LIE SYMMETRIES AND CONSERVED QUANTITY OF A BIPED ROBOT

I. INTRODUCTION It is well known there are close relationships between the symmetries and conservation laws inmechanical systems. The symmetric principles are among the key issues in mechanics. Two e?ectivemethods of studying the symmetries and conservation laws of mechanical are Noether’s method[1] andLie’s method. The approach to Lie symmetries was reported in the 19th century, but no applicationin mechanics appeared until 1979[2]. In recent years, studies of Lie’s method have be…     

A unified symmetry of lagrangian systems

In this paper, the definition and the criterion of a unified symmetry are presented. A new conserved quantity, as well as the Noether conserved quantity and the Hojman conserved quantity, deduced from the unified symmetry, are obtained. Some examples are given to illustrate the application of the results. The project supported by the National Natural Science Foundation of China (10272021)     

非保守力学系统的Lie对称性和守恒量

本文讨论非保守力学系统的Ｌｉｅ对称性，给出由Ｌｉｅ对称性得到力学系统守恒量的条件，并给出了说明性的例子，在文章最后，还说明对于非保守系统，它的Ｎｏｅｔｈｅｒ对称性并不一定是其自身的Ｌｉｅ对称性。     

Birkhoff系统的一般Lie对称性和非Noether守恒量

研究Birkhoff系统的一般Lie对称性导致的非Noether守恒量。得到非Noether守恒量的存在定理,举例说明结果的应用。     

Hamilton系统的一类新型守恒律

研究Hamilton系统的Lie对称性与守恒律。根据微分方程在无限小群变换下的不变性理论，建立了Hamilton系统仅依赖于正则变量的无限小群变换的Lie对称变换，给出了Lie对称性的确定方程，并直接由系统的Lie对称性得到了系统的一类新型定恒律。文末，举例说明结果的应用。     

基于DISLab电容充电法速度的测量

将物体通过一小段距离的时间,转换成用此过程对电容两端的充电电压来描述,而电容的充电电压可用DISLab电压传感器采集,再经反相推导,把电压量转换成时间量.根据v=s/t,即可测量物体的速度.实验表明,这种电容充电法测得的速度与传统光电门法所测的速度相一致.     

The conserved Penrose-Fife system with temperature-dependent memory

A nonlinear parabolic system of Penrose-Fife type with a singular evolution term, arising from modelling dynamic phenomena of the nonisothermal diffusive phase separation, is studied. Here, we consider the evolution of a material in which the heat flux is a superposition of two different contributions: one part is proportional to the spacial gradient of the inverse of the absolute temperature ?, while the other agrees with the Gurtin-Pipkin law, introduced in the theory of materials with thermal memory. The phase transition here is described through the evolution of the conserved order parameter χ, which may represent the density or concentration of some substance. It is shown that an initial-boundary value problem for the resulting state equations has a unique solution.     

准坐标下广义非保守系统Lagrange方程的积分因子与守恒定理

用积分因子方法研究准坐标下广义非保守系统Lagrange方程的守恒定理.列写系统的运动微分方程，给出它的积分因子的定义.研究守恒量存在的必要条件.建立系统的守恒定理及其逆定理，并举例说明结果的应用. 关键词： 准坐标 Lagrange方程 积分因子 守恒量     

关于区间估计和假设检验的一点注记

给出了当枢轴量和检验统计量的分布密度为单调函数时,寻找最优置信区间方法,并说明了在此条件下进行假设检验选择单侧拒绝域的合理性。     

Non-Noether Conserved Quantity of Nonholonomic System Having Variable Mass and Unilateral Constraints

Using the Lie Symmetry under infinitesimal transformations in which the time is not variable, the nonNoether conserved quantity of nonholonomic system having variable mass and unilateral constraints is studied. The differential equations of motion of the system are given. The determining equations of Lie symmetrical transformations of the system under infinitesimal transformations are constructed. The Hojman‘s conservation theorem of the system is established. Finally, we give an example to illustrate the application of the result.