人虎冲突是全球野生虎(Panthera tigris)保护和种群恢复工作迫切需要解决的问题,而人虎冲突的分布特征是开展冲突管理的重要科学依据。珲春地区是东北虎(P. t. altaica)从俄罗斯向中国扩散的重要廊道,随着东北虎种群数量的逐步增加,该...人虎冲突是全球野生虎(Panthera tigris)保护和种群恢复工作迫切需要解决的问题,而人虎冲突的分布特征是开展冲突管理的重要科学依据。珲春地区是东北虎(P. t. altaica)从俄罗斯向中国扩散的重要廊道,随着东北虎种群数量的逐步增加,该地区的人虎冲突特征亟需开展研究。本文以2016―2020年珲春地区的人虎冲突事件为基础,基于占域模型分析获得人虎冲突发生位点的特征,探究了坡向、海拔、距猎物距离等12个因素对人虎冲突的影响。结果显示,259起人虎冲突均为虎捕食家畜事件,其中东北虎捕食牛的事件约占90%,且主要发生在每年的5—7月。从特征来看,坡向(∑w_(i)=0.44)、猎物分布(∑w_(i)=0.28)、海拔(∑w_(i)=0.18)和距针阔混交林的距离(∑w_(i)=0.13)对人虎冲突的发生具有较大的影响。人虎冲突在中海拔的阴坡、针阔混交林和猎物活动频繁的区域占域率更高。未来珲春地区应从加强放牧管理、划分不同等级的人虎冲突管理范围和提高社区居民的保护意识等方面来缓解人虎冲突的发生。展开更多
When the ship is sailing at sea,wave added resistance has great influence on the rapidity and economy of the ship.With the increasing pressure of energy and environmental protection,IMO has proposed the EEDI formula o...When the ship is sailing at sea,wave added resistance has great influence on the rapidity and economy of the ship.With the increasing pressure of energy and environmental protection,IMO has proposed the EEDI formula of the newly built ships,which restricts the energy consumption standard of civil ships more strictly.Therefore,a panel method based on three dimensional potential flow theory is proposed to study the problem of wave added resistance in this paper.Firstly,the method solves the motion responses of the ship in the time domain,and then calculates the wave added resistance of the ship by near-field pressure integration method.The wave added resistance of S175 container ship in head and oblique waves are calculated and compared with the experimental data,and the accuracy of the proposed method are verified.At last,the influence of Froude number and wave direction angle on wave added resistance is studied.The proposed method provides an approach of satisfactory accuracy and efficiency for the development of high-performance new ship forms,optimization of ship hull lines,comprehensive performance evaluation of ships and practical navigation guidance.展开更多
文摘人虎冲突是全球野生虎(Panthera tigris)保护和种群恢复工作迫切需要解决的问题,而人虎冲突的分布特征是开展冲突管理的重要科学依据。珲春地区是东北虎(P. t. altaica)从俄罗斯向中国扩散的重要廊道,随着东北虎种群数量的逐步增加,该地区的人虎冲突特征亟需开展研究。本文以2016―2020年珲春地区的人虎冲突事件为基础,基于占域模型分析获得人虎冲突发生位点的特征,探究了坡向、海拔、距猎物距离等12个因素对人虎冲突的影响。结果显示,259起人虎冲突均为虎捕食家畜事件,其中东北虎捕食牛的事件约占90%,且主要发生在每年的5—7月。从特征来看,坡向(∑w_(i)=0.44)、猎物分布(∑w_(i)=0.28)、海拔(∑w_(i)=0.18)和距针阔混交林的距离(∑w_(i)=0.13)对人虎冲突的发生具有较大的影响。人虎冲突在中海拔的阴坡、针阔混交林和猎物活动频繁的区域占域率更高。未来珲春地区应从加强放牧管理、划分不同等级的人虎冲突管理范围和提高社区居民的保护意识等方面来缓解人虎冲突的发生。
基金the National Natural Science Foundation of China(Nos.51709246,52171280,51609220,U1806229)。
文摘When the ship is sailing at sea,wave added resistance has great influence on the rapidity and economy of the ship.With the increasing pressure of energy and environmental protection,IMO has proposed the EEDI formula of the newly built ships,which restricts the energy consumption standard of civil ships more strictly.Therefore,a panel method based on three dimensional potential flow theory is proposed to study the problem of wave added resistance in this paper.Firstly,the method solves the motion responses of the ship in the time domain,and then calculates the wave added resistance of the ship by near-field pressure integration method.The wave added resistance of S175 container ship in head and oblique waves are calculated and compared with the experimental data,and the accuracy of the proposed method are verified.At last,the influence of Froude number and wave direction angle on wave added resistance is studied.The proposed method provides an approach of satisfactory accuracy and efficiency for the development of high-performance new ship forms,optimization of ship hull lines,comprehensive performance evaluation of ships and practical navigation guidance.