The thermodynamic charge performance of a variable-mass thermodynamic system was investigated by the simulation modeling and experimental analysis. Three sets of experiments were conducted for various charge time and ...The thermodynamic charge performance of a variable-mass thermodynamic system was investigated by the simulation modeling and experimental analysis. Three sets of experiments were conducted for various charge time and charge steam flow under three different control strategies of charge valve. Characteristic performance parameters from the average sub-cooled degree and the charging energy coefficient point of views were also defined to evaluate and predict the charge performance of system combined with the simulation model and experimental data. The results show that the average steam flow reflects the average sub-cooled degree qualitatively, while the charging energy coefficients of 74.6%, 69.9% and 100% relate to the end value of the average sub-cooled degree at 2.1, 2.9 and 0 respectively for the three sets of experiments. The mean and maximum deviations of the results predicted from those by experimental data are smaller than 6.8% and 10.8%, respectively. In conclusion, the decrease of average steam flow can effectively increase the charging energy coefficient in the same charge time condition and therefore improve the thermodynamic charge performance of system. While the increase of the charging energy coefficient by extending the charge time needs the consideration of the operating frequency for steam users.展开更多
目的:探讨体力疲劳(physical fatigue,PF)、脑力疲劳(mental fatigue,MF)及体脑混合疲劳(physical and mental mixed fatigue,PMF)对橄榄球运动员下肢爆发力和心率变异性(heart rate variability,HRV)的影响。方法:选取15名橄榄球运动...目的:探讨体力疲劳(physical fatigue,PF)、脑力疲劳(mental fatigue,MF)及体脑混合疲劳(physical and mental mixed fatigue,PMF)对橄榄球运动员下肢爆发力和心率变异性(heart rate variability,HRV)的影响。方法:选取15名橄榄球运动员作为研究对象。采用随机交叉对照试验设计,受试者需完成PF、MF、PMF干预任务,并在每次实验后进行下肢爆发力和HRV测试。采用单因素重复测量方差分析进行统计学分析。结果:1)在跳深跳跃腾空高度指标上,PMF相较于MF显示出了更低的腾空高度(P<0.05)。2)在下蹲跳的垂直地面反作用力峰值(peak vertical ground reaction force,vGRFpeak)指标上,PF和PMF相较于基线和MF均显示出了更小的vGRFpeak(P<0.05);在跳深的vGRFpeak指标上,PMF相较于基线和MF显示出了更小的vGRFpeak(P<0.05)。3)不同疲劳方案对下蹲跳的力量发展速率具有显著差异(P<0.05),相较于基线、PF和MF,PMF显示出了更小的力量发展速率(P<0.05)。4)不同疲劳方案对跳深平均功率输出、反应力量指数和反应力量比具有显著影响(P<0.05),在平均功率输出指标上,相较于基线,PF、MF和PMF均显示出了更低的平均功率输出(P<0.05);在反应力量指数指标上,相较于基线,MF和PMF显示出了更低的反应力量指数(P<0.05);在反应力量比指标上,相较于基线,MF和PMF显示出了更低的反应力量比(P<0.05);相较于PF,MF显示出了更低的反应力量比(P<0.05)。5)不同疲劳方案对HRV的正常心跳间期的标准差(standard deviation of the normal to normal intervals,SDNN)、相邻R-R间期差值的均方根(root mean square successive difference,RMSSD)、高频(high frequency,HF)和低频(low frequency,LF)指标均有显著差异(P<0.05),相较于基线和MF,PF和PMF均显示出了更小的SDNN、RMSSD、HF和LF(P<0.05)。结论:PF、MF和PMF均对橄榄球运动员的下肢爆发力产生了显著影响。其中,相较于PF和MF,PMF对vGRFpeak以及反应性力量方面均产生了显著影响,表明PMF可能通过多重机制影响运动员的运动表现,且其影响可能大于单一类型的疲劳。此外,在HRV方面,PF和PMF均能降低HRV相关指标,但PMF与PF之间,以及基线与MF之间并未观察到显著差异。表明PMF对心脏应激反应和自主神经系统调节能力的即时影响与PF相似,而MF未表现出显著影响。展开更多
International freedom of the air(traffic rights)is a key resource for airlines to carry out international air transport business.An efficient and reasonable traffic right resource allocation within a country between a...International freedom of the air(traffic rights)is a key resource for airlines to carry out international air transport business.An efficient and reasonable traffic right resource allocation within a country between airlines can affect the quality of a country’s participation in international air transport.In this paper,a multi-objective mixed-integer programming model for traffic rights resource allocation is developed to minimize passenger travel mileages and maximize the number of traffic rights resources allocated to hub airports and competitive carriers.A hybrid heuristic algorithm combining the genetic algorithm and the variable neighborhood search is devised to solve the model.The results show that the optimal allocation scheme aligns with the principle of fairness,indicating that the proposed model can play a certain guiding role in and provide an innovative perspective on traffic rights resource allocation in various countries.展开更多
基金Project(20080431380) supported by the China Postdoctoral Science Foundation
文摘The thermodynamic charge performance of a variable-mass thermodynamic system was investigated by the simulation modeling and experimental analysis. Three sets of experiments were conducted for various charge time and charge steam flow under three different control strategies of charge valve. Characteristic performance parameters from the average sub-cooled degree and the charging energy coefficient point of views were also defined to evaluate and predict the charge performance of system combined with the simulation model and experimental data. The results show that the average steam flow reflects the average sub-cooled degree qualitatively, while the charging energy coefficients of 74.6%, 69.9% and 100% relate to the end value of the average sub-cooled degree at 2.1, 2.9 and 0 respectively for the three sets of experiments. The mean and maximum deviations of the results predicted from those by experimental data are smaller than 6.8% and 10.8%, respectively. In conclusion, the decrease of average steam flow can effectively increase the charging energy coefficient in the same charge time condition and therefore improve the thermodynamic charge performance of system. While the increase of the charging energy coefficient by extending the charge time needs the consideration of the operating frequency for steam users.
文摘目的:探讨体力疲劳(physical fatigue,PF)、脑力疲劳(mental fatigue,MF)及体脑混合疲劳(physical and mental mixed fatigue,PMF)对橄榄球运动员下肢爆发力和心率变异性(heart rate variability,HRV)的影响。方法:选取15名橄榄球运动员作为研究对象。采用随机交叉对照试验设计,受试者需完成PF、MF、PMF干预任务,并在每次实验后进行下肢爆发力和HRV测试。采用单因素重复测量方差分析进行统计学分析。结果:1)在跳深跳跃腾空高度指标上,PMF相较于MF显示出了更低的腾空高度(P<0.05)。2)在下蹲跳的垂直地面反作用力峰值(peak vertical ground reaction force,vGRFpeak)指标上,PF和PMF相较于基线和MF均显示出了更小的vGRFpeak(P<0.05);在跳深的vGRFpeak指标上,PMF相较于基线和MF显示出了更小的vGRFpeak(P<0.05)。3)不同疲劳方案对下蹲跳的力量发展速率具有显著差异(P<0.05),相较于基线、PF和MF,PMF显示出了更小的力量发展速率(P<0.05)。4)不同疲劳方案对跳深平均功率输出、反应力量指数和反应力量比具有显著影响(P<0.05),在平均功率输出指标上,相较于基线,PF、MF和PMF均显示出了更低的平均功率输出(P<0.05);在反应力量指数指标上,相较于基线,MF和PMF显示出了更低的反应力量指数(P<0.05);在反应力量比指标上,相较于基线,MF和PMF显示出了更低的反应力量比(P<0.05);相较于PF,MF显示出了更低的反应力量比(P<0.05)。5)不同疲劳方案对HRV的正常心跳间期的标准差(standard deviation of the normal to normal intervals,SDNN)、相邻R-R间期差值的均方根(root mean square successive difference,RMSSD)、高频(high frequency,HF)和低频(low frequency,LF)指标均有显著差异(P<0.05),相较于基线和MF,PF和PMF均显示出了更小的SDNN、RMSSD、HF和LF(P<0.05)。结论:PF、MF和PMF均对橄榄球运动员的下肢爆发力产生了显著影响。其中,相较于PF和MF,PMF对vGRFpeak以及反应性力量方面均产生了显著影响,表明PMF可能通过多重机制影响运动员的运动表现,且其影响可能大于单一类型的疲劳。此外,在HRV方面,PF和PMF均能降低HRV相关指标,但PMF与PF之间,以及基线与MF之间并未观察到显著差异。表明PMF对心脏应激反应和自主神经系统调节能力的即时影响与PF相似,而MF未表现出显著影响。
基金supported by the National Natural Science Foundation of Chinathe Civil Aviation Administration of China (U2333206).
文摘International freedom of the air(traffic rights)is a key resource for airlines to carry out international air transport business.An efficient and reasonable traffic right resource allocation within a country between airlines can affect the quality of a country’s participation in international air transport.In this paper,a multi-objective mixed-integer programming model for traffic rights resource allocation is developed to minimize passenger travel mileages and maximize the number of traffic rights resources allocated to hub airports and competitive carriers.A hybrid heuristic algorithm combining the genetic algorithm and the variable neighborhood search is devised to solve the model.The results show that the optimal allocation scheme aligns with the principle of fairness,indicating that the proposed model can play a certain guiding role in and provide an innovative perspective on traffic rights resource allocation in various countries.
