Electromagnetic Field Emissions Research Articles

Design and Analysis of Double-Layer Electromagnetic Field Limiter for Wireless Rechargeable Medical Implants

Human exposure to the electromagnetic field (EMF) has been raising concerns with the fast development of the wireless power transfer (WPT) technology. This article proposes a double-layer coil structure for wireless rechargeable implanted medical equipment, which can effectively strain the power beam into a single direction and limit the EMF emission to other parts of the human body. The system is designed and analyzed based on both the finite-element method (FEM) simulation and practical tests. A prototype of the proposed double-layer receiver with 56 mm diameters has successfully captured 6.84 W power and the EMF emission strength has been effectively reduced by over 20% at the concerning parts of the human body during WPT. The design scheme has been analyzed based on practical considerations and can be embedded into other similar medical implant applications.

Anthropogenic electromagnetic fields (EMF) influence the behaviour of bottom-dwelling marine species

Many marine animals have evolved sensory abilities to use electric and magnetic cues in essential aspects of life history, such as to detect prey, predators and mates as well as to orientate and migrate. Potential disruption of vital cues by human activities must be understood in order to mitigate potential negative influences. Cable deployments in coastal waters are increasing worldwide, in capacity and number, owing to growing demands for electrical power and telecommunications. Increasingly, the local electromagnetic environment used by electro- and magneto-sensitive species will be altered. We quantified biologically relevant behavioural responses of the presumed, magneto-receptive American lobster and the electro-sensitive Little skate to electromagnetic field (EMF) emissions of a subsea high voltage direct current (HVDC) transmission cable for domestic electricity supply. We demonstrate a striking increase in exploratory/foraging behaviour in skates in response to EMF and a more subtle exploratory response in lobsters. In addition, by directly measuring both the magnetic and electric field components of the EMF emitted by HVDC cables we found that there were DC and unexpectedly AC components. Modelling, restricted to the DC component, showed good agreement with measured results. Our cross-disciplinary study highlights the need to integrate an understanding of the natural and anthropogenic EMF environment together with the responses of sensitive animals when planning future cable deployments and predicting their environmental effects.

Design of DD Coil With High Misalignment Tolerance and Low EMF Emissions for Wireless Electric Vehicle Charging Systems

In this article, a design method of the double-D (DD) coil aiming at high misalignment tolerance is proposed, and the electromagnetic field (EMF) shielding of the system is considered. Inspired by the DD coil recommended in the standard J2954 published by the Society of Automotive Engineers, the novel structures of the transmitting (Tx) coil and the receiving (Rx) coil are designed, respectively. First, the standard DD coil is introduced as a reference. Second, for the Tx coil, the parameters, such as length, width, and coverage, are investigated in detail. For the Rx coil, the coil structure overlapped in the edge is optimized. The purpose is to obtain a higher coupling coefficient at the maximum offset. Third, considering EMF emissions exceeding the limit, the structure of the central-depressed coil with E-shaped cores is proposed in the Tx coil. The EMF emissions can be reduced to less than 27 μ T at the rated output power. Finally, a 6.6–kW experimental system of which the maximum transmission efficiency is higher than 94% is set up. The experimental results prove that the proposed structure is beneficial to maintain a higher coupling coefficient against misalignment and suppress EMF emissions.

Modeling and Design of Passive Shield to Limit EMF Emission and to Minimize Shield Loss in Unipolar Wireless Charging System for EV

In this paper, a detailed lumped model of the shield is developed, and an optimization method is proposed to minimize the shield loss while suppressing the emission within the standard limit. The electromagnetic emission in a wireless charging system (WCS) is a serious concern for health and safety, especially for medium- and high-power applications, where strong magnetic field propagates through a large air gap. Usually, a flat aluminum plate is used as a shield to suppress the emission outside the charging area. This field emission increases proportionally with the coil ampere turn; therefore, a much higher shield current is required to suppress the additional emission under the limit set by the International Commission on Non-Ionizing Radiation Protection. In this paper, a novel hybrid shield structure is proposed to limit the electromagnetic field (EMF) emission, as well as to minimize the shield loss. The proposed shielding is evaluated on a laboratory prototype of 7-kW WCS designed for electric vehicle application. The experimental result shows that, while suppressing the EMF under the limit, the shield loss has been reduced by 21% compared to the commonly used aluminum shield.

A health and safety model for occupational exposure to radiofrequency fields and static magnetic fields from 1.5 and 3 T MRI scanners

The exposure of MRI staff to SMFs and RF fields in the MRI units happen as a result of their induced movement in the MRI room during patients’ examination. Exposure to SMFs among health care workers has been associated with vertigo, nausea, increased heart rate, hypothermia and metallic taste in the mouth. The only known adverse effects associated with RF fields’ exposure include induced tissue heating, and the scientific arguments regarding non-thermal effects are inconclusive. The emission of MRI-related electromagnetic fields and exposure of workers to RF energy and SMFs can be reduced through implementation of reasonably practicable control measures. This study attempts to recommend the hierarchy of controls that can be implemented in the MRI units to reduce emissions and exposure of MRI staff to RF energy and SMFs. The controls are recommended based on exposure assessment conducted to quantify the exposure levels and self-reported priori-related and unrelated health consequences. In the MRI units, elimination is an impractical measure, hence, the implementation of engineering and administrative control measures as well as the utilisation of personal protective equipment (PPE) are recommended to mitigate exposure. Engineering controls include modification of MRI scanners to reduce emissions while administration controls include the design of work schedules and processes to be adaptive by MRI staff. PPE is recommended as a last resort and include protective equipment that are fit to reduce exposure arriving to workers. In South Africa, there is no legislation to assist in enforcing exposure limits and as a result, exposure levels are not monitored. The model of this kind could assist in reducing exposure levels in the MRI units and substantially reduce exposure-related effects amongst workers.

A 50-kW Three-Phase Wireless Power Transfer System Using Bipolar Windings and Series Resonant Networks for Rotating Magnetic Fields

The mass and volume of wireless power transfer (WPT) systems for charging electric vehicles are directly related to the rated power of the system. The difficulties of high-power wireless charging are exacerbated by the need to meet the same practical constraints associated with vehicle integration as lower power systems. Therefore, more advanced techniques are necessary to improve power density and specific power of wireless charging systems for high-power applications. This article presents theory and analysis of three-phase inductive WPT systems with bipolar phase windings. Magnetic coupler topologies and the theoretical and practical aspects of series three-phase resonant compensation networks are discussed. The systems under consideration are designed to utilize rotating magnetic fields to achieve a power transfer characteristic that is temporally smoother than single-phase systems. Other benefits associated with rotating magnetic field based WPT, including reduced ferrite mass, filter component requirements, and electromagnetic field emissions, are discussed. Experimental results of a prototype system are presented in both aligned and misaligned configurations. The system is demonstrated transferring 50 kW with 95% dc-to-dc efficiency over a 150-mm airgap in the aligned case. Onaper-pad basis, the magnetic couplers achieve a power density of 195 kW/m 2 and a specific power of 3.65 kW/kg. This article is accompanied by a video of the rotating magnetic field produced by a simulated three-phase WPT system.

From self-organization in relativistic electron bunches to coherent synchrotron light: observation using a photonic time-stretch digitizer

In recent and future synchrotron radiation facilities, relativistic electron bunches with increasingly high charge density are needed for producing brilliant light at various wavelengths, from X-rays to terahertz. In such conditions, interaction of electron bunches with their own emitted electromagnetic fields leads to instabilities and spontaneous formation of complex spatial structures. Understanding these instabilities is therefore key in most electron accelerators. However, investigations suffer from the lack of non-destructive recording tools for electron bunch shapes. In storage rings, most studies thus focus on the resulting emitted radiation. Here, we present measurements of the electric field in the immediate vicinity of the electron bunch in a storage ring, over many turns. For recording the ultrafast electric field, we designed a photonic time-stretch analog-to-digital converter with terasamples/second acquisition rate. We could thus observe the predicted link between spontaneous pattern formation and giant bursts of coherent synchrotron radiation in a storage ring.

Accurate Driver Detection Exploiting Invariant Characteristics of Smartphone Sensors.

Distracted driving jeopardizes the safety of the driver and others. Numerous solutions have been proposed to prevent distracted driving, but the number of related accidents has not decreased. Such a deficiency comes from fragile system designs where drivers are detected exploiting sensory features from strictly controlled vehicle-riding actions and unreliable driving events. We propose a system called ADDICT (Accurate Driver Detection exploiting Invariant Characteristics of smarTphone sensors), which identifies the driver utilizing the inconsistency between gyroscope and magnetometer dynamics and the interplay between electromagnetic field emissions and engine startup vibrations. These features are invariantly observable regardless of smartphone positions and vehicle-riding actions. To evaluate the feasibility of ADDICT, we conducted extensive experiments with four participants and three different vehicles by varying vehicle-riding scenarios. Our evaluation results demonstrated that ADDICT identifies the driver’s smartphone with 89.1% average accuracy for all scenarios and >85% under the extreme scenario, at a marginal cost of battery consumption.

Effects of radiofrequency electromagnetic radiation (RF-EMF) on honey bee queen development and mating success

Mobile phones can be found almost everywhere across the globe, upholding a direct point-to-point connection between the device and the broadcast tower. The emission of radiofrequency electromagnetic fields (RF-EMF) puts the surrounding environment inevitably into contact with this radiation. We have therefore exposed honey bee queen larvae to the radiation of a common mobile phone device (GSM band at 900 MHz) during all stages of their pre-adult development including pupation. After 14 days of exposure, hatching of adult queens was assessed and mating success after further 11 days, respectively. Moreover, full colonies were established of five of the untreated and four of the treated queens to contrast population dynamics. We found that mobile phone radiation had significantly reduced the hatching ratio but not the mating success. If treated queens had successfully mated, colony development was not adversely affected. We provide evidence that mobile phone radiation may alter pupal development, once succeeded this point, no further impairment has manifested in adulthood. Our results are discussed against the background of long-lasting consequences for colony performance and the possible implication on periodic colony losses.

A Study on Electromagnetic Field Emission and Its Effect on Electromagnetic Environment

A Study on Electromagnetic Field Emission and Its Effect on Electromagnetic Environment

Influence of High Frequency Electromagnetic Fields Produced by Antennas for Mobile Communication on the Structure of the Pancreas in Rats: Histological and Unbiased Stereological Analysis

Abstract The emission of high frequency electromagnetic fields (HF EMF) produced by antennas for mobile communications has been controversially alleged to have adverse health effects. The aim of our work was to examine whether there are effects on living organisms from HF EMF produced by mobile communication antennas. In this experiment Wistar strain rats were exposed to HF EMF with the following characteristics: 1.9 GHz frequency, 0.24 A/m intensity, electric field strength of 4.79 V/m, and SAR (specific absorption rate) value of 2.0 W/m2. Exposure time was 7 hours per day, 5 days per week, over the course of sixty days. This experiment was conducted on a total of 30 male rats divided randomly into two equal groups: one group of animals was exposed to GSM fields (Global System of antennas for Mobile Communications) as described above whereas the other group of animals was not exposed to any GSM fields. In our study, results show that the quantity, diameter and numerical density of the islets of Langerhans in the pancreatic tissue increased in rats exposed to HF EMF compared to the unexposed group. The volume density, number and numerical density of pancreatic cells also changed in rats that were exposed to the HF EMF compared to the unexposed group. Our study shows a change in the stereological and histological parameters of rat pancreatic tissue due to the effects of HF EM fields produced by antennas for mobile communication.

Understanding the effects of electromagnetic field emissions from Marine Renewable Energy Devices (MREDs) on the commercially important edible crab, Cancer pagurus (L.)

The effects of simulated electromagnetic fields (EMF), emitted from sub-sea power cables, on the commercially important decapod, edible crab (Cancer pagurus), were assessed. Stress related parameters were measured (l-Lactate, d-Glucose, Haemocyanin and respiration rate) along with behavioural and response parameters (antennular flicking, activity level, attraction/avoidance, shelter preference and time spent resting/roaming) during 24-h periods. Exposure to EMF had no effect on Haemocyanin concentrations, respiration rate, activity level or antennular flicking rate. EMF exposure significantly disrupted haemolymph l-Lactate and d-Glucose natural circadian rhythms. Crabs showed a clear attraction to EMF exposed shelter (69%) compared to control shelter (9%) and significantly reduced their time spent roaming by 21%. Consequently, EMF emitted from Marine Renewable Energy Devices (MREDs) will likely affect edible crabs both behaviourally and physiologically, suggesting that the impact of EMF on crustaceans must be considered when planning MREDs.

Assessment of the effectiveness of a dehumidification system by emission of electromagnetic fields: Proposal of a protocol

Abstract In this paper the operation of a dehumidification system has been studied in operating conditions and a protocol for the assessment of its effectiveness is proposed. The physical principle of the used system is based on the interaction of a pulsed electromagnetic field with the masonry materials affected by rising damp phenomena. As it is well known, water has a crucial role in decay mechanisms both by a physical and by a chemical point of view. In fact, soluble salts transport phenomena, biological growth, stress due to expanding clays, freeze–thaw cycles, are among the most diffused examples of decay mechanisms. The target of any dehumidification systems, as the one under analysis, is very ambitious and crucial in the field of cultural heritage conservation; hence starts the authors need in understanding the involved physical mechanisms and in evaluating the effectiveness of these systems. Literature reports laboratory tests carried out with the target to acquire a better knowledge of the interaction mechanism between pulsed electromagnetic field and masonry materials, with and without water presence. Very often laboratory tests are followed by tests on pilot site chosen on purpose. In the example presented in the paper, ground floor masonries belonging to an historical building, with evident rising damp phenomena, was chosen. The building is located at Saltino, Reggello close to Florence, at 995 m asl. The rising of water affects at different levels several rooms of the building at ground floor, but on the north side of the house, the effects are greater. This contribute also proposes preliminary ideas to draw a standard aimed at build up a protocol for the performance assessment of dehumidification systems, based on different physical principles. A full knowledge of physical principles is mandatory to optimize the effectiveness of these systems. The procedure to assess the effectiveness of these systems must be standardized identifying the environmental parameters to be checked in relation to the ones directly measured on the masonry.

Understanding the effects of electromagnetic field emissions from Marine Renewable Energy Devices (MREDs) on the commercially important edible crab, Cancer pagurus (L.)

Abstract The effects of simulated electromagnetic fields (EMF), emitted from sub-sea power cables, on the commercially important decapod, edible crab (Cancer pagurus), were assessed. Stress related parameters were measured ( l -Lactate, d -Glucose, Haemocyanin and respiration rate) along with behavioural and response parameters (antennular flicking, activity level, attraction/avoidance, shelter preference and time spent resting/roaming) during 24-h periods. Exposure to EMF had no effect on Haemocyanin concentrations, respiration rate, activity level or antennular flicking rate. EMF exposure significantly disrupted haemolymph l -Lactate and d -Glucose natural circadian rhythms. Crabs showed a clear attraction to EMF exposed shelter (69%) compared to control shelter (9%) and significantly reduced their time spent roaming by 21%. Consequently, EMF emitted from Marine Renewable Energy Devices (MREDs) will likely affect edible crabs both behaviourally and physiologically, suggesting that the impact of EMF on crustaceans must be considered when planning MREDs.

Effect of an 1800 MHz electromagnetic field emitted during embryogenesis on the blood picture of one-day-old domestic hen chicks (Gallus gallus domesticus)

Exposure to artificial electromagnetic fields emitted mainly by mobile telephony has been steadily increasing with the development of modern technology. Haematological indices are among the most common indicators of the body’s physiological status. The aim of the study was to determine the effect of an 1800 MHz electromagnetic field emission on the blood picture of one-day-old domestic hen chicks. During the experiment, chick embryos were exposed to artificial electromagnetic fields throughout incubation for 13 ´ 2 min/day, 4 ´ 10 min/day and 1 ´ 40 min/day. After hatching, blood was collected from 10 one-day-old chicks from each group to determine: red blood cell count, haemoglobin concentration, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, white blood cell count, and leukocyte differential count. In addition, the heterophil/lymphocyte ratio was calculated. The present study is probably the first to show an increase in the red blood cell count, haemoglobin concentration, haematocrit, white blood cell count, segmented heterophils and the heterophil/lymphocyte ratio, and a decrease in lymphocyte percentage of embryos exposed to an 1800 MHz electromagnetic field. The observed changes may be indicative of the stress-inducing effect of EMF on living organisms.

Effects of EMF emissions from undersea electric cables on coral reef fish.

The objective of this study was to determine if electromagnetic field (EMF) emissions from undersea power cables impacted local marine life, with an emphasis on coral reef fish. The work was done at the South Florida Ocean Measurement Facility of Naval Surface Warfare Center in Broward County, Florida, which has a range of active undersea detection and data transmission cables. EMF emissions from a selected cable were created during non-destructive visual fish surveys on SCUBA. During surveys, the transmission of either alternating current (AC), direct current (DC), or none (OFF) was randomly initiated by the facility at a specified time. Visual surveys were conducted using standardized transect and point-count methods to acquire reef fish abundances and species richness prior to and immediately after a change in transmission frequency. The divers were also tasked to note the reaction of the reef fish to the immediate change in EMF during a power transition. In general, analysis of the data did not find statistical differences among power states and any variables. However, this may be a Type II error as there are strong indications of a potential difference of a higher abundance of reef fish at the sites when the power was off, and further study is warranted. Bioelectromagnetics. 39:35-52, 2018. © 2017 Wiley Periodicals, Inc.

Public acceptance of high-voltage power lines: The influence of information provision on undergrounding

In Switzerland, the planned transformation of the energy system creates a need for grid expansions. However, grid expansion projects often confront social acceptance issues. The public prefers high-voltage power lines (HVPLs) to be buried underground. Despite the perceived advantages of undergrounding, underground HVPLs can leave visible traces on the surface and are accompanied by electromagnetic field emissions. Given the importance of visual and health impacts on public acceptance of HVPLs, the present study investigates whether providing people with relevant information on these aspects of undergrounding influences people's perception. The results show that, after receiving this information, participants viewed underground HVPLs with lower acceptance, lower perceived benefits, higher perceived risks, and less positive feelings. Although public acceptance remained higher for underground HVPLs compared with overhead HVPLs, our study reveals that information provision reduces perceived differences between the two technologies. Furthermore, our results show that affective reactions to underground HVPLs have an indirect effect on public acceptance. We conclude that providing people with relevant information on possible drawbacks related to undergrounding is a necessary precondition for informed decision-making in the context of grid expansions.

Assessing potential impacts of energized submarine power cables on crab harvests

Offshore renewable energy facilities transmit electricity to shore through submarine power cables. Electromagnetic field emissions (EMFs) are generated from the transmission of electricity through these cables, such as the AC inter-array (between unit) and AC export (to shore) cables often used in offshore energy production. The EMF has both an electric component and a magnetic component. While sheathing can block the direct electric field, the magnetic field is not blocked. A concern raised by fishermen on the Pacific Coast of North America is that commercially important Dungeness crab (Metacarcinus magister Dana, 1852)) might not cross over an energized submarine power cable to enter a baited crab trap, thus potentially reducing their catch. The presence of operating energized cables off southern California and in Puget Sound (cables that are comparable to those within the arrays of existing offshore wind energy devices) allowed us to conduct experiments on how energized power cables might affect the harvesting of both M. magister and another commercially important crab species, Cancer productus Randall, 1839. In this study we tested the questions: 1) Is the catchability of crabs reduced if these animals must traverse an energized power cable to enter a trap and 2) if crabs preferentially do not cross an energized cable, is it the cable structure or the EMF emitted from that cable that deters crabs from crossing? In field experiments off southern California and in Puget Sound, crabs were given a choice of walking over an energized power cable to a baited trap or walking directly away from that cable to a second baited trap. Based on our research we found no evidence that the EMF emitted by energized submarine power cables influenced the catchability of these two species of commercially important crabs. In addition, there was no difference in the crabs’ responses to lightly buried versus unburied cables. We did observe that, regardless of the position of the cable, Cancer productus in southern California tended to move to the west and Metacarcinus magister tended to move to the east.

Mitigation measures of electromagnetic field exposure in the vicinity of high frequency welders.

Presented information about the welding process and equipment, focusing on the emission of electromagnetic field (EMF) with levels significant in terms of the labor safety regulations in force in Poland - the ordinances of the Minister of Family, Labour and Social Policy that came into force on June 27, 2016 and June 29, 2016 - emerged due to harmonization with European Union directive 2013/35/EU of 26 June 2013 of the European Parliament and the Council. They presented methods of determination of the EMF distribution in the welding machine surroundings and analyzed the background knowledge from the available literature. The subject of the analysis included popular high frequency welders widely used in the industry. Electromagnetic field measurements were performed in the welder operating place (in situ) during machine normal operations, using measurement methods accordant with labor safety regulations in force in Poland and according to the same guidelines, the EMF distributions and parameters having been described. They presented various scenarios of particular, real examples of excessive exposure to EMF in the dielectric welder surroundings and showed solutions, ranging from simple and costless and ending on dedicated electromagnetic shielding systems, which allowed to reduce EMF exposure in some cases of more than 80% (protection zone ranges) or eliminate dangerous zone presence. It has shown that in the dielectric welders surrounding, significant EMF strength levels may be the result of errors or omissions which often occur during development, installation, operation or modification of welding machines. It has allowed to present the measures that may significantly reduce the exposure to EMF of workers in the welder surroundings. The role of accredited laboratories in helping in such cases was underlined. Med Pr 2017;68(6):693-703.

Identification of Non-Stationary Magnetic Field Sources Using the Matching Pursuit Method

The measurements of electromagnetic field emissions, performed on board a vessel have showed that, in this specific environment, a high level of non-stationary magnetic fields (MFs) is observed. The adaptive time-frequency method can be used successfully to analyze this type of measured signal. It allows one to specify the time interval in which the individual frequency components of the signal occur. In this paper, the method of identification of non-stationary MF sources based on the matching pursuit (MP) algorithm is presented. It consists of the decomposition of an examined time-waveform into the linear expansion of chirplet atoms and the analysis of the matrix of their parameters. The main feature of the proposed method is the modification of the chirplet’s matrix in a way that atoms, whose normalized energies are lower than a certain threshold, will be rejected. On the time-frequency planes of the spectrograms, obtained separately for each remaining chirlpet, it can clearly identify the time-frequency structures appearing in the examined signal. The choice of a threshold defines the computing speed and precision of the performed analysis. The method was implemented in the virtual application and used for processing real data, obtained from measurements of time-vary MF emissions onboard a ship.