Sources Of Electromagnetic Radiation Research Articles

Improper statistics of the radiation from a randomly rotating source

In a previous study [J. Opt. 19, 0905603 (2017)JOOPDB0150-536X10.1088/2040-8986/aa7cac], we revealed that the complete second-order statistics of narrowband polarized waves are characterized by 13 parameters, in contrast to the four parameters of the traditional Stokes vector description of the statistics of partially polarized light. In this study, we analyzed the second-order statistics of the field of a randomly rotating source of electromagnetic radiation and showed that it includes covariance of the right- and left-circular polarizations that are not captured by the Stokes vector formalism. We illustrate this finding using simple examples of rotating quadrupoles and dipole pairs.

TO THE EXPEDIENCY OF STUDENTS' TRAINING IN ELECTROMAGNETIC POLLUTION PROTECTION

Problem statement. Electromagnetic radiation is a combination of electric and magnetic radiation, the energy of which, when it affects a given material body, does not cause an ionisation process in it. Natural electromagnetic radiation not only guarantees the proper development of every living organism, but also affects the change of seasons and weather. Humans have disturbed the Earth's natural electromagnetic environment by including devices that emit electromagnetic energy in a wide range of frequencies. Artificial electromagnetic fields accompany us everywhere: at home, at work, on the road, and during leisure. The sanitary and hygienic state of the environment, including the electromagnetic situation in populated cities, is of great hygienic importance for ensuring proper living conditions for the population. The electromagnetic situation in cities and other settlements is created by a large number of radio and electrical equipment for economic, defence and other purposes. The purpose of the article. To conduct a systematic analysis of the impact of electromagnetic radiation from various types of electrical equipment on the environment. It is shown that electromagnetic radiation is dangerous both for the population as a whole, especially for children, and for personnel who operate powerful equipment - sources of electromagnetic radiation. Conclusion. Studies of electromagnetic radiation in the environment show that prolonged exposure to powerful electromagnetic fields can cause illness and even death. Therefore, rules for using artificial sources of electromagnetic radiation should be followed to minimise the damage to both human health and the environment. These rules are not so difficult to follow, but they are quite effective. And for labour protection and civil safety specialists, this knowledge will enable them to create safe working conditions in the workplace.

Estimating the lateral speed of a fast shock driven by a coronal mass ejection at the location of solar radio emissions

Fast coronal mass ejections (CMEs) can drive shock waves capable of accelerating electrons to high energies. These shock-accelerated electrons act as sources of electromagnetic radiation, often in the form of solar radio bursts. Recent findings suggest that radio imaging of solar radio bursts can provide a means to estimate the lateral expansion of CMEs and associated shocks in the low corona. Our aim is to estimate the expansion speed of a CME-driven shock at the locations of radio emission using 3D reconstructions of the shock wave from multiple viewpoints. In this study, we estimated the 3D location of radio emission using radio imaging from the Nançay Radioheliograph and the 3D location of a CME-driven shock. The 3D shock was reconstructed using white-light and extreme ultraviolet images of the CME from the Solar Terrestrial Relations Observatory, Solar Dynamics Observatory, and the Solar and Heliospheric Observatory. The lateral expansion speed of the CME-driven shock at the electron acceleration locations was then estimated using the approximate 3D locations of the radio emission on the surface of the shock. The radio bursts associated with the CME were found to reside at the flank of the expanding CME-driven shock. We identified two prominent radio sources at two different locations and found that the lateral speed of the shock was between $ $ and $ second $ at these locations. Such a high speed during the early stages of the eruption already indicates the presence of a fast shock in the low corona. We also found a larger ratio between the radial and lateral expansion speed compared to values obtained higher up in the corona. We estimated for the first time the 3D expansion speed of a CME-driven shock at the location of the accompanying radio emission. The high shock speed obtained is indicative of a fast acceleration during the initial stage of the eruption. This acceleration leading to lateral speeds in the range of $ second $ is most likely one of the key parameters contributing to the presence of metric radio emissions, such as type II radio bursts.

Application of neural networks to synchro-Compton blazar emission models

Context. Jets from supermassive black holes at the centers of active galaxies are the most powerful and persistent sources of electromagnetic radiation in the Universe. To infer the physical conditions in the otherwise out-of-reach regions of extragalactic jets, we usually rely on fitting their spectral energy distributions (SEDs). The calculation of radiative models for the jet’s non-thermal emission usually relies on numerical solvers of coupled partial differential equations. Aims. In this work, we use machine learning to tackle the problem of high computational complexity to significantly reduce the SED model evaluation time, which is necessary for SED fittings carried out with Bayesian inference methods. Methods. We computed the SEDs based on the synchrotron self-Compton model for blazar emission using the radiation code ATHEvA. We used them to train neural networks (NNs) to explore whether they can replace the original code, which is computationally expensive. Results. We find that a NN with gated recurrent unit neurons (GRUN) can effectively replace the ATHEvA leptonic code for this application, while it can be efficiently coupled with Markov chain Monte Carlo (MCMC) and nested sampling algorithms for fitting purposes. We demonstrate this approach through an application to simulated data sets, as well as a subsequent application to observational data. Conclusions. We present a proof-of-concept application of NNs to blazar science as the first step in a list of future applications involving hadronic processes and even larger parameter spaces. We offer this tool to the community through a public repository.

Novel Intelligent Methods for Channel Path Classification and Model Determination Based on Blind Source Signals

In this paper, the urban signal propagation characteristics based on the location of blind sources are investigated. To address the issue of blind electromagnetic radiation sources in complex urban environments, intelligent methods for propagation channel path classification, and model determination are brought forth based on field test data. The intelligent classification method distinguishes between the Line-of-Sight (LoS) path channel and a direct path, the LoS multipath channel with a direct path and other multiple paths, and the Non-Line-of-Sight (NLoS) multipath channel without a direct path from the source to the test point. The modeling aspect determines the model type to which the received signal belongs based on the statistical model derived from the tested data of a specific source. A validation measurement system was constructed for the FM broadcasting band, and validation campaigns were conducted in the city of Wuhan. The process and analysis of the data using this method demonstrate the accurate distinction of the different propagation path channels and models and involve the construction of a statistical model for the FM band in Wuhan’s urban area.

Using Analytic Hierarchy Process to Assess Beekeeping Suitability in Portuguese Controlled Areas: A First Approach.

Beekeeping management is greatly influenced by spatial factors (e.g., land use/land cover, roads, or electrical energy networks), so GIS are a powerful tool to overlap and relate a variety of spatial data levels and, consequently, a very useful tool for beekeeping activity planning. This study was developed within the intervention area of three controlled zones managed by Portuguese Beekeepers Associations. The methodology, based on multi-criteria decision analysis, integrates several criteria, such as hydrographic networks, road networks, soil occupation, solar radiation, and electromagnetic radiation sources. These criteria were proposed and evaluated through online questionnaires carried out with beekeepers. Concerning the selected criteria and the respective geographical data, the most relevant were land use/land cover and water availability, with a significance of 44% and 24%, respectively. The beekeeping suitability map enabled us to evaluate the degree of compliance for the actual location of apiaries, with 60% of the apiaries being installed in high potential areas. In the context of beekeeping planning, the potential of the techniques applied seems to be an important tool for optimizing the location of apiaries and the profitability of beekeeping.

Assessing sar1g distribution in the human head during hands-free mobile phone usage

This paper explores the distribution pattern of SAR1g within the adult male head during utilization of hands-free operation of contemporary mobile phones as a source of electromagnetic radiation. The research assesses the optimal positioning of the mobile phone by examining three distinct orientations to determine the minimal SAR1g distribution compared to the conventional talking position when hands-free feature is not utilized. The analysis encompasses GSM bands operating at 900 MHz and 1800 MHz, depending on the alignment between the mobile phone and the head.

Primena tehnika vizuelizacije strujanja za određivanje sile otpora projektila

The paper provides an overview of flow visualization methods. From the many ways of classifying flow visualization methods, the chosen method of classification is in accordance with the experimental procedure. Flow visualization methods that involve the addition of foreign material are the simplest, from the point of view of the required material and the experimental setup, in which one tracer and an adequate light source are most often applied, except for layers sensitive to pressure and shear stress. Their application is wide and most methods from this category can be modified very easily depending on the case. Visualization methods that involve addition of energy to the fluid flow use strong sources of electromagnetic radiation, most often lasers, to excite the molecules in the fluid stream, producing an adequate quantum-mechanical effect that enables visualization. Optical methods of flow visualization are based on changes in the refractive index of light caused by the presence of a fluid in motion in the test section, in addition, the principle of superposition of light waves is used in interferometry methods. Optical methods are mainly used in areas of supersonic flow and shock wave studies, but they are also present in exhaust gas propagation studies. As computational fluid dynamics is a separate subject, the physical laws on which CFD is based on are presented, as well as an example of flow visualization, which is an integral part of most calculations performed using this method. In addition to the classification and description of flow visualization methods, the paper provides an explanation of a approximate calculation procedure based on the use of one of the optical methods, Schlieren photography, in order to calculate the resistance force during supersonic projectile flow, as well as a comparison of results based on empirical data.

A Separation Method for Electromagnetic Radiation Sources of the Same Frequency

To separate electromagnetic interference sources with an unknown source number, a new separation method is proposed, which includes five key steps: spatial spectrum estimation, source number and direction-of-arrival estimation, mixed matrix estimation, separation matrix estimation, and source signal recovery. A pseudospatial spectrum estimation network based on a convolutional neural network is proposed to estimate the number of electromagnetic radiation sources, their direction of arrival, and the mixing matrix. A new loss function is designed as an optimization criterion for estimating the separation matrix. To ensure generalization, both simulated and measured datasets are used to train the proposed network. Experimental results demonstrate that the proposed separation method outperforms existing source separation techniques in terms of correlation coefficient, root mean square error, and running time. Importantly, it exhibits strong performance in underdetermined cases, as well as in overdetermined or determined cases.

Frequency Effect on Electromagnetic States Emitted from High Voltage Overhead Power Lines and Busbar Substation

Electrical power systems represent an immense source of electromagnetic radiation spanning a wide frequency range, encompassing low-frequency, transient states, and high-frequency emissions. The radiation poses a significant self-pollution challenge for electric and electronic devices situated in close proximity to these systems. The present article aims to address this research, and provides a comprehensive review of the electromagnetic effects and pollution at differences frequency’s ranges encompassing power systems network. In the context of the low-frequency range, the computation of electric and magnetic fields is conducted using quasi-static principles. To validate the behavior at high frequencies due to power line currents, Schelkunoff’s approach is employed. Additionally, transient electromagnetic fields are analyzed using an exact analytical method. The results of computer simulations are compared with previously published and measured data for low-frequency regime and transient overvoltage conditions, verifying their consistency. Additionally, high-frequency results are presented and corroborated through the utilization of a numerical electromagnetic code (NEC-4). These analyses underscore the valuable role of computer-based calculations in examining the electromagnetic environment of power system networks.

Model‐based systems engineering approach to the study of electromagnetic interference and compatibility in wireless powered microelectromechanical systems

AbstractElectromagnetic Interference and Compatibility (EMI–EMC) are a serious problem in Microelectromechanical Systems (MEMS), and specially in powered by wireless energy transfer MEMS. Most MEMS have dimensions in the order of 1 mm or less, thus, most of the suitable electromagnetic radiation sources have wavelengths larger than this, making isolation of electromagnetic effects very difficult. Model‐Based Systems Engineering (MBSE) can be an excellent tool to deal with EMI—EMC in MEMS during early design phases. In this work, we present a problem‐solving procedure and integration of EMI—EMC in MEMS from a Model‐Based Systems Engineering perspective. This approach is described in detail by a real example using a procedure based on nine steps fully integrated with the proposed systems engineering methodology. For example, the use of context diagrams (IBDs) and N SQUARE charts to describe EMC interactions is explained in detail. The system is formed by a Wireless Power Transfer (WPT) subsystem working near 2.45 or 4.5 GHz coupled to an electromagnetic micromotor. This micromotor contains copper microcoils which can receive electromagnetic radiation directly at the same time that the WPT subsystem. The greatest difficulty is, then, to power the WPT while isolating the micromotor, and optimizing the coupling interface. A summary of the most important EMC concepts and tools are reviewed from the systems engineer perspective and possible problems during the design and testing phases are discussed in detail using the example.

Community engagement programs on radiation and health: addressing public concerns.

Due to the negative connotations around radiation, there is a great deal of angst in the community regarding radiation exposure and health; especially electromagnetic radiation (EMR) sources such as powerlines, mobile phone towers and the rollout of the 5G network. As such, it is important for health authorities to provide the public with information and assurances regarding radiation safety. The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) set up community engagement programs to address community concerns. Type of program or service: From 2003 until April 2022, ARPANSA operated a Health Complaints Register, which collected reports of health complaints from members of the public related to possible EMR exposures. Collected data was used to produce annual statistical summaries on the nature and level of complaints received. Since 2016, ARPANSA has also run the Talk to a Scientist program, which allows the public to communicate directly with scientists on issues about radiation exposure, health and protection in Australia. Data is collected on the type of radiation and radiation source. There was a low level of interest in the Register, with only 180 reports received over the duration of its operation. Smart meters were the most common source of EMR exposure reported to be responsible for adverse health effects. The most common adverse health effect reported was headaches. The Register was closed in April 2022 due to a lack of interest. In contrast, the Talk to a Scientist program has responded to 6546 enquiries since 2016, most of which have been on EMR sources and the success of the Talk to a Scientist program, which rendered the Register obsolete. The EMR Health Complaints Register never received much interest from the public, potentially due to a perceived lack of engagement with authorities. The Talk to a Scientist program, which facilitated direct interaction with subject matter experts, has been much more successful in engaging with the public and addressing community concerns on radiation safety.

Technologies for Separation of ‘X’ and ‘Y’ Spermatozoa in Bovines: An Overview

Several approaches to sperm sexing such as Albumin gradient, Identification of H-Y antigen, Free-flow electrophoresis, Detection of sex-specific proteins, Centrifugal counter current distribution, Volumetric differences, Percoll density gradient, Flow-cytometry, Laser ablation, etc were put forward by the scientists. However, the alteration in DNA content between X- and Y-sperm remains the key and only discriminating feature for sperm sorting based on which only Flow cytometry and Laser ablation techniques are being used commercially. Flow cytometry is based on precise staining of the DNA of sperm with the nucleic acid-specific dye, Hoechst 33342, to differentiate between the subpopulations of X- and Y-sperm. The fluorescently stained sperm are then sex-sorted using a specialized highspeed sorter. Laser ablation (LA) is a system and method for sorting a mixture of stained particles in a fluid flow path. The system and method includes an electromagnetic radiation source for exciting fluorescence emissions from the stained particles, a photodetector for detecting the fluorescence emissions, a processor for classifying the stained particles, and a photo-damaging laser for damaging selected particles in the flow path.

Spatial Localization of Electromagnetic Radiation Sources by Cascade Neural Network Model with Noise Reduction

Spatial Localization of Electromagnetic Radiation Sources by Cascade Neural Network Model with Noise Reduction

Beam-Plasma Generator of the THz Radiation Based on an Induction Accelerator (LIA-PET Project)

BINP SB RAS together with RFNC-VNIITF carry out a research in the field of creating new sources of electromagnetic radiation in the THz range. Within the framework of this article, a project of the THz beam-plasma generator based on an electron beam generated by a linear induction accelerator is presented. The article provides generator scheme and describes the main elements of the electron beam formation system. In addition, the results of modeling the beam transport and its cross-section compression are presented. These calculations were performed under the current up to 1 kA and energy up to 1 MeV for the subsequent injection of the beam into the plasma section with plasma density up to 1015 –1016 cm–3. The article also contains the analysis of previous experimental studies results which are connected with the beam-plasma interaction for various beam and plasma parameters. Based on this analysis, a requirement for the ratio of the beam and plasma electron densities was formulated. This requirement should be satisfied for creation of the beam-plasma generator of EM radiation for the range of 0.1–1 THz with a pulse power of several MW.

Direction finding of electromagnetic radiation sources using the volumetric phased arrays consisting of the small number of elements

Problem statement. This article proposes a method to measure the bearing of electromagnetic radiation sources in the conditions of passive interference with multipath propagation and in the conditions of using "rough" (small number of elements) statistics taking into account particular design features of the direction finder located on a mobile object. The technical design of an adaptive direction finder (ADF) with a small number of channels M = 7 and “short spatial samples” m = 2 (bases) is substantiated, which leads to reducing hardware and software costs. Target. Determine the method of direction finding of electromagnetic radiation sources by volumetric phased arrays consisting of the small number of elements, which allow for the presence of passive interference with multipath radiation of electromagnetic radiation sources, and include spatial digital filters (DF) of a low order r = 2. Results. The problem of measuring the bearing of electromagnetic radiation sources under the conditions of correlated multipath passive interference and limited hardware and computing resources was solved. Direction finder includes a 7-element monopulse direction finder, which was built according to a sequential scheme at the nodes of a volumetric hexagonal grid with an equivalent spatial quantization step of 0.5l, forming programmable small-sized bases with a size of no more than l using the method of multiplexing (HF switching). Practical significance. The relevance of the proposed approach is substantiated due to the need to notch "multipath components", parasitic reflections from local objects surrounding the adaptive direction finder, and reduce the instrumental error in bearing measurement. A new approach to the construction of a volumetric phased array of an adaptive direction finder is proposed. Novelty. The synthesis of the optimal estimate is based on the principle of “whitewashing” passive correlated interference and the maximum likelihood method, which guarantees the achievement of potential direction finding accuracy in the conditions of using rough statistics that reduce hardware and software costs.

Experience in studying some aspects of adolescents’ lifestyle during the implementation of scientific and educational projects in the Far Eastern Federal District

The article presents the results of a study of the assessment of the lifestyle of students in educational institutions of regional and regional centers, as well as municipal educational organizations remote from the regional and regional centers of the Far Eastern Federal District, obtained as part of the implementation of a student scientific and educational project at the Department of Hygiene of the Pacific State Medical University. A survey of 1480 people was conducted, the issues of the daily use of mobile phones and the use of smoking mixtures («spice»), the parameters of the physical and psychological component of the health of adolescents in the Far Eastern Federal District were studied. It has been established that first-year students of institutions of secondary vocational education in the studied territories are daily in direct contact with a source of electromagnetic radiation for more than 7 hours a day, 63 % of respondents consider it necessary to carry out sanitary and educational work on the dangers of using smoking mixtures in educational institutions where adolescents are trained. These assessments of the quality of life indicate the presence of gender and age characteristics in adolescents aged 16–17 years of the Far Eastern Federal District. The results of the work carried out can be applied in planning educational and preventive measures with young people aimed at maintaining the physical and mental health of adolescents in the Far Eastern Federal District.

BASIC PRINCIPLES OF CONSTRUCTION OF MODULAR HARDWARE COMPLEXES FOR LED THERAPY

The industrial production of powerful light-emitting diodes has led to the appearance of devices for therapeutic purposes, where such diodes are used as sources of electromagnetic radiation in the optical range. The development and production of such devices was established in the city of Kharkiv with the participation of scientists and specialists of Kharkiv National University named after V.M. Karazin and National Technical University "Kharkiv Polytechnic Institute". Methods of using devices and hardware complexes in medical practice were created at the Kharkiv Medical Academy of Postgraduate Education. The article analyzes the main principles of building modular hardware complexes for LED therapy, defines structures and options for connecting modules. As a result of the work performed, it was established that the modular implementation of hardware complexes for LED therapy has five main options, which differ in the number and types of emitters connected to the control unit, in the connection scheme of photon emitters, and in their functionality. It was also noted that the modular principle of building hardware complexes for LED therapy makes it quite easy to carry out their modernization and form the necessary configuration of the irradiating system, that is, to significantly expand the functional capabilities of the complex for carrying out phototherapy treatment procedures with the greatest efficiency. The expediency of using microprocessor technology for the implementation of the information part of the control unit of the complex is shown. This makes it possible to ensure the operation of photon emitters in continuous, pulsed and scanning modes, as well as separate operation of the emitters of the irradiation system of the complex and irradiation of the patient in biosynchronization mode.

Protecting IoТ Wearable Devices from Electromagnetic Radiation Using Radio-Opaque Fabrics

The number of sources of electromagnetic radiation is increasing every day. In most cases, electromagnetic radiation has a negative effect on the human body, animals, and other living beings. Electromagnetic radiation negatively affects the operation of electronic devices. Due to the electromagnetic radiation of electronic devices, information may leak from them. The negative impact of electromagnetic radiation on the human body provokes a high level of fatigue, headache, heartache, etc. The everyday use of mobile equipment, household magnetic appliances (for example, microwave ovens), and telecommunication networks puts the majority of the planet's population at risk. Otherwise, the external influence of electromagnetic fields on the various sensors used in the IoT can contribute to receiving incorrect data from the sensors. The powerful external influence of the electromagnetic field on devices that process large data sets can contribute to a failure in mathematical calculations. Thus, protection from electromagnetic fields is necessary not only for electronic devices but also for human protection. Radio-opaque fabrics are one of the modern materials for protection from electromagnetic radiation. They can be used to protect stationary objects and wearable IoT devices and to protect people. Industrial samples of foreign and Ukrainian radio-opaque fabrics were analyzed in the work. Ukrainian manufacturers continue to develop new variants of radio-opaque fabrics. The next options for radiopaque fabrics are fabrics G7, G8, and G9. The article proposed and described a method of researching the shielding properties of the fabric. Experimental studies were carried out, and the shielding coefficient was calculated in the frequency range of 50 MHz - 2 GHz for two fabrics G7 and G8. Experimental studies were carried out for two cases of the location of fabric fibers relative to the radiating antenna and field polarization. Plots of dependences of the shielding coefficient for two fabrics with different locations of fabric fibers were presented. A comparative analysis of the shielding coefficients of two fabrics was made, and relevant conclusions were presented.

Plasma instability and amplified mode switching effect in THz field effect transistors with a grating gate

We developed a theory of collective plasma oscillations in a dc current-biased field effect transistor with an interdigitated dual grating gate and demonstrated a new mechanism of electron plasma instability in this structure. The instability in the plasmonic crystal formed in the transistor channel develops due to conversion of the kinetic energy carried by the drifting plasmons into electromagnetic energy. The conversion happens at the opposite sides of the gate fingers due to the asymmetry produced by the current flow, and occurs through the gate finger fringing capacitances. The key feature of the proposed instability mechanism is the behavior of the plasma frequency peak and its width as functions of the dc current bias. At a certain critical value of the current, the plasma resonant peak with a small instability increment experiencing redshift with increasing current changes to the blue-shifting peak with a large instability increment. This amplified mode switching effect has been recently observed in graphene-interdigitated structures. The obtained theoretical results are in very good qualitative agreement with these experiments and can be used in future designs of the compact sources of THz electromagnetic radiation.