水下摄影反向散射的研究与实验

由于水中光传输的特殊性,特别是水对光的反向散射,使得水下摄影的成象质量大大低于陆地摄影成象质量。本文从衬度的角度出发,着重讨论了水下摄影中反向散射对成象质量的影响,并比较了不同照明方式对摄影结果清晰度的影响,从而得出窄光束光源照明对提高摄影图像的衬度是大有好处的结果。 本文提供了一些理论分析和初步的实验结果。     

Lamb wave radiation from plate termination in a liquid

The liquid wedge method is used to excite leaky Lamb waves on an aluminium plate while the plate is immersed in water. The excitation occurs near the end of the plate so that sonic energy of the excited mode radiates into the liquid. A Schlieren method is used to observe the radiation pattern and a correlation is made between the radiation lobe structure and the symmetric or antisymmetric nature of the excited mode. Theoretical calculations of the transfer of energy from the plate to the liquid are made and agreement between theory and experiment is obtained.     

白光数字散斑照像术

本文提出一种新的数字散斑计量术——白光数字散斑照像术.它以两维数字偏心滤波技术实现全场信息的表征,而以数字相关技术实现点信息的表征.文中给出了计量方法、理论分析及实验结果.     

时间序列差分干涉术研究激波流场

本文用一种新的时间序列差分干涉术研究模型在超音速风洞中产生的激波流场.实.验中用调Q序列脉冲红宝石激光器作光源,用转镜扫描高速摄影机作为记录设备,结合单Wollaston棱镜差分干涉的方法获得了激波流场的序列差分干涉图.利用图象处理技术对干涉图进行图象处理,人机交互的方式采集数据,用条纹位移转换法将差分干涉图的条纹位移量转换为绝对干涉图的条纹位移量,然后用拉普拉斯变换法计算出了密度的相对分布值.     

用数字滤波消除散斑条纹图噪声

本文讨论了散斑摄影条纹图的噪声来源及模型,设计合适的数字滤波器.采取正交实验手段,全面分析了噪声、条纹对比度和密度对条纹方向及间距测量精度的影响.     

F. 特种高速摄影技术

本文主要介绍了激光散斑和莫尔摄影、纹影摄影、光纤技术、频闪光源和立体摄影等特种高速摄影技术。     

散斑照像计量中全场信息分布的统计学模型

本文论证了以散斑照像计量中计量场的系综平均值代表变形信息这样一个基本观点,明确了散斑照像计量中信息的识别是对单一样本计量物所进行的统计识别,进而建立了全场滤波技术中信息分布的统计学模型,并以此解决了测量范围及测量灵敏度等问题。     

GS-221高速摄影测量仪中的微机数据记录系统

本文介绍了单片机控制的GS-221高速摄影测量仪数据记录系统的工作原理、硬件设置和主要的软件流程。     

旋转孔径白光散斑照相法的研究

本文报道利用旋转孔径法进行白光散斑照相,研测动态问题.其不仅具有旋转孔径激光散斑照相的优点,而且最突出的优点是能走出实验室,到现场进行动态测量研究.     

Shock waves in aviation security and safety

Accident investigations such as of Pan Am 103 and TWA 800 reveal the key role of shock-wave propagation in destroying the aircraft when an on-board explosion occurs. This paper surveys shock wave propagation inside an aircraft fuselage, caused either by a terrorist device or by accident, and provides some new experimental results. While aircraft-hardening research has been under way for more than a decade, no such experiments to date have used the crucial tool of high-speed optical imaging to visualize shock motion. Here, Penn State's Full-Scale Schlieren flow visualization facility yields the first shock-motion images in aviation security scenarios: 1) Explosions beneath full-size aircraft seats occupied by mannequins, 2) Explosions inside partially-filled luggage containers, and 3) Luggage-container explosions resulting in hull-holing. Both single-frame images and drum-camera movies are obtained. The implications of these results are discussed, though the overall topic must still be considered in its infancy. Received 22 July 2001 / Accepted 19 July 2002 Published online 4 November 2002 Correspondence to: G.S. Settles (e-mail: gss2@psu.edu) An abridged version of this paper was presented at the 23rd International Symposium on Shock Waves at Fort Worth, Texas, from July 22 to 27, 2001.