The trapezoidal collinear four-body problem     

Martha Alvarez-Ramírez  Mario Medina  Claudio Vidal 《Astrophysics and Space Science》2015,358(1):1-18

  相似文献   

Long-term changes in the frequency,intensity and duration of extreme storm surge events in southern Europe     

Alba Cid  Melisa Menéndez  Sonia Castanedo  Ana J. Abascal  Fernando J. Méndez  Raúl Medina 《Climate Dynamics》2016,46(5-6):1503-1516

  相似文献   

Stochastic Lagrangian trajectory model for drifting objects in the ocean     

R. Mínguez  A. J. Abascal  S. Castanedo  R. Medina 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(8):1081-1093

The prediction of drifting object trajectories in the ocean is a complex problem plagued with uncertainties. This problem is usually solved simulating the possible trajectories based on wind and advective numerical and/or instrumental data in real time, which are incorporated into Lagrangian trajectory models. However, both data and Lagrangian models are approximations of reality and when comparing trajectory data collected from drifter exercises with respect to Lagrangian models results, they differ considerably. This paper introduces a stochastic Lagrangian trajectory model that allows quantifying the uncertainties related to: (i) the wind and currents numerical and/or instrumental data, and (ii) the Lagrangian trajectory model. These uncertainties are accounted for within the model through random model parameters. The quantification of these uncertainties consists in an estimation problem, where the parameters of the probability distribution functions of the random variables are estimated based on drifter exercise data. Particularly, it is assumed that estimated parameters maximize the likelihood of our model to reproduce the trajectories from the exercise. Once the probability distribution parameters are estimated, they can be used to simulate different trajectories, obtaining location probability density functions at different times. The advantage of this method is that it allows: (i) site specific calibration, and (ii) comparing uncertainties related to different wind and currents predictive tools. The proposed method is applied to data collected during the DRIFTER Project (eranet AMPERA, VI Programa Marco), showing very good predictive skills.  相似文献   

Focal depths and mechanisms of Tohoku-Oki aftershocks from teleseismic P wave modeling          下载免费PDF全文

Ling Bai  Lorena Medina Luna  Eric A. Hetland  Jeroen Ritsema 《地震科学（英文版）》2014,27(1):1-13

Aftershocks of the 2011 Tohoku-Oki great earthquake have a wide range of focal depths and fault plane mechanisms. We constrain the focal depths and focal mechanisms of 69 aftershocks with M _w > 5.4 by modeling the waveforms of teleseismic P and its trailing near-surface reflections pP and sP. We find that the “thrust events” are within 10 km from the plate interface. The dip angles of these thrust events increase with depth from ~5° to ~25°. The “non-thrust events” vary from 60 km above to 40 km below the plate interface. Normal and strike-slip events within the overriding plate point to redistribution of stress following the primary great earthquake; however, due to the spatially variable stress change in the Tohoku-Oki earthquake, an understanding of how the mainshock affected the stresses that led to the aftershocks requires accurate knowledge of the aftershock location.  相似文献   

Probabilistic relationships between wind and surface water circulation patterns in the SE Bay of Biscay     

Lohitzune Solabarrieta  Anna Rubio  Mar Cárdenas  Sonia Castanedo  Ganix Esnaola  Fernando J. Méndez  Raúl Medina  Luis Ferrer 《Ocean Dynamics》2015,65(9-10):1289-1303

  相似文献   

Distributed Temperature Sensing to Measure Infiltration Rates Across a Groundwater Recharge Basin     

Ricardo Medina  Christine Pham  Megan H. Plumlee  Adam Hutchinson  Matthew W. Becker  Patrick J. O'Connell 《Ground water》2020,58(6):913-923

Managed aquifer recharge is used to augment groundwater resources and provide resiliency to water supplies threatened by prolonged droughts. It is important that recharge facilities operate at their maximum efficiency to increase the volume of water stored for future use. In this study, we evaluate the use of distributed temperature sensing (DTS) technology as a tool to measure high-resolution infiltration rates at a large-scale recharge facility. Fiber optic cable was laid out inside a spreading basin in a spiral pattern, at two different depths. The cables measured the propagation of diurnal surface water temperature oscillations into the basin depth. The rate of heat propagation is proportional to the velocity of the water, making it possible to estimate the infiltration rate from the temperature measurements. Our results showed that the infiltration rate calculated from DTS, averaged over the entire basin, was within 5% of the infiltration rate calculated using a conventional metering method. The high-resolution data obtained from DTS, both spatially and temporally, revealed heterogeneous infiltration rates throughout the basin; furthermore, tracking the evolution of infiltration rates over time revealed regions with consistently high infiltration rates, regions with consistently low infiltration rates, and regions that evolved from high to low rates, which suggested clogging within that region. Water utilities can take advantage of the high-resolution information obtained from DTS to better manage recharge basins and make decisions about cleaning schedule, frequency, and extent, leading to improved basin management strategies, reduced O&M costs, and increased groundwater recharge.  相似文献   

Spatio-temporal patterns of the interaction between groundwater and surface water in plains     

Cristian Guevara Ochoa  Agustín Medina Sierra  Luis Vives  Erik Zimmermann  Ryan Bailey 《水文研究》2020,34(6):1371-1392

The study of the dynamics of anthropic disturbances that have an effect on the hydrological systems in plains requires integral simulation tools for their diagnosis. The objective of this article is, first, to analyse and reproduce the spatio-temporal interactions between groundwater (GW) and surface water, net recharge, GW level, surface run-off, and evapotranspiration in the upper creek basin of Del Azul, which is located in the centre of the province of Buenos Aires, Argentina, and second, to obtain insights to apply the methodology to other similar situations. For this purpose, a model coupling the semidistributed hydrological model (Soil and Water Assessment Tool [SWAT]) and the hydrogeological model (MODFLOW) has been used. A simulation was carried out for a period of 13 years (2003–2015) on a daily scale. The application of the SWAT–MODFLOW coupling gave good results based on the adjustment between the calculated flows and levels, reaching a Nash–Sutcliffe of 0.6 and R²0.6 at the Seminario hydrometric station located at the watershed outlet point. According to the annual average balance, out of the total rainfall, evapotranspiration accounts for 85%, recharge accounts for 10.2%, and surface run-off accounts for 4.8%. Annual and monthly trends of the stream–aquifer interaction were determined, obtaining on average an annual GW discharge of 34 mm and an annual average recharge of the stream to the aquifer of 1.4 mm. Monthly GW discharges are higher in winter–spring (July to December with an average of 3.3 mm) and lower in summer–autumn (January to June with an average of 2.8 mm). The monthly average recharge of the stream towards the aquifer varies from 0.02 to 0.36 mm and is higher in March, May, and August, when water excess is produced in the basin. Through the analysis of coupled modelling, it is possible to analyse and reproduce the spatio-temporal transitions of flow existing between the stream, the hyporheic zone, and the aquifer.  相似文献   

Evaluation of ASCE 7 equations for designing acceleration sensitive nonstructural components using data from instrumented buildings     

Hamidreza Anajafi  Ricardo A. Medina 《地震工程与结构动力学》2018,47(9):1984-1984

  相似文献   

Drivers of island beach evolution: insights from an island-scale study at Boa Vista (Cabo Verde)     

Cesária Gomes  Ana Nobre Silva  Rui Taborda  Filipe Santos  Luís Rebelo  Aníbal Medina 《地球表面变化过程与地形》2019,44(14):2810-2822

Beach erosion poses significant threat to small island economies which are generally highly dependent on coastal tourism. This work investigates the evolution of the low-lying sandy coast of Boa Vista through an integrated characterization of coastline and shoreline indicators (over the past four decades) based on aerial imagery. It was found that tandem use of the two indicators was important to obtain a reliable perspective of the Boa Vista low-lying coastal evolution across a wide range of coastal environments. Results indicate that between 1968 and 2010 the coast was relatively stable, although some spatial variability was recognized. The largest changes were observed at the tips of embayed beaches and a clear coastal progradation was found at the southern (downwind) coastal sectors. Coastal evolution has been dominated by sediment budget and the results put in evidence the sedimentary connections between the beaches across the island, either through bypass and overpass processes. Findings show that understanding coastal evolution at low-lying islands should be supported on island-scale observations, being the only scale capable to capture the sedimentary connections between beach systems, that often control coastal evolution. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.  相似文献   

Gas tracer transport in a heterogeneous fracture in two-phase flow conditions. Experimental and modeling results     

Jorge Jódar  Agustín Medina  Jesús Carrera 《Advances in water resources》2011,34(11):1401-1412

Large amounts of gas can result from anaerobic corrosion of metals and from chemical and biological degradation of organic substances in underground repositories for radioactive waste. Gas generation may lead to the formation of a buoyant gas phase bubble (i.e. zone with increased gas saturation surrounded by water) and to the migration of radioactive gaseous species. In this situation, gaseous species migration is controlled by (1) advection, dispersion and diffusion within the gas bubble, and (2) dissolution in the water surrounding the gas bubble and diffusion of the dissolved species away from the interface. A number of gas tracer tests were performed in the framework of the GAs Migration (GAM) project to study the role played by dissolution/diffusion phenomena in gas transport. Tracers were selected to display a large range of solubility and diffusion coefficients, which should have led to significant chromatographic separation in the breakthrough curves (BTCs) of the tracers. However, measured BTCs displayed much smaller chromatographic separation than expected. These curves were interpreted using (1) a numerical model of multiphase flow and tracer transport in the fracture plane and diffusion into the immobile water, and (2) a simple two box model. Results showed that dissolution/diffusion into immobile water regions played a small role, and tailing appears to have been largely controlled by diffusion into dead gas volumes, such as boreholes.  相似文献