对于氟碳钡铈矿（Cordylite—Ce）成分与结构的质疑   总被引：2，自引：0，他引：2  

沈今川  宓锦校 《岩石矿物学杂志》1992,11(1):69-74

本文讨论了氟碳钡铈矿的成分和结构问题。发现氟碳钡铈矿的成分、密度、折射率三者间的一致性参数很差,晶体结构与光性和空间群相矛盾,单个大阳离子的平均占有体积远大于同类矿物的平均占有体积,它的晶体结构与同类矿物不可类比。由于受当时条件的限制,在以往有关氟碳钡铈矿的成分和结构的资料中存在着一些明显的错误,有必要对其进行重新定义。其结构化学式应改为:(Na_(1-x),Ca_(0·5x))BaCe_2(CO_3)_4F。  相似文献   

用气象卫星资料监测冬麦长势和估测产量的研究   总被引：1，自引：0，他引：1  

陈添宇  秘晓东 《干旱气象》1995,(3)

利用１９９２、１９９３年的气象卫星资料，分析植被指数与甘肃省冬麦区３３个县市冬麦产量的关系，发现绿峰植被指数与产量存在极好的相关性。另外，从预测产量的角度和预报时限要求出发，可用４月中下旬累积植被指数预测冬麦产量，并给出了预报方程。  相似文献   

黑龙江伊春红山华夏—安加拉混生植物群   总被引：1，自引：0，他引：1  

金建华  米家榕 《吉林大学学报(地球科学版)》1993,(3)

系统研究了黑龙江省伊春红山地区晚二叠世红山组植物群,认为其性质为华夏—安加拉混生植物群。华夏植物区与安加拉植物区的界限,应以内蒙古陆及其东、西延展部分为界。  相似文献   

Comparison of the spatial distribution of ground motion between main shocks and strong aftershocks     

吕晓健高孟潭  高战武米素婷 《地震学报(英文版)》2007,20(3):312-318

Using the ground motion attenuation relation, we calculated and compared the effective peak acceleration (EPA) generated by main shocks and their strong aftershocks of 21 earthquake sequences with MS≥7 occurred in Chinese mainland and offing of China during 1966~2002. The result shows that EPA of strong aftershocks usually exceed that of main shock for 76.2% earthquake sequences and EPA of more than 50% strong aftershocks are greatly lar-ger than that of main shocks in large area, which suggests that it is necessary to take damage produced by strong aftershock into account in the probabilistic seismic hazard analysis and the seismic design.  相似文献   

无缝立体正射影像数据库的概念、原理及其实现   总被引：1，自引：0，他引：1  

李德仁  王密  潘俊  胡芬 《武汉大学学报(信息科学版)》2007,32(11):950-954

为了充分地开发和利用航空摄影测量所形成的立体模型,在二维无缝正射影像数据库的基础上,提出了无缝立体正射影像数据库的概念,即在摄影测量所形成的区域范围内,利用原始影像、定向参数及DEM,通过数字投影处理的方法,用无缝镶嵌的数字正射影像和立体辅助影像形成对摄影区域范围内无缝立体覆盖,即可以恢复摄影时记录的地形表面和地物碎部的三维信息,又可以通过立体观察设备进行无缝立体观察、浏览量测。为了方便立体观察、高精度立体量测和应用,对数字正射影像、立体辅助影像、像片定向参数及其DEM通过数据库的方式进行管理,形成区域范围内的无缝立体正射影像数据库。试验表明,无缝立体正射影像数据库具有良好的应用价值和应用前景。  相似文献   

多尺度的DMC彩色合成影像辐射再处理方法     

潘俊  王密 《武汉大学学报(信息科学版)》2007,32(9):800-803

在分析DMC（digital mapping camera）彩色合成影像存在的色彩过渡不平滑现象的特点和成因的基础上,提出了一种多尺度辐射再处理方法来改善影像质量。该方法采用多尺度处理策略,能自动定位拼接线和过渡区域的具体位置。实验表明,本文方法能够有效地改善DMC彩色合成影像的质量。  相似文献   

Demersally drifting invertebrates from Kongsfjorden,Svalbård (Arctic Ocean)–a comparison of catches from drift-pump and drift-nets     

Hans-Uwe Dahms  Hyoung-Min Joo  Jae Hyung Lee  Mi Sun Yun  So Hyun Ahn  Sang Heon Lee 《Ocean Science Journal》2015,50(4):639-648

Demersally drifting organisms were collected at Ny Ålesund (Svalbård–Arctic Ocean) to study the taxon composition and relative abundances in the Arctic summer. Catch potentials of two collection devices for demersal drift were compared. A lowvolume submersible drift-pump and a drift-net unit were employed for the collection of demersally drifting biota, particularly for shallow aquatic habitats. With the exception of Appendicularia, Chaetognatha, Coelenterata, and Ctenophora, which were damaged at times, the pump catches were in good condition and sufficient for identification and quantification of less mobile fauna. A comparison of the two devices revealed that the drift-pump collected more specimens than the drift-net. However, the drift-net may have caused an underestimation of the abundances of invertebrates. No differences in identified taxon number and indices of richness, evenness and diversity were found. However, the proportion of invertebrate animals in the two devices was different for the three groups: zooplankton, macrofauna and meiofauna. At Svalbård, zooplankton, larvae of macrofauna, and meiofauna were successfully collected by the two collecting devices. However, the catchibility of the two devices in collecting various invertebrate taxa was different and, therefore, a sound ‘Device Effect’ was revealed.  相似文献   

遥感影像智能解译样本库现状与研究     

龚健雅  许越  胡翔云  姜良存  张觅 《测绘学报》2021,50(8):1013-1022

我国遥感对地观测等项目顺利实施,获取了大量时效性强、覆盖范围广、信息量丰富的遥感数据.但遥感影像智能化自动处理技术发展仍相对滞后,无法满足区域/全球大范围地物信息快速提取的需求.近年来,人们利用深度学习技术显著提高了影像特征提取成效,但由于所使用的深度学习样本数量和类型有限,对于多源遥感影像的自动解译能力仍然不足.本文面向大范围多源遥感影像地物信息智能解译需求,在分析现有样本集现状及问题的基础上,研究提出遥感影像智能解译样本库设计方案,并在此基础上设计了基于互联网的样本协同采集与共享服务框架.本文将为多源遥感影像样本库建设提供参考,为大范围遥感影像智能解译提供支持.  相似文献   

Hyperspectral mapping of alteration assemblages within a hydrothermal vug at the Haughton impact structure,Canada          下载免费PDF全文

Rebecca N. Greenberger  John F. Mustard  Gordon R. Osinski  Livio L. Tornabene  Alexandra J. Pontefract  Cassandra L. Marion  Roberta L. Flemming  Janette H. Wilson  Edward A. Cloutis 《Meteoritics & planetary science》2016,51(12):2274-2292

Meteorite impacts on Earth and Mars can generate hydrothermal systems that alter the primary mineralogies of rocks and provide suitable environments for microbial colonization. We investigate a calcite–marcasite‐bearing vug at the ~23 km diameter Haughton impact structure, Devon Island, Nunavut, Canada, using imaging spectroscopy of the outcrop in the field (0.65–1.1 μm) and samples in the laboratory (0.4–2.5 μm), point spectroscopy (0.35–2.5 μm), major element chemistry, and X‐ray diffraction analyses. The mineral assemblages mapped at the outcrop include marcasite; marcasite with minor gypsum and jarosite; fibroferrite and copiapite with minor gypsum and melanterite; gypsum, Fe³⁺ oxides, and jarosite; and calcite, gypsum, clay, microcline, and quartz. Hyperspectral mapping of alteration phases shows spatial patterns that illuminate changes in alteration conditions and formation of specific mineral phases. Marcasite formed from the postimpact hydrothermal system under reducing conditions, while subsequent weathering oxidized the marcasite at low temperatures and water/rock ratios. The acidic fluids resulting from the oxidation collected on flat‐lying portions of the outcrop, precipitating fibroferrite + copiapite. That assemblage then likely dissolved, and the changing chemistry and pH resulting from interaction with the calcite‐rich host rock formed gypsum‐bearing red coatings. These results have implications for understanding water–rock interactions and habitabilities at this site and on Mars.  相似文献   

Evidence for high‐temperature fractionation of lithium isotopes during differentiation of the Moon          下载免费PDF全文

James M. D. Day  Lin Qiu  Richard D. Ash  William F. McDonough  Fang‐Zhen Teng  Roberta L. Rudnick  Lawrence A. Taylor 《Meteoritics & planetary science》2016,51(6):1046-1062

Lithium isotope and abundance data are reported for Apollo 15 and 17 mare basalts and the LaPaz low‐Ti mare basalt meteorites, along with lithium isotope data for carbonaceous, ordinary, and enstatite chondrites, and chondrules from the Allende CV3 meteorite. Apollo 15 low‐Ti mare basalts have lower Li contents and lower δ⁷Li (3.8 ± 1.2‰; all uncertainties are 2 standard deviations) than Apollo 17 high‐Ti mare basalts (δ⁷Li = 5.2 ± 1.2‰), with evolved LaPaz mare basalts having high Li contents, but similar low δ⁷Li (3.7 ± 0.5‰) to Apollo 15 mare basalts. In low‐Ti mare basalt 15555, the highest concentrations of Li occur in late‐stage tridymite (>20 ppm) and plagioclase (11 ± 3 ppm), with olivine (6.1 ± 3.8 ppm), pyroxene (4.2 ± 1.6 ppm), and ilmenite (0.8 ± 0.7 ppm) having lower Li concentrations. Values of δ⁷Li in low‐ and high‐Ti mare basalt sources broadly correlate negatively with ¹⁸O/¹⁶O and positively with ⁵⁶Fe/⁵⁴Fe (low‐Ti: δ⁷Li ≤4‰; δ⁵⁶Fe ≤0.04‰; δ¹⁸O ≥5.7‰; high‐Ti: δ⁷Li >6‰; δ⁵⁶Fe >0.18‰; δ¹⁸O <5.4‰). Lithium does not appear to have acted as a volatile element during planetary formation, with subequal Li contents in mare basalts compared with terrestrial, martian, or vestan basaltic rocks. Observed Li isotopic fractionations in mare basalts can potentially be explained through large‐degree, high‐temperature igneous differentiation of their source regions. Progressive magma ocean crystallization led to enrichment in Li and δ⁷Li in late‐stage liquids, probably as a consequence of preferential retention of ⁷Li and Li in the melt relative to crystallizing solids. Lithium isotopic fractionation has not been observed during extensive differentiation in terrestrial magmatic systems and may only be recognizable during extensive planetary magmatic differentiation under volatile‐poor conditions, as expected for the lunar magma ocean. Our new analyses of chondrites show that they have δ⁷Li ranging between ?2.5‰ and 4‰. The higher δ⁷Li in planetary basalts than in the compilation of chondrites (2.1 ± 1.3‰) demonstrates that differentiated planetary basalts are, on average, isotopically heavier than most chondrites.  相似文献