浅谈预制楼板灌缝开裂原因及预防措施

通过多年的现场观察及工程实践,对预制楼板灌缝开裂产生的原因和预防裂缝的措施等进行阐述。     

预防楼板缝开裂的几项技术措施

本文初步探讨了楼板缝开裂这一通病的形成原因和解决方法。     

关键参数对灌缝比影响的研究

针对开裂路面,常用的维护手段是对裂缝进行灌缝处理。为了研究灌缝过程中影响灌缝比的关键参数及其变化规律,采用Fluent软件进行仿真计算,模拟了整个灌缝处理过程,并分析了裂缝深宽比、喷射压力、流体粘度、喷嘴直径对灌缝比的影响。结果表明:灌缝比随裂缝深宽比增大近似线性降低;灌缝比随裂缝深度的增加而增加,在一定范围内,灌缝比的增速较快,但流体到达一定深度后,灌缝比基本不再随裂缝深度变化;灌缝比随喷射压力增加逐渐增大,且增速逐渐减小;随着流体粘度增加,灌缝比逐渐减小,其关系在一定粘度范围内近似线性变化,随着粘度继续增加,灌缝比变化的速度有变缓的趋势;灌缝比随喷嘴直径增加逐渐减小,且随着喷嘴直径增加,灌缝比变化增快。     

一种新型沥青灌缝装置设计

设计了一种实用新型沥青灌缝装置,该新型沥青灌缝装置能有效克服现有灌缝技术缺点,养护作业人员手持该沥青灌缝装置时转身灵活,提高了灌缝操作灵活性和方便性,非常适用于修补路面不规则裂缝,大大提高灌缝效率。     

灌缝技术在机场道面施工中的应用

以中国商飞江西生产试飞中心机场道面施工为背景,结合项目工程地质特点,分析了机场道面接缝的类型,提出机场道面施工中灌缝技术的具体要求,总结了以灌缝技术施工条件、灌缝技术施工要点和灌缝技术施工方法为主的机场道面灌缝关键技术。     

甲醇合成塔环缝开裂的现场检修问题研究

甲醇合成塔在甲醇装置中占据着重要的位置，具有操作压力较高、易燃易爆的特点，并具有一定的毒性。一旦出现事故，既会带来严重的经济损失，还可能引发人员伤亡。本文先对甲醇合成塔进行概述，然后分析了甲醇合成塔环缝开裂的具体原因，最后提出了甲醇合成塔环缝开裂的现场检修策略，希望能为甲醇合成塔的应用提供一定的参考。     

预制钢筋混凝土楼板板缝开裂原因分析

分析钢筋混凝土空心板在民用住宅应用中，楼板板缝开裂问题，提出了预防措施及处理办法。     

预制钢筋泥凝土楼板板缝开裂原因分析

分析钢筋混凝土空心板在民用住宅应用中,楼板板缝开裂问题,提出了预防措施及处理办法.     

一种新型混凝土路面沥青灌缝机的PLC控制

根据某创新设计的热气流加热式混凝土路面沥青灌缝机技术设计要求,结合其使用环境和现有条件,通过优化组合控制设计及多次试制总结,采用PLC对系统实施自动控制,完成了整机的设计制造。     

预制钢筋泥凝土楼板板缝开裂原因分析

分析钢筋混凝土空心板在民用住宅应用中,楼板板缝开裂问题,提出了预防措施及处理办法.     

现浇钢筋混凝土楼板裂缝成因分析及防治对策

对混凝土现浇楼板产生裂缝的原因进行分析并提出了具体解决问题的办法。     

Protection against degradation of the edge contour in fast-ionization dynistors

The results of studying silicon semiconductor devices with nanosecond turning-on times, that is, fast-ionization dynistors (FIDs), are presented. The effect of an abrupt increase in the leakage current that flows through an FID upon blocking of the power voltage after the termination of a train of switched pulses is discovered and described. It is shown that under certain conditions this effect may result in the destruction of the FID. Methods for modifying FIDs are presented that allow stabilization of the leakage current.     

轿厢意外移动保护装置研究

电梯在人员出入轿厢的时候,如果发生非正常移动,容易造成挤压和剪切的事故。为了避免此类事故的发生,提出应制定强制性的标准设置一种防止轿厢意外移动的装置,此装置应为机电联动结构,一旦检测到轿厢意外移动必须马上强制制停电梯。事实证明,轿厢意外移动保护装置能有效减少轿厢意外移动发生的剪切事故,保证乘客安全。     

Radiographic inspection of the weld seams: Test parameters

The EN 1435 standards and State Standard GOST 7512 are compared and corrections to State Standard GOST 7512 are recommended.     

Controlling the shop floor

Installing a new computerised control system is never particularly easy, and many different approaches have been advocated. Nick Norton describes the selection and implementation of a manufacturing control system for J.J. Harvey (Manchester) Limited.     

关于轿厢意外移动保护系统检测电路的探讨

首先简要介绍轿厢意外移动保护装置(UCMP)的定义以及相关标准的技术要求,接着通过分析一种常见的UCMP检测电路,指出该电路存在的缺陷,最后提出观点,即:UCMP检测电路为含电子元件的安全电路时,传感器(感应开关)应是安全电路的一部分,并应满足安全电路风险评价要求。     

多输出CCD接缝校正

针对多输出CCD传感器成像存在接缝的问题,提出了一种基于延时积分（TDI）的校正方法。使用TDI的读出方式对均匀光源成像获得了具有亮度线性渐变的图像数据,建立了获得图像的行平均灰度和行曝光时间关系的模型,通过该模型对CCD每路输出特性进行拟合,校正了CCD多输出的不均匀性,解决了图像接缝问题,并在模拟前端（AFE）完成了校正过程。本方法仅使用一次成像过程,避免了辐照度调整精度对校正精度的影响。与传统的两点法和多点法（16点）相比,提出方法的输出非均匀性分别减少了2.428%和 1.052%,校正效果明显提高。实验显示：本方法校正精度高,实验工作量低,可以广泛用于多输出CCD的接缝校正中。     

皮带机防压死拉断保护装置的设计分析

为更好的防治带式输送机的压死拉断问题,基于某公司DTL100/75-2×160型带式愉送机运行工况,分析了皮带压死拉断故障原因与当前所用保护控制回路的不足,设计了皮带防压死拉断保护装置,提出了设计思路与具体设计方案,并进行了安装调试,实际应用结果表明,该装置运行稳定,能很好的防治皮带输送机的压死拉断问题,具有一定的推广...     

Vertebrate floor plate transiently expresses a compound recognized by antisera raised against subcommissural organ secretion

Located along the ventral midline of the neural tube, the floor plate (FP) performs an essential role in central nervous system development, especially in the patterning of the ventral region of the neural tube and axonal guidance. Several studies have been directed to the identification of molecules mediating some of the functions of the FP. Most of the models proposed for floor plate actions involve contact-mediated- and/or gradients of diffusible-signals acting throughout the nervous tissue. This report presents and discusses findings showing that the FP cells secrete a novel compound, which is recognized by antisera raised against secretory products of the subcommissural organ (SCO). This immunoreactive compound appears to be very similar to one of the glycoproteins secreted by the SCO. This immunoreactivity is expressed transiently during central nervous system development, and its rostro-caudal extension along the anterior-posterior axis of the FP displays some species variations. However, a constant feature in all species investigated is that this immunoreactive compound is highly expressed in the FP located in the mesencephalic-metencephalic boundary. The distribution of this compound is compatible with basal and apical pathways of release from FP cells. The former might participate in the formation of some brain commissures. The latter might involve the use of the cerebrospinal fluid as a route for performing actions on distant targets, a pathway somehow disregarded by most models accounting for morphogen actions.