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On the tribological characteristics of dynamically loaded journal bearing with micropolar fluids

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Science china(Physics,Mechanics & Astronomy) 2004年第Z1期47卷 45-50页

作者： WANG Xiaoli, WANG Kongying & ZHU KeqinSchool of Mechanical and Vehicular Engineering, beijing institute of technology, beijing 100081, china department of Engineering Mechanics, Tsinghua University, {4. 100084. china School of Mechanical and Vehicular Engineering Beijing Institute of Technology Beijing China department of Engineering Mechanics Tsinghua University Beijing China

The addition of the additives to the lubricant oil to enhance the characteristics of the lubricant will influence the performance of the bearings. Based on the theory of micropolar fluids, the tribological characteristics of a dynamically-loaded journal bearing are numerically studied. Comparisons are made between the Newtonian fluids and the micropolar fluids. It is shown that for a dynamically-loaded journal bearing, the micropolar fluids yield an increase not only in the friction force, but also in the friction coefficient. In addition, the oil film pressure and the oil film thickness are obviously higher than that of Newtonian fluids.

关键词： micropolar fluids, dynamic loads journal bearing tribological characteristics.

The Existence of Solutions to Sturm-Liouville Boundary Value Problems with Laplacian-like Operator

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Acta Mathematicae Applicatae Sinica 2002年第2期18卷 341-348页

作者： Wei-ping Sun, Wei-gao Gedepartment of Applied Mathematics, beijing institute of technology, beijing 100081, china department of Applied Mathematics Beijing Institute of Technology Beijing China

The existence of infinitely many solutions to Sturm-Liouville boundary value problem with a Laplacian-like operator is studied by applying generalized polar coordinates.

关键词： Generalized polar coordinates Laplacian-like operator boundary value problem

Weighted estimation of single index models with right censored responses

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Science china Mathematics 2011年第3期54卷 479-514页

作者： WANG YanHua1, LI XiaYan2, WANG QiHua3 & HE ShuYuan4.1School of Sciences, beijing institute of technology, beijing 100081, china 2department of Mathematics, University of Science and {4. of china, Hefei 230026, china 3Chinese Academy of Mathematics and System Science, beijing 100080, china 4.chool of Mathematical Sciences, Capital Normal University, beijing 10004., china School of Sciences Beijing Institute of Technology Beijing China department of Mathematics University of Science and Technology of China Hefei China Chinese Academy of Mathematics and System Science Beijing China School of Mathematical Sciences Capital Normal University Beijing China

In this paper, the unknown link function, the direction parameter, and the heteroscedastic variance in single index models are estimated by the random weight method under the random censorship, respectively. The central limit theory and the convergence rate of the law of the iterated logarithm for the estimator of the direction parameter are derived, respectively. The optimal convergence rates for the estimators of the link function and the heteroscedastic variance are obtained. Simulation results support the theoretical results of the paper.

关键词： single index models random censorship central limit theorem law of the iterated logarithm weighted least squares unknown link function

The Study of the Damage Laws of Pool Fires

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Journal of Thermal Science 1995年第4期4卷 271-275页

作者： Yu Deming Feng Changgen Zeng Qingxuan Guo Xinya (Mechanics & Engineering department, beijing institute of technology, beijing 100081, china) Mechanics & Engineering department Beijing Institute of Technology Beijing China

This paper studies pool fires in open air and their damage laws. First, it discusses the damage criteria of thermal radiation, then presents an algorithm to predict damage radii of pool fires, and performs numerical calculations by using a software called POOLFIRE, which has been developed by the authors, finally discusses the possible ways to improve the algorithm and gives the conclusions obtained from the study.

关键词： pool fires damage criteria damage radii algorithm numerical calculation.

Preparation of Unsupported Molybdenum Phosphide Hydrofining Catalysts

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催化学报 2003年第2期24卷 79-80页

作者： LI Fengyan, ZHAO Tianbo, SUN Guida, LI Cuiqing (department of Applied Chemistry, beijing institute of Petrochemical technology, beijing 102617, china) department of Applied Chemistry Beijing Institute of Petrochemical Technology 北京 102617

The interface between homogeneous catalysis and heterogeneous catalysis has great scope for the development of new catalytic materials . Supported aqueous-phase (SAP) catalysis has been employed for the hydroformylation of olefins under mild conditions with high efficiency and convenient separation from the products . Heterogeneous hydroformylation is a promising process because of its easy separation . However, there is no commercial hydroformylation process using a heterogeneous catalyst owing to the comparatively low activity and selectivity. We have reported the enhancement of activity and selectivity through the syner-gistic effect between a heterogeneous component and a SAP catalyst for the hydroformylation of hexene-1 over SM(supported metal)-SAP catalyst . It was well known that the performance of supported metal catalysts for many reactions can be improved by oxide promoters. In this work, the catalysts consisting of the heterogeneous component of Rh-V/SiO2 and the homogeneous component of HRhCO(TPPTS)3 were prepared, and the attempts were made to show the promotion effect of vanadium oxides on the syn-ergism between the heterogeneous component and the SAP catalyst for hydroformylation of hexene-1.

关键词：磷化钼催化加氢催化剂催化性能

Entropy number and non-linear approximations on multivariate Besov space by manifolds of finite pseudo-dimension

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Progress in Natural Science:Materials International 2006年第3期16卷 260-265页

作者： LONG Jingfan and FANG Gensun (School of Mathematical Sciences, beijing Normal University, beijing 100875, china department of Computer Science, Information {4. institute, beijing 100101, china) School of Mathematical Sciences Beijing Normal University Beijing 100875 China department of Computer Science Information Technology Institute Beijing 100101 China

We determine the asymptotic order of entropy number and optimal non -linear approximations of anisotropic periodic Besov class of Bpθr(Td') (1≤p≤∞,1≤0≤∞) by manifolds of finite pseudo-dimension in the metric Lq... 详细信息

关键词： Pseudo-dimension anisotropic Besov class of functions entropy number nonlinear width.

Research on resolution between multi-component LFM signals in the fractional Fourier domain

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Science china(Information Sciences) 2012年第6期55卷 1301-1312页

作者： LIU Feng 1,XU HuiFa 1,2,TAO Ran 3 & WANG Yue 3 1 department of electronic and Information Engineering,Naval Aeronautical Engineering institute,Yantai 264.01,china 2 The 94.62 th Unit of People's Liberation Army,Qingdao 266111,china 3 School of Information Science and technology,beijing institute of technology,beijing 100081,china department of electronic and Information Engineering Naval Aeronautical Engineering Institute Yantai China The 94.62th Unit of People’s Liberation Army Qingdao China School of Information Science and technology Beijing Institute of Technology Beijing China

When the initial frequencies and chirp rates of multi-component linear frequency modulation (LFM or chirp) signals are close,the signals may not be distinguished in the fractional Fourier domain (FRFD).Consequently,some signals cannot be *** this paper,first,the spectral distribution characteristics of a continuous LFM signal in the FRFD are analyzed,and then the spectral distribution characteristics of a LFM signal in the discrete FRFD are ***,the critical resolution distance between the peaks of two LFM signals in the FRFD is deduced,and the relationship between the dimensional normalization parameter and the distance between two LFM signals in the FRFD is also *** is discovered that selecting a proper dimensional normalization parameter can increase the ***,a method to select the parameter is proposed,which can improve the resolution ability of the fractional Fourier transform (FRFT).Its effectiveness is verified by simulation results.

关键词： fractional Fourier transform LFM signal signal resolution

Synthesis of N-acetamide C_(60) nitride and its performance of optical limiting

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Chinese Science Bulletin 2000年第2期45卷 150-153页

作者： TANG Guangshi, ZHU Hesun & SONG Yinglin Research Center of Materials Science, beijing institute of technology, beijing 100081, china department of Applied Physics, Harbin {4. of technology. Harbin 150001. china department of Applied Chemiscy Beiji Research Center of Materials Science Beijing institute of Technology Beijing China department of Applied Chemistry Beijing University of Chemicals Technology Beijing China department of Applied Physics Harbin Institute of Technology Harbin China

N-acetamide C60 nitride (N-acetamide-1,2-dihydro-1,2-aza-fullerene[60]) has been synthesized by the reaction of C60 and azidoacetamide and initially characterized. Its mechanism was that the objective product is formed through intermediate triazoline. The computational study shows that N-nitride structure is thermodynamically more stable by using the semi-empirical AM1 SCF-MO method. The properties of optical limiting were tested by using double frequency Nd: YAG pulse laser system and showed that the optical limiting mechanism is reverse saturation absorption. At wavelength of 532 nm, compared with optical limiting for ns pulse, this new material has good optical limiting character for ps pulse. At wavelength of 707 nm. the capacity of optical limiting of the derivative is prior to C60-

关键词： C60 derivatives N-nitride structure optical limiting properties reverse saturation absorption.

ON THE EQUATION(t) =-ax(t) + bx(x(t))(b > a > 0)

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Systems Science and Mathematical Sciences 2000年第2期13卷 195-200页

作者： SUN Weiping GE Weigao (department of Applied Mathematics, beijing institute of technology, beijing 100081, china)

The existence and behavior of the solution of the differential-iterative equation x(t) =-ax(t)+bx(x(t))(b > a > 0) are studied. Some errors in [1] are corrected.

关键词： Differential-iterative equation fixed point monotone solution.