The combat survivability is an essential factor to be considered in the development of recent military aircraft. Radar stealth and onboard electronic attack are two major techniques for the reduction of aircraft susce...The combat survivability is an essential factor to be considered in the development of recent military aircraft. Radar stealth and onboard electronic attack are two major techniques for the reduction of aircraft susceptibility. A tactical scenario for a strike mission is presented. The effect of aircraft radar cross section on the detection probability of a threat radar, as well as that of onboard jammer, are investigated. The guidance errors of radar guided surface to air missile and anti aircraft artillery, which are disturbed by radar cross section reduction or jammer radiated power and both of them are determined. The probability of aircraft kill given a single shot is calculated and finally the sortie survivability of an attack aircraft in a supposed hostile thread environment worked out. It is demonstrated that the survivability of a combat aircraft will be greatly enhanced by the combined radar stealth and onboard electronic attack, and the evaluation metho dology is effective and applicable.展开更多
Here we propose a new concept of"molecule aging":with some special treatment,a molecule could be"aged"by losing some unknown tiny particles or pieces from atoms in the molecule,Such"aging"...Here we propose a new concept of"molecule aging":with some special treatment,a molecule could be"aged"by losing some unknown tiny particles or pieces from atoms in the molecule,Such"aging"or loss of unknown tiny particles does not change apparently its molecular structure or chemical composition,but some physicochemical properties could be changed irreversibly.We further confirm such"molecule aging"via a long-term electron attacking to age water(H_(2)O)molecules.The IR spectra show no structural difference between the fresh water and the aged one,while the NMR spectra show that the electron attacking can decrease the size of water clusters.Such facts indicate that the electron attacking indeed can"affect"the structure of water molecule slightly but without damaging to its basic molecule frame.Further exploration reveals that the hydrogen evolution reaction(HER)activity of the aged water molecule is lower than the fresh water on the same Pt/C electrocatalyst.The density functional theory calculations indicate that the shortened O-H bond in H_(2)O indeed can present lower HER activity,so the observed size decrease of water clusters from NMR probably could be attributed to the shortening of O-H bond in water molecules.Such results indicate significantly that the molecule aging can produce materials with new functions for new possible applications.展开更多
文摘The combat survivability is an essential factor to be considered in the development of recent military aircraft. Radar stealth and onboard electronic attack are two major techniques for the reduction of aircraft susceptibility. A tactical scenario for a strike mission is presented. The effect of aircraft radar cross section on the detection probability of a threat radar, as well as that of onboard jammer, are investigated. The guidance errors of radar guided surface to air missile and anti aircraft artillery, which are disturbed by radar cross section reduction or jammer radiated power and both of them are determined. The probability of aircraft kill given a single shot is calculated and finally the sortie survivability of an attack aircraft in a supposed hostile thread environment worked out. It is demonstrated that the survivability of a combat aircraft will be greatly enhanced by the combined radar stealth and onboard electronic attack, and the evaluation metho dology is effective and applicable.
基金funded by the Key Research and Development Program sponsored by the Ministry of Science and Technology(MOST)(2022YFA1203400)National Natural Science Foundation of China(21925205,22072145,21372155,22005294,and 22102172)。
文摘Here we propose a new concept of"molecule aging":with some special treatment,a molecule could be"aged"by losing some unknown tiny particles or pieces from atoms in the molecule,Such"aging"or loss of unknown tiny particles does not change apparently its molecular structure or chemical composition,but some physicochemical properties could be changed irreversibly.We further confirm such"molecule aging"via a long-term electron attacking to age water(H_(2)O)molecules.The IR spectra show no structural difference between the fresh water and the aged one,while the NMR spectra show that the electron attacking can decrease the size of water clusters.Such facts indicate that the electron attacking indeed can"affect"the structure of water molecule slightly but without damaging to its basic molecule frame.Further exploration reveals that the hydrogen evolution reaction(HER)activity of the aged water molecule is lower than the fresh water on the same Pt/C electrocatalyst.The density functional theory calculations indicate that the shortened O-H bond in H_(2)O indeed can present lower HER activity,so the observed size decrease of water clusters from NMR probably could be attributed to the shortening of O-H bond in water molecules.Such results indicate significantly that the molecule aging can produce materials with new functions for new possible applications.
