SVM后验概率结合改进多尺度MRF的遥感影像分割方法   总被引：1，自引：0，他引：1  

石强  陈凤娥  梅天灿  秦前清 《武汉大学学报(信息科学版)》2013,38(2):195-199

采用SVM方法估计似然概率,克服了混合高斯模型对观测场建模不准确的问题;通过改进的多尺度MRF模型,在标记场建模时充分考虑了各尺度之间和同一尺度内的相关性,进一步准确描述了标记场的统计特性.最后利用改进的建模方法,在序贯最大后验概率估计算法框架下进行影像分割.通过对人工合成影像和实际遥感影像的分割实验结果分析,证明了本文方法能够有效提高分割效果.  相似文献   

Strike‐slip tectonics and basin inversion in the Western Mediterranean: the Post‐Messinian evolution of the Alboran Sea     

P. Martínez‐García  M. Comas  J. I. Soto  L. Lonergan  A. B. Watts 《Basin Research》2013,25(4):361-387

A comprehensive interpretation of single and multichannel seismic reflection profiles integrated with biostratigraphical data and log information from nearby DSDP and ODP wells has been used to constrain the late Messinian to Quaternary basin evolution of the central part of the Alboran Sea Basin. We found that deformation is heterogeneously distributed in space and time and that three major shortening phases have affected the basin as a result of convergence between the Eurasian and African plates. During the Messinian salinity crisis, significant erosion and local subsidence resulted in the formation of small, isolated, basins with shallow marine and lacustrine sedimentation. The first shortening event occurred during the Early Pliocene (ca. 5.33–4.57 Ma) along the Alboran Ridge. This was followed by a major transgression that widened the basin and was accompanied by increased sediment accumulation rates. The second, and main, phase of shortening on the Alboran Ridge took place during the Late Pliocene (ca. 3.28–2.59 Ma) as a result of thrusting and folding which was accompanied by a change in the Eurasian/African plate convergence vector from NW‐SE to WNW‐ESE. This phase also caused uplift of the southern basins and right‐lateral transtension along the WNW‐ENE Yusuf fault zone. Deformation along the Yusuf and Alboran ridges continued during the early Pleistocene (ca. 1.81–1.19 Ma) and appears to continue at the present day together with the active NNE‐SSW trending Al‐Idrisi strike‐slip fault. The Alboran Sea Basin is a region of complex interplay between sediment supply from the surrounding Betic and Rif mountains and tectonics in a zone of transpression between the converging African and European plates. The partitioning of the deformation since the Pliocene, and the resulting subsidence and uplift in the basin was partially controlled by the inherited pre‐Messinian basin geometry.  相似文献   

On the evaluation of the gravity effects of polyhedral bodies and a consistent treatment of related singularities   总被引：4，自引：2，他引：2  

M. G. D’Urso 《Journal of Geodesy》2013,87(3):239-252

We show that the singularities which can affect the computation of the gravity effects (potential, gravity and tensor gradient fields) can be systematically addressed by invoking distribution theory and suitable formulas of differential calculus. Thus, differently from previous contributions on the subject, the use of a-posteriori corrections of the formulas derived in absence of singularities can be ruled out. The general approach presented in the paper is further specialized to the case of polyhedral bodies and detailed for a rectangular prism having a constant mass density. With reference to this last case, we derive novel expressions for the related gravitational field, as well as for its first and second derivative, at an observation point coincident with a prism vertex and show that they turn out to be more compact than the ones reported in the specialized literature.  相似文献   

Possibilities of GPS kinematic measurements for geological survey in East Slovakia     

Vladimír Sedlák  Viera Hurčíková  Soňa Molčíková 《地球空间信息科学学报》2013,16(4):21-25

This paper deals with transformation procedures for observed GPS data from the world geodetic system WGS-84 into the national geodetic grid datum S-UTCN (system of united trigonometric cadaster network) and Baa (the Baltic Sea after adjustment). Transformation from WGS-84 into SUTCN is performed most frequently by means of the 7-element Helmert transformation with three identical points. Geodetic network was adjusted by two ways.  相似文献   

Mapping burns and natural reforestation using thematic Mapper data   总被引：2，自引：0，他引：2  

M.J. López García  V. Caselles 《国际地球制图》2013,28(1):31-37

Remote sensing techniques are specially suitable to detect and to map areas affected by forest fires. In this work, Landsat 5 Thematic Mapper (TM) data has been used to study a number of forest fires that occurred in the province of Valencia (Spain) and to monitor the vegetation regeneration over burnt areas.

A reference area (non‐burnt forest) was established to assess the change produced by fire. The radiance in the thermal band (10.4–12.5 μm) and the normalized difference in reflectance between near 1R (0.76–0.90 μm) and middle IR (2.08–2.35 μm) were the most suitable parameters to map burnt areas. This index can also be used for monitoring vegetation regeneration in burnt areas. About a month after the fire, the burns show temperatures of 5–6 °C higher than those found in the reference area, and the vegetation index shows negative values whereas the reference area values remain positive. The differences between the burns and the reference area for the vegetation index decrease with time as vegetation regenerates.  相似文献   

Disentangling Turbulent Gas Diffusion from Non-diffusive Transport in the Boundary Layer     

Kowalski  Andrew S.  Serrano-Ortiz  Penélope  Miranda-García  Gabriela  Fratini  Gerardo 《Boundary-Layer Meteorology》2021,179(3):347-367

Boundary-Layer Meteorology - An analysis based on the law of linear momentum conservation demonstrates unequivocally that the mass fraction is the scalar whose gradient determines gas diffusion,...  相似文献   

渤海海域黄河口凹陷新近系多油水系统油藏成因分析          下载免费PDF全文

胡光义  杨希濮  古莉  范廷恩  王晖  汪珍宇  高云峰 《地学前缘》2012,19(2):95-101

为明确同类油田的开发调整方向和潜力目标,以滚动勘探开发为目的,以A油田为例,探讨了黄河口凹陷中央构造脊北端新近系多油水系统油藏成因。储层与油源断层的有效配置是控制该类油气聚集的关键因素。基于已开发油田井震一体化精细地层对比和储层展布研究,细化了储层空间展布,并结合油源断层特征剖析,系统分析了储-断耦合对油气分布的控制作用。首先,油源断裂垂向活动强弱的差异与储层的匹配控制着油气垂向上主要聚集层位;其次,断裂平面发育程度的差异与储层展布的耦合控制着油气在平面上的分布;再次,储-断接触关系影响着油气的富集和赋存规律。  相似文献   

Geochemical evidence of the 8.2 ka event and other Holocene environmental changes recorded in paleolagoon sediments,southeastern Brazil     

Alethéa E.M. Sallun  William Sallun Filho  Kenitiro Suguio  Marly Babinski  Simone M.C.L. Gioia  Benjamin A. Harlow  Wania Duleba  Paulo E. De Oliveira  Maria Judite Garcia  Cinthia Z. Weber  Sérgio R. Christofoletti  Camilla da S. Santos  Vanda B. de Medeiros  Juliana B. Silva  Maria Cristina Santiago-Hussein  Rosana S. Fernandes 《Quaternary Research》2012,77(1):31-43

The paleoclimatic record of Juréia Paleolagoon, coastal southeastern Brazil, includes cyclic and gradual changes with different intensities and frequencies through geological time, and it is controlled by astronomical, geophysical, and geological phenomena. These variations are not due to one single cause, but they result from the interaction of several factors, which act at different temporal and spatial scales. Here, we describe paleoenvironmental evidence regarding climatic and sea level changes from the last 9400 cal yr BP at the Juréia Paleolagoon — one of the main groups of protected South Atlantic ecosystems. Geochemical evidences were used to identify anomalies from multi-proxy analyses of a paleolagoon sediment core. The anomalies of centennial scale were correlated to climate and transgression–regression cycles from the Holocene period. Decadal scale anomalous oscillations in the Quaternary paleolagoon sediments occur between 9400 and 7500 cal yr BP, correlated with long- and short-term natural events, which generated high sedimentation rates, mainly between 8385 and 8375 cal yr BP (10 cm/yr). Our results suggest that a modern-day short-duration North Atlantic climatic event, such as the 8.2 ka event, could affect the environmental equilibrium in South America and intensify the South American Summer Monsoon.  相似文献   

Transformations of rock-forming minerals under stepwise shockwave compression of quartz-feldspar-biotite-garnet schist from the Southern Urals     

I. V. Belyatinskaya  V. I. Fel’dman  V. V. Milyavsky  T. I. Borodina  A. A. Belyakov 《Moscow University Geology Bulletin》2012,67(1):30-42

Patterns in the shock metamorphic transformations of rock-forming minerals (garnet, biotite, plagioclase, and K-feldspar) in quartz-feldspar-biotite-garnet schist (the Southern Urals) that were subjected to shockwave compression using planar geometry recovery ampoules were investigated. The maximum shock pressures that were attained upon a few wave circulations in a sample (stepwise shock compression) reached 26, 36, and 52 GPa. Comparison of the transformations that occurred due to stepwise shock compression with diaplectic changes of the studied minerals in nature and in the course of experiments with convergent spherical shock waves revealed significant differences in the transformations of melanocratic (garnet and biotite) minerals under different types of loading.  相似文献   

Reactive infiltration instability of a granitization front during the generation and development of granite-gneiss domes     

A. A. Pek  V. I. Mal’kovsky  S. P. Korikovsky 《Petrology》2012,20(3):205-217

The origin of granite-gneiss domes is traditionally attributed to gravity tectonics, the ascent of granite-gneiss diapirs in a gravitational field owing to a relative decrease in the density of granitized rocks compared with their protolith. This is usually considered by the example of a two-layer medium with a lower layer of granitized rocks overlain by a denser protolith layer; the development of gravitational instability in the system results in the ascent of a granite-gneiss diapir. However, the diapiric process can be initiated only if Archimedes?? buoyancy forces at the roof of the granite-gneiss layer will overcome the resistance of the protolith rocks related to their long-term strength. Under the conditions of plastic deformations, this requires the existence of a large-scale irregularity in the relief of the layer boundary, namely, an antiform cusp in the roof of the granite-gneiss layer. The model is based on the assumption that such antiforms appear owing to the reactive infiltration instability of the morphology of the granitization front caused by an increase in the fluid permeability of granitized rocks compared with that of the protolith. The results of computer modeling support the geological feasibility of the reactive infiltration mechanism of the generation and development of the protodiapiric forms of the granitization front triggering the development of the diapiric process of the gravitational upwelling of granite-gneiss domes. The model of a protodiapir stage allows us to consider dome formation as a result of the development of two sequential instabilities: the reactive infiltration instability of the granitization front related to an increase in the permeability of the transformed rock followed by the gravitational instability related to a relative decrease in rock density.  相似文献