介绍一种使用 G- M制冷机实现深冷环境的高温超导磁悬浮测试系统。高温超导体块材YBa Cu O被固定在制冷机冷头上 ,其温度通过温度控制器可以控制在 1 0 0 K到 40 K范围内。永久磁体 Nd Fe B固定在位于 YBa Cu O上方高温超导磁悬浮测试...介绍一种使用 G- M制冷机实现深冷环境的高温超导磁悬浮测试系统。高温超导体块材YBa Cu O被固定在制冷机冷头上 ,其温度通过温度控制器可以控制在 1 0 0 K到 40 K范围内。永久磁体 Nd Fe B固定在位于 YBa Cu O上方高温超导磁悬浮测试系统的垂直运动部件上 ,并在计算机控制下作垂直运动以改变它与 YBa Cu O之间的距离。同时 ,计算机采集数据得到 YBa Cu O与 Nd Fe B之间悬浮力与距离的关系。通过温度设定 ,可得到 YBa Cu O在不同温度下的悬浮性能。展开更多
The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic f...The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent.展开更多
文摘介绍一种使用 G- M制冷机实现深冷环境的高温超导磁悬浮测试系统。高温超导体块材YBa Cu O被固定在制冷机冷头上 ,其温度通过温度控制器可以控制在 1 0 0 K到 40 K范围内。永久磁体 Nd Fe B固定在位于 YBa Cu O上方高温超导磁悬浮测试系统的垂直运动部件上 ,并在计算机控制下作垂直运动以改变它与 YBa Cu O之间的距离。同时 ,计算机采集数据得到 YBa Cu O与 Nd Fe B之间悬浮力与距离的关系。通过温度设定 ,可得到 YBa Cu O在不同温度下的悬浮性能。
基金Project(2007CB707706) supported by the Major State Basic Research Development Program of ChinaProjects(2007E213,2007E203) supported by the Natural Science Foundation of Shaanxi Province,China
文摘The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent.
