Examination of the Thermal Cloaking Effectiveness with Layered Engineering Materials

The concentrically layered thermal cloaks with isotropic materials could realize the equivalent thermal cloaking effect with Pendry＇s cloak, while the effectiveness is scarcely investigated quantitatively. Here we examine the cloaking effectiveness quantitatively by evaluating the standard deviation of the temperature difference between the simulated plane with the layered thermal cloak and Pendry＇s thermal cloak. The design rules for the isotropic materials in terms of thermal conductivity and layer thickness are presented. The present method could quan- titatively evaluate the cloaking effectiveness, and could open avenues for analyzing the cloaking effect, detecting the （anti-） cloaks, etc.

超薄离心式微泵的水力设计及优化

超薄离心式微泵,作为便携电子设备中的液冷散热系统的关键部件,它的水力部件的尺寸受到严格限制,结构特性导致轮毂比很大,而且小流量大扬程的技术要求导致整机的比转速极低。运用传统的设计方法很难设计出高效并且性能优异的水力模型。本文采用速度系数法和CFD水力仿真技术相结合的方法,探究了叶片长度,叶片出口宽度,叶片数等参数对于微泵水力性能的影响。最后得到一个优化的超薄离心式微型泵的水力模型。