Instantaneous spectrum analysis and its application in estimation of earthquake tendency

In this paper, first discussing briefly the instantaneous spectrum theory. Then, the instantnaeous spectra and Fourier spectra of three seismic sequences are calculated, and comparing them to explain the superior characteristics of instantaneous spectrum. Finally, the earthquake tendency of North China is estimated by using the instantaneous spectrum theory. The results show that not only the occurrence time of the coming large earthquake, but also its magnitude instantaneous can be estimated by using instantaneous spectrum of the seismic sequence. The Chinese version of this paper appeared in the Chinese edition ofActa seismologica Sinica,15, 68–75, 1993.     

THE DISPERSION RELATION, OF EARTH''S ELECTROMAGNETIC RESPONSE FUNCTIONS AND THE JOINT INVERSION OF DATA

On the basis of the dispersion relations of MT field, the necessity and applied prospects of the joint inversions using a pair of MT response functions which are correlative with the dispersion relations, are infered. A filter coefficient algorithm is made, with which the corresponding impedance phase data can be estimated using a set of apparent resistivities. The tests for the observed MT data show that when comparing the impedance phase estimated using the dispersion relation with the ob served phase, it can be checked whether the dispersion relation between observed apparent resistivity and phase data is satisfied or not, and that the use of the phase data corrected using the dispersion relation in the joint inversion is advantageous to obtain more confident results. It is shown that joint inversions are more advantageous than single parameter inversions, and that in the most case the joint inversion using the apparent resistivities of impedance real and imaginary parts is more advantageous than the jointinversion using the normal apparent resistivity and impedance phase. The existence of the dipersion relations between the ratio apparent resistivity and corresponding impedance phase of the orthogonal electric and magnetic field horizontal Components in the frequency EM sounding with horizontal electric dipole(FEMS) are discussed, the better effect of the joint inversion using the pair of EM response functions is obtained. The problems on the one-dimensional joint inversion for the MT and FEMS apparent resistivities, for which the observed frequency bands partly overlape each other, are studied. It is shown that this joint inversion is applicable and effective:the joint inversions of the practical data for two kinds of EM methods at two sites give the results well corresponding to the drilling data. The simulated MT inversions for the data of two kinds of EM methods are made, and more confident results also are obtained.     

单片机控制的步进电机定频脉宽调制可变细分驱动系统

本文介绍所研制的由ＭＣＳ－５１单片机控制的步进电机定频脉宽调制可变细分驱动系统。该系统采用单电压驱动。配有软件。在不改变硬件电路的前提下．通过键盘操作，可以改变细分数。系统采用数字式定频脉宽调制技术，直接对细分电流进行反馈控制。最后提出了用实验确定均匀细分电流状态字的新方法，并验证了其可行性。     

等频大地水准面的概念及应用

阐述了等频大地水准面的概念及其理论基础，讨论了等频大地水准面与经典大地水准面的关系，提出了测定位差和高程差的新方法──引力或重力频移法，探讨了利用频移观测法解边值问题求定地球外部重力位的途径。     

BD—1标定信号发生器研制原理及性能

为提高标定仪器的技术性能和功能，满足台网地震遥测系统分段标定的使用要求，研制了ＢＤ—１型标定信号发生器．该仪器采用比较先进的单板机技术，用数字合成的方法产生标定需要的十八点频正弦波信号．     

MT重复测量在地震中短期预报中的应用──祁连山中段MT剖面监测研究

本文研究了青藏高原北缘第一个长约４００ｋｍ的ＭＴ监测剖面上所获得的５次５－７级地震前后的资料。着重分析了在相当于大陆多震层深度范围内壳内介质的多种ＭＴ参数（视电阻率、相位、主轴方位角、扭曲度等）．这些ＭＴ参数在大范围内的同步－同相变化和局部区域之间的超前、滞后变化、相对变化幅度随震中距增大而衰减的特征，可能分别对应着构造孕育型大震的地区性场兆和构造运动型强震的区域性场兆，形成了地震活动大背景叠加小背景的一种链式关系。运用＂ＭＴ监测优显参数＂进行择优监测，将可能为大陆地震的震源物理发展过程和中短期预报提供丰富可靠的判据。     

巴塘3次续发性中强地震震源的研究

本文使用ＣＤＳＮ宽频带数字地震波形记录，通过波谱分析研究了巴塘３次续发性中强地震震源的几何参数和动力参数，并同余震震源空间立体分布图像研究结果进行对比分析。     

A development of the lichenometric method applied to the dating of glacially influenced debris flows in southern chile

Lichenometry is a dating technique that has problems relating to questionable assumptions. The development of a size frequency approach, previously used in attempts to resolve some of the problems, is described and applied to the dating of four debris flows marginal to the San Rafael Glacier in Southern Chile. This study provides examples of the development's application, its problems and directions for further work. The size frequency approach, based on new assumptions, uses parameters derived from population size frequency distributions of the lichen species Placopsis patagonica to provide relative and absolute dating for rock surfaces. Changes in the shapes of distributions suggest the relative age of populations. Absolute dating is based on a curve (spanning a 24 year time period) derived from mean diameter size/age correlations. A stratified random sampling design permits the use of inferential statistics. Standard deviations and confidence intervals show error margins, the degree of relatedness between neighbouring populations, and populations that are anomalous. One-way analysis of variance is used to indicate where populations may safely be grouped. The size frequency approach appears to be particularly suitable for use on unstable debris flows where secondary movements are common. The approach also demonstrates that lichen growth and colonization are sensitive to aspect differences and other variations in microhabitat.     

Application of a generalized power transformation to geochemical data

In the context of analysis of variance, Box and Cox (1964) developed a generalized technique for power transformation of frequency distributions to normality. It is here applied to geochemical data, based on the nonlinear optimization of skewness and kurtosis. The transform appears to be particularly well suited to the preprocessing of geochemical data prior to multivariate analysis.     

基于双频磁共振的未知拉莫尔频率地下水探测方法

在利用地面磁共振方法进行地下水探测时,要求发射频率与拉莫尔（Larmor）频率相同.由于地磁场的不均匀性和噪声干扰,实际测量时无法获得准确的Larmor频率,导致发生偏共振现象.如果假设磁共振或频率偏量未知时,反演得到的含水量和弛豫时间（T₂^*）将存在较大误差.为了解决未知Larmor频率情况下的准确探测问题,本文在频率环测量方案的基础上提出了双频磁共振探测方法,即只需知道Larmor频率的范围区间,通过区间外的两个频率进行偏共振激发,利用频率差值的一半作为频率偏量计算核函数,即可消除未知Larmor频率的影响.通过仿真实验,证明了在电阻率大于100 Ωm时,双频磁共振和偏共振的核函数偏差较小.对于双层含水层模型,双频磁共振和偏共振的信号偏差小于3 nV,因此得到双频磁共振信号可以用偏共振核函数进行反演.通过对假设磁共振、假设偏共振和双频磁共振反演结果的对比,可以得到在未知频率偏量和设定频率偏量改变时,双频磁共振均能得到准确的反演结果.但是,当环境噪声增加和电阻率降低时,反演结果的准确度降低.最后,通过长春市烧锅镇采集数据的反演结果与已知钻探资料进行对比,验证了双频磁共振探测方法的有效性和准确性.