Results 31 to 40 of about 636,519 (177)
Dizhen xuebao, 2022 为探讨“最不利地震动”概念在地下结构抗震设计中的适用性，以软土地铁区间隧道为对象建立相应的地层-结构动力分析模型。以直径变形率为分析指标，基于动力时程方法研究18条不同输入地震动作用下隧道结构动力响应的分布及差异性，得出基于隧道地震响应的输入地震动排序，并通过调幅手段对比分析了地面峰值加速度（PGA）和隧道埋深变化对隧道结构地震动响应排序的影响规律。最后，评价了不同输入地震动参数，包括峰值加速度、峰值速度、峰值位移、绝对累积速度（CAV）和阿里亚斯（Arias）强度（IA）与隧道地震响应之间的相关性 ...
Haitao Yu, Jing Li, Qi Wang
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Regulatory compliance and support for altered management of the exotic pet trade
Conservation Biology, EarlyView.Abstract Globally, the exotic pet trade has contributed to species invasion, disease, and animal welfare risks. Although scientists have advocated for increased trade regulation, the success of management and regulatory efforts depends on compliance by participants in the exotic pet trade. We used a regulatory compliance framework to investigate exotic
Elizabeth N. Pratt +3 more
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Shiyou jixie, 2015 为了研究J型铺设升沉运动对管道应力的影响，利用ABAQUS软件对管道进行有限元建模，分析了不同水深、铺管角度和管道容重下船体下方10 m和TDP附近管道的动态响应。建模时采用PSI单元模拟管道与海底土壤之间的相互作用，将土壤反力定义为非线性。分析结果表明，在船体升沉运动影响下，轴向张力的变化是导致管道应力变化的重要因素；TDP附近的应力变化不仅要考虑轴力变化，还要考虑弯矩变化；若以增大壁厚的方式增大容重，则管道抗弯刚度增大，尽管TDP处管道静态应力呈增大趋势，但最大动态应力相差不大 ...
焦晓楠 +5 more
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Assessing differences among elasmobranch nurseries to aid conservation based on a genomics framework
Conservation Biology, EarlyView.Abstract Elasmobranch nurseries often differ in environmental conditions, demographics, and use patterns. These differences affect the distribution of genetic variation among nurseries. However, conservation and management strategies often fail to account for such differences because they are difficult to characterize.
Dominic G. Swift +8 more
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Dizhen xuebao, 2019 以地下隧道对附近场地动力特性的影响为研究目标，基于弹性波动理论，利用波函数展开法和镜像法，分析了弹性半空间中圆形衬砌隧道对平面SH波入射产生的散射问题，得到了地下圆形衬砌隧道附近场地位移的级数解答。通过数值算例分析了地下圆形衬砌隧道对场地动力响应的影响，重点考察了SH波入射角度、入射频率和隧道埋深、衬砌刚度对隧道周围土体动力响应随深度变化的影响规律。结果表明，地下隧道对沿线场地的地下地震动影响显著。
Fengxi Zhou, Lingmeng Gao, Qiang Ma
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Emerging applications of large language models in ecology and conservation science
Conservation Biology, EarlyView.Abstract Large language models (LLMs) mark a major development in artificial intelligence, with potentially transformative implications for ecology and conservation science. Built on advanced deep‐learning architectures, these models can support a wide range of tasks. We reviewed emerging applications of LLMs, drawing on the wider scientific literature
Christos Mammides +5 more
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Zhendong Ceshi yu Zhenduan非线性结构在稳态激励下存在多重响应，采用传统振动实验方法很难直接获得非线性结构的动力学特性。针对此问题，提出了基于加速度响应控制步进正弦扫频实验技术的恒定力动力学特性测试方法。首先，选择激励点处的加速度响应作为控制信号，通过控制其响应幅度恒定进行步进正弦扫频实验；其次，根据不同加速度幅值工况实验获得简谐激励谱和简谐加速度响应谱曲线，并利用线性插值构造平滑的简谐力面；然后，通过从简谐力面中提取恒定力幅值的等值线，即为非线性结构恒定力幅值工况的频响曲线；最后，对典型螺栓连接非线性结构开展动力学特性研究 ...
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Evaluating the use of taxonomy in the IUCN Red List
Conservation Biology, EarlyView.Abstract Taxonomy defines the units that conservationists strive to preserve for future generations. However, the discovery of new species and the taxonomic revision of existing species affect conservation efforts. Despite the importance of taxonomy for a species’ conservation, there is currently no overview of how those leading species extinction risk
Stephen T. Garnett +8 more
wiley +1 more source
强台风下高压输电线路塔—线耦联体系的力学行为仿真分析三:动静力响应对比
Gaoya dianqi, 2016 高压输电线路风致倒塔事故是近年来影响电力系统安全运行的重要因素。文中以南方电网某220 kV输电线路为背景,考虑铁塔和导、地线之间的耦联影响,运用ANSYS有限元分析软件,建立直线段塔线耦联三基塔两回线模型,对模型分别施加设计风速下的风载荷与时变风载荷,对比模型在两种情况下的静动力位移、应力响应数值差异,分析表明塔—线体系中铁塔的x、z向动力响应位移明显大于静力响应位移,铁塔部分主材轴应力与静力响应数值相比明显增大。研究结果可用于输电线路在风载荷作用下的可靠性分析。
贺博 +5 more
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Scientists’ warning on the global destruction of rock outcrop ecosystems
Conservation Biology, EarlyView.Abstract Rock outcrops are geological formations that harbor a highly specialized biota adapted to harsh environmental conditions that differ from their surrounding landscapes. They are globally distributed, especially in old, highly weathered landscapes, and can function as habitat islands containing high levels of endemism and distinct evolutionary ...
Luiza F. A. de Paula +19 more
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