lightning constitutes the greatest threat to wind power industry. The characteristics of the distributed electric field prior to lightning strike plays an important role in determining lightning discharge attachment point as well as the efficiency of wind turbine protection systems. It was assumed that electric field due to upward initiated lightning might be the same as that of downward initiated lightning. However, more lightning damages which are upward initiated are now highly recorded. In this paper, the blades of a modern sized wind turbine (Vestas V100 with 2 MW rated power, 100 m rotor diameter, and 49 m long blade) are rotated from 0 to 360 degrees and used to investigate the characteristics of the distributed electric field around an operational wind turbine. The model of the extended vertical tri-pole cloud charge distribution model developed with finite element analysis is used to study the variations in maximum electric field strength required for the initiation of upward leader. By comparing the electric field strength as the blade is rotated, the field behavior is evaluated. In addition, experimental evaluations are carried out to support the findings. Result showed that the field around the blade surface and the receptor for an upward initiated lightning is more complex than was assumed and different from downward initiated lightning. This will consequently affect the proficiency of the protection device.

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Wind turbine can be destroyed when not adequately protected by the receptor. According to recent research, the size of the receptor plays a very important role in its efficiency. The effect of receptor size has not been well considered in literature and standards. This paper investigates six receptor sizes (10 mm, 15 mm, 20 mm, 25 mm, 30 mm and 35 mm receptor diameters), encompassing adopted sizes in literature. As the blade is rotated, the interception efficiency of various receptor sizes is evaluated on a modern wind turbine. The vertical tri-pole cloud charge model developed with finite element analysis is used to study the maximum electric field strength required for the initiation of upward leader from the blade surfaces. The interception efficiency of each receptor size is evaluated by comparing the maximum electric field strength. The results of the point of initiation of upward leader match well with those obtained by experimental measurements from lightning discharge attachments.

Mobile Ad-Hoc Networks (MANETs) is a spontaneous network that facilitates communication among nodes without a centralized-control device unlike the infrastructure network category. One of the major challenges with MANETs and Vehicular Ad-Hoc Networks (VANETS) in mobile communication is the problem of connectivity between Mobile Nodes (MNs). This dilemma occurs as a result of high mobility of nodes moving farther from each other in MANETs or VANETS or moving away from the base station as in a cellular network or in a Mobile Infrastructure Ad Hoc Networks (MI-VANETs) as a result of propagation effects. Mobility of nodes is one of the major impacts of routing in every mobile and wireless network because of high dynamic nature of mobile environments. Several factors that influence the evaluation of the networks depend mainly on the implementation of the mobility model and the mobility model in turn depends on several factors of the environment. This paper evaluates the impact of communication and transmission range on network connectivity due to high mobility of nodes in a mobile and wireless environment. The results obtained through derived mobility metrics and Rate Adaption (RA) show that communication range has impact on connectivity in a highly mobile environment such as in vehicular communications. MN in this context is same as vehicles in this article.

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