用MATLAB工具精确快速测定宽频带地震计的周期与阻尼系数

对地震计的传统标定方法作了简单回顾，提出了借助Matlab工具软件用单位阶跃信号精确快速测定地震计的周期和阻尼系数的方法，给出了具体的设计思路与程序和测量实例，并进行了误差分析。     

宽频带地震计的快速标定

在满足一定测试精度的前提下,提高地震计标定的效率在地震计的批量生产中十分重要。讨论了宽频带地震计三点正弦波标定和阶跃标定,并将两种方法结合起来形成快速标定新方法,该方法具有一定的实用价值。     

CT-1地震计传递函数测试仪的设计

将计算机控制技术应用到甚宽频带地震计的传递函数测试中。讨论了基本的测试方法和原理，阐述了传递函数测试系统的软、硬件设计，给出了测试系统的应用实例。该测试系统具有正弦波自动扫频、阶跃信号法和脉冲信号法等标定方法，满足了甚宽频带地震计的传递函数测试在观测频带、动态范围和测试精度等方面的要求。     

地震计时域标定的噪声数据处理

分析了在甚宽频带地震计的时域标定中存在的各种噪声，探讨了相应的处理方法，重点阐述了对阶跃标定影响最大的长周期漂移噪声的处理方法——漂移曲线拟合法。     

超宽频带与甚宽频带地震计的台站现场标定

JCZ-1超宽频带地震计与CTS-1甚宽频带地震计是国家数字地震台网使用的关键设备,而地震计的台站现场标定是实现准确地震观测的重要环节。描述了这两种地震计对不同标定信号的响应规律;针对它们频带宽的特点,阐述了获取正确标定结果的条件;在分析标定误差来源基础上,提出了提高标定精度的数据处理方法。     

用超限率分析法提取钻孔倾斜地震前兆异常信号

选取钻孔倾斜观测资料,结合运用高通滤波与超限率方法,最大限度地提取波动、阶跃、突跳等高频信号,并定量描述这些信号的特征,检验此类信号与地震的关系。为确认信号的可靠性,排除气压、水位及仪器等因素影响。结果显示,中强地震前高频信号的数量和强度出现显著增大现象,多集中在3个月内,属短期异常,发震时间多为异常过程中或异常结束后3个月内。     

陆态网络太原台gPhone重力仪背景噪声水平研究

基于陆态网络太原台gPhone重力仪1a的观测记录,在地震频段(200~600s)、亚地震频段(1~6h)和潮汐频段(周期大于6h)研究其背景噪声水平,并与全球超导重力仪SG的背景噪声进行比较。结果发现,潮汐和大气改正可以一定程度上改进重力数据的功率谱密度PSD,尤其是在亚地震频段和潮汐频段。经计算,太原gPhone重力仪在地震频段、亚地震频段和潮汐频段的背景噪声水平分别为3.641、4.659和5.359。gPhone重力仪的噪声水平在地震频段和亚地震频段均高于SG的噪声水平,但是在频率低于0.8×10-4 Hz时,gPhone重力仪的噪声水平低于新低噪声模型NLNM。此外,分析gPhone重力仪记录的2014年智利Mw8.1地震激发的自由振荡信号表明,虽然gPhone重力仪的噪声水平高于超导重力仪,但其依然能够清晰检测到地球自由振荡信号,验证了gPhone重力仪不仅适合研究长周期潮汐和亚地震模,也可以清晰获取地震频段的地球自由振荡信号。     

宽频带负反馈地震计的实用标定方法

阐述了一种低成本有效标定宽频带负反馈地震计的方法,给出了实际标定结果和数据处理方法。     

二维地震勘探在伊南煤田伊昭井田的应用

在地震地质条件不利的情况下,确定了合理的野外数据采集方法;根据二维地震的目的任务,运用了合理的数据采集方法,采用了较好的技术措施解决了地震资料处理及解译中存在的技术难点,包括静校正问题、干扰波的去除、分辨率的提高、波组分析、层位标定、断点解释等。在覆盖层厚度、煤层底板、煤层露头、构造解释、火烧区推测等方面取得了较可靠的勘探成果,为后续全井田勘探布局发挥了指导性作用。     

一种去除地震背景噪音的新方法

结合希尔伯特-黄变换方法,根据信号背景噪音时间延续性假设,提出了一种自适应地震信号去噪算法。利用该算法实现了台站地震监测信号的去噪分析。分析表明：1）该去噪算法能根据背景信号特性有效去除信号的低频干扰;2）该算法可自适应完成信号分解去噪,计算效率高,无时间分辨率和频率分辨率问题;3）该算法处理高频干扰存在缺陷,有待进一步完善。     

Seislet transform denoising based on total variation minimization

Attenuation of noise is a persistent problem in seismic exploration. The authors use conventional denoising method to remove noise which may cause vibration near the discontinuity called pseudo-Gibbs artifact.In order to remove the artifact,the study proposed a method combining the seislet transform and total variation minimization. Firstly,the data are converted into the seislet transform domain. Secondly,the hard threshold was used for eliminating the noise and keep useful signal,which is the initial input for the next step. Finally,total variation minimization dealed with denoised data to recover boundary information and further eliminated the noise. Synthetic data examples show that the method has feasibility in eliminating random noise and protecting detailed signal,and also shows better results than the classic f-x deconvolution. The field data example also shows effective in practice. It can remove the noise and preserve the discontinuity signal at the same time.     

Characteristics and interpretation of the seismic signal of a field-scale landslide dam failure experiment

Outburst floods caused by breaches of landslide dams may cause serious damages and loss of lives in downstream areas; for this reason the study of the dynamic of the process is of particular interest for hazard and risk assessment. In this paper we report a field-scale landslide dam failure experiment conducted in Nantou County, in the central of Taiwan.The seismic signal generated during the dam failure was monitored using a broadband seismometer and the signal was used to study the dam failure process.We used the short-time Fourier transform(STFT) to obtain the time–frequency characteristics of the signal and analyzed the correlation between the power spectrum density(PSD) of the signal and the water level. The results indicate that the seismic signal generated during the process consisted of three components: a low-frequency band(0–1.5 Hz), an intermediate-frequency band(1.5–10 Hz) and a highfrequency band(10–45 Hz). We obtained the characteristics of each frequency band and the variations of the signal in various stages of the landslide dam failure process. We determined the cause for the signal changes in each frequency band and its relationship with the dam failure process. The PSD sediment flux estimation model was used to interpret the causes of variations in the signal energy before the dam failure and the clockwise hysteresis during the failure. Our results show that the seismic signal reflects the physical characteristics of the landslide dam failure process. The method and equipment used in this study may be used to monitor landslide dams and providing early warnings for dam failures.     

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Deriving the slope-mean shielded astronomical solar radiation spectrum and slope-mean possible sunshine duration spectrum over the Loess Plateau

Solar radiation is often shielded by terrain relief, especially in mountainous areas, before reaching the surface of the Earth. The objective of this paper is to study the spatial structures of the shielded astronomical solar radiation(SASR) and the possible sunshine duration(PSD) over the Loess Plateau. To this end, we chose six test areas representing different landforms over the Loess Plateau and the software package of Matlab was used as the main computing platform. In each test area, 5-m-resolution digital elevation model established from 1:10,000 scale topographic maps was used to compute the corresponding slope, SASR and PSD. Then, we defined the concepts of the slope-mean SASR spectrum and the slope-mean PSD spectrum, and proposed a method to extract them from the computed slope, SASR and PSD over rectangular analysis windows. Using this method, we found both spectrums in a year or in a season for each of the four seasons in the six test areas. Each spectrum was found only when the area of the corresponding rectangular analysis window was greater than the corresponding stable area of the spectrum. The values of the two spectrums decreased when the slope increased.Furthermore, the values of the stable areas of the spectrums in a year or in a season were positively correlated with the variable coefficients of the slope or the profile curvature. The values of the stable areas of the two spectrums in a year or in a season may represent the minimum value of test areas for corresponding future research on the spatial structures of the SASR or PSD. All the findings herein suggest that the spatial structures of the PSD and the SASR are caused by the interactions between solar radiation and terrain relief and that the method for extracting either spectrum is effective for detecting their spatial structures. This study may deepen our understanding of the spatial structure of solar radiation and help us further explore the distribution of solar energy in mountainous regions.     

卡尔曼滤波在InSAR噪声消除与相位解缠中的应用

相位解缠作为InSAR技术中的关键步骤,一直是研究的难点和热点。通常的相位解缠方法在相位解缠前首先必须进行噪声消除,而卡尔曼滤波将相位解缠问题转化为状态估计问题,实现了相位解缠与噪声消除一并处理,成为一种相位解缠新途径。并提出了卡尔曼滤波在相位解缠与噪声抑制中的一种新算法。