基于TVDI的藏北地区土壤湿度空间格局

利用2010年DOY 209期的Terra/MODIS 16 d合成的植被指数(EVI)产品数据MOD13A2和8d天合成的地表温度(LST)产品数据MOD11 A2,构建LST-EVI特征空间,从而得到了条件温度植被干旱指数TVDI反映的藏北土壤湿度空间分布图.结合野外同步土壤表层水含量测试数据,二者表现出较好的相关...     

中国沿海地区产业结构水平的横向对比与纵向测度模型及应用——基于福建省的视角

优化、高效的区域产业结构是区域社会经济发展的必备条件.本研究基于传统偏离-份额分析法(SSM)以及动态偏离-份额分析法对区域产业结构进行横向对比与纵向测度,从福建省的视角进行实证分析,旨在为区域产业结构优化升级、经济发展方式转变提供科学指导.研究表明:1)中国沿海地区的产业结构份额和产业竞争份额大部分大于全国平均水平,说明沿海地区相对于其他地区具有产业结构的优势;2)福建的经济增长主要是依靠全国经济增长的作用,而不是靠产业结构和产业竞争力的优势;3)相对于其他沿海地区,福建省的发展速度相对落后;4)福建省应利用区位优势,承接台湾地区的产业转移,促进福建省的产业结构优化升级.     

Scenario-based assessment of future food security

This paper presents a scenario-based assessment of global future food security. To do that, the socio-economic and climate change scenarios were defined for the future and were linked to an integrated modeling framework. The crop yields simulated by the GIS-based Environmental Policy Integrated Climate (EPIC) model and crop areas simulated by the crop choice decision model were combined to calculate the total food production and per capita food availability, which was used to represent the status of food availability and stability. The per capita Gross Domestic Product (GDP) simulated by IFPSIM model was used to reflect the situation of food accessibility and affordability. Based on these two indicators, the future food security status was assessed at a global scale over a period of approximately 20 years, starting from the year 2000. The results show that certain regions such as South Asia and most African countries will likely remain hotspots of food insecurity in the future as both the per capita food availability and the capacity of being able to import food will decrease between 2000 and 2020. Low food production associated with poverty is the determining factor to starvation in these regions, and more efforts are needed to combat hunger in terms of future actions. Other regions such as China, most Eastern European countries and most South American countries where there is an increase in per capita food availability or an increase in the capacity to import food between 2000 and 2020 might be able to improve their food security situation.     

Petrogenesis and Tectonic Implications of the Early Triassic Nianzi Adakitic Granite Unit in the Yanshan Fold and Thrust Belt: New Constraints from U-Pb Geochronology and Sr-Nd-Hf Isotopes

The Nianzi granite unit, which includes the Nianzi, Xiaolianghou and Xiawopu granitic intrusions, is a significant component of the northern part of the North China Craton (NCC) and is situated in the Yanshan fold and thrust belt (YFTB). However, there is still debate regarding the tectonic evolutionary history of the YFTB during the late Permian to Triassic period, specifically regarding the timing of subduction and collision between the NCC and the Paleo-Asian Ocean. The Nianzi granite unit exhibits unique petrological, geochronological and geochemical signatures that shed light on the tectonic evolutionary history of the YFTB. This study presents detailed petrology, whole-rock geochemistry, together with Sr-Nd isotopic, zircon U-Pb dating and Lu-Hf isotopic data of the granites within the Nianzi granite unit. Our findings demonstrate that the granites primarily consist of subhedral K-feldspar, plagioclase, quartz, minor biotite and hornblende, with accessory titanite, apatite, magnetite and zircon. Zircon U-Pb dating indicates that the Xiaolianghou granite was emplaced at 247.5 ± 0.62 Ma. Additionally, the adakitic characteristics of the Nianzi, Xiawopu and Xiaolianghou granitic intrusions, such as high Sr and Ba contents and high ratios of Sr/Y and (La/Yb)N, combined with negative Sr-Nd and Lu-Hf isotopes (87Sr/86Sr)i = 0.705681–0.7057433, εNd(t) = ?21.98 to ?20.97, zircon εHf(t) = ?20.26 to ?9.92), as well as the I-type granite features of high SiO2, Na2O and K2O/Na2O ratios, enriched Rb, K, Sr and Ba, along with depleted Th, U, Nb, Ta, P and Ti, suggest that the Nianzi granitic unit was mainly derived from the partial melting of a thickened lower crust containing hydrous, calc-alkaline to high-K calc-alkaline, mafic to intermediate metamorphic rocks. In light of these parameters, we further integrate our data with previous studies and conclude that the Nianzi granitic unit was generated in a post-collisional extensional environment during the Early Triassic.     

国土资源数据整合方法初探

针对国土资源数据库建设存在的单一数据库应用系统、应用系统之间数据共享程度不够等问题,提出了数据资源统一软件平台、统一坐标系、统一符号库等整合方法。通过数据资源整合,实现各专业数据库的一体化管理,可拓展数据应用空间,提高工作效率,进而极大地方便国土资源管理工作。     

双光子湮灭吸收截面和吸收系数

双光子湮灭造成的γ射线吸收是γ射线天文学辐射转移理论的一个重要内容。通过相对论变换，将目前QED理论给出的仅在动量中心参考系中表示的双光子湮灭截面推广到实验室系（观测者系），并用湮灭前两光子的能量hw,hw‘及夹角θ表示此截面，便于γ射线在天文学中的实际应用。进一步，在各向同性周边辐射场的一般前提下，求出方向平均的简化截面公式σ（w,w‘），得出方向平均的湮灭阈值条件和湮灭概率最大时两个光子能量的匹配条件。进一步确认在γ射线天文学中，双光子湮灭截面和γ光子－电子的康普顿散射截面确有可比性。最后完成了天体物理中几种常见低频辐射场如热韧致辐射场、黑体辐射场以及非热的幂律场中双光子湮灭吸收系数krr(hw)-hw的计算曲线，并给出较详细的物理讨论。     

灾害管理决策支持系统之发展建置

灾害管理包括减灾、整备、应变及复原四个阶段，灾害管理决策支持系统建置的主要目的，是整合不同领域的研究成果，透过防救灾体系及防救灾信息系统之建立，提供不同阶段灾害管理所需的信息分析及决策支持功能，以期将天然灾害所造成的生命及财产损失降到最低。本文提出灾害管理决策系统的架构规划，针对不同阶段的灾害管理特性及地区防灾工作实际需求，设置许多相关子系统与之配合，部分子系统已逐次完成。本系统目前朝向发展因特网地理信息系统技术，提供多点远程操作与集中管理功能，以达到灾害实时决策支持之目的。然考虑灾害发生时可能发生停电及网络不通的状况，因此，部分系统仍具有单机操作之功能。     

MapObjects中符号设计组件的设计与实现

组件式GIS已成为地理信息系统发展的一个重要阶段.ESRI公司推出的组件式GIS--MapObjects小巧灵活,运行速度快,开发方便,用很少的代码即可实现最基本的GIS功能,因而得到广泛应用.但MapObjects缺少直接符号化的函数,给用户实际制图工作造成不便.本文采用VC开发工具,结合COM技术,通过设计符号化的组件对这一问题加以解决.     

微动多阶瑞雷波SPAC系数反演方法及应用研究

为充分利用微动信号中基阶和高阶模式瑞雷波,本文研究了基于多阶瑞雷波SPAC系数直接反演的方法.该方法首先基于地层介质响应计算多阶瑞雷波的能量占比,考虑实际观测台阵有限台站个数对SPAC系数影响,正演计算多阶瑞雷波SPAC系数,再采用快速模拟退火算法对其反演以获得地下介质横波速度结构.在此基础上,本文通过数值模拟验证该方法的可靠性,分别选取三种典型地质模型,基于模式叠加算法合成理论微动信号,采用本文方法计算其理论多阶瑞雷波SPAC系数并反演,给出反演结果与真实模型对比.我们将该方法应用于上海中心城区的地质调查中,通过与钻探结果对比,进一步验证该方法的有效性.本文理论与实际应用研究表明,基于多阶瑞雷波SPAC系数直接反演的微动探测方法有助于提高反演结果的可靠性,尤其对含软硬夹层的复杂地层介质,可提高探测精度.     

水准尺倾斜对高铁桥墩沉降观测的影响研究

结合目前国内高铁建设实际,对桥墩沉降观测作业过程中水准尺倾斜的问题进行系统研究,并提出仪器高不变法和两次仪器高法等方法,可有效减弱水准尺倾斜对沉降观测结果精度的影响,并通过工程实例,验证其有效性和可操作性。