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Moslem Bahmani Abbas Bahram Jed A Diekfuss Saeed Arsham 《Journal of sports sciences》2013,31(20):2318-2330
ABSTRACTThe aims of this study were to (1) to explore attentional strategies in expert judo players and (2) investigate how attentional focus affects performance effectiveness and perceptions of workload in expert judo players during real competitions. Fourteen expert male judo players participated in the study. A simulated recall method was used following participants’ competition to explore contents of attention qualitatively. The data analysis process for the qualitative portion of the study was an iterative process between inductive and deductive analyses. Quantitative analyses of performance outcomes and workload were then associated with the qualitative findings. Qualitative results revealed that the focus of attention was dynamic and complex, with technical aspects of the movements as the highest identified focus. Quantitative analyses revealed that reporting a lower quantity of attentional cues and higher percentage of focus on opponent resulted in higher performance effectiveness and less perceptions of workload. This study indicates that cognitive control and automaticity may work in a synergistic manner for successful skill execution in expert performance. 相似文献
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YOUSEFI Saleh FATHY Mahmood BENSLIMANE Abderrahim 《浙江大学学报(A卷英文版)》2007,8(12):1990-2004
Currently, there is a growing belief that putting an IEEE 802.11-like radio into road vehicles can help the drivers to travel more safely. Message dissemination protocols are primordial for safety vehicular applications. There are two types of safety messages which may be exchanged between vehicles: alarm and beacon. In this paper we investigate the feasibility of deploying safety applications based on beacon message dissemination through extensive simulation study and pay special attention to the safety requirements. Vehicles are supposed to issue these messages periodically to announce to other vehicles their current situation and use received messages for preventing possible unsafe situations. We evaluate the performance of a single-hop dissemination protocol while taking into account the quality of service (QoS) metrics like delivery rate and delay. We realize that reliability is the main concern in beacon message dissemination. Thus, a new metric named effective range is defined which gives us more accurate facility for evaluating QoS in safety applications specifically. Then, in order to improve the performance, the effects of three parameters including vehicle's transmission range, message transmission's interval time and message payload size are studied. Due to special characteristics of the safety applications, we model the relationship between communication-level QoS and application-level QoS and evaluate them for different classes of safety applications. As a conclusion, the current technology of IEEE 802.11 MAC layer has still some challenges for automatic safety applications but it can provide acceptable QoS to driver assistance safety applications. 相似文献
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