Results 11 to 20 of about 680,507 (148)
, 2020 形状记忆合金(SMA)作为一种智能材料,相对于传统的驱动器具有功率重量比大、驱动电压低、质量轻、干净、无噪音等特性,被广泛应用在各领域.然而,非线性、迟滞、时变等因素影响了形状记忆合金的控制精度,限制了它的应用.为此,本文提出了自适应滑模反步控制方法,用于解决精确控制问题.文中首先搭建了实验装置,建立了形状记忆合金的机理模型; 然后,采用最小二乘算法辨识了模型参数; 最后,基于机理模型设计了自适应滑模反步控制器.实验结果表明,本文提出的方法具有动态响应快 ...
赵新刚, 张道辉, 李晓光, 张弼
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, 1990 对不可压缩层流二维干扰流动,本文提出一个干扰流动(IF)理论。IF理论要点为:1)干扰流动沿主流的法向被分为三层即粘性层、干扰层和无粘层,引进了法向动量交换为主导过程的干扰层概念。2)利用力学守恒律、三层匹配关系及文中引进的干扰模型,把三层的空间尺度及惯性-粘性诸力的数置级表示为单参数m的函数 ...
高智
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, 1980 本文介绍一种控制多台脉冲X光机同步运行的新型同步机。它具有抗干扰能力强,精度高,使用方便等特点。本文还对干扰机制和抗干扰措施以及仪器使用中如何保证可控精度的问题进行了探讨,并给出了应用结果——雷管爆炸 ...
杨业敏, 金辉
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Wildlife Letters, Volume 3, Issue 4, Page 143-151, December 2025.Effects of methylmercury bioaccumulation on survival of Columbia Spotted Frogs were modified by sex and length and were mediated by corticosterone (a glucocorticoid hormone) whereas effects of chytrid fungus were limited. ABSTRACT Amphibians have suffered widespread declines caused by many interacting factors whose effects are often difficult to ...
Brian J. Tornabene +7 more
wiley +1 more source
Gaoya dianqi, 2021 一二次融合开关是智能配电网建设的关键设备,其二次控制回路(FTU)安装在一次设备附近,处于电磁干扰环境中,但目前研究指出现行标准中的电磁兼容要求与实际电磁环境不符,在设备的运行中存在二次侧控制回路受电磁干扰严重的问题。为推动一二次融合设备试验标准化的改进,文中针对一二次融合设备电磁干扰抗扰度性能提出一种基于球隙放电的模拟电磁干扰试验方法,搭建试验平台开展一二次融合柱上开关传导干扰抗扰度试验并对互感器传递特性进行了分析。该方法可用于模拟系统中开关操作、击穿放电等工况中产生的放电干扰信号,可产生频率在1 ...
张志华 +5 more
doaj
Ecological Solutions and Evidence, Volume 6, Issue 3, July–September 2025.Over the past three decades, a large number of natural wild soybean populations have been declining inexplicably or even have disappeared and their distribution area has significantly decreased in China, and population losses continue unabated. Therefore, this study investigated 20 herbaceous communities of wild soybeans in various habitats in ...
Ke‐Jing Wang, Xiang‐Hua Li
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New Phytologist, Volume 247, Issue 2, Page 504-517, July 2025.Summary Repetitive DNA is a feature of all organisms, ranging from archaea and plants to humans. DNA repeats can be seen both in coding and in noncoding regions of the genome. Due to the recurring nature of the sequences, simple DNA repeats tend to be more prone to errors during replication and repair, resulting in variability in their unit length ...
Sridevi Sureshkumar +3 more
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Guangtongxin yanjiu, 2020 现有多输入多输出（MIMO）太赫兹通信网络双信道介质访问控制（MAC）协议工作在WiFi信道和太赫兹信道。多对节点同时在太赫兹信道传输数据存在波束重叠干扰问题,这会使消息传输的成功率和网络吞吐量下降。另外,在WiFi信道进行控制消息交互时存在的控制开销冗余问题会导致信道利用率低。基于这两个问题,文章提出了一种避免波束干扰的高效太赫兹双信道MAC协议（E-ABIMAC）。E-ABIMAC分为波束干扰预判机制、中继辅助机制和基于节点信息省略允许发送帧/确认帧（CTS/ACK）机制。仿真结果表明 ...
姚玉坤, 甘泽锋, 冯鑫, 刘顺辉
doaj
The enigmatic life history of the bamboo explained as a strategy to arrest succession
Ecological Monographs, Volume 94, Issue 4, November 2024.Abstract Bamboos are perennial woody grasses that display an enigmatic mix of traits. Bamboo is highly shade intolerant like early‐successional trees. Without secondary xylem, bamboos cannot continue to grow once they reach a maximum height or replace xylem damaged by hydraulic stress and must instead replace each stem after a few years using ...
Aiyu Zheng, Stephen W. Pacala
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, 1994 在激波区使用自适应壁对跨音速翼型上的激波／边界层的相互作用（干扰）进行控制;可改变机翼的气动性能。这种被动控制可通过在翼型的激波区开一凹腔;其上覆盖一弹性橡胶膜柔壁来实现。本文给出用Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ（Ｎ－Ｓ）方程数值模拟这一自适应控制翼型的跨音速粘性绕流;提出了一个适用于本特殊情况（物面边界局部地区在求解过程中有变化）的处理办法 ...
肖林奎, 马侠, 蒋金贵, 张绵纯
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