摘要：Cathode activity plays an important role in the improvement of the microbial fuel cells on ocean floor （BMFCs）. A comparison study between Rayon-based （CF-R） and PAN-based carbon fiber （CF-P） cathodes is conducted in the paper. The two carbon fibers were heat treated to improve cell performance （CF-R-H ＆ CF-P-H）, and were used to build a new BMFCs structure with a foamy carbon anode. The maximum power density was 112.4mWm-2 for CF-R-H, followed by 66.6mWm-2 for CF-R, 49.7 mWm-2 for CF-P-H and 21.6mWm-2 for CF-P respectively. The higher specific area and deep groove make CF-R have a better power output than with CF-P. Meanwhile, heat treatment of carbon fiber can improve cell power, nearly two-fold higher than heat treatment of plain fiber. This improvement may be due to the quinones group formation to accelerate the reduction of oxygen and electron transfer on the fiber surface in the three phase boundary after heat treatment. Compared to PAN-based carbon fiber, Rayon-based carbon fiber would be preferentially selected as cathode in novel BMFCs design due to its high surface area, low cost and higher power. The comparison research is significant for cathode material selection and cell design.

摘要：陶瓷复合装甲主要由陶瓷层和背板层组成,广泛应用于冲击防护.然而,目前仍缺乏背板层在提高陶瓷复合装甲系统防弹性能方面的定量认识和分析.本文以B4C/UHMWPE双层装甲体系为例,从理论上系统地研究了UHMWPE层在提高陶瓷复合装甲弹道阻力方面的增强机理和适合UHMWPE厚度的选取.开发并验证了预测双层装甲系统剩余速度的理论模型.具体而言,分别从理论上获得与塑性、断裂和摩擦相关的耗散能以及由弹性应变能和动能组成的储存能.理论结果表明,随着UHMWPE层厚度的增加,耗散能单调增加,而储存能则先增加后减少,并会出现一个转折点,这是由于储存能的主导机制由系统固有的最大储存能转变为剩余动能.此外,对于给定的弹道阻力,根据存储能的转变提出了为降低面密度的最佳UHMWPE厚度的参考值,这与陶瓷厚度、冲击速度和弹丸质量有关.本文的研究有助于指导陶瓷复合装甲的轻量化设计.

摘要：Soft rock control is a big challenge in underground *** for this problem,a high-strength support technique of confined concrete(CC)arches is proposed and studied in this *** on full-scale mechanical test system of arch,research is made on the failure mechanism and mechanical properties of CC ***,a mechanical calculation model of circular section is established for the arches with arbitrary section and unequal rigidity;a calculation formula is deduced for the internal force of the arch;an analysis is made on the influence of different factors on the internal force of the arch;and a calculation formula is got for the bearing capacity of CC arch through the strength criterion of bearing *** numerical calculation and laboratory experiment,the ultimate bearing capacity and internal force distribution is analyzed for CC *** research results show that:1)CC arch is 2.31 times higher in strength than the U-shaped steel arch and has better stability;2)The key damage position of the arch is the two sides;3)theoretical analysis,numerical calculation and laboratory experiment have good consistency in the internal force distribution,bearing capacity,and deformation and failure modes of the *** of that verifies the correctness of the theoretical *** on the above results,a field experiment is carried out in Liangjia *** with the U-shaped steel arch support,CC arch support is more effective in surrounding rock deformation *** research results can provide a basis for the design of CC arch support in underground engineering.