基于弯剪梁模型和Von Karman风速谱的高层建筑风振系数实用算法

为使风振系数计算中采用的振型函数更符合高层建筑振型特点且易于计算，采用基于弯剪梁模型的高层建筑基本振型简化算式，同时采用Von Karman与高度有关的风速谱模型和Davenport与频率有关的空间相关性模型，建立高层建筑风振系数计算的实用算式，并通过算例与我国现行荷载规范中的风振系数算式进行比较。结果表明，该方法考虑了不同高层建筑振型的特点，既提高了计算精度，简单实用，又便于与国际主流荷载规范接轨。     

格构式塔架顺风向脉动风荷载空间相关性研究

为了研究格构式塔架顺风向脉动风荷载的空间相关性,选取2段典型的格构式塔架节段模型,采用2个高频测力天平同步测力风洞试验技术,得到了不同水平距离和竖向距离情况下的模型基底剪力和弯矩的风荷载时程.在此基础上,通过数据处理分析,得到了各工况下塔架的顺风向风荷载相干函数.试验结果显示:格构式塔架顺风向风荷载相干函数与频率,水平距离和竖向距离等参数有关;结构顺风向风荷载相干函数与顺风向风速以及高层建筑等结构的风荷载相干函数存在一定差别.最后,采用最小二乘法,拟合得到了格构式塔架顺风向风荷载相干函数经验公式,试验结果与经验公式吻合较好,可为格构式塔架风荷载及风致响应计算提供有用的参考.     

某拟建838m高楼多自由度气弹模型风洞试验研究

为了考察某拟建超高层建筑(总高838m)在设计风速下的风致响应,对该大厦进行了多自由度气弹模型风洞试验.模型自振特性测试表明,该气弹模型各横截面对两个正交的水平主轴对称,每个轴向1阶和2阶频率误差分别在1%和28%以内,1阶阻尼比约为2%,平动振型与实际结构有限元模型计算结果较为一致.分析不同风速和风向角下风致响应发现,该大厦顶部在100年重现期设计风速下最大动态侧移为0.89m,且动态位移本身并未使结构顶部位移超标,而10年,50年和100年重现期下风致加速度响应超过规范阈值幅度分别为16%,23%和29%.另外,该大厦横风向涡振使得临界风速附近横风向风致响应明显偏大,如果假定风荷载谱为白噪声,则横风向1阶气动阻尼比对总响应的贡献达37%.若欲保证该建筑在百年一遇风速下加速度在允许范围内,则须使其结构阻尼比在2.9%以上.     

轻型门式刚架结构的等效静力风荷载

针对现行规范对轻型门式刚架结构风荷载的取值没有考虑脉动风荷载空间相关性的情况,分别采用荷载响应相关法和国外风荷载规范求得门式刚架结构风荷载的分布和大小,基于与现行规范计算结果的对比分析,提出轻型门式刚架结构等效静力风荷载分布的估计方法.基于刚性模型同步测压风洞试验测得的门式体形模型表面风荷载时程数据,建立了轻型门式刚结构架有限元整体模型.通过按建议方法求出的风致响应与实际动力响应极值的对比,验证了建议的风荷载分布的合理性,计算结果表明采用该方法得到的风致响应更接近实际动力响应极值,且表达形式简洁,方便工程设计使用.     

风力机塔架结构风振试验的模化方法(英文)

本文讨论了风力机塔架相似模型的建立,并把强风瞬时风速记录变换为符合相似条件的风模型。采用激振器对塔架模型做模拟风激振试验以及在静风荷载作用下塔架模型的光弹实验。完成上述工作,即构成了完整的风致振动的模化实验方法。     

基于改进大涡模拟模型的风荷载验证

为了获得与近地大气边界层实际脉动风场特征相一致的三维脉动风速,文章首先应用DSRFG(Discretizing and Synthesizing of Random Flow Generation)方法,模拟生成计算流体动力学中大涡模拟算法所需的模拟入口边界脉动风速时程,然后采用改进的动态一方程模型作为大涡模拟的亚格子模型,计算长宽高为1∶1∶3的高层单体矩形建筑在0度风向角下的风荷载分布及特性,并与日本TPU风洞试验进行了对比.结果表明:1当高层建筑长宽比(B/D)=1时,扭矩的能量主要来自涡旋脱落而不是入口湍流的影响;2DSRFG结合改进的动态一方程模型能够较为准确地模拟得到高层建筑表面的平均及脉动风荷载特征.此方法有望应用到实际高层建筑风荷载评估中.     

漏斗形开敞式膜结构的风致振动效应分析

采用谐波叠加法模拟风速时程,将风速时程转换为风荷载时程施于漏斗形膜结构,分析膜结构风振响应,获得结构各区块风致动力放大系数.计算表明：漏斗形敞开式膜结构各节点位移响应较为稳定且具有周期性,速度响应曲线和加速度响应曲线均较稳定;结构表面不同部位的风振响应差别较大,迎风面的风致动力放大系数较高,背风面风致动力放大系数平缓.     

大型风力机塔架在脉动风下的动力响应特性研究

采用Kaimal脉动风功率谱,考虑脉动风的空间相关性,采用AR模型模拟风电场脉动风速时程,并验证脉动风速谱与目标谱的一致性;通过有限元方法计算风力机塔架结构在风载荷作用下的动力响应特性。计算结果表明:AR模型对实际风场风速进行有效模拟,考虑脉动风的影响,塔架的风振响应显著增加;随着风速的增加,塔架的振动也随之增加,这为风力机塔架的风致响应分析和抗风研究提供了实用方法。     

坡地高层建筑非稳态雷暴冲击风荷载特性研究

目前结构风工程对于雷暴冲击风风荷载的研究多局限于稳态冲击射流模型,较少考虑风速随时间的变化以及坡地地形等因素的影响.基于冲击射流模型,引入衰减函数使得射流的入口风速更加接近真实的雷暴冲击风整个生命周期的衰变过程,并通过瞬态大涡模拟(LES)分析了坡地地形中坡顶位置处典型高层建筑的建筑风荷载特性及坡地地形雷暴冲击风场特性.结果表明,LES瞬态模拟具有较高的可靠性,非稳态冲击风场的风速波动较大,变化规律与实测的下击暴流风速曲线类似;建筑表面的风荷载具有强烈的非平稳特性,且随着风速迅速衰减;非稳态冲击风的风荷载波动大且潜在破坏能力更强;坡地地形下建筑迎风面风荷载普遍比平地小,且对建筑中上部的影响明显要大于底部,随着起坡角度的增大,建筑中上部风荷载逐渐减小.     

基于层内力等效的偏心高层建筑三维等效静力风荷载

对于质心和刚心不重合的偏心高层建筑，由于结构三维振型耦合与气动力耦合等因素的影响，其等效静力风荷载的评估变得十分复杂. 基于振型加速度法，推导了考虑三维气动力耦合和振型交叉项贡献的偏心高层建筑各层拟静力项和惯性力项内力（剪力和弯矩）响应计算方法. 在此基础上，基于各层内力响应等效，建立了能合理反映荷载沿高分布信息的结构三维等效静力风荷载评估方法. 随后，结合3种典型矩形截面高层建筑刚性模型测压风洞试验，分析了荷载相关性、结构偏心率和截面长宽比对偏心结构三维等效静力风荷载的影响. 研究表明：对于偏心截面高层建筑，振型交叉项和荷载相关性对结构风致响应与等效静力风荷载的贡献不可忽视，若忽略两者则会低估偏心高层建筑三维等效静力风荷载，特别是扭转向等效静力风荷载. 此外，偏心率和截面长宽比同样影响偏心高层建筑等效静力风荷载的大小和分布情况. 相关研究可为偏心高层建筑的抗风设计提供一定的指导.     

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.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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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