The normal hypervelocity impact of an Al-thin plate by an Al-sphere was numerically simulated by using the adaptive smoothed particle hydrodynamics (ASPH) method. In this method, the isotropic smoothing algorithm of s...The normal hypervelocity impact of an Al-thin plate by an Al-sphere was numerically simulated by using the adaptive smoothed particle hydrodynamics (ASPH) method. In this method, the isotropic smoothing algorithm of standard SPH is replaced with anisotropic smoothing involving ellipsoidal kernels whose axes evolve automatically to follow the mean particle spacing as it varies in time, space, and direction around each particle. Using the ASPH, the anisotropic volume changes under strong shock condition are captured more accurately and clearly. The sophisticated features of meshless and Lagrangian nature inherent in the SPH method are kept for treating large deformations, large inhomogeneities and tracing free surfaces in the extremely transient impact process. A two-dimensional ASPH program is coded with C++. The developed hydrocode is examined for example problems of hypervelocity impacts of solid materials. The results obtained from the numerical simulation are compared with available experimental ones. Good agreement is observed.展开更多
In the framework of D6rnyei＇s L2 Motivational Self System （hereafter abbreviated as L2MSS）, this paper makes an empirical survey among learners of English in China, investigating the parameters of the three interna...In the framework of D6rnyei＇s L2 Motivational Self System （hereafter abbreviated as L2MSS）, this paper makes an empirical survey among learners of English in China, investigating the parameters of the three internal components of L2MSS among learners of various L2 proficiency levels. It is found that the strongest predictor among the three internal components of L2MSS contributing to the L2 Learning Motivation is closely related to learners＇ L2 proficiency levels. For lower-level L2 learners, the strongest predictor of L2 Learning Motivation is Second Language Learning Experience （hereafter abbreviated as SLLE）, while for higher-level L2 learners, the strongest predictor is their Ideal L2 Self. Furthermore, the overall picture of the parameters of the three internal components of L2MSS across various groups of L2 proficiency levels shows a regular pattern. That is, with the increase of L2 proficiency, the self dimension （Ideal 1.2 Self and Ought-to L2 Self, especially the former） plays an increasingly important role in its contribution to L2 Learning Motivation while the SLLE plays a decreasingly important role in the contribution to L2 Learning Motivation.展开更多
文摘The normal hypervelocity impact of an Al-thin plate by an Al-sphere was numerically simulated by using the adaptive smoothed particle hydrodynamics (ASPH) method. In this method, the isotropic smoothing algorithm of standard SPH is replaced with anisotropic smoothing involving ellipsoidal kernels whose axes evolve automatically to follow the mean particle spacing as it varies in time, space, and direction around each particle. Using the ASPH, the anisotropic volume changes under strong shock condition are captured more accurately and clearly. The sophisticated features of meshless and Lagrangian nature inherent in the SPH method are kept for treating large deformations, large inhomogeneities and tracing free surfaces in the extremely transient impact process. A two-dimensional ASPH program is coded with C++. The developed hydrocode is examined for example problems of hypervelocity impacts of solid materials. The results obtained from the numerical simulation are compared with available experimental ones. Good agreement is observed.
基金supported by the Humanity and Social Sciences Planning Fund Sponsored by Chinese Ministry of Education(Grant No.10YJAZH048)
文摘In the framework of D6rnyei＇s L2 Motivational Self System （hereafter abbreviated as L2MSS）, this paper makes an empirical survey among learners of English in China, investigating the parameters of the three internal components of L2MSS among learners of various L2 proficiency levels. It is found that the strongest predictor among the three internal components of L2MSS contributing to the L2 Learning Motivation is closely related to learners＇ L2 proficiency levels. For lower-level L2 learners, the strongest predictor of L2 Learning Motivation is Second Language Learning Experience （hereafter abbreviated as SLLE）, while for higher-level L2 learners, the strongest predictor is their Ideal L2 Self. Furthermore, the overall picture of the parameters of the three internal components of L2MSS across various groups of L2 proficiency levels shows a regular pattern. That is, with the increase of L2 proficiency, the self dimension （Ideal 1.2 Self and Ought-to L2 Self, especially the former） plays an increasingly important role in its contribution to L2 Learning Motivation while the SLLE plays a decreasingly important role in the contribution to L2 Learning Motivation.
