Radar Observations of Taurid Complex Meteor Showers in 2003: Activity and Mass Distribution     

P. Pecina  V. Porub–an  D. Pecinová  J. Toth 《Earth, Moon, and Planets》2004,95(1-4):681-688

Results of Ondřejov radar observation of Taurid complex meteor showers, i.e. ζ Perseids, β Taurids, S and N Taurids, performed in 2003, are presented. We have found some mass segregation within ζ Perseid, β Taurid and S Taurid showers. We have also established conspicuous lack of long duration echoes (with T ⩾ 3 s resp. T ⩾ 5 s) in S and N Taurid showers. The lack within remaining showers is not so pronounced but still persists.  相似文献   

3D MODEL STUDY ON FOG OVER COMPLEX TERRAIN—PART Ⅰ:NUMERICAL STUDY     

石春娥  孙学金  杨军  李子华 《Acta Meteorologica Sinica》1996,(4)

A three-dimensional fog model,suitable for precipitous and complex terrain,is designed contain-ing four prognostic variables—wind speed,potential temperature,specific humidity and mixing ratioof liquid water.The model considers turbulent exchange,the long-wave radiation on the ground sur-face and in the air.the short-wave solar radiation,the evaporation and condensation of moisture andthe surface heat budget and so on.In order to make the model run steadily on precipitous and complexterrain,we have improved the method of calculating horizontal pressure gradient force in the terraincoordinate system.The results coincide on the whole with the actual situation.  相似文献   

Oxide Mineralogy and Magnetic Properties of the Koidu Kimberlite Complex, Sierra Leone, West Africa     

S. E. Haggerty  R. B. Hargraves  L. A. Tompkins 《Geophysical Journal International》1990,100(2):275-283

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A theory of spectral analysis based on the characteristic property of a linear dynamic system   总被引：3，自引：1，他引：2  

M. Kumazawa  Y. Imanishi  Y. Fukao  M. Furumoto  A. Yamamoto 《Geophysical Journal International》1990,101(3):613-630

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鲁西铜石中生代复式岩体岩石谱系单位划分及成因   总被引：1，自引：0，他引：1       下载免费PDF全文

孔令广  甘延景 《山东国土资源》2001,17(2):23-27

铜石岩体就位于燕山早期,有五次脉动侵入活动,相应地可建立五个单元,归并为铜石超单元;岩浆末期形成细晶岩、霏细岩,热膨胀形成隐爆角砾岩、侵入角砾岩及沉陷角砾岩等.铜石岩体具有花岗岩类高位深成复式岩体特征.  相似文献   

Humic Acid and Iron Chelation Modified Anode Improves the Electrochemical Performance of Marine Sediment Microbial Fuel Cell     

FU Yubin  CHEN Jiaqi  CHEN Yan  HUANG Xiang  LI Yang  ZHANG Huaijing  ZAI Xuerong 《中国海洋大学学报(英文版)》2022,21(2):388-394

Marine sediment microbial fuel cell(MSMFCs)can be utilized as a long lasting power source to drive small instruments to work for long time on ocean floor and its higher power has a significant meaning for practical application.Anode modification can greatly improve the performance of MSMFCs.Herein,humic acid(HA)and humic acid-iron ion complex(HA-Fe)were used to modify the anode for constructing a better MSMFCs.The results indicated that HA-Fe modified anode,better than HA modification,significantly improved the MSMFCs cell power output.The maximum power density of HA-Fe modified MSMFCs is 165.3 mW m?2,which are 6.5-folds of blank MSMFCs.The number of microorganisms on anode,redox activity,and relative kinetic activity were 1.8-,6.1-,and 13.1-folds of blank MSMFCs,respectively.The MSMFCs improvement would be attributed to the electron transfer media of HA and the valence conversion of Fe ions.A synergistic interaction between the naturally occurring HA and Fe ions on the anodic surface in marine sediments would make the modified anodes have‘renewable’characteristics,which is beneficial for the MSMFCs to maintain its long-term higher power.  相似文献   

ESR/U-series chronology of the Neanderthal occupation layers at Galería de las Estatuas (Sierra de Atapuerca,Spain)     

《Quaternary Geochronology》2022

The Galería de las Estatuas is a Mousterian site located within the Cueva Mayor-Cueva del Silo karstic system at the Sierra de Atapuerca (Burgos, Spain). This site is characterised by an important Upper Pleistocene stratigraphic sequence in which a large number of lithic artefacts exhibiting clear Mousterian affinities and a rich assemblage of faunal remains have been found.Additionally, this site has yielded a foot phalanx of a clear Neanderthal affinities and its sediment has yielded Neanderthal mitochondrial and nuclear DNA.Two test pits, GE-I and GE-II, have been excavated since 2008 which have been divided in 5 and 2 lithostratigraphical units, respectively. A minimum age of 45 ka cal BP for this site was obtained by radiocarbon dating in GE-II. This chronology was refined using single-grain Optically Stimulated Luminescence (OSL: 80–112 ka in GE-I and 70–79 ka in GE-II) and single-grain thermally transferred OSL (TT-OSL). Although in all case TT-OSL ages were systematically older than their single-grain counterparts. The detrital sequence is sealed by a flowstone whose base is dated to 53.7 ± 3.5 ka cal BP using U-series dating.In order to better constrain the age of this site, nine herbivorous teeth were collected from the whole sedimentary sequence to be dated by the ESR/U-series dating method though only seven provided modelled ages. Six of them were collected from levels 2 to 5 of the GE-I test pit while the last tooth was taken from level 2 of the GE-II test pit. Our results, ranging between 80 and 110 ka, are in agreement with those obtained by single grain TT-OSL and suggest that the sedimentological levels containing Mousterian lithic artefacts and faunal and human remains began to be deposited during the second part of the MIS5. These results fill a temporal gap in the chronology of the Atapuerca sites for which no contemporary MIS5 date was obtained until recently.  相似文献   

三氯乙烯污染土壤的复电阻率特征和频谱参数研究     

张振宇  许伟伟  邓亚平  任静华  施小清  吴吉春 《地学前缘》2021,28(5):114-124

复电阻率法(complex resistivity, CR)由于其对孔隙水化学性质、固-液界面和流体含量的敏感性已成为具有良好前景的污染物识别工具。本研究选取三氯乙烯(trichloroethylene, TCE)作为典型有机污染物,利用频谱激电仪对TCE污染土壤进行了复电阻率测量,讨论孔隙水盐度、水饱和度和土壤类型对污染土壤的复电阻率特征和频谱参数影响。试验结果表明:污染土样的复电阻率均随水饱和度的降低和孔隙水盐度的减小而增大;土壤黏土含量影响孔隙水连续性,当孔隙水出现不连续状态时,实部和虚部出现大幅度变化。总充电率M随着孔隙水盐度的增加而增加,随水饱和度的降低先减后增。黏土颗粒重排导致的比表面积减小使得总充电率M减小,双电层极化加强使总充电率M升高;平均弛豫时间常数随孔隙水盐度的升高而降低,二者呈对数相关,随水饱和度变化的主要原因为可极化孔隙尺寸的变化。本研究探讨了地球物理参数与水文地质参数间的关系,为SIP方法在实际有机污染场地调查与评估提供了理论依据。  相似文献   

中祁连西段石板墩堆晶岩的地球化学特征及构造意义     

马蓁  刘铮  刘懿馨  王金荣 《现代地质》2018,32(4):667

石板墩堆晶岩位于中祁连地块西段党河断裂带北侧,主要由橄榄岩、蛇纹石化橄辉岩和辉长岩组成,具有多旋回、多韵律层的产出特征。辉长岩LA ICP MS锆石U Pb年龄为(4865 ± 33) Ma。岩石地球化学结果显示,蛇纹石化橄辉岩和辉长岩配分型式十分相似,具有富集大离子亲石元素、亏损高场强元素、LREE相对富集、HREE平坦型分布以及正Eu异常(Eu/Eu*=097~304)的特点。研究结果表明,蛇纹石化橄辉岩、辉长岩为同源岩浆作用的产物,源区为被俯冲流体交代过的软流圈地幔,形成于火山弧环境,是在岩浆作用过程中不断发生堆晶作用,并在堆晶之后再次泵入混合大量新的玄武岩浆反复进行所形成。结合区域大地构造背景,认为中祁连西段是早古生代早期在残留的微陆块基础上形成的一个火山弧增生杂岩地体。  相似文献   

Formation Time of the Kalaqin Metamorphic Core Complex: Constraints from Zircon DatingEI北大核心CSCD     

Lin S.  Xie C.  Xiang B.  Zhao T. 《大地构造与成矿学》2018,(3):570-586

The Kalaqin metamorphic core complex, located on the northern margin of the Yanshan Tectonic Belt, is an important structure to understand the Late Mesozoic destruction processes of the North China Craton. In this study, structural analysis and geochronological investigation were conducted for the Anjiayingzi pluton and associated granodiorite dikes that intruded the core complex. Field observations demonstrated that emplacement of the pluton and dikes took place after the early stage extensional deformation, and intrusions are products of syn-tectonic magmatism during the late stage extension deformation. LA-ICP-MS zircon U-Pb dating yielded ages of 133-131 Ma for the Anjiayingzi pluton and 135 Ma for the dike, which demonstrated that the early extensional deformation took place at 156-135 Ma, rather than the Early Cretaceous as proposed previously. By integrating with other dating results, the early extensional deformation occurred at 156-150 Ma (Late Jurassic) and led to the exhumation of the core complex. The core complex was overprinted by a late extension in the Early Cretaceous. The revision of formation time for the Kalaqin metamorphic core complex further confirms that the extensional deformation took place in the Late Jurassic in the Yanshan tectonic belt, and therefore, it is likely that the northern margin of the North China Craton might have destructed since the Late Jurassic. © 2018, Science Press. All right reserved.  相似文献