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NONLINEAR GALERKIN METHOD AND CRANK-NICOLSONMETHOD FOR VISCOUS INCOMPRESSIBLE FLOW

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Journal of Computational Mathematics 1999年第2期17卷 139-158页

作者： Yin-nian He Dong-sheng Li Kai-Tai Li(College of Science, Xi’an Jiaotong university, Xi’an 710019, china) 西安交通大学基础科学部陕西西安

In this article we discuss a new full discrete scheme for the numerical solution of the Navier-Stokes equations modeling viscous incompressible flow. This scheme consists of nonlinear Galerkin method using mixed finite elements and Crank-Nicolson method. Next, we provide the second-order convergence accuracy of numerical solution corresponding to this scheme. Compared with the usual Galerkin scheme, this scheme can save a large amount of computational time under the same convergence accuracy. (Author abstract) 8 Refs.

关键词： nonlinear Galerkin method Crank-Nicolson method viscous incompressible flow

ONE-SIDED N-WIDTHS OF SOME CLASSES OF PERIODIC FUNCTIONS

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Analysis in Theory and Applications 1993年第4期9卷 21-36页

作者： Fang Gensun Zhang Jianhua Beijing Normal university,china Department of Mathematics Beijing Normal University Beijing PRC

In this paper,we determine the exact estimation of one-sided n-widths d_n^+(w_q^r(p_r),L_1).q=1,∝, where W_q^r(P_r)is a class of differentiable 2π-periodic functions,and is determined by a differential opera- tor P_... 详细信息

关键词： Differential Operator Periodic Function Implicit Function Theorem Simple Zero Exact Estimation

Improved threshold retracker for satellite altimeter waveform retracking over coastal sea

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Progress in Natural Science:Materials International 2006年第7期16卷 732-738页

作者： GUO Jinyun, HWANG Cheiway, CHANG Xiaotao and LIU Yuting ( Department of Land Information and Surveying Engineering, Xuzhou Normal university, Xuzhou 221116. china Departmenl of Civil Engineering, National Chiao Tung university, Hsinchu 30050, Taiwan, china Institute of Geodesy, china Academy of Surveying and Mapping, Beijing 100039, china) Xuzhou Normal Univ Dept Land Informat & Surveying Engn Xuzhou 221116 Peoples R China Natl Chiao Tung Univ Dept Civil Engn Hsinchu 30050 Taiwan china Acad Surveying & Mapping Inst Geodesy Beijing 100039 Peoples R China

Data quality is a key factor for the application of satellite altimetry to geodesy and oceanography. Accuracy of altimetry is limited in the coastal area because the altimeter waveforms are seriously contaminated by topography and environmental pollution. So waveform retracking is needed to compute the range correction of geophysical data records (GDRs) for better accuracy. In this paper, a new waveform retracker named the improved threshold retracker (ITR) is put forward. The retracker first builds sub-waveforms based on leading edges detected in a waveform, then determines the middle point of each leading edge to compute the retracking range correction, finally calculates the referenced sea surface heights according to the geoid undulation from a local geopotential model and tide heights from an ocean tide model, and compares it with all retracking ranges to determine the best one. As a test, altimeter waveforms of Geosat/GM are retracked around the Taiwan coastal area. The result shows that accuracy of ITR method is two times better than that of theβ-5-pa-rameter function-fitting method and threshold method, and three times better than that of GDRs. ITR can efficiently improve the altimetry accuracy of the coastal sea area.

关键词： satellite altimetry waveform retracking improved threshold retracker sub-waveform.

Effects of Sc content on the mechanical properties of Al-Sc alloys

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Rare Metals 2010年第5期29卷 451-455页

作者： SUN Yingying,SONG Min,and HE Yuehui State Key Laboratory of Powder Metallurgy,Central South university,Changsha 410083,china State Key Laboratory of Powder Metallurgy Central South University Changsha China

The effects of Sc content on the mechanical properties of Al-Sc alloys were investigated. The results show that the strengths of all the tested alloys with 0.1 wt.%, 0.3 wt.%, and 0.4 wt.% Sc additions increase initially with an increase in annealing time, due to the increase in volume fraction and size and the decrease in particle interspacing of Al3Sc particles. After reaching peak values, the strengths of all the tested alloys start to decrease with increasing annealing time due to the coarsening and increase in particle interspacing of At3Sc particles. It has also been shown that the alloy with 0.3 wt.% Sc has a higher strength and a lower elongation than the alloys with 0.1 wt.% and 0.4 wt.% Sc. The increase in strength and the decrease in elongation of the alloy with 0.3 wt.% Sc are due to the smaller particle interspacing of Al3Sc particles, resulting in a strong inhibition of dislocation movement during deformation.

关键词： aluminum alloys scandium mechanical properties microstructure

A new parameterization scheme for sea surface aerodynamic roughness

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Progress in Natural Science:Materials International 2008年第11期18卷 1365-1373页

作者： Yuping Pan~(a,b) Wenyu Sha~c Shouxian Zhu~c Sufang Ge~(a,*) a Nanjing university of Information Science and Technology,Nanjing 210044,china b Air Force Meteorological Center of the Nanjing Military Region,Nanjing 210018,china c Meteorology College,The PLA university of Information Science and Technology,Nanjing 211101,china Nanjing university of Information Science and Technology Nanjing 210044 China Air Force Meteorological Center of the Nanjing Military Region Nanjing 210018 China Meteorology College The PLA University of Information Science and Technology Nanjing 211101 China

The dimensionless roughness length derived from dimensional analysis bears a relation to wave age,and the dimensionless form of roughness length can be expressed with the relation with a significant wave *** on six experiments(HEXMAX,RASEX,BIO steady platform,Lake Ontario data analysis FETCH,CBLAST low wind),we verified that the Charnock parameter,Zch,and dimension- less roughness length,z0/Hs,are dependent on wave age,u*/***,we constructed a new scheme for roughness length,and explored its sensitivity to friction velocity and wave *** the newly developed parameterization scheme(PS07)with COARE (Coupled Ocean-Atmosphere Response Experiment V.3.0)algorithm,we calculated the data from the North Sea Platform experiment in December,1985,and made an attempt to validate the suitability of the PS07 compared to the other three schemes of *** found that the calculated results based on the PS07 are close to the *** also conducted an experiment in which the PS07 was combined with the nested model of waves coupling in datasets of 3 typhoons that occurred at the Zhanjiang *** comparison results between the calculated and observed waves around the Naozhou Island indicate that the new parameterization scheme(PS07)has a good applicability.

关键词： Sea surface roughness Parameterization scheme Significant wave height Wave age COARE algorithm

XPS Study of CeO_2/Al_2O_3 film

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International Journal of Minerals,Metallurgy and Materials 1999年第3期13卷 199-200,204页

作者： Mei Zhang Zhenxiang Liu Kan Xie Xueyan Du Wenchao Li(Metallurgy School, university of Science and Technology Beijing, Beijing 100083, china)(Institute of physics Chinese Academy of Science, Beijing 100080, china) Univ of Science and Technology Beijing Beijing China

The redox capacity of CeO2/Al2O3 thin film which was prepared by sol-gel method has been investigated by X-ray Photoelectron Spectrascopy (XPS). The results showed that the thin film was easier to be reduced and re-oxidized than pure CeO2 powder. The key role played by oxygen vacancies which were created from the interaction between CeO2 and Al,O, was also discussed.

关键词： CeO_2/Al_2O_3 thin film redox interaction XPS

ANALYTICAL SOLUTION FOR AXISYMMETRIC PROBLEM OF THICK LAMINATED CLOSED CANTILEVER SHELIS IN HAMILTON SYSTEM

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Acta Mechanica Solida Sinica 1998年第2期11卷 146-158页

作者： Ding Kewei Tang Limin (Dept.of Engineering Mechanics,Dalian university of Technology,Dalian 116.23,china)Fan Jiarang (Dept.of Civil Engineering,He fei university of Technology,Hefei 230009,china) Dept. of Engineering Mechanics Dalian University of Technology Dalian 116023 China Dept. of Civil Engineering Hefei University of Technology Hefei 230009 China

By giving up any assumptions about displacement models and stress distribution,the mixed state Hamilton equation for the axisymmetric problem of the thick laminated closed cantilever cylindrical shells is *** identical analytical solution is obtained for the thin,moderately thick and thick laminated closed cantilever cylindrical *** equations of elasticity can be satis- fied,and all elastic constants can be taken into account.

关键词： Hamilton canonical equation state equation cantilever cylindrical shell exact analysis

A New Algorithm for Routing in Ad-hoc Network

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wuhan university Journal of Natural Sciences 2003年第S1期8卷 269-278页

作者： Zhang Jian, Kang Li-shanSchool of Computer, wuhan university, wuhan 430072, Hubei, china wuhan university School of Computer Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***)

In this paper, we propose a new algorithm for wireless mobile and ad-hoc network, which establishes dynamic cluster of nodes. The proposed algorithm, namely, the Mobility Sensitive Routing Protocol (MSRP), consists of routing in cluster and routing between clusters. Ad-hoc network can utilize MSRP to reduce information exchange and communication bandwidth, to shorten route acquisition delay, and to accommodate more nodes.

关键词： ad-hoc routing algorithmf cluster MSRP

Equilibrium equations for nonlinear buckling analysis of drill-strings in 3D curved well-bores

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Science china(Technological Sciences) 2009年第3期52卷 590-595页

作者： TAN MeiLan1 & GAN LiFei2 1 Faculty of Science, Jiangsu university, Zhenjiang 212013, china 2 94973 Unit in Hangzhou of Zhejiang Province, Hangzhou 310021, china Faculty of Science Jiangsu University 294973 Unit in Hangzhou of Zhejiang Province

With the development of drilling technology, the oil/gas well has evolved from its early vertical straight form to the inclined, horizontal, plane curved, or even 3D curved well-bore. Understanding of the buck- ling behavior of a drill-string in a well-bore is crucial for the success of a drilling operation. Therefore, equilibrium equations for analyzing the buckling behavior of a drill-string in a 3D curved well-bore are required. Based on Love’s equilibrium equations for a curved and twisted rod in space, a set of equi- librium equations for the nonlinear buckling analysis of a drill-string in a 3D curved well-bore are de- rived by introducing a radial constraint of the well-bore. The proposed formulae can account for the well curvature and tortuosity. Thus, it can be used to analyze the buckling behaviors of a drill-string constrained in a well-bore and subjected to axial compression, torsion at its upper end, and gravity simultaneously. It is worth noting that the existing equations in the literature for a drill-string in a straight and plane curved well-bore with a constant curvature are a special case of the proposed model. Thus, the present model can provide a theoretical basis for the nonlinear buckling analysis of a drill-string constrained in a 3D curved well-bore.

关键词： nonlinear buckling tortuosity constraint equilibrium equations drill-strings 3D curved well-bores