工科基础课程考试命题设计的基本问题

现在,考试仍然是一种通用的评定学生学习成就的方法.当前关键的问题是要充分利用好这个"指挥棒"去促进教学内容和方法的改革,去引导学生在掌握知识,开发智力上发挥自己的主动性.为此,深入研究和探讨考试的命题设计问题,就显得迫切和重要了.     

双层碳纳米管中的周向导波

考虑双层碳纳米管的层间范德华力,采用连续介质力学的波动理论,建立了双层碳纳米管中周向导波传播模型,研究周向导波的频散现象.通过与单层碳纳米管结果的比较表明,双层碳纳米管中周向导波的传播表现出更为明显的频散特性,出现更多的模态干涉现象,并发现在某些特殊频率处出现成对模态的消失与新启现象.     

运动副摩擦参数的识别方法研究

采用粘性 库仑摩擦模型建立了单自由度回转机械系统运动微分方程,分别从时域和频域角度提出了两种识别运动副摩擦参数的方法。仿真结果表明,两种方法在较高信噪比下均能有效地辨识出库仑摩擦和粘性摩擦参数,其中频域法比时域法具有更高的参数估计精度。对电机驱动的单自由度转动机械系统实验装置的运动副建立了相应的摩擦模型,实验结果表明:在不同试验条件下两种方法计算得到的库仑和粘性摩擦参数具有较好重复性,从而验证了本文参数辨识方法的正确性。     

中国科大光力学工作进展

中国科学技术大学光力学实验室近年从事实验力学方法在红外成像、金属物理学以及生化传感等交叉领域的研究，为实验力学带来了新的研究内容，也为相关领域的研究开辟出独特的途径。本文拟对该小组近年来取得的研究进展作一个概述：1）提出微梁阵列FPA变形的高灵敏光学检测法，设计制作出相应的FPA，实现了新概念光学读出红外成像，热成像指标处于国际领先；2）提出用动态散斑研究合金材料锯齿形屈服剪切带，建立了溶质原子与位错交互作用的动态应变时效模型，再现出锯齿形加载曲线和带反复传播的轨迹；3）提出用微梁传感研究大分子／蛋白质构象折叠，检测到构象转变过程中分子间力的相互作用信息和折叠动力学过程，为研究大分子折叠机理提供了一种新途径。     

On the field method in non-holonomic mechanics

This paper deals with the generalization of the field method to non-holonomic systems whose motion is subject to either non-linear constraints or those of a higher order, while their motion is modeled by the generalized Lagrange equations of the second kind. Two examples are given to illustrate the theory.The project supported by the Ministry of Science, Technologies and Development, Republic of Serbia (1874)     

VIBRATION AND ACOUSTIC RADIATION FROM SUBMERGED STIFFENED SPHERICAL SHELL WITH DECK-TYPE INTERNAL PLATE

Based on the motion differential equations of vibration and acoustic coupling system for thin elastic spherical shell with an elastic plate attached to its internal surface, in which Dirac-δ functions are employed to introduce the moments and forces applied by the attachment on the surface of shell, by means of expanding field quantities as Legendre series, a semi-analytic solution is derived for the vibration and acoustic radiation from a submerged stiffened spherical shell with a deck-type internal plate, which has a satisfactory computational effectiveness and precision for an arbitrary frequency range. It is easy to analyze the effect of the internal plate on the acoustic radiation field by using the formulas obtained by the method proposed. It is concluded that the internal plate can significantly change the mechanical and acoustic characteristics of shell, and give the coupling system a very rich resonance frequency spectrum. Moreover, the method can be used to study the acoustic radiation mechanism in similar structures as the one studied here.     

Piecewise analysis of oblique vibro-impacting systems

A great number of studies have shown the complex nonlinear dynamics of mechanical systems with repeated normal impacts. An oblique frictional impact introduces even more complicated dynamics such as stick-slip motions to those systems. Hence, the dynamics of oblique vibro-impacting systems with possible sliding motion is an open problem. Based on a hybrid analysis of vibro-impact dynamics, kinematics and complementary conditions, a piecewise analysis method is developed in the paper to describe the sliding motion during an oblique impact. Thereby, a parametrically excited planar pendulum between two parallel rigid walls is studied as an illustrative example. The example, together with the corresponding numerical results, shows that the sliding impacts occur in such a system with a set of properly selected parameters. The project supported by the National Natural Science Foundation of China (59905010) and by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education, China     

三维相移电子散斑干涉法在柴油机机身中的应用

本文通过一新的三维电子散斑干涉方法，结合四步相移技术和图象处理技术，从三幅全场散斑位相条纹图分离出独立的u、υ、w场位移。测量系统的特点是用三个激光器作为光源，一个PZT相移器推动三个反射镜产生参考光并实现相移以及CCD摄像机前放置大错位剪切镜。将该测量系统应用到柴油机机身部件测量上，得到了机身主轴承孔周的三维位移场，并将此结果作为有限元计算的边界条件，得到了精确的柴油机机身计算结果，证明这一新技术可为柴油机零部件的强度和刚度分析评价提供一种十分有效的方法。     

旋转孔径散斑照相法用于动态三维位移的研测

采用两套旋转孔径散斑照相系统对动态三维位移场进行了研制。一次实验可把缓慢连续变形体的动态三维位移场的整个变化过程记录于两张散斑图上，对散斑图进行全场滤波可获取所有各时刻的三个位移分量的信息。     

部分相干像面散斑技术

本文以光的部分相干性理论为指导,讨论了部分相干像面散斑(通常称为白光散斑)技术的关键.其结果可与激光像面散斑媲美.