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By
Ma, Jianbo; Xu, Jin; Cao, Zhibin
3 Citations
In this paper a method of autonomous orbit determination using star sensor is studied. By building relatively consummate dynamical models which simulate attitude motion of satellite and observation from satellite to background stars, the simulant computation of this method is executed, and it is shown that the method of autonomous orbit determination is feasible. Academic and calculation analyses have been done for the relation between the direction of star sensor with respect to statellitebody coordinate system and the accuracy of autonomous orbit determination.
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By
Zhang, Dongming; Luo, Jisheng; Zhou, Heng
1 Citations
Based on the theoretical model for a single coherent structure in the wall region of a turbulent boundary layer, we studied the interaction of two coherent structures by direct numerical simulation in order to explain the mechanism for the formation of lowspeed streaks.
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By
Liu, Chun; Zhang, Laibin; Wang, Zhaohui
Condition monitoring and life prediction of the vehicle engine is an important and urgent problem during the vehicle development process. The vibration signals that are closely associated with the engine running condition and its development trend are complex and nonlinear. The chaos theory is used to treat the nonlinear dynamical system recently. A novel chaos method in conjunction with SVD (singular value decomposition) denoising skill are used to predict the vibration time series. Two types of time series and their prediction errors are provided to illustrate the practical utility of the method.
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By
Chen, Zhenpeng; Zhang, Rui; Sun, Yeying; Liu, Tingjin
Show all (4)
The error propagation features with Rmatrix model fitting^{7}Li,^{11}B and^{17}O systems have been researched systematically. Some laws of error propagation have been revealed, an experience formula for describing standard error propagation has been established, and the most possible error range for evaluated standard cross section of^{6}Li (n, α),^{10}B (n, α) and^{10}B (n, α_{1}) has been determined.
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By
Lin, Liu; Xin, Wang
While approaching the target body, the deepspace probe is orbiting hyperbolically before the maneuver. We discuss the variation of perturbed hyperbolic orbit using the method similar to that used in elliptic orbit. Ephemeris calculating and orbit control will benefit from the given analytical solution.
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By
Wang, Jing; Zeng, Jinyan
3 Citations
The symmetry and m partialwave analysis for twodimensional (2D) Coulombscattering is investigated. As a function of energyE, the m partialwave scattering amplitudef_{m}(θ) is analytically continuated to the, negativeE (complexk) plane, and it is found that the bound state energy eigenvalues (E<0) are just located at the poles off_{m}(θ) on the positive imaginaryk axis as is expected. In addition, as a function of m,f_{m}(θ) is analytically continuated to the complex m plane, the bound state energy eigenvalues are just located at the poles off_{m}(θ) on the positive real m axis.
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By
Feng, Shaotong; Han, Dianrong; Ding, Heping
By means of experimental technique of optical fractional Fourier transform, we have determined the Hurst exponent of a regular selfaffine fractal pattern to demonstrate the feasibility of this approach. Then we extend this method to determine the Hurst exponents of some irregular selfaffine fractal patterns. Experimental results show that optical fractional Fourier transform is a practical method for analyzing the selfaffine fractal patterns.
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By
Sun, WeiGuo; Fan, QunChao; Ren, WeiYi
12 Citations
The molecular dissociation energies of some electronic states of hydride and N_{2} molecules were studied using a parameterfree analytical formula suggested in this study and the algebraic method (AM) proposed recently. The results show that the accurate AM dissociation energies D_{e}^{AM}
agree excellently with experimental dissociation energies D_{e}^{expt}
, and that the dissociation energy of an electronic state such as the 2^{3}Δ_{g} state of ^{7}Li_{2} whose experimental value is not available can be predicted using the new formula.
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By
Xiong, ZhengYe; Tang, Qiang; Zhang, ChunXiang
12 Citations
Li_{2}B_{4}O_{7} (LBO):Cu,Ag,Mg phosphors have been prepared by the sintering technique. The roles of the Ag and Mg dopants in the phosphors have been studied using the methods of thermoluminescence (TL) glow curves and TL 3D spectra. The results indicated that proper concentrations of Ag and Mg can enhance the TL of LBO:Cu. It was also indicated that the intensity of TL peak at ∼130°C is reduced with the increasing Ag concentration, and enhanced with the increasing Mg concentration. From the TL 3D spectra, three emission bands (λ_{1} = 421 nm, λ_{2} = 380 nm, λ_{3} = 350 nm) were observed: the intensity of low energy emission band is reduced and that of the high energy is enhanced with the increasing dopant Ag; on the contrary, the intensity of low energy emission band is enhanced and that of the high energy one is reduced with the increasing dopant Mg.
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By
Zheng, Renrong; Chen, Zhiqian; Zhu, Shunquan
The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spinorbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.
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