共查询到19条相似文献，搜索用时 781 毫秒
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基于Agent的模型(Agent-based models,ABM)研究已成为水资源管理研究理论与方法的重要补充。对水资源管理ABM研究进行归纳与展望,有助于探索优化中国水资源管理体制和机制。在阐述水资源管理ABM概念及内涵的基础上,提炼出主体决策规则和互作机制两个建模核心内容,并对其方法进行了归纳分析;从流域水资源优化配置、城镇居民用水管理和灌区水资源管理3个方面,对2009—2018年主要水资源管理ABM研究进行了综述;针对当前研究的难点与不足,提出未来研究重点:①拓展复杂适应理论在水资源管理领域的应用;②加强不确定性水资源管理ABM研究;③探索基于机器学习的决策规则建模方法;④重视参数校准和结果校验及检验方法;⑤加强模型表述格式标准化进程;⑥综合权衡水资源管理ABM框架。 相似文献
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基于GeoCA和GIS的滑坡滑动面演化规律研究 总被引：6，自引：0，他引：6
传统的滑坡稳定性分析大多是建立在以数学模型为基础的一种确定性分析。实际上,滑坡是一个影响因数众多,边界条件复杂的不确定复杂系统。地理元胞自动机是一种时间和空间都离散的动力系统,为之设定相应的状态、元胞空间、邻居、规则和时间,可以很好地模拟滑坡滑动面从稳定到滑移这一微观变化过程,形成GeoCA LANDSLIDE模型。以吴家湾滑坡为例,对其滑动面的演化规律进行了模拟。 相似文献
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传统的滑坡稳定性分析大多是建立在以数学模型为基础的布点、观测、计算、预测这一方法进行的一种确定性分析.实际上,滑坡是一个影响因素众多,边界条件复杂,诱发因数偶然的、不确定的复杂系统.论文运用地理元胞自动机这一时间和空间都离散的动力系统工具,研究了用元胞自动机来模拟滑坡的原理、方法和工作流程,并在GIS技术支持下针对滑坡的可能滑面设定不同的元胞状态并以此确定相应的元胞空间,采用相同的邻居定义和转化规则,着重研究滑坡滑动面从稳定到滑移这一微观动态变化过程,形成Geo-CA-LANDSLIDE系统.最后,采用100×100的地理元胞自动机模型.实例研究了滑坡形成与元胞演化规律之间的关系,得出了与理论分析相一致的结论.运用GIS技术与之集成,可以将这一过程可视化表达. 相似文献
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元胞自动机模型在地学中的研究进展 总被引：6，自引：0，他引：6
元胞自动机模型具有离散动力学特征，可以模拟和分析一般的复杂系统，对具有空间特征的地理复杂系统更具优势。该模型有“自下而上”、离散、确定性和随机性结合、灵活性和开放性等优点，但亦具有边界的无限、空间同质、元胞形状规则、邻近关系固定以及对实践封闭等缺点。在介绍了该模型优缺点的基础上，分析了元胞自动机的理论研究趋势与主要的应用领域。 相似文献
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层状地质体的三维模拟与可视化 总被引：51，自引：1，他引：50
文中探讨了层状地质体的三维模拟与可视化方法和技术。地质数据通常是有限的、空间上分布不均匀的点数据 ,需要大量使用插值技术来形成合理的模型。简单层状实体可在二维插值的基础上 ,按照这些面的空间位置叠加 ,形成三维体模型。复杂的层状体包括沉积相以及一些物性参数的空间变化 ,断层等形成的不连续以及复杂的褶皱等。这些实体的模拟与可视化 ,需要进行三维插值 ,并根据不同现象的特点选择合适的方法。合理的专家知识或地质解释的交互加入 ,是形成合理的三维模型的关键。 相似文献
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本文介绍了苏联科学院地理研究所在第十二个五年计划期间地理学研究的五个主要方向:①深入研究综合自然地理学的理论原理;②综合研究地理系统的稳定性和变异性的因素和机制;③揭露社会与自然相互作用的地域组织的规律性;④深入研究社会地域组织的理论原理;⑤发展地理信息学、绘图模拟和遥感探测的理论和方法。 相似文献
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针对致密砂岩气储层复杂的微观孔隙结构进行岩石物理建模,在模型中比较了单一孔隙纵横比、双孔隙模型两种表征孔隙结构的表征方式。岩石物理正演分析表明,两种孔隙结构模型均可解释致密砂岩复杂的速度-孔隙度关系。岩石物理反演结果表明,双孔隙模型对测井横波速度的预测精度更高,说明该模型更适用于表征研究区致密砂岩的孔隙结构,反演的软孔比例参数能够反映地层中孔隙结构的非均匀分布。应用双孔隙模型计算致密砂岩地层岩石骨架的弹性模量,与Krief及Pride等传统经验公式相比,该方法考虑了岩石骨架模量与矿物基质、孔隙度和孔隙结构等微观物性因素的关系,理论上更具有严谨性。对致密砂岩骨架模量计算结果的分析表明,少量微裂隙的存在即能够显著影响致密砂岩骨架的弹性性质,同时孔隙空间中的球形孔隙是致密气的主要赋存空间。并且,通过致密砂岩骨架弹性模量,进一步计算了可用于地层评价的Biot系数等岩石物理参数。致密砂岩骨架模量的预测结果可为Gassmann流体替换理论、BISQ孔隙弹性介质理论等岩石物理方法提供关键参数。 相似文献
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国外空域资源开发利用的理论基础、方法论变革与实践 总被引：3，自引：1，他引：2
空中交通流量的持续增长引发充分开发利用空域资源的理论建设和方法论研究及其应用实践,旨在突破原有的空域结构及其扇区边界的限制。在过去的10年里航线结构及其需求有了显著变化,仍保持相对固定的几何扇区形态面临新的挑战,需要重新设计动态空域功能分区。首先分析了当前空域资源开发利用的理论基础,包括新一代航空运输体系,灵活空域使用,平衡扇区等;然后评价了方法论的变革,总结了从动态空域配置(DAC)到动态空域功能分区(DAS)的转变,以及动态空域功能分区的2D-DAS常用方法向3D-DAS新方法的演进,并讨论了"基于个体模型"(ABM)的局限性和"改进的基于个体模型"(i ABM)的应用优势;最后展望了地理学空间研究向空域拓展的前景。 相似文献
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Emmanuel Gringarten 《Mathematical Geosciences》1996,28(7):881-893
Traditional stochastic modeling of fracture networks usually failed because it required unaccessible statistics and may not be able to honor available local data. This paper presents an algorithm for the 3D geometric simulation of fractured reservoirs. It is based on geological rules of fracture propagation and interaction. It is part of a methodology which aims at integrating diverse data about the fracture system in the subsurface. This information can come from well cores and logs, analog outcrops, geomechanical stress studies, seismic surveys; it may be quantitative or qualitative, and have different degrees of reliability. 相似文献
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Gang Yao Nuno Vieira da Silva Henry Alexander Debens Di Wu 《Computational Geosciences》2018,22(2):469-484
Finite difference is the most widely used method for seismic wavefield modeling. However, most finite-difference implementations discretize the Earth model over a fixed grid interval. This can lead to irregular model geometries being represented by ‘staircase’ discretization, and potentially causes mispositioning of interfaces within the media. This misrepresentation is a major disadvantage to finite difference methods, especially if there exist strong and sharp contrasts in the physical properties along an interface. The discretization of undulated seabed bathymetry is a common example of such misrepresentation of the physical properties in finite-difference grids, as the seabed is often a particularly sharp interface owing to the rapid and considerable change in material properties between fluid seawater and solid rock. There are two issues typically involved with seabed modeling using finite difference methods: firstly, the travel times of reflections from the seabed are inaccurate as a consequence of its spatial mispositioning; secondly, artificial diffractions are generated by the staircase representation of dipping seabed bathymetry. In this paper, we propose a new method that provides a solution to these two issues by positioning sharp interfaces at fractional grid locations. To achieve this, the velocity model is first sampled in a model grid that allows the center of the seabed to be positioned at grid points, before being interpolated vertically onto a regular modeling grid using the windowed sinc function. This procedure allows undulated seabed bathymetry to be represented with improved accuracy during modeling. Numerical tests demonstrate that this method generates reflections with accurate travel times and effectively suppresses artificial diffractions. 相似文献
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生态地理建模中的多尺度问题 总被引：29，自引：0，他引：29
本文在分析生态地理建模内涵的基础上,讨论了生态地理建模中的尺度转换问题、跨尺度相互作用问题、空间尺度与时间尺度的关联问题和多尺度数据处理问题.由于生态地理问题的非线性、生态环境的异质性和随机事件,简单的线性尺度转换方法远不能满足生态地理建模的要求.为了从根本上解决生态地理建模中的时空尺度问题,除需要运用微分几何学和等级理论等经典方法外,还需要引入格点生成法和网格计算等现代理论和技术手段. 相似文献
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Summary The geometry of the rock joint is a governing factor for joint mechanical and hydraulic behaviour. A new method for evaluating
the aperture distribution, based on measurement of joint surfaces and three dimensional characteristics of each surface, is
developed. This method allows one to determine and visualize the aperture distribution under different normal stresses and
shear displacements, which is difficult to observe experimentally. A new laser scanner system is designed and developed for
joint surface measurements. Special attention is paid to both surfaces’ data gained by measurements and processing, such as
x-y coordinate table modification, data referencing, and matching between upper and lower surfaces. The surfaces of an artificial
joint in granite are measured, processed, analyzed and three dimensional approaches are carried out for surface characterization.
Parameters such as “asperity’s heights”, “slope angles”, and “aspects” distribution at micro scale, local concentration of
elements and their spatial localization at local scale are determined by Geographic Information System (GIS). These parameters
are used for joint surfaces matching and its real behavior quantitative analysis. The upper surface is brought down to make
contact with the lower surface and the distance between the two surfaces is evaluated from the joint mean experimental aperture,
which is obtained from normal and shear tests. Changes of aperture distribution at different normal stresses and various shear
displacements are visualized and interpreted. Increasing normal load causes negative changes in aperture frequency distribution
which indicates high joint matching. However, increasing shear displacement causes a rapid increase in the aperture and positive
changes in the aperture frequency distribution, which could be due to un-matching, surface anisotropy and spatial localization
of contact points with proceeding shear.
Author’s address: Mostafa Sharifzadeh, Department of Mining, Metallurgy and Petroleum Engineering, Amirkabir University of
Technology, Hafez 424, Tehran 15875-4413, Iran 相似文献
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The Enhanced Geothermal System (EGS) is an artificial geothermal system that aims to economically extract heat from hot dry rock (HDR) through the creation of an artificial geothermal reservoir. Chemical stimulation is thought to be an effective method to create fracture networks and open existing fractures in hot dry rocks by injecting chemical agents into the reservoir to dissolve the minerals. Granite is a common type of hot dry rock. In this paper, a series of chemical stimulation experiments were implemented using acid and alkaline agents under high temperature and pressure conditions that mimic the environment of formation. Granite rock samples used in the experiments are collected from the potential EGS reservoir in the Matouying area, Hebei, China. Laboratory experimental results show that the corrosion ratio per unit area of rock is 3.2% in static acid chemical experiments and 0.51% in static alkaline chemical experiments. The permeability of the core is increased by 1.62 times in dynamic acid chemical experiments and 2.45 times in dynamic alkaline chemical experiments. A scanning electron microscope analysis of the core illustrates that secondary minerals, such as chlorite, spherical silica, and montmorillonite, were formed, due to acid-rock interaction with plagioclase being precipitated by alkaline-rock interactions. Masking agents in alkaline chemical agents can slightly reduce the degree of plagioclase formation. A chemical simulation model was built using TOUGHREACT, the mineral dissolution and associated ion concentration variation being reproduced by this reactive transport model. 相似文献
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Exurbia from the bottom-up: Confronting empirical challenges to characterizing a complex system 总被引：2，自引：0，他引：2
Daniel G. Brown Derek T. Robinson Li An Moira Zellner William Rand Rick Riolo Bobbi Low 《Geoforum》2008,39(2):805-818
We describe empirical results from a multi-disciplinary project that support modeling complex processes of land-use and land-cover change in exurban parts of Southeastern Michigan. Based on two different conceptual models, one describing the evolution of urban form as a consequence of residential preferences and the other describing land-cover changes in an exurban township as a consequence of residential preferences, local policies, and a diversity of development types, we describe a variety of empirical data collected to support the mechanisms that we encoded in computational agent-based models. We used multiple methods, including social surveys, remote sensing, and statistical analysis of spatial data, to collect data that could be used to validate the structure of our models, calibrate their specific parameters, and evaluate their output. The data were used to investigate this system in the context of several themes from complexity science, including have (a) macro-level patterns; (b) autonomous decision making entities (i.e., agents); (c) heterogeneity among those entities; (d) social and spatial interactions that operate across multiple scales and (e) nonlinear feedback mechanisms. The results point to the importance of collecting data on agents and their interactions when producing agent-based models, the general validity of our conceptual models, and some changes that we needed to make to these models following data analysis. The calibrated models have been and are being used to evaluate landscape dynamics and the effects of various policy interventions on urban land-cover patterns. 相似文献
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This paper presents a numerical formulation of a three dimensional embedded beam element for the modeling of piles, which incorporates an explicit interaction surface between soil and pile. The formulation is herein implemented for lateral loading of piles but is able to represent soil–pile interaction phenomena in a general manner for different types of loading conditions or ground movements. The model assumes perfect adherence between beam and soil along the interaction surface. The paper presents a comparison of the results obtained by means of the present formulation and by means of a previously formulated embedded pile element without interaction surface, as well as reference semi‐analytical solutions and a fully 3D finite element (FE) model. It is seen that the proposed embedded element provides a better convergence behavior than a previously formulated embedded element and is able to reproduce key features of a full 3D FE model. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献