiments were carried out using air as the heat transfer medium. The diameter of the brass plates used was 350 mm. The diameter of the bakelite tubes used was 19.2 mm. The range of Rayleigh numbers was from 1.06x10 8 to 1.66x10 8 . The results show that the heat transfer coefficients in case (a) are very close to those obtained using standard correlations for vertical flat plates, whereas for case (b) the heat transfer coefficients are at least 50 percent higher than those predicted by the Churchill-Chu correlation. It is hence concluded that the disturbance to boundary layer caused by the presence of tubes enhances the heat transfer coefficient significantly. (author). 4 refs., 3 figs
The security energy encryption in wireless power transfer
Sadzali, M. N.; Ali, A.; Azizan, M. M.; Albreem, M. A. M.
2017-09-01
This paper presents a concept of security in wireless power transfer (WPT) by applying chaos theory. Chaos theory is applied as a security system in order to safeguard the transfer of energy from a transmitter to the intended receiver. The energy encryption of the wireless power transfer utilizes chaos theory to generate the possibility of a logistic map for the chaotic security key. The simulation for energy encryption wireless power transfer system was conducted by using MATLAB and Simulink. By employing chaos theory, the chaotic key ensures the transmission of energy from transmitter to its intended receiver.
Toe Tissue Transfer for Reconstruction of Damaged Digits due to Electrical Burns
Directory of Open Access Journals (Sweden)
Hyung-Do Kim
2012-03-01
Full Text Available Background Electrical burns are one of the most devastating types of injuries, and can becharacterized by the conduction of electric current through the deeper soft tissue such asvessels, nerves, muscles, and bones. For that reason, the extent of an electric burn is veryfrequently underestimated on initial impression.Methods From July 1999 to June 2006, we performed 15 cases of toe tissue transfer for thereconstruction of finger defects caused by electrical burns. We performed preoperative rangeof motion exercise, early excision, and coverage of the digital defect with toe tissue transfer.Results We obtained satisfactory results in both functional and aesthetic aspects in all 15cases without specific complications. Static two-point discrimination results in the transferredtoe cases ranged from 8 to 11 mm, with an average of 9.5 mm. The mean range of motionof the transferred toe was 20° to 36° in the distal interphalangeal joint, 16° to 45° in theproximal interphalangeal joint, and 15° to 35° in the metacarpophalangeal joint. All of thepatients were relatively satisfied with the function and appearance of their new digits.Conclusions The strategic management of electrical injury to the hands can be both challengingand complex. Because the optimal surgical method is free tissue transfer, maintenance ofvascular integrity among various physiological changes works as a determining factor for thepostoperative outcome following the reconstruction.
Broderick, Ciaran; Matthews, Tom; Wilby, Robert L.; Bastola, Satish; Murphy, Conor
2016-10-01
Understanding hydrological model predictive capabilities under contrasting climate conditions enables more robust decision making. Using Differential Split Sample Testing (DSST), we analyze the performance of six hydrological models for 37 Irish catchments under climate conditions unlike those used for model training. Additionally, we consider four ensemble averaging techniques when examining interperiod transferability. DSST is conducted using 2/3 year noncontinuous blocks of (i) the wettest/driest years on record based on precipitation totals and (ii) years with a more/less pronounced seasonal precipitation regime. Model transferability between contrasting regimes was found to vary depending on the testing scenario, catchment, and evaluation criteria considered. As expected, the ensemble average outperformed most individual ensemble members. However, averaging techniques differed considerably in the number of times they surpassed the best individual model member. Bayesian Model Averaging (BMA) and the Granger-Ramanathan Averaging (GRA) method were found to outperform the simple arithmetic mean (SAM) and Akaike Information Criteria Averaging (AICA). Here GRA performed better than the best individual model in 51%-86% of cases (according to the Nash-Sutcliffe criterion). When assessing model predictive skill under climate change conditions we recommend (i) setting up DSST to select the best available analogues of expected annual mean and seasonal climate conditions; (ii) applying multiple performance criteria; (iii) testing transferability using a diverse set of catchments; and (iv) using a multimodel ensemble in conjunction with an appropriate averaging technique. Given the computational efficiency and performance of GRA relative to BMA, the former is recommended as the preferred ensemble averaging technique for climate assessment.
Review of PCMS and heat transfer enhancement methods applied ...
African Journals Online (AJOL)
Most available PCMs have low thermal conductivity making heat transfer enhancement necessary for power applications. The various methods of heat transfer enhancement in latent heat storage systems were also reviewed systematically. The review showed that three commercially - available PCMs are suitable in the ...
Turbulent Heat Transfer in Curved Pipe Flow
Kang, Changwoo; Yang, Kyung-Soo
2013-11-01
In the present investigation, turbulent heat transfer in fully-developed curved pipe flow with axially uniform wall heat flux has been numerically studied. The Reynolds numbers under consideration are Reτ = 210 (DNS) and 1,000 (LES) based on the mean friction velocity and the pipe radius, and the Prandtl number (Pr) is 0.71. For Reτ = 210 , the pipe curvature (κ) was fixed as 1/18.2, whereas three cases of κ (0.01, 0.05, 0.1) were computed in the case of Reτ = 1,000. The mean velocity, turbulent intensities and heat transfer rates obtained from the present calculations are in good agreement with the previous numerical and experimental results. To elucidate the secondary flow structures due to the pipe curvature, the mean quantities and rms fluctuations of the flow and temperature fields are presented on the pipe cross-sections, and compared with those of the straight pipe flow. To study turbulence structures and their influence on turbulent heat transfer, turbulence statistics including but not limited to skewness and flatness of velocity fluctuations, cross-correlation coefficients, an Octant analysis, and turbulence budgets are presented and discussed. Based on our results, we attempt to clarify the effects of Reynolds number and the pipe curvature on turbulent heat transfer. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0008457).
Watt, D.A.
1956-07-01
A current transfer system is described for transferring current between a rotating member and a co-axial stationary member. The particular area of application for the invention is in connection with homopolar generators where a low voltage and high current are generated. The current tramsfer system of the invention comprises a rotor member and a co-axial stator member wherein one of the members is shaped to provide a circumferential surface concave in section and the other member is shaped to have a peripheral portion in close proximity to the surface, whereby a liquid metal can be stably supported between the two members when they are moving relative to one another to establish an electrical conducting path between the members.
Heat transfer enhancement with nanofluids
Bianco, Vincenzo; Nardini, Sergio; Vafai, Kambiz
2015-01-01
Properties of NanofluidSamuel Paolucci and Gianluca PolitiExact Solutions and Their Implications in Anomalous Heat TransferWenhao Li, Chen Yang and Akira NakayamaMechanisms and Models of Thermal Conductivity in NanofluidsSeung-Hyun Lee and Seok Pil JangExperimental Methods for the Characterization of Thermophysical Properties of NanofluidsSergio Bobbo and Laura FedeleNanofluid Forced ConvectionGilles RoyExperimental Study of Convective Heat Transfer in NanofluidsEhsan B. Haghighi, Adi T. Utomo, Andrzej W. Pacek and Björn E. PalmPerformance of Heat Exchangers Using NanofluidsBengt Sundén and Za
Transfer of heat to fluidized-solids beds
Energy Technology Data Exchange (ETDEWEB)
1952-10-16
The improvement in the method described and claimed in patent application 14,363/47 (136,186) for supplying heat to a dense turbulent mass of solid fluidized by a gas flowing upwardly therethrough and subjected to a high temperature in a treating zone, by heat transfer through heat-transfer surfaces of heat-transfer elements in contact with the said turbulent mass of finely divided solid and heated by means of a fluid heating medium, including burning fuels comprising contacting the said heat-transfer surfaces with a fuel and a combustion supporting gas under such conditions that the combustion of the fuel is localized in the heat-transfer element near the point of entry of the fuel and combustion-supporting gas and a substantial temperature gradient is maintained along the path of said fuel combustion-supporting gas and combustion products through the said heat-transfer element.
Supercritical water gasification with decoupled pressure and heat transfer modules
Dibble, Robert W.; Ng, Kim Choon; Sarathy, Mani
2017-01-01
decouples the function of containing high pressure from the high temperature function. The present invention allows the heat transfer function to be conducted independently from the pressure transfer function such that the system equipment can be designed
International Nuclear Information System (INIS)
Edelmann, M.
1995-12-01
A new measurement method for measuring the mean fuel temperature as well as the fuel-to-coolant heat transfer coefficient of fast breeder reactor subassemblies (SA) is reported. The method is based on the individual heat balance of fuel SA's after fast reactor shut-downs and uses only the plants normal SA outlet temperature and neutron power signals. The method was used successfully at the french breeder prototype Super Phenix 1. The mean SA fuel temperature as well as the heat transfer coefficient of all SPX SA's have been determined at power levels between 15 and 90% of nominal power and increasing fuel burn-up from 3 to 83 EFPD (Equivalent of Full Power-Days). The measurements also provided fuel and whole SA time constants. The estimated accuracy of measured fuel parameters is in the order of 10%. Fuel temperatures and SA outlet temperature transients were also calculated with the SPX1 systems code DYN2 for exactly the same fuel and reactor operating parameters as in the experiments. Measured fuel temperatures were higher than calculated ones in all cases. The difference between measured and calculated core mean values increases from 50 K at low power to 180 K at 90% n.p. This is about the double of the experimental error margins. Measured SA heat transfer coefficients are by nearly 20% lower than corresponding heat transfer parameters used in the calculations. Discrepancies found between measured and calculated results also indicate that either the transient heat transfer in the gap between fuel and cladding (gap conductance) might not be exactly reproduced in the computer code or that the gap in the fresh fuel was larger than assumed in the calculations. (orig.) [de
The Organic Chemistry of Conducting Polymers
Energy Technology Data Exchange (ETDEWEB)
Tolbert, Laren Malcolm [Georgia Inst. of Technology, Atlanta, GA (United States)
2014-12-01
For the last several years, we have examined the fundamental principles of conduction in one-dimensional systems, i.e., molecular “wires”. It is, of course, widely recognized that such systems, as components of electronically conductive materials, function in a two- and three-dimensional milieu. Thus interchain hopping and grain-boundary resistivity are limiting conductivity factors in highly conductive materials, and overall conductivity is a function of through-chain and boundary hopping. We have given considerable attention to the basic principles underlying charge transport (the “rules of the game”) in two-dimensional systems by using model systems which allow direct observation of such processes, including the examination of tunneling and hopping as components of charge transfer. In related work, we have spent considerable effort on the chemistry of conjugated heteropolymers, most especially polythiophens, with the aim of using these most efficient of readily available electroactive polymers in photovoltaic devices.
A Network Model for the Effective Thermal Conductivity of Rigid Fibrous Refractory Insulations
Marschall, Jochen; Cooper, D. M. (Technical Monitor)
1995-01-01
A procedure is described for computing the effective thermal conductivity of a rigid fibrous refractory insulation. The insulation is modeled as a 3-dimensional Cartesian network of thermal conductance. The values and volume distributions of the conductance are assigned to reflect the physical properties of the insulation, its constituent fibers, and any permeating gas. The effective thermal conductivity is computed by considering the simultaneous energy transport by solid conduction, gas conduction and radiation through a cubic volume of model insulation; thus the coupling between heat transfer modes is retained (within the simplifications inherent to the model), rather than suppressed by treating these heat transfer modes as independent. The model takes into account insulation composition, density and fiber anisotropy, as well as the geometric and material properties of the constituent fibers. A relatively good agreement, between calculated and experimentally derived thermal conductivity values, is obtained for a variety of rigid fibrous insulations.
Maurice, L.; Rawlins, B. G.; Farr, G.; Bell, R.; Gooddy, D. C.
2017-11-01
The evasion of greenhouse gases (including CO2, CH4, and N2O) from streams and rivers to the atmosphere is an important process in global biogeochemical cycles, but our understanding of gas transfer in steep (>10%) streams, and under varying flows, is limited. We investigated gas transfer using combined tracer injections of SF6 and salt. We used a novel experimental design in which we compared four very steep (18.4-29.4%) and four moderately steep (3.7-7.6%) streams and conducted tests in each stream under low flow conditions and during a high-discharge event. Most dissolved gas evaded over short distances ( 100 and 200-400 m, respectively), so accurate estimates of evasion fluxes will require sampling of dissolved gases at these scales to account for local sources. We calculated CO2 gas transfer coefficients (KCO2) and found statistically significant differences between larger KCO2 values for steeper (mean 0.465 min-1) streams compared to those with shallower slopes (mean 0.109 min-1). Variations in flow had an even greater influence. KCO2 was substantially larger under high (mean 0.497 min-1) compared to low flow conditions (mean 0.077 min-1). We developed a statistical model to predict KCO2 using values of streambed slope × discharge which accounted for 94% of the variation. We show that two models using slope and velocity developed by Raymond et al. (2012) for streams and rivers with shallower slopes also provide reasonable estimates of our CO2 gas transfer velocities (kCO2; m d-1). We developed a robust field protocol which could be applied in future studies.
Energy Technology Data Exchange (ETDEWEB)
Bhattacharyya, A
1965-11-15
This report contains descriptions of various analogues utilised to study different steady-state and unsteady-state heat transfer problems. The analogues covered are as follows: 1 . Hydraulic: a) water flow b) air flow 2. Membrane 3. Geometric Electrical: a) Electrolytic-tank b) Conducting sheet 4. Network; a) Resistance b) R-C A comparison of the different analogues is presented in the form of a table.
International Nuclear Information System (INIS)
Bhattacharyya, A.
1965-11-01
This report contains descriptions of various analogues utilised to study different steady-state and unsteady-state heat transfer problems. The analogues covered are as follows: 1 . Hydraulic: a) water flow b) air flow 2. Membrane 3. Geometric Electrical: a) Electrolytic-tank b) Conducting sheet 4. Network; a) Resistance b) R-C A comparison of the different analogues is presented in the form of a table
Hongmei Gu; John F. Hunt
2007-01-01
The anisotropy of wood creates a complex problem for solving heat and mass transfer problems that require analyses be based on fundamental material properties of the wood structure. Most heat transfer models for softwood use average thermal properties across either the radial or tangential direction and do not differentiate the effects of cellular alignment or...
Bone Conduction: Anatomy, Physiology, and Communication
National Research Council Canada - National Science Library
Henry, Paula; Letowski, Tomasz R
2007-01-01
... conduction transmission, and the use of the bone conduction pathway for communication. Bone conduction for the transmission of communication is effective and feasible for Soldiers because it provides a means of providing radio communication in combination with hearing protection devices.
A new approach for soil-plant transfer calculations
International Nuclear Information System (INIS)
Dorp, F. van; Eleveld, R.; Frissel, M.J.
1979-01-01
Models to calculate radiation doses to man caused by normal or accidental release of radionuclides from nuclear industries often include the transfer of these nuclides from soil to plant. This soil-plant transfer is mostly described with a black box approach by using concentration factors. This approach has several disadvantages, the most important being the lack of physical meaning of a concentration factor. We propose to describe the soil-plant transfer of radionuclides as a function of plant and soil parameters all having a physical meaning. The separate parameters are open to experimental determination but a realistic estimation of the parameters is also possible, or the use of a combination of both. Depending on the purpose of the calculation, realistic or conservative values of the parameters can be used and the degree of conservatism can be indicated. (author)
Heat transfer in intermediate heat exchanger under low flow rate conditions
International Nuclear Information System (INIS)
Mochizuki, H.
2008-01-01
The present paper describes the heat transfer in intermediate heat exchangers (IHXs) of liquid metal cooled fast reactors when flow rate is low such as a natural circulation condition. Although empirical correlations of heat transfer coefficients for IHX were derived using test data at the fast reactor 'Monju' and 'Joyo' and also at the 50 MW steam generator facility, the heat transfer coefficient was very low compared to the well known correlation for liquid metals proposed by Seban-Shimazaki. The heat conduction in IHX was discussed as a possible cause of the low Nusselt number. As a result, the heat conduction is not significant under the natural circulation condition, and the heat conduction term in the energy equation can be neglected in the one-dimensional plant dynamics calculation. (authors)
Comparison of correlations for heat transfer in sphere-pac beds
International Nuclear Information System (INIS)
Fundamenski, W.R.; Gierszewski, P.J.
1991-08-01
The design of a tritium breeding blanket for a fusion reactor requires the knowledge of heat transfer within the blanket. In this paper three models for effective bed heat transfer are compared against the experimental database in order to choose a reference correlation to be used in blanket design. Two parameters are used to describe heat transfer in a packed bed: effective thermal conductivity of the bed, and a heat transfer coefficient at the bed-solid interface
Cooperative heat transfer and ground coupled storage system
Metz, P.D.
A cooperative heat transfer and ground coupled storage system wherein collected solar heat energy is ground stored and permitted to radiate into the adjacent ground for storage therein over an extended period of time when such heat energy is seasonally maximally available. Thereafter, when said heat energy is seasonally minimally available and has propagated through the adjacent ground a substantial distance, the stored heat energy may be retrieved by a circumferentially arranged heat transfer means having a high rate of heat transfer.
Experience Transfer in Norwegian Oil and Gas Industry: Approaches and Organizational Mechanisms
Energy Technology Data Exchange (ETDEWEB)
Aase, Karina
1997-07-01
The core aim of the study is to explore the concept of experience transfer in oil and gas industry, and how an oil company approaches this concept. The thesis consists of five papers which are combined in a general description entitled 'Experience transfer in Norwegian oil and gas industry: approaches and organizational mechanisms'. The first paper describes how organizational members perceive experience transfer, and then specifies the many organizational and structural barriers that have to be overcome to achieve efficient experience transfer. The second paper elaborates and assesses the organizational means an oil company implements to address experience transfer. The third paper describes a process of improving and using requirement and procedure handbooks for experience transfer. The fourth paper explores in more detail how the use of information technology influences experience transfer. And the fifth paper compares organizational members' perceptions of experience transfer means in an oil company and an engineering company involved in offshore development projects. Some of the papers are based upon the same data material. Therefore there are reiterations in parts of the contents, especially in the methodological sections.
Experience Transfer in Norwegian Oil and Gas Industry: Approaches and Organizational Mechanisms
International Nuclear Information System (INIS)
Aase, Karina
1997-01-01
The core aim of the study is to explore the concept of experience transfer in oil and gas industry, and how an oil company approaches this concept. The thesis consists of five papers which are combined in a general description entitled 'Experience transfer in Norwegian oil and gas industry: approaches and organizational mechanisms'. The first paper describes how organizational members perceive experience transfer, and then specifies the many organizational and structural barriers that have to be overcome to achieve efficient experience transfer. The second paper elaborates and assesses the organizational means an oil company implements to address experience transfer. The third paper describes a process of improving and using requirement and procedure handbooks for experience transfer. The fourth paper explores in more detail how the use of information technology influences experience transfer. And the fifth paper compares organizational members' perceptions of experience transfer means in an oil company and an engineering company involved in offshore development projects. Some of the papers are based upon the same data material. Therefore there are reiterations in parts of the contents, especially in the methodological sections
Program for transfer research and impact studies
Rusnak, J. J.; Freeman, J. E.; Hartley, J. M.; Kottenstette, J. P.; Staskin, E. R.
1973-01-01
Research activities conducted under the Program for Transfer Research and Impact Studies (TRIS) during 1972 included: (1) preparation of 10,196 TSP requests for TRIS application analysis; (2) interviews with over 500 individuals concerning the technical, economic, and social impacts of NASA-generated technology; (3) preparation of 38 new technology transfer example files and 101 new transfer cases; and (4) maintenance of a technology transfer library containing more than 2,900 titles. Six different modes of technology utilization are used to illustrate the pervasiveness of the transfer and diffusion of aerospace innovations. These modes also provide a basis for distinguishing the unique characteristics of the NASA Technology Utilization Program. An examination is reported of the ways in which NASA-generated technology is contributing to beneficial social change in five major areas of human concern: health, environment, safety, transportation, and communication.
Heat Transfer in Directional Water Transport Fabrics
Directory of Open Access Journals (Sweden)
Chao Zeng
2016-10-01
Full Text Available Directional water transport fabrics can proactively transfer moisture from the body. They show great potential in making sportswear and summer clothing. While moisture transfer has been previously reported, heat transfer in directional water transport fabrics has been little reported in research literature. In this study, a directional water transport fabric was prepared using an electrospraying technique and its heat transfer properties under dry and wet states were evaluated, and compared with untreated control fabric and the one pre-treated with NaOH. All the fabric samples showed similar heat transfer features in the dry state, and the equilibrium temperature in the dry state was higher than for the wet state. Wetting considerably enhanced the thermal conductivity of the fabrics. Our studies indicate that directional water transport treatment assists in moving water toward one side of the fabric, but has little effect on thermal transfer performance. This study may be useful for development of “smart” textiles for various applications.
Energy Technology Data Exchange (ETDEWEB)
Day-Lewis, Frederick; Singha, Kamini; Haggerty, Roy; Johnson, Timothy; Binley, Andrew; Lane, John
2014-03-10
. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Our study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3-part research plan involving (1) development of computer codes and techniques to estimate mass-transfer parameters from time-lapse electrical data; (2) bench-scale experiments on synthetic materials and materials from cores from the Hanford 300 Area; and (3) field demonstration experiments at the DOE’s Hanford 300 Area.
The promises and prospects of worldwide wireless power transfer
International Nuclear Information System (INIS)
Van Voorhies, K.L.; Smith, J.E.
1991-01-01
The promise of worldwide wireless power transfer began with the pioneering work of Nikola Tesla about 100 years ago. His principal approach is summarized. The viability of such a system must still be demonstrated and many questions remain. Potentially, a wireless system can transfer power more efficiently and flexibly, especially to and from remote regions. This paper includes principle elements of worldwide wireless power transfer: the source: an oscillator/transmitter, the path: the cavity bounded by the earth and the ionosphere, and the receiver: a means of extracting power from the path. The system transfers and stores energy via the resonance modes of the cavity. The key challenges facing demonstration of technical feasibility are in finding an efficient means of coupling power into and out of the earth-ionosphere cavity, and in devising a feasible receiver that is both small and efficient. Along with demonstrating technical feasibility, new research must consider safety, environmental impact, susceptibility to weather, and effects on weather
Heat transfer from internally heated hemispherical pools
International Nuclear Information System (INIS)
Gabor, J.D.; Ellsion, P.G.; Cassulo, J.C.
1980-01-01
Experiments were conducted on heat transfer from internally heated ZnSO 4 -H 2 O pools to the walls of hemispherical containers. This experimental technique provides data for a heat transfer system that has to date been only theoretically treated. Three different sizes of copper hemispherical containers were used: 240, 280, 320 mm in diameter. The pool container served both as a heat transfer surface and as an electrode. The opposing electrode was a copper disk, 50 mm in diameter located at the top of the pool in the center. The top surface of the pool was open to the atmosphere
International Nuclear Information System (INIS)
Aharon, J.; Lahav, C.; Kalman, H.; Shai, I.
1996-01-01
The present work deals with natural convection on a vertical flat plate, where one side of the plate is maintained at a uniform temperature - T a , and the other side of the plate is exposed to an environment of constant temperature -T∞. The plate is consisted of several layers of conductive and non-conductive materials such that the series thermal resistance can be expressed as an equivalent heat transfer coefficient h eq 1/Σ(k i /d i ). It is also assumed a negligible axial conduction, which can be neglected. The present investigation treats the heat transfer problem in the laminar zone in air (P r ∼1). The wall effective heat transfer coefficient is in the range of 4.3 to 11.5 W/m 2 - deg C. An experimental apparatus was constructed to confirm the heat transfer features predicted analytically in a previous work. The local experimental Nusselt number was correlated with the modified Rayleigh number, for the laminar range (authors)
Transient heat transfer in liquid helium
International Nuclear Information System (INIS)
Shiotsu, Masahiro
1991-01-01
Detailed knowledge on the steady-state and transient heat transfer from solid surfaces in He I and He II is important as a database for the analysis of the influence of local thermal disturbances on the stability of He I or He II cooled large superconducting magnets. In this paper, an overview of the transient heat transfer characteristics on solid surfaces in He I and He II caused by various large stepwise heat inputs, such as the quasi-steady nucleate boiling with a certain lifetime in He I and the quasi-steady Kapitza conductance heat flux with a certain lifetime in He II, are presented in comparison with their steady-state heat transfer characteristics. (author)
The burden and outcome of in utero transfers.
Musson, Rebecca E; Harrison, Catherine M
2016-05-01
To quantify the number of intrauterine transfers (IUTs) arranged by Embrace Yorkshire and Humber Infant and Children's Transport Service and, to determine the outcome of when women delivered their babies, or when they were discharged following transfer. Identification of all IUTs Embrace arranged between January 1, 2011 and February 29, 2012 with data collection to determine delivery time or date of discharge. There were 623 IUT referrals with a mean time taken to arrange a transfer of 109 minutes. The mean distance of IUT was 42.5 miles, and the main reason for IUT request was capacity of referring unit. 247 (52%) women delivered during the same admission and 156 delivered within 48 hours of transfer. Of those undelivered, 111 (48.7%) were discharged within 48 hours. Fibronectin test was used in 51 patients. The IUT service provided by Embrace is busy, with significant demands on administrative staff time. Neonatal cot capacity and gestation are the main reasons for transfer. There is potentially a cohort of women who may not have benefitted from IUT. We suggest the use of obstetric expertise will enhance the service, while ongoing work looking at neonatal unit cot capacity problems continues. ©2015 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.
Reconfigurable electronics using conducting metal-organic frameworks
Allendorf, Mark D.; Talin, Albert Alec; Leonard, Francois; Stavila, Vitalie
2017-07-18
A device including a porous metal organic framework (MOF) disposed between two terminals, the device including a first state wherein the MOF is infiltrated by a guest species to form an electrical path between the terminals and a second state wherein the electrical conductivity of the MOF is less than the electrical conductivity in the first state. A method including switching a porous metal organic framework (MOF) between two terminals from a first state wherein a metal site in the MOF is infiltrated by a guest species that is capable of charge transfer to a second state wherein the MOF is less electrically conductive than in the first state.
Thermal conductivity tests on buffermasses of bentonite/silt
International Nuclear Information System (INIS)
Knutsson, S.
1977-09-01
The investigation concerns the thermal conductivity of the bentonite/quartz buffer mass suggested as embedding substance for radioactive canisters. The first part presents the theoretical relationships associated with the various heat transfer mechanisms in moist granular materials. Chapter 3 describes the author's experimental determination of the thermal conductivity of the buffer mass. The tested mass consisted of 10 percent (by weight) bentonite and 90 percent natural silt. Four tests were made with different water content values and degree of water saturation. A comparison between the measured and calculated thermal conductivities is given. It is shown that the conductivity can be calculated with an accuracy of +-20 percent. (author)
Knowledge Transfer Planning and Execution in Offshore Outsourcing
DEFF Research Database (Denmark)
Madsen, Sabine; Bødker, Keld; Tøth, Thomas
2015-01-01
In this paper, we report from a longitudinal project about knowledge transfer conducted in a major financial company headquartered in Denmark and an offshore development center located in Bangalore, India. We identify the main knowledge transfer challenges experienced by the case company....... The challenges inform the conceptual design of a systematic five-step approach to the company’s knowledge transfer. Our main contribution is to illustrate how extant research can be applied to understand and solve the knowledge transfer challenges of a particular company in a way that fits with the outsourcing...... setup and the company culture. We also draw attention to the fact that client side managers play a crucial role in determining how and with what priority knowledge transfer can take place. Our research indicates that a first, important step towards ensuring successful knowledge transfer in outsourcing...
Transferable, conductive TiO{sub 2} nanotube membranes for optoelectronics
Energy Technology Data Exchange (ETDEWEB)
Liu, Guohua [School of Energy and Environment, Anhui University of Technology, Maanshan 243002 (China); Department of Micro and Nano Systems Technology, Vestfold University College, Horten 3184 (Norway); Chen, Ting [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Sun, Yunlan; Chen, Guang [School of Energy and Environment, Anhui University of Technology, Maanshan 243002 (China); Wang, Kaiying, E-mail: Kaiying.Wang@hbv.no [Department of Micro and Nano Systems Technology, Vestfold University College, Horten 3184 (Norway)
2014-08-30
Graphical abstract: An optoelectronic device with vertical architecture offers straight conducting filaments for electron transportation. - Highlights: • Highly porous TiO{sub 2} nanotube membranes are prepared by two-step anodization. • An optoelectronic device is integrated with photocurrent transportation along the nanotube axial. • Straight conducting nano-filaments are beneficial for electron transportation. • Photoconductive performances are demonstrated under front/back-illumination. - Abstract: We report a facile approach for preparing free-standing and crystalline TiO{sub 2} nanotube membranes (TNMs) by taking advantage of differential mechanical stress between two anodic layers. The membrane exhibits visible light transmittance (∼40%) and UV absorption (∼99%) with good flexibility, which is favorable to integrate with substrates in optoelectronics. A sandwich-type device is assembled through stacking the membrane and substrates. The dependence of current-perpendicular-to-membrane vs applied voltage shows a remarkable photoconductive performance for both front and back illumination. The photocurrent value increases ∼2 or 3 orders magnitude under UV light radiation as compared to that in darkness. The photoresponse is arisen from high internal gain caused by hole trapping along the nanotube walls. This work is crucial for understanding intrinsic optical properties of nanostructured membranes.
Male gender explains increased birthweight in children born after transfer of blastocysts.
Kaartinen, N M; Kananen, K M; Rodriguez-Wallberg, K A; Tomás, C M; Huhtala, H Sa; Tinkanen, H I
2015-10-01
Does extended embryo culture have a different effect on the birthweight of girls and boys? The mean birthweight of boys born after fresh and frozen-thawed blastocyst transfer was increased compared with those born after cleavage stage embryo transfer. This effect was not detected among girls. Previous studies indicate that newborns from frozen-thawed cleavage stage embryos may present with a higher weight than newborns from fresh embryo transfers. With regard to fresh embryos, newborns after a blastocyst transfer have been reported as having higher birthweights than newborns from cleavage stage embryos. Retrospective multicentre case-control cohort study. All IVF/ICSI treatments were performed in the time-period from January 2008 to March 2014. Birthweight of singletons born at full-term (≥37 weeks), after fresh or frozen blastocyst embryo transfers (n = 277), were compared with weights of children born after fresh or frozen cleavage stage embryo transfers (Day 2-3) (n = 277). The cases and controls were matched by delivery week, and by gender. Data of IVF/ICSI treatments, and the treatments' outcomes were collected and analysed. The birthweight after a fresh blastocyst transfer was significantly higher (mean 3530.6 g) than that after a transfer of cleavage stage embryos (mean 3418.8 g; weight difference 111.8 g, P = 0.047). The weights of newborns after frozen-thawed blastocyst transfers (mean 3647.5 g) and the frozen-thawed cleavage stage embryo transfers (mean 3650.9 g), were similar (weight difference 3.4 g, P = 0.95). The boys born after transfer of frozen-thawed blastocysts had a significantly higher birthweight (mean 3767.9 g) than girls (3525.2 g; weight difference 242.7 g, P = 0.002), whereas the difference of birthweights between genders was only 13.5 g in cleavage stage (P = 0.863). The same effect was seen after fresh blastocyst transfers (weight difference 211.5 g, P = 0.011), but not after fresh Day 2-3 embryo transfers (weight difference 53.6 g, P
Technique for estimating relocated gap width for gap conductance calculations
International Nuclear Information System (INIS)
Klink, P.H.
1978-01-01
Thermally induced fuel fragmentation and relocation has been demonstrated to influence the thermal behavior of a fuel rod in two ways. The effective fuel pellet conductivity is decreased and pellet-to-cladding heat transfer is improved. This paper presents a correlation between as-built and relocated gap width which, used with the Ross and Stoute Gap Conductance Correlation and an appropriate fuel thermal expansion model, closely predicts the measured gap conductances
Oscillatory conductive heat transfer for a fiber in an ideal gas
Kuntz, H. L.; Perreira, N. D.
1985-01-01
A description of the thermal effects created by placing a cylindrical fiber in an inviscid, ideal gas, through which an acoustic wave propagates, is presented. The fibers and the gas have finite heat capacities and thermal conductivities. Expressions for the temperature distribution in the gas and in the material are determined. The temperature distribution is caused by pressure oscillations in the gas which, in turn, are caused by the passage of an acoustic wave. The relative value of a dimensionless parameter is found to be indicative of whether the exact or approximate equations should be used in the solution. This parameter is a function of the thermal conductivities and heat capacities of the fiber and gas, the acoustic frequency, and the fiber diameter.
DEFF Research Database (Denmark)
Nielsen, Mads Møller
The cornerstone in this dissertation is made up by three individual assessments of the diversity in the macromolecular landscape that can be obtained by applying relatively few efficient chemical tools. The intention is to gain deeper knowledge on the chemical tuning of proton exchange membranes...... of hydrocarbon macromolecular architectures, PSU with postsulfonated polystyrene (PS) grafts are investigated. Here, IEC is controlled through the degree of substitution, the graft length and DS. The grafting is performed with atom transfer radical polymerization (ATRP). The third assessment is dedicated...... of control by ATRP and click chemistry enables a wide selection of polymer structures with the handles: degree of substitution (DS), polymerization and sulfonation, and blending....
The Data Transfer Kit: A geometric rendezvous-based tool for multiphysics data transfer
International Nuclear Information System (INIS)
Slattery, S. R.; Wilson, P. P. H.; Pawlowski, R. P.
2013-01-01
The Data Transfer Kit (DTK) is a software library designed to provide parallel data transfer services for arbitrary physics components based on the concept of geometric rendezvous. The rendezvous algorithm provides a means to geometrically correlate two geometric domains that may be arbitrarily decomposed in a parallel simulation. By repartitioning both domains such that they have the same geometric domain on each parallel process, efficient and load balanced search operations and data transfer can be performed at a desirable algorithmic time complexity with low communication overhead relative to other types of mapping algorithms. With the increased development efforts in multiphysics simulation and other multiple mesh and geometry problems, generating parallel topology maps for transferring fields and other data between geometric domains is a common operation. The algorithms used to generate parallel topology maps based on the concept of geometric rendezvous as implemented in DTK are described with an example using a conjugate heat transfer calculation and thermal coupling with a neutronics code. In addition, we provide the results of initial scaling studies performed on the Jaguar Cray XK6 system at Oak Ridge National Laboratory for a worse-case-scenario problem in terms of algorithmic complexity that shows good scaling on 0(1 x 104) cores for topology map generation and excellent scaling on 0(1 x 105) cores for the data transfer operation with meshes of O(1 x 109) elements. (authors)
The Data Transfer Kit: A geometric rendezvous-based tool for multiphysics data transfer
Energy Technology Data Exchange (ETDEWEB)
Slattery, S. R.; Wilson, P. P. H. [Department of Engineering Physics, University of Wisconsin - Madison, 1500 Engineering Dr., Madison, WI 53706 (United States); Pawlowski, R. P. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185 (United States)
2013-07-01
The Data Transfer Kit (DTK) is a software library designed to provide parallel data transfer services for arbitrary physics components based on the concept of geometric rendezvous. The rendezvous algorithm provides a means to geometrically correlate two geometric domains that may be arbitrarily decomposed in a parallel simulation. By repartitioning both domains such that they have the same geometric domain on each parallel process, efficient and load balanced search operations and data transfer can be performed at a desirable algorithmic time complexity with low communication overhead relative to other types of mapping algorithms. With the increased development efforts in multiphysics simulation and other multiple mesh and geometry problems, generating parallel topology maps for transferring fields and other data between geometric domains is a common operation. The algorithms used to generate parallel topology maps based on the concept of geometric rendezvous as implemented in DTK are described with an example using a conjugate heat transfer calculation and thermal coupling with a neutronics code. In addition, we provide the results of initial scaling studies performed on the Jaguar Cray XK6 system at Oak Ridge National Laboratory for a worse-case-scenario problem in terms of algorithmic complexity that shows good scaling on 0(1 x 104) cores for topology map generation and excellent scaling on 0(1 x 105) cores for the data transfer operation with meshes of O(1 x 109) elements. (authors)
Effect of aerated concrete blockwork joints on the heat transfer performance uniformity
Pukhkal, Viktor; Murgul, Vera
2018-03-01
Analysis of data on the effect of joints of the aerated concrete blocks on the heat transfer uniformity of exterior walls was carried out. It was concluded, that the values of the heat transfer performance uniformity factor in the literature sources were obtained for the regular fragment of a wall construction by approximate addition of thermal conductivities. Heat flow patterns for the aerated concrete exterior walls amid different values of the thermal conductivity factors and design ambient air temperature of -26 °C were calculated with the use of "ELCUT" software for modelling of thermal patterns by finite element method. There were defined the values for the heat transfer performance uniformity factor, reduced total thermal resistance and heat-flux density for the exterior walls. The calculated values of the heat transfer performance uniformity factors, as a function of the coefficient of thermal conductivity of aerated concrete blocks, differ from the known data by a more rigorous thermal and physical substantiation.
Effect of aerated concrete blockwork joints on the heat transfer performance uniformity
Directory of Open Access Journals (Sweden)
Pukhkal Viktor
2018-01-01
Full Text Available Analysis of data on the effect of joints of the aerated concrete blocks on the heat transfer uniformity of exterior walls was carried out. It was concluded, that the values of the heat transfer performance uniformity factor in the literature sources were obtained for the regular fragment of a wall construction by approximate addition of thermal conductivities. Heat flow patterns for the aerated concrete exterior walls amid different values of the thermal conductivity factors and design ambient air temperature of -26 °C were calculated with the use of “ELCUT” software for modelling of thermal patterns by finite element method. There were defined the values for the heat transfer performance uniformity factor, reduced total thermal resistance and heat-flux density for the exterior walls. The calculated values of the heat transfer performance uniformity factors, as a function of the coefficient of thermal conductivity of aerated concrete blocks, differ from the known data by a more rigorous thermal and physical substantiation.
High Biofilm Conductivity Maintained Despite Anode Potential Changes in a Geobacter-Enriched Biofilm
This study systematically assessed intracellular electron transfer (IET) and extracellular electron transfer (EET) kinetics with respect to anode potential (Eanode) in a mixed-culture biofilm anode enriched with Geobacter spp. High biofilm conductivity (0.96–1.24 mScm^-1) was mai...
Karwa, Rajendra
2017-01-01
This textbook presents the classical treatment of the problems of heat transfer in an exhaustive manner with due emphasis on understanding of the physics of the problems. This emphasis is especially visible in the chapters on convective heat transfer. Emphasis is laid on the solution of steady and unsteady two-dimensional heat conduction problems. Another special feature of the book is a chapter on introduction to design of heat exchangers and their illustrative design problems. A simple and understandable treatment of gaseous radiation has been presented. A special chapter on flat plate solar air heater has been incorporated that covers thermo-hydraulic modeling and simulation. The chapter on mass transfer has been written looking specifically at the needs of the students of mechanical engineering. The book includes a large number and variety of solved problems with supporting line diagrams. The author has avoided duplicating similar problems, while incorporating more application-based examples. All the end-...
Measurement of heat transfers in cryogenic tank with several configurations
International Nuclear Information System (INIS)
Khemis, O.; Bessaieh, R.; Ait Ali, M.; Francois, M.X.
2004-01-01
The work presented here concerns the measurement of heat transfer in a cryogenic tank with several configurations. The experimental test incorporates the conductive heat in the neck, the convection heat transfers between the inner wall of the neck and the ascending vapor resulting from boiling, and the radiation heat transfers between the external envelope and the tank through a vacuum of 10 -8 mm Hg. An experimental prototype was produced in collaboration with the nuclear center of Orsay in France according to a didactic design, which takes into account the Wexler effect and the importance of the radiation compared to the conduction-convection heat transfer. The addition of a screen radiative ventilated with variable position on the neck (which can effectively replace several tens of floating screens), in order to find the optimal position, which minimizes the radiation flux, is presented in this paper
Effect of surface etching on condensing heat transfer
Energy Technology Data Exchange (ETDEWEB)
Seok, Sung Chul; Park, Jae Won; Jung, Jiyeon; Choi, Chonggun; Choi, Gyu Hong; Hwang, Seung Sik; Chung, Tae Yong; Shin, Donghoon [Kookmin University, Seoul (Korea, Republic of); Kim, Jin Jun [Hoseo University, Asan (Korea, Republic of)
2016-02-15
This study conducted experiments on humid air condensation during heat transfer in an air preheating exchanger attached to a home condensing boiler to improve thermal efficiency. An etchant composed of sulfuric acid and sodium nitrate was used to create roughness on the heat exchanger surface made from STS430J1L. A counter flow heat exchanger was fabricated to test the performance of heat transfer. Results showed that the overall heat transfer coefficients of all specimens treated with etchant improved with respect to the original specimens (not treated with etchant), and the overall heat transfer coefficient of the 60 s etching specimen increased by up to 15%. However, the increasing rate of the heat transfer coefficient was disproportional to the etching time. When the etching time specifically increased above 60 s, the heat transfer coefficient decreased. This effect was assumed to be caused by surface characteristics such as contact angle. Furthermore, a smaller contact angle or higher hydrophilicity leads to higher heat transfer coefficient.
Directory of Open Access Journals (Sweden)
Mahmood H. Ali
2015-02-01
Full Text Available A numerical study of non-Darcian natural convection heat transfer in a rectangular enclosure filled with porous medium saturated with viscous fluid was carried out. The effects of medium Rayleigh number, porosity, particle to fluid thermal conductivity ratio, Darcy number and enclosure aspect ratio on heat transfer were examined to demonstrate the ability of using this construction in thermal insulation of buildings walls.A modified Brinkman-Forchheimer-extended Darcy flow model was used and no-slip boundary conditions were imposed for velocity at the walls and the governing equations were expressed in dimensionless stream function, vorticity, and temperature formulation. The resulting algebraic equations obtained from finite difference discritization of vorticity and temperature equations are solved using (ADI method which uses Three Diagonal Matrix Algorithm (TDMA in each direction, while that of the stream function equation solved using successive iteration method.The study was done for the range of enclosure aspect ratio ( which is in the tall layers region at medium Rayleigh number ( , Darcy number (Da=10-3, 10-4, 10-5 , porosity (e=0.35, 0.45, 0.55, particle to fluid thermal conductivity (kS/kf=5.77, 38.5, 1385.5.The results showed that the Nusselt number is direct proportional to medium Rayleigh number and porosity and reversely proportional to Darcy number, ratio of particle to fluid thermal conductivity and enclosure aspect ratio. The variables that affect the heat transfer in the above arrangement was correlated in a mathematical equation that account better for their affects on heat transfer which is represented by mean Nusselt number (Nu.
Transfer-matrix approach for modulated structures with defects
International Nuclear Information System (INIS)
Kostyrko, T.
2000-01-01
We consider scattering of electrons by defects in a periodically modulated, quasi-one-dimensional structure, within a tight-binding model. Combining a transfer matrix method and a Green function method we derive a formula for a Landauer conductance and show its equivalence to the result of Kubo linear response theory. We obtain explicitly unperturbed lattice Green functions from their equations of motion, using the transfer matrices. We apply the presented formalism in computations of the conductance of several multiband modulated structures with defects: (a) carbon nanotubes (b) two-dimensional (2D) superlattice (c) modulated leads with 1D wire in the tunneling regime. (c) 2000 The American Physical Society
DEFF Research Database (Denmark)
Juhl, Pernille
, they are involved in preventive interventions. I conducted participatory observations with the children in their everyday life. Overall, the study stresses that even small children must be perceived as active participants who act upon and struggle with different conditions and meaning making processes across......In the paper I discuss how small children (0-4 year) develop through ‘conducting everyday life’ across contexts (Holzkamp 2013). I discuss how this process of conducting everyday life is essential when discussing the ‘good life for children’ from a child perspective. These issues are addressed...... contexts (home, day care, part-time foster family) and in relation to other co-participants....
The transfer of alkanoic acids from dodecane to water
International Nuclear Information System (INIS)
Sagert, N.H.; Quinn, M.J.; Dixon, R.S.
1981-01-01
A rotating diffusion cell was used to study the transfer of five alkanoic acids from dodecane to water under conditions of known interfacial area and hydrodynamics. hd The acids studied were acetic, butanoic, hexanoic, 2-methylbutanoic and 2,2-dimethylpropanoic acids. Small interfacial resistances to mass transfer were noted, the mass transfer coefficients for interfacial transfer being in the range 2.6 to 4.7 μm/s at 25 0 C. This small range means that the effects of the length and structure of the alkane chain on the resistance to mass transfer are minimal. A study of the temperature dependence of the resistance to mass transfer at the interface showed that the resistance is largely entropic rather than enthalpic. (author)
International Nuclear Information System (INIS)
Terres, H; Lizardi, A; Chávez, S; López, R; Vaca, M
2017-01-01
In this work, an exergy evaluation to determine the energy availability across to glass covers, place where the solar radiation enters toward a solar cooker box-type is done. Considering the heating process of water, the energy not used is quantified by means of exergy. The results allow identifying the glasses in the cover as the zone where the solar cooker could be improved. The conduction heat transfer losses for the glasses is most big than 75%. Because the values for the conduction heat losses are around 90%, which are very important, this allows to identify the cover glass as the area where improvements could be made in this type of solar cookers. (paper)
TRANSFERENCE BEFORE TRANSFERENCE.
Bonaminio, Vincenzo
2017-10-01
This paper is predominantly a clinical presentation that describes the transmigration of one patient's transference to another, with the analyst functioning as a sort of transponder. It involves an apparently accidental episode in which there was an unconscious intersection between two patients. The author's aim is to show how transference from one case may affect transference in another, a phenomenon the author calls transference before transference. The author believes that this idea may serve as a tool for understanding the unconscious work that takes place in the clinical situation. In a clinical example, the analyst finds himself caught up in an enactment involving two patients in which he becomes the medium of what happens in session. © 2017 The Psychoanalytic Quarterly, Inc.
Method for Measuring Thermal Conductivity of Small Samples Having Very Low Thermal Conductivity
Miller, Robert A.; Kuczmarski, Maria a.
2009-01-01
This paper describes the development of a hot plate method capable of using air as a standard reference material for the steady-state measurement of the thermal conductivity of very small test samples having thermal conductivity on the order of air. As with other approaches, care is taken to ensure that the heat flow through the test sample is essentially one-dimensional. However, unlike other approaches, no attempt is made to use heated guards to block the flow of heat from the hot plate to the surroundings. It is argued that since large correction factors must be applied to account for guard imperfections when sample dimensions are small, it may be preferable to simply measure and correct for the heat that flows from the heater disc to directions other than into the sample. Experimental measurements taken in a prototype apparatus, combined with extensive computational modeling of the heat transfer in the apparatus, show that sufficiently accurate measurements can be obtained to allow determination of the thermal conductivity of low thermal conductivity materials. Suggestions are made for further improvements in the method based on results from regression analyses of the generated data.
Heat Transfer Modeling and Validation for Optically Thick Alumina Fibrous Insulation
Daryabeigi, Kamran
2009-01-01
Combined radiation/conduction heat transfer through unbonded alumina fibrous insulation was modeled using the diffusion approximation for modeling the radiation component of heat transfer in the optically thick insulation. The validity of the heat transfer model was investigated by comparison to previously reported experimental effective thermal conductivity data over the insulation density range of 24 to 96 kg/cu m, with a pressure range of 0.001 to 750 torr (0.1 to 101.3 x 10(exp 3) Pa), and test sample hot side temperature range of 530 to 1360 K. The model was further validated by comparison to thermal conductivity measurements using the transient step heating technique on an insulation sample at a density of 144 kg/cu m over a pressure range of 0.001 to 760 torr, and temperature range of 290 to 1090 K.
Estimated Viscosities and Thermal Conductivities of Gases at High Temperatures
Svehla, Roger A.
1962-01-01
Viscosities and thermal conductivities, suitable for heat-transfer calculations, were estimated for about 200 gases in the ground state from 100 to 5000 K and 1-atmosphere pressure. Free radicals were included, but excited states and ions were not. Calculations for the transport coefficients were based upon the Lennard-Jones (12-6) potential for all gases. This potential was selected because: (1) It is one of the most realistic models available and (2) intermolecular force constants can be estimated from physical properties or by other techniques when experimental data are not available; such methods for estimating force constants are not as readily available for other potentials. When experimental viscosity data were available, they were used to obtain the force constants; otherwise the constants were estimated. These constants were then used to calculate both the viscosities and thermal conductivities tabulated in this report. For thermal conductivities of polyatomic gases an Eucken-type correction was made to correct for exchange between internal and translational energies. Though this correction may be rather poor at low temperatures, it becomes more satisfactory with increasing temperature. It was not possible to obtain force constants from experimental thermal conductivity data except for the inert atoms, because most conductivity data are available at low temperatures only (200 to 400 K), the temperature range where the Eucken correction is probably most in error. However, if the same set of force constants is used for both viscosity and thermal conductivity, there is a large degree of cancellation of error when these properties are used in heat-transfer equations such as the Dittus-Boelter equation. It is therefore concluded that the properties tabulated in this report are suitable for heat-transfer calculations of gaseous systems.
Final Report: Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters
Energy Technology Data Exchange (ETDEWEB)
Haggerty, Roy [Oregon State Univ., Corvallis, OR (United States); Day-Lewis, Fred [U.S. Geological Survey, Storrs, CT (United States); Singha, Kamini [Colorado School of Mines, Golden, CO (United States); Johnson, Timothy [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Binley, Andrew [Lancaster Univ. (United Kingdom); Lane, John [U.S. Geological Survey, Storrs, CT (United States)
2014-03-20
Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3
Investigating Wireless Power Transfer
St. John, Stuart A.
2017-01-01
Understanding Physics is a great end in itself, but is also crucial to keep pace with developments in modern technology. Wireless power transfer, known to many only as a means to charge electric toothbrushes, will soon be commonplace in charging phones, electric cars and implanted medical devices. This article outlines how to produce and use a…
TECHNOLOGY TRANSFER FROM THE UNIVERSITY OF MINNESOTA ESTIMATING THE ECONOMIC IMPACT
Ruttan, Vernon W.
2001-01-01
There is strong synergy among research, education, technology development and technology transfer. Examples of successful public-private technology transfer linkage institutions are provided. But efforts to document the benefits of research conducted at the University of Minnesota to the state have rarely been conducted with the rigor that would be required to meet the test of professional credibility. A program of research to develop more rigorous evidence on economic benefits to the State i...
Metallic conductivity in a disordered charge-transfer salt derived from cis-BET-TTF
Energy Technology Data Exchange (ETDEWEB)
Rovira, C. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Tarres, J. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Ribera, E. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Veciana, J. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Canadell, E. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Molins, E. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Mas, M. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Laukhin, V. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain)]|[Rossijskaya Akademiya Nauk, Chernogolovka (Russian Federation). Inst. Khimicheskoj Fiziki; Doublet, M.L. [Lab. de Structure et Dynamique (CNRS), Univ. de Montpellier 2 (France); Cowan, D.O. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemistry; Yang, S. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemistry
1997-02-28
The first example of a metallic charge-transfer salt derived from cis-bis(ethylenethio)-tetrathiafulvalene (BET-TTF) is reported. (BET-TTF){sub 2}SCN and (BET-TTF)SCN salts were obtained by electrocrystallization starting from trans-BET-TTF. X-ray crystal structure of the mixed-valence salt revealed that trans-cis isomerization occurs upon one electron oxidation. In spite of the structural disorder in both BET-TTF and the counterion, 2:1 salt is metallic down to 60 K and then resistance increases slowly down to 4 K. (orig.)
Lee, Jung Gil
2017-11-03
In order to improve water production of membrane distillation (MD), the development of high performance membrane having better mass transfer and enhancement of convection heat transfer in MD module have been continuously investigated. This paper presents the relationship between the heat and mass transfer resistance across the membrane and the performance improvement. Various ranges of mass transfer coefficient (MTC) from normal (0.3×10−6 to 2.1×10−6kg/m2sPa: currently available membranes) to high (>2.1×10−6kg/m2sPa: membranes under development) were simulated using an experimentally validated model at different ranges of convection heat transfer by varying the inlet flow rates and spacer enhancement factor. The effect of mass transfer and convection heat transfer on the MD performance parameters including temperature polarization coefficient (TPC), mean permeate flux, and specific energy consumption were investigated in a direct contact MD (DCMD) configuration. Results showed that improving the MTC at the low ranges is more important than that at the high ranges where the heat transfer resistance becomes dominant and hence the convection heat transfer coefficient must be increased. Therefore, an effort on designing MD modules using feed and permeate spacers and controlling the membrane surface roughness to increase the convection heat transfer and TPC in the channel aiming to enhance the flux is required because the currently developed mass transfer has almost reached the critical point.
Conjugate Heat Transfer of Mixed Convection for Viscoelastic Fluid Past a Stretching Sheet
Directory of Open Access Journals (Sweden)
Kai-Long Hsiao
2007-01-01
Full Text Available A conjugate heat transfer problem of a second-grade viscoelastic fluid past a stretching sheet has been studied. Governing equations include heat conduction equation of a stretching sheet, continuity equation, momentum equation, and energy equation of a second-grade fluid, analyzed by a combination of a series expansion method, the similarity transformation, and a second-order accurate finite-difference method. These solutions are used to iterate with the heat conduction equation of the stretching sheet to obtain distributions of the local convective heat transfer coefficient and the stretching sheet temperature. Ranges of dimensionless parameters, the Prandtl number Pr, the elastic number E and the conduction-convection coefficient Ncc are from 0.001 to 10, 0.0001 to 0.01, and 0.5 to 2.0, respectively. A parameter G, which is used to represent the dominance of the buoyant effect, is present in governing equations. Results indicated that elastic effect in the flow could increase the local heat transfer coefficient and enhance the heat transfer of a stretching sheet. In addition, same as the results from Newtonian fluid flow and conduction analysis of a stretching sheet, a better heat transfer is obtained with a larger Ncc, G, and E.
Heat transfer with freezing and thawing
Lunardini, VJ
1991-01-01
This volume provides a comprehensive overview on the vast amount of literature on solidification heat transfer. Chapter one develops important basic equations and discusses the validity of considering only conductive heat transfer, while ignoring convection, in the large class of materials which make up the porous media. Chapters 2 to 4 deal with problems that can be expressed in plane (Cartesian) coordinates. These problems are further divided into boundary conditions of temperature, prescribed heat flux, and surface convection. Chapter 5 examines some plane geometries involving three-dime
Heat transfer assembly for a fluorescent lamp and fixture
Siminovitch, M.J.; Rubenstein, F.M.; Whitman, R.E.
1992-12-29
In a lighting fixture including a lamp and a housing, a heat transfer structure is disclosed for reducing the minimum lamp wall temperature of a fluorescent light bulb. The heat transfer structure, constructed of thermally conductive material, extends from inside the housing to outside the housing, transferring heat energy generated from a fluorescent light bulb to outside the housing where the heat energy is dissipated to the ambient air outside the housing. Also disclosed is a method for reducing minimum lamp wall temperatures. Further disclosed is an improved lighting fixture including a lamp, a housing and the aforementioned heat transfer structure. 11 figs.
Electrochemical sensors based on polyconjugated conducting polymers
Energy Technology Data Exchange (ETDEWEB)
Zotti, G. (Ist. di Polarografia ed Elettrochimica Preparativa, Consiglio Nazionale delle Ricerche, Padua (Italy))
1992-09-01
An overview of the applications of polyconjugated conducting polymers to electrochemical sensors is given. Gas sensors, ion sensors, and biosensors (non-enzyme and enzyme sensors) are presented and discussed. The role of the polymer as enzyme host and mediator of charge transfer is particularly emphasized in the light of recent results. (orig.).
Heat transfer coeffcient for boiling carbon dioxide
DEFF Research Database (Denmark)
Knudsen, Hans Jørgen Høgaard; Jensen, Per Henrik
1997-01-01
Heat transfer coefficient and pressure drop for boiling carbon dioxide (R744) flowing in a horizontal pipe has been measured. The pipe is heated by condensing R22 outside the pipe. The heat input is supplied by an electrical heater wich evaporates the R22. With the heat flux assumed constant over...... the whole surface and with measured temperature difference between the inner surface and the evaporation temperature a mean heat transfer coefficient is calculated. The calculated heat transfer coefficient has been compared with the Chart Correlation of Shah. The Chart Correlation predicts too low heat...... transfer coefficient but the ratio between the measured and the calculated heat transfer coefficient is nearly constant and equal 1.9. With this factor the correlation predicts the measured data within 14% (RMS). The pressure drop is of the same order as the measuring uncertainty and the pressure drop has...
Heat transfer pipe shielding device for heat exchanger
International Nuclear Information System (INIS)
Hanawa, Jun.
1991-01-01
The front face and the rear face of a frame that surrounds the circumference of the water chamber body of a multi-tube heat exchanger are covered by a rotational shielding plate. A slit is radially formed to the shielding plate for the insertion of a probe or cleaner to the heat transfer pipe and a deflector is disposed on the side opposite to the slit. The end of the heat transfer pipe to be inspected is exposed to the outer side by way of the slit by the rotation of the shielding plate, and the probe or cleaner is inserted in the heat transfer pipe to conduct an eddy current injury monitoring test or cleaning. The inside of the water chamber and the heat transfer pipe is exhausted by a ventilation nozzle disposed to the frame. Accordingly, a shielding effect upon inspection and cleaning can be obtained and, in addition, inspection and exhaustion at the cleaning position can be conducted easily. Since the operation for attachment and detachment is easy, the effect of reducing radiation dose per unit can be obtained by the shortening of the operation time. (N.H.)
Quality standards for bone conduction implants.
Gavilan, Javier; Adunka, Oliver; Agrawal, Sumit; Atlas, Marcus; Baumgartner, Wolf-Dieter; Brill, Stefan; Bruce, Iain; Buchman, Craig; Caversaccio, Marco; De Bodt, Marc T; Dillon, Meg; Godey, Benoit; Green, Kevin; Gstoettner, Wolfgang; Hagen, Rudolf; Hagr, Abdulrahman; Han, Demin; Kameswaran, Mohan; Karltorp, Eva; Kompis, Martin; Kuzovkov, Vlad; Lassaletta, Luis; Li, Yongxin; Lorens, Artur; Martin, Jane; Manoj, Manikoth; Mertens, Griet; Mlynski, Robert; Mueller, Joachim; O'Driscoll, Martin; Parnes, Lorne; Pulibalathingal, Sasidharan; Radeloff, Andreas; Raine, Christopher H; Rajan, Gunesh; Rajeswaran, Ranjith; Schmutzhard, Joachim; Skarzynski, Henryk; Skarzynski, Piotr; Sprinzl, Georg; Staecker, Hinrich; Stephan, Kurt; Sugarova, Serafima; Tavora, Dayse; Usami, Shin-Ichi; Yanov, Yuri; Zernotti, Mario; Zorowka, Patrick; de Heyning, Paul Van
2015-01-01
Bone conduction implants are useful in patients with conductive and mixed hearing loss for whom conventional surgery or hearing aids are no longer an option. They may also be used in patients affected by single-sided deafness. To establish a consensus on the quality standards required for centers willing to create a bone conduction implant program. To ensure a consistently high level of service and to provide patients with the best possible solution the members of the HEARRING network have established a set of quality standards for bone conduction implants. These standards constitute a realistic minimum attainable by all implant clinics and should be employed alongside current best practice guidelines. Fifteen items are thoroughly analyzed. They include team structure, accommodation and clinical facilities, selection criteria, evaluation process, complete preoperative and surgical information, postoperative fitting and assessment, follow-up, device failure, clinical management, transfer of care and patient complaints.
The influence of mass transfer on solute transport in column experiments with an aggregated soil
Roberts, Paul V.; Goltz, Mark N.; Summers, R. Scott; Crittenden, John C.; Nkedi-Kizza, Peter
1987-06-01
The spreading of concentration fronts in dynamic column experiments conducted with a porous, aggregated soil is analyzed by means of a previously documented transport model (DFPSDM) that accounts for longitudinal dispersion, external mass transfer in the boundary layer surrounding the aggregate particles, and diffusion in the intra-aggregate pores. The data are drawn from a previous report on the transport of tritiated water, chloride, and calcium ion in a column filled with Ione soil having an average aggregate particle diameter of 0.34 cm, at pore water velocities from 3 to 143 cm/h. The parameters for dispersion, external mass transfer, and internal diffusion were predicted for the experimental conditions by means of generalized correlations, independent of the column data. The predicted degree of solute front-spreading agreed well with the experimental observations. Consistent with the aggregate porosity of 45%, the tortuosity factor for internal pore diffusion was approximately equal to 2. Quantitative criteria for the spreading influence of the three mechanisms are evaluated with respect to the column data. Hydrodynamic dispersion is thought to have governed the front shape in the experiments at low velocity, and internal pore diffusion is believed to have dominated at high velocity; the external mass transfer resistance played a minor role under all conditions. A transport model such as DFPSDM is useful for interpreting column data with regard to the mechanisms controlling concentration front dynamics, but care must be exercised to avoid confounding the effects of the relevant processes.
Electronic conductance of quantum wire with serial periodic potential structures
International Nuclear Information System (INIS)
Fayad, Hisham M.; Shabat, Mohammed M.; Abdus Salam International Centre for Theoretical Physics, Trieste
2000-08-01
A theory based on the total transfer matrix is presented to investigate the electronic conductance in a quantum wire with serial periodic potentials. We apply the formalism in computation of the electronic conductance in a wire with different physical parameters of the wire structure. The numerical results could be used in designing some future quantum electronic devices. (author)
Experience Transfer in Norwegian Oil and Gas Industry: Approaches and Organizational Mechanisms
Energy Technology Data Exchange (ETDEWEB)
Aase, Karina
1997-07-01
The core aim of the study is to explore the concept of experience transfer in oil and gas industry, and how an oil company approaches this concept. The thesis consists of five papers which are combined in a general description entitled 'Experience transfer in Norwegian oil and gas industry: approaches and organizational mechanisms'. The first paper describes how organizational members perceive experience transfer, and then specifies the many organizational and structural barriers that have to be overcome to achieve efficient experience transfer. The second paper elaborates and assesses the organizational means an oil company implements to address experience transfer. The third paper describes a process of improving and using requirement and procedure handbooks for experience transfer. The fourth paper explores in more detail how the use of information technology influences experience transfer. And the fifth paper compares organizational members' perceptions of experience transfer means in an oil company and an engineering company involved in offshore development projects. Some of the papers are based upon the same data material. Therefore there are reiterations in parts of the contents, especially in the methodological sections.
Linking Positive Affect and Motivation to Transfer within Training: A Multilevel Study
Paulsen, Hilko Frederik Klaas; Kauffeld, Simone
2017-01-01
Motivation to transfer is a critical element for successful training transfer. Whereas recent research has shown that training-related factors such as training design are related to motivation to transfer, participants' affective experiences have been neglected. Based on the broaden-and-build theory of positive emotions, we conducted a multilevel…
Determination of the heat transfer coefficient from IRT measurement data using the Trefftz method
Directory of Open Access Journals (Sweden)
Maciejewska Beata
2016-01-01
Full Text Available The paper presents the method of heat transfer coefficient determination for boiling research during FC-72 flow in the minichannels, each 1.7 mm deep, 24 mm wide and 360 mm long. The heating element was the thin foil, enhanced on the side which comes into contact with fluid in the minichannels. Local values of the heat transfer coefficient were calculated from the Robin boundary condition. The foil temperature distribution and the derivative of the foil temperature were obtained by solving the two-dimensional inverse heat conduction problem, due to measurements obtained by IRT. Calculations was carried out by the method based on the approximation of the solution of the problem using a linear combination of Trefftz functions. The basic property of this functions is they satisfy the governing equation. Unknown coefficients of linear combination of Trefftz functions are calculated from the minimization of the functional that expresses the mean square error of the approximate solution on the boundary. The results presented as IR thermographs, two-phase flow structure images and the heat transfer coefficient as a function of the distance from the channel inlet, were analyzed.
Nonsteady heat conduction code with radiation boundary conditions
International Nuclear Information System (INIS)
Fillo, J.A.; Benenati, R.; Powell, J.
1975-01-01
A heat-transfer model for studying the temperature build-up in graphite blankets for fusion reactors is presented. In essence, the computer code developed is for two-dimensional, nonsteady heat conduction in heterogeneous, anisotropic solids with nonuniform internal heating. Thermal radiation as well as bremsstrahlung radiation boundary conditions are included. Numerical calculations are performed for two design options by varying the wall loading, bremsstrahlung, surface layer thickness and thermal conductivity, blanket dimensions, time step and grid size. (auth)
Susman, S.; Volin, K.J.
Described is an ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A/sub 1 + x/D/sub 2-x/3/Si/sub x/P/sub 3 - x/O/sub 12 - 2x/3/, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.
Directory of Open Access Journals (Sweden)
K. V. Dobrego
2015-01-01
Full Text Available Differential approximation is derived from radiation transfer equation by averaging over the solid angle. It is one of the more effective methods for engineering calculations of radia- tive heat transfer in complex three-dimensional thermal power systems with selective and scattering media. The new method for improvement of accuracy of the differential approximation based on using of auto-adaptable boundary conditions is introduced in the paper. The efficiency of the named method is proved for the test 2D-systems. Self-consistent auto-adaptable boundary conditions taking into consideration the nonorthogonal component of the incident to the boundary radiation flux are formulated. It is demonstrated that taking in- to consideration of the non- orthogonal incident flux in multi-dimensional systems, such as furnaces, boilers, combustion chambers improves the accuracy of the radiant flux simulations and to more extend in the zones adjacent to the edges of the chamber.Test simulations utilizing the differential approximation method with traditional boundary conditions, new self-consistent boundary conditions and “precise” discrete ordinates method were performed. The mean square errors of the resulting radiative fluxes calculated along the boundary of rectangular and triangular test areas were decreased 1.5–2 times by using auto- adaptable boundary conditions. Radiation flux gaps in the corner points of non-symmetric sys- tems are revealed by using auto-adaptable boundary conditions which can not be obtained by using the conventional boundary conditions.
Determination of minor actinides fission cross sections by means of transfer reactions
Energy Technology Data Exchange (ETDEWEB)
Jurado, B.; Aiche, M.; Barreau, G.; Boyer, S.; Czajkowski, S.; Dassie, D.; Grosjean, C.; Guiral, A.; Haas, B.; Osmanov, B.; Petit, M. [CENBG - UMR 5795 CNRS/IN2P3-Univ. Bordeaux 1- Le Haut Vigneau, 33175 Gradignan (France); Berthoumieux, E.; Gunsing, F.; Perrot, L.; Theisen, Ch. [CEN Saclay, DSM/DAPNIA/SPhN, 91191 Gif-sur-Yvette cedex (France); Bauge, E. [CEA, SPhN, BP12 91680 Bruyeres-le-Chatel (France); Michel-Sendis, F. [IPN, 15 rue G. Clemenceau, 91406 Orsay cedex (France); Billebaud, A. [LPSC, 53 Avenue des Martyrs, 38026 Grenoble cedex (France); Wilson, J. N. [IPN, 15 rue G. Clemenceau, 91406 Orsay cedex (France); LPSC, 53 Avenue des Martyrs, 38026 Grenoble cedex (France); Ahmad, I.; Greene, J.P.; Janssens, R. V. F. [ANL, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)
2005-07-01
We present an original method that allows to determine neutron-induced cross sections of very short-lived minor actinides. This indirect method, based on the use of transfer reactions, has already been applied with success for the determination of the neutron-induced fission and capture cross section of {sup 233}Pa, a key nucleus in the {sup 232}Th - {sup 233}U fuel cycle. A recent experiment using this technique has been performed to determine the neutron-induced fission cross sections of {sup 242,243,244}Cm and {sup 241}Am which are present in the nuclear waste of the current U-Pu fuel cycle. These cross sections are highly relevant for the design of reactors capable to incinerate minor actinides. The first results will be illustrated. (authors)
Sadeghi, E.; Djilali, N.; Bahrami, M.
Heat transfer through the gas diffusion layer (GDL) is a key process in the design and operation of a proton exchange membrane (PEM) fuel cell. The analysis of this process requires determination of the effective thermal conductivity. This transport property differs significantly in the through-plane and in-plane directions due to the anisotropic micro-structure of the GDL. A novel test bed that allows separation of in-plane effective thermal conductivity and thermal contact resistance in GDLs is described in this paper. Measurements are performed using Toray carbon paper TGP-H-120 samples with varying polytetrafluoroethylene (PTFE) content at a mean temperature of 65-70 °C. The measurements are complemented by a compact analytical model that achieves good agreement with experimental data. The in-plane effective thermal conductivity is found to remain approximately constant, k ≈ 17.5 W m -1 K -1, over a wide range of PTFE content, and its value is about 12 times higher than that for through-plane conductivity.
Transient heat transfer in longitudinal fins of various profiles with ...
Indian Academy of Sciences (India)
Transient heat transfer through a longitudinal ﬁn of various proﬁles is studied. The thermal conductivity and heat transfer coefficients are assumed to be temperature dependent. The resulting partial differential equation is highly nonlinear. Classical Lie point symmetry methods are employed and some reductions are ...
Molecular engineering problems in heat and mass transfer
International Nuclear Information System (INIS)
Kotake, S.
1991-01-01
As for developing, manufacturing and applying new materials of advanced functions such as high-performance devices and high-temperature materials, fundamental understanding of the phenomena from the standpoint of molecular and atomic levels has been required. In these problems, the processes of heat and mass transfer play an important role, being one of the rate-controlling factors. But the energy levels associated with heat and mass transfer are of the orders much less than those of chemical reaction, and it is not easy to understand the thermal problems on the molecular and atomic basis. This paper views the processes of heat and mass transfer from the dynamical motions of atom and molecule for thermal engineering problems. Especially, problems are considered of heat conduction in fine-ceramics, sintered materials of high heat conductivity or high heat-insulation, phase change of condensation in vapor deposition processes such as CVD and PVD, and radiation in laser processing
Theory of periodic conjugate heat transfer
Zudin, Yuri B
2016-01-01
This book presents the theory of periodic conjugate heat transfer in detail. It offers a simplified description of the interaction between a solid body and a fluid as a boundary value problem of the heat conduction equation for the solid body.
Energy Technology Data Exchange (ETDEWEB)
Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je [Korea Institute of Machinery and Materials, Changwon (Korea, Republic of)
2016-09-15
An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space.
International Nuclear Information System (INIS)
Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je
2016-01-01
An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space
Photoactivation of heterocyclic change-transfer complexes-electrolytes
International Nuclear Information System (INIS)
Studzinskij, O.P.; Ponomareva, R.P.; Proskuryakova, T.V.
1999-01-01
Effect of light on the systems containing of five- or six-number nitrogen-containing heterocycles, molecular iodine and different-nature organic solvents, has been studied by the methods of absorption spectroscopy and electric conductivity measurement. It has been ascertained that in proton-donor solvents the complexes of 1:1 composition are formed with charge transfer, their electric conductivity increasing essentially with photoactivation [ru
Panzarasa, Guido; Dübner, Matthias; Soliveri, Guido; Edler, Matthias; Griesser, Thomas
2017-09-01
Patterning of functional surfaces is one of the cornerstones of nanotechnology as it allows the fabrication of sensors and lab-on-a-chip devices. Here, the patterning of self-assembled monolayers of branched poly(ethyleneimine) (bPEI) on silica was achieved by means of remote photocatalytic lithography. Moreover, when 2-bromoisobutyryl-modified bPEI was used, the resulting pattern could be amplified by grafting polymer brushes by means of surface-initiated atom transfer radical polymerization. In contrast to previous reports for the patterning of bPEI, the present approach can be conducted in minutes instead of hours, reducing the exposure time to UV radiation and enhancing the overall efficiency. Furthermore, our approach is much more user-friendly, allowing a facile fabrication of patterned initiator-modified surfaces and the use of inexpensive instrumentation such as a low-power UV source and a simple photomask. Considering the versatility of bPEI as a scaffold for the development of biosensors, patterning by means of remote photocatalytic lithography will open new opportunities in a broad field of applications.
International Nuclear Information System (INIS)
Thorpe, S.J.; Yoshino, S.; Ainsworth, R.W.; Harvey, N.W.
2004-01-01
The over-tip casing of the high-pressure turbine in a modern gas turbine engine is subjected to strong convective heat transfer that can lead to thermally induced failure (burnout) of this component. However, the complicated flow physics in this region is dominated by the close proximity of the moving turbine blades, which gives rise to significant temporal variations at the blade-passing frequency. The understanding of the physical processes that control the casing metal temperature is still limited and this fact has significant implications for the turbine design strategy. A series of experiments has been performed that seeks to address some of these important issues. This article reports the measurements of time-mean heat transfer and time-mean static pressure that have been made on the over-tip casing of a transonic axial-flow turbine operating at flow conditions that are representative of those found in modern gas turbine engines. Time-resolved measurements of these flow variables (that reveal the details of the blade-tip/casing interaction physics) are presented in a companion paper. The nozzle guide vane exit flow conditions in these experiments were a Mach number of 0.93 and a Reynolds number of 2.7 x 10 6 based on nozzle guide vane mid-height axial chord. The axial and circumferential distributions of heat transfer rate, adiabatic wall temperature, Nusselt number and static pressure are presented. The data reveal large axial variations in the wall heat flux and adiabatic wall temperature that are shown to be primarily associated with the reduction in flow stagnation temperature through the blade row. The heat flux falls by a factor of 6 (from 120 to 20 kW/m 2 ). In contrast, the Nusselt number falls by just 36% between the rotor inlet plane and 80% rotor axial chord; additionally, this drop is near to linear from 20% to 80% rotor axial chord. The circumferential variations in heat transfer rate are small, implying that the nozzle guide vanes do not produce
Directory of Open Access Journals (Sweden)
Balla Hyder H.
2015-01-01
Full Text Available Cu and Zn-water nanofluid is a suspension of the Cu and Zn nanoparticles with the size 50 nm in the water base fluid for different volume fractions to enhance its Thermophysical properties. The determination and measuring the enhancement of Thermophysical properties depends on many limitations. Nanoparticles were suspended in a base fluid to prepare a nanofluid. A coated transient hot wire apparatus was calibrated after the building of the all systems. The vibro-viscometer was used to measure the dynamic viscosity. The measured dynamic viscosity and thermal conductivity with all parameters affected on the measurements such as base fluids thermal conductivity, volume factions, and the temperatures of the base fluid were used as input to the Artificial Neural Fuzzy inference system to modeling both dynamic viscosity and thermal conductivity of the nanofluids. Then, the ANFIS modeling equations were used to calculate the enhancement in heat transfer coefficient using CFD software. The heat transfer coefficient was determined for flowing flow in a circular pipe at constant heat flux. It was found that the thermal conductivity of the nanofluid was highly affected by the volume fraction of nanoparticles. A comparison of the thermal conductivity ratio for different volume fractions was undertaken. The heat transfer coefficient of nanofluid was found to be higher than its base fluid. Comparisons of convective heat transfer coefficients for Cu and Zn nanofluids with the other correlation for the nanofluids heat transfer enhancement are presented. Moreover, the flow demonstrates anomalous enhancement in heat transfer nanofluids.
Sociality and intergenerational transfer of older adults' nostalgia.
Wildschut, Tim; Sedikides, Constantine; Robertson, Sara
2018-05-03
Interest in nostalgia has blossomed, yet its nature in older adulthood and potential for intergenerational transfer to younger adults has remained neglected. In Experiment 1, we focused on the content of older adults' nostalgic (vs. ordinary) recollections and asked whether older adults' nostalgia could be transferred to younger adults. We showed that nostalgia expressed in older adults' narratives was positively associated with nostalgia reported by young-adult readers. In Experiment 2, undergraduates read a nostalgic or ordinary narrative written by an older adult. Then they rated their own nostalgia as well as their perceived social connectedness, self-continuity, and meaning in life. Exposure to older adults' nostalgic (vs. ordinary) narratives promoted concurrent nostalgia among young adults, along with associated psychological benefits (social connectedness, self-continuity, meaning). The findings illustrate the potential for intergenerational transfer of nostalgia through written narratives, and attest to the universality of nostalgic themes across younger and older adults.
Heat transfer enhancement using 2MHz ultrasound.
Bulliard-Sauret, Odin; Ferrouillat, Sebastien; Vignal, Laure; Memponteil, Alain; Gondrexon, Nicolas
2017-11-01
The present work focuses on possible heat transfer enhancement from a heating plate towards tap water in forced convection by means of 2MHz ultrasound. The thermal approach allows to observe the increase of local convective heat transfer coefficients in the presence of ultrasound and to deduce a correlation between ultrasound power and Nusselt number. Heat transfer coefficient under ultrasound remains constant while heat transfer coefficient under silent conditions increases with Reynolds number from 900 up to 5000. Therefore, heat transfer enhancement factor ranges from 25% up to 90% for the same energy conditions (supplied ultrasonic power=110W and supplied thermal power=450W). In the same time cavitational activity due to 2MHz ultrasound emission was characterized from mechanical and chemical viewpoints without significant results. At least, Particle Image Velocimetry (PIV) measurements have been performed in order to investigate hydrodynamic modifications due to the presence of 2MHz ultrasound. It was therefore possible to propose a better understanding of heat transfer enhancement mechanism with high frequency ultrasound. Copyright © 2017 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Aharon, J; Lahav, C [Israel Atomic Energy Commission, Beersheba (Israel). Nuclear Research Center-Negev; Kalman, H; Shai, I [Ben-Gurion Univ. of the Negev, Beersheba (Israel) Dept, of Mechanical engineering, Pearlstone Center for Aeronautical Engineering Studies
1996-12-01
The present work deals with natural convection on a vertical flat plate, where one side of the plate is maintained at a uniform temperature - T{sub a}, and the other side of the plate is exposed to an environment of constant temperature -T{infinity}. The plate is consisted of several layers of conductive and non-conductive materials such that the series thermal resistance can be expressed as an equivalent heat transfer coefficient h{sub eq} 1/{Sigma}(k{sub i}/d{sub i}). It is also assumed a negligible axial conduction, which can be neglected. The present investigation treats the heat transfer problem in the laminar zone in air (P{sub r}{approx}1). The wall effective heat transfer coefficient is in the range of 4.3 to 11.5 W/m{sup 2} - deg C. An experimental apparatus was constructed to confirm the heat transfer features predicted analytically in a previous work. The local experimental Nusselt number was correlated with the modified Rayleigh number, for the laminar range (authors).
Transfer function analysis of radiographic imaging systems
International Nuclear Information System (INIS)
Metz, C.E.; Doi, K.
1979-01-01
The theoretical and experimental aspects of the techniques of transfer function analysis used in radiographic imaging systems are reviewed. The mathematical principles of transfer function analysis are developed for linear, shift-invariant imaging systems, for the relation between object and image and for the image due to a sinusoidal plane wave object. The other basic mathematical principle discussed is 'Fourier analysis' and its application to an input function. Other aspects of transfer function analysis included are alternative expressions for the 'optical transfer function' of imaging systems and expressions are derived for both serial and parallel transfer image sub-systems. The applications of transfer function analysis to radiographic imaging systems are discussed in relation to the linearisation of the radiographic imaging system, the object, the geometrical unsharpness, the screen-film system unsharpness, other unsharpness effects and finally noise analysis. It is concluded that extensive theoretical, computer simulation and experimental studies have demonstrated that the techniques of transfer function analysis provide an accurate and reliable means for predicting and understanding the effects of various radiographic imaging system components in most practical diagnostic medical imaging situations. (U.K.)
Son, Chang-Hyo; Oh, Hoo-Kyu
2012-11-01
The condensation heat transfer characteristics for CO2 flowing in a horizontal microfin tube were investigated by experiment with respect to condensation temperature and mass flux. The test section consists of a 2,400 mm long horizontal copper tube of 4.6 mm inner diameter. The experiments were conducted at refrigerant mass flux of 400-800 kg/m2s, and saturation temperature of 20-30 °C. The main experimental results showed that annular flow was highly dominated the majority of condensation flow in the horizontal microfin tube. The condensation heat transfer coefficient increases with decreasing saturation temperature and increasing mass flux. The experimental data were compared against previous heat transfer correlations. Most correlations failed to predict the experimental data. However, the correlation by Cavallini et al. showed relatively good agreement with experimental data in the microfin tube. Therefore, a new condensation heat transfer correlation is proposed with mean and average deviations of 3.14 and -7.6 %, respectively.
Forced convection heat transfer correlation for finned plates in a duct
International Nuclear Information System (INIS)
Chae, Myeong-Seon; Moon, Je-Young; Chung, Bum-Jin
2014-01-01
Forced convection heat transfer experiments were conducted for plate-fin in a duct using various fin spacing, fin height, duct width, Reynolds number for Prandtl numbers 2,014. Based upon analogy concept, mass transfer rate were measured instead of heat transfer rates. The heat transfer rates were enhanced with the increase of fin height and decrease of fin spacing as they increase the heat transfer area. Meanwhile, heat transfer rates were impaired with the increase of the duct width as the bypass flows increased to tip clearance region. Forced convection heat transfer correlations were developed for laminar and turbulent flow conditions and for narrow and wide ducts. The work draws attention to the tip clearance on the heat transfer of the finned plate in a duct. (author)
Flow and heat transfer behaviour of nanofluids in microchannels
Directory of Open Access Journals (Sweden)
James Bowers
2018-04-01
Full Text Available Flow and heat transfer of aqueous based silica and alumina nanofluids in microchannels were experimentally investigated. The measured friction factors were higher than conventional model predictions at low Reynolds numbers particularly with high nanoparticle concentrations. A decrease in the friction factor was observed with increasing Reynolds number, possibly due to the augmentation of nanoparticle aggregate shape arising from fluid shear and alteration of local nanoparticle concentration and nanofluid viscosity. Augmentation of the silica nanoparticle morphology by fluid shear may also have affected the friction factor due to possible formation of a core/shell structure of the particles. Measured thermal conductivities of the silica nanofluids were in approximate agreement with the Maxwell-Crosser model, whereas the alumina nanofluids only showed slight enhancements. Enhanced convective heat transfer was observed for both nanofluids, relative to their base fluids (water, at low particle concentrations. Heat transfer enhancement increased with increasing Reynolds number and microchannel hydraulic diameter. However, the majority of experiments showed a larger increase in pumping power requirements relative to heat transfer enhancements, which may hinder the industrial uptake of the nanofluids, particularly in confined environments, such as Micro Electro-Mechanical Systems (MEMS. Keywords: Nanofluid, Microchannel, Heat transfer, Pressure drop, Friction factor, Thermal conductivity, Viscosity
Melko, Joshua J; Ard, Shaun G; Johnson, Ryan S; Shuman, Nicholas S; Guo, Hua; Viggiano, Albert A
2014-09-18
We have determined the rate constants and branching ratios for the reactions of CO(+) with CH4 and CD4 in a variable-temperature selected ion flow tube. We find that the rate constants are collisional for all temperatures measured (193-700 K for CH4 and 193-500 K for CD4). For the CH4 reaction, three product channels are identified, which include charge transfer (CH4(+) + CO), H-atom transfer (HCO(+) + CH3), and H-atom expulsion (CH3CO(+) + H). H-atom transfer is slightly preferred to charge transfer at low temperature, with the charge-transfer product increasing in contribution as the temperature is increased (H-atom expulsion is a minor product for all temperatures). Analogous products are identified for the CD4 reaction. Density functional calculations on the CO(+) + CH4 reaction were also conducted, revealing that the relative temperature dependences of the charge-transfer and H-atom transfer pathways are consistent with an initial charge transfer followed by proton transfer.
Mass and Heat Transfer in Ion-Exchange Membranes Applicable to Solid Polymer Fuel Cells
Energy Technology Data Exchange (ETDEWEB)
Otteroey, M
1996-04-01
In this doctoral thesis, an improved emf method for determination of transference numbers of two counter ions in ion-exchange membranes is presented. Transference numbers were obtained as a continuous function of the composition. The method avoids problems with diffusion by using a stack of membranes. Water transference coefficients in ion-exchange membranes is discussed and reversible and irreversible water transfer is studied by emf methods. Efforts were made to get data relevant to the solid polymer fuel cell. The results support the findings of other researchers that the reversible water transfer is lower than earlier predicted. A chapter on the conductivity of ion-exchange membranes establishes a method to separate the very thin liquid layers surrounding the membranes in a stack. Using the method it was found that the conductivity is obtained with high accuracy and that the liquid layer in a membrane stack can contribute significantly to the total measured resistance. A four point impedance method was tested to measure the conductivity of membranes under fuel cell conditions. Finally, there is a discussion of reversible heat effects and heat transfer in ion-exchange membranes. 155 refs., 45 figs., 13 tabs.
Conjugated heat transfer in laminar flow between parallel-plates channel
International Nuclear Information System (INIS)
Guedes, R.O.C.; Cotta, R.M.; Brum, N.C.L.
1989-01-01
An analysis is made of conjugated convective-conductive heat transfer in laminar flow of a newtonian fluid between parallel-plates channel, taking into account the longitudinal conduction along the duct walls only, by neglecting the transversal temperature gradients in the solid. This extended Graetz-type problem is then analytically handled through the generalized integral transform technique, providing accurate numerical results for quantities of practical interest sucyh as bulk and wall temperatures, and Nusselt numbers. The effects of a conjugation parameter and Biot number on heat transfer behavior are then investigated. (author)
International Nuclear Information System (INIS)
Shukur, M.F.; Kadir, M.F.Z.
2015-01-01
Highlights: • Cation transference number of the highest conducting starch-chitosan-NH 4 Cl-glycerol electrolyte is 0.56. • LSV has shown that the polymer electrolyte is suitable for fabrication of EDLC and proton batteries. • The fabricated EDLC has been charged and discharged for 500 cycles. • Secondary proton battery has been charged and discharged for 40 cycles. - Abstract: This paper reports the characterization of starch-chitosan blend based solid polymer electrolyte (SPE) system and its application in electrochemical double layer capacitor (EDLC) and proton batteries. All the SPEs are prepared via solution cast technique. Results from X-ray diffraction (XRD) verify the conductivity result from our previous work. Scanning electron microscopy (SEM) analysis shows the difference in the electrolyte's surface with respect to NH 4 Cl and glycerol content. From transference number measurements (TNM), transference number of ion (t ion ) of the electrolytes shows that ion is the dominant conducting species. Transference number of cation (t + ) for the highest conducting electrolyte is found to be 0.56. Linear sweep voltammetry (LSV) result confirms the suitability of the highest conducting electrolyte to be used in the fabrication of EDLC and proton batteries. The EDLC has been characterized using cyclic voltammetry (CV) and galvanostatic charge-discharge measurements. The open circuit potential (OCP) of the primary proton batteries for 48 h is lasted at (1.54 ± 0.02) V, while that of secondary proton batteries is lasted at (1.58 ± 0.01) V. The primary proton batteries have been discharged at different constant currents. The secondary proton battery has been charged and discharged for 40 cycles
Zheleva, Denitsa; Viklund, Alexandra
2014-01-01
The following case study aims to explore the knowledge transfer and its implications in the context of a soft service firm. The complexity of knowledge itself and the knowledge transfer process in service firms brings new challenges. The phenomenon was investigated by the application of grounded theory. Interviews were conducted with employees at a company present in the Quick Service Restaurant segment. It resulted in several findings that were not reported by previous literature. Firstly, w...
Numerical simulation of heat transfer in metal foams
Gangapatnam, Priyatham; Kurian, Renju; Venkateshan, S. P.
2018-02-01
This paper reports a numerical study of forced convection heat transfer in high porosity aluminum foams. Numerical modeling is done considering both local thermal equilibrium and non local thermal equilibrium conditions in ANSYS-Fluent. The results of the numerical model were validated with experimental results, where air was forced through aluminum foams in a vertical duct at different heat fluxes and velocities. It is observed that while the LTE model highly under predicts the heat transfer in these foams, LTNE model predicts the Nusselt number accurately. The novelty of this study is that once hydrodynamic experiments are conducted the permeability and porosity values obtained experimentally can be used to numerically simulate heat transfer in metal foams. The simulation of heat transfer in foams is further extended to find the effect of foam thickness on heat transfer in metal foams. The numerical results indicate that though larger foam thicknesses resulted in higher heat transfer coefficient, this effect weakens with thickness and is negligible in thick foams.
Yamaguchi, K; Jürgens, K D; Bartels, H; Piiper, J
1987-01-01
To estimate the advantage of the small red blood cells (RBC) of high-altitude camelids for O2 transfer, the kinetics of O2 uptake into and release from the RBC obtained from llama, vicuña and alpaca were investigated at 37 degrees C with a stopped-flow technique. O2 transfer conductance of RBC (G) was estimated from the rate of O2 saturation change and the corresponding O2 pressure difference between medium and hemoglobin. For comparison, O2 kinetics for the RBC of a low-altitude camelid (dromedary camel) and the pygmy goat were determined and previously measured values for human RBC were used. O2 transfer of RBC was found to be strongly influenced by extracellular diffusion, except with O2 release into dithionite solutions of sufficiently high concentration (greater than 30 mM). The G values measured in these 'standard' conditions, Gst (in mmol X min-1 X Torr-1 X (ml RBC)-1) were: high-altitude camelids, 0.58 (averaged for llama, alpaca and vicuña since there were no significant interspecific differences); camel 0.42; goat, 0.42; man, 0.39. The differences can in part be attributed to expected effects of the size and shape of the RBC (volume, surface area, mean thickness), as well as to the intracellular O2 diffusivity which depends on the concentration of cellular hemoglobin. The high Gst of RBC of high-altitude camelids may be considered to enhance O2 transfer in lungs and tissues. But the O2 transfer conductance of blood, theta, equal to Gst multiplied by hematocrit (in mmol X min-1 X Torr-1 X (ml blood)-1), was only slightly higher as compared to other species: 0.20 (llama, alpaca, vicuña), 0.14 (camel), 0.18 (goat), 0.17 (man).
Heat Transfer in a Fixed Bed of Straw Char
DEFF Research Database (Denmark)
Fjellerup, Jan Søren; Henriksen, Ulrik Birk; Jensen, Anker
2003-01-01
A model for the thermal conductivity of a straw char bed has been developed. The model extends the work of Yagi and Kunii to describe heat transfer in a bed of cylinders, using a relationship between the interparticle distance and the external porosity. To verify the model, thermal conductivity...... the experimental uncertainty over the range of conditions investigated. The heat transfer model was used in a parametric study to evaluate the effect of gas flow rate, particle diameter, porosity, and temperature on the thermal conductivity in a straw char bed....... experiments were performed on shredded and un-shredded straw char samples, varying particle size, bed packing (loose or dense), and temperature. Predictions with the model, using the measured external porosity and particle diameter as input parameters, are in agreement with measurements within...
Transference of kettlebell training to strength, power, and endurance.
Manocchia, Pasquale; Spierer, David K; Lufkin, Adrienne K S; Minichiello, Jacqueline; Castro, Jessica
2013-02-01
Kettlebells are a popular implement in many strength and conditioning programs, and their benefits are touted in popular literature, books, and videos. However, clinical data on their efficacy are limited. The purpose of this study was to examine whether kettlebell training transfers strength and power to weightlifting and powerlifting exercises and improves muscular endurance. Thirty-seven subjects were assigned to an experimental (EXP, n = 23; mean age = 40.9 ± 12.9 years) or a control group (CON; n = 14; mean age = 39.6 ± 15.8 years), range 18-72 years. The participants were required to perform assessments including a barbell clean and jerk, barbell bench press, maximal vertical jump, and 45° back extensions to volitional fatigue before and after a 10-week kettlebell training program. Training was structured in a group setting for 2 d·wk(-1) for 10 weeks. A repeated measures analysis of variance was conducted to determine group × time interactions and main effects. Post hoc pairwise comparisons were conducted when appropriate. Bench press revealed a time × group interaction and a main effect (p power and strength in response to 10 weeks of training with kettlebells. Traditional training methods may not be convenient or accessible for strength and conditioning specialists, athletes, coaches, and recreational exercisers. The current data suggest that kettlebells may be an effective alternative tool to improve performance in weightlifting and powerlifting.
Heat Transfer and Cooling Techniques at Low Temperature
Baudouy, B
2014-07-17
The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.
Legal aspects of the transfer of nuclear technology
International Nuclear Information System (INIS)
Sartorelli, C.
1980-03-01
The paper stresses the importance of nuclear technology transfer and describes the legal instruments for transfer of technical and scientific technology, particularly from the contractual viewpoint. A description follows of the setting-up of national joint ventures for nuclear power plant projects with emphasis on technological know-how to enable operation of plants in compliance with safety standards. The possibility is discussed of the export of nuclear technology, and finally mention is made of a proposal for a 'code of conduct' on such transfers in the framework of the United Nations, having regard to the 'London agreements' on nuclear exports. (NEA) [fr
Enhancement of heat transfer using nanofluids - An overview
Energy Technology Data Exchange (ETDEWEB)
Godson, Lazarus; Mohan Lal, D. [Refrigeration and Air-Conditioning Division, Department of Mechanical Engineering., College of Engineering, Anna University, Chennai 600 025, Tamil Nadu (India); Raja, B. [Indian Institute of Information Technology, Design and Manufacturing-Kancheepuram Indian Institute of Technology-Madras, Chennai 600 036, Tamil Nadu (India); Wongwises, S. [Fluid Mechanics, Thermal Engineering and Multiphase Flow (FUTURE), Dept. of Mechanical Engineering, King Mongkut' s University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand)
2010-02-15
A colloidal mixture of nano-sized particles in a base fluid, called nanofluids, tremendously enhances the heat transfer characteristics of the original fluid, and is ideally suited for practical applications due to its marvelous characteristics. This article addresses the unique features of nanofluids, such as enhancement of heat transfer, improvement in thermal conductivity, increase in surface volume ratio, Brownian motion, thermophoresis, etc. In addition, the article summarizes the recent research in experimental and theoretical studies on forced and free convective heat transfer in nanofluids, their thermo-physical properties and their applications, and identifies the challenges and opportunities for future research. (author)
Heat Transfer and Cooling Techniques at Low Temperature
Energy Technology Data Exchange (ETDEWEB)
Baudouy, B [Saclay (France)
2014-07-01
The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.
Two-Dimensional Variable Property Conjugate Heat Transfer Simulation of Nanofluids in Microchannels
International Nuclear Information System (INIS)
Ramiar, A.; Ranjbar, A.A.
2013-01-01
Laminar two-dimensional forced convective heat transfer of CuO-water and Al 2 O 3 -water nanofluids in a horizontal microchannel has been studied numerically, considering axial conduction effects in both solid and liquid regions and variable thermal conductivity and dynamic viscosity. The results show that using nanoparticles with higher thermal conductivities will intensify enhancement of heat transfer characteristics and slightly increases shear stress on the wall. The obtained results show more steep changes in Nusselt number for lower diameters and also higher values of Nusselt number by decreasing the diameter of nanoparticles. Also, by utilizing conduction number as the criterion, it was concluded from the results that adding nanoparticles will intensify the axial conduction effect in the geometry considered.
Air-water transfer of hydrogen sulfide
DEFF Research Database (Denmark)
Yongsiri, C.; Vollertsen, J.; Rasmussen, M. R.
2004-01-01
The emissions process of hydrogen sulfide was studied to quantify air–water transfer of hydrogen sulfide in sewer networks. Hydrogen sulfide transfer across the air–water interface was investigated at different turbulence levels (expressed in terms of the Froude number) and pH using batch...... experiments. By means of the overall mass–transfer coefficient (KLa), the transfer coefficient of hydrogen sulfide (KLaH2S), referring to total sulfide, was correlated to that of oxygen (KLaO2) (i.e., the reaeration coefficient). Results demonstrate that both turbulence and pH in the water phase play...... a significant role for KLaH2S. An exponential expression is a suitable representation for the relationship between KLaH2S and the Froude number at all pH values studied (4.5 to 8.0). Because of the dissociation of hydrogen sulfide, KLaH2S increased with decreasing pH at a constant turbulence level. Relative...
Job transfers: a neglected aspect of migration in Malaysia.
Menon, R
1987-01-01
"This article examines the incidence of [job-related] transfers in Malaysia. The retrospective migration data from the Malaysia Family Life Survey [conducted in 1976-1977] are used to demonstrate that transfers comprise 18 percent of all migration in the country and that there has been a rise in the incidence of transfers over a 35 year period. Factors underlying this trend are outlined. Furthermore, significant differences in age, educational attainment and other characteristics between transferees and other types of migrants are identified and their implications discussed." excerpt
Heat transfer studies on spiral plate heat exchanger
Directory of Open Access Journals (Sweden)
Rajavel Rangasamy
2008-01-01
Full Text Available In this paper, the heat transfer coefficients in a spiral plate heat exchanger are investigated. The test section consists of a plate of width 0.3150 m, thickness 0.001 m and mean hydraulic diameter of 0.01 m. The mass flow rate of hot water (hot fluid is varying from 0.5 to 0.8 kg/s and the mass flow rate of cold water (cold fluid varies from 0.4 to 0.7 kg/s. Experiments have been conducted by varying the mass flow rate, temperature, and pressure of cold fluid, keeping the mass flow rate of hot fluid constant. The effects of relevant parameters on spiral plate heat exchanger are investigated. The data obtained from the experimental study are compared with the theoretical data. Besides, a new correlation for the Nusselt number which can be used for practical applications is proposed.
Heat Transfer Basics and Practice
Böckh, Peter
2012-01-01
The book provides an easy way to understand the fundamentals of heat transfer. The reader will acquire the ability to design and analyze heat exchangers. Without extensive derivation of the fundamentals, the latest correlations for heat transfer coefficients and their application are discussed. The following topics are presented - Steady state and transient heat conduction - Free and forced convection - Finned surfaces - Condensation and boiling - Radiation - Heat exchanger design - Problem-solving After introducing the basic terminology, the reader is made familiar with the different mechanisms of heat transfer. Their practical application is demonstrated in examples, which are available in the Internet as MathCad files for further use. Tables of material properties and formulas for their use in programs are included in the appendix. This book will serve as a valuable resource for both students and engineers in the industry. The author’s experience indicates that students, after 40 lectures and exercises ...
Heat exchanger device and method for heat removal or transfer
Koplow, Jeffrey P
2013-12-10
Systems and methods for a forced-convection heat exchanger are provided. In one embodiment, heat is transferred to or from a thermal load in thermal contact with a heat conducting structure, across a narrow air gap, to a rotating heat transfer structure immersed in a surrounding medium such as air.
Impact of the Flameholder Heat Conductivity on Combustion Instability Characteristics
Hong, Seunghyuck
2012-06-11
In this paper, we investigate the impact of heat transfer between the flame and the flame-holder on the dynamic stability characteristics in a 50-kW backward facing step combustor. We conducted tests where we use a backward step block made of two different materials: ceramic and stainless steel whose thermal conductivities are 1.06 and 12 W/m/K, respectively. A set of experiments was conducted using a propane/air mixture at Re = 6500 for the inlet temperature of 300 - 500 K at atmospheric pressure. We measure the dynamic pressure and flame chemiluminescence to examine distinct stability characteristics using each flame-holder material over a range of operating conditions. We find that for tests with a flame-holder made of ceramic, the onset of instability is significantly delayed in time and, for certain operating conditions, disappears altogether. Stated differently, for certain operating conditions, the combustor can be stabilized by reducing the thermal conductivity of the flame-holder. As the thermal conductivity of the flame-holder increases, the combustor becomes increasingly unstable over a range of operating conditions. These results imply that the dynamic stability characteristics depend strongly on the heat transfer between the flame and the combustor wall near the flame anchoring region. Copyright © 2012 by ASME.
Complete heat transfer solutions of an insulated regular polygonal pipe by using a PWTR model
International Nuclear Information System (INIS)
Wong, K.-L.; Chou, H.-M.; Li, Y.-H.
2004-01-01
The heat transfer characteristics for insulated long regular polygonal (including circular) pipes are analyzed by using the same PWRT model in the present study as that used by Chou and Wong previously [Energy Convers. Manage. 44 (4) (2003) 629]. The thermal resistance of the inner convection term and the pipe conduction term in the heat transfer rate are not neglected in the present study. Thus, the complete heat transfer solution will be obtained. The present results can be applied more extensively to practical situations, such as heat exchangers. The results of the critical thickness t cr and the neutral thickness t e are independent of the values of J (generated by the combined effect of the inner convection term and the pipe conduction term). However, the heat transfer rates are dependent on the values of J. The present study shows that the thermal resistance of the inner convection term and the pipe conduction term cannot be neglected in the heat transfer equation in situations of low to medium inner convection coefficients h i and/or low to medium pipe conductivities K, especially in situations with large pipe sizes or/and great outer convection coefficients h 0
Multi-sphere unit cell model to calculate the effective thermal conductivity in pebble bed reactors
International Nuclear Information System (INIS)
Van Antwerpen, W.; Rousseau, P.G.; Du Toit, C.G.
2010-01-01
A proper understanding of the mechanisms of heat transfer, fluid flow and pressure drop through a packed bed of spheres is of utmost importance in the design of a high temperature Pebble Bed Reactor (PBR). While the gas flows predominantly in the axial direction through the bed, the total effective thermal conductivity is a lumped parameter that characterises the total heat transfer in the radial direction through the packed bed. The study of the effective thermal conductivity is important because it forms an intricate part of the self-acting decay heat removal chain, which is directly related to the PBR safety case. The effective thermal conductivity is the summation of various heat transport phenomena. These are the enhanced thermal conductivity due to turbulent mixing as the fluid passes through the voids between pebbles, heat transfer due to the movement of the solid spheres and thermal conduction and thermal radiation between the spheres in a stagnant fluid environment. In this study, the conduction and radiation between the spheres are investigated. Firstly, existing correlations for the effective thermal conductivity are investigated, with particular attention given to its applicability in the near-wall region. Several phenomena in particular are examined namely: conduction through the spheres, conduction through the contact area between the spheres, conduction through the gas phase and radiation between solid surfaces. A new approach to simulate the effective thermal conductivity for randomly packed beds is then presented, namely the so-called Multi-sphere Unit Cell Model. The model is validated by comparing the results with that obtained in experiments. (authors)
Weis, James; Bashyam, Ashvin; Ekchian, Gregory J; Paisner, Kathryn; Vanderford, Nathan L
2018-01-01
Background: A large number of highly impactful technologies originated from academic research, and the transfer of inventions from academic institutions to private industry is a major driver of economic growth, and a catalyst for further discovery. However, there are significant inefficiencies in academic technology transfer. In this work, we conducted a data-driven assessment of translational activity across United States (U.S.) institutions to better understand how effective universities are in facilitating the transfer of new technologies into the marketplace. From this analysis, we provide recommendations to guide technology transfer policy making at both the university and national level. Methods: Using data from the Association of University Technology Managers U.S. Licensing Activity Survey, we defined a commercialization pipeline that reflects the typical path intellectual property takes; from initial research funding to startup formation and gross income. We use this pipeline to quantify the performance of academic institutions at each step of the process, as well as overall, and identify the top performing institutions via mean reciprocal rank. The corresponding distributions were visualized and disparities quantified using the Gini coefficient. Results: We found significant discrepancies in commercialization activity between institutions; a small number of institutions contribute to the vast majority of total commercialization activity. By examining select top performing institutions, we suggest improvements universities and technology transfer offices could implement to emulate the environment at these high-performing institutions. Conclusion: Significant disparities in technology transfer performance exist in which a select set of institutions produce a majority share of the total technology transfer activity. This disparity points to missed commercialization opportunities, and thus, further investigation into the distribution of technology transfer
Directory of Open Access Journals (Sweden)
Emilio Sassine
2017-12-01
Full Text Available The reliable estimation of buildings energy needs for cooling and heating is essential for any eventual thermal improvement of the envelope or the HVAC equipment. This paper presents an interesting method to evaluate the thermal performance of a massive wall by using the frequency-domain regression (FDR method to calculate CTF coefficients by means of the Fourier transform. The method is based on the EN ISO 13786 (2007 procedure by using the Taylor expansion for the elements of the heat matrix. Numerical results were validated through an experimental heating box with stochastic boundary conditions on one side of the wall representing real weather conditions and constant temperature profile on the other side representing the inside ambiance in real cases. Finally, a frequency analysis was performed in order to assess the validity and accuracy of the method used. The results show that development to the second order is sufficient to predict the thermal behavior of the studied massive wall in the range of frequencies encountered in the building applications (one hour time step. This method is useful for thermal transfer analysis in real weather conditions where the outside temperature is stochastic; it also allows the evaluation of the thermal performance of a wall through a frequency analysis.
Thermal conductivity of nanoscale thin nickel films
Institute of Scientific and Technical Information of China (English)
YUAN Shiping; JIANG Peixue
2005-01-01
The inhomogeneous non-equilibrium molecular dynamics (NEMD) scheme is applied to model phonon heat conduction in thin nickel films. The electronic contribution to the thermal conductivity of the film is deduced from the electrical conductivity through the use of the Wiedemann-Franz law. At the average temperature of T = 300 K, which is lower than the Debye temperature ()D = 450 K,the results show that in a film thickness range of about 1-11 nm, the calculated cross-plane thermal conductivity decreases almost linearly with the decreasing film thickness, exhibiting a remarkable reduction compared with the bulk value. The electrical and thermal conductivities are anisotropic in thin nickel films for the thickness under about 10 nm. The phonon mean free path is estimated and the size effect on the thermal conductivity is attributed to the reduction of the phonon mean free path according to the kinetic theory.
Kruis, Nathanael J. F.
Heat transfer from building foundations varies significantly in all three spatial dimensions and has important dynamic effects at all timescales, from one hour to several years. With the additional consideration of moisture transport, ground freezing, evapotranspiration, and other physical phenomena, the estimation of foundation heat transfer becomes increasingly sophisticated and computationally intensive to the point where accuracy must be compromised for reasonable computation time. The tools currently available to calculate foundation heat transfer are often either too limited in their capabilities to draw meaningful conclusions or too sophisticated to use in common practices. This work presents Kiva, a new foundation heat transfer computational framework. Kiva provides a flexible environment for testing different numerical schemes, initialization methods, spatial and temporal discretizations, and geometric approximations. Comparisons within this framework provide insight into the balance of computation speed and accuracy relative to highly detailed reference solutions. The accuracy and computational performance of six finite difference numerical schemes are verified against established IEA BESTEST test cases for slab-on-grade heat conduction. Of the schemes tested, the Alternating Direction Implicit (ADI) scheme demonstrates the best balance between accuracy, performance, and numerical stability. Kiva features four approaches of initializing soil temperatures for an annual simulation. A new accelerated initialization approach is shown to significantly reduce the required years of presimulation. Methods of approximating three-dimensional heat transfer within a representative two-dimensional context further improve computational performance. A new approximation called the boundary layer adjustment method is shown to improve accuracy over other established methods with a negligible increase in computation time. This method accounts for the reduced heat transfer
30 CFR 50.20-2 - Criteria-“Transfer to another job.”
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Criteria-âTransfer to another job.â 50.20-2 Section 50.20-2 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR ACCIDENTS..., Injuries, and Illnesses § 50.20-2 Criteria—“Transfer to another job.” “Transfer to another job” means...
Evaporative mass transfer behavior of a complex immiscible liquid.
McColl, Colleen M; Johnson, Gwynn R; Brusseau, Mark L
2008-09-01
A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult's law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium.
Study of coupled heat and mass transfer during absorption of ...
Indian Academy of Sciences (India)
(iii) The gas phase is ideal from thermodynamic point of view. (iv) Only mass transfer and no heat transfer takes place through the porous filter. (v) The thermal conductivity and specific heat of the hydride bed are assumed to be constant. This assumption underestimates the bed performance slightly, because in actual case ...
Heat Transfer Measurement and Modeling in Rigid High-Temperature Reusable Surface Insulation Tiles
Daryabeigi, Kamran; Knutson, Jeffrey R.; Cunnington, George R.
2011-01-01
Heat transfer in rigid reusable surface insulations was investigated. Steady-state thermal conductivity measurements in a vacuum were used to determine the combined contribution of radiation and solid conduction components of heat transfer. Thermal conductivity measurements at higher pressures were then used to estimate the effective insulation characteristic length for gas conduction modeling. The thermal conductivity of the insulation can then be estimated at any temperature and pressure in any gaseous media. The methodology was validated by comparing estimated thermal conductivities with published data on a rigid high-temperature silica reusable surface insulation tile. The methodology was also applied to the alumina enhanced thermal barrier tiles. Thermal contact resistance for thermal conductivity measurements on rigid tiles was also investigated. A technique was developed to effectively eliminate thermal contact resistance on the rigid tile s cold-side surface for the thermal conductivity measurements.
Effects of Schmidt number on near-wall turbulent mass transfer in pipe flow
Energy Technology Data Exchange (ETDEWEB)
Kang, Chang Woo; Yang, Kyung Soo [Inha University, Incheon (Korea, Republic of)
2014-12-15
Large Eddy simulation (LES) of turbulent mass transfer in circular-pipe flow has been performed to investigate the characteristics of turbulent mass transfer in the near-wall region. We consider a fully-developed turbulent pipe flow with a constant wall concentration. The Reynolds number under consideration is Re{sub r} = 500 based on the friction velocity and the pipe radius, and the selected Schmidt numbers (Sc) are 0.71, 5, 10, 20 and 100. Dynamic subgrid-scale (SGS) models for the turbulent SGS stresses and turbulent mass fluxes were employed to close the governing equations. The current paper reports a comprehensive characterization of turbulent mass transfer in circular-pipe flow, focusing on its near-wall characteristics and Sc dependency. We start with mean fields by presenting mean velocity and concentration profiles, mean Sherwood numbers and mean mass transfer coefficients for the selected values of the parameters. After that, we present the characteristics of fluctuations including root-mean-square (rms) profiles of velocity, concentration, and mass transfer coefficient fluctuations. Turbulent mass fluxes and correlations between velocity and concentration fluctuations are also discussed. The near-wall behaviour of turbulent diffusivity and turbulent Schmidt number is shown, and other authors' correlations on their limiting behaviour towards the pipe wall are evaluated based on our LES results. The intermittent characteristics of turbulent mass transfer in pipe flow are depicted by probability density functions (pdf) of velocity and concentration fluctuations; joint pdfs between them are also presented. Instantaneous snapshots of velocity and concentration fluctuations are shown to supplement our discussion on the turbulence statistics. Finally, we report the results of octant analysis and budget calculation of concentration variance to clarify Sc-dependency of the correlation between near-wall turbulence structures and concentration fluctuation in
Effects of Schmidt number on near-wall turbulent mass transfer in pipe flow
International Nuclear Information System (INIS)
Kang, Chang Woo; Yang, Kyung Soo
2014-01-01
Large Eddy simulation (LES) of turbulent mass transfer in circular-pipe flow has been performed to investigate the characteristics of turbulent mass transfer in the near-wall region. We consider a fully-developed turbulent pipe flow with a constant wall concentration. The Reynolds number under consideration is Re r = 500 based on the friction velocity and the pipe radius, and the selected Schmidt numbers (Sc) are 0.71, 5, 10, 20 and 100. Dynamic subgrid-scale (SGS) models for the turbulent SGS stresses and turbulent mass fluxes were employed to close the governing equations. The current paper reports a comprehensive characterization of turbulent mass transfer in circular-pipe flow, focusing on its near-wall characteristics and Sc dependency. We start with mean fields by presenting mean velocity and concentration profiles, mean Sherwood numbers and mean mass transfer coefficients for the selected values of the parameters. After that, we present the characteristics of fluctuations including root-mean-square (rms) profiles of velocity, concentration, and mass transfer coefficient fluctuations. Turbulent mass fluxes and correlations between velocity and concentration fluctuations are also discussed. The near-wall behaviour of turbulent diffusivity and turbulent Schmidt number is shown, and other authors' correlations on their limiting behaviour towards the pipe wall are evaluated based on our LES results. The intermittent characteristics of turbulent mass transfer in pipe flow are depicted by probability density functions (pdf) of velocity and concentration fluctuations; joint pdfs between them are also presented. Instantaneous snapshots of velocity and concentration fluctuations are shown to supplement our discussion on the turbulence statistics. Finally, we report the results of octant analysis and budget calculation of concentration variance to clarify Sc-dependency of the correlation between near-wall turbulence structures and concentration fluctuation in the
Gap conductance in Zircaloy-clad LWR fuel rods
International Nuclear Information System (INIS)
Ainscough, J.B.
1982-04-01
This report describes the procedures currently used to calculate fuel-cladding gap conductance in light water reactor fuel rods containing pelleted UO 2 in Zircaloy cladding, under both steady-state and transient conditions. The relevant theory is discussed together with some of the approximations usually made in performance modelling codes. The state of the physical property data which are needed for heat transfer calculations is examined and some of the relevant in- and out-of-reactor experimental work on fuel rod conductance is reviewed
Origin of low thermal conductivity in nuclear fuels.
Yin, Quan; Savrasov, Sergey Y
2008-06-06
Using a novel many-body approach, we report lattice dynamical properties of UO2 and PuO2 and uncover various contributions to their thermal conductivities. Via calculated Grüneisen constants, we show that only longitudinal acoustic modes having large phonon group velocities are efficient heat carriers. Despite the fact that some optical modes also show their velocities which are extremely large, they do not participate in the heat transfer due to their unusual anharmonicity. Ways to improve thermal conductivity in these materials are discussed.
International Nuclear Information System (INIS)
Kim, Ji Hoon; Ahn, Ho Seon; Kim, Ji Min
2016-01-01
Recently, graphene, carbon in two dimensions, were highlighted as a good heat transfer materials, according to its high thermal conductivity. Lateral conduction and water absorption into the structure helped graphene films to inhibit the formation of hot spots, which means increasing of critical heat flux (CHF) and boiling heat transfer coefficient (BHTC) performances. In this study, we report a promising increase of CHF and BHTC results with 2D graphene films. Furthermore, we tried to observe bubble behavior via high-speed visualization to investigate a relationship between bubble behavior and pool boiling performances in downward facing boiling. The effect of graphene film coating on the pool boiling performances of upward and downward facing heater surface were examined. 2D- and 3D- graphene film showed good enhancement results on the CHF (by 111% and 60%) and BHTC (by 40% and 20-25%) performances. Bubble behavior change was significant factor on the CHF and BHTC performances in downward facing boiling. The amount of evaporation heat flux was calculated from the velocity, bubble diameter, frequency, orientation angle and superheat that the post-products of the high-speed visualization
Network type sp3 boron-based single-ion conducting polymer electrolytes for lithium ion batteries
Deng, Kuirong; Wang, Shuanjin; Ren, Shan; Han, Dongmei; Xiao, Min; Meng, Yuezhong
2017-08-01
Electrolytes play a vital role in modulating lithium ion battery performance. An outstanding electrolyte should possess both high ionic conductivity and unity lithium ion transference number. Here, we present a facile method to fabricate a network type sp3 boron-based single-ion conducting polymer electrolyte (SIPE) with high ionic conductivity and lithium ion transference number approaching unity. The SIPE was synthesized by coupling of lithium bis(allylmalonato)borate (LiBAMB) and pentaerythritol tetrakis(2-mercaptoacetate) (PETMP) via one-step photoinitiated in situ thiol-ene click reaction in plasticizers. Influence of kinds and content of plasticizers was investigated and the optimized electrolytes show both outstanding ionic conductivity (1.47 × 10-3 S cm-1 at 25 °C) and high lithium transference number of 0.89. This ionic conductivity is among the highest ionic conductivity exhibited by SIPEs reported to date. Its electrochemical stability window is up to 5.2 V. More importantly, Li/LiFePO4 cells with the prepared single-ion conducting electrolytes as the electrolyte as well as the separator display highly reversible capacity and excellent rate capacity under room temperature. It also demonstrates excellent long-term stability and reliability as it maintains capacity of 124 mA h g-1 at 1 C rate even after 500 cycles without obvious decay.
Kedia, Kushal S.
2013-01-01
The dynamic response of a premixed flame stabilized on a heat-conducting perforated plate depends critically on their coupled thermal interaction. The objective of this paper is to develop an analytical model to capture this coupling. The model predicts the mean flame base standoff distance; the flame base area, curvature and speed; and the burner plate temperature given the operating conditions; the mean velocity, temperature and equivalence ratio of the reactants; thermal conductivity and the perforation ratio of the burner. This coupled model is combined with our flame transfer function (FTF) model to predict the dynamic response of the flame to velocity perturbations. We show that modeling the thermal coupling between the flame and the burner, while accounting for the two-dimensionality of the former, is critical to predicting the dynamic response characteristics such as the overshoot in the gain curve (resonant condition) and the phase delay. Good agreement with the numerical and experimental results is demonstrated over a range of conditions. © 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Haddad, Zoubida; Abu-Nada, Eiyad; Oztop, Hakan F.; Mataoui, Amina
2012-01-01
Natural convection heat transfer and fluid flow of CuO-Water nano-fluids is studied using the Rayleigh-Benard problem. A two component non-homogenous equilibrium model is used for the nano-fluid that incorporates the effects of Brownian motion and thermophoresis. Variable thermal conductivity and variable viscosity are taken into account in this work. Finite volume method is used to solve governing equations. Results are presented by streamlines, isotherms, nano-particle distribution, local and mean Nusselt numbers and nano-particle profiles at top and bottom side. Comparison of two cases as absence of Brownian and thermophoresis effects and presence of Brownian and thermophoresis effects showed that higher heat transfer is formed with the presence of Brownian and thermophoresis effect. In general, by considering the role of thermophoresis and Brownian motion, an enhancement in heat transfer is observed at any volume fraction of nano-particles. However, the enhancement is more pronounced at low volume fraction of nano-particles and the heat transfer decreases by increasing nano-particle volume fraction. On the other hand, by neglecting the role of thermophoresis and Brownian motion, deterioration in heat transfer is observed and this deterioration elevates by increasing the volume fraction of nano-particles. (authors)
Laser induced forward transfer of SnO2 for sensing applications using different precursors systems
Mattle, Thomas; Hintennach, Andreas; Lippert, Thomas; Wokaun, Alexander
2013-02-01
This paper presents the transfer of SnO2 by laser induced forward transfer (LIFT) for gas sensor applications. Different donor substrates of SnO2 with and without triazene polymer (TP) as a dynamic release layer were prepared. Transferring these films under different conditions were evaluated by optical microscopy and functionality. Transfers of sputtered SnO2 films do not lead to satisfactory results and transfers of SnO2 nanoparticles are difficult. Transfers of SnO2 nanoparticles can only be achieved when applying a second laser pulse to the already transferred material, which improves the adhesion resulting in a complete pixel. A new approach of decomposing the transfer material during LIFT transfer was developed. Donor films based on UV absorbing metal complex precursors namely, SnCl2(acac)2 were prepared and transferred using the LIFT technique. Transfer conditions were optimized for the different systems, which were deposited onto sensor-like microstructures. The conductivity of the transferred material at temperatures of about 400 ∘C are in a range usable for SnO2 gas sensors. First sensing tests were carried out and the transferred material proved to change conductivity when exposed to ethanol, acetone, and methane.
Electrothermal efﬁciency, temperature and thermal conductivity
Indian Academy of Sciences (India)
A study was made to evaluate the electrothermal efﬁciency of a DC arc plasma torch and temperature and thermal conductivity of plasma jet in the torch. The torch was operated at power levels from 4 to 20 kW in non-transferred arc mode. The effect of nitrogen in combination with argon as plasma gas on the above ...
Wang, Yongjiang; Niu, Wenjuan; Ai, Ping
2016-12-01
Dynamic estimation of heat transfer through composting reactor wall was crucial for insulating design and maintaining a sanitary temperature. A model, incorporating conductive, convective and radiative heat transfer mechanisms, was developed in this paper to provide thermal resistance calculations for composting reactor wall. The mechanism of thermal transfer from compost to inner surface of structural layer, as a first step of heat loss, was important for improving insulation performance, which was divided into conduction and convection and discussed specifically in this study. It was found decreasing conductive resistance was responsible for the drop of insulation between compost and reactor wall. Increasing compost porosity or manufacturing a curved surface, decreasing the contact area of compost and the reactor wall, might improve the insulation performance. Upon modeling of heat transfers from compost to ambient environment, the study yielded a condensed and simplified model that could be used to conduct thermal resistance analysis for composting reactor. With theoretical derivations and a case application, the model was applicable for both dynamic estimation and typical composting scenario. Copyright © 2016 Elsevier Ltd. All rights reserved.
KSC Tech Transfer News, Volume 5, No. 1
Buckingham, Bruce (Editor)
2012-01-01
In October 2011, the White House released a presidential memorandum titled "Accelerating Technology Transfer and Commercialization of Federal Research in Support of High-Growth Businesses." It emphasized the importance of technology transfer as a driver of successful innovation to fuel economic growth, create jobs, and make U.S. industries more competitive in a global market. In response to this memorandum, NASA developed a 5-year plan for accelerating its own technology transfer activities. This plan outlines key objectives for enhancing NASA's ability to increase the rate, volume, and quality of technology transfers to industry, academia, and other Government agencies. By doing so, we are increasing the economic impact and public benefit of Federal technology investments. In addition, NASA established technology transfer as a key element of one of its Agency High Priority Performance Goals: "Enable bold new missions and make new technologies available to Government agencies and U.S. industry."What does this mean to you? In the broadest sense, NASA defines technology transfer as the utilization of NASA's technological assets- technologies, innovations, unique facilities and equipment, and technical expertise- by public and private sectors to benefit the Nation. So, if your job involves developing new technologies, writing new software, creating innovative ways to do business, performing research, or developing new technical capabilities, you could be contributing to Kennedy Space Center's (KSC) technology transfer activities by creating the technological assets that may one day be used by external partners. Furthermore, anytime you provide technical expertise to external partners, you're participating in technology transfer. The single most important step you can take to support the technology transfer process is to report new technologies and innovations ro the Technology Transfer Office. This is the critical first step in fueling the technology transfer pipeline
Improvement Method of Gene Transfer in Kappaphycus Alvarezii
Triana, St. Hidayah; Alimuddin,; Widyastuti, Utut; Suharsono,; Suryati, Emma; Parenrengi, Andi
2016-01-01
Method of foreign gene transfer in red seaweed Kappaphycus alvarezii has been reported, however, li-mited number of transgenic F0 (broodstock) was obtained. This study was conducted to improve the method of gene transfer mediated by Agrobacterium tumefaciens in order to obtain high percentage of K. alvarezii transgenic. Superoxide dismutase gene from Melastoma malabatrichum (MmCu/Zn-SOD) was used as model towards increasing adaptability of K. alvarezii to environmental stress. The treat-ment...
Controlling Thermal Conduction by Graded Materials
Ji, Qin; Huang, Ji-Ping
2018-04-01
Manipulating thermal conductivities are fundamentally important for controlling the conduction of heat at will. Thermal cloaks and concentrators, which have been extensively studied recently, are actually graded materials designed according to coordinate transformation approaches, and their effective thermal conductivity is equal to that of the host medium outside the cloak or concentrator. Here we attempt to investigate a more general problem: what is the effective thermal conductivity of graded materials? In particular, we perform a first-principles approach to the analytic exact results of effective thermal conductivities of materials possessing either power-law or linear gradation profiles. On the other hand, by solving Laplace’s equation, we derive a differential equation for calculating the effective thermal conductivity of a material whose thermal conductivity varies along the radius with arbitrary gradation profiles. The two methods agree with each other for both external and internal heat sources, as confirmed by simulation and experiment. This work provides different methods for designing new thermal metamaterials (including thermal cloaks and concentrators), in order to control or manipulate the transfer of heat. Support by the National Natural Science Foundation of China under Grant No. 11725521, by the Science and Technology Commission of Shanghai Municipality under Grant No. 16ZR1445100
Mass and charge transfer within a floating water bridge
Fuchs, Elmar C.; Agostinho, Luewton L. F.; Eisenhut, Mathias; Woisetschläger, Jakob
2010-11-01
When high voltage is applied to pure water filled into two beakers close to each other, a connection forms spontaneously, giving the impression of a floating water bridge 1-8. This phenomenon is of special interest, since it comprises a number of phenomena currently tackled in modern water science. In this work, the charge and mass transfer through the water bridge are investigated with schlieren visualization and laser interferometry. It can be shown that the addition of a pH dye increases the H+ and OH- production with subsequent electrolysis, whereas schlieren and interferometric methods reveal another mechanism where charge and mass transfer appear to be coupled. Whereas this mechanism seems to be responsible for the electrolysis-less charge and mass transfer in the water bridge, it is increasingly superseded by the electrochemical mechanism with rising conductivity. Thus it can be shown that a pH dye does only indirectly visualize the charge transfer in the water bridge since it is dragged along with the water flow like any other dye, and additionally promotes conventional electrochemical conduction mechanisms, thereby enhancing electrolysis and reducing the masscoupled charge transport and thus destabilizing the bridge.
Non-linear heat transfer computer code by finite element method
International Nuclear Information System (INIS)
Nagato, Kotaro; Takikawa, Noboru
1977-01-01
The computer code THETA-2D for the calculation of temperature distribution by the two-dimensional finite element method was made for the analysis of heat transfer in a high temperature structure. Numerical experiment was performed for the numerical integration of the differential equation of heat conduction. The Runge-Kutta method of the numerical experiment produced an unstable solution. A stable solution was obtained by the β method with the β value of 0.35. In high temperature structures, the radiative heat transfer can not be neglected. To introduce a term of the radiative heat transfer, a functional neglecting the radiative heat transfer was derived at first. Then, the radiative term was added after the discretion by variation method. Five model calculations were carried out by the computer code. Calculation of steady heat conduction was performed. When estimated initial temperature is 1,000 degree C, reasonable heat blance was obtained. In case of steady-unsteady temperature calculation, the time integral by THETA-2D turned out to be under-estimation for enthalpy change. With a one-dimensional model, the temperature distribution in a structure, in which heat conductivity is dependent on temperature, was calculated. Calculation with a model which has a void inside was performed. Finally, model calculation for a complex system was carried out. (Kato, T.)
International Nuclear Information System (INIS)
Vasiliev, A.D.; Kobelev, G.V.; Astafieva, V.O.
2007-01-01
Radiative heat transfer is very important in different fields of mechanical engineering and related technologies including nuclear reactors, heat transfer in furnaces, aerospace, different high-temperature assemblies. In particular, in the course of a hypothetical severe accident at PWR-type nuclear reactor the temperatures inside the reactor vessel reach high values at which taking into account of radiative heat exchange between the structures of reactor (including core and other reactor vessel elements) gets important. Radiative heat transfer dominates the late phase of severe accident because radiative heat fluxes (proportional to T4, where T is the temperature) are generally considerably higher than convective and conductive heat fluxes in a system. In particular, heat transfer due to radiation determines the heating and degradation of the core and surrounding steel in-vessel structures and finally influences the composition, temperature and mass of materials pouring out of the reactor vessel after its loss of integrity. Existing models of radiative heat exchange use many limitations and approximations: approximate estimation of view factors and beam lengths; the geometry change in the course of the accident is neglected; the database for emissivities of materials is not complete; absorption/emission by steam-noncondensable medium is taken into account approximately. The module MRAD was developed in this paper to model the radiative heat exchange in rod-like geometry typical of PWR-type reactor. Radiative heat exchange is computed using dividing on zones (zonal method) as in existing radiation models implemented to severe accident numerical codes such as ICARE, SCDAP/RELAP, MELCOR but improved in following aspects: new approach to evaluation of view factors and mean beam length; detailed evaluation of gas absorptivity and emissivity; account of effective radiative thermal conductivity for the large core; account of geometry modification in the course of severe
Study of Heat Transfer Characteristics of Nanofluids in an Automotive Radiator
Harsh, R.; Srivastav, Hitish; Balakrishnan, Prabhat; Saini, Vivek; Senthil Kumar, D.; Rajni, K. S.; Thirumalini, S.
2018-02-01
This paper presents an experimental study on heat transfer using nanofluid as coolants in engines. Previous studies shows that Al2O3 is found to be more effective in heat transfer due to its high conductive property which is found to increase with concentration. Particles having diameter in the range 10-3 to 10-6 m have low thermal conductivities and cause clogging in the flow section along with significant friction and are highly unstable in solution. Nanoparticles on the other hand are easily dispersed and cause minimal clogging or friction in the flow. In the present work, ethylene glycol-water solution is taken as a base fluid for nanoparticle dispersion. The ratio of water to ethylene glycol used is 80:20 and it has been noted out that heat conduction improved with increasing fraction of ethylene glycol. The experiments were conducted with flow rate of 4,5,6 and 7 L/min and the air flow rate inside the duct was kept constant at 4.9 m/s. The temperature of water in the reservoir is kept at 70°C. The nanoparticles used in this experiment are Cu and TiO2 having particle size less than 80nm. Result shows that there is an improvement of 24.5% in the overall heat transfer coefficient and there was also an increase of 13.9% in the heat transfer rate compared to the base fluid (80:20 Water: EG solution).
Radiocaesium transfer to man from moose and roe deer in Sweden
International Nuclear Information System (INIS)
Johanson, Karl J.; Bergstroem, R.
1994-01-01
Studies of radiocaesium in the forest ecosystems in Sweden resulted in aggregated transfer factors quantified for the transfer of 137 Cs from soil to moose and roe deer. These aggregated transfer factors were 0.02 m 2 kg -1 for moose and 0.05 m 2 kg -1 for roe deer. There seems to be no decrease in the 137 Cs activity concentrations in moose harvested in our research area and therefore we suggest the use of the physical half-life of 137 Cs (30 years) as the effective ecological half-life. The time-integrated transfer of 137 Cs from the Chernobyl fall-out to man by moose in Sweden was calculated and found to be 115 GBq, corresponding to 1500 man Sv for moose. The time-integrated transfer by roe deer to man was estimated to be between 25-48 GBq, corresponding to 327-620 man Sv for roe deer. The annual transfer of 137 Cs to man by moose has varied between 2.0-2.7 GBq, corresponding to 27-34 man Sv. Depending on the group studied, the mean annual transfer of 137 Cs can be calculated to be from about 250 to 43'000 Bq. For example, the mean annual transfer of 137 Cs by moose to hunters and their families in Gaevle commune, the most affected commune in Sweden, was estimated to be about 26'000 Bq, corresponding to 0.34 mSv
Johnson, Alexander; Brace, Christopher
2015-01-01
Interventional oncology procedures such as thermal ablation are becoming widely used for many tumours in the liver, kidney and lung. Thermal ablation refers to the focal destruction of tissue by generating cytotoxic temperatures in the treatment zone. Hydrodissection - separating tissues with fluids - protects healthy tissues adjacent to the ablation treatment zone to improve procedural safety, and facilitate more aggressive power application or applicator placement. However, fluids such as normal saline and 5% dextrose in water (D5W) can migrate into the peritoneum, reducing their protective efficacy. As an alternative, a thermo-gelable poloxamer 407 (P407) solution has been recently developed to facilitate hydrodissection procedures. We hypothesise that the P407 gel material does not provide convective heat dissipation from the ablation site, and therefore may alter the heat transfer dynamics compared to liquid materials during hydrodissection-assisted thermal ablation. The purpose of this study was to investigate the heat dissipation mechanics within D5W, liquid P407 and gel P407 hydrodissection barriers. Overall it was shown that the gel P407 dissipated heat primarily through conduction, whereas the liquid P407 and D5W dissipated heat through convection. Furthermore, the rate of temperature change within the gel P407 was greater than liquid P407 and D5W. Testing to evaluate the in vivo efficacy of the fluids with different modes of heat dissipation seems warranted for further study.
Heat transfer studies in pool fire environment
International Nuclear Information System (INIS)
Nitsche, F.
1993-01-01
A Type B package has to withstand severe thermal accident conditions. To calculate the temperature behaviour of such a package in a real fire environment, heat transfer parameters simulating the effect of the fire are needed. For studying such heat transfer parameters, a systematic programme of experimental and theoretical investigations was performed which was part of the IAEA Coordinated Research Programme (Nitsche and Weib 1990). The studies were done by means of small, unfinned and finned, steel model containers of simplified design in hydrocarbon fuel open fire tests. By using various methods, flame and container temperatures were measured and also container surface absorptivity before and after the test to study the effect of sooting and surface painting on heat transfer. Based on all these experimental data and comparative calculations, simplified, effective heat transfer parameters could be derived, simulating the effect of the real fire on the model containers. (J.P.N.)
Soluble pig for radioactive waste transfer lines
International Nuclear Information System (INIS)
Ohl, P.C.; Pezeshki, C.
1997-01-01
Flushing transfer pipe after radioactive waste transfers generates thousands of gallons of additional radioactive waste each year at the Hanford site. The use of pneumatic pigging with waste soluble pigs as a means to clear transfer piping may be an effective alternative to raw water flushes. A feasibility study was performed by a group of senior mechanical engineering students for their senior design project as part of their curriculum at Washington State University. The students divided the feasibility study into three sub-projects involving: (1) material research, (2) delivery system design, and (3) mockup fabrication and testing. The students screened through twenty-three candidate materials and selected a thermoplastic polymer combined 50:50 wt% with sucrose to meet the established material performance criteria. The students also prepared a conceptual design of a remote pneumatic delivery system and constructed a mockup section of transfer pipe for testing the prototype pigs
What Makes Urban Transportation Efficient? Evidence from Subway Transfer Stations in Korea
Directory of Open Access Journals (Sweden)
Changhee Kim
2017-11-01
Full Text Available Subway stations have been proliferating underneath cosmopolitan metropolises with subway lines forming complex webs connected in strategic transfer stations. The efficiency of the subway system thus heavily weighs on the efficiency at these transfer stations. However, few studies have been conducted on transfer efficiency at transfer stations due to the complexities involved. As the first study of its kind in the subway context, we analyze the transfer efficiency of the subway transfer stations in Seoul, one of the megacities in the world, and demonstrate how transfer efficiency can be analyzed using bootstrap-based DEA technique. Based on the results, we discuss the reasons behind the inefficiency of subway transfer stations and possible ways to improve them into efficient decision-making units.
Directory of Open Access Journals (Sweden)
Yehui Cui
2018-06-01
Full Text Available In this work a three-dimensional (3D hydrogen absorption model was proposed to study the heat transfer behavior in thin double-layered annular ZrCo beds. Numerical simulations were performed to investigate the effects of conversion layer thickness, thermal conductivity, cooling medium and its flow velocity on the efficiency of heat transfer. Results reveal that decreasing the layer thickness and improving the thermal conductivity enhance the ability of heat transfer. Compared with nitrogen and helium, water appears to be a better medium for cooling. In order to achieve the best efficiency of heat transfer, the flow velocity needs to be maximized. Keywords: Hydrogen storage, ZrCo metal hydride, Heat transfer, Three-dimensional simulation
Human somatic cell nuclear transfer and cloning.
2012-10-01
This document presents arguments that conclude that it is unethical to use somatic cell nuclear transfer (SCNT) for infertility treatment due to concerns about safety; the unknown impact of SCNT on children, families, and society; and the availability of other ethically acceptable means of assisted reproduction. This document replaces the ASRM Ethics Committee report titled, "Human somatic cell nuclear transfer (cloning)," last published in Fertil Steril 2000;74:873-6. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.
Surgical anatomy of latissimus dorsi muscle in transfers about the shoulder.
Goldberg, Benjamin A; Elhassan, Bassem; Marciniak, Steven; Dunn, Jonathan H
2009-03-01
Transfer of the latissimus dorsi to the greater tuberosity has been used successfully in the treatment of massive rotator-cuff deficiency. For safe release and transfer of the tendon, the variations in the tendinous insertions of the latissimus dorsi and teres major onto the humerus need to be understood. In anatomical dissection of 12 cadavers, mean width of the latissimus tendon was 3.3 cm at its insertion, and mean length was 7.3 cm. In all specimens, there were fascial connections between the latissimus and teres major and between the latissimus and the long head of the triceps. There were 3 insertion patterns of the latissimus dorsi tendon onto the humerus with respect to the tendon of the teres major: completely separate (8 cadavers), loosely bound (3 cadavers), and completely joined (1 cadaver). If the latissimus dorsi were being transferred in the last type, the teres major would need to be transferred with the latissimus dorsi as a common musculotendinous unit.
CFD simulation of simultaneous monotonic cooling and surface heat transfer coefficient
International Nuclear Information System (INIS)
Mihálka, Peter; Matiašovský, Peter
2016-01-01
The monotonic heating regime method for determination of thermal diffusivity is based on the analysis of an unsteady-state (stabilised) thermal process characterised by an independence of the space-time temperature distribution on initial conditions. At the first kind of the monotonic regime a sample of simple geometry is heated / cooled at constant ambient temperature. The determination of thermal diffusivity requires the determination rate of a temperature change and simultaneous determination of the first eigenvalue. According to a characteristic equation the first eigenvalue is a function of the Biot number defined by a surface heat transfer coefficient and thermal conductivity of an analysed material. Knowing the surface heat transfer coefficient and the first eigenvalue the thermal conductivity can be determined. The surface heat transport coefficient during the monotonic regime can be determined by the continuous measurement of long-wave radiation heat flow and the photoelectric measurement of the air refractive index gradient in a boundary layer. CFD simulation of the cooling process was carried out to analyse local convective and radiative heat transfer coefficients more in detail. Influence of ambient air flow was analysed. The obtained eigenvalues and corresponding surface heat transfer coefficient values enable to determine thermal conductivity of the analysed specimen together with its thermal diffusivity during a monotonic heating regime.
A CONCEPTUAL MODEL OF ASSESSMENT OF KNOWLEDGE TRANSFER TO CONSUMER
Directory of Open Access Journals (Sweden)
Jurgita Raudeliūnienė
2017-12-01
Full Text Available Due to changing needs of knowledge consumers in the context of globalization organizations find it important to search out the way of effective application of the process of knowledge sharing and distribution in their activity in order to create and/or select proper means of communication with consumers on purpose of effective satisfaction of their knowledge needs. In order to address the problems of such nature it is important to assess the process of knowledge transfer and consumer purchase, knowledge needs, knowledge transferred to meet of consumer needs, channels and means of knowledge transfer. Also, to select purposefully channels of communication with consumers and tools of e-marketing that are suitable for satisfaction of consumer needs, i.e. channels and tools that affect self-determination of consumer to take a decision to acquire a product or service of specific organization.
DEFF Research Database (Denmark)
Cui, Xiaoti; Kær, Søren Knudsen
2018-01-01
Monolithic catalysts have received increasing attention for application in the small-scale steam methane reforming process. The radial heat transfer behaviors of monolith reformers were analyzed by two-dimensional computational fluid dynamic (CFD) modeling. A parameter study was conducted...... by a large number of simulations focusing on the thermal conductivity of the monolith substrate, washcoat layer, wall gap, radiation heat transfer and the geometric parameters (cell density, porosity and diameter of monolith). The effective radial thermal conductivity of the monolith structure, kr......,eff, showed good agreement with predictions made by the pseudo-continuous symmetric model. This influence of the radiation heat transfer is low for highly conductive monoliths. A simplified model has been developed to evaluate the importance of radiation for monolithic reformers under different conditions...
Thermophysical Properties of Nanoparticle-Enhanced Ionic Liquids (NEILs) Heat-Transfer Fluids
Energy Technology Data Exchange (ETDEWEB)
Fox, Elise B.; Visser, Ann E.; Bridges, Nicholas J.; Amoroso, Jake W.
2013-06-20
An experimental investigation was completed on nanoparticle enhanced ionic liquid heat transfer fluids as an alternative to conventional organic based heat transfer fluids (HTFs). These nanoparticle-based HTFs have the potential to deliver higher thermal conductivity than the base fluid without a significant increase in viscosity at elevated temperatures. The effect of nanoparticle morphology and chemistry on thermophysical properties was examined. Whisker shaped nanomaterials were found to have the largest thermal conductivity temperature dependence and were also less likely to agglomerate in the base fluid than spherical shaped nanomaterials.
PRAGMATIC TRANSFER IN REQUEST REALIZATIONS
Directory of Open Access Journals (Sweden)
Indawan Syahri
2007-01-01
Full Text Available This study investigates the pragmatic transfer in English request realizations made by EFL learners, i.e. the proficient learners. The subjects were students of an English Study Program who obtained TOEFL-like scores of at least 450. The data were collected by means of DCT-questionnaires and Role-plays. The results show that the subjects realize requests in the form of external modifications more frequently. Most of them embed their requests with supportive moves dominantly. They enfold the acts with the moves before, after or in both positions. Of the three positions, they mostly insert the moves initial position, i.e., through inductive patterns. This is due to pragmatic transfer.
Cui, Yehui; Zeng, Xiangguo; Kou, Huaqin; Ding, Jun; Wang, Fang
2018-06-01
In this work a three-dimensional (3D) hydrogen absorption model was proposed to study the heat transfer behavior in thin double-layered annular ZrCo beds. Numerical simulations were performed to investigate the effects of conversion layer thickness, thermal conductivity, cooling medium and its flow velocity on the efficiency of heat transfer. Results reveal that decreasing the layer thickness and improving the thermal conductivity enhance the ability of heat transfer. Compared with nitrogen and helium, water appears to be a better medium for cooling. In order to achieve the best efficiency of heat transfer, the flow velocity needs to be maximized.
Yeung, P. K.; Sreenivasan, K. R.
2014-01-01
In a recent direct numerical simulation (DNS) study [P. K. Yeung and K. R. Sreenivasan, "Spectrum of passive scalars of high molecular diffusivity in turbulent mixing," J. Fluid Mech. 716, R14 (2013)] with Schmidt number as low as 1/2048, we verified the essential physical content of the theory of Batchelor, Howells, and Townsend ["Small-scale variation of convected quantities like temperature in turbulent fluid. 2. The case of large conductivity," J. Fluid Mech. 5, 134 (1959)] for turbulent passive scalar fields with very strong diffusivity, decaying in the absence of any production mechanism. In particular, we confirmed the existence of the -17/3 power of the scalar spectral density in the so-called inertial-diffusive range. In the present paper, we consider the DNS of the same problem, but in the presence of a uniform mean gradient, which leads to the production of scalar fluctuations at (primarily) the large scales. For the parameters of the simulations, the presence of the mean gradient alters the physics of mixing fundamentally at low Peclet numbers. While the spectrum still follows a -17/3 power law in the inertial-diffusive range, the pre-factor is non-universal and depends on the magnitude of the mean scalar gradient. Spectral transfer is greatly reduced in comparison with those for moderately and weakly diffusive scalars, leading to several distinctive features such as the absence of dissipative anomaly and a new balance of terms in the spectral transfer equation for the scalar variance, differing from the case of zero gradient. We use the DNS results to present an alternative explanation for the observed scaling behavior, and discuss a few spectral characteristics in detail.
A heat transfer analysis of the CCI experiments 1-3
International Nuclear Information System (INIS)
Sevon, Tuomo
2008-01-01
This paper presents an attempt to evaluate the heat transfer rates and gas release rates in the CCI core-concrete interaction experiments 1-3, performed within the OECD MCCI project. A new method for calculating the heat transfer rates has been developed. It is based on calculating integrals of the concrete enthalpies with the help of piecewise exponential interpolation curves. The new method takes into account heat conduction in the concrete. Compared to traditional methods, the new method gives better results during slow concrete ablation, and its time resolution is significantly better. The gas release rates from the concrete were also calculated. A regression analysis was conducted for the heat transfer coefficients and gas release rates. Three correlations for the bubbling-enhanced heat transfer were developed. For the basemat, a single correlation can be used for both siliceous and limestone/common sand (LCS) concrete types. For the sidewall, two different correlations are needed for the two concrete types. With the same superficial gas velocity, the heat transfer rate to siliceous sidewalls is higher than to LCS sidewalls. This suggests that the reason for the different radial ablation rates of the concrete types observed in the tests is not the lower gas content of siliceous concrete
Updated heat transfer correlations for supercritical water-cooled reactor applications
International Nuclear Information System (INIS)
Mokry, S.J.; Pioro, I.L.; Farah, A.; King, K.
2011-01-01
In support of the development of SuperCritical Water-cooled Reactors (SCWRs), research is currently being conducted for heat-transfer at supercritical conditions. Currently, there are no experimental datasets for heat transfer from power reactor fuel bundles to the fuel coolant (Water) available in open literature. Therefore, for preliminary calculations, heat-transfer correlations obtained with bare tube data can be used as a conservative approach. A large set of experimental data, for supercritical water was analyzed and an updated heat-transfer correlation for forced-convective heat-transfer, in the normal heat transfer regime, was developed. This experimental dataset was obtained within conditions similar to those for proposed SCWR concepts. Thus, this new correlation can be used for preliminary heat-transfer calculations in SCWR fuel channels. It has demonstrated a good fit for the analyzed dataset. Experiments with SuperCritical Water (SCW) are very expensive. Therefore, a number of experiments are performed in modeling fluids, such as carbon dioxide and refrigerants. However, there is no common opinion if SC modeling fluids' correlations can be applied to SCW and vice versa. Therefore, a correlation for supercritical carbon dioxide heat transfer was developed as a less expensive alternative to using supercritical water. The conducted analysis also meets the objective of improving our fundamental knowledge of the transport processes and handling of supercritical fluids. These correlations can be used for supercritical water heat exchangers linked to indirect-cycle concepts and the cogeneration of hydrogen, for future comparisons with other independent datasets, with bundle data, for the verification of computer codes for SCWR core thermalhydraulics and for the verification of scaling parameters between water and modeling fluids. (author)
Mass-transfer characterization in a parallel-plate electrochemical reactor with convergent flow
International Nuclear Information System (INIS)
Colli, A.N.; Bisang, J.M.
2013-01-01
Highlights: • A convergent laminar flow enhances and becomes more uniform the mass-transfer rate. • The mass-transfer rate is increased under convergent turbulent flow conditions. • The mass-transfer rate under convergent laminar flow can be theoretically predicted. • A convergent duct improves the reactor behaviour and the concept is easily applicable. -- Abstract: A continuous reduction in the cross-section area is analysed as a means of improving mass-transfer in a parallel-plate electrochemical reactor. Experimental local mass-transfer coefficients along the electrode length are reported for different values of the convergent ratio and Reynolds numbers, using the reduction of ferricyanide as a test reaction. The Reynolds numbers evaluated at the reactor inlet range from 85 to 4600 with interelectrode gaps of 2 and 4 mm. The convergent flow improves the mean mass-transfer coefficient by 10–60% and mass-transfer distribution under laminar flow conditions becomes more uniform. The experimental data under laminar flow conditions are compared with theoretical calculations obtained by a computational fluid dynamics software and also with an analytical simplified model. A suitable agreement is observed between both theoretical treatments and with the experimental results. The pressure drop across the reactor is reported and compared with theoretical predictions
Improved coupling of the conduction and flow equations in TRAC
International Nuclear Information System (INIS)
Addessio, F.L.
1981-01-01
Recent nuclear-reactor-systems modeling efforts have been directed toward the development of computer codes capable of simulating transients in short computational times. For this reason, a stability enhancing two-stem method (SETS) has been applied to the two-phase flow equations in the Transient Reactor Analysis Code (TRAC) allowing the Courant limit to be violated. Unfortunately, the coupling between the wall conduction equation and the fluid-dynamics equations is performed semi-implicitly, that is, the wall-heat transfer term, is evaluated using old-time heat-transfer coefficients and wall temperatures and new-time coolant temperatures. This coupling may lead to numerical instabilities at large time steps because of large variations in the heat-transfer coefficient in certain regimes of the boiling curve. Consequently, simply using new-time wall temperatures is not sufficient. A technique that also incorporates new-time heat-transfer coefficients must be used
Electrolytic conductivity-the hopping mechanism of the proton and beyond
International Nuclear Information System (INIS)
Gileadi, E.; Kirowa-Eisner, E.
2006-01-01
The hopping mechanism of electrolytic conductivity is analyzed, employing mixtures of two solvents: one that sustains the hopping mechanism and the other that does not inhibit it directly, but interferes with it by diluting the solvent that sustains hopping. Measurement of the equivalent conductivity shows that the excess proton conductivities of H 3 O + and OH - increases with increasing temperature, although the number of hydrogen bonds is known to decrease. In mixtures of acetonitrile with water, proton hopping does not start until a threshold concentration of about 20 vol.% water has been reached, while no such threshold concentration is observed upon addition of methanol to acetonitrile. It is concluded that in the former the proton is transferred to a cluster of water molecules, which can be formed only if there is enough water in the solvent mixture. This observation leads to the concept of mono-water, which is the state of water molecules when they constitute a small minority in the solvent mixtures, as opposed to bulk water, which consists of clusters of variable sizes. Systems in which a hopping mechanism of heavy ions has been observed include Br - /Br 2 and I - /I 2 . In these cases the triple ions Br 3 - and I 3 - , respectively are formed, and serve as the mediators for the transfer of the simple halogen ion. A very large increase of conductivity was observed upon solidification of the Br - /Br 3 - system, probably caused by favorable linear alignment of ions in the solid. The conductivity of acidified methanol decreases upon addition of water, because the affinity of the proton to water is higher than to methanol, thus water can act as a scavenger for protons. This behavior exemplifies a general observation, namely that conductivity by hopping can only occur when the Gibbs energy of the system does not change significantly following ion transfer; otherwise the ions would be trapped in the more stable state, hindering further propagation by hopping