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LEVEL SET METHOD FOR TOPOLOGICAL OPTIMIZATION APPLYING TO STRUCTURE, MECHANISM AND MATERIAL DESIGNS

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Chinese Journal of Mechanical Engineering 2004年第2期17卷 200-209页

作者： Mei Yulin Wang Xiaoming Department of Mechanical Engineering,Dalian university of Technology,Dalian 116024,china Department of Mechanical Engineering Dalian University of Technology Dalian 116024 China

Based on a level set model, a topology optimization method has been suggestedrecently. It uses a level set to express the moving structural boundary, which can flexibly handlecomplex topological changes. By combining vector level set models with gradient projectiontechnology, the level set method for topological optimization is extended to a topologicaloptimization problem with multi-constraints, multi-materials and multi-load cases. Meanwhile, anappropriate nonlinear speed, mapping is established in the tangential space of the activeconstraints for a fast convergence. Then the method is applied to structure designs, mechanism andmaterial designs by a number of benchmark examples. Finally, in order to further improvecomputational efficiency and overcome the difficulty that the level set method cannot generate newmaterial interfaces during the optimization process, the topological derivative analysis isincorporated into the level set method for topological optimization, and a topological derivativeand level set algorithm for topological optimization is proposed.

关键词： Level set method Topology optimization Mean curvature flow Materialdesign Mechanism design Topological derivative

Effect of Grinding and Polishing on the Residual Stress and Bending Strength of a Silicon Nitride Ceramic

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Journal of wuhan university of Technology(Materials Science) 2005年第1期20卷 46-48页

作者：高玲 State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

The residual stresses on the surface of the d ifferently ground and polished silicon nitride ceramics were measured using X-r ay diffraction and identified by *** effect of the residual stress on the be nding strength was *** investigations show that the grinding proces s can introduce subatantial tensile residual stresses up to 290MPa on the surfac e of silicon nitride ceramics,which has a significant effect on reducing the ben ding strength of the ceramics after ***,in comparison with the ceramic s with a rough surface,the ceramics with a mirror image surface may have a lower *** can smooth the residual *** we evaluate the qualit y of the ceramic components after grinding,we must take residual stress into con sideration. The grinding methods and grinding conditions must be carefully selec ted in order to get the favorite residual stress as well as the surface smoothne ss.

关键词： residual stress grinding bending strengt h ceramics

UNIFORM　CONVERGENCY　FOR　WEIGHTED　PERIODOGRAM　OF　STATIONARY　LINEAR　RANDOM　FIELDS

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Chinese Annals of Mathematics,Series B 1995年第3期16卷 331-340页

作者： HE SHUYUAN(Department of Probability and Statistics, Beijing university, Beijing 100871, china.) BEIJING UNIV DEPT PROBABIL & STATBEIJING 100871PEOPLES R CHINA

Let {Xn; n ∈ N2} be a two dimensionally indexed linear stationary random field generated by a 1/4 martingale difference white noise. The logarithm uniform convergency resulte for the weighted periodogram of is proved.

关键词： Periodogram Random field Martingale difference Log-convergency.

IR STUDY ON MONOMOLECULAR PARTICLE AGGLOMERATES OF POLYSTYRENE OBTAINED BY FREEZE-DRYING OF ITS DILUTE SOLUTION

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Chinese Journal of Polymer Science 2002年第4期20卷 381-383页

作者： Song Wang Qing-hua Wang Rong-shi Cheng Research Center of Materials Beijing Institute of Technology Beijing 100081, china Department of Chemistry Nanjing university Nanjing 210093. china Nanjing Univ Dept Chem Nanjing 210093 Peoples R China Beijing Inst Technol Ctr Mat Res Beijing 100081 Peoples R China

The monomolecular particle agglomerates of polystyrenes were obtained by freeze-drying of its very dilute solutions of 1.3.x 10(-5)-2.0 x 10(-5) g/mL in benzene:cylcohexane (100:1) solvents, and they were annealed at room temperature for hundred days before use. According to C-13.NMR measurement the polystyrenes should be practically atactic. The number average molecular weights of the samples are 2.80 x 10(3., 2.00 x 10(4), and 1.55 x 10(6), respectively. The freeze-dried aPS with a molecular weight higher than 10(4) show two new IR absorption bands at 1098 and 1261 cm(-1), which are absent in the normal aPS and freeze-dried styrene oligomer. It was also found that the low molecular weight samples can only form powders, whereas the freeze-dried aPS with higher molecular weight form a mixture of powders and fibrils, of which the longer fibrils show a much stronger 1261 cm(-1) band than the shorter fibrils and the powder. It seems that the 1261 cm(-1) band corresponds to the stacking behavior of monomolecular particles.

关键词： monomolecular particles atactic polystyrene FTIR spectroscopy

On the Multiplier Conjecture

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Acta Mathematica Sinica,English Series 1994年第1期10卷 49-58页

作者： Qiu Weisheng Department of Mathematics Peking university Beijing,100871 china 1. Department of Mathematics Peking University 100871 Beijing China

The Multiplier Theorem is a celebrated theorem in the Design *** condition p>λis crucial to all known proofs of the multiplier *** in all known examples of difference sets μp is a multiplier for every prime p with（p,v）=1 and *** there is the multiplier conjecture:"The multiplier theorem holds without the assumption that p> λ."The general form of the multiplier theorem may be viewed as an attempt to partially resolve the multiplier conjecture,where the assumption"p>λ"is replaced by "n1>λ".Since then Newman（1963.,Turyn（1964）,and McFarland（1970）attempted to partially resolve the multiplier conjecture（see[7],[8],[9]）.This paper will prove the following result using the representation theory of finite groups and the algebraic number theory:Let G be an abelian group of order v,v0 be the exponent of G,and D be a（v, k,λ）-difference set in *** n=2n1, then the general form of the multiplier theorem holds without the assumption that n1>λin any of the following cases: （1）2|n1; （2）2 ×n1,and（v,7）=1; （3. 2 ×n1,7|v,and t≡1 or 2 or 4（mod 7）.

关键词： On the Multiplier Conjecture Math

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光伏充电控制器温度补偿的研究

太阳能学报 2004年第1期25卷 92-94页

作者：崔岩李大勇胡宏勋哈尔滨理工大学上海交通大学上海200030

对具有温度补偿功能的光伏系统充电控制器的设计与应用进行研究。利用半导体温度传感器对蓄电池过充点保护电压自动温度补偿的方法,实现了充电控制器在充电过程中的自动温度补偿功能,从而提高了光伏系统的可靠性以及延长了蓄电池的使用... 详细信息

对具有温度补偿功能的光伏系统充电控制器的设计与应用进行研究。利用半导体温度传感器对蓄电池过充点保护电压自动温度补偿的方法,实现了充电控制器在充电过程中的自动温度补偿功能,从而提高了光伏系统的可靠性以及延长了蓄电池的使用寿命。该研究成果具有实际推广应用价值。

关键词：温度补偿充电控制器

Existence and Uniqueness of Positive Solutions to Sublinear-Linear Initial Value Problems

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Acta Mathematica Sinica,English Series 1994年第1期10卷 19-29页

作者： Yang Enhao Department of Mathematics Jinan university Guangzhou,510275 china 1. Department of Mathematics Jinan University 510275 Guangzhou China

Existence and uniqueness conditions for nonnegative solutions to initial value prob- lems of general sublinear-linear differential equations are *** extend the uniqueness theorem due to ***~[6] and the main results of... 详细信息

关键词： Existence and Uniqueness of Positive Solutions to Sublinear-Linear Initial Value Problems Math

Estimation for nearly unit root processes with GARCH errors

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Applied Mathematics(A Journal of Chinese Universities) 2010年第3期25卷 297-306页

作者： YUAN Yu-ze ZHANG Rong-mao Department of Mathematics, Zhejiang university, Hangzhou 3.0027, china Department of Mathematics Zhejiang University Hangzhou China

In this paper the limiting distribution of the least square estimate for the autoregressive coefficient of a nearly unit root model with GARCH errors is derived. Since the limiting distribution depends on the unknown variance of the errors, an empirical likelihood ratio statistic is proposed from which confidence intervals can be constructed for the nearly unit root model without knowing the variance. To gain an intuitive sense for the empirical likelihood ratio, a small simulation for the asymptotic distribution is given.

关键词： Nearly unit root GARCH error least square estimation Ornstein-Uhlenbeck process empirical likelihood.

Study on Decision Support System of Agricultural Sustainable Development of Jianli County in Jianghan Plain

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wuhan university Journal of Natural Sciences 2000年第3期5卷 334-338页

作者： Wang Xue\|lei, Liu Gong\|hu Institute of Geodesy and Geophysics, Chinese Academy of Sciences, wuhan 43.077 , china Chinese Academy of Sciences Institute of Geodesy and Geophysics Wuhan China (GRID:grid.9227.e) (ISNI:***)

With the agricultural development and the modernization of decision-making, it is necessary to establish the agricultural sustainable development decision support system supported by GIS. We set Jianli county as an example; our aim is to realize decision spatialiazation with the support of information system, remote sensing and artificial intelligence. The system components are described in the aspects of database, knowledge base, model-base and method-base. This system will provide a workable system for local decision-makers and agricultural management sections.

关键词： Key words agricultural sustainable development decision support system system function