Friction stir processing and post process artificial ageing was successfully carried out on AA7075 with and without reinforcement of SiC particles producing defect free processed zone with uniform distribution of fill...Friction stir processing and post process artificial ageing was successfully carried out on AA7075 with and without reinforcement of SiC particles producing defect free processed zone with uniform distribution of filler material.Effect of SiC particle reinforcement and artificial ageing times on the microstructural modifications was characterized using optical and electron microscopy,electron backscattered diffraction and X-Ray diffraction.Hardness,impact and wear tests were carried out to investigate mechanical behaviour before and after processing.Reinforcement of SiC particles during FSP and subsequent age hardening treatment brought about nearly twofold increase in hardness and impact toughness values by the combined effect of grain refinement,Zener pinning,dispersion strengthening and precipitation hardening.Significant improvement in wear resistance in terms of wear loss was also observed after processing compared to the reference material AA7075-T6.Fractured surface of post FSP age hardened AA7075 alloy exhibited features of ductile fracture during Charpy impact test.展开更多
针对目前遥感影像中烤烟边缘识别效率低且识别精度低等问题,文章提出一种融合轻量化ASPP和U-Net框架的遥感影像烤烟种植区域提取模型。首先,该模型在U-Net编码层和解码层连接处加入轻量化空洞空间金字塔池化模块;其次,该模型将线性整流...针对目前遥感影像中烤烟边缘识别效率低且识别精度低等问题,文章提出一种融合轻量化ASPP和U-Net框架的遥感影像烤烟种植区域提取模型。首先,该模型在U-Net编码层和解码层连接处加入轻量化空洞空间金字塔池化模块;其次,该模型将线性整流函数(Rectified Linear Unit,ReLU)替换为ReLU6激活函数,能够在低精度计算时压缩动态范围,从而使算法更具鲁棒性;最后,该模型通过采用形态学孔洞填充构建标签图后处理算法,实现分割结果优化。为验证该模型框架的有效性和适用性,文章采用无人机遥感影像作为实验数据集,构建与传统语义分割模型的对比实验以及消融实验等。实验结果表明,通过与FCN、U-Net、SegNet和DeepLabV3+等传统语义分割算法相比较,文章提出的模型获得了较好的分割效果,其像素准确率和平均交并比分别为93.7%和84.1%。此外,该模型在保证模型精度的情况下,还能够提高模型的计算速度。展开更多
基金The authors would like to acknowledge National Facility for Texture and OIM(A DST-IRPHA project),IIT Mumbai for XRD and EBSD measurements.One of the authors VDH would like to acknowledge Science and Engineering Research Board(SERB)for financial assistance(EEQ/2016/000422)to carry out project work.
文摘Friction stir processing and post process artificial ageing was successfully carried out on AA7075 with and without reinforcement of SiC particles producing defect free processed zone with uniform distribution of filler material.Effect of SiC particle reinforcement and artificial ageing times on the microstructural modifications was characterized using optical and electron microscopy,electron backscattered diffraction and X-Ray diffraction.Hardness,impact and wear tests were carried out to investigate mechanical behaviour before and after processing.Reinforcement of SiC particles during FSP and subsequent age hardening treatment brought about nearly twofold increase in hardness and impact toughness values by the combined effect of grain refinement,Zener pinning,dispersion strengthening and precipitation hardening.Significant improvement in wear resistance in terms of wear loss was also observed after processing compared to the reference material AA7075-T6.Fractured surface of post FSP age hardened AA7075 alloy exhibited features of ductile fracture during Charpy impact test.
文摘针对目前遥感影像中烤烟边缘识别效率低且识别精度低等问题,文章提出一种融合轻量化ASPP和U-Net框架的遥感影像烤烟种植区域提取模型。首先,该模型在U-Net编码层和解码层连接处加入轻量化空洞空间金字塔池化模块;其次,该模型将线性整流函数(Rectified Linear Unit,ReLU)替换为ReLU6激活函数,能够在低精度计算时压缩动态范围,从而使算法更具鲁棒性;最后,该模型通过采用形态学孔洞填充构建标签图后处理算法,实现分割结果优化。为验证该模型框架的有效性和适用性,文章采用无人机遥感影像作为实验数据集,构建与传统语义分割模型的对比实验以及消融实验等。实验结果表明,通过与FCN、U-Net、SegNet和DeepLabV3+等传统语义分割算法相比较,文章提出的模型获得了较好的分割效果,其像素准确率和平均交并比分别为93.7%和84.1%。此外,该模型在保证模型精度的情况下,还能够提高模型的计算速度。
