design and construction of efficient and economic reinforced concrete (r.c.) hyperbolic cooling towers have driven the engineers toward the design of tall and thin-shell towers which have considerable high slenderness aspect ratio. consequently, the shell of r.c. cooling towers with relative high slenderness aspect ratio is extremely prone to buckling instability due to wind loading. to increas...

A 915-MHz boundary layer wind profiler with radio acoustic sounding system (RASS) was sited 8 km from a very tall (450 m) television transmitting tower in north-central Wisconsin during the spring, summer, and autumn of 1995. The profiler measured wind means and variances, and the RASS attachment measured virtual temperature. These quantities are compared to measurements from cup and sonic anem...

Due to the wind speed variation, wind shear and tower shadow effects, grid connected wind turbines are the sources of power fluctuations which may produce flicker during continuous operation. This paper presents a model of an MW-level variable speed wind turbine with a doubly fed induction generatorto investigate the flicker emission and mitigation issues. An individual pitch control (IPC) stra...

We investigate the suppression of the vibrations of a wind turbine tower using colocated feedback to achieve strong stability. We decompose the system into one model describing the vibrations in the plane of the turbine axis and another model in the plane of the turbine blades. In the plane of the turbine axis, we obtain a non-uniform Spacecraft Control Laboratory Experiment (SCOLE) model with ...

This research introduces an advanced forging method to produce the door frame of the wind turbine tower. The advantage of the new forging method is the increase of raw material utilization ratio and the energy saving. In the conventional method, the door frame is hot forged with a hydraulic press and machined out lots of material because of the big difference between forging shape and final mac...

This paper is a synopsis of the results of a research on the wind catcher, the cooling systems in traditional Iranian architecture which used in cities with hot-dry and hot-humid climates. This review demonstrates wind towers' characteristics with emphasis on their morphology. Different ratios between different elements of wind catcher such as its plan’s length to width, its tower height to she...

Aerodynamic roughness length 0 ) and displacement height 0 ) are important surface parameters for estimating surface fluxes in numerical models. These parameters are generally determined from wind flow characteristics using logarithmic wind profiles measured at a meteorological tower or by balloon release. It would be an advantage to use measurements of land surface characteristics instead of w...

In recent years, individual pitch control has been developed for wind turbines, with the purpose of reducing blade and tower loads. Such algorithms depend on reliable sensor information. The azimuth angle sensor, which positions the wind turbine rotor in its rotation, is quite important. This sensor has to be correct as blade pitch actions should be different at different azimuth angle as the w...