差分层析SAR技术研究现状分析

差分层析SAR是在层析SAR基础上发展起来的一种四维信息反演技术。它不仅实现了对雷达目标的三维分辨能力,同时可以获取目标的形变速率信息,可实现对目标方位-距离-高度-时间四维成像,这对实现城市基础设施动态形变监测、古建筑风险评估、重要工程安全监测等应用具有重要实际意义和价值。本文基于差分层析SAR成像原理,分析了成像处理过程中存在的问题,总结了差分层析SAR成像算法研究现状和特点;最后列举了差分层析SAR技术的主要应用领域,并对其技术发展趋势进行了展望。     

Differential subduction and exhumation of crustal slices in the Sulu HP-UHP metamorphic terrane: insights from mineral inclusions, trace elements, U-Pb and Lu-Hf isotope analyses of zircon in orthogneiss

Based on new evidence the Sulu orogen is divided from south‐east to north‐west into high‐pressure (HP) crustal slice I and ultrahigh‐pressure (UHP) crustal slices II and III. A combined set of mineral inclusions, cathodoluminescence images, U‐Pb SHRIMP dating and in situ trace element and Lu‐Hf isotope analyses was obtained on zircon from orthogneisses of the different slices. Zircon grains typically have three distinct domains that formed during crystallization of the magmatic protolith, HP or UHP metamorphism and late‐amphibolite facies retrogression, respectively: (i) oscillatory zoned cores, with low‐pressure (LP) mineral inclusions and Th/U > 0.38; (ii) high‐luminescent mantles (Th/U < 0.10), with HP mineral inclusions of Qtz + Grt + Arg + Phe + Ap for slice I zircon and Coe + Grt + Phe + Kfs + Ap for both slices II and III zircon; (iii) low‐luminescent rims, with LP mineral inclusions and Th/U < 0.08. Zircon U‐Pb SHRIMP analyses of inherited cores point to protolith ages of 785–770 Ma in all seven orthogneisses. The ages recorded for UHP metamorphism and subsequent retrogression in slice II zircon (c. 228 and c. 215 Ma, respectively) are significantly older than those of slice III zircon (c. 218 and c. 202 Ma, respectively), while slice I zircon recorded even older ages for HP metamorphism and subsequent retrogression (c. 245 and c. 231 Ma, respectively). Moreover, Ar‐Ar biotite ages from six paragneisses, interpreted as dating amphibolite facies retrogression, gradually decrease from HP slice I (c. 232 Ma) to UHP slice II (c. 215 Ma) and UHP slice III (c. 203 Ma). The combined data set suggests decreasing ages for HP or UHP metamorphism and late retrogression in the Sulu orogen from south‐east to north‐west. Thus, the HP‐UHP units are interpreted to represent three crustal slices, which underwent different subduction and exhumation histories. Slice I was detached from the continental lithosphere at ～55–65 km depth and subsequently exhumed while subduction of the underlying slice II continued to ～100–120 km depth (UHP) before detachment and exhumation. Slice III experienced a similar geodynamic evolution as slice II, however, both UHP metamorphism and subsequent exhumation took place c. 10 Myr later. Magmatic zircon cores from two types of orthogneiss in UHP slices II and III show similar mid‐Neoproterozoic crystallization ages, but have contrasting Hf isotope compositions (εHf_(～785) = ?2.7 to +2.2 and ?17.3 to ?11.1, respectively), suggesting their formation from distinct crustal units (Mesoproterozoic and Paleoproterozoic to Archean, respectively) during the breakup of Rodinia. The UHP and the retrograde zircon domains are characterized by lower Th/U and ¹⁷⁶Lu/¹⁷⁷Hf but higher ¹⁷⁶Hf/¹⁷⁷Hf(t) than the Neoproterozoic igneous cores. The similarity between UHP and retrograde domains indicates that late retrogression did not significantly modify chemical and isotopic composition of the UHP metamorphic system.     

气候变化和人类活动对中国地表水文过程影响定量研究

利用中国372个水文站月径流数据（1960-2000年）及41个水文站年径流数据（2001-2014年）,采用基于Budyko假设的水热耦合平衡方程,构建气候变化和人类活动对径流变化影响定量评估模型,在Penman-Monteith潜在蒸发分析基础上,进一步分析气象因子对径流变化的弹性系数,量化气候变化和人类活动对径流变化的影响。结果表明：① 中国北方地区流域径流变化对各气象因子弹性系数明显大于中国南方地区。就全国而言,径流变化对各因子的弹性系数为：降水>土地利用/土地覆盖变化（LUCC）>相对湿度>太阳辐射>最高气温>风速>最低气温;② 1980-2000年,气候变化总体上有利于增加中国年径流量,而降水对年径流量增加的贡献最为显著;③ 1980-2000年,中国南方流域中,气候变化对年径流变化的影响以增加作用为主,而北方流域,以减少年径流作用为主。对中国大多数流域径流变化而言,人类活动的影响主要以减少年径流量为主。2001-2014年,气候变化以减少径流量为主,人类活动对径流变化的影响程度明显增强,气候变化与人类活动对径流变化的贡献率分别为53.5%、46.5%。该研究对气候变化与人类活动影响下,中国水资源规划管理、防灾减灾及保障水资源安全具有重要理论与现实意义。     

浅谈全国第二次土地调查项目的几个关键环节

介绍了全国第二次土地调查项目中调绘底图生产、土地调查、田坎系数测定、农村宅基地调查等关键环节,结合实际生产,分析了各环节的重要性及实施情况。     

星际A型CH_3CH－H_2含超精细能级的碰撞跃迁速率系数的理论计算

本文作者利用ＩＯＳ近似模型，计算了星际分子云条件下Ａ型ＣＨ３ＣＮ－Ｈ２含超精细能级的碰撞跃迁速率系数。温度范围是２０Ｋ－１４０Ｋ。为研究分子云与恒星形成区的物理、化学性质提供了有用的基础分子数据。     

Spectral Simulation and Conditioning to Local Continuity Trends in Geologic Modeling

Spectral simulation has gained application in building geologic models due to the advantage of better honoring the spatial continuity of petrophysical properties, such as reservoir porosity and shale volume. Distinct from sequential simulation methods, spectral simulation is a global algorithm in the sense that a global density spectrum is calculated once and the inverse Fourier transform is performed on the Fourier coefficient also only once to generate a simulation realization. The generated realizations honor the spatial continuity structure globally over the whole field instead of only within a search neighborhood, as with sequential simulation algorithms. However, the disadvantage of global spectral simulation is that it traditionally cannot account for the local information such as the local continuity trends, which are often observed in reservoirs and hence are important to be accounted for in geologic models. This disadvantage has limited wider application of spectral simulation in building geologic models. In this paper, we present ways of conditioning geologic models to the relevant local information. To account for the local continuity trends, we first scale different frequency components of the original model with local-amplitude spectrum ratios that are specific to the local trend. The sum of these scaled frequency components renders a new model that displays the desired local continuity trend. The implementation details of this new method are discussed and examples are provided to illustrate the algorithm.     

一种基于最佳指数模型的 TM 遥感影像最佳波段组合计算方法

如何通过定量计算选择最佳波段组合一直是TM等多波段遥感影像信息提取的研究热点。本文综合利用Erdas提供的可视化空间建模工具（ Spatial Modeler ）和面向对象的编程技术,提出了一种基于最佳指数（ Opti-mum Index Factor ,OIF）的定量计算与定性分析相结合的TM遥感影像最佳波段组合方法。实验证明,该方法快速有效,极大提升了TM等多波段遥感影像最佳波段组合的计算过程。     

全国分县土地经济系数计算方法及比较

阐述土地经济系数的设置意义和目标,针对全国分县土地经济系数计算,提出并分析比较了统计指标法和分区样点法等思路及其数学处理方法。其中统计指标法中的农业产值消耗法基础数据来源可靠、便利,便于操作,计算结果较好,符合土地经济系数含义要求。     

静态密闭状态下大甸子井孔隙度与体积压缩系数时序特征分析

以内蒙古大甸子观测井为数据收集对象,利用原始水位观测数据得到该井静态密闭下气压系数、水位与气压的关系以及孔隙度与气压系数的关系,从而分析该井静态密闭状态下孔隙度与体积压缩系数时序特征。结果表明,孔隙度与固体骨架的体积压缩系数和含水层内水的体积压缩系数间存在幂函数关系;在第一象限内,各井含水层介质固体骨架的体积压缩系数随着孔隙度的增大而增大;含水层内水的体积压缩系数随着孔隙度的增大而减小。     

一种近岸区波浪破碎模型

从波浪破碎的能量关系入手,以紊流能量方程为基础,考虑破碎区内单个波在不同破碎阶段所提供的紊动能量强度的变化过程,提出了一种波浪破碎模式.通过将这一模型引入Boussinesq方程中,初步建立了一种近岸区波浪变形数学模型,并用波浪水槽实验资料对模型模拟波高和平均水位的情况进行了初步验证,得到了良好的结果.