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Abstract The characteristics of the wind at 10 m height were studied over a period of 32 months. The sampling interval was 20 ms and the averaging time was 10 min. Probability density functions are given for the speed, direction, inclination and intensity of turbulence of the wind. Frequency contour plots are given for wind speed vs solar time, wind speed vs wind direction, wind speed vs global solar irradiance and wind speed vs the intensity of turbulence of the wind. Differences between the results for day and night and between various seasons are examined.

Abstract The characteristics of the wind at 10 m height were studied over a period of 32 months. The sampling interval was 20 ms and the averaging time was 10 min. Probability density functions are given for the speed, direction, inclination and intensity of turbulence of the wind. Frequency contour plots are given for wind speed vs solar time, wind speed vs wind direction, wind speed vs global solar irradiance and wind speed vs the intensity of turbulence of the wind. Differences between the results for day and night and between various seasons are examined.

Dynamic stall (DS) on a wind turbine is encountered when the sectional angles of attack of the blade rapidly exceeds the steady-state stall angle of attack due to in-flow turbulence, gusts and yaw-misalignment. The process is considered as a primary source of unsteady loads on wind turbine blades and negatively influences the performance and fatigue life of a turbine. In the present article, the control requirements for DS have been outlined for wind turbines based on an in-depth analysis of the process. Three passive control methodologies have been investigated for dynamic stall control: (1) streamwise vortices generated using vortex generators (VGs), (2) spanwise vortices generated using a novel concept of an elevated wire (EW), and (3) a cavity to act as a reservoir for the reverse flow accumulation. The methods were observed to delay the onset of DS by several degrees as well as reduce the increased lift and drag forces that are associated with the DSV. However, only the VG and the EW were observed to improve the post-stall characteristics of the airfoil.

Dynamic stall (DS) on a wind turbine is encountered when the sectional angles of attack of the blade rapidly exceeds the steady-state stall angle of attack due to in-flow turbulence, gusts and yaw-misalignment. The process is considered as a primary source of unsteady loads on wind turbine blades and negatively influences the performance and fatigue life of a turbine. In the present article, the control requirements for DS have been outlined for wind turbines based on an in-depth analysis of the process. Three passive control methodologies have been investigated for dynamic stall control: (1) streamwise vortices generated using vortex generators (VGs), (2) spanwise vortices generated using a novel concept of an elevated wire (EW), and (3) a cavity to act as a reservoir for the reverse flow accumulation. The methods were observed to delay the onset of DS by several degrees as well as reduce the increased lift and drag forces that are associated with the DSV. However, only the VG and the EW were observed to improve the post-stall characteristics of the airfoil.

Abstract Usually, wind sites are equipped with fast-running Horizontal Axis Wind Turbines of the airscrew type, which has a high efficiency. In this article, the argument is put forward that the choice of a wind turbine must not be based only on high efficiency. We propose a comparative criterion adapted to the comparison of a horizontal axis wind turbine with a vertical axis wind turbine: the L–σ criterion. This criterion consists in comparing wind turbines which intercept the same front width of wind, by allocating them a same reference value of the maximal mechanical stress on the blades or the paddles. On the basis of this criterion, a quantitative comparison points to a clear advantage of the Savonius rotors, because of their lower angular velocity, and provides some elements for the improvement of their rotor.

Abstract Usually, wind sites are equipped with fast-running Horizontal Axis Wind Turbines of the airscrew type, which has a high efficiency. In this article, the argument is put forward that the choice of a wind turbine must not be based only on high efficiency. We propose a comparative criterion adapted to the comparison of a horizontal axis wind turbine with a vertical axis wind turbine: the L–σ criterion. This criterion consists in comparing wind turbines which intercept the same front width of wind, by allocating them a same reference value of the maximal mechanical stress on the blades or the paddles. On the basis of this criterion, a quantitative comparison points to a clear advantage of the Savonius rotors, because of their lower angular velocity, and provides some elements for the improvement of their rotor.

Environmental pollution is a principal concern for all countries. In particular, the issue is alarming for Australia as the country has been suffering from various environmental disasters for some recent years. Therefore, examination the roles of some variables that are related to environment are vital. To this end, this work endeavors to ascertain the impacts of industrialization, non-renewable and renewable energy use, and financial development on environmental pollution in Australia. Using the data period of 1990 e2020, a series of econometric techniques such as the Augmented Dickey-Fuller test, Phillips-Perron test, Autoregressive Distributive Lag (ARDL) bounds test and the pairwise Granger causality test are applied. The findings reveal that industrialization and non-renewable energy use increase while the square of industrialization, renewable energy use, and financial development reduces CO2 emissions in Australia. The validation of the environmental Kuznets’ curve (EKC) hypothesis is also found. Bidirectional and unidirectional causal association of the studied variables with CO2 emissions are attained. All the outcomes are theoretically and empirically relevant and have important policy implications.

Environmental pollution is a principal concern for all countries. In particular, the issue is alarming for Australia as the country has been suffering from various environmental disasters for some recent years. Therefore, examination the roles of some variables that are related to environment are vital. To this end, this work endeavors to ascertain the impacts of industrialization, non-renewable and renewable energy use, and financial development on environmental pollution in Australia. Using the data period of 1990 e2020, a series of econometric techniques such as the Augmented Dickey-Fuller test, Phillips-Perron test, Autoregressive Distributive Lag (ARDL) bounds test and the pairwise Granger causality test are applied. The findings reveal that industrialization and non-renewable energy use increase while the square of industrialization, renewable energy use, and financial development reduces CO2 emissions in Australia. The validation of the environmental Kuznets’ curve (EKC) hypothesis is also found. Bidirectional and unidirectional causal association of the studied variables with CO2 emissions are attained. All the outcomes are theoretically and empirically relevant and have important policy implications.

Abstract The purpose of this work is two-fold. First, to introduce a comparison between steady state and dynamic test methods for two different collectors. Second, to design a solar water heating system to satisfy both hot water and space heating demands for a multi-family house in Alexandria, Egypt.

Abstract The purpose of this work is two-fold. First, to introduce a comparison between steady state and dynamic test methods for two different collectors. Second, to design a solar water heating system to satisfy both hot water and space heating demands for a multi-family house in Alexandria, Egypt.

The thermal regulation which is under preparation for Tunisian buildings is based on the thermal comfort level achieved in the building by natural means, since residential buildings are rarely heated or cooled. This paper investigates the appropriate building solutions in order to reach the highest possible comfort level, while keeping the overrun cost of construction at a reduced level.

The thermal regulation which is under preparation for Tunisian buildings is based on the thermal comfort level achieved in the building by natural means, since residential buildings are rarely heated or cooled. This paper investigates the appropriate building solutions in order to reach the highest possible comfort level, while keeping the overrun cost of construction at a reduced level.

For wind farm optimizations with lands belonging to different owners, the traditional penalty method is highly dependent on the type of wind farm land division. The application of the traditional method can be cumbersome if the divisions are complex. To overcome this disadvantage, a new method is proposed in this paper for the first time. Unlike the penalty method which requires the addition of penalizing term when evaluating the fitness function, it is achieved through repairing the infeasible solutions before fitness evaluation. To assess the effectiveness of the proposed method on the optimization of wind farm, the optimizing results of different methods are compared for three different types of wind farm division. Different wind scenarios are also incorporated during optimization which includes (i) constant wind speed and wind direction; (ii) various wind speed and wind direction, and; (iii) the more realisticWeibull distribution. Results show that the performance of the new method varies for different land plots in the tested cases. Nevertheless, it is found that optimum or at least close to optimum results can be obtained with sequential land plot study using the new method for all cases. It is concluded that satisfactory results can be achieved using the proposed method. In addition, it has the advantage of flexibility in managing the wind farm design, which not only frees users to define the penalty parameter but without limitations on the wind farm division.