In this paper, an investigation into the propagation of far field explosion waves in water and their effects on nearby structures are carried out. For the far field structure, the motion of the fluid surrounding the s...In this paper, an investigation into the propagation of far field explosion waves in water and their effects on nearby structures are carried out. For the far field structure, the motion of the fluid surrounding the structure may be assumed small, allowing linearization of the governing fluid equations. A complete analysis of the problem must involve simultaneous solution of the dynamic response of the structure and the propagation of explosion wave in the surrounding fluid. In this study, a dynamic adaptive finite element procedure is proposed. Its application to the solution of a 2D fluid-structure interaction is investigated in the time domain. The research includes：a） calculation of the far-field scatter wave due to underwater explosion including solution of the time-depended acoustic wave equation, b） fluid-structure interaction analysis using coupled Euler-Lagrangian approach, and c） adaptive finite element procedures employing error estimates, and re-meshing. The temporal mesh adaptation is achieved by local regeneration of the grid using a time-dependent error indicator based on curvature of pressure function. As a result, the overall response is better predicted by a moving mesh than an equivalent uniform mesh. In addition, the cost of computation for large problems is reduced while the accuracy is improved.展开更多
Temporal adverbial clause is an important language structure and exhibits different features in English and Chinese,which brings about difficulties for Chinese EFL learners.Based on the theory of Dependency Grammar,th...Temporal adverbial clause is an important language structure and exhibits different features in English and Chinese,which brings about difficulties for Chinese EFL learners.Based on the theory of Dependency Grammar,the study attempts to investigate the ordering distribution of temporal adverbial clauses by Chinese EFL learners at the beginning,intermediate and advanced levels.The results show that:1)Chinese EFL learners at different proficiencies tend to precede temporal adverbial clause to main clause.With the increase of proficiency,the postposition of temporal adverbial clauses by learners increases and is approaching to the ordering preference of target language.2)The ordering distribution of subordinators for temporal adverbial clauses by Chinese EFL learners is consistent with native English,showing a tendency of 100%preposition,which ascribes to the high frequency and salience of subordinators in English.3)MDD is one of the significant motivations that cause the preference of prepositional temporal adverbial clauses by Chinese EFL learners.As a kind of natural language,interlanguage has a unique cognitive mechanism which distinguishes from both native and target language.This study provides a more comprehensive theoretical reference for learners at different proficiencies to understand and learn temporal adverbial clauses,as well as data support from empirical research for language teaching.展开更多
文摘In this paper, an investigation into the propagation of far field explosion waves in water and their effects on nearby structures are carried out. For the far field structure, the motion of the fluid surrounding the structure may be assumed small, allowing linearization of the governing fluid equations. A complete analysis of the problem must involve simultaneous solution of the dynamic response of the structure and the propagation of explosion wave in the surrounding fluid. In this study, a dynamic adaptive finite element procedure is proposed. Its application to the solution of a 2D fluid-structure interaction is investigated in the time domain. The research includes：a） calculation of the far-field scatter wave due to underwater explosion including solution of the time-depended acoustic wave equation, b） fluid-structure interaction analysis using coupled Euler-Lagrangian approach, and c） adaptive finite element procedures employing error estimates, and re-meshing. The temporal mesh adaptation is achieved by local regeneration of the grid using a time-dependent error indicator based on curvature of pressure function. As a result, the overall response is better predicted by a moving mesh than an equivalent uniform mesh. In addition, the cost of computation for large problems is reduced while the accuracy is improved.
基金supported by the National Social Science Foundation of China(No.21BYY186)。
文摘Temporal adverbial clause is an important language structure and exhibits different features in English and Chinese,which brings about difficulties for Chinese EFL learners.Based on the theory of Dependency Grammar,the study attempts to investigate the ordering distribution of temporal adverbial clauses by Chinese EFL learners at the beginning,intermediate and advanced levels.The results show that:1)Chinese EFL learners at different proficiencies tend to precede temporal adverbial clause to main clause.With the increase of proficiency,the postposition of temporal adverbial clauses by learners increases and is approaching to the ordering preference of target language.2)The ordering distribution of subordinators for temporal adverbial clauses by Chinese EFL learners is consistent with native English,showing a tendency of 100%preposition,which ascribes to the high frequency and salience of subordinators in English.3)MDD is one of the significant motivations that cause the preference of prepositional temporal adverbial clauses by Chinese EFL learners.As a kind of natural language,interlanguage has a unique cognitive mechanism which distinguishes from both native and target language.This study provides a more comprehensive theoretical reference for learners at different proficiencies to understand and learn temporal adverbial clauses,as well as data support from empirical research for language teaching.
