温度对沥青混合料密实度的影响

<正> 沥青混凝土的密实度对沥青混凝土的物理力学性质特别是沥青混凝土面层的使用性能和使用寿命有至关重要的影响。同一种沥青混凝土,在不同密实度下的现场空隙率有着明显的差别。国内外研究证明:①沥青混凝土的空隙率过大,降水容易透入结构层中,使沥青路面产生各种各样的水破坏;②沥青混凝土的空隙大于8%时,空气容易进入结构层中,使沥青容易氧化变脆,从而导致沥青混凝土松散,产生裂缝,间接影响路面的使用寿命;③空隙率增大,沥青混凝土的疲劳寿命和弯拉劲度下降。研究表明,热拌沥青混凝土的空隙率每增加1%,沥青面层的使用寿命就要降低10%。     

芯样空隙率与路面水损害的影响规律

该文通过取芯检测沥青混合料的空隙率,采用高温浸水条件下的多轮车辙试验研究空隙率和沥青含量对路面水损害的影响规律.结果表明,行车带处上、中面层车辙深度明显大于路肩处的上、中面层的车辙深度;随着空隙率(空洞)的增大车辙深度有较为明显的增大;基于上、中面层空隙率的养护措施选择原则为:空隙率6%~8%,采用"中"强度养护措施;空隙率8%~12%时,采用"强"强度的养护措施;空隙率大于12%时,建议采用矫正性养护措施.研究成果为运营期沥青路面内部缺陷的判别及养护措施的制定提供了重要依据.     

基于侧向位移法的沥青路面抗车辙影响因素

为分析当前高速公路严重车辙路段流动性车辙的影响因素,建立了沥青路面三维有限元模型.以沥青层的侧向(横向)位移为评价指标,分析了不同沥青层材料、不同沥青层结构组合及不同基层形式对流动性车辙产生的影响.给出了减少流动性车辙产生的对策;提出了沥青结构层协调组合设计的理念;指出了级配碎石联结层的使用不仅会减少高温下沥青上、中面层的侧向流动变形趋势,还会减小上、中面层的横向位移.     

基于介电常数沥青路面均匀性评价研究

现有沥青路面均匀性评价方法由于工作量原因局限于小范围检测评价,无法进行长距离大面积的评价。通过分析沥青路面离析现象的存在位置与频率,结合三维探地雷达与无核密度仪检测工作效率,提出两者最佳检测区间长度。根据三维探地雷达与无核密度仪检测原理提出检测控制因素。通过实地检测获得新建沥青路面介电常数与空隙率数据,采用多层前向反馈神经网络构建沥青路面介电常数与空隙率的关系,确定沥青路面介电常数离析阈值;进而实现通过介电常数进行长距离大面积的沥青路面均匀性评价工作。     

基于介电常数沥青路面均匀性评价

现有沥青路面均匀性评价方法由于工作量原因局限于小范围检测评价,无法进行长距离大面积的评价。通过分析沥青路面离析现象的存在位置与频率,结合三维探地雷达与无核密度仪检测工作效率,提出两者最佳检测区间长度。根据三维探地雷达与无核密度仪检测原理提出检测控制因素。通过实地检测获得新建沥青路面介电常数与空隙率数据,采用多层前向反馈神经网络构建沥青路面介电常数与空隙率的关系,确定沥青路面介电常数离析阈值;进而实现通过介电常数进行长距离大面积的沥青路面均匀性评价工作。     

排水沥青路面空隙变化下的动力响应分析

分析排水沥青路面在渗流和动荷载联合作用下的动力响应过程,提高排水路面行车安全.通过设计物理实验获取沥青混合料参数,建立排水沥青路面数值分析模型,分析路面内部空隙变化下的排水沥青路面超孔隙水压力和特征应力的时程变化情况,并与普通密级配沥青混凝土路面进行对比.结果表明：在行车荷载作用下,排水沥青路面内出现超孔隙水压力的正、负交替变化,在面层与基层交界面处最为严重,排水面层和防水层渗透性的差别会导致局部超孔隙水压力突变.排水沥青路面排水面层内的超孔隙水压力远小于密级配沥青混凝土面层和其他结构层,排水面层中竖向应力较密级配沥青面层大,且超孔隙水压力的消散速度更快.     

基于BP-PSO联合算法的沥青混合料空隙率反演计算

为提高沥青混合料空隙率反演计算效率,提出一种基于BP神经网络和PSO联合算法的沥青混合料空隙率反演计算方法.通过建立探地雷达电磁波在沥青路面结构层中的传播仿真模型,利用BP神经网络对仿真样本进行训练,得到能够反映输入和输出关系的回归曲面.利用PSO算法对回归曲面进行寻优,得到最优解.将该联合算法应用于沥青混合料空隙率反演计算中,反演计算结果表明:该联合算法能够在满足计算精度的条件下大幅提高计算效率,证明应用该联合算法反演计算沥青混合料空隙率的可行性和有效性.     

基于WRELAX时延估计算法的沥青面层分层厚度检测

沥青面层不同材料层的探地雷达(GPR)反射信号相互叠加,会降低沥青面层厚度检测的精度.为此,文中利用WRELAX时延估计算法分析沥青路面的1 GHz空耦GPR反射信号,以提高沥青路面分层厚度检测精度,并通过仿真实验和现场检测进行了效果验证.研究结果表明:WRELAX时延估计算法通过强信号搜索并在迭代计算中逐步去除强信号,使微弱的重叠信号得以显现,从而可以提取出信号时延和幅度的参数信息;1 GHz雷达信号应用WRELAX时延估计算法处理后可以有效检测沥青面层分层厚度,而且估计误差波动相对较小,算法稳健性较好,总体效果优于2 GHz雷达信号;WRELAX时延估计算法的沥青面层分层厚度估计最大相对误差小于5%,满足沥青路面分层厚度检测和评价要求.     

动载作用下沥青路面内部孔隙水压力的轴对称弹性解

将沥青路面视为多层饱和弹性半空间轴对称体,引入比奥渗流固结理论和渗流方程.利用Hankel和Laplace积分变换等数学方法,推导出浸水沥青路面的沥青路面水损害力学模型,并做出如下假设:除渗透性外,沥青混凝土是均质的、完全饱和的理想弹性材料;沥青混凝土的变形是微小的;沥青混凝土和孔隙水均不可压缩;孔隙水渗流服从达西定律,渗透系数为常数.计算了沥青路面结构层孔隙水压力大小.结果表明,沥青面层内的孔隙水压力与面层渗透系数、面层厚度、结构层材料参数以及车辆行驶速度等有密切关系.当路表孔隙饱水时,在荷载作用下,面层中以及面层与基层的接触面附近孔隙水压力最大,在荷载的反复作用之下,导致疲劳开裂破坏,加速路表病害的出现.     

材料参数对沥青混合料高温稳定性的影响

为了提高国内高速公路沥青路面的高温稳定性,针对沥青路面中面层常用的19型沥青混合料,分析了集料级配、沥青类型、沥青用量、空隙率等材料参数以及压实方法、实验温度等因素对19型沥青混合料高温稳定性的影响.试验结果表明,沥青混合料的抗高温车辙受集料级配和沥青性能的双重影响,同时采用油石比在最佳油石比基础上低0%～0.3%和4%的空隙率时,沥青混合料的高温稳定性最好.     

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