线性三相对称负载Y联接时中线电流不为零的现象分析

分析了线性三相对称负载Y联接在对称三相四线制电源时，中线电流不为零的原因，并给出了解决的方法．     

两种均匀磁介质分界面上有长载流导线的场和电流分布

分析两种均匀磁介质分界面上有长载流导线的场和电流分布，指出磁感应强度B=B(r)φ径向对称分布是由径向对称分布的总电流j=j(r)ez(包括传导电流和磁化电流)所激发,探讨了传导电流的分布与磁感应强度B、磁场强度H和磁化电流的分布的关系。     

相空间中力学系统的两类Mei对称性及守恒量

研究相空间中力学系统的两类Mei对称性及守恒量，给出相空间中力学系统的两类Mei对称性的定义，得到其确定方程及守恒量，并举例说明结果的应用. 关键词： 相空间 力学系统 Mei对称性 守恒量     

两半无限长圆柱形导体管内电位的计算与分析

分别运用分离变量法和有限差分法计算和分析两半无限长圆柱形导体管内电位的解析解和数值解,并通过MAT LAB编程算出其场域中一些点的电位结果,由相对误差的比较说明数值解的有效性,以此对保角变换的解析解结果进行了验证,找到缺陷并作了修正,从而说明把数值计算与求解析解综合起来分析场域内的电位分布会使结果更加可靠和准确.     

Lie symmetry and Mei symmetry of a rotational relativistic system in phase space

The Lie symmetry and the Mei symmetry of a rotational relativistic system in phase space are studied. The definition, criterion and conserved quantity of the Lie symmetry and the Mei symmetry of a rotational relativistic system in phase space are given. The relation between the Lie symmetry and the Mei symmetry is found. An example is given to illustrate the application of the result.     

Synchronisation and general dynamic symmetry of a vibrating system with two exciters rotating in opposite directions

We derive the non-dimensional coupling equation of two exciters, including inertia coupling, stiffness coupling and load coupling. The concept of general dynamic symmetry is proposed to physically explain the synchronisation of the two exciters, which stems from the load coupling that produces the torque of general dynamic symmetry to force the phase difference between the two exciters close to the angle of general dynamic symmetry. The condition of implementing synchronisation is that the torque of general dynamic symmetry is greater than the asymmetric torque of the two motors. A general Lyapunov function is constructed to derive the stability condition of synchronisation that the non-dimensional inertia coupling matrix is positive definite and all its elements are positive. Numeric results show that the structure of the vibrating system can guarantee the stability of synchronisation of the two exciters, and that the greater the distances between the installation positions of the two exciters and the mass centre of the vibrating system are, the stronger the ability of general dynamic symmetry is.     

Noether——Lie symmetry and conserved quantities of mechanical system in phase space

In this paper, a new kind of symmetry and its conserved quantities of a mechanical system in phase space are studied. The definition of this new symmetry, i.e. a Noether--Lie symmetry, is presented, and the criterion of this symmetry is also given. The Noether conserved quantity and the generalized Hojman conserved quantity of the Noether--Lie symmetry of the system are obtained. The Noether--Lie symmetry contains the Noether symmetry and the Lie symmetry, and has more generalized significance.     

Unified Symmetry and Conserved Quantities of Mechanical System in Phase Space

In this paper, a new symmetry and its conserved quantities of a mechanical system in phase space are studied. The defition of this new symmetry, i.e., a unified one is presented, and the criterion of this symmetry is also given. The Noether, the generalized Hojman and the Mei conserved quantities of the unified symmetry of the system are obtained. The unified symmetry contains the Noether, the Lie and the Mei symmetries, and has more generalized significance.     

相空间中离散完整系统的Noether对称性和Mei对称性

研究相空间中离散完整系统的Noether对称性、Mei对称性及其导致的守恒量.利用差分离散变分方法,给出相空间中离散完整系统的差分离散变分原理,建立系统的离散正则方程和能量演化方程;给出系统Noether对称性和Mei对称性的判定条件,得到系统离散形式的Noether守恒量和Mei守恒量及其存在的条件.举例说明结果的应用. 关键词： 相空间 离散完整系统 对称性 守恒量     

夫兰克-赫兹演示实验中工频的相位干扰分析与消除

充氩管夫兰克-赫兹实验装置的示波器显示图像不稳定,其原因是夫兰克-赫兹管输出电流太小,受到环境中的工频电磁波的污染,以及能谱信号受到了噪声相位的干扰.从噪声中提取扫描触发信号,用来同步夫兰克-赫兹管的扫描信号,可以完全消除噪声相位的干扰.本文给出了不稳定图像的数学模型、解决方案及仿真结果.