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Orientation-Singularity Representation and Orientation-Capability Computation of a Special Class of the Gough-Stewart Parallel Mechanisms Using Unit Quaternion

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Chinese Journal of Mechanical Engineering 2012年第6期25卷 1096-1104页

作者： LI Baokun1, 2, CAO Yi1, 3, *, ZHAnG Qiuju1, and HUAnG Zhen4 1 School of Mechanical Engineering, Jiangnan University, Wuxi 214122, China 2 School of Mechanical Engineering, Anhui University of Science and Technology, Huainan 232001, China 3 State Key Laboratory of Fluid Power Transmission and Control, Hangzhou 310027, China 4 Robotics Research Center, Yanshan University, Qinhuangdao 066004, China 1. School of Mechanical Engineering Jiangnan University Wuxi 214122 China 2. School of Mechanical Engineering Anhui University of Science and Technology Huainan 232001 China 3. State Key Laboratory of Fluid Power Transmission and Control Hangzhou 310027 China 4. Robotics Research Center Yanshan University Qinhuangdao 066004 China

Singular configuration seriously affects the performance of the Gough-Stewart parallel mechanism and has attracted many researchers’ attentions. However, most of existing topics often focus on the position-singularity of the mechanism for a constant-orientation, but few reports research the orientation-singularity for a given position. In order to investigate the orientation-singularity of the Gough-Stewart parallel mechanisms with two dissimilar semi-regular hexagonal platforms for a given position, after constructing the discrimination matrix of the singular configuration of the mechanism and computing the determinant of this matrix by using unit quaternion as the orientation parameters which can avoid the singularities in parameterization, a general symbolic expression representing the three-dimensional orientation-singularity locus for a given position is obtained and the three-dimensional view of the orientation-singularity locus is further described. The orientation-singularity-free void exists inside the orientation-singularity locus, but the shape of the orientation-singularity-free void is irregular and inconvenient for the design of the mechanism. The minimal inscribed sphere of the three-dimensional orientation-singularity locus namely the orientation-singularity-free ball is described. The radius of the ball orientation-capability is used as the measurement for the orientation-singularity-free void size. A new efficient algorithm is proposed for the computation of the orientation-capability. Finally, the influences of the geometry parameters and the different positions of the mechanism on the orientation-capability are discussed. A new method of the singularity analysis of the Gough-Stewart parallel mechanism is advanced based on the unit quaternion, and the research finds have important referential value for the configuration parameters optimization of this class of the parallel mechanisms with the goal of having the maximal singularity-free zone.

关键词： parallel mechanism unit quaternion orientation-singularity orientation-singularity-free void orientation-capability

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Fracture analysis of a functionally graded interfacial zone between two dissimilar homogeneous materials

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Science China(Physics,Mechanics & Astronomy) 2006年第5期49卷 540-552页

作者： CHEnG Zhanqi1,2 & ZHOnG Zheng1 1. School of Aerospace Engineering and Applied mechanics, Tongji University, Shanghai 200092, China 2. College of Civil Engineering, Zhengzhou University, Zhengzhou 450002, China 1. School of Aerospace Engineering and Applied mechanics Tongji University Shanghai 200092 China 2. College of Civil Engineering Zhengzhou University Zhengzhou 450002 China

In this paper the plane elasticity problem for a functionally graded interfacial zone containing a crack between two dissimilar homogeneous materials has been considered. It is assumed that in the interfacial zone the reciprocal of the shear modulus is a linear function of the coordinate, while Possion’s ratio keeps constant. By utilizing the Fourier transformation technique and the transfer matrix method, the mixed boundary problem is reduced to a system of singular integral equations that are solved numerically. The influences of the geometric parameters and the graded parameter on the stress intensity factors are investigated. The numerical results show that the graded parameters, the thickness of interfacial zone, the crack size and location have significant effects on the stress intensity factors.

关键词： functionally graded material interfacial zone fracture stress intensity factor

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Degradation of 4-chlorophenol in aqueous solution by γ-radiation and ozone oxidation

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Science China Chemistry 2006年第2期49卷 186-192页

作者： HU Jun1, WAnG Jianlong1,2 & CHEn Rong1 1. Laboratory of Environmental Technology, Institute of nuclear Energy Technology, Tsinghua University, Beijing 100084, China 2. State Key Joint Laboratory of Environmental Simulation and Pollution Control, Tsinghua University, Beijing 100084, China Correspondence should be addressed to Wang Jianlong 1. Laboratory of Environmental Technology Institute of Nuclear Energy Technology Tsinghua University Beijing 100084 China 2. State Key Joint Laboratory of Environmental Simulation and Pollution Control Tsinghua University Beijing 100084 China

The degradation of 4-chlorophenol (4-CP) by using gamma rays generated by a 60Co source in the presence of O3 was investigated. The radiolysis of 4-CP and the kinetics of 4-CP min-eralization were analyzed based on the determination of total organic carbon (TOC). The influence of initial 4-CP concentration and the free radicals scavengers (such as naHCO3 and t-butanol) on the 4-CP degradation was also studied. The results showed that when the radiation rate was 336 Gy·min?1, 4-chlorophenol at concentration of 10 mg·L?1 could be completely degraded at the radiation dose of 2 kGy. The degradation of 4-chlorophenol could be described by a first-order reaction model, the rate constant of 4-CP degradation by combined ozonation and radiation was 0.1016 min?1, which was 2.4 times higher than the sum of radiation (0.0294 min?1) and ozonation (0.0137 min?1). It re-vealed that the combination of radiation and ozonation resulted in synergistic effect, which can re-markably increase the degradation efficiency of 4-CP.

关键词： radiolysis, 4-chlorophenol, priority pollutant, degradation, O3, synergistic effect, kinetics.

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Formation control for networked spacecraft in deep space:with or without communication delays and with switching topology

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Science China(Information Sciences) 2011年第3期54卷 469-481页

作者： WAnG nan 1,2, ZHAnG TianWu 2 & XU JieQiong 1 1 School of Aeronautic Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China 2 Department of Computer Science and Engineering, Henan Institute of Engineering, Zhengzhou 451191, China 1. School of Aeronautic Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China2. Department of Computer Science and Engineering Henan Institute of Engineering Zhengzhou 451191 China

In this paper, several formation controllers are developed with constant and variable connected communication topology for six-degree-of-freedom (6-DOF) networked spacecraft flying in deep space with constant and time-varying communication delays considered. In the control algorithm, any explicit leader does not exist in the formation team and it is required that each spacecraft communicate only with its neighbors and therefore the required communication loads of the whole formation is greatly reduced. The proposed control strategies allow that each spacecraft can track its desired position and attitude and simultaneously the whole group moves to the desired formation and obtain its desired relative attitudes with its neighbors. Simulation results demonstrate the effectiveness of the proposed controllers.

关键词： deep space graph theory formation control communication topology delays

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高层建筑工程可建性评价研究

高层建筑工程可建性评价研究

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作者： constant MAHAME 兰州交通大学

学位级别：硕士

本研究旨在研究和评价甘肃省兰州市高层建筑工程的可建性,旨在对我国特别是兰州地区高层建筑项目的可建性进行评价。运用可建性原则对我国建筑业的实际工作进行评价,探讨阻碍高层建筑可建性理念实施的主要因素,并尽可能提出解决方案。... 详细信息

本研究旨在研究和评价甘肃省兰州市高层建筑工程的可建性,旨在对我国特别是兰州地区高层建筑项目的可建性进行评价。运用可建性原则对我国建筑业的实际工作进行评价,探讨阻碍高层建筑可建性理念实施的主要因素,并尽可能提出解决方案。评价政府将扮演的特定角色,以确保适当的可建性原则应用于高层建筑中。本研究的数据是通过结构化问卷的方式收集的,本次研究共收到201份有效问卷,问卷参与者包括学术界人士和建筑专业人士。任何建筑工程的可建性评价,都是指在工程动工前评价该工程是否可行。然而,高层建筑项目在规划、设计和执行方面具有复杂性,这要求项目管理团队不得不适当考虑以往的项目,在项目开始前进行足够的可建性评价,积累足够的施工知识和施工经验,以确保预期的结构稳定性、耐久性、安全性和建筑质量。最后,本研究建议政府继续执行与行业相关的法律环境,避免实际上以“关系”,而非中标人接手建筑项目等不公平文化;采用预制材料和先进技术,以达到预期的质量、成本和工期交付项目。

关键词：高层建筑工程可建性评价研究

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Structural Optimization of a novel Up-run Gas-solid Separator

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China Petroleum Processing & Petrochemical Technology 2011年第2期13卷 36-42页

作者： Gai Xikun1 Tian Yuanyu2 Xia Daohong1 Qiao Yingyun2(1.China University of Petroleum(East China),Qingdao 266555 2.Shandong University of Science and Technology,Qingdao 266510) China Univ Petr E China Qingdao 266555 Peoples R China Shandong Univ Sci & Technol Qingdao 266510 Peoples R China

A new gas-solid separator dedicated to heavy-oil fast pyrolysis process incorporating inertial and centrifugal separation was designed. Gas and typical fluid catalytic cracking （FCC） catalyst particles （with a density of 1500 kg/m3, and a mean diameter of 45.81 p.m） were used in the study. The inlet gas velocity was kept constant at 13.36 m/s, while the solid loading at the inlet ranged from 0 to 700 g/m3. When the exhaust pipe opening was provided with two narrow-width slots near the inlet without baffles, the solid collection efficiency increased with an increasing solid loading at the inlet and was close to 95% along with a decreasing pressure drop. After increasing the secondary separation structure, the separation efficiency greatly improved. By adjusting the diameter of the secondary exhaust pipe, the separation efficiency and pressure drop could be balanced. Under the experimental conditions, when the diameter of the second exhaust pipe was equal to d=100 mm, the pressure drop was lower than 1400 Pa while the separation efficiency could exceed 99.50%; and when the diameter was equal to d=120 mm, the pressure drop was less than 700 Pa, with the separation efficiency reaching over 99.00%.

关键词： gas-solid separation separation efficiency pressure drop cyclone separators

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The dust emission law in the wind erosion process on soil surface

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Science China(Physics,Mechanics & Astronomy) 2009年第2期52卷 258-269页

作者： XInG Mao1 & GUO LieJin2 1 Mining Technology Institute, Taiyuan University of Technology, Taiyuan 030024, China 2 State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China Mining Technology Institute Taiyuan University of Technology Taiyuan 030024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The dust emission models to date cannot describe the relation between the transport rate of different sized grains and their grain size composition in soil surface, so Aeolian grain transport on a soil-like bed composed of fine sand and silt powder was measured in a wind tunnel. Six types of soil-like beds with different silt fractions have been tested in this experiment. The mass flux profiles of silt dust and sand grains are much different due to their different motion modes. Analysis of the vertical distribution of the powder and sand grains reveals that for a given soil bed, the ratio of the horizontal dust flux to the horizontal sand flux is directly proportional to their mass ratio in the bed. The dust flux is closely linked to the sand flux by the bombardment mechanism. For a given wind velocity and grain size of the bed, the slopes of the vertical mass flux profiles of sand grains larger than 100 μm are nearly equal in a log-linear plot and the ratio between the fraction of transport rate of each size group to the whole transport rate and the mass fraction of each size group in the bed is a constant only dependent on grain size. With this law, the transport rate of dust and different sized grains can be related with the grain size composition in the soil surface.

关键词： wind erosion dust transport rate grain size

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Stability of linear discrete switched systems with delays based on average dwell time method

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Science China(Information Sciences) 2010年第6期53卷 1216-1223页

作者： WAnG Yong 1 , WAnG Wei 1 & LIU GuoPing 2,3 1 Research Center of Information and Control, Dalian University of Technology, Dalian 116024, China 2 Faculty of Advanced Technology, University of Glamorgan, Pontypridd, CF37 1DL, UK 3 CTGT Center in Harbin Institute of Technology, Harbin 150001, China 1. Research Center of Information and Control Dalian University of Technology Dalian 116024 China2. Faculty of Advanced Technology University of Glamorgan Pontypridd CF37 1DL UK3. CTGT Center in Harbin Institute of Technology Harbin 150001 China

This paper deals with the problem of exponential stability for a class of linear discrete switched systems with constant *** switched systems consist of stable and unstable *** on the average dwell time method, some switching signals will be found to guarantee exponential stability of these *** explicit state decay estimation is also given in the form of the solutions of linear matrix inequalities(LMIs).An example relating to networked control systems(nCSs) illustrates the effectiveness of the proposed method.

关键词： switched systems average dwell time time delay LMI

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Equilibrium equations for nonlinear buckling analysis of drill-strings in 3D curved well-bores

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Science China(Technological Sciences) 2009年第3期52卷 590-595页

作者： TAn MeiLan1 & GAn LiFei2 1 Faculty of Science, Jiangsu University, Zhenjiang 212013, China 2 94973 Unit in Hangzhou of Zhejiang Province, Hangzhou 310021, China 1. Faculty of Science Jiangsu University Jiangsu Zhenjiang 212013 China 2. 94973 Unit in Hangzhou of Zhejiang Province Hangzhou 310021 China

With the development of drilling technology, the oil/gas well has evolved from its early vertical straight form to the inclined, horizontal, plane curved, or even 3D curved well-bore. Understanding of the buck- ling behavior of a drill-string in a well-bore is crucial for the success of a drilling operation. Therefore, equilibrium equations for analyzing the buckling behavior of a drill-string in a 3D curved well-bore are required. Based on Love’s equilibrium equations for a curved and twisted rod in space, a set of equi- librium equations for the nonlinear buckling analysis of a drill-string in a 3D curved well-bore are de- rived by introducing a radial constraint of the well-bore. The proposed formulae can account for the well curvature and tortuosity. Thus, it can be used to analyze the buckling behaviors of a drill-string constrained in a well-bore and subjected to axial compression, torsion at its upper end, and gravity simultaneously. It is worth noting that the existing equations in the literature for a drill-string in a straight and plane curved well-bore with a constant curvature are a special case of the proposed model. Thus, the present model can provide a theoretical basis for the nonlinear buckling analysis of a drill-string constrained in a 3D curved well-bore.

关键词： nonlinear buckling tortuosity constraint equilibrium equations drill-strings 3D curved well-bores

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Round-optimal zero-knowledge proofs of knowledge for nP

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Science China(Information Sciences) 2012年第11期55卷 2473-2484页

作者： LI HongDa1,FEnG DengGuo2,LI Bao1 & XUE HaiXia1 1State Key Lab of Information Security,Graduate University of Chinese Academy of Sciences,Beijing 100049,China 2State Key Lab of Information Security,Institute of software of Chinese Academy of Sciences,Beijing 100080,China 1. State Key Lab of Information Security Graduate University of Chinese Academy of Sciences Beijing 100049 China2. State Key Lab of Information Security Institute of software of Chinese Academy of Sciences Beijing 100080 China

It is well known that all the known black-box zero-knowledge proofs of knowledge for nP are *** there exit constant-round black-box zero-knowledge proofs of knowledge for all nP languages under certain standard assumptions is an open *** paper focuses on the problem and gives a positive answer by presenting two constructions of constant-round(black-box) zero-knowledge proofs of knowledge for the HC(hamiltonian cycle) *** the recent result of Katz,our second construction which relies on the existence of claw-free functions has optimal round complexity(5-round) assuming the polynomial hierarchy does not collapse.

关键词： zero-knowledge proofs proofs of knowledge black-box simulation constant-round

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