Andres Peratta

Boundary Element Modeling of the Realistic Human Body Exposed to Extremely-Low-Frequency (ELF) Electric Fields: Computational and Geometrical Aspects

This paper presents the human exposure assessment to high-voltage extremely-low-frequency (ELF) fields by the three-dimensional (3-D) boundary element method (BEM). The formulation is based on a realistic, anatomically based representation of the human body. The main objective is to analyze the influence of the relative position of the arms with respect to the body on the axial distribution of current density along the body and to determine the most vulnerable regions. Numerical results along head, neck, torso, abdomen, arms, legs, and ankles are presented and discussed in the case of grounded subject standing under power-distribution lines and in the vicinity of power transformer substations

Thermal modelling of the human eye exposed to laser radiation

Nowadays, various lasers are widely used in medical surgery procedures involving the human eye. The most important issue with laser eye surgery is estimation of temperature rise in eye tissues due to absorption of high intensity laser radiation. Model of the human eye, using the finite elements method, is developed in order to study the temperature distribution in the human eye subjected to radiation by several lasers, covering the electromagnetic spectrum from ultraviolet to visible and infrared. The mathematical model is based on the space-time dependent Pennespsila bioheat transfer equation supplemented with natural boundary condition equations for cornea and sclera. The results could prove to be useful in predicting the damage to intraocular tissues due to heating by laser radiation, but alongside the thermal effects, it could be used to evaluate other interaction mechanisms, such as photoablation, plasma-induced ablation and photodisruption.

Finite element model of the human head exposed to electrostatic field generated by Video Display Units

The goal of this paper is to investigate interaction between electrostatic field of video display units (VDUs) and human head in front of it. Special attention is given to the field at the surface of the face. The finite element model for assessment of the electrostatic field, by solving Laplace equation for the electric potential, is implemented. The electrostatic field is calculated for two different faces and for two different types of the domain and then compared with results obtained by the finite difference method. The advantage of the presented numerical method is a high resolution and a higher accuracy

Electromagnetic-thermal Analysis For Human Exposure To High Frequency (hf) Radiation

The paper aims to review some electromagnetic-thermal dosimetry methods for the assessment of human exposure to high frequency (HF) electromagnetic fields. The analysis approaches are based on certain integral/differential equation formulations and related numerical solution procedures for the calculation of specific absorption rate (SAR) and related temperature increase in a tissue. Illustrative computational examples for the human eye and the human brain exposed to HF electromagnetic fields are given in the paper. Also, some numerical results for the transcranial magnetic stimulation (TMS) are presented as an example of biomedical application of electromagnetic fields. The obtained numerical results for SAR are compared against exposure limits proposed by ICNIRP (International Commission on Non Ionizing Radiation Protection).

Pregnant woman exposed to extremely low frequency electromagnetic fields

The aim of this paper is to present recent advances in modelling a three dimensional anatomic model of a pregnant woman and foetus exposed to extremely low frequency electromagnetic fields. The case scenario is focused on the exposure to high voltage power transmission lines. The paper presents the background theory, together with the BEM computational implementation and results. The latter are expressed in terms of current density, potential and electric field in the different tissues. This work is part of an ongoing research whose overall objectives are to provide accurate estimations of fields and induced currents for assessing exposure of human bodies to electro-magnetic fields.

Electrostatic field around human head in front of Video display unit: Field as a function of display - face distance

The goal of this paper is to investigate correlation between electrostatic field of video display units (VDUs) generated around human head located in front of VDU and display-face distance. The mathematical model is based on the Laplace equation for the electrostatic potential. The finite element model for the assessment of the electrostatic field is derived. The electrostatic field is calculated for different distances between display and the human head and for different sizes of display, respectively. Results were compared with results obtained by the finite difference method (FDM). The advantage of the presented numerical method is a high resolution and a higher accuracy, compared to the FDM results.

Antenna Models for Electromagnetic Compatibility Applications

In recent decades there have been a number of significant advances in EMC modeling which can be carried out within a significantly shorter time than it would be necessary for building and testing the appropriate prototype via experimental procedures. Moreover EMC simulation can predict the system behaviour for a rather wide variety of parameters including different initial and boundary conditions, excitation types, and different configuration of the system itself. EMC-computational models are often classified as

Computer Modeling of Impressed Current Cathodic Protection (ICCP) System Anodes

Computer modeling is now widely used to predict how effective cathodic protection (CP) systems are at protecting structures and maritime vessels. There are two types of CP systems based on either sacrificial anodes or impressed anodes (ICCP) or some combination of the two types. Impressed anodes are often referred to as “active” systems as they can respond to changes in the protection requirements as they are connected to some form of control system. Typically in computer models ICCP anodes are controlled by specifying the current they output in response to the potential measured at a reference electrode. In this paper an alternative approach has been investigated where the model also includes the power supply as well as the associated cables etc connecting to the anodes. This enables us to more accurately model situations where any number of anodes are connected to a single power supply, anode/reference electrode (RE) failure scenarios, non symmetric anode layouts, localized damage to coatings and situations where there are significant appendages to the vessel which change the current requirements. The paper will describe the technical approach to the modeling and present examples of modeling of a commercial FPSO vessel. (Floating, Production, Storage and Offloading vessels are used in the Oil & Gas industry typically as part of deepwater developments) The benefits of the proposed approach compared with the conventional approach will be presented and the results critically analyzed.© 2009 ASME

Induced currents in the human body resulting from the proximity to surfaces at fixed potentials

The paper evaluates the currents induced in the human body when exposed to extremely low frequency (60 Hz) electric fields by numerical modelling with boundary elements. The exposure is driven by the voltage of a rectangular panel representing the control keyboard of a power substation room. The main focus is to study the variations of the current density along the vertical axis of the body when located at different distances from the panel. In addition, the sensitivity of the results for the current density when considering the human body with and without its internal organs is estimated. The numerical approach is based on the three dimensional boundary element method (BEM) with the kernel of Laplace equation, in which the human body model considered is a simplified representation which allows parametric modifications of its geometry and physical properties.

A 3D BEM Modelling Of Human Exposure ToExtremely Low Frequency (ELF) Electric Fields

The boundary element analysis of the human body exposed to extremely low frequency (ELF) electric fields is presented in this work. The human being is represented by a multidomain inhomogeneous body of revolution. The formulation of the problem is based on the quasi-static approximation and the related Laplace equation form of the continuity equation. This Laplace equation has been solved by the boundary element method (BEM). Solving the resulting Laplace equation for the electric scalar potential, the induced current density inside the human body is obtained. This quantity is the fundamental parameter in further analysis of possible biological effects of ELF exposures. An illustrated computational example of the human body exposed to the electric field generated by an overhead power line is also presented.