基于VMD和LSTM方法的北京市PM2.5短期预测     

秦喜文  王强进  王新民  郭佳静  初晓 《吉林大学学报(地球科学版)》2022,52(1):214-221

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基于数据产品的风廓线雷达故障识别   总被引：1，自引：0，他引：1  

李昭春  周红根  朱毅  周良  丁仁惠  储俊 《气象科技》2019,47(5):757-767

风廓线雷达是一种以大气湍流为主要探测对象的晴空测风设备,近年来普遍使用。其资料的应用广泛,对数据产品的可用性要求越来越高。本文以1456D/F型两种布网风廓线雷达为研究对象,收集了22个产品异常个例,并对其进行了分类,分析了数据产品产生异常的原因;基于数据产品异常,总结出识别与分析风廓线雷达故障的经验方法及排查流程。有利于提高省级、台站业务人员识别风廓线雷达异常数据产品的能力,有效保障数据的正常采集与上传,从而为预报服务提供更准确的探测数据。  相似文献   

国外城市地质工作进展与趋势及其对我国的启示   总被引：1，自引：0，他引：1  

吕敦玉  余楚  侯宏冰  刘长礼  张云 《现代地质》2015,(2):466-473

城市化是世界各国发展的共同趋势,是人类文明和进步的标志。我国城市化的趋势与世界总趋势一致,因此弄清国外城市地质工作进展与趋势对我国城市地质工作的开展具有重要意义。首先对城市地质的定义、内涵、任务、工作内容进行了总结与阐述,接着对国外发达国家近百年来开展的主要城市地质工作内容、思路、技术方法进行梳理和总结。在此基础上,从城市地质的理论研究、工作重点、技术方法、信息系统、工作深度、机制建设等方面,分析未来城市地质工作的发展趋势。最后,结合我国地质工作现状和发展历程,对我国未来城市地质工作的重点、内容、研究层次进行了探讨,以期为我国正处于加速发展阶段的城市化进程提供有效建议和支持。  相似文献   

A Comprehensive Method for Precise Determination of Re,Os, Ir,Ru, Pt,Pd Concentrations and Os Isotopic Compositions in Geological Samples   总被引：2，自引：0，他引：2       下载免费PDF全文

Zhuyin Chu  Yan Yan  Zhi Chen  Jinghui Guo  Yueheng Yang  Chaofeng Li  Yanbin Zhang 《Geostandards and Geoanalytical Research》2015,39(2):151-169

A comprehensive method for the precise determination of Re, Os, Ir, Ru, Pt and Pd concentrations as well as Os isotopic compositions in geological samples is presented. Samples were digested by the Carius tube method, and the Os was extracted by conventional CCl₄ method. The Re, Ir, Ru, Pt and Pd were first subgroup separated from the matrix elements into Re‐Ru, Ir‐Pt and Pd by a 2‐ml anion exchange column. Subsequently, the Re‐Ru was further purified by a secondary 0.25 ml anion exchange column or by microdistillation of Ru using CrO₃‐H₂SO₄ as an oxidant followed by a secondary 0.25 ml anion exchange separation of Re. The Pd and Ir‐Pt were further successively purified by an Eichrom‐LN column to completely remove Zr and Hf, respectively. Rhenium, Ir, Ru, Pt and Pd were individually measured by multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS), except for Ru after microdistillation purification was analysed by negative‐thermal ionisation mass spectrometry (N‐TIMS). The analytical results for peridotite reference material WPR‐1 agree well with the previously published data. Finally, several mafic rock reference materials including TDB‐1, WGB‐1, BHVO‐2, BCR‐2, BIR‐1a and DNC‐1a were analysed for Re‐Os isotopes and platinum‐group element concentrations to test their suitability for certification.  相似文献   

Rhenium-osmium isotope and platinum-group elements in the Xinjie layered intrusion, SW China: Implications for source mantle composition, mantle evolution, PGE fractionation and mineralization   总被引：2，自引：0，他引：2  

Hong Zhong  Liang Qi  Mei-Fu Zhou  Wei-Guang Zhu  Zhu-Yin Chu 《Geochimica et cosmochimica acta》2011,75(6):1621-6741

The Xinjie mafic-ultramafic layered intrusion in the Emeishan large igneous province (ELIP) hosts Cu-Ni-platinum group element (PGE) sulfide ore layers within the lower part and Fe-Ti-V oxide-bearing horizons within the middle part. The major magmatic Cu-Ni-PGE sulfide ores and spatially associated cumulate rocks are examined for their PGE contents and Re-Os isotopic systematics. The samples yielded a Re-Os isochron with an age of 262 ± 27 Ma and an initial ¹⁸⁷Os/¹⁸⁸Os of 0.12460 ± 0.00011 (γ_Os(t) = −0.5 ± 0.1). The age is in good agreement with the previously reported U-Pb zircon age, indicating that the Re-Os system remained closed for most samples since the intrusion emplacement. They have near-chondritic γ_Os(t) values ranging from −0.7 to −0.2, similar to those of the Lijiang picrites and Song Da komatiites. Exceptionally, two samples from the roof zone and one from upper sequence exhibit radiogenic γ_Os(t) values (+0.6 to +8.6), showing minor contamination by the overlying Emeishan basalts.The PGE-rich ores contain relatively high PGE and small amounts of sulfides (generally less than 2%) and the abundance of Cu and PGE correlate well with S, implying that the distribution of these elements is controlled by the segregation and accumulation of a sulfide liquid. Some ore samples are poor in S (mostly <800 ppm), which may due to late-stage S loss caused by the dissolution of FeS from pre-existing sulfides through their interaction with sulfide-unsaturated flowing magma. The combined study shows that the Xinjie intrusion may be derived from ferropicritic magmas. The sharp reversals in Mg#, Cr/FeO_T and Cr/TiO₂ ratios immediately below Units 2-4, together with high Cu/Zr ratios decreasing from each PGE ore layer within these cyclic units, are consistent with multiple magma replenishment episodes. The sulfides in the cumulate rocks show little evidence of PGE depletion with height and thus appear to have segregated from successive inputs of fertile magma. This suggests that the Xinjie intrusion crystallized from in an open magma system, e.g., a magma conduit. The compositions of the disseminated sulfides in most samples can be modeled by applying an R factor (silicate-sulfide mass ratio) of between 1000 and 8000, indicating the segregation of only small amounts of sulfide liquid in the parental ferropicritic magmas. Thus, continuous mixing between primitive ferropicritic magma and differentiated resident magma could lead to crystallization of chromite, Cr-bearing magnetite and subsequently abundant Fe-Ti oxides, thereby the segregation of PGE-rich Cu-sulfide.When considered in the light of previous studies on plume-derived komatiites and picrites worldwide, the close-to-chondritic Os isotopic composition for most Xinjie samples, Lijiang picrites and Song Da komatiites suggest that the ferropicritic magma in the ELIP were generated from a plume. This comprised recycled Neoproterozic oceanic lithosphere, including depleted peridotite mantle embedded with geochemically enriched domains. The ascending magmas thereafter interacted with minor (possibly <10%) subducted/altered oceanic crust. This comparison suggests that the komatiitic melts in the ELIP originated from a greater-than normal degree of melting of incompatible trace element depleted, refractory mantle components in the plume source.  相似文献   

Strength failure of spatial reticulated structures under multi-support excitation     

Jihong Ye  Zhiqiang Zhang  Ye Chu 《地震工程与工程振动(英文版)》2011,10(1):21-36

Under strong earthquakes, long-span spatial latticed structures may collapse due to dynamic instability or strength failure. The elasto-plastic dynamic behaviors of three spatial latticed structures, including two double-layer cylindrical shells and one spherical shell constructed for the 2008 Olympic Games in Beijing, were quantitatively examined under multi-support excitation (MSE) and uniform support excitation (USE). In the numerical analyses, several important parameters were investigated such as the peak acceleration and displacement responses at key joints, the number and distribution of plastic members, and the deformation of the shell at the moment of collapse. Analysis results reveal the features and the failure mechanism of the spatial latticed structures under MSE and USE. In both scenarios, the double-layer reticulated shell collapses in the "overflow" mode, and the collapse is governed by the number of invalid plastic members rather than the total number of plastic members, beginning with damage to some of the local regions near the supports. By comparing the numbers and distributions of the plastic members under MSE to those under USE, it was observed that the plastic members spread more sufficiently and the internal forces are more uniform under MSE, especially in cases of lower apparent velocities in soils. Due to the effects of pseudo-static displacement, the stresses in the members near the supports under MSE are higher than those under USE.  相似文献   

豫西雷门沟斑岩钼矿床成矿流体特征及其地质意义   总被引：1，自引：0，他引：1  

陈小丹  叶会寿  毛景文  汪欢  褚松涛  程国祥  刘彦伟 《地质学报》2011,85(10):1629-1643

豫西雷门沟钼矿床位于东秦岭钼矿带东段,是区内典型的斑岩型钼矿床之一.矿体主要分布于花岗斑岩与围岩新太古界太华群片麻岩的内外接触带中,呈透镜状、似层状产出.矿化类型主要有浸染状和细脉-网脉状.根据矿脉穿切关系,将热液成矿过程划分为4个阶段:Ⅰ)面型钾长石化阶段,Ⅱ)石英-钾长石阶段,Ⅲ)石英-辉钼矿-硫化物阶段,Ⅳ)石英...  相似文献   

广州地铁沉降监测方法及数据处理     

刘建廷  李东辉 《地理空间信息》2011,9(2):122-124

广州是轨道交通工程在建项目较多的城市,沉降监测对地铁工程的安全施工有着重要意义,同时监测数据能够直接用来评价地铁施工对地表环境的影响.重点论述了广州地铁沉降监测的方法与技术要求,阐述了数据处理和统计分析;并给出了变形预报分析的数学方法,说明了其现实意义.  相似文献   

Phytoplankton distribution and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam)     

Rochelle-Newall EJ  Chu VT  Pringault O  Amouroux D  Arfi R  Bettarel Y  Bouvier T  Bouvier C  Got P  Nguyen TM  Mari X  Navarro P  Duong TN  Cao TT  Pham TT  Ouillon S  Torréton JP 《Marine pollution bulletin》2011,62(11):2317-2329

Phytoplankton diversity, primary and bacterial production, nutrients and metallic contaminants were measured during the wet season (July) and dry season (March) in the Bach Dang Estuary, a sub-estuary of the Red River system, Northern Vietnam. Using canonical correspondence analysis we show that phytoplankton community structure is potentially influenced by both organometallic species (Hg and Sn) and inorganic metal (Hg) concentrations. During March, dissolved methylmercury and inorganic mercury were important factors for determining phytoplankton community composition at most of the stations. In contrast, during July, low salinity phytoplankton community composition was associated with particulate methylmercury concentrations, whereas phytoplankton community composition in the higher salinity stations was more related to dissolved inorganic mercury and dissolved mono and tributyltin concentrations. These results highlight the importance of taking into account factors other than light and nutrients, such as eco-toxic heavy metals, in understanding phytoplankton diversity and activity in estuarine ecosystems.  相似文献   

Electron-positron annihilation lines and decaying sterile neutrinos     

M. H. Chan  M.-C. Chu 《Astrophysics and Space Science》2012,338(2):313-317

If massive sterile neutrinos exist, their decays into photons and/or electron-positron pairs may give rise to observable consequences. We consider the possibility that MeV sterile neutrino decays lead to the diffuse positron annihilation line in the Milky Way center, and we thus obtain bounds on the sterile neutrino decay rate Γ _e ≥10⁻²⁸ s⁻¹ from relevant astrophysical/cosmological data. Also, we expect a soft gamma flux of 1.2×10⁻⁴–9.7×10⁻⁴ ph cm⁻² s⁻¹ from the Milky Way center which shows up as a small MeV bump in the background photon spectrum. Furthermore, we estimate the flux of active neutrinos produced by sterile neutrino decays to be 0.02–0.1 cm⁻² s⁻¹ passing through the earth.  相似文献