The Experts below are selected from a list of 103284 Experts worldwide ranked by ideXlab platform
Stanislav Stoupin - One of the best experts on this subject based on the ideXlab platform.
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x ray scattering from a plane parallel slab using Radiation transfer considerations
Journal of Applied Crystallography, 2020Co-Authors: Stanislav StoupinAbstract:The X-ray scattering power of a plane parallel homogeneous slab of material is derived using Radiation Intensity transfer equations. The scattering power scales with the ratio of the scattering coefficient of interest to the total attenuation coefficient. The results can be used to guide the choice of slab thickness, scattering geometry and photon energy to maximize the scattering power in both elastic and inelastic X-ray scattering experiments.
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x ray scattering from a plane parallel slab using Radiation transfer considerations
arXiv: Optics, 2020Co-Authors: Stanislav StoupinAbstract:X-ray scattering power of a plane parallel homogeneous slab of material is derived using Radiation Intensity transfer equations.The scattering power scales with the ratio of the scattering coefficient of interest to the total attenuation coefficient. The results can be used to guide the choice of slab thickness, scattering geometry and photon energy to maximize scattering power in both elastic and inelastic X-ray scattering experiments.
P J Coelho - One of the best experts on this subject based on the ideXlab platform.
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a comparison of spatial discretization schemes for differential solution methods of the radiative transfer equation
Journal of Quantitative Spectroscopy & Radiative Transfer, 2008Co-Authors: P J CoelhoAbstract:A comparison of discretization schemes required to evaluate the Radiation Intensity at the cell faces of a control volume in differential solution methods of the radiative transfer equation is presented. Several schemes developed using the normalized variable diagram and the total variation diminishing formalisms are compared along with essentially non-oscillatory schemes and genuinely multidimensional schemes. The calculations were carried out using the discrete ordinates method, but the analysis is equally valid for the finite-volume method. It is shown that the S schemes of the genuinely multidimensional family perform quite well, particularly in problems with discontinuous Radiation Intensity fields. However, they are time consuming, and so they do not always become more attractive regarding the trade-off between accuracy and computational requirements, in comparison with other high-order schemes that, although being less accurate, are also more economical.
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numerical simulation of the interaction between turbulence and Radiation in reactive flows
Progress in Energy and Combustion Science, 2007Co-Authors: P J CoelhoAbstract:The interaction between turbulence and Radiation (TRI) in reactive flows has been demonstrated experimentally, theoretically and numerically, and results from the highly non-linear coupling between fluctuations of Radiation Intensity and fluctuations of temperature and chemical composition of the medium. The instantaneous and the time-averaged form of the radiative transfer equation (RTE) are presented, and the TRI effects resulting from time-averaging are discussed. Methods to account for TRI in practical calculations are surveyed, and works where such methods have been employed are reviewed. These include both decoupled and coupled fluid flow/radiative transfer calculations. It is shown that the solution of the RTE using instantaneous scalar data is the most accurate way to deal with TRI, but it is computationally prohibitive for coupled problems. Hence, this approach has been mainly used to calculate the Radiation Intensity along lines of sight. The generation of time series of instantaneous scalar data may be accomplished using stochastic or deterministic models, which are also surveyed. Coupled fluid flow/radiative transfer problems are generally solved using the time-averaged form of the RTE or the Monte Carlo method, and rely on the optically thin fluctuation approximation, which neglects the correlation between fluctuations of the absorption coefficient and fluctuations of the Radiation Intensity. Experimental data and numerical calculations demonstrate that turbulent fluctuations may significantly increase the mean spectral Radiation Intensity in both non-luminous and luminous flames. Turbulent fluctuations contribute to decrease the flame temperature below the level observed without fluctuations, particularly for optically thick flames. The net radiative power and the fraction of radiative heat loss increase due to TRI, particularly in the case of optically thin flames. Recent direct numerical simulations provide additional insight on the role of different correlations responsible for TRI, and on how they are influenced by the optical thickness of the medium.
John D Joannopoulos - One of the best experts on this subject based on the ideXlab platform.
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thermal Radiation from photonic crystals a direct calculation
Physical Review Letters, 2004Co-Authors: Chiyan Luo, Arvind Narayanaswamy, Gang Chen, John D JoannopoulosAbstract:A classical simulation of equilibrium thermal emissivity from dispersive, lossy photonic crystals is presented. Normal emission results consistent with those assuming Kirchoff's law are obtained; i.e., a photonic crystal does not emit more than what a blackbody does. Significant enhancement, however, can be achieved over the Radiation Intensity from a uniform slab, indicating the potential usefulness of photonic crystals in incandescent lighting and thermal photovoltaic applications.
Radek Srb - One of the best experts on this subject based on the ideXlab platform.
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Differential Evolution and Heat Radiation Intensity Optimization
2014 International Conference on Mathematics and Computers in Sciences and in Industry, 2014Co-Authors: Jaroslav Mlýnek, Radek SrbAbstract:This article focuses on heat Radiation Intensity optimization across the surface of an aluminium mould. The inner mould surface is sprinkled with a special PVC powder and the outer mould surface is warmed by infrared heaters located above the mould. This is an economic way of producing artificial leathers in the automotive industry (e.g. The artificial leather on a car dashboard). The article includes a description of a mathematical model that allows us to calculate the heat Radiation Intensity across the mould surface for every fixed location of the heaters. We also use this mathematical model to optimize the location of the heaters to provide approximately the same heat Radiation Intensity across the whole mould surface during the warming of the mould. In this way we obtain a uniform colour tone and material structure of the artificial leather. The problem of optimization is more complicated. Using gradient methods is not suitable because the minimized function contains many local extremes. A differential evolution algorithm is used during the process of optimization. The calculations were performed by a Mat lab code written by the authors. The article contains a practical example including graphical outputs.
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the process of an optimized heat Radiation Intensity calculation on a mould surface
26th Conference on Modelling and Simulation, 2012Co-Authors: Jaroslav Mlýnek, Radek SrbAbstract:This article is focused on the optimization of heat Radiation Intensity across the surface of an aluminium mould. The mould is warmed by infrared heaters located above the mould surface, and in this way artificial leathers in the automotive industry are produced (e.g. the artificial leather on a car dashboard). This described model allows us to specify the location of infrared heaters over the mould to obtain approximately the same heat Radiation Intensity across the whole mould surface. In this way we can obtain a uniform material structure and colour tone across the whole surface of artificial leather. We used a genetic algorithm and the technique of “hill-climbing” during the optimization process. A computational procedure was programmed in the language Matlab.
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Artificial leather production in the automotive industry
2012 ELEKTRO, 2012Co-Authors: Jaroslav Mlýnek, Radek SrbAbstract:This article is focused on the process of artificial leather production in the automotive industry (e.g. the artificial leather on a car dashboard). One successful manufacturing process is the heating of the mould surface by infrared heaters located above the mould. We will describe one model of mould warming, as well as a method to calculate the heat Radiation Intensity on the mould surface in order to pinpoint the location of infrared heaters. During the calculation of heat Radiation Intensity across the mould surface, we will use experimental measured values for the heat Radiation Intensity from a sensor in proximity to an infrared heater. It is necessary to maintain approximately the same heat Radiation Intensity across the whole mould surface during warming process. The model described in this article allows us to optimize the infrared heaters' location for this purpose. In this way, we obtain the same material structure and color tone across the whole surface of an artificial leather. We will apply a genetic algorithm to optimize the heaters' location. A computational procedure of heat Radiation Intensity across mould surface and heaters location optimization was programmed in the language Matlab. The last chapter provides a practical example with a description of the solution.
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Optimization of a Heat Radiation Intensity on a Mould Surface in the Car Industry
Mechatronics, 2011Co-Authors: Jaroslav Mlýnek, Radek SrbAbstract:This article is focused on the process of the heat Radiation Intensity optimization on an aluminium mould surface intended for the production of artificial leather in the car industry (e.g. the artificial leather on a car dashboard). The inside of the mould surface is sprinkled with a special powder and its outside is heated by infra heaters located above the mould, up to a temperature of 250°C. It is necessary to carry out the configuration optimization of the infra heater locations above the mould in such way that the heat Radiation Intensity on the mould surface is approximately the same. The procedure of configuration optimization of the infra heater locations by use of a genetic algorithm is described in this paper. Experimental measured values for the heat Radiation Intensity in the surroundings of an infra heater are used for the calculation procedures.
I Seftelis - One of the best experts on this subject based on the ideXlab platform.
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design optimisation and conversion efficiency determination of a line focus parabolic trough solar collector ptc
Applied Energy, 2001Co-Authors: G C Bakos, I Ioannidis, N Tsagas, I SeftelisAbstract:PTCs are the preferred type of collector used for steam generation, due to their ability to work at high temperatures with high efficiencies. The results produced from a simulation program, showing the variation of collector's efficiency as a function of heat transfer fluid flux, pipe diameter, solar Radiation Intensity and active area of the PTC, are presented.
