Nonlocal period parameters of frequency content characterization for near-fault ground motions

This paper focuses on the frequency property analysis of near-fault ground motions with and without distinct pulses, separately from the Chi-Chi and Northridge earthquakes. Ten scalar period parameters of ground motions, especially several nonlocal period parameters, are considered. Two new nonlocal parameters, namely the mean period of Hilbert marginal spectrum (T_mh) and the improved characteristic period (T_gi), are suggested. Moreover, comprehensive comparison and analysis indicate that T_mh, T_gi and T_avg (average spectral period) can distinguish the low-frequency components of near-fault ground motions; T_m (mean period of Fourier amplitude spectrum) and T_o (smoothed spectral predominant period) represent the moderate- and high-frequency components, respectively. The variance coefficient of predominant instantaneous frequency of Hilbert spectrum (H_cov) can be regarded as an alternative index to measure the non-stationary degree of near-fault ground motions. Finally, the velocity pulses and earthquake magnitude remarkably affect the frequency parameters of near-fault ground motions. Copyright © 2012 John Wiley & Sons, Ltd.     

武汉市主城规划区地震动参数小区划及其应用问题研究

本文以武汉市主城规划区地震动参数小区划（以下简称武汉市地震动参数小区划）工作为主线,研究了弱震区内潜在震源区划分和工程地质条件对峰值加速度的影响程度、软土地基反应谱特征与构造措施的选取,以及以小区划成果作为抗震设防标准在实际应用中所遇到的一些问题。     

扩频微波网桥在新疆测震网络中的应用

以频率为2.4 GHz和5.8 GHz设备为例,对扩频微波网桥在新疆测震网络中的应用范围进行阐述;根据实际工作中无线网桥的安装架设经验,对在不同条件、不同环境下可能出现的问题提出相应解决方案.     

基于地震对应概率谱分析的定点形变前兆异常探索

利用地震对应概率谱和累计滑动平均概率方法,选取精河水平摆卡尔曼滤波差值进行中强地震前兆定量的异常识别探索。探索中先是对精河水平摆卡尔曼滤波差值数据进行数据分布及各区间参数有震对应分布的研究,然后利用累计滑动平均方法得到滑动平均概率,从而检验地震对应概率谱在定点形变前兆异常的预报效能。     

土层地震反应中软弱夹层对加速度反应谱的影响

为了研究土层地震反应中软弱夹层对加速度反应谱的影响,本文构造了多种包含不同厚度、不同位置软夹层的土层结构,通过国内地震安评通用的ESE软件进行计算、分析。研究结果表明,软夹层的厚度、位置、输入地震动的幅值等对加速度反应谱均有不同程度的影响,上部含有软夹层的土层结构能造成反应谱出现双峰现象,引起加速度反应谱特征周期变大。本文研究结果对软土地区工程抗震设计有一定参考价值。     

海南新海夏季潮流谱分析和余流研究

根据夏季琼州海峡新海附近15 m处地层潮流谱分析结果可得,无论是f>0 或f<0,全日潮谱峰都高于半日潮谱峰。其中,半日潮周期,约为12 h,12.4 h,日潮存在两个,一个在23.9 h,另一个在25.8 h前后;在半日潮和全日潮分量中,反时针分量是主要的、顺时针的日潮能谱只有反时针的84%;顺时针的半日潮能谱只有反时针的63%;浅水分潮8.3 h,6.2 h和超过24 h的4.2 d,3 d等也很明显,但是未通过显著性检验; 大多数余流流速在5~10 cm/s之间,个别情况超过40 cm/s。受反时针运动涡旋影响,余流主要向偏东北、北、西北方向运动。在这个区间内的流向,占总观测数68%以上;风对余流也有重要影响:东北风将使余流方向偏向西北,偏北向风将使余流方向偏南。     

大连海域近海面湍流结构及谱特征

利用黄海北部大连海域2009年10月—11月的近海面大气湍流观测资料,对湍流强度、方差相似关系、风速与温度分量谱及湍流通量协谱等进行了分析。结果表明:该海域在海风环境下湍流强度随着风速的增大逐渐减小,且强度均小于0.5;湍流方差相似关系基本上满足1/3定律,近中性环境下无量纲化三维风速方差主要受海滨地形的影响;各速度分量谱在惯性副区符合理论上的-2/3次幂规律,不稳定条件下由于湿度因素的影响,温度谱谱线在高频部分收缩较差,略有上翘;动量谱在惯性副区更接近-2/3幂率,感热谱在惯性区基本符合-4/3的分布,但是谱线分布与稳定度没有明显的规律性。     

基于累积和算法的动态变形预警模型研究

利用GPS对构筑物进行动态变形监测,获取构筑物的动态变形序列,通过卡尔曼滤波处理变形时间序列,从而削弱相关噪声的影响,提取真实的变形信号,并通过FFT处理变形信号,验证其滤波效果.在分析累积和算法的前提下,构建构筑物预警模型,分析了平均运行长度及预警阈值等相关参数的选取原则.经实测数据分析,模型能有效检测到变形发生时刻,该方法能够提高GPS进行动态变形预警的可靠性,特别是为微小变形提供一定研究指导意义.     

Preliminary investigations on Arctic microalgae by joint aDDlication of fluorescent instruments

In vivo fluorescence has a wide application in analyzing microalgae, including assessing phytoplankton biomass, rates of primary production and physiological status. This study describes a preliminary investigation on the joint application of the three kinds of fluorescence analysis in the physiological study of microalgae. Flow cytometry and fluorescence spectrometry were used to obtain the in vivo static fluorescence information of pigments, and a Pulsed-Amplitude-Modulation chlorophyll fluorometer was used to detect the dynamic fluorescence of chlorophyll. The validity of the joint application was proved by analyzing two labora- tory cultured Arctic microalgae, Pseudo-nitzschia delicatissima （Bacillariophyceae） and Thalassiosira sp. The higher value of minimum fluorescence yield in dark-adapted state （Fo）, actual photochemical efficiency of PSll （ФPSII）, and electron transport rate （ETR） exhibited positive results in a higher cell abundance and chlorophyll a content of P. delicatissima; whereas higher fl-carotene content of Thalassiosira sp. played an important role in the protection of photosynthesis.     

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