摘要：质子交换膜燃料电池(PEMFC)由于其较高的发电效率和常温工作稳定性而被广泛关注。传统PEMFC由于电堆内部发电负载不均匀,容易发生“水淹”等问题。大多数研究基于在单电池层面上通过改变流场结构的方法优化PEMFC,但PEMFC工作时往往是组装电堆的形式。为此,设计带有竖直流道作为反应物进出口的单电池电堆结构,并提出一种新型的串联补偿流场,采用3个进气口,并具有首尾互相串联的3个流道,流道之间可以互相补偿反应物。使用ANSYS软件基于单层电堆层面进行仿真模拟研究,保证阳极是相同蛇形流场的情况下,阴极分别采用传统单流道蛇形流场和新型串联补偿流场,分析单层PEMFC电堆中多孔介质层(即扩散层(GDL)和催化层(CL))的电流密度、氧气质量分数、液态水饱和度、速度矢量和流道压力的分布规律。仿真结果表明:传统单流道蛇形流场单层PEMFC电堆中,整体管道压降较高,电流密度和氧气质量分数较高的区域集中在入口段,越靠近出口段分布越少;出口段液态水饱和度较高而速度矢量没有明显升高,液态水容易囤积在出口段;新型串联补偿流场,电流密度分布相对均匀,氧气质量分数有多个较高的区域,分布更加广泛,电化学反应更加充分,整体压降较低,在氧气质量分数较高的区域,速度矢量明显较高,促使氧气在多个流道间快速补充和扩散,整体液态水饱和度相对较低,出口段同样速度矢量较高,排水效果增强。

摘要：The art of cricket bowling is complex and arduous owing to the run-up and ball release time energy requirement to achieve speed and variations. Therefore, human bowlers cannot bowl for extended periods and numerous mechanical bowling machines have been built to help batsmen improve their skills during practice sessions. However, most of these existing machines are designed for spherical balls ignoring the distinguishing physical feature of a cricket ball: the raised equatorial seam, which makes it less of a sphere. The bowlers are known to often benefit from this seam in their pursuit to taking the batsmen's wicket by imparting swing, spin and bounce variations along-with other bowling variables. This lack of the seam consideration creates a void between human and mechanical bowling. In this work, we present design and development of an automatic bowling machine termed as ROBOWLER to make mechanical bowling more realistic. This machine ensures ball seam position as well as fulfills other constraints. Ball pitching and seam position accuracy results underscore the suitability of this design to enhance the capabilities of mechanical bowling.

摘要：本文将探索热带早期建筑的基本设计思想，意图让专业人员在头脑中重新树立这种思想，使他们能够完善现有的技术，遵循早期建筑的设计原理，创造出更生动的建筑设计。