The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Lisong Zhang - One of the best experts on this subject based on the ideXlab platform.
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investigation on the effective thermal conductivity of carbonized high silica phenolic ablative material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based ablative material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized ablative material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic ablative material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
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Investigation on the effective thermal conductivity of carbonized high silica/phenolic ablative material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based ablative material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized ablative material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic ablative material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
Yexin Xu - One of the best experts on this subject based on the ideXlab platform.
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investigation on the effective thermal conductivity of carbonized high silica phenolic ablative material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based ablative material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized ablative material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic ablative material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
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Investigation on the effective thermal conductivity of carbonized high silica/phenolic ablative material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based ablative material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized ablative material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic ablative material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
Hong Ye - One of the best experts on this subject based on the ideXlab platform.
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investigation on the effective thermal conductivity of carbonized high silica phenolic ablative material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based ablative material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized ablative material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic ablative material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
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Investigation on the effective thermal conductivity of carbonized high silica/phenolic ablative material
International Journal of Heat and Mass Transfer, 2017Co-Authors: Yexin Xu, Hong Ye, Lisong ZhangAbstract:Abstract As a phenolic resin-based ablative material, high silica/phenolic composite is widely used in aerospace field. However, the effective thermal conductivity of carbonized ablative material formed during ablation process is rarely reported. In this work, carbonized sample of the high silica/phenolic ablative material was obtained by a carbonization process, and its effective thermal conductivity was measured from 100 to 970 °C. In addition, an analysis model of the effective thermal conductivity of the carbonized ablator consisting of fiber yarns and carbonized phenolic was established based on the result of structure analysis. The measured value of the effective thermal conductivity of the carbonized phenolic was used to inverse the transverse effective thermal conductivity of the fiber yarns. When the inversed values were adopted in different empirical models, it was found that the Clayton model is suitable for predicting the effective thermal conductivity of the carbonized high silica/phenolic.
J.m.f. Moura - One of the best experts on this subject based on the ideXlab platform.
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Inversion of block matrices with block banded inverses: application to Kalman-Bucy filtering
2000 IEEE International Conference on Acoustics Speech and Signal Processing. Proceedings (Cat. No.00CH37100), 2000Co-Authors: A. Asif, J.m.f. MouraAbstract:We investigate the properties of block matrices with block banded inverses to derive efficient matrix inversion algorithms for such matrices. In particular, we derive the following: (1) a recursive algorithm to invert a full matrix whose inverse is structured as a block tridiagonal matrix; (2) a recursive algorithm to compute the inverse of a structured block tridiagonal matrix. These algorithms are exact. They reduce the computational complexity respectively by two and one orders of magnitude over the direct inversion of the associated matrices. We apply these algorithms to develop a computationally efficient approximate implementation of the Kalman-Bucy filter (KBf) that we refer to as the local KBf. The computational effort of the local KBf is reduced by a factor of I/sup 2/ over the exact KBf while exhibiting near-optimal performance.
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Matrices with banded inverses: inversion algorithms and factorization of Gauss-Markov processes
IEEE Transactions on Information Theory, 2000Co-Authors: A. Kavcic, J.m.f. MouraAbstract:The paper considers the inversion of full matrices whose inverses are L-banded. We derive a nested inversion algorithm for such matrices. Applied to a tridiagonal matrix, the algorithm provides its explicit inverse as an element-wise product (Hadamard product) of three matrices. When related to Gauss-Markov random processes (GMrp), this result provides a closed-form factored expression for the covariance matrix of a first-order GMrp. This factored form leads to the interpretation of a first-order GMrp as the product of three independent processes: a forward independent-increments process, a backward independent-increments process, and a variance-stationary process. We explore the nonuniqueness of the factorization and design it so that the forward and backward factor processes have minimum energy. We then consider the issue of approximating general nonstationary Gaussian processes by Gauss-Markov processes under two optimality criteria: the Kullback-Leibler distance and maximum entropy. The problem reduces to approximating general covariances by covariance matrices whose inverses are banded. Our inversion result is an efficient algorithmic solution to this problem. We evaluate the information loss between the original process and its Gauss-Markov approximation.
G. A. Gravvanis - One of the best experts on this subject based on the ideXlab platform.
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Explicit approximate inverse preconditioning techniques
Archives of Computational Methods in Engineering, 2002Co-Authors: G. A. GravvanisAbstract:The numerical treatment and the production of related software for solving large sparse linear systems of algebraic equations, derived mainly from the discretization of partial differential equation, by preconditioning techniques has attracted the attention of many researchers. In this paper we give an overview of explicit approximate inverse matrix techniques for computing explicitly various families of approximate inverses based on Choleski and LU—type approximate factorization procedures for solving sparse linear systems, which are derived from the finite difference, finite element and the domain decomposition discretization of elliptic and parabolic partial differential equations. Composite iterative schemes, using inner-outer schemes in conjunction with Picard and Newton method, based on approximate inverse matrix techniques for solving non-linear boundary value problems, are presented. Additionally, isomorphic iterative methods are introduced for the efficient solution of non-linear systems. Explicit preconditioned conjugate gradient—type schemes in conjunction with approximate inverse matrix techniques are presented for the efficient solution of linear and non-linear system of algebraic equations. Theoretical estimates on the rate of convergence and computational complexity of the explicit preconditioned conjugate gradient method are also presented. Applications of the proposed methods on characteristic linear and non-linear problems are discussed and numerical results are given.
