弹性地基处周期性圆形钢筋混凝土管道振动特性分析

针对弹性地基处周期性钢筋混凝土管道的波动特性,基于声子晶体理论和Flugge壳体理论,建立了圆形管道环径向轴对称波动微分方程,利用传递矩阵法建立了相邻胞元间的传递矩阵,数值分析了周期性管道结构的能带特性。结果表明,振动波在传播过程中存在禁带域和通带域,弹性地基对弯曲波在特定频率范围内的传播具有抑制作用,长度比的变化对周期性圆形混凝土管道禁带的幅值、宽度和个数影响显著,因此可通过调整结构尺寸参数改变结构中波的传播特性。     

射频识别技术在钢管制造中的应用

介绍钢管管号识别方式,分析射频识别技术在钢管制作流程中的应用。分析认为:利用射频识别技术自动读取钢管管号,可以解决MES人工输入存在的输入错误、滞后等问题;射频识别设备具有远距离快速识别标签的特点,应用在钢管生产流程中可以最大限度地提高生产效率和准确性。射频识别技术应用近5年来,虽存在重复发卡、数据读取错误等问题,但通过技术和工艺调整,目前使用效果良好。     

建筑工程中常用塑料管材的性能对比与应用研究

介绍了目前建筑工程中塑料管材的发展和应用现状,对建筑工程中常用的几种塑料管材的性能特点及安装特点进行了对比分析,对建筑工程选用塑料管材的一般原则进行了总结,并对塑料管材市场的未来发展方向及重点进行了探讨。     

新型8MN/3MN钢管管端加厚机的开发

介绍新型8MN3 MN钢管管端加厚机的整体结构,重点分析其肘杆增力机构原理;通过与传统钢管管端加厚机的对比发现,研发的新型肘杆增力机构式钢管管端加厚机具有结构简单,生产效率高,性能稳定,节能降耗效果显著等优势。     

注水工况下的管柱水锤分析

注水过程中管柱内液体具有高压、高速流动的特点,一旦管内液体流动边界发生短时间变化,将会产生管内液体流速及压力的变化,可能造成管柱振动、密封失效甚至断裂。主要针对注水工况下,运用管道振动分析软件AUTOPIPE对管柱注水过程进行水锤模拟分析,重点对管内液体流速、压力、轴向振动速度以及轴向附加应力进行分析,为现场管道施工安全及优化提供参考。     

脱硝还原剂尿素法改造常见问题及优化探讨

近几年,脱硝还原剂尿素法改造常见于火电厂,这是为了消除液氨这一危险源。但在改造设计中,有些具体问题容易被设计人员忽视。以L公司为例,尿素制氨系统运行2 a多来,暴露出了卸料管振动大、溶解罐溢流管出气泡、疏水箱振动大、疏水母管无法隔离、气相阀门腐蚀内漏、水解器排污时间定值不合理等一系列问题。经过L公司技术人员的努力,现已对部分问题进行了优化,经过运行,检验效果良好。     

Moving beyond ‘more crop per drop’: insights from two decades of research on agricultural water productivity

ABSTRACT

Concern over increasing water scarcity has led to the introduction of the concept of agricultural water productivity and an emphasis on interventions to achieve ‘more crop per drop’. Yet, a strong debate continues on how the concept is to be defined and used. Drawing largely from the irrigation literature, the origins of the concept and its methodological developments are reviewed, and its use in applied work over two decades is discussed. Based on this analysis of conceptual and applied research, key insights into the concept’s contributions and limitations are presented, as well as opportunities for further refinements.     

Effect of hydrophilic pipe structure of proton exchange membrane fuel cell on water removal from the gas diffusion layer surface

In a proton exchange membrane fuel cell (PEMFC), effective GDL surface water elimination is significant to water management. This paper used the volume-of-fluid method (VOF) method to carry out simulation research on transferring liquid water in the flow channel with a hydrophilic pipe. The findings indicated that compared with a straight channel, a hydrophilic pipe structure could effectively remove water from the gas diffusion surface (GDL) and reduce the surface water coverage of the GDL. With the increase in the diameter and height of the pipe structure, the GDL surface's water coverage first increased and then decreased, and it was less with the pipe structure than with the direct flow channel. The removal rate of water on the GDL surface was accelerated. The spacing of hydrophilic pipes has a significant impact on the transportation of water. As the spacing increases, the removal rate of water on the GDL surface slowed. A hydrophilic pipe structure with a diameter of 75 μm, a height of 400 μm, and spacing of 300 μm has good water removal performance on the GDL surface. This research work proposes a new internal structure design of the flow channel, which has specific implications for removing water on the GDL surface.