共查询到20条相似文献，搜索用时 15 毫秒
1.
本文主要针对当前磁法勘探中高精度处理解释的需求,对强磁性体ΔT异常计算存在的误差进行分析研究.我们首先通过理论模型计算试验,证明常规计算采用的投影关系的ΔT与实际测量的模量差ΔT之间的误差E在磁异常幅值大时是明显存在的,其影响不容忽视.其次,当磁性强且剩磁存在时,投影ΔT曲线及其误差曲线在磁化方向与地磁场方向改变时具有一定的对称性;地磁场T0、磁性体形态(如二度水平圆柱体模型的半径r、柱体埋深R)和磁性参数(如磁化率κ)等参数确定的情况下,最大误差值出现在磁性体正上方,且其大小与磁性参数(κ)和模型体规模(如r/R)之间皆是指数关系;另外,研究还发现ΔT的计算误差曲线的一些其他规律特点,如在各纬度带上,ΔT计算误差的最大值Emax曲线的极值主要分布在中纬度地区;磁异常矢量Ta与地磁场T0的夹角θ逐渐变化时,随θ变化Emax曲线的极值分布在θ=90°~120°范围内;当磁异常幅值小于10000nT时,最大误差近似为磁异常矢量垂直于地磁场方向的测点附近的误差值;另外,磁性体(圆柱体为例)的半径(即尺度)与埋深的比值r/R超过0.5,且磁化率超过0.1SI时误差已达到3.9nT,磁化率增大与对应的Emax的值呈指数增长特点.因此,我们的研究表明,在强磁性体、磁异常幅值大的数据处理、反演及解释时,现有方法会产生较大的误差,应该基于严格的模量差ΔT,完善相应的处理以及反演方法. 相似文献
2.
总强度磁异常(ΔT1)常规处理方法通常将其近似当作磁异常矢量在地磁正常场方向上的投影(ΔT2).然而对于高磁环境如磁铁矿处的磁异常场幅值可达104 nT甚至更大的情况,上述近似假设则不再成立,如采用常规处理方法可能会带来明显的误差.本文针对该问题,提出一种基于等效源的总强度磁异常非线性处理方法;该方法根据总强度磁异常获取流程,直接反演实测地磁场总强度幅值与正常场强度幅值之差来求取等效场源.本文首先通过模型试验,分析ΔT1与ΔT2的差异;然后将ΔT1当作ΔT2采用常规处理方法以及ΔT1采用新方法得到的结果作对比分析,结果表明新方法处理结果与理论值的差异为常规方法处理结果的1/5甚至更小,充分说明了新方法的有效性;最后将该方法应用于铁矿实测总强度磁异常处理实例中来转换计算磁异常总模量,其实际应用效果进一步体现了高幅值总强度磁异常数据处理过程中采用新方法的必要性. 相似文献
3.
一、问题的提出区域地震传输台网,担负着日常地震的监测和大震速报工作。台网的监测能力,除子台分布合理外,还依赖于设备的配套。西昌传输台网的子台均为1秒短周期垂直向地震仪。当网内发生M_L≥2级(RΔ<100km),网边发生M_L>3级(RΔ>100km)时,1秒短周期地震仪的记录都限幅(出格),震相不清,分析困难,影响震级及其它参数测定的速度和精度。 相似文献
4.
利用伺服控制双轴加载系统,采用阵列式布局的应变、自电位测量方法,对岩石样品弹性变形阶段和破坏过程中的应变和自电位进行了实验研究. 结果表明,在突然加卸载、黏滑和岩样破裂几种特定情况下,自电位和应变场均出现了互相关联的脉冲状突然变化,且具有相当大的空间展布. 尽管有时应力σ值相当高,但当应力变化率γ= dσ/ dt为零（恒载）且保持正、负常数（匀速加、卸载）时,自电位始终没有异常出现. 反之,无论γ的增量Δγ为正值或负值,当γ突变,即对样品进行突然加卸载的时刻则出现了脉冲状自电位信号ΔV,Δγ的正或负对ΔV的影响是相反的. 分析表明,应力突变时ΔV与Δγ的异常幅度成正比. 应力突变和岩石破裂过程中自电位明显的时空变化意味着,孕震区附近如果自电位有突变,就有可能观测到相关的自电位前兆和同震变化, 并可能出现同步的应变变化,这给地震的自电位和应变前兆方法提供了实验证据. 相似文献
5.
地震事件一般具有离散性, 即它们的发生和转移具有一定的时间和空间间隔。 当孕震系统处于平衡(或正常)状态时, 系统状态变量X(这里以地震活动性为例)的时间序列概率分布表现为单峰型(如泊松分布); 其时间间隔(或等候时间)Δt分布可用负指数分布来描述。 当系统处于非平衡(或异常)状态时, X的概率分布表现为双峰型或多峰型, 其时间间隔Δt(或空间间隔ΔS)可采用幂函数关系来描述。 可以计算X的1~4阶矩统计参数识别X的概率分布性质, 进一步判断系统所处的状态。 根据这个思路, 本文尝试针对地震活动性的群体概率特征, 探索研究地震活动系统时间和空间结构的演变以及正常和异常状态的辨别, 并将这些方法应用于2008年汶川8.0级地震及其余震趋势和强余震预测实践。 相似文献
6.
基于伪随机信号系统辨识的电法勘查仪器多试图借助于相关处理——计算大地(系统)输入信号(供电电流I(t))和输出信号(电位差ΔU(t))的互相关RI,U(t)和自相关RI,I(t)——以期提高获取大地阻抗的瞬变过程(冲激响应和阶跃响应)和/或频谱(频率响应)的抗干扰性能.笔者先前的研究结果表明,仅在偏移时间t小于位宽Δt,特别是在零偏移时间,互相关RI,U(t)和自相关RI,I(t)函数值较大时才有较强的抗干扰能力;而时间偏移t大于位宽Δt时,相关函数值非常小,易受干扰而畸变.利用全周期相关函数值计算大地(系统)时间响应和频率响应的伪随机相关辨识的抗干扰性,并不理想.在电磁干扰较大或信噪比较低(近于或小于0 dB)时,不能取得可靠的时间响应和频率响应数据.基于上述情况,本文提出仅利用零偏移时间的互相关和自相关函数值RI,U(0)和RI,I(0),获取具有高抗干扰性能的导电和激电参数.文中给出了这些抗干扰参数的具体算法,并列举仿真模拟和野外观测数据,证明它们的... 相似文献
7.
地震总输入能量与瞬时输入能量谱的研究 总被引：2，自引：0，他引：2
现有的抗震设计理论大多是基于承载力或强度的设计方法,与其相应的反应谱理论最大的缺陷是无法反映地震动持时的影响,而以地震动能量作为设计参数时就能弥补现有抗震理论的不足。本文按照反应谱理论的思路建立了线性单自由度体系的地震动总输入能量谱和瞬时输入能量谱。研究发现,阻尼比为5%时的地震动总输入能量谱和最大瞬时输入能量谱的等价速度谱可以分别用阻尼比为0.5%和10%下的拟速度谱来近似获得;地震波的V/A值大于0.15时,总输入能量谱的Δt谱峰值与地震波的强震持时呈线性增长关系,V/A值小于0.15时,两者间的关系无规律性。最大瞬时输入能量谱的Δt谱峰值基本不受地震波的V/A值与强震持时的影响;输入能量谱(总输入能量谱与最大瞬时输入能量谱)的特征周期随地震波V/A值的增大而增大,根据分析结果本文提出了线性单自由度体系输入能量谱的简化计算方法,方法简便,计算结果偏安全。 相似文献
8.
数字遥测地震台网测震能力图的制作 总被引：1，自引：1，他引：0
王翠芳 《地震地磁观测与研究》2004,25(4):32-37
数字遥测地震台网的测震能力图是衡量台网测震水平的一个重要标志,它既能反映一个台网的监测精度,更能反映一个台网的监测范围。要作出台网测震能力图,首先要获得台基振动数据,并对该数据作处理,然后根据相应的公式计算出起算函数R(Δ)、震中距Δ和台站监视半径r,最后作出测震能力图。 相似文献
9.
《地球物理学进展》2020,(4)
烃源岩总有机碳含量(TOC)的预测是烃源岩有机质丰度评价的重要一环.为解决传统ΔlogR方法应用于陆相深层烃源岩误差较大的问题.本文以ΔlogR法为基础,提出了一种考虑密度因素的广义ΔlogR法预测TOC.传统ΔlogR方法是一种基于测井曲线(声波、电阻率等)和成熟度参数(LOM)的预测TOC的方法,可以获得纵向上连续的有机碳分布,并且在国内外多个地区取得了较好的效果.但是研究表明,由于陆相深层烃源岩受到压实作用等影响,传统ΔlogR方法预测的结果不理想.干酪根有机质的密度远低于烃源岩基质密度,将考虑密度因素的广义ΔlogR法预测TOC的方法应用于渤中凹陷西南部东营组和沙河街组烃源岩,对其TOC进行分段预测,并与传统ΔlogR法、敏感测井多元回归方法预测结果进行对比,结果表明,研究区使用该方法的效果要优于其他两种方法.该方法拓展了传统ΔlogR法的适用范围,为烃源岩TOC的预测提供了新的思路和方法. 相似文献
10.
大定源是地面瞬变电磁观测的主要方式之一, 该方式在大深度、高密度的面积测量时具有明显的优势. 但当接收点偏离发射框中心时, 由于场源的非对称性(即框边影响), 数据处理和解释比较困难, 特别是全程瞬变响应的精确计算相当耗时. 本文介绍一种数值算法, 它既能实现快速计算, 又能满足精度要求. 该算法通过对瞬变场垂直分量(bz)及其时间变化率(bz/t)的核函数Y(Z)和Y'(Z)表现特性的研究, 以参数Z把整个瞬变过程分为早期阶段(Z→0), 中期阶段和晚期阶段(Z→∞). 计算全程响应时, 早期和晚期阶段分别采用Y(Z)和Y'(Z)的渐近表达式;对中期阶段, 内层积分(即误差函数erf)采用有理Chebyshev渐近展开式, 外层积分采用Romberg数值积分法. 理论模型计算表明, 利用该算法可以快速计算空间任意点(除发射边框)的全程响应核函数Y(Z)和Y'(Z). 当测点到边框的距离大于边长的25%时, 计算速度比常规数值积分算法快7倍;其它测点处计算速度比常规数值积分算法快4倍. 全程时段的相对误差<0.0002%. 相似文献
11.
《Journal of Atmospheric and Solar》2008,70(17):2144-2158
The results from the numerical calculations of the global distribution of topside ionospheric parameters such as H+ ions and ion and electron temperatures up to 1500 km height are presented for equinoctial conditions at solar minimum. Calculations are carried out using the Global Self-consistent Model of Thermosphere, Ionosphere and Protonosphere (GSM TIP) developed in WD IZMIRAN, and using a new calculation block for electric fields due to dynamo and of magnetospheric origin. A comparison of two sets of calculations of magnetospheric convection electric field for a given potential difference is carried out, one through polar caps and other through field aligned currents of first zone. It is shown that the distribution of the electric potential obtained through field aligned currents of first zone is more self-consistent than that through polar caps. The light ion trough in H+ ions is deeper and occupies larger region for the potential difference through polar cap. For a given potential difference through field aligned current, at 1500 km, the maximum ion temperature is 150 K higher, minimum ion temperature is 200 K lower and maximum electron temperature is 100 K higher than those obtained for the same potential difference through polar caps. It is concluded that for modeling the electric field of magnetospheric origin, it is necessary to use the potential difference through field aligned current of first zone instead of through polar caps. 相似文献
12.
ＥｓｔｉｍａｔｉｏｎｏｆｓｅｉｓｍｉｃｓｔｒｅｓｄｒｏｐｆｒｏｍｔｈｅｐｅａｋｖｅｌｏｃｉｔｙｏｆｇｒｏｕｎｄｍｏｔｉｏｎＪＩＡＺＨＥＮＧＱＩＮ（秦嘉政）ＺＵＹＩＮＬＩＵ（刘祖荫）ＸＩＡＯＤＯＮＧＱＩＡＮ（钱晓东）ＱＩＮＧＹＩＮＸＩＥ（谢庆... 相似文献
13.
Pei-Yan Chen 《地震学报(英文版)》1997,10(2):181-191
In this paper, the relation that the curves of nonlinear parameter H and its difference ΔH bear with strong earthquakes in North China has been studied. First, the RSH algorithm has been applied to the North China
region; the schemes of six quantitative prediction indexes have been studied in detail and then tested by tracing-back predictions.
The result shows that all the six prediction schemes are of certain prediction efficiency and have passed the test. Among
the six schemes, A and E are of the best effect, with correlation coefficients R of 0.47 and 0.48 respectively. We recommend these two schemes for practical use in prediction in the future. Furthermore,
the relation between the curve of ΔH (the difference of H) and strong earthquake has been studied. Based on the above results, the RSΔH algorithm that uses the
ΔH value to predict strong earthquake has been put forward and applied to predict strong earthquakes in North China. The correlation
coefficient R of tracing-back prediction by this method is 0.45; this means that this method is also of better prediction efficiency. A
combined application of these two algorithms has also been proposed. By the combined method, the time length spanned by false
predictions can be shortened and thus the R value can be raised.
Contribution No. 96A0033, Institute of Geophysics, SSB, China.
This project sponsored by the Chinese Joint Seismological Science Foundation. 相似文献
14.
Beata Orlecka-Sikora Eleftheria E. Papadimitriou Grzegorz Kwiatek 《Acta Geophysica》2009,57(2):413-434
We applied the Coulomb stress transfer technique to investigate interactions among seismic events induced by mining works
in the Rudna mine in the Legnica-Glogów Copper District in Poland. We considered events with energy greater than 105 J from the period 1993–1999.
We examined the influence of the cumulative static stress changes (ΔCFF) due to previous events on the generation of subsequent
ones. The results indicate that in many cases strong mining tremors produce changes in the state of stress of a sufficient
magnitude to influence subsequent events. The location of over 60% of events is consistent with stress-enhanced areas where
the values of ΔCFF were above 0.01 MPa. For most of the events located inside areas of a calculated negative ΔCFF, their modelled
rupture zone was partially located inside stress enhanced area, providing thus additional evidence for possible triggering
at the nucleation point. 相似文献
15.
The estimation of the Earth’s gravitational potential energy E was obtained for different density distributions and rests
on the expression E = − (Wmin + ΔW) derived from the conventional relationship for E. The first component Wmin expresses minimum amount of the work W and the second component ΔW represents a deviation from Wmin interpreted in terms of Dirichlet’s integral applied on the internal potential. Relationships between the internal potential
and E were developed for continuous and piecewise continuous density distributions. The global 3D density model inside an
ellipsoid of revolution was chosen as a combined solution of the 3D continuous distribution and the reference PREM radial
piecewise continuous profile. All the estimates of E were obtained for the spherical Earth since the estimated (from error
propagation rule) accuracy σE of the energy E is at least two orders greater than the ellipsoidal reduction and the contribution of lateral density inhomogeneities
of the 3D global density model. The energy E contained in the 2nd degree Stokes coefficients was determined. A good agreement
between E = EGauss derived from Gaussian distribution and other E, in particular for E = EPREM based on the PREM piecewise continuous density model and E-estimates derived from simplest Legendre-Laplace, Roche, Bullard
and Gauss models separated into core and mantle only, suggests the Gaussian distribution as a basic radial model when information
about density jumps is absent or incomplete. 相似文献
16.
The influence of the four different methods of measuring Lg amplitude, and the selection of different geometrical attenuation
coefficient ζ-values (=5/6 or 1) on the determination ofγ value of Lg wave are discussed.γ=0.0034±0.0001km−1 (when ζ=5/6) for six eastern provinces is redetermined. The revised magnitude calibration function ofm
Lg (mxh),q
E (Δ)=(5/6)logΔ+0.00147Δ+1.81 is deduced.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 171–178, 1991.
Projects sponsored by the Chinese Joint Seismological Science Foundation. 相似文献
17.
We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver–Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets. 相似文献
18.
ＳｔｕｄｙｏｆｃａｌｉｂｒａｔｉｏｎｆｕｎｃｔｉｏｎｆｏｒｓｕｒｆａｃｅｗａｖｅｍａｇｎｉｔｕｄｅｏｆＤＫ１ｓｅｉｓｍｏｇｒａｐｈｓＦＥＮＧＸＵＥ（薛峰）ＹＯＮＧＺＨＡＯ（赵永）ＣｅｎｔｅｒｆｏｒＡｎａｌｙｓｉｓａｎｄＰｒｅｄｉｃｔｉｏｎ，Ｓｔａｔ... 相似文献
19.
随着地震勘探目标复杂化和精细化程度的提高以及"两宽一高"等采集技术的广泛应用,当前地震数据采集的时间越来越长、成本越来越高.针对此问题,本文基于压缩感知理论开展了地震数据高效采集方法的改进和探索研究.根据波动方程解的一般表示式,从波场传播的角度给出了地震数据具有稀疏性的数学物理依据及寻找适应地震数据稀疏变换的一般方案;在稀疏性先验信息的指导下,发展了具有"蓝色噪声"频谱特征的改进的分段采样方法,并基于最优化理论提出了地震数据重建方法.地震数据的稀疏性理论、稀疏约束下的高效采集方法以及地震数据的重建方法构成了相对完善的地震数据高效采集理论.把该理论用于指导地震数据采集,即利用稀疏约束的随机采样方法改变常规规则密集测网中炮点和检波点(或二者之一)的分布,设计了三种随机且均匀的高效采集测网,提出了利用相应测网获取的地震数据重建为常规规则密集测网地震数据的针对性方案,并使用重建精度、高效采集数据的直接成像和重建后再成像的结果对比证明了上述重建方案的有效性.基于Marmousi模型的高效采集试验检验了本文构建的基于稀疏约束的地震数据高效采集方法理论框架在提高当前地震数据采集效率、降低勘探成本上的优势以及方法的有效性和可行性. 相似文献
20.
Liu XiaoHong Shao XueMei Wang LiLi Zhao LiangJu Wu Pu Chen Tuo Qin DaHe Ren JiaWen 《中国科学D辑(英文版)》2007,50(7):1076-1085
In the reconstruction of past climate using stable carbon isotope composition (δ13C) in tree ring, the responses of the stable carbon composition (δ13C) of multiple tree species to environmental factors must be known detailedly. This study presented two δ13C series in annual tree rings for Chinese hemlock (Tsuga chinensis Pritz) and alpine pine (Pinus densata Mast), and investigated the relationships between climatic parameters and stable carbon discrimination (Δ13C) series, and evaluated the potential of climatic reconstruction using Δ13C in both species, in a temperate-moist region of Chuanxi Plateau, China. The raw δ13C series of the two species was inconsistent, which may be a result of different responses caused by tree's inherent physiological differences. After removing the low-frequency effects of CO2 concentration, the high-frequency (year-to-year) inter-series correlation of Δ13C was strong, indicating that Δ13C of the two tree species were controlled by common environmental conditions. The Δ13C series of the species were most significantly correlated with temperature and moisture stress, but in different periods and intensity between the species. During the physiological year, the impacts of temperature and moisture stress on Δ13C occur earlier for Chinese hemlock (previous December to February for moisture stress and February to April for temperature, respectively) than for alpine pine (March to May for moisture stress and April to July for temperature, respectively). In addition, in temperatemoist regions, the control on Δ13C of single climatic parameter was not strongly dominant and the optimal multiple regressions functions just explained the 38.5% variance of the total. Therefore, there is limited potential for using δ13C alone to identify clear, reliable climatic signals from two species. 相似文献