Lightning protection, earthing and surge protection of base transmission stations
An effective lightning protection design for a telecommunication facility requires an integrated approach to a number of key factors: • Protection against direct lightning strikes • Effective earth termination network for discharge of lightning current • Integration of power supply and lightning protection earthing systems • Extensive equipotential bonding to prevent electric shock • Mitigation for ground potential rise • Prevention of conducted surges to equipment cabin • Mitigation of LEMP This paper examines the challenges and solutions in the integration of lightning protection, earthing and surge protection for a base transmission station comprising a telecom tower and an equipment cabin, taking into consideration external power source via overhead lines.
Estimation of Actual Earth Resistance in Complex Earthing Networks: A Case Study for Telecom Towers
In this paper, we address the problem of estimating the actual earth resistance of a complex earthing system. Specifically, we model the earthing network using ANSYS Electromagnetics in the finite element domain. Then, we compare the theoretical and simulated results to estimate the earth resistance by analyzing the relationship between them. Finally, we validate the effectiveness of the proposed method using simulation and experimental results.
The infection process, sporulation and survival of Alternaria helianthi on sunflower
SUMMARY 
 
Electron microscopy was used to study the infection of sunflower leaves by Alternaria helianthi. Conidia germinated by producing one to many germ tubes which grew across the leaf surface before forming appressoria. The fungus directly penetrated its host through the cuticle and epidermis. Entry into the host through wounds and stomates was also observed. Extracellular sheaths were found to be associated with germ tubes and intercellular hyphae of A. helianthi. Conidiophores developed through collapsed stomates, from leaf veins, trichomes and also from mycelium growing across the host leaf surface. Microcylic conidia were produced directly from parent conidia under certain conditions. Studies using a volumetric spore trap showed that the airborne spore concentration followed a distinct periodicity with peaks occurring between 0900 and 1100 h each day. Laboratory studies showed that safflower, noogoora burr and bathurst burr could serve as alternative hosts for A. helianthi. The pathogen was readily isolated from sunflower crop debris from a diseased crop that had been harvested 1 yr earlier.