Recent decades have seen rapid advances in the field of electrical engineering, such that our environment has become a sea of electrical and magnetic signals, raising questions about the possible effects of low-freque...Recent decades have seen rapid advances in the field of electrical engineering, such that our environment has become a sea of electrical and magnetic signals, raising questions about the possible effects of low-frequency electromagnetic fields on the environment and which are capable of modifying and destroying our ecosystem. Particular interest was given in this article due to a massive influx of population living near high voltage lines. The analysis and simulation of the influence of low frequency electromagnetic fields on living beings in the vicinity of high voltage sources 132 kV and 220 kV in urban areas in DR Congo is the subject of our research with a view to estimating the level of exposure of humans to low frequency electromagnetic fields. To carry out our research, we used the classic method of analyzing the field produced near a high voltage line based on Maxwell’s image theory, the Maxwell-Gauss theorem and Maxwell-Ampère theorem to model and quantify low-frequency electromagnetic fields in the vicinity of high-voltage lines. The 2D FDTD numerical formulation was developed from telegraphers’ equations and allowed us to obtain models of current and voltage induced by electromagnetic fields on living beings below and near HV lines. The different simulations carried out on the proposed models illustrate the effects of the electrical and geometric parameters of the pylons on the distribution of the electromagnetic field in the vicinity of the HV lines. The results obtained were compared to the safety limits recommended by the standards.展开更多
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 d...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 <span>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 expe</span>rimental values <span></span><span><span><span style="font-family:;" "="">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.</span></span></span>展开更多
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 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 biological tissue is a linear function of the duration of exposure to microwave electromagnetic waves.展开更多
The actions and health effects of electromagnetic fields in the radio frequency (RF) domains, referred to as radio frequencies and HV transmission networks have been studied for several decades. Following the appearan...The actions and health effects of electromagnetic fields in the radio frequency (RF) domains, referred to as radio frequencies and HV transmission networks have been studied for several decades. Following the appearance of questions and debates within the population, the actions and potential effects of radiofrequency and HV transport networks on health, in connection with the development of new wireless technologies, are generating a certain revival of interest. Thus, the increasing exposure to electromagnetic fields and the concerns of the public have led health organizations to undertake large-scale research programs to respond to the concerns expressed. These research programs have contributed to significantly increasing the number of studies on the actions and effects of electromagnetic pollution as well as their consequences on living beings. The objective of our research is focused on the analysis, sources, and study of the biological consequences of electromagnetic pollution. To do this, we have used physical laws and theorems, in particular Maxwell-Ampère, Maxwell-Gauss, Maxwell-Faraday, and Ohm’s law, to model the interactions between electromagnetic fields and living matter. In this article we have chosen the approach based on the electrical model of human biological tissue, taking into account on the one hand the physical phenomena of the propagation of an electromagnetic microwave plane wave in the range from 0 to 300GHz and on the other hand, the experimental values to simulate the relaxations α, β and γ and the impedance of the biological tissue faced with the variation of the frequency of propagation of the electromagnetic waves to identify the biological consequences relating thereto. The results obtained in the literature show the linear dependence of bio-impedance on frequency, these observations suggest that the tissue can be physiologically stressed at high frequencies. This can cause biological consequences for humans. The 2D simulation based on the proposed model has been developed as well as the verification of the consistency of the different mathematical models, by comparing the fractal dimensions of the results of the program with those of the figures obtained experimentally.展开更多
In high voltage networks for the transport of electrical energy, lightning, a phenomenon as dangerous as it is impressive, with an easily recognizable form, can affect a power line by striking either a phase conductor...In high voltage networks for the transport of electrical energy, lightning, a phenomenon as dangerous as it is impressive, with an easily recognizable form, can affect a power line by striking either a phase conductor, a tower or a guard cable, thus causing more dangerous and constraining stresses on the lines for its proper operation. Thus, this article aims to analyze the behavior of a HV line during an atmospheric discharge and assess the spatial and temporal distribution of the lightning current wave. For this purpose, the generalities on the transmissible power in case of link without resistance and the modeling of the atmospheric surge propagation established on the basis of the theory of the lines with distributed constants implementing the wave equation known as the Alembert equation have been developed. Through this research, we are interested in the study of the space-time distribution of the lightning current wave in order to model the radiated electromagnetic field and to examine the influence of the atmospheric discharge induced overvoltage on the transportable power of a High Voltage AC Transmission line, for a good selective protection in order to illuminate the parasites. The 2D simulation based on engineering and “Transmission Line” models have been developed as well as the verification of the coherence of the different models, by comparing the fractal dimensions of the program results with those of the experimentally obtained figures.展开更多
文摘Recent decades have seen rapid advances in the field of electrical engineering, such that our environment has become a sea of electrical and magnetic signals, raising questions about the possible effects of low-frequency electromagnetic fields on the environment and which are capable of modifying and destroying our ecosystem. Particular interest was given in this article due to a massive influx of population living near high voltage lines. The analysis and simulation of the influence of low frequency electromagnetic fields on living beings in the vicinity of high voltage sources 132 kV and 220 kV in urban areas in DR Congo is the subject of our research with a view to estimating the level of exposure of humans to low frequency electromagnetic fields. To carry out our research, we used the classic method of analyzing the field produced near a high voltage line based on Maxwell’s image theory, the Maxwell-Gauss theorem and Maxwell-Ampère theorem to model and quantify low-frequency electromagnetic fields in the vicinity of high-voltage lines. The 2D FDTD numerical formulation was developed from telegraphers’ equations and allowed us to obtain models of current and voltage induced by electromagnetic fields on living beings below and near HV lines. The different simulations carried out on the proposed models illustrate the effects of the electrical and geometric parameters of the pylons on the distribution of the electromagnetic field in the vicinity of the HV lines. The results obtained were compared to the safety limits recommended by the standards.
文摘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 <span>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 expe</span>rimental values <span></span><span><span><span style="font-family:;" "="">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.</span></span></span>
文摘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 biological tissue is a linear function of the duration of exposure to microwave electromagnetic waves.
文摘The actions and health effects of electromagnetic fields in the radio frequency (RF) domains, referred to as radio frequencies and HV transmission networks have been studied for several decades. Following the appearance of questions and debates within the population, the actions and potential effects of radiofrequency and HV transport networks on health, in connection with the development of new wireless technologies, are generating a certain revival of interest. Thus, the increasing exposure to electromagnetic fields and the concerns of the public have led health organizations to undertake large-scale research programs to respond to the concerns expressed. These research programs have contributed to significantly increasing the number of studies on the actions and effects of electromagnetic pollution as well as their consequences on living beings. The objective of our research is focused on the analysis, sources, and study of the biological consequences of electromagnetic pollution. To do this, we have used physical laws and theorems, in particular Maxwell-Ampère, Maxwell-Gauss, Maxwell-Faraday, and Ohm’s law, to model the interactions between electromagnetic fields and living matter. In this article we have chosen the approach based on the electrical model of human biological tissue, taking into account on the one hand the physical phenomena of the propagation of an electromagnetic microwave plane wave in the range from 0 to 300GHz and on the other hand, the experimental values to simulate the relaxations α, β and γ and the impedance of the biological tissue faced with the variation of the frequency of propagation of the electromagnetic waves to identify the biological consequences relating thereto. The results obtained in the literature show the linear dependence of bio-impedance on frequency, these observations suggest that the tissue can be physiologically stressed at high frequencies. This can cause biological consequences for humans. The 2D simulation based on the proposed model has been developed as well as the verification of the consistency of the different mathematical models, by comparing the fractal dimensions of the results of the program with those of the figures obtained experimentally.
文摘In high voltage networks for the transport of electrical energy, lightning, a phenomenon as dangerous as it is impressive, with an easily recognizable form, can affect a power line by striking either a phase conductor, a tower or a guard cable, thus causing more dangerous and constraining stresses on the lines for its proper operation. Thus, this article aims to analyze the behavior of a HV line during an atmospheric discharge and assess the spatial and temporal distribution of the lightning current wave. For this purpose, the generalities on the transmissible power in case of link without resistance and the modeling of the atmospheric surge propagation established on the basis of the theory of the lines with distributed constants implementing the wave equation known as the Alembert equation have been developed. Through this research, we are interested in the study of the space-time distribution of the lightning current wave in order to model the radiated electromagnetic field and to examine the influence of the atmospheric discharge induced overvoltage on the transportable power of a High Voltage AC Transmission line, for a good selective protection in order to illuminate the parasites. The 2D simulation based on engineering and “Transmission Line” models have been developed as well as the verification of the coherence of the different models, by comparing the fractal dimensions of the program results with those of the experimentally obtained figures.
