针对Watt型平面六连杆机构解域分析问题,提出了基于欧拉公式和判别法的平面四环链和平面六环链的奇异点识别方法,并结合平面四环链和平面六环链的运动特征,对Watt型平面六连杆机构进行了分支自动识别研究。首先,基于提出的识别方法并结...针对Watt型平面六连杆机构解域分析问题,提出了基于欧拉公式和判别法的平面四环链和平面六环链的奇异点识别方法,并结合平面四环链和平面六环链的运动特征,对Watt型平面六连杆机构进行了分支自动识别研究。首先,基于提出的识别方法并结合MFC(microsoft foundation classes,微软基础类库)设计了计算机辅助识别软件,实现对Watt型平面六连杆机构的分支、构型位置以及奇异点坐标的自动识别。然后,基于识别结果分析Watt型平面六连杆机构的可行域,再根据Watt型平面六连杆机构的可行域生成机构的运动仿真视频,并通过仿真视频分析其运动学特性。最后,结合实例演示Watt型平面六连杆机构分支的自动识别过程。结果显示该计算机辅助识别软件能够对该机构分支进行自动判别。研究结果表明利用所提出的Watt型平面六连杆机构分支自动识别方法可简便快捷地实现对机构的可行域分析和运动学分析,具有较强的工程实用性。展开更多
We study the evolutionary snowdrift game in a heterogeneous Newman-Watts small-world network. The heterogeneity of the network is controlled by the number of hubs. It is found that the moderate heterogeneity of the ne...We study the evolutionary snowdrift game in a heterogeneous Newman-Watts small-world network. The heterogeneity of the network is controlled by the number of hubs. It is found that the moderate heterogeneity of the network can promote the cooperation best. Besides, we study how the hubs affect the evolution of cooperative behaviours of the heterogeneous Newman-Watts small-world network. Simulation results show that both the initial states of hubs and the connections between hubs can play an important role. Our work gives a further insight into the effect of hubs on the heterogeneous networks.展开更多
The Planck constant h is one of the most significant constants in quantum physics. Recently, the precision measurement of the value of h has been a hot issue due to its important role for the establishment of both a n...The Planck constant h is one of the most significant constants in quantum physics. Recently, the precision measurement of the value of h has been a hot issue due to its important role for the establishment of both a new SI and a revised fundamental physical constant system. Up to date, two approaches, the watt balance and counting atoms, have been employed to determine the Planck constant at a level of several parts in 108. In this paper, the principle and progress on precision measurement of the Planck constant using watt balance and counting atoms at national metrology institutes are reviewed. Further improvement in determining the Planck constant and possible developments of a revised physical constant system in future are discussed.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
文摘针对Watt型平面六连杆机构解域分析问题,提出了基于欧拉公式和判别法的平面四环链和平面六环链的奇异点识别方法,并结合平面四环链和平面六环链的运动特征,对Watt型平面六连杆机构进行了分支自动识别研究。首先,基于提出的识别方法并结合MFC(microsoft foundation classes,微软基础类库)设计了计算机辅助识别软件,实现对Watt型平面六连杆机构的分支、构型位置以及奇异点坐标的自动识别。然后,基于识别结果分析Watt型平面六连杆机构的可行域,再根据Watt型平面六连杆机构的可行域生成机构的运动仿真视频,并通过仿真视频分析其运动学特性。最后,结合实例演示Watt型平面六连杆机构分支的自动识别过程。结果显示该计算机辅助识别软件能够对该机构分支进行自动判别。研究结果表明利用所提出的Watt型平面六连杆机构分支自动识别方法可简便快捷地实现对机构的可行域分析和运动学分析,具有较强的工程实用性。
基金supported by the National Basic Research Program of China (No 2006CB705500)the National Natural Science Foundation of China (Grant Nos 60744003, 10635040, 10532060 and 10472116)the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘We study the evolutionary snowdrift game in a heterogeneous Newman-Watts small-world network. The heterogeneity of the network is controlled by the number of hubs. It is found that the moderate heterogeneity of the network can promote the cooperation best. Besides, we study how the hubs affect the evolution of cooperative behaviours of the heterogeneous Newman-Watts small-world network. Simulation results show that both the initial states of hubs and the connections between hubs can play an important role. Our work gives a further insight into the effect of hubs on the heterogeneous networks.
基金Project supported by the National Natural Science Foundation of China(Grant No.51477160)the National Department Public Benefit Research Foundation of China(Grant No.201010010)the National Key Technology R&D Program of China(Grant No.2006BAF06B01)
文摘The Planck constant h is one of the most significant constants in quantum physics. Recently, the precision measurement of the value of h has been a hot issue due to its important role for the establishment of both a new SI and a revised fundamental physical constant system. Up to date, two approaches, the watt balance and counting atoms, have been employed to determine the Planck constant at a level of several parts in 108. In this paper, the principle and progress on precision measurement of the Planck constant using watt balance and counting atoms at national metrology institutes are reviewed. Further improvement in determining the Planck constant and possible developments of a revised physical constant system in future are discussed.
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.
