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地震传感器在地震学研究与防震减灾领域应用广泛,数量众多,将其测量量值溯源到国际单位,能够保证测量结果准确和统一。文中对地震传感器测量量值进行量值溯源的必要性进行了叙述,说明了地震传感器的量值单位与国际标准单位的关系。对地震传感器量值溯源的途径以及与校准之间的联系进行了阐述。以力平衡加速度计为例对地震传感器的工作原理进行了说明。参照有关的国际标准,研究了基于正弦逼近法的地震传感器绝对法校准的技术要求,并给出了量值溯源框图,为建立地震传感器的量值溯源体系提供了技术依据。最后对低频振动校准的技术发展方向也作了阐述。 相似文献
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《地球物理学进展》2015,(3)
地震计标定的一项重要内容是幅度响应的测量,一般采用电测法.目前,国内地震计应用者普遍采用阶跃标定或正弦标定的方法.本文提出了一种利用宽频带信号标定地震计的新方法:改进型伪随机二进制标定方法.在低频段,我们用伪随机二进制信号作为标定输入,在高频段,用一种新设计的信号作为标定输入.采用此方法,通过低频段和高频段两个测试实验可快速且准确的测量地震计在0.003 Hz到100 Hz上的幅度响应.实验分别耗时1048秒和204秒,幅度响应测试的频点间隔分别为0.0038Hz和0.49Hz.而且,标定信号形式简单,用简单的电路就可生成.通过与阶跃、正弦标定结果对比表明采用此方法测量地震计幅度响应时,其相对误差在小于2 Hz的频段上小于1%,在大于2 Hz的频段上小于2%.此方法与正弦标定相比,减少了实验耗时;与阶跃标定相比,增大了可测量的频带范围;与单纯利用伪随机二进制信号的方法相比,提高了在高频段测量结果的准确度.此外,其对幅度响应高频段宽度很窄的高峰的识别效果尤为显著. 相似文献
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对测氡仪器进行定期校准是保证测量结果准确性和可靠性的关键。基于用国际公认的计量传递仪器AlphaGUARD P2000F作为氡气溯源仪器及其自带水氡测量组件对三套DDL-1型电离法测氡仪使用水中溶解氡进行校准实验。实验结果和用固体氡源校准三套仪器的结果与仪器出厂校准结果进行对比,两种校准方法的K值相对误差均小于5%,达到目前地震监测氡观测技术要求。实验结果表明,水中溶解氡代替固体氡气源校准,可以解决目前固体氡源校准中存在的运输困难、维修技术要求高、国家环保部门监管严格等问题,为地震氡观测仪器校准技术找到了一种新的途径。 相似文献
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《世界地震译丛》2017,(3)
提出了一种利用加速度记录图中的体波初动与高频振幅峰值的到时差(T_(op))测量地震震级M的简单方法。用这种方式测量,我们发现,对于5≤M_W≤7的地震M_W与2logT_(op)成正比,如果T_(op)与震源尺度成正比并且应力降量级不变,这与理论结果相一致。使用高频(2Hz)数据,M_W与M_(T_(op))(根据T_(op)估计的M)之间的均方根(rms)残差约为0.5个震级单位。在2~16Hz通带中高频数据的均方根残差,均匀地小于从较低频数据获得的值。T_(op)的值与震中距弱相关,在震中距200km范围内可以忽略这种相关性。该算法对2011年日本东北地震的回顾性应用,在该地震发震时刻之后120s内做出M9.0的最终震级估算。我们由此得出结论,高频(2Hz)加速度记录的T_(op)值,在发生特大地震时对地震预警很有价值。 相似文献
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将多通道相关分析方法用于宽频带地震仪的自噪声检测,测量分析了Reftek 130、130 B和130 S三种地震数据采集器的自噪声检测结果以及14套Reftek 130 S连接Guralp CMG-3T地震计的自噪声一致性检测结果,同时给出了地震计的三轴正交性估计.结果表明:Reftek数据采集器设置为普通增益时在0.3 Hz以上频段自噪声高于Guralp CMG-3T地震计自噪声,设置为32倍高增益时在测量频段远低于地震计自噪声;测量的多台Guralp CMG-3T地震计自噪声结果在不同频段一致性差异较大,垂直向分量0.3 Hz以下频段可作为一致性比对参考频段,采集配置选择普通增益时0.3~2 Hz频段可作为数据采集器一致性比对参考频段;Guralp CMG-3T地震计三轴正交性误差估计平均在0.5°以内. 相似文献
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本文采用多通道相关分析方法测量并分析研究了国内地震观测常用的6种进口地震数据采集器的自噪声.结果表明:6种进口地震数据采集器无论在普通增益还是高增益模式下,当频带范围处于1 Hz以下时,自噪声均低于NLNM低噪声模型(灵敏度按750 V·s/m换算);在低增益模式下,当频带范围处于1 Hz以上时,各数据采集器的自噪声与NLNM低噪声模型高低交错,须根据观测目的谨慎使用;Q330HRS和Reftek-130/130S型数据采集器的高增益模式较适合测量宽频带地震计的自噪声. 相似文献
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一、问题的提出 目前国内使用的电感法地应力测量到底能够对不同震级的地震在多大范围内测量到多大的前兆异常变化?它的最大控制距离是多少?这是我们在于报地震时常常碰到的,也是目前许多同志在研究的一个问题。毛主席教导我们:“要去掉我们党内浓厚的盲目性,必须提倡思索,学会分析事物的方法,养成分析的习惯。”如果我们不加思索地认为相隔几千公里的地方有一个四级地震也能够有异常反映,那么这种对应或予报究竟有多少道理,是否符合客观实际,就需要认真推敲了。因此,探讨现有仪器的控制距离,对找寻前兆与地震的确切的物理联系是有益的。 在这里我们是用一个弹性力学中无限平面上小圆孔受均布内压问题,通过求震源力的方法来解决我们所要讨论的问题。 相似文献
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《Journal of Atmospheric and Solar》2002,64(15):1623-1629
Pyrgeometers are used to measure longwave terrestrial radiation. Regular pyrgeometer calibration against an internationally recognized standard is required in order to measure the longwave radiation consistently at different sites around the globe. At present, there is no internationally recognized standard to calibrate pyrgeometers. A well-characterized blackbody is, however, an accepted approach. This paper describes a method of establishing a precise blackbody reference and using it to calibrate a group of four transfer reference pyrgeometers. The group is then deployed outdoors to evaluate the precision of the blackbody calibration. The results from the outdoor data shows that the percentage mean-square-error of each transfer reference pyrgeometer is 0.12%, 0.07%, 0.46%, and 0.10% with a resultant percentage root-mean-square of 0.43%. The errors are calculated with respect to the average of the irradiance readings of the transfer reference pyrgeometers. To minimize the number of transfer reference pyrgeometers and to allow more space for calibrating test pyrgeometers, a sub-set of the transfer reference pyrgeometers is then used to calibrate a test pyrgeometer outdoors. The calibration of the test pyrgeometer resulted in reducing its error from +4.00% to ±0.32% with respect to the irradiance measured by the sub-set of the transfer reference pyrgeometers. The outdoor calibration method can minimize the calibration cost resulting from using the lengthy and costly blackbody calibration because many pyrgeometers can be calibrated at the same time.Appendix A shows a diagram that describes the paper's concept. 相似文献
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本文介绍了改制后ＤＤ－１型地震仪放大器、稳频器、稳压器的工作原理，简述了其主要技术指标，并给出了仪器的标定和试验结果．ＤＤ－１型短周期地震仪改制。是为了使仪器更好地适应地震预报与基础研究的观测需要而进行的。将改制后的仪器经室内测试标定和实际观测，并与沈阳地震基准台记录进行对比分析，证明改制后的ＤＤ－１型短周期地震仪主要技术指标与工作性能已达到规范的要求． 相似文献
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《Advances in water resources》1998,21(7):591-604
A heuristic algorithm is presented for problems which are formulated to find an optimal groundwater remediation strategy with constraints on confined groundwater flow and contaminant transport. The problem is simplified by decoupling the transport constraints from the hydraulic constraints to produce a linear hydraulic control optimization problem. The solution is obtained by an iterative process in which the constraints on hydraulic gradient are updated, using information from transport simulation, and the hydraulic control problem is solved repeatedly. In effect, the transport simulation is used to calibrate the head difference constraint values of the hydraulic control problem. The algorithm is described in detail and its convergence is demonstrated on several examples. The advantages and limitations of the algorithm are discussed. 相似文献
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年剂量测量是释光和电子自旋共振测年的关键之一。厚源α-计数仪(简称TSAC)是年剂量测量中的常用仪器。通过不同标准源的标定对比实验,对美国Daybreak公司582,583型低本底厚源α-计数仪的高压值(HV)和积分甄别器阈值(DISC)进行了标定。同时,对测量过程中的诸多影响因素如被测样品的氡逃逸、粒度、含水量、颜色以及ZnS闪烁屏的密度、测量时间等开展了初步的实验研究,并根据实验结果提出了针对本型号仪器在实际测量时的改进措施,以提高厚源α-计数仪的测量精度 相似文献
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如何精确地测定地震观测系统的频谱特性,是测震学中的一项重要课题。目前所用的分段测量和计算的方法,不仅需要一定的仪器设备,而且还忽略了机(拾震器)——电(放大装置)接口部分的相互作用和影响。因此,不能获得精确的幅频特性,也不能用实验直接得出相位特性。 本文通过傅里叶变换推导出计算与实测任何一种测震系统频谱特性的方法————TS方法,其中用三角波与阶跃函数作为测试信号。 如果对测试信号的动态响应已知,则所研究的系统频谱特性可立即求得。 相似文献
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The use of spatial patterns of flood inundation (often obtained from remotely sensed imagery) to calibrate flood inundation models has been widespread over the last 15 years. Model calibration is most often achieved by employing one or even several performance measures derived from the well‐known confusion matrix based on a binary classification of flooding. However, relatively early on, it has been recognized that the use of commonly reported performance measures for calibrating flood inundation models (such as the F measure) is hampered because the calibration procedure commonly utilizes only one possible solution of a wet/dry classification of a remote sensing image [most often acquired by a synthetic aperture radar (SAR)] to calibrate or validate models and are biased towards either over‐prediction or under‐prediction of flooding. Despite the call in several studies for an alternative statistic, to this date, very few, if any, unbiased performance measure based on the confusion matrix has been proposed for flood model calibration/validation studies. In this paper, we employ a robust statistical measure that operates in the receiver operating characteristics (ROC) space and allows automated model calibration with high identifiability of the best model parameter set but without the need of a classification of the SAR image. The ROC‐based method for flood model calibration is demonstrated using two different flood event test cases with flood models of varying degree of complexity and boundary conditions with varying degree of accuracy. Verification of the calibration results and optional SAR classification is successfully performed with independent observations of the events. We believe that this proposed alternative approach to flood model calibration using spatial patterns of flood inundation should be employed instead of performance measures commonly used in conjunction with a binary flood map. © 2013 California Institute of Technology. Hydrological Processes © 2013 John Wiley & Sons, Ltd. 相似文献
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对解释模型进行评价以及如何选择合适的解释模型是复杂岩性解释中非常重要的问题。本文应用统计学的理论以及非线性优化技术,系统研究了在线性约束条件下对储层参数的置信区域和误差大小进行估计的问题,通过将梯度投影算法与奇异值分解技术相结合的方法给出了计算储层参数置信区域与误差大小的公式,以及对复杂岩性解释模型的稳定性和可靠性进行合理评价的具体方法。最后通过数值计算实例研究了一种能够有效提高解释模型稳定性和可靠性的措施,数值计算结果证明解释模型响应函数的最小非零奇异值大小是影响稳定性和可靠性的一个重要参数,当最小非零奇异值较大时,模型的稳定性往往较好,否则较差,因此通过对解释模型进行适当组合并选取最小非零奇异值较大的综合解释模型,可以大大提高其稳定性和可靠性。 相似文献
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In well velocity surveys made to calibrate Sonic (CV) Logs the calibration survey uses frequencies around 50 Hz whereas the Sonic Logging tool uses frequencies around 20 kHz. There thus exists the possibility of making a direct measure of velocity dispersion. In any one survey the disturbing factors, both instrumental and operational, will often mask any dispersive effect that might exist. Consequently this paper reports on a statistical analysis of the velocity differences resulting from calibration surveys and Sonic logs. Only Borehole Compensated Sonic Logs were used. Four areas were investigated: the North Sea, Abu Dhabi, Libya and Alaska. After rejecting logs and calibration records which were obviously in error there remained 424000 feet (about 130 km) of usable log distributed throughout 66 wells. The four areas were analysed separately and in no case was the estimated dispersion significantly different from zero. However, the mean values did correlate with lithology from (? 0.17 ± 0.18)% for the essentially carbonate section in Abu Dhabi to (+ 0.45 ± 0.25)% for the sand-shale section in Alaska, a positive sign meaning that the higher frequencies travelled faster. Except for Alaska the calibration surveys were made with a wall-clamp geophone, and for these areas amplitude measurements were made. After suitable corrections estimates of the absorption parameter Q were obtained. These varied from 20 to 200 with mean values of 63 for Libya, 70 for Abu Dhabi and 88 for the North Sea (excluding the Tertiary). If, as is usually assumed, the absorption mechanism is linear and is described by a Q which is independent of frequency, then these values would necessarily imply dispersion of several percent. As instanced above no such dispersion was observed. It is possible that the expected dispersion was compensated for by invasion of the mud filtrate into the borehole walls, but it is more likely that the absorption mechanism was substantially non-linear. 相似文献
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《中国科学:地球科学(英文版)》2017,(5)
Gradient based UCODE_2005 and data assimilation based on the Ensemble Kalman Filter(EnKF) are two different inverse methods. A synthetic two-dimensional flow case with four no-flow boundaries is used to compare the UCODE_2005 with the Ensemble Kalman Filter(EnKF) for their efficiency to inversely calculate and calibrate a hydraulic conductivity field based on hydraulic head data. A zonal, random heterogeneous conductivity field is calibrated by assimilating the time series of heads observed in monitoring wells. The study results indicate that the two inverse methods, UCODE_2005 and EnKF, could be used to calibrate the hydraulic conductivity field to a certain degree. More available observations and information about the conductivity field, more accurate inverse results will be obtained for the UCODE_2005. On the other hand, for a realistic zonal heterogeneous hydraulic conductivity field, EnKF can only efficiently determine the hydraulic conductivity field at the first several assimilated time steps. The results obtained by the UCODE_2005 look better than those by the EnKF. This is possibly due to the fact that the UCODE_2005 uses observed head data at every time step, while EnKF can only use observed heads at first several steps due to the filter divergence problem. 相似文献