Search results for " modeling"
showing 10 items of 2411 documents
A Multidisciplinary Approach to the Analysis of Multifactorial Land Mammal Colonization of Islands
2013
A highly debated question that engages paleontologists, zoogeographers, and zoologists is how terrestrial mammals colonize islands. The question’s oversimplification and the subjective and partial responses to it have led to reductionist models. Insular faunas and fossil assemblages result from a complex interaction of geological, biological (in a broad sense), climatic, eustatic, taphonomic, and historical processes. Insular assemblages and their accompanying variables should be investigated on a case-by-case basis. In this article, we discuss not only common misconceptions and their potential origins but also the key issues that should be addressed when dealing with the colonization of is…
Molecular analysis of the fungal microbiome associated with the olive fruit fly Bactrocera oleae
2015
Abstract A molecular approach was used to investigate the fungal microbiome associated with Bactrocera oleae a major key pest of Olea europea , using the ITS2 region of the ribosomal DNA (rDNA) as barcode gene. Amplicons were cloned and a representative number of sequenced fragments were used as barcode genes for the identification of fungi. The analysis of the detected sequence types (STs) enabled the identification of a total of 34 phylotypes which were associated with 10 fungal species, 3 species complexes and 8 genera. Three phylotypes remained unresolved within the order Saccharomycetales and the phylum Ascomycota because of the lack of closely related sequences in GenBank. Cladosporiu…
Effect of attitudes toward Physical Education on motives to sport practice outside school hours
2016
[Resumen] La literatura especializada destaca la relación entre la participación de los adolescentes en actividades físicas y diversos beneficios físicos y psicosociales. Sin embargo, la actividad física de los adolescentes está por debajo de lo necesario para disfrutar de una buena salud física y psicológica. Existe consenso en que la Educación Física puede ayudar a los adolescentes a implicarse en actividades físicas y promover estilos de vida saludables. Por ello, el objetivo de este trabajo ha sido analizar la relación entre las actitudes hacia la Educación Física y los motivos para la práctica deportiva fuera del horario escolar. Han participado 428 alumnos de Educación Secundaria y 1º…
Equation of State for Macromolecules of Variable Flexibility in Good Solvents: A Comparison of Techniques for Monte Carlo Simulations of Lattice Mode…
2007
The osmotic equation of state for the athermal bond fluctuation model on the simple cubic lattice is obtained from extensive Monte Carlo simulations. For short macromolecules (chain length N=20) we study the influence of various choices for the chain stiffness on the equation of state. Three techniques are applied and compared in order to critically assess their efficiency and accuracy: the repulsive wall method, the thermodynamic integration method (which rests on the feasibility of simulations in the grand canonical ensemble), and the recently advocated sedimentation equilibrium method, which records the density profile in an external (e.g. gravitation-like) field and infers, via a local …
Contrail Formation: Analysis of Sublimation Mechanisms
2018
We study losses of ice crystals in a persistent, soot-rich contra i l in the wake behind a medium-sized aircraft at cru i se. Constrain i n g a model covering ice nucleation, growth, and subl i m a t i o n phases with a n aircraft data set, we track the subl i m a t i o n history over two minutes of cont r a i l age and rela t e ice crystal numbers to the number of soot particles emitted by th e aircraft engines.
Physics-Aware Machine Learning For Geosciences And Remote Sensing
2021
Machine learning models alone are excellent approximators, but very often do not respect the most elementary laws of physics, like mass or energy conservation, so consistency and confidence are compromised. In this paper we describe the main challenges ahead in the field, and introduce several ways to live in the Physics and machine learning interplay: encoding differential equations from data, constraining data-driven models with physics-priors and dependence constraints, improving parameterizations, emulating physical models, and blending data-driven and process-based models. This is a collective long-term AI agenda towards developing and applying algorithms capable of discovering knowled…
Numerical modeling and design of a disk-type rotating permanent magnet induction pump
2016
Abstract Electromagnetic induction pumps with rotating permanent magnets appear to be the most promising devices to transport liquid metals in high-temperature applications. Here we present a numerical methodology to simulate the operation of one particular modification of these types of pumps: a disk-type induction pump. The numerical model allows for the calculation and analysis of the flow parameters, including the pressure–flow rate characteristics of the pump. The simulations are based on an iterative fully coupled scheme for electromagnetic and hydrodynamic solvers. The developed model is verified by comparing with experimental data obtained using a Pb-Bi loop test facility, for press…
Sound absorption prediction of linear damped acoustic resonators using a lightweight hybrid model
2019
International audience; A lightweight numerical method is developed to predict the sound absorption coefficient of resonators whose cross-section dimensions are significantly larger compared to the viscous and thermal boundary layer’s thicknesses. This method is based on the boundary layer theory and on the perturbations theory. According to the perturbations theory, in acoustical domains with large dimensions, the fluid viscosity and thermal conductivity only affect the boundary layers. The model proposed in this article combines the lossless Helmholtz wave equation derived from a perfect fluid hypothesis, with viscosity and thermal conductivity values of a real fluid to compute the sound …
Probing the internal solar magnetic field through g-modes
2006
The observation of g-mode candidates by the SoHO mission opens the possibility of probing the internal structure of the solar radiative zone (RZ) and the solar core more directly than possible via the use of the p-mode helioseismology data. We study the effect of rotation and RZ magnetic fields on g-mode frequencies. Using a self-consistent static MHD magnetic field model we show that a 1% g-mode frequency shift with respect to the Solar Seismic Model (SSeM) prediction, currently hinted in the GOLF data, can be obtained for magnetic fields as low as 300 kG, for current measured modes of radial order n=-20. On the other hand, we also argue that a similar shift for the case of the low order g…
Flare diagnostics from loop modeling of a stellar flare observed with XMM-Newton
2006
Abstract XMM-Newton data of an X-ray flare observed on Proxima Centauri provide detailed and challenging constraints for flare modeling. The comparison of the data with the results of time-dependent hydrodynamic loop modeling of this flare allows us to constrain not only the loop morphology, but also the details of the heating function. The results show that even a complex flare event like this can be described with a relatively few – though constrained – components: two loop systems, i.e., a single loop and an arcade, and two heat components, an intense pulse probably located at the loop footpoints followed by a low gradual decay distributed in the coronal part of the loop. The similarity …