多相导电混凝土的受弯开裂自监测性能

将结构型钢纤维(SF)、碳纤维(CF)及纳米炭黑(NCB)作为多相导电材料加入混凝土中,研究了多相导电材料对混凝土开裂后的力学性能、导电性能及裂缝扩展自监测性能的影响.建立了混凝土梁的受拉区表面电阻变化率(FCR)与裂缝张开位移(COD)之间的关系.结果表明:导电相材料的加入能够显著提高抗弯强度与弯曲韧性;多相导电材料对弯曲性能及裂缝扩展的自监测性能具有正混杂效应;电阻变化率与裂缝张开位移呈线性关系.     

炭黑导电混凝土和碳纤维炭黑导电混凝土电热试验

目的为开发出融雪化冰或室内升温用的新型功能混凝土材料,研究炭黑导电混凝土(Carbon Black Conductive Concrete)和复掺碳纤维炭黑导电混凝土(Carbon fiber-carbon Black Diphasic Conductive Concrete)的导电性能以及电热效应.方法通过制作两种材料插有电极的立方体混凝土试块并测量记录不同龄期下的电阻率,比较分析两种材料的导电性能,并考虑碳纤维对导电性的影响作用.将两种材料试块分别串联进直流电路中,观察其通电发热情况并比较发热效果和电阻率的变化情况.结果相对于炭黑导电混凝土,复掺碳纤维炭黑导电混凝土的导电性更好,其中炭黑掺量为1%、碳纤维掺量为2%的试块电阻率低于100Ω·cm.两种材料通电发热速率均比较稳定且升温效果较好.单掺炭黑导电混凝土试块电阻率随通电时间延长变化较稳定,而复掺碳纤维炭黑试块电阻率受极化效应影响较大.结论相对于单掺炭黑导电混凝土,复掺碳纤维炭黑导电混凝土有更好的导电性,但其电阻率稳定性还有待研究.而单掺炭黑导电混凝土在通电发热试验中,其电阻率变化较小,具有较好的电阻率稳定性.     

碳纤维粉改性水泥砂浆压阻特性分析

为改善压阻特性,对砂浆掺加CF（Carbon Fiber,碳纤维）粉、硅粉进行改性,开展了试件的压阻测试,并对应变-电阻率曲线进行了分析。结果表明：试件的电阻率随压应变的增加而下降;应力-电阻率曲线可分为接触、承载和破坏阶段;CF掺量为2%时,其灵敏度最高,线性区间最大; CF掺量为2%时,单掺、复掺试件的线性相关系数分别为99.92%和99.45%;CF掺量为4%时,单掺、复掺试件的线性相关系数分别为98.39%和98.33%;CF掺量为6%时,CF粉会出现团聚现象,试件应力-电阻率符合指数关系;在单掺和复掺试件中,4%接近CF粉掺量的逾渗阀值;复掺试件的强度高于单掺试件,Si4/CF4的抗压强度达到52.4 MPa。可见,Si4/CF4试件具有较高的强度、压阻线性度和区间,但其灵敏度、线性区间不及Si2/CF4。     

碳纤维钢渣混凝土强度及导电性能研究

将碳纤维和钢渣复相导电组分加入到水泥基中制备成导电混凝土,不仅能起到增强的作用,而且还具有良好的导电性能.通过试验的方法,探讨了碳纤维含量不同的两组混凝土随钢渣掺量对抗压强度和电阻率的影响.试验结果表明:在碳纤维混凝土中加入一定量的钢渣,不仅能有效增加混凝土的抗压强度,而且能够改善纤维混凝土的导电性能.在不影响混凝土导电性能的条件下,通过掺加钢渣降低碳纤维的使用量,节约导电混凝土的材料成本.     

碳纳米管/水泥基复合材料导电机理的研究

利用四极法对碳纳米管/水泥基复合材料（MWNT/CC材料）的直流Ⅰ-V特性和交流阻抗特性进行了对比研究,同时采用SEM方法对碳纳米管在MWNT/CC材料的分布情况与连接情况进行了观察.研究结果表明,碳纳米管（MWNT）的掺入可以明显降低MWNT/CC材料的电阻率;不同MWNT掺量的MWNT/CC材料的电阻率在直流电压与交流电压下有相同的变化规律,且当MWNT掺量较高时,MWNT/CC材料内部出现了电容;当MWNT掺量较低时,MWNT/CC材料体现为非接触导电;当MWNT掺量提高到0.3％（占水泥质量的百分比）时,接触导电和非接触导电在MWNT/CC材料内部同时存在.     

电解质对离子导电混凝土电阻率的影响

普通混凝土电阻率很大,电解质溶液具有较好的导电性能且廉价易得,本文利用二电极法研究了电解质种类、电解质掺量、水灰比、导电温度等因素对离子导电混凝土电阻率的影响规律。实验结果表明,随电解质掺量、水灰比、导电温度的增加电阻率减小;以CaCl_2为导电相,掺量在1%~2%,水灰比为0.45,灰砂比为1:1时,离子导电混凝土的电阻率最小,且对离子导电混凝土的强度影响不大。由此表明,在混凝土中掺入电解质可以降低离子导电混凝土的电阻率,制备的离子导电混凝土通电后可应用于融雪化冰及电加热等实际工程应用中。     

碳纤维混凝土的导电性及其影响因素分析

以碳纤维作为导电基元材料,并利用羧甲基纤维素钠（CMC）对碳纤维表面进行改性,制备了一种导电性能良好的碳纤维导电混凝土．通过SEM微观测试,评价了所制备的导电混凝土中碳纤维的分散性,并分析了纤维体积掺量、水胶比、养护龄期对碳纤维混凝土导电性能的影响．结果表明,CMC能够明显改善碳纤维在混凝土中的分散性;水胶比和纤维掺量是影响碳纤维混凝土导电性能的主要因素,当混凝土的水胶比为0．6、碳纤维体积率0．62％时,所制备的碳纤维混凝土电阻率小于0．20Ω·m,满足电网工程中接地降阻技术的要求．     

利用铁屑和钢渣制备抗辐射混凝土的研究

为解决钢渣资源化利用问题,研究钢渣和铁屑在制备抗辐射混凝土上的应用。通过混凝土试块配合比设计及强度检测,发现:随着铁屑掺量的增加,混凝土抗压强度逐渐增大,当铁屑掺量达到30%时,抗压强度出现最大值;随着钢渣掺量的增加,混凝土抗压强度逐渐下降,当钢渣掺量大于20%后,抗压强度下降明显。利用研究结论制备抗辐射混凝土试块,在配合比:胶凝材料∶细集料∶赤铁矿石∶水∶减水剂为1∶3.11∶3.84∶0.41∶0.01时,力学性能、密度及和易性较好。此时,胶凝材料组成:水泥∶矿渣∶钢渣7∶2∶1,细集料组成:赤铁矿砂∶铁屑∶硼玻璃粉为1∶1.28∶0.49(体积比为4∶3∶3),混凝土试块密度为3 550 kg/m3、强度等级为C30。     

CB/PP复合材料的导电性能和PTC效应研究

采用碳黑(CB)Vulcan XC-72为填充材料、聚丙烯(PP)为基体材料制备了CB/PP导电复合材料,研究了CB含量对CB/PP复合体系导电性能和电阻正温度效应(PTC)的影响.结果表明:复合体系的电阻率随着CB含量的增加呈非线性的递减,当CB含量增大到2.5 wt%时,发生绝缘体—导体转变;同时复合体系的电阻率随温度的升高而增大,当温度达到167℃左右时发生突变,表现出PTC特性;并且CB含量越大,则复合体系的PTC强度越小.     

多壁碳纳米管对钢渣混凝土力学及耐久性能的影响

多壁碳纳米管(MWCNTs)作为新兴纳米材料,能够改善混凝土材料的宏观性能及微观结构。本文研究MWCNTs对钢渣混凝土的力学性能及耐久性能的影响,并利用扫描电镜(SEM)分析其增强机理。研究结果表明：MWCNTs掺量为0.08%时,钢渣混凝土的力学性能及耐久性能显著提高,28 d标准养护条件下,钢渣掺量为15%时,与未掺加MWCNTs的钢渣混凝土相比,抗压强度和抗折强度分别提高了13.2%和14.6%;28 d氯离子扩散深度和氯离子扩散系数分别降低了29.8%和27.4%;200次冻融循环过程中,掺入MWCNTs的钢渣混凝土质量损失率及相对动弹性模量变化率偏低,材料抗冻性能增强。MWCNTs通过桥联和拔出效应,可抑制微裂缝的产生和扩展,有效改善骨料界面过渡区,从而提高混凝土材料的力学性能及抗冻、抗氯离子侵蚀性能。     

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