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气候变化下新疆乌伦古河上游蒙新河狸的潜在分布变化
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作者 苏灿霞 初雯雯 +5 位作者 撇力扎提·巴哈提别克 江晓珩 陈艳秋 黄文溥 马驰 初红军 《干旱区研究》 CSCD 北大核心 2024年第3期509-520,共12页
蒙新河狸(Castor fiber birulai)在我国仅分布于新疆阿勒泰地区的乌伦古河流域,研究蒙新河狸潜在适生区的分布对该物种的保护具有重要意义。使用2021—2022年野外实地调查收集的97个蒙新河狸家族分布位点,结合28个环境因子,利用MaxEnt... 蒙新河狸(Castor fiber birulai)在我国仅分布于新疆阿勒泰地区的乌伦古河流域,研究蒙新河狸潜在适生区的分布对该物种的保护具有重要意义。使用2021—2022年野外实地调查收集的97个蒙新河狸家族分布位点,结合28个环境因子,利用MaxEnt模型预测不同气候情景下新疆乌伦古河上游蒙新河狸适宜生境区的分布。结果表明:影响蒙新河狸适宜生境分布的主要环境因子是距道路距离(0.1~1 km)、距水渠距离(小于3 km)、土地覆盖类型(河流、湿地与林地)、海拔(1000 m左右)、最湿月雨量(22~25 mm)与温度季节性变动系数(1500以上)的影响。当前蒙新河狸适宜生境沿乌伦古河上游河流紧密分布、区域狭窄。在2050s(ssp585气候情景)与2070s(ssp126气候情景)期间高适生区分别与当前持平或增加,未来两种气候情景较当前蒙新河狸适宜生境面积均有所降低,适宜生境降低的区域基本相似。本研究结果为气候变化影响下的蒙新河狸的保护与管理提供参考依据。 展开更多
关键词 蒙新河狸 MaxEnt模型 适宜生境区 乌伦古河上游
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SELECTION OF OBJECTIVE FUNCTIONS AND APPLICATION OF GENETIC ALGORITHMS IN DAMPING DESIGN OF PIPE SYSTEM 被引量:1
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作者 chenyanqiu FanQinsban ZhuZigen 《Acta Mechanica Solida Sinica》 SCIE EI 2003年第2期171-178,共8页
The vibration failure of pipe system of aeroengine seriously influences the safety of aircraft.Its damping design is determined by the selection of the design target,method and their feasibility.Five objective functio... The vibration failure of pipe system of aeroengine seriously influences the safety of aircraft.Its damping design is determined by the selection of the design target,method and their feasibility.Five objective functions for the vibration design of a pipeline or pipe system are introduced,namely,the frequency,amplitude,transfer ratio,curvature and deformation energy as options for the optimization process.The genetic algorithms(GA)are adopted as the opti- mization method,in which the selection of the adaptive genetic operators and the method of implementation of the GA process are crucial.The optimization procedure for all the above ob- jective functions is carried out using GA on the basis of finite element software-MSC/NASTRAN. The optimal solutions of these functions and the stress distribution on the structure are calculated and compared through an example,and their characteristics are analyzed.Finally we put forward two new objective functions,curvature and deformation energy for pipe system optimization.The calculations show that using the curvature as the objective function can reflect the case of minimal stress,and the optimization results using the deformation energy represent lesser and more uni- form stress distribution.The calculation results and process showed that the genetic algorithms can effectively implement damping design of engine pipelines and satisfy the efficient engineering design requirement. 展开更多
关键词 objective function genetic algorithms OPTIMIZATION pipe system
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