Demonstration and application of NMM‐based fractured porous medium flow model

In natural rock masses, the shapes of three‐dimensional (3‐D) blocks cut by arbitrary fracture networks may be very complex. Owing to the geometric complexity and difficulty of mesh discretization of 3‐D blocks and fracture facets, explicit consideration of fracture networks in flow analysis of fractured porous medium (FPM) is very challenging. Using the numerical manifold method based on independent covers (NMMIC), an FPM flow model was proposed that can deal with very complex 3‐D fracture networks. In this paper, the convergence of NMMIC was first demonstrated. The theoretical basis of the arbitrary refinement of computational meshes was proven. Moreover, three peculiarities of NMMIC meshes, that is, arbitrary shape, arbitrary connection, and arbitrary refinement of independent covers, were concluded. Finally, some two‐dimensional (2‐D) tunnel flow examples were analyzed and the numerical results were compared with the analytical results. 3‐D examples with complex fracture distributions were also analyzed. In addition, the computational scale of the developed program was tested by increasing the number of computational elements. The results show that our model can accurately analyze the groundwater flow of rocks surrounding tunnels with complex fracture distributions.     

2018年松原5.7级地震前地磁垂直分量日变化低点时间时空演化特征

本文对松原5.7级地震前地磁垂直分量日变化低点时间时空演化特征进行研究，结果显示：1）以去除经度效应后低点时间为0 h的等值线作为低点位移分界线，松原5.7级地震的震中分别位于2018-04-13分界线上和2018-04-24分界线附近；2）异常日期间，中国大陆地磁垂直分量日变形态存在分区特征，去除经度效应后低点时间为正、负的区域内日变形态分别以“W”型和“V”型为主；3）在2018-04-13和2018-04-24这2个异常日期间，中国大陆都存在去除经度效应后的低点时间高梯度带，松原5.7级地震的震中分别位于2018-04-13高梯度区边缘和2018-04-24高梯度区东侧。     

珠江口海洋软土不排水抗剪强度及循环弱化特性试验研究

为了获得广东珠江口海洋软土的不排水抗剪强度,分别开展了不固结不排水剪切和固结不排水剪切三轴试验、无侧限抗压试验、现场取土离心机正常固结模型地基的T-bar静力贯入试验以及现场十字板剪切试验和静力触探试验（CPT）,并采用土力学经验公式进行计算,确定了珠江口海洋软土不排水抗剪强度沿深度的分布规律,并综合评价了各种方法的有效性。为了获得该区域软土的循环弱化规律,分别开展了循环动三轴试验、现场取土离心机正常固结模型地基的T-bar循环贯入试验和现场单桩水平循环加载试验,揭示了软土循环动模量比与循环次数之间的双对数线性关系,获得了3种试验条件下珠江口海洋软土的循环弱化因子。其研究结果可为该区域海洋建筑物设计提供直接依据,也可为其他类型工程提供借鉴。     

页岩气藏缝网压裂裂缝间距优化研究

页岩气藏一般具有低孔隙、低渗透等特征,对其实施缝网压裂是高效开发页岩气的最佳途径。采用位移不连续法建立线弹性二维均质地层诱导应力场分布数学模型,通过水平应力差异系数对顺序压裂和交替压裂的裂缝间距进行优化研究。结果表明,水平应力差异系数受到裂缝净压力、裂缝缝长、原地应力场等因素的影响;裂缝净压力越大、缝长越长,水平应力差异系数越小;随着与裂缝距离的增加,水平应力差异系数呈现先减小后增加的趋势,因此,存在后续裂缝形成复杂网络的最佳裂缝间距;顺序压裂裂缝间距不宜过大,且后续压裂裂缝间距应适当减小;交替压裂裂缝间距最优时,缝间水平应力差异系数最小,对中间裂缝形成缝网最有利。     

传感网环境下传感器信息建模与注册方法研究

如何对传感器资源进行重新组合并用于发现来实现高级的信息共享是目前亟待解决的问题。本文针对目前传感器的建模现状和发现机制现状,选择传感器模型语言(Sensor ML)实现传感器信息的建模。针对Sensor ML用于发现机制的Profile规则,提出了面向处理的传感器抽象模板建模方法。并且使用传感器实例注册(Sensor Instance Registry,SIR)客户端传感器信息模型。基于本文提出的方法,采用自主设计开发的传感器建模软件SensorModel完成了对传感器的快速实例化建模,应用SIR客户端完成了对所建传感器信息模型有效的注册和发现。     

Indices of El Nio and El Nio Modoki:An Improved El Nio Modoki Index

In recent years, El Nio Modoki (a type of pseudo-El Nio) has been distinguished as a unique large-scale ocean warming phenomenon happening in the central tropical Pacific that is quite different from the traditional El Nio. In this study, EOF analysis was used to successfully separate El Nio and El Nio Modoki. The abilities of the NINO3 index, NINO3.4 index, NINO1+2 index and NINO4 index in characterizing El Nio were explored in detail. The resulting suggestion was that, comparatively, NINO3 is the op...     

碾压施工质量监控的径向神经网络拟合高程研究

针对面板堆石坝摊铺层表面及测量机器人采集摊铺层离散数据密且精度高等特征,利用径向神经网络方法,采用复二次函数作为径向基,根据数理统计理论和逐步趋近法自适应优选平滑因子拟合摊铺层高程,以达到与实际高程的最佳吻合。以某面板堆石坝的测量机器人采集的数据为例,对该方法进行了验证。结果表明,其拟合精度明显优于常规拟合方法,更加适合面板堆石坝摊铺层表面的高程拟合。     

Discontinuous Data 3D/4D Variation Fusion Based on the Constraint of L1 Norm Regularization Term

Classical 3D/4D variation fusion is based on the theory that error follows Gaussian distribution. When using minimization iteration, the gradient of objective function is involved, and the solution of which requires the continuity of data. This paper adopted the extended classical 3D/4D variation fusion method, and explicitly applied the prior knowledge, which was based on L1-norm, as regularization constraint to the classical variation fusion method. Original data was firstly projected into the wavelet domain during the implementation process, and new fusion model was adopted for data fusion in wavelet space, then inverse wavelet transform was used to project the result to the observation space. Ideal experiment was carried out by using linear advection-diffusion equation as four-dimensional prediction model, which made a hypothesis of the discontinuity with the data between background and observation, and that meant the derivatives between left and right were not equal on some points. The result of the experiment showed that the method adopted here was practicable. A further research was also done for multi-source precipitation fusion. Firstly, CMORPH inversion precipitation data were corrected through PDF (Probability Density Function, PDF) matching method based on GAMMA fitting function. Then corrected data was fused with the observation one. By comparison with the reference field, the result showed that this method can keep some outliers better, which might represent certain weather phenomenon. The L1-norm regularization variation fusion in this paper provided a possible way to deal with discrete data, especially for jump point.     

岩溶动力系统中的生物作用机理初探

岩溶动力系统是地球表层系统的重要组成部分。生物是地球表层系统中最活跃的地质营力之一 ,它在岩溶动力系统中扮演着重要的角色。地质历史时期 ,生物圈大气圈界面上 ,生物通过植物的光合同化、动植物分泌 ,使大气圈中的CO2 不断转移到碳酸盐岩中 ,形成岩溶发育的物质基础 ,并成为全球最大的碳库 ;生物圈水圈界面上 ,生物形成的生物 (微 )环境改变了水循环的强度和方向 ,并影响岩溶发育 ;生物圈岩石圈界面上 ,生物通过生物物理、生物化学过程 ,殖居碳酸盐岩之上 ,并以之为生存依托 ,生物的新陈代谢过程使碳酸盐岩岩石圈活化 ,使其积极参与全球碳循环。     

黄河源区降水与径流过程对ENSO事件的响应特征

根据最新季分辨率ENSO指数序列所确认的近40年多来所发生的20次ENSO事件，并确定了每次ENSO事件强度及其影响年，通过对相应年份黄河源区降水与径流距平变化值的对比，分析了降水与径流过程对ENSO事件响应的统计规律；ENSO事件与黄河源区降水与径流年际波动变化有很好的相关性，这种相关性与ENSO事件的性质强弱，发生季节以及持续时间等有关。一般夏秋季暖事件无论强弱均使影响年降水减少，发生于春季的中等强度暖事件使发生年降水呈负距平，影响年降水呈增加趋势，冷事件与暖事件对降水的影响正好相反；暖事件对应年份黄河源区径流量减少，而冷事件则使其增加，随着20世纪90年代以来暖事件发生频率的增加，径流呈现持续减少。