GeoImageDB 多分辨率无缝影像数据库系统的开发与实现     

方涛  李德仁  龚健雅  皮明红 《武汉大学学报(信息科学版)》1999,24(3):08

介绍了已开发实现的ＧｅｏＩｍ ａｇｅＤＢＶ２．０ 系统的组织、压缩与拼接,基于分布式的存储与管理,多尺度、跨工程、跨工作区任意分辨率影像数据空间索引与调度,与 ＧｅｏＳｔａｒ、ＧｅｏＧｒｉｄ 的集成,支持国家影像空间数据交换标准与输出等的基本原理、主要功能和特色。  相似文献   

Changes of snow cover in Poland   总被引：2，自引：2，他引：0  

Małgorzata Szwed  Iwona Pińskwar  Zbigniew W. Kundzewicz  Dariusz Graczyk  Abdelkader Mezghani 《Acta Geophysica》2017,65(1):65-76

The present paper examines variability of characteristics of snow cover (snow cover depth, number of days with snow cover and dates of beginning and end of snow cover) in Poland. The study makes use of a set of 43 long time series of observation records from the stations in Poland, from 1952 to 2013. To describe temporal changes in snow cover characteristics, the intervals of 1952–1990 and of 1991–2013 are compared and trends in analysed data are sought (e.g., using the Mann–Kendall test). Observed behaviour of time series of snow-related variables is complex and not easy to interpret, for instance because of the location of the research area in the zone of transitional moderate climate, where strong variability of climate events is one of the main attributes. A statistical link between the North Atlantic Oscillation (NAO) index and the snow cover depth, as well as the number of snow cover days is found.  相似文献   

Estimation of large wood budgets in a watershed and river corridor at interdecadal to interannual scales in a cold‐temperate fluvial system          下载免费PDF全文

Maxime Boivin  Thomas Buffin‐Bélanger  Hervé Piégay 《地球表面变化过程与地形》2017,42(13):2199-2213

Large wood (LW) is a ubiquitous feature in rivers of forested watersheds worldwide, and its importance for river diversity has been recognized for several decades. Although the role of LW in fluvial dynamics has been extensively documented, there is a need to better quantify the most significant components of LW budgets at the river scale. The purpose of our study was to quantify each component (input, accumulation, and output) of a LW budget at the reach and watershed scales for different time periods (i.e. a 50‐year period, decadal cycle, and interannual cycle). The LW budget was quantified by measuring the volumes of LW inputs, accumulations, and outputs within river sections that were finally evacuated from the watershed. The study site included three unusually large but natural wood rafts in the delta of the Saint‐Jean River (SJR; Québec, Canada) that have accumulated all LW exported from the watershed for the last 50 years. We observed an increase in fluvial dynamics since 2004, which led to larger LW recruitment and a greater LW volume trapped in the river corridor, suggesting that the system is not in equilibrium in terms of the wood budget but is rather recovering from previous human pressures as well as adjusting to hydroclimatic changes. The results reveal the large variability in the LW budget dynamics during the 50‐year period and allow us to examine the eco‐hydromorphological trajectory that highlights key variables (discharge, erosion rates, bar surface area, sinuosity, wood mobility, and wood retention). Knowledge on the dynamics of these variables improves our understanding of the historical and future trajectories of LW dynamics and fluvial dynamics in gravel‐bed rivers. Extreme events (flood and ice‐melt) significantly contribute to LW dynamics in the SJR river system. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Reappraisal of the GL‐O Reference Material for K‐Ar Dating: New Insight from Microanalysis,Single‐Grain and Milligram Ar Measurements     

Thomas Boulesteix  Jesús Sol  Teresa Pi  Michel Cathelineau 《Geostandards and Geoanalytical Research》2020,44(2):287-306

The homogeneity and Ar‐dating suitability of the GL‐O reference material were re‐evaluated to determine whether this material is sufficiently homogeneous to be suitable for the calibration of modern high sensitivity instruments. Based on new micro‐analyses and noble gas determinations, our contribution reveals several kinds of inhomogeneity at the grain scale: disparity in the glauconitisation among and within the pellets, variable occurrence of a phosphatic component within pellets (1% m/m on average), and rare occurrences of calcite and detrital grains. Measurements on test portions of ≤ 1 mg reflect such heterogeneity with variability in ⁴⁰Ar* content that exceeds analytical uncertainty, including a few highly anomalous values. The lesser evolved glauconite population yielded ⁴⁰Ar* contents ~ 15% lower than the value of 24.8 nl g^?1 recommended by Odin et al. (1982, Numerical dating in stratigraphy. Wiley (Chichester, UK), 123–148). But the measured concentrations of ⁴⁰Ar* converge towards the aforementioned value as test portion mass increased to > 3 mg. A few rare 3 mg experiments still yielded ⁴⁰Ar* contents lower than the recommended value (down to 24.0 nl g^?1), and we recommend using more conservative minimum masses of 5–10 mg. A further purification step for GL‐O or the intercalibration of its powder version could be considered to diminish the size of the test portions and the intensity of the measured signals.  相似文献   

枣庄矿区采煤塌陷现状及防治对策   总被引：1，自引：0，他引：1       下载免费PDF全文

皮士然 《山东国土资源》2005,21(4):15-16,18

枣庄矿区由枣陶煤田、官桥煤田、滕南煤田、滕北煤田、滕东煤田和韩台煤田组成。已探明煤炭地质储量45亿吨,含煤面积1046．7km^2,占枣庄市土地总面积的23％,其中已开采240km^2。现有国家统配矿井8座,地方矿井69座,已形成年产1800万t的规模。煤矿的开发利用,支援了国家的建设与发展,也使枣庄成为新兴的矿业城市,但同时,也对枣庄自然生态环境,  相似文献   

Cataclysmic variables based on the stellar spectral survey LAMOST DR3     

Xianming L.Han  Li-Yun Zhang  Jian-Rong Shi  Qing-Feng Pi  Hong-Peng Lu  Li-Bo Zhao  Rachel K.Terheide  Lin-Yang Jiang 《天文和天体物理学研究(英文版)》2018,(6)

Big data in the form of stellar spectra from the spectroscopic survey associated with the Large Sky Area Multi-object Fiber Spectroscopic Telescope(LAMOST) are important for studying properties of cataclysmic variables(CVs). By cross matching the catalogs of CVs compiled with LAMOST DR3,acquired from October 2011 to July 2015, we obtained the first spectroscopic catalog for CVs observed by LAMOST with high signal to noise ratio, above 8. By integrating line profiles, their equivalent widths(EWs) of the Hα, Hβ, Hγ and Hδ, as well as He I 5876 and 6678 A? lines, were calculated. There were74 stellar spectra from 48 known CVs and three spectra from three new CV candidates. At the same time, we also collected their previously published EWs. Thirty-three objects had repeated spectra and30 stars showed spectral variability in the Hα line. Moreover, we carried out photometric follow-up studies for five CVs(UU Aqr, TT Tri, PX And, BP Lyn and RW Tri). We obtained nine new light curves and revised their linear ephemerides. For RW Tri, there is a possible oscillation with an amplitude of0.0031(2) days and a period of 47.6±0.4 years, which might be caused by a third body(brown dwarf)or magnetic activity cycle.  相似文献   

中全新世以来南黄海中部沉积过程——基于岩心粒度和有机质指标     

皮仲  李铁刚  类彦立 《海洋学报》2019,41(11):75-88

海陆交互作用下的南黄海沉积环境复杂,其沉积机制一直是古海洋研究的重点和难点。本文以取自南黄海中部泥质区的Z1岩心为载体,对196个样品的粒度和整体有机质指标(TOC、TN、TOC/TN和δ13Corg)进行了详细分析,并对5个层位进行AMS14C年龄测定,分辨率高达11 a/cm。研究结果显示,6.1 ka BP以来南黄海中部沉积过程可分为3个阶段:(1) 6.1～5.2 ka BP,沉积物粒度较粗,以残留砂和陆源粗粒物质为主,有机质含量较低且主要为陆源输入,本阶段多受东亚季风强盛的影响,动荡海洋环境下有机质保存效率低,大量陆源输入冲淡作用显著;(2) 5.2～3.9 ka BP,沉积物粒度变细且波动较大,有机质呈增加趋势且以海源为主,主要受东亚冬季风减弱的影响,海源有机质含量增加,与黄海暖流影响增强有关;(3) 3.9～0 ka BP,沉积物粒度最细且相对稳定,有机质含量继续增加,直至1.9 ka BP趋于稳定,主要受现代环流系统和东亚冬季风影响。结果表明,南黄海粒度和整体有机质指标变化过程复杂,显示中全新世以来南黄海中部泥质区沉积环境演化的复杂性。本研究获得了南黄海高分辨率的沉积环境演化记录,不仅为沉积机制研究提供更多数据支撑,还可为区域古气候和古海洋演化提供关键的指示证据。  相似文献