对地磁低点位移异常机理的一些新的认识

"地磁低点位移异常"现象指的是一个大区域的地磁垂直分量日变化极小值出现时间(简称低点时间),明显地与另一个大区域的低点时间不同,而每个大区域内部低点时间又基本一致,两个区域之间有明显的突变分界线(简称低点位移线),并且两个区域之间的低点时间相差在两小时以上.根据80次5.8级以上地震统计表明.85%以上地震发震时间在异常日后的第27天或41天的前后4天;在仅考虑预报占用时间时,该法对6.6以上地震的R值达0.60.     

A multiresolution method for climate system modeling: application of spherical centroidal Voronoi tessellations

During the next decade and beyond, climate system models will be challenged to resolve scales and processes that are far beyond their current scope. Each climate system component has its prototypical example of an unresolved process that may strongly influence the global climate system, ranging from eddy activity within ocean models, to ice streams within ice sheet models, to surface hydrological processes within land system models, to cloud processes within atmosphere models. These new demands will almost certainly result in the develop of multiresolution schemes that are able, at least regionally, to faithfully simulate these fine-scale processes. Spherical centroidal Voronoi tessellations (SCVTs) offer one potential path toward the development of a robust, multiresolution climate system model components. SCVTs allow for the generation of high-quality Voronoi diagrams and Delaunay triangulations through the use of an intuitive, user-defined density function. In each of the examples provided, this method results in high-quality meshes where the quality measures are guaranteed to improve as the number of nodes is increased. Real-world examples are developed for the Greenland ice sheet and the North Atlantic ocean. Idealized examples are developed for ocean–ice shelf interaction and for regional atmospheric modeling. In addition to defining, developing, and exhibiting SCVTs, we pair this mesh generation technique with a previously developed finite-volume method. Our numerical example is based on the nonlinear, shallow-water equations spanning the entire surface of the sphere. This example is used to elucidate both the po tential benefits of this multiresolution method and the challenges ahead.     

How well can we simulate complex hydro‐geomorphic process chains? The 2012 multi‐lake outburst flood in the Santa Cruz Valley (Cordillera Blanca,Perú)

Changing high‐mountain environments are characterized by destabilizing ice, rock or debris slopes connected to evolving glacial lakes. Such configurations may lead to potentially devastating sequences of mass movements (process chains or cascades). Computer simulations are supposed to assist in anticipating the possible consequences of such phenomena in order to reduce the losses. The present study explores the potential of the novel computational tool r.avaflow for simulating complex process chains. r.avaflow employs an enhanced version of the Pudasaini ( 2012 ) general two‐phase mass flow model, allowing consideration of the interactions between solid and fluid components of the flow. We back‐calculate an event that occurred in 2012 when a landslide from a moraine slope triggered a multi‐lake outburst flood in the Artizón and Santa Cruz valleys, Cordillera Blanca, Peru, involving four lakes and a substantial amount of entrained debris along the path. The documented and reconstructed flow patterns are reproduced in a largely satisfactory way in the sense of empirical adequacy. However, small variations in the uncertain parameters can fundamentally influence the behaviour of the process chain through threshold effects and positive feedbacks. Forward simulations of possible future cascading events will rely on more comprehensive case and parameter studies, but particularly on the development of appropriate strategies for decision‐making based on uncertain simulation results. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.     

GIS专业人才培养的实践教学体系构建

实践教学是GIS专业人才培养不可缺少的重要环节.文章在分析国内外GIS实践教学现状的基础上,建立了GIS专业实践教学系统,确定了实践体系、实践模式与综合能力间的关系,系统阐述了GIS实践教学体系和模式的主要内容,提出多层次知识结构GIS人才培养的实践教学体系和模式.该GIS实践教学系统在高校GIS实践教学中得以广泛推广,为GIS教育和GIS创新人才的培养发挥重要的作用.     

基于异构数据互操作的电子地图质量控制研究——以南京市政务版电子地图为例

作为服务于城市各部委办局的政务版电子地图在数据共享过程中具有重要方位意义和共享责任。多要素、大数据量的政务版电子地图编辑是一个复杂过程,在编辑中各环节都有可能存在误差,由于误差积累最终会影响地图质量。为此,南京政务版电子地图在生产与建库过程中尝试采用异构数据互操作的方法,即采用AutoCAD平台编辑,采用ArcGIS平台存储,并且基于这种异构数据互操作新模式,创新提出一套数据双平台质量检查方法。相对于传统电子地图的编辑方法,不仅解决了数据编辑与数据存储之间的矛盾,同时利用各平台软件质量检查优势,使政务版电子地图在生产与建库上实现了全面、有效的质量控制。     

遥感影像档案时空多维管理北大核心CSCD

遥感影像档案作为重要的基础地理信息资料,可为自然资源监管监测、城市可持续发展规划等提供关键决策依据。本文针对当前遥感影像档案多来源、多介质、多尺度、多规格的现状,分析了当前遥感影像管理方式所存在的主要问题,提出并构建了“空间+时间+形态+属性”的时空多维管理体系,实现了对遥感影像档案的科学高效管理利用。     

相对海平面变化时段选择效应分析

验潮站观测的海面高度数据是监测海平面变化以及确定平均海面的重要基础观测信息,利用滑动时段法和时段累积法对验潮站不同观测时段相对海平面变化速率的差异进行了分析,讨论了时段选择效应对计算相对海平面变化的影响,并利用美国东海岸验潮站观测数据对分析结果进行了补充实验.实验结果表明,不同观测时段相对海平面变化速率差异最大可达27...     

高放废物地质处置与岩石力学研究

高放废物处置库是一个特殊的深部地下工程,涉及大量的岩石力学问题。笔者简述了我国高放废物处置的技术路线和主要进展,探讨了处置库选址、设计、建造、性能评价中的主要岩石力学问题。     

On detecting stellar binary black holes via the LISA-Taiji network

The detection of gravitational waves(GWs)by ground-based laser interferometer GW observatories(LIGO/Virgo)reveals a population of stellar binary black holes(sBB...     

Possible properties of Te V spectra in PKS 2155–304

We present a one-zone homogeneous lepton-hadronic model and obtain steady-state spectra by solving the time-dependent equations to study a plausible origin of hard TeV spectra in PKS 2155-304.In this model,we assume a steady electron and proton injection rate in the source and solve the non-linear time-dependent kinematic equations that self-consistently consist of proton-photon interaction,synchrotron radiation of electron/positron pairs and proton,inverse Compton scattering,and synchrotron self-absorption.We employ this model to reproduce the multi-wavelength spectrum of PKS 2155-304,then find that the possible bump located at E~1 TeV which may originate from the synchrotron radiation of secondary electrons produced by Bethe-Heitler pair production,resulting in the hard TeV spectrum.