Effect of the wind acceleration magnitude during the first stages of the wind-wave generation process     

Robles-Diaz  Lucia  Ocampo-Torres  Francisco J.  Branger  Hubert  Garcia-Nava  Hector  Osuna  Pedro  Rascle  Nicolas 《Ocean Dynamics》2021,71(10):981-992

Ocean Dynamics - A comprehensive analysis of the wavefield evolution under accelerated wind conditions provides an essential contribution to understanding the wind-wave generation process. A set of...  相似文献   

Polygonal terrains on Mars: A contribution to their geometric and topological characterization   总被引：1，自引：0，他引：1  

Pedro Pina  José Saraiva  Joana Antunes 《Planetary and Space Science》2008,56(15):1919-1924

Detailed examination of large extensions of polygonal terrains on the surface of Mars and extraction of some characteristic geometric and topological parameters is made possible by the application of image analysis methods to scenes of the Martian surface acquired from orbit. This is illustrated by the analysis of a set of diverse Martian networks, clearly visible in MOC/MGS images with high spatial resolution. It is shown that these networks present, in average, a hexagonal habit, and that they verify two classic laws relative to 2D random networks (those of Lewis and Aboav-Weaire). This research can, through the quantified analysis of the differences and similarities between networks, lead into a much better understanding of the origin and dynamics of this type of features.  相似文献   

High-Order Block Support Spatial Simulation Method and Its Application at a Gold Deposit     

de Carvalho  Joao Pedro  Dimitrakopoulos  Roussos  Minniakhmetov  Ilnur 《Mathematical Geosciences》2019,51(6):793-810

Mathematical Geosciences - High-order sequential simulation methods have been developed as an alternative to existing frameworks to facilitate the modeling of the spatial complexity of non-Gaussian...  相似文献   

Integration schemes with substepping algorithms for creep analysis in geomaterials     

Roberto Quevedo  Pedro Firme  Deane Roehl 《国际地质力学数值与分析法杂志》2019,43(7):1467-1487

This paper describes a robust and efficient methodology for predicting displacements, deformations, and stresses in geomaterials that are susceptible to creep. The methodology is based on two integration schemes, which consider substepping algorithms. The first scheme is used for integrating space-time relations in a global sense, whereas the second scheme is used for integrating stress-stain relations in a local sense. Different from previous studies, both integration schemes are easy to implement and general in the sense that they can be applied to any type of creep law. Through an in-house finite element simulator, several numerical tests are performed. They include triaxial and wellbore closure analyses considering soft soils and salt rocks. The results show that the combination of both schemes leads to stable and accurate solutions with reduced computational time.  相似文献   

Detection of early warning signals in paleoclimate data using a genetic time series segmentation algorithm     

Athanasia Nikolaou  Pedro Antonio Gutiérrez  Antonio Durán  Isabelle Dicaire  Francisco Fernández-Navarro  César Hervás-Martínez 《Climate Dynamics》2015,44(7-8):1919-1933

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Comparing access for all: disability-induced accessibility disparity in Lisbon     

David S. Vale  Fernando Ascensão  Nuno Raposo  António Pedro Figueiredo 《Journal of Geographical Systems》2017,19(1):43-64

It is well known that individual impairments create disparities in the accessibility of individuals to opportunities, lengthening the distances or time needed to reach them or even completely impeding access. However, the accurate calculation and representation of these disparities remain a major challenge for urban and transportation planners. In this paper, we adopt the concept of accessibility disparity, originally applied to measure place accessibility by different modes of transport, to measure and represent the accessibility of individuals with physical disabilities compared to those without disabilities. We use spatial network analysis to calculate spatial connectivity and the accessibility of Lisbon’s city center, revealing what we define as ‘disability-induced accessibility disparity’. Our results reveal not only the locations responsible for reduced accessibility, i.e., barriers and/or deterrents to movement, but also how much any given disparity reduces the accessibility of an individual, allowing the use of this methodology by planners to identify critical areas and to design inclusive public spaces.  相似文献   

Modeling the environmental susceptibility of landfill sites in California     

Victor Fernandez Nascimento  Nazli Yesiller  Keith C Clarke  Jean Pierre Henry Balbaud Ometto  Pedro R. Andrade  Anahi Chimini Sobral 《地理信息系统科学与遥感》2017,54(5):657-677

??The proper management of solid waste (SW) is a global environmental challenge. A major issue is the proper disposal of SW while balancing a wide range of criteria and working with different spatial data. In this study, we used geographic information system as a tool to perform multi-criteria decision analysis with an analytical hierarchy process to develop an environmental impact susceptibility model (EISM) for landfills. The model was applied to the state of California, USA and results are presented herein. In particular, the EISM considers factors such as geology, pedology, geomorphology, water resources, and climate as represented by 13 associated environmental indicators. The results of the EISM indicate that more than 75% of California’s territory is situated in areas with very low, low, and medium environmental impact susceptibility categories. However, in the remaining 25% of the state’s land, 61 landfills are located in the high and very high categories. These results are alarming because during the period from 2000 to 2015, these 61 landfills received approximately 308 million tons of SW, which corresponds to more than 57% of all SW disposed in California. The model results can be used toward mitigating the environmental impacts of these facilities.  相似文献   

Estimation of Surface-Layer Scaling Parameters in the Unstable Boundary Layer: Implications for Orographic Flow Speed-Up     

José Luís Argaín  Miguel A. C. Teixeira  Pedro M. A. Miranda 《Boundary-Layer Meteorology》2017,165(1):145-160

A method is proposed for estimating the surface-layer depth \((z_s)\) and the friction velocity \((u_*)\) as a function of stability (here quantified by the Obukhov length, L) over the complete range of unstable flow regimes. This method extends that developed previously for stable conditions by Argaín et al. (Boundary-Layer Meteorol 130:15–28, 2009), but uses a qualitatively different approach. The method is specifically used to calculate the fractional speed-up \((\varDelta S)\) in flow over a ridge, although it is suitable for more general boundary-layer applications. The behaviour of \(z_s \left( L\right) \) and \(u_*\left( L\right) \) as a function of L is indirectly assessed via calculation of \(\varDelta S\left( L\right) \) using the linear model of Hunt et al. (Q J R Meteorol Soc 29:16–26, 1988) and its comparison with the field measurements reported in Coppin et al. (Boundary-Layer Meteorol 69:173–199, 1994) and with numerical simulations carried out using a non-linear numerical model, FLEX. The behaviour of \(\varDelta S\) estimated from the linear model is clearly improved when \(u_*\) is calculated using the method proposed here, confirming the importance of accounting for the dependences of \(z_s\left( L \right) \) and \(u_*\left( L \right) \) on L to better represent processes in the unstable boundary layer.  相似文献   

Mass rig system for shaking table tests of slender columns          下载免费PDF全文

Pedro F. Silva  Arash Sangtarashha  Rigoberto Burgueño 《地震工程与结构动力学》2015,44(15):2717-2736

A new mass rig system is proposed to minimize the deficiencies in current shaking table testing setups. This is accomplished by placing the inertial mass on a convex path designed to impose P‐Delta demands on slender cantilever columns. The design and performance of the mass rig system, and the principles used in deriving the equations of motion and their analytical validation against results obtained from shaking table tests, are presented. Formulation of the governing equations of motion was based on Lagrangian mechanics and solved using an implicit linear acceleration method with an adaptive time step formulation. Friction developed in the sliding system was also incorporated in the equations of motion. Experimental results validated the accuracy in the derivation and solution of the equations of motion. Validated by analytical and experimental results, P‐Delta effects were found to increase the displacement demands on slender columns in the low‐frequency range of acceleration input, while in the high‐frequency range P‐Delta effects led to no increase and in some cases even a reduction in displacement demands. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Coastal vulnerability assessment based on video wave run-up observations at a mesotidal,steep-sloped beach     

Michalis Ioannis Vousdoukas  Dagmara Wziatek  Luis Pedro Almeida 《Ocean Dynamics》2012,62(1):123-137

Coastal imagery obtained from a coastal video monitoring station installed at Faro Beach, S. Portugal, was combined with topographic data from 40 surveys to generate a total of 456 timestack images. The timestack images were processed in an open-access, freely available graphical user interface (GUI) software, developed to extract and process time series of the cross-shore position of the swash extrema. The generated dataset of 2% wave run-up exceedence values R ₂ was used to form empirical formulas, using as input typical hydrodynamic and coastal morphological parameters, generating a best-fit case RMS error of 0.39 m. The R ₂ prediction capacity was improved when the shore-normal wind speed component and/or the tidal elevation η _tide were included in the parameterizations, further reducing the RMS errors to 0.364 m. Introducing the tidal level appeared to allow a more accurate representation of the increased wave energy dissipation during low tides, while the negative trend between R ₂ and the shore-normal wind speed component is probably related to the wind effect on wave breaking. The ratio of the infragravity-to-incident frequency energy contributions to the total swash spectra was in general lower than the ones reported in the literature E _infra/E _inci > 0.8, since low-frequency contributions at the steep, reflective Faro Beach become more significant mainly during storm conditions. An additional parameterization for the total run-up elevation was derived considering only 222 measurements for which η _total,2 exceeded 2 m above MSL and the best-fit case resulted in RMS error of 0.41 m. The equation was applied to predict overwash along Faro Beach for four extreme storm scenarios and the predicted overwash beach sections, corresponded to a percentage of the total length ranging from 36% to 75%.  相似文献