No abstract

Chinese fir [Cunninghamia lanceolata (Lamb.) Hook] is an important evergreen coniferous tree species that is widely distributed in many southern provinces of China and has important economic value. The Chinese fir accounts for 1/4 and 1/3 of the total artificial forest area and stock volume, respectively. Red-heart Chinese fir is popular in the market because of its high density and red heartwood. The long-growth cycle hindered the breeding process of Chinese fir, while molecular marker-assisted breeding could accelerate it. However, Chinese fir, a perennial conifer species, has a large genome, which has not yet been published. In this study, the growth-related traits and secondary metabolite contents of red- and white-heart Chinese fir were measured and found to be different between them. There are extremely significant differences among growth-related traits (p < 0.001), but secondary metabolite contents have different correlations due to differences in chemical structure. Moreover, genotype effect analysis of the substantially correlated single nucleotide polymorphisms (SNPs) revealed that most of the loci related to each growth-related traits were different from each other, indicating a type specificity of the genes regulated different growth-related traits. Furthermore, among the loci related to secondary metabolite contents, nine loci associated with multiple metabolite phenotypes such as Marker21022_4, Marker21022_172, Marker24559_31, Marker27425_37, Marker20748_85, Marker18841_115, Marker18841_198, Marker65846_146, and Marker21486_163, suggesting the presence of pleiotropic genes. This study identified the potential SNP markers associated with secondary metabolites in Chinese fir, thus setting the basis for molecular marker-assisted selection.

The main function of nacelle intake is to provide the fan with stable and uniform flow in a wide operating range. The next-generation civil turbofan engine requires nacelle intake to have shorter length and larger lip thickness. However, the thicker lip is, the higher the probability flow to be separated, and the total pressure distortion disturbance is quickly transmitted to the fan, which causes the increase of the inhalation of distortion. Eventually, the stability of the engine is destroyed. Therefore, it is necessary to study the distortion of the nacelle intake and the coupling effect of the nacelle intake and fan. Aiming at the coupling effect of intake distortion of the nacelle intake and fan under a high angle of attack, the research focus on the flow characteristics of isolated nacelle intake and intake/ fan integrated model under different angle of attack. Results show that the intake presents different flow patterns under different Ma and mass flow rate; however, the interaction between the intake and fan presents a similar pattern. The presence of fan leads to the flow swirl angle changes significantly and mass redistribution. The studies also indicate that the intake distortion sensitivity level decrease with the fan coupling. The sensitivity of the distortion index decreases from 4.057% to 0.315% under cruise condition; the sensitivity of the distortion index decreases from 0.186% to 0.1423% under take-off condition.