Enhanced Pool Boiling Heat Transfer on Copper Foam Welded Surfaces

Enhanced pool boiling heat transfer of the porous structure is critical to the thermal management technology.In this paper,pool boiling heat transfer experiments are performed on copper foam welded surfaces in de-ionized water to investigate the effects of basic parameters of copper foam on heat transfer enhancement.Boiling phenomenon is observed to facilitate the understanding of enhancement mechanism.The results show that copper foam welded surfaces can significantly enhance the pool boiling heat transfer performance,reduce the boiling incipience temperature by 7-9℃,and reach two times heat transfer coefficient compared with smooth plain surfaces due to numerous nucleation sites,extended surface areas,and enhanced turbulent effect.Pore density and thickness of foam have two side effects on heat transfer.

基于模板匹配的生物触角电信号采集系统

生物(如蜜蜂)触角作为自然界最高效的感测系统,研究其感知机制是仿制高性能传感技术的关键。针对触角感知机制研究过程中存在的实验过程非标准化、手动操作干扰与效率低等问题,本文开发了一种适用于采集生物触角电信号(含触角反应时间信息)的自动化实验装置。首先,针对实验中昆虫头部的自动识别定位问题,建立了昆虫头部轮廓特征的图像模板,对昆虫头部实现了基于豪斯多夫(Hausdorff)法的模板匹配。然后,针对昆虫头部相对于标准检测位置的角度偏差问题,提出了基于长轴最小外接矩形的昆虫头部中轴线角度计算方法。最终,通过生物触角电信号采集装置采集得到昆虫触角接触试剂时产生的电信号。本文以蜜蜂为研究对象,实验结果表明:利用模板匹配可实现对蜜蜂头部准确率95.3%的快速匹配定位,蜜蜂头部的位姿角度纠正误差小于1°;触角与实验试剂的接触距离能够满足触角感知机制实验的要求;采集得到蜜蜂触角对蔗糖溶液的接触反应时间等参数与人工实验得到的结果一致。该系统在无人干扰的状态下实现了生物触角接触信号的有效采集,提高了生物触角感知机制实验的标准化水平,为研究与分析生物触角感知机制中所涉及的生物触角反应时间提供一种实验方法与装置。