Topographic relations: developing a heuristic device for conceptualising networked relations     

Rob Inkpen  Peter Collier  Mark Riley 《Area》2007,39(4):536-543

This paper considers whether the deployment of a topographical metaphor may add value to the recent discussion of networked relations. The paper discusses how viewing relations as part of a relational landscape may add a third dimension to the discussion by allowing an appreciation of the strength, or entrenchment, of relations, and how these entrenchments impact on the development of new relations and the resistance to watershed events. The heuristic device is explored through the case of air survey in the 1920s and 1930s. This illustrative case demonstrates how relations are held together, resisted and reformed to different degrees depending on the varying topography of the relational landscape.  相似文献   

岩质边坡的关键块体稳定性影响因素的敏感性研究   总被引：5，自引：0，他引：5  

朱杰 《工程地质学报》2007,15(2):249-252

岩质边坡的关键块体是边坡安全分析和支护设计的重要方面,影响关键块体稳定性的因素较多,本文结合正交试验设计方法,对影响关键块体稳定的重要因素进行敏感性分析,评价不同物理力学参数对关键块体的安全系数的影响程度,为工程提供合理的意见。  相似文献   

基于计划行为理论的樱桃种植户对气候变化与气象灾害适应行为研究   总被引：1，自引：0，他引：1  

李欢娟  史兴民 《气候变化研究进展》2019,15(3):301-312

了解农户气候变化与气象灾害适应行为影响机制对未来制定有效气候变化政策至关重要。基于计划行为理论,利用西安市白鹿原樱桃种植区农户的调查数据,结合结构方程模型分析樱桃种植户气候变化与气象灾害适应行为机制。研究表明,种植户关于气候变化与气象灾害的行为态度、主观规范和知觉行为控制三者之间相互影响,且三者均可直接影响种植户适应气候变化与气象灾害的行为意向,其中行为态度对行为意向的影响最为显著;种植户的知觉行为控制对于气候变化及气象灾害的适应行为影响不显著;种植户对气候变化与气象灾害的行为意向是影响其适应行为最直接的因素。  相似文献   

三维介质中速度结构和界面的联合成像   总被引：16，自引：5，他引：11       下载免费PDF全文

周龙泉  刘福田  陈晓非 《地球物理学报》2006,49(4):1062-1067

根据波逆行原理推导了三维介质中地震波射线走时对界面偏导数的完整基本关系式,并对基本关系式进行简化,得到其在二维和一维介质中的关系式. 给出了任意多个复杂界面情况下,反演时所需的走时对界面偏导数系数矩阵. 为了检验三维介质中速度和界面联合成像理论的有效性,进行了数值模拟计算,很好地对三维速度结构和界面进行了重建.  相似文献   

Estimation of a non-stationary prior covariance from seismic data     

Rasmus Bødker Madsen  Thomas Mejer Hansen  Henning Omre 《Geophysical Prospecting》2020,68(2):393-410

Non-stationarity in statistical properties of the subsurface is often ignored. In a classical linear Bayesian inversion setting of seismic data, the prior distribution of physical parameters is often assumed to be stationary. Here we propose a new method of handling non-stationarity in the variance of physical parameters in seismic data. We propose to infer the model variance prior to inversion using maximum likelihood estimators in a sliding window approach. A traditional, and a localized shrinkage estimator is defined for inferring the prior model variance. The estimators are assessed in a synthetic base case with heterogeneous variance of the acoustic impedance in a zero-offset seismic cross section. Subsequently, this data is inverted for acoustic impedance using a non-stationary model set up with the inferred variances. Results indicate that prediction as well as posterior resolution is greatly improved using the non-stationary model compared with a common prior model with stationary variance. The localized shrinkage predictor is shown to be slightly more robust than the traditional estimator in terms of amplitude differences in the variance of acoustic impedance and size of local neighbourhood. Finally, we apply the methodology to a real data set from the North Sea basin. Inversion results show a more realistic posterior model than using a conventional approach with stationary variance.  相似文献   

Mechanical compaction in heterogeneous clastic formations from plastic–poroelastic deformation principles: theory and applications          下载免费PDF全文

Ran Bachrach 《Geophysical Prospecting》2017,65(3):724-735

Mechanical compaction or loss of porosity due to increase in effective stress is a fundamental geological process that governs many of the rock elastic and transport parameters, all of great importance in exploring and developing subsurface reservoirs. The ability to model the compaction process enables us to improve our understanding of the seismic signature of the basin and better relate the geology of deposition to current porosity, velocity, pore pressure, and other mechanical parameters that depend on the state of compaction of the sediment. In this paper, a set of mathematical equations that can be used to model the plastic deformation associated with primary and secondary loading curves is presented. Compaction laws are posed in terms of natural strain increment formulation often used in plasticity theory to model large deformation. Laboratory and field estimates of constitutive plastic deformation relations for sand–shale mixtures are used in a numerical model that generates estimates of porosity under various pore pressures, shale content, and loading scenarios. These estimates can be used in a variety of settings to predict various basin and reservoir properties associated with different loading conditions and/or sedimentation processes.  相似文献   

Double plane‐wave reverse‐time migration          下载免费PDF全文

Zeyu Zhao  Mrinal K. Sen  Paul L. Stoffa 《Geophysical Prospecting》2017,65(6):1541-1558

We develop a new time‐domain reverse‐time migration method called double plane‐wave reverse‐time migration that uses plane‐wave transformed gathers. Original shot gathers with appropriate data acquisition geometry are double slant stacked into the double plane‐wave domain with minimal slant stacking artefacts. The range of plane‐wave components needed for migration can be determined by estimating the maximum time dips present in shot gathers. This reduces the total number of input traces for migration and increases migration efficiency. Unlike the pre‐stack shot‐profile reverse‐time migration where the number of forward propagations is proportional to the number of shots, the number of forward propagations needed for the proposed method remains constant and is relatively small even for large seismic datasets. Therefore, the proposed method can improve the efficiency of the migration and be suitable for migrating large datasets. Double plane‐wave reverse‐time migration can be performed for selected plane‐wave components to obtain subsurface interfaces with different dips, which makes the migration method target oriented. This feature also makes the method a useful tool for migration velocity analysis. For example, we are able to promptly obtain trial images with nearly horizontal interfaces and adjust velocity models according to common image gathers. Seismic signal coming from steeply dipping interfaces can be included into the migration to build images with more detailed structures and higher spatial resolution as better velocity models become available. Illumination compensation imaging conditions for the proposed method are also introduced to obtain images with balanced amplitudes.  相似文献   

On occurrence of point singularities in orthorhombic media     

Yuriy Ivanov 《Geophysical Prospecting》2019,67(9):2287-2297

Degeneracies of the slowness surfaces of shear (and compressional) waves in low-symmetry anisotropic media (such as orthorhombic), known as point singularities, pose difficulties during modelling and inversion, but can be potentially used in the latter as model parameter constraints. I analyse the quantity and spatial arrangement of point singularities in orthorhombic media, as well as their relation to the overall strength of velocity anisotropy. A classification scheme based on the number and spatial distribution of singularity directions is proposed. In normal orthorhombic models (where the principal shear moduli are smaller than the principal compressional moduli), point singularities can only be arranged in three distinct patterns, and media with the theoretical minimum (0) and maximum (16) number of singularities are not possible. In orthorhombic models resulting from embedding vertical fractures in transversely isotropic background, only two singularity distributions are possible, in contrast to what was previously thought. Although the total number of singularities is independent of the overall anisotropy strength, for general (non-normal) orthorhombic models, different spatial distributions of singularities become more probable with increasing magnitude of anisotropy.  相似文献   

Thinking about Fuel Management: The Potential of Integrative Complexity Theory to Inform Design of Communication about Fuel Management Used To Reduce Wildfire Risk     

Melinda R. Mylek  Jacki Schirmer 《社会与自然资源》2019,32(9):983-1002

Multiple studies have examined ‘what’ people think about fuel management (perceptions); fewer have examined ‘how’ people think about it (structure of thoughts). In an Australian study, we used Integrative Complexity Theory (ICT) to explore the relationship between how complexly people thought about, and how acceptable they found, three fuel management strategies: prescribed burning, mechanical thinning and livestock grazing. Integrative complexity (IC) was associated with the direction of acceptability of the most familiar practice - prescribed burning, but trust in organizations was associated with acceptability of all strategies. IC was associated with the extremity of acceptability, with higher IC associated with more moderate attitudes. Our findings support the argument that targeting communication to (i) match current IC and (ii) encourage growth in complexity of thinking has potential to encourage more moderate and stable attitudes about fuel management.  相似文献   

基于区际负外部性理论的海岸带空间用途管制研究     

李彦平  王煜萍  曹诚为  池源  刘大海 《地理研究》2022,41(10):2600-2614

海岸带是陆海相互作用强烈的特殊界面,其空间利用的负外部性具有典型的跨区域特征,需要以全局性、整体性、系统性的思维实施用途管制。本文引入区际负外部性理论,将研究对象从空间和空间利用转到伴随空间利用所产生的人地（海）关系的演变过程。首先,梳理海岸带空间利用区际负外部性的几种典型表现形式,进而构建海岸带区域系统,并明确了系统间的作用关系;其次,从区域系统作用的视角阐述海岸带空间用途管制的作用机制和具体手段;最后,提出政策建议,以期为海岸带空间用途管制的制度完善提供理论支撑和决策支持。  相似文献