80 research outputs found

    Land use detection in Nusajaya using higher-order modified geodesic active contour model

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    Urban development is a global phenomenon. In Johor, especially Nusajaya is one of the most rapidly developing cities. This is due to the increase of land demand and population growth. Moreover, land-use changes are considered to be one of the major components of current environmental monitoring strategies. In this context, image segmentation and mathematical model offers essential tools that can be used to analyze land use detection. The image segmentation process is known as the most important and difficult task in image analysis. Nonlinear fourth-order models had shown to have a good achievement in recovering smooth regions. Therefore, these motivate us to propose a fourth-order modified geodesic active contour (GAC) model. In the proposed model, a modified signed pressure force (SPF) function has been defined to segment the inhomogeneous satellite images. The simulations of the fourth-order modified GAC model through some numerical methods based on the higher-order finite difference method (FDM) have been illustrated. Matlab R2015a software in Windows 7 Ultimate on Intel (R) Core (TM) i5-3230M @ 2.60GHz CPU with 8 GB RAM has been considered as a computational platform for the simulation. Qualitative and quantitative differences between modified SPF functions and other SPF functions have been shown as a comparison. Hence land use detection is very useful for local governments and urban planners to enhance the future sustainable development plans of Nusajaya

    Kinematics and Convergent Tectonics of the Northwestern South American Plate During the Cenozoic

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    The interaction of the northern Nazca and southwestern Caribbean oceanic plates with northwestern South America (NWSA) and the collision of the Panama-Choco arc (PCA) have significant implications on the evolution of the northern Andes. Based on a quantitative kinematic reconstruction of the Caribbean and Farallon/Farallon-derived plates, we reconstructed the subducting geometries beneath NWSA and the PCA accretion to the continent. The persistent northeastward migration of the Caribbean plate relative to NWSA in Cenozoic time caused the continuous northward advance of the Farallon-Caribbean plate boundary, which in turn resulted in its progressive concave trench bending against NWSA. The increasing complexity during the Paleogene included the onset of Caribbean shallow subduction, the PCA approaching the continent, and the forced shallow Farallon subduction that ended in the fragmentation of the Farallon Plate into the Nazca and Cocos plates and the Coiba and Malpelo microplates by the late Oligocene. The convergence tectonics after late Oligocene comprised the accretional process of the PCA to NWSA, which evolved from subduction erosion of the forearc to collisional tectonics by the middle Miocene, as well as changes of convergence angle and slab dip of the Farallon-derived plates, and the attachment of the Coiba and Malpelo microplates to the Nazca plate around 9 Ma, resulting in a change of convergence directions. During the Pliocene, the Nazca slab broke at 5.5°N, shaping the modern configuration. Overall, the proposed reconstruction is supported by geophysical data and is well correlated with the magmatic and deformation history of the northern Andes

    AUTOMATED APPROACHES FOR SALT DOME DETECTION FROM 2D AND 3D SEISMIC DATA

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    Synthesis of finite displacements and displacements in continental margins

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    The scope of the project is the analysis of displacement-rate fields in the transitional regions between cratonal and oceanic lithospheres over Phanerozoic time (last 700 ma). Associated goals are an improved understanding of range of widths of major displacement zones; the partition of displacement gradients and rotations with position and depth in such zones; the temporal characteristics of such zones-the steadiness, episodicity, and duration of uniform versus nonunifrom fields; and the mechanisms and controls of the establishment and kinematics of displacement zones. The objective is to provide a context of time-averaged kinematics of displacement zones. The initial phase is divided topically among the methodology of measurement and reduction of displacements in the lithosphere and the preliminary analysis from geologic and other data of actual displacement histories from the Cordillera, Appalachians, and southern North America

    Digital image processing and isostatic studies of the regional gravity field of Great Britain and adjacent marine regions

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    This thesis presents the results of an investigation into the regional gravity field of Great Britain and the adjacent regions. A prerequisite for this study was the development of a computer database designed to store, manipulate and display the information contained within nearly 400,000 gravity and topography point observations for the region. Digital image processing techniques have been applied to the reduction and display of the Bouguer anomaly data. The observed Bouguer anomaly lineaments display a pattern of geological basement structures which correlates closely with those predicted by recent plate tectonic models of the Lower Palaeozoic Caledonian orogeny which assume the convergence of three distinct continental plates. The nature of the isostatic compensation of the topography in the vicinity of the United Kingdom has been investigated using cross spectral analysis of the gravity and topography. The observed cross spectral relationships are compared with those for a theoretical isostatic model which assumes the lithosphere behaves like a thin elastic plate loaded by both surface topography and internal density contrasts overlying an inviscid fluid substratum. For a uniform elastic thickness of the continental lithosphere the best fit between the observed and theoretical relationships is obtained for values of the elastic thickness of the lithosphere of 22.5-24.5 km. A better fit is obtained if the continental lithosphere is assumed to comprise a population of distinct tectonic provinces of equal area with the values of the elastic thickness of the lithosphere for the provinces distributed uniformly between 6-8 km and 86-90 km. Detailed investigations into the structure of the crust beneath the Tertiary igneous complexes of Mull and Skye, northwest Scotland, indicate a possible slight thickening of the crust which is considered to be an important consequence of the mechanism of the emplacement of the complexes

    Three-dimensional structure and kinematics of the Piedras-Girardot foldbelt in the northern Andes of Colombia

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    Detailed geologic mapping, strain analysis, and simple stratigraphic principles indicate that deformation in the Piedras-Girardot foldbelt in the northern Andes began in the early Campanian with incipient propagation of faults that uplifted gentle domes where the accumulation of some sandy units did not take place. Maastrichtian unroofing of a metamorphic terrane west of the Piedras-Girardot foldbelt is documented by a conglomerate that was deformed shortly after deposition developing a conspicuous intragranular fabric of microscopic veins that accommodate little extension (between 1 and 2 percent in a general northeast-southwest direction). This extensional fabric, distortion of fossil molds, and a moderate cleavage most likely developed concurrently, during and after incipient late Cretaceous folding, but before large scale Paleogene faulting and folding. Cleavage also seems to record small amounts of contraction in a general northwest-southeast direction. Paleogene folding and thrust sheet propagation is recorded by syntectonic strata, and records westward to southwestward propagation of faults. Mesoscopic fabric elements associated with continuous Paleogene deformation are nearly absent, and apparently were passively rotated and translated along thrust sheets. Neogene deformation took place only in the norhtwestern flank of this foldbelt. As a result of this history of deformation, a complex array of faults and folds exists: northwest- and west-verging thrust faults, north- and northeastverging normal faults, and north- and northeast-trending strike-slip faults. Changes in the structural trend delineate a sigmoidal sinistral stepover in this dextral system, with faults verging outwardly in opposite directions defining a positive flower structure
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