自标定法在低频振动传感器参数校准中的应用

介绍了自标定法在低频振动传感器参数校准中的应用,阐述了该方法用于校准的理论依据及适用范围,并将自标定法获得的校准数据和用振动标准装置获得的校准数据进行了比较,通过实测数据证实了自标定法的标定结果在一定的频率范围内是可信的.由于自标定法不需要复杂的标定设备,简单方便,因此具有较好的实用价值.最后,分析了自标定法的误差来源...     

上海台阵标定方法的对比研究

本文介绍了基于台阵标定理论建立的上海台阵标定数据库;提出了最近标定和平均标定的方法。通过典型的地震事件对新方法进行了校验,结果表明最近标定和平均标定法的标定效果都比较好,有效的提高了地震定位精度。     

适用于标定机电换能器和地震仪的一种互易法

本文讨论了一种外加机械负载来标定电动式机电换能器和地震仪的互易法.介绍了互易法的原理.并对北京宣武测振仪器厂生产的电动换能器和电动地震仪进行了标定.结果表明, 互易法标定与振动台标定符合较好.      

一种地应力连续测量系统的标定方法

在地应力连续测量方法"渗透率法"的基础上,设计了一种对观测系统进行标定的方法。经对原有推导结果进行数学转换,给出了新的计算公式以及其中有关参数的测定方法。结果表明,经过标定之后,原有的连续相对测量方法可转换为抗干扰性强、灵敏度高、经济简便且物理意义确切的有效正应力连续测量方法。     

LaCoste&Romberg航空重力仪K因子的动态标定及其特性研究

摆杆尺度因子(K因子)是反映LaCoste&Romberg航空重力仪线性响应特性的最重要参数.利用基于地面参考数据的外部标定法和基于交叉点不符值的内部标定法分别对其进行了标定,实测数据分析表明,K因子的内、外部标定结果非常一致,且利用新K因子计算的空中重力扰动,其精度较采用出厂值提高了0.2～0.4 mGal.内部标定法具有较好的实际应用价值.研究了K因子与滤波尺度的相关性,表明重力仪可能为一非线性响应系统,即K因子的大小与摆杆速度的变化有关.     

最小二乘法分段拟合标定反应谱方法

反应谱的标定方法直接关系到反应谱特征参数的确定,合理的反应谱标定方法得到的设计反应谱能够真实地表达地震动的特性,是确定地震动输入的重要环节。提出了基于坐标变换的最小二乘法分段拟合方法,通过对汶川大地震不同场地典型强震记录反应谱的标定,对比了反应谱不同的标定方法,根据反应谱标定图形的对比及误差分析认为,最小二乘法分段拟合方法是操作简便且标定结果合理的反应谱标定方法。     

人工值守台数字化地震仪标定原理

推导了人工台数字化地震仪的分段标定公式，提出数字化记录系统的微分近似标定和拾震器阻尼衰减法标定的方法，并提供了不同短周期地震仪与数字化地震仪并行的藕合方式和标定计算公式。     

大位移拾振器线性度的标定

至今仍未见一种有效的标定方法和设备，可直接标定大位移拾振器的线性度。本文介绍了一种标定超低水平向大位移拾振器线性度的回转标定法，以供讨论。     

负电阻反馈式地震计的自标定技术

针对负电阻反馈式地震计缺乏标定线圈无法进行现场标定的问题,研制了一种可内置于地震计内部的相对标定系统,该系统在信号线圈内接入阶跃电流,通过电磁感应对摆体施加阶跃加速度激励,测量仪器的暂态响应输出求解得到地震计的传递特性.文章首先推导和建立了自标定模型,设计和制作标定电路,采用L-M法求解地震计的传递函数,分别对三台样机进行了自标定和振动台标定实验.实验表明两种标定方法的结果较为一致,相对误差在5%以内,证明了这种自标定技术的有效性,实现了该类型地震传感器的灵活标定.     

地震前兆观测仪器的校准与标定辨析

对地震行业常用的"标定"术语和计量领域的"校准"术语之间的异同进行分析,同时提出目前"标定"在保障地震仪器观测质量中的作用及限制,最终指出并强调了"校准"在确保地震仪器观测量值单位统一、量值准确的法定地位。     

新型气氡仪三种常用校准方法的差异性比测分析

为保证气氡测量结果准确性和可靠性,需对测氡仪器进行定期校准。应用目前我国地震系统内常用的三种校准方法：标准仪器校准法、RN-FD循环式氡气源校准法及固体氡气源校准法,对入网新型气氡仪进行校准方法比测。得出结果认为：循环式常压取源方式更接近新型数字化氡观测仪器的正常工作方式;标准仪器校准法是目前正在使用的几种校准方法中系统误差最小、校准效率最高、维护成本最低的方法;RN-FD循环式氡气源校准法和固体氡气源校准法均为标准物质传递方法,该方法存在诸多困难及不便(如放射性固体源运输、人员技术及环保监管等)影响仪器校准的及时性。通过分析这三种校准方法在原理、使用操作方法等方面的差异,讨论它们对校准结果准确度的影响,为新型仪器的校准操作规程(规范)的编写及实施提供参考。     

山东地震台网“十五”与“九五”期间地震定位方法对比研究

应用山东地震台网数据,对比研究山东台网“十五”与“九五”期间地震定位参数,初步认为：山东台网“十五”期间定位与“九五”期间定位参数基本一致,“十五”期间中单纯型法定位适用于网内、网缘和网外所有近震和远震,是“十五”期间中最好用的一种定位方法。     

On-site calibration of air-coil sensor for transient electromagnetic exploration

This paper proposes a time-domain fitting method for on-site calibration of the air-coil sensor. The air-coil sensor has been widely used in transient electromagnetic exploration. Due to limited bandwidth of the coil, the output signal is distorted, causing a phenomenon known as the transition process. To accurately measure the magnetic field from the output signals, the relationship between the coil induced electromotive force and the output voltage must be confirmed by on-site calibration, which requires high calibration accuracy and demands simple operation, portable equipment, and adaptability to the environment. Conventional frequency response methods, however, requires a uniform magnetic field with various frequencies to obtain the frequency response curve of the air-coil sensor. The time to acquire the signal correlates with the number of test frequencies, and the equipment used to generate a uniform magnetic field must be tailored to the shape of the air-coil sensor under test. This paper constructs a relationship between the calibration file and the zero-input response of the air-coil sensor and designs an optimization algorithm to suppress the soil eddy current effect. This on-site calibration method lifts the dependence on the uniform calibration field and reduces significantly the time required for calibration. The calibration source can be generated by cutting off the voltage source in parallel to the calibration coil, which greatly reduces the cost of the signal generator and provides a better solution for realizing the embedded self-test devices. Experimental results show that the proposed method effectively improves the calculation accuracy of the apparent resistivity.     

Simultaneous perturbation stochastic approximation for tidal models

The Dutch continental shelf model (DCSM) is a shallow sea model of entire continental shelf which is used operationally in the Netherlands to forecast the storm surges in the North Sea. The forecasts are necessary to support the decision of the timely closure of the moveable storm surge barriers to protect the land. In this study, an automated model calibration method, simultaneous perturbation stochastic approximation (SPSA) is implemented for tidal calibration of the DCSM. The method uses objective function evaluations to obtain the gradient approximations. The gradient approximation for the central difference method uses only two objective function evaluation independent of the number of parameters being optimized. The calibration parameter in this study is the model bathymetry. A number of calibration experiments is performed. The effectiveness of the algorithm is evaluated in terms of the accuracy of the final results as well as the computational costs required to produce these results. In doing so, comparison is made with a traditional steepest descent method and also with a newly developed proper orthogonal decomposition-based calibration method. The main findings are: (1) The SPSA method gives comparable results to steepest descent method with little computational cost. (2) The SPSA method with little computational cost can be used to estimate large number of parameters.     

Faults有限元程序在Windows平台上的移植

Faults有限元软件综合高程、热流、断层等多个地球物理场参数,相较于Ansys、Adina等商用有限元软件能更好的处理断层的摩擦机制,因此Faults有限元软件在地学模拟中有独特优势.目前使用的Faults软件基于IBM科学与工程数学库(ESSL),使用环境较为苛刻,使用不便,需要移植源代码.利用Linpack免费数...     

台阵地震计程控化正弦标定系统设计

为满足台阵地震计标定要求,通过对程控化标定测控仪和标定测控软件的研究,采用一种适用于台阵地震计的程控化正弦标定方法,对中国地震局地球物理勘探中心负责管理的台阵地震计进行标定。台阵地震计标定实验结果显示,采用程控化正弦标定方法,在缩短标定时长、提高标定效率方面具有显著效果。     

基于无线模块的地下流体井水位校测装置

水位校测对提高流体观测网的运行质量与监测效能具有重要意义,是规范井水位观测技术的关键环节。基于电极法的水位校测装置广泛应用于地震流体观测台站,其校测精度受到装置本身、使用者熟练程度等因素影响。为提高水位校测装置的测量精度,设计一种地震流体井下水位校测装置,采用多电极探针的校测探头,并设计读数模块,将各电极接触水面的电信号通过无线模块传输,触发蜂鸣器报警和指示灯显示。该设计方案的可行性在实验中得到验证。     

正弦标定波形组起始点的自动判别方法

地震观测系统标定的完整含义包括系统特性的测定和系统灵敏度的测定。系统灵敏度标定的最佳方法是振动台标定。由于地震台站不具备振动台标定的条件,因而目前普遍采用电动式力激励稳态正弦波标定的方法,即由一组正弦标定波形自动计算出幅频特性,并得到系统灵敏度。要实现计算程序的自动化,那么正弦标定波形组起始点的判断尤其重要。文章结合滑动短长平均法和AIC算法,提出了一种自动判别正弦标定波形组起始点的方法。     

Calibration of Parameter Fields Consisting of Multiple Statistical Populations

If a parameter field to be calibrated consists of more than one statistical population, usually not only the parameter values are uncertain, but the spatial distributions of the populations are uncertain as well. In this study, we demonstrate the potential of the multimodal calibration method we proposed recently for the calibration of such fields, as applied to real-world ground water models with several additional stochastic parameter fields. Our method enables the calibration of the spatial distribution of the statistical populations, as well as their spatially correlated parameterization, while honoring the complete prior geostatistical definition of the multimodal parameter field. We illustrate the implications of the method in terms of the reliability of the posterior model by comparing its performance to that of a "conventional" calibration approach in which the positions of the statistical populations are not allowed to change. Information from synthetic calibration runs is used to show how ignoring the uncertainty involved in the positions of the statistical populations not only denies the modeler the opportunity to use the measurement information to improve these positions but also unduly influences the posterior intrapopulation distributions, causes unjustified adjustments to the cocalibrated parameter fields, and results in poorer observation reproduction. The proposed multimodal calibration allows a more complete treatment of the relevant uncertainties, which prevents the abovementioned adverse effects and renders a more trustworthy posterior model.     

Calibrating Lattice Boltzmann flow simulations and estimating uncertainty in the permeability of complex porous media

A common way to simulate fluid flow in porous media is to use Lattice Boltzmann (LB) methods. Permeability predictions from such flow simulations are controlled by parameters whose settings must be calibrated in order to produce realistic modelling results. Herein we focus on the simplest and most commonly used implementation of the LB method: the single-relaxation-time BGK model. A key parameter in the BGK model is the relaxation time τ which controls flow velocity and has a substantial influence on the permeability calculation. Currently there is no rigorous scheme to calibrate its value for models of real media. We show that the standard method of calibration, by matching the flow profile of the analytic Hagen-Poiseuille pipe-flow model, results in a BGK-LB model that is unable to accurately predict permeability even in simple realistic porous media (herein, Fontainebleau sandstone). In order to reconcile the differences between predicted permeability and experimental data, we propose a method to calibrate τ using an enhanced Transitional Markov Chain Monte Carlo method, which is suitable for parallel computer architectures. We also propose a porosity-dependent τ calibration that provides an excellent fit to experimental data and which creates an empirical model that can be used to choose τ for new samples of known porosity. Our Bayesian framework thus provides robust predictions of permeability of realistic porous media, herein demonstrated on the BGK-LB model, and should therefore replace the standard pipe-flow based methods of calibration for more complex media. The calibration methodology can also be extended to more advanced LB methods.