Results 31 to 40 of about 5,862 (131)
Conservation Biology, Volume 39, Issue 2, April 2025.Abstract Accelerating rate of human impact and environmental change severely affects marine biodiversity and increases the urgency to implement the Convention on Biological Diversity (CBD) 30×30 plan for conserving 30% of sea areas by 2030. However, area‐based conservation targets are complex to identify in a 3‐dimensional (3D) ocean where deep‐sea ...
Laetitia Mathon +19 more
wiley +1 more source
Shiyou jixie, 2012 为进一步提高煤层气钻机的自动化水平，尽量减少司钻的操作，提高设备自检能力，研制了MC90Y煤层气车载专用钻机。该钻机采用电液控制方式，PLC控制器集中控制，起升和旋转系统使用比例容积泵调速，辅助系统采用恒压变量泵提供动力；起升系统采用平衡阀回路设计，实现了正载荷、负载荷和变载荷情况下的平稳运行；采用手柄方位辨识控制，降低司钻的操作复杂性，优化起升和旋转系统的运行；控制系统具有自检、监测和自锁保护等功能，提高了钻机的安全保护能力。测试及现场应用结果表明，该钻机操作便捷，可控性好，运行平稳。
纪友哲, 闵庆利, 王金宏
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Uncovering Xi Jinping's Policy Agenda: Text As Data Approach
The Developing Economies, Volume 63, Issue 1, Page 9-46, March 2025.How many agendas has Xi Jinping put forth and promoted since taking office in 2012, and what are the types of agendas? How much of political attention has each agenda received, and how has the allocation of attention changed over time? We utilize a dataset of presidential statements, speeches, and reports from 2012 to 2022 and employed automated text ...
Jaehwan Lim, Asei Ito, Hongyong Zhang
wiley +1 more source
Gaoya dianqi, 2011 介绍了主动过电压保护的概念。通过动态模拟实验研究了利用可控串补硬件bypass运行模式限制系统故障期间串补电容两端过电压、减小短路电流的作用,提出了在系统发生短路故障时,减小短路电流,保护电容器的有效控制策略。
罗虎, 曲欣, 李慧娜
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Conservation Biology, Volume 39, Issue 1, February 2025.Abstract Trade restrictions are often advocated and implemented as measures to protect wild species threatened by overexploitation. However, in some instances, their efficacy has been questioned, notably by governments in the southern African (SADC) region, which tend to favor a sustainable use approach to wildlife management. We conducted a systematic
Christina Hiller +1 more
wiley +1 more source
Dianci bileiqi, 2015 结合视频监控系统信号传输的特点,设计用于视频监控系统保护的电涌保护器（SPD）。主要目的是抑制来自线路故障、开关动作过电压以及在信号线路上感应到的暂态雷电过电压,从而保护后端电子通讯设备免受电涌冲击。详细介绍了SPD的设计方案,采用电源、控制、视频三合一结构,由气体放电管和瞬态抑制二极管组成两级保护电路,选用合适的退耦元件以满足多级保护的能量配合,并通过桥式电路减小电路中的分布电容。通过理论分析与试验表明,该SPD具有电涌抑制能力强,电压保护水平低,插入损耗小等特点。
王志翔 +4 more
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Integrative Conservation, Volume 3, Issue 4, Page 294-311, December 2024.Freshwater biodiversity in China is threatened by multiple anthropogenic factors, and while there are some reasons to suppose it may be possible to bend the curve of biodiversity loss, the variety of threats and their likely interactions with ongoing climate change provide little basis for optimism. For example, the historic overexploitation of Yangtze
David Dudgeon
wiley +1 more source
Gaoya dianqi, 2008 研究了葛南直流控制保护系统改造完成后遗留下来的一个隐患,分析了葛洲坝换流站一次双极停运事故的现象,根据绝对最小滤波器组不满足的条件,指出无功控制与交流滤波器保护配合不当是这次事故的主要原因,同时找出有功功率回降软件功能不完善之处,最后给出了相应的解决办法,为将来更好地实施直流控制保护系统国产化改造提供参考。
田庆, 王晓希
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Conservation Biology, Volume 38, Issue 6, December 2024.Abstract Human–wildlife conflict (HWC) is a critical challenge to human development and well‐being and threatens biodiversity conservation. Ideally, HWC mitigation should benefit both wildlife and communities and limit the costs associated with living alongside wildlife.
Aalayna R. Green +8 more
wiley +1 more source
Gaoya dianqi, 2012 笔者分析了天广直流控制保护系统改造完成后发生的3次双极线路保护动作事件,剖析其中直流线路突变量保护误动作的原因。根据天生桥换流站和广州换流站的实际录波和实际过程,结合厂家给出的突变量保护定值和整定思想,分析导致突变量保护误动作的因素。笔者给出了2个解决方案——降低低电压保护定值和增大突变量保护的动作延时,并经实践验证正确,为以后更好地实施直流控制保护系统国产化改造提供参考。
田庆
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