1064 nm窄带干涉滤光片激光破坏研究

干涉滤光片由于内部谐振场共振吸收特性,其激光破坏过程有别于全反膜而具有特殊的性质。本文从谐振场及湿度场理论出发,计算得出了ZnS/MgF2为主材料的滤光片的谐振场及温度场分布规律。在此规律指导下,对相同膜系结构的一系列滤光片的激光破坏阈值、吸收及破坏形貌进行了测量与分析,结合实验结果对干涉滤光片独具特色的破坏发展过程作出了描述,并给出了一定的解释。     

Invariant Manifold Approach for the Stabilization of Nonholonomic Chained Systems: Application to a Mobile Robot

In this paper it is shown that a class ofn-dimensional nonholonomic chained systems can bestabilized using the invariant manifold approach. First, we derive aninvariant manifold for this class of systems and we show that, once onit, all the closed-loop trajectories tend to the origin under a linearsmooth time-invariant state feedback. Thereafter, it is shown that thismanifold can be made attractive by means of a discontinuoustime-invariant state feedback. Finally, a mobile robot is taken as anexample demonstrating the effectiveness of our study.     

提高电化学法测试壁面剪应力精度的方法

应用电化学方法对流场壁面剪应力进行测试在生物力学中有着广泛的用途,静止极限电流在存在将影响壁面剪应力测试的精度,在测试时应根据具体的实验条件进行现场测试,实验表明在测试较低壁面剪应力时,静止极限电流的影响较大;在测试较高壁面剪应力时,则可忽略静止极限电流的影响,极化电压条件下测得极限电流是测试壁面剪应力的基础。为了测试的准确可靠,需对产生极化的外加电压进行实地测试,在测试时,对每个电极都需根据相应的测试条件进行系统标定。     

用高速阴影技术研究K9玻璃中的失效波

用高速阴影摄影技术研究了爆轰加载下K9玻璃样品中波的传播和压缩区内损伤破坏的物理图象和规律。实验中观测到冲击波阵面后有一个移动速度为 2 .1～ 2 .2mm/ s的黑色阴影区边界 ,即失效波 (Fail urewave) ;实验发现只有当冲击载荷接近材料的HEL时 ,在冲击波和失效波之间的区域才有少量的微裂纹成核和长大 ,而在冲击载荷较低时却没有观察到 ;同时实验中观测到失效波萌生于被撞击面 ,并在两块玻璃的交界面上观测到失效波的再生。这些结果表明失效波的产生基本与冲击相变无关 ,主要与玻璃样品表面的初始损伤有关 ,换言之 ,失效波是玻璃样品表面微裂纹在冲击波作用下失稳扩展造成的。     

水下图像导航技术在潜艇上的应用

潜艇传统的导航方法是采用惯导、无线电导航等技术,随着计算机技术=数字图像处理技术以及传感器技术的发展,在潜艇上采用视觉图像定位测距系统进行导航是一个新的发展方向,它可以实现潜艇自主导航,减少被敌方发现和干扰的机会,从而增强潜艇的隐蔽性及其发起攻击的突然性,因此,研究图像导航技术并将其应用到实际战斗单元上是迫切需要的,水下视觉图像包括声视觉和光视觉两种图像形式,中就水下图像导航技术的几个方面阐述目前的技术现状,指出将其应用于潜艇导航的可行性。     

The recent development of neutronic techniques for determination of residual stresses

Neutron diffraction is a well-established non-destructive method for the measurement of residual stress deep inside materials. This paper gives a short overview of the use of neutrons for materials research and measurement techniques. Neutron diffraction has been applied in determining residual stresses in metal matrix composites. Measurement and prediction of residual stress for plastic deformation are presented. More recently, the neutron diffraction technique has also been applied for the determination of plastic strain which results from microstructural defects and leads to peak broadening. Influence of the shot penning treatment on austenitic steel is presented.     

关于中学生的原子、分子心智模型的研究

学生对于科学概念的认识被称为学生的心智模型。本研究探讨了学生关于原子、分子2个概念的心智模型。研究采用半结构的访谈法,访谈对象是初三、高一和大学一年级的学生。文章从2个方面对研究结果进行了分析：学生关于原子模型的认识、学生对于原子、分子的描述。文章最后对研究结果进行了讨论。     

Effect of testing conditions on the laser flash thermal diffusivity measurements of ceramics

Several experimental techniques either under steady state or transient heat transfer conditions, have been developed to evaluate thermal conductivity and thermal diffusivity of materials. However, testing difficulties resulting from specimen size, extended testing time and heat losses, have somewhat impaired the applicability of many of them. In this respect, the use of the laser flash technique for thermal diffusivity measurements, is a very convenient alternative, considering its basic modeling equation is independent of the temperature gradient as well as the heat flow, and in addition the heat losses can be analytically treated. Another important advantage of the technique is its rapid experimental execution. In this work, it is presented as an investigation concerning how the testing conditions such as specimen coating, laser power and pulse duration, base line adoption, heat losses correction methods, and specimen thickness, may affect the thermal diffusivity measurements of some ceramic materials using the laser flash technique.     

脉冲电势调制型电化学气体传感器

根据暂态电化学原理 ,使用微电极并融合计算机控制的快速电势调制技术和数据采集、处理功能 ,提出并建立了一类全新的集信号提取、处理与结果显示等功能于一体的“脉冲电势调制型气体传感器” .在优化传感器性能及其新的功能开发和集成方面取得了重要进展 ,是一类为常规电化学气体传感器无法比拟而有发展前景的暂态电化学多组份气体传感器 .     

Studies on Ion-molecule Reaction of Disubstituted Benzene with IonSystem of Acetyl Chloride in Gas Phase

IntroductionThe intramolecular function group interaction plays an important role in gas--phase ionmolecular reactions and the fragmentation reactions of its product ionsLI--12]. The fragmenta..non reactions of the odd--electron ions of benzoic acid[13], phenylacetyleneL"], phenylsulfide[15], nitrobenzene[16j, methoxybenzaldehyde["] and acetophenone["J obviously show theOrtho effect. The fragmentation properties of the protonated molecules and the adduct ions ofo, m, p- meth oxy - ac etop he…