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Natural Resources Research - Assessing reservoir properties and knowing the relationship between different reservoir parameters can significantly help to plan for production from a reservoir. In... 相似文献
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Estimation of boundary values in a North Atlantic circulation model using an adjoint method 总被引：2，自引：0，他引：2
A 1° × 1° resolution version of the MIT-GCM in the North Atlantic is used to test whether open-boundary conditions can be constrained by observations inside the domain using an adjoint method. In this preliminary feasibility study, the model is run during 1993 with a simplified vertical mixing physics. It is constrained by monthly SST fields, monthly climatological θ, S fields and TOPEX/POSEIDON altimetry. The adjoint model is built using automatic differentiation software. The method aims at bringing the model’s trajectory to consistency with data, by adjusting the initial θ, S fields, the time-varying atmospheric forcing fields and the time-varying open-boundary values. An originality of the work is the ‘nested approach’, which uses optimized fields from a global, coarser resolution model for the open-boundary conditions and for the prior estimates of the surface conditions adjustments. A solution is obtained after 75 iterations. This study shows that significant changes can be obtained on the open-boundary values, and that a general improvement in the circulation is achieved in the constrained solution, mainly in the Gulf Stream and equatorial regions. Changes at the open boundaries are characterized by a large temporal variability and small spatial scales. Large local adjustments are found close to the bottom and are likely unrealistic. There, the method tends to compensate for some model’s deficiencies by computing large corrections on the open-boundary values. The analysis of the cost function gradients with respect to the controls allows us to explore the local consistency between the constraints from the different data sets. This study suggests that no fundamental difficulty emerges when constraining open-boundary values. Its extension to a longer run with complete mixing physics can be envisaged. 相似文献
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This paper presents an inelastic element for the analysis of beams resting on two-parameter foundations. The element is derived from a two field mixed formulation with independent approximation of forces and displacements. The values for the two parameters of the foundation are derived through an iterative technique that is based on an assumption of plane strain for the soil medium. This iterative behavior is repeated at each time step of the nonlinear solution algorithm. The nonlinear response of structures resting on this improved two-parameter foundation model is analyzed following both a Vlasov and a Pasternak approach. Numerical examples that clarify the advantage of the newly developed model are conducted. These studies confirmed the importance of accounting for the foundation second parameter, and the efficiency and accuracy of the proposed model. 相似文献
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RésuméDans ce travail, des modèles de prévision de l’érosion spécifique des bassins versants en insuffisance voire en absence de jaugeages ont été élaborés, en fonction des paramètres climatiques, hydromorphométriques et de la couverture végétale, au droit des sites de barrages et retenues collinaires dans le bassin très érodé qu’est l’Algérois-Hodna-Soummam. Les paramètres régissant l’érosion ont été soigneusement sélectionnés sur la base d’une recherche bibliographique et regroupés en deux catégories distinctes par le biais de l’analyse en composantes principales. Deux méthodes statistiques ont été appliquées: la première, basée sur la régression multiple et la deuxième sur les réseaux de neurones artificiels. Des résultats très satisfaisants sont obtenus en testant, par validation croisée, la validité du modèle neuronal composé de: lame écoulée, densité de drainage, pente moyenne du bassin et précipitation moyenne annuelle comme variables d’entrées avec un coefficient de détermination de 0,81 et une erreur quadratique moyenne de 0,19.Editeur Z.W. Kundzewicz; Editeur associé G. MahéCitation Salhi, C., Touaibia, B., et Zeroual, A., 2013. Les réseaux de neurones et la régression multiple en prédiction de l’érosion spécifique: cas du bassin hydrographique Algérois-Hodna-Soummam (Algérie). Hydrological Sciences Journal, 58 (7), 1573–1580. 相似文献
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On 12th May 2008, a MW7.9 earthquake occurred on the Longmenshan fault in the mountains to the west of Sichuan Province, which shook many Asian cities and killed at least 69 000 people. 相似文献
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Forough Keshvari Z. Hossein Shomali Mohammad Tatar Ayoub Kaviani 《Journal of Seismology》2011,15(2):329-339
Non-linear teleseismic S-phase tomography across the Zagros collision zone in southwestern Iran is used to determine a high-resolution
image of the upper-mantle structure. The inversion was done using 41 high-quality earthquakes recorded by 19 broad-band and
medium-band stations along a 620 km long profile across the collision zone. Smearing from strong crustal velocity anomalies
into the upper-mantle is suppressed by travel-time corrections calculated based on a 3-D crustal model for the study area.
Our results show that the relatively old and cold Arabian shield has a higher velocity (up to 6% faster, at depths between
70 and 300 km) than the younger lithosphere farther north in Central Iran. These two upper-mantle domains are separated by
a sharp near-vertical transition whose surface expression coinciding with the Main Zagros Thrust. 相似文献
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A Greek oil-tanker ran aground, resulting in a huge oil spill along the costal areas of Karachi, Pakistan. The purpose of this study was to assess the lung function and follow up change after one year in subjects exposed to crude oil spill in sea water. It was a cross sectional study with follow up in 20 apparently healthy, non-smoking, male workers, who were exposed to a crude oil spill environment during oil cleaning operation. The exposed group was matched with 31 apparently healthy male control subjects. Pulmonary function test was performed using an electronic Spirometer. Subjects exposed to polluted air have significant reduction in forced vital capacity (FVC), forced expiratory volume in first second (FEV(1)), forced expiratory flow (FEF(25-75%)) and maximum voluntary ventilation (MVV) compared to their matched controls. This impairment was reversible and lung functions parameters were improved when the subjects were withdrawn from the polluted air environment. 相似文献
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François Ayoub Sébastien Leprince Jean-Philippe Avouac 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(6):551-560
We describe and test a procedure to accurately co-register and correlate multi-temporal aerial images. We show that this procedure can be used to measure surface deformation, and explore the performance and limitations of the technique. The algorithms were implemented in a software package, COSI-Corr (available from the Caltech Tectonics Observatory website). The technique is validated on several case examples of co-seismic deformation. First, we measure co-seismic ground deformation due to the 1992, Mw 7.3, Landers, California, earthquake from 1 m resolution aerial photography of the National Aerial Photography Program (United States Geological Survey). The fault ruptures are clearly detected, including small kilometric segments with fault slip as small as a few tens of centimeters. We also obtained similar performance from images of the fault ruptures produced by the 1999 Mw 7.1 Hector Mine, California, earthquake. The measurements are shown to be biased due to the inaccuracy of the Digital Elevation Model, film distortions, scanning artifacts, and ignorance of ground displacements at the location of the tie points used to co-register the multi-temporal images. We show that some of these artifacts can be identified and corrected. 相似文献