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Shen, Yunwen; Liu, Mengjun; Dong, Haijun
In some mechanical nonlinear systems, the transient motion will be undergoing a very long process and the attractorbasin boundaries are so complicated that some difficulties occur in analyzing the system global behavior. To solve this problem a mixed cell mapping method based on the point mapping and the principle of simple celll mapping is developed. The algorithm of the mixed cell mapping is studied. A dynamic model of a gear pair is established with the backlash, damping, transmission error and the timevarying stiffness taken into consideration. The global behaviors of this system are analyzed. The coexistence of the system attractors and the respective attractorbasin of each attractor with different parameters are obtained, thus laying a theoretical basis for improvement of the dynamic behaviors of gear system.
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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
2 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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Chen, Zhenpeng; Zhang, Rui; Sun, Yeying; Liu, Tingjin
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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
Cao, Xiankun; Shao, Tianmin; Wen, Shizhu; Qing, Tao; Qi, Feng
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TiB2 thin film was deposited by laserarc deposition method on the surface of single crystalline silicon. The morphology, composition, structure and microtribological properties of the film were studied by using XPS, XRD and atomic force/friction force microscope (AFM/FFM). The results show that TiB2 (100) preferred growth on the Si(100) substrate, TiB2(001) preferred growth on the Si(111) substrate. The TiB2 thin film was composed of TiB2 and a small amount of TiO2. The friction coefficient of TiB2 film on substrates Si (100) and Si(111) in microtribological process were 0.087 and 0.073, respectively. TiB2 thin film displayed distinct ability of antiscratch and wearresistance.
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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
11 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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