The Experts below are selected from a list of 15465 Experts worldwide ranked by ideXlab platform
Eugene A Ustinov - One of the best experts on this subject based on the ideXlab platform.
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atmospheric weighting functions and surface partial derivatives for remote sensing of scattering planetary atmospheres in thermal spectral region general Adjoint approach
Journal of Quantitative Spectroscopy & Radiative Transfer, 2005Co-Authors: Eugene A UstinovAbstract:Abstract An approach to formulation of inversion algorithms for remote sensing in the thermal spectral region in the case of a scattering planetary atmosphere, based on the Adjoint Equation of radiative transfer (Ustinov (JQSRT 68 (2001) 195; JQSRT 73 (2002) 29); referred to as Papers 1 and 2, respectively, in the main text), is applied to the general case of retrievals of atmospheric and surface parameters for the scattering atmosphere with nadir viewing geometry. Analytic expressions for corresponding weighting functions for atmospheric parameters and partial derivatives for surface parameters are derived. The case of pure atmospheric absorption with a scattering underlying surface is considered and convergence to results obtained for the non-scattering atmospheres (Ustinov (JQSRT 74 (2002) 683), referred to as Paper 3 in the main text) is demonstrated.
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Adjoint sensitivity analysis of radiative transfer Equation 2 applications to retrievals of temperature in scattering atmospheres in thermal ir
Journal of Quantitative Spectroscopy & Radiative Transfer, 2002Co-Authors: Eugene A UstinovAbstract:Abstract An approach to formulation of inversion algorithms for thermal sounding in the case of scattering atmosphere based on the Adjoint Equation of radiative transfer (Ustinov, JQSRT 68 (2001) 195, referred to as Paper 1 in the main text) is applied to temperature retrievals in the scattering atmosphere for the nadir viewing geometry. Analytical expressions for the weighting functions involving the integration of the source function are derived. Temperature weighting functions for a simple model of the atmosphere with scattering are evaluated and convergence to the case of pure atmospheric absorption is demonstrated. The numerical experiments on temperature retrievals are carried out to demonstrate the validity of the expressions obtained.
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Adjoint sensitivity analysis of radiative transfer Equation temperature and gas mixing ratio weighting functions for remote sensing of scattering atmospheres in thermal ir
Journal of Quantitative Spectroscopy & Radiative Transfer, 2001Co-Authors: Eugene A UstinovAbstract:Abstract Sensitivity analysis based on of the Adjoint Equation of radiative transfer is applied to the case of atmospheric remote sensing in the thermal spectral region with non-negligible atmospheric scattering. Analytic expressions for the weighting functions for retrievals of temperature and gas mixing ratio are derived. It is demonstrated that these expressions include the case of pure absorption as a particular case when single scattering albedo of atmospheric scattering can be neglected.
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Adjoint sensitivity analysis of radiative transfer Equation temperature and gas mixing ratio weighting functions for remote sensing of scattering atmospheres in thermal ir
Journal of Quantitative Spectroscopy & Radiative Transfer, 2001Co-Authors: Eugene A UstinovAbstract:Sensitivity analysis based on using of the Adjoint Equation of radiative transfer is applied to the case of atmospheric remote sensing in the thermal spectral region with non-negligeable atmospheric scattering.
Mathieu Sellier - One of the best experts on this subject based on the ideXlab platform.
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estimation of thermal conductivity heat transfer coefficient and heat flux using a three dimensional inverse analysis
International Journal of Thermal Sciences, 2016Co-Authors: Farzad Mohebbi, Mathieu SellierAbstract:Abstract This paper presents a numerical inverse analysis to estimate the thermal conductivity, the heat transfer coefficient, and the heat flux in three dimensional irregular bodies in steady state heat conduction problems. In this study, a 3-D elliptic grid generation technique is used to mesh the irregular body. The 3-D Laplace Equation is solved in the computational domain to compute the temperature at any grid point in the meshed body. A novel and very efficient sensitivity analysis scheme is introduced to compute the sensitivity coefficients in gradient based optimization method. Using this sensitivity analysis scheme, one can solve the inverse problem without need to the solution of Adjoint Equation. The main advantages of the sensitivity analysis scheme are its simplicity, accuracy, and independency of the number of the direct problem solution from the number of the unknown variables which makes the numerical inverse analysis presented here very accurate and efficient. The conjugate gradient method (CGM) is used to minimize the objective function which is the difference between the computed temperature on part of the boundary and the measured temperature. The obtained results confirm that the proposed algorithm is very accurate, robust, and efficient.
Liming Ruan - One of the best experts on this subject based on the ideXlab platform.
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experimental research on noninvasive reconstruction of optical parameter fields based on transient radiative transfer Equation for diagnosis applications
Journal of Quantitative Spectroscopy & Radiative Transfer, 2019Co-Authors: Fangzhou Zhao, Yaobin Qiao, Yatao Ren, Linyang Wei, Arafat Islam, Liming RuanAbstract:Abstract The noninvasive reconstruction of optical parameter fields in participating phantom is investigated experimentally based on the measured time-resolved radiative signals, which are detected by the time-correlated single-photon counting system. The discrete ordinate method is employed to solve the forward transient radiative transfer Equation to simulate the time-resolved radiative transfer in the physical phantom exposed to ultra-short pulse laser irradiation. On top of that, the sequential quadratic programming algorithm based on the generalized Gaussian Markov random field is applied to solve the inverse problem. To improve the computational efficiency, an Adjoint Equation technique is adopted to determine the gradient of objective function. Good agreement was obtained between the predicted optical parameter fields and realistic ones. All the reconstruction results demonstrate that the proposed reconstruction methods are proved to be accurate and efficient experimentally.
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application of sqp algorithm for fluorescence tomography with the time domain Equation of radiative transfer
Journal of Quantitative Spectroscopy & Radiative Transfer, 2017Co-Authors: Yaobin Qiao, Hong Qi, Liming RuanAbstract:Abstract A reconstruction scheme for the fluorescence tomography is investigated based on the time-domain radiative transfer Equation (TD-RTE). Two coupled TD-RTEs, which can provide considerable measurement data, are used as the forward model and solved by the discrete ordinate method. The sequential quadratic programming (SQP) is employed to build the reconstruction scheme for solving the inverse problem. The gradient of objective function is calculated efficiently by the Adjoint Equation technique. Considering the ill-posed nature of the inverse problem, the regularization term based on the generalized Gaussian Markov random field (GGMRF) model is adopted to enhance the reconstructed image. Influence of the initial guess, contrast, noisy data, and shape of the fluorescent target are analyzed. Simulated results show that the proposed algorithm performs efficiently and accurately on reconstructing the distribution of the fluorescence yield.
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application of the sequential quadratic programming algorithm for reconstructing the distribution of optical parameters based on the time domain radiative transfer Equation
Optics Express, 2016Co-Authors: Yaobin Qiao, Yatao Ren, Jingwen Shi, Zeyu Zhang, Liming RuanAbstract:Sequential quadratic programming (SQP) is used as an optimization algorithm to reconstruct the optical parameters based on the time-domain radiative transfer Equation (TD-RTE). Numerous time-resolved measurement signals are obtained using the TD-RTE as forward model. For a high computational efficiency, the gradient of objective function is calculated using an Adjoint Equation technique. SQP algorithm is employed to solve the inverse problem and the regularization term based on the generalized Gaussian Markov random field (GGMRF) model is used to overcome the ill-posed problem. Simulated results show that the proposed reconstruction scheme performs efficiently and accurately.
Jalil Jamali - One of the best experts on this subject based on the ideXlab platform.
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direct estimation of local convective boiling heat transfer coefficient in mini channel by using conjugated gradient method with Adjoint Equation
International Communications in Heat and Mass Transfer, 2014Co-Authors: S D Farahani, Farshad Kowsary, Jalil JamaliAbstract:Abstract The purpose of this paper was to present an inverse heat conduction method used for determining the local convective boiling heat transfer coefficient in mini-channel for pure water, copper nanofluid by using three different concentrations of nanoparticles: 5 mg/L, 10 mg/L and 50 mg/L. Conjugated gradient method with Adjoint Equation is used to solve the IHCP and estimate directly the space-variable convective heat transfer coefficient. Direct estimation local convective boiling heat transfer coefficient is a nonlinear inverse heat problem. The uncertainties in the estimated in heat transfer coefficient are calculated using bias and variance errors. This method is able to estimate local convective boiling heat transfer coefficient very well.
Farzad Mohebbi - One of the best experts on this subject based on the ideXlab platform.
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estimation of thermal conductivity heat transfer coefficient and heat flux using a three dimensional inverse analysis
International Journal of Thermal Sciences, 2016Co-Authors: Farzad Mohebbi, Mathieu SellierAbstract:Abstract This paper presents a numerical inverse analysis to estimate the thermal conductivity, the heat transfer coefficient, and the heat flux in three dimensional irregular bodies in steady state heat conduction problems. In this study, a 3-D elliptic grid generation technique is used to mesh the irregular body. The 3-D Laplace Equation is solved in the computational domain to compute the temperature at any grid point in the meshed body. A novel and very efficient sensitivity analysis scheme is introduced to compute the sensitivity coefficients in gradient based optimization method. Using this sensitivity analysis scheme, one can solve the inverse problem without need to the solution of Adjoint Equation. The main advantages of the sensitivity analysis scheme are its simplicity, accuracy, and independency of the number of the direct problem solution from the number of the unknown variables which makes the numerical inverse analysis presented here very accurate and efficient. The conjugate gradient method (CGM) is used to minimize the objective function which is the difference between the computed temperature on part of the boundary and the measured temperature. The obtained results confirm that the proposed algorithm is very accurate, robust, and efficient.