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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 school of mechanical engineering Jiangnan University Wuxi China school of mechanical engineering Anhui University of Science and Technology Huainan China State Key Laboratory of Fluid Power Transmission and Control Hangzhou China Robotics Research Center Yanshan University Qinhuangdao 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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Rolling Element Bearing Diagnostics by Combination of Envelope Analysis and Wavelet Transform

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Journal of university of science and technology Beijing 2001年第1期8卷 69-74页

作者： Ying Tang, Qiao Sun mechanical engineering school, university of science and technology Beijing, Beijing 100083, china Department of mechanical engineering, university of Calgary Calgary Alberta T2N 1N4, Canada mechanical engineering school Univ. of Sci. and Technology Beijing Beijing 100083 China

Rolling element-bearing diagnostics has been studied over the last thirty years, and envelope analysis is widely recognized as being the best approach for detection and diagnosis of rolling element bearing incipient failure. But one of the on-going difficulties with envelope technique is to determine the best frequency band to envelop. Here, wavelet transform technique is introduced into envelope analysis to solve the problem by capturing bearing defects-sensory scales (i.e. frequency bands). A modulated Gaussian function is chosen to be the analytical wavelet because it coincides well with bearing defect-induced vibration signal patterns. Vibration signals measured from railway bearing tests were studied by the proposed method. Cases of bearings with single and multiple defects on inner and outer race under different testing conditions are presented. Experimental results showed that the proposed method allowed a more accurate local description and separation of transient signal part, which were caused by impacts between defects and the mating surfaces in the bearing. The combination method provides an effective signal detection technique for rolling element-bearing diagnostics.

关键词： continuous wavelet transform envelope analysis rolling element bearing diagnostics

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Production of O' -sialon-SiC Composites by Carbon Reduction-Nitridation

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International Journal of Minerals,Metallurgy and Materials 1998年第1期12卷 26-30页

作者： Haijun Zhang Wenchao Li Xiangcong Zhong (Applied science school, university of science and technology Beijing, Beijing 1 0008 3, china) Applied science school University of Science and Technology Beijing Beijing 100083 China

The effect of temperature, soak times, carbon and addition on composites was discussed in the process ofsynthesizing O'-sialon-SiC by carbonthermal reduction-nitration from nature kaolin. It showed that the fracturestrength (MOR) of composites sintered under certain conditions can be up to 140MPa at room temperature. Thetarget parameter optima regions with good mechanical properties of this material were also indicated by usingcomputer pattern recognition program.

关键词： O'-sialon-SiC compostites carbonthermal reduction-nitration pattern recognition program

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Mathematical Model for the Drying Process of Granular Materials in a Fluidized Bed

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International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 296-300页

作者： Xiulan Huai, Li Wang, Zhiyun Qu ( mechanical engineering school, university of science and technology Beijing, Beijing 100083, china Chemical Industry Research Institute of Shanxi, Taiyuan 030031, china) mechanical engineering school University of Science and Technology Beijing Beijing 100083 China Chemical Industry Research Institute of Shanxi Taiyuan 030031 China

The experiment of granular materials, barley, drying in a fluidized bed was carried out to investigate the influence of the factors, inlet air temperature, air moisture, bed height and original moisture content of the dried materials on drying process. Based on the experimental data, a corresponding mathematical model is presented. As a conclusion, a higher inlet air temperature and a reasonable bed height should be used so as to increase the dring rate and to improve the product quality.

关键词： fluidization granular materials drying, experimental investigation mathematical model Information

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Real-time Non-linear Target Tracking Control of Wheeled Mobile Robots

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武汉理工大学学报 2006年第S3期28卷 861-866页

作者： YU Wenyong school of mechanical engineering,Huazhong university of science & technology,Wuhan 430074,china, school of mechanical engineering Huazhong University of Science & TechnologyWuhan 430074China

A control strategy for real-time target tracking for wheeled mobile robots is *** a modified Kalman filter for environment perception,a novel tracking control law derived from Lyapunov stability theory is *** of linear velocity and angular velocity with mechanical constraints is *** proposed control system can simultaneously solve the target trajectory prediction,real-time tracking,and posture regulation problems of a wheeled mobile *** results illustrate the effectiveness of the proposed tracking control laws.

关键词： wheeled mobile robots motion control dynamic tracking

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Microwave Disinfection in a Ventilation and Air-Conditioning System

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湖南大学学报（自然科学版） 2009年第S1期36卷 55-59页

作者： LU Zhen1,2,ZHANG Ji-li1,MA Liang-dong1,HE Juan3(1.school of Civil & Hydraulic engineering,Dalian university of technology,Dalian,liaoning 116023,china 2.Municipal and Environmental engineering Research Center,Shenyang Jianzhu university,Shenyang,liaoning 110168,china 3.school of Municipal & Environmental engineering,Harbin Institute of technology,Harbin,Heilongjiang 150090,china) school of Civil and Hydraulic engineering Dalian University of Technology Dalian 116023 China Municipal and Environmental engineering Research Center Shenyang Jianzhu University Shenyang 110168 China school of Municipal and Environmental engineering Harbin Institute of Technology Harbin 150090 China

Because of its broad spectrum and high efficiency,the microwave disinfection was used to control the airborne microbial contaminates in VAC *** microwave disinfection devices were developed combined with air filter,the design and calculation method was presented,and the disinfection effects on White staphylococcus,Staphylococcus aureus,Bacillus Subtilis,Escherichi coli were *** results show that the major influence factors on disinfection effect are microwave power,water-content of filter material,disinfecting *** 15 min,the kill ratio is >90%,and the log value is >*** microwave field is uniform and the kill effect of bacteria on each surface of filter is the same,without statistically significant difference.

关键词： VAC system microwave disinfection airborne microbe microwave power kill ratio

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Large-eddy simulations and vortex structures of turbulent jets in crossflow

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science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 118-132页

作者： GUAN Hui1,2 & WU ChuiJie2 1 school of mechanical and Power engineering,East china university of science and technology,Shanghai 200237,china 2 Research Center for Fluid Dynamics,PLA university of science and technology,Nanjing 211101,china school of mechanical and Power engineering East China University of Science and Technology Shanghai China Research Center for Fluid Dynamics PLA University of Science and Technology Nanjing China

Using the method of large-eddy simulation, the 3-dimensional turbulent jets in crossflow with stream-wise and transverse arrangements of nozzle are simulated, emphasizing on the dynamical process of generation and evolution of vortex structures in these flows. The results show that the basic vortex structures in literatures, such as the counter-rotating vortex pair, leading-edge vortices, lee-side vortices, hanging vortices, kidney vortices and anti-kidney vortices, are not independent physical substances, but local structures of the basic vortex structure of turbulent jets in crossflow-the 3-D stretching vortex rings originating from the orifice of the nozzle, which is discovered in this study. Therefore, the most important large-scale structures of turbulent jets in crossflow are unified to the 3-D vortex rings which stretch and twist in stream-wise and swing in transverse directions. We also found that the shedding frequencies of vortex rings are much lower than the one corresponding to the appearance of leading-edge and lee-side vortices in the turbulent jets.

关键词： turbulent jet in crossflow coherent structure large-eddy simulation

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Complex conforming Delaunay triangulation

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science china(Information sciences) 2010年第6期53卷 1130-1140页

作者： MENG XianHai 1, LI JiGang 1, YANG Qin 1, CAI Qiang 2 & CHEN QiMing 3 1 NLSDE, school of Computer science and engineering, BeiHang university, Beijing 100083, china 2 school of Computer sciences, Beijing technology and Business university, Beijing 100037, china 3 school of mechanical engineering and Automation, BeiHang university, Beijing 100083, china NLSDE School of Computer Science and Engineering BeiHang University Beijing China school of Computer sciences Beijing Technology and Business University Beijing China school of mechanical engineering and Automation BeiHang University Beijing China

A novel algorithm of conforming Delaunay triangulation for curved geometry is presented in the paper.A progress has been made for the problem puzzled Delaunay refinement where curved constraints cannot be accepted as input *** algorithm is based on a new sufficient condition for the existence of constraints in *** requires computing only the intersection between constraints and Voronoi edges or faces instead of the circum-sphere of curved *** the termination of the algorithm when small input angles exist in constraints, a weighted method is applied to ensure that the algorithm can terminate under any *** two-dimensional and three-dimensional results are also *** is shown that the algorithm has the capability of dealing with both linear and nonlinear constraints in a consistent way, without the need of maintaining triangular meshes on face constraints.

关键词： mesh generation Delaunay triangulation conforming curved constraints tetrahedralization weight

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External synchronization of two dynamical systems with uncertain parameters

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science china(Technological sciences) 2010年第3期53卷 731-740页

作者： HAN QingKai 1,SUN XiaoYu 2,YANG XiaoGuang 3 &WEN BangChun 1 1 school of mechanical engineering&Automation,Northeastern university,Shenyang 110004,china 2 school of Electrical engineering,Shenyang university of technology,Shenyang 110023,china 3school of mechanical engineering,The university of Birmingham,Birmingham,B15 2TT,UK school of mechanical engineering & Automation Northeastern University Shenyang China school of Electrical engineering Shenyang University of Technology Shenyang China school of mechanical engineering The University of Birmingham Birmingham UK

External synchronization is addressed as two or more dynamical systems with synchronous motions,which is also regarded as master-slave *** this paper,two dynamical systems,one employs a hysteretic term to model the friction phenomenon,the other involves a hardening stiffness component with the third order of displacement due to flexible deformation,are controlled to converge to the same *** control strategy is extended from feedback control for all parameters known to adaptive control for linear parameters unknown and all parameters *** slave system can keep synchronous motions with the movements of master via the designed control strategy even all the parameters are not *** stability of synchronization error,the transient process into synchronization and the effects of parameters on the designed controller using different control strategies are *** simulation results unfold the feasibility and effectiveness of this synchronization method.

关键词： controlled synchronization uncertain parameters hysteretic system Duffing system

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On edge dislocation in a multilayered laminate

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Theoretical & Applied Mechanics Letters 2011年第2期1卷 25-28页

作者： Xu Wang~(a) school of mechanical and Power engineering,East china university of science and technology,Shanghai 200237, china school of mechanical and Power engineering East China University of Science and Technology Shanghai 200237 China

We investigate the elastic field induced by an edge dislocation in a multilayered laminated composite composed of(N—2)thin bonded elastic layers sandwiched between two semi-infinite elastic media.A simple closed-form solution is obtained when all the phases have equal shear modulus but different Poisson's ratios,and when the dislocation is located in the upper semi-infinite *** image force acting on the dislocation due to its interaction with the multilayered structure is also derived. Several specific examples are discussed in detail to illustrate the mobility of the edge dislocation. Some interesting behaviors of the dislocation are *** results indicate that it is possible to find at most(N—2)equilibrium positions for the edge dislocation in an N-phase composite structure.

关键词： laminated composite edge dislocation image force equilibrium position

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