Thermal dissipation in quantum turbulence
Kobayashi, Michikazu; Tsubota, Makoto
2006-01-01
The microscopic mechanism of thermal dissipation in quantum turbulence has been numerically studied by solving the coupled system involving the Gross-Pitaevskii equation and the Bogoliubov-de Gennes equation. At low temperatures, the obtained dissipation does not work at scales greater than the vortex core size. However, as the temperature increases, dissipation works at large scales and it affects the vortex dynamics. We successfully obtained the mutual friction coefficients of the vortex dy...
Thermal Reservoir coupled to External Field and Quantum Dissipation
Patriarca, M; Patriarca, Fabrizio Illuminati & Marco
1992-01-01
In the framework of the Caldeira-Leggett model of dissipative quantum mechanics, we investigate the effects of the interaction of the thermal reservoir with an external field. In particular, we discuss how the interaction modifies the conservative dynamics of the central particle, and the mechanism of dissipation. We briefly comment on possible observable consequencies.
Nanoscale thermal imaging of dissipation in quantum systems
Halbertal, Dorri; Shalom, Moshe Ben; Embon, Lior; Shadmi, Nitzan; Anahory, Yonathan; Naren, HR; Sarkar, Jayanta; Uri, Aviram; Ronen, Yuval; Myasoedov, Yury; Levitov, Leonid; Joselevich, Ernesto; Geim, Andre Konstantin; Zeldov, Eli
2016-01-01
Energy dissipation is a fundamental process governing the dynamics of physical, chemical, and biological systems. It is also one of the main characteristics distinguishing quantum and classical phenomena. In condensed matter physics, in particular, scattering mechanisms, loss of quantum information, or breakdown of topological protection are deeply rooted in the intricate details of how and where the dissipation occurs. Despite its vital importance the microscopic behavior of a system is usually not formulated in terms of dissipation because the latter is not a readily measureable quantity on the microscale. Although nanoscale thermometry is gaining much recent interest, the existing thermal imaging methods lack the necessary sensitivity and are unsuitable for low temperature operation required for study of quantum systems. Here we report a superconducting quantum interference nano-thermometer device with sub 50 nm diameter that resides at the apex of a sharp pipette and provides scanning cryogenic thermal se...
Dissipative Particle Dynamics investigation of parameters affecting planar nanochannel flows
Kasiteropoulou, D. [Hydromechanics and Environmental Engineering Laboratory, School of Engineering, University of Thessaly, 38834 Pedion Areos, Volos (Greece); Karakasidis, T.E., E-mail: thkarak@uth.gr [Hydromechanics and Environmental Engineering Laboratory, School of Engineering, University of Thessaly, 38834 Pedion Areos, Volos (Greece); Liakopoulos, A. [Hydromechanics and Environmental Engineering Laboratory, School of Engineering, University of Thessaly, 38834 Pedion Areos, Volos (Greece)
2011-11-25
The method of Dissipative Particle Dynamics is applied to investigate the effect of the parameters involved in a nano-channel Poisseuille flow. The parameters considered here include (a) fluid/wall interactions, (b) wall material, (c) range of interaction of fluid particles and wall particles, and (d) external applied force. The computed macroscopic quantities include density, velocity, pressure and temperature profiles. Fluid particle localization near the solid wall is affected by the conservative force (fluid/wall interactions), the wall number density, and the range of atomic interactions (cut-off radius). The external driving force magnitude does not affect the number density distribution. Fluid velocity increases as the conservative force and the wall density increase and the cut-off radius decreases. Pressure distribution is mainly affected by the conservative force and the interaction cut-off radius. Temperature is uniform across most of the channel but presents an increase close to the solid walls especially when increasing the external driving force. We believe that the detailed knowledge of the fluid behaviour under variation of the system parameters obtained from the DPD simulations could be helpful in the design of nanodevices such as lab-on-a-chip devices and nanomixers.
Quantum chaos, thermalization and dissipation in nuclear systems
Sudhir R Jain
2001-08-01
Nuclei have complex energy-level sequence with statistical properties in agreement with canonical random matrix theory. This agreement appears when the one-particle one-hole states are mixed completely with two-particle two-hole states. In the transition, there is a new universality which we present here, bringing about a relation between dynamics and statistics. We summarize also the role of chaos in thermalization and dissipation in isolated systems like nuclei. The methods used to bring forth this understanding emerge from random matrix theory, semiclassical physics, and the theory of dynamical systems.
Firearm suppressor having enhanced thermal management for rapid heat dissipation
Moss, William C.; Anderson, Andrew T.
2014-08-19
A suppressor is disclosed for use with a weapon having a barrel through which a bullet is fired. The suppressor has an inner portion having a bore extending coaxially therethrough. The inner portion is adapted to be secured to a distal end of the barrel. A plurality of axial flow segments project radially from the inner portion and form axial flow paths through which expanding propellant gasses discharged from the barrel flow through. The axial flow segments have radially extending wall portions that define sections which may be filled with thermally conductive material, which in one example is a thermally conductive foam. The conductive foam helps to dissipate heat deposited within the suppressor during firing of the weapon.
The effect of thermal asymmetrical boundaries on entropy generation of viscous dissipative flow of forced convection in thermal non-equilibrium porous media is analytically studied. The two-dimensional temperature, Nusselt number and entropy generation contours are analysed comprehensively to provide insights into the underlying physical significance of the effect on entropy generation. By incorporating the effects of viscous dissipation and thermal non-equilibrium, the first-law and second-law characteristics of porous-medium flow are investigated via various pertinent parameters, i.e. heat flux ratio, effective thermal conductivity ratio, Darcy number, Biot number and averaged fluid velocity. For the case of symmetrical wall heat flux, an optimum condition with a high Nusselt number and a low entropy generation is identified at a Darcy number of 10−4, providing an ideal operating condition from the second-law aspect. This type of heat and fluid transport in porous media covers a wide range of engineering applications, involving porous insulation, packed-bed catalytic process in nuclear reactors, filtration transpiration cooling, and modelling of transport phenomena of microchannel heat sinks. - Highlights: • Effects of thermal asymmetries on convection in porous-medium are studied. • Exergetic effectiveness of porous media with thermal asymmetries is investigated. • 2-D temperature, Nusselt number and entropy generation contours are analyzed. • Significance of viscous dissipation in entropy generation is scrutinized. • Significance of thermal non-equilibrium in entropy generation is studied
Dissipation process of binary gas mixtures in thermally relativistic flow
Yano, Ryosuke
2016-04-01
In this paper, dissipation process of binary gas mixtures in thermally relativistic flows is discussed with focus on characteristics of diffusion flux. As an analytical object, we consider the relativistic rarefied-shock layer around a triangular prism. Numerical results for the diffusion flux are compared with the Navier–Stokes–Fourier (NSF) order approximation of the diffusion flux, which is calculated using the diffusion and thermal-diffusion coefficients by Kox et al (1976 Physica A 84 165–74). In the case of uniform flow with small Lorentz contraction, the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is roughly approximated by the NSF order approximation inside the shock wave, whereas the diffusion flux in the vicinity of a wall is markedly different from the NSF order approximation. The magnitude of the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is similar to that of the NSF order approximation inside the shock wave, unlike the pressure deviator, dynamic pressure and heat flux, even when the Lorentz contraction in the uniform flow becomes large, because the diffusion flux does not depend on the generic Knudsen number from its definition in Eckart’s frame. Finally, the author concludes that for accuracy diffusion flux must be calculated using the particle four-flow and averaged four velocity, which are formulated using the four velocity defined by each species of hard spherical particles.
Dissipation process of binary mixture gas in thermally relativistic flow
Yano, Ryosuke
2016-01-01
In this paper, we discuss dissipation process of the binary mixture gas in the thermally relativistic flow \\textcolor{red}{by focusing on the characteristics of the diffusion flux}. As an analytical object, we consider the relativistic rarefied-shock layer problem around the triangle prism. Numerical results of the diffusion flux are compared with the Navier-Stokes-Fourier (NSF) order approximation of the diffusion flux, which is calculated using the diffusion and thermal-diffusion coefficients by Kox \\textit{et al}. [Physica A, 84, 1, pp.165-174 (1976)]. In the case of the uniform flow with the small Lorentz contraction, the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is roughly approximated by the NSF order approximation inside the shock wave, whereas the diffusion flux in the vicinity of the wall is markedly different from the NSF order approximation. The magnitude of the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is simil...
Highlights: ► The effectiveness of the THENs is defined. ► Thermal resistance decreases monotonously with the increase in effectiveness. ► Entropy generation is not always appropriate to optimize THENs. ► Application of entransy dissipation to THEN optimization is conditional. - Abstract: The two-stream heat exchanger networks (THENs) are widely used in industry. The effectiveness of the THENs is analyzed in this paper. The general expressions for the entransy dissipation, the entransy-dissipation-based thermal resistance and the entropy generation for a generalized THEN are developed. It is found that the expressions are independent of the specific constitution of the THENs. Only the entransy-dissipation-based thermal resistance always decreases monotonously with the increase in effectiveness, while the entransy dissipation and the entropy generation do not. Therefore, the entransy-dissipation-based thermal resistance is most applicable for the optimization of the THENs.
Thermal dissipation media for high power electronic devices using a carbon nanotube-based composite
Challenges in the thermal dissipation of an electronic package arise from the continuous increase in power density of higher-power devices. Carbon nanotubes (CNTs) are known as the highest thermal conductivity material (2000 W mK−1). This excellent thermal property suggests an approach in applying the CNTs in thermal dispersion materials to solve the aforementioned problems. In this work, we present an effect of thermal dissipation of the CNTs in the high-brightness light emitting diode (HB-LED) and micro-processor. For the thermal dissipation of the HB-LED, a vertically aligned carbon nanotube (VA-CNT) film on a Cu substrate was applied. Meanwhile, for the thermal dissipation of a micro-processor, the composite of commercial thermal paste/CNTs was used instead of the VA-CNTs. The experimental and simulation results have confirmed the advantages of the VA-CNT film and thermal paste/CNT composite as excellent thermal dissipation media for HB-LEDs, μ-processors and other high power electronic devices
Basic characteristics of Kadra reservoir influencing the heat dissipation of thermal effluent
The condenser coolant water from the nuclear power plants installed at Kaiga is being discharged into Kadra reservoir. This paper presents some of the important characteristics of Kadra reservoir which may influence the dissipation of heat from warm water released into the reservoir. Ambient temperature of the reservoir water varied annually from 24.6 degC to 33.3 degC. Preliminary investigation shows that the surface temperature of the discharged warm water decreased slowly as the distance from out fall point increases. In the out fall area practically there is no water current except when wind speeds are high. Wind affected surface current and resulting turbulence were observed. Water below 5m depth is practically unaffected by the thermal plume. The detailed investigation is in progress to generate conclusive data. (author)
Tidal dissipation in creeping ice and the thermal evolution of Europa
McCarthy, Christine; Cooper, Reid F.
2016-06-01
The thermal and mechanical evolution of Europa and comparable icy satellites-the physics behind creating and sustaining a subsurface water ocean-depends almost entirely on the mechanical dissipation of tidal energy in ice to produce heat, the mechanism(s) of which remain poorly understood. In deformation experiments, we combine steady-state creep and low-frequency, small-strain periodic loading, similar conditions in which tectonics and tidal flexing are occurring simultaneously. The data reveal that the relevant, power-law attenuation in ice (i) is non-linear, depending on strain amplitude, (ii) is independent of grain size, and (iii) exceeds in absorption the prediction of the Maxwell solid model by an order of magnitude. The Maxwell solid model is widely used to model the dynamics of planetary ice shells, so this discrepancy is important. The prevalent understanding of damping in the geophysical context is that it is controlled by chemical diffusion on grain boundaries, which renders attenuation strongly dependent on grain size. In sharp contrast, our results indicate instead the importance of intracrystalline dislocations and their spatial interactions as the critical structural variable affecting dissipation. These dislocation structures are controlled by stress and realized by accumulated plastic strain. Thus, tectonics and attenuation are coupled, which, beyond the icy satellite/subsurface ocean problem, has implications also for understanding the attenuation of seismic waves in deforming regions of the Earth's upper mantle.
Sidles, J A; Dougherty, W M; Chao Shang Huang
2000-01-01
A general theory of thermal magnetic fluctuations near conductive materials is developed; such fluctuations are the magnetic analog of Johnson noise. For realistic experiments in quantum computing and magnetic resonance force microscopy, the predicted relaxation can be rapid enough that substantial experimental care should be taken to minimize it. The same Hamiltonian matrix elements that govern fluctuation and dissipation are shown to also govern entanglement and renormalization, and a specific example of a fluctuation-dissipation-entanglement theorem is constructed.
Influence of bubble size and thermal dissipation on compressive wave attenuation in liquid foams
Monloubou, M.; Saint-Jalmes, A.; Dollet, B.; Cantat, I.
2015-11-01
Acoustic or blast wave absorption by liquid foams is especially efficient and bubble size or liquid fraction optimization is an important challenge in this context. A resonant behavior of foams has recently been observed, but the main local dissipative process is still unknown. In this paper, we evidence the thermal origin of the dissipation, with an optimal bubble size close to the thermal boundary layer thickness. Using a shock tube, we produce typical pressure variation at time scales of the order of the millisecond, which propagates in the foam in linear and slightly nonlinear regimes.
Hot nuclei-Landau theory, thermal fluctuations and dissipation
The basic ideas and theoretical methods used in the description of hot nuclei are reviewed. In particular, a macroscopic approach to shape transitions is discussed in the framework of the Landau theory in which the quadrupole shaps degress if freedom play the role of the order parameters. This theory describes the universal features of the nuclear shape evolution with temperature and spin. A unified description of fluctuations in all five quadrupole degress of freedom is introduced and plays an important role in the calculation of physical observables. A macroscopic approach to the giant dipole resonance (GDR) in hot nuclei is developed. With all parameters fixed by the zero temperature nuclear properties, the theory predicts both the GDR cross-section and angular anisotropy of the γ-rays in very good agreement with recent experiments. The intrinsic shape fluctuations are the main cause for the resonance broadening at higher temperatures, while the orientatin fluctuations are responsible for the observed attenuation in the angular anisotropy. Dissipation at finite temperature is discussed in the framework of a Langevin-like equation describing the time-dependent shape fluctuations. Non-adiabatic effects may cause motional narrowing of the resonance. (orig.)
Dissipative Bose–Einstein condensation in contact with a thermal reservoir
Caspar, S.; Hebenstreit, F.; Mesterházy, D.; Wiese, U.-J.
2016-07-01
We investigate the real-time dynamics of open quantum spin-1/2 or hardcore boson systems on a spatial lattice, which are governed by a Markovian quantum master equation. We derive general conditions under which the hierarchy of correlation functions closes such that their time evolution can be computed semi-analytically. Expanding our previous work (2016 Phys. Rev. A 93 021602) we demonstrate the universality of a purely dissipative quantum Markov process that drives the system of spin-1/2 particles into a totally symmetric superposition state, corresponding to a Bose–Einstein condensate of hardcore bosons. In particular, we show that the finite-size scaling behavior of the dissipative gap is independent of the chosen boundary conditions and the underlying lattice structure. In addition, we consider the effect of a uniform magnetic field as well as a coupling to a thermal bath to investigate the susceptibility of the engineered dissipative process to unitary and nonunitary perturbations. We establish the nonequilibrium steady-state phase diagram as a function of temperature and dissipative coupling strength. For a small number of particles N, we identify a parameter region in which the engineered symmetrizing dissipative process performs robustly, while in the thermodynamic limit N\\to ∞ , the coupling to the thermal bath destroys any long-range order.
Quantum fluctuations and thermal dissipation in higher derivative gravity
Roychowdhury, Dibakar
2015-01-01
In this paper, based on the $ AdS_{2}/CFT_{1} $ prescription, we explore the low frequency behavior of quantum two point functions for a special class of strongly coupled CFTs in one dimension whose dual gravitational counterpart consists of \\textit{extremal} black hole solutions in higher derivative theories of gravity defined over an asymptotically AdS space time. The quantum critical points thus described are supposed to correspond to a very large value of the dynamic exponent ($ z\\rightarrow \\infty $). In our analysis, we find that quantum fluctuations are enhanced due to the higher derivative corrections in the bulk which in turn increases the possibility of quantum phase transition near the critical point. On the field theory side, such higher derivative effects would stand for the corrections appearing due to the finite coupling in the gauge theory. Finally, we compute the coefficient of thermal diffusion at finite coupling corresponding to Gauss Bonnet corrected charged Lifshitz black holes in the bul...
Quantum fluctuations and thermal dissipation in higher derivative gravity
Dibakar Roychowdhury
2015-08-01
Full Text Available In this paper, based on the AdS2/CFT1 prescription, we explore the low frequency behavior of quantum two point functions for a special class of strongly coupled CFTs in one dimension whose dual gravitational counterpart consists of extremal black hole solutions in higher derivative theories of gravity defined over an asymptotically AdS spacetime. The quantum critical points thus described are supposed to correspond to a very large value of the dynamic exponent (z→∞. In our analysis, we find that quantum fluctuations are enhanced due to the higher derivative corrections in the bulk which in turn increases the possibility of quantum phase transition near the critical point. On the field theory side, such higher derivative effects would stand for the corrections appearing due to the finite coupling in the gauge theory. Finally, we compute the coefficient of thermal diffusion at finite coupling corresponding to Gauss Bonnet corrected charged Lifshitz black holes in the bulk. We observe an important crossover corresponding to z=5 fixed point.
Entransy dissipation-based constraint for optimization of heat exchanger networks in thermal systems
The Lagrange multiplier method is introduced for the global optimization of HENs (heat exchanger networks) with fixed layouts to give the optimal configuration of thermal systems that cannot be determined by other methods, such as HEN synthesis or linear programming method. A four-loop HEN with five heat exchangers and heat exchangers in thermodynamic systems are optimized as two examples from different perspectives. The first perspective is based on energy conservation where the energy and heat transfer equations act as the constraints in the Lagrange function. The second perspective is the heat transfer irreversibility where the entransy dissipation-based equation acts as the constraint. The entransy dissipation-based constraint eliminates the number of unknown intermediate fluid temperatures in the HENs and the corresponding number of constraints for HENs in thermal systems, which greatly simplifies the solution of optimization equations. Although the entropy generation-based equation can also act as a constraint, the intermediate fluid temperatures in the HENs cannot be eliminated because the entropy generation is a function of the absolute fluid temperature. As a result, the number of constraints is the same as when using energy conservation, so the optimization procedure for multi-component thermal systems cannot be simplified. - Highlights: • Lagrange multiplier method is a good option in thermal system optimization. • Entransy balance equation acts as a constraint without intermediate temperatures. • Entransy dissipation-based method greatly simplifies the optimization. • Entransy method is superior to traditional and entropy methods in some cases
Hu Jianjun; Li Tao; Li Jing
2014-01-01
Aimed to achieve good thermal stability of lithium batteries in electric vehicles under the conditions of high-power. This study established a three-dimensional, transient heat dissipation model for Lithium-ion battery package in the three-dimensional Cartesian coordinate system based on theoretical knowledge of thermodynamics and heat transfer. With the help of the numerical simulation theoretical of CFD, the flow and temperature field of force air cooling Lithium-ion battery pack was simula...
Use of thermal dissipation probes to estimate water loss of containerized landscape trees
Montague, Thayne; Kjelgren, Roger
2006-01-01
Granier style thermal dissipation probes (TDPs) have been used to estimate whole plant water use on a variety of tree and vine species. However, studies using TDPs and load cells (gravimetric water loss) to estimate water use of landscape tree species are rare. This research compared gravimetric water loss (extimated with load cells) of four containerized landscape tree species with water loss estimated with TDPs. Over a 66 day period, an experiment compared water loss of three established...
Lei, Huan; Baker, Nathan A.; Wu, Lei; Schenter, Gregory K.; Mundy, Christopher J.; Tartakovsky, Alexandre M.
2016-08-01
Thermal fluctuations cause perturbations of fluid-fluid interfaces and highly nonlinear hydrodynamics in multiphase flows. In this work, we develop a multiphase smoothed dissipative particle dynamics (SDPD) model. This model accounts for both bulk hydrodynamics and interfacial fluctuations. Interfacial surface tension is modeled by imposing a pairwise force between SDPD particles. We show that the relationship between the model parameters and surface tension, previously derived under the assumption of zero thermal fluctuation, is accurate for fluid systems at low temperature but overestimates the surface tension for intermediate and large thermal fluctuations. To analyze the effect of thermal fluctuations on surface tension, we construct a coarse-grained Euler lattice model based on the mean field theory and derive a semianalytical formula to directly relate the surface tension to model parameters for a wide range of temperatures and model resolutions. We demonstrate that the present method correctly models dynamic processes, such as bubble coalescence and capillary spectra across the interface.
Hu Jianjun
2014-01-01
Full Text Available Aimed to achieve good thermal stability of lithium batteries in electric vehicles under the conditions of high-power. This study established a three-dimensional, transient heat dissipation model for Lithium-ion battery package in the three-dimensional Cartesian coordinate system based on theoretical knowledge of thermodynamics and heat transfer. With the help of the numerical simulation theoretical of CFD, the flow and temperature field of force air cooling Lithium-ion battery pack was simulated with the heat source obtained from dynamic performance simulations of Pure Electric Vehicles (PEVs under 15% climbing conditions. For the issues of high temperature rise and large temperature difference, optimal programs to improve the cooling effect of Lithium-ion battery pack were proposed. Simulation results indicate that the optimal measures make heat dissipation well and temperature distribution uniform, which satisfies the application requirement in PEVs.
Daane, Abigail R; Vokos, Stamatis; Scherr, Rachel E
2014-01-01
Research has demonstrated that many students and some teachers do not consistently apply the conservation of energy principle when analyzing mechanical scenarios. In observing elementary and secondary teachers engaged in learning activities that require tracking and conserving energy, we find that challenges to energy conservation often arise in dissipative scenarios in which kinetic energy transforms into thermal energy (e.g., a ball rolls to a stop). We find that teachers expect that when they can see the motion associated with kinetic energy, they should be able to perceive the warmth associated with thermal energy. Their expectations are violated when the warmth produced is imperceptible. In these cases, teachers reject the idea that the kinetic energy transforms to thermal energy. Our observations suggest that apparent difficulties with energy conservation may have their roots in a strong and productive association between forms of energy and their perceptible indicators. We see teachers resolve these ch...
Heber, Ulrich; Soni, Vineet; Strasser, Reto J
2011-05-01
During desiccation, fluorescence emission and stable light-dependent charge separation in the reaction centers (RCs) of photosystem II (PSII) declined strongly in three different lichens: in Parmelia sulcata with an alga as the photobiont, in Peltigera neckeri with a cyanobacterium and in the tripartite lichen Lobaria pulmonaria. Most of the decline of fluorescence was caused by a decrease in the quantum efficiency of fluorescence emission. It indicated the activation of photoprotective thermal energy dissipation. Photochemical activity of the RCs was retained even after complete desiccation. It led to light-dependent absorption changes and found expression in reversible increases in fluorescence or in fluorescence quenching. Lowering the temperature changed the direction of fluorescence responses in P. sulcata. The observations are interpreted to show that reversible light-induced increases in fluorescence emission in desiccated lichens indicate the functionality of the RCs of PSII. Photoprotection is achieved by the drainage of light energy to dissipating centers outside the RCs before stable charge separation can take place. Reversible quenching of fluorescence by strong illumination is suggested to indicate the conversion of the RCs from energy conserving to energy dissipating units. This permits them to avoid photoinactivation. On hydration, re-conversion occurs to energy-conserving RCs. PMID:21029105
Papiernik, Sharon K; Yates, Scott R; Koskinen, William C; Barber, Brian
2007-10-17
Two-year field dissipation studies were conducted in three soil types in Minnesota to examine the processes affecting the dissipation of the herbicide isoxaflutole and its phytotoxic diketonitrile metabolite (DKN) under relatively cool, wet soil conditions. Plots of cuphea were treated with isoxaflutole and potassium bromide, a nonsorbed, nondegraded tracer. Replicate soil cores were collected six times during the growing season to a depth of 1 m, and the bromide or herbicide concentration was measured in each of five depth increments. The dissipation half-life (DT50) of isoxaflutole + DKN was 8-18 days in each soil. Bromide and herbicide concentrations were low at depths >40 cm throughout the study, and herbicide concentrations in soil 100 days after application were usually undetectable. Simulation modeling using Hydrus-1D for the loam soil suggested that plant uptake was an important mechanism of dissipation. PMID:17880161
On the viscous dissipation modeling of thermal fluid flow in a porous medium
Salama, Amgad
2011-02-24
The problem of viscous dissipation and thermal dispersion in saturated porous medium is numerically investigated for the case of non-Darcy flow regime. The fluid is induced to flow upward by natural convection as a result of a semi-infinite vertical wall that is immersed in the porous medium and is kept at constant higher temperature. The boundary layer approximations were used to simplify the set of the governing, nonlinear partial differential equations, which were then non-dimensionalized and solved using the finite elements method. The results for the details of the governing parameters are presented and investigated. It is found that the irreversible process of transforming the kinetic energy of the moving fluid to heat energy via the viscosity of the moving fluid (i.e.; viscous dissipation) resulted in insignificant generation of heat for the range of parameters considered in this study. On the other hand, thermal dispersion has shown to disperse heat energy normal to the wall more effectively compared with the normal diffusion mechanism. © 2011 Springer-Verlag.
Heber, Ulrich
2008-09-01
In order to survive sunlight in the absence of water, desiccation-tolerant green plants need to be protected against photooxidation. During drying of the chlorolichen Cladonia rangiformis and the cyanolichen Peltigera neckeri, chlorophyll fluorescence decreased and stable light-dependent charge separation in reaction centers of the photosynthetic apparatus was lost. The presence of light during desiccation increased loss of fluorescence in the chlorolichen more than that in the cyanolichen. Heating of desiccated Cladonia thalli, but not of Peltigera thalli, increased fluorescence emission more after the lichen had been dried in the light than after drying in darkness. Activation of zeaxanthin-dependent energy dissipation by protonation of the PsbS protein of thylakoid membranes was not responsible for the increased loss of chlorophyll fluorescence by the chlorolichen during drying in the light. Glutaraldehyde inhibited loss of chlorophyll fluorescence during drying. Desiccation-induced loss of chlorophyll fluorescence and of light-dependent charge separation are interpreted to indicate activation of a highly effective mechanism of photoprotection in the lichens. Activation is based on desiccation-induced conformational changes of a pigment-protein complex. Absorbed light energy is converted into heat within a picosecond or femtosecond time domain. When present during desiccation, light interacts with the structural changes of the protein providing increased photoprotection. Energy dissipation is inactivated and structural changes are reversed when water becomes available again. Reversibility of ultra-fast thermal dissipation of light energy avoids photo-damage in the absence of water and facilitates the use of light for photosynthesis almost as soon as water becomes available. PMID:18587600
Wills, P.; Iacocca, E.; Hoefer, M. A.
2016-04-01
The magnetic dissipative droplet is a strongly nonlinear wave structure that can be stabilized in a thin film ferromagnet exhibiting perpendicular magnetic anisotropy by use of spin transfer torque. These structures have been observed experimentally at room temperature, showcasing their robustness against noise. Here, we quantify the effects of thermal noise by deriving stochastic equations of motion for a droplet based on soliton perturbation theory. First, it is found that deterministic droplets are linearly unstable at large bias currents, subject to a drift instability. When the droplet is linearly stable, our framework allows us to analytically compute the droplet's generation linewidth and center variance. Additionally, we study the influence of nonlocal and Oersted fields with micromagnetic simulations, providing insight into their effect on the generation linewidth. These results motivate detailed experiments on the current and temperature-dependent linewidth as well as drift instability statistics of droplets, which are important figures-of-merit in the prospect of droplet-based applications.
On the sound attenuation in fluid due to the thermal diffusion and viscous dissipation
We review the sound attenuation in fluid due to the thermal diffusion and viscous dissipation and derive the formula of the sound attenuation coefficient in fluid by solving a fully thermally–mechanically coupled equation set. Problem occurring in Stokes–Kirchhoff relation, the well-known and widely used classical formula for sound attenuation coefficient, is therefore found and pointed out. The reason for its generation is analyzed and verified. An improved formula to replace Stokes–Kirchhoff relation is suggested and the typical case for the error in calculating sound pressure level (SPL) of attenuated sound wave in fluid between the two formulas is also given. - Highlights: • Problem with Stokes–Kirchhoff relation. • Generation reason of defect in Stokes–Kirchhoff relation. • An improved formula for sound attenuation coefficient in fluid. • Typical cases of the calculation error by Stokes–Kirchhoff relation
Auclair-Desrotour, P; Poncin-Lafitte, C Le
2015-01-01
Tidal dissipation in planets and stars is one of the key physical mechanisms driving the evolution of star-planet and planet-moon systems. Several signatures of its action are observed in planetary systems thanks to their orbital architecture and the rotational state of their components. Tidal dissipation inside the fluid layers of celestial bodies are intrinsically linked to the dynamics and the physical properties of the latter. This complex dependence must be characterized. We compute the tidal kinetic energy dissipated by viscous friction and thermal diffusion in a rotating local fluid Cartesian section of a star/planet/moon submitted to a periodic tidal forcing. The properties of tidal gravito-inertial waves excited by the perturbation are derived analytically as explicit functions of the tidal frequency and local fluid parameters (i.e. the rotation, the buoyancy frequency characterizing the entropy stratification, viscous and thermal diffusivities) for periodic normal modes. The sensitivity of the resul...
The thermal development of the hydrodynamically developing laminar flow of a viscoplastic fluid (fluid of Bingham) between two plane plates maintained at a constant temperature has been studied numerically. This analysis has shown the effect caused by inertia and the rheological behaviour of the fluid on the velocity, pressure and temperature fields. The effects of Bingham and Peclet numbers on the Nusselt values with the inclusion of viscous dissipation are also discussed. (authors)
Boualit, A.; Boualit, S. [Unite de recherche appliquee en energies renouvelables, Ghardaia (Algeria); Zeraibi, N. [Universite de Boumerdes, Faculte des hydrocarbures dept. Transport et equipement, Boumerdes (Algeria); Amoura, M. [Universite des Sciences et de la Technologie Houari Boumedienne, Faculte de Physique, Dept. Energetique, Alger (Algeria)
2011-01-15
The thermal development of the hydrodynamically developing laminar flow of a viscoplastic fluid (fluid of Bingham) between two plane plates maintained at a constant temperature has been studied numerically. This analysis has shown the effect caused by inertia and the rheological behaviour of the fluid on the velocity, pressure and temperature fields. The effects of Bingham and Peclet numbers on the Nusselt values with the inclusion of viscous dissipation are also discussed. (authors)
Cating, Emma E M; Pinion, Christopher W; Van Goethem, Erika M; Gabriel, Michelle M; Cahoon, James F; Papanikolas, John M
2016-01-13
Thermal management is an important consideration for most nanoelectronic devices, and an understanding of the thermal conductivity of individual device components is critical for the design of thermally efficient systems. However, it can be difficult to directly probe local changes in thermal conductivity within a nanoscale system. Here, we utilize the time-resolved and diffraction-limited imaging capabilities of ultrafast pump-probe microscopy to determine, in a contact-free configuration, the local thermal conductivity in individual Si nanowires (NWs). By suspending single NWs across microfabricated trenches in a quartz substrate, the properties of the same NW both on and off the substrate are directly compared. We find the substrate has no effect on the recombination lifetime or diffusion length of photogenerated charge carriers; however, it significantly impacts the thermal relaxation properties of the NW. In substrate-supported regions, thermal energy deposited into the lattice by the ultrafast laser pulse dissipates within ∼10 ns through thermal diffusion and coupling to the substrate. In suspended regions, the thermal energy persists for over 100 ns, and we directly image the time-resolved spatial motion of the thermal signal. Quantitative analysis of the transient images permits direct determination of the NW's local thermal conductivity, which we find to be a factor of ∼4 smaller than in bulk Si. Our results point to the strong potential of pump-probe microscopy to be used as an all-optical method to quantify the effects of localized environment and morphology on the thermal transport characteristics of individual nanostructured components. PMID:26629610
How does dissipation affect the transition from static to dynamic macroscopic friction?
Gershenzon, Naum I; Skinner, Thomas
2014-01-01
Description of the transitional process from a static to a dynamic frictional regime is a fundamental problem of modern physics. Previously we developed a model based on the well-known Frenkel-Kontorova model to describe dry macroscopic friction. Here this model has been modified to include the effect of dissipation in derived relations between the kinematic and dynamic parameters of a transition process. The main (somewhat counterintuitive) result is a demonstration that the rupture (i.e. detachment front) velocity of the slip pulse which arises during the transition does not depend on friction. The only parameter (besides the elastic and plastic properties of the medium) controlling the rupture velocity is the spatial distribution of the shear to normal stress ratio. In contrast to the rupture velocity, the slip velocity does depend on friction. The model we have developed describes these processes over a wide range of rupture and slip velocities (up to 7 orders of magnitude) allowing, in particular, the co...
García-Jaramillo, M; Redondo-Gómez, S; Barcia-Piedras, J M; Aguilar, M; Jurado, V; Hermosín, M C; Cox, L
2016-04-15
The presence of pesticides in surface and groundwater has grown considerably in the last decades as a consequence of the intensive farming activity. Several studies have shown the benefits of using organic amendments to prevent losses of pesticides from runoff or leaching. A particular soil from the Guadalquivir valley was placed in open air ponds and amended at 1 or 2% (w/w) with alperujo compost (AC), a byproduct from the olive oil industry. Tricyclazole dissipation, rice growth and microbial diversity were monitored along an entire rice growing season. An increase in the net photosynthetic rate of Oryza sativa plants grown in the ponds with AC was observed. These plants produced between 1100 and 1300kgha(-1) more rice than plants from the unamended ponds. No significant differences were observed in tricyclazole dissipation, monitored for a month in soil, surface and drainage water, between the amended and unamended ponds. The structure and diversity of bacteria and fungi communities were also studied by the use of the polymerase chain reaction denaturing gel electrophoresis (PCR-DGGE) from DNA extracted directly from soil samples. The banding pattern was similar for all treatments, although the density of bands varied throughout the time. Apparently, tricyclazole did not affect the structure and diversity of bacteria and fungi communities, and this was attributed to its low bioavailability. Rice cultivation under paddy field conditions may be more efficient under the effects of this compost, due to its positive effects on soil properties, rice yield, and soil microbial diversity. PMID:26849328
Organic amendments affecting sorption, leaching and dissipation of fungicides in soils.
Fernandes, María C; Cox, Lucía; Hermosín, María C; Cornejo, Juan
2006-12-01
Metalaxyl and tricyclazole are two fungicides widely used in Spain in vineyard and rice crops respectively. In this study an investigation has been made of the effect of three organic amendments [two commercial amendments, solid fertiormont (SF) and liquid fertiormont (LF), and a residue from the olive oil production industry, alperujo (OW)] on fungicide fate in soils. Changes in soil porosity on amendment were studied by mercury intrusion porosimetry, sorption-desorption studies were performed by the batch equilibration method, dissipation of metalaxyl and tricyclazole in the soil was studied at - 33 kPa moisture content and 20 degrees C and leaching was studied in hand-packed soil columns. Amendments with SF and LF reduced soil porosity, while OW increased porosity through an increase in pore volume in the highest range studied. Tricyclazole sorbed to soils to a much higher extent than metalaxyl. With some exceptions, sorption of both fungicides increased on amendment, especially in the case of SF-amended soils, which rendered the highest K(oc) values. In soils amended with the liquid amendment LF, sorption either remained unaffected or decreased, and this decrease was much higher in the case of metalaxyl and a soil with 70% clay. In this clay soil, amendment with OW, of very high soluble organic matter content, also decreased metalaxyl sorption. Tricyclazole is more persistent in soil than metalaxyl, and both fungicides were found to be more persistent in amended soils than in unamended soils. Leaching of metalaxyl and tricyclazole in soil columns was inversely related to sorption capacity. The low recoveries of tricyclazole in leachates and in soil columns when compared with metalaxyl, a less persistent fungicide, were attributed to diffusion into micropores and to increase in sorption with residence time in the soil, both processes favoured by the low mobility of tricyclazole. PMID:17051652
Kamel Hooman; Alireza Pourshaghaghy; Arash Ejlali
2006-01-01
The viscous dissipation effect on forced convection in a porous saturated circular tube with an isoflux wall is investigated on the basis of the Brinkman flow model.For the thermally developing region, a numerical study is reported while a perturbation analysis is presented to find expressions for the temperature profile and the Nusselt number for the fully developed region. The fully developed Nusselt number found by numerical solution for the developing region is compared with that of asymptotic analysis and a good degree of agreement is observed.
Motsumi, T. G.; Makinde, O. D.
2012-10-01
The effects of suction, viscous dissipation, thermal radiation and thermal diffusion are numerically studied on a boundary layer flow of nanofluids over a moving flat plate. The partial differential equations governing the motion are transformed into ordinary differential equations using similarity solutions, and are solved using the Runge-Kutta-Fehlberg method with the shooting technique. The effects of nanoparticle volume fraction, the type of nanoparticles, the radiation parameter, the Brinkman number, the suction/injection parameter and the relative motion of the plate on the nanofluids velocity, temperature, skin friction and heat transfer characteristics are graphically presented and then discussed quantitatively. A comparative study between the previously published and the present results in a limiting sense reveals excellent agreement between them.
STRONG TIDAL DISSIPATION IN SATURN AND CONSTRAINTS ON ENCELADUS' THERMAL STATE FROM ASTROMETRY
Lainey, Valery; Desmars, Josselin; Arlot, Jean-Eudes; Emelyanov, Nicolai; Remus, Francoise [IMCCE-Observatoire de Paris, UMR 8028 du CNRS, UPMC, 77 Av. Denfert-Rochereau, 75014 Paris (France); Karatekin, Oezguer [Royal Observatory of Belgium, Avenue Circulaire 3, 1180 Uccle, Bruxelles (Belgium); Charnoz, Sebastien; Mathis, Stephane [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/SAp Centre de Saclay, 91191 Gif-sur-Yvette (France); Le Poncin-Lafitte, Christophe [SyRTE-Observatoire de Paris, UMR 8630 du CNRS, 77 Av. Denfert-Rochereau, 75014 Paris (France); Tobie, Gabriel [Laboratoire de Planetologie et Geodynamique de Nantes, Universite de Nantes, CNRS, UMR 6112, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Zahn, Jean-Paul, E-mail: lainey@imcce.fr [LUTH-Observatoire de Paris, UMR 8102 du CNRS, 5 place Jules Janssen, 92195 Meudon Cedex (France)
2012-06-10
Tidal interactions between Saturn and its satellites play a crucial role in both the orbital migration of the satellites and the heating of their interiors. Therefore, constraining the tidal dissipation of Saturn (here the ratio k{sub 2}/Q) opens the door to the past evolution of the whole system. If Saturn's tidal ratio can be determined at different frequencies, it may also be possible to constrain the giant planet's interior structure, which is still uncertain. Here, we try to determine Saturn's tidal ratio through its current effect on the orbits of the main moons, using astrometric data spanning more than a century. We find an intense tidal dissipation (k{sub 2}/Q = (2.3 {+-} 0.7) Multiplication-Sign 10{sup -4}), which is about 10 times higher than the usual value estimated from theoretical arguments. As a consequence, eccentricity equilibrium for Enceladus can now account for the huge heat emitted from Enceladus' south pole. Moreover, the measured k{sub 2}/Q is found to be poorly sensitive to the tidal frequency, on the short frequency interval considered. This suggests that Saturn's dissipation may not be controlled by turbulent friction in the fluid envelope as commonly believed. If correct, the large tidal expansion of the moon orbits due to this strong Saturnian dissipation would be inconsistent with the moon formations 4.5 Byr ago above the synchronous orbit in the Saturnian subnebulae. But it would be compatible with a new model of satellite formation in which the Saturnian satellites formed possibly over a longer timescale at the outer edge of the main rings. In an attempt to take into account possible significant torques exerted by the rings on Mimas, we fitted a constant rate da/dt on Mimas' semi-major axis as well. We obtained an unexpected large acceleration related to a negative value of da/dt = -(15.7 {+-} 4.4) Multiplication-Sign 10{sup -15} AU day{sup -1}. Such acceleration is about an order of magnitude larger
Wullschleger, Stan D [ORNL; Childs, Kenneth W [ORNL; King, Anthony Wayne [ORNL; Hanson, Paul J [ORNL
2011-01-01
A variety of thermal approaches are used to estimate sap flux density in stems of woody plants. Models have proven valuable tools for interpreting the behavior of heat pulse, heat balance, and heat field deformation techniques, but have seldom been used to describe heat transfer dynamics for the heat dissipation method. Therefore, to better understand the behavior of heat dissipation probes, a model was developed that takes into account the thermal properties of wood, the physical dimensions and thermal characteristics of the probes, and the conductive and convective heat transfer that occurs due to water flow in the sapwood. Probes were simulated as aluminum tubes 20 mm in length and 2 mm in diameter, whereas sapwood, heartwood, and bark each had a density and water fraction that determined their thermal properties. Base simulations assumed a constant sap flux density with sapwood depth and no wounding or physical disruption of xylem beyond the 2 mm diameter hole drilled for probe installation. Simulations across a range of sap flux densities showed that the dimensionless quantity k defined as ( Tm T)/ T where Tm is the temperature differential ( T) between the heated and unheated probe under zero flow conditions was dependent on the thermal conductivity of the sapwood. The relationship between sap flux density and k was also sensitive to radial gradients in sap flux density and to xylem disruption near the probe. Monte Carlo analysis in which 1000 simulations were conducted while simultaneously varying thermal conductivity and wound diameter revealed that sap flux density and k showed considerable departure from the original calibration equation used with this technique. The departure was greatest for abrupt patterns of radial variation typical of ring-porous species. Depending on the specific combination of thermal conductivity and wound diameter, use of the original calibration equation resulted in an 81% under- to 48% over-estimation of sap flux density at
Chen Liang; Zhang Wan-Rong; Jin Dong-Yue; Shen Pei; Xie Hong-Yun; Ding Chun-Bao; Xiaa Ying; Sun Bo-Tao; Wang Ren-Qing
2011-01-01
method of non-uniform finger spacing is proposed to enhance thermal stability of a multiple finger power SiGe hererojunction bipolar transistor under different power dissipations. Temperature distribution on the emitter fingers of a multi-finger SiGe heterojunction bipolar transistor is studied using a numerical electro-thermal model. The results show that the SiGe heterojunction bipolar transistor with non-uniform finger spacing has a small temperature difference between fingers compared with a traditional uniform finger spacing heterojunction bipolar transistor at the same power dissipation. What is most important is that the ability to improve temperature non-uniformity is not weakened as power dissipation increases. So the method of non-uniform finger spacing is very effective in enhancing the thermal stability and the power handing capability of power device. Experimental results verify our conclusious.
A method of non-uniform finger spacing is proposed to enhance thermal stability of a multiple finger power SiGe heterojunction bipolar transistor under different power dissipations. Temperature distribution on the emitter fingers of a multi-finger SiGe heterojunction bipolar transistor is studied using a numerical electro-thermal model. The results show that the SiGe heterojunction bipolar transistor with non-uniform finger spacing has a small temperature difference between fingers compared with a traditional uniform finger spacing heterojunction bipolar transistor at the same power dissipation. What is most important is that the ability to improve temperature non-uniformity is not weakened as power dissipation increases. So the method of non-uniform finger spacing is very effective in enhancing the thermal stability and the power handing capability of power device. Experimental results verify our conclusions. (interdisciplinary physics and related areas of science and technology)
Heber, Ulrich; Bilger, Wolfgang; Türk, Roman; Lange, Otto L
2010-01-01
*The photobionts of lichens have previously been shown to reversibly inactivate their photosystem II (PSII) upon desiccation, presumably as a photoprotective mechanism. The mechanism and the consequences of this process have been investigated in the green algal lichen Lobaria pulmonaria. *Lichen thalli were collected from a shaded and a sun-exposed site. The activation of PSII was followed by chlorophyll fluorescence measurements. *Inactivation of PSII, as indicated by the total loss of variable fluorescence, was accompanied by a strong decrease of basal fluorescence (F(0)). Sun-grown thalli, as well as thalli exposed to low irradiance during drying, showed a larger reduction of F(0) than shade-grown thalli or thalli desiccated in the dark. Desiccation increased phototolerance, which was positively correlated to enhanced quenching of F(0). Quenching of F(0) could be reversed by heating, and could be inhibited by glutaraldehyde but not by the uncoupler nigericin. *Activation of energy dissipation, apparent as F(0) quenching, is proposed to be based on an alteration in the conformation of a pigment protein complex. This permits thermal energy dissipation and gives considerable flexibility to photoprotection. Zeaxanthin formation apparently did not contribute to the enhancement of photoprotection by desiccation in the light. Light-induced absorbance changes indicated the involvement of chlorophyll and carotenoid cation radicals. PMID:19863730
Statistical investigation and thermal properties for a 1-D impact system with dissipation
Díaz I., Gabriel; Livorati, André L. P.; Leonel, Edson D.
2016-05-01
The behavior of the average velocity, its deviation and average squared velocity are characterized using three techniques for a 1-D dissipative impact system. The system - a particle, or an ensemble of non-interacting particles, moving in a constant gravitation field and colliding with a varying platform - is described by a nonlinear mapping. The average squared velocity allows to describe the temperature for an ensemble of particles as a function of the parameters using: (i) straightforward numerical simulations; (ii) analytically from the dynamical equations; (iii) using the probability distribution function. Comparing analytical and numerical results for the three techniques, one can check the robustness of the developed formalism, where we are able to estimate numerical values for the statistical variables, without doing extensive numerical simulations. Also, extension to other dynamical systems is immediate, including time dependent billiards.
Measurements of mechanical thermal noise and energy dissipation in optical dielectric coatings
Li, Tianjun; Geitner, Mickael; Cagnoli, Gianpietro; Dolique, Vincent; Degallaix, Jérôme; Flaminio, Raffaele; Forest, Danièle; Granata, Massimo; Michel, Christophe; Morgado, Nazario; Pinard, Laurent; Bellon, Ludovic
2014-01-01
In recent years an increasing number of devices and experiments are shown to be limited by mechanical thermal noise. In particular sub-Hertz laser frequency stabilization and gravitational wave detectors, that are able to measure fluctuations of 1E-18 m/rtHz or less, are being limited by thermal noise in the dielectric coatings deposited on mirrors. In this paper we present a new measurement of thermal noise in low absorption dielectric coatings deposited on micro-cantilevers and we compare it with the results obtained from the mechanical loss measurements. For the first time the coating thermal noise is measured on a wide range of frequencies with high signal to noise ratio. In addition we present a novel technique to deduce the coating mechanical losses from the measurement of the mechanical quality factor which does not rely on the knowledge of the coating and substrate Young moduli. The dielectric coatings are deposited by ion beam sputtering. The results presented here give a frequency independent loss a...
Antonov, A. A.; Pankratov, A. L.; Yulin, A. V.; Mygind, Jesper
2000-01-01
The nonlinear dynamics of fluxons in Josephson systems with dispersion and thermal fluctuations is analyzed using the "quasiparticle" approach to investigate the influence of noise on the Cherenkov radiation effect. Analytical expressions for the stationary amplitude of the emitted radiation and its spectral distribution have been obtained in an annular geometry. It is demonstrated that noise reduces the amplitude of the radiated wave and broadens its spectrum. The effect of the radiated wave...
Legal and regulatory issues affecting aquifer thermal energy storage
Hendrickson, P.L.
1981-10-01
This document updates and expands the report with a similar title issued in October 1980. This document examines a number of legal and regulatory issues that potentially can affect implementation of the aquifer thermal energy storage (ATES) concept. This concept involves the storage of thermal energy in an underground aquifer until a later date when it can be effectively utilized. Either heat energy or chill can be stored. Potential end uses of the energy include district space heating and cooling, industrial process applications, and use in agriculture or aquaculture. Issues are examined in four categories: regulatory requirements, property rights, potential liability, and issues related to heat or chill delivery.
Antonov, A. A.; Pankratov, A. L.; Yulin, A. V.;
2000-01-01
The nonlinear dynamics of fluxons in Josephson systems with dispersion and thermal fluctuations is analyzed using the "quasiparticle" approach to investigate the influence of noise on the Cherenkov radiation effect. Analytical expressions for the stationary amplitude of the emitted radiation...... and its spectral distribution have been obtained in an annular geometry. It is demonstrated that noise reduces the amplitude of the radiated wave and broadens its spectrum. The effect of the radiated wave on the fluxon dynamics leads to a considerably smaller linewidth than observed in the usual flux flow...
On the thermal stability for a model reactive flow with viscous dissipation
We study the thermal stability of a reactive flow of a third-grade fluid with viscous heating and chemical reaction between two horizontal flat plates, where the top is moving with a uniform speed and the bottom plate is fixed in the presence of an imposed pressure gradient. This study is a natural continuation of earlier work on rectilinear shear flows. The governing equations are non-dimensionalized and the resulting system of equations are not coupled. An approximate explicit solution is found for the flow velocity using homotopy - perturbation technique and the range of validity is determined. After the velocity is known, the heat transport may be analyzed. It is found that the temperature solution depends on the non-Newtonian material parameter of the fluid, Λ, viscous heating parameter, Γ, and an exponent, m. Attention is focused upon the disappearance of criticality of the solution set {β, δ, θmax} for various values of Λ, Γ and m, and the numerical computations are presented graphically to show salient features of the solution set. (author)
Three different regimes of thermally activated dissipation behaviour were determined in the superconducting (Bi,Pb)2Sr2Ca2Cu3OX thin film in dependence on the external magnetic field. The negative electrostatic field applied to the film surface has been found to increase the activation energy of flux creep in relatively low magnetic fields. The upper critical magnetic field determined from resistive measurements increases in the vicinity of superconducting transition temperature under the influence of the electrostatic field. (orig.)
How Do Thermal Recovery Methods Affect Wettability Alteration?
Abhishek Punase
2014-01-01
Full Text Available We will investigate the effect of temperature on wettability. First, we will list and summarize the different schools of thoughts from previous literature describing wettability changes for sandstone and carbonate reservoirs at elevated temperature. Next, we will describe the properties that affect wettability: how they alter wettability and how they are affected by temperature. After that, we will present indications of wettability changes and current wettability measurement techniques. Following this, case studies describing how wettability change influences reservoir characteristics and field performance during thermal recovery processes will be discussed. The thermal recovery methods included in the case studies were steam flooding, cyclic steam injection, hot water flooding, and in situ combustion. The main and very important take away from this study is that temperature induced wettability change is determined by many possible mechanisms combined together and not by just one or two phenomena occurring simultaneously. Finally, we will propose a reasonable scheme for wettability alteration during dry forward combustion, which needs further investigation.
Factors affecting static stratification of thermal water storage
AlMarafie, A. (Mechanical Engineering Dept., Kuwait Univ., Kuwait City (KW)); Moustafa, S.M. (Mechanical Engineering Dept., California Polytechnic State Univ., San Luis Obispo, CA (US)); Al-Kandarie, A. (Energy Dept., Kuwait Institute for Scientific Research, Kuwait City (KW))
1989-01-01
The thermal shortage is a key component of any successful solar thermal system. A good thermal storage should allow minimum thermal energy losses while permitting the highest possible extraction efficiency of the stored thermal energy. Despite the many available examples of successful designs of solar thermal storage tanks, the static behavior of the solar thermal storage is not fully understood. Among the many factors influencing such behavior are heat losses, tank geometry, dead zones, and tank wall material. In this study, laboratory-scale models with different geometries were built for the purpose of examining thermal behavior during the period after charging. During this period, called the thermal diffusion period, the extraction efficiency was temporarily decreased until natural stratification was achieved. After the thermal period, the extraction efficiency decreased primarily as a result of thermal losses to the environment and thermal degradation caused by the storage tank walls. Increasing the ratio of length to diameter up to 3 or 4 significantly increases the extraction efficiency. Storages with length-to-diameter ratios larger than 4 are not desirable because the added cost does not result in improvement of the thermal extraction efficiency.
Factors affecting thermal infrared images at selected field sites
A thermal infrared (TIR) survey was conducted to locate surface ordnance in and around the Naval Ordnance Disposal Area, and a thermal anomaly was found. This report documents studies conducted to identify the position of cause of the thermal anomaly. Also included are results of a long path Fourier transform infrared survey, soil sampling activities, soil gas surveys, and buried heater studies. The results of these studies indicated that the thermal anomaly was caused by a gravel pad, which had thermal properties different than those of the surrounding soil. Results from this investigation suggest that TIR is useful for locating surface objects having a high thermal inertia compared to the surrounding terrain, but TIR is of very limited use for characterizing buried waste or other similar buried objects at the INEL
Factors affecting thermal infrared images at selected field sites
Sisson, J.B.; Ferguson, J.S.
1993-07-01
A thermal infrared (TIR) survey was conducted to locate surface ordnance in and around the Naval Ordnance Disposal Area, and a thermal anomaly was found. This report documents studies conducted to identify the position of cause of the thermal anomaly. Also included are results of a long path Fourier transform infrared survey, soil sampling activities, soil gas surveys, and buried heater studies. The results of these studies indicated that the thermal anomaly was caused by a gravel pad, which had thermal properties different than those of the surrounding soil. Results from this investigation suggest that TIR is useful for locating surface objects having a high thermal inertia compared to the surrounding terrain, but TIR is of very limited use for characterizing buried waste or other similar buried objects at the INEL.
Campos, Huitziméngari; Trejo, Carlos; Peña-Valdivia, Cecilia B; García-Nava, Rodolfo; Conde-Martínez, F Víctor; Cruz-Ortega, Ma Del Rocío
2014-10-01
Agave salmiana Otto ex Salm-Dyck, a crassulacean acid metabolism plant that is adapted to water-limited environments, has great potential for bioenergy production. However, drought stress decreases the requirement for light energy, and if the amount of incident light exceeds energy consumption, the photosynthetic apparatus can be injured, thereby limiting plant growth. The objective of this study was to evaluate the effects of drought and re-watering on the photosynthetic efficiency of A. salmiana seedlings. The leaf relative water content and leaf water potential decreased to 39.6 % and -1.1 MPa, respectively, over 115 days of water withholding and recovered after re-watering. Drought caused a direct effect on photosystem II (PSII) photochemistry in light-acclimated leaves, as indicated by a decrease in the photosynthetic electron transport rate. Additionally, down-regulation of photochemical activity occurred mainly through the inactivation of PSII reaction centres and an increased thermal dissipation capacity of the leaves. Prompt fluorescence kinetics also showed a larger pool of terminal electron acceptors in photosystem I (PSI) as well as an increase in some JIP-test parameters compared to controls, reflecting an enhanced efficiency and specific fluxes for electron transport from the plastoquinone pool to the PSI terminal acceptors. All the above parameters showed similar levels after re-watering. These results suggest that the thermal dissipation of excess energy and the increased energy conservation from photons absorbed by PSII to the reduction of PSI end acceptors may be an important acclimation mechanism to protect the photosynthetic apparatus from over-excitation in Agave plants. PMID:24798124
How Do Thermal Recovery Methods Affect Wettability Alteration?
Abhishek Punase; Amy Zou; Riza Elputranto
2014-01-01
We will investigate the effect of temperature on wettability. First, we will list and summarize the different schools of thoughts from previous literature describing wettability changes for sandstone and carbonate reservoirs at elevated temperature. Next, we will describe the properties that affect wettability: how they alter wettability and how they are affected by temperature. After that, we will present indications of wettability changes and current wettability measurement techniques. Foll...
Waves in vertically inhomogeneous dissipative atmosphere
Dmitrienko, I S
2015-01-01
A method of construction of solution for acoustic-gravity waves (AGW) above a wave source, taking dissipation throughout the atmosphere into account (Dissipative Solution above Source, DSAS), is proposed. The method is to combine three solutions for three parts of the atmosphere: an analytical solution for the upper isothermal part and numerical solutions for the real non-isothermal dissipative atmosphere in the middle part and for the real non-isothermal small dissipation atmosphere in the lower one. In this paper the method has been carried out for the atmosphere with thermal conductivity but without viscosity. The heights of strong dissipation and the total absorption index in the regions of weak and average dissipation are found. For internal gravity waves the results of test calculations for an isothermal atmosphere and calculations for a real non-isothermal atmosphere are shown in graphical form. An algorithm and appropriate code to calculate DSAS, taking dissipation due to finite thermal conductivity i...
Pahlavani, M. R.; Mirfathi, S. M.
2016-04-01
The incorporation of the four-dimensional Langevin equations led to an integrative description of fission cross-section, fragment mass distribution and the multiplicity and energy distribution of prompt neutrons and γ-rays in the thermal neutron-induced fission of 239Pu. The dynamical approach presented in this paper thoroughly reproduces several experimental observables of the fission process at low excitation energy.
Hydraulic modeling of thermal discharges into shallow, tidal affected streams
A two-unit nuclear fired power plant is being constructed in western Washington state. Blowdown water from cooling towers will be discharged into the Chehalis River nearby. The location of a diffuser is some 21 miles upriver from Grays Harbor on the Pacific Ocean. Because the Chehalis River is classified as an excellent stream from the standpoint of water quality, State regulatory agencies required demonstration that thermal discharges would maintain water quality standards within fairly strict limits. A hydraulic model investigation used a 1:12 scale, undistorted model of a 1300-foot river reach in the vicinity of the diffuser. The model scale was selected to insure fully turbulent flows both in the stream and from the diffuser (Reynolds similitude). Model operation followed the densimetric Froude similitude. Thermistors were employed to measure temperatures in the model; measurements were taken by computer command and such measurements at some 250 positions were effected in about 2.5 seconds
Study of thermal stress in heat affected zones during welding
The importance of applications of welding in the nuclear industry leads to the study of the main problem concerning metal welding: sensibility to cracking. The development of computation methods allows the numerical simulation of welding effects. Due to the complexity of this problem, it is divided in three steps: thermal, metallurgical and mechanical calculus. Interactions between the 3 steps are examined. Mathematical models necessary to get residual stress (i.e. stress remaining when welding is completed and structure at ambient temperature) are described. Then parameters for metallurgical structure determination are given and compared to experiments. A508 and A533 type steels of primary coolant circuit of PWR reactors are taken as examples and the numerical simulation of a test is presented
Joaquín Zueco; O. Anwar Bég; L.M. López-Ochoa
2011-01-01
Network simulation method (NSM) is used to solve the laminar heat and mass transfer of an electricallyconducting, heat generating/absorbing fluid past a perforated horizontal surface in the presence of viscous and Joule heating problem. The governing partial differential equations are non-dimensionalized and transformed into a system of nonlinear ordinary differential similarity equations, in a single independent variable, η. The resulting coupled, nonlinear equations are solved under appropriate transformed boundary conditions. Computations are performed for a wide range of the governing flow parameters, viz Prandtl number, thermophoretic coefficient (a function of Knudsen number), thermal conductivity parameter, wall transpiration parameter and Schmidt number. The numerical details are discussed with relevant applications. The present problem finds applications in optical fiber fabrication, aerosol filter precipitators, particle deposition on hydronautical blades, semiconductor wafer design, thermo-electronics and problems including nuclear reactor safety.
The purpose of this study was to characterize a change in Non-photochemical quenching (NPQ) upon exposure to ultraviolet-B (UV-B), the xanthophyll cycle-dependent and -independent NPQs were compared in Cucumis sativus, Lycopersicum esculentum, and Arabidopsis thaliana leaves. The xanthophyll cycle-dependent NPQ was dramatically but reversibly suppressed by UV-B radiation. This suppression was correlated more strongly with a marked decrease in photosynthetic electron transport rather than changes in xanthophyll cycle enzymes such as violaxanthin de-epoxidase and zeaxanthin epoxidase. Accordingly, the UV-B-induced suppression of NPQ cannot be attributed to changes in expressions of violaxanthin de-epoxidase (VDE) and zeaxanthin epoxidase (ZEP). However, suppression of the xanthophyll cycle-dependent NPQ could only account for the 77 K fluorescence emission spectra of thylakoid membranes and the increased level of 1O2 production, but not for the decreased levels of hydroxyl radical O2- production and H2O2 scavenging. These results suggest that a gradual reduction of H2O2 scavenging activity as well as a transient and reversible suppression of thermal energy dissipation may contribute differentially to increased photooxidative damages in cucumber, tomato, and Arabidopsis plants after acute exposure to UV-B radiation. (author)
Thermal fluctuations affect the transcriptome through mechanisms independent of average temperature.
Sørensen, Jesper Givskov; Schou, Mads Fristrup; Kristensen, Torsten Nygaard; Loeschcke, Volker
2016-01-01
Terrestrial ectotherms are challenged by variation in both mean and variance of temperature. Phenotypic plasticity (thermal acclimation) might mitigate adverse effects, however, we lack a fundamental understanding of the molecular mechanisms of thermal acclimation and how they are affected by fluctuating temperature. Here we investigated the effect of thermal acclimation in Drosophila melanogaster on critical thermal maxima (CTmax) and associated global gene expression profiles as induced by two constant and two ecologically relevant (non-stressful) diurnally fluctuating temperature regimes. Both mean and fluctuation of temperature contributed to thermal acclimation and affected the transcriptome. The transcriptomic response to mean temperatures comprised modification of a major part of the transcriptome, while the response to fluctuations affected a much smaller set of genes, which was highly independent of both the response to a change in mean temperature and to the classic heat shock response. Although the independent transcriptional effects caused by fluctuations were relatively small, they are likely to contribute to our understanding of thermal adaptation. We provide evidence that environmental sensing, particularly phototransduction, is a central mechanism underlying the regulation of thermal acclimation to fluctuating temperatures. Thus, genes and pathways involved in phototransduction are likely of importance in fluctuating climates. PMID:27487917
Kishore P.M.
2012-01-01
Full Text Available This investigation is undertaken to study the hydromagnetic flow of a viscous incompressible fluid past an oscillating vertical plate embedded in a porous medium with radiation, viscous dissipation and variable heat and mass diffusion. Governing equations are solved by unconditionally stable explicit finite difference method of DuFort - Frankel’s type for concentration, temperature, vertical velocity field and skin - friction and they are presented graphically for different values of physical parameters involved. It is observed that plate oscillation, variable mass diffusion, radiation, viscous dissipation and porous medium affect the flow pattern significantly.
Hamada, Joël; Pétrissans, Anélie; Mothe, Frédéric; Ruelle, Julien; Pétrissans, Mathieu; Gérardin, Philippe
2016-01-01
International audience AbstractKey messageThermogravimetric analysis, performed on small samples of earlywood (EW) or latewood (LW), indicated that earlywood is more susceptible to thermal degradation than latewood. These results suggest a direct relationship between wood density (which depends on the EW/LW ratio and indirectly on silviculture) and the response of wood during thermo-modification processes.ContextOne of the main difficulties in developing thermo-modified wood products at an...
Tamaraukuro Tammy Amasuomo
2016-04-01
Full Text Available The study investigated the relationship between students’ perceived thermal discomfort and stress behaviours affecting their learning in lecture theatres in the humid tropics. Two lecture theatres, LTH-2 and 3, at the Niger Delta University, Nigeria, were used for the study. Two groups of students from the Faculties of Agriculture and Engineering and the Department of Technology Education constituted the population. The sample size selected through random sampling for Groups A and B was 210 and 370 students, respectively. Objective and self-report instruments were used for data collection. The objective instrument involved physical measurement of the two lecture theatres and of the indoor temperature, relative humidity and air movement. The self-report instrument was a questionnaire that asked for the students perceived indoor thermal discomfort levels and the effect of indoor thermal comfort level on perceived stress behaviours affecting their learning. The objective indoor environmental data indicated thermal discomfort with an average temperature of 29–32 °C and relative humidity of 78% exceeding the ASHARE [1] and Olgyay [2].The students’ experienced a considerable level of thermal discomfort and also perceived that stress behaviours due to thermal discomfort affected their learning. Further, there were no significant differences in the perceived thermal discomfort levels of the two groups of students in LTH-2 and 3. Furthermore, stress behaviours affecting learning as perceived by the two groups of students did not differ significantly. In addition, no correlation existed between the perceived indoor thermal discomfort levels and stress behaviour levels affecting learning for students in LTH-2, because the arousal level of the students in the thermal environment was likely higher than the arousal level for optimal performance [3,4]. However, a correlation existed in the case of students in LTH-3, which was expected because it only
Fejer, M M; Cagnoli, G; Crooks, D R M; Gretarsson, A M; Harry, G M; Hough, J; Penn, S D; Sneddon, P H; Vyatchanin, S P
2004-01-01
The displacement noise in the test mass mirrors of interferometric gravitational wave detectors is proportional to their elastic dissipation at the observation frequencies. In this paper, we analyze one fundamental source of dissipation in thin coatings, thermoelastic damping associated with the dissimilar thermal and elastic properties of the film and the substrate. We obtain expressions for the thermoelastic dissipation factor necessary to interpret resonant loss measurements, and for the spectral density of displacement noise imposed on a Gaussian beam reflected from the face of a coated mass. The predicted size of these effects is large enough to affect the interpretation of loss measurements, and to influence design choices in advanced gravitational wave detectors.
Richter-Boix, Alex; Katzenberger, Marco; Duarte, Helder; Quintela, María; Tejedo, Miguel; Laurila, Anssi
2015-08-01
Although temperature variation is known to cause large-scale adaptive divergence, its potential role as a selective factor over microgeographic scales is less well-understood. Here, we investigated how variation in breeding pond temperature affects divergence in multiple physiological (thermal performance curve and critical thermal maximum [CTmax]) and life-history (thermal developmental reaction norms) traits in a network of Rana arvalis populations. The results supported adaptive responses to face two main constraints limiting the evolution of thermal adaptation. First, we found support for the faster-slower model, indicating an adaptive response to compensate for the thermodynamic constraint of low temperatures in colder environments. Second, we found evidence for the generalist-specialist trade-off with populations from colder and less thermally variable environments exhibiting a specialist phenotype performing at higher rates but over a narrower range of temperatures. By contrast, the local optimal temperature for locomotor performance and CTmax did not match either mean or maximum pond temperatures. These results highlight the complexity of the adaptive multiple-trait thermal responses in natural populations, and the role of local thermal variation as a selective force driving diversity in life-history and physiological traits in the presence of gene flow. PMID:26118477
Quantum state preparation using dissipation
Full text: We investigate the possibility of using a dissipative process to prepare a quantum system in a desired state. We derive for any multipartite pure state a dissipative process for which this state is the unique stationary state and solve the corresponding master equation analytically. For certain states, like the cluster states, we use this process to show that the jump operators can be chosen quasi-locally, i.e. they act non-trivially only on a few, neighboring qubits. We demonstrate the general formalism by considering MPS-PEPS states. In particular, we show that the ground state of the AKLT-model can be prepared employing a quasi-local dissipative process. Furthermore, we discuss a dissipatively driven Bose-Einstein condensate, where for non-interacting atoms a pure state exhibiting long range order is generated as the steady state by quasi-local coupling to an environment with finite correlation length. Applying standard linearization schemes in the weakly interacting situations, allows us to determine the solution of the master equation, revealing a steady state with properties similar to bosons in thermal contact to a heat bath. Furthermore, we consider a special class of states, called locally maximally entangleable states and discuss their applications for quantum information tasks. The generation of those states using either dissipative processes, or unitary evolutions is presented. (author)
Legal and regulatory issues affecting the aquifer thermal energy storage concept
Hendrickson, P.L.
1980-10-01
A number of legal and regulatory issus that potentially can affect implementation of the Aquifer Thermal Energy Storage (ATES) concept are examined. This concept involves the storage of thermal energy in an underground aquifer until a later date when it can be effectively utilized. Either heat energy or chill can be stored. Potential end uses of the energy include district space heating and cooling, industrial process applications, and use in agriculture or aquaculture. Issues are examined in four categories: regulatory requirements, property rights, potential liability, and issues related to heat or chill delivery.
Experimental Study Abour How the Thermal Plume Affects the Air Quality a Person Breathes
Olmedo, Inés; Nielsen, Peter V.; Ruiz de Adana, Manuel;
2011-01-01
.10 m (length), 3.2 m (width), 2.7 m (height). The incoming air is distributed through a wall-mounted displacement diffuser. A breathing thermal manikin exhaling through the mouth and inhaling through the nose was used. A tracer gas, N2O, was used to simulate the gaseous substances, which might be......The Personal Micro Environment (PME) depends directly on the heat transfer in the surrounding environment. For the displacement ventilation systems the convective transport mechanism, which is found in the thermal plume around a person, influences the human exposure to pollutants. The aim of this...... research is to increase the knowledge of how the thermal plume generated by a person affects the PME and therefore the concentration of contaminants in the inhalation area. An experimental study in a displacement ventilation room was carried out. Experiments were developed in a full scale test chamber 4...
Bird population trends are linearly affected by climate change along species thermal ranges
Jiguet, Frédéric; Devictor, Vincent; Ottvall, Richard; Van Turnhout, Chris; van der Jeugd, Henk; Lindström, Åke
2010-01-01
Beyond the effects of temperature increase on local population trends and on species distribution shifts, how populations of a given species are affected by climate change along a species range is still unclear. We tested whether and how species responses to climate change are related to the populations locations within the species thermal range. We compared the average 20 year growth rates of 62 terrestrial breeding birds in three European countries along the latitudinal gradient of the spec...
Analysing Thermal Response Test Data Affected by Groundwater Flow and Surface Temperature Change
Verdoya, Massimo; Imitazione, Gianmario; Chiozzi, Paolo; Orsi, Marco; Armadillo, Egidio
2014-05-01
Tests that record the underground temperature variation due to a constant heat injected into a borehole (or extracted from it) by means of a carrier fluid are routinely performed to infer subsurface thermal conductivity and borehole thermal resistance, which are needed to size geothermal heat pump systems. The most popular model to analyse temperature-time curves obtained from these tests is the infinite line source (ILS). This model gives appropriate estimations of thermal parameters only if particular hydro-geological conditions are fulfilled. Several flaws can however affect data interpretation with ILS, which is based on strong assumptions like those of a purely conductive heat transfer regime in a homogeneous medium, no vertical heat flow and infinite length of the borehole. Other drawbacks can arise from the difficulty in the proper thermal insulation of the test equipment, and consequently with oscillations of the carrier fluid temperature due to surface temperature changes. In this paper, we focused on the treatment of thermal response test data when both advection and periodic changes of surface temperature occur. We used a moving line source model to simulate temperature-time signals under different hypothesis of Darcy velocity and thermal properties. A random noise was added to the signal in order to mimic high frequency disturbances, possibly caused by equipment operating conditions and/or geological variability. The subsurface thermal conductivity, the Darcy velocity and the borehole thermal resistance were inferred by minimising the root mean square error between the synthetic dataset and the theoretical model. The optimisation was carried out with the Nelder-Mead algorithm, and thermal and hydraulic properties were determined by iterative reprocessing according to a trial-and-error procedure. The inferred thermal and hydraulic parameters are well consistent with the 'a priory' values, and the presence of noise in the synthetic data does not produce
Decker, Jeremy D.; Swain, Eric D.; Stith, Bradley M.; Langtimm, Catherine A.
2013-01-01
Everglades restoration activities may cause changes to temperature and salinity stratification at the Port of the Islands (POI) marina, which could affect its suitability as a cold weather refuge for manatees. To better understand how the Picayune Strand Restoration Project (PSRP) may alter this important resource in Collier County in southwestern Florida, the USGS has developed a three-dimensional hydrodynamic model for the marina and canal system at POI. Empirical data suggest that manatees aggregate at the site during winter because of thermal inversions that provide warmer water near the bottom that appears to only occur in the presence of salinity stratification. To study these phenomena, the environmental fluid dynamics code simulator was used to represent temperature and salinity transport within POI. Boundary inputs were generated using a larger two-dimensional model constructed with the flow and transport in a linked overland-aquifer density-dependent system simulator. Model results for a representative winter period match observed trends in salinity and temperature fluctuations and produce temperature inversions similar to observed values. Modified boundary conditions, representing proposed PSRP alterations, were also tested to examine the possible effect on the salinity stratification and temperature inversion within POI. Results show that during some periods, salinity stratification is reduced resulting in a subsequent reduction in temperature inversion compared with the existing conditions simulation. This may have an effect on POI’s suitability as a passive thermal refuge for manatees and other temperature-sensitive species. Additional testing was completed to determine the important physical relationships affecting POI’s suitability as a refuge.
Dissipation of acoustic-gravity waves: an asymptotic approach.
Godin, Oleg A
2014-12-01
Acoustic-gravity waves in the middle and upper atmosphere and long-range propagation of infrasound are strongly affected by air viscosity and thermal conductivity. To characterize the wave dissipation, it is typical to consider idealized environments, which admit plane-wave solutions. Here, an asymptotic approach is developed that relies instead on the assumption that spatial variations of environmental parameters are gradual. It is found that realistic assumptions about the atmosphere lead to rather different predictions for wave damping than do the plane-wave solutions. A modification to the Sutherland-Bass model of infrasound absorption is proposed. PMID:25480091
REVIEW ON THERMAL PROPERTIES OF NANOFLUIDS AND FACTORS AFFECTING THE SAME
PARUL SHARMA
2014-08-01
Full Text Available A steady amelioration in technology has raised research work for developing nanofluids as coolants in comparison to the conventionally used coolants. This article reflects upon a review of the thermo-physical properties of nanofluids and how various factors affect those properties. Addition of surfactants, operating temperature, duration of sonication, concentration of anoparticles and various other factors contribute towards changing the properties such as thermal conductivity and viscosity of nanofluids. Thus, a wholesome analysis of properties is essential for the future course of research and developmental work. The purpose of this review article is to highlight the content of articles published in this direction and guide a course for futuredevelopments.
Quantification of factors affecting thermally-induced bow in a CANDU fuel element simulator
Thermally induced bow, caused by a circumferential temperature distribution around a fuel element, was investigated in this study using a fuel element simulator. The objective was to identify the factors affecting CANDU fuel element bow induced by dryout as a result of some predicted reactor transients in which the maximum fuel temperature reaches 600 deg C. The results showed that circumferential temperature distribution, pellet-to-sheath mechanical interaction and creep were the major factors affecting bow. Transient bow increased with increasing diametral sheath temperature difference and with mechanical interaction between the pellet and the sheath. Permanent bow of the fuel element was observed in some tests which was the result of creep. Mechanical interaction between the sheath and pellet produced the stresses necessary for creep deformation. A simplified ABAQUS model was developed to explain the experimental findings and could be used to predict the bow behaviour of fuel elements during reactor transients, where the dry patches are of different sizes. (author)
Circulation and Dissipation on Hot Jupiters
Li, Jason
2010-01-01
Many global circulation models predict supersonic zonal winds and large vertical shears in the atmospheres of short-period jovian exoplanets. Using linear analysis and nonlinear local simulations, we investigate hydrodynamic dissipation mechanisms to balance the thermal acceleration of these winds. The adiabatic Richardson criterion remains a good guide to linear stability, although thermal diffusion allows some modes to violate it at very long wavelengths and very low growth rates. Nonlinearly, wind speeds saturate at Mach numbers $\\approx 2$ and Richardson numbers $\\lesssim 1/4$ for a broad range of plausible diffusivities and forcing strengths. Turbulence and vertical mixing, though accompanied by weak shocks, dominate the dissipation, which appears to be the outcome of a recurrent Kelvin-Helmholtz instability. An explicit shear viscosity, as well as thermal diffusivity, is added to ZEUS to capture dissipation outside of shocks. The wind speed is not monotonic nor single valued for shear viscosities larger...
Thermal study of welding for the characterization of the heat affected zones
Due to the local character of the fusion, the assemblage is submitted to mechanical processing under heat, undergoes withdrawals and is the residual constraint seat. These solicitations, fathered by the welding operation, determine the weldment final characteristics into mechanical and metallurgic view point. In this paper, we present a two-dimension quasi stationary model, to study heat transfers that happen during the welding at constant speed of thin metallic plates. The solution is justified for a small Biot number based on the metallic plate thickness and the convection heat exchange coefficient. This approach allows us from the knowledge of the assemblage thermal state to predict the Fusion (FZ) and the heat affected (HAZ) zones that are fragile zones of the structure welded. This study permit us the determination of the temperatures field, of any point with coordinates (ζ,Y,Z) and at any moment t, as well as the welding thermal cycle Θ=f(t), layout in a neighbour point of weldment at different welding speeds. This last informs us about the maximum temperature Θm reached in this point and which is needed for the metallurgic characterisation. The structural modification distribution in the weldment surroundings is determined from the thermal distribution Θm=f(y) that translates the maximum temperature variation reached in each point according to the distance y. This study also indicates the welding speed importance on the two ominous zones extents FZ and HAZ. (Author)
Affect of Air Leakage into a Thermal-Vacuum Chamber on Helium Refrigeration Heat Load
Garcia, Sam; Meagher, Daniel; Linza, Robert; Saheli, Fariborz; Vargas, Gerardo; Lauterbach, John; Reis, Carl; Ganni, Venkatarao (Rao); Homan, Jonathan
2008-01-01
NASA s Johnson Space Center (JSC) Building 32 houses two large thermal-vacuum chambers (Chamber A and Chamber B). Within these chambers are liquid nitrogen shrouds to provide a thermal environment and helium panels which operate at 20K to provide cryopumping. Some amount of air leakage into the chambers during tests is inevitable. This causes "air fouling" of the helium panel surfaces due to the components of the air that adhere to the panels. The air fouling causes the emittance of the helium panels to increase during tests. The increase in helium panel emittance increases the heat load on the helium refrigerator that supplies the 20K helium for those panels. Planning for thermal-vacuum tests should account for this increase to make sure that the helium refrigerator capacity will not be exceeded over the duration of a test. During a recent test conducted in Chamber B a known-size air leak was introduced to the chamber. Emittance change of the helium panels and the affect on the helium refrigerator was characterized. A description of the test and the results will be presented.
Ohmic Dissipation in Mini-Neptunes
Valencia, Diana; Pu, Michael
2015-12-01
In the quest of characterizing low-mass exoplanets, it is important to consider all sources that may contribute to the interpretation of planetary composition given mass and a radius measurements. While it has been firmly established that inferring the composition of super-Earths and mini-Neptunes suffers from the inherent problem of compositional degeneracy, the effect from ohmic dissipation on these planets and its connection to compositional interpretation has not been studied so far. Ohmic dissipation is arguably the leading theory that aims to explain the large radii seen in highly-irradiated exo-Jupiters. In this study, we determine the strength of ohmic dissipation on mini-Neptunes and its effect on their H/He envelope structure as a function of insolation temperature and planetary mass. We find that ohmic dissipation is strong enough to halt the contraction of mini-Neptunes during their thermal evolution and therefore, inflate their radii in comparison to planets that do not suffer dissipation. This means that the radius of highly irradiated of this class of planets may be explained by the presence of volatiles and ohmic dissipation. In other words, there is a trade-off between ohmic dissipation and H/He content for hot mini-Neptunes.
The fluctuation-dissipation dynamics of cosmological scalar fields
Bartrum, Sam; Rosa, Joao G
2014-01-01
We show that dissipative effects have a significant impact on the evolution of cosmological scalar fields, leading to friction, entropy production and field fluctuations. We explicitly compute the dissipation coefficient for different scalar fields within the Standard Model and some of its most widely considered extensions, in different parametric regimes. We describe the generic consequences of fluctuation-dissipation dynamics in the post-inflationary universe and analyze in detail two important effects. Firstly, we show that dissipative friction delays the process of spontaneous symmetry breaking and may even damp the the motion of a Higgs field sufficiently to induce a late period of warm inflation. Along with dissipative entropy production, this may parametrically dilute the abundance of dangerous thermal relics. Secondly, we show that dissipation can generate the observed baryon asymmetry without symmetry restoration, and we develop in detail a model of dissipative leptogenesis. We further show that this...
The physics of heat dissipation in micro-nano-scale devices
Heat dissipation in micro-nano-scale devices is one of the bottlenecks which hinder the further development of the semiconductor industry. A series of procedures should be performed to dissipate the heat generated by the electronic device to the environment, which involves the thermal transport across interfaces and high performance heat conducting materials. We first review the recent progress in the field of micro-nano-scale thermal transport in solids from both the theoretical and experimental approaches. In the area of thermal transport theory and computational methodology, the Boltzmann transport equation, molecular-dynamics simulation, and Green's function are discussed. For the thermal transport experiments, we present an introduction to scanning thermal microscopy which is used to measure the spatial temperature distribution of sample surfaces, as well as the ultra-fast thermoreflectance technique which is used to measure the thermal conductivity of thin films and thermal boundary resistance. Then we tackle the problem of heat transport across an interface, including the calculation of thermal boundary resistance and how this is affected by the electron-phonon interaction. Several new heat conducting materials are also discussed, including carbon-based materials, boron-nitride whose crystal structure is similar to that of graphene, polymer chains, and thermal interface materials. (authors)
Thermal DissiPation AnalYsis of EleCtriC motorCYCle Controller%电动摩托车控制器的散热性能分析
凌智勇; 缪友谊; 邢雷杰
2015-01-01
分析了电动摩托车控制器的主要热源金属———氧化物半导体场效应晶体管（MOS-FET）的功率损耗并进行了理论计算，根据控制器总散热热阻对控制器的散热底板进行热设计，运用 CFD 软件 FloEFD 对控制器整体的热设计进行数值分析，得出控制器的温度分布。针对控制器最大功率损耗下的散热性能，分析了散热底板上的不同散热翅片参数对控制器整体温度分布的影响。实验结果表明：针对控制热散热性能的仿真误差小于10%，验证了仿真的合理性，优化后的散热底板可以满足控制器的散热需求。%AbstraCt:The power loss of the metal oxide semiconductor field effect transistor(MOSFET)in elec-tric motorcycle controller was calculated and analyzed. The controller thermal baseplate was designed according to the total thermal resistance,and the controller temperature distribution was simulated by the FloEFD. Based on the controller heat dissipation performance under maximum power loss,the in-fluence of the different thermal fin parameters on controller temperature distribution was analyzed. The experimental results verify the rationality of simulation,and the simulation deviation of controller ther-mal performance is less than 10% . The optimized baseplate can meet the thermal dissipation require-ments of controller.
Dessie Hunegnaw
2015-01-01
Full Text Available The effects of variable viscosity and thermal conductivity on MHD heat transfer flow of viscous incompressible electrically conducting fluid near stagnation point flow on non-conducting stretching sheet in presence of uniform transfer magnetic field with heat source/sink and viscous dissipation has been analyzed. The governing partial differential equations are transformed into ordinary differential equations using a special form of Lie group transformations and then solved using Fourth order Runge-Kutta Method. Effects of different physical parameters on the flow and heat transfer characteristics are analyzed. Variations of different parameters on skin fiction coefficient-f′′(0 and temperature gradient −θ′(0 are presented in tabular form.
Najafi, Amin
2014-05-01
Using the Monte Carlo simulations, we have calculated mean-square fluctuations in statistical mechanics, such as those for colloids energy configuration are set on square 2D periodic substrates interacting via a long range screened Coulomb potential on any specific and fixed substrate. Random fluctuations with small deviations from the state of thermodynamic equilibrium arise from the granular structure of them and appear as thermal diffusion with Gaussian distribution structure as well. The variations are showing linear form of the Fluctuation-Dissipation Theorem on the energy of particles constitutive a canonical ensemble with continuous diffusion process of colloidal particle systems. The noise-like variation of the energy per particle and the order parameter versus the Brownian displacement of sum of large number of random steps of particles at low temperatures phase are presenting a markovian process on colloidal particles configuration, too.
Using the Monte Carlo simulations, we have calculated mean-square fluctuations in statistical mechanics, such as those for colloids energy configuration are set on square 2D periodic substrates interacting via a long range screened Coulomb potential on any specific and fixed substrate. Random fluctuations with small deviations from the state of thermodynamic equilibrium arise from the granular structure of them and appear as thermal diffusion with Gaussian distribution structure as well. The variations are showing linear form of the Fluctuation-Dissipation Theorem on the energy of particles constitutive a canonical ensemble with continuous diffusion process of colloidal particle systems. The noise-like variation of the energy per particle and the order parameter versus the Brownian displacement of sum of large number of random steps of particles at low temperatures phase are presenting a markovian process on colloidal particles configuration, too.
Floris M van Beest
Full Text Available BACKGROUND: Empirical tests that link temperature-mediated changes in behaviour (activity and resource selection to individual fitness or condition are currently lacking for endotherms yet may be critical to understanding the effect of climate change on population dynamics. Moose (Alces alces are thought to suffer from heat stress in all seasons so provide a good biological model to test whether exposure to non-optimal ambient temperatures influence seasonal changes in body mass. Seasonal mass change is an important fitness correlate of large herbivores and affects reproductive success of female moose. METHODOLOGY/PRINCIPAL FINDINGS: Using GPS-collared adult female moose from two populations in southern Norway we quantified individual differences in seasonal activity budget and resource selection patterns as a function of seasonal temperatures thought to induce heat stress in moose. Individual body mass was recorded in early and late winter, and autumn to calculate seasonal mass changes (n = 52 over winter, n = 47 over summer. We found large individual differences in temperature-dependent resource selection patterns as well as within and between season variability in thermoregulatory strategies. As expected, individuals using an optimal strategy, selecting young successional forest (foraging habitat at low ambient temperatures and mature coniferous forest (thermal shelter during thermally stressful conditions, lost less mass in winter and gained more mass in summer. CONCLUSIONS/SIGNIFICANCE: This study provides evidence that behavioural responses to temperature have important consequences for seasonal mass change in moose living in the south of their distribution in Norway, and may be a contributing factor to recently observed declines in moose demographic performance. Although the mechanisms that underlie the observed temperature mediated habitat-fitness relationship remain to be tested, physiological state and individual variation in
Cooperstone, Jessica L; Francis, David M; Schwartz, Steven J
2016-11-01
Tangerine tomatoes, unlike red tomatoes, accumulate cis-lycopenes instead of the all-trans isomer. cis-Lycopene is the predominating isomeric form of lycopene found in blood and tissues. Our objective was to understand how thermal processing and lipid concentration affect carotenoid isomerisation and degradation in tangerine tomatoes. We conducted duplicated factorial designed experiments producing tangerine tomato juice and sauce, varying both processing time and lipid concentration. Carotenoids were extracted and analysed using high-performance liquid chromatography with photodiode array detection. Phytoene, phytofluene, ζ-carotene, neurosporene, tetra-cis-lycopene, all-trans-lycopene and other-cis-lycopenes were quantified. Tetra-cis-lycopene decreased with increasing heating time and reached 80% of the original level in sauce after processing times of 180min. All-trans-lycopene and other-cis-lycopenes increased with longer processing times. Total carotenoids and total lycopene decreased with increased heating times while phytoene and phytofluene were unchanged. These data suggest limiting thermal processing of tangerine tomato products if delivery of tetra-cis-lycopene is desirable. PMID:27211672
Spatial environmental heterogeneity affects plant growth and thermal performance on a green roof.
Buckland-Nicks, Michael; Heim, Amy; Lundholm, Jeremy
2016-05-15
Green roofs provide ecosystem services, including stormwater retention and reductions in heat transfer through the roof. Microclimates, as well as designed features of green roofs, such as substrate and vegetation, affect the magnitude of these services. Many green roofs are partially shaded by surrounding buildings, but the effects of this within-roof spatial environmental heterogeneity on thermal performance and other ecosystem services have not been examined. We quantified the effects of spatial heterogeneity in solar radiation, substrate depth and other variables affected by these drivers on vegetation and ecosystem services in an extensive green roof. Spatial heterogeneity in substrate depth and insolation were correlated with differential growth, survival and flowering in two focal plant species. These effects were likely driven by the resulting spatial heterogeneity in substrate temperature and moisture content. Thermal performance (indicated by heat flux and substrate temperature) was influenced by spatial heterogeneity in vegetation cover and substrate depth. Areas with less insolation were cooler in summer and had greater substrate moisture, leading to more favorable conditions for plant growth and survival. Spatial variation in substrate moisture (7%-26% volumetric moisture content) and temperature (21°C-36°C) during hot sunny conditions in summer could cause large differences in stormwater retention and heat flux within a single green roof. Shaded areas promote smaller heat fluxes through the roof, leading to energy savings, but lower evapotranspiration in these areas should reduce stormwater retention capacity. Spatial heterogeneity can thus result in trade-offs between different ecosystem services. The effects of these spatial heterogeneities are likely widespread in green roofs. Structures that provide shelter from sun and wind may be productively utilized to design higher functioning green roofs and increase biodiversity by providing habitat
Pal, Dulal, E-mail: dulalp123@rediffmail.com [Department of Mathematics, Siksha-Bhavana, Visva-Bharati University, Santiniketan, West Bengal-731235 (India); Mondal, Hiranmoy, E-mail: hiranmoymondal@yahoo.co.in [Department of Mathematics, Bengal Institute of Technology and Management, Santiniketan, West Bengal-731236 (India)
2013-04-15
The present paper deals with the thermophoresis particle deposition and Soret–Dufour effects on the convective flow, heat and mass transfer characteristics of an incompressible Newtonian electrically conducting fluid having temperature-dependent viscosity over a non-isothermal wedge in the presence of thermal radiation. The governing boundary layer equations are written into a dimensionless form by similarity transformations. The transformed coupled non-linear ordinary differential equations are solved numerically. The effects of various important physical parameters are analyzed in detail. It is found that the skin friction coefficient and the local Sherwood number increase with increase in the values of thermal radiation parameter in the presence of heat generation/absorption whereas reverse effect is seen on the local Nusselt number. -- Highlights: ► The effect of thermophoresis of particle deposition is to increase the concentration. ► Temperature in the thermal boundary layer decreases with increasing Soret number. ► Skin friction increases with increase in the thermal radiation and heat generation/absorption. ► Local Sherwood number increases with increase in the thermal radiation and heat generation/absorption. ► Local Nusselt number decreases with increase in the thermal radiation.
CIRCULATION AND DISSIPATION ON HOT JUPITERS
Many global circulation models predict supersonic zonal winds and large vertical shears in the atmospheres of short-period Jovian exoplanets. Using linear analysis and nonlinear local simulations, we investigate hydrodynamic dissipation mechanisms to balance the thermal acceleration of these winds. The adiabatic Richardson criterion remains a good guide to linear stability, although thermal diffusion allows some modes to violate it at very long wavelengths and very low growth rates. Nonlinearly, wind speeds saturate at Mach numbers ∼2 and Richardson numbers ∼-3 of the sound speed times the pressure scale height. Coarsening the numerical resolution can also increase the speed. Hence global simulations that are incapable of representing vertical turbulence and shocks, either because of reduced physics or because of limited resolution, may overestimate wind speeds. We recommend that such simulations include artificial dissipation terms to control the Mach and Richardson numbers and to capture mechanical dissipation as heat.
Highlights: • A practical thermal analysis of underground power cable system. • The geological measurements were performed for cable line placement location. • Dry zone formation effect included in soil and FTB thermal conductivity formula. • A simplified FEM model of underground power cable system. • The computational numerical code validation with ANSYS. - Abstract: This paper presents the thermal analysis of the underground transmission line, planned to be installed in one of the Polish power plants. The computations are performed by using the Finite Element Method (FEM) code, developed by the authors. The paper considers a system of three power cables arranged in flat (in-line) formation. The cable line is buried in the multilayered soil. The soil layers characteristic and thermal properties are determined from geological measurements. Different conditions of cable bedding are analyzed including power cables placement in the FTB or direct burial in a mother ground. The cable line burial depth, measured from the ground level, varies from 1 m to 2.5 m. Additionally, to include the effect of dry zones formation on the temperature distribution in cable line and surroundings, soil and FTB thermal conductivities are considered as a temperature-dependent. The proposed approach for determining the temperature-dependent thermal conductivity of soil layers is discussed in detail. The FEM simulation results are also compared with the results of the simulation that consider soil layers as homogeneous materials. Therefore, thermal conductivity is assumed to be constant for each layer. The results obtained by using the FEM code, developed by the authors, are compared with the results of ANSYS simulations, and a good agreement was found
张红平; 李牧; 阚明先; 王刚华; 种涛
2015-01-01
To study the pressure-specific volume (p-v )reference line and equation of state from the stress-strain curve of material at high pressure,the viscous dissipation due to loading strain rate and thermal dissipation due to irreversible heat conduction in quasi-isentropic compression experiment (ICE)were discussed and analyzed.A backward integration and forward integration method was used to analyze the data in laser driving and magnetic pressure driving ICE with different strain rates.For viscous dissipation,the sound speed,stress-strain curve,temperature and entropy production during loading were obtained,and the relations between high strain rate and these physical quantities were discussed.For thermal dissipation,through the calculation of the thermal conduction and SCG consti-tutive model,the variation of temperature and the corresponding yield strength,shear module and sound speed were presented.The results show that:in the laser driving ICE with a high strain rate of 10 8 s-1 ),the temperature variation caused by high strain rate is about 180 K,and the entropy produc-tion due to heat conduction is about 250 J/(kg·K);and in the magnetic pressure driving with a rela-tively low strain rate of 10 5 s-1 ,the entropy production is less than 8 J/(kg·K).%为获取高压下材料的纯热力学压力-比容参考线和完全物态方程,减去应力-应变曲线中的其它信息,对准等熵压缩实验中由加载应变率引起的黏性耗散和热传导引起的热耗散做了分析讨论。基于反积分计算和流体动力学积分计算相结合的方法,根据激光加载(约108 s-1)和磁驱动准等熵压缩(约105 s-1)的实验数据,对材料声速、应力-应变曲线、温度和熵增等物理量进行计算,分析了不同应变率与该物理量的关系；还对热传导和 SCG 本构模型进行了计算,分析了热传导引起的温度变化对材料屈服强度、剪切模量和拉格朗日声速的影响。结果表明：激光加载实验
Entanglement generated by dissipation
Krauter, Hanna; Jensen, Kasper; Wasilewski, Wojciech; Petersen, Jonas M; Cirac, J Ignacio; Polzik, Eugene S
2010-01-01
Entanglement is not only one of the most striking features of Quantum Mechanics but also an essential ingredient in most applications in the field of Quantum Information. Unfortunately, this property is very fragile. In experiments conducted so far, coupling of the system to a quantum mechanical environment, commonly referred to as dissipation, either inhibits entanglement or prevents its generation. In this Letter, we report on an experiment in which dissipation induces entanglement between two atomic objects rather than impairing it. This counter-intuitive effect is achieved by engineering the dissipation by means of laser- and magnetic fields, and leads to entanglement which is very robust and therefore long-lived. Our system consists of two distant macroscopic ensembles containing about 10^{12} atoms coupled to the environment composed of the vacuum modes of the electromagnetic field. The two atomic objects are kept entangled by dissipation at room temperature for about 0.015s. The prospects of using this...
Roles of Energy Dissipation in a Liquid-Solid Transition of Out-of-Equilibrium Systems
Komatsu, Yuta; Tanaka, Hajime
2015-07-01
Self-organization of active matter as well as driven granular matter in nonequilibrium dynamical states has attracted considerable attention not only from the fundamental and application viewpoints but also as a model to understand the occurrence of such phenomena in nature. These systems share common features originating from their intrinsically out-of-equilibrium nature, and how energy dissipation affects the state selection in such nonequilibrium states remains elusive. As a simple model system, we consider a nonequilibrium stationary state maintained by continuous energy input, relevant to industrial processing of granular materials by vibration and/or flow. More specifically, we experimentally study roles of dissipation in self-organization of a driven granular particle monolayer. We find that the introduction of strong inelasticity entirely changes the nature of the liquid-solid transition from two-step (nearly) continuous transitions (liquid-hexatic-solid) to a strongly discontinuous first-order-like one (liquid-solid), where the two phases with different effective temperatures can coexist, unlike thermal systems, under a balance between energy input and dissipation. Our finding indicates a pivotal role of energy dissipation and suggests a novel principle in the self-organization of systems far from equilibrium. A similar principle may apply to active matter, which is another important class of out-of-equilibrium systems. On noting that interaction forces in active matter, and particularly in living systems, are often nonconservative and dissipative, our finding may also shed new light on the state selection in these systems.
Dissipation in Relativistic Pair-Plasma Reconnection
Hesse, Michael; Zenitani, Seiji
2007-01-01
We present an investigation of the relativistic dissipation in magnetic reconnection. The investigated system consists of an electron-positron plasma. A relativistic generalization of Ohm's law is derived. We analyze a set of numerical simulations, composed of runs with and without guide magnetic field, and of runs with different species temperatures. The calculations indicate that the thermal inertia-based dissipation process survives in relativistic plasmas. For anti-parallel reconnection, it is found that the pressure tensor divergence remains the sole contributor to the reconnection electric field, whereas relativistic guide field reconnection exhibits a similarly important role of the bulk inertia terms.
无
2009-01-01
Based on entransy dissipation, the mean temperature difference of solenoid (electromagnet) with high thermal conductivity material inserted is deduced, which can be taken as the fundament for heat transfer optimization using the extremum principle of entransy dissipation. Then, the electromagnet working at steady state (constant magnetic field, constant heat generating rate per unit volume) is optimized for entransy dissipation minimization (i.e. mean temperature difference minimization) with and without volume constraint. Besides, the effect of high thermal conductivity material on the magnetic field is analyzed, and the minimum mean temperature versus volume and magnetic induction characteristic are also studied.
Machireddy Gnaneswara Reddy
2014-01-01
Full Text Available A two-dimensional mathematical model is presented for the laminar heat and mass transfer of an electrically-conducting, viscous and Joule (Ohmic heating fluid over an inclined radiate isothermal permeable surface in the presence of the variable thermal conductivity, thermophoresis and heat generation. The Talbot- Cheng-Scheffer-Willis formulation (1980 is used to introduce a thermophoretic coefficient into the concentration boundary layer equation. The governing partial differential equations are non-dimensionalized and transformed into a system of nonlinear ordinary differential similarity equations, in a single independent variable . The resulting coupled nonlinear equations are solved under appropriate transformed boundary conditions using the Runge-Kutta fourth order along with shooting method. Comparisons with previously published work are performed and the results are found to be in very good agreement. Computations are performed for a wide range of the governing flow parameters, viz., magnetic field parameter, thermophoretic coefficient (a function of Knudsen number, Eckert number (viscous heating effect, angle of inclination, thermal conductivity parameter, heat generation parameter and Schmidt number. The present problem finds applications in optical fiber fabrication, aerosol filter precipitators, particle deposition on hydronautical blades, semiconductor wafer design, thermo-electronics and magnetohydrodynamic energy generators.
Grant, Leah D.; Heever, Susan C.
2016-02-01
The mechanisms by which sensible heat fluxes (SHFs) alter cold pool characteristics and dissipation rates are investigated in this study using idealized two-dimensional numerical simulations and an environment representative of daytime, dry, continental conditions. Simulations are performed with no SHFs, SHFs calculated using a bulk formula, and constant SHFs for model resolutions with horizontal (vertical) grid spacings ranging from 50 m (25 m) to 400 m (200 m). In the highest resolution simulations, turbulent entrainment of environmental air into the cold pool is an important mechanism for dissipation in the absence of SHFs. Including SHFs enhances cold pool dissipation rates, but the processes responsible for the enhanced dissipation differ depending on the SHF formulation. The bulk SHFs increase the near-surface cold pool temperatures, but their effects on the overall cold pool characteristics are small, while the constant SHFs influence the near-surface environmental stability and the turbulent entrainment rates into the cold pool. The changes to the entrainment rates are found to be the most significant of the SHF effects on cold pool dissipation. SHFs may also influence the timing of cold pool-induced convective initiation by altering the environmental stability and the cold pool intensity. As the model resolution is coarsened, cold pool dissipation is found to be less sensitive to SHFs. Furthermore, the coarser resolution simulations not only poorly but sometimes wrongly represent the SHF impacts on the cold pools. Recommendations are made regarding simulating the interaction of cold pools with convection and the land surface in cloud-resolving models.
Dissipative structures and chaos
Mori, Hazime
1998-01-01
This monograph consists of two parts and gives an approach to the physics of open nonequilibrium systems. Part I derives the phenomena of dissipative structures on the basis of reduced evolution equations and includes Bénard convection and Belousov-Zhabotinskii chemical reactions. Part II discusses the physics and structures of chaos. While presenting a construction of the statistical physics of chaos, the authors unify the geometrical and statistical descriptions of dynamical systems. The shape of chaotic attractors is characterized, as are the mixing and diffusion of chaotic orbits and the fluctuation of energy dissipation exhibited by chaotic systems.
Weiss, Ulrich
2008-01-01
Major advances in the quantum theory of macroscopic systems, in combination with stunning experimental achievements, have brightened the field and brought it to the attention of the general community in natural sciences. Today, working knowledge of dissipative quantum mechanics is an essential tool for many physicists. This book - originally published in 1990 and republished in 1999 as an enlarged second edition - delves much deeper than ever before into the fundamental concepts, methods, and applications of quantum dissipative systems, including the most recent developments. In this third edi
张高胜; 丁晓红; 周吉
2015-01-01
在制造锂电池时，设定方法来估算锂电池内部温度是十分必要的。电池模块解决的主要问题是：保持电池模块内单体电池之间一致恒定的温度，避免达到电池本身所要求的温度峰值，引起电池性能的恶化及安全问题。通过单体电池的电化学反应来估算电池的热产生率，为实现这一目的，进行充放电实验来获得电池放电过程中的特性参数。测试是在恒温下进行，模拟仿真设置条件为恒温，自然对流。热产生率是通过热模型方程进行计算的。随后证实热模型的有效性，并将该模型进行简单的散热分析，得出增大空气对流系数可以明显降低温度，这为以后的散热分析奠定了基础。%It is very necessary to set the method to estimate internal temperature of the lithium battery when making lithium battery.The main problems of the battery module are:keep consistent constant temperature between single battery of the battery module,avoid reaching the peak temperature required by the battery itself,causing the worsening of battery performance and safety issue.Through single battery electrochemistry reaction to estimate heat generation rate of battery power,in order to achieve this aim,taking the charging and discharging experiment to obtain the characteristic parameter in the discharging process.Test was conducted under constant temperature,simulation setting constant temperature,natural convection.Through thermal model calculate heat power.Then verify the valid of the thermal model and take the model for simple thermal analysis,conclude that increasing the air convection coefficient can reduce the temperature obviously,which laid the foundation for later heat analysis.
Collective variables and dissipation
This course is an introduction to some basic concepts of non-equilibrium statistical mechanics. We put stress on the relevant entropy associated to a set of collective variables, on the meaning of the projection method in Liouville space and its use to establish equations of motion for these variables, and on the interpretation of dissipation in the framework of information theory
Dissipative work in thermodynamics
This work explores the concept of dissipative work and shows that such a kind of work is an invariant non-negative quantity. This feature is then used to get a new insight into adiabatic irreversible processes; for instance, why the final temperature in any adiabatic irreversible process is always higher than that attained in a reversible process having the same initial state and equal final pressure or volume. Based on the concept of identical processes, numerical simulations of adiabatic irreversible compression and expansion were performed, enabling a better understanding of differences between configuration and dissipative work. The positive nature of the dissipative work was used to discuss the case where the dissipated energy ends up in the surroundings, while the invariance of such work under a system-surroundings interchange enabled the resulting modification in thermodynamical quantities to be determined. The ideas presented in this study are primarily intended for undergraduate students with a background in thermodynamics, but they may also be of interest to graduate students and teachers.
Dissipative Work in Thermodynamics
Anacleto, Joaquim; Pereira, Mario G.; Ferreira, J. M.
2011-01-01
This work explores the concept of dissipative work and shows that such a kind of work is an invariant non-negative quantity. This feature is then used to get a new insight into adiabatic irreversible processes; for instance, why the final temperature in any adiabatic irreversible process is always higher than that attained in a reversible process…
Dissipation Bound for Thermodynamic Control
Machta, Benjamin B.
2015-12-01
Biological and engineered systems operate by coupling function to the transfer of heat and/or particles down a thermal or chemical gradient. In idealized deterministically driven systems, thermodynamic control can be exerted reversibly, with no entropy production, as long as the rate of the protocol is made slow compared to the equilibration time of the system. Here we consider fully realizable, entropically driven systems where the control parameters themselves obey rules that are reversible and that acquire directionality in time solely through dissipation. We show that when such a system moves in a directed way through thermodynamic space, it must produce entropy that is on average larger than its generalized displacement as measured by the Fisher information metric. This distance measure is subextensive but cannot be made small by slowing the rate of the protocol.
A two-dimensional mathematical model is presented for the laminar heat and mass transfer of an electrically-conducting, heat generating/absorbing fluid past a perforated horizontal surface in the presence of viscous and Joule (Ohmic) heating. The Talbot-Cheng-Scheffer-Willis formulation (1980) is used to introduce a thermophoretic coefficient into the concentration boundary layer equation. The governing partial differential equations are non-dimensionalized and transformed into a system of nonlinear ordinary differential similarity equations, in a single independent variable, η. The resulting coupled, nonlinear equations are solved under appropriate transformed boundary conditions using the Network Simulation Method. Computations are performed for a wide range of the governing flow parameters, viz Prandtl number, thermophoretic coefficient (a function of Knudsen number), Eckert number (viscous heating effect), thermal conductivity parameter, heat absorption/generation parameter, wall transpiration parameter, Hartmann number and Schmidt number. The numerical details are discussed with relevant applications. Excellent correlation is achieved with earlier studies due to White (1974) and Chamkha and Issa (2000). The present problem finds applications in optical fiber fabrication, aerosol filter precipitators, particle deposition on hydronautical blades, semiconductor wafer design, thermo-electronics and nuclear hazards.
Host-specific thermal profiles affect fitness of a widespread pathogen.
Stevenson, Lisa A; Roznik, Elizabeth A; Alford, Ross A; Pike, David A
2014-11-01
Host behavior can interact with environmental context to influence outcomes of pathogen exposure and the impact of disease on species and populations. Determining whether the thermal behaviors of individual species influence susceptibility to disease can help enhance our ability to explain and predict how and when disease outbreaks are likely to occur. The widespread disease chytridiomycosis (caused by the fungal pathogen Batrachochytrium dendrobatidis, Bd) often has species-specific impacts on amphibian communities; some host species are asymptomatic, whereas others experience mass mortalities and population extirpation. We determined whether the average natural thermal regimes experienced by sympatric frog species in nature, in and of themselves, can account for differences in vulnerability to disease. We did this by growing Bd under temperatures mimicking those experienced by frogs in the wild. At low and high elevations, the rainforest frogs Litoria nannotis, L. rheocola, and L. serrata maintained mean thermal regimes within the optimal range for pathogen growth (15-25°C). Thermal regimes for L. serrata, which has recovered from Bd-related declines, resulted in slower pathogen growth than the cooler and less variable thermal regimes for the other two species, which have experienced more long-lasting declines. For L. rheocola and L. serrata, pathogen growth was faster in thermal regimes corresponding to high elevations than in those corresponding to low elevations, where temperatures were warmer. For L. nannotis, which prefers moist and thermally stable microenvironments, pathogen growth was fastest for low-elevation thermal regimes. All of the thermal regimes we tested resulted in pathogen growth rates equivalent to, or significantly faster than, rates expected from constant-temperature experiments. The effects of host body temperature on Bd can explain many of the broad ecological patterns of population declines in our focal species, via direct effects on
Analysis of the factors affecting thermal evolution of hot rolled steel during coil cooling
无
2006-01-01
The thermal evolution of steel coil during cooling was simulated and investigated by the use of in-house Q-CSP(R) software.The dependence of the thermal evolution of steel coil on cooling methods, temperature distribution of the strip before coiling, coil size and steel grades was also discussed.The study plays a significant role in helping steel makers to better understand and control the cooling process.
Radial thermal diffusivity of toroidal plasma affected by resonant magnetic perturbations
We investigate how the radial thermal diffusivity of an axisymmetric toroidal plasma is modified by effect of resonant magnetic perturbations (RMPs), using a drift kinetic simulation code for calculating the thermal diffusivity in the perturbed region. The perturbed region is assumed to be generated on and around the resonance surfaces, and is wedged in between the regular closed magnetic surfaces. It has been found that the radial thermal diffusivity χr in the perturbed region is represented as χr = χr(0) {1 + c r parallel2>}. Here r parallel2>1/2 is the strength of the RMPs in the radial directions, means the flux surface average defined by the unperturbed (i.e., original) magnetic field, χr(0) is the neoclassical thermal diffusivity, and c is a positive coefficient. In this paper, dependence of the coefficient c on parameters of the toroidal plasma is studied in results given by the δ f simulation code solving the drift kinetic equation under an assumption of zero electric field. We find that the dependence of c is given as c ∝ ωb/νeff m in the low collisionality regime νeff b, where νeff is the effective collision frequency, ωb is the bounce frequency and m is the particle mass. In case of νeff > ωb, the thermal diffusivity χr evaluated by the simulations becomes close to the neoclassical thermal diffusivity χr(0). (author)
How Stress Can Reduce Dissipation in Glasses
Wu, Jiansheng; Yu, Clare C.
2011-01-01
We propose that stress can decrease the internal friction of amorphous solids, either by increasing the potential barriers of defects, thus reducing their tunneling and thermal activation that produce loss, or by decreasing the coupling between defects and phonons. This stress can be from impurities, atomic bonding constraints, or externally applied stress. Externally applied stress also reduces mechanical loss through dissipation dilution. Our results are consistent with the experiments, and...
Debus, J -D; Succi, S; Herrmann, H J
2015-01-01
By inspecting the effect of curvature on a moving fluid, we find that local sources of curvature not only exert inertial forces on the flow, but also generate viscous stresses as a result of the departure of streamlines from the idealized geodesic motion. The curvature-induced viscous forces are shown to cause an indirect and yet appreciable energy dissipation. As a consequence, the flow converges to a stationary equilibrium state solely by virtue of curvature-induced dissipation. In addition, we show that flow through randomly-curved media satisfies a non-linear transport law, resembling Darcy-Forchheimer's law, due to the viscous forces generated by the spatial curvature. It is further shown that the permeability can be characterized in terms of the average metric perturbation.
Nuruddin, Ibrahim K.
2012-01-01
This research is aimed at understanding the effect of thermal cycles on the metallurgical and microstructural characteristics of the heat affected zone of a multi-pass pipeline weld. Continuous Cooling Transformation (CCT) diagrams of the pipeline steel grades studied (X65, X70 and X100) were generated using a thermo mechanical simulator (Gleeble 3500) and 10 mm diameter by 100 mm length samples. The volume change during phase transformation was studied by a dilatometer, this is to underst...
Quantum tunneling with dissipation
The authors derive an exact solution to the problem of determining the rate of decay Γ of the metastable state of a quantum system when T = O with arbitrary dissipation. A potential of the type V(q) = aq2 + b(x - q)Θ(1 - x) is considered; this is realized in quantum decay of current states of superconducting bridges with a normal interlayer. The expression for Γ differs significantly from the case (Vq) = q2 - β q3 examined previously
With restriction to an irrotational velocity field, equations of motion for a nuclear fluid with dissipation are derived from the quantum-mechanical variational principle. Memory effects in the resulting Navier-Stokes-like equations ascribe elastoplasticity to the fluid whenever the intrinsic equilibration times are comparable to the collective time scale. The markovian limits yield the Euler equation, the Navier-Stokes equation and the fluid-dynamical equation for irrotational velocity fields. (orig.)
Schaffner, David
2015-11-01
A typical signature of dissipation in conventional fluid turbulence is the steepening power spectrum of velocity fluctuations, signaling the transition from the inertial range to the dissipation range where scales become small enough for fluid viscosity effects to be dominant and convert flow energy into thermal energy. In MHD fluids, resistivity can play an analogous role to viscosity for magnetic field fluctuations, where collisional scales determine the onset of dissipation. However, turbulent plasmas can exhibit other mechanisms for converting magnetic energy into thermal energy such as through the generation of current sheets and magnetic reconnection or through coupling to kinetic scale fluctuations such as Kinetic Alfven waves or Whistler waves. In collisionless plasmas such as the solar wind, only these alternative dissipation mechanisms are likely active. Recent experiments with MHD turbulence generated in the wind-tunnel configuration of the Swarthmore Spheromak Experiment (SSX) provide an environment in which various potential non-resistive signatures of magnetic turbulent energy dissipation can be studied. SSX plasma is magnetically dynamic with no background field. Previous work has demonstrated that a steepening in the magnetic fluctuation spectrum is observed which can be roughly interpreted as a transition from inertial range to a dissipation range magnetic turbulence. The frequency range at which this steepening occurs can be correlated to the ion inertial scale of the plasma, a length which is characteristic of the size of current sheets in MHD plasmas. Detailed intermittency and structure function analysis presented here coupled with appeals to fractal scaling models support the hypothesis that the observed turbulence is being affected by a global dissipation mechanism such as the generation of current sheets. Information theory based analysis techniques using permutation entropy and statistical complexity are also applied to seek dissipation
Quantum dissipative Higgs model
Amooghorban, Ehsan, E-mail: Ehsan.amooghorban@sci.sku.ac.ir; Mahdifar, Ali, E-mail: mahdifar_a@sci.sku.ac.ir
2015-09-15
By using a continuum of oscillators as a reservoir, we present a classical and a quantum-mechanical treatment for the Higgs model in the presence of dissipation. In this base, a fully canonical approach is used to quantize the damped particle on a spherical surface under the action of a conservative central force, the conjugate momentum is defined and the Hamiltonian is derived. The equations of motion for the canonical variables and in turn the Langevin equation are obtained. It is shown that the dynamics of the dissipative Higgs model is not only determined by a projected susceptibility tensor that obeys the Kramers–Kronig relations and a noise operator but also the curvature of the spherical space. Due to the gnomonic projection from the spherical space to the tangent plane, the projected susceptibility displays anisotropic character in the tangent plane. To illuminate the effect of dissipation on the Higgs model, the transition rate between energy levels of the particle on the sphere is calculated. It is seen that appreciable probabilities for transition are possible only if the transition and reservoir’s oscillators frequencies to be nearly on resonance.
Climate change affects marine fishes through the oxygen limitation of thermal tolerance.
Pörtner, Hans O; Knust, Rainer
2007-01-01
A cause-and-effect understanding of climate influences on ecosystems requires evaluation of thermal limits of member species and of their ability to cope with changing temperatures. Laboratory data available for marine fish and invertebrates from various climatic regions led to the hypothesis that, as a unifying principle, a mismatch between the demand for oxygen and the capacity of oxygen supply to tissues is the first mechanism to restrict whole-animal tolerance to thermal extremes. We show in the eelpout, Zoarces viviparus, a bioindicator fish species for environmental monitoring from North and Baltic Seas (Helcom), that thermally limited oxygen delivery closely matches environmental temperatures beyond which growth performance and abundance decrease. Decrements in aerobic performance in warming seas will thus be the first process to cause extinction or relocation to cooler waters. PMID:17204649
Thermal tolerance affects mutualist attendance in an ant-plant protection mutualism.
Fitzpatrick, Ginny; Lanan, Michele C; Bronstein, Judith L
2014-09-01
Mutualism is an often complex interaction among multiple species, each of which may respond differently to abiotic conditions. The effects of temperature on the formation, dissolution, and success of these and other species interactions remain poorly understood. We studied the thermal ecology of the mutualism between the cactus Ferocactus wislizeni and its ant defenders (Forelius pruinosus, Crematogaster opuntiae, Solenopsis aurea, and Solenopsis xyloni) in the Sonoran Desert, USA. The ants are attracted to extrafloral nectar produced by the plants and, in exchange, protect the plants from herbivores; there is a hierarchy of mutualist effectiveness based on aggression toward herbivores. We determined the relationship between temperature and ant activity on plants, the thermal tolerance of each ant species, and ant activity in relation to the thermal environment of plants. Temperature played a role in determining which species interact as mutualists. Three of the four ant species abandoned the plants during the hottest part of the day (up to 40 °C), returning when surface temperature began to decrease in the afternoon. The least effective ant mutualist, F. pruinosus, had a significantly higher critical thermal maximum than the other three species, was active across the entire range of plant surface temperatures observed (13.8-57.0 °C), and visited plants that reached the highest temperatures. F. pruinosus occupied some plants full-time and invaded plants occupied by more dominant species when those species were thermally excluded. Combining data on thermal tolerance and mutualist effectiveness provides a potentially powerful tool for predicting the effects of temperature on mutualisms and mutualistic species. PMID:25012597
A long-standing objective in materials research is to understand how energy is dissipated in both the electronic and atomic subsystems in irradiated materials, and how related non-equilibrium processes may affect defect dynamics and microstructure evolution. Here we show that alloy complexity in concentrated solid solution alloys having both an increasing number of principal elements and altered concentrations of specific elements can lead to substantial reduction in the electron mean free path and thermal conductivity, which has a significant impact on energy dissipation and consequentially on defect evolution during ion irradiation. Enhanced radiation resistance with increasing complexity from pure nickel to binary and to more complex quaternary solid solutions is observed under ion irradiation up to an average damage level of 1 displacement per atom. Understanding how materials properties can be tailored by alloy complexity and their influence on defect dynamics may pave the way for new principles for the design of radiation tolerant structural alloys
Dissipative effects in the expansion of the universe. I, II.
Matzner, R. A.; Misner, C. W.
1972-01-01
Consideration of dissipative processes in anisotropic homogeneous world models, showing that dissipation reduces the anisotropy. The viscosity approximation and its range of applicability is discussed. Examples are presented which have been calculated by the use of a simple approximation to the collision-time method, using the cross section appropriate to weak interaction neutrino scattering. It is found that such dissipation is quite effective except for one particular cosmological model which is axisymmetric and in which the entire expansion of the model is taken up by expansion along the axis. A detailed multicomponent model is developed for dissipative processes in Euclidean homogeneous cosmological models. These processes involve neutrinos which might have long mean free times in interaction with other constituents which are thermalized by electromagnetic interactions, and whose weak interactions produce thermal neutrinos.
Heat conduction modelling with energy conservation dissipative particle dynamics
The paper studies by means of numerical simulations the model of dissipative particle dynamics with energy conservation for the simple case of thermal conduction. The model can be understood as a versatile discretization of the heat conduction equation on a random lattice including thermal fluctuations
Relative Entropy, Interaction Energy and the Nature of Dissipation
Bernard Gaveau
2014-06-01
Full Text Available Many thermodynamic relations involve inequalities, with equality if a process does not involve dissipation. In this article we provide equalities in which the dissipative contribution is shown to involve the relative entropy (a.k.a. Kullback-Leibler divergence. The processes considered are general time evolutions both in classical and quantum mechanics, and the initial state is sometimes thermal, sometimes partially so. By calculating a transport coefficient we show that indeed—at least in this case—the source of dissipation in that coefficient is the relative entropy.
Direct and indirect detection of dissipative dark matter
We study the constraints from direct detection and solar capture on dark matter scenarios with a subdominant dissipative component. This dissipative dark matter component in general has both a symmetric and asymmetric relic abundance. Dissipative dynamics allow this subdominant dark matter component to cool, resulting in its partial or total collapse into a smaller volume inside the halo (e.g., a dark disk) as well as a reduced thermal velocity dispersion compared to that of normal cold dark matter. We first show that these features considerably relax the limits from direct detection experiments on the couplings between standard model (SM) particles and dissipative dark matter. On the other hand, indirect detection of the annihilation of the symmetric dissipative dark matter component inside the Sun sets stringent and robust constraints on the properties of the dissipative dark matter. In particular, IceCube observations force dissipative dark matter particles with mass above 50 GeV to either have a small coupling to the SM or a low local density in the solar system, or to have a nearly asymmetric relic abundance. Possible helioseismology signals associated with purely asymmetric dissipative dark matter are discussed, with no present constraints
Dissipation regimes for short wind waves
Caulliez, Guillemette
2013-02-01
The dissipation processes affecting short wind waves of centimeter and decimeter scales are investigated experimentally in laboratory. The processes include damping due to molecular viscosity, generation of capillary waves, microbreaking, and breaking. The observations were made in a large wind wave tank for a wide range of fetches and winds, using a laser sheet and a high-resolution video camera. The work aims at constructing a comprehensive picture of dissipative processes in the short wind wave field, to find for which scales particular dissipative mechanism may become important. Four distinct regimes have been identified. For capillary-gravity wave fields, i.e., for dominant waves with scales below 4 cm, viscous damping is found to be the main dissipation mechanism. The gravity-capillary wave fields with dominant wavelength less than 10 cm usually exhibit a train of capillary ripples at the crest wavefront, but no wave breaking. For such waves, the main dissipation process is molecular viscosity occurring through nonlinear energy cascade toward high-frequency motions. Microscale breaking takes place for waves longer than 10 cm and manifests itself in a very localized surface disruption on the forward face of the crest. Such events generate turbulent motions in water and thus enhance wave dissipation. Plunging breaking, characterized by formation of a crest bulge, a microjet hitting the water surface and a splash-up, occurs for short gravity waves of wavelength exceeding 20 cm. Macroscale spilling breaking is also observed for longer waves at high winds. In both cases, the direct momentum transfer from breaking waves to the water flow contributes significantly to wave damping.
The various incidents, imputed to thermal fatigue, which occurred throughout the world on the auxiliary lines of Reactor Coolant System (SIS, RHR, CVC), led EDF to urge a research program in order to determine the origins and the consequences of these problems for the French nuclear power plants. In 1992, following the crossing crack discovered at Dampierre 2 on the un-isolable part of a Safety Injection System pipe, a program of instrumentation was defined and is described in this paper. Among the objectives, two of the principal goals were to determine the thermal loadings really supported by the various lines and to highlight the thermal hydraulic phenomena affecting them. Indeed, in order to explain the discovered damages, it was essential to know the real thermal loadings to compare them with those of design and to carry out mechanical calculations of resistance to thermal fatigue. The instrumentations installed on the 900 MW units enabled to check the resistance with the fatigue of all the auxiliary lines in spite of significant differences between the real loadings and those envisaged at the design. They contributed to the knowledge improvement on the local thermal hydraulic phenomena but the incidents at Dampierre 1 showed that this knowledge is still imperfect. The results of these instrumentations are also used for the design of the future units by the use of the feedback of several cycles of acquisition on the 900 MW units, but also 1300 MW and 1450 MW since similar instrumentations were installed on the auxiliary lines in Golfech 2 and Chooz B1
Buckwheat and Millet Affect Thermal, Rheological, and Gelling Properties of Wheat Flour.
Wu, Kao; Gan, Renyou; Dai, Shuhong; Cai, Yi-Zhong; Corke, Harold; Zhu, Fan
2016-03-01
Buckwheat (BF) and millet (MF) are recommended as healthy foods due to their unique chemical composition and health benefits. This study investigated the thermal and rheological properties of BF-WF (wheat flour) and MF-WF flour blends at various ratios (0:100 to 100:0). Increasing BF or MF concentration led to higher cold paste viscosity and setback viscosity of pasting properties gel adhesiveness, storage modulus (G') and loss modulus (G″) of dynamic oscillatory rheology, and yield stress (σ0 ) of flow curve of WF. BF and MF addition decreased peak viscosity and breakdown of pasting, gel hardness, swelling volume, and consistency coefficient (K) of flow curve of WF. Thermal properties of the blends appeared additive of that of individual flour. Nonadditive effects were observed for some property changes in the mixtures, and indicated interactions between flour components. This may provide a physicochemical basis for using BF and MF in formulating novel healthy products. PMID:26890337
Kalashnikov, Vladimir L
2010-01-01
The analytical theory of chirped dissipative soliton solutions of nonlinear complex Ginzburg-Landau equation is exposed. Obtained approximate solutions are easily traceable within an extremely broad range of the equation parameters and allow a clear physical interpretation as a representation of the strongly chirped pulses in mode-locked both solid-state and fiber oscillators. Scaling properties of such pulses demonstrate a feasibility of sub-mJ pulse generation in the continuous-wave mode-locking regime directly from an oscillator operating at the MHz repetition rate.
Heat flux and quantum correlations in dissipative cascaded systems
Lorenzo, Salvatore; Farace, Alessandro; Ciccarello, Francesco; Palma, G. Massimo; Giovannetti, Vittorio
2015-02-01
We study the dynamics of heat flux in the thermalization process of a pair of identical quantum systems that interact dissipatively with a reservoir in a cascaded fashion. Despite that the open dynamics of the bipartite system S is globally Lindbladian, one of the subsystems "sees" the reservoir in a state modified by the interaction with the other subsystem and hence it undergoes a non-Markovian dynamics. As a consequence, the heat flow exhibits a nonexponential time behavior which can greatly deviate from the case where each party is independently coupled to the reservoir. We investigate both thermal and correlated initial states of S and show that the presence of correlations at the beginning can considerably affect the heat-flux rate. We carry out our study in two paradigmatic cases—a pair of harmonic oscillators with a reservoir of bosonic modes and two qubits with a reservoir of fermionic modes—and compare the corresponding behaviors. In the case of qubits and for initial thermal states, we find that the trace distance discord is at any time interpretable as the correlated contribution to the total heat flux.
Holloway, J.M.; Nordstrom, D.K.; Böhlke, J.K.; McCleskey, R.B.; Ball, J.W.
2011-01-01
Dissolved inorganic nitrogen, largely in reduced form (NH4(T)≈NH4(aq)++NH3(aq)o), has been documented in thermal waters throughout Yellowstone National Park, with concentrations ranging from a few micromolar along the Firehole River to millimolar concentrations at Washburn Hot Springs. Indirect evidence from rock nitrogen analyses and previous work on organic compounds associated with Washburn Hot Springs and the Mirror Plateau indicate multiple sources for thermal water NH4(T), including Mesozoic marine sedimentary rocks, Eocene lacustrine deposits, and glacial deposits. A positive correlation between NH4(T) concentration and δ18O of thermal water indicates that boiling is an important mechanism for increasing concentrations of NH4(T) and other solutes in some areas. The isotopic composition of dissolved NH4(T) is highly variable (δ15N = −6‰ to +30‰) and is positively correlated with pH values. In comparison to likely δ15N values of nitrogen source materials (+1‰ to +7‰), high δ15N values in hot springs with pH >5 are attributed to isotope fractionation associated with NH3(aq)o loss by volatilization. NH4(T) in springs with low pH typically is relatively unfractionated, except for some acid springs with negative δ15N values that are attributed to NH3(g)o condensation. NH4(T) concentration and isotopic variations were evident spatially (between springs) and temporally (in individual springs). These variations are likely to be reflected in biomass and sediments associated with the hot springs and outflows. Elevated NH4(T) concentrations can persist for 10s to 1000s of meters in surface waters draining hot spring areas before being completely assimilated or oxidized.
2002-01-01
The moon's gravity imparts tremendous energy to the Earth, raising tides throughout the global oceans. What happens to all this energy? This question has been pondered by scientists for over 200 years, and has consequences ranging from the history of the moon to the mixing of the oceans. Richard Ray at NASA's Goddard Space Flight Center, Greenbelt, Md. and Gary Egbert of the College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Ore. studied six years of altimeter data from the TOPEX/Poseidon satellite to address this question. According to their report in the June 15 issue of Nature, about 1 terawatt, or 25 to 30 percent of the total tidal energy dissipation, occurs in the deep ocean. The remainder occurs in shallow seas, such as on the Patagonian Shelf. 'By measuring sea level with the TOPEX/Poseidon satellite altimeter, our knowledge of the tides in the global ocean has been remarkably improved,' said Richard Ray, a geophysicist at Goddard. The accuracies are now so high that this data can be used to map empirically the tidal energy dissipation. (Red areas, above) The deep-water tidal dissipation occurs generally near rugged bottom topography (seamounts and mid-ocean ridges). 'The observed pattern of deep-ocean dissipation is consistent with topographic scattering of tidal energy into internal motions within the water column, resulting in localized turbulence and mixing', said Gary Egbert an associate professor at OSU. One important implication of this finding concerns the possible energy sources needed to maintain the ocean's large-scale 'conveyor-belt' circulation and to mix upper ocean heat into the abyssal depths. It is thought that 2 terawatts are required for this process. The winds supply about 1 terawatt, and there has been speculation that the tides, by pumping energy into vertical water motions, supply the remainder. However, all current general circulation models of the oceans ignore the tides. 'It is possible that properly
Stress analysis of thermally affected rotating nanoshafts with varying material properties
Kiani, Keivan
2016-04-01
Based on the surface elasticity theory of Gurtin-Murdoch, thermo-elastic fields within rotating nanoshafts with varying material properties subjected to a thermal field are explicitly examined. Accounting for the surface energy effect, the nonclassical boundary conditions are enforced in the cases of fixed-free and free-free conditions. The effects of variation of material properties, temperature of the environment, angular velocity, and radius of the outer radius on the radial displacement, hoop and radial stresses are investigated. In all performed studies, the role of the surface effect on the thermo-elastic field of the nanostructure is methodically discussed.
Elementary Processes in Dissipative Cosmic Medium
Yoshimura, M
1997-01-01
Quantum dynamics of a finite degrees of freedom is often much affected by interaction with the larger environment of cosmic medium. In this lecture we first review some recent developments of the theory of quantum dissipation in the linear open system. In the second part we discuss two classes of applications: decay of unstable particle in medium, and environmental effect on the parametric particle production. The first subject of particle decay may have important consequences on the scenario...
Viscosity measurement techniques in Dissipative Particle Dynamics
Boromand, Arman; Jamali, Safa; Maia, Joao M.
2015-11-01
In this study two main groups of viscosity measurement techniques are used to measure the viscosity of a simple fluid using Dissipative Particle Dynamics, DPD. In the first method, a microscopic definition of the pressure tensor is used in equilibrium and out of equilibrium to measure the zero-shear viscosity and shear viscosity, respectively. In the second method, a periodic Poiseuille flow and start-up transient shear flow is used and the shear viscosity is obtained from the velocity profiles by a numerical fitting procedure. Using the standard Lees-Edward boundary condition for DPD will result in incorrect velocity profiles at high values of the dissipative parameter. Although this issue was partially addressed in Chatterjee (2007), in this work we present further modifications (Lagrangian approach) to the original LE boundary condition (Eulerian approach) that will fix the deviation from the desired shear rate at high values of the dissipative parameter and decrease the noise to signal ratios in stress measurement while increases the accessible low shear rate window. Also, the thermostat effect of the dissipative and random forces is coupled to the dynamic response of the system and affects the transport properties like the viscosity and diffusion coefficient. We investigated thoroughly the dependency of viscosity measured by both Eulerian and Lagrangian methodologies, as well as numerical fitting procedures and found that all the methods are in quantitative agreement.
Mariana Ferreira Oliveira Prates; Raquel Pires Campos; Michelly Morais Barbosa da Silva; Maria Lígia Rodrigues Macedo; Priscila Aiko Hiane; Manoel Mendes Ramos Filho
2015-01-01
The effect of jelly processing on the chemical properties, nutrients, antinutritional factors, bioactive compounds, and antioxidant activity of unripe and ripe canjiqueira fruits was evaluated. The fruits were collected from Pantanal regions at two different ripening stages and were used to produce jellies. The processing affected the chemical characteristics and the content of all nutrients, except for the lipids. Moisture and protein content reduced, whereas the energy value increased. The ...
Influence of queue propagation and dissipation on route travel times
Raovic, Nevena
classes into account (Bliemer, 2008). Yperman (2007) indicates that there is a significant difference in queue-propagation and queue-dissipation between the LTM and DQM. This results in different route travel times, and can further affect route choice. In this paper, different approaches to represent...... queue propagation and dissipation through the CTM, LTM and DQM are studied. A simple network allows to show how these approaches influence route travel time. Furthermore, the possibility of changing the existing DQM is considered in order to more realistically represent queue propagation and dissipation......, which would lead to more accurate route travel times....
Fluctuations of Quantum Radiation Pressure in Dissipative Fluid
Wu, C H; Wu, Chun-Hsien; Lee, Da-Shin
2003-01-01
Using the generalized Langevin equations involving the stress tensor approach, quantum fluctuations of electromagnetic radiation pressure in the presence of a dissipative environment have been studied. We consider a perfectly reflecting mirror which is exposed to the electromagnetic radiation pressure in a fluid at finite temperature. The dynamics of velocity fluctuations of the mirror is studied analytically in both small time and large time limits. In the small time limit, the minimum uncertainty of the mirror's position measurement from both quantum and thermal noises effects including the photon counting error in the laser interferometer is obtained based on the fluctuation-dissipation theorem as compared with the ''standard quantum limit''. In addition, the result of the large time behavior of fluctuations of the mirror's velocity in a dissipative environment can be applied to the laser interferometer of the ground-based gravitational wave detector. The role of the dissipative effects in this case is pla...
Thermal ageing embrittlement of the heat-affected-zone in a PWR RPV steel weldment
Ferritic pressure vessels in the PWR primary circuit operate at temperatures in the range 288 to 345 degrees C. Plant life extension without vessel replacement will require that these components exceed their original design life of approximately 300,000 h. Such extended durations offer the potential for embrittlement by grain boundary segregation of impurity elements. In this paper results from Charpy impact fracture testing of the ehat-affected-zone (HAZ) region of a reactor pressure vessel (RPV) weldment are reported for a range of aging treatments uip to 20,000 h at temperatures between 325 and 450 degrees C. Auger electron spectroscopy has been used to quantify associated changes in grain boundary chemistry. These data are compared with model predictions of segregation and embrittlement based on previous studies on simulated HAZ microstructures and the possible implications for extended in service aging are discussed
Thermal conditions during juvenile development affect adult dispersal in a spider.
Bonte, Dries; Travis, Justin M J; De Clercq, Nele; Zwertvaegher, Ingrid; Lens, Luc
2008-11-01
Understanding the causes and consequences of dispersal is a prerequisite for the effective management of natural populations. Rather than treating dispersal as a fixed trait, it should be considered a plastic process that responds to both genetic and environmental conditions. Here, we consider how the ambient temperature experienced by juvenile Erigone atra, a spider inhabiting crop habitat, influences adult dispersal. This species exhibits 2 distinct forms of dispersal, ballooning (long distance) and rappelling (short distance). Using a half-sib design we raised individuals under 4 different temperature regimes and quantified the spiders' propensity to balloon and to rappel. Additionally, as an indicator of investment in settlement, we determined the size of the webs build by the spiders following dispersal. The optimal temperature regimes for reproduction and overall dispersal investment were 20 degrees C and 25 degrees C. Propensity to perform short-distance movements was lowest at 15 degrees C, whereas for long-distance dispersal it was lowest at 30 degrees C. Plasticity in dispersal was in the direction predicted on the basis of the risks associated with seasonal changes in habitat availability; long-distance ballooning occurred more frequently under cooler, spring-like conditions and short-distance rappelling under warmer, summer-like conditions. Based on these findings, we conclude that thermal conditions during development provide juvenile spiders with information about the environmental conditions they are likely to encounter as adults and that this information influences the spider's dispersal strategy. Climate change may result in suboptimal adult dispersal behavior, with potentially deleterious population level consequences. PMID:18974219
Heat flux dynamics in dissipative cascaded systems
de Lorenzo, S.; Farace, A.; Ciccarello, F.; De Palma, G; Giovannetti, V.
2014-01-01
We study the dynamics of heat flux in the thermalization process of a pair of identical quantum system that interact dissipatively with a reservoir in a {\\it cascaded} fashion. Despite the open dynamics of the bipartite system S is globally Lindbladian, one of the subsystems "sees" the reservoir in a state modified by the interaction with the other subsystem and hence it undergoes a non-Markovian dynamics. As a consequence, the heat flow exhibits a non-exponential time behaviour which can gre...
Two-resonator circuit QED: Dissipative theory
Managing the interaction between two quantum objects is a fundamental issue for quantum information processing. A promising approach is a two-resonator circuit quantum electrodynamics setup referred to as quantum switch. Here, a superconducting qubit provides switchable coupling between the resonators. This requires operation in the dispersive regime, where the qubit transition frequency is far detuned from those of the resonators. In our contribution we present a dissipative theory for the quantum switch. We derive an effective Hamiltonian beyond rotating-wave approximation and study the dissipative dynamics within a quantum master equation approach. We derive analytically how the qubit affects the dynamics and the coherence of the switch even if its state remains constant, and we estimate the strength of this influence. Our results are corroborated by numerical simulations.
Mariana Ferreira Oliveira Prates
2015-03-01
Full Text Available The effect of jelly processing on the chemical properties, nutrients, antinutritional factors, bioactive compounds, and antioxidant activity of unripe and ripe canjiqueira fruits was evaluated. The fruits were collected from Pantanal regions at two different ripening stages and were used to produce jellies. The processing affected the chemical characteristics and the content of all nutrients, except for the lipids. Moisture and protein content reduced, whereas the energy value increased. The phytic acid found in fresh fruits was eliminated after processing, and the trypsin inhibitors were reduced, especially in ripe fruits. Lectin activity was not verified in unripe and ripe fruits and jellies. The levels of bioactive compounds were reduced after jelly processing, but their retention was higher in unripe fruits. The final levels of bioactive compounds in the jelly made from unripe fruits were higher than that in the jelly made from ripe fruits, whereas the IC50 value was lower, indicating higher potential to prevent free radicals damages to human body. Jelly processing proved to be a good alternative to the use of canjiqueira fruits due to the reduction in antinutritional factors and the retention of bioactive compounds
Notari, Alessio
2016-01-01
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...
Corneanu, Ciprian Adrian; Simon, Marc Oliu; Cohn, Jeffrey F; Guerrero, Sergio Escalera
2016-08-01
Facial expressions are an important way through which humans interact socially. Building a system capable of automatically recognizing facial expressions from images and video has been an intense field of study in recent years. Interpreting such expressions remains challenging and much research is needed about the way they relate to human affect. This paper presents a general overview of automatic RGB, 3D, thermal and multimodal facial expression analysis. We define a new taxonomy for the field, encompassing all steps from face detection to facial expression recognition, and describe and classify the state of the art methods accordingly. We also present the important datasets and the bench-marking of most influential methods. We conclude with a general discussion about trends, important questions and future lines of research. PMID:26761193
Highlights: • The constitution of Ni–17Mo–7Cr alloy was convincingly ascertained by TEM analysis. • The Ni–17Mo–7Cr alloy was thermally cycled with a peak temperature up to 1350 °C. • The lamellar-like phases in the alloy were firstly determined by TEM and HRTEM. • The formation mechanism for the lamellar-like phases was unveiled rigorously. • Effect of lamellar-like phases on the alloy’s performances was evaluated in depth. - Abstract: A representative Ni–Mo–Cr superalloy with basic composition of Ni–17Mo–7Cr (wt.%) was fabricated in the work and the relationship between the microstructure and mechanical properties while it went through simulated heat-affected zone (HAZ) thermal cycle treatment was investigated. The results reveal that the Ni–Mo–Cr alloy mainly consisted of Ni matrix and MoC carbides. The critical peak temperature that a lamellar-like structure occurred in the alloy was found to be 1300 °C. These products were firstly characterized by transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) analysis, and they were essentially Ni matrix and carbides (MoC and chromium carbides) generated through local melting. The equivalent mechanical properties of the alloy relative to that of un-treated alloy were received owing to its unique architecture even the peak temperature during thermal cycle was up to 1350 °C. The results obtained suggests these lamellar-like products dispersed near the fusion line in a Ni–Mo–Cr welded joint will not influence the joint’s mechanical strength and stability while the peak temperature in the HAZ was adjusted below 1350 °C, providing valuable guideline in designing and applying the Ni–Mo–Cr system superalloys
He, Yanming, E-mail: heyanming@zjut.edu.cn [Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou 310014 (China); Yang, Jianguo, E-mail: yangjg@zjut.edu.cn [Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou 310014 (China); Qin, Chunjie [Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou 310014 (China); Chen, Shuangjian [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Gao, Zengliang [Institute of Process Equipment and Control Engineering, Zhejiang University of Technology, Hangzhou 310014 (China)
2015-09-15
Highlights: • The constitution of Ni–17Mo–7Cr alloy was convincingly ascertained by TEM analysis. • The Ni–17Mo–7Cr alloy was thermally cycled with a peak temperature up to 1350 °C. • The lamellar-like phases in the alloy were firstly determined by TEM and HRTEM. • The formation mechanism for the lamellar-like phases was unveiled rigorously. • Effect of lamellar-like phases on the alloy’s performances was evaluated in depth. - Abstract: A representative Ni–Mo–Cr superalloy with basic composition of Ni–17Mo–7Cr (wt.%) was fabricated in the work and the relationship between the microstructure and mechanical properties while it went through simulated heat-affected zone (HAZ) thermal cycle treatment was investigated. The results reveal that the Ni–Mo–Cr alloy mainly consisted of Ni matrix and MoC carbides. The critical peak temperature that a lamellar-like structure occurred in the alloy was found to be 1300 °C. These products were firstly characterized by transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) analysis, and they were essentially Ni matrix and carbides (MoC and chromium carbides) generated through local melting. The equivalent mechanical properties of the alloy relative to that of un-treated alloy were received owing to its unique architecture even the peak temperature during thermal cycle was up to 1350 °C. The results obtained suggests these lamellar-like products dispersed near the fusion line in a Ni–Mo–Cr welded joint will not influence the joint’s mechanical strength and stability while the peak temperature in the HAZ was adjusted below 1350 °C, providing valuable guideline in designing and applying the Ni–Mo–Cr system superalloys.
Noise and Dissipation During Preheating
Jorás, S E; Joras, Sergio E.; Ramos, Rudnei O.
2002-01-01
We study the consequences of noise and dissipation for parametric resonance during preheating. The effective equations of motion for the inflaton and the radiation field are obtained and shown to present self-consistent noise and dissipation terms. The equations exhibit the usual parametric resonance phenomenon, allowing for exponential amplification of the radiation modes inside the instability bands. By focusing on the dimension of the border of those bands we explicitly show that they are fractal, indicating the strong dependence of the outcome in the initial conditions. The simultaneous effect of noise and dissipation to the fractality of the borders are then examined.
Dissipative Particle Dynamics with Energy Conservation: Heat Conduction
Ripoll, Marisol; Español, Pep; Ernst, Matthieu H.
1999-01-01
We study by means of numerical simulations the model of dissipative particle dynamics with energy conservation for the simple case of thermal conduction. It is shown that the model displays correct equilibrium fluctuations and reproduces Fourier law. The connection between "mesoscopic coarse graining" and "resolution" is clarified.
Turbulent energy dissipation and intermittency in ambipolar diffusion magnetohydrodynamics
Momferratos, Georgios; Falgarone, Edith; Forêts, Guillaume Pineau des
2015-01-01
The dissipation of kinetic and magnetic energy in the interstellar medium (ISM) can proceed through viscous, Ohmic or ambipolar diffusion (AD). It occurs at very small scales compared to the scales at which energy is presumed to be injected. This localized heating may impact the ISM evolution but also its chemistry, thus providing observable features. Here, we perform 3D spectral simulations of decaying magnetohydrodynamic turbulence including the effects of AD. We find that the AD heating power spectrum peaks at scales in the inertial range, due to a strong alignment of the magnetic and current vectors in the dissipative range. AD affects much greater scales than the AD scale predicted by dimensional analysis. We find that energy dissipation is highly concentrated on thin sheets. Its probability density function follows a lognormal law with a power-law tail which hints at intermittency, a property which we quantify by use of structure function exponents. Finally, we extract structures of high dissipation, de...
Imaging dissipation and hot spots in carbon nanotube network transistors
Estrada, David; Pop, Eric
2011-02-01
We use infrared thermometry of carbon nanotube network (CNN) transistors and find the formation of distinct hot spots during operation. However, the average CNN temperature at breakdown is significantly lower than expected from the breakdown of individual nanotubes, suggesting extremely high regions of power dissipation at the CNN junctions. Statistical analysis and comparison with a thermal model allow the estimate of an upper limit for the average tube-tube junction thermal resistance, ˜4.4×1011 K/W (thermal conductance of ˜2.27 pW/K). These results indicate that nanotube junctions have a much greater impact on CNN transport, dissipation, and reliability than extrinsic factors such as low substrate thermal conductivity.
Nanoscale resolution immersion scanning thermal microscopy
Tovee, Peter D
2013-01-01
Nanoscale thermal properties are becoming of extreme importance for modern electronic circuits that dissipate increasing power on the length scale of few tens of nanometers, and for chemical and physical properties sensors and biosensors using nanoscale sized features. While Scanning Thermal Microscopy (SThM) is known for its ability to probe thermal properties and heat generation with nanoscale resolution, until today it was perceived impossible to use it in the liquid environment due to dominating direct heat exchange between microfabricated thermal probe and surrounding liquid that would deteriorate spatial resolution. Nonetheless, our theoretical analysis of SThM in liquids showed that for certain design of SThM probe with resistive heater located near the probe tip, their thermal signal is only moderately affected, by less than half on immersion in a dodecane environment. More significantly, its spatial resolution, surprisingly, would remain practically unaffected, and the thermal contact between the tip...
Rank of Stably Dissipative Graphs
Duarte, Pedro
2011-01-01
For the class of stably dissipative Lotka-Volterra systems we prove that the rank of its defining matrix, which is the dimension of the associated invariant foliation, is completely determined by the system's graph.
Zhou, L; Luo, Y X
2001-01-01
We present the dissipative dynamics of the field of two-photon Jaynes-Cummings model (JCM) with Stark shift in dispersive approximation and investigate the influence of dissipation on entanglement. We show the coherence properties of the field can be affected by the dissipative cavity when nonlinear two-photon process is involved.
Dissipative Effect and Tunneling Time
Samyadeb Bhattacharya
2011-01-01
Full Text Available The quantum Langevin equation has been studied for dissipative system using the approach of Ford et al. Here, we have considered the inverted harmonic oscillator potential and calculated the effect of dissipation on tunneling time, group delay, and the self-interference term. A critical value of the friction coefficient has been determined for which the self-interference term vanishes. This approach sheds new light on understanding the ion transport at nanoscale.
Wen LIU; Shuming XING; Peiwei BAO; Milan ZHANG; Liming XIAO
2007-01-01
The energy dissipation caused by the viscous force has great effects on the flow property of semi-solid metal during rheological processes such as slurry preparing, delivering and cavity filling. Experimental results in this paper indicate that the viscous friction between semi-solid metal and pipe wall, the collisions among the solid particles, and the liquid flow around particles are the three main types of energy dissipation. On the basis of the hydromechanics, the energy dissipation calculation model is built. It is demonstrated that the micro-structural parameters such as effective solid fraction, particle size and shape, and flow parameters such as the mean velocity, the fluctuant velocity of particles and the relative velocity between the fluid and solid phase, affect the energy dissipation of semi-solid metal.
SIMULATION IN THERMAL DESIGN FOR ELECTRONIC CONTROL UNIT OF ELECTRONIC UNIT PUMP
XU Quankui; ZHU Keqing; ZHUO Bin; MAO Xiaojian; WANG Junxi
2008-01-01
The high working junction temperature of power component is the most common reason of its failure. So the thermal design is of vital importance in electronic control unit (ECU) design. By means of circuit simulation, the thermal design of ECU for electronic unit pump (EUP) fuel system is applied. The power dissipation model of each power component in the ECU is created and simulated. According to the analyses of simulation results, the factors which affect the power dissipation of components are analyzed. Then the ways for reducing the power dissipation of power components are carried out. The power dissipation of power components at different engine state is calculated and analyzed. The maximal power dissipation of each power component in all possible engine state is also carried out based on these simulations. A cooling system is designed based on these studies. The tests show that the maximum total power dissipation of ECU drops from 43.2 W to 33.84 W after these simulations and optimizations. These applications of simulations in thermal design of ECU can greatly increase the quality of the design, save the design cost and shorten design time
Graphical abstract: The present work demonstrates that the temperature dependence of the escape rate is not only embedded in the so-called Arrhenius type factor, the second exponential factor also includes the temperature dependence which has a purely quantum origin that is entangled with dissipation. Display Omitted Highlights: → We explore the noise-induced barrier crossing dynamics of an open quantum system. → The bath coupled with the system is driven out of equilibrium by an external noise. → Nonlinear system-bath coupling and modulation of the bath affect the escape rate. → An additional exponential factor, other than Arrhenius is also temperature dependent. → This temperature dependence is purely quantum in origin. - Abstract: We address the stochastic dynamics of an open quantum system coupled to a heat reservoir that is driven out of thermal equilibrium by an external noise. By constructing Langevin and Fokker-Planck equations, we obtain the rate of decay from a metastable state of the system when the dissipation is state dependent. We discuss the effects and consequences of the non-linear interaction(s) stemming out of the system-bath coupling alongside the modulation of the bath by an external noise on the rate expression. We demonstrate that the temperature dependence of the escape rate is not only embedded in the so-called Arrhenius type factor, the second exponential factor also includes the temperature dependence. The last effect has a purely quantum origin. Interestingly, we also envisage that this quantum effect is entangled with dissipation. The results offer a basis for clarifying the relationship between the dissipation and exponential factor of the obtained rate expression.
Shit, Anindita [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India); Chattopadhyay, Sudip, E-mail: sudip_chattopadhyay@rediffmail.com [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711 103 (India); Ray Chaudhuri, Jyotipratim, E-mail: jprc_8@yahoo.com [Department of Physics, Katwa College, Katwa, Burdwan 713 130 (India)
2011-07-28
Graphical abstract: The present work demonstrates that the temperature dependence of the escape rate is not only embedded in the so-called Arrhenius type factor, the second exponential factor also includes the temperature dependence which has a purely quantum origin that is entangled with dissipation. Display Omitted Highlights: {yields} We explore the noise-induced barrier crossing dynamics of an open quantum system. {yields} The bath coupled with the system is driven out of equilibrium by an external noise. {yields} Nonlinear system-bath coupling and modulation of the bath affect the escape rate. {yields} An additional exponential factor, other than Arrhenius is also temperature dependent. {yields} This temperature dependence is purely quantum in origin. - Abstract: We address the stochastic dynamics of an open quantum system coupled to a heat reservoir that is driven out of thermal equilibrium by an external noise. By constructing Langevin and Fokker-Planck equations, we obtain the rate of decay from a metastable state of the system when the dissipation is state dependent. We discuss the effects and consequences of the non-linear interaction(s) stemming out of the system-bath coupling alongside the modulation of the bath by an external noise on the rate expression. We demonstrate that the temperature dependence of the escape rate is not only embedded in the so-called Arrhenius type factor, the second exponential factor also includes the temperature dependence. The last effect has a purely quantum origin. Interestingly, we also envisage that this quantum effect is entangled with dissipation. The results offer a basis for clarifying the relationship between the dissipation and exponential factor of the obtained rate expression.
Energy dissipation in biomolecular machines
Lervik, Anders
2012-07-01
The operation of a molecular pump, the calcium pump of sarcoplasmic reticulum is studied using mesoscopic non-equilibrium thermodynamics and molecular dynamics. The mesoscopic non-equilibrium thermodynamic description of the pump is compared to the description obtained in the framework of Hill for kinetic enzyme cycles. By comparing these two descriptions at isothermal conditions, they are found to be equivalent. This supports the validity of the mesoscopic approach. An extension of the mesoscopic non-equilibrium framework to also include a heat flux and the corresponding temperature difference is proposed. This can be used to model phenomena such as non-shivering thermogenesis, a process which lack a theoretical description in the kinetic cycle picture. Further, the heat transfer in the calcium pump is studied using molecular dynamics. This is done in order to obtain phenomenological parameters that can be used for the modeling of thermogenesis. A non-stationary non-equilibrium molecular dynamics approach is developed, which may be used to study heat transfer between a small object and the surrounding solvent. This methodology is applied to the calcium pump solvated in water. It is found that the thermal conductivity of the protein is low (0.2 W K-1 m-1) compared to water (0.6 WK-1 m-1). This means that the protein may sustain a large temperature gradient across its structure. The simulations also show that the protein-water surface is important for the heat transfer. The time scale for vibrational energy relaxation is found to be of order 10/100 ps which strengthens the local equilibrium assumption of mesoscopic non-equilibrium thermodynamics. Mesoscopic non-equilibrium thermodynamics is also applied to calculate the thermodynamic efficiency of the calcium pump embedded in lipid bilayers of varying length and from different tissues. This is done in order to show the applicability of mesoscopic non-equilibrium thermodynamics to interpret experimental data. The
Dilepton emission in high-energy heavy-ion collisions with dissipative hydrodynamics
Vujanovic, Gojko; Shen, Chun; Luzum, Matthew; Schenke, Bjoern; Jeon, Sangyoung; Gale, Charles
2015-01-01
In this contribution we study the effects of three transport coefficients of dissipative hydrodynamics on thermal dilepton anisotropic flow observables. The first two transport coefficients investigated influence the overall size and growth rate of shear viscous pressure, while the last transport coefficient governs the magnitude of net baryon number diffusion in relativistic dissipative fluid dynamics. All calculations are done using state-of-the-art 3+1D hydrodynamical simulations. We show that thermal dileptons are sensitive probes of the transport coefficients of dissipative hydrodynamics.
Work Fluctuation-Dissipation Trade-Off in Heat Engines
Funo, Ken; Ueda, Masahito
2015-12-01
Reducing work fluctuation and dissipation in heat engines or, more generally, information heat engines that perform feedback control, is vital to maximize their efficiency. The same problem arises when we attempt to maximize the efficiency of a given thermodynamic task that undergoes nonequilibrium processes for arbitrary initial and final states. We find that the most general trade-off relation between work fluctuation and dissipation applicable to arbitrary nonequilibrium processes is bounded from below by the information distance characterizing how far the system is from thermal equilibrium. The minimum amount of dissipation is found to be given in terms of the relative entropy and the Renyi divergence, both of which quantify the information distance between the state of the system and the canonical distribution. We give an explicit protocol that achieves the fundamental lower bound of the trade-off relation.
Energy dissipation in circular tube
A.D. Girgidov
2012-01-01
Full Text Available Energy dissipation distribution along the circular tube radius is important in solving such problems as calculation of heat transfer by the air flow through building envelope; calculation of pressure loss in spiral flows; calculation of cyclones with axial and tangential supply of dust-containing gas.Two types of one-dimensional radially axisymmetric flows in circular tube were considered: axial flow and rotation about the axis (Rankine vortex. Relying on two- and four-layer description of axial turbulent flow energy dissipation was calculated in each layer.Similar calculation for Rankine vortex with viscous sublayer at the tube surface was provided. By employing the dissipation minimum principle the boundary radius between rigid rotation and free vortex is calculated. Approximation of the velocity distribution in Rankine vortex is proposed.
Dissipative structures and related methods
Langhorst, Benjamin R; Chu, Henry S
2013-11-05
Dissipative structures include at least one panel and a cell structure disposed adjacent to the at least one panel having interconnected cells. A deformable material, which may comprise at least one hydrogel, is disposed within at least one interconnected cell proximate to the at least one panel. Dissipative structures may also include a cell structure having interconnected cells formed by wall elements. The wall elements may include a mesh formed by overlapping fibers having apertures formed therebetween. The apertures may form passageways between the interconnected cells. Methods of dissipating a force include disposing at least one hydrogel in a cell structure proximate to at least one panel, applying a force to the at least one panel, and forcing at least a portion of the at least one hydrogel through apertures formed in the cell structure.
DISSIPATIVE DIVERGENCE OF RESONANT ORBITS
Batygin, Konstantin [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Morbidelli, Alessandro, E-mail: kbatygin@gps.caltech.edu [Departement Cassiopee, Universite de Nice-Sophia Antipolis, Observatoire de la Cote d' Azur, F-06304 Nice (France)
2013-01-01
A considerable fraction of multi-planet systems discovered by the observational surveys of extrasolar planets reside in mild proximity to first-order mean-motion resonances. However, the relative remoteness of such systems from nominal resonant period ratios (e.g., 2:1, 3:2, and 4:3) has been interpreted as evidence for lack of resonant interactions. Here, we show that a slow divergence away from exact commensurability is a natural outcome of dissipative evolution and demonstrate that libration of critical angles can be maintained tens of percent away from nominal resonance. We construct an analytical theory for the long-term dynamical evolution of dissipated resonant planetary pairs and confirm our calculations numerically. Collectively, our results suggest that a significant fraction of the near-commensurate extrasolar planets are in fact resonant and have undergone significant dissipative evolution.
Dissipative heavy-ion collisions
This report is a compilation of lecture notes of a series of lectures held at Argonne National Laboratory in October and November 1984. The lectures are a discussion of dissipative phenomena as observed in collisions of atomic nuclei. The model is based on a system which has initially zero temperature and the initial energy is kinetic and binding energy. Collisions excite the nuclei, and outgoing fragments or the compound system deexcite before they are detected. Brownian motion is used to introduce the concept of dissipation. The master equation and the Fokker-Planck equation are derived. 73 refs., 59 figs
Dissipation in Relativistic Outflows: A Multisource Overview
Thompson, Christopher
2013-01-01
Relativistically expanding sources of X-rays and gamma-rays cover an enormous range of (central) compactness and Lorentz factor. The underlying physics is discussed, with an emphasis on how the dominant dissipative mode and the emergent spectrum depend on these parameters. Photons advected outward from high optical depth are a potentially important source of Compton seeds. Their characteristic energy is bounded below by ~1 MeV in pair-loaded outflows of relatively low compactness, and remains near ~1 MeV at very high compactness and low matter loading. This is compared with the characteristic energy of O(1) MeV observed in the rest frame spectra of many sources, including gamma-ray bursts, OSSE jet sources, MeV Blazars, and the intense initial 0.1 s pulse of the March 5 event. Additional topics discussed include the feedback of pair creation on electron heating and the formation of non-thermal spectra, their effectiveness at shielding the dissipative zone from ambient photons, direct Compton damping of irregu...
Energy Dissipation Processes in Solar Wind Turbulence
Wang, Y.; Wei, F. S.; Feng, X. S.; Xu, X. J.; Zhang, J.; Sun, T. R.; Zuo, P. B.
2015-12-01
Turbulence is a chaotic flow regime filled by irregular flows. The dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, dissipation ultimately cannot be achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection (MR) are two possible dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the dissipation region scaling around a solar wind MR region. We find that the MR region shows unique multifractal scaling in the dissipation range, while the ambient solar wind turbulence reveals a monofractal dissipation process for most of the time. These results provide the first observational evidences for intermittent multifractal dissipation region scaling around a MR site, and they also have significant implications for the fundamental energy dissipation process.
Scaling laws for the upper ocean temperature dissipation rate
Bogucki, D.J.; Huguenard, K.; Haus, B.K.; Özgökmen, T.M.; Reniers, A.J.H.M.; Laxague, N.J.M.
2015-01-01
Our understanding of temperature dissipation rate χ within the upper ocean boundary layer, which is critical for climate forecasts, is very limited. Near-surface turbulence also affects dispersion of contaminants and biogeochemical tracers. Using high-resolution optical turbulence measurements, scal
Constructal entransy dissipation minimization for 'volume-point' heat conduction
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
On Dissipation in Stochastic Systems
Thygesen, Uffe Høgsbro
1999-01-01
We define the property of dissipativity for controlled Ito diffusions. We investigate elementary properties, and we demonstrate that the framework is useful for control problems in which both probabilistic and worst-case representations of dynamic uncertainty are present. As an example we discuss...
Impacts on Dissipative Sonic Vacuum
Xu, Yichao; Nesterenko, Vitali
We investigate the propagating compression bell shape stress waves generated by the strikers with different masses impacting the sonic vacuum - the discrete dissipative strongly nonlinear metamaterial with zero long wave sound speed. The metamaterial is composed of alternating steel disks and Nitrile O-rings. Being a solid material, it has exceptionally low speed of the investigated stress waves in the range of 50 - 74 m/s, which is a few times smaller than the speed of sound or shock waves in air generated by blast. The shape of propagating stress waves was dramatically changed by the viscous dissipation. It prevented the incoming pulses from splitting into trains of solitary waves, a phenomenon characteristic of the non-dissipative strongly nonlinear discrete systems when the striker mass is larger than the cell mass. Both high-speed camera images and numerical simulations demonstrate the unusual rattling behavior of the top disk between the striker and the rest of the system. The linear momentum and energy from the striker were completely transferred to the metamaterial. This strongly nonlinear dissipative metamaterial can be designed for the optimal attenuation of dynamic loads generated by impact or contact explosion. Author 1 wants to acknowledge the support provided by UCSD.
Harvesting dissipated energy with a mesoscopic ratchet
Roche, B.; Roulleau, P.; Jullien, T.; Jompol, Y.; Farrer, I.; Ritchie, D. A.; Glattli, D. C.
2015-04-01
The search for new efficient thermoelectric devices converting waste heat into electrical energy is of major importance. The physics of mesoscopic electronic transport offers the possibility to develop a new generation of nanoengines with high efficiency. Here we describe an all-electrical heat engine harvesting and converting dissipated power into an electrical current. Two capacitively coupled mesoscopic conductors realized in a two-dimensional conductor form the hot source and the cold converter of our device. In the former, controlled Joule heating generated by a voltage-biased quantum point contact results in thermal voltage fluctuations. By capacitive coupling the latter creates electric potential fluctuations in a cold chaotic cavity connected to external leads by two quantum point contacts. For unequal quantum point contact transmissions, a net electrical current is observed proportional to the heat produced.
A dissipation bound for thermodynamic control
Machta, Benjamin
Biological and engineered systems operate by coupling function to the transfer of heat and/or particles down a thermal or chemical gradient. In idealized deterministically driven systems, thermodynamic control can be exerted reversibly, with no entropy production, as long as the rate of the protocol is made slow compared to the equilibration time of the system. Here we consider fully realizable, entropically driven systems where the control parameters themselves obey rules that are reversible and that acquire directionality in time solely through dissipation. We show that when such a system moves in a directed way through thermodynamic space, it must produce entropy that is on average larger than its generalized displacement as measured by the Fisher information metric. This distance measure is sub-extensive but cannot be made small by slowing the rate of the protocol.
Quantum memories based on engineered dissipation
Pastawski, Fernando; Cirac, Juan Ignacio
2010-01-01
Storing quantum information for long times without disruptions is a major requirement for most quantum information technologies. A very appealing approach is to use self-correcting Hamiltonians, i.e. tailoring local interactions among the qubits such that when the system is weakly coupled to a cold bath the thermalization process takes a long time. Here we propose an alternative but more powerful approach in which the coupling to a bath is engineered, so that dissipation protects the encoded qubit against more general kinds of errors. We show that the method can be implemented locally in four dimensional lattice geometries by means of a toric code, and propose a simple 2D set-up for proof of principle experiments.
Effective field theory of dissipative fluids
Crossley, Michael; Liu, Hong
2015-01-01
We develop an effective field theory for dissipative fluids which governs the dynamics of gapless modes associated to conserved quantities. The system is put in a curved spacetime and coupled to external sources for charged currents. The invariance of the hydrodynamical action under gauge symmetries and diffeomorphisms suggests a natural set of dynamical variables which provide a mapping between an emergent "fluid spacetime" and the physical spacetime. An essential aspect of our formulation is to identify the appropriate symmetries in the fluid spacetime. Our theory applies to nonlinear disturbances around a general density matrix. For a thermal density matrix, we require an additional Z_2 symmetry, to which we refer as the local KMS condition. This leads to the standard constraints of hydrodynamics, as well as a nonlinear generalization of the Onsager relations. It also leads to an emergent supersymmetry in the classical statistical regime, with a higher derivative version required for the full quantum regim...
Fluctuation and dissipation in de Sitter space
Fischler, Willy; Pedraza, Juan F; Tangarife, Walter
2014-01-01
In this paper we study some thermal properties of quantum field theories in de Sitter space by means of holographic techniques. We focus on the static patch of de Sitter and assume that the quantum fields are in the standard Bunch-Davies vacuum. More specifically, we follow the stochastic motion of a massive charged particle due to its interaction with Hawking radiation. The process is described in terms of the theory of Brownian motion in inhomogeneous media and its associated Langevin dynamics. At late times, we find that the particle undergoes a regime of slow diffusion and never reaches the horizon, in stark contrast to the usual random walk behavior at finite temperature. Nevertheless, the fluctuation-dissipation theorem is found to hold at all times.
Introduction to thermal transport
Phillpot, Simon R.; Alan J. H. McGaughey
2005-01-01
The relentless increase in the thermal loads imposed on devices and materials structures is driving renewed interest among materials scientists and engineers in the area of thermal transport. Applications include thermal barrier coatings on turbine blades, thermoelectric coolers, high-performance thermal transfer liquids, and heat dissipation in microelectronics. These, and other applications, demand not only ever more efficient thermal management, but also a better fundamental understanding ...
Sabine eVögeli
2015-05-01
Full Text Available Many stimuli evoke short-term emotional reactions. These reactions may play an important role in assessing how a subject perceives a stimulus. Additionally, long-term mood may modulate the emotional reactions but it is still unclear in what way. The question seems to be important in terms of animal welfare, as a negative mood may taint emotional reactions. In the present study with sheep, we investigated the effects of thermal stimuli on emotional reactions and the potential modulating effect of mood induced by manipulations of the housing conditions. We assume that unpredictable, stimulus-poor conditions lead to a negative and predictable, stimulus-rich conditions to a positive mood state. The thermal stimuli were applied to the upper breast during warm ambient temperatures: hot (as presumably negative, intermediate, and cold (as presumably positive. We recorded cortical activity by functional near-infrared spectroscopy, restlessness behavior (e.g. locomotor activity, aversive behaviors and ear postures as indicators of emotional reactions. The strongest hemodynamic reaction was found during a stimulus of intermediate valence independent of the animal’s housing conditions, whereas locomotor activity, ear movements and aversive behaviors were seen most in sheep from the unpredictable, stimulus-poor housing conditions, independent of stimulus valence. We conclude that, sheep perceived the thermal stimuli and differentiated between some of them. An adequate interpretation of the neuronal activity pattern remains difficult, though. The effects of housing conditions were small indicating that the induction of mood was only modestly efficacious. Therefore, a modulating effect of mood on the emotional reaction was not found.
Energy dissipation processes in solar wind turbulence
Wang, Y; Feng, X S; Xu, X J; Zhang, J; Sun, T R; Zuo, P B
2015-01-01
Turbulence is a chaotic flow regime filled by irregular flows. The dissipation of turbulence is a fundamental problem in the realm of physics. Theoretically, dissipation cannot be ultimately achieved without collisions, and so how turbulent kinetic energy is dissipated in the nearly collisionless solar wind is a challenging problem. Wave particle interactions and magnetic reconnection are two possible dissipation mechanisms, but which mechanism dominates is still a controversial topic. Here we analyze the dissipation region scaling around a solar wind magnetic reconnection region. We find that the magnetic reconnection region shows a unique multifractal scaling in the dissipation range, while the ambient solar wind turbulence reveals a monofractal dissipation process for most of the time. These results provide the first observational evidences for the intermittent multifractal dissipation region scaling around a magnetic reconnection site, and they also have significant implications for the fundamental energy...
An essential mechanism of heat dissipation in carbon nanotube electronics.
Rotkin, Slava V; Perebeinos, Vasili; Petrov, Alexey G; Avouris, Phaedon
2009-05-01
Excess heat generated in integrated circuits is one of the major problems of modern electronics. Surface phonon-polariton scattering is shown here to be the dominant mechanism for hot charge carrier energy dissipation in a nanotube device fabricated on a polar substrate, such as SiO(2). By use of microscopic quantum models, the Joule losses were calculated for the various energy dissipation channels as a function of the electric field, doping, and temperature. The polariton mechanism must be taken into account to obtain an accurate estimate of the effective thermal coupling of the nonsuspended nanotube to the substrate, which was found to be 0.1-0.2 W/(m x K) even in the absence of the bare phononic thermal coupling. PMID:19334687
Dynamical response theory for driven-dissipative quantum systems
Campos Venuti, Lorenzo; Zanardi, Paolo
2016-03-01
We discuss dynamical response theory of driven-dissipative quantum systems described by Markovian master equations generating semigroups of maps. In this setting thermal equilibrium states are replaced by nonequilibrium steady states, and dissipative perturbations are considered in addition to the Hamiltonian ones. We derive explicit expressions for the linear dynamical response functions for generalized dephasing channels and for Davies thermalizing generators. We introduce the notion of maximal harmonic response and compute it exactly for a single-qubit channel. Finally, we analyze linear response near dynamical phase transitions in quasifree open quantum systems. It is found that the effect of the dynamical phase transition shows up in a peak at the edge of the spectrum in the imaginary part of the dynamical response function.
Compaction shock dissipation in low density granular explosive
Rao, Pratap T.; Gonthier, Keith A.; Chakravarthy, Sunada
2016-06-01
The microstructure of granular explosives can affect dissipative heating within compaction shocks that can trigger combustion and initiate detonation. Because initiation occurs over distances that are much larger than the mean particle size, homogenized (macroscale) theories are often used to describe local thermodynamic states within and behind shocks that are regarded as the average manifestation of thermodynamic fields at the particle scale. In this paper, mesoscale modeling and simulation are used to examine how the initial packing density of granular HMX (C4H8N8O8) C4H8N8O8 having a narrow particle size distribution influences dissipation within resolved, planar compaction shocks. The model tracks the evolution of thermomechanical fields within large ensembles of particles due to pore collapse. Effective shock profiles, obtained by averaging mesoscale fields over space and time, are compared with those given by an independent macroscale compaction theory that predicts the variation in effective thermomechanical fields within shocks due to an imbalance between the solid pressure and a configurational stress. Reducing packing density is shown to reduce the dissipation rate within shocks but increase the integrated dissipated work over shock rise times, which is indicative of enhanced sensitivity. In all cases, dissipated work is related to shock pressure by a density-dependent power law, and shock rise time is related to pressure by a power law having an exponent of negative one.
Burcu Gülsevil Belber
2015-09-01
Full Text Available In this study, it was mentioned the situation of thermal tourism in Turkey and in the world, Turkey’s geothermal potential and utilization of the thermal tourism, the characteristics of the thermal waters and benefits in terms of health, activities related to the subject of the tourism ministry, elements of the marketing mix in the thermal plant, the status of the thermalplant in Kırşehir, a research about determining the level of satisfaction of the consumer who staying in thermal plants. Research was conducted by applying the survey methods to the tourist consumer accommodate in thermal plants. It has been demonstrated the factors affecting the level of satisfaction of participants by the agency of factor analysis and MANOVA analysis were made for the purpose ofresearch and were determined whether if they show changes according to demographic characteristics. According to results, it has appeared as the impact of factors “process management”, qualifications of the facility employees”, “qualifications of the facility”, “repurchase and recommend behaviors” on satisfaction of the consumer and these factors vary according totheir demographic characteristics.
Modeling helicity dissipation-rate equation
Yokoi, Nobumitsu
2016-01-01
Transport equation of the dissipation rate of turbulent helicity is derived with the aid of a statistical analytical closure theory of inhomogeneous turbulence. It is shown that an assumption on the helicity scaling with an algebraic relationship between the helicity and its dissipation rate leads to the transport equation of the turbulent helicity dissipation rate without resorting to a heuristic modeling.
From Molecular Dynamics to Dissipative Particle Dynamics
Flekkoy, Eirik G.; Coveney, Peter V.
1999-01-01
A procedure is introduced for deriving a coarse-grained dissipative particle dynamics from molecular dynamics. The rules of the dissipative particle dynamics are derived from the underlying molecular interactions, and a Langevin equation is obtained that describes the forces experienced by the dissipative particles and specifies the associated canonical Gibbs distribution for the system.
Fluctuation and Dissipation in Classical Many-Particle Systems
Csernai, L. P.; Jeon, S.; Kapusta, J. I.
1997-01-01
Coarse-grained Langevin-type effective field equations are derived for classical systems of particles. These equations include the effects of thermal fluctuation and dissipation which may arise from coupling to an external bath, as in the Brownian motion of a single particle, or which may arise from statistical fluctuations in small parts of an isolated many-particle system, as in sound waves. These equations may provide some guidance for the analysis of mesoscopic or microscopic molecular sy...
Classical and quantum dissipation in non homogeneous environments
Illuminati, F.; Patriarca, M.; Sodano, P.
1994-01-01
We generalize the oscillator model of a particle interacting with a thermal reservoir by introducing arbitrary nonlinear couplings in the particle coordinates.The equilibrium positions of the heat bath oscillators are promoted to space-time functions, which are shown to represent a modulation of the internal noise by the external forces. The model thus provides a description of classical and quantum dissipation in non homogeneous environments. In the classical case we derive a generalized Lan...
Persistent Currents and Dissipation in Narrow Bilayer Quantum Hall Bars
Kyriakidis, Jordan; Radzihovsky, Leo
2000-01-01
Bilayer quantum Hall states support a flow of nearly dissipationless staggered current which can only decay through collective channels. We study the dominant finite-temperature dissipation mechanism which in narrow bars is driven by thermal nucleation of pseudospin solitons. We find the finite-temperature resistivity, predict the resulting staggered current-voltage characteristics, and calculate the associated zero-temperature critical staggered current and gate voltage.
Deformed quantum harmonic oscillator with diffusion and dissipation
ISAR, A.; Scheid, W.
2007-01-01
A master equation for the deformed quantum harmonic oscillator interacting with a dissipative environment, in particular with a thermal bath, is derived in the microscopic model by using perturbation theory. The coefficients of the master equation and of equations of motion for observables depend on the deformation function. The steady state solution of the equation for the density matrix in the number representation is obtained and the equilibrium energy of the deformed harmonic oscillator i...
Scaling laws to quantify tidal dissipation in star-planet systems
Auclair-Desrotour, P.; Mathis, S.; Le Poncin-Lafitte, C.
2015-12-01
Planetary systems evolve over secular time scales. One of the key mechanisms that drive this evolution is tidal dissipation. Submitted to tides, stellar and planetary fluid layers do not behave like rocky ones. Indeed, they are the place of resonant gravito-inertial waves. Therefore, tidal dissipation in fluid bodies strongly depends on the excitation frequency while this dependence is smooth in solid ones. Thus, the impact of the internal structure of celestial bodies must be taken into account when studying tidal dynamics. The purpose of this work is to present a local model of tidal gravito-inertial waves allowing us to quantify analytically the internal dissipation due to viscous friction and thermal diffusion, and to study the properties of the resonant frequency spectrum of the dissipated energy. We derive from this model scaling laws characterizing tidal dissipation as a function of fluid parameters (rotation, stratification, diffusivities) and discuss them in the context of star-planet systems.
Scaling laws to quantify tidal dissipation in star-planet systems
Auclair-Desrotour, Pierre; Poncin-Lafitte, Christophe Le
2015-01-01
Planetary systems evolve over secular time scales. One of the key mechanisms that drive this evolution is tidal dissipation. Submitted to tides, stellar and planetary fluid layers do not behave like rocky ones. Indeed, they are the place of resonant gravito-inertial waves. Therefore, tidal dissipation in fluid bodies strongly depends on the excitation frequency while this dependence is smooth in solid ones. Thus, the impact of the internal structure of celestial bodies must be taken into account when studying tidal dynamics. The purpose of this work is to present a local model of tidal gravito-inertial waves allowing us to quantify analytically the internal dissipation due to viscous friction and thermal diffusion, and to study the properties of the resonant frequency spectrum of the dissipated energy. We derive from this model scaling laws characterizing tidal dissipation as a function of fluid parameters (rotation, stratification, diffusivities) and discuss them in the context of star-planet systems.
Dissipation and nuclear collective motion
This contribution is intended to give a brief summary of a forthcoming paper which shall review extensively the linear response theory for dissipation and statistical fluctuations as well as its application to heavy-ion collisions. It shall contain new results on the following subjects: numerical computations of response functions and transport coefficients; dissipation in a self-consistent treatment of harmonic vibrations; introduction of collective variables within a quantum theory. The method used consists of an extended version of the Bohm and Pines treatment of the electron gas. It allows to deduce a quantum Hamiltonian for the collective and intrinsic motion including coupling terms; discussion and solution of a quantal Master equation for non-linear collective motion. Additionally, a somewhat elaborate discussion of the problems of irreversibility is given, especially in connection to a treatment within the moving basis
Nuclear Dissipation from Fission Time
Gontchar, I.; Morjean, M.; Basnary, S. [GANIL DSM/CEA, IN2P3/CNRS, BP 5027, 14076 Caen Cedex 5 (France)
2000-04-21
Fission times, pre-scission neutron multiplicities and GDR pre-scission {gamma}-ray multiplicities measured for uranium or thorium nuclei formed with temperatures T {approx} 1.8 MeV have been compared with calculations performed with CDSM2, a two-dimensional dynamical model combined with a statistical one. Among the three experimental approaches considered, fission times give access to the most precise pieces of information on nuclear dissipation at high excitation energy. For the temperature range under consideration, an agreement between the model and data is achieved if one-body dissipation is used with a strength factor k{sub red} {approx} 0.45 {+-} 0.10 applied to the wall term for the mononuclear configuration. (authors)
Dissipative effects in projectile fragmentation
Reaction mechanisms in intermediate energy heavy ion collisions are studied. A two step model is proposed. Dissipative stage and abrasion stage are considered with special emphasis to phase space configuration of participant region. Fragmentation and damped collisions are found with their relative importance. Results are given for main observables and are compared to existing experimental data. Comparisons with other models are also discussed. (41 refs, 18 figs)
Energy dissipation in circular tube
A.D. Girgidov
2012-01-01
Energy dissipation distribution along the circular tube radius is important in solving such problems as calculation of heat transfer by the air flow through building envelope; calculation of pressure loss in spiral flows; calculation of cyclones with axial and tangential supply of dust-containing gas.Two types of one-dimensional radially axisymmetric flows in circular tube were considered: axial flow and rotation about the axis (Rankine vortex). Relying on two- and four-layer description of a...
K.V. Prasad
2013-01-01
Full Text Available The present study investigates the effects of internal heat generation/absorption, thermal radiation, magnetic field, and temperature-dependent thermal conductivity on the flow and heat transfer characteristics of a Non-Newtonian Maxwell fluid over a stretching sheet. The upper convected Maxwell fluid model is used to characterize the non-Newtonian fluid behavior. Similarity solutions for the governing equations are obtained with prescribed surface temperature (PST and/or with prescribed surface heat flux (PHF. Numerical solutions for the governing equations subject to the appropriate boundary conditions are obtained by a finite difference scheme known as Keller-Box method. The numerical results thus obtained are analyzed for the effects of the several pertinent parameters namely, the Maxwell parameter, the magnetic parameter, the temperature-dependent thermal conductivity parameter, the heat source/sink parameter, the Prandtl number, the Eckert number, and the thermal radiation parameter on the flow and heat transfer fields. Results for the velocity and temperature fields, skin friction, and Nusselt number are shown through graphs. It is observed that the thermal boundary layer thickness increases with increasing values of the elasticity parameter and the magnetic parameter; however it decreases with the Prandtl number.
Transient chaotic transport in dissipative drift motion
Oyarzabal, R. S.; Szezech, J. D.; Batista, A. M.; de Souza, S. L. T.; Caldas, I. L.; Viana, R. L.; Sanjuán, M. A. F.
2016-04-01
We investigate chaotic particle transport in magnetised plasmas with two electrostatic drift waves. Considering dissipation in the drift motion, we verify that the removed KAM surfaces originate periodic attractors with their corresponding basins of attraction. We show that the properties of the basins depend on the dissipation and the space-averaged escape time decays exponentially when the dissipation increases. We find positive finite time Lyapunov exponents in dissipative drift motion, consequently the trajectories exhibit transient chaotic transport. These features indicate how the transient plasma transport depends on the dissipation.
Cold collisions in dissipative optical lattices
Piilo, J
2004-01-01
In the past, light-assisted cold collisions between laser cooled atoms have been widely studied in magneto-optical atom traps (MOTs). We describe here theoretical studies of dynamical interactions, specifically cold collisions, between atoms trapped in near-resonant, dissipative optical lattices. The developed quantum-mechanical model is based on Monte Carlo wave-function simulations and combines atomic cooling and collision dynamics in a single framework. It turns out, that the radiative heating mechanism affects the dynamics of atomic cloud in a red-detuned lattice in a way that is not directly expected from the MOT studies. The optical lattice and position dependent light-matter coupling introduces selectivity of collision partners. Atoms, which are most mobile and energetic, are strongly favored to participate in collisions, and are more often ejected from the lattice, than the slow ones in the laser parameter region selected for study. For blue-detuned lattices, we study how optical shielding emerges as ...
Siboni, Nachshon; Abrego, David; Evenhuis, Christian; Logan, Murray; Motti, Cherie A.
2015-12-01
Crustose coralline algae (CCA) are well known for their ability to induce settlement in coral larvae. While their wide distribution spans reefs that differ substantially in temperature regimes, the extent of local adaptation to these regimes and the impact they have on CCA inductive ability are unknown. CCA Porolithon onkodes from Heron (southern) and Lizard (northern) islands on Australia's Great Barrier Reef (separated by 1181 km) were experimentally exposed to acute or prolonged thermal stress events and their thermal tolerance and recruitment capacity determined. A sudden onset bleaching model was developed to determine the health status of CCA based on the rate of change in the CCA live surface area (LSA). The interaction between location and temperature was significant ( F (2,119) = 6.74, p = 0.0017), indicating that thermally driven local adaptation had occurred. The southern population remained healthy after prolonged exposure to 28 °C and exhibited growth compared to the northern population ( p = 0.022), with its optimum temperature determined to be slightly below 28 °C. As expected, at the higher temperatures (30 and 32 °C) the Lizard Island population performed better that those from Heron Island, with an optimum temperature of 30 °C. Lizard Island CCA displayed the lowest bleaching rates at 30 °C, while levels consistently increased with temperature in their southern counterparts. The ability of those CCA deemed thermally tolerant (based on LSA) to induce Acropora millepora larval settlement was then assessed. While spatial differences influenced the health and bleaching levels of P. onkodes during prolonged and acute thermal exposure, thermally tolerant fragments, regardless of location, induced similar rates of coral larval settlement. This confirmed that recent thermal history does not influence the ability of CCA to induce settlement of A. millepora larvae.
Data envelopment analysis (DEA) has gained much popularity in performance measurement of power industry. This paper presents a slack-based measure approach to investigating the relationship between fossil fuel consumption and the environmental regulation of China's thermal power generation. We first calculate the total-factor energy efficiency without considering environmental constraints. An environmental performance indicator is proposed through decomposing the total-factor energy efficiency. The proposed approach is then employed to examine whether environmental regulation affects the energy efficiency of China's thermal power generation. We find that the environmental efficiency plays a significant role in affecting energy performance of China's thermal generation sector. Decreasing the discharge of major pollutants can improve both energy performance and environmental efficiency. Besides, we also have three main findings: (1) The energy efficiency and environmental efficiency were relatively low. (2) The energy and environmental efficiency scores show great variations among provinces. (3) Both energy efficiency and environmental efficiency are of obvious geographical characteristics. According to our findings, we suggest some policy implications. - Highlights: • We assess the energy efficiency and the environmental efficiency of China's thermal power generation simultaneously. • The energy efficiency and the environmental efficiency were relatively low during 2007–2009. • The energy efficiency and environmental efficiency show obvious geographic characters. • The environmental performance of a DMU plays a decisive role in the energy performance
Węglowski M. St.; Zeman M.; Grocholewski A.
2016-01-01
In the present study, the investigation of weldability of ultra-high strength steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5 on microstructure and mechanical properties of heat affected zone (HAZ) for a Weldox 1300 ultra-high strength steel. In the frame of these investigation the microstructure was studied by light and transmission electron microscopies. Mechanical properties of parent material were analysed by tensile...
Landau-Zener transitions mediated by an environment: Population transfer and energy dissipation
We study Landau-Zener transitions between two states with the addition of a shared discretized continuum. The continuum allows for population decay from the initial state as well as indirect transitions between the two states. The probability of nonadiabatic transition in this multichannel model preserves the standard Landau-Zener functional form except for a shift in the usual exponential factor, reflecting population transfer into the continuum. We provide an intuitive explanation for this behavior assuming individual, independent transitions between pairs of states. In contrast, the ground state survival probability at long time shows a novel, non-monotonic, functional form with an oscillatory behavior in the sweep rate at low sweep rate values. We contrast the behavior of this open-multistate model to other generalized Landau-Zener models incorporating an environment: the stochastic Landau-Zener model and the dissipative case, where energy dissipation and thermal excitations affect the adiabatic region. Finally, we present evidence that the continuum of states may act to shield the two-state Landau-Zener transition probability from the effect of noise
Effect of heat treatment on mechanical dissipation in Ta$_2$O$_5$ coatings
Martin, I W; Nawrodt, R; Fejer, M M; Gretarsson, A; Gustafson, E; Harry, G; Hough, J; MacLaren, I; Penn, S; Reid, S; Route, R; Rowan, S; Schwar, C; Seidel, P; Scott, J; Woodcraft, A L
2010-01-01
Thermal noise arising from mechanical dissipation in dielectric reflective coatings is expected to critically limit the sensitivity of precision measurement systems such as high-resolution optical spectroscopy, optical frequency standards and future generations of interferometric gravitational wave detectors. We present measurements of the effect of post-deposition heat treatment on the temperature dependence of the mechanical dissipation in ion-beam sputtered tantalum pentoxide between 11\\,K and 300\\,K. We find the temperature dependence of the dissipation is strongly dependent on the temperature at which the heat treatment was carried out, and we have identified three dissipation peaks occurring at different heat treatment temperatures. At temperatures below 200\\,K, the magnitude of the loss was found to increase with higher heat treatment temperatures, indicating that heat treatment is a significant factor in determining the level of coating thermal noise.
无
2003-01-01
In the viewpoint of heat transfer, heat transport potential capacity and its dissipation are defined based on the essence of heat transport phenomenon. Respectively, their physical meanings are the overall heat transfer capabilityand the dissipation rate of the heat transfer capacity. Then the least dissipation principle of heat transport potential capacity is presented to enhance the heat conduction efficiency in the heat conduction optimization. The principle is,for a conduction process with the constant integral of the thermal conductivityover the region, the optimal distribution of thermal conductivity, which corresponds to the highest heat conduction efficiency, is characterized by the least dissipation of heat transport potential capacity. Finally the principle is applied to some cases in heat conduction optimization.
Magnetic dissipation Spatial and temporal structure
Nordlund, A A
2002-01-01
A magnetically dominated plasma driven by motions on boundaries at which magnetic field lines are anchored is forced to dissipate the work being done upon it, no matter how small the electrical resistivity. Numerical experiments have clarified that dissipation is achieved through the formation of a hierarchy of electrical current sheets. The probability distribution function of the local winding of magnetic field lines is nearly Gaussian, with a width of the order unity. The dissipation is highly irregular in space and time, but the average level of dissipation is well described by a scaling law that is independent of the electrical resistivity. If the boundary driving is suspended for a period of time the magnetic dissipation rapidly drops to insignificant levels, leaving the magnetic field in a nearly force-free state. Renewed boundary driving leads to a quick return to dissipation levels compatible with the rate of boundary work, with dissipation starting much more rapidly than when starting from idealized...
TIDALLY INDUCED THERMAL RUNAWAYS ON EXTRASOLAR EARTHS: IMPACT ON HABITABILITY
We study the susceptibility of extrasolar Earth-like planets to tidal dissipation by varying orbital, rheological, and heat transfer parameters. We employ a three-dimensional numerical method solving the coupled problem of mantle convection and tidal dissipation. A reference model mimicking a plate tectonic regime and reproducing Earth's present-day heat output is considered. Four other models representing less efficient heat transfer regimes are also investigated. For these five initial models, we determine the orbital configurations under which a positive feedback between tidal dissipation and temperature evolution leads to a thermal runaway. In order to describe the occurrence of thermal runaways, we develop a scaling that relates the global dissipated power to a characteristic temperature and to the orbital parameters. For all numerical experiments sharing the same initial temperature conditions, we show that the reciprocal value of the runaway timescale depends linearly on the global dissipated power at the beginning of the simulation. In the plate tectonic-like regime, Earth-like planets in the habitable zone (HZ) of 0.1 Msun stars experience thermal runaways for 1:1 spin-orbit resonance if the eccentricity is sufficiently high (e>0.02 at a 4 day period, e>0.2 at a 10 day period). For less efficient convective regimes, runaways are obtained for eccentricities as low as ∼0.004 at the inner limit of the HZ. In the case of 3:2 spin-orbit resonance, the occurrence of thermal runaways is independent of eccentricity and is predicted for orbital periods lower than 12 days. For less efficient convective regimes, runaways may occur at larger orbital periods potentially affecting the HZ of stars with a mass up to 0.4 Msun. Whatever the convective regime and spin-orbit resonance, tidal heating within Earth-like planets orbiting in the HZ of stars more massive than 0.5 Msun is not significant.
Effect of heat treatment on mechanical dissipation in Ta$_2$O$_5$ coatings
Martin, I. W.; Bassiri, R.; Nawrodt, R.; Fejer, M. M.; Gretarsson, A.; Gustafson, E; Harry, G; Hough, J.; MacLaren, I.; Penn, S.; Reid, S.; Route, R; Rowan, S.; Schwarz, C; Seidel, P.
2010-01-01
Abstract Thermal noise arising from mechanical dissipation in dielectric reflective coatings is expected to critically limit the sensitivity of precision measurement systems such as high-resolution optical spectroscopy, optical frequency standards and future generations of interferometric gravitational wave detectors. We present measurements of the effect of post-deposition heat treatment on the temperature dependence of the mechanical dissipation in ion-beam sputtered tantalum pentoxide b...
Dilepton emission in high-energy heavy-ion collisions with dissipative hydrodynamics
Vujanovic, Gojko; Denicol, Gabriel S.; Shen, Chun; Luzum, Matthew; Schenke, Bjoern; Jeon, Sangyoung; Gale, Charles
2015-01-01
In this contribution we study the effects of three transport coefficients of dissipative hydrodynamics on thermal dilepton anisotropic flow observables. The first two transport coefficients investigated influence the overall size and growth rate of shear viscous pressure, while the last transport coefficient governs the magnitude of net baryon number diffusion in relativistic dissipative fluid dynamics. All calculations are done using state-of-the-art 3+1D hydrodynamical simulations. We show ...
Fluid particle dynamics: a synthesis of dissipative particle dynamics and smoothed particle dynamics
Español, Pep
1997-01-01
We present a generalization of dissipative particle dynamics that includes shear forces between particles. The new algorithm has the same structure as the (isothermal) smoothed particle dynamics algorithm, except that it conserves angular momentum and includes thermal fluctuations consistently with the principles of equilibrium statistical mechanics. This clarifies the connection of dissipative particle dynamics with numerical resolution algorithms of the macroscopic Navier-Stokes equations.
Rajneesh Kumar
2014-01-01
Full Text Available The reflection of plane waves at the free surface of thermally conducting micropolar elastic medium with two temperatures is studied. The theory of thermoelasticity with and without energy dissipation is used to investigate the problem. The expressions for amplitudes ratios of reflected waves at different angles of incident wave are obtained. Dissipation of energy and two-temperature effects on these amplitude ratios with angle of incidence are depicted graphically. Some special and particular cases are also deduced.
The work presents the development of new algorithms for calculating the fraction of thermal energy dissipated during the irradiation on the inner surface of pores. On the basis of these algorithms, the simulation of heat transfer in three-layered systems was carried out taking into account the dissipation of thermal energy in specimens having different porosity. We have performed quantitative estimates of the portion of dissipating thermal energy and its influence on the distribution of thermal stresses in thermal barrier coating systems. It was demonstrated that the presence of pores with a large internal surface area in the intermediate layer material enables two-fold decrease of the internal thermal stresses
C. Drogue
2000-01-01
Full Text Available In northern Vietnam, exposed carbonate rock formations cover an area of more than 50,000 km2 .Their accumulated thickness from the Cambrian to the Triassic is in some places as much as 3000 m. Numerous thermal waters (springs and wells occur in these strongly karstified carbonate massifs. This is the result of significant ancient and present orogenic activity, as the region demonstrates by its strong seismic activity. These karstic formations are water-bearing and strongly recharged by rainfall of between 1600 mm and 2000 mm per year in 90% of the area concerned. In view of the average annual air temperatures (17°C-25°C according to the region, 23 sample springs or wells were chosen with water temperatures of between 29°C and 68°C. Hydrochemical characteristics of these thermal waters emerging in different carbonate-rock units were examined by chemical analyses of major ions. In this large region, thermal waters are divided into four hydrochemical types: the Na-Cl type resulting from the intrusion of sea water for distances of up to several kilometres inland and depths of 1000 m, the Ca-SO4 type, probably resulting from the leaching of deposits of metallic sulphides that are widely distributed in these carbonate-rock units, and finally the Ca-HCO3 and Mg-HCO3 types which are chemically similar to fresh karstic waters in limestones and dolostones. The occurrence of these thermal groundwaters as well as their chemical characteristics seem to indicate the existence of large-scale deepseated groundwater flow systems in the karstic aquifers. Keywords: Vietnam; thermal waters; karst; hydrochemistry
Designing Biomimetic, Dissipative Material Systems
Balazs, Anna C. [Univ. of Pittsburgh, PA (United States). Chemical Engineering Dept.; Whitesides, George M. [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry and Chemical Biology; Brinker, C. Jeffrey [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering. Dept. of Chemistry. Dept. of Molecular Genetics and Microbiology. Center for Micro-Engineered Materials; Aranson, Igor S. [UChicago, LLC., Argonne, IL (United States); Chaikin, Paul [New York Univ. (NYU), NY (United States). Dept. of Physics; Dogic, Zvonimir [Brandeis Univ., Waltham, MA (United States). Dept. of Physics; Glotzer, Sharon [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Chemical Engineering. Dept. of Materials Science and Engineering. Dept. of Macromolecular Science and Engineering Physics; Hammer, Daniel [Univ. of Pennsylvania, Philadelphia, PA (United States). School of Engineering and Applied Science; Irvine, Darrell [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Materials Science and Engineering and Biological Engineering; Little, Steven R. [Univ. of Pittsburgh, PA (United States). Chemical Engineering Dept.; Olvera de la Cruz, Monica [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Parikh, Atul N. [Univ. of California, Davis, CA (United States). Dept. of Biomedical Engineering. Dept. of Chemical Engineering and Materials Science; Stupp, Samuel [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering. Dept. of Chemistry. Dept. of Medicine. Dept. of Biomedical Engineering; Szostak, Jack [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry and Chemical Biology
2016-01-21
Throughout human history, new materials have been the foundation of transformative technologies: from bronze, paper, and ceramics to steel, silicon, and polymers, each material has enabled far-reaching advances. Today, another new class of materials is emerging—one with both the potential to provide radically new functions and to challenge our notion of what constitutes a “material”. These materials would harvest, transduce, or dissipate energy to perform autonomous, dynamic functions that mimic the behaviors of living organisms. Herein, we discuss the challenges and benefits of creating “dissipative” materials that can potentially blur the boundaries between living and non-living matter.
Advanced thermal management materials
Jiang, Guosheng; Kuang, Ken
2012-01-01
""Advanced Thermal Management Materials"" provides a comprehensive and hands-on treatise on the importance of thermal packaging in high performance systems. These systems, ranging from active electronically-scanned radar arrays to web servers, require components that can dissipate heat efficiently. This requires materials capable of dissipating heat and maintaining compatibility with the packaging and dye. Its coverage includes all aspects of thermal management materials, both traditional and non-traditional, with an emphasis on metal based materials. An in-depth discussion of properties and m
Drogue, C.; Cat, N. N.; Dazy, J.
2000-01-01
In northern Vietnam, exposed carbonate rock formations cover an area of more than 50,000 km2 .Their accumulated thickness from the Cambrian to the Triassic is in some places as much as 3000 m. Numerous thermal waters (springs and wells) occur in these strongly karstified carbonate massifs. This is the result of significant ancient and present orogenic activity, as the region demonstrates by its strong seismic activity. These karstic formations are water-bearing and strongly recharge...
Drogue, C.; Cat, N. N.; Dazy, J.
2002-01-01
In northern Vietnam, exposed carbonate rock formations cover an area of more than 50,000 km2 .Their accumulated thickness from the Cambrian to the Triassic is in some places as much as 3000 m. Numerous thermal waters (springs and wells) occur in these strongly karstified carbonate massifs. This is the result of significant ancient and present orogenic activity, as the region demonstrates by its strong seismic activity. These karstic ...
Natural approach to quantum dissipation
Taj, David; Öttinger, Hans Christian
2015-12-01
The dissipative dynamics of a quantum system weakly coupled to one or several reservoirs is usually described in terms of a Lindblad generator. The popularity of this approach is certainly due to the linear character of the latter. However, while such linearity finds justification from an underlying Hamiltonian evolution in some scaling limit, it does not rely on solid physical motivations at small but finite values of the coupling constants, where the generator is typically used for applications. The Markovian quantum master equations we propose are instead supported by very natural thermodynamic arguments. They themselves arise from Markovian master equations for the system and the environment which preserve factorized states and mean energy and generate entropy at a non-negative rate. The dissipative structure is driven by an entropic map, called modular, which introduces nonlinearity. The generated modular dynamical semigroup (MDS) guarantees for the positivity of the time evolved state the correct steady state properties, the positivity of the entropy production, and a positive Onsager matrix with symmetry relations arising from Green-Kubo formulas. We show that the celebrated Davies Lindblad generator, obtained through the Born and the secular approximations, generates a MDS. In doing so we also provide a nonlinear MDS which is supported by a weak coupling argument and is free from the limitations of the Davies generator.
Power dissipation of air turbine VT - 400
Noga, Tomas; Žitek, Pavel
2016-06-01
This article provides an overview of ongoing systematic research of a turbine stage efficiency on a model air turbine VT 400. It contains an analysis of existing mathematical relations for a rotor friction dissipation calculation, on which basis a practical procedure of a calculation of those dissipations is recommended. Friction dissipations in the turbine rotor were divided into three main tasks: disc friction dissipations, shaft friction dissipations and dissipations in bearings. A contribution of performed work lies in the fact, that there is a dependence of rotor friction losses on its speed and a stage reaction has been revealed. This knowledge is completely essential for a further research, and will lead to more precise results of experiments. For the future, we plan to adjust the measuring track by adding a moment collar. We also assume an experimental verification of calculated friction losses.
Moving mirrors and the fluctuation-dissipation theorem
Stargen, D Jaffino; Sriramkumar, L
2016-01-01
We investigate the random motion of a mirror in (1 + 1)-dimensions that is immersed in a thermal bath of massless scalar particles which are interacting with the mirror through a boundary condition. Imposing the Dirichlet or the Neumann boundary conditions on the moving mirror, we evaluate the mean radiation reaction force on the mirror and the correlation function describing the fluctuations in the force about the mean value. From the correlation function thus obtained, we explicitly establish the fluctuation-dissipation theorem governing the moving mirror. Using the fluctuation-dissipation theorem, we compute the mean-squared displacement of the mirror at finite and zero temperature. We clarify a few points concerning the various limiting behavior of the mean-squared displacement of the mirror. While we recover the standard result at finite temperature, we find that the mirror diffuses logarithmically at zero temperature, confirming similar conclusions that have been arrived at earlier in this context. We a...
Scaling laws for the upper ocean temperature dissipation rate
Bogucki, D.J.; Huguenard, K.; Haus, B.K.; Özgökmen, T.M.; Reniers, A.J.H.M.; Laxague, N.J.M.
2015-01-01
Our understanding of temperature dissipation rate χ within the upper ocean boundary layer, which is critical for climate forecasts, is very limited. Near-surface turbulence also affects dispersion of contaminants and biogeochemical tracers. Using high-resolution optical turbulence measurements, scaling laws for χ are investigated under forcing states where either the daytime heat flux or the wind stress forcing is dominant. We find that χ remains constant over 1.5 times the significant wave h...
Dissipative heat engine is thermodynamically inconsistent
Makarieva, A. M.; Gorshkov, V. G.
2009-01-01
A heat engine operating on the basis of the Carnot cycle is considered, where the mechanical work performed is dissipated within the engine at the temperature of the warmer isotherm and the resulting heat is added to the engine together with an external heat input. The resulting work performed by the engine per cycle is increased at the expense of dissipated work produced in the previous cycle. It is shown that such a dissipative heat engine is thermodynamically inconsistent violating the fir...
Dissipative quantum theory: Implications for quantum entanglement
Rajagopal, A. K.; Rendell, R. W.
2001-01-01
Three inter-related topics are discussed here. One, the Lindblad dynamics of quantum dissipative systems; two, quantum entanglement in composite systems and its quantification based on the Tsallis entropy; and three, robustness of entanglement under dissipation. After a brief review of the Lindblad theory of quantum dissipative systems and the idea of quantum entanglement in composite quantum systems illustrated by describing the three particle systems, the behavior of entanglement under the ...
Semiclassics for a Dissipative Quantum Map
Braun, D; Haake, F; Braun, Daniel; Braun, Petr A.; Haake, Fritz
1998-01-01
We present a semiclassical analysis for a dissipative quantum map with an area-nonpreserving classical limit. We show that in the limit of Planck's constant to 0 the trace of an arbitrary natural power of the propagator is dominated by contributions from periodic orbits of the corresponding classical dissipative motion. We derive trace formulae of the Gutzwiller type for such quantum maps. In comparison to Tabor's formula for area-preserving maps, both classical action and stability prefactor are modified by the dissipation. We evaluate the traces explicitly in the case of a dissipative kicked top with integrable classical motion and find good agreement with numerical results.
Dissipative heat engine is thermodynamically inconsistent
Makarieva, A M
2009-01-01
A heat engine operating on the basis of the Carnot cycle is considered, where the mechanical work performed is dissipated within the engine at the temperature of the warmer isotherm and the resulting heat is added to the engine together with an external heat input. The resulting work performed by the engine per cycle is increased at the expense of dissipated work produced in the previous cycle. It is shown that such a dissipative heat engine is thermodynamically inconsistent violating the first and second laws of thermodynamics. The existing physical models employing the dissipative heat engine concept, in particular, the heat engine model of hurricane development, are physically invalid.
Viscous Dissipation and Criticality of Subducting Slabs
Riedel, Mike; Karato, Shun; Yuen, Dave
2016-04-01
Rheology of subducting lithosphere appears to be complicated. In the shallow part, deformation is largely accomodated by brittle failure, whereas at greater depth, at higher confining pressures, ductile creep is expected to control slab strength. The amount of viscous dissipation ΔQ during subduction at greater depth, as constrained by experimental rock mechanics, can be estimated on the basis of a simple bending moment equation [1,2] 2ɛ˙0(z) ∫ +h/2 2 M (z) = h ṡ ‑h/2 4μ(y,z)y dy , (1) for a complex multi-phase rheology in the mantle transition zone, including the effects of a metastable phase transition as well as the pressure, temperature, grain-size and stress dependency of the relevant creep mechanisms; μ is here the effective viscosity and ɛ˙0(z) is a (reference) strain rate. Numerical analysis shows that the maximum bending moment, Mcrit, that can be sustained by a slab is of the order of 1019 Nm per m according to Mcrit˜=σp ∗h2/4, where σp is the Peierl's stress limit of slab materials and h is the slab thickness. Near Mcrit, the amount of viscous dissipation grows strongly as a consequence of a lattice instability of mantle minerals (dislocation glide in olivine), suggesting that thermo-mechanical instabilities become prone to occur at places where a critical shear-heating rate is exceeded, see figure. This implies that the lithosphere behaves in such cases like a perfectly plastic solid [3]. Recently available detailed data related to deep seismicity [4,5] seems to provide support to our conclusion. It shows, e.g., that thermal shear instabilities, and not transformational faulting, is likely the dominating mechanism for deep-focus earthquakes at the bottom of the transition zone, in accordance with this suggested "deep criticality" model. These new findings are therefore briefly outlined and possible implications are discussed. References [1] Riedel, M. R., Karato, S., Yuen, D. A. Criticality of Subducting Slabs. University of Minnesota
Fujishima, K.
1986-03-01
Tympanic (Tty), mean skin (¯Tsk) and mean body (¯Tb) temperatures and heart rate (HR) increased more in low Vo2 max group (LG) than in high Vo2 max group (HG) during exercise. The regression coefficient of body temperatures (Tty and ¯Tb) on HR and the increased rate of heat storage were larger in LG than in HG during exercise. The local sweat rate (per min/cm2) during a hot water bath exhibited a considerable large quantity in comparison with the amount during exercise. Internal and skin temperatures during a hot water bath increased more immediately than those during exercise. The levels of comfort sensation during the preovulatory phase in women and pre-exercise period in men were higher at 40‡C than at 20‡C as peripheral thermal stimulus. The levels during the postovulatory and post-exercise phases in the same subjects were higher with the cool stimuli than with the warm stimuli. Above results suggest that thermoregulatory responses during submaximal exercise are different according to physical fitness and that these responses are different from those during hot water immersion. In addition, these suggest that the scores of thermal sensation with warm and cool stimuli are different during the pre- and post-ovulatory phases and the pre- and post-exercise periods.
Dissipative Dynamics of Quantum Fluctuations
Benatti, F; Floreanini, R
2015-01-01
One way to look for complex behaviours in many-body quantum systems is to let the number $N$ of degrees of freedom become large and focus upon collective observables. Mean-field quantities scaling as $1/N$ tend to commute, whence complexity at the quantum level can only be inherited from complexity at the classical level. Instead, fluctuations of microscopic observables scale as $1/\\sqrt{N}$ and exhibit collective Bosonic features, typical of a mesoscopic regime half-way between the quantum one at the microscopic level and the classical one at the level of macroscopic averages. Here, we consider the mesoscopic behaviour emerging from an infinite quantum spin chain undergoing a microscopic dissipative, irreversible dynamics and from global states without long-range correlations and invariant under lattice translations and dynamics. We show that, from the fluctuations of one site spin observables whose linear span is mapped into itself by the dynamics, there emerge bosonic operators obeying a mesoscopic dissipa...
Dissipative Shocks behind Bacteria Gliding
Virga, Epifanio G
2014-01-01
Gliding is a means of locomotion on rigid substrates utilized by a number of bacteria includingmyxobacteria and cyanobacteria. One of the hypotheses advanced to explain this motility mechanism hinges on the role played by the slime filaments continuously extruded from gliding bacteria. This paper solves in full a non-linear mechanical theory that treats as dissipative shocks both the point where the extruded slime filament comes in contact with the substrate, called the filament's foot, and the pore on the bacterium outer surface from where the filament is ejected. We prove that kinematic compatibility for shock propagation requires that the bacterium uniform gliding velocity (relative to the substrate) and the slime ejecting velocity (relative to the bacterium) must be equal, a coincidence that seems to have already been observed.
Power dissipation characteristics of great power and super high speed semiconductor switch
The power dissipation characteristics of pulsed power switch reversely switched dynistors (RSDs) are investigated in this paper. According to the expressions of voltage on RSD, derived from the plasma bipolar drift model and the RLC circuit equations of RSD main loop, the simulation waveforms of current and voltage on RSD are acquired through iterative calculation by using the fourth order Runge–Kutta method, then the curve of transient power on RSD versus time is obtained. The result shows that the total dissipation on RSD is trivial compared with the pulse discharge energy and the commutation dissipation can be nearly ignored compared with the quasi-static dissipation. These characteristics can make the repetitive frequency of RSD increase largely. The experimental results prove the validity of simulation calculations. The influence factors on power dissipation are discussed. The power dissipation increases with the increase of the peak current and the n-base width and with the decrease of n-base doping concentration. In order to keep a low power dissipation, it is suggested that the n-base width should be smaller than 320μm when doping concentration is 1.0×1014cm−3 while the doping concentration should be higher than 5.8×1013cm−3 when n-base width is 270μm. (condensed matter: structure, thermal and mechanical properties)
Photothermal microscopy: imaging of energy dissipation from photosynthetic complexes.
Gruszecki, Wieslaw I; Luchowski, Rafal; Zubik, Monika; Grudzinski, Wojciech
2015-10-01
An idea of a photothermal imaging microscopy (PTIM) is proposed, along with its realization based on a dependence of fluorescence anisotropy of dye molecules on heat emission in their nearest vicinity. Erythrosine B was selected as a fluorophore convenient to report thermal deactivation of the excited pigment-protein complex isolated from the photosynthetic apparatus of plants (LHCII), owing to the relatively large spectral gap between the fluorescence emission bands of chlorophyll a and a probe. Comparison of the simultaneously recorded images based on fluorescence lifetime of LHCII and fluorescence anisotropy of erythrosine shows a high rate of thermal energy dissipation from the aggregated forms of the complex and, possibly, thermal energy transmission along the protein supramolecular structures. Relatively high resolution of this novel microscopic technique, comparable to the fluorescence lifetime microscopy, enables its application in a nanoscale imaging and in nanothermography. PMID:26393534
Mid-Band Dissipative Spatial Solitons
Staliunas, Kestutis
2003-01-01
We show dissipative spatial solitons in nonlinear optical micro-resonators in which the refractive index is laterally modulated. In addition to "normal" and "staggered" dissipative solitons, similar to those in spatially modulated conservative systems, a narrow "mid-band" soliton is shown, having no counterparts in conservative systems.
Taylor's dissipation surrogate and its associated anomaly
McComb, David
2009-01-01
It is shown that, for stationary isotropic turbulence, Taylor's well known surrogate for the dissipation can be derived directly from the Karman-Howarth equation and is in fact a surrogate for inertial transfer, which becomes equal to the dissipation rate as the Reynolds number tends to infinity.
Robust dissipativity for uncertain impulsive dynamical systems
Liu Bin
2003-01-01
Full Text Available We discuss the robust dissipativity with respect to the quadratic supply rate for uncertain impulsive dynamical systems. By employing the Hamilton-Jacobi inequality approach, some sufficient conditions of robust dissipativity for this kind of system are established. Finally, we specialize the obtained results to the case of uncertain linear impulsive dynamical systems.
Symmetries of the dissipative Hofstadter model
Freed, D E
1993-01-01
The dissipative Hofstadter model, which describes a particle in 2-D subject to a periodic potential, uniform magnetic field, and dissipation, is also related to open string boundary states. This model exhibits an SL(2,Z) duality symmetry and hidden reparametrization invariance symmetries. These symmetries are useful for finding exact solutions for correlation functions.
SAITO Keiji; Kayanuma, Yosuke
2001-01-01
Dissipative effects on the nonadiabatic transition for the two and three level systems are studied. When the system is affected by a strong dissipation through the diabatic states, the exact transition probability is enumerated making use of the effective master equation. In the two-level system, we consider the case where the external field is swept from not only a negative large value but also from the resonant field, and the exact transition probabilities in these cases are derived. The tr...
Research on the Heat Dissipation Characteristics of Lithium Battery Spatial Layout in an AUV
Zhaoyong Mao; Shaokun Yan
2016-01-01
To meet the power demand requirements of autonomous underwater vehicles (AUVs), the power supply is generally composed of a large number of high-energy lithium battery groups. The lithium battery heat dissipation properties not only affect the underwater vehicle performance but also bring some security risks. Based on the widespread application of lithium batteries, lithium batteries in an AUV are taken as an example to investigate the heat dissipation characteristics of the lithium battery s...
Węglowski M. St.
2016-03-01
Full Text Available In the present study, the investigation of weldability of ultra-high strength steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5 on microstructure and mechanical properties of heat affected zone (HAZ for a Weldox 1300 ultra-high strength steel. In the frame of these investigation the microstructure was studied by light and transmission electron microscopies. Mechanical properties of parent material were analysed by tensile, impact and hardness tests. In details the influence of cooling time in the range of 2,5 ÷ 300 sec. on hardness, impact toughness and microstructure of simulated HAZ was studied by using welding thermal simulation test. The microstructure of ultra-high strength steel is mainly composed of tempered martensite. The results show that the impact toughness and hardness decrease with increase of t8/5 under condition of a single thermal cycle in simulated HAZ. The increase of cooling time to 300 s causes that the microstructure consists of ferrite and bainite mixture. Lower hardness, for t8/5 ≥ 60 s indicated that low risk of cold cracking in HAZ for longer cooling time, exists.
Material Systems for Blast-Energy Dissipation
James Schondel; Henry S. Chu
2010-10-01
Lightweight panels have been designed to protect buildings and vehicles from blast pressures by activating energy dissipation mechanisms under the influence of blast loading. Panels were fabricated which featured a variety of granular materials and hydraulic dissipative deformation mechanisms and the test articles were subjected to full-scale blast loading. The force time-histories transmitted by each technology were measured by a novel method that utilized inexpensive custom-designed force sensors. The array of tests revealed that granular materials can effectively dissipate blast energy if they are employed in a way that they easily crush and rearrange. Similarly, hydraulic dissipation can effectively dissipate energy if the panel features a high fraction of porosity and the panel encasement features low compressive stiffness.
Exploring quantum phases by driven dissipation
Lang, Nicolai; Büchler, Hans Peter
2015-07-01
Dephasing and decay are the intrinsic dissipative processes prevalent in any open quantum system and the dominant mechanisms for the loss of coherence and entanglement. This inadvertent effect not only can be overcome but can even be capitalized on in a dissipative quantum simulation by means of tailored couplings between the quantum system and the environment. In this context it has been demonstrated that universal quantum computation can be performed using purely dissipative elements, and furthermore, the efficient preparation of highly entangled states is possible. In this article, we are interested in nonequilibrium phase transitions appearing in purely dissipative systems and the exploration of quantum phases in terms of a dissipative quantum simulation. To elucidate these concepts, we scrutinize exemplarily two paradigmatic models: the transverse-field Ising model and the considerably more complex Z2 lattice gauge theory. We show that the nonequilibrium phase diagrams parallel the quantum phase diagrams of the Hamiltonian "blueprint" theories.
Analytical study of dissipative solitary waves
Dini, Fatemeh [Department of Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Emamzadeh, Mehdi Molaie [Department of Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Khorasani, Sina [School of Electrical Engineering, Sharif University of Technology, PO Box 11365-363, Tehran (Iran, Islamic Republic of); Bobin, Jean Louis [Universite Pierre et Marie Curie, Paris (France); Amrollahi, Reza [Department of Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Sodagar, Majid [School of Electrical Engineering, Sharif University of Technology, PO Box 11365-363, Tehran (Iran, Islamic Republic of); Khoshnegar, Milad [School of Electrical Engineering, Sharif University of Technology, PO Box 11365-363, Tehran (Iran, Islamic Republic of)
2008-02-15
In this paper, the analytical solution to a new class of nonlinear solitons is presented with cubic nonlinearity, subject to a dissipation term arising as a result of a first-order derivative with respect to time, in the weakly nonlinear regime. Exact solutions are found using the combination of the perturbation and Green's function methods up to the third order. We present an example and discuss the asymptotic behavior of the Green's function. The dissipative solitary equation is also studied in the phase space in the non-dissipative and dissipative forms. Bounded and unbounded solutions of this equation are characterized, yielding an energy conversation law for non-dissipative waves. Applications of the model include weakly nonlinear solutions of terahertz Josephson plasma waves in layered superconductors and ablative Rayleigh-Taylor instability.
Analytical study of dissipative solitary waves
In this paper, the analytical solution to a new class of nonlinear solitons is presented with cubic nonlinearity, subject to a dissipation term arising as a result of a first-order derivative with respect to time, in the weakly nonlinear regime. Exact solutions are found using the combination of the perturbation and Green's function methods up to the third order. We present an example and discuss the asymptotic behavior of the Green's function. The dissipative solitary equation is also studied in the phase space in the non-dissipative and dissipative forms. Bounded and unbounded solutions of this equation are characterized, yielding an energy conversation law for non-dissipative waves. Applications of the model include weakly nonlinear solutions of terahertz Josephson plasma waves in layered superconductors and ablative Rayleigh-Taylor instability
Minimising the heat dissipation of quantum information erasure
Hamed Mohammady, M.; Mohseni, Masoud; Omar, Yasser
2016-01-01
Quantum state engineering and quantum computation rely on information erasure procedures that, up to some fidelity, prepare a quantum object in a pure state. Such processes occur within Landauer's framework if they rely on an interaction between the object and a thermal reservoir. Landauer's principle dictates that this must dissipate a minimum quantity of heat, proportional to the entropy reduction that is incurred by the object, to the thermal reservoir. However, this lower bound is only reachable for some specific physical situations, and it is not necessarily achievable for any given reservoir. The main task of our work can be stated as the minimisation of heat dissipation given probabilistic information erasure, i.e., minimising the amount of energy transferred to the thermal reservoir as heat if we require that the probability of preparing the object in a specific pure state ≤ft|{\\varphi }1\\right.> be no smaller than {p}{\\varphi 1}{max}-δ . Here {p}{\\varphi 1}{max} is the maximum probability of information erasure that is permissible by the physical context, and δ ≥slant 0 the error. To determine the achievable minimal heat dissipation of quantum information erasure within a given physical context, we explicitly optimise over all possible unitary operators that act on the composite system of object and reservoir. Specifically, we characterise the equivalence class of such optimal unitary operators, using tools from majorisation theory, when we are restricted to finite-dimensional Hilbert spaces. Furthermore, we discuss how pure state preparation processes could be achieved with a smaller heat cost than Landauer's limit, by operating outside of Landauer's framework.
Calibration and temperature correction of heat dissipation matric potential sensors
Flint, A.L.; Campbell, G.S.; Ellett, K.M.; Calissendorff, C.
2002-01-01
This paper describes how heat dissipation sensors, used to measure soil water matric potential, were analyzed to develop a normalized calibration equation and a temperature correction method. Inference of soil matric potential depends on a correlation between the variable thermal conductance of the sensor's porous ceramic and matric poten-tial. Although this correlation varies among sensors, we demonstrate a normalizing procedure that produces a single calibration relationship. Using sensors from three sources and different calibration methods, the normalized calibration resulted in a mean absolute error of 23% over a matric potential range of -0.01 to -35 MPa. Because the thermal conductivity of variably saturated porous media is temperature dependent, a temperature correction is required for application of heat dissipation sensors in field soils. A temperature correction procedure is outlined that reduces temperature dependent errors by 10 times, which reduces the matric potential measurement errors by more than 30%. The temperature dependence is well described by a thermal conductivity model that allows for the correction of measurements at any temperature to measurements at the calibration temperature.
The METER (Meteorological Effects of Thermal Energy Releases) Program was organized to develop and verify methods for predicting the maximum amount of energy that can be dissipated to the atmosphere (through cooling towers or cooling ponds) from proposed nuclear energy centers without affecting...the local and regional environment. The initial program scope (mathematical modeling, laboratory and field experimentation, and societal impact assessment) has now narrowed to emphasis on the acquisition of field data of substantial quality and extent
Pantazopoulos, George; Toulfatzis, Anagnostis; Zormalia, Sylvia; Vazdirvanidis, Athanasios; Skarmoutsos, Dionysios
2012-10-01
The influence of heat treatment conditions on the mechanical behavior and microstructure of CuFe2P (ASTM C19400) in comparison to deoxidized-high-phosphorus (DHP-Cu/ASTM C12200) tubes was investigated. The aim of this study was the enhancement of understanding of microstructure/thermal treatment/strength relationships which could be further utilized for the manufacturing of components exhibiting superior performance and reliability for refrigeration and heat exchanger applications. Microstructural examination employing optical metallography and scanning electron microscopy is used for the evaluation of the recrystallization progress and grain growth processes. In addition, tensile testing was conducted to CuFe2P and DHP tubes following the application of heat treatment cycles, in accordance to the EN 10002-1 specifications. Mechanical properties and microstructure evaluation showed that CuFe2P material is fully recrystallized at 740 °C and DHP at 400 °C for 20 min. Recrystallization initiation varies within the range of 640-660 °C for CuFe2P and below 400 °C for DHP tubes. The tensile strength of the CuFe2P tube decreased from 513 to 367 MPa, the hardness was reduced from 144 to 126 HV, while tensile elongation was significantly improved from 3 to 17%. At 640 °C, only isolated recrystallized areas were evident mainly at the Fe-based intermetallic particle/copper matrix interface areas.
Maite MART(I)NEZ-EIXARCH; ZHU De-feng; Maria del Mar CATAL(A)-FORNER; Eva PLA-MAYOR; Nuria TOM(A)S-NAVARRO
2013-01-01
Field experiments were conducted in the Ebro Delta area (Spain),from 2007 to 2009 with two rice varieties:Gleva and Tebre.The experimental treatments included a series of seed rates,two different water management systems and two different nitrogen fertilization times.The number of leaves on the main stems and their emergence time were periodically tagged.The results indicated that the final leaf number on the main stems in the two rice varieties was quite stable over a three-year period despite of the differences in their respective growth cycles.Interaction between nitrogen fertilization and water management influenced the final leaf number on the main stems.Plant density also had a significant influence on the rate of leaf appearance by extending the phyllochron and postponing the onset of intraspecific competition after the emergence of the 7th leaf on the main stems.Final leaf number on the main stems was negatively related to plant density.A relationship between leaf appearance and thermal time was established with a strong nonlinear function.In direct-seeded rice,the length of the phyllochron increases exponentially in line with the advance of plant development.A general model,derived from 2-year experimental data,was developed and satisfactorily validated; it had a root mean square error of 0.3 leaf.An exponential model can be used to predict leaf emergence in direct-seeded rice.
FEA based Dissipation Energy and Temperature Distribution of Rubber Bushing
Zhengui Zhanga ,
2016-01-01
Full Text Available Rubber bushings used in the vehicle or aerospace can reduce the noise and vibration and absorb the shocks. The heat accumulation in the rubber components is attributed to the nonlinear mechanical behavior of rubber and leads to degeneration of mechanical properties. The viscoelastic damping is treated as the major mechanism of dissipation energy, which is heat source of temperature rising in bushing. A finite element method is expanded from elastic structure to viscoelastic structure and computes the dissipation energy distribution in the rubber core. Based on that heat source, the temperature distribution of rubber bushing under radial harmonic excitation has been calculated using finite volume method. The frequency and amplitude effect on dissipation energy and temperature distribution are described. The radial dynamic testing is carried out and the temperature is recorded using thermal imager to evaluate the simulation. As complement, the dynamic torsional testing is also carried out explore the possible failure zone of rubber bushing under different types of loading.