一种固定阈值的毫米波图像边缘检测方法

文章提出了一种固定阈值的毫米波图像边缘检测方法。根据图像的统计特征确定出像素的标准梯度强度，并采用单阈值对图像进行边缘粗定位，然后施行非最大抑制处理和滤波，得到最终检测结果。由于该算法对各幅毫米波图像设置相同的阈值，故能实现自动检测，同时还具有计算量小的特点。实验结果表明该方法进行毫米波图像边缘检测的有效性和可行性。     

Hybrid numerical scheme for time-evolving wave fields

Many problems in geophysics, acoustics, elasticity theory, cancer treatment, food process control and electrodynamics involve study of wave field synthesis (WFS) in some form or another. In the present work, modelling of wave propagation phenomena is studied as a static problem, using finite element method and treating time as an additional spatial dimension. In particular, WFS problems are analysed using discrete methods. It is shown that a fully finite element-based scheme is very natural and effective method for the solution of such problems. Distributed WFS in the context of two-dimensional problems is outlined and incorporation of any geometric or material non-linearities is shown to be straightforward. This has significant implications for problems in geophysics or biological media, where material inhomogeneities are quite prevalent. Numerical results are presented for several problems referring to media with material inhomogeneities and predefined absorption profiles. The method can be extended to three-dimensional problems involving anisotropic media properties in a relatively straightforward manner. Copyright © 2006 John Wiley & Sons, Ltd.     

利用Love波特性计算地基动力响应

本文利用Love波弥散特性在频域上对地基出平面振动及扭振问题进行了研究。在计算区域内结构将采用有限单元划分,而在边界上则根据Love 面波特性使用传递边界有限单元。本文同时讨论了不同模态波对结构动力响应的贡献。本文方法也适合于静力分析。     

波浪力计算中的一个新边界元方法

本文就波浪与结构物作用问题，提出了一个新的高阶边界元方法。较之Ｅａｔｏｃｋ Ｔｏｙｌｏｒ和Ｃｈａｕ的方法，本文在体内附助积分方程中应用了满足刚性水面条件和弱刚性底面条件的简单格林函数。计算速度相应地有所提高；漂浮结构的积分方程更为简洁；计算结果与Ｅａｔｏｃｋ Ｔａｙｌｏｒ和Ｃｈａｕ的方法具有几乎相同的精度和收敛速度。     

用于疏通油水井的脉冲放电技术

评价了各种不同的解堵技术，指出冲击波解堵是一种很有发展前途的技术。介绍了液中脉冲放电产生冲击波的基本原理，并由此研制出了一套井下脉冲放电油水井处理设备样机。通过现场试验，表明用冲击波疏通油井能较好地解除油井污染，提高采收率。     

CTS-26型超声探伤仪典型故障的分析与排除

在简要介绍CTS-26型超声探伤仪工作原理及组成的基础上。对其几种典型故障作了具体的分析和处理。     

Nondestructive evaluation of pavements using spectral analysis of surface waves in the frequency wave-number domain

The potential of using Spectral analysis of surface waves (SASW) for nondestructive testing of pavement and soil sites has been demonstrated in several publications. The usual SASW field testing and data analysis procedures and the assumption of a single propagation mode yield accurate results when there are no sharp changes in the stiffness of the site with depth. When this is not the case, however, difficulties arise in the interpretation of experimental data due to the participation of more than one mode in the wave field. In an earlier study, the multiple filter/crosscorrelation technique was suggested for analyzing multi-mode SASW signals. This technique, however, may not yield accurate results when propagation modes are closely spaced. A more general method using spectral analysis in the frequency wave-number domain is presented in this paper. Formulas are presented for determining a reasonably small number of surface measurements, and the accuracy of this method in resolving experimental dispersion curves is demonstrated for a pavement site.     

连续运转的掺钛蓝宝石激光器

本文报导一种连续波氩离子激光泵浦的掺钛蓝宝石激光器。在氩离子激光功率(全谱线)为10.45瓦且仅用一组腔镜时,获得最大平均功率超过1000mW、调谐范围750～850nm的掺钛蓝宝石激光输出。     

Passivation and corrosion behaviours of cobalt and cobalt-chromium-molybdenum alloy

Passivation and corrosion behaviour of the cobalt and cobalt-base alloy Co30Cr6Mo was studied in a simulated physiological solution containing chloride and bicarbonate ions and with pH of 6.8. The oxido-reduction processes included solid state transformations occurring at the cobalt/electrolyte interface are interpreted using theories of surface electrochemistry. The dissolution of cobalt is significantly suppressed by alloying it with chromium and molybdenum, since the alloy exhibited “chromium like” passivity. The structural and protective properties of passive oxide films formed spontaneously at the open circuit potential or during the anodic polarization were studied using electrochemical impedance spectroscopy in the wide frequency range.     

高频声表面波滤波器用单指换能器

报道两种带宽极窄的采用单指换能器制作的声表面波滤波器。一种是利用单指换能器声同步频率与反射频率之间的相位叠加与相消来制作的体积极小（芯片面积只有采用双指换能器的三分之一不到）的高频极窄带声表面波滤波器，其３ｄＢ带宽的相位变化只１２０°；另一种是采用合理布局的单指无内反射换能器制作的高频极布带声表面波滤波器，其幅频特性同采用双指换能器制作的同类型的声表面波滤波器一样。最后给出了这两种声表面波滤波器的较详细的理论分析和实验结果。关键词