基于偏振视觉的轴承曲面划痕缺陷检测

针对轴承工作曲面划痕缺陷成像的问题,提出了一种采用正交偏振成像的检测方法.首先,采用偏振相机结合正交偏振理论获取光滑轴承曲面图像,利用形态学滤波差分运算消除不均匀背景;然后,采用特定滤波和增强方式对SWT产生的分解系数进行保边去噪和增强,并进行图像重构;最后,对其中的缺陷特征进行分割处理.结果表明:采用线偏振光源照射光...     

中国城市老旧社区非正式绿地改造及其公众感知研究

Existing large-scale urban green spaces in a low distribution density can hardly meet citizens’ diverse and growing needs for convenient access and sharing modes, especially to those living in old communities. Compared with formal green spaces, informal green space (IGS) is a new urban green infrastructure contributing to the city’s coconstruction, co-governance, and co-sharing. This study was conducted based on a typical old residential community in the historic city center of Beijing, namely Beitaipingzhuang Neighborhood, acquired residents’ opinions, evaluation, and willing to participate in IGS governance, and investigated their preference of IGS renovation, activity, and the positive / negative perception of IGS scenarios through virtual renovation proposals upon the real scenes. According to the survey result, most residents have been aware of the existing IGS in communities as well as the advantages and disadvantages, and shown their support to IGS cogovernance; residents’ preference of IGS renovation scenarios is significantly affected by environmental factors—residents prefer the green spaces with a higher plant richness, a larger crown size, and a more complete leisure facility system. Therefore, residents’ positive perception can be enhanced through enriching plant species, adjusting green space ratio, and introducing proper planting patterns and facility types. Finally, the authors put forward several research interests for following up so as to provide targeted guidelines for the optimization of urban living environment.