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试论水氡观测中仪器K值的使用 总被引:1,自引:0,他引:1
在水氡观测仪器标定中,关于标定K值的使用方法,《规范》规定:当新一原K值相对偏差小于5%时继续管用原K值。但在实际观测中,这样容易导致误差积累。本文从日常观测中出现的几个问题分析,认为在每年仪器标定后,无论标定的仪器新一原K值相对偏差是否大于5%,都应采用新K值。 相似文献
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几年来的实践表明,使用Rn-150型固体源对常用的水氡仪器进行标定具有明显的优点:操作简便,标定精度高,误差明显地小于使用液体源的标定结果。但是,如果在标定中对具体环节注意不够,造成观测与标定条件不一致,则会产生明显的标定误差。为此本文分别对标定中干燥剂、真空表、乳胶管使用等环节进行实验研究,搞清了各个环节对K值的不同影响。 相似文献
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高阶脉冲标定器及观测系统幅频特性 总被引:1,自引:1,他引:0
在前阶段理论研究的基础上,搜寻到了几种高阶脉冲波形,其频谱的低频分量平坦,高频分量更丰富。据此制成功能完善,性能优良的标定器。用高阶脉冲标定器产生的标定电流来激励拾震器,使观测系统产生相应的响应,由计算机采集该响应,并进行富氏变换及相关运算。由此可得到系统的幅频特性K(ω),为暂态标定结果。对于速度 平坦型观测系统暂态标定与稳定态标定所得的特性曲线完全重合,即标定精度相同。 相似文献
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形变标定格值计算软件 总被引:1,自引:1,他引:0
为提高地壳形变观测仪器格值标定的真实性、准确性和可靠性,根据《地震前兆台网运行管理办法》和《地震前兆台网形变观测与运行工作细则》,针对不同测项、不同仪器标定的规范要求及特点,应用Visual Basic语言编制了格值计算软件。本文主要介绍了软件的使用、格值计算、误差检查方法,结果以全国形变台网中心推荐的Word格式保存。对水管仪、水平摆、垂直摆仪直接从原始文件读取数据,提高了标定精度,实现了格值标定的半自动化。本软件已应用于河北省地震前兆数字化台站工作。 相似文献
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从标定前一天和标定当天的地形变前兆数据变化趋势入手,在分析当天数据结构的基础上采用最小二乘法原理,提出了一种计算数采改正值的新方法。经典型实例计算表明,该方法精度较高,效果明显。并对误差的来源作了进一步的分析。 相似文献
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The subject of environmental engineering is currently of great interest. Field experiments as well as numerical models have proven their worth in this research field. An introduction to hydrodynamic modelling, coupled to the modelling of vegetation biomass is described. The developed Strive (STream RIVer Ecosystem) model is set up in the Femme (‘Flexible Environment for Mathematically Modelling the Environment’) environment and has already proven its worth in a large number of calculations (De Doncker et al., 2006 , 2008b ). Discharges and water levels are modelled together with modelling of electrical conductivity (EC). Extensive measurement campaigns are carried out to collect a large number of observations and calibration of the model is based on this data set. Furthermore, calibration methods and the discussion of this process are displayed. As a result, it is seen that the developed Strive model can model both, hydrodynamic and ecological processes, in an accurate way. The work highlights the importance of detailed determination of Manning's coefficient, dependent on discharge and amount of biomass, as an important calibration parameter for accurate modelling. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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When measured earthquake accelerations are used as a basis for structural design, then acceleration errors of a few per cent are usually acceptable. However a number of tasks in structural design, and in earthquake engineering research, require measured accelerations with errors limited to a few parts per thousand. Such tasks include those which call for the calculation of angular accelerations, the comparison of acceleration spectra or the calculation of relative displacement Accurate accelerations may be obtained from existing accelerographs by applying the results of an accurate static calibration to an accelerogram, and then applying corrections for the effects of accelerometer resonance. This paper concentrates attention on the correction of static errors, including sensing direction errors and cross-axis interaction errors. For completeness there is a brief discussion of dynamic errors, which depend on accelerometer periods and dampings. It is concluded that earthquake accelerations may be obtained with errors of not much more than 0·001 g, the resolution of a typical accelerograph, at least for periods greater than 0·2 sec. When the accelerations have shorter periods, larger errors may arise due to the limited accuracy of the corrections for dynamic errors The static calibration of accelerographs, and the corresponding record correction procedures, are illustrated by application to the M.O.2 accelerograph. 相似文献
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Regional frequency analysis is an important tool in estimating design flood for ungauged catchments. Index flood is an important component in regionalized flood formulas. In the past, many formulas have been developed based on various numbers of calibration catchments (e.g. from less than 20 to several hundred). However, there is a lack of systematic research on the model uncertainties caused by the number of calibration catchments (i.e. what is the minimum number of calibration catchment? and how should we choose the calibration catchments?). This study uses the statistical resampling technique to explore the impact of calibration catchment numbers on the index flood estimation. The study is based on 182 catchments in England and an index flood formula has been developed using the input variable selection technique in the data mining field. The formula has been used to explore the model uncertainty due to a range of calibration catchment numbers (from 15 to 130). It is found that (1) as expected, the more catchments are used in the calibration, the more reliable of the models developed are (i.e. with a narrower band of uncertainty); (2) however, poor models are still possible with a large number of calibration catchments (e.g. 130). In contrast, good models with a small number of calibration catchments are also achievable (with as low as 15 calibration catchments). This indicates that the number of calibration catchments is only one of the factors influencing the model performance. The hydrological community should explore why a smaller calibration data set could produce a better model than a large calibration data set. It is clear from this study that the information content in the calibration data set is equally if not more important than the number of calibration data. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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The utilisation of sound backscattered from sediments in suspension, to measure profiles of near-bed particle size and concentration, has been gaining increasing acceptance and usage by sedimentologists and coastal engineers over the past two decades. To obtain the sediment parameters from the backscattered signal requires an inversion to be conducted on the signal and this necessitates a system calibration. The calibration can be carried out by detailed acoustic and electronic measurements, or alternatively by measuring the backscattering from suspensions with known scattering characteristics. Here, we explore the latter approach and describe in some detail the calibration of a triple frequency acoustic backscatter system. The aim is to provide coastal scientists involved in using acoustics as a tool for sediment transport research, with a clear exposition of the calibration process. Suspensions of glass spheres of varying particle size were used as the calibration scatterers. To interpret the signal backscatter from the suspension of glass spheres a simple model for sphere scattering is presented. The results show that consistent calibration results can be obtained in a relatively simple and robust manner. 相似文献
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This research is part of a larger effort to better understand and quantify the epistemic model uncertainty in dynamic response-history simulations. This paper focuses on how calibration methods influence model uncertainty. Structural models in earthquake engineering are typically built up from independently calibrated component models. During component calibration, engineers often use experimental component response under quasi-static loading to find parameters that minimize the error in structural response under dynamic loading. Since the calibration and the simulation environments are different, if a calibration method wants to provide optimal parameters for simulation, it has to focus on features of the component response that are important from the perspective of global structural behavior. Relevance describes how efficiently a calibration method can focus on such important features. A framework of virtual experiments and a methodology is proposed to evaluate the influence of calibration relevance on model error in simulations. The evaluation is demonstrated through a case study with buckling-restrained braced frames (BRBF). Two calibration methods are compared in the case study. The first, highly relevant calibration method is based on stiffness and hardening characteristics of braces; the second, less relevant calibration method is based on the axial force response of braces. The highly relevant calibration method consistently identified the preferable parameter sets. In contrast, the less relevant calibration method showed poor to mediocre performance. The framework and methodology presented here are not limited to BRBF. They have the potential to facilitate and systematize the improvement of component-model calibration methods for any structural system. 相似文献
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本文讨论了感应式磁力仪标定的最佳方法。定量分析了标定方式的选择、标定线圈最佳尺度和标定中的误差等问题。为标定线圈制作、野外施工和提高标定精度等提供参考 相似文献
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IntroductionWith the time passing by and the environment changing, the characteristics of the components in a seismometer may change a little to some extent because of some certain reasons. Therefore the reliability of a sensor(s output may lower the reliability and a wrong result may also be produced if these changes are not realized and controlled or adjusted in time. Hence, the seismometers must be calibrated either before leaving factory or in use, so as to check the parameters and the cha… 相似文献