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A blow-up criterion for classical solutions to the compressible Navier-Stokes equations

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science china Mathematics 2010年第3期53卷 671-686页

作者： HUANG XiangDi 1 & XIN ZhouPing 2. 1 department of Mathematics, university of science and technology of china, {2., china 2.department of Mathematics, The Chinese university of Hong Kong, Hong Kong, china department of Mathematics University of Science and Technology of China Hefei China department of Mathematics The Chinese University of Hong Kong Hong Kong China

In this paper, we obtain a blow-up criterion for classical solutions to the 3-D compressible Navier-Stokes equations just in terms of the gradient of the velocity, analogous to the Beal-Kato-Majda criterion for the id... 详细信息

关键词： blow-up classical solutions compressible Navier-Stokes

Analysis on cohesive crack opening displacement considering the strain softening effect

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science china(Physics,Mechanics & Astronomy) 2006年第1期49卷 88-101页

作者： WANG Limin1, XU Shilang2.& ZHAO Xiqiang3 1. Mechanics department, Shandong university of {2., Zibo 2.5049, china 2. Civil Engineering department, Dalian university of {2., Dalian 11602., china 3. Mathematics department, Ocean university of china, Qingdao 2.6071, china Mechanics department Shandong University of Technology Zibo China Civil Engineering department Dalian University of Technology Dalian China Mathematics department Ocean University of China Qingdao China

In order to investigate the crack propagation in quasi-brittle materials like rock, ceramic and concrete, Hillerborg and his co-researchers abstracted the fracture process zone in front of a stress free crack in terms of a “fictitious crack zone”. On the fictitious crack zone, cohesive stresses distribute following a given softening relationship of stress vs. crack opening. Based on the polynomial or power series expression of cohesive crack opening displacement, the relationship of the cohesive stress vs. the crack opening displacement is established using elastic theory and integral equation, and some unknown physics variables are obtained using variation approach. The calculation results gained in this paper are close to the experimentally test ones.

关键词： cohesive crack, softening, dissipation work, variation approach.

Prediction for RNA planar pseudoknots

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Progress in Natural science:Materials International 2007年第6期17卷 717-724页

作者： Li Hengwu1,2. Zhu Daming1, Liu Zhendong1 and Li Hong2.1. School of Computer science and technology, Shandong {2., Jinan 2.0100, china 2. department of Computer, Shandong Economic {2., Jinan 2.0014, china) School of Computer science and technology Shandong University Jinan 250100 China department of Computer Shandong Economic University Jinan 250014 China

Based on m-stems and semi-extensible structure, a model is presented to represent RNA planar pseudoknots, and corresponding dynamic programming algorithm is designed and implemented to predict arbitrary planar pseudoknots and simple non-planar pseudoknots with O(n4) time and O(n3) space. The algorithm folds total 2.5 sequences in the Pseudobase database, and the test results indicate that the algorithm has good accuracy, sensitivity and specificity.

关键词： algorithm RNA secondary structure pseudoknot dynamic programming.

A study of two-dimensional magnetic polaron

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science china(Physics,Mechanics & Astronomy) 2006年第4期49卷 421-429页

作者： LIU Tao1, ZHANG Huaihong1, FENG Mang1,2.& WANG Kelin1,3 1. School of science, Southwest university of science and technology, Mianyang 62.010, china 2. Wuhan Institute of Physics and Mathematics, Chinese Academy of sciences, Wuhan 430070, china 3. department of Modern Physics, university of science and technology of china, hefei 2.002., china School of science Southwest University of Science and Technology Mianyang China Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan China department of Modern Physics University of Science and Technology of China Hefei China

By using the variational method and anneal simulation, we study in this paper the self-trapped magnetic polaron (STMP) in two-dimensional anti-ferromagnetic material and the bound magnetic polaron (BMP) in ferromagnetic material. Schwinger angular momentum theory is applied to changing the problem into a coupling problem of carriers and two types of Bosons. Our calculation shows that there are single-peak and multi-peak structures in the two-dimensional STMP. For the ferromagnetic material, the properties of the two-dimensional BMP are almost the same as that in one-dimensional case; but for the anti-ferromagnetic material, the two-dimensional STMP structure is much richer than the one-dimensional case.

关键词： self-trapped magnetic polaron, bound magnetic polaron, impurity potential, anti-ferromagnet.

Real estate appraisal system based on GIS and BP neural network

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中国有色金属学会会刊：英文版 2011年第S3期21卷 626-630页

作者： LIU Xiao-sheng1, DENG Zhe1, WANG Ting-li2.1. School of Architecture and Survey Engineering, Jiangxi university of science and {2., Ganzhou 341000, china 2. School of Applied science, Jiangxi university of science and {2., Ganzhou 341000, china School of Architecture and Survey Engineering Jiangxi University of Science and Technology Ganzhou 341000 China School of Applied science Jiangxi University of Science and Technology Ganzhou 341000 China

For the inefficiency and inaccuracy of appraisal method of traditional estate appraisal theory, the real estate appraisal system based on GIS and BP neural network was established. The structure of the system was designed which includes appraisal model, trade case, GIS database and query analysis module. With the help of the L-M algorithm in MATLAB software, BP neural network was improved and the trade cases were trained, then the BP neural network which has already been trained was tested. At the same time, the BP neural and GIS were put together to construct the hedonic price estimate model. The C# and ArcGIS9.3 were used to achieve the system in VS2.08. City basic geographic data and real estate related information were used as the basic data in practice. The results show that the functions of querying, adding and editing the spatial data and attribute data are achieved and also the efficiency and accuracy of real estate are improved, so that the new method of real estate is provided by the system.

关键词： BP neural network GIS hedonic price real estate appraisal

Spectrum characteristics and pump wavelengths of Nd_(3+) -doped double-clad fiber

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Chinese science Bulletin 1997年第11期42卷 897-900页

作者： MING Hai, YANG Bao, DONG Xiaopeng, A. Fedotov, Xudong Xiao and M. M. T. Loy1. department of Physics, university of science and technology of china, {2., china 2. department of Physics, university of science and technology of Hong Kong, Hong Kong, china department of Physics University of Science and Technology of China Hefei China department of Physics University of Science and Technology of Hong Kong Hong Kong China

Nd3+ -doped double-clad fiber is a new type of fiber that has large *** large receivingarea compared with single-clad rare-earth-doped *** Nd3+-doped double-clad fiberpumped directly by laser-diode arrays can be manufactured into high-power fiber lasers,high-power superfluorescence sources and high-gain fiber amplifiers,and they will be applied

关键词： double-clad fiber optimum pump wavelength optical spectrum.

Effect of Preparation Methods on Mechanical Properties of PVA/HA Composite Hydrogel

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Journal of Bionic Engineering 2010年第3期7卷 235-243页

作者： Dekun Zhang~1, Junjie Duan~1, Dagang Wang~2. Shirong Ge~2.1. School of Materials science and Engineering, china {2. of Mining and technology Xuzhou 2.1116, P. R. china 2. School of Mechanical and Electrical Engineering, china {2. of Mining and technology, Xuzhou 2.1116, P. R. china School of Materials science and Engineering China University of Mining and Technology Xuzhou P. R. China School of Mechanical and Electrical Engineering China University of Mining and Technology Xuzhou P. R. China

Poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogel specimens were prepared with 15% PVA and 1%,2., 3%, 4% and 5% HA by repeated freezing-thawing. The tests of static and dynamic mechanical properties were carried out todiscuss the influence of different contents of HA and freezing-thawing cycles on the mechanical properties of PVA/HA compositehydrogel. The results of static mechanical tests showed that the PVA/HA composite hydrogel with 3% HA and ninefreezing-thawing cycles had excellent stress relaxation properties, higher relaxation ratio, lower stress equilibrium value andpresented better properties of creep and recovery. The results of dynamic mechanical test showed that the PVA/HA compositehydrogel with nine freezing-thawing cycles had higher storage modulus and loss modulus, so was the PVA/HA compositehydrogel with 3% HA.

关键词： composite hydrogel HA contents freezing-thawing cycles static properties dynamic properties

A complex variable meshless method for fracture problems

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science china(Physics,Mechanics & Astronomy) 2006年第1期49卷 46-59页

作者： CHENG Yumin1 & LI Jiuhong2.1. Shanghai Institute of Applied Mathematics and Mechanics, Shanghai university, Shanghai 2.0072. china 2. {2. of Building Engineering, Xi’an university of technology, Xi’an 710048, china Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai China department of Building Engineering Xi’an University of Technology Xi’an China

Based on the moving least-square (MLS) approximation, the complex variable moving least-square approximation (CVMLS) is discussed in this paper. The complex variable moving least-square approximation cannot form ill-conditioned equations, and has greater precision and computational efficiency. Using the analytical solution near the tip of a crack, the trial functions in the complex variable moving least-square approxi- mation are extended, and the corresponding approximation function is obtained. And from the minimum potential energy principle, a complex variable meshless method for fracture problems is presented, and the formulae of the complex variable meshless method are obtained. The complex variable meshless method in this paper has greater precision and computational efficiency than the conventional meshless method. Some examples are given.

关键词： moving least-square approximation, complex variable moving least-square approximation, meshless method, complex variable meshless method, fracture.

Effects of NaNbO_3-Co_2._3 Co-additive on the Properties of PZN-PZT Ceramics

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Journal of Wuhan university of technology(Materials {2.) 2007年第4期22卷 722-724页

作者：邓毅华 College of Material science and Engineering South China University of Technology department of Electronic science and {2. Huazhong University of Science and TechnologyWuhan 430074China

NaNbO3-Co2.3 co-added PZN-PZT （PZCNNT） ceramics were prepared using conventional solid state reaction. The piezoelectric and dielectric properties were measured. The experimental results show that the addition of 0.3mo1% Co2.3 leads to low dielectric loss （tgδ） in PZCNNT ceramics and the proper addition of NaNbO3 not only improves piezoelectric properties but also decreases intensively dielectric loss and mechanical loss. The optimal ceramic having d33=310 pC/N, kp=0.59, εr=985, tgδ=0.0034, Qm=1380 was obtained.

关键词： PZN-PZT piezoelectric constant dielectric constant dielectric loss