Results 31 to 40 of about 467 (87)
Study on flutter characteristics of NACA0012 flexible straight wing with high-aspect-ratio
Xibei Gongye Daxue Xuebao, 2022 采用三维雷诺平均N-S方程和S-A湍流模型求解展弦比为16的NACA0012弹性平直机翼的非定常气动力, 结合机翼动力学方程, 建立了机翼颤振时域分析方法。利用该方法对机翼的颤振特性、颤振过程中的变形和振动响应, 以及瞬时流场进行数值模拟和分析, 并研究材料刚度和密度对机翼颤振速度和频率的影响。结果表明, 由于展弦比较大, 且材质轻柔, 机翼会出现一定幅度的静弯曲变形。第二阶(垂向弯曲)和第三阶(扭转)振动模态的耦合作用是机翼发生颤振的原因, 且颤振频率介于这两阶模态固有频率之间 ...
YU Qiuyang +3 more
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Conservation Biology, Volume 38, Issue 3, June 2024.Abstract Reintroduced populations are typically considered to progress through establishment, growth, and regulatory phases. However, most reintroduction programs do not monitor intensively enough to test this conceptual model. We studied population indices derived from track activity of 4 threatened species (greater bilby [Macrotis lagotis], burrowing
Katherine E. Moseby +3 more
wiley +1 more source
Jianzhu Gangjiegou Jinzhan, 2003 <正> 在文章中提出了考虑局部失稳的3维二阶塑性铰分析。此分析方法考虑了结构系统和构件的材料非线性和几何非线性。这个问题和传统的二阶塑性铰分析相关,传统方法中并不考虑由于局部失稳而引起抗弯强度减低的问题得以解决,提出了评估钢框架性能的有效方法:包括考虑残余应变和弯曲的逐渐屈服、二阶效应、几何缺陷等。在研究中,用一个考虑宽厚比的模型来模拟局部失稳。所提出的方法通过与其它分析方法和LRFD的结果相比得到了验证 ...
方明霁
doaj
Dizhen xuebao, 2022 对Lg波衰减模型中建模误差的统计特征进行了系统研究，并建立了地壳二维Lg波衰减模型。由于Lg波振幅可能受到几何扩散函数的强烈影响，合理评估反演过程的误差对于能否使用最小二乘意义下的反演非常重要。通过在川滇及其邻近地区收集的建模误差样本，使用K-S数值检验方法、Q-Q图和正态分布图形检验方法对Lg波衰减层析成像反演的输入数据中建模误差的分布特征进行了统计分析。采用奇异值分解（SVD）和反投影方法，分别获得了川滇地区的QLg模型，定量计算模型的协方差矩阵和分辨率矩阵 ...
Yansong Hu +3 more
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World Affairs, Volume 187, Issue 1, Page 118-122, Spring 2024.Abstract A caste is one of the conventional four social strata into which Hindu society seperates its members. The scriptures from ancient India make reference to it. The four classes are the Brahmins (priestly people), the Kshatriyas (rulers, administrators, and warriors; also known as Rajanyas), the Vaishyas (artisans, merchants, businessmen, and ...
Md Nurul Momen, Md Abu Shahen
wiley +1 more source
Graphic method calculating Boolean E-derivative based on K-map(基于K图的布尔E-导数计算的图形方法)
Zhejiang Daxue xuebao. Lixue ban, 2013 分析了逻辑函数的K图和降维K图，在此基础上，从逻辑函数定义出发，讨论了用K图和降维K图计算逻辑函数一阶布尔E-导数和二阶布尔E-导数的图形方法，实例表明该方法具有直观、简单等特点，并且能给出布尔E-导数的最简与/或式.
LIXiao-hua(厉晓华) +2 more
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中西医结合护理, 2022 Objective To investigate the effect of interventions based on the transtheoretical model and stages of change on relief of anxiety in patients with maintenance hemodialysis.
WANG Jiaying (王嘉莹) +1 more
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Lianas shift towards larger sizes and more acquisitive trait values in an Asian tropical rainforest
Biotropica, Volume 56, Issue 2, March 2024.Liana communities showed a shift in trait values indicating that they changed towards more large, acquisitive lianas with rapid water use. There are more larger stems through time due to the relatively low mortality of the larger individuals, which is associated with relatively low levels of disturbance.
Qi Liu +3 more
wiley +1 more source
Jianzhu Gangjiegou Jinzhan, 2009 本文先建立四个有初始几何缺陷的框架结构,通过有限元分析分别得到这四个框架的竖向极限荷载Pcr和水平极限荷载Hcr;再对与这四个框架几何及截面相同但没有初始缺陷的框架,用之前计算得到竖向和水平极限荷载分别按一阶弹性分析和二阶弹性分析得到其内力,用我国现行《钢结构设计规范》(GB50017)中压弯杆件极限承载力验算式计算其名义应力,并与实际结果比较。结果证明,进行钢框架压弯杆件平面内稳定验算时,对框架采用二阶弹性分析,并将柱的计算长度取为实际柱长,所得验算结果较对框架采用一阶弹性分析 ...
王翼, 李国强
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Dizhen xuebao基于汶川MS8.0地震后在窦圌山坡顶和坡脚测点获得的9次余震记录，通过基线校正、滤波处理，得到各余震记录的傅里叶谱谱比及质点运动轨迹图，结果表明山体的自振频率具有多阶段性，其最大位移方位会出现在山体的横向或走向上，且山体存在偏振效应。将9次余震东西向和南北的水平向加速度时程以10°为单位进行分解得到324条新的时程曲线，基于分解合成后的时程记录，将坡顶与坡脚相同分解角度下的时程作比值，对其峰值加速度比和傅里叶谱谱比进行分析，结果表明二者最大值所在的方位均与山体最大位移所在的方位相同 ...
Wei Wang +5 more
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