月球光学遥感与制图研究进展   总被引：1，自引：0，他引：1  

刘建军  任鑫  王奋飞  牟伶俐  王文睿  谭旭 《矿物岩石地球化学通报》2015,(3)

在月球探测活动中,光学成像探测是任务重点,也是信息量最大的数据源。航天技术和传感器技术的发展促进了月球光学遥感的发展,月球科学研究也越来越依赖于高分辨率遥感数据,对月球光学遥感与制图的研究是月球探测的关键问题之一。本文扼要论述了其中的几个方面,包括月球光学遥感数据获取系统、月球遥感立体测绘和制图,以及月球控制网构建等方面的研究进展。  相似文献   

Empirical modeling of plate load test moduli of soil via gene expression programming     

Ali Mollahasani  Amir Hossein Alavi  Amir Hossein Gandomi 《Computers and Geotechnics》2011

New empirical models were developed to predict the soil deformation moduli using gene expression programming (GEP). The principal soil deformation parameters formulated were secant (E_s) and reloading (E_r) moduli. The proposed models relate E_s and E_r obtained from plate load-settlement curves to the basic soil physical properties. The best GEP models were selected after developing and controlling several models with different combinations of the influencing parameters. The experimental database used for developing the models was established upon a series of plate load tests conducted on different soil types at depths of 1–24 m. To verify the applicability of the derived models, they were employed to estimate the soil moduli of a part of test results that were not included in the analysis. The external validation of the models was further verified using several statistical criteria recommended by researchers. A sensitivity analysis was carried out to determine the contributions of the parameters affecting E_s and E_r. The proposed models give precise estimates of the soil deformation moduli. The E_s prediction model provides considerably better results in comparison with the model developed for E_r. The simplified formulation for E_s significantly outperforms the empirical equations found in the literature. The derived models can reliably be employed for pre-design purposes.  相似文献   

侧限压缩下砂土的细观力学特性及其形态分析   总被引：1，自引：0，他引：1       下载免费PDF全文

曹亮  刘文白  李晓昭  赵晓豹  张辉 《地质论评》2011,57(4):591-599

本文基于室内固结试验,自行设计加工了土体受到轴向压力和侧限条件时,对土的细观结构进行观测的细观结构观测固结仪.通过对中砂半模固结仪试验的宏观变形场分析选择了细观特征观测点,发现中砂的位移场类似于抛物线形,位移量最大区总是发生在上透水石的底面中心处;利用MiFas图像软件对中砂压缩过程中的显微图像进行处理,分析了中砂试样...  相似文献   

A hybrid computational approach to formulate soil deformation moduli obtained from PLT     

Seyyed Mohammad Mousavi  Amir Hossein Alavi  Ali Mollahasani  Amir Hossein Gandomi 《Engineering Geology》2011,123(4):324

In this study, new empirical equations were developed to predict the soil deformation moduli utilizing a hybrid method coupling genetic programming and simulated annealing, called GP/SA. The proposed models relate secant (E_s), unloading (E_u) and reloading (E_r) moduli obtained from plate load–settlement curves to the basic soil physical properties. Several models with different combinations of the influencing parameters were developed and checked to select the best GP/SA models. The database used for developing the models was established upon a series of plate load tests (PLT) conducted on different soil types at various depths. The validity of the models was tested using parts of the test results that were not included in the analysis. The validation of the models was further verified using several statistical criteria. A traditional GP analysis was performed to benchmark the GP/SA models. The contributions of the parameters affecting E_s, E_u and E_r were analyzed through a sensitivity analysis. The proposed models are able to estimate the soil deformation moduli with an acceptable degree of accuracy. The E_s prediction model has a remarkably better performance than the models developed for predicting E_u and E_r. The simplified formulations for E_s, E_u and E_r provide significantly better results than the GP-based models and empirical models found in the literature.  相似文献   

Vitreous state in nature—Origin and properties     

Klaus Heide  Gerhard Heide 《Chemie der Erde / Geochemistry》2011,71(4):305-335

Vitreous materials are quite routinely found in natural settings. Most of them are aluminosilicates, which often occur in large deposits. Considering the geological formations in which naturally occurring vitreous aluminosilicates are found, they have generally remained stable for more than 1 Ma on the earth's surface, even in different geological and climatic environments. These non-crystalline solids played a very important role in the development of ancient human civilizations, long before the introduction of metallic tools. Today, however, the properties of natural glasses are of interest to mankind for completely different reasons. For example, industrial glasses are used today for encapsulating toxic wastes, especially radioactive waste, which remains active for centuries or more, in order to prevent the unwanted transfer of harmful materials to the environment. The chemical compositions of industrially produced glasses are in large part different from the compositions of natural glasses. Little is quantitatively known about the stability of industrial glasses over very long periods of time (>10,000 years). However, the physical and chemical stability of natural aluminosilicate glasses is known to extend over very long periods of time.The advancement of technological design to prevent or at least minimize the melt down of toxic waste during the encapsulation process is currently a major challenge, using glasses of natural chemical composition. Brecciated glass, which is found frequently in natural settings, provides a special clue to the possibility of producing vitreous solids by sintering glass fragments without melting the cullets. It is essential to prevent melting of the cullets because the melt has the potential of chemically reacting with the toxic waste.This paper summarizes the geological, chemical, and physical facts concerning naturally produced glasses, and seeks to establish a recognized database for further research in the domain of understanding the glass-forming processes that occur in nature. Furthermore, the authors hope to stimulate research into the utilization of natural resources that to solve the problem of storing of toxic waste safely.Major and trace element data have been collected over the past 100 years. These data constitute a sufficient basis for the chemical characterization of natural glasses. More information about the major elements is not required, in order to understand the chemical properties of these materials. On the other hand, large gaps in compositional data exist where other related components are concerned: e.g., in the case of “water-species”, with its different forms of bonding in silicates or oxygen (oxygen fugacity), CO₂-, sulphur - or hydrocarbons (methane)-, hydrogen-, chlorine-and fluorine-species. All these components have a significant impact on the properties of glasses, even when present only in minor quantities. Glass textures and crystal morphologies reflect the processes of nucleation and crystal growth in a glass-forming matrix during the cooling and reheating cycles which are currently not thoroughly understood. In nature, the processes that led to the formation of vitreous materials are very different from those used in the production of industrial glasses. The different genetic conditions under which glass formation occurs permit differentiation between magmatic and metamorphic vitreous solids. Sedimentary and biogenetic processes also contribute to the formation of non-crystalline solids.  相似文献   

循环冻融条件下安山岩和花岗岩的物理力学特性试验研究   总被引：5，自引：0，他引：5  

刘华  牛富俊  徐志英  林战举  许健 《冰川冻土》2011,33(3):557-563

结合青藏铁路块石护坡路基处于青藏高原特殊的气候条件,对用于青藏铁路护坡的两种主要岩石（花岗岩和安山岩）进行循环冻融试验.结果表明:两种岩石在经历了数次冻融循环后都出现了微细裂纹;声波监测表明,超声波速同冻融循环周期呈指数下降关系,显示了冻融循环对岩石风化的影响以及循环后岩石物理力学参数变化的趋势.结果说明,花岗岩的冻融...  相似文献   

长江源北麓河流域多年冻土区热融湖塘形成对高寒草甸土壤环境的影响   总被引：10，自引：7，他引：3  

王一博  吴青柏  牛富俊 《冰川冻土》2011,33(3):659-667

通过对长江源北麓河流域多年冻土区热融湖塘及湖塘影响周边条件下高寒草甸土壤理化性质的比较研究,结果表明:热融湖塘的形成对高寒草甸土壤环境产生了明显影响,热融湖塘形成对土壤质地、含水量、容重以及土壤养分等产生强烈改变,尤其表层土壤;土壤机质(SOM)、全氮(N)等化学物质和其他养分成分在不同退化的土壤中都有所改变.有机质和...  相似文献   

The Seasonal Variations of Aerosols over East Asia as Jointly Inferred from MODIS and OMI          下载免费PDF全文

LIU Qi  DING Wei-Dong  FU Yun-Fei 《大气和海洋科学快报》2011,4(6):330-337

Data on aerosol optical thickness(AOT) and single scattering albedo(SSA) derived from Moderate Resolution Imaging Spectrometer(MODIS) and Ozone Monitoring Instrument(OMI) measurements,respectively,are used jointly to examine the seasonal variations of aerosols over East Asia.The seasonal signals of the total AOT are well defined and nearly similar over the land and over the ocean.These findings indicate a natural cycle of aerosols that originate primarily from natural emissions. In contrast,the small-sized aerosols represented by the fine-mode AOT,which are primarily generated over the land by human activities,do not have evident seasonalscale fluctuations.A persistent maximum of aerosol loadings centered over the Sichuan basin is associated with considerable amounts of fine-mode aerosols throughout the year.Most regions exhibit a general spring maximum. During the summer,however,the aerosol loadings are the most marked over north central China.This occurrence may result from anthropogenic fine particles,such as sulfate and nitrate.Four typical regions were selected to perform a covariation analysis of the monthly gridded AOT and SSA.Over southwestern and southeastern China,if the aerosol loadings are small to moderate they are composed primarily of the highly absorptive aerosols. However,more substantial aerosol loadings probably represent less-absorptive aerosols.The opposite covariation pattern occurring over the coastal-adjacent oceans suggests that the polluted oceanic atmosphere is closely correlated with the windward terrestrial aerosols.North central China is strongly affected by dust aerosols that show moderate absorption.This finding may explain the lower variability in the SSA that accompanies increasing aerosol loadings in this region.  相似文献   

Study on Probability Distributions of Multi-Timescale Aerosol Optical Depth Using AERONET Data          下载免费PDF全文

WU Lin  ZENG Qing-Cun 《大气和海洋科学快报》2011,4(4):216-222

The probability distribution analysis is per-formed for multi-timescale aerosol optical depth (AOD) using AErosol RObotic NETwork (AERONET) level 2.0 data.The maximum likelihood estimation is employed to determine the best-fit probability density function (PDF),and the statement that the fitting Weibull distribution will be light-tailed is proved true for these AOD samples.The best-fit PDF results for multi-site data show that the PDF of AOD samples with longer timescale in most sites tends to be stably represented by lognormal distribution,while Weibull distribution is a better fit for AOD samples with short timescales.The reason for this difference is ana-lyzed through tail characteristics of the two distributions,and an indicator for the selection between Weibull and lognormal distributions is suggested and validated.The result of this research is helpful for determining the most accurate AOD statistics for a given site and a given time-scale and for validating the retrieved AOD through its PDF.  相似文献   

Reconstruction of sub-wavelength fractures and physical properties of masonry media using full-waveform inversion of proximal penetrating radar   总被引：1，自引：0，他引：1  

Claudio Patriarca  Sbastien Lambot  M.R. Mahmoudzadeh  Julien Minet  Evert Slob 《Journal of Applied Geophysics》2011,74(1):26-37

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