一种无线传感器网络节点硬件结构设计

针对无线传感器网络实时监测和突发事件处理的应用需求,设计了无线传感器网络节点.节点采用超低功耗的MSP430F149单片机和具有多种工作模式的无线射频模块nRF905,采用了声音、磁性和加速度3种传感器,用于实现对环境数据的采集和目标信息的探测,同时通过蜂鸣器、麦克风以及音频信号的接收放大和解码电路实现节点间的测距.     

混凝土结构裂缝的成因及综合控制措施

分析了混凝土结构裂缝的成因，并提出了有效解决裂缝的综合措施，为防止和控制裂缝提供了实用可行的方法。     

Hydraulic conductivity of GCLs in MSW landfills

The state of the art of the study on the hydraulic conductivity of GCLs is presented in terms of the influence of the effective stress,chemical interactions,freeze-thaw cycles and temperature gradients.The changes of void ratio caused by changes of effective stress have a direct linear effect on the hydraulic conductivity,regardless of the cation concentration or the thickness of the adsorbed layer.The hydraulic conductivity is related to the relative abundance of monovalent and divalent cation（RMD）,and RMD has a great effect on the hydraulic conductivity in weak solution.The long-term susceptibility of GCLs to increased hydraulic conductivity as a response to repeated freeze-thaw cycling is minimal,which has been proved after 150 freeze-thaw cycles.The potential of desiccation cracking increases with the increasing temperature gradient and is related to the initial subsoil water content,the applied overburden stress,etc.