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## Predicting asphalt pavement temperature with a three-dimentional finite element method

Minhoto, Manuel; Pais, Jorge; Pereira, Paulo; Picado-Santos, Luís
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.81%
A Three-dimensional (3D) finite element (FE) model was developed to calculate the temperature of a pavement located in Northeast of Portugal. A case study was developed to validate the model. Input data to the model were the hourly values for solar radiation, air temperature and mean daily values of wind speed obtained from a meteorological station. The thermal response of a multilayered pavement structure was modeled with a transient thermal analysis for 4 months (December 2003 to April 2004) and the analysis was initiated with a full-depth constant initial temperature obtained from field measurements. During these 4 months, the pavement temperature was measured at a new pavement section, located in IP4 main road, near Bragança, in northern Portugal. At this location, seven thermocouples were installed in the asphalt concrete layers at seven different depths. These pavement data were used to validate this simulation model by a comparison of model calculated data with measured pavement temperatures. The 3D FE analysis proved to be a interesting tool to simulate the transient behavior of asphalt concrete pavements. The suggested simulation model can predict the pavement temperature at different levels of bituminous layers with good accuracy. É apresentado um modelo numérico...

## Limite de altas temperaturas em presença de campos externos estáticos; High temperature limit in static background fields

Siqueira, João Bosco de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Relevância na Pesquisa
55.91%
Investigamos certas propriedades físicas da teoria de campos a temperatura finita. Mostramos que, na presença de campos externos bosonicos, o limite de altas temperaturas das funções de Green pode ser obtido supondo que todas as componentes dos momentos externos sao nulas, para todas as funções de Green 1PI em ordem de um laco e em ordem de dois laços para a auto-energia. No contexto do método do campo de fundo, este resultado implica que a lagrangiana efetiva estática de um campo externo bosonico pode ser obtida calculando a pressão na presença de um campo externo independente do espaço-tempo, no limite de altas temperaturas. Aplicamos este resultado para obter a lagrangiana efetiva estática de um campo de Maxwell interagindo com um plasma da QED em ordem de dois laços. Obtivemos também a lagrangiana efetiva estática de um campo gravitacional interagindo com um campo escalar real livre, e com um plasma da QED em ordem de dois laços.; We have investigated some physical proprieties of nite temperature field theory. We have shown that, in the presence of an external bosonic field, the high temperature limit of the static Green's functions can be obtained assuming that all components of the external momenta are zero. This was shown to be the case for all 1PI Green's functions...

## Desenvolvimento de um modelo numérico de uma chama sem pré-mistura de combustível de baixo poder calorífico no interior de um tubo; Development of a numerical model to low calorific fuel flame without pre-mixing of fuel inside a tube

Pinto Neto, Milton Mario Moreira
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
POR
Relevância na Pesquisa
45.71%
O estudo em questão propõe o desenvolvimento de um modelo numérico para analisar o comportamento de uma chama sem pré-mistura para um combustível de baixo poder calorífico no interior de um tubo em escoamento laminar. A ferramenta numérica implementada permite gerar o campo de fração de mistura e o campo de temperatura para o escoamento de ar e combustível no interior do tubo em regime permanente. Para tal, foi construído um modelo axissimétrico para desenvolver as equações de conservação de energia, momento e transporte da fração de mistura utilizando o método dos volumes finitos através do método iterativo de Gauss-Seidel e Power Low como esquema de interpolação.; The study proposes the development of a numerical model to analyse a low calorific fuel flame without pre-mixing inside a tube under laminar flow. The implemented numeric tool allows generating the mixture fraction field and the temperature field to the air-fuel flow inside the tube under permanent regime. Therefore, it was built an axisymmetric model to develop the energy conservation equations for the mixture fraction using the Finite Volume Method through the Gauss-Seidel iterative method and Power Low as interpolation scheme.

## Temperature Field Reconstruction for Minimally Invasive Cryosurgery With Application to Wireless Implantable Temperature Sensors and/or Medical Imaging

Thaokar, Chandrajit; Rabin, Yoed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.9%
There is an undisputed need for temperature-field reconstruction during minimally invasive cryosurgery. The current line of research focuses on developing miniature, wireless, implantable, temperature sensors to enable temperature-field reconstruction in real time. This project combines two parallel efforts: (i) to develop the hardware necessary for implantable sensors, and (ii) to develop mathematical techniques for temperature-field reconstruction in real time—the subject matter of the current study. In particular, this study proposes an approach for temperature-field reconstruction combining data obtained from medical imaging, cryoprobe-embedded sensors, and miniature, wireless, implantable sensors, the development of which is currently underway. This study discusses possible strategies for laying out implantable sensors and approaches for data integration. In particular, prostate cryosurgery is presented as a developmental model and a two-dimensional proof-of-concept is discussed. It is demonstrated that the lethal temperature can be predicted to a significant degree of certainty with implantable sensors and the technique proposed in the current study, a capability that is yet unavailable.

## A numerical study of the influence of temperature fluctuations in the thermal radiation field

Santos, Elizaldo Domingues dos; Galar??a, Marcelo Moraes; Mossi, Anderson Chaves; Petry, Adriane Prisco; Fran??a, Francis Henrique Ramos
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.85%
The present paper performs a numerical study of the influence of fluctuations on the temperature field over the thermal radiation field with the purpose to simulate the effect of Turbulence-Radiation Interactions (TRI). To evaluate the behavior of the divergence of the radiant heat flux for a flame in a cylindrical cavity, four temperature profiles are imposed: na average temperature profile and other three with 10%, 20% and 30% of turbulence intensity. The radiative transfer equation is solved using the discrete ordinates method (DOM) and the participating medium is treated as a gray gas. The results demonstrate that the fluctuations of temperature profiles increase significantly the mean divergence of the radiant heat flux in comparison with the average temperature profile, reaching to approximately 20% for the profile with 30% of turbulence intensity.

## Violação da invariância de Lorentz no regime de temperatura finita; Lorentz invariance violation in the finite temperature regime

Leite, Júlio Rafael da Silva
Fonte: Universidade Federal de Alagoas; BR; Física geral; Física teórica e computacional; Mecânica estatística; Ótica; Ótica não linear; Proprie; Programa de Pós-Graduação em Física da Matéria Condensada; UFAL Publicador: Universidade Federal de Alagoas; BR; Física geral; Física teórica e computacional; Mecânica estatística; Ótica; Ótica não linear; Proprie; Programa de Pós-Graduação em Física da Matéria Condensada; UFAL
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
45.73%
In this master s thesis, we have studied the possibility of Lorentz invariance violation by considering some terms of the standard-model extesion (SME), specifically, those terms which refer to the quantum electrodynamics extension. We have performed quantum corrections in the fermionic sector of the usual quantum electrodynamics with added terms which violate the Lorentz and CPT symmetries in two different configurations. Firstly, adding operators governed by the coefficient gκλμ and, in a later time, adding operators governed by the coefficient bμ. In the theory with the coefficient gκλμ, we have performed quantum corrections in order to induce, in the bosonic sector of the theory, the conventional Chern-Simons and the higher-derivative terms, and analyze the behavior of both terms in the finite temperature regime, by using the method of derivative expansion and the Matsubara formalism. On the other hand, in the model with the coefficient bμ, we have performed quantum corrections in order to induce, in the bosonic sector, the higher-derivative Chern-Simons term, by using the method of derivative expansion and, subsequently, analyze the behavior of this term in the finite temperatura regime...

## Finite temperature field theory on the Moyal plane

Akofor, Earnest; Balachandran, Aiyalan P.
Fonte: The American Physical Society Publicador: The American Physical Society
Tipo: Artigo de Revista Científica Formato: text/html
Relevância na Pesquisa
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In this paper, we initiate the study of finite temperature quantum field theories on the Moyal plane. Such theories violate causality which influences the properties of these theories. In particular, causality influences the fluctuation-dissipation theorem: as we show, a disturbance in a space-time region M1 creates a response in a space-time region M2 spacelike with respect to M1 (M1×M2). The relativistic Kubo formula with and without noncommutativity is discussed in detail, and the modified properties of relaxation time and the dependence of mean square fluctuations on time are derived. In particular, the Sinha-Sorkin result [Phys. Rev. B 45, 8123 (1992)] on the logarithmic time dependence of the mean square fluctuations is discussed in our context. We derive an exact formula for the noncommutative susceptibility in terms of the susceptibility for the corresponding commutative case. It shows that noncommutative corrections in the four-momentum space have remarkable periodicity properties as a function of the four-momentum k. They have direction dependence as well and vanish for certain directions of the spatial momentum. These are striking observable signals for noncommutativity. The Lehmann representation is also generalized to any value of the noncommutativity parameter θ(μν) and finite temperatures.; This work was supported by the US Department of Energy under grant number DE-FG02-85ER40231 and by the Universidad Carlos III de Madrid.; 10 pages...

## Numerical Simulation of Zr-based Bulk Metallic Glass During Continuous Casting Solidification Process

Tang,Renhong; Zhou,Bingwen; Ma,Yuejiao; Jia,Fei; Zhang,Xingguo
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Relevância na Pesquisa
45.82%
A numerical simulation method was used to analyze the solidification process of Zr-based bulk metallic glass (BMG) during the horizontal continuous casting (HCC) process. The large-scale general-purpose finite element analysis software ANSYS was adopted to develop a temperature field model. The variation of temperature field in the specific area at different time was studied. Its accuracy was verified by the experimental results of Zr48Cu36Ag8Al8 bulk metallic glass continuous casting solidification process. The effects of casting parameters include intermittent casting procedure (drawing and stopping), casting speed, pouring temperature and cooling rate. The results show that the optimum casting speed range is 1-2 mm/s, pouring temperature is 1223 K and cooling rate of 10 mm rod casting is 5 L/min respectively. A fully Zr-based bulk metallic glass whose diameter is 10 mm and length has no limitation has been successfully fabricated.

## Thermal stresses of a trimaterial medium in a nonuniform temperature field

Neibert, Michael Joseph
Tipo: Tese de Doutorado Formato: 99 p.
EN_US
Relevância na Pesquisa
55.8%
Approved for public release: Distribution is unlimited; The objective of this investigation was to conduct a parametric study of the effect of a nonuniform temperature field on the system behavior of a trilayered medium. In particular, the resulting shear and normal stresses along the media interfaces are analyzed. A finite element model utilizing a recently developed element which provides for both axial and lateral displacement continuity is employed. First, the effect of the material properties, that is, Young's Modulus and coefficient of thermal expansion, is examined. Then, the effect of the geometric properties, that is, length and thickness dimensions of the midlayer, is analyzed. Finally, a study of the effect of a nonuniform temperature field on the trimaterial medium is conducted; http://archive.org/details/thermalstresseso00neib; Lieutenant, United States Navy

## Processing of temperature field in chemical microreactors with infrared thermography

PRADERE, Christophe; JOANICOT, Mathieu; BATSALE, Jean-Christophe; TOUTAIN, Jean; GOURDON, Christophe
Fonte: Lavoisier, Taylor & Francis Publicador: Lavoisier, Taylor & Francis
EN_US
Relevância na Pesquisa
65.85%
This work is devoted to the first analysis of temperature fields related to chemical microfluidic reactors. The heat transport around and inside a microchannel is both convective and diffusive with spatial distribution of source terms and strong conductive effects in the channel surrounding. With simplified assumptions, it is shown that Infrared thermography and processing methods of the temperature frames allow to estimate important fields for the chemical engineers, such as the heating source distribution of the chemical reaction along the channel. A validation experiment of a temperature field processing method is proposed with Joule effect as calibrated source term and non reactive fluids. From such previous experiment, a Peclet field is estimated and used in a further step in order to study an acid-base flow configuration

## Statistics and scaling properties of temperature field in symmetrical non-Oberbeck-Boussinesq turbulent convection

Burnishev, Yuri; Steinberg, Victor
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.82%
The influence of symmetrical non-Oberbeck-Boussinesq (SNOB) effect on statistical and scaling properties of temperature field in turbulent convection is investigated experimentally in $SF_{6}$ in the vicinity of its gas-liquid critical point (CP). The main conclusion of the studies is that besides the strong $Ra$ and $Pr$ dependence of the rms of temperature fluctuations normalized by the temperature difference across the cell, different from the Oberbeck-Boussinesq (OB) case of turbulent convection, all rest of statistical and scaling properties of temperature field discussed in details are the same as in the OB case.; Comment: 28 pages, 25 figures

## Effects of shock topology on temperature field in compressible turbulence

Ni, Qionglin; Chen, Shiyi
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.87%
Effects of two types of shock topology, namely, small-scale shocklet and large-scale shock wave, on the statistics of temperature in compressible turbulence were investigated by simulations. The shocklet and shock wave are caused by the solenoidal and compressive modes of driven forces, respectively. Hereafter, the related two flows are called as SFT and CFT, respectively. It shows that in SFT the temperature spectrum follows the k^-5/3 power law, and the temperature field has "ramp-cliff" structures. By contrast, in CFT the temperature spectrum obeys the k^-2 power law, and the temperature field is dominated by large-scale rarefaction and compression. The power-law exponents for the p.d.f. of large negative dilatation are -2.5 in SFT and -3.5 in CFT, close to theoretical values. For the isentropic assumption of thermodynamic variables, the derivation in SFT grows with the turbulent Mach number (Mt), and for same Mt, the variables in CFT are more anisentropic. The angle statistics shows that the temperature gradient in CFT is preferentially perpendicular to the anisotropic strain rate tensor. It tends to be parallel with the first eigenvector and be orthogonal with the other two eigenvectors. For the cascade of temperature, the temperature variance is increased by the viscous dissipation and the pressure-dilatation...

## Tracer diffusivity in a time or space dependent temperature field

Golestanian, Ramin; Ajdari, Armand
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.72%
The conventional assumption that the self-diffusion coefficient of a small tracer can be obtained by a local and instantaneous application of Einstein's relation in a temperature field with spatial and temporal heterogeneity is revisited. It is shown that hydrodynamic fluctuations contribute to the self-diffusion tensor in a universal way, i.e. independent of the size and shape of the tracer. The hydrodynamic contribution is anisotropic--it reflects knowledge of the global anisotropy in the temperature profile, leading to anisotropic self-diffusion tensor for a spherical tracer. It is also retarded--it creates memory effects during the diffusion process due to hydrodynamic interactions.; Comment: 4 pages, 1 figure, to appear in Europhysics Letters

## Statistical Anisotropic Gaussian Simulations of the CMB Temperature Field

Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.95%
Although theoretically expected to be Statistically Isotropic (SI), the observed Cosmic Microwave Background (CMB) temperature \& polarization field would exhibit SI violation due to various inevitable effects like weak lensing, Doppler boost and practical limitations of observations like non-circular beam, masking etc. However, presence of any SI violation beyond these effects may lead to a discovery of inherent cosmic SI violation in the CMB temperature \& polarization field. Recently, Planck presented strong evidence of SI violation as a dipolar power asymmetry of the CMB temperature field in two hemispheres. Statistical studies of SI violation effect require non-SI (nSI) Gaussian realizations of CMB temperature field. The nSI Gaussian temperature field leads to non-zero off-diagonal terms in the Spherical Harmonics (SH) space covariance matrix encoded in the coefficients of the Bipolar Spherical Harmonics (BipoSH) representation. We discuss an effective numerical algorithm, Code for Non-Isotropic Gaussian Sky (CoNIGS) to generate nSI realizations of Gaussian CMB temperature field of Planck like resolution with specific cases of SI violation. Realizations of nSI CMB temperature field are obtained for non-zero quadrupolar $(L=2)$ BipoSH measurements by WMAP...

## Computing Spectral Densities in Finite Temperature Field Theory

Jeon, Sangyong
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.72%
Convenient Cutkosky-like diagrammatic rules for computing the spectral densities of arbitrary two-point correlation functions in finite temperature field theory are derived. The approach is based on an explicit analytic continuation of imaginary-time Feynman diagrams and avoids the complications of real-time finite temperature perturbation theory. The application of this method to the perturbative evaluation of transport coefficients is briefly discussed.; Comment: 51 pages, in latex using revtex macros, 12 figures in postscript, appended. UW/PT-92-03

## Finite temperature field theory and phase transitions

Quiros, Mariano
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.85%
We review different aspects of field theory at zero and finite temperature, related to the theory of phase transitions. We discuss different renormalization conditions for the effective potential at zero temperature, emphasizing in particular the MS-bar renormalization scheme. Finite temperature field theory is discussed in the real and imaginary time formalisms, showing their equivalence in simple examples. Bubble nucleation by thermal tunneling, and the subsequent development of the phase transition is described in some detail. Some attention is also devoted to the breakdown of the perturbative expansion and the infrared problem in the finite temperature field theory. Finally the application to baryogenesis at the electroweak phase transition is done in the Standard Model and in the Minimal Supersymmetric Standard Model. In all cases we have translated the condition of not washing out any previously generated baryon asymmetry by upper bounds on the Higgs mass.; Comment: 73 pages, 9 figures. Based on lectures given at the Summer School in High Energy Physics and Cosmology, ICTP, Trieste (Italy) 29 June--17 July 1998

## Restoration of chiral symmetry in light-front finite temperature field theory

Strauß, S.; Beyer, M.; Mattiello, S.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.78%
We investigate the properties of $qq$ and $q\bar q$ states in hot and dense quark matter in the framework of light-front finite temperature field theory. Presently we use the Nambu Jona-Lasinio model of QCD and derive the gap equation at finite temperature and density. We study pionic and scalar diquark dynamics in quark matter and calculate the masses and the Mott dissociation as a function of the temperature $T$ and the chemical potential $\mu$. For the scalar diquark we determine the critical temperature of color superconductivity.; Comment: 4 pages, 3 figures, Presented by S.Strau\ss at Light-Cone 2004, Amsterdam, 16 - 20 August

## Low temperature field-effect in crystalline organic material

Butko, V. Y.; Lashley, J. C.; Ramirez, A. P.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.8%
Molecular organic materials offer the promise of novel electronic devices but also present challenges for understanding charge transport in narrow band systems. Low temperature studies elucidate fundamental transport processes. We report the lowest temperature field effect transport results on a crystalline oligomeric organic material, rubrene. We find field effect switching with on-off ratio up to 10^7 at temperatures down to 10 K. Gated transport shows a factor of ~10 suppression of the thermal activation energy in 10-50 K range and nearly temperature independent resistivity below 10 K.; Comment: 5 pages, 4 figures

## A variational formulation for dissipative fluids with interfaces in an inhomogeneous temperature field

Fukagawa, Hiroki; Liu, Chun; Tsuji, Takeshi
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
45.77%
We propose a formalization for dissipative fluids with interfaces in an inhomogeneous temperature field from the viewpoint of a variational principle. Generally, the Lagrangian of a fluid is given by the kinetic energy density minus the internal energy density. The necessary condition for minimizing an action with subject to the constraint of entropy yields the equation of motion. However, it is sometimes to know the proper equation of entropy. Our main purpose is to obtain it by using the three requirements, which are a generalization of Noether's Theorem, the second law of thermodynamics, and well-posedness. To illustrate this approach, we investigate several phenomena in an inhomogeneous temperature field. In the case of vaporization, diffusion and the rotation of a chiral liquid crystals, we clarify the cross effects between the entropy flux and these phenomena via the internal energy.; Comment: 16 pages, 1 figure

## A Tracing of the Fractional Temperature Field

Shi, S. G.; Xiao, J.
This note is devoted to a study of $L^q$-tracing of the fractional temperature field $u(t,x)$ -- the weak solution of the fractional heat equation $(\partial_t+(-\Delta_x)^\alpha)u(t,x)=g(t,x)$ in $L^p(\mathbb R^{1+n}_+)$ subject to the initial temperature $u(0,x)=f(x)$ in $L^p(\mathbb R^n)$.; Comment: 20 pages