The horse, the cowboy and the lightning modeling: A case study on a farm in the State of Minas Gerais, Brazil
Lightning provoke fear, fright and many material and personal losses in the urban environment, corroborated by the agglomeration of people and concentration of high buildings. No less terrified, however, are the inhabitants of the countryside, including the animals, in the occurrences of atmospheric discharges. This article deals with the action of lightning that victimized a horse and a cowboy, on a farm, by simulating the propagation of potentials in the soil.
Detecting and Avoiding Step Voltage Hazards
Uncontrolled flow of electrical current in the earth may have a range of effects, from barely perceptible to dangerous electrical shocks, or unintended electrical heating resulting in fires. This paper promotes awareness of hazards from ground-potential rise and briefly describes the root causes of voltage in the ground. It is proven that the values of ground potential can be above permissible limits if a voltage as small as 220 V ac is applied into the ground. The step voltage hazards depend on the distance of the fault as well as from the step length. Ground resistivity also affects ground-potential rise. A wearable device is proposed for avoiding injuries. The device warns and protects the user of the step voltage hazards.
Computer simulations and theory of oceanographic fluorescence lidar signals: effect of sea surface structure.
A 3-D computer simulation model has been developed using geometrical optics suitable for analyzing the effect of sea surface structure on oceanographic fluorescence lidar signals. Depth-resolved and depth-integrated signals reveal a considerable dependence on the surface structure. The results obtained by simulation are confirmed by a theoretical approach based on the transformation of solid angles by curved boundaries. Using statistical assumptions about the distribution of curvatures of the ocean surface, a general expression for this influence is found.