匀强磁场产生装置的设计

阐述了亥姆霍兹线圈轴线上磁感应强度高阶导数的奇特性质,提出利用共轴四线圈组产生均匀磁场的设想,并通过模拟共轴四线圈组磁场的轴线分布及空间分布,展现了共轴四线圈组的优越之处.     

氟橡胶O型圈低压气体密封黏滞摩擦特性实验

开展了低气体密封压力条件下的氟橡胶O型圈低压黏滞摩擦特性实验研究.对氟橡胶O型圈与不锈钢2Cr13摩擦副的摩擦力的时变曲线进行测量,重点分析了密封压力、O型圈压缩率和滑动速度对O型圈黏滞摩擦力的影响规律.结果表明:随压缩率的增加,氟橡胶O型圈摩擦力增加,并呈现出明显的回弹特征,即滞后摩擦力增加且释放时间增加;随着密封压力的增加,其所受最大静摩擦力、滑动摩擦力与滞后摩擦力均呈现非线性变化,且存在一极大值;减小往复运动速度,摩擦力数值增大,但摩擦力极值对应的密封压力值变小.     

Lie symmetries and conserved quantities of discrete nonholonomic Hamiltonian systems

This paper focuses on studying Lie symmetries and conserved quantities of discrete nonholonomic Hamiltonian systems. Firstly, the discrete generalized Hamiltonian canonical equations and discrete energy equation of nonholonomic Hamiltonian systems are derived from discrete Hamiltonian action. Secondly, the determining equations and structure equation of Lie symmetry of the system are obtained. Thirdly, the Lie theorems and the conservation quantities are given for the discrete nonholonomic Hamiltonian systems. Finally, an example is discussed to illustrate the application of the results.     

Ore度和条件下赋权triangle-free图中的重圈(英文)

设G是一个2-连通赋权图,且G中每一对不相邻顶点u和v都满足d~w(u)+d~w(v)≥2d.Bondy等人证明了G或者包含一个哈密尔顿圈,或者包含一个权至少为2d的圈.如果G不是哈密尔顿图,这个结论意味着G中包含一个权至少为2d的圈.但是当G是哈密尔顿图时,我们不能判断G是否包含一个权至少为2d的圈.这篇文章中,在Fujisawa的一篇文章的启发下,我们证明了当G是triangle-free图并且|V(G)|是奇数时,G中一定包含一个权至少为2d的圈,即使G是哈密尔顿图.     

传动装置密封环摩擦磨损性能研究

为分析车辆传动装置密封环在高速高压工作环境下的磨损失效,利用自主研制的试验台研究了速度、接触压力和介质油温对密封摩擦副摩擦磨损特性的影响;利用扫描电子显微镜观察了磨损程度不同的密封环端面的表面形貌,并探讨了其磨损机理.结果表明,在设定的试验条件下,密封摩擦副的摩擦系数随着压力的增大和转速的升高先急剧减小再降幅减缓后趋于稳定,而压力对摩擦状态的影响要比转速显著.密封环端面温度与摩擦状态之间存在相互影响的特征.密封介质性质同样影响着密封环的摩擦状态.在稳定磨损阶段,密封环的磨损机理以磨粒和黏着磨损为主导,当进入到剧烈磨损期后,磨粒磨损和疲劳磨损的影响更为突出.     

关于线图上的等距图和次泛圈

给定一个图Ｇ,且满足min{d(u) d(v):u,v∈Ｅ（Ｇ）}≥８。有下结论：若Ｃ是Ｇ中的圈且满足dc(u,v)=d(u,v),任意{u,v}包含于Ｖ（Ｃ）。当任一这样的圈Ｃ的长度不超过△（Ｇ）＋１时,线圈Ｌ（Ｇ）是次泛圈的且所给的条件都是最好可能的。     

一类混合Ramsey数

设a(G)表示图G的点荫度,m为正整数,H为连通图,混合Ramsey数v(a;m;H)被定义的为最小的正整数P,使得对任意P阶图G则有a(G)≥m或者H包括于G^-。本文给出了v(a;m;H)的一种计算方法,并对图Cn和轮Wn确定了v(a;n;Cn)和v(a;m;Wn)的值。     

带弦有向圈的2级合成

考察带一条弦的有向圈的2级合成图,得到了它们强连通的充要条件,这些结果被用于判定布尔矩阵组合合成的本原性。     

On the linearization of the coupled Harry－Dym soliton hierarchy

This paper is devoted to the study of the underlying linearities of the coupled Harry--Dym (cHD) soliton hierarchy, including the well-known cHD equation. Resorting to the nonlinearization of Lax pairs, a family of finite-dimensional Hamiltonian systems associated with soliton equations are presented, constituting the decomposition of the cHD soliton hierarchy. After suitably introducing the Abel--Jacobi coordinates on a Riemann surface, the cHD soliton hierarchy can be ultimately reduced to linear superpositions, expressed by the Abel--Jacobi variables.     

Discrete integrable system and its integrable coupling

This paper derives new discrete integrable system based on discrete isospectral problem. It shows that the hierarchy is completely integrable in the Liouville sense and possesses bi-Hamiltonian structure. Finally, integrable couplings of the obtained system is given by means of semi-direct sums of Lie algebras.