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Influencing Factors of Seed Long-distance Dispersal on a Fragmented Forest Landscape on Changbai Mountains,China 被引量:1
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作者 ZHAO Fuqiang QI Lin +1 位作者 FANG Lei YANG Jian 《Chinese Geographical Science》 SCIE CSCD 2016年第1期68-77,共10页
Seed long-distance dispersal(LDD) events are typically rare, but are important in the population processes that determine large-scale forest changes and the persistence of species in fragmented landscapes. However, pr... Seed long-distance dispersal(LDD) events are typically rare, but are important in the population processes that determine large-scale forest changes and the persistence of species in fragmented landscapes. However, previous studies focused on species dispersed via animal-mediated LDD, and ignored those dispersed by wind. The aim of this study was to assess the effects of canopy openness, edge, seed source, and patch tree density on the LDD of seeds by wind in forest. We collected birch seeds, a typical wind-dispersed species, throughout a larch plantation. We then assessed the relationship between birch LDD and each factor that may influence LDD of seeds by wind including distance to edge, canopy openness size, distance to mature forest, and the tree density of the larch plantation. We used univariate linear regression analysis to assess the influence of those factors on birch LDD, and partial correlations to calculate the contribution of each factor to LDD. The results showed that both canopy openness and edge had significant influences on birch LDD. Specifically, a negative relationship was observed between distance to edge and birch LDD, whereas there was a positive correlation between canopy openness size and LDD. In contrast, the distance to the mature forest was not correlated with birch LDD. Our results suggest that patch tree density could potently affect the probability of LDD by wind vectors, which provides novel and revealing insights regarding the effect of fragmentation on wind dynamics. The data also provide compelling evidence for the previously undocumented effect of habitat fragmentation on wind-dispersed organisms. As such, these observations will facilitate reasonable conservation planning, which requires a detailed understanding of the mechanisms by which patch properties hamper the delivery of seeds of wind-dispersed plants to fragmented areas. 展开更多
关键词 seed long-distance dispersal (LDD) forest fragmentation patch property wind dispersal Changbai Mountains
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基于局部感知环境分区评价的机器人运动控制 被引量:1
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作者 袁文博 曹志强 +1 位作者 刘希龙 谭民 《华中科技大学学报(自然科学版)》 EI CAS CSCD 北大核心 2013年第S1期38-41,共4页
提出一种基于局部感知环境分区评价的机器人运动控制方法,根据激光测距仪所提供的感知信息进行环境分区,引入距离影响因子,结合视觉指引及基于记忆的判断,产生各候选区评价,确定出适合当前环境的最优区用于移动机器人运动决策.实验结果... 提出一种基于局部感知环境分区评价的机器人运动控制方法,根据激光测距仪所提供的感知信息进行环境分区,引入距离影响因子,结合视觉指引及基于记忆的判断,产生各候选区评价,确定出适合当前环境的最优区用于移动机器人运动决策.实验结果表明:所提方法能够将感知环境进行较好的分区,并产生适合当前环境的最优区,实现了机器人的运动控制,验证了所提方法的有效性. 展开更多
关键词 移动机器人 局部感知 距离影响因子 基于记忆的判断 分区评价 运动控制
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基于改进人工势场法的多无人车编队路径规划 被引量:7
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作者 尹凤仪 刘芳 吴向阳 《无人系统技术》 2022年第6期24-30,共7页
为了解决传统人工势场法在路径规划上存在的目标不可达和局部极小值问题,提出一种改进的人工势场法算法,用于采用领航-跟随法的多无人车编队路径规划。针对目标不可达问题,建立无人车到达目标点附近的动力学模型,研究目标点附近的人工... 为了解决传统人工势场法在路径规划上存在的目标不可达和局部极小值问题,提出一种改进的人工势场法算法,用于采用领航-跟随法的多无人车编队路径规划。针对目标不可达问题,建立无人车到达目标点附近的动力学模型,研究目标点附近的人工势场的建立规则。当目标点附近出现障碍物时,通过在障碍物斥力场函数中加入距离影响因子,从而使无人车能够抵达目标点。经过改进后的斥力场函数,可以使无人车编队在2%的误差允许范围内,认为可以到达目标点。针对局部极小值问题,引入动态法向力,其方向根据领航车和跟随车的不同而进行分类,从而消除无人车陷入极小值的问题。MATLAB仿真结果表明,通过与传统人工势场法进行比较,改进方法可以有效避免无人车陷入局部极小值,无法到达目标点。大大减少无人车回归编队的时间,使无人车编队的路径更加平滑,并且可以将效率提高25%。提出的改进势场法可以有效解决传统人工势场法的目标不可达和局部极小值问题,使多无人车编队能够规划出较为平滑稳定的路线,保持编队队形并抵达目标点,验证了改进算法在多无人车编队路径规划上的可行性,为无人车编队的进一步路径优化奠定基础。 展开更多
关键词 人工势场法 路径规划 动态法向力 距离影响因子 多无人车编队 领航-跟随法
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