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一个热带气旋移向变化的判据
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作者 周智翔 刘伯汉 《热带海洋》 CSCD 1991年第4期79-83,共5页
本文对热带气旋移向突变进行了动力学分析,得到影响路径变化的主要因子,并在此基础上设计了一个诊断气旋移向稳定性的判据,经两百多次计算检验,证实其准确率达84%强。
关键词 热带气旋 移向变化 稳定性 判据
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南海北部热带气旋移向突变的气候特征 被引量:4
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作者 胡斯团 黄大文 张儒林 《气象》 CSCD 北大核心 1995年第8期23-25,共3页
统计21年(1970-1990年)进入预报研究区(15-25°N,125°E以西)的热带气旋移向变化情况,分析移向发生突变的季节变化与地理分布等方面的气候特征。研究了热带气旋移向的突变与副热带高压活动、海岸地... 统计21年(1970-1990年)进入预报研究区(15-25°N,125°E以西)的热带气旋移向变化情况,分析移向发生突变的季节变化与地理分布等方面的气候特征。研究了热带气旋移向的突变与副热带高压活动、海岸地形的关系,得到一些有意义的结果,为寻找预报判据提供了气候特征的依据。 展开更多
关键词 热带气旋 气候特征 移向变化
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Shear mechanical properties and frictional sliding responses of rough joint surfaces under dynamic normal displacement conditions
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作者 ZHU Qiang YIN Qian +9 位作者 TAO Zhi-gang HE Man-chao ZHENG Bo-wen JING Hong-wen REN Shu-lin ZHANG Qiang MENG Bo BAI Dong-feng WU Sai-sai WU Jiang-yu 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第7期2393-2410,共18页
A comprehensive understanding of the dynamic frictional characteristics in rock joints under high normal load and strong confinement is essential for ensuring the safety of deep engineering construction and mitigating... A comprehensive understanding of the dynamic frictional characteristics in rock joints under high normal load and strong confinement is essential for ensuring the safety of deep engineering construction and mitigating geological disasters.This study conducted shear experiments on rough rock joints under displacement-controlled dynamic normal loads,investigating the shear behaviors of joints across varying initial normal loads,normal loading frequencies,and normal loading amplitudes.Experimental results showed that the peak/valley shear force values increased with initial normal loads and normal loading frequencies but showed an initial increase followed by a decrease with normal loading amplitudes.Dynamic normal loading can either increase or decrease shear strength,while this study demonstrates that higher frequencies lead to enhanced friction.Increased initial normal loading and normal loading frequency result in a gradual decrease in joint roughness coefficient(JRC)values of joint surfaces after shearing.Positive correlations existed between frictional energy dissipation and peak shear forces,while post-shear joint surface roughness exhibited a negative correlation with peak shear forces through linear regression analysis.This study contributes to a better understanding of the sliding responses and shear mechanical characteristics of rock joints under dynamic disturbances. 展开更多
关键词 dynamic normal displacement shear strength variations phase lag phenomenon STICK-SLIP
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Dynamics of the Alpine Treeline Ecotone under Global Warming:A Review
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作者 XU Dandan AN Deshuai ZHU Jianqin 《Journal of Resources and Ecology》 CSCD 2022年第3期476-482,共7页
The alpine treeline ecotone is defined as a forest-grassland or forest-tundra transition boundary either between subalpine forest and treeless grassland,or between subalpine forest and treeless tundra.The alpine treel... The alpine treeline ecotone is defined as a forest-grassland or forest-tundra transition boundary either between subalpine forest and treeless grassland,or between subalpine forest and treeless tundra.The alpine treeline ecotone serves irreplaceable ecological functions and provides various ecosystem services.There are three lines associated with the alpine treeline ecotone,the tree species line(i.e.,the highest elevational limit of individual tree establishment and growth),the treeline(i.e.,the transition line between tree islands and isolated individual trees)and the timber line(i.e.,the upper boundary of the closed subalpine forest).The alpine treeline ecotone is the belt region between the tree species line and the timber line of the closed forest.The treeline is very sensitive to climate change and is often used as an indicator for the response of vegetation to global warming.However,there is currently no comprehensive review in the field of alpine treeline advance under global warming.Therefore,this review summarizes the literature and discusses the theoretical bases and challenges in the study of alpine treeline dynamics from the following four aspects:(1)Ecological functions and issues of treeline dynamics;(2)Methodology for monitoring treeline dynamics;(3)Treeline shifts in different climate zones;(4)Driving factors for treeline upward shifting. 展开更多
关键词 alpine treeline treeline ecotone treeline dynamics treeline upward shifting
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