New Type of Conserved Quantities of Lie Symmetry for Nonholonomic Mechanical Systems in Phase Space

The new types of conserved quantities, which are directly induced by Lie symmetry of nonholonomie mechanical systems in phase space, are studied. Firstly, the criterion of the weak Lie symmetry and the strong Lie symmetry are given. Secondly, the conditions of existence of the new type of conserved quantities induced by the weak Lie symmetry and the strong Lie symmetry directly are obtained, and their form is presented. Finaily, an Appell-Hamel example is discussed to further illustrate the applications of the results.     

CURRENT TRENDS OF MICRO-AND NANOMECHANICS

Introduction Scaling down to the micro- and nanoscale is a strong current trend in the development of science and technology. ＇Small is energy efficient and cost effective＇ has long been for the motto of the semiconductor industry, including micro- and nanoelectronics, micro-electro-mechanical systems （MEMS） and nanoelectro-mechanical systems （NEMS）.     

同步辐射讲座第五讲微电子机械系统加工新方法--LIGA技术

简述了微电子机械系统的起源和特点，介绍了LIGA技术的基本原理以及一些相关技术，对同步辐射深度光刻的技术要求进行了详细地说明，并介绍了国内外利用LIGA技术进行微电子机械系统研发的现状。     

Conformal invariance and Hojman conservedquantities of first order Lagrange systems

In this paper the conformal invariance by infinitesimal transformations of first order Lagrange systems is discussed in detail. The necessary and sufficient conditions of conformal invariance and Lie symmetry simultaneously by the action of infinitesimal transformations are given. Then it gets the Hojman conserved quantities of conformal invariance by the infinitesimal transformations. Finally an example is given to illustrate the application of the results.     

封面故事

一种新型智能液体微型镜头 人类的眼睛尽管很简洁，但能够通过调整透镜的形状很轻松地聚焦在不同的距离。而传统的人造光学系统则通过改变透镜的位置实现聚焦。现在，研究人员研制出了一种新型智能液体微型镜头，它与目前的大多数镜头的不同之处在于，不再使用复杂的机械系统，而且能自对焦。这种镜头的关键部件是一种能对刺激产生响应的水系统中，充当一个液滴的容器。该水溶胶同时探测刺激和促使液滴形状发生变化，从而也使焦距发生变化。刺激包括生物和化学试剂以及物理参数。在这种微米尺度上，固定的液一液界面被用来获得稳定的装置，从而实现10秒到几十秒的响应时间。这样的镜头可以具有几乎任意长度的焦距，并且可以方便地集成进阵列中。本期封面所示为一种智能液体微型镜头，在其中，一种水溶胶（图中带斑纹的环）根据一个局部刺激调控镜头形状。     

用一个线阵CCD检测刚体瞬态平面运动的研究

介绍高速外触发式远距离驱动线阵ＣＣＤ传感器及其数据采集系统,利用该套系统测试刚体的瞬态平面运动,获得了被测刚体的角位移、角速度及其特定点的位置、角速度。测试结果与其他方法的测试结果比较,比较吻合。     

Algebraic structure and Poisson＇s theory of mechanico-electrical systems

The algebraic structure and Poisson's integral theory of mechanico-electrical systems are studied. The Hamilton canonical equations and generalized Hamilton canonical equations and their the contravariant algebraic forms for mechanico-electrical systems are obtained. The Lie algebraic structure and the Poisson's integral theory of Lagrange mechanico-electrical systems are derived. The Lie algebraic structure admitted and Poisson's integral theory of the Lagrange--Maxwell mechanico-electrical systems are presented. Two examples are presented to illustrate these results.     

Lie symmetry and conserved quantity of a system of first-order differential equations

This paper focuses on studying the Lie symmetry and a conserved quantity of a system of first-order differential equations. The determining equations of the Lie symmetry for a system of first-order differential equations, from which a kind of conserved quantity is deduced, are presented. And their general conclusion is applied to a Hamilton system, a Birkhoff system and a generalized Hamilton system. Two examples are given to illustrate the application of the results.     

时变调幅信号的循环平稳特征

介绍了一种新的时变幅值调制信号的处理方法－循环平稳信号分析与处理方法。在给出时变幅值调制信号模型的基础上,论证了其具有循环平稳特性,进一步分析了其一阶和二阶循环平稳特性,给出了相应的计算公式,并指出循环自相关函数可以有效地实现解调的功能。通过仿真和实测滚动轴承的振动信号加以验证。     

频谱分析在共振系统中的应用

采用频谱分析在方法对机械系统中的振动模式进行分析,使系统中的共振模式的测定规范化、定量化、此方法应用于液体切变波共振吸收谱仪的研制中,取得了良好的效果。