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用于快速测试电路信号响应的袖珍型白噪声发生器
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作者 aaron shultz Peter Haak 《世界电子元器件》 2021年第6期21-27,共7页
问:能否同时产生所有频率的频谱?答:电路中的噪声通常都是有害的,任何好电路都应该输出尽可能低的噪声。尽管如此,在某些情况下,一个特性明确且没有其他信号的噪声源就是所需的输出。电路特性测量就是这种情况。许多电路的输出特性可通... 问:能否同时产生所有频率的频谱?答:电路中的噪声通常都是有害的,任何好电路都应该输出尽可能低的噪声。尽管如此,在某些情况下,一个特性明确且没有其他信号的噪声源就是所需的输出。电路特性测量就是这种情况。许多电路的输出特性可通过扫描一定频率范围内的输入信号并观测设计的响应来测量。输入扫描可以由离散输入频率或扫频正弦波组成。干净的极低频率正弦波(低于10 Hz)难以产生。处理器、DAC和一些复杂的精密滤波可以产生相对干净的正弦波,但对于每个频率阶跃,系统必须稳定下来,使得包含许多频率的顺序全扫描很缓慢。 展开更多
关键词 白噪声发生器 频率阶跃 测试电路 频率范围 输入频率 信号响应 电路特性 扫频
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Reimagining large river management using the Resist-Accept-Direct(RAD)framework in the Upper Mississippi River
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作者 Nicole K.Ward Abigail J.Lynch +22 位作者 Erik A.Beever Joshua Booker Kristen L.Bouska Holly Embke Jeffrey N.Houser John F.Kocik Joshua Kocik David J.Lawrence Mary Grace Lemon Doug Limpinsel Madeline R.Magee Bryan M.Maitland Owen McKenna Andrew Meier John M.Morton Jeffrey D.Muehlbauer Robert Newman Devon C.Oliver Heidi M.Rantala Greg G.Sass aaron shultz Laura M.Thompson Jennifer L.Wilkening 《Ecological Processes》 SCIE EI CSCD 2023年第1期645-664,共20页
Background Large-river decision-makers are charged with maintaining diverse ecosystem services through unprec-edented social-ecological transformations as climate change and other global stressors intensify.The interc... Background Large-river decision-makers are charged with maintaining diverse ecosystem services through unprec-edented social-ecological transformations as climate change and other global stressors intensify.The interconnected,dendritic habitats of rivers,which often demarcate jurisdictional boundaries,generate complex management chal-lenges.Here,we explore how the Resist–Accept–Direct(RAD)framework may enhance large-river management by promoting coordinated and deliberate responses to social-ecological trajectories of change.The RAD frame-work identifies the full decision space of potential management approaches,wherein managers may resist change to maintain historical conditions,accept change toward different conditions,or direct change to a specified future with novel conditions.In the Upper Mississippi River System,managers are facing social-ecological transformations from more frequent and extreme high-water events.We illustrate how RAD-informed basin-,reach-,and site-scale decisions could:(1)provide cross-spatial scale framing;(2)open the entire decision space of potential management approaches;and(3)enhance coordinated inter-jurisdictional management in response to the trajectory of the Upper Mississippi River hydrograph.Results The RAD framework helps identify plausible long-term trajectories in different reaches(or subbasins)of the river and how the associated social-ecological transformations could be managed by altering site-scale conditions.Strategic reach-scale objectives may reprioritize how,where,and when site conditions could be altered to contribute to the basin goal,given the basin’s plausible trajectories of change(e.g.,by coordinating action across sites to alter habitat connectivity,diversity,and redundancy in the river mosaic).Conclusions When faced with long-term systemic transformations(e.g.,>50 years),the RAD framework helps explicitly consider whether or when the basin vision or goals may no longer be achievable,and direct options may open yet unconsidered potential for the basin.Embedding the RAD framework in hierarchical decision-making clarifies that the selection of actions in space and time should be derived from basin-wide goals and reach-scale objectives to ensure that site-scale actions contribute effectively to the larger river habitat mosaic.Embedding the RAD framework in large-river decisions can provide the necessary conduit to link flexibility and innovation at the site scale with stability at larger scales for adaptive governance of changing social-ecological systems. 展开更多
关键词 ECOSYSTEM MANAGEMENT Transformation Social-ecological system ANTHROPOCENE Climate change Basin planning Cross-scale interactions
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