The uncertainty of the mechanism motion error is mostly caused by the manufacturing process,so the motion error cannot be effectively predicted at the design phase.The problems of manufacturing complexity and the rela...The uncertainty of the mechanism motion error is mostly caused by the manufacturing process,so the motion error cannot be effectively predicted at the design phase.The problems of manufacturing complexity and the relationship between design and manufacturing are analyzed,and the influence of dimensional tolerance and fit tolerance on the motion accuracy of the system is considered in the design process.Then based on the Monte Carlo simulation,an optimal design model of planar linkage mechanism is set up.A typical offset slider-crank mechanism is used as an illustrative example to carry out the optimal design.Compared with the result of typical robustness design,the similar variation characteristics of the mean value and the standard deviation can be found,so the proposed method is effective.The method is furthermore applied in the optimization of the schemes with different fit tolerances and the prediction of motion errors in the design phase is achieved.A set of quantitative evaluation system for mechanism optimal design is provided.Finally,a basic strategy is presented to balance the motion precision and manufacturing cost.展开更多
The analytical solutions of the non-steady-state concentrations of species at a planar microelectrode are presented. These simple new approximate expressions of concentrations are valid for all values of time and poss...The analytical solutions of the non-steady-state concentrations of species at a planar microelectrode are presented. These simple new approximate expressions of concentrations are valid for all values of time and possible values of rate constants. Analytical equations are given to describe the current when the homogeneous equilibrium position lies heavily in favour of the electroinactive species. Working surfaces are presented for the variation of limiting current with a homogeneous kinetic parameter and equilibrium constant. Moreover, in this work we employ the Homotopy perturbation method to solve the boundary value problem.展开更多
There are clearances in mechanism because of manufacture and assembly error,which reduces operation life and working accuracy of mechanism and has a great impact on dynamical responses.At the moment,research in this a...There are clearances in mechanism because of manufacture and assembly error,which reduces operation life and working accuracy of mechanism and has a great impact on dynamical responses.At the moment,research in this area mainly focuses on single degree⁃of⁃freedom mechanism considering one clearance,while research of multi⁃DOF mechanism considering multi⁃clearance is less.With the purpose of studying the dynamical characteristics of complex multi⁃DOF mechanism with multi⁃clearances,a dynamic model was developed.The dynamic responses of 2⁃DOF mechanism with two clearances under different positions,values,and numbers of clearance were analyzed.The displacement,velocity,acceleration,collision force,and the axis trajectory at clearance were then given.In addition,there is a limited amount of literature on chaotic phenomena,which mainly focuses on the chaotic phenomena of end⁃effector of mechanism.But in this paper,the non⁃linear characteristics were analyzed by chaotic phenomenon of clearance joint,then chaotic phenomenon was identified by Poincarémappings and phase diagrams.Bifurcation diagrams were given.The results will offer a reliable technical support for the study of dynamical responses of planar mechanisms and the analysis of chaotic phenomena.展开更多
In this paper, chemical mechanical planarization (CMP) of amorphous Ge2Sb2Te5 (a-GST) in acidic H2O2 slurry is investigated. It was found that the removal rate of a-GST is strongly dependent on H2O2 concentration and ...In this paper, chemical mechanical planarization (CMP) of amorphous Ge2Sb2Te5 (a-GST) in acidic H2O2 slurry is investigated. It was found that the removal rate of a-GST is strongly dependent on H2O2 concentration and gradually increases with the increase in H2O2 concentration, but the static etch rate first increases and then slowly decreases with the increase in H2O2 concentration. To understand the chemical reaction behavior of H2O2 on the a-GST surface, the potentiodynamic polarization curve, surface morphology and cross-section of a-GST immersed in acidic slurry are measured and the results reveal that a-GST exhibits a from active to passive behavior for from low to high concentration of H2O2 . Finally, a possible removal mechanism of a-GST in different concentrations of H2O2 in the acidic slurry is described.展开更多
A method for automatically establishing a mathematical model of kinematic analysis to a planar mechanism with multiple joint and prismatic pair is presented.The breadth(or depth) first search spanning tree can be obta...A method for automatically establishing a mathematical model of kinematic analysis to a planar mechanism with multiple joint and prismatic pair is presented.The breadth(or depth) first search spanning tree can be obtained based on an adjacency matrix of the mechanism.Then the kinematic chain(or mechanism)'s basic loops can be obtained.On the basis of these basic loops,a mathematical model of kinematic analysis can be established and solved automatically.In the sense of a calculative mechanism,structural analysis of the kinematic chain relates to the kinematic analysis of a mechanism.Thus,an effective way is supplied to the given mechanism's kinematic analysis for automatic modeling and solving,and a method is supplied to the structural type to optimize kinematic synthesis.展开更多
This paper relates to the deep research on the Splinc Model Method of KED analysis. With the use of cubic B-splinc function as a link’s transverse deflection interpolation function, the principle of virtual displacem...This paper relates to the deep research on the Splinc Model Method of KED analysis. With the use of cubic B-splinc function as a link’s transverse deflection interpolation function, the principle of virtual displacement is presented as a basic theory for the general formulation of the equations of motion, and thus abandoned the kinematic assumption and the instantaneous structure assumption which arc used in the Spline Model Method. In thc same time, the nonlinear terms sue as coupling terms between thc rigid body motion and elastic deformation arc included. New member’s spline models are established. Mass matrix, Coriolis mass matrix, normal and tangential mass matrix, linear stiffness matrix, nonlinear stiffness matrix and rotation matrix arc derived. The kinematic differential equations of a member and system are deduced in the end. The Newmark direct integration method is used as the solution scheme of the kinematic differential equations to get the periodic response.展开更多
By using transfer matrix,the lower-order natural frequencies of the Watt type planar six-barlinkage are calculated in this paper.The experiment of the modal analysis is done with the SignalProcessor 7T17S,and the expe...By using transfer matrix,the lower-order natural frequencies of the Watt type planar six-barlinkage are calculated in this paper.The experiment of the modal analysis is done with the SignalProcessor 7T17S,and the experiment results agree with the calculated ones.This method only re-quires calculation of lower-order transfer matrix and determinant values,so that, it can be done ona minicomputer such as IBM/PC.The method adopted in this paper is also suitable for vibrationanalysis of other types of linkages.展开更多
基金supported by the National Natural Science Foundation of China(No.51275365)the National High-tech R&D Program (863 Program ) (No. 2014AA041504)
文摘The uncertainty of the mechanism motion error is mostly caused by the manufacturing process,so the motion error cannot be effectively predicted at the design phase.The problems of manufacturing complexity and the relationship between design and manufacturing are analyzed,and the influence of dimensional tolerance and fit tolerance on the motion accuracy of the system is considered in the design process.Then based on the Monte Carlo simulation,an optimal design model of planar linkage mechanism is set up.A typical offset slider-crank mechanism is used as an illustrative example to carry out the optimal design.Compared with the result of typical robustness design,the similar variation characteristics of the mean value and the standard deviation can be found,so the proposed method is effective.The method is furthermore applied in the optimization of the schemes with different fit tolerances and the prediction of motion errors in the design phase is achieved.A set of quantitative evaluation system for mechanism optimal design is provided.Finally,a basic strategy is presented to balance the motion precision and manufacturing cost.
文摘The analytical solutions of the non-steady-state concentrations of species at a planar microelectrode are presented. These simple new approximate expressions of concentrations are valid for all values of time and possible values of rate constants. Analytical equations are given to describe the current when the homogeneous equilibrium position lies heavily in favour of the electroinactive species. Working surfaces are presented for the variation of limiting current with a homogeneous kinetic parameter and equilibrium constant. Moreover, in this work we employ the Homotopy perturbation method to solve the boundary value problem.
基金Sponsored by the Shandong Key Research and Development Public Welfare Program(Grant No.2019GGX104011)the Natural Science Foundation of Shandong Province(Grant No.ZR2017MEE066).
文摘There are clearances in mechanism because of manufacture and assembly error,which reduces operation life and working accuracy of mechanism and has a great impact on dynamical responses.At the moment,research in this area mainly focuses on single degree⁃of⁃freedom mechanism considering one clearance,while research of multi⁃DOF mechanism considering multi⁃clearance is less.With the purpose of studying the dynamical characteristics of complex multi⁃DOF mechanism with multi⁃clearances,a dynamic model was developed.The dynamic responses of 2⁃DOF mechanism with two clearances under different positions,values,and numbers of clearance were analyzed.The displacement,velocity,acceleration,collision force,and the axis trajectory at clearance were then given.In addition,there is a limited amount of literature on chaotic phenomena,which mainly focuses on the chaotic phenomena of end⁃effector of mechanism.But in this paper,the non⁃linear characteristics were analyzed by chaotic phenomenon of clearance joint,then chaotic phenomenon was identified by Poincarémappings and phase diagrams.Bifurcation diagrams were given.The results will offer a reliable technical support for the study of dynamical responses of planar mechanisms and the analysis of chaotic phenomena.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2010CB934300, 2011CBA00607, and 2011CB9328004)the National Integrate Circuit Research Program of China (Grant No. 2009ZX02023-003)+2 种基金the National Natural Science Foundation of China (Grant Nos. 60906004, 60906003,61006087, 61076121, 61176122, and 61106001)the Science and Technology Council of Shanghai, China (Grant Nos. 11DZ2261000 and 11QA1407800)the Chinese Academy of Sciences (Grant No. 20110490761)
文摘In this paper, chemical mechanical planarization (CMP) of amorphous Ge2Sb2Te5 (a-GST) in acidic H2O2 slurry is investigated. It was found that the removal rate of a-GST is strongly dependent on H2O2 concentration and gradually increases with the increase in H2O2 concentration, but the static etch rate first increases and then slowly decreases with the increase in H2O2 concentration. To understand the chemical reaction behavior of H2O2 on the a-GST surface, the potentiodynamic polarization curve, surface morphology and cross-section of a-GST immersed in acidic slurry are measured and the results reveal that a-GST exhibits a from active to passive behavior for from low to high concentration of H2O2 . Finally, a possible removal mechanism of a-GST in different concentrations of H2O2 in the acidic slurry is described.
基金supported by the Foundation for Docotors of Xiangtan University under Grant No. 08QDZ42the Project of Engineering Research Center of Ministry of Education under Grant No. 09-FZGJ04
文摘A method for automatically establishing a mathematical model of kinematic analysis to a planar mechanism with multiple joint and prismatic pair is presented.The breadth(or depth) first search spanning tree can be obtained based on an adjacency matrix of the mechanism.Then the kinematic chain(or mechanism)'s basic loops can be obtained.On the basis of these basic loops,a mathematical model of kinematic analysis can be established and solved automatically.In the sense of a calculative mechanism,structural analysis of the kinematic chain relates to the kinematic analysis of a mechanism.Thus,an effective way is supplied to the given mechanism's kinematic analysis for automatic modeling and solving,and a method is supplied to the structural type to optimize kinematic synthesis.
基金This project is supported by National Basic Research Program of China (973 Program, N0.2003CB716201)National Natural Science Foundation of China (No.50575131)Science Foundation of Shanghai Municipal Commission of Science and Technology, China(No.0452nm013).
文摘This paper relates to the deep research on the Splinc Model Method of KED analysis. With the use of cubic B-splinc function as a link’s transverse deflection interpolation function, the principle of virtual displacement is presented as a basic theory for the general formulation of the equations of motion, and thus abandoned the kinematic assumption and the instantaneous structure assumption which arc used in the Spline Model Method. In thc same time, the nonlinear terms sue as coupling terms between thc rigid body motion and elastic deformation arc included. New member’s spline models are established. Mass matrix, Coriolis mass matrix, normal and tangential mass matrix, linear stiffness matrix, nonlinear stiffness matrix and rotation matrix arc derived. The kinematic differential equations of a member and system are deduced in the end. The Newmark direct integration method is used as the solution scheme of the kinematic differential equations to get the periodic response.
文摘By using transfer matrix,the lower-order natural frequencies of the Watt type planar six-barlinkage are calculated in this paper.The experiment of the modal analysis is done with the SignalProcessor 7T17S,and the experiment results agree with the calculated ones.This method only re-quires calculation of lower-order transfer matrix and determinant values,so that, it can be done ona minicomputer such as IBM/PC.The method adopted in this paper is also suitable for vibrationanalysis of other types of linkages.
基金the National Natural Science Foundation of China(10632060)the Special Funds for the Major State Basic Research Projects of China(G2003CB615603,G2006CB601202)
