地震短临预报困境的思考     

王付良  李彦堂  姬志勇  韩强  张磊 《华北地震科学》2007,25(3):34-36

我国地震工作者长期的探索与努力,证明了地震短临预报是有可能做到的.但地震的复杂性决定了前兆信息的复杂性,使得我们的地震短临预报面临着一些困境,我们对此进行了一些思考.  相似文献   

Mid‐MIS3 climate inferred from reconstructing the Dalijia Shan ice cap,north‐eastern Tibetan Plateau          下载免费PDF全文

JIE WANG  HANG CUI  JONATHAN M. HARBOR  LIMIN ZHENG  PAN YAO 《第四纪科学杂志》2015,30(6):558-568

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Lateglacial cryptotephra detected within clay varves in Östergötland,south‐east Sweden          下载免费PDF全文

A. MACLEOD  L. BRUNNBERG  S. WASTEGÅRD  T. HANG  I. P. MATTHEWS 《第四纪科学杂志》2014,29(7):605-609

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The First Observed Cloud Echoes and Microphysical Parameter Retrievals by China's 94-GHz Cloud Radar   总被引：1，自引：0，他引：1       下载免费PDF全文

WU Juxiu  WEI Ming  HANG Xin  ZHOU Jie  ZHANG Peichang  LI Nan 《Acta Meteorologica Sinica》2014,28(3):430-443

By using the cloud echoes first successfully observed by China's indigenous 94-GHz SKY cloud radar, the macrostructure and microphysical properties of drizzling stratocumulus clouds in Anhui Province on 8 June2013 are analyzed, and the detection capability of this cloud radar is discussed. The results are as follows.(1) The cloud radar is able to observe the time-varying macroscopic and microphysical parameters of clouds,and it can reveal the microscopic structure and small-scale changes of clouds.(2) The velocity spectral width of cloud droplets is small, but the spectral width of the cloud containing both cloud droplets and drizzle is large. When the spectral width is more than 0.4 m s-1, the radar reflectivity factor is larger(over –10 dBZ).(3) The radar's sensitivity is comparatively higher because the minimum radar reflectivity factor is about–35 dBZ in this experiment, which exceeds the threshold for detecting the linear depolarized ratio(LDR) of stratocumulus(commonly –11 to –14 dBZ; decreases with increasing turbulence).(4) After distinguishing of cloud droplets from drizzle, cloud liquid water content and particle effective radius are retrieved. The liquid water content of drizzle is lower than that of cloud droplets at the same radar reflectivity factor.  相似文献   

制备条件对聚乙烯醇-壳聚糖凝胶性能的影响   总被引：1，自引：0，他引：1  

温燕梅  李思东  钟杰平  章超桦  梁泽萍 《广东海洋大学学报》2007,27(4):74-77

以戊二醛为交联剂,由聚乙烯醇(PVA)和壳聚糖(CTS)混合交联得到一种水凝胶,考察了聚乙烯醇和壳聚糖的配比、交联剂用量和反应时间对聚乙烯醇/壳聚糖凝胶吸水率的影响。通过单因素实验,得出了聚乙烯醇/壳聚糖凝胶具有最佳溶胀性能时的条件:聚乙烯醇与壳聚糖的摩尔比为6∶1,交联剂戊二醛的体积分数为0.05%,反应时间9h。测定了该凝胶在不同pH值下的吸水率和吸附铜离子的性能,得出聚乙烯醇/壳聚糖凝胶在酸性介质的吸水率远远大于碱性介质,对铜离子(Cu2+)的吸附量比壳聚糖凝胶提高了33.7%,因此该凝胶吸附剂在工业废水处理重金属离子方面具有一定的优越性。  相似文献   

First discovery of cryptotephra in Holocene peat deposits of Estonia, eastern Baltic     

TIIT HANG  STEFAN WASTEGÅRD  SIIM VESKI  ATKO HEINSALU 《Boreas: An International Journal of Quaternary Research》2006,35(4):644-649

This article reports the first discovery of middle Holocene cryptotephra from a peat sequence in Estonia, eastern Baltic. Two sequences, Mustjärve and Parika (located 110 km apart), were chosen for a pilot study aimed at finding traces of tephra fallout during the middle Holocene. Peat accumulation at both sites started in the early Holocene (c. 9500–9000 ¹⁴C yr BP; c . 11 000–10000 cal. yr BP) and continued throughout the whole Holocene. The radiocarbon-dated intervals between c. 2000 and 5000 ¹⁴C yr BP (c. 2000–5500 cal. yr BP) were chosen from both sites for the study. Colourless tephra shards were identified at 312–316 cm below the peat surface in the Mustjärve peat sequence, while no tephra was found in peat of the same age at Parika. Electron microprobe analyses suggest a correlation with the initial phase of the Hekla-4 eruption (c. 4260 cal. yr BP), although the age-depth model indicated an age around 4900 cal. yr BP. Small concentrations of colourless to light brown tephra shards at 266–270 cm in the Mustjärve sequence indicate that the Kebister tephra (c. 3750 cal. yr BP) might also be present, but geochemical analyses were not possible. The low concentration and small size of the tephra particles indicate that Estonian bogs are probably on the verge of where tephrochronology is possible in northwestern Europe. Further studies of full Holocene sequences are required in order to discover traces of other ash plumes reaching as far east as the eastern Baltic area.  相似文献   

Correlation of stadial and interstadial events in the south Swedish glacial varves with the GRIP oxygen isotope record     

BERTIL RINGBERG  JONAS BJÖRCK  TIIT HANG 《Boreas: An International Journal of Quaternary Research》2003,32(2):427-435

A number of correlated varve sequences from the local varve chronology in southeastern Sweden have been selected to make a 1040 varve years long mean varve thickness curve. Pollen analyses were carried out over an interval of 373 varve years in the northern part of the study area. The pollen stratigraphical data have been divided into local pollen assemblage zones which have been correlated with the radiocarbon-dated regional pollen assemblage zones. Based on variations in herb and tree pollen content of the analysed varve sequences, it has been possible to identify well-documented lateglacial pollen zones for southern Sweden, i.e. the Bölling interstadial (GI-1e), the Older Dryas cold event (GI-1d) and the early part of the Alleröd interstadial (GI-1c). The event stratigraphy in this study, based on varying varve thicknesses and the composition of the pollen flora in the varves, has been correlated with the oxygen isotope stratigraphy of the GRIP ice-core on Greenland between 13600 and 14400 GRIP ice-core years BP. It is concluded that five decadal warm events and one centennial warm event (15–60 and 100 varve years long, respectively) occur in the clay varve record along with one centennial cold event (150 varve years long), the Older Dryas (GI-1d).  相似文献   

天水地区近50年气温与降水变化特征   总被引：8，自引：1，他引：7  

胡利平  姚延锋  裴古娥  安晶  袁雅萍  杭波 《地理科学进展》2009,28(4)

根据1961-2006年天水7个站每月温度和降水资料,分析了近50a天水温度和降水的突变事实。在此基础上给出了气候变暖前后气温、降水的概率分布,比较了变暖前后时段天水气温、降水空间分布的差异。结果表明:1)20世纪90年代初期天水气温、降水发生了明显突变,进入温度显著增暖和降水偏少时段;2)增暖后天水气温和降水的概率分布发生了明显变化,气温偏冷的概率显著减小,偏暖的概率显著增大;降水偏少的概率明显增多,偏多的概率明显减少;3)气候变暖后天水地区和各气候分区气温上升幅度均较显著;降水距平百分率渭北区下降幅度相对突出。进而,讨论了温度增加和降水减少对该地区农业生产的影响。  相似文献   

印尼塔里阿布岛铁矿项目岩心钻探施工技术          下载免费PDF全文

杭程 《探矿工程》2012,39(1):25-28

在印尼塔里阿布铁矿项目岩心钻探施工中,其地层既具有泥岩、页岩、粘土岩的遇水膨胀、坍塌,又有凝灰岩、火山灰岩的遇水溶解及硅化石英岩的“打滑”,以及粉状铁矿取心难的特点。易出现卡钻、粘钻等孔内事故。通过大胆的探索,形成了针对该地区岩心钻探施工的一套施工工艺,取得了良好的钻探技术效果。详细介绍了印尼塔里阿布岛铁矿项目岩心钻探施工技术。  相似文献   

我国不同气候带黄土中粘土矿物组合特征分析   总被引：11，自引：1，他引：10  

师育新  戴雪荣  宋之光  张卫国  王立群 《沉积学报》2005,23(4):690-695

在兰州黄土和下蜀黄土中粘土矿物的X衍射分析基础上,对我国不同纬度和气候带的五个黄土剖面(点)中的粘土矿物组合和空间分布进行了对比分析,并探讨了与古气候的关系。结果表明,黄土中粘土矿物组合具有明显的地带性特征。从西北到东南,随着纬度的逐渐降低,黄土中的粘土矿物组合也发生有规律的变化。主要表现为绿泥石含量的逐渐减少和蛭石含量的逐渐增多。位于温带半干旱区的兰州黄土以伊利石和绿泥石为主要粘土矿物,而位于亚热带湿润区的大港下蜀黄土则以伊利石和蛭石为主要粘土矿物。黄土中含有较多量的绿泥石可作为黄土母质堆积后干冷气候和微弱风化的标志,而蛭石和蛭石/绿泥石混层矿物含量的增加指示了风化强度的增强。因此,黄土粘土矿物组合特征不仅反映物源区古环境信息,而且指示了黄土堆积期后的生物气候环境。  相似文献