Longitudinal elastic waves in columns due to earthquake motion

An analysis is presented of longitudinal waves in a thin elastic column. Velocity is specified at one end, and the boundary condition at the other end is expressed in terms of a range of effective impedances of an attached structure. Propagation, reflection and interference of the waves are followed by the method of characteristics. Integration of differential equations along characteristics yields the wave-induced stress, which is then applied to problems of earthquake excitation. Numerical examples are given for recorded updown ground motion of the Kobe Earthquake.     

Early detection of ageing in solder joints through laser probe thermal analysis of the peltier effect

We have recently developed an optical contactless method for testing the quality of solder joints during accelerated thermal cycling ageing processes.¹ The method was based upon the measurement of the dynamic thermal behaviour of the joint to short bursts of Joule heating. It has proved to be efficient in revealing the formation of cracks at the lead-solder interface. We present a method to evaluate ageing at a much earlier stage in the cycling process. We have observed in earlier work,¹ that before cracks appear, structural changes occur in the solder at the lead-solder interface. The thermal response of the solder joint is recorded over time to a Peltier heat perturbation produced by flowing a current pulse through the interface where structural changes occur. The key point in this method is to discriminate the Peltier effect from the Joule thermal response because both effects generate heat. The variation of the early Peltier response in the thermal cycling ageing tests is seen as a quantitative signature of the structural changes in the lead-solder interface.     

高灵敏度热释电摄象管红外电视系统

针对热释电摄象管(PEV)在传统的对称斩波模式下存在的各种问题,设计了一种新的非对称斩波模式PEV红外电视系统.通过提高PEV摄象机的温度响应率R_i和采用高去噪声信号处理系统,大大改善了PEV红外成象系统的性能.     

Modeling and simulation of the drying of thin sheets in a continuous infrared dryer

The model gives the temperature and moisture distributions of the air, and of the moist sheet, as a function of time and distance in the dryer. The influence of the sheet's velocity and that of the radiant energy on the dryer performance as well as the effect of the moisture content of the entering sheet have been studied. A set of 27 experiments was carried out using the infrared dryer in order to calibrate the model. In these, the following three variables each had three operational levels: web velocity, initial web moisture and heating power. The model predictions agreed very well with the experimental data. Model predictions using arithmetic averages for the parameters, and parameters correlated with operational variables, are also presented and discussed.     

砷化镓声电荷转移延迟线的设计与工艺研究

由于声电荷转移(ACT)这一新颖的高速缓冲抽样技术的发明,使得新一代高速高频信号处理器件的实现成为可能。本文研究了第二代平面结构的ACT器件转移沟道的电位分布特性,给出了平面结构ACT延迟线的设计,并研究了ACT器件的工艺实现。     

热力系统节能技术改造方案介绍

针对热电厂热力系统存在的浪费能源和设计不合理现象作了浅析 ,介绍了几种对热力系统进行改造的方案 ,并对取得的经济效益进行了计算。     

利用短周期地脉动推断深层地基S波速度

从二维随机波场的相关理论出发，提出了如何从短周期地脉动（频率＞０．５Ｈｚ）时域信号中计算Ｒａｙｌｅｉｇｈ波弥散曲线，进而反演深层地基剪切波（Ｓ波）速度的理论方法和分析技术，并结合实测信号的分析结果，探讨了该方法的可行性和实用性。     

近红外仿灸仪的研制与临床应用

近红外仿灸仪,也称为经络灸疗仪,是采用我国传统医学与现代科学技术相结合而研制成的一种新型中医治疗、保健仪器,可以用于治疗多种疾病。本仪器根据艾灸燃烧时所辐射的光谱,运用仿真技术进行模拟,根除了传统灸法燃烧缓慢、效率不高、烟雾较大、刺鼻熏眼、易于灼伤、操作不便等缺点,充分发挥了我国传统灸法的温经通络、补气活血、化瘀消肿,祛湿止痛的功效。     

Optical measurements of thermal diffusivity of a material

The measurement of thermal diffusivity of a material (in particular, a thin film) is important for various reasons, e.g., to predict the heat transfer in the solid subjected to a thermal process, to monitor surface composition or morphology, or to detect invisible subsurface defects like delaminations. This measurement can be done in a noncontact manner using various photothermal methods. Such methods typically involve pulsed heating of the surface by small amounts using a laser source; the decay of the surface temperature after this pulsed photothermal heating is then probed to provide the thermal diffusivity. Various probing methods have been developed in the literature, including the probing of reflection, refraction, and diffraction from the pulsed heated area, infrared thermal radiometry, and surface deformation. This paper provides an overview of such techniques and some examples of their applications.     

叠后地震剖面的线性化波阻抗反演

本文提出了由井旁道出发逐道进行的叠后地震剖面的线性化波阻抗反演方法。每一道反演采用逐次线性化对波阻抗进行修正，反演的纵向分辨率为一个采样时间间隔，并以合成记录道与实际地震道的相似系数作为迭代收敛准则，已处理的地震道波阻抗作为下一道反演初始值。实际资料处理表明，该方法具有较高的分辨率和运算速度快的优点。