Wind turbines operate mostly in yaw conditions that give rise to cyclic variations in aerodynamic forces applied on the blade. This induced load fluctuation is closely related to the upstream velocity field of the rotor and can be a significant source of fatigue and vibration. An accurate prediction of blade loading is considered the key in designing reliable and efficient wind turbines. The related calculation remains a complicated task to perform and requires enormous computing time. In this context, a numerical method is presented, aimed at evaluating the azimuthal fluctuation of the normal force. This method is obtained by coupling the Beddoes near-wake model and the free-wake method: the near-wake-induced velocities are calculated using Beddoes near-wake model with the far-wake contribution evaluated using the free-wake method. In addition, the unsteady effects on the aerodynamic coefficients are taken into account using the Beddoes-Leishman dynamic stall model. A computer code was developed, and numerical values were obtained in acceptable computational time. Results are compared with measurements performed in the NASA Ames wind tunnel.

A new generation of wind turbines, in comparison to the old versions, have been designed with colossal blades to produce a larger amount of power output. However, this has led to some unpredictable challenges including their construction procedure and expenses and particularly blades’ transportation. To overcome these issues, multi-rotor wind turbines have been suggested. The aerodynamic performances of such turbines have been previously assessed by other investigators. However, the wake characteristics of these turbines have been less studied. The focus of the present research is on the assessment of these characteristics, which are crucial in the process of any wind farm design. For this purpose, the wake flow of a small three-rotor wind turbine is numerically simulated using computational fluid dynamics. A numerical simulation has been conducted for a single-rotor wind turbine and three-rotor small horizontal axis wind turbine with an angle of 180⸰ arrangement. The results of a single rotor wind turbine indicated that far downstream wake extended up to 8D, with Jensen-Gaussian model can be better predicted. The comparison between the three-bladed wind turbine and the results of wake models for the equivalent turbine showed that because of wake interactions in downstream of the rotor, the loss of turbulent kinetic energy and recovery of the stream speed will be faster. As a result, in the wind farms, the turbines in closer distances around 4D of the equivalent single-rotor wind turbine can be installed.

Background and Objective: Wind is a clean and abundant of source of energy which is completely renewable. Large wind farms are being built around the world as a way to generate electricity, but operators still seeking the most effective arrangement of wind turbines in the wind farm to maximize absorption of wind energy. Wind farm layout optimization is one the way to increase the output of the wind farm. Method: In this paper, a genetic algorithm to maximize the expected energy output was used. The purpose of the genetic algorithm optimization of wind farm was arranged in terms of location, hub height and rotor diameter of the turbines to capture maximum wind energy and reduce the wake effect. The proposed model with two scenarios of wind speed and direction distribution of wind sites are shown on the flat ground. Results: The results of the present study were compared with the previous studies. The results showed by wind farm layout optimization of the place, the hub height and rotor diameter of the turbines, at the same time, has a better performance-in terms of the maximum value of the expected energy output and reduces the wake effect with strategies which optimize with one or two parameters simultaneously. Discussion and Conclusion: The use of wind turbines with a hub height and rotor diameter varies in a wind farm and has the benefits of reducing the wake effect and captures maximum wind energy.

Political Islam is the only active religion discourse in the world claiming to have program for Religion and the Muslim world and to achieve this goal it must gain political power. From its existence the dialogue has triggered different experiences in Islamic countries. The most important victory of the Islamic Revolution in Iran in 1979 and Egypt's Muslim Brotherhood movement was to seize power in 2011 in a democratic way. Islamic Revolution in Iran could have been hegemon in the minds and language of people, But Muslim Brotherhood has a history of more combat power during activity which always has failed. To find the reason of success for Islamic Revolution in 1979 and the failure of the Muslim Brotherhood movement between the years 2011-2013 as two identical understanding of political Islam, is the purpose of the present paper. The question raised in this situation is: what are the advantages of political Islam dialogue in Iran that lack of them for The Muslim Brotherhood movement has caused a failure to gain political power? The findings of the present paper, gained based on Laclau, and Mouffe's discourse analysis, indicate that since the Muslim Brotherhood movement emphasizes on eclectic knowledge, has no evidence of superior leader like Imam Khomeini, and has no signs of the supreme leadership and the inability to control structural power centers, Failed to gain political developments in Egypt during the 2011-2013, and failed to maintain its sovereignty in the political arena facing with military crises and ultimately has pushed into margin.

For optimizing the operational efficiency of a wind farm in complex terrain, the wake study of wind turbines and the detailed analysis of the wind data are essential. In this research, Manjil wind farm located in Alborz Mountains with special topography and distinct wind regime had been studied. OpenFOAM has been applied for Computational fluid dynamics simulations of two wind speeds in different reference heights as case studies. Then, a comparison between the simulation results and available Supervisory control and data acquisition dataset has been done. The result pretended that velocity of the wake is recovered up to 85% after ten times the diameter of the turbine. In this distance, there is a 14.5% and 15.5% speed reduction on average for two simulations, with velocity on the hub height of 9 and 17 m/s respectively. The analysis of raw wind data shows that a high potential of wind energy is available in summer and there is almost no wind in wintertime, which causes some challenges for developing the wind farms under these conditions.

Rhinoplasty surgery changes the shape of the nose. The motivation for rhinoplasty may be to change the appearance of the nose, improve breathing, or both. A 25-year-old patient was referred to the Basir clinic for a visual evoked potential (VEP) examination. The patient complained from far distance blurry vision after rhinoplasty. Her magnetic resonance imaging (HRI) and VEP examination were normal. The present work explains her case.

The small microwave skin depth of sea water as well as the small penetration depth of laser signal in water impose limitations on the application of SAR and Lidar in sea surveillance systems. On the other hand, vessels travelling at sea bring about hydrodynamic anomalies in the sea water called as wake. These hydrodynamic disturbances can be detected by using some techniques such as airborne radio imaging and Extremely Low Frequency (ELF) electromagnetic signal processing. In practice, the motion of conductive sea water anomalies in the natural earth's magnetic field induces ELF magnetic wakes which can be measured via accurate magnetic sensors and detected through signal processing schemes. The physical properties of the hydrodynamic wake as well as those relating to the corresponding magnetic wake are directly related to the vessel parameters such as hull shape, speed and heading. In this work, we firstly derive and formulate the mathematical expressions relating to the aforementioned hydrodynamic and magnetic wakes. By employing derived expressions, a novel detection scheme is proposed based on constructing the 2-dimentional image of the vessel’, s magnetic wake through the magnetic signals captured from an array of magnetic sensors, and finally, the relation between the spectral image of the magnetic wake and the vessel heading is studied. We will show that our proposed scheme can detect the existence of a remote vessel as well as its heading from the constructed image with high accuracy, and moreover, it does not have common limitations of existing single-sensor based heading detection schemes.