Research was conducted on topmouth culter (Culter alburnus) grown in ponds and lakes as well as wild types in order to determine their chemical composition and nutritional value. There are three types of fish that dif...Research was conducted on topmouth culter (Culter alburnus) grown in ponds and lakes as well as wild types in order to determine their chemical composition and nutritional value. There are three types of fish that differ in their proximate composition, amino acids, fatty acids, and minerals. Wild fish had a significantly lower crude lipid contents than cultured fish (P P ∑PUFAs) showed an obviously opposite trend. As compared with cultured fish, wild fish had significantly higher levels of n-3 PUFAs, arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahxaenoic acid (DHA) (P P > 0.05), except for Na, Fe and Se. In conclusion, diet composition and external aqueous environment may determine the differences between wild and cultured topmouth culter.展开更多
Maximum expansion angle is the primary parameter for the design of expansion section of hypersonic quiet nozzle. According to the quantity of maximum expansion angle, expansion section could be classified as fast expa...Maximum expansion angle is the primary parameter for the design of expansion section of hypersonic quiet nozzle. According to the quantity of maximum expansion angle, expansion section could be classified as fast expansion and slow expansion. In order to diminish the effect of instability of Görtler vortex, gradually, slow expansion was employed for quiet nozzle design. Based on the favorable pressure effect, the maximum expansion angle is optimized in this paper, and a considerable selective session of maximum expansion angle is obtained. The trend that slow expansion is employed instead of fast expansion is explained, and a new method is established for aerodynamic optimization of expansion section contour in a quiet nozzle.展开更多
文摘Research was conducted on topmouth culter (Culter alburnus) grown in ponds and lakes as well as wild types in order to determine their chemical composition and nutritional value. There are three types of fish that differ in their proximate composition, amino acids, fatty acids, and minerals. Wild fish had a significantly lower crude lipid contents than cultured fish (P P ∑PUFAs) showed an obviously opposite trend. As compared with cultured fish, wild fish had significantly higher levels of n-3 PUFAs, arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahxaenoic acid (DHA) (P P > 0.05), except for Na, Fe and Se. In conclusion, diet composition and external aqueous environment may determine the differences between wild and cultured topmouth culter.
文摘Maximum expansion angle is the primary parameter for the design of expansion section of hypersonic quiet nozzle. According to the quantity of maximum expansion angle, expansion section could be classified as fast expansion and slow expansion. In order to diminish the effect of instability of Görtler vortex, gradually, slow expansion was employed for quiet nozzle design. Based on the favorable pressure effect, the maximum expansion angle is optimized in this paper, and a considerable selective session of maximum expansion angle is obtained. The trend that slow expansion is employed instead of fast expansion is explained, and a new method is established for aerodynamic optimization of expansion section contour in a quiet nozzle.
