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随着三维深部地质填图和含页岩气盆地潜力的评价项目展开,大地电磁方法的重要性越来越突显。大地电磁资料处理和解释中,至今还存在几个挑战性难题,例如阻抗张量旋转、TE和TM模式识别、静态矫正、TE和TM模式选择二维反演问题。从WinGlink软件大地电磁模块出发,使用5种阻抗旋转方法和3种数据圆滑方法处理在内蒙古扎鲁特旗采集的大地电磁数据。以数据质量不同的3个测点的处理结果为依据,对各种旋转方法和圆滑方法进行详细评价,数据极化图显示地下结构模型是复杂的三维结构。对这些方法的比较研究,对三维结构下大地电磁数据处理,特别是对使用WinGlink软件处理大地电磁数据具有重要现实意义。 相似文献
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广义S变换时频域滤波在MT数据处理中的应用 总被引：1，自引：0，他引：1
短时傅里叶变换是建立在稳态信号基础之上,它仅能提供信号的频域信息,对信号的时间分辨能力差。这影响了它在大地电磁测深数据处理中的应用效果。S变换是一种优于短时傅立叶变换的时频分析方法,能够提供信号时-频域信息。利用S变换对大地电磁测深数据进行时频分析,有助于实现大地电磁测深数据噪声的时频-域滤波,从而提高大地电、磁分量数据的频谱分析精度。从广义S变换理论出发,分析了各类波形噪声的时-频域特征及其对大地电磁测深数据的影响。针对大地电磁测深数据处理特点,利用广义S变换得到时频谱,采用时频比值和门槛值方法,研究适合压制电磁噪声的时频滤波器和滤波方法。对实际大地电磁测深数据的处理结果表明这个方法提高了阻抗张量的估算质量,验证了该方法的有效性。 相似文献
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《物探化探计算技术》2017,(3)
为了提高强干扰地区大地电磁测深数据质量、保留大地电磁信号低频段的有用信息,压制大尺度强干扰已刻不容缓。针对矿集区典型的强干扰类型,引入子空间增强方法对大地电磁信号与强干扰进行信噪分离研究。通过计算机模拟常见的大尺度方波和充放电三角波干扰,讨论了子空间增强算法中帧长与特征值判别阈值的最优选取范围,给出了算法流程,并对矿集区实测大地电磁数据进行了信噪分离处理。实验结果表明:该方法是切实可行的,能有效剔除时间域序列中的大尺度强干扰,近源效应得到了有效压制;经处理后,重构的大地电磁信号中包含了更为丰富的细节成分,视电阻率曲线更为光滑、连续,低频段的大地电磁数据质量得到了明显改善。 相似文献
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top-hat变换与庐枞矿集区大地电磁强干扰分离 总被引：1，自引：0，他引：1
作为一种非线性信号处理方法,基于数学形态学的广义形态滤波已经展现出其在大地电磁时间域信号去噪中的作用;然而,广义形态滤波在滤除大地电磁时间域信号中噪声波形的同时,也滤除了时间域信号中包含有用信息的缓变化。针对这一问题,提出一种基于数学形态学top-hat变换的大地电磁时间域噪声压制方案,利用top-hat变换对波峰和波谷的检测能力,采用直线型结构元素,对大地电磁时间域信号进行去噪。用该方法对庐枞矿集区大地电磁实测数据进行处理后,数据的标准差与曲线相似性参数都优于处理前数据,表明所提方法能够去除噪声波形并保留时间域信号的缓变化,恢复受噪声污染的大地电磁时间域信号,提高大地电磁视电阻率曲线的质量。 相似文献
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大地电磁测深勘探方法易受电台、电网、工业游离电流等人为因素干扰,致使资料数据离差大、曲线形态畸变、可信度差.根据噪声对大地电磁测深张量阻抗估算值的影响规律和大地电磁测深远参考技术的应用效果,阐述了远参考技术的一种折中方案,即互参考道方法.选取不同参考距离、不同质量的大地电磁实测数据作为互参考点,通过计算经互参考处理后的大地电磁测深数据得出相干度、信噪比以及卡尼亚电阻率～相位曲线,分析了经互参考道处理后MT资料的效果.结果表明,该方法是有效的,并总结了应用此方法的一些问题. 相似文献
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《世界地质》2021,(3)
通过在北京南中轴强干扰区不同距离处布设6个大地电磁测深试验点,分析受干扰的大地电磁测深数据,总结了城市游散电流对大地电磁测深数据干扰特征,根据干扰特征选择远参考法进行去噪。首先利用同步布设的11个不同距离远参考站分别对测点进行远参考处理,分析单站远参考的局限性,然后提出不同频段最优化组合的多站远参考处理方式。在 0.044 00 Hz、0.044 00～0.005 50Hz和0.005 50～0.000 57 Hz频段分别选取距测点80 km、220 km和360 km处远参考站处理结果,最优化组合得到全频段大地电磁测深曲线。研究表明,城市游散电流对大地电磁测深的主要干扰方式为近场干扰,27 km以外测点数据经多站远参考处理后近场干扰可得到有效压制,实现了数据质量提升的目的,优于单站远参考处理方式。 相似文献
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西方大地电磁测深法理论发展现状 总被引：2，自引：0，他引：2
文章回顾总结了近几年来西方大地电磁测深法在数据处理、正反演等方面所取得的理论研究成果,指出在目前的大地电磁测深法研究中,资料的噪音分析、数据的正反演尤其是多维大地电磁测深法数据正反演研究是最为活跃的研究领域。 相似文献
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基于支撑全国地质灾害研究和服务地质灾害防治的目的,针对全国地质灾害数据库,提出了包括完整性、时效性、准确性、一致性、规范性五个维度为一级指标的评价指标体系,其下涵盖10个二级指标、28个三级指标;利用德尔菲法确定各指标评价权重,并以中部某省地质灾害数据库为例完成其质量评价,结果显示该省地质灾害数据库建设总体情况较好。此次地质灾害数据质量评价体系研究融科学性、实用性、探索性为一体,对于提高全国地质灾害数据库质量,开展基于数据挖掘的地质灾害科学研究,提升数据对全国地质灾害防治支撑能力具有重要意义和作用。 相似文献
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黔北桐梓红花园剖面是华南扬子台地经典的奥陶系剖面之一,其中的湄潭组下部泥页岩段产出大量的腕足类化石。在前人研究的基础上,形态分析显示：红花园剖面湄潭组下部的腕足类化石共有27属,其中以正形贝类Sinorthis的丰度最高,为湄潭组下段腕足动物中的优势类型。此外,Paralenorthis,Desmorthis,Xinanorthis等也比较常见,同为早奥陶世扬子台地近岸浅水环境下Sinorthis动物群的共生腕足分子。通过与黔中乌当地区湄潭组下段的腕足动物组合进行多样性比较,结果显示：桐梓红花园剖面的腕足动物,无论是化石丰度还是形态分异度,都明显高于贵阳乌当地区。两地之间湄潭组沉积环境的差异和研究程度的不同可能是腕足动物化石面貌不一样的主要原因。红花园剖面湄潭组下部腕足动物的多样性迅速增加,为研究华南早奥陶世腕足动物演化史上首次辐射事件提供了新的证据,也为探讨该地质时期黔中古陆南、北缘近岸环境下腕足动物的地理区系划分提供了重要信息。 相似文献
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因围岩质量评价对地下洞室的设计、施工具有重要作用,因此勘察规范对洞室围岩质量评价具有明确的规定。围岩质量评价方法很多,但在勘察阶段,围岩质量的评价结果与实际情况有很多差别。造成这种问题的主要原因是岩体质量评价需要准确而丰富的工程地质数据,而在勘察阶段,洞室围岩的直接数据有限,多为间接数据(物探数据)和推测数据(以地表工程地质测绘数据和钻孔数据为基础进行推测)。根据勘察阶段所获得的工程地质数据,以钻孔中岩心质量与测井数据之间的关系为基础,建立岩体质量与地球物理参数之间的关系,多种地球物理参数对比,可以比较准确地预测目标围岩质量。通过某花岗岩体中钻孔随深度变化的BQ值曲线、RQD曲线、测井曲线和电磁法物探剖面的对比,发现岩体质量与物探数据很难一一对应,但其大致趋势一致。 相似文献
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David J. Delene 《Earth Science Informatics》2011,4(1):29-44
The practice of conducting quality control and quality assurance in the construction of data sets is often an overlooked and
underestimated task of many research projects in the Earth Sciences. The development of software to effectively process and
quickly analyze measurements is a critical aspect of a research project. An evolutionary approach has been used at the University
of North Dakota to develop and implement software to process and analyze airborne measurements. Development over the past
eight years has resulted in a collection of software named the Airborne Data Processing and Analysis (ADPAA) package which
has been published as an open source project on Source Forge. The ADPAA package is intended to fully automate data processing
while incorporating the concept of missing value codes and levels of data processing. At each data level, ADPAA utilizes a
standard ASCII file format to store measurements from individual instruments into separate files. After all data levels have
been processed, a summary file containing parameters of scientific interest for the field project is created for each aircraft
flight. All project information is organized into a standard directory structure. ADPAA contains several tools that facilitate
quality control procedures conducted on instruments during field projects and laboratory testing. Each quality control procedure
is designed to ensure proper instrument performance and hence the validity of the instrument’s measurement. Data processing
by ADPAA allows edit files to be created that are automatically used to insert missing value codes into a time period that
had instrument problems. The creation of edit files is typically done after the completion of a field project when scientists
are performing quality assurance of the data set. Since data processing is automatic, preliminary data can be created and
analyzed within hours of an aircraft flight and a complete field project data set can be reprocessed many times during the
quality assurance process. Once a final data set has been created, ADPAA provides several tools for visualization and analysis.
In addition to aircraft data, ADPAA can be used on any data set that is based on time series measurements. The concepts illustrated
by ADPAA and components of ADPAA, such as the Cplot visualization tool, are applicable to areas of Earth Science that work
with time series measurements. 相似文献
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矿井电阻率法监测是采煤工作面顶底板水害预防的一项重要技术手段,但因井下监测环境电磁干扰复杂、强度极大,同时为煤矿安全生产考虑,最大发射电流受限,因此,矿井电阻率法监测采集数据的质量难以保证。为了从每日监测到的海量数据中选择可信度较高的数据加以利用,对比分析了常用的矿井直流电阻率法探测数据质量评价方法的优缺点,基于矿井电阻率法监测本身自动化、智能化、全波形、不间断数据采集的特点,研究了矿井电阻率法监测全波形数据的时频域特征;针对发射电流、原始数据噪声、数据稳定性3个方面,利用统计学原理提出定量的数据质量评价方法,设计了可用于矿井电阻率法监测数据质量评价的发射电流和稳定性、接收信号时间和空间稳定性以及原始数据的信噪比4种参数;并以此为基础建立了矿井电阻率法监测数据质量评价流程;最后应用于井下实际采集的监测数据。结果表明：该流程具备针对性强、手段丰富、较全面反映噪声干扰情况等优点,能够适用于井下电阻率法监测本身自动化、智能化、全波形不间断数据采集的特点,解决了现有技术条件下矿井电阻率法监测数据质量管控不足的问题。 相似文献
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Several interrelated factors affect, water quality in the Albemarle-Pamlico Estuarine System (APES) including land use change in the upland and coastal watersheds, legislatively mandated basin-wide nutrient management plans, intense storms, and global and local changes in sea level. Despite its importance as an essential fish habitat, the APES has not been monitored as intensively or extensively for habitat impacts associated with decreased water quality as other estuaries have been, such as with the North Carolina tributary estuaries or Chesapeake Bay. To support the sustainable use of these estuaries, we are developing an automated water quality monitoring system aboard ferries that traverse the APES. This program, FerryMon, provides a unique, long-term, and cost-effective monitoring system to evaluate status and trends in APES water quality. Intensive temporal and spatial data obtained from all ferry routes provide an environmental baseline and are used to assess the patterns and variability in surface water hydrography, dissolved constituents, and particulate matter. The data are useful to calibrate estimates of ocean color and sea surface temperature from aircraft and satellite sensors. We are creating a searchable geographic database that is intended for scientists, managers, and the general public. Using ferries as sampling platforms to monitor estuarine water quality is a tractable approach and FerryMon represents a model for use in other large bodies of water traversed by ferries. 相似文献
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M. A. Kamal M. A. Sulehri D. A. B. Hughes 《Geotechnical and Geological Engineering》2006,24(4):819-831
This paper summarizes an extensive series of common durability, shape and strength tests carried out on road aggregates from
quarries in northern Pakistan by Sharif et al. at the University of Engineering and Technology, Taxila. The data from these
standard tests have been correlated for a particular aggregate type to show the close relationship between these measured
physical characteristics. The paper outlines how, once these relationships have been established for a particular aggregate
source, it is feasible to simplify the testing or quality assurance regime and monitor only some of these characteristics
to assess the overall quality of the aggregate. The physical characteristics have then been combined into a linear relationship,
using coefficients estimated from the extensive data set in the paper, to give a single characteristic for an aggregate type
known as the Toughness Index (TI). The TI is therefore based on the main strength and durability characteristics of the aggregates
and can be used as an indicator of the overall quality of the aggregate. 相似文献