We study the stellar and wind properties of a sample of Galactic O dwarfs to track the conditions under which weak winds (i.e mass loss rates lower than ∼ 10 M⊙ yr) appear. The sample is composed of low and high luminosity dwarfs including Vz stars and stars known to display qualitatively weak winds. Atmosphere models including non-LTE treatment, spherical expansion and line blanketing are comp...

In main-sequence stars, at effective temperatures below ' 20 000 K, radiation ceases to be able to drive a stellar wind. In a rather narrow transition regime, elemental segregation seems possible due to the decoupling of He and, under special circumstances, also of H from the absorbing metal ions in the wind. This effect may even be more pronounced, if the wind is surface modulated, say by a ma...

During the last two decades, renewable wind energy has become increasingly popular as a consequence of strong ecological concerns and appealing advantages with regard to economical energy solutions in remote communities. Furthermore, with very large wind farms emerging, the dispersed renewable wind energy is required to be fully connected to the electrical distribution networks. However, the in...

— In this work, the non-dominated sorting genetic algorithm–II (NSGA-II) is applied to determine the weights of a neural network trained for short-term forecasting of wind speed. More precisely, the neural network is trained to produce the lower and upper bounds of the prediction intervals of wind speed. The objectives driving the search for the optimal values of the neural network weights are ...

We investigate experimentally the early stage of the generation of waves by a turbulent wind at the surface of a viscous liquid. The spatio-temporal structure of the surface deformation is analyzed by the optical method Free Surface Synthetic Schlieren, which allows for time-resolved measurements with a micrometric accuracy. Because of the high viscosity of the liquid, the flow induced by the t...

The performance of 23 World Climate Research Programme (WCRP) Coupled Model Intercomparison Project, phase 3 (CMIP3) models in the simulation of the Indian Ocean dipole (IOD) is evaluated, and the results show large diversity in the simulated IOD intensity. A detailed diagnosis is carried out to understand the role of the Bjerknes dynamic air–sea feedback and the thermodynamic air–sea coupling ...

The field of surface wind blowing over the vast ocean areas is an important parameter for numerical models used for weather forecasts. Surface wind is currently measured from satellites. This provides necessary global coverage; however, measurements of high winds meet some difficulties due to weak dependency of the radarand radiometric signals on the wind velocity at high winds. In [1] a new me...