Dejan Krstić

Electric field distribution and SAR in human head from mobile phones

This paper presents the distribution of electric field inside a human head as well as around the electromagnetic field source, i.e. the mobile phone. Specific Absorption Rate (SAR), which is obtained inside a human head and the thermal effect due to exposure to electric field from mobile phone was presented. For this research two different models of human head have been used. In the first case electromagnetic parameters of biological tissues of human head were modeled with a volumetric interpolation function that estimates the characteristics of a given tissue inside the human head while in the second case model with layers was used. The layers represent human head parts (skin, fat tissue, muscles, the skull, and the brain). The parts of the human head are based on their electromagnetic properties (conductivity, electric permittivity, and magnetic permeability). In order to obtain the electric field distribution for different cross-sections, the numerical calculation based on the Finite Integration Technique (FIT) and Finite Element Method (FEM) was performed.

Predicting the Biological Effects of Mobile Phone Radiation Absorbed Energy Linked to the MRI-obtained Structure

The nature of an electromagnetic field is not the same outside and inside a biological subject. Numerical bioelectromagnetic simulation methods for penetrating electromagnetic fields facilitate the calculation of field components in biological entities. Calculating energy absorbed from known sources, such as mobile phones when placed near the head, is a prerequisite for studying the biological influence of an electromagnetic field. Such research requires approximate anatomical models which are used to calculate the field components and absorbed energy. In order to explore the biological effects in organs and tissues, it is necessary to establish a relationship between an analogous anatomical model and the real structure. We propose a new approach in exploring biological effects through combining two different techniques: 1) numerical electromagnetic simulation, which is used to calculate the field components in a similar anatomical model and 2) Magnetic Resonance Imaging (MRI), which is used to accurately locate sites with increased absorption. By overlapping images obtained by both methods, we can precisely locate the spots with maximum absorption effects. This way, we can detect the site where the most pronounced biological effects are to be expected. This novel approach successfully overcomes the standard limitations of working with analogous anatomical models.

Effect of silicon-rich water intake on the systemic and peritoneal inflammation of rats with chronic low levels of aluminum ingestion

BACKGROUND AND OBJECTIVES Study evaluated effect of silicon-rich water intake on systemic inflammation and functional characteristics of peritoneal macrophages (PMs) of rats that were chronically exposed to dietary aluminum. METHODS One month-old female Wistar Albino rats were administered aluminum chloride dissolved in distilled water (1.6mg/kg body weight in 0.5mL) by gavage for 90days. The rats were then given standard (6mg/L) or silicon-rich water (19mg/L silicon) (n=7/group). Control rats underwent sham gavage and received standard or silicon-rich water (n=7/group). Blood was assessed for cytokine levels. Unstimulated and lipopolysaccharide (LPS)-stimulated PMs were assessed in terms of phagocytic activity and cytokine secretion in vitro. RESULTS Chronic exposition to dietary aluminum and silicon-rich drinking water did not change serum TNF-α levels. Aluminum increased serum IL-2 and this was reversed by silicon-rich water. The aluminum-exposed rats had higher serum sICAM-1 than sham-gavaged, unrelated to type of water. LPS-stimulated PMs from aluminum-intoxicated animals exhibited low phagocytic activity and release of TNF-α, this was significantly improved by silicon-rich water intake. In the presence of silicon-rich water, LPS-stimulated and unstimulated PMs from aluminum-exposed rats produced significantly more IL-10. CONCLUSIONS Chronic ingestion of aluminum, increases systemic and peritoneal inflammation and PM dysfunction. The presence of high levels of the natural aluminum antagonist silicon in the drinking water restored IL-10 and TNF-α PM secretion, preventing prolonged inflammation. Thus, silicon intake can decrease the immunotoxicity of aluminum.

Thermal effects on human head from mobile phones

The subject of this paper is monitoring of thermal effects on human head from mobile phones. In this paper temperature distribution and SAR at surface of human head close to source of electromagnetic radiation are shown. Results of simulation were compared with experimental results obtained with thermal imaging camera.

Economics of a small-scale, grid-connected PV system in Western Romania: An LCoE analysis

PV power systems have gained much attention in the last decades due to the clean operation and potential benefits in fossil fuel and greenhouse gas sparings. An economic analysis of grid-connected, small-scale, residential PV systems is proposed, based on the levelized cost of energy is proposed. Economy in gas emission is also estimated. All calculations rely on measured radiation and energy production data in the western part of Romania. Results indicate that a coherent policy of promotion is necessary for widespreading of residential grid-connected PV systems.

Battery Pack Design Problems – Influence of the Transverse Magnetic Field on Internal Battery Resistance

The battery pack represents an essential part of electric vehicles (EV), so its design significantly influences the drive characteristics. The system of energy flow control in EV use highfrequency power electronic components that cause the appearance of high harmonics super-imposed on DC component of the battery current. This paper examines the influence of the distribution of the transversal magnetic field inside of the battery pack depending on battery pack design and its influence on battery parameters. DC component of the transversal magnetic field inside of battery cells cause Hall effect ions path allocation that is reflected on internal battery resistance negative change. AC component of the transversal magnetic field in electrically closed loops within battery pack induced e.m.s. that also cause negative phenomena on battery pack parameters.

Safety rules for use in electric vehicle charging infrastructure

Development trend in automotive industry is based on development of electric vehicles (EV) and supporting infrastructure. To ensure safety of users and user friendly interfaces, complex systems of power electronics, high voltage and current levels, as well as control systems in real time have priority in research and development. This paper presents an overview of technical solutions and standard procedures related to systems infrastructure for EV power charging, protocols for connections and security systems.

Green Function of the Point Source Inside/Outside Spherical Domain - Approximate Solution

A brief review of derivation of two groups of approximate closed form expressions for the electrical scalar potential (ESP) Green functions that originates from the current of the point ground electrode (PGE) in the presence of a spherical ground inhomogeneity are presented in this paper. The PGE is fed by a very low frequency periodic current through a thin isolated conductor. One of approximate solutions is proposed in this paper. Known exact solutions that have parts in a form of infinite series sums are also given in this paper. In this paper, the exact solution is solely reorganized in order to facilitate comparison to the closed form solutions, and to estimate the error introduced by the approximate solutions. Finally, error estimation is performed comparing the results for the electrical scalar potential obtained applying the approximate expressions and the accurate calculations. This is illustrated by a number of numerical experiments.

The grounding system of the pillar on the road

The lightning pillars on the highway need to be grounded in accordance with the corresponding standards. A procedure for characterization of the grounding systems placed inside the road is presented in the paper. The road is treated as a ground inhomogeneity. Using the estimation method, the road is approximated by a domain having semi-circular cross-section. The analysis includes application of the quasi-stationary image theory and the Greens function for the point source placed inside the cylinder of the semi-circular cross-section. Leakage current distributions are obtained applying the Method of Moments. Afterwards, the grounding system characteristics are determined.