讲座一

Nonlinear dynamics of a conducting rod in a magnetic field: with applications to electrodynamic space tethers

时 间

9月16日（星期五）上午9：00～11：00

地 点

威廉希尔足球网第三会议室（西2楼西2层）

讲座人

Gert van der Heijden教授，数学博士

讲座一

内 容

简 介

The lecture will focus on three aspects of stability of rods in magnetic fields inspired by electrodynamic space tethers, i.e., conducting cables connecting satellites or other space objects and propelled by the earth's magnetic field. The first is the magnetically-induced buckling of a whirling conducting rod in a uniform magnetic field, leading to coiled solutions. The second is the localization of long rods in a uniform magnetic field. It turns out that while the equations for an inextensible rod are integrable and therefore (in principle) solvable in closed form, the equations for an extensible rod are nonintegrable, leading to multi-pulse localization and spatial chaos. The third problem is that of a short rigid tether moving in the earth's magnetic field. Orbits of these tethers are unstable (if we assume constant current through the tether) and we apply a time-delay feedback control scheme to stabilize tether motion. Early results show mixed success in stabilization of tether orbits, with only the simplest periodic orbits allowing for stabilization.

讲座二

Applied Mechanics: some applications of the Euler-Lagrange equations of analytical mechanics.

时 间

9月19日(星期一) 上午9：00～11：00

地 点

威廉希尔足球网第三会议室（西2楼西2层）

讲座人

Gert van der Heijden教授，数学博士

讲座人简介

Centre for Nonlinear Dynamics and its Applications

Department of Civil, Environmental and Geomatic Engineering

UniversityCollege London

Gert van der Heijden 教授1994年在荷兰乌德勒支大学（UtrechtUniversity）获得数学博士学位，后在伦敦大学学院（University College London）进行了长期的非线性力学和数学方面的研究工作。2008年成为该校的Reader，2010年任教授。

Gert van der Heijden教授主要从事柔性细长结构在约束条件下的几何精确描述和分析，他和同事Eugene Starostin关于莫比乌斯带空间结构的研究，解开了这一长达75年的难题，相关论文在2007年7月15日在线发表于《自然—材料学》（Nature Materials）上，获得学界赞誉。其主要研究方向包括：

u Nonlinear mechanics of slender elastic structures, both 1D (rods, strings) and 2D (strips, ribbons). Applications both in engineering and in biology.

u Constrained variational calculus, conjugate point theory, variational inequalities, non-smooth mechanical systems

u Hamiltonian mechanics, integrability, Melnikov theory

u Computational (numerical as well as analytical) dynamical systems: normal forms, (homoclinic) bifurcations

u Numerical continuation and bifurcation analysis, computer software

u Nonlinear rotordynamics, coupled oscillators, chaotic dynamics

欢迎广大师生届时听讲座，研究生计学分。

威廉希尔足球网

2011-9-14