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ASYMPTOTIC ERROR EXPANSION AND DEFECT CORRECTION FOR SOBOLEV AND VISCOELASTICITY TYPE EQUATIONS

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Journal of Computational Mathematics 1998年第1期16卷 51-62页

作者： Qun Lin Shu-hua Zhang Ning-ning Yan(institute of systems science, chinese academy of sciences, beijing, china) 中科院系统科学所北京

In this paper we study the higher accuracy methods - the extrapolation and defect correction for the semidiscrete Galerkin approximations to the solutions of Sobolev and viscoelasticity type equations. The global extrapolation and the correction approximations of third order, rather than the pointwise extrapolation results are presented.

关键词： asymptotic error semidiscrete Galerkin approximation global extrapolation higher accuracy

Some results about holomorphic vector bundles over general Hopf manifolds

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science china Mathematics 2009年第12期52卷 2863-2866页

作者： ZHOU XiangYu institute of Mathematics,academy of Mathematics and systems science,and Hua Loo-Keng Key Laboratory of Mathematics,chinese academy of sciences,beijing 100190,china 1. institute of Mathematics Academy of Mathematics and Systems Science and Hua Loo-Keng Key Laboratory of Mathematics Chinese Academy of Sciences Beijing 100190 China

In the present note that grew out of my talk given at the conference in honor of Prof. Zhong Tongde,I give a survey of some recent results about holomorphic vector bundles over general Hopf manifolds.

关键词： holomorphic vector bundles Hopf manifolds cohomology groups 32L10 32L05 32J18

Admissibilities of linear estimator in a class of linear models with a multivariate t error variable

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science china Mathematics 2010年第8期53卷 2011-2019页

作者： YANG GuoQing 1 & WU QiGuang 2 1 Department of Mathematics,Tongji University,Shanghai 200092,china 2 institute of systems science,academy of Mathematics and systems science,chinese academy of sciences,beijing 100190,china 1. Department of Mathematics Tongji University Shanghai 200092 China2. Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

This paper discusses admissibilities of estimators in a class of linear models,which include the following common models:the univariate and multivariate linear models,the growth curve model,the extended growth curve model,the seemingly unrelated regression equations,the variance components model,and so *** is proved that admissible estimators of functions of the regression coefficient β in the class of linear models with multivariate t error terms,called as Model II,are also ones in the case that error terms have multivariate normal distribution under a strictly convex loss function or a matrix loss *** is also proved under Model II that the usual estimators of β are admissible for p 2 with a quadratic loss function,and are admissible for any p with a matrix loss function,where p is the dimension of β.

关键词： multivariate t distribution convex loss quadratic loss matrix loss admissible estimator

Interface delamination of the thermal barrier coating subjected to local heating

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science china(Technological sciences) 2010年第12期53卷 3168-3174页

作者： WU ChenWu, HUANG ChenGuang & CHEN GuangNan institute of Mechanics, chinese academy of sciences, beijing 100190, china 1. institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

To investigate the possible failure modes of the thermal barrier coating (TBC) used to protect the scramjet combustion chamber, the local heating via laser beam irradiation was utilized to simulate the service condition of high thermal flux and high temperature gradient. Firstly, the experimental method and process were described and the typical fracture morphology of the TBC under test were provided. Then, the theoretical and finite element modeling were carried out to study the temperature, deformation and stresses of the specimen when the top ceramic coat was subjected to local heating, and to demonstrate the mechanism on the failure of the TBC. It is revealed that the interface delamination shall appear and ultimately lead to the failure of the TBC under such thermal loading of local quick heating. According to the outcome of this study, the driving force of the interface delamination is influenced greatly by the key structural parameters and performance matching. Moreover, by utilizing the rules of the effects of these parameters on the fracture driving force, there is some possibility for the designer to optimize the performances of the TBC.

关键词： TBC local heating interface delamination FE modeling

Existence of SURU estimators in SURE model with special covariance structures

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chinese science Bulletin 1997年第14期42卷 1149-1151页

作者： WU Qiguanginstitute of systems science, chinese academy of sciences, beijing 100080, china institute of systems science Chinese Academy of Sciences Beijing China

THROUGHOUT this note, the following notations are used: For a matrix A, A>0 means thatA is positive definite symmetric; R （A）, A′and A- stand for the column space, transposeand any g-inverse of A respectively; PA = A （A′A）- A′and PA = Ik - PA, where Ik is theidentity matrix of order k that is the number of rows in A. Rm×n is the totality of m×n realmatrices.

关键词： seemingly unrelated regression equations (SURE) model uniformly minimum risk unbiased (UMRU) estimator uniform covariance structure serial covariance structure.

Tree-decompositions of graphs ( I )

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chinese science Bulletin 1997年第4期42卷 277-281页

作者： SHI Minyonginstitute of systems science, chinese academy of sciences beijing 100080, china institute of systems science Chinese Academy of Sciences Beijing China

IN this note all graphs are undirected, finite and simple. For a subgraph H of G, V(H), E(H), ε(H) and μ(H) denote the set of vertices, the set of edges, the number of edges in H and the number of cycles in H respectively. H[X] denotes the subgraph of H induced by X. Given two disjoint subsets X and Y of V(G), we write E_G(X, Y)={xy∈E(G)

关键词： tree-decomposition singular vertex maximal planar bipartite graph.

A simple proof of the formal duality of the Kerdock and Preparata codes

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chinese science Bulletin 2000年第14期45卷 1279-1282页

作者： WAN Zhexianinstitute of systems science, chinese academy of sciences, beijing 100080, china institute of systems science Chinese Academy of Sciences Beijing China

The nonlinearity of the Z2-Kerdock code Km+1, where m is an odd integer ≥3, is not at all obvious. By regarding Km+1 as the binary image of the Z4-Kerdock code .,K(m) under the Gray map[1], a simple proof can be achieved (cf. Theorems 8.7 and 8.9 of [2]). Similarly, the formal duality of the Z2-Kerdock code Km+1 and the Z2-Preparata code Pm+1 is even more not at all obvious. A simple proof is given in the present note, by regarding Km+1 as the binary image of .K (m) and using the duality of .K(m) and the Z4-Preparata code . (m) established in [1].

关键词： 4-code. Kerdock code Preparata code formal duality.

A note on noncommutative moment problems

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science china Mathematics 2005年第8期48卷 1144-1151页

作者： MA Xiujuan School of sciences, Hebei University of Technology, Tianjin 300130, china Mathematics institute, academy of Mathematics and systems science, chinese academy of sciences, beijing 100080, china 1. School of sciences Hebei University of Technology 300130 Tianjin China 2. Mathematics institute Academy of Mathematics and Systems Science Chinese Academy of Sciences 100080 Beijing China

Noncommutative moment problems for C*-algebras are studied. We generalize a result of Hadwin on tracial states to nontracial case. Our results are applied to obtain simple solutions to moment problems on the square and the circle as well as extend the positive unital functionals from a (discrete) complex group algebra to states on the group C*-algebra.

关键词： moment, free product, state, group C*-algebra.

Anti-saturation block adaptive quantization algorithm for SAR raw data compression over the whole set of saturation degrees

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Progress in Natural science:Materials International 2009年第8期19卷 1003-1009页

作者： Haiming Qi , Weidong Yu institute of Electronics, chinese academy of sciences, beijing 100190, china [a]institute of Electronics Chinese Academy of Sciences Beijing 100190 China

In order to improve the performance of block adaptive quantization (BAQ) when the output of the analog to digital converter (ADC) is saturated, this paper proposes an anti-saturation BAQ algorithm. First, the concept of the standard deviation of the output signal (SDOS) of the ADC is proposed. Also, unlike traditional normalization processing, SDOS is used and the mapping between SDOS and the average signal magnitude is deduced. Second, the saturation term is introduced to the Lloyd–Max quantizer and an optimal non-uniform scalar quantizer for saturated SAR raw data quantization is proposed. After this, the implementation scheme for the proposed algorithm using an FPGA is analyzed in detail. Third, the relationships among the saturation degree of the signal, the peak-topeak value of the ADC, standard deviation of the input and output signal of the ADC and the average signal magnitude are deduced. Based on these relationships, a power compensation decoder is designed for encoding. Numerical experiment results based on ERS-1 and the simulated data show that the performance of the proposed algorithm is better than that of BAQ.

关键词： Synthetic aperture radar (SAR) Raw data compression Block adaptive quantization (BAQ) Anti-saturation