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Two-dimensional inlet is usually used in the wide-speed-range aircraft which has a higher flying velocity region. It is difficult to meet more requirements under both low-speed and high-speed flow conditions. Although the inlet perfor-mance could be improved by using jets to control shock waves on compression ramps, the existing jet excitation only push the shock wave toward the cowl, which may not achieve optimal performance. The optimization of jet control parameters is a significant problem. The effects of different optimization variables on inlet performance were investigated at Ma=6 based on Isight with the Hooke-Jeeves optimization method, in which different jet parameters were selected as optimization variables, flow coefficient was selected as constraint condition and maximum total pressure recovery coefficient was selected as objective function for optimization. The result show that the Hooke-Jeeves optimization method is able to optimize inlet with jet control. The optimized inlet can meet the requirements of flow coefficients. The total pressure recovery coefficient after optimizing the jet angle is increased by 18% compared to the inlet without jet, and the total pressure recovery coefficient after combination optimization is increased by 2.82% compared to only optimizing the jet angle.

In order to improve the ability to produce ethyl acetate, Nakazawaea ishiwadae GDMCC 60786 was mutagenized by atmospheric and room-temperature plasma (ARTP), ethyl methanesulfonate (EMS) and nitrosoguanidine (NTG). The mutants were sequentially screened by using a plate medium containing tributyrin, shake flask fermentation and addition of substrate. The genetic stability, hemolytic activity and in vitro drug resistance of the selected mutant were evaluated. Mutant N5, which was found to be able to produce a high yield of ethyl acetate, had good genetic stability and in vitro safety. After five successive passages, the average production of ethyl acetate was 764.54 mg/L, and the glucose conversion rate was 38.22%, which were 2.90 times and 25.03% higher than those observed with the original strain, respectively. When ethanol was used as a supplementary carbon source, the yield of ethyl acetate was 1 426.81 mg/L; however, upon the addition of acetic acid, N5 did not grow and lost the ability to produce esters, indicating that the strain was more tolerant to ethanol than acetic acid. Meanwhile, the activities of esterase, acetyl-CoA and alcohol acyltransferase in N5 cells were measured to reach a maximum value after 24 h. In summary, this study successfully constructed a set of suitable mutagenesis system for this strain.