鄱阳湖区洪灾风险与农户脆弱性分析

This paper quantitatively explores farmers' vulnerability to flood in the Poyang Lake Region (PLR) with the supports of GIS spatial functions. The analysis consists of three major steps,which is based on the spatial unit of township. Firstly,the spatial extent and charac-teristics of flood risk areas were determined using a digital elevation model (DEM) derived from the 1:50,000 topographic map. Secondly,for each of the township,six indices indicating the economic activities of local farmers were calculated. These indices are: rural population proportion,cultivated land proportion,GDP per unit area,employment proportion of primary industry,net rural income per capita and agricultural income proportion. These six indices were then normalized and used for later vulnerability assessment. Thirdly,the normalized indices (as GIS data layers) were overlaid with the flood risk areas to produce the risk coeffi-cient for each township and to calculate the overall vulnerability for each township. The analysis results show that in the PLR there are high flood risk areas where the farmers' livings are seriously influenced or threatened. About 55.56% of the total 180 townships in the flood risk areas have a high degree of flood vulnerability. The townships under flood risk are mainly distributed in the areas around the Poyang Lake and the areas along the "five rivers".     

鄂尔多斯盆地天环坳陷北段奥陶系烃源岩特征及成熟演化史

为研究天环坳陷北段下古生界天然气成藏规律,利用探井资料和有机地球化学方法,评价了天环坳陷北段奥陶系烃源岩特征并恢复其成熟演化史。天环坳陷北段奥陶系乌拉力克组和克里摩里组烃源岩有机碳含量和生烃潜量相对较高,烃源岩有机质丰度以中等—好为主,少部分为差烃源岩;三道坎组和桌子山组烃源岩以差为主。干酪根组分鉴定表明,天环坳陷北段奥陶系烃源岩主要为Ⅱ₁～Ⅰ型干酪根,热演化程度高,处于生干气阶段。成熟演化史模拟显示,古生代—中生代早期地温梯度低,地层埋藏浅,烃源岩成熟演化程度低。燕山期,由于构造热事件,地温梯度迅速升高,早白垩世烃源岩经历的最高温度超过200℃,达到生气高峰期,早白垩世是油气成藏的主要时期。早白垩世之后,鄂尔多斯盆地整体抬升,地温梯度减小,生烃作用停止。     

OC4漂浮式风电平台的水弹性响应及波浪载荷研究

漂浮式风电平台在波浪中的摇晃运动会导致塔架根部产生很大的弯矩,极大地威胁平台结构安全。同时流体的附连水质量效应对平台塔架结构的动响应有着较为显著的影响,因此充分考虑这种流固耦合效应有利于更加准确地评估平台塔架的结构动响应。采用三维频域线性水弹性方法计算塔架在流体作用下的结构共振频率特征以及各阶模态振动的主坐标响应特性,然后通过弹性模态叠加法获得塔架的弯矩载荷。并结合概率学手段,预报了短期极限海况下塔架弯曲载荷响应,为新一代漂浮式风电平台结构安全性评估和方案设计提供了技术支撑。     

An internal-external optimized convolutional neural network for arbitrary orientated object detection from optical remote sensing images

Due to the bird's eye view of remote sensing sensors, the orientational information of an object is a key factor that has to be considered in object detection. ...     

新疆生态系统健康遥感评估及关键驱动因子研究

作为我国陆地面积最大的省级行政区,新疆维吾尔自治区具有多样的生态系统结构和丰富的动植物物种资源,是我国西北地区重要的生物多样性热点研究区域.通过以新疆维吾尔自治区为研究对象,结合区域特点和定量遥感数据实时、易获取、周期性等优势,选取归一化植被指数、动物物种丰富度、干旱度、人类扰动指数四类单因子指标,依据"活力-组织-恢...     

基于EPAS技术的日照市大气单颗粒物理化学特性及来源研究

城市地区大气气溶胶颗粒的物理化学特性复杂,理清单颗粒精细的化学成分和混合状态对于大气污染溯源和精细治理具有重要意义。本研究利用被动式气溶胶采样器分别在山东省日照市城区和钢铁园区两个区域进行了定点采样,并利用智能扫描电镜环境颗粒物分析系统（IntelliSEM EPAS）对采集的大气单颗粒物样品进行分析。结果表明,日照市大气颗粒物主要由不规则碳质颗粒（C-rich）、含硫颗粒（Ca-S、Na-S-Ca）与矿物颗粒组成。其中,城区样品中C-rich颗粒数量贡献为53.5%,是钢铁园区样品的2.5倍,大于1 μm的颗粒物数量为9.0%,是钢铁园区样品的1.7倍,城区居民活动和工业过程是城市中大气颗粒物特别是二次细颗粒的主要来源。钢铁园区样品中含硫颗粒物数量贡献为72.9%,含硫颗粒物质量贡献为30.9%,富铁颗粒物质量贡献为5.3%,分别是城区样品的1.8倍、3.6倍和2.9倍,表明钢铁园区大气颗粒物的主要来源包括钢铁企业排放的一次污染物及其转化生成的二次细颗粒物。     

陇东新近纪红粘土与第四纪黄土地球化学特征及其物源和风化指示意义

甘肃省平凉市灵台县邵寨镇剖面风尘堆积底界年龄大约为5.23 Ma B.P.,通过对该剖面新近纪红粘土与第四纪黄土-古土壤序列的常量元素、 微量元素、Nd同位素的测试,分析其在物源和风化方面的指示意义,发现新近纪红粘土与第四纪黄土具有相似的常量、 微量元素UCC标准化曲线和稀土元素球粒陨石标准化曲线,指示二者皆来自广阔的...     

Quasi-waveform seismic tomography of crustal structures in the capital circle region of China

Seismic tomography is one of the main tools to explore the interior of the earth.In this study,the quasi-waveform seismic tomographic method is used for the first time to reveal the crustal structures in the capital region of China.3-D highresolution V_P,V_S and the Poisson’s ratio models are generated by inverting 29839 direct P-and 29972 direct S-wave traveltimes selected from 3231 local earthquakes.The results reveal strong crustal heterogeneities.The velocity anomalies at shallow depths are well consistent with surface geologic structures.The relatively low-velocity anomaly layer in the middle crust may be the result of multiple phases of tectonic activity.Earthquakes generally occurred on the boundaries of high-and low-velocity and Poisson’s ratio anomalies.There are obvious low-velocity anomalies below the hypocenters of the Tangshan earthquake and the historical Sanhe-Pinggu earthquake,implying the existence of fluids.The similar velocity structures around the hypocenters of the two earthquakes indicate that the occurrences of the two earthquakes may be related to the same mechanism.The highresolution velocity models provide important observational constraints on the small-scale heterogeneities and dynamic mechanism of the crust in the capital region of China.     

Modeling 3D thermal fracture propagation by transient cooling using virtual multidimensional internal bonds

Thermal fracturing can play an important role in development of unconventional petroleum and geothermal resources. Thermal fractures can result from the nonlinear deformation of the rock in response to thermal stress related to cold water injection as well as heating. Before the rock reaches the final failure stage, material softening and bulk modulus degradation can cause changes in the thermo‐mechanical properties of the solid. In order to capture this aspect of the rock fracture, a virtual multidimensional internal bond‐based thermo‐mechanical model is derived to track elastic, softening, and the failure stages of the rock in response to the temporal changes of its temperature field. The variations in thermo‐mechanical properties of the rock are derived from a nonlinear constitutive model. To represent the thermo‐mechanical behavior of pre‐existing fractures, the element partition method is employed. Using the model, numerical simulation of 3D thermal fracture propagation in brittle rock is carried out. Results of numerical simulations provide evidence of model verification and illustrate nonlinear thermal response and fracture development in rock under uniform cooling. In addition, fracture coalescence in a cluster of fractures under thermal stress is illustrated, and the process of thermal fracturing from a wellbore is captured. Results underscore the importance of thermal stress in reservoir stimulation and show the effectiveness of the model to predict 3D thermal fracturing. Copyright © 2016 John Wiley & Sons, Ltd.     

Modeling three‐dimensional hydraulic fracture propagation using virtual multidimensional internal bonds

Propagation of fractures, especially those emanating from wellbores and closed natural fractures, often involves Mode I and Mode II, and at times Mode III, posing significant challenges to its numerical simulation. When an embedded inclined fracture is subjected to compression, the fracture edge is constrained by the surrounding materials so that its true propagation pattern cannot be simulated by 2D models. In this article, a virtual multidimensional internal bond (VMIB) model is presented to simulate three‐dimensional (3D) fracture propagation. The VMIB model bridges the processes of macro fracture and micro bond rupture. The macro 3D constitutive relation in VMIB is derived from the 1D bond in the micro scale and is implemented in a 3D finite element method. To represent the contact and friction between fracture surfaces, a 3D element partition method is employed. The model is applied to simulate fracture propagation and coalescence in typical laboratory experiments and is used to analyze the propagation of an embedded fracture. Simulation results for single and multiple fractures illustrate 3D features of the tensile and compressive fracture propagation, especially the propagation of a Mode III fracture. The results match well with the experimental observation, suggesting that the presented method can capture the main features of 3D fracture propagation and coalescence. Moreover, by developing an algorithm for applying pressure on the fracture surfaces, propagation of a natural fracture is also simulated. The result illustrates an interesting and important phenomenon of Mode III fracture propagation, namely the fracture front segmentation. Copyright © 2012 John Wiley & Sons, Ltd.