Level, Class, and Prospected Safety Performance of a Lightning Protection System for a Complex of Structures (LPCS)
The Standard IEC 62305 provides advanced information for the design of lightning protection of structures (LPS). In determining the position of the air-termination system, two methods are generally suggested: the protective angle method and the rolling sphere method. Adopting a 3-D graphical simulation, the “rolling sphere” method allows one: to analyze the protected volume at the building roof inside of the rolling ply surface; to verify the behavior of the designed air-termination system; to evaluate the contribution of the surrounding structures in limiting the lightning current flowing in the down-conductors. This current affects the probability of dangerous sparking and the separation distance for the protection of internal installations. This paper presents this approach by a case study of a building in a complex of structures: it highlights particularly the worst cases of the lightning impact related to the designed air-termination system.
The Modern Mathematical Equation for the Lightning protection Angle
The lightning protection angle ($\alpha $) is a method which is approved by IEC standard 62305, continuously. Essentially, it can be utilized to determine the protective angle for the tall object above a ground level, for instance, a building, cultural heritage and so on. During in the past decade, the many literatures demonstrated the mathematical correlation of lightning protection angle, which were complicated, unclear relationship, and many constraints for implementation respectively. Nowadays, these problems are not improved. Therefore, this article is proposed a modern mathematical equation for lightning protection angle, which this equation is an easy relationship, low complexity, and correct result respectively. Moreover, the result of a modern equation is corresponding, as well as it closely matches the result of all existing techniques. Therefore, the modern equation is suitable for practical.
Numerical Simulation of Thermal Sensitivity for Explosives
In order to compare the thermal sensitivity of several typical explosives, this article solved numerically one-dimensional transient heat conduction equation including thermal decomposition for explosives with finite difference method. The explicit difference equations under different boundary conditions were established, and the corresponding stability criterion was derived. The ignition times for typical explosives were calculated, which was used to evaluate thermal sensitivity of explosives.