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镁掺杂对二氧化钒薄膜光学性能的影响
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作者 赵鑫 康同同 +3 位作者 梁潇 邬春阳 周阳 秦俊 《表面技术》 EI CAS CSCD 北大核心 2024年第20期183-189,222,共8页
目的通过在二氧化钒薄膜中掺杂镁元素,实现高优值光学相变材料的制备。方法通过脉冲激光沉积方法在(0001)氧化铝单晶衬底上沉积二氧化钒外延薄膜,进一步采用交叉打靶的方法沉积不同镁掺杂浓度的二氧化钒外延薄膜;通过高分辨XRD和TEM表... 目的通过在二氧化钒薄膜中掺杂镁元素,实现高优值光学相变材料的制备。方法通过脉冲激光沉积方法在(0001)氧化铝单晶衬底上沉积二氧化钒外延薄膜,进一步采用交叉打靶的方法沉积不同镁掺杂浓度的二氧化钒外延薄膜;通过高分辨XRD和TEM表征镁掺杂外延二氧化钒薄膜的晶体结构和微观原子分布,采用XPS表征表面原子化学态,采用光谱椭偏仪表征不同镁掺杂浓度的二氧化钒外延薄膜的折射率和消光系数,并计算获得光学优值;最后构建第一性原理计算模型得到镁掺杂对二氧化钒薄膜光学优值影响的机理。结果制备出4种不同镁掺杂浓度的外延二氧化钒薄膜,分析了镁掺杂对薄膜相变前后的晶体取向和微观原子结构的影响,分析了薄膜中镁和钒元素的价态,分析了镁掺杂对单斜相和金红石相光学常数和光学优值的影响,从电子态密度分布分析了镁掺杂对提升材料光学优值的原因。结论镁掺杂二氧化钒与氧化铝衬底的外延关系为(020)_(VO_(2))//(0006)_(Al_(2)O_(3)),随着镁掺杂浓度的提高,金红石相二氧化钒薄膜的光学损耗降低,且中红外波段的光学优值提升。在11.9%(原子数分数)掺杂量时光学优值比未掺杂提高3.7倍。第一性原理计算表明,高光学优值是源于镁掺杂后导带周围电子态密度的局部化。 展开更多
关键词 二氧化钒 相变材料 镁掺杂 光学优值 脉冲激光沉积
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A Fast Underwater Optical Image Segmentation Algorithm Based on a Histogram Weighted Fuzzy C-means Improved by PSO 被引量:4
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作者 王士龙 徐玉如 庞永杰 《Journal of Marine Science and Application》 2011年第1期70-75,共6页
The S/N of an underwater image is low and has a fuzzy edge.If using traditional methods to process it directly,the result is not satisfying.Though the traditional fuzzy C-means algorithm can sometimes divide the image... The S/N of an underwater image is low and has a fuzzy edge.If using traditional methods to process it directly,the result is not satisfying.Though the traditional fuzzy C-means algorithm can sometimes divide the image into object and background,its time-consuming computation is often an obstacle.The mission of the vision system of an autonomous underwater vehicle (AUV) is to rapidly and exactly deal with the information about the object in a complex environment for the AUV to use the obtained result to execute the next task.So,by using the statistical characteristics of the gray image histogram,a fast and effective fuzzy C-means underwater image segmentation algorithm was presented.With the weighted histogram modifying the fuzzy membership,the above algorithm can not only cut down on a large amount of data processing and storage during the computation process compared with the traditional algorithm,so as to speed up the efficiency of the segmentation,but also improve the quality of underwater image segmentation.Finally,particle swarm optimization (PSO) described by the sine function was introduced to the algorithm mentioned above.It made up for the shortcomings that the FCM algorithm can not get the global optimal solution.Thus,on the one hand,it considers the global impact and achieves the local optimal solution,and on the other hand,further greatly increases the computing speed.Experimental results indicate that the novel algorithm can reach a better segmentation quality and the processing time of each image is reduced.They enhance efficiency and satisfy the requirements of a highly effective,real-time AUV. 展开更多
关键词 underwater image image segmentation autonomous underwater vehicle (AUV) gray-scale histogram fuzzy C-means real-time effectiveness sine function particle swarm optimization (PSO)
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