High speed wind tunnels are widely used in the study of fluid flow behavior around various objects. The air flow in the starting step of supersonic wind tunnels is transient including strong shock waves caused by the interaction of the tunnel main stream and the boundary layer at walls. To arrive in running step, the tunnel must be designed so as these waves leave immediately the test section. ...

[1] The solar wind is filled with strong current sheets and sudden velocity shears; often the two are co-located. Sudden velocity shears at 1 AU are statistically analyzed using ACE measurements from 1998 to 2008. The occurrence rates of passage and the orientations of the shear planes are examined. For shear layers with vector velocity changes |Dv| > 50 km/s, an average of 12 pass the Earth pe...

The operation of wind energy conversion systems mainly deals with variable and unpredictable wind regimes resulting in variable power efficiency. In addition, nowadays with the presence of high penetration level of wind farms integrated to power systems, stability and power quality problems might be addressed, when a disturbance event occurs. These challenges are worsened with significant degre...

The most common controller in wind turbine is the blade pitch angle control in order to get the desired power. Controlling the pitch angle in wind turbines has a direct impact on the dynamic performance of the machine and fluct­uat­io­ns in the power systems. Due to constant changes in wind speed, the wind turbines are of nonlinear and multivariate system. The design of a controller that can ad...

Wind Energy Generation Systems (WECS) are confronted with increasing demands for power quality and harmonic distortion control. With the advances in power electronics technology, the rapid growth of variable speed WECS is now witnessed. However, the power quality still remains an important issue to be addressed thoroughly by researchers. This paper presents a comparative study on grid connected...

One of the greatest challenges associated with wind power is the unpredictable character of the wind. Wind energy is one of the lowest-priced renewable energy technologies available today, costing between 4 and 6 cents per kilowatt-hour, depending upon the wind resource and project financing of the particular project. In our research, a design and modeling technique has been proposed to optimiz...

urbanization expanse and population growth, as well as pilgrim's possibility of some cities provide overuse of vehicles and consequently increased air pollution. thus by considering the importance of the impact of air pollution on human health, in this study, air pollution in terms of pm10 using psi standard index and inverse distance weighting is zoned in mashhad. on the other hand, meteo...

in this paper the maximum power point tracking (mppt) algorithms for wind energy systems arereviewed. as the amounts of power produced in wind power plants is changing due to theinstantaneous changing nature of the wind, it is desirable to determine the one optimal generatorspeed that ensures maximum energy yield. thus, it is important to include a controller that cantrack the maximum peak rega...