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3 2020

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A model of degree of scattering polarization for oil spilling

Wang Xiao, Xu Jiang, Qian Weixian, Ouyang Jingyi

Optica Applicata

2020

Vol. 50, nr 3

433--445

Oil slicks often show uncertain surface roughness and Fresnel reflection parameters. Consequently, differentiating oil spilled on the seawater in these areas using optical sensors is a challenge. Therefore, the optical mechanism of the oil film has been studied by the Maxwell equation. It is found that the polarization characteristics of the oil slicks can help us to overcome this problem. According to the Fresnel formula, the scattering coefficient and scattering rate of the homogeneous oil film have been deduced, and the phase difference of the scattering electromagnetic wave has also been calculated to verify the accuracy of the model. The parameter, a degree of scattering polarization, has been derived to identify the oil slicks on the sea wave. It depends on accurately knowing the Stokes parameter for the reflected light, and varies with the refractive index of the surface layer and viewing angles. The actual spilled oil has been measured by this model, and the oil film can be accurately identified at various angles. These preliminary results suggest that the potential of multi-angle polarization measurement of ocean surface needs further researches.

Dynamic failure mechanism of copper foil in laser dynamic flexible forming

Shen Zongbao, Zhang Lei, Li Pin, Liu Kai, Lin Youyu, Zhou Guoyang, Wang Yang, Zhang Jindian, Liu Huixia, Wang Xiao

Materials Science Poland

2020

Vol. 38, No. 4

684--692

Laser dynamic flexible forming (LDFF) is a novel high velocity forming (HVF) technology, in which the foil metal is loaded by laser shock wave. Strain localization is readily to occur around the bulge edge, which will result in the ultimate dynamic failure. In this work, the microstructures before and after dynamic fracture are characterized by transmission electron microscopy (TEM) to investigate the dynamic failure mechanism. The plastic deformation regions of copper foil are composed of shock compression, strain localization and bulge. Microstructure refinement was observed in three different plastic deformation regions, particularly, dynamic recrystallization (DRX) occurs in the strain localization and bulge regions. In bulge region, extremely thin secondary twins in the twin/matrix (T/M) lamellae are formed. The microstructure features in the strain localization region show that superplastic flow of material exists until fracture, which may be due to DRX and subsequent grain boundary sliding (GBS) of the recrystallized grains. The grain coarsening in strain localization region may degrade the material flowing ability which results in the dynamic fracture.

Research on Yarn Diameter and Unevenness Based on an Adaptive Median Filter Denoising Algorithm

Wang Xiao, Hou Ru-Meng, Gao Xiao-Yan, Xin Bin-Jie

Fibres & Textiles in Eastern Europe

2020

Vol. 28, no. 1 (139)

36--41

In this paper an adaptive median filtering denoising algorithm is proposed to measure yarn diameter and its unevenness. Images of nine different yarn samples were captured using one set of a self-developed yarn image acquisition system. Image separation of the background and yarn sections was conducted using a combination of adaptive median filtering, adaptive threshold segmentation and morphological processing. The noise-free yarn image was used for diameter detection of the subsequent yarn image and the discrimination of the yarn unevenness. Experimental results show that the testing data of yarn unevenness detection based on the adaptive median filter denoising algorithm is very consistent with the data using the traditional method. It is proved that the yarn detection method proposed, based on an adaptive median filter denoising algorithm, is feasible. It can be used to calculate yarn diameter accurately and measure yarn unevenness efficiently, so as to determine the quality of yarn appearance objectively.

W artykule zaproponowano algorytm odszumiania z adaptacyjnym filtrem medianowym (AMF) do pomiaru średnicy przędzy i jej nierówności. Obrazy dziewięciu różnych próbek przędzy zostały przechwycone przy użyciu jednego zestawu samodzielnie opracowanego systemu akwizycji obrazów przędzy. Rozdzielenie obrazu tła i odcinków przędzy przeprowadzono przy użyciu kombinacji AMF, adaptacyjnej segmentacji progowej i przetwarzania morfologicznego. Bezszumowy obraz przędzy wykorzystano do wykrywania średnicy przędzy i rozróżnienia nierówności przędzy. Wyniki eksperymentalne pokazały, że dane testowe dotyczące wykrywania nierówności przędzy w oparciu o zaproponowany algorytm miały wysoką zgodność z danymi uzyskanymi przy użyciu tradycyjnej metody. Algorytmu tego można użyć do dokładnego obliczenia średnicy przędzy i skutecznego pomiaru nierówności przędzy, aby obiektywnie określić jakość wyglądu przędzy.