To quantify unmanned aerial vehicle(UAV)flight risks in low-altitude airspace,we analyze the factors of UAV flight risks from three aspects:flight conflict,flight environment,and traffic characteristics.The aerial ris...To quantify unmanned aerial vehicle(UAV)flight risks in low-altitude airspace,we analyze the factors of UAV flight risks from three aspects:flight conflict,flight environment,and traffic characteristics.The aerial risk index and ground risk index of the UAV are constructed,the index screening model and the UAV flight risk assessment model are established,and a UAV flight risk assessment model based on K-means clustering has been proposed.Meanwhile,numerical simulations show the proposed method can not only evaluate the UAV flight risks effectively,but also provide technical support for UAV risk management and control.展开更多
Purpose： This study aimed to examine the extent to which the quality physical education teaching （QPET） practices contributed to improving 4th- and 5th-grade students＇ manipulative skill competency. Methods： Part...Purpose： This study aimed to examine the extent to which the quality physical education teaching （QPET） practices contributed to improving 4th- and 5th-grade students＇ manipulative skill competency. Methods： Participants were 9 elementary physical education （PE） teachers and their 4th- and 5th-grade students （n = 2709 3420）. The students＇ skill competency was assessed with 3 manipulative skills using PE metrics assessment rubrics. The PE teachers＇ levels of QPET were assessed by coding 63 videotaped lessons using the assessing quality teaching rubrics （AQTR）, which consisted of 4 essential dimensions including task design, task presentation, class management, and instructional guidance. Codes were confirmed through inter-rater reliability （82.4%, 84.5%, and 94%）. Data were analyzed through descriptive statistics, multiple R2 regression models, and independent sample t tests. Results： This study indicated that the 4 essential dimensions of QPET were all significant contributors to students＇ manipulative skill competency. These predictors were significantly higher for boys than for girls in soccer and striking skills, while they were significantly higher for girls than for boys in throwing skill competency. Of the 4 essential dimensions of QPET, task presentation played the most significant role in contributing to all 3 skill competencies for both boys and girls. Further, students who experienced high QPET were significantly more skillfully competent than those students who did not have this experience. Conclusion： It was concluded that the QPET practices played a significantly critical role in contributing to students＇ manipulative skill competency.展开更多
To the potential oil-spill risk caused by offshore pipeline more attention has been paid after the Dalian oil spill incident from oil-pipeline explosion. Since then an issue about how to prevent and control the sudden...To the potential oil-spill risk caused by offshore pipeline more attention has been paid after the Dalian oil spill incident from oil-pipeline explosion. Since then an issue about how to prevent and control the sudden oil-spill from the offshore pipeline has been raised. In this paper, we proposed an optimized model to analyze the main causes(probability) of spill and the consequence with the fuzzy comprehensive assessment model. Considering the complicated assessment process for oil-spill, the assessment factor system involving the spill probability and consequence was established based on the operative manual and statistic leakage/damage data of offshore pipeline in order to estimate the integrated spill risk score automatically. The evaluated factors of spill probability could be grouped into five aspects: corrosion, fatigue, national damage, third party, and operational fault; the consequence evaluated factors of spill included hazard of oil and impact-controlling capability. With some modifications based on experts' opinions, each of the evaluated factors in our work was developed with a relative weight and evaluation criterion. A test example for an offshore pipeline in the Bohai waters was described to show how the model can be used for an actual case in more detail. By using the oil-spill risk assessment model, it is easy to determine the risk level associated with the ongoing activity and management level and hence to take the risk mitigation action immediately.展开更多
This paper mainly makes a performance evaluation for the industrial structure adjustment of the industrial enterprises, establishing a set of evaluation index system. It uses the mathematics statistics knowledge and m...This paper mainly makes a performance evaluation for the industrial structure adjustment of the industrial enterprises, establishing a set of evaluation index system. It uses the mathematics statistics knowledge and management knowledge to establish a scientific and operable performance evaluation model for the industrial structure adjustment of the industrial enterprises. Based on the model, it can make a performance evaluation for the internal industrial structure adjustment of the industrial enterprises and also it can evaluate the performance of the industrial structure adjustu^ent of different industries.展开更多
基金supported in part by the National Natural Science Foundation of China (Nos. 71971114,61573181)Open Grant of State Key Laboratory of Air Traffic Management System and Technique(No. SKLATM201801).
文摘To quantify unmanned aerial vehicle(UAV)flight risks in low-altitude airspace,we analyze the factors of UAV flight risks from three aspects:flight conflict,flight environment,and traffic characteristics.The aerial risk index and ground risk index of the UAV are constructed,the index screening model and the UAV flight risk assessment model are established,and a UAV flight risk assessment model based on K-means clustering has been proposed.Meanwhile,numerical simulations show the proposed method can not only evaluate the UAV flight risks effectively,but also provide technical support for UAV risk management and control.
文摘Purpose： This study aimed to examine the extent to which the quality physical education teaching （QPET） practices contributed to improving 4th- and 5th-grade students＇ manipulative skill competency. Methods： Participants were 9 elementary physical education （PE） teachers and their 4th- and 5th-grade students （n = 2709 3420）. The students＇ skill competency was assessed with 3 manipulative skills using PE metrics assessment rubrics. The PE teachers＇ levels of QPET were assessed by coding 63 videotaped lessons using the assessing quality teaching rubrics （AQTR）, which consisted of 4 essential dimensions including task design, task presentation, class management, and instructional guidance. Codes were confirmed through inter-rater reliability （82.4%, 84.5%, and 94%）. Data were analyzed through descriptive statistics, multiple R2 regression models, and independent sample t tests. Results： This study indicated that the 4 essential dimensions of QPET were all significant contributors to students＇ manipulative skill competency. These predictors were significantly higher for boys than for girls in soccer and striking skills, while they were significantly higher for girls than for boys in throwing skill competency. Of the 4 essential dimensions of QPET, task presentation played the most significant role in contributing to all 3 skill competencies for both boys and girls. Further, students who experienced high QPET were significantly more skillfully competent than those students who did not have this experience. Conclusion： It was concluded that the QPET practices played a significantly critical role in contributing to students＇ manipulative skill competency.
基金the Marine Public Welfare Research Project of China (No. 201205012)Preferential Funding of Tianjin
文摘To the potential oil-spill risk caused by offshore pipeline more attention has been paid after the Dalian oil spill incident from oil-pipeline explosion. Since then an issue about how to prevent and control the sudden oil-spill from the offshore pipeline has been raised. In this paper, we proposed an optimized model to analyze the main causes(probability) of spill and the consequence with the fuzzy comprehensive assessment model. Considering the complicated assessment process for oil-spill, the assessment factor system involving the spill probability and consequence was established based on the operative manual and statistic leakage/damage data of offshore pipeline in order to estimate the integrated spill risk score automatically. The evaluated factors of spill probability could be grouped into five aspects: corrosion, fatigue, national damage, third party, and operational fault; the consequence evaluated factors of spill included hazard of oil and impact-controlling capability. With some modifications based on experts' opinions, each of the evaluated factors in our work was developed with a relative weight and evaluation criterion. A test example for an offshore pipeline in the Bohai waters was described to show how the model can be used for an actual case in more detail. By using the oil-spill risk assessment model, it is easy to determine the risk level associated with the ongoing activity and management level and hence to take the risk mitigation action immediately.
文摘This paper mainly makes a performance evaluation for the industrial structure adjustment of the industrial enterprises, establishing a set of evaluation index system. It uses the mathematics statistics knowledge and management knowledge to establish a scientific and operable performance evaluation model for the industrial structure adjustment of the industrial enterprises. Based on the model, it can make a performance evaluation for the internal industrial structure adjustment of the industrial enterprises and also it can evaluate the performance of the industrial structure adjustu^ent of different industries.
