Recently, retro-reflective (RR) materials have been proposed to be applied to building facades instead of diffuse reflective (DR) materials for urban heat island (UHI) mitigation. This paper focuses on analyzing the RR performance of glass bead RR material under different incident angles of light rays by using the proposed bead model. The results show that the retro-reflectivity of bead model increases when the incident angle changes from 10^o to 50^o with respect to the surface normal, and the retro-reflectivity begins to decrease when the incident angle exceeds 50^o with respect to the surface normal. Additionally, this study also analyzes the upward to downward reflection ratio by different incident angles. The results show that the upward to downward reflection ratio decreases and the specular reflection increases when the incident angle changes from small to large. There is strong relationship between upward to downward reflection ratio and incident angle, showing the correlation coefficient (R) is approximately 0.92. Moreover, the retro-reflectivity of bead on representative two days (Jun. 21 and Sep. 23, 2020) in Osaka is calculated using the proposed model. The results show that the retro-reflectivity gradually increases from morning to noon, reaches the maximum at noon, and then gradually decreases from noon.

近来，已提出将逆向反射（RR）材料应用于建筑立面，而不是用于城市热岛（UHI）缓解的漫反射（DR）材料。本文利用提出的玻璃珠模型，重点分析了玻璃珠RR材料在不同入射角下的RR性能。结果表明，当入射角相对于表面法线从10 ^o变为50 ^o时，珠子模型的后向反射率增加，而当入射角超过50 ^o时，后向反射率开始下降^。相对于表面法线。此外，本研究还分析了不同入射角下的向上反射率与向下反射率。结果表明，当入射角从小到大变化时，上下反射比减小，镜面反射增加。上下反射比与入射角之间存在很强的关系，表明相关系数（R）约为0.92。此外，使用所提出的模型计算了在代表性的两天（2020年6月21日和2020年9月23日），珠在大阪的回射率。结果表明，逆反射率从早晨到中午逐渐增加，在中午达到最大值，然后从中午逐渐减小。