Analysis of a high-amplitude event in component A of the gravitational lens QSO 2237+0305

We present an analysis of a high-amplitude event in the flux curve of component A of the gravitational lens QSO 2237+0305 observed by the OGLE and GLITP groups in autumn 1999. Hypothesizing this event to be associated with microlensing of a fold caustic, we analyzed the observational data using a method for the successive reconstruction of branches of the one-dimensional strip brightness distribution across the source corresponding to positive and negative arguments. The search for the branches was carried out on compact sets of nonnegative, monotonically nonincreasing, convex downward functions. The resulting shape of the strip brightness distribution for the accretion disk of the quasar is in agreement with results obtained earlier via model fitting. Features in the lensing curve that could be associated with curvature of the caustic, nearness of a cusp, or the influence of nearby caustics are noted.     

The gravitational lens Q2237+0305: Reduction and analysis of the observational data

The results of V RI photometry of the gravitationally lensed system Q2237+0305 carried out on the 1.5-m telescope of the Maidanak Observatory in 2004–2005 are presented. The method used to reduce the observational data is described in detail. An analysis of the brightness and color variations of the system’s components is presented.     

Optical observations of the gravitational lens SBS1 520+530 at the Ma $$\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l} $$ danak Observatory

Observations of the gravitationally lensed quasar SBS 1520+530 obtained in 2000–2001 on the 1.5-m telescope of the Ma $\overset{\lower0.5em\hbox{$\overset{\lower0.5em\hbox{ danak Observatory (Uzbekistan) are presented. The photometric algorithms used to observe the components of SBS 1520+530 are discussed. The images have a resolution of 0.5″–0.6″, enabling us to detect the lensing galaxy in the R and I bands and to measure its luminosity and coordinates. The results of photometric observations of components A and B of SBS 1520+530 are presented; the light curves show variability on various time scales from a few weeks to a year. A gravitational-lens model for SBS 1520+530 is constructed utilizing all currently available data.     

遥感影像库中影像布局功能的开发实现

打印布局是众多软件必备的功能。布局是一种图纸空间环境,它通过模拟图纸页面,提供直观的打印设置。利用ArcObjects强大的开发功能,通过可视化编程,开发实现了遥感影像库中以布局管理和布局设置两个模块为核心的影像布局模块,并详细描述了打开布局和布局设置的开发过程和技术障碍,解决了多个图层加载时图层闪烁和速度慢的缺点,从而满足遥感影像库中图像打印输出的需要。     

Simple procedure for quantification of the gravitational stress field in fractured hard rock massifs

In this paper, a quantitative procedure for evaluating the gravitational stress field in a hard rock massif is presented, using only a geological hammer and compass. Using the orientation of the fracture planes and their statistical distribution, a method for calculating of the tendency of the fractures to reactivate under gravitational load is proposed, based on Coulomb failure criterion. The method is applicable for assessing the most stable layout of the underground excavations and for evaluating the geometry of the stress field at a point during the initial stage of rock failure.     

黑河流域TM/ETM+影像数字镶嵌图的制作与应用研究

对研究区内两个时期(1986-1990年和1999-2000年)20景Landsat TM5或Landsat ETM7影像图进行多波段合成、色彩优化、几何配准和数字镶嵌等预处理工作,生成试验区两个时期的TM/ETM+影像数字镶嵌图,并利用均方根(Root mean square, RMS)误差法评价几何配准的精度,用采样法评价数字镶嵌的精度. 结果表明,单景TM/ETM+影像图几何配准的精度可以控制在1个像元以内. 多景数字镶嵌时多数点的RMS误差小于2个像元,总的RMS误差在1.3～1.5之间. 利用影像图作为几何配准的数据源的方法要优于利用地形图作为几何配准的数据源的方法.     

A self-consistent model for an isotropic universe evolving under the influence of quantum gravitational effects

The polarization-correction energy-momentum tensor for a semi-classical gravitational theory is derived. This tensor accounts for the creation of particles from a vacuum at a finite temperature. The theory contains an asymptotic cosmological Friedmann solution. The solution obtained turns out to be dynamically stable, so that it can form the observed properties of the Universe. New cosmological solutions describing the early stages of cosmological evolution of a homogeneous isotropic Universe are obtained. One of these corresponds to the simultaneous creation of matter and geometry from the vacuum of a flat, empty space-time without structure. Another solution corresponds to a high-temperature inflation regime. A cosmological scenario for the creation of the observed Universe from “nothing” that includes the properties of all the solutions obtained is put forward.     

Empirical calibration of six geobarometers for the mineral assemblage quartz+muscovite+biotite+plagioclase+garnet

Six equilibria among quartz, plagioclase, biotite, muscovite, and garnet were empirically calibrated using mineral composition data from 43 samples having the assemblage quartz+muscovite+biotite+garnet+plagioclase+Al₂SiO₅ (sillimanite or kyanite). Pressures and temperatures in the data set used for calibration were determined through the simultaneous application of garnet-biotite geothermometry and garnet-quartz-plagioclase-Al₂SiO₅ geobarometry. Thermodynamic expressions for four of the six equilibria incorporate interaction parameters that model non-ideality in the mixing of cations in the octahedral sites of both muscovite and biotite. With pressure chosen as the dependent variable, multiple regression was used to solve for unknowns in the equilibrium thermodynamic expressions. The regressions yielded multiple correlation coefficients ranging from 0.983 to 0.999, with corresponding standard deviations of 338 and 92 bars in the residuals. The standard deviations in the residuals may be explained largely or entirely by the propagation of errors associated with electron microprobe analysis. These equilibria enable the determination of pressures from equilibrium assemblages of quartz+garnet+plagioclase+muscovite+biotite, and give results closely comparable to the experimentally calibrated garnet-quartz-plagioclase-Al₂SiO₅ geobarometer. Geobarometric applications should be restricted to rocks in which equilibrium constants and compositional variables fall within the same ranges as those used for calibration.     

Segregation freezing as the cause of suction force for ice lens formation

We propose a new freezing mechanism, called segregation freezing, to explain the generation of the suction force that draws pore water up to the freezing surface of a growing ice lens. We derive the segregation freezing temperature by applying thermodynamics to a soil mechanics concept that distinguishes the mechanically effective pressure from the mechanically neutral pressure. The frost-heaving pressure is formulated as part of the solution of the differential equations of the simultaneous flow of heat and water, of which the segregation freezing temperature is one of the boundary conditions.     

基于ETM+影像的西藏南迦巴瓦峰地区海洋性冰川信息提取

西藏墨脱高等级公路方案线穿越冰川作用强烈的南迦巴瓦峰地区, 为查明该区冰川活动对公路工程的影响, 以ETM⁺为信息源, 以图像统计量为基础, 运用遥感数字图像处理技术, 对该区冰川进行了图像光谱信息提取与分析.冰川在 TM5、7 波段光谱值范围窄, 且冰碛与冰雪有明显的光谱差异, 是冰川信息提取的有利波段. 包含TM5、7的多波段图像K—L变换的最后主组分是TM5、7的差值图像, 主要反映的是图像中的冰川信息.这种基于图像变换、信息分离提取冰川信息的方法, 在西藏墨脱高等级公路工程勘察中取得了较好的应用效果.     

长江三角洲全新世海平面重建研究综述

通过综述国内外全新世海平面重建研究进展,总结了全新世海平面重建的各种指标和海平面重建存在的科学问题,认为冰川—水均衡作用、区域差异性构造沉降、沉积物压实和侵蚀再沉积作用是各地区全新世海平面差异性存在的主要原因;对长江三角洲各海平面重建指标进行了有效性分析,得出基底泥炭、硅藻、有孔虫转换函数,海相地层、古人类遗址、TOC/TN和δ13C、TOC/TS和自生铁硫化物是重建海平面的有效指标,并对每个指标的优缺点及重建时需要考虑的问题进行了阐述。     

Phytoliths as quantitative indicators for the reconstruction of past environmental conditions in China II: palaeoenvironmental reconstruction in the Loess Plateau

Quantitative reconstruction of the climatic history of the Chinese Loess Plateau is important for understanding present and past environment and climate changes in the Northern Hemisphere. Here, we reconstructed mean annual temperature (MAT) and mean annual precipitation (MAP) trends during the last 136 ka based on the analysis of phytoliths from the Weinan loess section (34°24′N, 109°30′E) near the southern part of the Loess Plateau in northern China. The reconstructions have been carried out using a Chinese phytolith–climate calibration model based on weighted averaging partial least-squares regression. A series of cold and dry events, as indicated by the reconstructed MAT and MAP, are documented in the loess during the last glacial periods, which can be temporally correlated with the North Atlantic Heinrich events. Our MAT and MAP estimations show that the coldest and/or driest period occurred at the upper part of L2 unit (Late MIS 6), where MAT dropped to ca 4.4 °C and MAP to ca 100 mm. Two other prominent cold-dry periods occurred at lower Ll-5 (ca 77–62 ka) and L1-1 (ca 23–10.5 ka) where the MAT and MAP decreased to about 6.1–6.5 °C and 150–370 mm, respectively, ca 6.6–6.2 °C and 400–200 mm lower than today. However, the highest MAT (average 14.6 °C, max. 18.1 °C) and MAP (average 757 mm, max. 1000 mm) occurred at Sl interval (MIS 5). During the interstadial of L1-4–L1-2 (MIS 3) and during the Holocene warm-wet period, the MAT was about 1–2 °C and MAP 100–150 mm higher than today in the Weinan region. The well-dated MAT and MAP reconstructions from the Chinese Loess Plateau presented in this paper are the first quantitatively reconstructed proxy record of climatic changes at the glacial–interglacial timescale that is based on phytolith data. This study also reveals a causal link between climatic instability in the Atlantic Ocean and climate variability in the Chinese Loess Plateau.     

图像法水面流速测验方法简介

针对北方山溪性河流采用传统浮标法水面流速测验存在的不足，介绍了一种采用摄影测量技术进行水面流速测验的方法，阐述了坐标转换模型建立、浮标拟合的思路与步骤。     

基于重构信号模型的去噪技术

面波和多次波等噪音的产生是海上地震勘探的突出特点,如何高保真地对其进行压制一直是信号处理工作的难题。基于重构信号模型的去噪技术通过不同的方法,充分考虑不同入射角度和横波地震信息,重构信号模型,分离出剩余信号,然后针对剩余信号进行去噪处理,利用建立的信号模型和剩余有效信号结合,得到有效地震信号,达到突出有效信号衰减噪声的目的。     

沉积盆地下古生界碳酸盐岩地区热历史恢复方法探索

古温标是目前恢复沉积盆地热历史最常用方法之一,但在下古生界高过成熟碳酸盐岩由于没有合适的成熟度标定参数(古温标),对其经受的热历史和成烃史的恢复一直是困扰中国海相碳酸盐岩油气勘探的问题。目前常用的沥青反射率、牙形石色变指数、镜状体反射率等各类古温标,在用于早古生代碳酸盐岩地区的热历史恢复时都是借助于它们各自与镜质体反射率之间的关系,再利用现有的镜质体反射率模拟热历史方法来恢复热历史,因而存在不同的缺陷。重点介绍了利用有机质自由基浓度作为碳酸盐岩地区古温标的可能性。通过不同时间和温度下的热模拟得到的有机质自由基浓度数据,初步建立了三种类型有机质的自由基浓度(N)与时间-温度指数(TTI)的定量模型。这种有机质自由基浓度与TTI的关系式为碳酸盐岩地区古地温的恢复提供了新的方法。     

基于TM/ETM+影像反演祁连山七一冰川反照率精度比较研究

冰川反照率是联系冰川与气候、 寒区水文过程的纽带, 也是制约分布式冰川能量-物质平衡模型发展的重要因子.冰雪反照率的变化会改变整个地气系统的能量收支平衡, 亦可引起局地以至全球的气候变化.利用Landsat TM/ETM+数据, 运用不同学者提出的窄波段转换宽波段的方程, 反演了祁连山七一冰川总短波段的反照率.把不同的转换方程得到反演值与实测值进行比较, 选择绝对误差最小的反演公式.结果表明: Duguay1992模型提出的方程能保证4景影像反演值与实测值的绝对误差在0.05范围内, 而气候模式输入的反照率产品要求绝对误差在0.05以内.运用该方程反演的反照率结果, 较其他方程要准确, 可为分布式冰川物质-能量平衡模型的构建提供更准确的参数数据.     

浅埋硬土层小截面短桩沉桩分析

在地层比较特殊的地段,往往由于经验及对地质情况认识不深而出现沉桩困难、桩头开裂等现象。文章针对浅埋硬土层采用小截面短桩情况,应用静力触探测试指标计算沉桩阻力,结合考虑桩身强度的方法进行沉桩分析,并统计了不同锤型入持力层不同深度的实际锤击数,为以后类似工程的选锤提供参考。