摘要：In order to effectively assess the mechanical properties of concrete with freeze-thaw and seawater erosion, tests about basic mechanical properties of concrete after freeze-thaw and seawater erosion are conducted based on the large-scale static and dynamic stiffness servo test set. 50, 100, 200 and 300 cycles of freeze-thaw cycling are made on normal concrete, and the artificial seawater is produced. The reasonable wet and dry accelerate system is selected. 10, 20, 30, 40, 50 and 60 cycles of wet and dry cycling are made to concrete after freeze-thaw cycling. The degeneration law of the concrete elastic modulus and compressive strength is studied. The Ottosen tri-axial strength criterion considering cycles of freeze-thaw and wet and dry cycling is deduced based on uniaxial mechanical properties of concrete and damage theory. Experimental results show that with the increase in the number of wet and dry cycles and freeze-thaw cycles, the concrete axial compressive strength and the elastic modulus decline gradually. Tensile and compressive meridians of concrete shrink gradually. The research can be referenced for anti-crack design of actual structures eroded by seawater at cold regions.

摘要：针对山区、丘岭区有地形高差水源可资利用，在发展温室大棚经济作物时，灌溉可优先选用迷宫式滴灌带，采用自压滴灌灌水技术，该技术具有安装简易、造价低，不需能源、高效节水等优点，是一项易于为群众接受，较为理想的滴灌形式。对该滴灌技术的设计方法及步骤作了总结，可以在同类地区推广应用。

摘要：为配合非法伪基站专项治理工作,检测中心基于便携式频谱监测平台,设计一款用于伪基站侦测查找的移动通信空中接口监测仪,首先介绍伪基站的工作原理,然后重点说明移动通信空中接口监测仪的设计原理与性能指标,并对伪基站查找过程中遇到的问题进行归纳总结。

摘要：实际工程施工中,竖向预应力钢筋及锚垫板的定位都存在误差,导致锚垫板顶面和锚固螺母底面之间产生初始夹角θ,该夹角使竖向预应力钢筋在锚固时回缩量增加,竖向预应力损失增大,本研究通过现场测试分析夹角θ对竖向预应力损失的影响。在某预应力连续刚构桥施工过程中,利用SDC620三维电子寻北仪对该初始夹角θ进行测试,收集400个样本,采用皮尔逊Ⅲ曲线假设、矩估计法及皮尔逊2χ拟合检验法对样本分布规律进行分析,结果表明:初始夹角θ服从皮尔逊Ⅲ曲线分布。利用JMZX-3108AT型锚索计对竖向预应力瞬时锚固损失进行测试,结果分析表明:瞬时锚固损失F与钢筋长度l呈反比,与夹角θ呈线性关系,夹角θ对竖向预应力损失影响很大。本研究中初始夹角θ的测试方法和瞬时锚固损失的计算公式为首次提出,以期对竖向预应力设计及施工有所帮助。

摘要：本文介绍了地铁数字集群系统频率使用率评价的测试方法、采集设备要求和路测方案设计,并针对测试工作量大的问题提出了一种既能保证数据量又能提高测试效率的路测方案。