China has the largest number of English users in the Expanding Circle, but little information is available about the exact number of users and their English proficiency. This paper presents a demographic profile of the users of English in China and the distribution of proficiency among the millions of English users. Also presented in the article is a sociolinguistic profile of the different uses of English in Chinese society. The authors contend that the primary function of English in China is not one of international communication, as has been believed in the literature, but one of social and economic mobility.

To study the lift generation mechanism and energy expenditure of clap and fling motion for insect flight, an unstructured mesh finite volume ALE method is developed. To solve mesh deformation problems during clap and fling motion, we adopt two mesh modification techniques. A 2D elliptical wing model is used to validate our solver by comparing the solutions to the already published numerical and experimental results. We analyzed the lift generation mechanism of clap and fling motion. The paper also released the comparison of Cl and energy expenditure between the single wing hovering motion and clap & fling. Conclusions have been made: the wake capture and delayed stall contribute to the lift generation while the rapid pitch mechanism decreases the lift. Clap and fling motion generate less lift but consume less energy, which means that it can generate more lift as consuming the same energy compared to single hovering motion by quantitative analysis.

In this paper, the necessary and sufficient conditions of a system with delayed feedback have been derived. In order to study the bifurcation and chaotic behavior, an asymptotic expansion of the solution in terms of the inverse delay time (TR-1) has been obtained. In long delay time limit, the first order effect in TR-1 is to prolong period of the motion. More interesting phenomena are about the higher order terms. The TR-2 terms lead to some hysteresis processes (some bistability) at each bifurcation point. And the third approximation in TR-1 influences the period-doubling bifurcation, i.e. the ratio of the periods below and at the transition point is not exact two. It is also shown that, some instable windows appear at merging points of the chaotic bands and lead to some mode-locked phenomena.

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