In order to predict the powder flow law of the injection molding process of MgTiO3 ceramic parts with complex structures,a constitutive model and numerical simulation method for MgTiO3 ceramic injection molding were e...In order to predict the powder flow law of the injection molding process of MgTiO3 ceramic parts with complex structures,a constitutive model and numerical simulation method for MgTiO3 ceramic injection molding were established based on the Hunt method.The material parameters of MgTiO3 such as elastic modulus,Poisson ratio,glass transition temperature,thermal conductivity and specific heat capacity were measured.Based on the fitting curve and the material parameters measured,the cross-WLF viscosity model and P-V-T model required for MgTiO3 ceramic injection molding were optimized.Furthermore,the influence of process parameters on mold filling flow and distribution of parts defects was researched.It was found that the gate position,injection speed and melt temperature have greater influence on mold filling flow and the packing process has an obvious effect on parts’defects.On this basis,the MgTiO3 ceramic parts injection molding experiment verification was carried out.By comparing the experimental results with the simulated results,it is found that the deformation error is within 1.5%and the density error is within 1%.Therefore,this research provided theoretical guidance for the engineering application of MgTiO3 ceramic parts fabricated by injection molding.展开更多
The creative talents are of constructive significance to the development of the country. Starting from the early exploration and the scientific definition of the creativity of the talents, this article summarizes the ...The creative talents are of constructive significance to the development of the country. Starting from the early exploration and the scientific definition of the creativity of the talents, this article summarizes the research achievements of the creativity of talents in China from three aspects of the determination of the nature and the research of the structural model, the research of the relationship between creativity and other factors, and the development and research of the cross cultural creativity. And from the perspective of the theory and the practice, the author puts forward the ways to cultivate the creativity of the talents from the five dimensions of optimizing the development of the brain functions, improving the abilities of the thinking, judgment and control, debugging the emotional stability and the creative personality, striving to improve the teachers＇ creativity, and drawing lessons from the practical experience of training innovative talents in western countries.展开更多
In this paper, the structured trajectory planning of lane change in collision-free road environment is studied and validated using the vehicle-driver integration data, and a new trajectory planning model for lane chan...In this paper, the structured trajectory planning of lane change in collision-free road environment is studied and validated using the vehicle-driver integration data, and a new trajectory planning model for lane change is proposed based on linear offset and sine function to balance driver comfort and vehicle dynamics. The trajectory curvature of the proposed model is continuous without mutation, and the zero-based curvature at the starting and end points during lane change assures the motion direction of end points in parallel with the lane line. The field experiment are designed to collect the vehicle-driver integration data, such as steering angle, brake pedal angel and accelerator pedal angel. The correction Correlation analysis of lane-changing maneuver and influencing variables is conducted to obtain the significant variables that can be used to calibrate and test the proposed model. The results demonstrate that vehicle velocity and Y-axis acceleration have significant effects on the lane-changing maneuver, so that the model recalibrated by the samples of different velocity ranges and Y-axis accelerations has better fitted performance compared with the model calibrated by the sample trajectory. In addition, the proposed model presents a decreasing tendency of the lane change trajectory fitted MAE with the increase of time span of calibrating samples at the starting stage.展开更多
Most previous studies have mainly focused on the analyses of one entire network(graph) or the giant connected components of networks. In this paper, we investigate the disconnected components(non-giant connected compo...Most previous studies have mainly focused on the analyses of one entire network(graph) or the giant connected components of networks. In this paper, we investigate the disconnected components(non-giant connected component) of some real social networks, and report some interesting discoveries about structural properties of disconnected components. We study three diverse, real networks and compute the significance profile of each component. We discover some similarities in the local structure between the giant connected component and disconnected components in diverse social networks. Then we discuss how to detect network attacks based on the local structure properties of networks. Furthermore, we propose an empirical generative model called i Friends to generate networks that follow our observed patterns.展开更多
基金Project(2018CFB439)supported by the Hubei Province Natural Science Foundation,China。
文摘In order to predict the powder flow law of the injection molding process of MgTiO3 ceramic parts with complex structures,a constitutive model and numerical simulation method for MgTiO3 ceramic injection molding were established based on the Hunt method.The material parameters of MgTiO3 such as elastic modulus,Poisson ratio,glass transition temperature,thermal conductivity and specific heat capacity were measured.Based on the fitting curve and the material parameters measured,the cross-WLF viscosity model and P-V-T model required for MgTiO3 ceramic injection molding were optimized.Furthermore,the influence of process parameters on mold filling flow and distribution of parts defects was researched.It was found that the gate position,injection speed and melt temperature have greater influence on mold filling flow and the packing process has an obvious effect on parts’defects.On this basis,the MgTiO3 ceramic parts injection molding experiment verification was carried out.By comparing the experimental results with the simulated results,it is found that the deformation error is within 1.5%and the density error is within 1%.Therefore,this research provided theoretical guidance for the engineering application of MgTiO3 ceramic parts fabricated by injection molding.
文摘The creative talents are of constructive significance to the development of the country. Starting from the early exploration and the scientific definition of the creativity of the talents, this article summarizes the research achievements of the creativity of talents in China from three aspects of the determination of the nature and the research of the structural model, the research of the relationship between creativity and other factors, and the development and research of the cross cultural creativity. And from the perspective of the theory and the practice, the author puts forward the ways to cultivate the creativity of the talents from the five dimensions of optimizing the development of the brain functions, improving the abilities of the thinking, judgment and control, debugging the emotional stability and the creative personality, striving to improve the teachers＇ creativity, and drawing lessons from the practical experience of training innovative talents in western countries.
基金supported by the National Natural Science Foundation of China(Grant No.61473028)the National Basic Research Program of China("973" Program)(Grant No.2012CB725403)the National High Technology Research and Development Program of China("863" Program)(Grant No.2015AA124103)
文摘In this paper, the structured trajectory planning of lane change in collision-free road environment is studied and validated using the vehicle-driver integration data, and a new trajectory planning model for lane change is proposed based on linear offset and sine function to balance driver comfort and vehicle dynamics. The trajectory curvature of the proposed model is continuous without mutation, and the zero-based curvature at the starting and end points during lane change assures the motion direction of end points in parallel with the lane line. The field experiment are designed to collect the vehicle-driver integration data, such as steering angle, brake pedal angel and accelerator pedal angel. The correction Correlation analysis of lane-changing maneuver and influencing variables is conducted to obtain the significant variables that can be used to calibrate and test the proposed model. The results demonstrate that vehicle velocity and Y-axis acceleration have significant effects on the lane-changing maneuver, so that the model recalibrated by the samples of different velocity ranges and Y-axis accelerations has better fitted performance compared with the model calibrated by the sample trajectory. In addition, the proposed model presents a decreasing tendency of the lane change trajectory fitted MAE with the increase of time span of calibrating samples at the starting stage.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61572060, 61190125, 61472024)CERNET Innovation Project 2015 (Grant No. NGII20151004)
文摘Most previous studies have mainly focused on the analyses of one entire network(graph) or the giant connected components of networks. In this paper, we investigate the disconnected components(non-giant connected component) of some real social networks, and report some interesting discoveries about structural properties of disconnected components. We study three diverse, real networks and compute the significance profile of each component. We discover some similarities in the local structure between the giant connected component and disconnected components in diverse social networks. Then we discuss how to detect network attacks based on the local structure properties of networks. Furthermore, we propose an empirical generative model called i Friends to generate networks that follow our observed patterns.
