There are both pedagogical and theoretical grounds for asking second language writers to plan before they start writing.The question then arises whether pre-task planning(PTP)improves written output.To address this qu...There are both pedagogical and theoretical grounds for asking second language writers to plan before they start writing.The question then arises whether pre-task planning(PTP)improves written output.To address this question,this article reviewed 32 studies by comparing the effect of PTP either with no planning or with unpressured online planning(OLP).These studies also investigated the moderating effect of variables relating to the writer participants,the nature of the planning,and the writing tasks.The main findings are:(1)There is no clear evidence that PTP leads to better overall writing quality when this is measured using rating rubrics,(2)PTP generally results in more fluent writing,(3)its impact on syntactical and lexical complexity is inconsistent and negligible,(4)OLP does sometimes result in increased linguistic accuracy,and(5)there is insufficient evidence to reach clear conclusions about the role that moderating variables have on the impact of PTP,but the results suggest that collaborative(as opposed to individual planning)can lead to increased accuracy and that PTP tends to lead to more complex language when the writing task is a complex one.The article concludes with a set of principles to ensure better quality research and three general proposals for the kind of future research needed.展开更多
In this paper, robot path planning in globally unknown environments is studied. Using the rolling optimization concept in predictive control for reference, a new strategy of path planning for a mobile robot, based on ...In this paper, robot path planning in globally unknown environments is studied. Using the rolling optimization concept in predictive control for reference, a new strategy of path planning for a mobile robot, based on rolling windows, is proposed. The method makes full use of the real-time local environmental information detected by the robot and the on-line path planning is carried on in a rolling style. Optimization and feedback are combined in a reasonable way. The convergence of the planning algorithm is also discussed.展开更多
文摘There are both pedagogical and theoretical grounds for asking second language writers to plan before they start writing.The question then arises whether pre-task planning(PTP)improves written output.To address this question,this article reviewed 32 studies by comparing the effect of PTP either with no planning or with unpressured online planning(OLP).These studies also investigated the moderating effect of variables relating to the writer participants,the nature of the planning,and the writing tasks.The main findings are:(1)There is no clear evidence that PTP leads to better overall writing quality when this is measured using rating rubrics,(2)PTP generally results in more fluent writing,(3)its impact on syntactical and lexical complexity is inconsistent and negligible,(4)OLP does sometimes result in increased linguistic accuracy,and(5)there is insufficient evidence to reach clear conclusions about the role that moderating variables have on the impact of PTP,but the results suggest that collaborative(as opposed to individual planning)can lead to increased accuracy and that PTP tends to lead to more complex language when the writing task is a complex one.The article concludes with a set of principles to ensure better quality research and three general proposals for the kind of future research needed.
基金the National 973 Plan (Grant No. G1998030415) and the National Natural Science Foundation of China (Grant No. 69774004) and the National 863 Program (Grant No. 9805-18).
文摘In this paper, robot path planning in globally unknown environments is studied. Using the rolling optimization concept in predictive control for reference, a new strategy of path planning for a mobile robot, based on rolling windows, is proposed. The method makes full use of the real-time local environmental information detected by the robot and the on-line path planning is carried on in a rolling style. Optimization and feedback are combined in a reasonable way. The convergence of the planning algorithm is also discussed.
