Heat Transport

Steady state solute and heat transfer for laminar flow in a flat duct has been widely studied . The same problem in a circular tube is called the Graetz Problem . The transfer rate of solute and heat from fluids is of importance in a number of processes, such as diffusion of drugs in the blood stream and the uptake of environmental contaminants by animals in aquatic media . In this study the rate of solute or heat transfer from fluids was determined by solving the associated differential equation. Solution by the series approach in the complex plane was used with a series that had a gaussian factor. The eigenfunctions and eigenvalues involved were examined for two different sets of boundary conditions.

We discuss the earthquake rupture behavior along the Chile-Peru subduction zone in terms of the buoyancy of the subducting high oceanic features (HOF's), and the effect of the interplay between HOF and subduction channel thickness on the degree of interplate coupling. We show a strong relation between subduction of HOF's and earthquake rupture segments along the Chile-Peru margin, elucidating how these subducting features play a key role in seismic segmentation. Within this context, the extra increase of normal stress at the subduction interface is strongly controlled by the buoyancy of HOF's which is likely caused by crustal thickening and mantle serpentinization beneath hotspot ridges and fracture zones, respectively. Buoyancy of HOF's provide an increase in normal stress estimated to be as high as 10-50 MPa. This significant increase of normal stress will enhance seismic coupling across the subduction interface and hence will affect the seismicity. In particular, several large earthquakes (M w ≥ 7.5) have occurred in regions characterized by subduction of HOF's including fracture zones (e.g., Nazca, Challenger and Mocha), hotspot ridges (e.g., Nazca, Iquique, and Juan Fernández) and the active Nazca-Antarctic spreading center. For instance, the giant 1960 earthquake (M w = 9.5) is coincident with the linear projections of the Mocha Fracture Zone and the buoyant Chile Rise, while the active seismic gap of north Chile spatially correlates with the subduction of the Iquique Ridge. Further comparison of rupture characteristics of large underthrusting earthquakes and the locations of subducting features provide evidence that HOF's control earthquake rupture acting as both asperities and barriers. This dual behavior can be partially controlled by the subduction channel thickness. A thick subduction channel smooths the degree of coupling caused by the subducted HOF which allows lateral earthquake rupture propagation. This may explain why the 1960 rupture propagates through six major fracture zones, and ceased near the Mocha Fracture Zone in the north and at the Chile Rise in the south (regions characterized by a thin subduction channel). In addition, the thin subduction channel (north of the Juan Fernández Ridge) reflects a heterogeneous frictional behavior of the subduction interface which appears to be mainly controlled by the subduction of HOF's.

An integrated SOL/divertor code is being developed by the JAEA (Japan Atomic Energy Agency) for interpretation and prediction studies of the behavior of plasmas, neutrals, and impurities in the SOL/divertor region. A code system consists of the 2D fluid code for plasma (SOLDOR), the neutral Monte-Carlo code (NEUT2D), the impurity Monte-Carlo code (IMPMC), and the particle simulation code (PARASOL). The physical processes of neutrals and impurities are studied using the Monte Carlo (MC) code to accomplish highly accurate simulations. The so-called divertor code, SOLDOR/NEUT2D, has the following features: 1) a high-resolution oscillation-free scheme for solving fluid equations, 2) neutral transport calculation under the condition of fine meshes, 3) successful reduction of MC noise, and 4) optimization of the massive parallel computer. As a result, our code can obtain a steady state solution within 3 ∼ 4 hours even in the first run of a series of simulations, allowing the performance of an effective parameter survey. The simulation reproduces the X-point MARFE (multifaceted asymmetric radiation from edge) in the JT-60U. It is found that the chemically sputtered carbon at the dome causes radiation peaking near the X-point. The performance of divertor pumping in the JT-60U is evaluated based on particle balances. In regard to the divertor design of the next tokamak of JT-60U, the simulation indicates the dependencies of pumping efficiency on the divertor geometry and operational conditions. The efficiency is determined by the balance between the incident and back-flow fluxes into and from the exhaust chamber.

Cleaning techniques for foraminifera for Mg/Ca analyses include water and methanol rinses, but techniques vary as to whether they include oxidative and reductive steps or only an oxidative step . The difference in cleaning technique has been found to affect Mg/Ca ratios. found the reductive step lowers Mg/Ca ratios by approximately 10%, and an interlaboratory comparison study estimated the reductive step lowered Mg/Ca by 15% . Recent work by found the difference to be 8-9%. Mg/Ca values were converted to temperature using the Anand multispecies equation as this calibration is relatively data rich. The equation was adjusted to account for the fact that the Anand calibration was based on foraminifera that had been cleaned only with an oxidative step. We assume the reductive step reduces Mg/Ca values by approximately 10%: Original Anand Multi-species equation: Mg/Ca = 0.38exp(0.090T) Modified Anand equation: Mg/Ca + 0.1Mg/Ca = 0.38e 0.09T or Mg/Ca = 0.345exp(0.090T) Mg/Ca samples from cores GeoB10029-4 [Mohtadi et al., 2010], GeoB10038-4

A comparative study of three snow models with different complexities was carried out to assess how a physically detailed snow model can improve snow modeling within general circulation models. The three models were (a) the U.S. Army Cold Regions Research and Engineering Laboratory Model (SNTHERM), which uses the mixture theory to simulate multiphase water and energy transfer processes in snow layers; (b) a simplified three-layer model, Snow-Atmosphere-Soil Transfer (SAST), which includes only the ice and liquid-water phases; and (c) the snow submodel of the Biosphere-Atmosphere Transfer Scheme (BATS), which calculates snowmelt from the energy budget and snow temperature by the force-restore method. Given the same initial conditions and forcing of atmosphere and radiation, these three models simulated time series of snow water equivalent, surface temperature, and fluxes very well, with SNTHERM giving the best match with observations and SAST simulation being close. BATS captured the major processes in the upper portion of a snowpack where solar radiation provides the main energy source and gave satisfying results for seasonal periods. Some biases occurred in BATS surface temperature and energy exchange due to its neglecting of liquid water and underestimating snow density. Ice heat conduction, meltwater heat transport, and the melt-freeze process of snow exhibit strong diurnal variations and large gradients at the uppermost layers of snowpacks. Using two layers in the upper 20 cm and one deeper layer at the bottom to simulate the multiphase snowmelt processes, SAST closely approximated the performance of SNTHERM with computational requirements comparable to those of BATS.

When used in conjunction with the CQL3D code, X-ray spectra and flux allow estimates of fast electron population and diffusion coefficient. Using new solid state materials -compact, flexible and low maintenance high energy X-ray diagnostics are possible with low cost. Cadmium-telluride (CdTe) X-ray detectors in the 5-150KeV energy range have been used to measure the hard X-ray spectrum on MST for a range of plasma parameters. A direct digitization proceedure has been used to measure the X-rays rather than the conventional energy discrimination and counting. This allows a simpler hardware setup with flexible energy and time binning with no increase in cost. Modelling using the CQL3D Fokker-Planck code gives estimates for the fast electon population and diffusion coefficient.

The theoretical background for the finite element computer program, MPSalsa, is presented in detail. MPSalsa is designed to solve laminar, low Mach number, two-or three-dimensional incompressible and variable density reacting fluid flows on massively parallel computers, using a Petrov-Galerkin finite element formulation. The code has the capability to solve coupled fluid flow, heat transport, multicomponent species transport, and finite-rate chemical reactions, and to solve coupled multiple Poisson or advection-diffusion-reaction equations. The program employs the CHEMKIN library to provide a rigorous treatment of multicomponent ideal gas kinetics and transport. Chemical reactions occurring in the gas phase and on surfaces are treated by calls to CHEMKIN and SURFACE CHEMKIN, respectively. The code employs unstructured meshes, using the EXODUS I1 finite element database suite of programs for its input and output files. MPSalsa solves both transient and steady flows by using fully implicit time integration, an inexact Newton method and iterative solvers based on preconditioned Krylov methods as implemented in the Aztec solver library.

Provision of passive means to reactor core decay heat removal enhances the nuclear power plant (NPP) safety and availability. In the earlier Indian pressurised heavy water reactors (IPHWRs), like the 220 MWe and the 540 MWe, crash cooldown from the steam generators (SGs) is resorted to mitigate consequences of station blackout (SBO). In the 700 MWe PHWR currently being designed an additional passive decay heat removal (PDHR) system is also incorporated to condense the steam generated in the boilers during a SBO. The sustainability of natural circulation in the various heat transport systems (i.e., primary heat transport (PHT), SGs, and PDHRs) under station blackout depends on the corresponding system's coolant inventories and the coolant circuit configurations (i.e., parallel paths and interconnections). On the primary side, the interconnection between the two primary loops plays an important role to sustain the natural circulation heat removal. On the secondary side, the steam ...

An eddy-permitting, quasi-global oceanic general circulation model, LICOM (LASG/IAP (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics) Climate System Ocean Model), with a uniform grid of 0.5 • × 0.5 • is established. Forced by wind stresses from Hellerman and Rosenstain (1983), a 40-yr integration is conducted with sea surface temperature and salinity being restored to the Levitus 94 datasets. The evaluation of the annual mean climatology of the LICOM control run shows that the large-scale circulation can be well reproduced. A comparison between the LICOM control run and a parallel integration of L30T63, which has the same framework but a coarse resolution, is also made to confirm the impact of resolution on the model performance. On account of the reduction of horizontal viscosity with the enhancement of the horizontal resolution, LICOM improves the simulation with respect to not only the intensity of the large scale circulations, but also the magnitude and structure of the Equatorial Undercurrent and South Equatorial Current. Taking advantage of the fine grid size, the pathway of the Indonesian Throughflow (ITF) is better represented in LICOM than in L30T63. The transport of ITF in LICOM is more convergent in the upper layer. As a consequence, the Indian Ocean tends to get warmer in LICOM. The poleward heat transports for both the global and individual basins are also significantly improved in LICOM. A decomposed analysis indicates that the transport due to the barotropic gyre, which primarily stands for the barotropic effect of the western boundary currents, plays a crucial role in making the difference.

Ultrahigh-resolution bathymetric maps (25 cm grid) are used to quantify the physical dimensions of and spatial relationships between tectonic, volcanic, and hydrothermal features at six hydrothermal vent fields in the Lau back-arc basin. Supplemented with near-bottom photos, and nested within regional DSL-120A side-scan sonar data, these maps provide insight into the nature of hydrothermal systems along the Eastern Lau Spreading Center (ELSC) and Valu Fa Ridge (VFR). Along-axis transitions evident in localized volcanic morphology and tectonic characteristics include a change from broad low-relief volcanic domes (hundreds of meters wide, <10 m tall) that are dominated by pillow and lobate lava morphologies and are cut by faults and fissures to higher aspect ratio volcanic domes (tens of meters wide, tens of meters tall) dominated by aa-type lava morphologies, with finger-like flows, and few tectonic structures. These alongaxis differences in localized seafloor morphology suggest differences in hydrothermal circulation pathways within the shallow crust and correlate with regional transitions in a variety of ridge properties, including the large-scale morphology of the ridge axis (shallow axial valley to axial high), seafloor lava compositions, and seismic properties of the upper crust. Differences in morphologic characteristics of individual flows and lava types were also quantified, providing an important first step toward the remote characterization of complex terrains associated with hydrothermal vent fields.

The circulation and water mass properties in the Eurasian Basin are discussed based on a review of previous research and an examination of observations made in recent years within, or parallel to, DAMOCLES (Developing Arctic Modeling and Observational Capabilities for Long-term Environmental Studies). The discussion is strongly biased towards observations made from icebreakers and particularly from the cruise with R/V Polarstern 2007 during the International Polar Year (IPY). Focus is on the Barents Sea inflow branch and its mixing with the Fram Strait inflow branch. It is proposed that the Barents Sea branch contributes not just intermediate water but also most of the water to the Atlantic layer in the Amundsen Basin and also in the Makarov and Canada basins. Only occasionally would high temperature pulses originating from the Fram Strait branch penetrate along the Laptev Sea slope across the Gakkel Ridge into the Amundsen Basin. Interactions between the Barents Sea and the Fram Strait branches lead to formation of intrusive layers, in the Atlantic layer and in the intermediate waters. The intrusion characteristics found downstream, north of the Laptev Sea are similar to those observed in the northern Nansen Basin and over the Gakkel Ridge, suggesting a flow from the Laptev Sea towards Fram Strait. The formation mechanisms for the intrusions at the continental slope, or in the interior of the basins if they are reformed there, have not been identified. The temperature of the deep water of the Eurasian Basin has increased in the last 10 yr rather more than expected from geothermal heating. That geothermal heating does influence the deep water column was obvi-ous from 2007 Polarstern observations made close to a hydrothermal vent in the Gakkel Ridge, where the temperature minimum usually found above the 600-800 m thick homogenous bottom layer was absent. However, heat entrained from the Atlantic water into descending, saline boundary plumes may also contribute to the warming of the deeper layers.

We show that the local temperature dependence of thermalized electron and phonon populations along metallic carbon nanotubes is the main reason behind this non-linear transport characteristics in the high bias regime. Our model that considers optical and zone boundary phonon emission as well as absorption by charge carriers is based on the solution of the Boltzmann transport equation that assumes a local temperature along the nanotube, determined self-consistently with the heat transport equation. By using realistic transport parameters, our results not only reproduce experimental data for electronic transport, but also provide a coherent interpretation of thermal breakdown under electric stress. In particular, electron and phonon thermalization prohibits ballistic transport in short nanotubes.

In the North Atlantic, cold, relatively salty water sinks in the icy Labrador and Greenland seas, forming North Atlantic Deep Water (NADW).This circulates through the global ocean, driving ocean overturning and global heat transport and, thus, impacting global climate. As one of the most climatically sensitive regions on Earth, the North Atlantic has experienced abrupt changes to its oceanatmosphere‐cryosphere system, triggered by fluctuations in meltwater delivery to source areas of NADW formation.For about the past 100 thousand years, these abrupt jumps in climate state have manifested as ‘Dansgaard/Oeschger’ (D/O) oscillations (millennial‐scale warm‐cold oscillations) and &#39;Heinrich&#39; events in ice and marine sediment cores, respectively [e.g., Dansgaard et al., 1993; Bond and Lotti, 1995]. These Heinrich events are characterized as huge input of ice‐rafted debris (IRD) and meltwater pulses, documenting episodes of sudden instability and collapse of the current Greenland ic...

Heat transfer in metal honeycomb monoliths, under non-adiabatic conditions, is considered in this work. Using a simple geometric simulation of the monolithic structure, steady-state heat balances are written separately for the solid and gas phases of the simulated monolith In the absence of chemical reaction the model is solved analytically to give solid and gas temperature profiles radially and axially within the monolith. An experimental system is used to compare heat transfer in a honeycomb metal monolith to the model predictions. Also, heat transfer in a packed bed of ceramic pellets is studied experimentally and compared to the metal monolith under similar, non-adiabatic conditions. Results point out the different heattransfer merits of each of these two bed configurations.

Horizontal convection has been used as an idealised model of the ocean overturning circulation, where some non-uniform buoyancy forcing profile is imposed along a horizontal boundary. Several different driving temperature profiles have been chosen for past numerical and laboratory studies, likely for convenience, yet the effect of the shape of the chosen profile on the resulting horizontal convection flow remains unexplored. Here high order numerical simulation is used to investigate this problem. Time independent, periodic and chaotic regimes are identified as functions of Rayleigh number (Ra) and profile shape, with a step temperature profile being found to be more unstable than a linear temperature profile. Using a nonlinear Stuart-Landau analysis, the primary instability is consistently found to occur through a supercritical (non-hysteretic) bifurcation. This research highlights the importance of the horizontal buoyancy forcing profile in determining the thermal forcing required to produce instability in horizontal convection. In addition, Nusselt number scales to Ra 1=5 in the fully convective regime, with scaling exponents elevating beyond Ra � 10 10 . This elevated scaling was more pronounced for the linear thermal boundary profile than for the step profile over the computed Rayleigh numbers range.

In this paper, we focus on the thermal transport properties of antiferromagnetic spin chains cuprates. The chain magnetic excitations, the spinons, partake in heat transport at low temperature, but spinon heat transport decays well below room temperature, possibly because of a coupling with phonons. By means of inelastic neutron scattering, we thoroughly study the lattice dynamics of spin chain compounds Sr 2 CuO 3 , Ca 2 CuO 3 , along with double spin-chain compounds SrCuO 2 . We come to the conclusion that there are no obvious anomalies in the phonon dispersions, which suggests a weak spinon-phonon coupling regime.

We show that the local temperature dependence of thermalized electron and phonon populations along metallic carbon nanotubes is the main reason behind this non-linear transport characteristics in the high bias regime. Our model that considers optical and zone boundary phonon emission as well as absorption by charge carriers is based on the solution of the Boltzmann transport equation that assumes a local temperature along the nanotube, determined self-consistently with the heat transport equation. By using realistic transport parameters, our results not only reproduce experimental data for electronic transport, but also provide a coherent interpretation of thermal breakdown under electric stress. In particular, electron and phonon thermalization prohibits ballistic transport in short nanotubes.

The American Physical Society Gyrokinetic particle characterization of core turbulence in tokamaks JEAN-NOEL LEBOEUF, JNL Scientific, BENJAMIN CARRERAS, BACV Solutions, VIKTOR DECYK, UCLA, DAVID NEWMAN, U. Alaska Fairbanks, RAUL SANCHEZ, ORNL -We are continuing to characterize transport in gyrokinetic calculations of ion channel turbulence in tokamaks with the three-dimensional global toroidal nonlinear parallel particle-in-cell UCAN code. In particular, we are taking full advantage of the extended particle manager in UCLA's own PLIB library of massively parallel particle and field managing MPI routines. It now automatically handles tracking/tracing of the same active simulation particles through space and time and especially multiple processors, including restarts with different numbers of tagged particles. The particle data thus tracked and stored comprise the complete set of positions and velocities for each tracked particle at each chosen instant of time (typically every 100th time step). These particle data have been analyzed with tools previously applied to passive marker particles in fluid turbulence simulations which are specifically aimed at revealing the non-diffusive aspects of particle and heat transport. The UCAN calculations show that the transport signatures are different without and with zonal flows self-consistently generated from the fluctuations allowed to evolve. These differences are explored in this presentation for tokamak discharges with DIII-D parameters and profiles.

Paltridge (1975, 1978) proposed that the atmosphere seeks to maximize entropy production, as a non-equilibrium thermodynamic system. He constructed a simple box model of the atmosphere which yields surprisingly realistic predictions for the latitudinally-averaged surface temperature, fractional cloud cover and meridional heat fluxes. First and foremost, I would like to thank Prof. Joe LaCasce for making this an interesting journey. This was so not what I expected to do when I knocked on your door in August! However, it has been a great experience and I have learned so much. Thank you for sharing your enthusiasm and your knowledge, and for excellent guidance throughout. Also thank you for giving me freedom to explore my whims and for answering my questions at any time of the day. Thanks to Lise and Maria for sharing your CAM3 expertise. An extra thanks to Lise for kindly providing all CAM3 data used in this thesis and for insightful storm tracks comments. A special thanks to Andrea for proofreading and for adding a taste of academic structure. Great thanks to Henrik, Rafa and Paulo for making Atmospheric Sciences to so much more than just Science! Henrik, thank you for thinking about everything differently and for teaching me that the Mediterranean Sea is slightly deeper than six meters. Rafa, thank you for asking intricate questions where no answer could satisfy you and for demanding ice cream breaks too often. Paulo, thank you for sharing your knowledge and for interesting discussions about dynamics and strange American food. Most of all I would like to thank Henrik for giving me the chance to complete my master's degree. Also thank you for your support and care throughout. Life would not have been the same without you.

The control of phonon propagation in nanoparticle arrays is one of the frontiers of nanotechnology, potentially enabling the discovery of materials with unknown functionalities for potential innovative applications. The exploration of the terahertz window appears quite promising as phonons in this range are the leading carriers of heat transport in insulators and their control is the key to implement devices for heat flow management. Unfortunately, this scientific field is still in its infancy, and even a basic topic such as the influence of floating nanoparticles on the terahertz phonon propagation of a colloidal suspension still eludes a firm answer. Shedding some light on this topic is the main motivation of the present work, which focuses an inelastic X-ray scattering (IXS) measurements on a dilute suspension of Au nanospheres in water. Measured spectra showed a nontrivial shape displaying multiple inelastic features that, based on a Bayesian inference analysis, we assign to pho...

On 19th September 2008, during powering tests of the main dipole circuit of the Large Hadron Collider, an electrical fault occurred producing an electrical arc and resulting in mechanical and electrical damage, release of helium from the magnet cold mass to the insulation vacuum enclosure and consequently to the tunnel, via the spring-loaded relief discs on the vacuum enclosure. The

The peculiar characteristics of CH 4 catalytic autothermal reforming make this process a good candidate for a hydrogen based distributed power generation. The feasibility of this option is closely linked to both technological and economical aspects. Indeed, the choice of a very highly active catalyst to reach the goal of reactor compactness as well as the costs comparison of small scale plants with that of large scale ones are essential requirement to assess the suitability of the former for an energy sustainable development. In this paper the performances of ATR structured catalysts in form of monoliths or ceramic foams are compared. Moreover, the production costs of a traditional scheme (ATR+PSA) for a 50 m 3 /h (STP) small scale unit are reported. Such a scheme could be applied to natural gas fed stationary plants.

In this paper the heat transport of attosecond electron pulses is investigated. It is shown that attosecond electrons can propagate as thermal waves or diffused as particle conglommerates ,Proca equation as type equation for the thermal transport of the attosecond electron pulsem is formulated

In this paper the Lorentz transformation for temperature is derived and discussed. Considering the hyperbolic heat transport equation it is shown that T( prim) = gamma T, where gamma is the Lorentz factor, T denotes the temperature in the rest system and T(prim) is the temperature in the moving system (rod).

In this paper a global optimization algorithm is presented to rigorously solve the MINLP model by for the synthesis of heat exchanger networks under the simplifying assumptions of linear area cost, arithmetic mean temperature difference driving forces and no stream splitting. The proposed approach relies on the use of two new different sets of convex underestimators for the heat transfer area. A thermodynamic analysis is used to derive the first set of analytical linear and nonlinear convex underestimators as well as variable bounds and bounds contraction relationships. The second set of convex underestimators is generated by a relaxation of the heat transport equation through the introduction of a new variable, and an inequality that contains a nonconvex term that is subsequently replaced by its concave envelope. Based on these new underestimator functions, the original nonconvex MINLP is replaced by a convex MINLP that predicts tight lower bounds to the global optimum, and which is used in a hybrid branch and bound/outer-approximation search method. Application of the proposed ideas, and the algorithm are illustrated with several numerical examples.

MHD flow and heat transfer have been analyzed for a front poloidal channel in the outboard module of a Dual Coolant Lithium Lead (DCLL) blanket, with a flow channel insert made of a silicon carbide composite. The US reference DCLL blanket module [C.

Hydraulic conductivity data derived from ca. 140, 000 crystalline rock boreholes from the upper 150 m of the crust of Norway and Sweden have been pre-processed in a GIS and subsequently subject to explorative data analysis and simple-and stepwise multiple linear regression methods. The variables that were evaluated include the annual postglacial uplift rate, lithology, soil thickness, relative relief, net precipitation and borehole depth. The results are discussed in light of the regional geodynamic framework especially that related to postglacial rebound and crustal deformation. The typical regional variables, the rate of postglacial uplift and net precipitation, explain only a small portion of the total variation in hydraulic conductivity. Drilled rock depth stands out as the most important predictor. Regional variations in hydraulic conductivity coincide with distinct irregularities in profile graphs of the uplift surface, suggesting an influence of recent geodynamics on hydraulic conductivity along localised zones of compression, tension and shear. It is believed that these findings, if further pursued, may contribute to the understanding of the complexity of the rebound tectonics associated with the late glacial and Holocene deglaciation.

The accuracy of using laboratory-scale experiments to predict drainage quality from mining waste rock piles is not well understood. A rigorous study to measure and compare waste rock and drainage characteristics at various scales has been designed, constructed and is being monitored at the Diavik diamond mine in the Northwest Territories, Canada. The objectives of the program are to characterize the physicochemical processes occurring in waste rock piles in a permafrost environment, and to quantitatively assess the application of small-scale laboratory experiments in the prediction of effluent quality from waste rock piles. Three well instrumented, large-scale waste rock piles were constructed from run of mine waste rock. Diavik waste rock has low sulfide content and has developed three rock classes for waste rock: Type I with a target of &lt; 0.04 wt. % S, Type II with target 0.04 to 0.08 wt. % S and Type III with a target of &gt; 0.08 wt. % S. A Type I pile, a Type III pile and a ...

Kapitza thermal resistance is a common feature of material interfaces. It is defined as the ratio of the thermal drop at the interface to the heat flux flowing across the interface. One expects that this resistance will depend on the structure of the interface and on the temperature. We address the heat conduction in one-dimensional chain models with isotopic and/or coupling defects and explore the relationship between the interaction potentials and simulated properties of the Kapitza resistance. It is revealed that in linear models the Kapitza resistance is well-defined and size-independent (contrary to the bulk heat conduction coefficient), but depends on the parameters of thermostats used in the simulation. For β-FPU model one also encounters the dependence on the thermostats; in addition, the simulated boundary resistance strongly depends on the total system size. Finally, in the models characterized by convergent bulk heat conductivity (chain of rotators, Frenkel-Kontorova model) the boundary resistance is thermostat-and size-independent, as one expects. In linear chains, the Kapitza resistance is temperature-independent; thus, its temperature dependence allows one to judge on significance of the nonlinear interactions in the phonon scattering processes at the interface.

Strike-point sweeping and real-time-controlled (RTC) impurity seeding are both expected to be needed on JET following its upgrade to an all-metal wall with enhanced neutral-beam heating, thereby anticipating exhaust-control requirements plus the materials planned for ITER. Preliminary trials in the previous carbon device have combined these techniques in high-triangularity type I H-mode plasmas, using a VUV spectroscopic signal for feedback control of nitrogen injection. Compared with earlier unswept feedforward counterparts, similar strong mitigation of divertor heat load between ELMs was achieved in swept RTC cases for less than half the integrated nitrogen input and correspondingly less adverse effect upon other properties. Both sweeping and RT control contributed to this improvement. Time-average normalized energy confinement H 98y t ∼ 1, Greenwald density fraction f Gwd t ∼ 0.9 and particularly purity denoted by effective ionic charge Z eff t ≈ 1.7, all remained closer to good reference levels. Transient effluxes in ELMs were also less affected, however, and would require separate active control.

persion curve of the high-temperature b-phase of zirconium at ambient pressure, which has been related to the b ! q and b ! a phase transitions . It is therefore possible that these phonon mode softenings may play a key role in the formation of zirconium metallic glass. Inelastic scattering at elevated pressure and temperature is needed to investigate the driving mechanisms for the present observations. Liquid-liquid phase separation or decomposition of deeply undercooled metallic liquids is at present a major problem faced in the fundamental study and technological processing of bulk metallic glasses, even for extremely good glass-formers like Vit1 (Zr 41.2 Ti 13.8 Cu 12.5 Ni 10 Be 22.5 ) and Vit105 (Zr 52.5 Ti 5 Cu 17.9 Ni 14.6 Al 10 ) (refs 5-8). Similarly, decomposition happens when amorphous alloys are annealed at temperatures above the glass transition temperature 5 , T g . Experiments have revealed that such decomposition is responsible for the embrittlement of some bulk metallic glasses 1,5 . For mechanical applications, it is important to find metallic glasses that have higher thermal stability (that is, a smaller difference between the critical temperature 1 , T c , and T g ) and thus a lower probability of decomposition. As T c 2 T g reduces, however, the amorphous alloys, such as derivatives of Vit1 and Vit105, tend to have a somewhat diminished GFA. We consider that the extraordinary GFA of pure zirconium metal, combined with its superior thermal stability, will overcome the problems that exist in amorphous alloys. In addition, the glass formed within a solid state may represent a distinct state of matter that may have other distinct properties yet to be explored, which may open new opportunities for research and development in the area of metallic glasses. A Synchrotron X-ray experiments at high pressure and temperature were conducted on bulk, polycrystalline zirconium specimens of 1.0 mm diameter and 0.5 mm thickness, with the diffraction volume defined by 0.1 £ 0.1 mm collimators. After observing the formation of amorphous zirconium, particular care was taken in our experiments, in that the formation of glassy zirconium was confirmed by collecting data at several different locations in the sample. The incident X-ray beam, however, is still too small compared to the bulk sample studied. In this regard, the GFA of bulk zirconium metal needs to be further studied by neutron diffraction. In our high P-T neutron diffraction experiments, the cross-section of the incident neutron beam has a diameter of 5 mm, which is defined by cadmium and B 4 C collimators. The time-of-flight neutron diffraction patterns were collected by eight detector banks that are available for TAP-98, at a fixed Bragg angle of 2v ¼ 908. The experiments were performed on the polycrystalline zirconium specimens of ,100 mm 3 sample volume. This sample size, along with the current design of high-pressure cell, limits the experimental pressure to 5 GPa at high temperatures. So, unlike our X-ray diffraction experiments, our neutron diffraction experiments did not reach the P-T conditions needed for the glassy zirconium to form. These results are mainly used to constrain the a-b phase boundary, and will be published elsewhere.

It is well-known that during high-velocity flow of gas-particle mixtures through a vertical duct the particles are distributed nonuniformly over the cross section. We had shown in an earlier paper that such a nonuniform state is sustained under fully-developed flow conditions by the large scale fluctuations accompanying such flows. In the present study, we have carried out a simple analysis of the developing flow problem to demonstrate that the evolution of the nonuniform distribution is indeed driven by turbophoresis.

This paper continues the process of reconciling results obtained when investigating heat transfer in the supercritical liquid-vapour region inherent in stationary and fast processes. A relatively simple model of nonstationary heat transfer at the microscopic level in a non-idealised system is constructed. The model provides a possible explanation for the increase in the thermal resistance of a supercritical fluid (drop in heat conduction) at a not too great distance from the critical isobar on a scale of small characteristic times and sizes. The model is based on an explicit account of a significant decrease in thermal diffusivity when approaching the critical temperature of the substance. The simulation results are compared with experimental data on the rapid (lasting in units-tens of milliseconds) transfer of a compressed liquid to the supercritical temperature region along a supercritical isobar.

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The linear instability of the tearing mode is analyzed using a gyrokinetic approach within a Hamiltonian formalism, where the interaction between particles and the tearing mode through the wave-particle resonance is retained. On the one hand, the curvature of the magnetic field is shown to play no role in the linear instability when only passing particles are present in the plasma. On the other hand, the presence of trapped particles leads to an overall increase in the growth rate. Gyrokinetic simulations using the state-of-the-art Gkw code confirm these findings and are further used to investigate the impact of the magnetic field curvature and the temperature gradient on tearing modes including the effect of trapped particles. Without the temperature gradient, wave-particle resonance with the trapped electrons tends to stabilize the tearing mode, while with the finite temperature gradient, the magnetic curvature tends to destabilize the tearing mode, suggesting an interchange mecha...

An advanced quantitative approach of pulse-phase-thermography for non-destructive testing in civil engineering is described in this contribution. The characteristic frequency of the maximum phase-contrast between defects and sound areas is used as a means for the characterization of its depth. The new approach is tested in the laboratory on concrete structures with defects of polystyrene. The surfaces of the structures were heated with IR-radiators for varying time periods. The presented investigations were funded by the Deutsche Forschungsgemeinschaft (DFG) and were carried out in co-operation with the Technical University of Berlin (TUB).

Pulse thermography of concrete structures is used in civil engineering for detecting voids, honeycombing and delamination. The physical situation is readily modeled by Fourier's law. Despite the simplicity of the PDE structure, quantitatively realistic numerical 3D simulation faces two major obstacles. First, the short heating pulse induces a thin boundary layer at the heated surface which encapsulates all information and therefore has to be resolved faithfully. Even with adaptive mesh refinement techniques, obtaining useful accuracies requires an unsatisfactorily fine discretization. Second, bulk material parameters and boundary conditions are barely known exactly. We address both issues by a semi-analytic reformulation of the heat transport problem and by parameter identification. Numerical results are compared with measurements of test specimens.

The mass and heat budgets of the warm upper-ocean layer are investigated in the equatorial Atlantic using in situ observations during the period 1979-99, which encompassed a series of warm events in the equatorial Atlantic. The warm water layer is defined as the layer having an in situ temperature higher than 20ЊC, which is within the core of the equatorial thermocline. The geostrophic transport is calculated by combining gridded temperatures with historical salinity data. The Ekman transport is estimated from observed wind data or modelbased wind products. The change in warm water volume is then compared with the horizontal mass convergence, and the residuals are determined. The heat budget of the upper layer is investigated in the same way. Three regions are considered: the equatorial band between 8ЊN and 8ЊS to study the meridional redistribution of the warm water and two boxes (western and eastern boxes) to investigate the zonal redistribution of the warm water. Mass and heat budget variability in the equatorial band is discussed in relation to the zonal wind variability. The authors discovered that during the development of an equatorial warm event the meridional net divergence first decreases, reaching its minimum as the warm event matures. Meridional divergence increases again as conditions become normal in the equatorial band. The vertical velocity through the 20ЊC isotherm also reveals variations consistent with this scenario. Cross-isotherm mass transport decreases during warm events. The heat budget residual is more difficult to interpret. The average value is consistent with heat loss through turbulent mixing at the base (20Њ isotherm), but the fluctuations are most likely noise, resulting mainly from the limited accuracy of the model surface heat fluxes used.

This paper presents an experimental study on the operational limitation of closed loop pulsating heat pipes (CLPHPs), which consist of a total of 40 copper tubes with 1 mm and 2 mm inner diameter, respectively. R123 was employed as the working fluid with filling ratios of 30%, 50% and 70%, respectively. Three operational orientations were investigated, viz. vertical bottom heated, horizontal heated and vertical top heated orientations. The effects of inner diameter, operational orientation, filling ratio and heat input flux on thermal performance and performance limitation were investigated. The results show that for the CLPHP with 2 mm ID tubes the best performance existed in the vertical orientation with heating at the bottom, while for the CLPHP with 1 mm ID tubes, orientation played almost no role. A filling ratio of 50% was optimum for both CLPHPs to obtain best performances in all orientations. The CLPHPs were operated till a performance limit characterized by serious evaporator overheating (dry-out) occurred. Rather high heat loads could be accommodated. Dry-out heat fluxes in the vertical bottom heat mode were about 1242 W/cm 2 (1 mm ID) and 430 W/cm 2 (2 mm ID) for axial heat transport, and about 32 W/cm 2 (1 mm ID) and 24 W/cm 2 (2 mm ID) for radial heat input, always with respect to the inner tube diameter.

An analytical model of heat transport in a laser diode is presented together with measurements of the temperature distribution by photothermal microscopy. Comparison between model and measurements shows the temperature distribution to be issued from a cylindrical heat source diffusing in the surrounding bulk material. Laser output facet heating by stimulated photon absorption is shown to be of negligible importance.

UNLV hosted an NHI Systems Interface Meeting on Dec. 16 and a UNLVRF HTHX Kickoff Meeting on Dec. 17. The purpose of the meetings was to coordinate the FY05 research and development effort of the UNLV Research Foundation portion of the Nuclear Hydrogen Initiative among the DOE, national program technical directors and the UNLVRF collaborators. Collaborators also had the opportunity to discuss their research program plan and update their progress. It was decided that these type of collaboration meetings were very useful and they will be held quarterly at the various collaborator sites. The next meeting will be in March in Salt Lake City hosted by Ceramatec, Inc. • HTHX Computational Design. The work on the three-dimensional numerical simulations for both the rectangular and curved fin edge cases for the baseline heat exchanger using UC Berkeley dimensions with He-Flinak as the working fluids continued. Simulations indicate that temperature dependent physical properties do not significantly affect the flow and heat transfer results. The mesh independence investigation for CFD calculations of high temperature heat exchanger was completed and investigations of correctness for periodic boundary conditions for upper and lower walls were completed, both showing satisfactory results. Turbulence modeling had a pronounced effect on the helium channel heat exchanger channels with rectangular fin edges (23% difference in the pressure drop results) while other results were not significantly affected. • Metallic Materials Testing. Tensile properties of Alloy C-22, Alloy C-276 and Waspaloy have been determined at ambient temperature, 450 and 600 o C in the presence of nitrogen. The evaluation of the stress corrosion cracking (SCC) susceptibility of all three alloys in a 90 o C aqueous solution containing sulfuric acid and sodium iodide under a constant-loading condition was completed. Fractographic evaluations of the tested tensile specimens by scanning electron microscopy (SEM) was also performed. Based on the review of literature gathered from numerous materials-related meetings held at ORNL and UNLV during the quarter, additional materials have been identified for material testing: Incoloy 800H, Incoloy 800HT, AL 610, Niobium (Nb)-1 Zirconium (Zr), Nb-7.5 Tantalum (Ta), and Zr 705. • LSI C-C/Si-C Composite Material Studies. The high-pressure helium permeation tests on a CVD SiC and Pyrolytic Carbon coated fiber sample were performed up to 5.5 MPa. The coating layer kept good hermeticity as no helium bubbles were observed on the sample surface. The sample, however, failed about five minutes later, while experiencing a tensile stress of 276 MPa before breaking (which is much higher than 9 MPa maximum tensile stress typically found from unit cell stress analysis). This test directly verified that CVD carbon coated SiSiC material can keep helium hermeticity under high pressure and stress well beyond the working pressure and stress expected for NGNP.

UNLV hosted an NHI Systems Interface Meeting on Dec. 16 and a UNLVRF HTHX Kickoff Meeting on Dec. 17. The purpose of the meetings was to coordinate the FY05 research and development effort of the UNLV Research Foundation portion of the Nuclear Hydrogen Initiative among the DOE, national program technical directors and the UNLVRF collaborators. Collaborators also had the opportunity to discuss their research program plan and update their progress. It was decided that these type of collaboration meetings were very useful and they will be held quarterly at the various collaborator sites. The next meeting will be in March in Salt Lake City hosted by Ceramatec, Inc. • HTHX Computational Design. The work on the three-dimensional numerical simulations for both the rectangular and curved fin edge cases for the baseline heat exchanger using UC Berkeley dimensions with He-Flinak as the working fluids continued. Simulations indicate that temperature dependent physical properties do not significantly affect the flow and heat transfer results. The mesh independence investigation for CFD calculations of high temperature heat exchanger was completed and investigations of correctness for periodic boundary conditions for upper and lower walls were completed, both showing satisfactory results. Turbulence modeling had a pronounced effect on the helium channel heat exchanger channels with rectangular fin edges (23% difference in the pressure drop results) while other results were not significantly affected. • Metallic Materials Testing. Tensile properties of Alloy C-22, Alloy C-276 and Waspaloy have been determined at ambient temperature, 450 and 600 o C in the presence of nitrogen. The evaluation of the stress corrosion cracking (SCC) susceptibility of all three alloys in a 90 o C aqueous solution containing sulfuric acid and sodium iodide under a constant-loading condition was completed. Fractographic evaluations of the tested tensile specimens by scanning electron microscopy (SEM) was also performed. Based on the review of literature gathered from numerous materials-related meetings held at ORNL and UNLV during the quarter, additional materials have been identified for material testing: Incoloy 800H, Incoloy 800HT, AL 610, Niobium (Nb)-1 Zirconium (Zr), Nb-7.5 Tantalum (Ta), and Zr 705. • LSI C-C/Si-C Composite Material Studies. The high-pressure helium permeation tests on a CVD SiC and Pyrolytic Carbon coated fiber sample were performed up to 5.5 MPa. The coating layer kept good hermeticity as no helium bubbles were observed on the sample surface. The sample, however, failed about five minutes later, while experiencing a tensile stress of 276 MPa before breaking (which is much higher than 9 MPa maximum tensile stress typically found from unit cell stress analysis). This test directly verified that CVD carbon coated SiSiC material can keep helium hermeticity under high pressure and stress well beyond the working pressure and stress expected for NGNP.

We present high-precision measurements of the Nusselt number N as a function of the Rayleigh number R for cylindrical samples of water (Prandtl number σ = 4.38) with diameters D = 49.7, 24.8, and 9.2 cm, all with aspect ratio Γ ≡ D/L ≃ 1 (L is the sample height). In addition, we present data for D = 49.7 and Γ = 1.5, 2, 3, and 6. For each sample the data cover a range of a little over a decade of R. For Γ ≃ 1 they jointly span the range 10 7 < ∼ R < ∼ 10 11 . Where needed, the data were corrected for the influence of the finite conductivity of the top and bottom plates and of the side walls on the heat transport in the fluid to obtain estimates of N ∞ for plates with infinite conductivity and sidewalls of zero conductivity. For Γ ≃ 1 the effective exponent γ ef f of N ∞ = N 0 R γ ef f ranges from 0.28 near R = 10 8 to 0.333 near R ≃ 7 × 10 10 . For R < ∼ 10 10 the results are consistent with the Grossmann-Lohse model. For larger R, where the data indicate that N ∞ (R) ∼ R 1/3 , the theory has a smaller γ ef f than 1/3 and falls below the data. The data for Γ > 1 are only a few percent smaller than the Γ = 1 results.

Temperature gradients can drive vapor diffusion by controlling vapor pressure in the soil. We studied vapor diffusion for soils in two different climates: A semiarid climate at El Cabril (Cordoba, Spain) and a subarctic climate in the Upper Tuul River basin (Mongolia). For El Cabril vapor diffusive fluxes were studied by means of the measured temperatures and an analytical model. For the second site (Upper Tuul) a physically based soil water and energy balance model was developed accounting for relevant processes such as melting-freezing of water and vapor diffusion in the soil. Results of both sites show that vapor diffuses downwards during summer and upwards during winter, while yearly averaged fluxes diffuse downwards. The overall amount is small for El Cabril, but significant for the Upper Tuul. The latter large values can be explained by the large temperature oscillations of the Mongolian climate and the freezing/thawing of subsoil layer.

The mechanical and thermo-mechanical integrity of GaN-on-diamond wafers used for ultra-high power microwave electronic devices was studied using a micro-pillar based in situ mechanical testing approach combined with an optical investigation of the stress and heat transfer across interfaces. We find the GaN/diamond interface to be thermo-mechanically stable, illustrating the potential for this material for reliable GaN electronic devices.

In this investigation, we examined the effects of the three-dimensional geometry of the Barbados Ridge accretionary complex on decollement zone fluid flow and thermal transport. Modeling results indicate that fluid preferentially escapes the decollement zone through the thin sediment layer north of the Tiburon Rise. This "drain" produces a northerly (along-strike) component of fluid flow in the vicinity of the Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) transect. Depending on porepressure ratios on the arcward boundary of the complex, the along-strike component can reach half the magnitude of the component perpendicular to the deformation front. Thermal advection along oblique flow paths would result in significantly higher decollement temperatures at the deformation front than indicated by cross-sectional models constructed perpendicular to the deformation front. Introduction At the Barbados Ridge accretionary complex, Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) drilling legs have yielded geochemical and thermal data that provide evidence for the long-distance migration of fluids (Fisher and Hounslow, 1990; Gieskes et al., 1990; Vrolijk et al., 1990). Driving forces for fluid migration include rapid loading of the sediments during accretionary prism growth, dehydration of minerals, and generation of hydrocarbons (Moore and Vrolijk, 1992). High fiu.id pressures throughout the decollement have been inferred from the narrow taper of the prism (Davis et al., 1983). Borehole measurements provide direct confirmation of elevated fluid pressures within the decollement zone. Excess pore pressure ratios, 3,*, of 0.3 and 0.5 were calculated for boreholes near the deformation front (where 3,* = (Pp-Ph)/(PI-Ph), Pp = pore pressure, Ph = hydrostatic pressure and Pt = lithostatic pressure; Becker et al., in press; Foucher et al., in press). Analytical and numerical models of fluid, thermal, and geochemical transport have provided insight on the formation of excess pore pressures within the accretionary complex and have aided interpretation of observed geochemical and thermal anomalies (

In this investigation, we examined the effects of the three-dimensional geometry of the Barbados Ridge accretionary complex on decollement zone fluid flow and thermal transport. Modeling results indicate that fluid preferentially escapes the decollement zone through the thin sediment layer north of the Tiburon Rise. This "drain" produces a northerly (along-strike) component of fluid flow in the vicinity of the Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) transect. Depending on porepressure ratios on the arcward boundary of the complex, the along-strike component can reach half the magnitude of the component perpendicular to the deformation front. Thermal advection along oblique flow paths would result in significantly higher decollement temperatures at the deformation front than indicated by cross-sectional models constructed perpendicular to the deformation front. Introduction At the Barbados Ridge accretionary complex, Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) drilling legs have yielded geochemical and thermal data that provide evidence for the long-distance migration of fluids (Fisher and Hounslow, 1990; Gieskes et al., 1990; Vrolijk et al., 1990). Driving forces for fluid migration include rapid loading of the sediments during accretionary prism growth, dehydration of minerals, and generation of hydrocarbons (Moore and Vrolijk, 1992). High fiu.id pressures throughout the decollement have been inferred from the narrow taper of the prism (Davis et al., 1983). Borehole measurements provide direct confirmation of elevated fluid pressures within the decollement zone. Excess pore pressure ratios, 3,*, of 0.3 and 0.5 were calculated for boreholes near the deformation front (where 3,* = (Pp-Ph)/(PI-Ph), Pp = pore pressure, Ph = hydrostatic pressure and Pt = lithostatic pressure; Becker et al., in press; Foucher et al., in press). Analytical and numerical models of fluid, thermal, and geochemical transport have provided insight on the formation of excess pore pressures within the accretionary complex and have aided interpretation of observed geochemical and thermal anomalies (

A model calculation is presented for the magnons coherent transmission and corresponding heat transport at magnetic insulating nanojunctions. The system consists of a ferromagnetically ordered ultrathin insulating junction between two semi-infinite ferromagnetically ordered leads. Spin dynamics are analyzed using the equations of motion for the spin precession displacements, valid for the range of temperatures of interest. Coherent scattering cross-sections at the junction boundary are calculated using the phase field matching theory, for all the incidence angles on the boundary from the lead bands, for arbitrary angles of incidence, at variable temperatures, and for different nano thicknesses of the ultrathin junction. The model is general; it is applied in particular to the Fe/Gd/Fe system with a sandwiched ferromagnetic Gd junction. It yields also the thermal conductivity due to the magnons coherent transmission between the two leads when these are maintained at slightly different temperatures. The calculation is carried out for state of the art values of the exchange constants, and elucidates the relation between the coherent scattering transmission of magnons and their thermal conductivity, for different thicknesses.