Several parameter identification methods of thermal response test were evaluated through numerical and experimental study.A three-dimensional finite-volume numerical model was established under the assumption that the...Several parameter identification methods of thermal response test were evaluated through numerical and experimental study.A three-dimensional finite-volume numerical model was established under the assumption that the soil thermal conductivity had been known in the simulation of thermal response test.The thermal response curve was firstly obtained through numerical calculation.Then,the accuracy of the numerical model was verified with measured data obtained through a thermal response test.Based on the numerical and experimental thermal response curves,the thermal conductivity of the soil was calculated by different parameter identification methods.The calculated results were compared with the assumed value and then the accuracy of these methods was evaluated.Furthermore,the effects of test time,variable data quality,borehole radius,initial ground temperature,and heat injection rate were analyzed.The results show that the method based on cylinder-source model has a low precision and the identified thermal conductivity decreases with an increase in borehole radius.For parameter estimation,the measuring accuracy of the initial temperature of the deep ground soil has greater effect on identified thermal conductivity.展开更多
A surgical simulation and evaluation method in the anterior cruciate ligament(ACL)reconstructionwith image-free navigation was presented.Firstly,video tracking module,bone surface reconstructionmodule and virtual simu...A surgical simulation and evaluation method in the anterior cruciate ligament(ACL)reconstructionwith image-free navigation was presented.Firstly,video tracking module,bone surface reconstructionmodule and virtual simulation module of this system were discussed.Secondly,the coordinate relations ofseveral surgery objects(including surgical instrument,anatomical,camera and screen)in the surgicalenvironment,the tracking based on MicronTracker with two cameras and the bone surface real-time recon-struction based on the Delaunay algorithm were introduced in detail.Finally,experiments of anisometrymeasurement and virtual simulation on two plastics were carried out to verify the validity of the proposedmethod.The anisometry value of reconstructed ACL was 8.970039mm.The effectiveness of ACL recon-struction has been proved by preliminary evaluation trials.展开更多
For the three-dimensional compressible multicomponent displacement problem we put forward the modified method of characteristics with finite element operator-splitting procedures and make use of operator-splitting,cha...For the three-dimensional compressible multicomponent displacement problem we put forward the modified method of characteristics with finite element operator-splitting procedures and make use of operator-splitting,characteristic method,calculus of variations,energy method,negative norm estimate,two kinds of test functions and the theory of prior estimates and techniques.Optimal order estimates in L^2 norm are derived for the error in the approximate solution.These methods have been successfully used in oil-gas resources estimation,enhanced oil recovery simulation and seawater intrusion numerical simulation.展开更多
Dielectric elastomer actuators (DEAs) are an emerging class of polymer actuation devices and have extensive application prospect in the field of robotics because of their light weight, high efficiency and large deform...Dielectric elastomer actuators (DEAs) are an emerging class of polymer actuation devices and have extensive application prospect in the field of robotics because of their light weight, high efficiency and large deformation. A cone DEA is manufactured and its working principle is analyzed. To obtain the deformation of elastomer and movement of DEA in advance, a finite element method (FEM) simulation is performed first. According to the working principle, two working equilibrium points of DEA, corresponding to the displacements of DEA with voltage off and on, are obtained and validated by experiments, thus work output in a workcycle is computed. Experiments show that the actuator can respond quickly when voltage is applied and can return to its original position rapidly when voltage is released. Simulation results agree well with experimental ones and the feasibility of DEA simulation is proved, and causes for the small difference between them in displacement output are analyzed. The performance of the actuator is improved from the aspects of both displacement and force output. A diamond four-bar linkage mechanism is used as the preload part and a displacement output of 17 mm is obtained. The force output of one actuating unit is about 1.77 N, so three actuating units are assembled in parallel and the force output is heightened to as high as 5.07 N.展开更多
基金Project(xjj20100078) supported by the Fundamental Research Funds for the Central Universities in China
文摘Several parameter identification methods of thermal response test were evaluated through numerical and experimental study.A three-dimensional finite-volume numerical model was established under the assumption that the soil thermal conductivity had been known in the simulation of thermal response test.The thermal response curve was firstly obtained through numerical calculation.Then,the accuracy of the numerical model was verified with measured data obtained through a thermal response test.Based on the numerical and experimental thermal response curves,the thermal conductivity of the soil was calculated by different parameter identification methods.The calculated results were compared with the assumed value and then the accuracy of these methods was evaluated.Furthermore,the effects of test time,variable data quality,borehole radius,initial ground temperature,and heat injection rate were analyzed.The results show that the method based on cylinder-source model has a low precision and the identified thermal conductivity decreases with an increase in borehole radius.For parameter estimation,the measuring accuracy of the initial temperature of the deep ground soil has greater effect on identified thermal conductivity.
基金Supported by the National High Technology Research and Development Programme of China (No. 2004AA421022)National Science Fund for Distinguished Young Scholars of P. R. China (No. 60525314)National Science & Technology Pillar Program in the Eleventh Five-year Plan ( No.2006BAI03A16)
文摘A surgical simulation and evaluation method in the anterior cruciate ligament(ACL)reconstructionwith image-free navigation was presented.Firstly,video tracking module,bone surface reconstructionmodule and virtual simulation module of this system were discussed.Secondly,the coordinate relations ofseveral surgery objects(including surgical instrument,anatomical,camera and screen)in the surgicalenvironment,the tracking based on MicronTracker with two cameras and the bone surface real-time recon-struction based on the Delaunay algorithm were introduced in detail.Finally,experiments of anisometrymeasurement and virtual simulation on two plastics were carried out to verify the validity of the proposedmethod.The anisometry value of reconstructed ACL was 8.970039mm.The effectiveness of ACL recon-struction has been proved by preliminary evaluation trials.
基金This research is supported by the Major State Research Program of China(Grant No.19990328),the National Natural Sciences Foundation of China(Grant Nos.19871051 and 19972039),the National Tackling Key Problems Program and the Doctorate Foundation of the S
文摘For the three-dimensional compressible multicomponent displacement problem we put forward the modified method of characteristics with finite element operator-splitting procedures and make use of operator-splitting,characteristic method,calculus of variations,energy method,negative norm estimate,two kinds of test functions and the theory of prior estimates and techniques.Optimal order estimates in L^2 norm are derived for the error in the approximate solution.These methods have been successfully used in oil-gas resources estimation,enhanced oil recovery simulation and seawater intrusion numerical simulation.
基金Project supported by the National Natural Science Foundation of China (No. 50605031)the Natural Science Foundation of Jiangsu Province (No. BK2008395), China
文摘Dielectric elastomer actuators (DEAs) are an emerging class of polymer actuation devices and have extensive application prospect in the field of robotics because of their light weight, high efficiency and large deformation. A cone DEA is manufactured and its working principle is analyzed. To obtain the deformation of elastomer and movement of DEA in advance, a finite element method (FEM) simulation is performed first. According to the working principle, two working equilibrium points of DEA, corresponding to the displacements of DEA with voltage off and on, are obtained and validated by experiments, thus work output in a workcycle is computed. Experiments show that the actuator can respond quickly when voltage is applied and can return to its original position rapidly when voltage is released. Simulation results agree well with experimental ones and the feasibility of DEA simulation is proved, and causes for the small difference between them in displacement output are analyzed. The performance of the actuator is improved from the aspects of both displacement and force output. A diamond four-bar linkage mechanism is used as the preload part and a displacement output of 17 mm is obtained. The force output of one actuating unit is about 1.77 N, so three actuating units are assembled in parallel and the force output is heightened to as high as 5.07 N.
