In this paper, the relative orbital configurations of satellites in formation flying with non-perturbation and J<SUB>2</SUB> perturbation are studied, and an orbital elements method is proposed to obtain t...In this paper, the relative orbital configurations of satellites in formation flying with non-perturbation and J<SUB>2</SUB> perturbation are studied, and an orbital elements method is proposed to obtain the relative orbital configurations of satellites in formation. Firstly, under the condition of non-perturbation, we obtain many shapes of relative orbital configurations when the semi-major axes of satellites are equal. These shapes can be lines, ellipses or distorted closed curves. Secondly, on the basis of the analysis of J<SUB>2</SUB> effect on relative orbital configurations, we find out that J<SUB>2</SUB> effect can induce two kinds of changes of relative orbital configurations. They are distortion and drifting, respectively. In addition, when J<SUB>2</SUB> perturbation is concerned, we also find that the semi-major axes of the leading and following satellites should not be the same exactly in order to decrease the J<SUB>2</SUB> effect. The relationship of relative orbital elements and J<SUB>2</SUB> effect is obtained through simulations. Finally, the minimum relation perturbation conditions are established in order to reduce the influence of the J<SUB>2</SUB> effect. The results show that the minimum relation perturbation conditions can reduce the J<SUB>2</SUB> effect significantly when the orbital element differences are small enough, and they can become rules for the design of satellite formation flying.展开更多
a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radic...a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radicals in plasma originating from source gases dissociation are analyzed by relative irradiance measurement. The bonding configurations and binding state of a-C:F films are measured with Fourier-transformed infrared spectrometer (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show that a-C:F films are mainly composed of CF radical at lower powers but of CF2 radical at higher powers. The deposition of films is related to the radicals generated in plasma and the main bonding configurations are dependent on the ratio of CF to CF2 radicals in films.展开更多
A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(...A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(residual dipolar coupling)-based NMR and DFT-supported chiroptical spectroscopy.It is worth to note that in this study without the aid of the RDC analysis,an unambiguous determination of configuration and conformation was not feasible due to the excessive conformational possibilities of this open-chain compound.展开更多
基金The project supported by the National Natural Science Foundation of China(10202008)Specialized Research Fund for the Doctoral Program of Higher Education(20020003024)
文摘In this paper, the relative orbital configurations of satellites in formation flying with non-perturbation and J<SUB>2</SUB> perturbation are studied, and an orbital elements method is proposed to obtain the relative orbital configurations of satellites in formation. Firstly, under the condition of non-perturbation, we obtain many shapes of relative orbital configurations when the semi-major axes of satellites are equal. These shapes can be lines, ellipses or distorted closed curves. Secondly, on the basis of the analysis of J<SUB>2</SUB> effect on relative orbital configurations, we find out that J<SUB>2</SUB> effect can induce two kinds of changes of relative orbital configurations. They are distortion and drifting, respectively. In addition, when J<SUB>2</SUB> perturbation is concerned, we also find that the semi-major axes of the leading and following satellites should not be the same exactly in order to decrease the J<SUB>2</SUB> effect. The relationship of relative orbital elements and J<SUB>2</SUB> effect is obtained through simulations. Finally, the minimum relation perturbation conditions are established in order to reduce the influence of the J<SUB>2</SUB> effect. The results show that the minimum relation perturbation conditions can reduce the J<SUB>2</SUB> effect significantly when the orbital element differences are small enough, and they can become rules for the design of satellite formation flying.
文摘a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radicals in plasma originating from source gases dissociation are analyzed by relative irradiance measurement. The bonding configurations and binding state of a-C:F films are measured with Fourier-transformed infrared spectrometer (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show that a-C:F films are mainly composed of CF radical at lower powers but of CF2 radical at higher powers. The deposition of films is related to the radicals generated in plasma and the main bonding configurations are dependent on the ratio of CF to CF2 radicals in films.
基金Support by the National Natural Science Foundation of China(U1132607)to J.K.L.the DFG(Forschergruppe FOR 934)to C.Gas well as the Chinese/German foundation(GZ1104)to H.S.and C.G.is acknowledged.
文摘A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(residual dipolar coupling)-based NMR and DFT-supported chiroptical spectroscopy.It is worth to note that in this study without the aid of the RDC analysis,an unambiguous determination of configuration and conformation was not feasible due to the excessive conformational possibilities of this open-chain compound.
