基于云GIS与大数据的区划地名云服务平台设计

随着云GIS和大数据的深入应用,为用户提供区划地名云服务成为当前研究的热点。本文提出了区划地名云服务平台,采用基于遥感的地名数据更新、地名地址数据清洗与融合、地名数据挖掘等关键技术,设计了全新的区划地名云计算环境,实现了区划地名信息资源随时获取,为区划地名信息服务提供了创新的技术模式。     

基于WCF与GIS的便携式网络视频服务发布与集成研究

目前便携式网络视频应用越来越广泛,这些便携式设备一般带有GPS定位功能,现有的网络视频系统SDK难以与GIS系统实现集成,需在此基础上采用WCF的方法实现网络视频服务的发布与集成。     

青藏高原东北缘岩石圈厚度与上地幔各向异性

利用青海地震台网和甘肃地震台网2007-2009年记录的远震波形资料,提取S波接收函数和SKS分裂参数,得到了青藏高原东北缘的三维岩石圈厚度分布和上地幔各向异性特征.S波接收函数结果表明:昆仑-阿尼玛卿缝合带以南的松潘-甘孜地块东北缘和西秦岭造山带下方岩石圈较薄,厚度为125~135 km;昆仑-阿尼玛卿缝合带以北具有较厚的岩石圈,在昆仑和祁连地块下方岩石圈厚达145~175 km,并向柴达木盆地(175~190 km)和克拉通(鄂尔多斯南部约为170 km、阿拉善南缘约为200 km)下方增厚.上地幔各向异性结果显示:东北缘地区的SKS快波偏振方向为NW-SE向,与前人得到的昆仑断裂带南侧的快波方向存在较大差异,南侧自高原内部呈顺时针旋转,表明昆仑断裂带可能为上地幔变形的转换带.SKS快、慢波延迟时间为0.8~1.9 s,且在昆仑-阿尼玛卿缝合带以北,延迟时间与岩石圈厚度呈正相关关系,推断该区各向异性主要来源于地幔盖层的初期伸展变形.     

松潘-甘孜地块东部、川滇地块北部与四川盆地西部的地壳剪切波分裂

松潘-甘孜地块东部、川滇地块及四川盆地西部属青藏高原东部,是中国大陆内部强烈地震发生的主要地区之一.本研究利用四川区域数字地震台网2000年1月至2010年4月的地震波形资料,使用剪切波分裂系统分析方法(SAM),获得了研究区内44个台站的快剪切波偏振方向和慢剪切波的时间延迟.剪切波分裂参数的空间分布特征显示,由于受到区域主压应力场以及局部地质结构的影响,快剪切波的偏振方向表现出复杂的特征.龙门山断裂带北东段和西南段的快剪切波偏振方向分别显示北东和北西的优势方向,川滇菱形地块西北部和东南部的快剪切波偏振方向分别显示近东西和北北西的优势方向.青川断裂北侧和南侧地震的快剪切波偏振方向分别为近南北向和近东西向,北侧地震的慢剪切波的时间延迟大于该断裂南侧地震的慢剪切波时间延迟.研究表明,复杂的地质结构以及活动断裂的几何形态会造成剪切波分裂参数的区域化的分布特征.     

太阳活动对中山站F2层峰值电子浓度的影响

利用中山站1995-2006年的电离层垂测数据统计分析了当地电离层F2层峰值电子浓度（N_mF2）对太阳活动变化的依赖性,研究发现在中山站N_mF2月中值随修正太阳10.7厘米通量指数F10.7P增大而增大,其饱和或放大趋势不明显。除冬季12-16 UT、20-2 UT与夏季2-11 UT以外的绝大部分时刻,两者具有良好的线性关系。N_mF2月中值随F10.7P变化斜率随季节、地方时而变化。在日变化中,N_mF2随F10.7P变化斜率极大值出现在磁中午附近,明显大于其他时刻,在夜侧变化斜率整体较小,且在分季和冬季的夜侧以及夏季全天,其斜率随地方时变化不大。在年变化中,日侧斜率最大值出现在两分季,冬季次之,夏季最小;而夜侧斜率在夏半年（10月-3月）整体上要大于冬半年（4月-9月）。结合中山站位于极隙区纬度的特殊地理位置,分析了上述N_mF2变化特征的可能原因。     

Improvement of artificial neural networks to predict daily streamflow in a semi-arid area

ABSTRACT

The application of artificial neural networks (ANNs) has been widely used recently in streamflow forecasting because of their ?exible mathematical structure. However, several researchers have indicated that using ANNs in streamflow forecasting often produces a timing lag between observed and simulated time series. In addition, ANNs under- or overestimate a number of peak flows. In this paper, we proposed three data-processing techniques to improve ANN prediction and deal with its weaknesses. The Wilson-Hilferty transformation (WH) and two methods of baseflow separation (one parameter digital filter, OPDF, and recursive digital filter, RDF) were coupled with ANNs to build three hybrid models: ANN-WH, ANN-OPDF and ANN-RDF. The network behaviour was quantitatively evaluated by examining the differences between model output and observed variables. The results show that even following the guidelines of the Wilson-Hilferty transformation, which significantly reduces the effect of local variations, it was found that the ANN-WH model has shown no significant improvement of peak flow estimation or of timing error. However, combining baseflow with streamflow and rainfall provides important information to ANN models concerning the flow process operating in the aquifer and the watershed systems. The model produced excellent performance in terms of various statistical indices where timing error was totally eradicated and peak flow estimation significantly improved.

Editor D. Koutsoyiannis; Associate editor Y. Gyasi-Agyei     

场地条件对地表地震动特征的影响

以安徽省滁州市地震小区划场地为研究对象,基于ABAQUS显式有限元并行计算平台,采用大尺度二维精细化有限元非线性分析方法,研究了局部地质条件差异对场地地震效应的影响。结果表明：该场地地震动放大效应明显,河漫滩地表PGA放大效应尤为显著;相比一级阶地,河漫滩地表加速度反应谱谱形加宽,谱峰向长周期方向移动,移动幅度约为0．05～0．25S,相应的特征周期增大。地表加速度反应谱呈双峰甚至多峰特征,大尺度场地非线性有限元分析能定性反映出局部地质条件对场地地震效应特性的影响,可为城市地震小区划提供更为合理的科学依据。     

Modelling impacts of agricultural practice on flood peaks in upland catchments: An application of the distributed TOPMODEL

Upland agricultural land management activities such as grazing, vegetation burning, and bare ground restoration impact hydrological elements of headwater catchments, many of which may be important for downstream flood peaks (e.g., overland flow and soil water storage). However, there is poor understanding of how these management practices affect river flow peaks during high magnitude rainfall events. Using the distributed TOPMODEL, spatial configurations of land management were modelled to predict flood response in an upland catchment, which contains different regions operating subsidized agricultural stewardship schemes. Heavy grazing leading to soil compaction and loss of vegetation cover in stewardship regions covering 79.8% of the catchment gave a 42‐min earlier flow peak, which was 82.2% higher (under a 1‐hr 15‐mm storm) than the current simulated hydrograph. Light grazing over the same regions of the catchment had much less influence on river flow peaks (18 min earlier and 32.9% increase). Rotational burning (covering 8.8% of the catchment), most of which is located in the headwater areas, increased the peak by 3.2% in the same rainfall event. Vegetation restoration with either Eriophorum or Sphagnum (higher density) in bare areas (5.8%) of the catchment provided a reduction of flood peak (3.9% and 5.2% in the 15‐mm storm event), whereas the same total area revegetated with Sphagnum in riparian regions delivered a much larger decrease (15.0%) in river flow peaks. We show that changes of vegetation cover in highly sensitive areas (e.g., near‐stream zones) generate large impacts on flood peaks. Thus, it is possible to design spatially distributed management systems for upland catchments, which reduce flood peaks while at the same time ensuring economic viability for upland farmers.     

Glacier Peak and mid-Lateglacial Katla cryptotephras in Scotland: potential new intercontinental and marine-terrestrial correlations

Using contiguous high resolution sampling methods, we report the detection of a Glacier Peak volcanic ash from North America in Lateglacial Interstadial lake sediments in western Scotland. It occurs in close proximity to the Icelandic Borrobol and Penifiler tephras, but is distinguishable by its rhyolitic major-element composition that is consistent with the earliest set G layer, one of a number of mid-Interstadial Glacier Peak eruptions dated between 13.71 and 13.41 cal ka bp. Another cryptotephra layer present in these same Interstadial sediments has a rhyolitic composition consistent with the Icelandic Katla source. However, it is in a stratigraphic position below the widespread mid-Lateglacial Stadial Vedde Ash from Katla, which is also present in these cores. The Katla layer is stratigraphically well defined, suggesting primary airfall, and is compositionally similar to a mid-Interstadial rhyolitic tephra reported from a North Atlantic marine sequence south of Iceland dated to ~13.6 ka. The detection of Glacier Peak G in the European tephrostratigraphy will permit direct high-precision correlation of mid-Interstadial palaeoenvironments between North American and European terrestrial sequences. Any correlation between the new Katla layer and similar marine layers remains provisional, though if verified would permit similar correlation between North Atlantic marine and European terrestrial records.     

A micro‐mechanical study of peak strength and critical state

We present a micro‐mechanical analysis of macroscopic peak strength, critical state, and residual strength in two‐dimensional non‐cohesive granular media. Typical continuum constitutive quantities such as frictional strength and dilation angle are explicitly related to their corresponding grain‐scale counterparts (e.g., inter‐particle contact forces, fabric, particle displacements, and velocities), providing an across‐the‐scale basis for a better understanding and modeling of granular materials. These multi‐scale relations are derived in three steps. First, explicit relations between macroscopic stress and strain rate with the corresponding grain‐scale mechanics are established. Second, these relations are used in conjunction with the non‐associative Mohr–Coulomb criterion to explicitly connect internal friction and dilation angles to the micro‐mechanics. Third, the mentioned explicit connections are applied to investigate, understand, and derive micro‐mechanical conditions for peak strength, critical state, and residual strength. Copyright © 2015 John Wiley & Sons, Ltd.