Synergistic effects on iodine release in potassium iodide solution by combination of ultrasound and visible light irradiations

Iodine release in potassium iodide solution has been investigated under the irradiations of ultrasound and visible light respectively and simultaneously. We have observed that the amount of iodine liberated under the combined irradiation of ultrasound and visible light is larger than the sum of that under the respective irradiations of ultrasound and visible light, indicating a synergistic effect of ultrasound and visible light irradiations. Based on the investigation of the reaction kinetics of iodine liberated, we have ascribed the synergistic effect to the perfect stirring of the photochemical reactor induced by the applying simultaneous ultrasound. The ideal stirring can result in the homogenization of the primary light effect in the whole reaction medium, which induces the acceleration of the photochemical reaction. On behavior of our knowledge, there are few reports on the investigations of utilizing the combination of ultrasonic energy and light energy to accelerate the reaction yield and rate as well as the kinetics of the reaction.     

基于超声红外技术对金属管内壁缺陷的检测

为提高管道的运送效率,及时检测排除管道内壁的缺陷非常重要。提出利用超声红外无损检测方法对管道内部进行检测。超声主动热激励试件,高频红外热像仪记录试件表面温度变化,结合了超声摩擦生热和红外热成像的优点。对壁厚约为3.3mm检测难度较大的金属管内壁缺陷进行了检测。通过对采集数据和热图的处理分析,准确快速地确定缺陷所在的位置。实物对比分析表明：超声热激励红外无损检测技术可以对金属管道内壁缺陷进行准确检测定位。     

A methodology for structural health monitoring with diffuse ultrasonic waves in the presence of temperature variations

Diffuse ultrasonic waves for structural health monitoring offer the advantages of simplicity of signal generation and reception, sensitivity to damage, and large area coverage; however, there are the serious disadvantages of no accepted methodology for analyzing the complex recorded signals and sensitivity to environmental changes such as temperature and surface conditions. Presented here is a methodology for applying diffuse ultrasonic waves to the problem of detecting structural damage in the presence of unmeasured temperature changes. This methodology is based upon the prediction and observation that the first order effect of a temperature change on a diffuse ultrasonic wave is a time dilation or compression. A multi-step procedure is implemented to (1) record a set of baseline waveforms from the undamaged specimen at temperatures spanning the expected operating range, (2) select a waveform from the baseline set whose temperature is the closest to that of a subsequently measured signal, (3) adjust this baseline waveform to best match the signal, and (4) calculate an error parameter between the signal and the adjusted waveform and compare this parameter to a threshold to determine the structural status. This procedure is applied to experimental data from aluminum plate specimens with artificial flaws. Probability of detection and the minimum flaw size detected are presented as a function of the size of the baseline waveform set. It is shown that a probability of detection of over 95% can be achieved with a small number of baseline waveforms.     

超声降解处理水体污染物的研究状况与发展

利用超声产生的空化效应来降解水体中的污染物,是近几年来国外研究者关注的热点领域之一。文章就超声在污染水体降解的原理、理论、降解效果以及主要的影响因素作扼要的综述介绍,对存在的问题和发展的趋势提出见解和看法。     

Non-linearity parameter B/A of binary liquid mixtures at elevated pressures

When sound waves of high amplitude propagate, several non-linear effects occur. Ultrasonic studies in liquid mixtures provide valuable information about structure and interaction in such systems. The present investigation comprises of theoretical evaluation of the acoustic non-linearity parameter B/A of four binary liquid mixtures using Tong and Dong equation at high pressures and T=303.15 K. Thermodynamic method has also been used to calculate the non-linearity parameter after making certain approximations.     

Intermediate regime of light diffraction by surface ultrasonic waves in planar gyrotropic optical waveguides

The intermediate regime of optoacoustic interaction, similar to the Bragg one, with Rayleigh surface ultrasonic waves in gyrotropic planar waveguides is studied. A system of equations of bound waves is presented that describes planar optoacoustic interaction in the intermediate, Raman-Natoh, and Bragg regimes of light diffraction by surface ultrasonic waves. It is shown that the optical activity of a wavequide film favors the incident light energy pumping to diffracted light for a TE-polarization wave and decelerates this process for an incident TM-polarization wave. Mozyr' State Pedagogical Institute, 28, Studencheskaya St., Mozyr', 247760, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 412–416, May–June, 1997.     

简谈空气中的声速与温度关系

讨论了驻波法测空气中声速的实验,分别用相位比较法和李萨如图法来确定超声波波长.在不同温度条件下测量了声速并与理论值进行比较,实验结果显示测量温度接近室温时实验值与理论值基本一致,测量温度与室温相差较大时实验值与理论值偏差较大.     

低声阻抗复合压电陶瓷的研究及应用

本文研究了我们所配制夹心结构复合压电材料低声阻抗的特性。实验表明，夹心复合压电陶瓷材料的声阻抗，与所用陶瓷材料的种类，气孔率，孔径，样品厚度以及工艺制备过程有关。实验证明，研制特定阻抗的材料是可行的，最后，用研制的新材料成功地应用于混凝土、Ｃ／Ｃ复合材料等非金属材料的超声检测中。     

虫蛀玉米种子的空气耦合超声波检测

提出了一种基于空气耦合超声波技术的玉米种子虫蛀孔洞颗粒和完好颗粒分类识别方法·首先根据玉米颗粒的弹性模量、泊松比和密度等物理量计算出了玉米颗粒的声速,并根据检测精度需求设定了激励信号频率。然后采用MATLAB对采集的两类种子超声波信号数据进行分析处理,并分析了种子厚度和摆放方位对超声波响应特征的影响。最后建立了K近邻(KNN)、簇类独立软模式法(SIMCA)、Fisher线性判别(LDA)和决策树(DT)识别模型,并对模型性能进行了测试.结果表明;种子孔洞深度、胚部厚度和正反面方位不同,即超声波在种子表面的反射程度不同、在种子中传播声程不同,则起声波信号衰减程度不同,导致接收到信号的幅值不同,且样本点在主成分分析(PCA)特征空间的分布也不同。4种识别模型均可以实现对两类玉米的分类识别,其中KNN模型性能最佳,其对虫蛀孔洞颗粒和完好颗粒的正确识别率分别为98%100%,误差带为2%,0。此结果说明采用空气耦合超声波技术可以实现对玉米种子虫蛀孔洞颗粒的检测。     

一类弱散射界面背向散射超声散斑一阶统计特性

对超声入射至分布有细小凹坑的界平面，这一类弱散射界面背向散射所形成的超声散斑的一阶统计特性进行了研究.在假设条件下，理论分析的结果表明，空间超声散斑的振幅服从Rice分布，而它们的相位概率密度函数是一个包含Gauss分布函数和Gauss概率积分函数的复合函数.当细孔密度非常大时，超声散斑的振幅就趋于Rayleigh分布.应用作者建立的由计算机控制扫描的实验系统，对这一类弱散射界面反射超声散斑的振幅分布进行了测量.实验结果表明，理论分析的结果是正确的，由此，所作的假设条件也是成立的. 关键词： 弱散射 超声散斑 统计特性