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121.
Elastic behaviour of an edge dislocation near a sharp crack emanating from a semi-elliptical blunt crack
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The interaction between an edge dislocation and a crack
emanating from a semi-elliptic hole is dealt with. Utilizing the
complex variable method, closed form solutions are derived for
complex potentials and stress fields. The stress intensity factor at
the tip of the crack and the image force acting on the edge
dislocation are also calculated. The influence of the morphology of
the blunt crack and the position of the edge dislocation on the
shielding effect to the crack and the image force is examined in
detail. The results indicate that the shielding or anti-shielding
effect to the stress intensity factor increases acutely when the
dislocation approaches the tip of the crack. The effect of the
morphology of the blunt crack on the stress intensity factor of the
crack and the image force is very significant. 相似文献
122.
提出一种基于背景光调制的用于傅里叶变换轮廓术测量范围的复合光栅,该光栅通过调制一正弦条纹和不含任何相位信息的背景光来抑制零频,较基于相移技术的复合光栅有更大的优势:背景光只含直流分量,使得复合光栅的频谱更加简单,有利于滤出载波信息,提高测量精度;对从复合光栅中解调出来的背景光只涉及平均值校准,校准过程更为简单;解调出的背景光与物体表面的反射率成正比,具有潜在的应用价值。采用Matlab程序对该复合光栅进行了数值模拟,并对该光栅实用性进行了实验研究,结果证实了该光栅用于抑制零频、扩大傅里叶变换轮廓术测量范围的有效性,且提高了测量精度。 相似文献
123.
Two types of low-light-level image sensors have been investigated for use in low distortion recording: an SIT-vidicon (Silicon-Intensifier Target), and a sensor consisting of a newvicon and two stage proxifier. The results are compared and discussed. In addition, a triggerable video frame store is described. 相似文献
124.
高温扫描隧道显微镜(HT-STM)可以实时原位地捕捉到表面原子的熔化相变过程.在这一原位变温实验中,快速可靠地识别出每帧STM图像中的熔融相十分关键.传统的手工统计方法存在效率低下、随意性大等问题.我们发展出一套基于数学形态学的算法,来自动快速地识别.与人工方法相比,该算法消除了人为主观误差,使确定的边界更加准确、光滑,处理效率提高了266倍. 相似文献
125.
Learnable three-dimensional Gabor convolutional network with global affinity attention for hyperspectral image classification
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Hai-Zhu Pan 《中国物理 B》2022,31(12):120701-120701
Benefiting from the development of hyperspectral imaging technology, hyperspectral image (HSI) classification has become a valuable direction in remote sensing image processing. Recently, researchers have found a connection between convolutional neural networks (CNNs) and Gabor filters. Therefore, some Gabor-based CNN methods have been proposed for HSI classification. However, most Gabor-based CNN methods still manually generate Gabor filters whose parameters are empirically set and remain unchanged during the CNN learning process. Moreover, these methods require patch cubes as network inputs. Such patch cubes may contain interference pixels, which will negatively affect the classification results. To address these problems, in this paper, we propose a learnable three-dimensional (3D) Gabor convolutional network with global affinity attention for HSI classification. More precisely, the learnable 3D Gabor convolution kernel is constructed by the 3D Gabor filter, which can be learned and updated during the training process. Furthermore, spatial and spectral global affinity attention modules are introduced to capture more discriminative features between spatial locations and spectral bands in the patch cube, thus alleviating the interfering pixels problem. Experimental results on three well-known HSI datasets (including two natural crop scenarios and one urban scenario) have demonstrated that the proposed network can achieve powerful classification performance and outperforms widely used machine-learning-based and deep-learning-based methods. 相似文献
126.
127.
Study of a millimeter-wave squint indirect holographic algorithm suitable for imaging with large field-of-view
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In this paper a millimeter-wave (MMW) squint indirect holographic method is presented, which is suitable for imaging with a large field-of-view. The proposed system employs the squint operation mode to remove the background and twin- image interferences, which achieves a similar effect to off-axis holography but leaves out the large-aperture quasi-optical component. The translational scanning manner enables a large field of view and ensures the image uniformity, which is difficult to realize in off-axis holography. In addition, a corresponding imaging algorithm for the presented scheme is developed to reconstruct the image from the recorded hologram. Some imaging results on typical objects, obtained with electromagnetic simulation, demonstrate good performance of the imaging scheme and validate the effectiveness of the image reconstruction algorithm. 相似文献
128.
基于形态学4子带分解金字塔的图像融合 总被引:3,自引:0,他引:3
提出了一种基于数学形态学滤波的多分辨力图像融合。这种融合方法使用了形态学开闭运算构造了低通与高通滤波器,将原始图像分解为4子带图像金字塔和4子带方向衬比度图像金字塔。然后利用方向衬比度和区域标准差进行图像融合得到融合的4子带图像金字塔,最后应用子带图像重构得到融合图像。融合实验表明,该方法优于传统的形态学金字塔图像融合,衬比度金字塔图像融合和小波分解图像融合。 相似文献
129.
Observation of Fano resonance and classical analog of electromagnetically induced transparency in toroidal metamaterials
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Toroidal multipoles have recently been explored in various scientific communities, ranging from atomic and molecular physics, electrodynamics, and solid‐state physics to biology. Here we experimentally and numerically demonstrate a three‐dimensionsal toroidal metamaterial where two different toroidal dipoles along orthogonal directions have been observed. The chosen toroidal metamaterial also simultaneously supports Fano resonance and the classical analog of electromagnetically induced transparency (EIT) phenomena in the transmission spectra that originate from the electric–toroidal dipole and electric–magnetic dipole destructive interference. The intriguing properties of the toroidal resonances may open up avenues for applications in toroidal moments generator, sensing and slow‐light devices. 相似文献
130.