大跨开合屋盖风荷载与风致响应试验与数值计算研究     

陈伏彬  蔡虬瑞  翁兰溪  周晋芳  李秋胜 《地震工程与工程振动》2019,39(1):88-95

为研究屋盖开孔对大跨结构风效应的影响,在边界层风洞中开展了大跨开合屋盖刚性模型风洞测压试验,分析了结构表面风荷载分布特征,基于时域分析法研究了屋盖开合对风致响应的影响。结果表明:大跨结构模态密集,第一阶模态能量最大,高阶成分的贡献不容忽视;屋盖开洞能有效的减小屋面风荷载,降低位移响应与加速度响应,减小风振系数。研究结果可为大跨开合屋盖风荷载设计提供参考。  相似文献   

随钻声波测井固井质量评价理论与数值模拟研究   总被引：2，自引：0，他引：2       下载免费PDF全文

李盛清  林剑松  江灿  苏远大  唐晓明 《地球物理学报》2020,63(7):2762-2773

大斜度井、水平井的固井质量评价需求,推动了基于随钻测井仪器的固井质量评价技术的发展.本文基于弹性波传播理论,建立柱状分层介质的套管井随钻测井模型,模拟了不同水泥胶结情况的随钻声场响应,特别是其波形特征.结果表明,套管井中随钻与电缆波形特征最大的区别在于随钻波列中存在隔声衰减后的钻铤波.特别是当水泥胶结较好时,钻铤波与套管波幅度大小相近,甚至钻铤波幅度更大,而时间域上两者波形重叠,该特点使得常规电缆声波(声幅/变密度)固井质量评价方法不适用于随钻测井环境.本文考察了不同水泥胶结程度下随钻波列中套管波幅度和衰减与胶结指数的关系,形成一种同时利用幅度和衰减的随钻声波胶结指数计算方法,为随钻声波固井质量评价提供理论指导.  相似文献   

用重力测量技术观测城市地表下沉的实验研究          下载免费PDF全文

陈晓东  李航  邓明莉  江利明  孙和平  李德伟  张为民  郝洪涛  桑鹏  白林 《地球物理学报》2020,63(8):2882-2892

本文用重力测量技术对城市地表下沉进行了实验研究,从2016年3月到2017年5月在武汉市内地表下沉较大的部分城区进行了7期流动重力观测实验,并用D-InSAR观测的垂向位移进行了验证.数值结果表明重力观测每期整网平差后点值平均精度都小于10×10~(-8)m·s~(-2),说明采用重力观测能在城市内获得高精度的区域重力变化.第7期相对于第1期的结果与D-InSAR在大致相同时间段内地表垂直位移结果比较表明,重力增加的大部分区域与D-InSAR观测到的地表下沉区域相一致,说明这些区域的重力增加主要是由地表下沉引起的.从第2到7期相对于第1期的重力变化说明在近12个月的时间内测区最大重力变化约40×10~(-8)m·s~(-2),且局部区域的重力值是逐渐增加的,说明地表下沉是持续进行的.本实验结果说明重力观测技术能为城市地表下沉提供重力观测约束和机制解释.  相似文献   

Improved environmental contour methods based on an optimization of hybrid models     

《Applied Ocean Research》2019

  相似文献   

Scenarios of tsunami amplitudes in the north eastern coast of Sea of Marmara generated by submarine mass failure     

A. Hayir  B. Seseogullari  İ. Kilinc  A. Erturk  H.K. Cigizoglu  M.S. Kabdasli  O. Yagci  K. Day 《Coastal Engineering》2008

In this paper the tsunamis resulting from a submarine mass failure such as slides and slumps triggered by earthquakes or other environmental effects, which is settled at the bottom of the north eastern Sea of Marmara are examined in one sample region. As the solution method, one hybrid method is developed. The main objective of this method is to combine an analytical solution presenting near-field tsunami amplitudes above the submarine mass failure with a numerical solution indicating the tsunami amplitudes in the coastal regions. For this purpose, one common linear boundary between analytical and numerical solution domains is defined. Movements of Submarine Mass Failures (SMF) are modeled using one simple kinematics source model and the amplitudes of the tsunamis at the region that are closer to the landslide are computed by using the analytical method. SMF is modeled approximately from the bottom geometry, and an average depth is used. Scenarios of SMF are established depending on the velocities and thicknesses of the failure, and near-field tsunami amplitudes are obtained in the open sea during the source time. After the source times, the solutions are found in the numerical region using TELEMAC-2D software system with the mentioned boundary above. In this boundary, the output of the analytical solutions is taken as the boundary conditions or the disturbances for the numerical method. With these disturbances, the numerical method is performed and the amplitudes are calculated in the coastal area. The generation, propagation and coastal amplifications of the tsunamis are illustrated at some certain points and regions both in the open sea and near the coast line. The results have been visualized and discussed.  相似文献   

基于带权点法向量的LiDAR数据屋顶检测方法   总被引：1，自引：0，他引：1  

黄先锋  王潇  张帆 《武汉大学学报(信息科学版)》2009,34(1)

提出了一种基于带权点法向量的LiDAR数据屋顶检测方法。通过利用点和其邻接点构成的面法向量进行峰值统计,检测屋顶面。检测过程中同时考虑每个点法向量的权值,从而确定每个点对面的贡献,一定程度上消除了噪声的影响,提高了小面积屋顶检测的准确程度。同时,采用多阈值进行屋顶面检测,能够检测大小不同的面。通过实验验证了本算法的有效性。  相似文献   

Character and distribution of hybrid sediment gravity flow deposits from the outer Forties Fan, Palaeocene Central North Sea, UKCS   总被引：1，自引：0，他引：1  

Christopher Davis  Peter Haughton  William McCaffrey  Erik Scott  Nicholas Hogg  David Kitching 《Marine and Petroleum Geology》2009,26(10):1919

Seven categories of event bed (1–7) are recognised in cores from hydrocarbon fields in the outer part of the Palaeocene Forties Fan, a large mixed sand-mud, deep-water fan system in the UK and Norwegian Central North Sea. Bed Types 1, 6 and 7 resemble conventional high-density turbidite, debrite and low-density turbidite, respectively. However the cores are dominated by distinctive hybrid event beds (Types 2–5; 81% by thickness) that comprise an erosively-based graded and structureless and/or banded sandstone overlain by an argillaceous sandstone or sandy-mudstone unit containing mudstone-clasts and common carbonaceous fragments. Many of the hybrid beds are capped by a thin laminated sandstone–mudstone couplet (the deposit of a dilute wake behind the head of the turbidity current). Different types of hybrid event bed Types are defined on the basis of the ratio of sandier lower part to upper argillaceous part of the bed, and the internal structure, particularly the presence of banding. Although the argillaceous and clast-rich upper divisions could reflect post-depositional mixing, sand injection or substrate deformation, they can be shown to be dominantly primary depositional features and record both a temporal (and by implication) spatial change from turbidite to debrite deposition beneath rheologically complex hybrid flows. Where banding occurs between lower sandy and upper argillaceous divisions, the flow may have passed through a transitional flow regime. Significantly, the often soft-sediment sheared and partly sand-injected argillaceous divisions are present in cores both close to and remote from salt diapirs and hence are not a local product of remobilisation around salt-cored topography. Lateral correlations between wells establish that sandy hybrid beds (Types 2, 3S) pass down-dip and laterally into packages dominated by muddier hybrid beds (Types 3M, 4) over relatively short distances (several km). Type 5 beds have minimal or no lower sandier divisions, implying that the debritic component outran the sandier component of the flow. The Forties hybrid beds are thought to record flow transformations affecting fluidal flows following erosion and bulking with mudstone clasts and clays that suppressed near-bed turbulence and induced a change to plastic flow. Hybrid beds dominate the muddier parts of sandying-upward, muddying-upward and sandying to muddying-upward successions, interpreted to record splay growth and abandonment, overall fan progradation, and local non-uniformity effects that either delayed or promoted the onset of flow transformations. The dominance of hybrid event beds in the outer Forties Fan may reflect very rapid delivery of sand to the basin, an uneven substrate that promoted flow non-uniformity, tilting as a consequence of source area uplift and extensive inner-fan erosion to create deep fan valleys. This combination of factors could have promoted erosion and bulking, and hence transformations leading to the predominance of hybrid beds in the outer parts of the fan.  相似文献   

非均匀介质全局广义R/T递推传播矩阵法二维SH地震波模拟研究          下载免费PDF全文

刘彬  荣棉水  孙伟家  黄建平  巴振宁 《地球物理学报》2021,64(2):525-536

地球深部圈层及沉积盆地是一种分区非均匀介质系统,其中不规则地层边界(含起伏地表)对地震波的主要特征有显著影响,而地层的随机非均匀性则主要影响地震波的散射和衰减特征.为了精确刻画不规则地层边界对地震波的反射、透射效应以及非均质体散射引起的地震波衰减效应,全局广义R/T递推传播矩阵法(GGRTM)被提出并逐步发展成为继有限...  相似文献   

A new generation photodetector for astroparticle physics: The VSiPMT     

《Astroparticle Physics》2015

The VSiPMT (Vacuum Silicon PhotoMultiplier Tube) is an innovative design we proposed for a revolutionary photon detector. The main idea is to replace the classical dynode chain of a PMT with a SiPM (G-APD), the latter acting as an electron detector and amplifier. The aim is to match the large sensitive area of a photocathode with the performance of the SiPM technology. The VSiPMT has many attractive features. In particular, a low power consumption and an excellent photon counting capability. To prove the feasibility of the idea we first tested the performance of a special non-windowed SiPM by Hamamatsu (MPPC) as electron detector and current amplifier. Thanks to this result Hamamatsu realized two VSiPMT industrial prototypes. In this work, we present the results of a full characterization of the VSiPMT prototype.  相似文献   

Simulation of green roof test bed runoff          下载免费PDF全文

Gerald Krebs  Kirsi Kuoppamäki  Teemu Kokkonen  Harri Koivusalo 《水文研究》2016,30(2):250-262

Low Impact Development (LID) aims to mitigate the hydrological impacts of urbanization by replication of processes in natural catchments. Green roofs covered with vegetation and pervious substrate are one alternative among a wide range of LID tools. Water retention of green roofs depends on many factors (e.g. local climate), and measurements remain crucial in evaluating their performance. The simulation of green roof retention by a hydrological model is one option to evaluate their potential benefits before implementation. In this paper, we evaluated the ability of the recently introduced LID green roof module of the stormwater management model to replicate runoff from monitored green roof test beds under Nordic climate conditions. A parameter sensitivity analysis was conducted to identify calibration parameters. The model showed an overall acceptable performance, and the results indicated the importance of accurately estimating potential evapotranspiration rates for inter‐event periods, which is essential in representing the retention capacity regeneration. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献