某船用钢动态断裂行为的温度效应

在高加载速率条件下,利用Hopkinson杆型动态断裂韧度测试装置测定了某船用钢在不同温度下的动态断裂韧度,首次获得了该钢动态断裂韧度随温度的变化规律,即随着温度降低,动态断裂韧度呈现明显的上下平台及韧脆转变特征.断口形貌则由上平台的微孔型延性断口、韧脆转变区的混合断口过渡到下平台的解理断口.同时,测定的动态断裂韧度值也为该钢在高加载速率条件下的韧脆转变行为及安全性评定提供了定量依据.     

四层两跨高性能混凝土框架的抗震性能

通过低周反复荷载试验对四层两跨高性能混凝土框架的破坏形态、破坏机制、恢复力模型、变形恢复能力、位移延性、刚度退化以及耗能能力等进行了研究,并对多层多跨框架结构的最优破坏机制进行了分析。研究表明,实现逐层梁铰机制的框架具有良好的整体延性和耗能能力,框架顶点和层间位移延性系数达到4.5~8.0。编制了基于恢复力模型的滞回全过程分析程序,应用该程序对四层两跨高性能混凝土框架进行了模拟计算,计算结果与试验值吻合良好。在此基础上,对高性能混凝土框架结构基于"中震可修"的性能指标及其限值进行了初步探讨。     

网络行为建模环境的实现及网络混沌性状分析

设计并实现了一种用于网络行为研究的网络行为建模环境，将网络环境的监测功能和网络行为的分析功能相互结合，为网络系统行为的研究奠定了基础。在这一环境下，归纳了四种有普遍意义的网络突发流量模型，并用混沌分形理论中的迭代函数系统和相空间重构方法对它们进行描述、分析、计算和重构，得到了它们的分形维以及能体现网络流量行为特性的宏观参数。     

特高含水油藏聚驱后非均相驱渗流规律

目的 针对特高含水油藏窜流问题严重、聚合物驱流度控制能力有限等问题,探索特高含水阶段非均相驱微观渗流特征。方法 通过微观可视化渗流实验、均质条件驱油及非均质条件调驱实验,评价了特高含水阶段水窜规律和聚驱对注水剖面的调整能力。结果 在特高含水阶段,注入聚合物和非均相体系后,驱替压差有效提高,最终采收率较水驱提高了32.8%;非均相体系的注入可在聚驱后继续动用低渗岩心中的剩余油,低渗填砂管采收率较水驱提高了38.1%。非均相体系有效动用了各类微观剩余油,含量显著降低。结论 非均相体系能够对窜流通道实现有效封堵,改善多孔介质的微观非均质性,促使驱替液转向并进入未波及区域,对剩余油实现有效的动用,进而提高原油采收率。     

内嵌碟簧型自复位防屈曲支撑性能试验及其恢复力模型研究

提出了一种内芯与约束构件均为型钢的全钢装配式防屈曲支撑,该支撑具有全装配、内芯可更换、工艺简单、造价低廉和可用于既有构件加固等优点。钢内芯由2个角钢与加劲板组成T型截面,外约束构件由角钢和盖板通过螺栓连接形成。对6个该支撑试件进行拟静力试验,讨论其滞回性能、抗震性能及破坏机理,并分析内芯上设置填板、内芯与约束构件的间隙、内芯双角钢之间的间距以及限位方式对滞回性能的影响。结果表明,该支撑的实际性能与设计性能基本一致,具有稳定的滞回性能;在支撑中间设置填板对支撑的滞回性能基本没有影响;内芯与约束构件的间隙及内芯双角钢之间的间距过大会降低支撑的滞回性能;采用中部限位方式的支撑滞回性能优于端部限位方式。对试件的抗震性能分析表明,该支撑具有较好的延性和累积塑性变形能力,可作为阻尼器应用于结构中。通过分析破坏模式发现,加劲板末端的焊缝应力集中会造成支撑的断裂位置由屈服段转移至止焊处;设置中部限位卡可以减小摩擦力的不利影响。     

基于改进Bouc-Wen模型的RC梁-柱节点抗震性能研究

该文基于美国太平洋地震工程研究中心结构性能数据库中的76根弯曲破坏及弯剪破坏的钢筋混凝土(Reinforced concrete, RC)圆柱试验数据,以峰值指向型改进Ibarra-Medina-Krawinkler (I-M-K)材料模型作为恢复力模型,采用OpenSEES有限元平台对所选择的RC圆柱试验数据进行数值模拟,识别得到了每一RC圆柱的恢复力模型参数。选取RC圆柱的15个基本设计参数为基本变量,采用多元线性回归和分步拟合,获得了RC圆柱恢复力模型参数的经验预测公式(值)。通过对试验验证组中3根RC圆柱的滞回试验数据进行模拟,对该文提出的RC圆柱恢复力模型参数的经验预测公式(值)的合理性进行了验证。结果表明：该文获得的经验预测公式(值)可以较为准确地预测RC圆柱的恢复力模型参数,可以较合理地反映RC圆柱在循环加载过程中的强度及刚度的退化特征。     

Electrochemical behaviors of benzoic acid at polyaniline/CuGeO3 nanowire modified glassy carbon electrode

20 wt.% polyaniline/CuGeO₃ nanowires have been used as glassy carbon electrode (GCE) modified materials for electrochemical determination of benzoic acid (BA) in neutral solution. The intensities of the anodic cyclic voltammogram (CV) peaks increase linearly with the increase of BA concentration and scan rate. The linear range is 0.001–2 mM and detection limit is 0.96 μM and 0.47 μM for cvp1 and cvp2, respectively at a signal-to-noise ratio of 3. 20 wt.% polyaniline/CuGeO₃ nanowire modified GCE exhibits good stability and reproducibility. Polyaniline plays an important role in the electrochemical responses of BA at polyaniline/CuGeO₃ nanowire modified GCE. The detection limit decreases to 0.64 μM and 0.28 μM for cvp1 and cvp2, respectively with the polyaniline content increasing to 40 wt.%. Polyaniline/CuGeO₃ nanowire modified GCE exhibit better electrochemical performance than traditional methods.     

脱层材料与槽接式挫屈束制支撑的性能研究

挫屈束制支撑耐震性能优劣与否与脱层材料性能有密切关系,首先提出了一种估算脱层不完全因子的方法,利用4组分别使用不同脱层材料的挫屈束制支撑进行构件试验;研究结果表明以黏性橡胶作为脱层材料具有可靠性、经济性与优良的施工性。特别介绍了地震工程研究中心近期所研发的槽接式挫屈束制支撑,并通过3组实尺寸构件试验验证了其耐震性能;测试构件包含一组长度为12.5m,最大抗压强度超过16800kN,核心消能段应变量达3.5%的构件。试验结果表明,新研发的槽接式挫屈束制支撑经济效益极高,迟滞消能行为良好稳定,具有优良的耐震性能,各组试体于试验停止前所累积的总非线性变形量皆超过400倍斜撑屈曲位移量;研究亦显示,非线性结构分析软件PISA3D可准确预测其受力与变形反应。     

Does cyberbullying overlap with school bullying when taking modality of involvement into account?

Education professionals and researchers are concerned by school bullying and cyberbullying because of its repercussions on students’ health and the school climate. However, only a few studies investigating the impact of school versus cyberbullying have systematically explored whether student victims and perpetrators are involved in school bullying only, cyberbullying only, or both. The aim of the present study was thus to examine the possible overlap, as well as the similarities and/or differences, between these two forms of bullying when taking modality of involvement into account. Individual interviews were conducted with 1422 junior high- and high-school students (girls = 43%, boys = 57%, mean age = 14.3 ± 2.7 years). Results showed that cyberbullying and school bullying overlapped very little. The majority of students involved in cyberbullying were not simultaneously involved in school bullying. Moreover, results indicated that psychosocial problems (psychological distress, social disintegration, general aggression) varied according to the form of bullying. Victims of school bullying had greater internalizing problems than cybervictims, while school bullies were more aggressive than cyberbullies. Given the sizable proportion of adolescents involved in bullying (school and cyber) and its significant relationship with mental health, the issue warrants serious attention from school and public health authorities.     

Rheological and thermal properties of epoxy nanocomposites reinforced with alkylated multi‐walled carbon nanotubes

The effects of functionalized multi‐walled carbon nanotubes (MWCNTs) on thermal and chemorheological behaviors of an epoxy‐based nanocomposite system were investigated. Chemical functionalization of MWCNTs by acid modification (A‐MWCNTs) and chemical amidation (D‐MWCNTs) was confirmed using Fourier transform infrared spectroscopy and thermogravimetric analysis. It was found that the D‐MWCNTs had a significant effect on the chemorheological behaviors of the epoxy‐based nanocomposite. Compared to the epoxy/A‐MWCNT nanocomposite, the epoxy/D‐MWCNTs nanocomposite showed a significant increase in gel time, as obtained from isothermal rheology measurements. Also, the storage modulus of the diglycidylether of bisphenol F (DGEBF)/D‐MWCNTs nanocomposite was higher than that of the DGEBF/D‐MWCNTs nanocomposite and gradually increased with an increase of frequency. This could be interpreted by the relatively strongly interconnected structure of the D‐MWCNTs in the DGEBF epoxy resin, which arises from the functionalized alkyl groups of the D‐MWCNTs in dispersion phases with the DGEBF epoxy resin. Copyright © 2012 Society of Chemical Industry