夹心式纵-扭复合模式压电超声换能器的共振频率

本文对夹心式纵-扭复合振动模式压电超声换能器进行了研究．从换能器的等效电路出发，在无耦合时，得出了换能器中纵向振动模式及扭转振动模式的各自共振频率方程．实验表明，换能器各自共振频率的测试值与理论计算值基本符合．     

关于隐式代数曲面的一种几何连续性定义

本文利用函数的幂级数给出了隐式代数曲面的一种几何连续性定义．证明了在此定义下的ｋ阶几何连续即为ｋ阶变尺度（ｒｅｓｃａｌｉｎｇ）连续，并举例说明了其应用的方便性．     

Ultrasonic methods for measuring crack location,crack height and crack angle

Two ultrasonic methods are proposed to measure the crack location and the crack height for vertical and inclined defects. The methods measure the time traversed between the entry point of the sound beam in the material and the defect. Differing from most previous methods, they do not depend on knowing the probe angle, a parameter difficult to measure accurately and which varies from material to material being inspected. Accordingly, the crack can be viewed from different angles, thus reducing the random error in the measurement.     

对数平均的推广

记J_1(x,y)=[t(x~(t+1)-y~(t+1)]/[(t+1)(x~t-y~t)]。它有性质:J_(-1/2)(x,y)=G(x,y),J_(1/2)(x,y)=He(x,y),J_1(x,y)=A(x,y)。我们证明了J_1(x,y)关于t单调增加。同时有(?)。那么我们有不等式G(x,y)≤L(x,y)≤He(x,y)≤A(x,y)。     

无氨湿法制备纳米晶In2O3及表征

Preparation of In₂O₃nano-scale powders by ultrasonic and homogeneous precipitation, using metal In and urea as raw materials, was reported for the first time, while the effects of reaction temperature, the ratio of the materials and the pH etc. on the preparation was dicussed. This method can be operated and industrialized easily with very low cost． The structural properties of precursor and In₂O₃were characterized by TG-DTA, XRD, ESCA and TEM. The results show that In₂O₃produced are very pure, monophase and spherical nano-scale powders with average size of 25 nm.     

5-叔丁基-5-(1'-羟基-2'-甲基丙基)-2,2-二甲基-1,3-二氧六环的合成研究

为得到3,4-二取代双环硫化磷酸酯的中间体5-叔丁基-5-(1'-羟基-2'-甲基丙基)-2,2-二甲基-1,3-二氧六环, 通过5-叔丁基-5-甲酰基-2,2-二甲基-1,3-二氧六环与异丙基溴化镁反应没有得到目标化合物, 而得到了还原产物, 改用异丙基锂代替异丙基溴化镁反应后得到目标化合物, 通过超声波辅助反应, 大幅度提高了反应收率.     

Stability of adsorber resins under mechanical compression and ultrasonication

Different adsorber and ion exchange resins have been sonicated with ultrasound of different frequencies in a fixed bed. Afterwards, the sonicated particles were investigated by scanning electron and light microscopy. Also, different mechanical properties, like fracture load, maximum flattening and Young's modulus were measured in compression tests and compared to the results of the ultrasonication experiments. Cavitational collapses cause cracks in resins with a high fracture load and a high Young's modulus as well as a low deformation at fracture. Complete destruction of adsorbent particles due to acoustic cavitation is observed with particles of low fracture loading and low Young's modulus. No or only little destruction is observed with particles which inhibit both sufficient strength and deformation properties. On the basis of these findings it is concluded that resin particles with optimum resistance to ultrasound show both a sufficient fracture load as well as high mechanical flexibility. Copyright © 2002 John Wiley & Sons, Ltd.     

Molecular Interactions in Formamide + Isomeric Butanols: An Ultrasonic and Volumetric Study

Densities, , ultrasonic speeds, u and viscosities, of the binary mixtures of formamide (FA) with 1-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol, including those of pure liquids, were measured over the whole composition range at 35°C. Using the experimental values of , u and , the deviations in isentropic compressibility, _s , excess volume, V ^E, viscosity, , and excess Gibbs energy of activation of viscous flow, G* ^E , were calculated from the linear dependence of these parameters on composition of mixtures. The apparent molar isentropic compressibility, K _,2 and apparent molar volume, V ^,2 of alcohols in FA were also calculated. The variations of these parameters with composition are discussed from the point of view of intermolecular interactions in these mixtures. The V ^E data have also been analyzed using Prigogine–Flory–Patterson theory. An analysis of each of the three contributions, viz., interactional, free volume, and P* effect to V ^E shows that P*, the internal pressure parameter of the theory, plays a dominant role in deciding the sign and magnitude of V ^E.     

关于聚电解质浓溶液的粘度-浓度幂律方程中指数(α)的探讨

在含有0.07 mol NaNO_3外加盐和无外加盐的二甲基甲酰胺/甲苯(体积比:3/1)的两类混合溶剂中,采用RN50-1型落球粘度仪研究了不同磺化度(IEC=0～0.93mmol/g)的磺化聚砜(S-PSF)浓溶液的零剪切粘度(η)-浓度(C)的幂律关系式,η=K·C~α。实验结果显示:磺化度不同的试样在舍有外加盐溶剂中的指数(α=4.29～3.52)值均分别大于无外加盐溶剂中的指数(α=4.09～3.03)值,且它们都随试样磺化度的增加而下降。文中,应用标度的分析方法对浓度指数(α)的变化规律作了解释。     

Quasichemical interpretation of the ultrasonic velocity in ternary aqueous systems

The quasichemical model of hydration have been used to calculate the speed of ultrasound in binary solutions of water and nonelectrolyte. The model has been confined to systems that exhibit a maximum in the ultrasonic velocity vs. nonelectrolyte concentration. The parameters of the model are the hydration equilibrium constant, the nonelectrolyte hydration number, and the molar volume and compressibility of the hydrated nonelectrolyte. These have been fitted to experimental results by the method of least squares. The model calculations reproduce qualitatively the ultrasonic velocity as a function of nonelectrolyte concentration. The calculated maximum of the ultrasonic velocity is generally too low, but the nonelectrolyte concentration at which this maximum occurs agrees well with experiment.Addition of a third component shift the velocity maximum. The quasichemical model has also been used to calculate this shift. These calculations have been based on the parameters developed for the binary system. The shift on the nonelectrolyte concentration scale is reproduced satisfactorily, but the shift of the maximal value of the ultrasonic velocity is less accurately predicted by the model.