保护东滩湿地爱护绿色家园

湿地是地球上具有高度多样性的独特生态系,它与海洋、森林并列为世界三大生态系。它具有季节或常年积水、生长和栖息喜湿植物、动物和土壤发生熟化3个基本特征。根据1971年2月在伊朗拉姆萨尔签署的《湿地     

水下浅埋软岩隧道施作拱墙二衬力学效应的现场实测与分析

以一座用矿山法施工的水下浅埋软岩公路隧道为工程背景,基于现场实测数据,分析了施作拱墙二衬对初期支护受力性状的影响以及拱墙二衬本身的受力特性.研究结果表明:与浇注拱墙二衬混凝土的前一天相比,浇注完拱墙二衬混凝土后第20d,初期支护的局部锚杆轴力和局部型钢拱架应力明显减小,说明施作拱墙二衬能分担初期支护承受的部分围岩荷载;...     

Laboratory evaluation of a new device for water drainage in roadside slope along railway systems

The majority of the existing railway systems in China, from roadside slopes to retaining walls, suffered from poor drainage induced failures. Recently, a new drainage device was proposed to tackle these problems. Preliminary field implementations indicated that the new drainage device could effectively remove groundwater from the surrounding soil without any clogging effect. However, at present, most existing designs are purely based upon the engineers' personal experience and judgement; there is no well-established design method to take full advantage of the device.In this study, a series of laboratory modeling tests were conducted to investigate flow rates, and the optimum installation angle of the drainage device. After that, the long-term performance of the drainage device and conventional perforated PVC pipe under multiple wetting-drying cycles was also evaluated and compared. The results indicate that during the constant head tests, the flow rates in the new drainage device initially increased with an increase in the installation angles of the drainage device from 0° to 15°, and then decreased from 15° to 60°. An inclination angle from 5° to 15° is recommended for this new drainage device when installed in the exiting railway cut slope. The clogging effect was not a primary concern for the applications of this new device. The proposed drainage device provides an alternative way to tackle the poor drainage problem in the exiting railway cut slopes and retaining walls.     

PVC塑料抗静电地砖的施工应用

PVC塑料抗静电地砖主要由PVC、填充剂、增塑剂、颜料、稳定剂等组成，利用粒子界面间形成的导静电网络，连接地面金属网络，接地后形成整体防静电环境，具有永久性防静电功能。防静电效果达到防静电国标A级标准，且表面酷似天然石材花纹，装饰效果较好，还具有质量轻、耐磨、耐酸、耐碱、抗老化、阻燃等特点。     

级联型多电平逆变器的空间矢量控制

针对级联型多电平逆变器,提出了一种高性能的空间矢量控制方法。这种方法基于空间矢量理论确定与参考电压矢量误差最小的电压矢量,它能够在接近基频的开关频率下输出接近正弦波的电压。仿真结果证实了空间矢量控制所具有的一系列显著优点。