排序方式: 共有32条查询结果,搜索用时 16 毫秒
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多尺度数据的有效组织与管理是实现三维建筑自动综合及多尺度应用的基础。本文对空间数据综合与多尺度表达数据管理方法的研究现状进行了分析。根据三维建筑自动综合的特点,本文提出了一种基于R树的多尺度三维建筑空间索引模型——GAMR树(Generalization Area Multi-representation R Tree);对GAMR树的定义和结构进行了详细描述,设计了顾及GAMR树高度与所选长度阈值关联关系的索引构建方法。针对三维建筑特点,设计了一种支持多尺度区域对象完整查询的检索方法,并根据建筑特征的可辨性,实现了顾及视线角度对投影长度影响的三维建筑模型多尺度可视化方法。实验证明,GAMR树能很好地适用于三维建筑多尺度模型的组织与管理,对三维建筑几何模型的自动综合具有重要意义。 相似文献
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Ichiro Yoshikawa Junya Ono Go Murakami Shingo Kameda 《Planetary and Space Science》2008,56(13):1676-1680
A rare, but normal, astronomical event occurred on November 9th 2006 (JST) as Mercury passed in front of the Sun from the perspective of the Earth. The abundance of the sodium vapor above the planet limb was observed by detecting an excess absorption in the solar sodium line D1 during this event. The observation was performed with a 10-m spectrograph of Czerny-Turnar system at Domeless Solar Tower Telescope at the Hida Observatory in Japan. The excess absorption was red-shifted by 10 pm relative to the solar line, and was measured at the dawnside (eastside) and duskside (westside) of Mercury. Between the dawn and dusksides, an asymmetry of total sodium abundance was clearly identified. At the dawnside, the total sodium column density was 6.1×1010 Na atoms/cm2, while it was 4.1×1010 Na atoms/cm2 at the duskside. The investigation of dawn-dusk asymmetry of the sodium exosphere of Mercury is a clue to understand the release mechanism of sodium from the surface rock. Our result suggests that a thermal desorption is a main source process for sodium vapor in the vicinity of Mercury. 相似文献
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Zhang Rong-Hua Yu Yongqiang Song Zhenya Ren Hong-Li Tang Youmin Qiao Fangli Wu Tongwen Gao Chuan Hu Junya Tian Feng Zhu Yuchao Chen Lin Liu Hailong Lin Pengfei Wu Fanghua Wang Lin 《中国海洋湖沼学报》2020,38(4):930-961
El Nino-Southern Oscillation(ENSO) is the strongest interannual signal that is producedby basinscale processes in the tropical Pacific,with significant effects on weather and climate worldwide.In the past,extensive and intensive international efforts have been devoted to coupled model developments for ENSO studies.A hierarchy of coupled ocean-atmo sphere models has been formulated;in terms of their complexity,they can be categorized into intermediate coupled models(ICMs),hybrid coupled models(HCMs),and fully coupled general circulation models(CGCMs).ENSO modeling has made significant progress over the past decades,reaching a stage where coupled models can now be used to successfully predict ENSO events 6 months to one year in advance.Meanwhile,ENSO exhibits great diversity and complexity as observed in nature,which still cannot be adequately captured by current state-of-the-art coupled models,presenting a challenge to ENSO modeling.We primarily reviewed the long-term efforts in ENSO modeling continually and steadily made at different institutions in China;some selected representative examples are presented here to review the current status of ENSO model developments and applications,which have been actively pursued with noticeable progress being made recently.As ENSO simulations are very sensitive to model formulations and process representations etc.,dedicated efforts have been devoted to ENSO model developments and improvements.Now,different ocean-atmosphere coupled models have been available in China,which exhibit good model performances and have already had a variety of applications to climate modeling,including the Coupled Model Intercomparison Project Phase 6(CMIP6).Nevertheless,large biases and uncertainties still exist in ENSO simulations and predictions,and there are clear rooms for their improvements,which are still an active area of researches and applications.Here,model performances of ENSO simulations are assessed in terms of advantages and disadvantages with these differently formulated coupled models,pinpointing to the areas where they need to be further improved for ENSO studies.These analyses provide valuable guidance for future improvements in ENSO simulations and predictions. 相似文献
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Journal of Oceanology and Limnology - Based on initial errors of sea temperature in the tropical Indian Ocean that are most likely to induce spring predictability barrier (SPB) for the El Niño... 相似文献
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Osama Eljamal Junya Okawauchi Kazuaki Hiramatsu Masayoshi Harada 《Environmental Earth Sciences》2013,68(3):859-863
The sorption of phosphorus by using four different natural materials (marble dust, sawdust, soil, and rice husk) was studied by conducting batch tests and kinetic sorption model. The kinetic sorption model based on a pseudo equation was applied to predict the rate constant of sorption. Thorough investigations to understand the mechanism of phosphorus sorption onto the natural materials using kinetic sorption models, pseudo first- and second-order kinetic sorption model showed that the kinetic sorption is consistent with the second-order model, from which it can be inferred that the mechanism of sorption is chemisorption. Batch tests and kinetic sorption model results showed that by using marble dust as sorbent, among other materials, could remove more than 93 % of phosphorus from aqueous solution. 相似文献
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贵州乐康二叠/三叠系界线剖面的有机碳同位素异常及其意义 总被引:6,自引:0,他引:6
本文研究了贵州望谟乐康深水槽谷相二叠/三叠系界线剖面的有机碳同位素记录。研究结果表明,乐康剖面上二叠统δ13Corg值的变化幅度不大,越过第34层进入第35层以后,在WL-16号样品层位上,δ13Corg值突然从WL-15号样品的-25.419‰降低到-28.235‰,衰减幅度达到近3‰;其后δ13Corg值逐渐回升,并进入下三叠统。根据δ13Corg值的突然衰减正好发生在第34,35层的界线过渡层内这一事实,我们认为乐康剖面的P/T界线应划在第35层的WL-16号样品层位上。由于沉积有机物的碳同位素组成与海洋生物原始生产率(primaryproductivity)密切相关,因此,贵州乐康二叠/三叠系界线剖面的有机碳同位素变化曲线,不仅可以作为精确划分地层界线的一种新的有效手段,而且反映了海洋原始生产率的变化情况。 相似文献
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Towhata Ikuo Goto Satoshi Goto Shigeru Akima Takeshi Tanaka Junya Uchimura Taro Wang Gonghui Yamaguchi Hiroshi Aoyama Shogo 《Natural Hazards》2021,105(1):501-530
Natural Hazards - A volcanic slope in Izu Oshima Island in Japan experienced a profound rain-induced disaster in October 2013. Since this slope had been stable for centuries except for minor... 相似文献
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南君亚 《沉积与特提斯地质》1995,15(2):58-65
全球沉积岩数据库(简称SEDBA)在UNESCO-IGCP和IUGS支持下,由IGCP 269项目设计建成。建立SEDBA的目的是实现对全球沉积岩数据的存储、管理、检索和利用,以促进信息的国际交流和全球地质对比研究的开展。 相似文献
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Dinosaur eggshells from the Cretaceous red beds of southern China were selected for element geochemical study.The concentrations of the major elements indicate that the eggshells did not change much in their chemical composition after they were formed.Variations in the contents of trace elements and REEs imply that a palaeoclimatic anomaly might occur during Late Cretaceous. 相似文献