Optimal instrumentation of uncertain structural systems subject to earthquake ground motions     

Ernesto Heredia-Zavoni  Luis Esteva 《地震工程与结构动力学》1998,27(4):343-362

A criterion is proposed for making decisions regarding the optimal location of a given number of sensors to record the seismic response of a structure for identification purposes. The optimal location of the sensors is selected so that the expected value of a Bayesian loss function, expressed in terms of the Fisher information in the recordings, is minimized. The criterion is applied to the case of multi-degree-of-freedom systems with uncertain structural properties subjected to earthquake ground motions modelled as stationary stochastic processes. The use and capabilities of the criterion are thoroughly illustrated by means of an example. Results are used to assess the influence of record duration, recording noise, and ground motion frequency content and amplitude, on the optimal location of accelerometers as well as on the reduction of prior uncertainty about the structural parameters. © 1998 John Wiley & Sons, Ltd.  相似文献   

冲击荷载下玄武岩纤维水泥土吸能及分形特征     

马芹永  高常辉 《岩土力学》2018,39(11):3921-3928

为研究玄武岩纤维对水泥土冲击破坏过程中能量吸收及碎块块度分布特征的影响,采用Φ50 mm变截面霍普金森压杆（split Hopkinson pressure bar,简称SHPB）试验装置对不同玄武岩纤维掺量的水泥土进行了冲击压缩和动态劈裂试验,分析了冲击荷载作用下玄武岩纤维掺量与水泥土吸收能、破坏形态和分形维数 的关系,试验结果表明：随着玄武岩纤维掺量的增加,水泥土吸收能呈先增大后减小的趋势,超过最佳掺量后,由于纤维-纤维薄弱面的存在,水泥土吸收能减少;冲击破坏后水泥土破碎块度分布是具有统计意义上的分形,冲击压缩试验中水泥土破碎块度平均粒径随玄武岩纤维掺量的增加而不断增大,对应的 值总体上呈现不断减小的趋势;在动态劈裂试验中,玄武岩纤维掺量在0～2.0%范围内,水泥土破碎块度平均粒径呈现上升趋势, 值不断减小,玄武岩纤维掺量超过2.0%后,平均粒径有所降低,对应 值增大。玄武岩纤维水泥土吸收能和 值之间有着密切的联系,冲击压缩试验中,吸收能在分形维数为2.20～2.26范围内呈先增大后减小的趋势,而在动态劈裂试验中,吸收能在分形维数为1.85～2.20范围内总体呈现下降趋势,两者具有一定的负相关性;合适掺量的玄武岩纤维对水泥土动态特性起着积极作用,通过试验得出玄武岩纤维的合适掺量为1.5%～2.0%。  相似文献   

基于BOFDA的地面塌陷变形分布式监测模型试验研究          下载免费PDF全文

卢毅  于军  龚绪龙  施斌  王宝军  季峻峰 《高校地质学报》2018,24(5):778

地面塌陷变形作为一种分布广泛的地质灾害已成为目前城市发展中亟待解决的一个问题。文章使用布里渊光频域分 析（BOFDA）技术对地面塌陷变形进行分布式监测模型实验研究。利用自制的地面塌陷物理模型,对不同类型、不同厚度 土体在塌陷过程中的变形进行分布式光纤监测,并对其试验结果进行对比分析。结果表明：基于BOFDA分布式光纤传感技 术可有效捕捉到地面塌陷变形的发生和发展过程,并较为准确地反映出地面的塌陷变形规律。研究结果为该技术在地面塌 陷变形监测的推广应用提供一定的参考依据。  相似文献   

泥蚶(Tegillarca granosa)重组铁蛋白富集重金属离子的特性及化学传感器的研究     

张涛  苏倡  刘艳  张迪骏  周君  芦晨阳  明庭红  司开学  苏秀榕 《海洋与湖沼》2017,48(4):870-876

利用泥蚶(Tegillarca granosa)铁蛋白原核表达工程菌获得的重组铁蛋白,通过圆二色光谱分析蛋白二级结构,扫描电镜和电感耦合等离子质谱研究重组铁蛋白富集Fe~(2+)、Mn~(2+)、Cd~(2+)、Cr~(3+)、Hg~(2+)、Pb~(2+)和As~(3+)等7种重金属离子的特性,同时探索利用重组铁蛋白修饰丝网印刷电极,设计和制备重组铁蛋白检测Pb~(2+)和Cd~(2+)浓度的电化学生物传感器。结果表明复性成功的铁蛋白多为完整的?-螺旋结构,而复性不成功的蛋白聚集体则多为无规卷曲。重组铁蛋白的直径和形态与富集的离子种类有关。泥蚶铁蛋白对单一金属离子Fe~(2+)和Mn~(2+)的富集凸显优势。对两种混合金属离子的富集大多表现为竞争关系。但重组铁蛋白对Hg~(2+)和As~(3+)混合组的富集量明显高于单一金属离子组的富集量,对Hg~(2+)和As~(3+)混合组的富集表现出协同促进作用。重组铁蛋白传感器对Pb~(2+)和Cd~(2+)溶液的最低检测限为10μg/L。  相似文献   

四种海水透明度现场测量方法的对比分析及发展趋势研究          下载免费PDF全文

任尚书  周树道 《海洋开发与管理》2017,34(3):99-104

随着海洋探测的不断发展,海水透明度作为海水光学性质的一个重要参量,也越来越受到人们的关注。文章对比分析了4种海水透明度现场测量方法:透明度盘法~([1])、光纤式高光谱剖面测量法~([2])、激光衰减测量法~([3])和基于双光路原理的海水IOPs高光谱测量法~([4]),主要分析了4种方法的测量原理,对比各自的优缺点,并提出了海水透明度测量未来发展设想。  相似文献   

Field testing of modular borehole monitoring with simultaneous distributed acoustic sensing and geophone vertical seismic profiles at Citronelle,Alabama          下载免费PDF全文

T.M. Daley  D.E. Miller  K. Dodds  P. Cook  B.M. Freifeld 《Geophysical Prospecting》2016,64(5):1318-1334

A modular borehole monitoring concept has been implemented to provide a suite of well‐based monitoring tools that can be deployed cost effectively in a flexible and robust package. The initial modular borehole monitoring system was deployed as part of a CO₂ injection test operated by the Southeast Regional Carbon Sequestration Partnership near Citronelle, Alabama. The Citronelle modular monitoring system transmits electrical power and signals, fibre‐optic light pulses, and fluids between the surface and a reservoir. Additionally, a separate multi‐conductor tubing‐encapsulated line was used for borehole geophones, including a specialized clamp for casing clamping with tubing deployment. The deployment of geophones and fibre‐optic cables allowed comparison testing of distributed acoustic sensing. We designed a large source effort (>64 sweeps per source point) to test fibre‐optic vertical seismic profile and acquired data in 2013. The native measurement in the specific distributed acoustic sensing unit used (an iDAS from Silixa Ltd) is described as a localized strain rate. Following a processing flow of adaptive noise reduction and rebalancing the signal to dimensionless strain, improvement from repeated stacking of the source was observed. Conversion of the rebalanced strain signal to equivalent velocity units, via a scaling by local apparent velocity, allows quantitative comparison of distributed acoustic sensing and geophone data in units of velocity. We see a very good match of uncorrelated time series in both amplitude and phase, demonstrating that velocity‐converted distributed acoustic sensing data can be analyzed equivalent to vertical geophones. We show that distributed acoustic sensing data, when averaged over an interval comparable to typical geophone spacing, can obtain signal‐to‐noise ratios of 18 dB to 24 dB below clamped geophones, a result that is variable with noise spectral amplitude because the noise characteristics are not identical. With vertical seismic profile processing, we demonstrate the effectiveness of downgoing deconvolution from the large spatial sampling of distributed acoustic sensing data, along with improved upgoing reflection quality. We conclude that the extra source effort currently needed for tubing‐deployed distributed acoustic sensing vertical seismic profile, as part of a modular monitoring system, is well compensated by the extra spatial sampling and lower deployment cost as compared with conventional borehole geophones.  相似文献   

Efficient Bayesian sensor placement algorithm for structural identification: a general approach for multi‐type sensory systems          下载免费PDF全文

Ka‐Veng Yuen  Sin‐Chi Kuok 《地震工程与结构动力学》2015,44(5):757-774

In this paper, a Bayesian sequential sensor placement algorithm, based on the robust information entropy, is proposed for multi‐type of sensors. The presented methodology has two salient features. It is a holistic approach such that the overall performance of various types of sensors at different locations is assessed. Therefore, it provides a rational and effective strategy to design the sensor configuration, which optimizes the use of various available resources. This sequential algorithm is very efficient due to its Bayesian nature, in which prior distribution can be incorporated. Therefore, it avoids the possible unidentifiability problem encountered in a sequential process, which starts with small number of sensors. The proposed algorithm is demonstrated using a shear building and a lattice tower with consideration of up to four types of sensors. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

一种洪涝灾害事件信息建模方法     

陈泽强  陈能成  杜文英  宋凡 《地球信息科学学报》2015,17(6):644-652

我国洪涝灾害频发且危害巨大,为有效防灾、减灾和救灾,需建立洪涝灾害事件信息模型,表示和共享洪涝灾害信息。然而,目前事件信息模型主要是表示静态信息,缺乏对洪涝灾害事件动态过程的表示。本文从观测角度出发,建立顾及洪涝灾害事件阶段和动态过程的洪涝灾害事件信息模型。围绕洪涝灾害事件信息模型,提出了10类需建模的元素,并以MOF（Meta Object Facility）建模框架构建了十元组模型,通过映射方法实现模型编码方案与事件模式语言的映射。最后,以2010年梁子湖洪涝灾害模拟为例,开展了模型分阶段建立过程实验。结果表明,本文提出的模型能表示洪涝灾害事件的动态信息和实现洪涝灾害事件的动态建模。  相似文献   

MPA方法在不同高度桥墩地震响应分析中的适用性研究          下载免费PDF全文

蒋崇文  王典斌  卢皓 《地震工程学报》2015,37(2):577-584

桥梁通常是线路中的控制工程,其抗震性能显得尤为重要。作为梁桥重要组成部分的桥墩,往往是地震作用下容易受到损伤的构件。结合西部山区梁桥的典型桥墩结构形式,基于纤维模型的有限元方法建立桥墩的非线性数值分析模型。采用MPA方法对不同高度桥墩的地震响应进行分析,以非线性时程分析方法的计算结果为基准研究MPA方法的适用性。计算表明MPA方法在分析高阶模态参与程度较高的高墩构件时适用性较差。  相似文献   

基于OpenSees的RCS组合框架结构抗震性能模拟分析     

门进杰  胡俊  王秋维  郭智峰 《地震学刊》2014,(5):649-655

选取已有钢筋混凝土柱—钢梁组合结构（RCS）框架的低周期反复试验数据,采用地震工程开源模拟软件OpenSees对其进行有限元模拟,对比骨架曲线与滞回曲线,试验结果与有限元结果吻合较好。随后考察弯矩放大系数（Mc/Mb=0.86、1.48、2.04）、柱轴压比（n=0.06、0.2、0.3、0.6、0.8）对抗震性能的影响,得到了各参数下框架的滞回曲线、骨架曲线和各特征阶段的荷载与位移值。分析了框架的破化过程、延性与强度退化。结果表明：RCS组合框架滞回曲线饱满,具有良好的变形及耗能能力;随着弯矩放大系数的减小、柱轴压比的增大,框架的水平极限承载力降低、屈服状态提前、位移延性降低。分析结果可供有关研究或工程应用参考。  相似文献