变质量非完整系统的哈密顿原理

本文将哈密顿原理推广到最一般的,变质量非完整系统,得出变质量非完整系统的哈密顿原理,并给出了实例.     

非线性非完整系统Vacco动力学方程的积分方法*

本文给出积分非线性非完整系统Vacco动力学方程的积分方法.首先,将Vacco动力学方程表示为正则形式和场方程形式;然后,分别用梯度法,单分量法和场方法积分相应完整系统的动力学方程,并加上非完整约束对初条件的限制而得到非线性非完整系统Vacco动力学方程的解.     

变质量非线性非完整系统相对运动动力学方程的积分方法

本文给出积分变质量非线性非完整系统相对于非惯性系动力学方程的梯度法,单分量法和场方法。首先,将这类问题的动力学方程表示为正则形式和场方程形式;然后,分别用梯度法,单分量法和场方法积分相应常质量完整系统相对于惯性系的动力学方程,并加上非完整约束对初始条件的限制而得到变质量非线性非完整系统相对于非惯性系动力学方程的解。     

变质量非线性非完整系统的Gibbs-Appell方程

本文首先将Gibbs-Appell方程推广到最一般的变质量非完整系统.得到变质量非线性非完整系统在广义坐标、准坐标下的Gibbs-Appell方程和积分变分原理,最后给出一个例子.     

非线性约束下非完整系统的平衡稳定性

Kozlov将Liapunov第一方法推广到非线性力学系统,用来解决保守和耗散力场中,运动力学系统平衡位置的不稳定性.文中讨论的系统运动限于理想的非线性非完整约束.将势能和约束函数展开为Maclaurin级数,对其第一非平凡多项式的阶,确定了相互间关系的5种情况,并对生成的非线性非完整约束方程进行了分析.将3种线性齐次约束下的非完整系统平衡位置的不稳定定理(Kozlov,1986),推广到非线性非完整约束.另外两种情况下的新定理,也是将Kozlov(1994)的结果,拓展到非线性约束下的非完整系统.     

变质量非线性非完整系统的相对运动动力学方程的积分方法

本给出积分变质量非线性百在完整系统相对于非惯性系动力学方程的梯度法，单分量法和场方法。     

一类非线性哈密顿系统的周期解

结合Maslov指标理论,利用环绕定理证明了一类非线性哈密顿系统的周期解的存在性,而这类哈密顿系统所对应的作用泛函可能不满足Palais-Smale条件.     

Mac-Millan方程对非线性非完整力学系统的推广

本文首先将Mac-Millan方程推广到最一般的非完整力学系统,得到非线性非完整系统的广义Mac-Millan方程.其次,证明广义Mac-Millan方程与广义Чаплыгин方程的等价性,最后给出一个例子.     

非线性非完整系统相对于非惯性系动力学的积分理论*

本文建立非线性非完整系统相对于非惯性系动力学的积分理论.首先,由这种相对运动的Routh方程给出系统的第一积分;其次,分别利用系统的循环积分、能量积分降阶运动方程,得到推广的Routh方程和推广的Whittaker方程;再次,建立这类系统运动的正则方程和变分方程,并由第一积分构造系统的积分不变量;然后,给出系统的Poincare-Cartan型积分变量关系和积分不变量.最后,给出一系列推论.     

导出非线性非完整系统Mac-Millan方程的一种途径

只要由Jourdain微分变分原理就能导出一阶非线性非完整系统的Mac-Millan方程,无需引入虚位移的牛青萍定义。后一定义只是本方法的自然推论。     

Energy-Preserving Integrators Applied to Nonholonomic Systems

We introduce energy-preserving integrators for nonholonomic mechanical systems. We will see that the nonholonomic dynamics is completely determined by a triple \(({{\mathcal {D}}}^*, \varPi , \mathcal {H})\), where \({{\mathcal {D}}}^*\) is the dual of the vector bundle determined by the nonholonomic constraints, \(\varPi \) is an almost-Poisson bracket (the nonholonomic bracket) and \( \mathcal {H}: {{\mathcal {D}}}^*\rightarrow \mathbb {R}\) is a Hamiltonian function. For this triple, we can apply energy-preserving integrators, in particular, we show that discrete gradients can be used in the numerical integration of nonholonomic dynamics. By construction, we achieve preservation of the constraints and of the energy of the nonholonomic system. Moreover, to facilitate their applicability to complex systems which cannot be easily transformed into the aforementioned almost-Poisson form, we rewrite our integrators using just the initial information of the nonholonomic system. The derived procedures are tested on several examples: a chaotic quartic nonholonomic mechanical system, the Chaplygin sleigh system, the Suslov problem and a continuous gearbox driven by an asymmetric pendulum. Their performance is compared with other standard methods in nonholonomic dynamics, and their merits verified in practice.

     

Integrators for Nonholonomic Mechanical Systems

We study a discrete analog of the Lagrange-d'Alembert principle of nonhonolomic mechanics and give conditions for it to define a map and to be reversible. In specific cases it can generate linearly implicit, semi-implicit, or implicit numerical integrators for nonholonomic systems which, in several examples, exhibit superior preservation of the dynamics. We also study discrete nonholonomic systems on Lie groups and their reduction theory, and explore the properties of the exact discrete flow of a nonholonomic system.     

Constraint Control of Nonholonomic Mechanical Systems

We derive an optimal control formulation for a nonholonomic mechanical system using the nonholonomic constraint itself as the control. We focus on Suslov’s problem, which is defined as the motion of a rigid body with a vanishing projection of the body frame angular velocity on a given direction \(\varvec{\xi }\). We derive the optimal control formulation, first for an arbitrary group, and then in the classical realization of Suslov’s problem for the rotation group \(\textit{SO}(3)\). We show that it is possible to control the system using the constraint \(\varvec{\xi }(t)\) and demonstrate numerical examples in which the system tracks quite complex trajectories such as a spiral.     

一类非线性方程组的求解

对于一个给定的非线性方程组,通过一系列的变化,可以将其构造成一个函数,从而把非线性方程组的求解问题转换为求函数极小值问题.通过利用正交表的数据分析方法,给出了求函数极小值进而求解非线性方程组的方法,这种方法得到的解比已有的更精确,且大大缩减了复杂方程组的计算量,用时少,不需要初始值.最后,采用Matlab软件,验证了其可行性和有效性.     

Homogenization of Monotone Systems of Non-Coercive Hamilton-Jacobi Equations

In this article, we study homogenization for a class of monotone systems of first-order timedependent Hamilton-Jacobi equations in the case of non-coercive Hamiltonians. And we prove the uniform convergence of the solution of oscillating systems to the solution of the homogenized systems.     

积分非完整可控力学系统运动方程的场方法

本文将场方法推广应用于积分非完整可控力学系统的运动方程,并举例说明方法的应用.