Abstract. Personalized education is a very hot topic in distant research. To realize personalized E-learning, a personalized recommendation service system was proposed and realized. Web technologies of personality and adaptive filtering were applied in the system. The structure of system, workflow and key technologies of realizing feature selection module, user interest module, personalized teaching resources filtering module were introduced in the paper.

To study the wake development characteristics of wind farms in complex terrains, two different types of Light Detection and Ranging (LiDAR) were used to conduct the field measurements in a mountain wind farm in Hebei Province, China. Under two different incoming wake conditions, the influence of wind shear, terrain and incoming wind characteristics on the development trend of wake was analyzed. The results showed that the existence of wind shear effect causes asymmetric distribution of wind speed in the wake region. The relief of the terrain behind the turbine indicated a subsidence of the wake centerline, which had a linear relationship with the topography altitudes. The wake recovery rates were calculated, which comprehensively validated the conclusion that the wake recovery rate is determined by both the incoming wind turbulence intensity in the wake and the magnitude of the wind speed.

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