Secular variation from monthly means from Apia and Amberley magnetic observatories     

D. Gubbins  L. Tomlinson 《Geophysical Journal International》1986,86(2):603-616

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Nonlinearly Constrained Optimization Theory to Interpret Magnetic Anomalies Due to Vertical Faults and Thin Dikes     

J. Asfahani  M. Tlas 《Pure and Applied Geophysics》2004,161(1):203-219

A new and simple method based on a nonlinearly mathematical optimization concept has been proposed in this research to interpret magnetic anomalies due to vertical faults and thin dikes. This proposed interpretative method consists of three main steps. The first step is to formulate nonlinearly constrained optimization problems to describe the geophysical problems related to the studied structures. The second step is to suggest an interior penalty function in order to convert these nonlinearly constrained optimization problems into nonlinearly unconstrained optimization ones. The third step is to solve the converted nonlinearly unconstrained optimization problems by using the famous Hooke and Jeevess algorithm in order to estimate the geophysical parameters of the studied structures such as: depth, amplitude coefficient, and index parameter. The Hooke and Jeevess algorithm is purposely chosen for being robust and also its application to magnetic data converges rapidly towards the optimal estimation of parameters. This method was first tested on theoretical models with different random noise, where a very close agreement was obtained between the assumed and evaluated parameters. The validity of this new method was also tested on practical field examples taken from Australia, India, United States, and Brazil, where available magnetic data existed and was previously analyzed by different interpretative methods. The agreement between the results obtained by our developed method and those obtained by the other geophysical methods is good. The advantages of this newly proposed method, compared with the other published interpretative methods, also have been discussed and demonstrated.  相似文献   

基于地震数据专家的子午链台站地磁自动化产品系统设计与实现     

陈洪凯  陈传华  张明  赵帝  洒荣利 《地震地磁观测与研究》2021,42(4):195-199

基于对子午链台站地震地磁前兆异常以及地球空间环境变化等研究方向的需求分析,利用网络、大数据、云计算等新技术,结合地震数据专家（DatistEQ）软件,设计子午链台站地磁指数报告自动产出系统。该系统通过低代码、敏捷式开发工作流程,连接不同功能节点,可以实现用户定制化、数据标准化、功能智能化的系统报告产出。通过本地或者云端一键流程化工作,将不同类型的数据发送到科研工作者或其他需求者,简化工作流程,优化数据处理,实现高效率产品产出。  相似文献   

A critical zone observatory dedicated to suspended sediment transport: The meso-scale Galabre catchment (southern French Alps)     

Cédric Legout  Guilhem Freche  Romain Biron  Michel Esteves  Oldrich Navratil  Guillaume Nord  Magdalena Uber  Thomas Grangeon  Nico Hachgenei  Brice Boudevillain  Céline Voiron  Lorenzo Spadini 《水文研究》2021,35(3):e14084

The 20 km² Galabre catchment belongs to the French network of critical zone observatories (OZCAR; Gaillardet et al., Vadose Zone Journal, 2018, 17(1), 1–24). It is representative of the sedimentary lithology and meteorological forcing found in Mediterranean and mountainous areas. Due to the presence of highly erodible and sloping badlands on various lithologies, the site was instrumented in 2007 to understand the dynamics of suspended sediments (SS) in such areas. Two meteorological stations including measurements of air temperature, wind speed and direction, air moisture, rainfall intensity, raindrop size and velocity distribution were installed both in the upper and lower part of the catchment. At the catchment outlet, a gauging station records the water level, temperature and turbidity (10 min time-step). Stream water samples are collected automatically to estimate SS concentration-turbidity relationships, allowing quantification of SS fluxes with known uncertainty. The sediment samples are further characterized by measuring their particle size distributions and by applying a low-cost sediment fingerprinting approach using spectrocolorimetric tracers. Thus, the contributions of badlands located on different lithologies to total SS flux are quantified at a high temporal resolution, providing the opportunity to better analyse the links between meteorological forcing variability and watershed hydrosedimentary response. The set of measurements was extended to the dissolved phase in 2017. Both stream water electrical conductivity and major ion concentrations are measured each week and every 3 h during storm events. This extension of measurements to the dissolved phase will allow progress in understanding both the origin of the water during the events and the partitioning between particulate and dissolved fluxes of solutes in the critical zone. All data sets are available at https://doi.osug.fr/public/DRAIXBLEONE_GAL/index.html .  相似文献   

海底观测网发展现状及趋势研究     

陈建冬  张达  王潇  潘筱屹  王策男  张自丽  葛辉良 《海洋技术学报》2019,38(6):95-103

文中详细研究了当前世界上最典型的海底观测网的建设发展规模、形式、设备类型以及我国海底观测网的发展现状,并对国内外海底观测网的发展趋势进行总结。对日本、加拿大、美国及欧洲的海底观测网进行了设备级研究,对我国台湾地区、东海、南海的海底观测网现状进行了研究,并讨论了国外先进观测网对我国的海底观测网建设的借鉴意义。文中总结出海底观测网发展的整体趋势为:单节点网络加速验证新型设备及传感器的水下能力;区域尺度网络用于加速多学科发展并提升灾害预警能力;而浮标平台网络作为补充,铺设在远海区域以降低阶段建设成本。  相似文献   

PDR算法对地磁室内定位精度的提升研究     

黄鹤  张新宇  仇凯悦 《测绘通报》2019,(12):18-21

利用建筑物中金属结构引起的地磁场扰动可以对室内的行人目标进行定位，而且基于地磁场的定位无需布设任何额外设施，因此可以以低成本实现定位。但仅靠单一的地磁技术无法满足室内定位的精度要求。为了解决磁场数据中单点定位的模糊性问题，本文提出了一种利用粒子滤波算法将PDR与地磁相融合的室内定位方法，并开发了地磁室内导航系统，以智能手机为硬件平台构建磁力计传感器模型，建立匹配轨迹的均方误差准则并实现PDR累积误差实时校正的迭代计算。在68 m×1.8 m的试验区域内，产生的平均定位误差为1.13 m，最大定位误差为2.17 m。本文算法的定位精度比单独PDR算法提升了42%；与单一地磁指纹匹配算法相比，定位精度提高了57%。试验证明，本文提出的融合算法对提高室内定位精度具有显著的作用。  相似文献   

大型工程项目中BIM+GIS指挥调度系统的应用     

赵妍妍  杨宁宇  马燕 《测绘与空间地理信息》2017,40(Z1)

在"京津冀一体化"的发展目标下,随着新区的建设,政府项目存在着规模大、周期紧、关注度高、管理难度大等特点.利用互联网+的理念提高建筑行业的管理精度是解决问题的主流方向,也符合住建部《2016—2020年建筑业信息化发展纲要》提出的"构建基于BIM、大数据、智能化、移动通信、云计算等技术的工程质量、安全监管模式与机制".本文以某一重大政府项目工程为例,介绍如何将住建部要求的技术要素通过BIM+GIS指挥调度系统应用到项目中.  相似文献   

On the age calibration of the geomagnetic polarity timescale     

Pierre Agrinier  Yves Gallet  & Eric Lewin 《Geophysical Journal International》1999,137(1):81-90

Knowledge of the age of undated events is not null if a time-order relationship can be found among these events. The knowledge of such a time-ordered sequence can be formalized by using non-informative (uniform) prior probability densities for the ages of undated events and Bayes' theorem to introduce the time-order relationship condition. We show that the conditional probability densities of the ages of events of unknown age are given by various forms of Euler's beta distribution. These distributions yield an estimate of the probability for an undated event to occur in a given age interval.
  We use this method to propose appropriate probabilistic representations of our actual knowledge of the dating of the magnetic polarity reversals during the Cenozoic. These representations take into account the uncertainties arising from irregularities in accretion process and from the quality of a few calibration points. Both types of uncertainties generate large ambiguities in the age of magnetic reversals, which should be taken into consideration when the geomagnetic polarity timescale is used for dating purposes. We propose to use the entropy function to quantify these ambiguities.  相似文献   

Magnetostratigraphy of Palaeocene basalts from the Vaigat Formation of West Greenland   总被引：1，自引：0，他引：1  

Peter Riisager  & Niels Abrahamsen 《Geophysical Journal International》1999,137(3):774-782

A palaeomagnetic study comprising the directional results from 289 individual lava flows, sampled along eight sections in the Palaeocene basalts of West Greenland, is reported. The eight individual sections are correlated using lithostratigraphical marker horizons to form a single composite profile. Generally, the lithological correlation is in good agreement with the record of geomagnetic secular variation.
  The total composite palaeomagnetic profile represents a stratigraphic thickness of 1.6  km through the Vaigat Formation, which is the lowermost of the two volcanic formations formed during the main stage of plateau volcanism. Only two polarity zones are found in the composite profile, suggesting a very short duration for the West Greenland main plateau-building volcanism. ⁴⁰Ar/³⁹Ar dates support a high extrusion rate and also indicate that the lower normal polarity zone is Chron C27n and that the upper reverse polarity zone is Chron C26r.
  The C27n–C26r transition is fully recorded along one of the sections (Nuusap Qaqqarsua), with intermediate directions covering a 200  m thick succession of lavas. A combined palaeomagnetic, field and geochemical study along this profile showed good agreement; that is, geochemically and geologically derived single magmatic events show groupings of the palaeomagnetic directions. Supposing a duration for the geomagnetic transition of 5000 years, the eruption frequency during this period was as high as one flow every 80 years.  相似文献   

Possible Cause-Effect Relationships Between Vrancea (Romania) Earthquakes and Some Global Geophysical Phenomena     

D. Enescu  B. D. Enescu 《Natural Hazards》1999,19(2-3):233-245

The possibility that the Earth's tides are a triggering factor of Vrancea subcrustal earthquakes is investigated in the first part of this paper. A possible correlation between Vrancea subcrustal earthquakes and geomagnetic jerks is demonstrated in the second part. The last part of the paper presents a number of results concerning a possible relationship between the regularities of strong Vrancea subcrustal seismicity and the Chandler nutation parameters. An attempt is made to integrate all of these phenomena in a more general framework that takes into account physical processes in the Earth mantle and core. A long-term prediction of the next strong Vrancea earthquake is finally attempted.  相似文献