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Li Q.,Guangxi University | Chen Y.,Guangxi University | Wei Y.,Zhejiang Forestry Institute | Lu Q.,Beihang University
International Journal of Non-Linear Mechanics | Year: 2011

In the study of dynamical systems, the spectrum of Lyapunov exponents has been shown to be an efficient tool for analyzing periodic motions and chaos. So far, different calculating methods of Lyapunov exponents have been proposed. Recently, a new method using local mappings was given to compute the Lyapunov exponents in non-smooth dynamical systems. By the help of this method and the coordinates transformation proposed in this paper, we investigate a two-degree-of-freedom vibro-impact system with two components. For this concrete model, we construct the local mappings and the Poincar mapping which are used to describe the algorithm for calculating the spectrum of Lyapunov exponents. The spectra of Lyapunov exponents for periodic motions and chaos are computed by the presented method. Moreover, the largest Lyapunov exponents are calculated in a large parameter range for the studied system. Numerical simulations show the success of the improved method in a kind of two-degree-of-freedom vibro-impact systems. © 2010 Elsevier Ltd. All rights reserved. Source


Shi C.,Zhejiang Forestry Institute | Zhu G.,Zhejiang Forestry Institute | Huang H.,Zhejiang University | Li Y.,Zhejiang Forestry Institute | And 2 more authors.
Journal of Chinese Institute of Food Science and Technology | Year: 2014

Styrax tonkinesis seed was squeezed and then raw oil was obtained. Raw oil was purified after the heating and suction filter steps to obtain refined oil. Then both oil types were used to process rat/mouse acute oral toxicity test and 3 chronic toxicity tests, including Ames, mouse bone marrow cell micro nuclear test and mouse sperm malformation test. Rat acute oral toxicology test results showed that the corresponding LD50 value of refined oil was improved than that of raw oil. For the female mice, the LD50 value increased from 6.81 g/kg to a maximum of 17.10 g/kg, while for the male, it increased from 7.94 g/kg to a maximum of approximately 10.80 g/kg. In contrast, the LD50 value of female mice improved more than that of male mice, revealed that female mice showed more tolerance to Styrax tonkinesis seed oil than male mice. Results of rat acute oral toxicity test suggested that difference of LD50 value between raw oil and refined oil was not significant. To raw oil, the LD50 of 20.00 g/kg was obtained for both male and female rat, whereas, to refined oil of Styrax tonkinesis, the value of LD50 was 17.10 g/kg for both the sexes. Although the difference between two values are not much, yet achieved the theoretical limit of non-toxic standard as in both case the LD50 value is greater than 15.0 g/kg. On the other hand, the results of Ames test, mouse bone marrow cell micro test and mouse sperm malformation test were negative with both the Styrax tonkinesis seed oil types. In conclusion, Styrax tonkinesis seed oil conforms to the national new resource food safety evaluation procedures, and has huge potential to develop some types of new resource food. Source

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