Results 31 to 40 of about 32,954 (259)
Guangtongxin yanjiu, 1992 本文探讨非线性SELFOC光纤的模式转换。给出了计算这种光纤轴对称模式转换的公式。结果表明,如果n2P（n2:非线性系数,P:功率）较大,那么克尔非线性效应导致了模式转换。
陈智浩, 蔡声镇
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Integrative Conservation, Volume 4, Issue 2, Page 154-164, June 2025.This study identified self‐efficacy as a crucial outcome of nature education, with the potential for achieving long‐term conservation goals. Using a mixed‐methods design, we evaluated the effect of a wildlife course implemented in ten rural elementary schools in China, which significantly increased students' self‐efficacy, and also contributed to pro ...
Zhijian Liang +6 more
wiley +1 more source
Nonlinear finite element analysis for seismic performance of high-strength concrete beam-column joints with new reinforcement details [PDF]
, 2006 Because the factors that affect the behavior of the beam-column joints are complicated, an experimental study alone is not sufficient. Therefore, a nonlinear finite element analysis was conducted to provide better understanding of the performance of the ...
Gan, L, Li, J, Pam, HJ
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Jianzhu Gangjiegou Jinzhan, 2019 Kelvin多面体空间刚架是一种新型的空间结构形式。首先采用弯曲起拱方式建立了柱面Kelvin多面体网壳模型;接着研究了切割面位置、边界条件、旋转角度和荷载分布对网壳静力承载力的影响;最后分别采用几何非线性和双非线性方法,研究了不同工况下网壳的稳定承载性能。结果表明:相同工况下,旋转60°时网壳相比未旋转时的轴力减小、弯矩变化不大,两侧边支承时网壳相比四角点支承时的轴力增大、弯矩较小;柱面Kelvin网壳以局部屈曲模态为主,几何非线性分析时的荷载-位移曲线基本呈线性增长,双非线性分析时在最大竖向位移为0.
庞崇安, 王震
doaj
Integrative Conservation, Volume 4, Issue 2, Page 134-142, June 2025.Our study addresses the significant knowledge gap regarding the wintering population and habitat utilization of the Yellow‐breasted Bunting (Emberiza aureola) in Nepal, providing crucial insights that can aid in the conservation of this critically endangered species in wintering grounds.
Hem Bahadur Katuwal +6 more
wiley +1 more source
Investigation of Plasmon-Enhanced Second-Harmonic Generation (PESHG) [PDF]
, 2016 等离激元增强二次谐波效应（Plasmon-EnhancedSecond-HarmonicGeneration，PESHG）由于其展现出了对于近场耦合效应、结构形貌变化等空间变化信息的极高检测灵敏度和空间分辨能力，因而在超空间分辨技术、高效的非线性光学转换器件、全光调制和转换以及超材料等研究领域受到越来越多研究者的关注。尽管PESHG的研究在近年来取得了很大的进步，但依然存在着许多重大的科学问题尚待解决。比如在具体的实验研究中如何引入PESHG对纳米尺度变化进行超高空间分辨表征及分析 ...
沈少鑫
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Guangtongxin yanjiu, 2013 基于非线性光学原理,周期性金属纳米结构与非线性光学材料复合可以实现全光开关。通过数值模拟周期性金属纳米结构附近的电磁场可知,周期性金属纳米结构的表面等离子体激元有着明显的局域场增强特性。这种强的局域场可以大大增加非线性材料的三阶非线性效应,使全光调控现象更明显,从而降低开关的阈值功率,并实现超快的响应速度,有望在将来全光通信网络中得到广泛应用。
陈婕, 陈莹, 赵浩岚
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Assessment of risk for pre‐eclampsia at mid‐gestation to define subsequent care
Ultrasound in Obstetrics &Gynecology, Volume 65, Issue 6, Page 694-702, June 2025.ABSTRACT Objective To stratify pregnancy care based on the estimated risk of pre‐eclampsia (PE) from screening at 19–24 weeks' gestation by combinations of maternal risk factors, estimated fetal weight (EFW), mean arterial pressure (MAP) and uterine artery pulsatility index (UtA‐PI).
S. Adjahou +5 more
wiley +1 more source
A class of iterative projection methods for nonlinear large sparse eigenvalue problems [PDF]
, 2008 本文研究了解大型稀疏非线性特征值问题的一类迭代投影法。非线性有理Krylov法和非线性Arnoldi法适用于求解非线性问题在一个区域内的多个特征值。二者都属于迭代投影法，在本质上是等价的，在实现方式上却有所不同。非线性Arnoldi方法可以采用高效的算法来求解投影小问题，在实现上更为灵活，一般说来其实现性能要好于非线性有理Krylov方法。但非线性有理Krylov法在计算过程中不必明确给出投影小问题，可能比较适用于某些应用问题。 非线性有理Krylov法将非线性问题线性化，只能近似求解投影特征值问题 ...
李长伟
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Guangtongxin yanjiu, 2017 VLC（可见光通信）系统中,LED（发光二极管）的调制带宽会限制传输速率,其非线性也会影响系统的整体吞吐量。针对OFDM（正交频分复用）VLC系统中由于高峰均比引起的非线性失真问题,提出了一种基于一位∑△调制器的非线性VLC系统。研究表明:在OFDM VLC系统中引入一位∑△调制器,能够提高频谱利用率,改善LED非线性对系统性能的影响。
戈立军, 陶进
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