Mobility increases the surface coverage of distributed sensor networks

Coverage is a fundamental issue in sensor networks, which usually dictates the overall network performance. Previous studies on coverage issues mainly focused on sensor networks deployed on a 2D plane or in 3D space. However, in many real world applications, the target fields can be complex 3D surfaces where the existing coverage analysis methodology cannot be applied. This paper investigates the coverage of mobile sensor networks deployed over convex 3D surfaces. This setting is highly challenging because this dynamic type of coverage depends on not only sensors’ movement but also the characteristics of the target field. Specifically, we have made three major contributions. First, we generalize the previous analysis of coverage in the 2D plane case. Second, we derive the coverage characterization for the sphere case. Finally, we consider the general convex 3D surface case and derive the coverage ratio as a function of sensor mobility, sensor density and surface features. Our work timely fills the blank of coverage characterization for sensor networks and provides insights into the essence of the coverage hole problem. Numerical simulation and real-world evaluation verify our theoretical results. The results can serve as basic guidelines for mobile sensor network deployment in applications concerning complex sensing fields.     

基于PPP模式的电动汽车充电服务定价模型

运用公共定价理论、Stackelberg博弈理论和情景分析法,基于PPP融资模式,结合电动汽车充电服务特性,构造了考虑政府、用户和服务商三者利益主体的电动汽车充电服务定价模型。文章在电动汽车发展不同阶段应用该模型进行分析,研究结果表明在PPP模式下,政府对于电动汽车充电服务市场定价权的规制,有利于协调平衡各参与方的利益;政府依据平均成本和外部环境价值的规制限价,有利于社会福利最大化。     

井震联合网格层析各向异性速度建模研究及应用

各向异性速度场及参数场的建立是各向异性叠前深度偏移技术在地震资料处理过程中取得成功的关键环节。井震联合求取各向异性参数是目前地震资料处理时常用的方法之一,但常规井震联合法通过对比地层厚度来求取各向异性参数,计算精度较低,达不到地质要求。将网格层析技术应用于三维VTI介质井震联合各向异性速度建模中,沿射线路径同时更新每个网格点的各向异性速度和参数,并通过多次迭代进一步提高速度模型的精度。应用结果表明,相较于常规井震联合法,基于网格层析的井震联合法能大幅提高各向异性速度场和参数场的计算精度,增强深度偏移结果与测井资料的吻合度,并且使得共成像点道集的远偏移距更加平直,为叠前反演提供更丰富的远偏移距信息,同时还能有效改善局部成像效果。     

脆弱性指数法在沙曲矿上组煤突水性预测评价中的应用

通过对沙曲矿影响上组煤底板太灰突水脆弱性的主控因素、上组煤底板太灰突水脆弱性评价专题图的建立、太灰突水脆弱性评价模型的建立、煤层底板突水脆弱性评价分区及模型的识别与检验(利用脆弱性指数法)对现开采的3 #+4#煤层底板太原组灰岩的突水性作出综合研究评价,为矿井防治水工作提供科学指导.