亚音速气流下不对称双跨黏弹性板的非线性振动特性研究

研究了亚音速气流作用下不对称双跨黏弹性板的非线性振动特性。考虑von Kármán几何大变形,利用Hamilton原理,建立了不对称双跨黏弹性板的非线性运动方程,并对其采用分离变量法进行了离散。运用线性势理论得到了亚音速气流的气动压力表达式。利用板的边界条件和中间支承条件得到了双跨板的模态函数。研究了来流速度对双跨板非线性振动特性的影响,分析了不对称程度和黏弹性阻尼系数对结构发生混沌运动的影响。     

屈曲粘弹性倾斜矩形板的非线性振动分岔

粘弹性矩形板在工程中经常发生各种振动 ,根据屈曲粘弹性倾斜矩形板的非线性动力方程 ,采用Melnikov法及Galerkin原理研究了其在铅垂周期扰力作用下的非线性振动分岔。并讨论分析了倾斜角、长宽比、板厚等因素对屈曲粘弹性矩形板发生混沌运动区域的影响 ,得到了倾斜角、板厚的增加会使混沌运动区域减小 ,长宽比的增大会使混沌运动区域变大的重要结论     

屈曲粘弹性倾斜矩形板的非线性振动分岔

粘弹性矩形板在工程中经常发生各种振动,根据屈曲粘弹性倾斜矩形板的非线性动力方程,采用Melnikov法及Galerkin原理研究了其在铅垂周期扰力作用下的非线性振动分岔。并讨论分析了倾斜角、长宽比、板厚等因素对屈曲粘弹性矩形板发生混沌运动区域的影响,得到了倾斜角、板厚的增加会使混沌运动区域减小,长宽比的增大会使混沌运动区域变大的重要结论。     

粘弹性地基上四边自由矩形中厚板的非线性自由振动分析

为了解决中厚板与粘弹性地基共同作用下的非线性振动问题,在Reissner-Mindlin一阶剪切变形板的理论基础上,运用pb-2瑞利-里兹法分析双参数粘弹性地基上四边自由矩形中厚板的非线性自由振动,探讨了板的尺寸参数、横向剪切因子、粘滞系数以及地基反应模量对板的振动特性产生的影响及其变化规律。并对数值算例进行编程求解,与文献实测数据进行对比,结果十分接近,证明了该方法的可行性。     

双跨弹性转子系统弯扭摆耦合非线性故障特征分析

建立了非对称弹性支承下,带有基础松动-碰摩耦合故障的双跨转子系统弯扭摆耦合非线性动力学模型.应用数值方法研究双跨转子弯扭摆耦合振动下的动力学特性,利用分岔图、幅频特性曲线图、相图及幅值谱图,分析了摆振对于双跨转子系统的影响,揭示了不同结构参数下该类转子系统的典型非线性特征,为该类转子系统故障诊断提供依据.结果表明:摆振对双跨转子系统的运动影响显著;具有松动故障的转子系统非线性幅频特性曲线呈现不光滑的多个波峰     

航空发动机压气机叶片的非线性振动问题

本文研究了航空发动机压气机叶片的非线性振动问题．将叶片简化为功能梯度材料的悬臂薄壁梁,因为是稳态气流,利用一阶活塞理论来计算气动力．考虑几何大变形的影响,利用Hamilton原理建立了叶片的非线性偏微分运动方程．运用Galerkin方法对方程进行一阶离散得到常微分控制方程．考虑1：1：1内共振情况,利用高阶多尺度法对控制方程进行摄动分析．基于平均方程,通过数值仿真模拟不同气流流速下旋转叶片的动态响应,得到相图、波形图和频谱图．结果表明：气流流速对系统动力学特性有重要影响,随着气流流速的增加,系统会呈现倍周期运动、周期运动、混沌运动等多种复杂动力学行为．     

非线性粘弹性桩的横向混沌运动

研究了轴向周期载荷作用下非线性粘弹性嵌岩桩的横向混沌运动．假定桩和土体分别满足Leaderman非线性粘弹性和线性粘弹性本构关系,得到的运动方程为非线性偏微分．积分方程;利用Galerkin方法将方程简化为非线性常微分方程,并进行了数值计算;考察了几个参数的影响．数值结果表明非线性粘弹性桩可以通过准周期分叉方式进入混沌运动状态．     

矩形薄板的混沌运动研究

研究了气流和面外激励共同作用下四边完全简支的矩形薄板的混沌运动行为。考虑几何大变形理论,利用Hamilton变分原理,建立了气流作用下矩形薄板的非线性振动偏微分方程;并将偏微分方程离散为常微分方程。运用线性势理论,得到了气流的气动力。用梅尔尼科夫方法得到了混沌运动存在的必要条件;数值模拟给出了振动系统的分叉图、相图和庞加莱截面,验证了必要条件的正确性。研究结果表明,随着来流速度的增加,矩形薄板会发生不稳定振动,出现混沌运动。     

损伤粘弹性正交铺设层合板的非线性振动分析

研究了考虑横向剪切变形和损伤效应的粘弹性正交铺设层合中厚板的非线性自由振动问题.基于一阶剪切变形理论、应变等效假设和Boltzmann叠加原理,建立了考虑横向剪切变形和损伤效应的粘弹性层合中厚板的非线性自由振动控制方程,且应用有限差分法、Newmark法和迭代法进行求解.算例中,具体讨论了损伤效应、不同跨厚比和长宽比对粘弹性层合板的非线性自由振动幅频响应曲线的影响.     

双质量微机电陀螺驱动轴结构不对称误差辨识

双质量微机电振动陀螺驱动轴振动的对称性是影响陀螺性能的重要因素,造成振动不对称的主要原因是驱动电容、检测电容和弹性梁刚度都存在不对称误差。该文建立了非理想双质量陀螺驱动轴的动力学模型,分析了刚度不对称和驱动力不对称对陀螺振动特性的影响。弹性梁刚度不对称误差是导致双质量块振幅不等的主要因素。提出了一种通过扫频测试和数据处理辨识不对称误差的方法,采用该方法对所研究的双质量陀螺的不对称误差进行了辨识。依据误差辨识参数对驱动轴振动模型的频率响应特性进行了计算,计算结果和测试结果一致,验证了该辨识方法的准确性。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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