为减少三体船结构质量以提高三体船总体性能,同时保证结构质量减少后三体船舱壁结构具有足够的结构强度,本文基于《Rules for The Classification of Trimarans》设计了7个三体船结构强度校核工况。应用变密度拓扑优化方法,计算了优化...为减少三体船结构质量以提高三体船总体性能,同时保证结构质量减少后三体船舱壁结构具有足够的结构强度,本文基于《Rules for The Classification of Trimarans》设计了7个三体船结构强度校核工况。应用变密度拓扑优化方法,计算了优化前、后三体船舱壁结构在不同工况下的应力分布。计算及优化结果表明:特定工况不同体积约束条件下,优化后舱壁结构应力最大值与体积减少比例之间不存在正相关关联;通过优化能在保证结构安全的前提下,减少舱壁优化区域内50%的结构重量,实现非水密舱壁结构的轻量化设计;通过与实船舱壁设计对比,优化后舱壁连接材料的分布与实船舱壁的加强筋分布相似,特定工况下按照优化结果进行加强筋布置的舱壁结构强度更好,拓扑优化技术可在特定工况下为舱壁结构的加筋布置提供指导。展开更多
Combining multiple crop protection Unmanned Aerial Vehicles(UAVs)as a team for a scheduled spraying mission over farmland now is a common way to significantly increase efficiency.However,given some issues such as diff...Combining multiple crop protection Unmanned Aerial Vehicles(UAVs)as a team for a scheduled spraying mission over farmland now is a common way to significantly increase efficiency.However,given some issues such as different configurations,irregular borders,and especially varying pesticide requirements,it is more important and more complex than other multi-Agent Systems(MASs)in common use.In this work,we focus on the mission arrangement of UAVs,which is the foundation of other high-level cooperations,systematically propose Efficiency-first Spraying Mission Arrangement Problem(ESMAP),and try to construct a united problem framework for the mission arrangement of crop protection UAVs.Besides,to characterise the differences in sub-areas,the varying pesticide requirement per unit is well considered based on Normalized Difference Vegetation Index(NDVI).Firstly,the mathematical model of multiple crop-protection UAVs is established and ESMAP is defined.Furthermore,an acquisition method of a farmland’s NDVI map is proposed,and the calculation method of pesticide volume based on NDVI is discussed.Secondly,an improved Genetic Algorithm(GA)is proposed to solve ESMAP,and a comparable combination algorithm is introduced.Numerical simulations for algorithm analysis are carried out within MATLAB,and it is determined that the proposed GA is more efficient and accurate than the latter.Finally,a mission arrangement tested with three UAVs was carried out to validate the effectiveness of the proposed GA in spraying operation.Test results illustrated that it performed well,which took only 90.6%of the operation time taken by the combination algorithm.展开更多
文摘为减少三体船结构质量以提高三体船总体性能,同时保证结构质量减少后三体船舱壁结构具有足够的结构强度,本文基于《Rules for The Classification of Trimarans》设计了7个三体船结构强度校核工况。应用变密度拓扑优化方法,计算了优化前、后三体船舱壁结构在不同工况下的应力分布。计算及优化结果表明:特定工况不同体积约束条件下,优化后舱壁结构应力最大值与体积减少比例之间不存在正相关关联;通过优化能在保证结构安全的前提下,减少舱壁优化区域内50%的结构重量,实现非水密舱壁结构的轻量化设计;通过与实船舱壁设计对比,优化后舱壁连接材料的分布与实船舱壁的加强筋分布相似,特定工况下按照优化结果进行加强筋布置的舱壁结构强度更好,拓扑优化技术可在特定工况下为舱壁结构的加筋布置提供指导。
基金the China Postdoctoral Science Foundation Grant(2019M661912)Major Scientific and Technological Innovation Projects in Shandong Province(2019JZZY020616)+1 种基金Opening Foundation of Key Laboratory of Modern Agricultural Equipment(Ministry of Agriculture and Rural Affairs),the Project of Scientific Research and Development of the University in Shandong Province(J18KA128)Cotton innovation team of Shandong modern agricultural industry technology system(SDAIT-03-09).
文摘Combining multiple crop protection Unmanned Aerial Vehicles(UAVs)as a team for a scheduled spraying mission over farmland now is a common way to significantly increase efficiency.However,given some issues such as different configurations,irregular borders,and especially varying pesticide requirements,it is more important and more complex than other multi-Agent Systems(MASs)in common use.In this work,we focus on the mission arrangement of UAVs,which is the foundation of other high-level cooperations,systematically propose Efficiency-first Spraying Mission Arrangement Problem(ESMAP),and try to construct a united problem framework for the mission arrangement of crop protection UAVs.Besides,to characterise the differences in sub-areas,the varying pesticide requirement per unit is well considered based on Normalized Difference Vegetation Index(NDVI).Firstly,the mathematical model of multiple crop-protection UAVs is established and ESMAP is defined.Furthermore,an acquisition method of a farmland’s NDVI map is proposed,and the calculation method of pesticide volume based on NDVI is discussed.Secondly,an improved Genetic Algorithm(GA)is proposed to solve ESMAP,and a comparable combination algorithm is introduced.Numerical simulations for algorithm analysis are carried out within MATLAB,and it is determined that the proposed GA is more efficient and accurate than the latter.Finally,a mission arrangement tested with three UAVs was carried out to validate the effectiveness of the proposed GA in spraying operation.Test results illustrated that it performed well,which took only 90.6%of the operation time taken by the combination algorithm.
