氟离子观测水温干扰因素的排除及实验

由于受观测水温因素干扰,氟离子标准序列的溶液温度和水样水温的温度差值越大,引起氟离子观测误差也越大。通过比测实验,结果表明:恒温和同温氟离子观测方法能消除水温与溶温不同引起的观测误差。得出经验:每日配制氟离子标准序列,选择恒温观测方法;氟离子标准序列不是每天配制,而是批量配制,选择"同温"观测方法。     

福建地下流体氟离子动态非地震前兆异常识别

2008年3—7月福建地区共发生4次中等地震,福建地下流体氟离子有多孔观测井,在震前或震后出现高值突跳的现象;2008年9-11月福建地下流体氟离子又有多孔观测井出现高值异常。本研究通过实验提出:该氟离子高值异常为非地震前兆异常,建议准备一支氟离子选择性电极作为备用电极,用于对比观测,以提高氟离子观测数据异常的判别。     

CIC-200离子色谱仪地震观测标准模板检验与标定

为了提高地震观测数据质量,有必要对配制的标准溶液、混合标准溶液、混合标准曲线溶液进行检验,提出标准模板检验方法。当观测数据出现异常时,需要对旧标准模板进行标定,提出标准模板标定方法。通过标准模板检验与标定结果分析,用低浓度标准样标定标准模板时,不能使用国标作为判断标准,而应使用标准偏差作为判断标准。提出特征离子概念,选一种相对标准偏差最小的离子,称为该水样的特征离子,作为判别标定结果是否合格的依据。     

河北永清龙虎庄地下水中氟浓度的异常形态分析

永清龙虎庄公社砖厂一口氟离子含量较高的热水井,其氟浓度平均为9.27毫克/升。为了研究地下水中氟浓度变化与地震之间的关系,我们于1981年底开始对该井点的地下水进行氟浓度的每日一次的观测。但是,由于采用电极标准加入法对氟的日常观测工作,毕竟属于探索性的研究工作,所以对于所得的氟浓度的日变曲线应如何认识,这是很值得研究的。下面我们就对我们初期的氟观测资料进行分析解剖,以说明这一问题。     

基于电磁探测数据的时序分析模型研究

针对电磁探测数据交叉检验时对不同卫星探测数据的时间匹配需求,本文基于DEMETER卫星时序探测数据,分析了国际参考电离层(IRI)模型模拟电子浓度(N_e)数据在不同纬度区域的误差分布特征; 同时,基于自回归移动平均(ARIMA)模型构建了N_e数据时序预测模型. 在此基础上,分析比较IRI模型与ARIMA模型在N_e数据时序预测中的优缺点,结果表明: ARIMA模型模拟预测N_e数据时间序列的相对误差在短期内较低(小于10%),且随着预测时间的增长而增大; 而IRI模型模拟预测N_e数据时间序列的相对误差不会随着预测时间的增长而增大,且在高纬度地区的预测相对误差比在中低纬度地区低.      

最大Lyapunov指数计算的几种方法

地震预报以各种时间序列数据为依据，因此如何从大量的时间序列中提取描述地震蕴孕过程的复杂性特征，成为从非线性科学角度探索地震预报的一个重要研究方向。本文讨论了混沌吸子的Ｌｙａｐｕｎｏｖ指数计算问题，并以一个模拟时间序列为例，讨论了如何从实验数据时间序列计算Ｌｙａｐｕｎｏｖ指数的问题，给出了两种实用的计算方法，对数值计算结果作了比较。此方法可用于地震及前兆时间序列复杂性刻划。     

应用离子选择性电极法测定深井水F~-浓度的实验

离子选择性电场法是电化学分析中普遍应用的一种方法。1985年,我们采用标准加入法对永清县浅牛—6井F~-浓度进行了实验观测。该井位于牛东断裂北伸、牛驼镇凸起顶峰。井深1274米。为Cl—Na型震旦亚界铁岭—雾迷山组岩溶裂隙水。实验所用主要仪器是:PXD—2型通用离子计、CSB—F—1型氟电极、212型饱和甘汞电极、681型磁力加热搅拌器、WMZL—01型温度控制仪及自制恒温水浴锅等。实验证明,离子选择性电极法做为地震地球化学监测的一种手段,在有条件的地方台和群测点是可以普及的。     

基于多种度量的电离层TEC混沌预测分析

利用东经120°,北纬45°上空的2008年年积日101～150 d时间段内共600个电离层格网TEC数据为时间序列样本,分析了该点上空电离层TEC参数的混沌特性,发现其关联维数为2.2632,嵌入维数为5,最大Lyapunov指数为λ=0.0833,表明该点上空电离层TEC时间序列具有混沌的特征,存在混沌现象.采用加权一阶局域法对TEC时间序列进行预测时,在有效预报尺度内,利用各种度量进行预报得到的中误差都随着预报天数的增加而逐渐增大,但预报的相对误差却是在一定幅度范围内上下波动.采用四种距离度量以及皮尔森相关系数和Jaccard相似系数进行预报,其预测结果或者平均中误差较大,或者平均相对误差较大,结果不理想.其中,采用标准化欧氏距离得到的平均中误差最大,达到5.107TECU,而采用皮尔森相关系数得到的平均中误差最小,为5.078TECU;对于平均相对误差而言,由切比雪夫距离得到的平均相对误差最大,为0.185,而Jaccard相似系数得到的平均相对误差最小,为0.166.而采用余弦相似度得到的预测结果,其平均中误差和平均相对误差都很小,分别为5.079TECU和0.167.因此,在一阶局域混沌预测时,采用余弦相似度作为衡量相空间轨迹的差异性是较为合适的.     

CIC-200离子色谱仪高浓度离子水样观测实验

CIC-200型离子色谱仪观测高浓度离子水样时,对水样稀释500—1 000倍,但观测误差大。考虑仪器观测的精密度,兼顾各离子正常图谱形态,福州地震台对高浓度离子水样进行不同倍数稀释实验,即进行高浓度标准溶液和标准添加的准确度和精密度实验,结果均满足国标要求,说明CIC-200离子色谱仪观测高浓度离子水样是可行的。     

大功率高频电波加热电离层中参量衰减不稳定性研究(2):EISCAT实验观测

本文利用欧洲非相干散射雷达协会(European Incoherent Scatter Scientific Association,EISCAT)的两次加热实验诊断数据,基于我们在文章(1)中建立的数值模型,定量分析了实验过程中出现参量衰减不稳定性(Parametric decay instability,PDI)的物理过程.分析结果如下:(1)通过对两次加热实验数据的分析,均观测到了增强的等离子体谱线(HFPLs)和离子声波谱线(HFILs),谱线的频率和加热电波频率满足频率匹配条件,表明电离层加热过程中参量衰减不稳定性的激发.(2)通过对加热电波反射区电子密度和离子密度模拟数据的谱分析,可以清晰发现与实验结果相符的朗缪尔波和离子声波.实验1观测到的离子声波谱线频率为8.8 kHz,而模拟得到的离子声波在5～6 kHz,实验2观测到的离子声波谱线为7.1 kHz,而模拟得到的离子声波频率在5.5～6 kHz,模拟结果与实验观测比较一致.(3)实验观测和模拟结果均表明,在参量衰减不稳定性激发过程中,加热电波频率(f_h)与等离子谱线频率和离子声波谱线频率(f_(ia))并不是简单匹配,实验1观测到的等离子体谱线频率为f_h-3f_(ia),实验2观测到的等离子体谱线增强频率为f_h—f_(ia)和f_h—3f_(ia).这一结果表明在加热过程中出现了多次参量衰减的现象,从而为朗缪尔湍流的激发提供了条件.     

采样方式对地震监测闪烁室法测氡仪校准结果的影响研究

利用HD-6型多功能自控氡室, 配合国际标准计量仪器AlphaGUARD PQ2000Pro测氡仪, 分别采用循环采样和负压采样两种方式, 对FD-125氡钍分析器的3个闪烁室进行校准实验, 计算3个闪烁室K值和相对固有误差。 结果表明: 循环采样方式得到的闪烁室K值比负压采样方式小, 负压采样方式得到的K值偏大, 已经接近《地震水文地球化学观测技术规范》要求的闪烁室K值的极限。 循环采样得到的闪烁室相对固有误差≤5%, 达到了《地震水文地球化学观测技术规范》的要求, 而负压采样方式得到的闪烁室相对固有误差>5%, 未达到《地震水文地球化学观测技术规范》的要求; 因此, 循环采样方式更适合地震监测闪烁室法测氡仪的氡室校准。     

Multi-point source identification of sudden water pollution accidents in surface waters based on differential evolution and Metropolis–Hastings–Markov Chain Monte Carlo

Sudden water pollution accidents in surface waters occur with increasing frequency. These accidents significantly threaten people’s health and lives. To prevent the diffusion of pollutants, identifying these pollution sources is necessary. The identification problem of pollution source, especially for multi-point source, is one of the difficulties in the inverse problem area. This study examines this issue. A new method is designed by combining differential evolution algorithm (DEA) and Metropolis–Hastings–Markov Chain Monte Carlo (MH–MCMC) based on Bayesian inference to identify multi-point sudden water pollution sources. The effectiveness and accuracy of this proposed method is verified through outdoor experiments and comparison between DEA and MH–MCMC. The average absolute error of the sources’ position and intensity, the relative error and the average standard deviations obtained using the proposed method are less than those of DEA and MH–MCMC. Moreover, the relative error and the sampling relative error under four different standard deviations of measurement error (σ = 0.01, 0.05, 0.1, 0.15) are less than 2 and 0.11 %, respectively. The proposed method (i.e., DEMH–MCMC) is effective even when the standard deviation of the measurement error increases to 0.15. Therefore, the proposed method can identify sources of multi-point sudden water pollution accidents efficiently and accurately.     

积分安培离子色谱法测定地下水中碘化物的不确定度评定

本文对积分安培离子色谱法测定地下水中碘化物含量的不确定度进行了评定,标准曲线采用双误差拟合法,建立了不确定度评定模型,得出几种影响测定结果的因素。     

A multifactor analysis of parameters controlling solar wind ion flux correlations using an artificial neural network technique

Solar wind plasma and magnetic field observations from multiple spacecraft can be used to separate temporal and spatial variations and to determine the accuracy of predictions of solar wind conditions near Earth based on distant-spacecraft measurements. The study of correlations between the ion fluxes measured by three spatially separated spacecraft (IMP 8, WIND and INTERBALL-1) was one of the first steps in this direction. This paper describes a complex multifactor analysis of different physical, geometrical, and statistical parameters that control such correlations (considered separately and in combination). A linear-regression and an artificial neural network techniques are used for this analysis. The analysis is applied to an extensive array of correlation coefficients for the ion flux in the solar wind and provides estimates of the relative significance of the factors that control these correlation coefficients. The study shows that the most influential parameters are the solar wind density and the standard deviations of solar wind density, solar wind velocity and interplanetary magnetic field. This set of parameters permits us to develop a sufficiently accurate (with a relative error of less than a few per cent) quantitative model for the correlation between the ion fluxes measured on two spatially separated spacecraft.     

Errors in time delay measurements

Summary Simple delay and sum of sensors in a seismic array is an effective method for noise suppression. However, unless we have precise steering delays, much of the signal energy is lost during the beam forming process too. We have investigated possible error sources in time delay measurements, using a computerized cross-correlation procedure. Parameters perturbed are correlation window length and positioning, signal frequency content and signal to noise ratio (SNR). Our results indicate that relative low frequency waves and using the very first part of theP-signals give the most reliable and stable time delay values. High frequency bandpass filtering improves SNR, but signal correlation and the precision in beam steering corrections decrease. Significant loss of high frequency energy during beamforming seems to be unavoidable.     

地下流体测项中氟氯离子及水电导的映震效率

展示了数十年来国内外科研机构运用地下流体测项中氟氯离子及水电导的异常特征探索防震减灾的突出成果。在分析了异常特征可能的产生机理后指出:流体测项中氟氯离子及水电导很可能是我们探寻多年的地化敏感元素,该元素抗干扰能力强,映震效果好,测试方便快捷,既经济又可靠。建议各地区结合本地化学、地质构造特征做到扬长避短,在不适合进行水位和水气观测的井泉多开展对氟氯及其他离子元素和水电导的多项目的综合监测研究,做到一井多用,监测有重点,分析有全面。     

A hybrid approach to compute seismic travel times in three-dimensional tetrahedral meshes

We propose an optimized method to compute travel times for seismic inversion problems. It is a hybrid method combining several approaches to deal with travel time computation accuracy in unstructured meshes based on tetrahedral elementary cells. As in the linear travel time interpolation method, the proposed approach computes travel times using seismic ray paths. The method operates in two sequential steps: At a first stage, travel times are computed for all nodes of the mesh using a modified version of the shortest path method. The difference with the standard version is that additional secondary nodes (called tertiary nodes) are added temporarily around seismic sources in order to improve accuracy with a reasonable increase in computational cost. During the second step, the steepest travel time gradient method is used to trace back ray paths for each source–receiver pair. Travel times at each receiver are then recomputed using slowness values at the intersection points between the ray path and the traversed cells. A number of numerical tests with an array of different velocity models, mesh resolutions and mesh topologies have been carried out. These tests showed that an average relative error in the order of 0.1% can be achieved at a computational cost that is suitable for travel time inversion.     

Fluorine in surface and subsoil waters in the Middle Klyaz’ma Basin

Data on fluorine concentration in water in the Middle Klyaz’ma Basin during summer low-water period have been obtained. Fluorine background concentration has been determined in streams (Klyaz’ma R., small rivers, and creeks), water bodies (drainage ditches, lakes), and subsoil waters. Anthropogenic fluorine hydrochemical anomalies have been determined and localized with respect to urbanized industrial areas. An assumption has been made and experimentally substantiated, according to which fluorine concentration in subsoil water is governed by the processes of its distribution between water and host rocks. It has been established that the interaction of soils with snowmelt water and alluvial deposits with river water in neutral and acid media is accompanied by fluorine removal from solution, while in a weakly alkaline medium, fluorine passes from solid phase into solution. The effect of dissolved organic matter on the process of fluorine leaching from rock minerals also depends, primarily, on the equilibrium pH value: in weakly alkaline media, the presence of organic acids contributes to fluorine mobilization, while in weakly acid media, it reduces mobilization rate.     

地震台阵上信号方位角和慢度的时、频域估计方法比较

地震台阵常用频率-波数分析法来估计地震信号的后方位角和慢度。尽管有关的算法是众所周知的,但不同的实现在某些情况下可能导致不同的结果。如应用在宽频带的澳大利亚WRA台阵的记录时,标准的f-k分析方法往往给出不正确的结果。本文发现错误是由FFT的频谱泄漏效应引起的,如在进行FFT之前对原始数据进行高通滤波则可以有效地避免这样的错误。进一步对在时域中直接估算信号方位角和慢度的一种算法进行了分析,比较发现时域方法的计算速度和精度都不低于频域方法,且在某些低信噪比的情况下,前者可以给出更可靠的结果。