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1.
In the practice of administrative or engineering geosciences, the problem of deriving a digital surface representation from a map displaying contour lines of the interesting quantity is quite often encountered. First, alpha-numerical data are retrieved from the map by digitizing these contour lines pointwise into polygons. However, common gridding algorithms are known to fail at adequately reproducing the input contour lines due to the inhomogeneous and anisotropic areal distribution of the sites of the data sampled from given contour lines. Therefore, we suggest a new algorithm; the basic elements of its first stage are a constrained Delaunay triangulation of the data sites honoring their natural neighborhood relationship—i.e., whether they belong to the same contour line or not, and linear interpolation according to this triangulation of the data domain. In a second stage, a Bezier-Bernstein or simplex B-spline representation is easily achieved if a C1 or C2 smooth representation is required. At this stage, also, discontinuities of the function or its first directional derivatives with known locations in the data domain may be represented, provided this additional information has been taken into account when the triangulation was performed. The algorithm is numerically stable and efficient, and allows external interaction by the user to introduce his/her additional knowledge of the phenomenon to be studied, which may not be explicitly inherent in the available data. 相似文献
2.
Parameter identification is one of the key elements in the construction of models in geosciences. However, inherent difficulties
such as the instability of ill-posed problems or the presence of multiple local optima may impede the execution of this task.
Regularization methods and Bayesian formulations, such as the maximum a posteriori estimation approach, have been used to
overcome those complications. Nevertheless, in some instances, a more in-depth analysis of the inverse problem is advisable
before obtaining estimates of the optimal parameters. The Markov Chain Monte Carlo (MCMC) methods used in Bayesian inference
have been applied in the last 10 years in several fields of geosciences such as hydrology, geophysics or reservoir engineering.
In the present paper, a compilation of basic tools for inference and a case study illustrating the practical application of
them are given. Firstly, an introduction to the Bayesian approach to the inverse problem is provided together with the most
common sampling algorithms with MCMC chains. Secondly, a series of estimators for quantities of interest, such as the marginal
densities or the normalization constant of the posterior distribution of the parameters, are reviewed. Those reduce the computational
cost significantly, using only the time needed to obtain a sample of the posterior probability density function. The use of
the information theory principles for the experimental design and for the ill-posedness diagnosis is also introduced. Finally,
a case study based on a highly instrumented well test found in the literature is presented. The results obtained are compared
with the ones computed by the maximum likelihood estimation approach. 相似文献
3.
数据网格化是三维地质建模的常用方法。断层是普遍的地质现象,带断层的海量数据三角剖分在建模中较为复杂。提出了一种简单的可以解决带断层地震数据Delaunay三角剖分的有效算法。该算法首先对数据边界进行初始Delaunay三角剖分,然后将其变尺度加密,生成较均匀三角网,最后将断层边界强行嵌入三角网,实现了三角网格化。 相似文献
4.
Automatic triangulation of scattered locations permits analysis of local variation in a dependent variable through calculation of a roughness index. This is approached by treating triangles of the triangulation (including the dependent variable) as vectorial structures, and accumulating at each data point the vector sum of the cluster of triangles surrounding it. The roughness index is defined as the complement of the ratio of the area of a triangle cluster to the area of component triangles as projected onto a gradient plane defined by their vector sum. The roughness index provides a measure of consistency of data values relative to surrounding observations and can be interpreted as a local index of reliability of interpolation. 相似文献
5.
6.
土地退化已成为全球性重大的环境问题之一,中国是一个土地退化十分严重的国家,松嫩平原的盐碱荒漠化严重制约农牧业的可持续发展。因此,应用新技术、新方法对农业生态环境进行研究和管理是一项迫切的任务。文章提出农业生态环境的新概念,建立了农业生态环境系统模型,进行模拟研究。由于该方法在信息存储、管理和应用方面存在较大的局限性,笔者继而建立了农业生态环境信息系统模型,扩大对空间信息的应用。但该信息系统缺乏信息共享的功能,而且不能对海量的信息进行空间化、数字化和一体化的管理。笔者以多学科的理论和多种技术方法为基础,借鉴数字地球的研究成果,研制了吉林西部农业生态环境数字信息系统。该系统具有存储、管理海量空间数据的功能和信息共享功能,可在统一的用户界面下进行农业生态环境评价、预测、仿真和规划等方面的系列、连续研究,并可实现模拟结果的可视化。该系统具有扩充性、移植性等优点,因此,具有推广价值。 相似文献
7.
《地学前缘(英文版)》2016,7(1)
Learning incorporates a broad range of complex procedures. Machine learning(ML) is a subdivision of artificial intelligence based on the biological learning process. The ML approach deals with the design of algorithms to learn from machine readable data. ML covers main domains such as data mining, difficultto-program applications, and software applications. It is a collection of a variety of algorithms(e.g. neural networks, support vector machines, self-organizing map, decision trees, random forests, case-based reasoning, genetic programming, etc.) that can provide multivariate, nonlinear, nonparametric regression or classification. The modeling capabilities of the ML-based methods have resulted in their extensive applications in science and engineering. Herein, the role of ML as an effective approach for solving problems in geosciences and remote sensing will be highlighted. The unique features of some of the ML techniques will be outlined with a specific attention to genetic programming paradigm. Furthermore,nonparametric regression and classification illustrative examples are presented to demonstrate the efficiency of ML for tackling the geosciences and remote sensing problems. 相似文献
8.
ZHANG Huai SHI Yaolin WU Zhongliang Graduate University of Chinese Academy of Sciences Beijing China Institute of Geophysics China Earthquake Administration Beijing China 《《地质学报》英文版》2009,83(4)
Recent rapid progress in cyberinfrastructure in geosciences is providing seismologists an enormous boost for addressing multi-physical phenomena of regional seismic activities.The inherent nature of their multi-scale properties,from temporal to spatial spaces,makes it inevitably to be solved using large-scale computations and distributed parallel data processing schemes.Under such circumstance,using the advanced numerical algorithms and unstructured mesh generation technologies become the obstacles for m... 相似文献
9.
一种基于似三棱柱体元的地质三维建模方法研究 总被引：4，自引：0，他引：4
三堆空间建模方法是三堆地劫工程GIS研究的核心问题之一。提出一种基于似三棱柱体元的三堆数据模型，模型包含顶点、线段(棱边、三角形边)、三角形、侧面四边形、三棱柱体元5个基本元素。和点对象、线对象、面对象、体对象、复杂对象、空间对象等6个对象。设计了5个基本元素和3种地质对象的数据结构和它们之间的拓扑关系。以岩体和巷道为例。给出了似三棱柱体建模思路和算法。利用内蒙古某矿区实际钻孔资料和模拟巷道数据对所开发的系统原型进行验证。研究表明。基于似三棱柱体元的数据模型的优势在于可以表示空间对象的表面和内部结构。便于建模和节省存储空间，同时便于不规劓的自然地质体和规则勘探工程建模。 相似文献
10.
Abstract: Recent rapid progress in cyberinfrastructure in geosciences is providing seismologists an enormous boost for addressing multi-physical phenomena of regional seismic activities. The inherent nature of their multi-scale properties, from temporal to spatial spaces, makes it inevitably to be solved using large-scale computations and distributed parallel data processing schemes. Under such circumstance, using the advanced numerical algorithms and unstructured mesh generation technologies become the obstacles for modern seismologists. The main objective of this paper is to present a framework, which includes a parallel finite element simulation and distributed data infrastructure, to address the novel algorithms, state-of-the-art modeling and their implementation in regional seismicgenic systems. We also discuss and implement this framework to analyze the strong earthquake evolution processes in the Sichuan-Yunnan region. This study is the key to long-term seismic risk by estimates, providing a platform for predictive large-scale numerical simulation modeling of regional earthquake activities. 相似文献
11.
An important issue in reservoir modeling is accurate generation of complex structures. The problem is difficult because the connectivity of the flow paths must be preserved. Multiple-point geostatistics is one of the most effective methods that can model the spatial patterns of geological structures, which is based on an informative geological training image that contains the variability, connectivity, and structural properties of a reservoir. Several pixel- and pattern-based methods have been developed in the past. In particular, pattern-based algorithms have become popular due to their ability for honoring the connectivity and geological features of a reservoir. But a shortcoming of such methods is that they require a massive data base, which make them highly memory- and CPU-intensive. In this paper, we propose a novel methodology for which there is no need to construct pattern data base and small data event. A new function for the similarity of the generated pattern and the training image, based on a cross-correlation (CC) function, is proposed that can be used with both categorical and continuous training images. We combine the CC function with an overlap strategy and a new approach, adaptive recursive template splitting along a raster path, in order to develop an algorithm, which we call cross-correlation simulation (CCSIM), for generation of the realizations of a reservoir with accurate conditioning and continuity. The performance of CCSIM is tested for a variety of training images. The results, when compared with those of the previous methods, indicate significant improvement in the CPU and memory requirements. 相似文献
12.
Neil A. Chapman 《地学学报》1994,6(1):5-19
The last 10–15 years have produced a considerable amount of research into the geological disposal of radioactive wastes. This has had some very beneficial spin-offs for the geosciences. There are, however, a number of areas where it is difficult for earth scientists to provide quantitative information required for the types of long-term safety assessment being performed at present. With the likely increased stringency with which we may begin to treat other industrial wastes, much is to be learned from the radioactive waste experience. This article reviews some of the geological issues in constraining long-term predictions, discusses how geological data are used, and questions exactly what it is that we are trying to achieve in the management of these wastes and in the regulations concerning their disposal. 相似文献
13.
《China Geology》2021,4(2):329-352
In the context of global climate change, geosciences provide an important geological solution to achieve the goal of carbon neutrality, China’s geosciences and geological technologies can play an important role in solving the problem of carbon neutrality. This paper discusses the main problems, opportunities, and challenges that can be solved by the participation of geosciences in carbon neutrality, as well as China’s response to them. The main scientific problems involved and the geological work carried out mainly fall into three categories: (1) Carbon emission reduction technology (natural gas hydrate, geothermal, hot dry rock, nuclear energy, hydropower, wind energy, solar energy, hydrogen energy); (2) carbon sequestration technology (carbon capture and storage, underground space utilization); (3) key minerals needed to support carbon neutralization (raw materials for energy transformation, carbon reduction technology). Therefore, geosciences and geological technologies are needed: First, actively participate in the development of green energy such as natural gas, geothermal energy, hydropower, hot dry rock, and key energy minerals, and develop exploration and exploitation technologies such as geothermal energy and natural gas; the second is to do a good job in geological support for new energy site selection, carry out an in-depth study on geotechnical feasibility and mitigation measures, and form the basis of relevant economic decisions to reduce costs and prevent geological disasters; the third is to develop and coordinate relevant departments of geosciences, organize and carry out strategic research on natural resources, carry out theoretical system research on global climate change and other issues under the guidance of earth system science theory, and coordinate frontier scientific information and advanced technological tools of various disciplines. The goal of carbon neutrality provides new opportunities and challenges for geosciences research. In the future, it is necessary to provide theoretical and technical support from various aspects, enhance the ability of climate adaptation, and support the realization of the goal of carbon peaking and carbon neutrality. 相似文献
14.
Jonathan L. Carrivick Mark W. Smith Duncan J. Quincey Steve J. Carver 《Geology Today》2013,29(4):138-143
Acquiring outcrop, landform or other surface topography data in the field for the geosciences has always been challenging. Accessibility is often a problem, time is usually limited and an ideal spatial and temporal coverage often has to be compromised to be more manageable. However, emerging technologies, and some re-inventions of rather older ones, can overcome many of these constraints in a very exciting and budget-friendly manner. This article briefly introduces and reviews four major recent developments in budget remote sensing, specifically the use of blimps, kites, drones or UAVs (including quadcopters), and structure from motion (SFM) software. Both scientific and applied case studies are given and some possibilities for future studies are highlighted. Overall, the potential for these technologies to revolutionise the geosciences is clear and should be opportunistically embraced by scientists, resource and hazard managers and educators alike. 相似文献
15.
采用剖开算子法,把二维输运问题剖分为两个子初值问题(对流分步、扩散分步)。在任意三角形网格中,分别对不同性质的算子采用各自适合的算法,即采用特征线法求解对流分步,采用半隐式有限元法求解扩散分步。重点探讨了对流插值问题,给出了一种完全对称三次插值模式,有效地减少了数值阻尼。为了克服高阶插值数值震荡问题,计算中保证了函数及其一阶偏导数连续。算例表明,数值方法模拟结果与精确解吻合较好。该算法在求解输运方程(包括纯对流输运方程)时,既能有效减少数值阻尼,也能保证计算中不出现数值震荡。 相似文献
16.
试论花岗质深成岩体的复合定位机制及定位空间问题 总被引：12，自引：0，他引：12
大陆地壳中巨量花岗岩体的定位机制及定位空间是一个长期急论的问题,已提出十余种机制,但都困难以解决定位空间面引起争议,近年来,人们认识到岩体定位及获取空间是多种机制共存的复合定位机制,这是今后需进一步研究的新课题,笔者提出的复合定位机制可概括为主动膨胀,构造扩展,岩浆侵吞作用３个基本端元机制的构成的复合,可用三角图解表述,并以具体研究实例进行了论述。 相似文献
17.
非负矩阵分解（NMF）是重要的矩阵分解算法与数据降维工具。介绍了NMF的背景、定义、原理及特征。在已有NMF算法分类的基础上,总结当前流行的NMF算法及研究进展,综述NMF在地学领域中的应用,主要包括高光谱图像的处理与矿产资源预测。对NMF算法的研究方向进行了预测和展望。 相似文献
18.
Logistic regression is a widely used statistical method to relate a binary response variable to a set of explanatory variables
and maximum likelihood is the most commonly used method for parameter estimation. A maximum-likelihood logistic regression
(MLLR) model predicts the probability of the event from binary data defining the event. Currently, MLLR models are used in
a myriad of fields including geosciences, natural hazard evaluation, medical diagnosis, homeland security, finance, and many
others. In such applications, the empirical sample data often exhibit class imbalance, where one class is represented by a
large number of events while the other is represented by only a few. In addition, the data also exhibit sampling bias, which
occurs when there is a difference between the class distribution in the sample compared to the actual class distribution in
the population. Previous studies have evaluated how class imbalance and sampling bias affect the predictive capability of
asymptotic classification algorithms such as MLLR, yet no definitive conclusions have been reached. 相似文献
19.
Rapid estimation of ground-shaking maps for seismic emergency management in the Campania Region of southern Italy 总被引：1，自引：1，他引：0
Vincenzo Convertito Raffaella De Matteis Luciana Cantore Aldo Zollo Giovanni Iannaccone Mauro Caccavale 《Natural Hazards》2010,52(1):97-115
Strong ground-shaking mapping soon after a moderate-to-large earthquake is crucial to recognize the areas that have suffered
the largest damage and losses. These maps have a fundamental role for emergency services, loss estimation and planning of
emergency actions by the Civil Protection Authorities. This is particularly important for areas with high seismic risk levels,
such as the Campania-Lucania Region in southern Italy. Taking advantage of the Irpinia Seismic Network (ISNet), a recently
installed dense and wide dynamic seismic network, we have developed a procedure for rapid estimation of ground-shaking maps
after moderate-to-large earthquakes (GRSmap). This uses an optimal data gridding scheme designed to account for bi-dimensional
features of strong ground-motion fields, such as directivity, radiation patterns and focal mechanisms, to which most damage
can be correlated. The basis of the mapping technique is a triangulation procedure to locally correct predicted data at the
triangle barycentres where their vertices correspond to seismic stations. The method has been tested off-line using a simulated
M 6.6 earthquake located at the centre of ISNet and applied to data of the 23 November 1980 Irpina M 6.9 earthquake recorded by a sparse network. This has highlighted its ability to predict peak ground-motion parameters of
large magnitude earthquakes with respect to the attenuation relationships. 相似文献
20.
空间信息技术的发展及其在地球科学中的应用 总被引：35，自引：1，他引：34
空间信息技术有两个分支：其一是空间图形信息技术,即地理信息系统（ＧＩＳ）;其二是地质统计学。两种技术在本质上是相通的。ＧＩＳ的核心是建立图形元素的拓扑关系与建立空间数据库与属性数据库的联动关系。正是立足于这两个重要关系,使对千变万化的地学图形信息进行灵活高效的编辑、检索与显示成为可能。在迄今为止所有的计算机应用系统中,ＧＩＳ无疑将在地学中产生最重要的影响。地质统计学是一种空间数字处理技术,它是传统统计学的空间版本。用包含多元统计学的传统统计方法研究地质问题存在严重的缺陷,因为传统统计学忽略变量的空间存在,而地质过程具有强烈的空间性。地质统计学恰恰是立足于变量的空间关系发展起来的统计科学,因此它特别适用于地球科学。正如空间图形与空间数字可以相互转换一样,两种空间信息技术也存在内在的关系。利用ＧＩＳ与地质统计学这两种空间信息技术,使我们能不断地在空间图形与空间数字这两种状态间穿越。空间信息技术为地质学家在进行矿产资源预测、物化遥数据分析、地质环境评价、地质灾害评价与矿产资源管理等方面提供了强有力的工具。空间信息技术特别适合于地球科学,它不仅能大幅度地提高地球科学对图形的编制和研究的效率和水平,而且也将转变传统的? 相似文献