多层混合填充吸波材料的三目标粒子群优化

使用多层结构来离散自由空间到金属衬底之间理想的连续阻抗变化过程是吸波材料设计的重要方法之一,较多层数的精细结构能够更好地逼近这一连续变化过程以获得更理想的吸波性能,但也会增加工程实现成本和复杂度。因此,实际工程中往往需要在结构层数和逼近精度等诸多相互矛盾的因素之间寻求平衡。文中采用石墨烯纳米片(GNS)/片状羰基铁颗粒(FCI)混合填充的多层吸波材料,在由极化无关的宽带宽角吸波性能、FCI填充量以及最终层数这三个指标所张成的三维目标空间中,基于粒子群优化对多层吸波材料进行了优化设计。结果显示,相比于吸波性能和磁性粒子填充量二维空间中的设计结果,在FCI填充量仅需增加不到3.3 wt%的情况下,即可使所需层数下降50%并保持原有吸波能力的98%;不进行优化的GNS填充量仅增加0.6 wt%,且得益于层数的显著减少,吸波材料的总厚度降低了14%,综合性能也提高了27.9%。此外,与其它不同优化策略的系统进行了对比,文中设计为混合填充吸波材料的多目标优化提供了一定参考。

Optimum Determination of Partial Transmission Ratios of Three-Step Helical Gearboxes for Getting Minimum Cross Section Dimension

This paper presents a new study on optimum calculation of partial ratios of three-step helical gearboxes. The chosen objective function is the cross section dimension of the gearbox. In solving the optimization problem, the design equation for pitting resistance of a gear set was investigated and equations on moment equilibrium condition of a mechanic system including three gear units and their regular resistance condition are analyses. From the results of the study, effective formula for determination of the partial ratios of three-step helical gearboxes is introduced. As the formulas are explicit, the partial ratios can be calculated accurately and simply.