珠江黄埔大桥钢箱梁温度长期监测与分析

基于珠江黄埔大桥结构健康监测系统为期一年的温度监测数据,详细分析了北汊斜拉桥和南汊悬索桥扁平钢箱梁的温度分布特性.采用统计学方法建立了钢箱梁顶板和底板温度以及顶板和底板竖向温差的概率分布模型,确定了具有一定重现期的钢箱梁温度和竖向温差标准值.分析结果表明:钢箱梁横截面温度分布具有对称性,并且顶板与底板之间存在较大的竖向正温差;钢箱梁顶板和底板温度均可以通过2个正态分布函数的加权和来描述其概率分布,顶板和底板竖向正温差则可以通过2个Weibull分布函数的加权和来描述其概率分布.在此基础上分别计算了重现期为50年的钢箱梁温度和竖向正温差标准值.研究结果可为我国温热地区的大跨钢箱梁桥全寿命设计提供参考.     

润扬悬索桥扁平钢箱梁局部应力的测试与分析

为了计算钢箱梁的局部应力并与现场实测进行对比分析,基于子模型法提出了大跨悬索桥扁平钢箱梁应力分析的数值计算方法.以润扬悬索桥为例,建立全桥的整体结构尺度模型,并通过成桥试验验证了该模型的准确性.选取跨中钢箱梁建立局部构件尺度的精细模型.在局部模型的切割边界,应用子模型法衔接两尺度模型进行钢箱梁局部应力的数值计算,并与成桥静载试验的测试结果进行了对比分析.在此基础之上,系统地总结了大跨悬索桥钢箱梁结构在车辆荷载作用下的工作行为和受力性能.结果表明,钢箱梁顶板U形肋存在较大的应力变化幅值,应作为结构健康监测与疲劳状态评估的重点构件.     

多室混凝土箱梁二维温度梯度研究

文章基于对儒乐湖大桥的温度监测,采用假设检验和最小二乘法对多室混凝土箱梁实测温差进行了统计分析;根据监测数据提出多室箱梁的二维温度梯度曲线,并与现行铁路桥梁规范的温度梯度曲线进行比较。研究结果表明:南昌及其周边地区多室混凝土箱梁横向和竖向实测温差服从三参数对数正态分布;竖向和横向温度曲线可表示为2个指数函数相加,模拟温度场与实测值吻合良好,能较准确地描述多室箱梁的温度分布特性。     

混凝土厚壁箱形墩温度场观测与数值模拟

在现场实测温度资料的基础上,分析了某混凝土厚壁箱形墩在日照温差作用下的温度分布,并参照国内外规范及经验公式,用指数函数形式拟合出了最大温差时刻的温度梯度模式,分析结果对研究贵州地区混凝土墩柱结构的温度分布规律及同类型桥梁的设计和施工有一定的参考价值.采用有限元程序ANSYS对箱墩温度场进行了数值模拟分析,其理论计算结果与实测值吻合较好,从而证明了用ANSYS模拟温度场的可行性.该方法同样适用于同类型混凝土结构的温度场模拟.     

随机车流作用下悬索桥钢桥面板疲劳损伤与寿命评估

为了评估大跨度悬索桥钢桥面板在车流荷载作用下疲劳安全性,在实测车流数据的基础上,采用有限元数值模拟方法对某主跨为820 m的悬索桥钢箱梁顶板-U型肋构造细的疲劳损伤及寿命进行研究。通过对动态称重(WIM)实测车流数据的统计分析建立随机车流模型,基于应力-寿命(S-N)曲线和线性累积损伤准则分析运营状态和交通量增长对悬索桥钢桥面板构造细节疲劳损伤及寿命的影响。研究结果表明:随着密集运行车辆占有率的增加,疲劳损伤呈较缓增长趋势;随着交通量系数的增长,疲劳损伤呈加速增长趋势。与密集运行车辆占有率相比,交通量增长系数对疲劳损伤有较大的影响。在交通量增长系数达到6%时,钢桥面板细节疲劳寿命小于设计基准期,基于实测车流数据的疲劳性能评估对确保钢桥面板在运营期的安全性尤为重要。     

逐级删失定时截尾恒加寿命试验模型的抽样方案设计

研究了对数正态分布下伴有随机移走的逐级删失定时截尾恒加寿命试验模型的抽样方案设计.假定产品的寿命分布遵从对数正态分布，被随机移走的试验产品数服从二项分布，其中每一个试验产品被随机移走的概率为p.考虑了高于正常状态的2个应力水平，并假定对数寿命分布的参数与应力水平是线性关系，推导了模型的Fisher信息矩阵，并通过极小化广义渐近方差得到低应力水平的值和试验样品的分配比例，最后使用OC曲线来确定接收系数和样本量.利用数值模拟的方法，得到了最优的低应力水平值、试验样品的分配比例以及相应的抽样方案.     

基于对流换热系数修正的钢箱梁温度场研究

为了研究对流换热边界条件对钢箱梁温度场分布的影响,提出了一种基于对流换热系数修正的钢箱梁温度场数值模拟方法.首先,基于商用软件Fluent计算了钢箱梁截面附近的风速分布,其次,以Fluent计算得到的钢箱梁截面各表面风速修正对流换热系数,并基于ANSYS有限元软件进一步对比研究了不同工况下钢箱梁温度场的分布特征.钢箱梁...     

截断删失数据下泊松分布参数的点估计

利用EM算法和MCMC方法对截断删失数据下泊松分布寿命参数的点估计进行了研究.利用逆变换法和舍选法对缺损数据进行了填充,获得了产品的完全数据,得到了参数的EM迭代公式.对满条件分布进行了抽样,把Gibbs样本的算术平均值作为参数的MCMC估计.随机模拟的估计效果较好,估计值比较稳定,且精度较高.     

高温浇注环境下钢桥面温度场及温度变形效应分析

采用数值模拟的方法研究浇注式沥青混凝土摊铺时钢桥面摊铺温度场及温度变形效应.建立钢箱梁温度场模型,对浇注式沥青混凝土摊铺过程中钢桥面温度场分布规律进行了数值模拟,拟合出最不利温度荷载公式.根据时空等效原理建立考虑施工过程的温度荷载公式,计算钢桥面板的局部温度变形,并分析其对铺装效果的影响.研究结果表明,摊铺10 min后钢板局部迅速升温至120℃,并在17 min后达到最大温度123℃,此阶段摊铺温度对钢板结构的影响较大;摊铺区域钢板会产生局部温度变形,最大竖向变形达到7.5 mm,使摊铺层局部厚度有偏差,模拟值接近1 mm.     

颗粒对各向同性湍流中温度场的影响

为考察各颗粒参数对颗粒与气相温度场间相互作用的影响,对非等温气固两相各向同性湍流进行直接数值模拟.结果表明,在具有温度梯度的各向同性湍流中,加大颗粒质量载荷可使气相温度脉动强度和温度耗散率单调递减,加大颗粒质量载荷和颗粒比热均可使温度场的概率密度函数明显偏离高斯分布.     

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     

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