中国物理B ›› 2017, Vol. 26 ›› Issue (8): 84501-084501.doi: 10.1088/1674-1056/26/8/084501

• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇    下一篇

Noether symmetry and conserved quantity for dynamical system with non-standard Lagrangians on time scales

Jing Song(宋静), Yi Zhang(张毅)   

  1. 1 College of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009, China;
    2 College of Civil Engineering, Suzhou University of Science and Technology, Suzhou 215011, China
  • 收稿日期:2017-02-28 修回日期:2017-04-10 出版日期:2017-08-05 发布日期:2017-08-05
  • 通讯作者: Yi Zhang E-mail:zhy@mail.usts.edu.cn
  • 基金资助:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 11572212 and 11272227) and the Innovation Program of Suzhou University of Science and Technology, China (Grant No. SKYCX16_012).

Noether symmetry and conserved quantity for dynamical system with non-standard Lagrangians on time scales

Jing Song(宋静)1, Yi Zhang(张毅)2   

  1. 1 College of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009, China;
    2 College of Civil Engineering, Suzhou University of Science and Technology, Suzhou 215011, China
  • Received:2017-02-28 Revised:2017-04-10 Online:2017-08-05 Published:2017-08-05
  • Contact: Yi Zhang E-mail:zhy@mail.usts.edu.cn
  • About author:0.1088/1674-1056/26/8/
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 11572212 and 11272227) and the Innovation Program of Suzhou University of Science and Technology, China (Grant No. SKYCX16_012).

摘要:

This paper focuses on studying the Noether symmetry and the conserved quantity with non-standard Lagrangians, namely exponential Lagrangians and power-law Lagrangians on time scales. Firstly, for each case, the Hamilton principle based on the action with non-standard Lagrangians on time scales is established, with which the corresponding Euler-Lagrange equation is given. Secondly, according to the invariance of the Hamilton action under the infinitesimal transformation, the Noether theorem for the dynamical system with non-standard Lagrangians on time scales is established. The proof of the theorem consists of two steps. First, it is proved under the infinitesimal transformations of a special one-parameter group without transforming time. Second, utilizing the technique of time-re-parameterization, the Noether theorem in a general form is obtained. The Noether-type conserved quantities with non-standard Lagrangians in both classical and discrete cases are given. Finally, an example in Friedmann-Robertson-Walker spacetime and an example about second order Duffing equation are given to illustrate the application of the results.

关键词: time scale, non-standard Lagrangian, Noether symmetry, conserved quantity

Abstract:

This paper focuses on studying the Noether symmetry and the conserved quantity with non-standard Lagrangians, namely exponential Lagrangians and power-law Lagrangians on time scales. Firstly, for each case, the Hamilton principle based on the action with non-standard Lagrangians on time scales is established, with which the corresponding Euler-Lagrange equation is given. Secondly, according to the invariance of the Hamilton action under the infinitesimal transformation, the Noether theorem for the dynamical system with non-standard Lagrangians on time scales is established. The proof of the theorem consists of two steps. First, it is proved under the infinitesimal transformations of a special one-parameter group without transforming time. Second, utilizing the technique of time-re-parameterization, the Noether theorem in a general form is obtained. The Noether-type conserved quantities with non-standard Lagrangians in both classical and discrete cases are given. Finally, an example in Friedmann-Robertson-Walker spacetime and an example about second order Duffing equation are given to illustrate the application of the results.

Key words: time scale, non-standard Lagrangian, Noether symmetry, conserved quantity

中图分类号:  (Lagrangian and Hamiltonian mechanics)

  • 45.20.Jj
11.30.Na (Nonlinear and dynamical symmetries (spectrum-generating symmetries)) 45.10.Db (Variational and optimization methods)