Changes in surface air temperature can directly affect hydrology, agriculture, and ecosystems through extreme climate events such as heat waves. For this reason, and to improve climate change adaptation strategies, it...Changes in surface air temperature can directly affect hydrology, agriculture, and ecosystems through extreme climate events such as heat waves. For this reason, and to improve climate change adaptation strategies, it is important to investigate the ranking of hottest years. In this study, the Wilcoxon signed-ranktest and Monte Carlo simulation are used to estimate the ranking of the hottest years for theTibetan Plateau （TP） in recent decades, and the uncertainty in the ranking.The Wilcoxon signed-rank test shows that the top 10 hottest years on record over the TP mainly occur after 1998. The top three hottest years are ranked as 2006, 2009, and 2010, but there is almost no significant difference between them. When both sampling and observational errors are considered, only five years have a non-zero probability of being the hottest year, with the three highest probabilities being for the years 2006 （-47.231%）, 2009 （-40.390%）, and 2010 （-12.376%）. Similarly, with respect to a given year that is among the 10 hottest years, our results show that all the years among the ranks of 1-10 resulting from the Wilcoxon signed-rank test have probabilities above 10%, while the years 2001 and 2012 have probabilities of 3% and 4%.展开更多
The optimal rendezvous trajectory designs in many current research efforts do not incorporate the practical uncertainties into the closed loop of the design.A robust optimization design method for a nonlinear rendezvo...The optimal rendezvous trajectory designs in many current research efforts do not incorporate the practical uncertainties into the closed loop of the design.A robust optimization design method for a nonlinear rendezvous trajectory with uncertainty is proposed in this paper.One performance index related to the variances of the terminal state error is termed the robustness performance index,and a two-objective optimization model(including the minimum characteristic velocity and the minimum robustness performance index)is formulated on the basis of the Lambert algorithm.A multi-objective,non-dominated sorting genetic algorithm is employed to obtain the Pareto optimal solution set.It is shown that the proposed approach can be used to quickly obtain several inherent principles of the rendezvous trajectory by taking practical errors into account.Furthermore,this approach can identify the most preferable design space in which a specific solution for the actual application of the rendezvous control should be chosen.展开更多
基金supported by the National Natural Science Foundation of China[grant number 41405069],[grant number91537214],[grant number 41605063]the Key Foundation of the Education Department of Sichuan Province[grant number16ZA0203]the Scientific Research Foundation of Chengdu University of Information Technology[grant number KYTZ201517],[grant number J201516],[grant number J201518]
文摘Changes in surface air temperature can directly affect hydrology, agriculture, and ecosystems through extreme climate events such as heat waves. For this reason, and to improve climate change adaptation strategies, it is important to investigate the ranking of hottest years. In this study, the Wilcoxon signed-ranktest and Monte Carlo simulation are used to estimate the ranking of the hottest years for theTibetan Plateau （TP） in recent decades, and the uncertainty in the ranking.The Wilcoxon signed-rank test shows that the top 10 hottest years on record over the TP mainly occur after 1998. The top three hottest years are ranked as 2006, 2009, and 2010, but there is almost no significant difference between them. When both sampling and observational errors are considered, only five years have a non-zero probability of being the hottest year, with the three highest probabilities being for the years 2006 （-47.231%）, 2009 （-40.390%）, and 2010 （-12.376%）. Similarly, with respect to a given year that is among the 10 hottest years, our results show that all the years among the ranks of 1-10 resulting from the Wilcoxon signed-rank test have probabilities above 10%, while the years 2001 and 2012 have probabilities of 3% and 4%.
基金supported by the National Natural Science Foundation of China(Grant No.11222215)the National Basic Research Program of China(Grant No.2013CB733100)the Science Project of the National University of Defense Technology(Grant No.CJ12-01-02)
文摘The optimal rendezvous trajectory designs in many current research efforts do not incorporate the practical uncertainties into the closed loop of the design.A robust optimization design method for a nonlinear rendezvous trajectory with uncertainty is proposed in this paper.One performance index related to the variances of the terminal state error is termed the robustness performance index,and a two-objective optimization model(including the minimum characteristic velocity and the minimum robustness performance index)is formulated on the basis of the Lambert algorithm.A multi-objective,non-dominated sorting genetic algorithm is employed to obtain the Pareto optimal solution set.It is shown that the proposed approach can be used to quickly obtain several inherent principles of the rendezvous trajectory by taking practical errors into account.Furthermore,this approach can identify the most preferable design space in which a specific solution for the actual application of the rendezvous control should be chosen.
