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A new trust region algorithm for image restoration

Science china Mathematics 2005年第2期48卷 169-184页

作者： WEN Zaiwen & WANG Yanfei State Key laboratory of Scientific Engineering Computing, institute of Computational Mathematics and Scientific/Engineering Computing, academy of Mathematics and System sciences, chinese academy of sciences, beijing 100080, china national Key laboratory on Remote Sensing Science, institute of Remote Sensing Applications, chinese academy of sciences, beijing 100101, china 1. State Key laboratory of Scientific Engineering Computing Institute of Computational Mathematics and Scientific/Engineering Computing Academy of Mathematics and System Sciences Chinese Academy of Sciences 100080 Beijing China 2. national Key laboratory on Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences 100101 Beijing China

The image restoration problems play an important role in remote sensing and astronomical image analysis. One common method for the recovery of a true image from corrupted or blurred image is the least squares error (LSE) method. But the LSE method is unstable in practical applications. A popular way to overcome instability is the Tikhonov regularization. However, difficulties will encounter when adjusting the so-called regularization parameter a. Moreover, how to truncate the iteration at appropriate steps is also challenging. In this paper we use the trust region method to deal with the image restoration problem, meanwhile, the trust region subproblem is solved by the truncated Lanczos method and the preconditioned truncated Lanczos method. We also develop a fast algorithm for evaluating the Kronecker matrix-vector product when the matrix is banded. The trust region method is very stable and robust, and it has the nice property of updating the trust region automatically. This releases us from tedious finding the regularization parameters and truncation levels. Some numerical tests on remotely sensed images are given to show that the trust region method is promising.

关键词： trust region algorithm, image restoration, Lanczos method, Kronecker matrix-vector product, preconditioning.

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Mass Spectrometric Evidence of Heparin Disaccharides for the Catalytic Characterization of A Novel Endolytic Heparinase

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Acta Biochimica et Biophysica Sinica 2004年第12期36卷 840-844页

作者： Yapeng CHAO1,3, Shaoxiang XIONG2, Xiulan CHENG1, and Shijun QIAN1* 1institute of microbiology, chinese academy of sciences, beijing 100080, china 2Center of Mass Spectrometry, institute of Chemistry, chinese academy of sciences, beijing 100080, china 3Graduate School of the chinese academy of sciences, beijing 100039, china institute of microbiology Chinese Academy of SciencesBeijing 100080 China Graduate School of the chinese academy of sciencesbeijing 100039 China Center of Mass Spectrometry Institute of Chemistry Chinese Academy of SciencesBeijing 100080 China

Heparinase from different sources can eliminate heparin or/and heparan sulfate into various low-molecular weight heparins with different characteristics. Porcine intestinal mucosa heparin was de- graded into a series of oligosaccharides by a novel heparinase from the species Sphingobacterium. Disaccha- ride components from the digests were separated and purified by ultrafiltration and HPLC. Five major peaks appeared as three types according to their retention time. The mass spectrometry of peak I mainly gave the non-sulfated disaccharide with the mass of 379 Da. Peak II and III were indicated as two major monosulfated disaccharides with molecular mass of 417 and 459 Da respectively. Moreover, the peak III represented an N- acetyl disaccharide. Both peak IV and V showed the same mass of 496 Da, hinting that they were disulfate- substituted disaccharides. No trisulfate-substituted disaccharides were detected in the mixture of the heparin digest though they were abundant in the heparin structure. The results revealed that the heparinase might specifically cut the sites with low sulfated domain in heparin.

关键词： electrospray ionization-mass spectrometry heparin disaccharides heparinase high perfor- mance liquid chromatography Sphingobacterium sp.

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The gravity wave instability induced by photochemistry in summer polar mesopause region

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chinese Science Bulletin 2000年第3期45卷 267-272页

作者： Center for Space Science and Applied Research, chinese academy of sciences, beijing 100080, china laboratory of Numeric Study of Heliospheric Physics, chinese academy of sciences, beijing 100080, china Center for Space Science and Applied Research Chinese Academy of Sciences Beijing China laboratory of Numeric Study of Heliospheric Physics Chinese Academy of Sciences Beijing China

The effect of diabatic process due to the photochemical heating and cooling on the gravity wave propagation in middle atmosphere is studied. A linear gravity wave model which considers the diabatic process is established. The unstable region and the growth rate of the gravity wave caused by photochemistry are calculated. And the comparison between the model and the adiabatic gravity wave theory of pure dynamics is made. The results indicate that the photochemical heating process can induce the instability of gravity wave at mesopause. The intensity of the instability becomes stronger as the temperature decreases. The temperature feature and the altitude characteristics of the instability are consistent with the observation. Therefore, the instability of the gravity wave induced by photochemistry may be an important mechanism in polar mesopause region in summer.

关键词： photochemistry instability gravity wave growth rate.

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On the contact width in generalized plain strain JKR model for isotropic solids

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Acta Mechanica Sinica 2009年第4期25卷 491-497页

作者： Cong Yan Shaohua Chen LNM, institute of mechanics, chinese academy of sciences,100190 beijing. china LNM Institute of Mechanics Chinese Academy of Sciences 100190 Beijing China

Adhesive contact model between an elastic cylinder and an elastic half space is studied in the present paper, in which an external pulling force is acted on the above cylinder with an arbitrary direction and the contact width is assumed to be asymmetric with respect to the structure. Solutions to the asymmetric model are obtained and the effect of the asymmetric contact width on the whole pulling process is mainly discussed. It is found that the smaller the absolute value of Dundurs＇ parameter 13 or the larger the pulling angle O, the more reasonable the symmetric model would be to approximate the asymmetric one.

关键词： Contact mechanics Generalized JKRmodel Asymmetric contact width Oscillatory solution Non-oscillatory solution

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Competitive Adsorption between Bovine Serum Albumin and Collagen Observed by Atomic Force microscope

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chinese Chemical Letters 2004年第12期15卷 1465-1468页

作者： Yong YU Pei Qing YING Gang JIN national microgravity Lab,institute of mechanics,chinese academy of sciences, beijing 100080 national microgravity Lab Institute of MechanicsChinese Academy of SciencesBeijing 100080

Atomic force microscopy (AFM) was used to study the competitive adsorption betweenbovine serum albumin (BSA) and type Ⅰ collagen on hydrophilic and hydrophobic silicon wafers.BSA showed a grain shape and the type Ⅰ collagen displayed fibril-like molecules with relativelyhomogeneous height and width, characterized with clear twisting (helical formation). These AFMimages illustrated that quite a lot of type Ⅰ collagen appeared in the adsorption layer on hydrophilicsurface in a competitive adsorption state, but the adsorption of BSA was more preponderant than thatof type Ⅰ collagen on hydrophobic silicon wafer surface. The experiments showed that theinfluence of BSA on type Ⅰ collagen adsorption on hydrophilic surface was less than that onhydrophobic surface.

关键词： Atomic force microscope protein competitive adsorption collagen bovine serum albumin.

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Effects of fundamental structure parameters on dynamic responses of submerged floating tunnel under hydrodynamic loads

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Acta Mechanica Sinica 2009年第3期25卷 335-344页

作者： Xu Long Fei Ge Lei Wang Youshi Hong State Key laboratory of Nonlinear mechanics, institute of mechanics, chinese academy of sciences, beijing 100190, china State Key laboratory of Nonlinear mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

This paper investigates the effects of structure parameters on dynamic responses of submerged floating tunnel （SFT） under hydrodynamic loads. The structure parameters includes buoyancy-weight ratio （BWR）, stiffness coefficients of the cable systems, tunnel net buoyancy and tunnel length. First, the importance of structural damp in relation to the dynamic responses of SPT is demonstrated and the mechanism of structural damp effect is discussed. Thereafter, the fundamental structure parameters are investigated through the analysis of SFT dynamic responses under hydrodynamic loads. The results indicate that the BWR of SFT is a key structure parameter. When BWR is 1.2, there is a remarkable trend change in the vertical dynamic response of SFT under hydrodynamic loads. The results also indicate that the ratio of the tunnel net buoyancy to the cable stiffness coefficient is not a characteristic factor affecting the dynamic responses of SFT under hydrodynamic loads.

关键词： Submerged floating tunnel Structural dampBuoyancy-weight ratio Cable stiffness coefficient ,Tunnel net buoyancy - Hydrodynamic load

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A CLASS OF NEW PARALLEL HYBRID ALGEBRAIC MULTILEVEL ITERATIONS

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Journal of Computational Mathematics 2001年第6期19卷 651-672页

作者： Zhong-zhi Bai (LSEC ICMSEC, academy of Mathematics and Systems sciences, chinese academy of sciences, beijing 100080, china) 中科院计算数学与科学工程计算所北京 100080

Presents preconditioning matrices having parallel computing function for the coefficient matrix and a class of parallel hybrid algebraic multilevel iteration methods for solving linear equations. Solution to elliptic ... 详细信息

关键词： elliptic boundary value problem system of linear equations symmetric positive definite matrix multilevel iteration parallel method

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THE DUAL MIXED METHOD FOR AN UNILATERAL PROBLEM

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Journal of Computational Mathematics 2003年第6期21卷 733-746页

作者： Lie-heng Wang(LSEC, ICMSEC, academy of Mathematics and System sciences, chinese academy of sciences,beijing 100080, china) LSEC ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China

In this paper, the dual mixed method for an unilateral problem, which is the simplified modelling of scalar function for the friction-free contact problem, is considered. The dual mixed problem is introduced, the existence and uniqeness of the solution of the problem are presented, and error bounds O(h3/4) and O(h3/2) are obtained for the dual mixed finite element approximations of Raviart-Thomas elements for k = 0 and k = 1 respectively.

关键词： Dual Mixed Method Unilateral Problem.

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Ambient noise near the sea-route

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Science china(Physics,mechanics & Astronomy) 2009年第1期52卷 40-45页

作者： HE Li1,2, LI ZhengLin1,3 & PENG ZhaoHui1 1 national laboratory of Acoustics, institute of Acoustics, chinese academy of sciences, beijing 100190, china 2 institute of Geology and Geophysics, chinese academy of sciences, beijing 100029, china 3 NanHai laboratory of Acoustics, institute of Acoustics, chinese academy of sciences, Haikou 570206, china national laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Beijing 100190 China institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China NanHai laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Haikou 570206 China

Ambient noise data measured in an experiment conducted in shallow water near a sea-route were analyzed. It was observed that, at low frequency, the horizontal correlation has an obvious difference from that predicted by the classical ambient noise model. The theoretical analyses show that this phenomenon is caused by wind noise together with the discrete shipping noise nearby. An ambient noise model was proposed to include the effects caused by both the noise sources. Data measured at different times verify that the proposed model can be used to forecast the ambient noise field in shallow water near the sea-route.

关键词： ambient noise model horizontal correlation discrete ships

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MATHEMATICAL ANALYSIS FOR QUADRILATERAL ROTATED Q_1 ELEMENT Ⅲ: THE EFFECT OF NUMERICAL INTEGRATION

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Journal of Computational Mathematics 2003年第3期21卷 287-294页

作者： Ping-bing Ming Zhong-ci Shi (institute of Computational Mathematics, chinese academy of sciences, beijing 100080, china) institute of Computational Mathematics Chinese Academy of Sciences 北京 100080

This is the third part of the paper for the rotated Q1 nonconforming element on quadrilateral meshes for general second order elliptic problems. Some optimal numerical formulas are presented and analyzed. The novelty is that it includes a formula with only two sampling points which excludes even a Q1 unisolvent set. It is the optimal numerical integration formula over a quadrilateral mesh with least sampling points up to now.

关键词： Quadrilateral rotated Q1 element Numerical quadrature.

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