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81.
    
Runge‐Kutta pairs sharing orders 5 and 4 are among the most celebrated methods for solving initial value problems. Here, after considering the phase lag as a function of frequency v, we derive a modification of a particular pair. Namely, we present a zero dissipative pair with vanished phase error and its first derivative. After extended numerical tests in various oscillatory problems, it seems that this modified pair outperforms existing methods in the literature.  相似文献   
82.
    
Curved beam structures have been used in many civil, mechanical, aircraft, and aerospace constructions. The analysis is mainly based on solid and plate models due to the fact that traditional curved beam elements do not include nonuniform warping effects, especially in the dynamic analysis. In this article, independent warping parameters have been taken into account and the initial curvature effect is considered. Curved beam’s behavior becomes more complex, even for dead loading, due to the coupling between axial force, bending moments, and torque that curvature produces. In addition to these, the Isogeometric tools (b-splines or NURBS), either integrated in the Finite Element Method or in a Boundary Element–based Method called Analog Equation Method, have been employed in this contribution for the dynamic analysis of horizontally curved beams of open or closed (box-shaped) cross sections. Free vibration characteristics and responses of the stress resultants and displacements to moving loading have been studied.  相似文献   
83.
Bin Zhen  Jian Xu 《力学快报》2013,3(6):063004
Conditions for complete and lag synchronizations in drive-response systems are considered under the unified framework of generalized synchronization. The question is addressed that whether the synchronization conditions achieving complete synchronization is still valid for lag synchronization when the time delay of signal transmission between the drive and response systems increases from 0. Theoretical and numerical results show that whether the synchronization conditions is stable for the influence of the time delay of signal transmission depends on a particular form of equilibria of the drive and response systems. Furthermore, it seems that the less the number of the equilibria of the drive system, the more likely the synchronization conditions are stable for the time delay of signal transmission.  相似文献   
84.
This paper investigates retarded differential–algebraic equations of index zero to two with state-dependent delay. The theory needed to understand the numerical approach and analyze the numerical treatment by collocation methods is developed. Different strategies for tracking the jump discontinuities are considered and numerical examples are presented to support the convergence results. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
85.
Let W be a standard Brownian motion,and define Y(t) =∫ods/W(s) as Cauchy‘s principal value related to the local time of W. We study some limit results on lag increments of Y(t) and obtain various results all of which are related to earlier work by Hanson and Russo in 1983.  相似文献   
86.
Until recently, the issue of the thermal gradients within TMDSC samples remained mostly a subject of theory and mathematical models — only the phase lag was subject to experimental verification, as this information is readily available from the analysis software of most instruments. There was no method to verify the transient behaviour and temperature gradients within a sample without making costly and intensive modifications to the equipment. Recently, however, a group of researchers were able to experimentally measure thermal profiles as a function of sample thickness with a high-speed, high-resolution infrared camera mounted on the TMDSC cell. Therefore, this paper is dedicated to comparing the predictions of our three-dimensional model with this newly available data.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   
87.
本文研究了一类自治泛函微分方程的普遍方面和泛函方面对解的性质的影响,在较为广泛的前提下证明了这类方程解的存在性唯一性、有界性及渐近性.  相似文献   
88.
将变宽度截面箱梁的剪力滞翘曲位移函数定义为三次抛物线形式,用能量变分原理建立了分析变宽截面箱梁剪力滞效应的控制微分方程,并用差分法求解此方程。分别计算了简支箱梁在集中荷载和均布荷载作用下的正应力,并用有限元法作了验证。将计算结果与等截面箱梁的应力进行对比,总结变宽箱梁剪力滞效应的分布规律。结果表明,均布荷载作用下,相对于等截面梁,变宽箱梁的顶板应力变化幅度更大,峰值更高,箱梁的顶板宽度变化对剪力滞效应影响较大;在集中荷载作用下,等截面与变宽度箱梁跨中截面的应力相近,应力分布曲线吻合较好,说明顶板宽度变化对剪力滞效应影响较小;分别在集中和均布荷载作用下,箱梁跨中截面应力均为正剪力滞分布状态。当箱梁顶板、底板和悬臂板宽度相等时,剪力滞效应控制微分方程也适用于等截面箱梁。  相似文献   
89.
在政府低碳补贴政策下,本文考虑技术的时滞效应,构建政府、制造商和零售商的微分博弈模型,在分散决策下分析了制造商采用远视策略和短视策略时各方的最优决策,并将结果与集中决策下的对应情形进行了比较分析。研究发现滞后效应与政府的最优补贴比率负相关。制造商的短视策略并不一定会损害收益,若滞后时间超过特定阈值,那么企业将不会投资低碳技术。集中决策下减排努力、宣传努力、减排稳定值、商誉稳定值均高于分散决策,但满足一定条件时集中决策的供应链利润会低于分散决策。  相似文献   
90.
为揭示“高端备课”项目下教师与学生行为互动的关键特征,研究采用视频分析法及滞后序列分析法(LSA)对2019年高端备课项目中“离子反应”课堂中的师生交互行为、比率、教师语言、师生操作技术以及教师与学生之间的交互行为等进行量化与质性分析。研究发现,高端备课更加关注学生对于本源性认识问题的科学认识逻辑,以传授核心观念建构以及基于学生认识发展为本为理念,由知识解析为本向促进学生认识发展转变,通过师生思维不断碰撞的过程促进学生知识迁移与应用,为常态化课堂优化提供了参考路径。  相似文献   
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