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RESEARCH ON DESIGN METHOD OF A MULTIPLE DISC WET BRAKE IN LUBRICATED ENVIRONMENT

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Chinese Journal of Mechanical Engineering 2003年第4期16卷 391-395页

作者： Qin datong Sun DongyeState Key Laboratory ofMechanical Transmission,Chongqing university,Chongqing 400044, China Chongqing university State Key Laboratory of Mechanical Transmission 重庆 400044

The rmomechanical phenomens occurring between friction pairs greatly changethe distributions of lining pressure and friction surface temperature of a multiple disc wet *** has become one of the main causes of brake failure. In order to understand these thermomechanicalphenomena, several design and material factors that have great influence on thermomechanicalphenomena, such as heat transfer coefficient, friction factor; sliding velocity, initial liningpressure and so on, are analyzed. An isothermal design method is proposed for designing a multipledisc wet brake.

关键词： Wet brake Thermomechanical phenomena Heat transfer coefficient Frictionfactor

Dimension reduction based on weighted variance estimate

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Science China mathematics 2009年第3期52卷 539-560页

作者： ZHAO JunLong1 & XU XingZhong2.1 department of mathematics, Beihang university Laboratory of {2., Information and Behavior of the Ministry of Education, Beijing 100083, China 2.department of mathematics, Beijing Institute of Technology, Beijing 100081, China department of mathematics Beihang University Laboratory of mathematics Information and Behavior of the Ministry of Education Beijing 100083 China department of mathematics Beijing Institute of Technology Beijing 100081 China

In this paper, we propose a new estimate for dimension reduction, called the weighted variance estimate (WVE), which includes Sliced Average Variance Estimate (SAVE) as a special case. Bootstrap method is used to select the best estimate from the WVE and to estimate the structure dimension. And this selected best estimate usually performs better than the existing methods such as Sliced Inverse Regression (SIR), SAVE, etc. Many methods such as SIR, SAVE, etc. usually put the same weight on each observation to estimate central subspace (CS). By introducing a weight function, WVE puts different weights on different observations according to distance of observations from CS. The weight function makes WVE have very good performance in general and complicated situations, for example, the distribution of regressor deviating severely from elliptical distribution which is the base of many methods, such as SIR, etc. And compared with many existing methods, WVE is insensitive to the distribution of the regressor. The consistency of the WVE is established. Simulations to compare the performances of WVE with other existing methods confirm the advantage of WVE.

关键词： central subspace contour regression sliced average variance estimate sliced inverse regression sufficient dimension reduction weight function 62.08 62.05

Lipschitz equivalence of generalized {1,3,5}-{1,4,5} self-similar sets

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Science China mathematics 2007年第11期50卷 1537-1551页

作者： Li-feng XI~(1+) Huo-jun RUAN~2.1 Institute of mathematics,Zhejiang Wanli university,Ningbo 315100,China 2.{2.,Zhejiang university,Hangzhou 31002.,China Institute of mathematics Zhejiang Wanli University Ningbo 315100 China department of mathematics Zhejiang University Hangzhou 310027 China

This paper investigates the Lipschitz equivalence of generalized {1,3,5}-{1,4,5} self-similar sets D=(r_1D)∪(r_2.+(1+r_1-r_2.r_3)/2.∪(r_3D+1+r_3) and E=(r_1E)∪(r_2.+1-r_2. r_3)∪(r_3E+1-r_3),and proves that D and E... 详细信息

关键词： self-similar set overlap Lipschitz equivalence graph-directed construction ergodicity martingale

SPECTRAL AND PSEUDOSPECTRAL APPROXIMATIONS IN TIME FOR PARABOLIC EQUATIONS

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Journal of Computational mathematics 1998年第2期16卷 107-120页

作者： Fa-yong Zhang (department of mathematics, Heilongjiang university, Harbin 150080, China) Heilongjiang Univ Dept Math Harbin 150080 Peoples R China

In this paper, spectral and pseudospectral methods are applied to both time and space variables for parabolic equations. Spectral and pseudospectral schemes are given, and error estimates are obtained for approximate ... 详细信息

关键词： spectral approximation pseudospectral approximation parabolic equation error estimate

Density functional study on enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine

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Science China Chemistry 2006年第4期49卷 296-307页

作者： LI Ming1, ZHENG Wenxu2.& TIAN Anmin2.1. department of Chemistry, Southwest-China Normal university, Chongqing 400715, China 2. department of Chemistry, Sichuan university, Chengdu 610064, China 1. department of Chemistry Southwest-China Normal University Chongqing 400715 China 2. department of Chemistry Sichuan University Chengdu 610064 China

The enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine is discussed by the density functional theory (DFT) method. The main intermediates and transition states for this reaction are optimized completely at the B3LYP/6-31g(d) level, and the transition states are verified by vibrational modes. As shown, the chirality-controlled steps for this re- action are the hydride transfer from borane to carbonyl carbon and oxime carbon of keto oxime ether, and the chirality for the reduced products is determined in these two reaction steps. In all examined reaction paths, the first hydride is transferred via a six-membered ring and the second hydride via a five-membered ring or a four-membered ring.

关键词： keto oxime ether, oxazaborolidine, enantioselective reduction, DFT.

Completely regular paracompact reflection of locales

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Science China mathematics 2006年第6期49卷 820-826页

作者： HE Wei & LUO Maokang department of mathematics, Nanjing Normal university, Nanjing 2.0097, China department of mathematics, Sichuan university, Chengdu 610064, China department of mathematics Nanjing Normal University Nanjing 210097 China department of mathematics Sichuan University Chengdu 610064 China

We give an explicit construction of the completely regular paracompact reflection pL of a completely regular locale L described as a sublocale of the Stone-tech compactification βL of L.

关键词： completely regular paracompact locale, nucleus.

Limit theory of restricted range approximations of complex-valued continuous functions

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Science China mathematics 2007年第10期50卷 1427-1440页

作者： Xian-fa LUO~1 Chong LI~(2.) ~1 School of mathematics and Computer Science,Jishou university,Jishou 416000,China ~2.{2.,Zhejiang university,Hangzhou 31002.,China 1. School of mathematics and Computer Science Jishou University Jishou 416000 China 2. department of mathematics Zhejiang University Hangzhou 310027 China

This paper is concerned with the problem of the best restricted range approximations of complex-valued continuous functions. Several properties for the approximating set PΩ such that the classical characterization results and/or the uniqueness results of the best approximations hold are introduced. Under the very mild conditions, we prove that these properties are equivalent that P is a Haar subspce.

关键词： restricted range approximation, Haar subspace, characterization, uniqueness

Study on the two and three-parameter working stability regions of 3Y-TZP suspension

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Science China(Technological Sciences) 2006年第5期49卷 547-568页

作者： CHEN Youqiang1, 2. ZHANG Xinni3, CHEN Sha’ou3 & QI Ping3 1. department of Chemistry, Qingdao university, Qingdao 2.6071, China 2. department of Chemistry, Tsinghua university, Beijing 100084, China 3. department of Physics, Qingdao university, Qingdao 2.6071, China 1. department of Chemistry Qingdao University Qingdao 266071 China 2. department of Chemistry Tsinghua University Beijing 100084 China 3. department of Physics Qingdao University Qingdao 266071 China

We determined the variation tendency of viscosity (η) at various solids load- ing (α) for 3Y-TZP suspension as a function of dispersant concentration (Cw) using vis- cosity measurement, measured the diameter of particles as a function of Cw in very dilute suspension using light scattering method, and obtained the surface features of the sedi- ment of suspension with different Cw using SEM. We also discussed the influence of the microstructure of adsorbed polymer layers on particles and their interactions in the dis- persing medium on the stability of suspension. Then two different stable states and two different unstable states for 3Y-TZP suspension were given. Accordingly, the (Cw, η), (Cw, α), and (α, η) two-parameter, and (Cw, α, η) three-parameter stability maps were con- structed. Based on the DLVO theory calculations, the dispersant concentration, particle distance (r), and interparticle potential energy (VT) maps with various solids loading for 3Y-TZP aqueous suspension were also constructed. In (Cw, r) two-parameter coordinate system, the stable motion region map for particles was established. The Cw, α, and VT,max (the highest potential energy) surface of the potential barrier map was obtained through calculation and simulation on the basis of the surfaces of Cw, r, VT maps introduced above. The (Cw, α) two-parameter stability map was then obtained from the Cw, α, VT,max map. The results showed that this theoretical map can qualitatively prove the experimentally obtained results—the existence of different dispersed states of particles in suspension system and the variation tendency of suspension stability with changing each parame- ter—were reasonable.

关键词： 3Y-TZP, suspension, stability, DLVO theory, interparticle potential energy.

Mean size formula of wavelet subdivision tree on Heisenberg group

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Applied mathematics(A Journal of Chinese Universities) 2008年第3期23卷 303-312页

作者： WANG Guo-mao department of mathematics,Zhejiang university,Hangzhou 31002.,China department of mathematics,Hangzhou Dianzi university,Hangzhou 310018,China. department of mathematics Zhejiang University Hangzhou 310027 China department of mathematics Hangzhou Dianzi University Hangzhou 310018 China

The purpose of this paper is to investigate the mean size formula of wavelet packets （wavelet subdivision tree） on Heisenberg group. The formula is given in terms of the p-norm joint spectral radius. The vector refinement equations on Heisenberg group and the subdivision tree on the Heisenberg group are discussed. The mean size formula of wavelet packets can be used to describe the asymptotic behavior of norm of the subdivision tree.

关键词： Heisenberg group wavelet packets subdivision tree joint spectral radius stability