178,017 research outputs found
L’insufficienza respiratoria come patologia di una funzione vitale: conseguenze in acuto e in cronico
No full textA mixed-mode cohesive model accounting for small to large openings transition
No full textThis work addresses the formulation of a new mixed-mode cohesive model, able to handle the transition from small to large openings: the proposed model is an extension of the isotropic damage model formulated in [Confalonieri and Perego, JSSCM, 11-2, 2017] for the simulation of mixed-mode delamination with variable mode-ratio, under the assumption of small relative displacements
Combining a weather generator and a standard sensitivity analysis method to quantify the relevance of weather variables on agrometeorological models outputs
No full textSensitivity analysis (SA) is increasingly used to explain models behaviour in response to inputs variation. Agrometeorologists are used to apply standard SA methods only on model parameters because of the difficulty of applying standard sampling techniques to derive series of weather data where each value cannot be sampled independently from those of the neighbouring days and from other variables in the same day. The impact of weather variability on a crop model was here analysed by coupling the Morris SA method to a weather generator. Spring barley in northern Italy was simulated and different outputs considered. Under the explored conditions, parameters involved with temperature generation resulted the most relevant in determining yield and maturity date. Radiation-related parameters were high-ranked for cumulated drainage and actual evapotranspiration. According to the author, this is the first time the sensitivity of a cropping system model to weather variables is quantified using standard SA techniques
Monte Carlo based sensitivity analysis of two crop simulators and considerations on model balance
No full textSensitivity analysis is crucial for building, understanding and using complex mathematical models for agroenvironmental applications. In this study, a variance-based sensitivity analysis was carried out for the first time on CropSyst and WOFOST, two of the crop models most diffused worldwide and different in their degree of mechanism. The scenario assumed for the simulations refers to paddy rice grown in Northern Italy. After screening parameters using the Morris method, the Sobol' approach was used for quantifying their influence on models output variability. Seven out of 34 parameters for WOFOST (mostly involved with CO2 assimilation and photosynthetates conversion into plant organs) and 3 out of 15 for CropSyst (biomass-transpiration coefficient, base temperature and light extinction coefficient) were responsible for about 90% of the total output variability. Assuming the homogeneity among the sensitivity indices of the parameters as an indicator of model balance, the Grubbs test for outliers detection was used to check if the relevance of a parameter (or a few of them) was significantly higher than the others. In the explored conditions (non-limiting for water and nutrients availability), CropSyst resulted unbalanced, being mostly driven by the biomass-transpiration coefficient, whereas no significant differences were identified among the relevance of the WOFOST parameters
1st European Meeting on WARM : a rice modelling experience : preface to the special issue
No full textCoSMo: a simple approach for reproducing plant community dynamics using a single instance of generic crop simulators
No full textGrassland productivity can be estimated using individual-centred models or via crop simulators parameterized to mimic average morphological and physiological features of the phytocoenosis as a whole. Although the latter is often considered an oversimplified solution, individual-centred models are characterized by a degree of complexity that often restricts their use to scientists specialized in pastures modelling or in crop-weed interaction. In this study, an intermediate solution is presented (CoSMo), based on two assumptions allowing the use of a single instance of a generic crop model to simulate phytocoenosis dynamics and productivity. The first is that community parameters can be derived at each time step from the relative presence of the different species and from parameter values determined for the species in monoculture. The second is that inter-specific competition and changes in species relative presence can be simulated as a function of species-specific responses to hierarchically arranged drivers (triggered and continuous) representing the suitability of the different species to the conditions explored at each time step. CoSMo was here analyzed by means of three simulation experiments, where changes in the relative presence of three species with different traits and the productivity of the community were simulated under current conditions and future climate projections. Results encourage further studies, given that the solution proposed is easy to implement and parameterize, and leaves users free to work with the generic crop simulator they are familiar with. These features make CoSMo suitable for being coupled - within integrated studies - to models developed for other domains by scientists not specialist in the ecophysiological aspects involved with inter-specific competition. However, this approach cannot be considered as an alternative to individual-centred models in case of in silico studies explicitly focusing on the relationships between inter-specific competition and species traits and phenotypic plasticity
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