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Design and Experiments of a Robotic Fish Imitating Cow-Nosed Ray

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Journal of Bionic Engineering 2010年第2期7卷 120-126页

作者： Yueri Cai,Shusheng Bi,Licheng Zheng Robotics Institute,beihang university,beijing 1.01.1,P.R.china [a] Robotics Institute Beihang University Beijing 100191 P. R. China

The cow-nosed ray is studied as natural sample of a flapping-foil robotic *** structure, motion discipline, and dynamicfoil deformation of cow-nosed ray are *** on the analysis results, a robotic fish imitating cow-nosed ray,named Robo-ray Ⅱ, mainly composed of soft body, flexible ribs and pneumatic artificial muscles, is *** andswimming morphology of the robotic prototype are as that of a normal cow-nosed ray in *** propulsion parameters ofRobo-ray Ⅱ at normal conditions, including the St Number at linear swimming, thrust coefficient at towing are studied *** suitable driving parameters are confirmed considering the efficiency and swimming *** of 0.16 m·s’and thrust coefficient of 0.56 in maximum are achieved in experiments.

关键词： robotic fish cow-nosed ray flexible structure St Number thrust coefficient

Cutting Performance and Mechanism of RE Carbide Tools

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Rare Metals 2001年第3期20卷 197-201页

作者： Jianbing Cheng, Yufang Wu, Qixun Yu 1) Department of Mechanical Engineering, beijing Technology and Business university, beijing 100037, china 2) college of Mechanical Engineering and Automation, beijing Institute of Technology beijing 100081, china beijing Technol & Business Univ Dept Mech Engn Beijing 100037 Peoples R China beijing Inst Technol Coll Mech Engn & Automat Beijing 100081 Peoples R China

The research of rare earth elements (RE), added into cemented carbide tools, is one of the recent developments of new types of tool materials in china. Systematic experiments about RE carbides YG8R. (K30), YT14R (P20) and, YW1R (M10) were made to study on the cutting performance in comparison with non-RE carbides YG8, YT14 and YW1. The cutting experiments were as follows: tool life, cutting force, tool-chip friction coefficient and interrupted machining. The action of RE on the carbide materials and the cutting mechanism of the RE carbide tools in the cutting process were verified with the aid of SEM and energy spectrum analysis. Experimental results show that the RE carbide tools have a good overall performance.

关键词： rare earth elements cemented carbide tool cutting performance cutting mechanism

Empirical likelihood-based inference in a partially linear model for longitudinal data

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Science china Mathematics 2008年第1期51卷 115-130页

作者： XUE LiuGen~(1+) & ZHU LiXing~2 1 college of Applied Sciences, beijing university of Technology, beijing 100022, china 2 Department of Mathematics, Hong Kong Baptist university, Hong Kong, china college of Applied Sciences Beijing University of Technology Beijing 100022 China Department of Mathematics Hong Kong Baptist University Hong Kong China

A partially linear model with longitudinal data is considered, empirical likelihood to infer- ence for the regression coefficients and the baseline function is investigated, the empirical log-likelihood ratios is proven to be asymptotically chi-squared, and the corresponding confidence regions for the pa- rameters of interest are then constructed. Also by the empirical likelihood ratio functions, we can obtain the maximum empirical likelihood estimates of the regression coefficients and the baseline function, and prove the asymptotic normality. The numerical results are conducted to compare the performance of the empirical likelihood and the normal approximation-based method, and a real example is analysed.

关键词： partially linear model empirical likelihood confidence region longitudinal data 62G05 62G15 62G20

Numerical Simulation of Damage and Fracture on Typical Interfaces of Plasma Sprayed Thermal Barrier Coatings

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稀有金属材料与工程 2011年第S3期40卷 166-170页

作者： Qi Hongyu, Yang Xiaoguang, Xie Jian, Wei Hongliang beihang university, beijing 1.01.1, china beihang Univ Sch Jet Prop Beijing 100191 Peoples R China

Modern thermal barrier coatings (TBC) are required to not only limit heat transfer through the coating but to also protect engine components from thermal cyclic load and oxidation. Failure mechanism of TBC is important for the safety status of components. To obtain a better understanding of the failure mechanism under thermal cyclic load, a new type of interface elements with three nodes which is based on the idea of interface damage mechanics was proposed. Compared with traditional interface elements, these elements have the quality of indicating the normal direction of interface with arbitrary shape. The modified model was implemented into ABAQUS by user subroutine UEL. The damage and fracture of cosine shape interface were numerical simulated considering the rough interface of the plasma sprayed thermal barrier coating. The calculating results show that, under thermal cycle loadings, the displacement between nodes of the interface elements is not continuous which represents the opening process of the interface crack, the damage increases with the number of thermal cycle loadings and the max damage is caused during the first cycle, the top of the interface is the critical position and the normal separation dominants; under tension loadings, the wavy interface has better capability of load bearing than the linear interface for PS-TBC. Simulation of damage and fracture for different materials with arbitrary interface using the modified interface elements is available, and the results are reasonable.

关键词： interface elements thermal barrier coatings interfaces damage fracture

Topological relations between directed lines and simple geometries

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Science china(Technological Sciences) 2008年第S1期51卷 91-101页

作者： GAO Yong1,ZHANG Yi1,TIAN Yuan1 & WENG JingNong2 1 Institute of Remote Sensing and Geographic Information System,Peking university,beijing 100871,china 2 Colledge of Software,beihang university,beijing 100083,china 1. Institute of Remote Sensing and Geographic Information System Peking University Beijing 100871 China2. Colledge of Software Beihang University Beijing 100083 China

Directed lines are fundamental geometric elements to represent directed linear en-tities. The representations of their topological relations are so different from those of simple lines that they cannot be solved exactly with normal methods. In this paper,a new model based on point-set topology is defined to represent the topo-logical relations between directed lines and simple geometries. Through the inter-sections between the start-points,end-points,and interiors of the directed lines and the interiors,boundaries,and exteriors of the simple geometries,this model identifies 5 cases of topological relations between directed lines and points,39 cases of simple lines,and 26 cases of simple polygons. Another 4 cases of simple lines and one case of simple polygons are distinguished if considering the exteri-ors of the directed lines. All possible cases are furthermore grouped into an exclu-sive and complete set containing 11 named predicts. And the conceptual neigh-borhood graph is set up to illustrate their relationship and similarity. This model can provide a basis for natural language description and spatial query language to present the dynamic semantics of directed lines relative to the background fea-tures.

关键词： topological relation directed line simple geometry intersection model

Presenting degenerate Ringel-Hall algebras of type B

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Science china Mathematics 2012年第5期55卷 949-960页

作者： FAN LiJuan1 & ZHAO ZhongHua2,1Department of Mathematics,beijing Normal university,beijing 100875,china 2Department of Mathematics and computer Science,School of Science,beijing university of Chemical Technology,beijing 100029,china 1. Department of Mathematics Beijing Normal University Beijing 100875 China2. Department of Mathematics and Computer Science School of Science Beijing University of Chemical Technology Beijing 100029 China

We give a presentation for the degenerate Ringel-Hall algebras of type B by studying the corresponding generic extension monoid *** an application,it is shown that the degenerate Ringel-Hall algebras of type B admit m... 详细信息

关键词： degenerate Ringel-Hall algebras generic extension monoid algebras Auslander-Reiten quivers Frobenius morphism

Co-adaptability solution to conflict events in construction projects by segmented hierarchical algorithm

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Science china(Technological Sciences) 2008年第7期51卷 932-939页

作者： HOU XueLiang1 & LU Mei2 1 Department of Construction Management, Tsinghua university, beijing 100084, china 2 college of Management, Xi’an university of Architecture and Technology, Xi’an 710055, china 1. Department of Construction Management Tsinghua University Beijing 100084 China 2. college of Management Xi’an University of Architecture and Technology Xi’an 710055 China

In order to seek the co-adaptability solution to conflict events in construction engineering projects, a new method referred to as segmented hierarchical algorithm is proposed in this paper by means of comparing co-adaptability evolution process of conflict events to the stackelberg model. By this new algorithm, local solutions to the first-order transformation of co-adaptability for conflict events can be obtained, based upon which, a global solution to the second-order transformation of co-adaptability for conflict events can also be decided by judging satisfaction degree of local solutions. The research results show that this algorithm can be used not only for obtaining co-adaptability solution to conflict events efficiently, but also for other general decision-making problems with multi-layers and multi-subsidi-aries in project management field.

关键词： conflict co-adaptability segmented hierarchical algorithm

The kink-soliton and antikink-soliton in quasi-one-dimensional nonlinear monoatomic lattice

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Science china(Physics,Mechanics & Astronomy) 2005年第2期48卷 150-157页

作者： XU Quan1 & TIAN Qiang2 1. Scientific and Technological Office, Daqing Teacher college, Daqing 163712, china 2. Department of Physics , beijing Normal university, beijing 100875, china Scientific and Technological Office Daqing Teacher College Daqing 163712 China Department of Physics Beijing Normal University Beijing 100875 China

The quasi-one-dimensional nonlinear monoatomic lattice is analyzed. The kink-soliton and antikink-soliton are presented. When the interaction of the lattice is strong in the x-direction and weak in the y-direction, the two-dimensional (2D) lattice changes to a quasi-one-dimensional lattice. Taking nearest-neighbor interaction into account, the vibration equation can be transformed into the KPI, KPII and MKP equation. Considering the cubic nonlinear potential of the vibration in the lattice, the kink-soliton solution is presented. Considering the quartic nonlinear potential and the cubic interaction potential, the kink-soliton and antikink-soliton solutions are presented.

关键词： two-dimensional nonlinear lattice, quasi-one-dimensional nonlinear lattice, kink-soliton, antikink-soliton.

Investigation of Mechanical Property of Oil Tube Steel P110S in High Temperature and High Pressure Environment Containing H_2S/CO_2

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Journal of Iron and Steel Research International 2011年第S1期18卷 685-689页

作者： LI Xiao-dong 1,QI Ya-meng 2,CHEN Chang-feng 2,DONG Xiu-cheng 1 (1.School of Business Administration,china university of Petroleum(beijing),beijing 102249,china 2.college of Science,china university of Petroleum(beijing),beijing 102249,china) china Univ Petr Sch Business Adm Beijing 102249 Peoples R China china Univ Petr Coll Sci Beijing 102249 Peoples R China

With the exploitation of high sour and deep oil well in china,the corrosion medium containing CO 2,H 2 S,Cl-and organic acid threaten the safety of oil equipment and tube steel *** this article,many experiments,including corrosion tests,tensile tests,hydrogen concentration measurement tests and SEM examinations,were performed to investigate the effect of H 2 S partial pressure and loading stress on the mechanical property of oil tube steel P110S in high temperature and high pressure environment containing H 2 S/CO *** tensile strength and yield strength during fracture process of P110S steel were obtained experimentally and the fracture morphology was analyzed by *** results indicate that both tensile strength and yield strength decreased after *** damage of tensile strength and yield strength became serious with an increase in H 2 S partial pressure and loading *** to the fracture analysis,the fracture mode exhibited quasi-cleavage and dimple mixed fracture,and the area of quasi-cleavage pattern increased with H 2 S partial pressure and loading stress *** to the results of tensile test and hydrogen concentration measurement test,the tensile property degradation is closely associated with diffusible hydrogen concentration of P110S steel in the H 2 S/CO 2 environment.

关键词： metallic tension P110S diffusible hydrogen H 2 S/CO 2 corrosion