排序方式: 共有58条查询结果,搜索用时 15 毫秒
21.
22.
深度学习(Deep Learning)是目前最强大的机器学习算法之一,其中卷积神经网络(Convolutional Neural Network, CNN)模型具有自动学习特征的能力,在图像处理领域较其他深度学习模型有较大的性能优势。本文先简述了深度学习的发展史,然后综述了深度学习在超声检测缺陷识别中的应用与发展,从早期浅层神经网络到现在深度学习的应用现状,并借鉴医学影像识别和射线图像识别领域的方法,分析了卷积神经网络对超声图像缺陷识别的适用性。最后,探讨归纳了目前在超声检测图像识别中使用CNN存在的一些问题,及其主要应对策略的研究方向。 相似文献
23.
24.
25.
The horizontally polarized ultrasonic shear wave field emitted by an electromagnetic acoustic transducer (EMAT) is studied by the surface force distribution on the EMAT approximately described as an inhomogeneous horizontal shear force. The shear wave directivity pattern is plotted by numerical calculations based on our strictly analytic solutions of the wave field we presented previously. An experimental system of EMAT generation and piezoelectric transducer reception is set up to check the predictions of the theoretical wave field by measuring the ultrasonic signals through aluminium block. The directivity pattern of the wave field obtained from the experimental results conforms the theoretical prediction, which lays a foundation for engineering applications of EMATs. 相似文献
26.
Theoretical Development of Nonlinear Spring Models for the Second Harmonics on an Interface between Two Solids
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Based on the exact solutions for the second-harmonic generations of the fundamental longitudinal and transverse waves propagating normally through a thin elastic layer between two solids, the approximate representations termed as 'nonlinear spring models' relating the stresses and displacements on both sides of the interface are rigorously developed by asymptotic expansions of the wave fields for an elastic layer in the limit of small thickness to wavelength ratio. The applicability for the so-called nonlinear spring models is numerically analyzed by comparison with exact solutions for the second harmonic wave reflections. The present nonlinear spring models lay a theoretical foundation to evaluate the interracial properties by nonlinear acoustic waves. 相似文献
27.
28.
今年6月15日,是我国著名物理学家、超声学研究奠基人、声学领域著名教育家,中国科学院资深院士应崇福先生95诞辰。《应用声学》杂志出版系列纪念论文,以缅怀这位学术大师。我有幸应邀为此系列纪念论文作序,追思应先生对声学事业发展的重大贡献,表达声学同仁们对他的崇高敬意,激励后人继承应先生爱国奉献的精神和严谨治学的学风。 相似文献
29.
30.
板底薄层的超声谐振检测分析 总被引:2,自引:0,他引:2
理论上研究了带有薄层的板的超声谐振频率随薄层的厚度或物性改变而发生变化的规律,研究结果表明,在0 ≤ ω<c2/d2 arctan (Z1/Z2)范围内,板的半波谐振频率因薄层厚度的增加向低频飘移;在一阶近似条件下,飘移量的大小正比于薄层和板的单位面积质量之比。在此基础上,提出了利用板的谐振频率飘移量进行板底薄层厚度检测的方法,并对6.24 mm厚铝板下不同厚度(54-324 μm)的薄层进行了厚度检测,实验得到的厚度相对误差在6%以下。实验结果进一步证实了该规律是正确的,以及基于该规律的板底薄层检测方法是可行的。 相似文献