The fall armyworm(FAW),Spodoptera frugiperda is one of the most damaging crop pests,and it has become major threat to the food security of many countries.In order to monitor possible invasion of this pest into China,a...The fall armyworm(FAW),Spodoptera frugiperda is one of the most damaging crop pests,and it has become major threat to the food security of many countries.In order to monitor possible invasion of this pest into China,a searchlight trap was established in March 2018 in western Yunnan Province,China,where it has served as the"first station"for many pests that have migrated from Myanmar to China.A number of suspected FAW moths were captured and identified by DNA sequencing.The results showed that the FAW moth was first captured on December 11 and formed its first immigration peak in mid-December 2018.DNA detection revealed that the early invading FAW population was the"corn-strain".The field survey indicated that the pest mainly colonized corn in Pu’er,Dehong and Baoshan areas.Migration trajectory simulation implied that the moths might have mainly come from the eastern area in the mid-latitude region of Myanmar(20-25°N,94-100°E).This case study confirmed the first immigration of FAW into China,and will be helpful for guiding monitoring and management work to control this pest.展开更多
The reentry trajectory optimization for hypersonic vehicle（HV）is a current problem of great interest.Some complex constraints,such as waypoints for reconnaissance and no-fly zones for threat avoidance,are inevitably...The reentry trajectory optimization for hypersonic vehicle（HV）is a current problem of great interest.Some complex constraints,such as waypoints for reconnaissance and no-fly zones for threat avoidance,are inevitably involved in a global strike mission.Of the many direct methods,Gauss pseudospectral method（GPM）has been demonstrated as an effective tool to solve the trajectory optimization problem with typical constraints.However,a series of diffculties arises for complex constraints,such as the uncertainty of passage time for waypoints and the inaccuracy of approximate trajectory near no-fly zones.The research herein proposes a multi-phase technique based on the GPM to generate an optimal reentry trajectory for HV satisfying waypoint and nofly zone constraints.Three kinds of specifc breaks are introduced to divide the full trajectory into multiple phases.The continuity conditions are presented to ensure a smooth connection between each pair of phases.Numerical examples for reentry trajectory optimization in free-space flight and with complex constraints are used to demonstrate the proposed technique.Simulation results show the feasible application of multi-phase technique in reentry trajectory optimization with waypoint and no-fly zone constraints.展开更多
经验取样法是一种有效的密集纵向研究数据收集方法。该方法的优点正逐渐被广大研究者所认同,国外运用经验取样法取得的研究成果越来越多,而国内学者对经验取样法的研究尚处于探索阶段,运用此方法的实证研究更是凤毛麟角。通过对《应用...经验取样法是一种有效的密集纵向研究数据收集方法。该方法的优点正逐渐被广大研究者所认同,国外运用经验取样法取得的研究成果越来越多,而国内学者对经验取样法的研究尚处于探索阶段,运用此方法的实证研究更是凤毛麟角。通过对《应用心理学期刊》（Journal of Applied Psychology）最近5年（2010-2014年）发表的26篇采用经验取样法的实证研究论文的内容分析,发现这些文章全面体现了经验取样法的特点、研究内容、样本量、激励方式、数据收集和操作过程等该方法的操作要素。对其进行总结不仅有利于对经验取样法在组织行为学中的应用状况进行总结,而且也能促进这一方法在未来的组织行为学和人力资源管理中的发展和应用。展开更多
Cells of eukaryotic multicellular organisms have inherent heterogeneity.Recent advances in single-cell gene expression studies enable us to explore transcriptional regulation in dynamic development processes and highl...Cells of eukaryotic multicellular organisms have inherent heterogeneity.Recent advances in single-cell gene expression studies enable us to explore transcriptional regulation in dynamic development processes and highly heterogeneous cell populations.In this study,using a high-throughput single-cell RNA-sequencing assay,we found that the cells in Arabidopsis root are highly heterogeneous in their transcriptomes.A total of 24 putative cell clusters and the cluster-specific marker genes were identified.The spatial distribution and temporal ordering of the individual cells at different developmental stages illustrate their hierarchical structures and enable the reconstruction of continuous differentiation trajectory of root development.Moreover,we found that each root cell cluster exhibits distinct patterns of ion assimilation and hormonal responses.Collectively,our study reveals a high degree of heterogeneity of root cells and identifies the expression signatures of intermediate states during root cell differentiation at single-cell resolution.We also established a web server(http://wanglab.sippe.ac.cn/rootatlas/)to facilitate the use of the datasets generated in this study.展开更多
Multiple Uninhabited Aerial Vehicles (multi-UAVs) coordinated trajectory replanning is one of the most complicated global optimum problems in multi-UAVs coordinated control. Based on the construction of the basic mode...Multiple Uninhabited Aerial Vehicles (multi-UAVs) coordinated trajectory replanning is one of the most complicated global optimum problems in multi-UAVs coordinated control. Based on the construction of the basic model of multi-UAVs coordinated trajectory replanning, which includes problem description, threat modeling, constraint conditions, coordinated function and coordination mechanism, a novel Max-Min adaptive Ant Colony Optimization (ACO) approach is presented in detail. In view of the characteristics of multi-UAVs coordinated trajectory replanning in dynamic and uncertain environments, the minimum and maximum pheromone trails in ACO are set to enhance the searching capability, and the point pheromone is adopted to achieve the collision avoidance between UAVs at the trajectory planner layer. Considering the simultaneous arrival and the air-space collision avoidance, an Estimated Time of Arrival (ETA) is decided first. Then the trajectory and flight velocity of each UAV are determined. Simulation experiments are performed under the complicated combating environment containing some static threats and popup threats. The results demonstrate the feasibility and the effectiveness of the proposed approach.展开更多
基金supported by the National Natural Science Foundation of China(31727901)。
文摘The fall armyworm(FAW),Spodoptera frugiperda is one of the most damaging crop pests,and it has become major threat to the food security of many countries.In order to monitor possible invasion of this pest into China,a searchlight trap was established in March 2018 in western Yunnan Province,China,where it has served as the"first station"for many pests that have migrated from Myanmar to China.A number of suspected FAW moths were captured and identified by DNA sequencing.The results showed that the FAW moth was first captured on December 11 and formed its first immigration peak in mid-December 2018.DNA detection revealed that the early invading FAW population was the"corn-strain".The field survey indicated that the pest mainly colonized corn in Pu’er,Dehong and Baoshan areas.Migration trajectory simulation implied that the moths might have mainly come from the eastern area in the mid-latitude region of Myanmar(20-25°N,94-100°E).This case study confirmed the first immigration of FAW into China,and will be helpful for guiding monitoring and management work to control this pest.
基金supported by Aviation Science Foundation of China(No.2011ZC13001 and 2013ZA18001)National Natural Science Foundation of China(Nos:60975073,61273349,61175109 and 61203223)Innovation Foundation of BUAA for PhD Graduates
文摘The reentry trajectory optimization for hypersonic vehicle（HV）is a current problem of great interest.Some complex constraints,such as waypoints for reconnaissance and no-fly zones for threat avoidance,are inevitably involved in a global strike mission.Of the many direct methods,Gauss pseudospectral method（GPM）has been demonstrated as an effective tool to solve the trajectory optimization problem with typical constraints.However,a series of diffculties arises for complex constraints,such as the uncertainty of passage time for waypoints and the inaccuracy of approximate trajectory near no-fly zones.The research herein proposes a multi-phase technique based on the GPM to generate an optimal reentry trajectory for HV satisfying waypoint and nofly zone constraints.Three kinds of specifc breaks are introduced to divide the full trajectory into multiple phases.The continuity conditions are presented to ensure a smooth connection between each pair of phases.Numerical examples for reentry trajectory optimization in free-space flight and with complex constraints are used to demonstrate the proposed technique.Simulation results show the feasible application of multi-phase technique in reentry trajectory optimization with waypoint and no-fly zone constraints.
文摘经验取样法是一种有效的密集纵向研究数据收集方法。该方法的优点正逐渐被广大研究者所认同,国外运用经验取样法取得的研究成果越来越多,而国内学者对经验取样法的研究尚处于探索阶段,运用此方法的实证研究更是凤毛麟角。通过对《应用心理学期刊》（Journal of Applied Psychology）最近5年（2010-2014年）发表的26篇采用经验取样法的实证研究论文的内容分析,发现这些文章全面体现了经验取样法的特点、研究内容、样本量、激励方式、数据收集和操作过程等该方法的操作要素。对其进行总结不仅有利于对经验取样法在组织行为学中的应用状况进行总结,而且也能促进这一方法在未来的组织行为学和人力资源管理中的发展和应用。
基金the State Key Basic Research Program of China(2013CB127000)National Natural Science Foundation of China(31430013+5 种基金31222029912173023,31525004)Strategic Priority Research Program of the Chinese Academy of Sciences(XDB27030101)Young Elite Scientists Sponsorship Program by CAST(2016QNRC001)National Postdoctoral Program for Innovative Talents(BX201600178)the Sanofi-SI BS 2017 Post-doctoral Fellowship.
文摘Cells of eukaryotic multicellular organisms have inherent heterogeneity.Recent advances in single-cell gene expression studies enable us to explore transcriptional regulation in dynamic development processes and highly heterogeneous cell populations.In this study,using a high-throughput single-cell RNA-sequencing assay,we found that the cells in Arabidopsis root are highly heterogeneous in their transcriptomes.A total of 24 putative cell clusters and the cluster-specific marker genes were identified.The spatial distribution and temporal ordering of the individual cells at different developmental stages illustrate their hierarchical structures and enable the reconstruction of continuous differentiation trajectory of root development.Moreover,we found that each root cell cluster exhibits distinct patterns of ion assimilation and hormonal responses.Collectively,our study reveals a high degree of heterogeneity of root cells and identifies the expression signatures of intermediate states during root cell differentiation at single-cell resolution.We also established a web server(http://wanglab.sippe.ac.cn/rootatlas/)to facilitate the use of the datasets generated in this study.
基金supported by the Natural Science Foundation of China (Grant no.60604009)Aeronautical Science Foundation of China (Grant no.2006ZC51039,Beijing NOVA Program Foundation of China (Grant no.2007A017)+1 种基金Open Fund of the Provincial Key Laboratory for Information Processing Technology,Suzhou University (Grant no KJS0821)"New Scientific Star in Blue Sky"Talent Program of Beihang University of China
文摘Multiple Uninhabited Aerial Vehicles (multi-UAVs) coordinated trajectory replanning is one of the most complicated global optimum problems in multi-UAVs coordinated control. Based on the construction of the basic model of multi-UAVs coordinated trajectory replanning, which includes problem description, threat modeling, constraint conditions, coordinated function and coordination mechanism, a novel Max-Min adaptive Ant Colony Optimization (ACO) approach is presented in detail. In view of the characteristics of multi-UAVs coordinated trajectory replanning in dynamic and uncertain environments, the minimum and maximum pheromone trails in ACO are set to enhance the searching capability, and the point pheromone is adopted to achieve the collision avoidance between UAVs at the trajectory planner layer. Considering the simultaneous arrival and the air-space collision avoidance, an Estimated Time of Arrival (ETA) is decided first. Then the trajectory and flight velocity of each UAV are determined. Simulation experiments are performed under the complicated combating environment containing some static threats and popup threats. The results demonstrate the feasibility and the effectiveness of the proposed approach.
