A polymeric gel is an aggregate of polymers and solvent molecules, which can retain its shape after a large deformation. The deformation behavior of polymeric gels was often described based on the Flory-Rehner free en...A polymeric gel is an aggregate of polymers and solvent molecules, which can retain its shape after a large deformation. The deformation behavior of polymeric gels was often described based on the Flory-Rehner free energy function without considering the influence of chain entanglements on the mechanical behavior of gels. In this paper,a new hybrid free energy function for gels is formulated by combining the EdwardsVilgis slip-link model and the Flory-Huggins mixing model to quantify the time-dependent concurrent process of large deformation and mass transport. The finite element method is developed to analyze examples of swelling-induced deformation. Simulation results are compared with available experimental data and show good agreement. The influence of entanglements on the time-dependent deformation behavior of gels is also demonstrated.The study of large deformation kinetics of polymeric gel is useful for diverse applications.展开更多
Based on the theory of the post method pedagogy and the teaching practice，this paper proposes a new teaching model，the self-correction model，and explains it from the point of view of linking theory.
We study the phenomena of preferential linking in a large-scale evolving online social network and find that the linear preference holds for preferential creation, preferential acceptance, and preferential attachment....We study the phenomena of preferential linking in a large-scale evolving online social network and find that the linear preference holds for preferential creation, preferential acceptance, and preferential attachment. Based on the linear preference, we propose an analyzable model, which illustrates the mechanism of network growth and reproduces the process of network evolution. Our simulations demonstrate that the degree distribution of the network produced by the model is in good agreement with that of the real network. This work provides a possible bridge between the micro=mechanisms of network growth and the macrostructures of online social networks.展开更多
The object of study is about dynamic modeling and control for a 2degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic anddynamic equations are established according to the characte...The object of study is about dynamic modeling and control for a 2degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic anddynamic equations are established according to the characteristics of mixed rigid and flexiblestructure. By using the singular perturbation approach (SPA), the model of the mechanism can beseparated into slow and fast subsystems. Based on the feedback linearization theory and inputshaping technique, the large scale rigid motion controller and the flexible link vibrationcontroller can be designed separately to achieve fast and accurate positioning of the PM.展开更多
Select link analysis provides information of where traffic comes from and goes to at selected links.This disaggregate information has wide applications in practice.The state-of-the-art planning software packages often...Select link analysis provides information of where traffic comes from and goes to at selected links.This disaggregate information has wide applications in practice.The state-of-the-art planning software packages often adopt the user equilibrium(UE) model for select link analysis.However,empirical studies have repeatedly revealed that the stochastic user equilibrium model more accurately predicts observed mean and variance of choices than the UE model.This paper proposes an alternative select link analysis method by making use of the recently developed logit–weibit hybrid model,to alleviate the drawbacks of both logit and weibit models while keeping a closed-form route choice probability expression.To enhance the applicability in large-scale networks,Bell’s stochastic loading method originally developed for logit model is adapted to the hybrid model.The features of the proposed method are twofold:(1) unique O–D-specific link flow pattern and more plausible behavioral realism attributed to the hybrid route choice model and(2) applicability in large-scale networks due to the link-based stochastic loading method.An illustrative network example and a case study in a large-scale network are conducted to demonstrate the efficiency and effectiveness of the proposed select link analysis method as well as applications of O–D-specific link flow information.A visualizationmethod is also proposed to enhance the understanding of O–D-specific link flow originally in the form of a matrix.展开更多
Linked tetra shaft and double cantilever flat flap gate is a new type of structure in water conservancy projects,but the traditional method is now adopted in its design.In order to the application and dissemination ...Linked tetra shaft and double cantilever flat flap gate is a new type of structure in water conservancy projects,but the traditional method is now adopted in its design.In order to the application and dissemination of the type of sluice,this paper researches the difficult points of design advance,through researching the motion locus & stress coundition of linked tetra shaft system.The writer will build up the mathmatical model and handle it with the computer.Thus,we can achieve the modern desing on the basis of the software of linked tetra shaft system development.展开更多
This paper presents a novel adaptive nonlinear model predictive control design for trajectory tracking of flexible-link manipulators consisting of feedback linearization, linear model predictive control, and unscented...This paper presents a novel adaptive nonlinear model predictive control design for trajectory tracking of flexible-link manipulators consisting of feedback linearization, linear model predictive control, and unscented Kalman filtering. Reducing the nonlinear system to a linear system by feedback linearization simplifies the optimization problem of the model predictive controller significantly, which, however, is no longer linear in the presence of parameter uncertainties and can potentially lead to an undesired dynamical behaviour. An unscented Kalman filter is used to approximate the dynamics of the prediction model by an online parameter estimation, which leads to an adaptation of the optimization problem in each time step and thus to a better prediction and an improved input action. Finally, a detailed fuzzy-arithmetic analysis is performed in order to quantify the effect of the uncertainties on the control structure and to derive robustness assessments. The control structure is applied to a serial manipulator with two flexible links containing uncertain model parameters and acting in three-dimensional space.展开更多
Usually it is demanded that the metric and its 1st derivatives have to match at the boundary of two adjacent regions which are solutions to Einstein’s field equation. We propose a new linking condition concerning gra...Usually it is demanded that the metric and its 1st derivatives have to match at the boundary of two adjacent regions which are solutions to Einstein’s field equation. We propose a new linking condition concerning gravitational models based on surfaces which could be embedded into a higher dimensional flat space. We probe this condition for the Schwarzschild interior and exterior solution.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
针对气象变化对自由空间光(Free Space Optical,FSO)通信链路和毫米波射频(Radio Frequency,RF)通信链路可用率的影响问题,采用马尔科夫建模与稳态概率求解计算方法,分析不同天气条件下FSO/RF混合链路的双接收站分集与中断概率性能.基于...针对气象变化对自由空间光(Free Space Optical,FSO)通信链路和毫米波射频(Radio Frequency,RF)通信链路可用率的影响问题,采用马尔科夫建模与稳态概率求解计算方法,分析不同天气条件下FSO/RF混合链路的双接收站分集与中断概率性能.基于FSO链路和RF链路的信道模型,采用有限状态马尔科夫链(Finite State Markov Chain,FSMC)分别对单双站FSO/RF混合链路的切换选择进行建模,推导得出不同参数和天气情况下系统稳态的中断概率表达式.数值计算结果表明,当中断概率达到10^(-6),雨雾天气链路距离为1~7 km时,双站FSO/RF混合链路相比单站可获得4~25 dB的增益.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.11272237 and11502131)the Natural Science Foundation of Fujian Province(No.2016J05019)the Foundation of the Higher Education Institutions of Fujian Education Department for Distinguished Young Scholar(No.[2016]23)
文摘A polymeric gel is an aggregate of polymers and solvent molecules, which can retain its shape after a large deformation. The deformation behavior of polymeric gels was often described based on the Flory-Rehner free energy function without considering the influence of chain entanglements on the mechanical behavior of gels. In this paper,a new hybrid free energy function for gels is formulated by combining the EdwardsVilgis slip-link model and the Flory-Huggins mixing model to quantify the time-dependent concurrent process of large deformation and mass transport. The finite element method is developed to analyze examples of swelling-induced deformation. Simulation results are compared with available experimental data and show good agreement. The influence of entanglements on the time-dependent deformation behavior of gels is also demonstrated.The study of large deformation kinetics of polymeric gel is useful for diverse applications.
文摘Based on the theory of the post method pedagogy and the teaching practice，this paper proposes a new teaching model，the self-correction model，and explains it from the point of view of linking theory.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61104139,70871082,and 71101053)the ECUST for Excellent Young Scientists,China
文摘We study the phenomena of preferential linking in a large-scale evolving online social network and find that the linear preference holds for preferential creation, preferential acceptance, and preferential attachment. Based on the linear preference, we propose an analyzable model, which illustrates the mechanism of network growth and reproduces the process of network evolution. Our simulations demonstrate that the degree distribution of the network produced by the model is in good agreement with that of the real network. This work provides a possible bridge between the micro=mechanisms of network growth and the macrostructures of online social networks.
基金This project is supported by National Natural Science Foundation of China (No.50390064, No.50375099) Doctorate Foundation of Ministry of Education of China(No.20020248048).
文摘The object of study is about dynamic modeling and control for a 2degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic anddynamic equations are established according to the characteristics of mixed rigid and flexiblestructure. By using the singular perturbation approach (SPA), the model of the mechanism can beseparated into slow and fast subsystems. Based on the feedback linearization theory and inputshaping technique, the large scale rigid motion controller and the flexible link vibrationcontroller can be designed separately to achieve fast and accurate positioning of the PM.
基金supported by National Natural Science Foundation of China(51408433)Fundamental Research Funds for the Central Universities of Chinathe Chenguang Program sponsored by Shanghai Education Development Foundation and Shanghai Municipal Education Commission
文摘Select link analysis provides information of where traffic comes from and goes to at selected links.This disaggregate information has wide applications in practice.The state-of-the-art planning software packages often adopt the user equilibrium(UE) model for select link analysis.However,empirical studies have repeatedly revealed that the stochastic user equilibrium model more accurately predicts observed mean and variance of choices than the UE model.This paper proposes an alternative select link analysis method by making use of the recently developed logit–weibit hybrid model,to alleviate the drawbacks of both logit and weibit models while keeping a closed-form route choice probability expression.To enhance the applicability in large-scale networks,Bell’s stochastic loading method originally developed for logit model is adapted to the hybrid model.The features of the proposed method are twofold:(1) unique O–D-specific link flow pattern and more plausible behavioral realism attributed to the hybrid route choice model and(2) applicability in large-scale networks due to the link-based stochastic loading method.An illustrative network example and a case study in a large-scale network are conducted to demonstrate the efficiency and effectiveness of the proposed select link analysis method as well as applications of O–D-specific link flow information.A visualizationmethod is also proposed to enhance the understanding of O–D-specific link flow originally in the form of a matrix.
文摘Linked tetra shaft and double cantilever flat flap gate is a new type of structure in water conservancy projects,but the traditional method is now adopted in its design.In order to the application and dissemination of the type of sluice,this paper researches the difficult points of design advance,through researching the motion locus & stress coundition of linked tetra shaft system.The writer will build up the mathmatical model and handle it with the computer.Thus,we can achieve the modern desing on the basis of the software of linked tetra shaft system development.
文摘This paper presents a novel adaptive nonlinear model predictive control design for trajectory tracking of flexible-link manipulators consisting of feedback linearization, linear model predictive control, and unscented Kalman filtering. Reducing the nonlinear system to a linear system by feedback linearization simplifies the optimization problem of the model predictive controller significantly, which, however, is no longer linear in the presence of parameter uncertainties and can potentially lead to an undesired dynamical behaviour. An unscented Kalman filter is used to approximate the dynamics of the prediction model by an online parameter estimation, which leads to an adaptation of the optimization problem in each time step and thus to a better prediction and an improved input action. Finally, a detailed fuzzy-arithmetic analysis is performed in order to quantify the effect of the uncertainties on the control structure and to derive robustness assessments. The control structure is applied to a serial manipulator with two flexible links containing uncertain model parameters and acting in three-dimensional space.
文摘Usually it is demanded that the metric and its 1st derivatives have to match at the boundary of two adjacent regions which are solutions to Einstein’s field equation. We propose a new linking condition concerning gravitational models based on surfaces which could be embedded into a higher dimensional flat space. We probe this condition for the Schwarzschild interior and exterior solution.
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.
文摘针对气象变化对自由空间光(Free Space Optical,FSO)通信链路和毫米波射频(Radio Frequency,RF)通信链路可用率的影响问题,采用马尔科夫建模与稳态概率求解计算方法,分析不同天气条件下FSO/RF混合链路的双接收站分集与中断概率性能.基于FSO链路和RF链路的信道模型,采用有限状态马尔科夫链(Finite State Markov Chain,FSMC)分别对单双站FSO/RF混合链路的切换选择进行建模,推导得出不同参数和天气情况下系统稳态的中断概率表达式.数值计算结果表明,当中断概率达到10^(-6),雨雾天气链路距离为1~7 km时,双站FSO/RF混合链路相比单站可获得4~25 dB的增益.
