110m栏攻栏腿最佳下压时机探讨     

付伟平 《湖北体育科技》2009,28(2):191-192

用文献参阅、录象资料观察和理论分析的方法研究了优秀运动员和普通水平运动员110m栏中蹬地腿和攻栏腿下压时机的配合,并将配合分为三种情况：1.蹬地腿离地瞬间攻栏腿继续上摆;2.蹬地腿离地前攻栏腿开始下压;3.蹬地腿离地的瞬间攻栏腿开始下压。结果表明：蹬地腿离地瞬间攻栏腿继续上摆,拉长了过栏时间,造成压栏过晚;蹬地腿离地前攻栏腿开始下压,造成跳栏,影响了水平速度;蹬地腿离地的瞬间攻栏腿开始下压是最佳的下压时机。希望通过该研究能给跨栏训练者提供一些理论参考。  相似文献   

Reducing 0s bias in video moment retrieval with a circular competence-based captioner     

《Information processing & management》2023,60(2):103147

The current study addresses the problem of retrieving a specific moment from an untrimmed video by a sentence query. Existing methods have achieved high performance by designing various structures to match visual-text relations. Yet, these methods tend to return an interval starting from 0s, which we named “0s bias”. In this paper, we propose a Circular Co-Teaching (CCT) mechanism using a captioner to improve an existing retrieval model (localizer) from two aspects: biased annotations and easy samples. Correspondingly, CCT contains two processes: (1) Pseudo Query Generation (captioner to localizer), aiming at transferring the knowledge from generated queries to the localizer to balance annotations; (2) Competence-based Curriculum Learning (localizer to captioner), training the captioner in an easy-to-hard fashion guided by localization results, making pairs of the false-positive moment and pseudo query become easy samples for the localizer. Extensive experiments show that our CCT can alleviate “0s bias” with even 4% improvement for existing approaches on average in two public datasets (ActivityNet-Captions, and Charades-STA), in terms of R@1,IoU=0.7. Notably, our method also outperforms baselines in an out-of-distribution scenario. We also quantitatively validate CCT’s ability to cope with “0s bias” by a proposed metric, DM. Our study not only theoretically contributes to detecting “0s bias”, but also provides a highly effective tool for video moment retrieval by alleviating such bias.  相似文献