An ICPSO-RBFNN nonlinear inversion for electrical resistivity imaging

To improve the global search ability and imaging quality of electrical resistivity imaging(ERI) inversion, a two-stage learning ICPSO algorithm of radial basis function neural network(RBFNN) based on information criterion(IC) and particle swarm optimization(PSO) is presented. In the proposed method, IC is applied to obtain the hidden layer structure by calculating the optimal IC value automatically and PSO algorithm is used to optimize the centers and widths of the radial basis functions in the hidden layer. Meanwhile, impacts of different information criteria to the inversion results are compared, and an implementation of the proposed ICPSO algorithm is given. The optimized neural network has one hidden layer with 261 nodes selected by AKAIKE's information criterion(AIC) and it is trained on 32 data sets and tested on another 8 synthetic data sets. Two complex synthetic examples are used to verify the feasibility and effectiveness of the proposed method with two learning stages. The results show that the proposed method has better performance and higher imaging quality than three-layer and four-layer back propagation neural networks(BPNNs) and traditional least square(LS) inversion.     

静电对煤矿安全的危害及其预防

介绍了静电的产生及其对煤矿安全的危害,提出了煤矿产品的防静电措施,包括产品在设计阶段的静电放电设计方法和外壳材质的抗静电设计、检验阶段的抗静电检测方法、应用阶段的防静电措施。这些措施对预防由静电引起的煤矿安全事故有一定的指导意义。     

煤矿安全监控设备的电磁兼容性分析与设计

文章分析了煤矿安全监控设备的电磁兼容性(EMC),针对不同类型的电磁干扰,提出了适合煤矿井下安全监控设备的电磁兼容的设计方法。该方法提高了矿用设备的抗电磁干扰能力,为矿井安全生产提供了保障。     

一种新型矿用本质安全型电源的设计

针对目前煤矿井下多输入电压等级本质安全型电源的笨重和单输入电压等级本质安全型电源的局限性问题,提出了一种新型本质安全型电源的设计方案。该新型本质安全型电源采用R型隔离变压器,体积小;采用高性能的DC/DC开关转换电源,提高了本质安全型电源的转换效率,且减小了输出纹波噪声;同时采用由过流检测芯片、单稳态触发芯片、大功率三极管等组成的双重化过流和过压保护电路,提高了本质安全型电源的可靠性。     

矿用本质安全电源的基本要求和设计方法

结合新版国家标准GB3836.4—2010和安标国家矿用产品安全标志中心的相关要求,分析了矿用本质安全电源的技术性能,即电气隔离方法和限能电路的保护方式;根据矿用本质安全电源的技术指标,介绍了矿用本质安全电源的主要放电形式和设计要点,指出在设计本质安全电源时,需考虑最大输出电压、最大输出电流、最大外部电容、最大外部电感四个本质安全输出参数之间的关系,为了达到最大输出功率,可以尽量选择较低的最大输出电压。该文对矿用本质安全电源的设计有一定的参考价值。     

砂土地层盾构法施工的模型试验设计研究

为更好地指导盾构隧道的设计与施工。很有必要开展土体-盾构系统的适应性试验研究。以直径6．34m的土压平衡盾构和上海地区粉砂地层为参照原型,将相似理论和模型试验的方法成功地应用于盾构掘进的模型试验设计。使之能够实现对盾构机工作参数和地层特性参数进行不同组合的试验,进而探求盾构机与土体相互作用的机理,并可由模型试验的结果来预测原型的性能。从而为最终形成盾构及地层适应性理论服务。     

水工混凝土质量无损检测技术研究进展

大型水利枢纽工程混凝土质量无损检测工作具有体积大、结构复杂、强度成长期长的特点,为适应工程质量检测的需要,展开了从检测硬件到软件,从工作方法到处理方法,从模型试验到现场试验,从理论到实践,又从实践到理论的多方面、全方位的系统反复研究,并十分注重新技术研究成果在工程实践中见到成效,使新技术开发研究与工程检测需求紧密结合,取得了一批既有方法技术理论创新,又能满足工程实用要求的丰硕成果,使原本在世界范围内主要用于常见的小尺度、简单结构混凝土的无损检测技术,通过改进、升级、完善、创新和发展,全方位地(而不是某一局部、某一方面)、系统地(而不是零星的)推向了特大型水工混凝土的检测。     

基于二维高密度电阻率数据的二、三维反演对比(英文)

目前高密度电阻率法所采用的数据处理方法主要是将地质结构体视为二度体进行二维处理,因而二维数据资料处理结果只是一种近似解释,其计算精度与反演效果达不到精确反演的要求。设计两种典型的电阻率异常地质体模型,利用有限单元法进行正演计算。为更真实地模拟实测数据并分析二维、三维反演算法对噪声的敏感度,在正演剖面中加入1%的高斯随机误差,然后再分别利用最小二乘法进行高密度电阻率法二维、三维反演。对比二维和三维高密度电阻率法的反演水平切片及垂直切片图可知,三维反演受高斯随机误差的影响更小,反演结果在模型异常位置、形态和电阻率特性反映上都比二维反演的效果更好,与实际地质模型更接近。     

GPR numerical simulation of full wave field based on UPML boundary condition of ADI-FDTD

Alternating direction implicit difference scheme (ADI-FDTD) divides a traditional time step into two time steps, with forward difference and backward difference, and integrates both the advantages of unconditional stability of implicit difference scheme and relatively simple calculation of explicit difference scheme, it breaks through the constraint of Courand–Friedrichs–Levy (CFL), and is characterized by unconditional stability. And the boundary condition of uniaxial anisotropic perfectly matched layer (UPML) is anisotropic medium PML applied in absorption edge of FDTD area, with the absorption of wide band, simple iterative formula, and easy programming, without the electric and magnetic field splitting. By discretizing the Maxwell equations in a two dimensional structure, numerical formulas of ADI-FDTD with UPML boundary condition for GPR wave are presented in detail. GPR simulations are carried out for two models. Based on the analysis of numerical results, insights of the radar wave spreading and changing in space are obtained, which can provide a better interpretation of real radar data. The results show that the ADI-FDTD algorithm based on the UPML boundary condition can deploy larger time step and eliminate the strong reflection on the truncated boundaries, lead to an efficient GPR modeling.     

环保型常温锌钙系磷化工艺

研究了(NH4)2MoO4、Ca(NO3)2、硫脲、柠檬酸、温度,时间和pH等工艺条件对磷化膜层的耐蚀性和表面状况的影响.通过正交试验法确定的最佳工艺配方为:氧化锌4.5 g/L,磷酸11.25 mL/L,硝酸钙8 g/L,钼酸铵4.0 g/L,硫脲1.5 g/L,柠檬酸1.4 g/L,温度25～35℃,时间20 min以上,pH 2.5～3.0.该磷化工艺操作简单,清洁环保,常温即可磷化,使用周期较长,易维护.