نتایج جستجو برای: the wind

تعداد نتایج: 16073694  

In the current study, twin wind blades are designed, fabricated and the effect of various gap ratio (g*) at various angle of attacks (α) on a next to each other twin wind blades are examined in an open-channel wind tunnel. Aerodynamic forces and moments are determined by using three-constraint force balancer. For gap ratio of zero, the aerodynamic attributes are like those of a solitary wind bl...

Journal: :آب و خاک 0
محمد موحدان نادر عباسی مجید کرامتی

abstract wind erosion of soils and suspended particles in iran is one of the serious environmental and agricultural problems which affect agricultural lands, water reservoirs, irrigation canals, drains and etc. therefore wind erosion control needs attention specially in arid and semi-arid regions. although in recent years, some polymeric materials have been used for improvement of structural st...

Journal: :international journal of smart electrical engineering 2013
reza khanzadeh mahmoud reza haghifam

as renewable energy increasingly penetrates into power grid systems, new challenges arise for system operators to keep the systems reliable under uncertain circumstances, while ensuring high utilization of renewable energy. this paper presents unit commitment (uc) which takes into account the volatility of wind power generation. the uc problem is solved with the forecasted intermittent wind pow...

In this paper, a new type of multi-variable compensation control method for the wind energy conversion systems (WECS) is presented. Based on wind energy conversion systems, combining artificial neural network (ANN) control and PID, a new type of PID NN intelligent controller for steady state torque of the wind generator is designed, by which the steady state torque output is regulated to track ...

ژورنال: کواترنری ایران 2018
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Introduction: At present, about 36% of the land surface is covered by arid and semi-arid areas, with 19% of these levels completely dry and no plant life. In Iran, between one third and one-fourth of Iran's dry surfaces are covered with Sand and Sand Dunes. The arid and semi-arid conditions of Iran have caused about 80 million hectares of Iran to be covered by desert areas, sand dunes and insi...

Wind affects adversely the cooling tower thermal performance. A field investigation was carried out to study the thermal performance of Heller cooling towers under wind conditions, involving measurement of wind velocity and its direction around the cooling tower, and obtaining water flow rates and temperatures at the cooling tower inlet and outlet. Results show that air suction at the tower top...

Existing fossil fuels do not meet the needs of modern societies and are almost coming to an end. Hence, governments can respond both to the needs of the people and the industry, by investing in the use of renewable energies. As well as saving fossil fuels, natural gas and even water. According to the research, renewable energy, especially wind energy, has been used in recent years and are able ...

2008
M. Doherty S. Johnston A. J. Green M. S. E. Roberts R. W. Romani B. M. Gaensler F. Crawford

We have made radio continuum, H i and X-ray observations in the direction of the unidentified EGRET source 3EG J1410−6147, using the Australia Telescope Compact Array and the Chandra X-ray Observatory. The observations encompass the supernova remnant (SNR) G312.4–0.4 and the two young pulsars PSRs J1412–6145 and J1413– 6141. We derive a lower distance limit of 6 kpc to the SNR, although interpr...

2008
HENDRIK BARTKO

We consider a situation in which a pulsar (and its nebula) is formed inside or close to a high density regions of a molecular cloud. We apply a recent model for the gamma radiation of pulsar wind nebulae (PWN), which includes not only radiation processes due to injected leptons but also processes due to injection of relativistic hadrons, in order to calculate the expected γ-ray emission from su...

2016
Lei Shang

Abstract: With the rapid development of wind power generations, the inertial response of wind turbines (WTs) are widely concerned recently, which is important for grid frequency dynamic and stability. This paper recognizes and understands the inertial response of type-3 and type-4 WTs from the view of equivalent internal voltage, in analogy with typical synchronous generators (SGs). Due to the ...

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