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Mário Pereira Fernando Veloso-Gomes José Lima Sérgio Oliveira 《Marine Georesources & Geotechnology》2016,34(7):617-629
This article describes the implementation of a monitoring system on the breakwater at the Funchal Port (Madeira Island, Portugal) for the purpose of understanding its dynamic behavior and the temporal evolution of structural health. The monitoring system focuses on the breakwater superstructure and aims to identify the evolution of damage on the breakwater and analyze the impact of cruise ships docking and undocking. The system includes the measurement of displacements through geodetic techniques using global navigation satellite systems and the measurement of vibrations using accelerometers. Ten observation campaigns were performed over almost 3 years. As the measured displacements during this period were less than 7.5 mm it can be concluded that, despite some visible cracks, the breakwater superstructure did not suffer significant structural changes. It was shown from the measured acceleration records that some of the main modal parameters could be identified, namely the main natural frequencies of the superstructure. Through an analysis of the natural frequencies progression over time, it will be possible to identify deterioration effects on the foundation and/or the superstructure. The comparison of natural frequencies identified could be useful to evaluate the impact of these events on structural health. 相似文献
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传统地震预警方法通过在地震频发区域部署高密度地震监测台网,进而构建区域地震预警系统。但此方法所需投资较高,同时还需要政府和不同行业间的密切合作,使得大部分位于地震频发区域的国家和地区无力支撑地震预警系统的建设与运维。随着微机电系统技术的发展以及智能手机的普及,地震预警技术出现了新的研究方向,利用智能手机开展地震预警具有巨大的发展潜力。迄今为止,国内外已研发完成多款诸如MyShake、i-jishin之类的手机端APP地震预警软件。本文详细描述了利用手机端内嵌MEMS芯片开展地震预警的研究进展,较为系统地总结了在手机端进行地震预警时所涉及的处理流程以及相关算法。 相似文献
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密集布设的MEMS强震仪台网获取的准实时强震观测数据,可以为震后灾情快速判断和平时地震学基础研究提供科学依据。本文阐述了利用3G/4G无线通信和L2TP（Layer Two Tunneling Protocol,第二层通道协议）VPN（Virtual Private Network,虚拟专用网络）技术,基于互联网组建MEMS（Micro Electromechanical System,微机电系统）强震仪监测网络的主要步骤和实现过程,实现了MEMS数据的实时传输。提供了一种简单的组网模式,为建立灵活、实用、覆盖面广,并具有一定安全性的密集监测网络提供参考。 相似文献
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车载导航系统常用惯性测量元件（IMU）与全球卫星导航系统（GNSS）技术组合以提高系统的稳定性。由于车载导航系统的应用场景限制,对初始对准速度有着较高要求。为了提高传统车载组合导航系统中低成本微机电系统（MEMS）陀螺仪的初始对准速度,降低初始对准过程中的计算量,本文提出了一种适用于任意失准角下的基于网络RTK辅助与无损Kalman滤波（UKF）的MEMS陀螺仪初始对准算法。同时针对车载系统的特点,简化了IMU系统误差方程,分析了简化带来的误差。在诺瓦泰ProPak6和诺瓦泰IMU-IGM-S1组成的导航系统中验证了本文提出的算法。试验结果表明,在以诺瓦泰双天线GNSS输出航向角为"真值"的情况下,本文提出的算法基本可以在5 s内完成陀螺仪的初始对准,对准精度达0.3°。 相似文献
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室内定位需求急剧增加,普及的智能手机带来了解决问题的一种方法。本文提出了一种基于智能手机的粒子滤波室内融合定位方法。利用三轴加速计和三轴罗盘等微机电系统(micro-electromechinical system, MEMS)传感器数据估计目标的运动状态信息,利用WiFi数据更新运动状态,实现融合定位。室内动态环境下实验结果表明,融合定位方法平均定位误差小于2 m,其有效利用智能手机平台获取多种传感器数据,很好地结合了行人航迹推算方法和K加权最近邻方法的优势,在定位精度和稳健性方面均有良好表现。 相似文献
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在双天线GNSS/MEMS组合测姿中,低精度、低成本的MEMS加速度计输出通常包含比较大的噪声,导致由加速度计调平计算得到的水平角观测值精度较低,影响组合测姿的精度和可靠性。不同于传统的时域降噪方法,从频域的角度出发,根据实际车载运动中加速度计输出具有因汽车固有结构产生的高频振动噪声的特点,利用滑动窗口的Butterworth低通滤波器平滑加速度计输出。动态车载实验结果表明,该滤波器降噪效果明显。与滤波前相比,水平角观测值精度提升了约4倍,达到(0.643°,0.546°)。在此基础上,滤波后组合测姿精度也从(0.124°,0.738°,0.532°)提升到(0.122°,0.074°,0.052°),其中水平角精度提升了大约一个数量级,滤波后的测姿结果更加准确可靠。 相似文献
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微机电系统（MEMS）表面加工工艺中的材料层厚度是决定MEMS器件性能的重要参数之一,如多晶硅结构层厚度和牺牲层厚度,直接决定了MEMS器件的机构性能和结构的纵向移动范围,因此对材料层厚度进行测试和工艺控制监视是极具意义的.当前的材料层厚度测试大多采用光机械的方法,因其测试方法复杂、设备昂贵、测试时间长且很难集成到一个工艺控制监视（PCM）系统中,提出一种新颖的材料层厚度电学测试结构,该测试结构具有结构简单、测量方便并且便于MEMS测试系统集成的特点.通过软件对测试结构和测试模型进行闭环验证,结果表明,模拟值与理论值有较好的一致性. 相似文献
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Anibal Ojeda Samuel Martinez Maria Bermudez Kuvvet Atakan 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):791-797
The new accelerographic network of Santa Fe de Bogotá is composed of 29 three-component stations with sensors at the surface and three additional six-component borehole stations with three sensors at the surface and three at depth (115, 126 and 184 m). In total, 32 stations have been operative in the metropolitan area of Bogotá since 1999. During this period of time, a significant number of weak motion are recorded and used for a preliminary analysis of local site effects. Using the SH-wave response spectra we verify the behavior of the different seismic zones proposed by the previous microzonation study of the city. A comparison between normalized SH-wave response spectra and the normalized design spectra for each zone clearly depicts that parts of the design spectra should be revised, as well as the boundaries between different zones may require some changes. The spectral amplification levels reach up to a factor of 5. The predominant periods obtained by the amplification spectra in different stations in the city, show variability from 0.3 to 3.0 s. A comparison is also made between the predominant periods obtained using H/V spectral ratios of microtremors and those using weak motion. In general, microtremors tend to predict slightly lower values of dominant periods than those calculated by the weak motion spectra. However, there is a general correlation between the two data sets. Using the data recorded by one of the borehole station, an equivalent linear seismic response analysis was conducted. The modeled and recorded response spectra show similarities in period peaks, however, the modeled soil amplification is underestimated for periods less than 0.8 s. Since the available record is weak motion which represents mostly the linear response of the soils, further analysis is required. 相似文献