This note studies the optimality conditions of vector optimization problems involving generalized convexity in locally convex spaces. Based upon the concept of Dini set-valued directional derivatives, the necessary an...This note studies the optimality conditions of vector optimization problems involving generalized convexity in locally convex spaces. Based upon the concept of Dini set-valued directional derivatives, the necessary and sufficient optimality conditions are established for Henig proper and strong minimal solutions respectively in generalized preinvex vector optimization problems.展开更多
This work aims to compute stability derivatives in the Newtonian limit in pitch when the Mach number tends to infinity.In such conditions,these stability derivatives depend on the Ogive’s shape and not the Mach numbe...This work aims to compute stability derivatives in the Newtonian limit in pitch when the Mach number tends to infinity.In such conditions,these stability derivatives depend on the Ogive’s shape and not the Mach number.Generally,the Mach number independence principle becomes effective from M=10 and above.The Ogive nose is obtained through a circular arc on the cone surface.Accordingly,the following arc slopes are consideredλ=5,10,15,−5,−10,and−15.It is found that the stability derivatives decrease due to the growth inλfrom 5 to 15 and vice versa.Forλ=5 and 10,the damping derivative declines with an increase inλfrom 5 to 10.Yet,for the damping derivatives,the minimum location remains at a pivot position,h=0.75 for large values ofλ.Hence,whenλ=−15,the damping derivatives are independent of the cone angles for most pivot positions except in the early twenty percent of the leading edge.展开更多
The ignition tendency of diesel fuels is highly sensitive to ambient conditions and fuel properties.In this study,the ignition characteristics of different diesel surrogate fuels with the same derived cetane numbers(D...The ignition tendency of diesel fuels is highly sensitive to ambient conditions and fuel properties.In this study,the ignition characteristics of different diesel surrogate fuels with the same derived cetane numbers(DCN)were measured and compared in varied thermodynamic and oxidizing environments.The combustion pressures,heat release rates,ignition delays,and combustion delays of the test fuels were compared.The experimental results showed that the diesel surrogate fuels with the same DCNs exhibit similar ignition propensity at standard DCN test conditions.Further,for the test conditions of high cetane fuels,high ambient temperatures,and suficient oxygen concentrations,surrogate fuels with the same DCN have similar ignition behaviors,and using the DCN to evaluate fuel ignition tendency is appropriate.However,for the test conditions of low cetane fuels,low ambient temperatures,and reduced oxygen concentrations,different ignition behaviors are observed for the surrogate fuels with the same DCN,so at these conditions using DCN as the evaluation index for fuel ignition tendency may lead to higher uncertainty.展开更多
基金The National Natural Science Foundation for the Youth(10901004)the Zizhu Science Foundation of Beifang University of Nationalities(2011ZQY024)the Key Project of Science and Technology of Ministry of Education(212204)
文摘This note studies the optimality conditions of vector optimization problems involving generalized convexity in locally convex spaces. Based upon the concept of Dini set-valued directional derivatives, the necessary and sufficient optimality conditions are established for Henig proper and strong minimal solutions respectively in generalized preinvex vector optimization problems.
文摘This work aims to compute stability derivatives in the Newtonian limit in pitch when the Mach number tends to infinity.In such conditions,these stability derivatives depend on the Ogive’s shape and not the Mach number.Generally,the Mach number independence principle becomes effective from M=10 and above.The Ogive nose is obtained through a circular arc on the cone surface.Accordingly,the following arc slopes are consideredλ=5,10,15,−5,−10,and−15.It is found that the stability derivatives decrease due to the growth inλfrom 5 to 15 and vice versa.Forλ=5 and 10,the damping derivative declines with an increase inλfrom 5 to 10.Yet,for the damping derivatives,the minimum location remains at a pivot position,h=0.75 for large values ofλ.Hence,whenλ=−15,the damping derivatives are independent of the cone angles for most pivot positions except in the early twenty percent of the leading edge.
基金supported by the National Natural Science Foundation of China(Grant No.52022058)the Shanghai Science and Technology Committee(Grant No.19160745400)。
文摘The ignition tendency of diesel fuels is highly sensitive to ambient conditions and fuel properties.In this study,the ignition characteristics of different diesel surrogate fuels with the same derived cetane numbers(DCN)were measured and compared in varied thermodynamic and oxidizing environments.The combustion pressures,heat release rates,ignition delays,and combustion delays of the test fuels were compared.The experimental results showed that the diesel surrogate fuels with the same DCNs exhibit similar ignition propensity at standard DCN test conditions.Further,for the test conditions of high cetane fuels,high ambient temperatures,and suficient oxygen concentrations,surrogate fuels with the same DCN have similar ignition behaviors,and using the DCN to evaluate fuel ignition tendency is appropriate.However,for the test conditions of low cetane fuels,low ambient temperatures,and reduced oxygen concentrations,different ignition behaviors are observed for the surrogate fuels with the same DCN,so at these conditions using DCN as the evaluation index for fuel ignition tendency may lead to higher uncertainty.
