Cambridge deep Ocean geophone     

Jeremy Duschenes  Chris Potts  Martyn Rayner 《Marine Geophysical Researches》1985,7(4):455-466

We describe recent mechanical andeelectronic modifications to the Cambridge Ocean Bottom Hydrophone system, enabling it to record in addition three geophone channels from a deployed, disposable geophone package. Examples of data from seismic refraction experiments show good correspondence between records of ground motion detected by the hydrophone and the vertical geophone. Seismic signals are undistorted by noise from instrument related sources. Clear examples of P to S conversions just below the receiver are observed. Improved recording conditions are achieved by deploying the geophones in a small pressure vessel as far away as possible from the main instrument package.  相似文献   

The University of Durham Southern Hemisphere VHE gamma ray telescope     

K. T. Brazier  A. Carramiñana  P. M. Chadwick  T. R. Currell  N. A. Dipper  E. W. Lincoln  V. G. Mannings  T. J. L. McComb  K. J. Orford  S. M. Rayner  K. E. Turver 《Experimental Astronomy》1989,1(2):77-99

The design of very high energy (VHE) gamma ray telescopes is discussed and it is shown that a triple-mirror telescope operating in threefold fast coincidence provides an effective instrument. The design, construction and operation of a large VHE gamma ray telescope with an energy threshold of 300 GeV (at the zenith) and incorporating several novel features is described. The use of a coincidence guard ring technique is shown to result in the rejection of about 50% of the off-source (proton) events which form a high background and limit the sensitivity of such telescopes.  相似文献   

流动环境中二维铅垂纯射流的试验研究   总被引：3，自引：2，他引：3       下载免费PDF全文

槐文信  李爱华  那宇彤  杨中华  童汉毅  黄纪忠 《水科学进展》2003,14(3):300-304

对均匀流动环境中的铅直二维射流进行了试验研究,得到了流动转变的条件.采用超声多普勒流速仪(ADV)对射流流场进行了测量,得到了流速矢量图和流线图,发现在射流的迎流面存在流线跌落现象.探讨了流速比对射流背流面涡心和分离点位置的影响.给出低流速比为8的射流流场的实测结果,以供数值模拟对比使用.  相似文献   

A mathematical model of concentrate solids content for the wet drum magnetic separator     

John G. Rayner  T. J. Napier-Munn   《International Journal of Mineral Processing》2003,70(1-4):53-65

Low concentrate density from wet drum magnetic separators in dense medium circuits can cause operating difficulties due to inability to obtain the required circulating medium density and, indirectly, high medium solids losses. The literature is almost silent on the processes controlling concentrate density. However, the common name for the region through which concentrate is discharged—the squeeze pan gap—implies that some extrusion process is thought to be at work. There is no model of magnetics recovery in a wet drum magnetic separator, which includes as inputs all significant machine and operating variables.A series of trials, in both factorial experiments and in single variable experiments, was done using a purpose built rig which featured a small industrial scale (700 mm lip length, 900 mm diameter) wet drum magnetic separator. A substantial data set of 191 trials was generated in this work. The results of the factorial experiments were used to identify the variables having a significant effect on magnetics recovery.It is proposed, based both on the experimental observations of the present work and on observations reported in the literature, that the process controlling magnetic separator concentrate density is one of drainage. Such a process should be able to be defined by an initial moisture, a drainage rate and a drainage time, the latter being defined by the volumetric flowrate and the volume within the drainage zone. The magnetics can be characterised by an experimentally derived ultimate drainage moisture. A model based on these concepts and containing adjustable parameters was developed. This model was then fitted to a randomly chosen 80% of the data, and validated by application to the remaining 20%. The model is shown to be a good fit to data over concentrate solids content values from 40% solids to 80% solids and for both magnetite and ferrosilicon feeds.  相似文献   

1995年日本阪神地震近场强地面运动的特征          下载免费PDF全文

罗奇峰  那向谦 《地震工程学报》1997,19(3):52-55,62

分析了１９９５年日本阪神地震（Ｍ７．２）近场强地面运动特征．结果表明，震中附近地区水平加速度峰值达６００～８００ｇａｌ，竖向加速度峰值达３００ｇａｌ，强地面运动持续时间为１０～１５ｓ，加速度时程的卓越周期为０．２～２ｓ．谱分析的结果还表明，在较宽的频带范围内该次地震的近场地震动的强度都比较大．  相似文献   

Multi-species chemical data assimilation with the Danish Eulerian hemispheric model: system description and verification     

Jeremy D. Silver  Jesper H. Christensen  Michael Kahnert  Lennart Robertson  Peter J. Rayner  Jørgen Brandt 《Journal of Atmospheric Chemistry》2016,73(3):261-302

Satellite retrievals of atmospheric composition provide a wealth of data on a global scale. These complement results from atmospheric chemistry-transport models (CTMs), and can be combined using data assimilation. We present two assimilation schemes coupled to the Danish Eulerian Hemispheric Model (DEHM), a three-dimensional, off-line CTM with full photochemistry: a variant on the ensemble Kalman filter and the three-dimensional variational scheme. The aim of this paper is to describe the two schemes and present an initial assessment of their impacts on model skill. Retrievals of multiple atmospheric trace gases are assimilated, namely: NO₂ tropospheric column densities, CH₄ total column densities, and partial column concentrations of O₃, CO and CH₄; these data are retrieved from four satellite sensors. Data for each species are assimilated independently of one another, and other species are only adjusted indirectly via the model’s chemistry and dynamics. Assimilation results are compared with measurements from surface monitoring stations and other satellite retrievals, and preliminary validation results are presented.Reference simulations (without assimilation) grossly underestimate surface CO concentrations, and both assimilation schemes eliminate this large and systematic model bias. The assimilation improves the spatial correlation of modelled CO with surface observations, and improves the spatial correlation between forecasts and retrievals for CO, NO₂ and O₃. Results for CH₄ show a loss of skill due to a mismatch in model bias between two assimilated CH₄ data-sets. Finally, we discuss differences in methodology and results between this paper and a recent study on multi-species chemical data assimilation. Joint optimisation of initial conditions and emission rates offers a promising direction for improving modelled boundary-layer concentrations.  相似文献   

The First Discovery of the Easternmost Jehol Biota from Southeastern Jilin,China     

LI Yunfeng  HUANG Wei  WANG Hongshan  David L. DILCHER  TAN Xiao  LI Tao  NA Yuling  SUN Chunlin 《《地质学报》英文版》2018,92(4):1649-1650

正Objective The Jehol Biota,a world-famous Early Cretaceous fossil Lagerst?tte characterized by the traditional Eosestheria-Ephemeropsis-Lycoptera(EEL)assemblage,has a wide distribution over most parts of northern China,the coastal area of southeastern China,southeastern Mongolia,Transbaikalian area of Russia,Korea and Japan(Shao et al.,2017).The Baishan Basin,situated in  相似文献   

内蒙古科尔沁右翼中旗协和尔斯德中生代火山沉积地层时代研究          下载免费PDF全文

付俊彧  那福超  郑少林  钟辉  汪岩  宋维民  孙巍  杨帆 《中国地质》2018,45(1):129-140

内蒙古科尔沁右翼中旗协和尔斯德一带出露一套中生代地层,岩石组合主要为酸性火山碎屑岩、火山碎屑沉积岩夹碎屑沉积岩及酸性火山熔岩。1∶50000区调依据在该套地层上部层位发现的木化石组合确定其时代为中—晚侏罗世,结合岩石组合,将该套地层划分为上侏罗统满克头鄂博组。为了准确厘定该套地层时代,为木化石延限研究及区域生物地层划分对比提供依据,本次研究在低于产木化石层位的酸性火山碎屑岩中采取了锆石测年样品(LA-ICP-MS),获得锆石U-Pb年龄(165±1)Ma,时代为中侏罗世。同时采取了侵入该套地层的斑状细晶闪长岩测年样品,获得锆石年龄(131±1)Ma,限定了地层形成的上限年龄。根据岩性组合的区域对比、测年结果、木化石组合时限、地层产状特征,认为该套地层应划为中侏罗统新民组,是突泉火山-沉积盆地充填物的一部分。  相似文献   

对冀北-辽西-大兴安岭地区晚中生代地层划分、对比的区域构造学思考     

张允平  宋维民  那福超 《地质与资源》2018,27(4):307-316

根据冀北-辽西-大兴安岭地区晚中生代具有相关沉积建造组合、火山-沉积建造组合、生物组合和构造类型组合特征,提出建立与造山运动"同期"的构造地层单位概念.认为这种构造地层单位的概念有利于以区域构造演化为主线,理解"同造山期"陆缘活化区陆相沉积以及火山-沉积盆地地层系统的复杂性,并从区域构造学角度提出该地区地层划分、对比的方案.  相似文献   

大兴安岭北段扎兰屯地区晚古生代早期花岗质岩浆作用——对额尔古纳 兴安地块和松嫩地块拼合时限的制约   总被引：1，自引：0，他引：1  

钱程  陆露  秦涛  李林川  陈会军  崔天日  江斌  那福超  孙巍  汪岩  吴新伟  马永非 《地质学报》2018,92(11):2190-2214

扎兰屯地区位于二连 贺根山 黑河构造带中段,区内发育韧性变形叠加的晚古生代早期花岗岩类。本文在详尽的野外地质调查基础上,对该套花岗岩类的锆石U- Pb年代学和地球化学进行系统分析,研究其成岩年代序列,探讨岩石成因及构造背景,厘定韧性构造叠加的时限,进一步揭示扎兰屯地区额尔古纳 兴安地块和松嫩地块的拼合过程,为兴蒙造山带的区域构造演化研究提供新材料。大量年代学研究显示,扎兰屯地区晚古生代早期花岗质岩浆作用发生于405~325Ma之间,该作用可进一步细化为早中泥盆世(Ⅰ期、405~380Ma)、晚泥盆世—早石炭世初(Ⅱ期、365~350Ma)和早石炭世晚期(Ⅲ期335~325Ma)等3期。其中Ⅰ期和Ⅱ期花岗岩类属高钾—钾玄质钙碱性、准铝质—弱过铝质花岗岩类,可能为俯冲背景下岛弧岩浆活动形成的I型 分异I型花岗岩;Ⅲ期花岗岩类属中—高钾钙碱性、准铝质—弱过铝质花岗岩类,可能为后碰撞背景下岩浆活动形成的分异I型- A型花岗岩。该套花岗岩类普遍叠加韧性变形,可能为碰撞后侧向逃逸作用的产物,变形时限为晚石炭世末—早二叠世(308~290Ma)。大兴安岭北段晚古生代早期花岗质岩浆作用与额尔古纳 兴安地块和松嫩地块的碰撞拼合作用有关,扎兰屯地区二者的碰撞拼合时限可能为早石炭世中期。  相似文献