Cool stars at giant and supergiant evolutionary phases present low velocity and high density winds, responsible for the observed high mass-loss rates. Although presenting high luminosities, radiation pressure on dust particles is not sufficient to explain the wind acceleration process. Among the possible solutions to this still unsolved problem, Alfvén waves are, probably, the most interesting ...

The possibility of velocity shear-induced linear transformations of different magnetohydrodynamic waves in the solar wind is studied both analytically and numerically. A quantitative analysis of the wave transformation processes for all possible plasma-β regimes is performed. By applying the obtained criteria for effective wave coupling to the solar wind parameters, we show that velocity sheari...

The surface current response to winds is analyzed in a two-year time series of a 12 MHz (HF) Wellen Radar (WERA) off the West coast of France. Consistent with previous observations, the measured currents, after filtering tides, are of the order of 1.0 to 1.8% of the wind speed, in a direction 10 to 40 degrees to the right of the wind, with systematic trends as a function of wind speed. This Lag...

This study investigates the effect of stratospheric sudden warmings (SSWs) on planetary wave (PW) activity in the mesosphere–lower thermosphere (MLT). PW activity near 95 km is derived from meteor wind data using a chain of eight SuperDARN radars at high northern latitudes that span longitudes from 150W to 25 E and latitudes from 51 to 66 N. Zonal wave number 1 and 2 components were extracted f...

A comprehensive control strategy, for the variable speed cage induction achine that addresses the control objectives in a wind generation system,i.e.control of the local bus voltage to avoid voltage rise, capture of maximum power in the wind. The control signals are the desired current wave shapes of the rectifier and the inverter in a double–sided PWM converter system connected between the win...

The influence of spatial and temporal variations in wind forcing on the circulation in lakes is investigated using field data and the three-dimensional Estuary and Lake Computer Model (ELCOM) applied to Lake Kinneret. Lake Kinneret field data from six thermistor chains and eight wind anemometers deployed during July 2001 are presented. Internal wave motions are well reproduced by the numerical ...

Hydroelectric power plants’ open-type surge tanks may be built in mountains subject to the provision of atmospheric air. Hence, a ventilation tunnel is indispensable. The air flow in the ventilation tunnel is associated with the fluctuation of water-level in the surge tank. There is a great relationship between the wind speed and the safe use and project investment of ventilation tunnels. To ob...

Numerical simulation of wind waves in the bays of south-west part of the Crimea Peninsula is carried out with high space resolution. Particular attention is paid to the local characteristics of wind waves in the Sevastopol Bay. The parallel version of wind wave spectral model SWAN is implemented. The steady state waves caused by wind of different directions are considered. It is obtained that t...

[1] Sea-surface slope probability density functions, which are usually fitted to a GramCharlier series, can be fit equally well by a bound wave/free wave model in which the distributions of bound and free waves are Gaussian. Bound waves are generated by longer waves on the surface and travel at nearly the phase speed of the long wave while free waves are generated directly by the wind and trave...

A simple coupled flux and sea state model is developed. It is applicable to low, moderate, and high wind speeds, with a nonarbitrary wave age. It is fully consistent with an atmospheric flux parameterization. The flux model includes the influence of capillary waves on surface stress, which dominate surface stress on a waveperturbed surface for U10 , 7 m s21. The coupled model is verified for co...