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Ab Initio MO Studies on the Reaction Mechanism for Carbonyl Insertion Catalyzed by Carbonyl Cobalt Complex

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Chemical Research in Chinese Universities 2000年第1期16卷 31-35页

作者： LEI Ming FENG Wen-lin and xu Zhen-feng (department of applied Chemistry, beijing university of Chemical technology,beijing 100029, P. R. china department of Chemistry, beijing Normal university, beijing 100875, P. R. china) 北京化工大学北京 100029 北京师范大学北京 100875

Ab initio method, under the effective core potential(ECP) approximation at HF/LANL2DZ level, has been employed to study the reaction mechanism of the carbonyl insertion of olefin hydroformylation catalyzed by a carbonyl cobalt HCo(CO)_3. The two reaction paths have been discussed. The calculated potential energy barriers for the carbonyl migration and the ethyl group migration are 105. 0 kJ/mol and 39. 17 kJ/mol, respectively. The results indicate that the reaction path via ethyl migration is more energetically favorable than that via carbonyl insertion.

关键词： Carbonyl Cobalt Hydroformylation Ab initio method Effective core potential

A fiducial argument for generalized p-value

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Science china mathematics 2007年第7期50卷 957-966页

作者： Xin-min LI~(1+) Xing-zhong xu~2 Guo-ying LI~3 1 Institute of applied mathematics,Shandong university of technology,Zibo 255049,china 2 department of mathematics,beijing Institute of technology,beijing 100801,china 3 Academy of mathematics and Systems Science,Chinese Academy of Sciences,beijing 100800,china Institute of applied mathematics Shandong University of Technology Zibo China department of mathematics Beijing Institute of Technology Beijing China Academy of Mathemtics and Systems Science Chinese Academy of Sciences Beijing China

This paper provides a general method for constructing generalized p-value via the fiducial ***,the power properties of the generalized test are *** illustrations, the two-parameter exponential distribution and unbalan... 详细信息

关键词： fiducial distribution generalized p-value frequency property two-parameter exponential distribution variance component 62F03 62E15

Approximation bounds for quadratic maximization and max-cut problems with semidefinite programming relaxation

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Science china mathematics 2007年第11期50卷 1583-1596页

作者： Da-chuan xu~(1+) Shu-zhong ZHANG~2 1 department of applied mathematics,beijing university of technology,beijing 100022,china 2 department of Systems Engineering and Engineering Management,The Chinese university of Hong Kong,Shatin,Hong Kong,china department of applied mathematics Beijing University of Technology Beijing China department of Systems Engineering and Engineering Management The Chinese University of Hong Kong Shatin Hong Kong China

In this paper,we consider a class of quadratic maximization *** a subclass of the problems,we show that the SDP relaxation approach yields an approximation solution with the worst-case performance ratio at leastα=0.87856….In fact,the estimated worst-case performance ratio is dependent on the data of the problem withαbeing a uniform lower *** light of this new bound,we show that the actual worst-case performance ratio of the SDP relaxation approach (with the triangle inequalities added) is at leastα+δ_d if every weight is strictly positive,whereδ_d>0 is a constant depending on the problem dimension and data.

关键词： quadratic maximization max-cut problem semideflnite programming relaxation approximation algorithm performance ratio

A　NEW　SUFFICIENT　CONDITION　FOR　THE　CONVERGENCE　OF　THE　DFP　ALGORITHM　WITH　WOLFE　LINE　SEARCH

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Systems Science and Mathematical Sciences 1996年第3期9卷 259-269页

作者： xu dachuan(department of mathematics,Qufu Normal university,Qufu 273165,china)LIU Guanghui(Institute of applied mathematics, Academia Sinica, beijing 100080,china)

ＡＮＥＷＳＵＦＦＩＣＩＥＮＴＣＯＮＤＩＴＩＯＮＦＯＲＴＨＥＣＯＮＶＥＲＧＥＮＣＥＯＦＴＨＥＤＦＰＡＬＧＯＲＩＴＨＭＷＩＴＨＷＯＬＦＥＬＩＮＥＳＥＡＲＣＨ￥ＸＵＤａｃｈｕａｎ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉ... 详细信息

ＡＮＥＷＳＵＦＦＩＣＩＥＮＴＣＯＮＤＩＴＩＯＮＦＯＲＴＨＥＣＯＮＶＥＲＧＥＮＣＥＯＦＴＨＥＤＦＰＡＬＧＯＲＩＴＨＭＷＩＴＨＷＯＬＦＥＬＩＮＥＳＥＡＲＣＨ￥ＸＵＤａｃｈｕａｎ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＱｕｆｕＮｏｒｍａｌＵｎｉｖ...

关键词： Global convergence DFP algorithm Wolfe line Search

Novel Experimental Method in the Study of Double Rydberg States by Laser Resonance Excitation

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Chinese Journal of Lasers 1997年第2期B6卷 141-146页

作者： xu Xiangyuan HUANG Wen(department of Modern applied Physics, Tsinghua university, beijing 100084, china) Tsinghua Univ Beijing China

We describe a novel experimental method by introducing sequential ionization with a pulsed and a strong constant electric field in a time-of-flight mass spectrometer. This method is applied to study laser-excited double Rydberg states of neutral ytterbium atom, with the ionic resonance background in the spectrum of the double Rydberg states of Yb being greatly suppressed.

关键词： atomic double Rydberg state laser excitation field ionization

Approximation of dense-n/2-subgraph and table compression problems

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Science china mathematics 2005年第9期48卷 1223-1233页

作者： xu dachuan~1 HAN Jiye~2 & DU Dongle~3 1. College of applied Sciences,beijing university of technology,beijing 100022,china 2. Institute of applied mathematics,Academy of mathematics and Systems Science,Chinese Academy of Sciences,beijing 100080,china 3. Faculty of Administration,university of New Brunswick,P.O.Box 4400,Fredericton,NB E3B 5A3,Canada College of applied Sciences Beijing University of Technology Beijing 100022 China Institute of applied mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China Faculty of Administration University of New Brunswick P.O. Box 4400 Fredericton NB E3B 5A3 Canada

We develop improved approximation algorithms for two NP-hard problems: the dense-n/2-subgraph and table *** on SDP relaxation and advanced rounding techniques,we first propose 0. 5982 and 0. 5970-approximation algorithms respec- tively for the dense-n/2-subgraph problem (DSP) and the table compression problem (TCP). Then we improve these bounds to 0. 6243 and 0. 6708 respectively for DSP and TCP by adding triangle inequalities to strengthen the SDP *** results for TCP beat the 0. 5 bound of a simple greedy algorithm on this problem,and hence answer an open question of Anderson in an affirmative way.

关键词： dense-n/2-subgraph problem(DSP) table compression problem(TCP) SDP approximation ratio

Two-dimensional Compact Perfect Shuffle Optical Interconnection

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Chinese Journal of Lasers 1995年第2期B4卷 133-136页

作者： ZHANG Erping YU Chongxiu ZHOU Jing xu Daxiong(BOX 163#, department of applied Science & technology, beijing university ofPosts and Telecommunications, beijing 100088, china) beijing Univ of Posts and Telecommunications Beijing China

Ｔｗｏ－ｄｉｍｅｎｓｉｏｎａｌＣｏｍｐａｃｔＰｅｒｆｅｃｔＳｈｕｆｆｌｅＯｐｔｉｃａｌＩｎｔｅｒｃｏｎｎｅｃｔｉｏｎ￥ＺＨＡＮＧＥｒｐｉｎｇ；ＹＵＣｈｏｎｇｘｉｕ；ＺＨＯＵＪｉｎｇ；ＸＵＤａｘｉｏｎｇ（ＢＯＸ１６３＃... 详细信息

Ｔｗｏ－ｄｉｍｅｎｓｉｏｎａｌＣｏｍｐａｃｔＰｅｒｆｅｃｔＳｈｕｆｆｌｅＯｐｔｉｃａｌＩｎｔｅｒｃｏｎｎｅｃｔｉｏｎ￥ＺＨＡＮＧＥｒｐｉｎｇ；ＹＵＣｈｏｎｇｘｉｕ；ＺＨＯＵＪｉｎｇ；ＸＵＤａｘｉｏｎｇ（ＢＯＸ１６３＃，ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌ...

关键词： PS(perfect shuffle) HOE optical interconnection

On exactness and unbiasedness of confidence bands for a continuous distribution function

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Science china mathematics 2010年第10期53卷 2665-2678页

作者： DING XiaoBo1,2,xu XingZhong2 & ZHAO ShuRan3 1Institute of applied mathematics,Academy of mathematics and Systems Science,Chinese Academy of Sciences,beijing 100190,china 2department of mathematics,beijing Institute of technology,beijing 100081,china 3School of Economics,Ocean university of china,Qingdao 266071,china Institute of applied mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China department of mathematics Beijing Institute of Technology Beijing China School of Economics Ocean University of China Qingdao China

We define a class of confidence bands for distribution functions,named simple confidence *** class of bands includes the common step bands and continuous bands,some of which may perform better than the smoothed bands not belonging to the class,e.g.,the kernel smoothed *** is shown that under some mild assumptions,the simple bands with exact coverage for continuous distribution functions are all step *** unbiasedness problem of the step bands is also *** is proved that most of two-sided step bands are biased and one-sided step bands are unbiased.

关键词： exact coverage goodness of fit kernel smoothing simple confidence bands unbiasedness

The evolution and morphological stability of a spherical crystal

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Science china(Technological Sciences) 2008年第3期51卷 225-243页

作者： CHEN MingWen1,2, WANG ZiDong2 & xu JianJun3,4 1 School of applied Sciences, university of Science and technology beijing, beijing 100083, china 2 School of Materials Science and Engineering, university of Science and technology beijing, beijing 100083, china 3 School of Mathematical Sciences, Nankai university, Tianjin 300071, china 4 department of mathematics and Statistics, McGill university, Montreal H3A 2K6, Canada School of applied Sciences University of Science and Technology Beijing Beijing China School of Materials Science and Engineering University of Science and Technology Beijing Beijing China School of Mathematical Sciences Nankai University Tianjin China department of mathematics and Statistics McGill University Montreal Canada

The growth model of a spherical crystal in the undercooled melt including the surface energy, interfacial kinetics and convective flow is established. The effect of the convective flow induced by a small far field flow on the evolution and morphological stability of the interface of the spherical crystal is studied. The interface shape of the spherical crystal, which is affected by the far field flow, and the dispersion relation of the growth rate of amplitude of the perturbed interface are derived. It is shown that the convection induced by the far field flow makes the interface of the growing spherical crystal further grow in the upstream direction of the far field flow and inhibit growth in the downstream direction; the interface of the decaying spherical crystal further decays in the upstream direction and inhibits decay in the downstream direction. The theoretical result suggests that both the growth of the sphere in the upstream direction and the decay of the sphere in the downstream direction make the spherical crystal tend to evolve into an oval; the morphological stability of the interface depends on a certain radius R c such that the spherical crystal is unstable when its radius is greater than R c and stable when its radius is less than R c . The surface energy and interfacial kinetics have strong stabilizing effects on the growth of the spherical crystal. In the meantime interfacial kinetics is a table factor of the interface when the interface of the sphere is growing; it is an unstable factor of the interface when the interface is decaying.

关键词： solid-liquid interface spherical crystal convective flow crystal growth morphological stability