Values Of Electric Field Strength Research Articles

New design of a medium voltage indoor post insulator

This paper describes the designing of a new external shape for a medium voltage indoor post insulator, which consists of an optimization polynomial. The new external shape provides lower values of electric field strength inside the insulator and in the air. Another innovation is the use of reliable components, i.e. the voltage divider. The new insulator uses a ceramic capacitor with the required capacitance, unlike previous insulators that had problems reaching the appropriate capacitance using cylindrical metal mesh. The insulator model was built with MATLAB software, followed by the calculations of electric fields in EleFAnT software. The differential evolution (DE) algorithm was used as a successful and global optimization algorithm for the optimal design of an insulator's external shape and the position of internal insulator elements.

Radiofrequency Exposures of Workers on Low-Power FM Radio Transmitters.

Low-power radio transmitters are one of the most common radio frequency sources and the exposure limit values (ELVs) for occupational exposure may be exceeded close to them. Therefore, a detailed analysis and assessment of occupational exposure in their vicinity is presented in the paper. For 20 different exposure scenarios, electric field strength and specific absorption rate (SAR) values were computed to determine whether the action levels (ALs) and ELVs of the European directive 2013/35/EU are exceeded for different 500 W radio transmitters. The results show that the ALs are very conservative for such exposure situations. Even when the ALs are greatly exceeded, the SAR values are not necessarily above the limit. However, in some situations, the ELVs were also exceeded. The local 10 g averaged value of the SAR can be exceeded if the worker is grounded (in direct contact with the steel structure), while the whole body ELVs can be exceeded for exposures at distances of <1 m from the transmitting dipole array antennas.

MOBILE PHONES ELECTROMAGNETIC FIELD RADIATION RESEARCH AND ANALYSIS OF ITS DISPERSION BY APPLYING MATLAB7 SOFTWARE

The propagation of electromagnetic radiation was investigated at different points, and the theory of covariance was applied to identify the main parameters by recording the max, mean and min values of density. The biggest electric field strength values are emitted by the second generation (2G) GSM mobile phones that operate in the frequency band of 900 MHz. The smaller electric field strength values are determined by the higher frequency (1800 MHz) used by mobile phones and smaller maximum power, the maximum of which reaches up to 1 W. Third generation (3G) UMTS smart phones that operate in the frequency band of 2100 MHz, emit smallest electric field strength values during the conversation. The values of digital arrays of measurement of the electromagnetic field energy flux density of interrelated covariance functions and digital arrays of individual covariance functions were identified. Data concerning interrelated covariances and auto-covariances of electromagnetic field energy flux density in a time scale are presented by means of the Matlab 7 software package.

Machine Learning for Bioelectromagnetics: Prediction Model using Data of Weak Radiofrequency Radiation Effect on Plants

Plant sensitivity and its bio-effects on non-thermal weak radio-frequency electromagnetic fields (RF-EMF) identifying key parameters that affect plant sensitivity that can change/unchange by using big data analytics and machine learning concepts are quite significant. Despite its benefits, there is no single study that adequately covers machine learning concept in Bioelectromagnetics domain yet. This study aims to demonstrate the usefulness of Machine Learning algorithms for predicting the possible damages of electromagnetic radiations from mobile phones and base station on plants and consequently, develops a prediction model of plant sensitivity to RF-EMF. We used rawdata of plant exposure from our previous review study (extracted data from 45 peer-reviewed scientific publications published between 1996-2016 with 169 experimental case studies carried out in the scientific literature) that predicts the potential effects of RF-EMF on plants. We also used values of six different attributes or parameters for this study: frequency, specific absorption rate (SAR), power flux density, electric field strength, exposure time and plant type (species). The results demonstrated that the adaptation of machine learning algorithms (classification and clustering) to predict 1) what conditions will RF-EMF exposure to a plant of a given species may not produce an effect; 2) what frequency and electric field strength values are safer; and 3) which plant species are affected by RF-EMF. Moreover, this paper also illustrates the development of optimal attribute selection protocol to identify key parameters that are highly significant when designing the in-vitro practical standardized experimental protocols. Our analysis also illustrates that Random Forest classification algorithm outperforms with highest classification accuracy by 95.26% (0.084 error) with only 4% of fluctuation among algorithm measured. The results clearly show that using K-Means clustering algorithm, demonstrated that the Pea, Mungbean and Duckweeds plants are more sensitive to RF-EMF (p <= 0.0001). The sample size of reported 169 experimental case studies, perhaps low significant in a statistical sense, nonetheless, this analysis still provides useful insight of exploiting Machine Learning in Bioelectromagnetics domain. As a direct outcome of this research, more efficient RF-EMF exposure prediction tools can be developed to improve the quality of epidemiological studies and the long-term experiments using whole organisms.

Investigation of the Electric Field of Metallic Fence under a High Voltage Transmission Line

There could be areas near a high voltage power transmission lines where electric field strength can exceed maximum permissible values and could be harmful to workers. Territory of the open switch–gear with a metallic fence can be dangerous especially because the power line wires there are at a relatively low height. Therefore, it is important to know surely what the values of electric field strength are near a fence. The expressions for calculation of electric field strength at any observation point near the three-phase line with near the line set metallic fence dependently on the geometrical parameters of line and fence and the coordinates of observation point are presented in the paper. 2D approach is applied to implement the task. Values of electric field strength, obtained applying the analytical method, were compared with the numerically calculated ones. The comparison showed that difference between results obtained by analytical calculations and results obtained by numerical modelling is not greater than 10%. The results show that there is some area near the fence in which the electric field strength exceeds permissible values.DOI: http://dx.doi.org/10.5755/j01.eie.22.6.17218

Electric Field Driven Addressing of Oil-in-Water Droplets in the Presence of Gradients of Ionic and Nonionic Surfactants

We deal with controlled transport (addressing) of dielectric kerosene droplets dispersed on water surface by dc electric field in the presence of surfactants. Experimental planar microfluidic platform with a central chamber and two electrode compartments enables formation of concentration gradients of cationic, anionic, or nonionic surfactants. We show that a kerosene droplet always moves away from the surfactant reservoir due to the Marangoni phenomenon. The release of ionic surfactants can be well controlled by imposed electric field. Once surfactant molecules reach the surface of the water phase, the Marangoni phenomenon pulls the kerosene droplet in the direction from the surfactant reservoir. Thus, the observed mechanism does not rely on the classical electrophoretic migration of charged macroscopic objects-droplets. As the dependence of droplet motion on the absolute value of electric field strength is linear, apparent droplet mobilities are evaluated. Finally, we discuss the use of the observed phenomenon for droplet addressing in fluidic systems.

Investigating an alternative ring design of transducer arrays for tumor treating fields (TTFields).

Tumor treating fields (TTFields) is a therapy that inhibits cell proliferation and has been approved by the U.S Food and Drug Administration (FDA) for the treatment of Glioblastoma Multiforme. This anti-mitotic technique works non-invasively and regionally, and is associated with less toxicity and a better quality of life. Currently a device called Optune™ is clinically used which works with two perpendicular and alternating array pairs each consisting of 3×3 transducers. The aim of this study is to investigate a theoretical alternative array design which consists of two rings of 16 transducers and thus permits various field directions. A realistic human head model with isotropic tissues was used to simulate the electric field distribution induced by the two types of array layouts. One virtual tumour was modelled as a sphere in the white matter close to one lateral ventricle. Four alternative ring design directions were evaluated by activating arrays of 2×2 transducers on opposite sides of the head. The same amount of current was passed through active transducer arrays of the Optune system and the ring design. The electric field distribution in the brain differs for the various array configurations, with higher fields between activated transducer pairs and lower values in distant areas. Nonetheless, the average electric field strength values in the tumour are comparable for the various configurations. Values between 1.00 and 1.91 V/cm were recorded, which are above the threshold for effective treatment. Increasing the amount of field directions could possibly also increase treatment efficacy, because TTFields' effect on cancer cells is highest when the randomly distributed cell division axis is aligned with the field. The results further predict that slightly changing transducer positions only has a minor effect on the electric field. Thus patients might have some freedom to adjust array positions without major concern for treatment efficacy.

Enhanced energy-storage performance of 0.94NBT-0.06BT thin films induced by a Pb0.8La0.1Ca0.1Ti0.975O3 seed layer

0.94(Na0.5Bi0.5TiO3)-0.06BaTiO3 ferroelectric thin films with and without the Pb0.8La0.1Ca0.1Ti0.975O3 seed layer were deposited on platinum-buffered silicon substrates by using Sol–Gel process. The influence of Pb0.8La0.1Ca0.1Ti0.975O3 seed layer and annealing temperatures on the microstructures, ferroelectric properties and energy-storage performances of the as-prepared films were investigated in details. The low annealing temperature and Pb0.8La0.1Ca0.1Ti0.975O3 seed layer could improve the values of electric break-down field strength and Pmax-Pr, which play a vital role for high recoverable energy-storage density. Owing to the high electric break-down field strength value of 3310kV/cm, a large recoverable energy density of W=17.2J/cm3 and a high energy efficiency of η=74.3% were obtained for the 0.94(Na0.5Bi0.5TiO3)-0.06BaTiO3 thin film with the Pb0.8La0.1Ca0.1Ti0.975O3 seed layer, which was annealed at 450°C.

Frequency-Selective Evaluation of Personal Exposure to Electromagnetic Fields of Wireless Communications and Broadcast Transmitters

We performed a frequency-selective measurement campaign using personal exposure meters with a three-axis E-field probe to assess the electric field strength and power density of wireless communication systems and broadcast transmitters in Kosovo. Mean exposure levels were compared among different microenvironments--outdoor urban, living room, office and bedroom microenvironments--in different geographical locations and different exposure time periods. Furthermore, typical exposure levels in European countries and Kosovo were compared. Measurement post-processing results show that the highest values of the mean power density in an outdoor urban microenvironment were 0.173 mW/m2 for Wi-Fi 5G, 0.137 mW/m2 for GSM 900 uplink, 0.128 mW/m2 for GSM 1800 uplink and 0.112 mW/m2 for Wi-Fi 2G. The maximal recorded value of the total electric field strength was 10.44 V/m. The highest exposure levels per frequency band in the living room were 0.042 mW/m2 for FM, 0.023 mW/m2 for GSM 900 uplink and 0.023 mW/m2 for GSM 900 downlink and Wi-Fi 2G. In office environments, the mean power density for 14 predefined frequency bands in the range 88---5850 MHz was 0.227 mW/m2 in total. The highest total electric field strength for office microenvironments was 5.439 V/m. Residential homes were mainly dominated by the GSM bands (GSM 900 downlink, 54 %; GSM 1800 downlink, 36 %). For the frequency bands FM, TETRA and TV4&5, the exposure was much higher on upper residential floors.

Non-neutral plasma diode in the presence of a transverse magnetic field

An analytical study of the plasma states in non-neutral plasma diodes in the presence of an external transverse magnetic field is presented for an arbitrary neutralization parameter γ. Considerations are restricted to the regime where no electrons are turned around by the magnetic field. The emitter electric field strength E0 is used as a characteristic function to investigate the existence of solutions depending on the diode length, the applied voltage, the neutralization parameter, and the magnetic field strength. The potential distribution has a wave form for small magnitudes of the external magnetic field, as well as for the case when magnetic field is absent. A new family of solutions appears along with the Bursian ones. On the other hand, as the Larmor radius becomes comparable with the beam Debye length, oscillations in the potential disappear, and only the Bursian branches remain. Unlike the vacuum diode, there are steady state solutions for the negative values of the emitter field strength. As the neutralization parameter (γ) increases, the emitter field strength relating to the SCL (space charge limit) bifurcation point diminishes, and at γ &amp;gt; 1, the value of the emitter's electric field strength at the space charge limit (E0,SCL) turns out to be negative.

Prediction study on positive DC corona onset voltage of rod‐plane air gaps and its application to the design of valve hall fittings

Corona inception can be viewed as the release of capacitive energy stored in the electric field. A new prediction method of the corona onset voltage based on electric field features and support vector machine (SVM) is proposed in this study. This method was used to predict the positive DC corona onset voltage of the rod-plane air gap. The predicted results were compared with the experimental values and the calculated values of the existing methods. Then, the corona onset voltage of the shielding sphere used in a valve hall of ±660 kV DC converter station was measured and predicted by the SVM model and the photoionisation model. The safe values of corona inception electric field strength were obtained. By comparing the finite element numerical calculation results of the electric field strength with the safe value, it was proved that the corona would not incept on the surface of the shielding sphere under operating voltage. This method provides a new possible way to predict corona onset voltages of valve hall fittings used in HVDC transmission projects.

Pressure-dependent mobility of negative ions in mixtures of H2O with Ar

The mobility of negative ions in H2O–Ar mixtures has been measured with a pulsed Townsend technique. It has been found that for a fixed value of the density-normalized electric field strength, E/N, the mobility of the H2O anions is strongly pressure dependent. We have also found that even for a single, total gas mixture pressure, even though at first sight the mobility of the anions seems to follow Blanc’s relation closely, a closer view indicates that the mobilities tend to shift to higher values as the water vapour concentration decreases. In spite of the lack of mass spectrometry to assess the mass and abundance of the drifting anions under specific conditions of E/N, water vapour concentration and gas pressure, the present measurements are strongly indicative of a complex ion transport and ion-molecule reaction scheme of daughter H2O anions in the H2O–Ar mixture.

Narrowband frequency-selective up-link and down-link evaluation of daily personal-exposure induced by wireless operating networks

The aim of the study is to present a frequency-selective evaluation of personal exposure induced by wireless operating networks in typical daily environments, derived by analysis of 1,905,162 samples of electric field strength, taken at a 5-s sampling interval. Measurements were collected with calibrated isotropic three-axial electric field probe personal exposure meters operating in the frequency range 88---5850 MHz. `' To estimate the electric field distribution below the measurement equipment detection limit, the robust regression on order statistics method was applied, enabling determination of mean values of electric field strength per wireless technology for: home, office, transport, outdoor, and leisure environments. The highest value of total electric field strength exposure is obtained on public transport (buses) followed by coffee shops and outdoor environments, whereas the lowest values are captured in home and office environments. Most of the mean values of the electric field were less than 0.06 V/m. Furthermore, the analyses between the contribution of uplink and downlink exposures for operating wireless cellular networks are given, including a comparison of uplink and downlink electric field levels from other countries. Readings of the 24-h personal-exposure pattern, reveal the GSM + UMTS downlink and Wi-Fi as dominant exposure contributors. The results of this study show that spatial and temporal exposure levels in Kosovo are comparable to those reported for other European countries and far below the international safety guidelines and exposure limits.

Vplyv sta¬tychnoho elektrychnoho polya na histerezys svitloindukovanoho perekhodu Frederiksa v nematychniy komirtsi

The influence of an external dc electric field on the hysteresis of the light-induced Fr´eedericksz transition in a nematic liquid crystal cell in the field of a light beam with a finite diameter has been studied. The external electric field orientations perpendicular to the cell surface and along it, in the direction of the incident light polarization, are considered. The dependences of the Fr´eedericksz transition thresholds for the increasing and decreasing intensities of the incident light on the electric field strength and the transversal light beam size are obtained numerically. The values of transversal light beam size and electric field strength, for which the Fr´eedericksz transition has a hysteretic character, are found. The hysteresis loop width is shown to increase if the dc electric field perpendicular to the cell surface grows. At the same time, the hysteresis loop width decreases, if the electric field is oriented along the cell surface.

Modelling and assessment of the electric field strength caused by mobile phone to the human head.

Electromagnetic field exposure is the one of the most important physical agents that actively affects live organisms and environment. Active use of mobile phones influences the increase of electromagnetic field radiation. The aim of the study was to measure and assess the electric field strength caused by mobile phones to the human head. In this paper the software "COMSOL Multiphysics" was used to establish the electric field strength created by mobile phones around the head. The second generation (2G) Global System for Mobile (GSM) phones that operate in the frequency band of 900 MHz and reach the power of 2 W have a stronger electric field than (2G) GSM mobile phones that operate in the higher frequency band of 1,800 MHz and reach the power up to 1 W during conversation. The third generation of (3G) UMTS smart phones that effectively use high (2,100 MHz) radio frequency band emit the smallest electric field strength values during conversation. The highest electric field strength created by mobile phones is around the ear, i.e. the mobile phone location. The strength of mobile phone electric field on the phantom head decreases exponentially while moving sidewards from the center of the effect zone (the ear), and constitutes 1-12% of the artificial head's surface. The highest electric field strength values of mobile phones are associated with their higher power, bigger specific energy absorption rate (SAR) and lower frequency of mobile phone. The stronger electric field emitted by the more powerful mobile phones takes a higher percentage of the head surface. The highest electric field strength created by mobile phones is distributed over the user's ear.

Influence of lateral electric field on intraband optical absorption in concentric double quantum rings

The influence of lateral electric field on one-electron states and intraband absorption in two-dimensional concentric double quantum rings is investigated. The confining potential of the rings is modeled as a double harmonic central potential. Using the exact diagonalization technique, we calculate the dependence of the electron energy spectrum as a function of the electric field strength as well as the inner ring radius. Also, different values of confinement strength are considered. Selection rule is obtained for intraband transitions, caused by the direction of incident light polarization. The intraband absorption coefficient is calculated for different values of electric field strength, inner ring radius, confinement strength and incident light polarization direction. The combined influence of electric field strength and change of confining strength show that while the increment of the first one leads only to blueshift of absorption spectrum, the augment of the second one makes the redshift. In addition, both blueshift and redshift of the spectrum have been obtained with the enlargement of inner ring radius. Finally, we show that the absorption spectrum undergoes redshift by changing the polarization of incident light from x- to y-axis.

Statistical analysis of one Chinese sun-synchronous satellite anomalies

Based on the data from the Medium-Energy Proton and Electron Detector (MEPED) onboard NOAA-17, 141 anomalies of a Chinese Sun-Synchronous satellite (SSO-X) that occurred between 02/01/2010 and 09/31/2012 were studied statistically. About 26 out of the 52 anomalies that occurred outside the South Atlantic Anomaly (SAA) were accompanied by energetic electron storms. Superposed Epoch Analysis (SEA) was used to analyze the properties of the anomalies and the dynamics of the space environments during these 26 events. Then, a Monte Carlo method was utilized to simulate the electron deposition and the interactions of the injected electrons with an aluminum shield and polyethylene dielectric. The average, median, and 75th percentile values of the maximum electric field strength inside the dielectric were calculated. The results showed the following. (1) SSO-X anomalies are more likely to occur within the SAA, as 89 out of 141 anomalies (63%) occurred there. (2) Twenty-six of the anomalies that occurred outside the SAA during energetic electron storms were located near the outer boundaries of the outer radiation belts, and these were more frequent in the Southern Hemisphere than in the Northern Hemisphere. (3) Electron flux enhancements occurred around the failure time at all energy levels but were more profound in the lower energy channels. The maximum fluxes of electrons >30 keV, >100 keV, and >300 keV were 106, 3.5×105, and 1.2×106 cm-2 s-1 sr-1, respectively. (4) The average, median, and 75th percentile values of the maximum electric field strengths inside the dielectric for the aforementioned 26 events remained in the range from 106 to 107 V/m for long time periods, which suggests that the ‘potential hazards’ of internal discharges cause SSO-X anomalies. The above results can provide useful information for the design and protection of sun-synchronous spacecraft.

Statistical analysis of electromagnetic radiation measurements in the vicinity of GSM/UMTS base station installed on buildings in Serbia.

As a result of dense deployment of public mobile base stations, additional electromagnetic (EM) radiation occurs in the modern human environment. At the same time, public concern about the exposure to EM radiation emitted by such sources has increased. In order to determine the level of radio frequency radiation generated by base stations, extensive EM field strength measurements were carried out for 664 base station locations, from which 276 locations refer to the case of base stations with antenna system installed on buildings. Having in mind the large percentage (42 %) of locations with installations on buildings, as well as the inevitable presence of people in their vicinity, a detailed analysis of this location category was performed. Measurement results showed that the maximum recorded value of total electric field strength has exceeded International Commission on Non-Ionizing Radiation Protection general public exposure reference levels at 2.5 % of locations and Serbian national reference levels at 15.6 % of locations. It should be emphasised that the values exceeding the reference levels were observed only outdoor, while in indoor total electric field strength in no case exceeded the defined reference levels.

Students Exposure to Radio Frequency Electromagnetic Fields in Marmara University

In recent years, there has been increasing public concern about the health implication of electromagnetic (EM) wave exposures due to the electronic sources. For this reason, various public organizations in the world have been established safety guidelines. This paper focused on the investigation of Marmara University students’ health effects that cause by the radio frequency (RF) sources. For the purpose of the assessment, electric field strength values are measured at 44 different location points of Marmara University in Goztepe Campus. In addition to the spot measurements, 24 hours measurement is also done to analyze the variation of electric field strength values. The results show that the measured electric field strength values are below the recommended international standard limits.

Simulation of the electric field strength in the vicinity of metallization edges on dielectric substrates

High electric field strengths at the edge of the metallization of insulated gate bipolar transistor (IGBT) power modules are, besides defects in the substrate or the potting gel, the main reason for partial discharge. These critical electric field strengths occur at the energized contact where it is bordered by the insulating ceramic and the cover (mostly silicone gel). The reduction of high electric field strengths for increasing the threshold voltage for partial discharge has been studied in several publications based on experiments as well as on simulations. Simulations allow the localization of the critical spots and the quantification of the maximum electric field strength. However, a systematic study of the singularities of the electric field strength at the sharp edges is lacking. Such singularities are investigated in this article. The calculation of an absolute electric field strength value is only possible for finite edge radii. For sharp edges, however, the maximum electric field strength returned by simulation depends on the grid size: Through the finite grid size a virtual edge radius is induced that suppresses the singularity at the edge. To get around this problem, a mesh-independent evaluation procedure is introduced. With this procedure it is possible to quantitatively evaluate the electric field strength in the vicinity of the sharp edge. As an example, the influence of the offset between the top and bottom metallization layer on the maximum electric field strength is studied. Moreover, the influence of the thickness of the involved layers and of the shape of the electrodes is discussed. Also, the impact of the material properties of the involved dielectrics is examined. In addition to electrostatic simulations we have carried out electric transient simulations, which show that the ratio of the conductivities of the involved dielectric materials plays a major role for determining the maximum electric field strength.