The main objective of this proposed article is to provide explanations to justify the validity of the results of the studies of the interaction between the electromagnetic fields and the human body. It can also find direct applications in the characterization and modeling of the macroscopic electrical properties of the biological media for assessing the effects of fields induced by electromagnetic radiation sources in the human body to set up new standards on the Human exposure to electromagnetic fields. To do this, we have taken into account the different physical phenomena of propagation of a hyper-frequency electromagnetic plane wave and on the other hand, the experimental values in order to model the electrical behavior of human biological tissues based on an equivalent electronic circuit model composed of capacities, resistance and reel, which assimilates the biological tissues of the skin, grease, blood. This model using the characteristic impedance of the dielectric support makes it possible to evaluate the voltage induced by the electromagnetic waves of the hyper-frequencies in the studied biological system. The results of the simulations obtained from computer tools demonstrate that the hyper-frequency electromagnetic waves can result in an elevation of the electrical potential of the biological tissues. Despite this potential is a decreasing function of the penetration depth.
The interactions of electromagnetic waves with the human body are complex and depend on several factors related to the characteristics of the incident wave, including its frequency, its intensity, the polarization of the tissue encountered, the geometry of the tissue and its electromagnetic properties. That's to say, the dielectric permittivity, the conductivity and the type of coupling between the field and the exposed body. A biological system irradiated by an electromagnetic wave is traversed by induced currents of non-negligible density; the water molecules present in the biological tissues exposed to the electromagnetic field will begin to oscillate at the frequency of the incident wave, thus creating internal friction responsible for the heating of the irradiated tissues. This heating will be all the more important as the tissues are rich in water. This article presents the establishment from a mathematical and numerical analysis explaining the phenomena of interaction and consequences between electromagnetic waves and health. Since the total electric field in the biological system is unknown, that is why it can be determined by the Finite Difference Time Domain FDTD method to assess the electromagnetic power distribution in the biological system under study. For this purpose, the detailed on the mechanisms of interaction of microwave electromagnetic waves with the human body have been presented. Mathematical analysis using Maxwell's equations as well as bio-heat equations is the basis of this study for a consistent result. Therefore, a thermal model of biological tissues based on an electrical analogy has been developed. By the principle of duality, an electrical model in the dielectric form of a multilayered human tissue was used in order to obtain a corresponding thermal model. This thermal model made it possible to evaluate the temperature profile of biological tissues during exposure to electromagnetic waves. The simulation results obtained from computer tools show that the temperature in the bio-How to cite this paper: Nzao, A.B.S.
How to cite this paper: Nzao, A.B.S.
The roles of electrical energy no longer need to be demonstrated since the industrial revolution of 1740 based on the use of new sources of energy, of which electrical energy is considered to be one of the greatest revolutions in the world. Despite this, we must note that electrical energy is changing the habits of human activity and, on the one hand, has consequences on its transport, the large quantities of which are transmitted by power lines, forcing them to operate more and more. more within their limits and unplanned outages increase the risk of instability. Storms, industrial pollution, and lightning strikes are the main causes of these unscheduled outages. In regions with a high keraunic level, the reduction of insulation breakdown due to lightning is, therefore, a major concern for designers and operators of HV lines. It is possible to reduce the number of tripping of power lines due to lightning by the proper installation of ground wires and by the appropriate grounding of pylons. In this article, we focus our research on the analysis of the impact of the earthing of the pylons on the performance of HV lines against lightning strikes. Considering these parameters and using the oldest and simplest analytical model as a time-varying current wave whose model is a difference of two decaying exponentials, we brought into contribution Maxwell's equations, the law of Ohm, telegrapher's equations, transmission line theory, and the FDTD method to model lightning-induced voltages as a function of HVAC tower grounding. This study was carried out on the Liminga-Funa 220 kilovolt alternating line in the DRCongo, located in a region where storm activity and industrial pollution are very high. Thus, the results obtained by simulation show that the peak voltage on the components of the HVAC line is a linear function of the impedance of the earthing of the pylon. The impedance value of the pylon earthing less than or equal to 10 Ohm dampens the atmospheric overvoltage and ensures good coordination of the insulation of the line elements in the event of a lightning strike at the top of the pylon for the first bow. But for the return arc taken in this case, the bypass of the insulator is unavoidable. The fractal dimensions of the results of our programs have been compared with those of the figures obtained experimentally.
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