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Multi-turn Event Argument Extraction Based on Role Information Guidance
YU Yuanfang, ZHANG Yong, ZUO Haoyang, ZHANG Lianfa, WANG Tingting
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (1): 83-91.   DOI: 10.13209/j.0479-8023.2022.064
Abstract237)   HTML    PDF(pc) (685KB)(122)       Save
Aiming at the two problems of insufficient utilization of role information and lack of interaction between arguments in general domain event argument extraction research, a role information-oriented multi-turn event argument extraction model is proposed to enhance the semantic information of texts and interactions between arguments. The interactive capability can improve the performance of event argument extraction. First, to better utilize role knowledge to guide argument extraction, the model builds role knowledge based on role definitions, independently encodes role information and text, and uses a method based on attention mechanism to obtain label-knowledge-enhanced representations. Then the augmented embeddings are used to predict whether or not each token is a start or end position for some category. At the same time, in order to make full use of the interaction between event arguments in the extraction process, inspired by the multi-turn dialogue model, this paper designs a multi-turn event argument extraction algorithm. The algorithm refers to the natural logic of “easiness to hardness”, and selects the character with the highest prediction probability, that is, the most predictable character, for extraction each time. In the process of argument extraction, in order to model the interaction between arguments, the model introduces historical embedding, and updates the historical embedding after each prediction to help the extraction of the next round of event arguments. The experimental results show that the guidance of role information and multi round extraction algorithm effectively improve the performance of argument extraction, and the method achieves state-of-the-art performance.
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Similarities Analysis on Center of Pressure Trajectories for Healthy Volunteers during Walking and Jogging
HUANG Hongshi, QIU Jianwei, YU Yuanyuan, YANG Jie, AO Yingfang, LUO Dingsheng
Acta Scientiarum Naturalium Universitatis Pekinensis    2015, 51 (6): 1035-1039.   DOI: 10.13209/j.0479-8023.2015.128
Abstract1171)      PDF(pc) (459KB)(858)       Save

The aim of this study was to investigate the similarities of Center of Pressure (COP) trajectories during barefoot walking and jogging, based on plantar pressure data collected from 32 healthy volunteers. 32 subjects walk or run on a two-meter footscan® system at a self-selected speed for 5 valid trials respectively. For each trial, a sequence of frames is generated which records the instantaneous pressure value of the reaction between body and the supporting surface. Similarities between COP trajectories are calculated. Results show that similarities between walking and jogging COP trajectories are lower than 0.25, while similarities between left and right COP trajectories during the same motion status (walking or jogging) is higher than 0.91. In addition, intrasubject similarities are significantly higher than those of intersubject. Moreover, similarities between the same sides are significantly higher than those of different sides. COP trajectories similarities between walking and jogging are very low which indicates COP trajectories can distinguish walking from jogging. During the same motion, intersubject similarities are high. In addition, intrasubject similarities are even higher. This study provides a reliable dataset for clinical diagnosis, rehabilitation evaluation, orthosis prescription and sports exercises.

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Oscillation of Second Order Delay Difference Equations
YU Wensheng,LIN Shizhong,YU Yuanhong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract653)            Save
Some new oscillation criteria for the second order nonlinear delaydifference equations Delta2yn+Pnf(yn-k)=0 are established. Here Deltayn=yn+1-yn is difference operator, k is nonnegative integers, {Pn} is a sequence of nonnegative real numbers and f is continuous on R=(-infinity,infinity).
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On the Oscillation and Nonoscillation for a Class of Nonlinear Differential Equations
LIU Zhengrong,YU Yuanhong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1001)            Save
Sufficient conditions have been obtained for oscillation and nonoscil-lation of solutions of a class of nonlihear differential equations with piecewise constant arguments, which generalize some results of the literature.
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