Search results for "Scale model"
showing 10 items of 64 documents
A Grain-Scale Model of Inter-Granular Stress Corrosion Cracking in Polycrystals
2017
In this contribution, we propose a cohesive grain-boundary model for hydrogen-assisted inter-granular stress corrosion cracking at the grain-scale in 3D polycrystalline aggregates. The inter-granular strength is degraded by the presence of hydrogen and this is accounted for by employing traction-separation laws directly depending on hydrogen concentration, whose diffusion is represented at this stage through simplified phenomenological relationships. The main feature of the model is that all the relevant mechanical fields are represented in terms of grain-boundary variables only, which couples particularly well with the employment of traction-separation laws.
Experimental dynamic analysis of elastic-plastic shear frames with secondary structures
2003
Various experimental models are developed to study the influence of lightweight secondary structures on the dynamic response of elastic and elastic-plastic shear frames. Small-scale two-story model frames, with an elastic single-degree-of-freedom secondary structure attached, are considered for sinusoidal and random in-plane support excitation. Both elastic and elastic-plastic responses are recorded by varying the material properties of the columns of a distinguished floor. Parametric studies are performed by varying the secondary structure's fundamental frequency and damping. Experimental results are compared with those obtained by computational simulations. Experimental and numerical resu…
Modelling agricultural risk in a large scale positive mathematical programming model
2020
International audience; Mathematical programming has been extensively used to account for risk in farmers' decision making. The recent development of the positive mathematical programming (PMP) has renewed the need to incorporate risk in a more robust and flexible way. Most of the existing PMP-risk models have been tested at farm-type level and for a very limited sample of farms. This paper presents and tests a novel methodology for modelling risk at individual farm level in a large scale model, called individual farm model for common agricultural policy analysis (IFM-CAP). Results show a clear trade-off between including and excluding the risk specification. Albeit both alternatives provid…
Simulation of extreme heat events over the Valencia coastal region: Sensitivity to initial conditions and boundary layer parameterizations
2019
The Valencia coastal region (Western Mediterranean) is especially sensitive to extreme heat events, where they are really common. However, due to its geophysical characteristics and climatic conditions, the incidence of high and extreme temperatures may still be modulated over this area by means of sea breeze circulations, defining a Sea Breeze Convergence Zone (SBCZ) due to the meet and interaction of these mesoscale conditions and Western synoptic-scale wind regimes. A proper definition of this convergence zone is of significant importance over the study area for the simulation and forecast of intense-heat meteorological events. This study analyses a week period in August 2010 over this a…
Re-evaluation of moisture sources for the August 2002 extreme rainfall episode in central Europe: Evaporation from falling precipitation included in …
2015
Summary Discriminating moisture sources with precision is an important requirement to better understand the processes involved in extreme rainfall episodes. In a previous contribution by Gangoiti et al. (2011b), an innovative technique was presented to assess surface moisture sources contributing to a target precipitation within a Lagrangian framework. The technique was based in transporting parcels of vapor, representing the target precipitation, across a set of nested grids covering a large area at different resolutions. A mesoscale model estimated the meteorological variables to transport and redistribute the vapor back into its original sources, all of them assumed to be at the surface.…
Impact of Initial Soil Temperature Derived from Remote Sensing and Numerical Weather Prediction Datasets on the Simulation of Extreme Heat Events
2016
Extreme heat weather events have received increasing attention and has become of special importance as they can remarkably affect sectors as diverse as public health, energy consumption, water resources, natural biodiversity and agricultural production. In this regard, summer temperatures have become a parameter of essential interest under a framework of a hypothetical increase in the number of intense-heat conditions. Thus, their forecast is a crucial aspect bearing in mind a mitigation of the effects and impacts that these intense-heat situations could produce. The current work tries to reach a better understanding of these sorts of situations that are really common over the Western Medit…
Monsoon onset over Sudan-Sahel: Simulation by the regional scale model MM5.
2006
[1] The Mesoscale Model MM5 is used to study the regional features of the West African Monsoon onset. In order to increase the results, simulations are carried out for eight consecutive seasons (March to September) of the years 1994 to 2001. The results show that the model can reproduce the dynamical features of the monsoon in a reasonably good manner but the seasonal cycle seems enhanced. It is hypothesized that overestimated rainfall amounts could be related to a poor representation of the land surface characteristics. Nevertheless, the mean simulated monsoon onset dates are similar to those find in the CMAP data set. The onset is characterized by an apparent increase in zonal flow that c…
Implementation of non-local boundary layer schemes in the Regional Atmospheric Modeling System and its impact on simulated mesoscale circulations
2016
This paper proposes the implementation of different non-local Planetary Boundary Layer schemes within the Regional Atmospheric Modeling System (RAMS) model. The two selected PBL parameterizations are the Medium-Range Forecast (MRF) PBL and its updated version, known as the Yonsei University (YSU) PBL. YSU is a first-order scheme that uses non-local eddy diffusivity coefficients to compute turbulent fluxes. It is based on the MRF, and improves it with an explicit treatment of the entrainment. With the aim of evaluating the RAMS results for these PBL parameterizations, a series of numerical simulations have been performed and contrasted with the results obtained using the Mellor and Yamada (M…
Regional-scale modeling of reference evapotranspiration: Intercomparison of two simplified temperature- and radiation-based approaches
2015
Two regionalized models for the distributed estimation of daily reference evapotranspiration, the temperature-based Hargreaves (HE) and the radiation-based Makkink (MK) equations, are applied in Southern Italy during the years 2007 and 2008. Spatially distributed meteorological inputs, such as air temperature and incoming solar radiation, were derived from geostatistical interpolation of ground data and from the Land Surface Analysis Satellite Application Facility (LSA-SAF) surface radiation product, respectively. Comparison of the latter with 83,394 daily measurements provided by 128 weather stations shows a not negligible seasonal error in daily solar radiation that is corrected by means …
Modelización computacional cardiaca
2020
Resumen Las enfermedades cardiovasculares tienen en la actualidad un gran impacto social y economico y constituyen una de las principales causas de mortalidad y morbilidad. Los modelos computacionales personalizados del corazon estan demostrando ser utiles tanto para ayudar a comprender los mecanismos subyacentes a las patologias cardiacas como para optimizar su tratamiento prediciendo la respuesta del paciente. En este contexto, se ha puesto en marcha la Red Espanola de Investigacion en Modelizacion Computacional Cardiaca (V-Heart SN). El objetivo general de V-Heart SN es el desarrollo de un modelo computacional multifisico y multiescala integrado del corazon. Este objetivo general se abor…