Sources Of Electromagnetic Emission Research Articles

Constraining Inputs to Realistic Kilonova Simulations through Comparison to Observed r-process Abundances

Kilonovae, one source of electromagnetic emission associated with neutron star mergers, are powered by the decay of radioactive isotopes in the neutron-rich merger ejecta. Models for kilonova emission consistent with the electromagnetic counterpart to GW170817 predict characteristic abundance patterns, determined by the relative balance of different types of material in the outflow. Assuming that the observed source is prototypical, this inferred abundance pattern in turn must match r-process abundances deduced by other means, such as what is observed in the solar system. We report on analysis comparing the input mass-weighted elemental compositions adopted in our radiative transfer simulations to the mass fractions of elements in the Sun, as a practical prototype for the potentially universal abundance signature from neutron star mergers. We characterize the extent to which our parameter inference results depend on our assumed composition for the dynamical and wind ejecta and examine how the new results compare to previous work. We find that a dynamical ejecta composition calculated using the FRDM2012 nuclear mass and FRLDM fission models with extremely neutron-rich ejecta (Y e = 0.035) along with moderately neutron-rich (Y e = 0.27) wind ejecta composition yields a wind-to-dynamical mass ratio of M w /M d = 0.47, which best matches the observed AT2017gfo kilonova light curves while also producing the best-matching abundance of neutron capture elements in the solar system, though, allowing for systematics, the ratio may be as high as of order unity.

GNSS Based Low-Cost Magnetometer Calibration.

With the development of MEMS sensors, the magnetometer has increasingly become a part of various wearable devices. The magnetometer measures the intensity of the magnetic field in all three axes, resulting in a 3D vector-direction and power. Calibration must be done before using a magnetometer, especially in wearable electronics, due to the low quality of the sensor and high proximity to other electromagnetic emission sources. Several magnetometer calibration algorithms exist in the literature, with most of them requiring multi-sided rotation. However, such calibration is highly impractical when the sensor is mounted on larger objects, e.g., vehicles, which cannot easily be rotated. Vehicles contain a large amount of ferromagnetic soft and hard material that affects the measured magnetic field. A magnetometer can be useful for an INS system in a car as long as it does not drift over time. This article describes how to calibrate a magnetometer using the GNSS motion vector. The calibration is performed using data from the initial section of the vehicle's trajectory. The quality of the calibration is then validated using the remaining section of the trajectory, comparing the deviation between the azimuth obtained by GNSS and by the calibrated magnetometer. Based on the azimuth and speed of the vehicle, we predicted the position of the vehicle and plotted the prediction on the map. The experiment showed that such calibration is functional. The uncalibrated data were unusable due to the strong effect of ferromagnetic soft and hard materials in the vehicle.

On potential use of natural electromagnetic emissions in ELF, VLF and HF radio bands at active landslide areas: Preliminary results from Vinohrady nad Váhom site (Slovakia)

The use of natural electromagnetic (EM) emissions in extreme low frequency (ELF) and very low frequency (VLF) radio bands for monitoring and predicting landslide activity is examined. The approach is based on measuring EM emissions using radio receivers and subsequent correlation of their intensity with the amount and character of deformation in the landslide. There are several sources of EM emissions in the rock environment, but it is mostly the piezoelectric impulse of quartz grains during the deformation or sliding movements within rock masses. Deformation was observed in the studied landslide body. Deformations were measured using a geodetic band and a network of stakes, which were installed before and re-measured after recording a natural EM signal attributed to the geodynamic activity. A method of direct monitoring of the entire VLF spectrum using sound cards such as AD converters was applied. So far, several candidate signals were captured and two permanent VLF monitoring stations have been built.

Investigation of the Polycrystalline Silicon PV Cell Efficiency in 3D Approximation versus Electromagnetic Field under Monochromatic Illumination

This manuscript is about the electric output of the silicon (Si) photovoltaic (PV) cell versus the electromagnetic field of a radio wave and a monochromatic illumination in three-dimensional (3D) assumptions. The polarisation direction of the electromagnetic wave and power density are fixed. The electromagnetic wave is provided by electromagnetic emission sources such as the telecommunication, radio, or TV antennas. A PV system is installed in the vicinity of an electromagnetic emission source. The current produced by the PV cell is sensitive to electromagnetic field increase more than the electric voltage. The electromagnetic field causes the decomposition of the current into two components which are a transferred current and a leakage current. The transferred component provides the transmitted current to the external load while the leakage component gives the loss of the carrier charge into the junction. Consequently, this decomposition of the current shares the electric power in transferred electric power and leakage electric power. The transferred electric power is obtained only in the intermediate circuit, and the maximum power point (MPP) shifts to the short circuit situation as the junction dynamic velocity becomes the greatest. However, the leakage electric power corresponds to a loss of the minority carrier’s charge in the junction during the crossing of the junction. This loss causes a Joule heating effect of the junction. The heating of the junction causes the quality degradation of the PV cell mainly due to the electric component. The solar illumination wavelength is presenting the inversion phenomenon with the maximum of the electrical outputs of the silicon PV cell of around 0.70 μm which provides the greatest conversion efficiency. This value has been chosen for the modelling of the radio wave influence. Hence, the conversion efficiency increases when the PV system is far away from the electromagnetic emission source. PV system installation in the vicinity of an electromagnetic emission source is not advised.

Ensembles of Layered Nanowires, Obtained by Matrix Synthesis Technique, for Generation of THz Irradiation

Ensembles of parallel nanowires, consists of the parts from different ferro-magnetic metals (for example-FeNi/Co/FeNi) were obtained by method of template synthesis. It was shown that such samples could be the sources of electromagnetic emission – irradiation of Terahertz range. It could be detected when current passed through the contacts at the sample with these wires. The methods of obtaining nanowires was proposed (two-bath galvanic technique), formation of contact layers at the surface (parallel narrow strips of metal) were proposed. The features of these radiation were investigated–it‘s threshold character, it‘s non-thermal origin and spatial distribution. The calculation was also presented, which demonstrated possibility of detecting of Terahertz irradiation, using ensemble of such nanowires, included ferro-magnetic metal and anti-ferromagnetic metal.

Estimates of the Early Electromagnetic Emission from Compact Binary Mergers

Abstract Compact binary mergers that involve at least one neutron star, either binary neutron star or black hole–neutron star coalescences, are thought to be the potential sources of electromagnetic emission due to the material ejected during the merger or those left outside the central object after the merger. Since the intensity of these electromagnetic transients decays rapidly with time, one should pay more attention to early emissions from such events, which are useful in revealing the nature of these mergers. In this work, we study the early emission of kilonovae, short gamma-ray bursts (GRBs), and cocoons that could be produced in those mergers. We estimate their luminosities and timescales as functions of the chirp mass, which is the most readily constrained parameter from the gravitational wave detections of these events. We focus on the range of chirp mass as 1.3–2.7 M ⊙, which is compatible with one of the merging components being a so-called “mass gap” black hole. We show that the electromagnetic observation of these transients could be used to distinguish the types of the mergers when the detected chirp mass falls in the range of 1.5–1.7 M ⊙. Applying our analysis to the subthreshold GRB GBM-190816, we found that for this particular event the effective spin should be larger than 0.6 and the mass of the heavier object might be larger than 5.5 M ⊙ for the phenomenological Steiner–Fischer–Hempel equation of state.

Electromagnetic Safety of Remote Communication Devices—Videoconference

Devices powered by electricity become sources of electromagnetic emissions in the course of their operation. In the case of devices oriented to process information, these emissions can have a character of revealing emissions, i.e., those whose reception and analysis allow for remote reconstruction of related data. The best known example of this phenomenon is the formation of revealing emissions during the operation of imaging devices: monitors, projectors or printers. Increasingly more often, these components are used for communication in the form of videoconferences with other network users. The article presents the result of tests and analyses of threats related to the use of such solutions (monitors, personal computers, VoIP terminals) for the confidentiality of conversations and the data presented during them. The focus is on video signals; however, the potential possibilities of revealing speech signals were also indicated. Such phenomenon causes a huge threat to data confidentiality because the combination of graphics and sound can undoubtedly contain much more information about the protected data than just graphics or sound separately. The presented results of analyses apply to graphic data, possibilities of non-invasive acquisition of such data, similarity of images and of patterns and reconstructed image and image recognition. The results indicate that there is still a risk of loss of data confidentiality due to a phenomenon of an electromagnetic leakage, and specialized instrumentation is not required for its interception under favorable circumstances. This may particularly apply to audio data that may be accidentally received by home radio receivers. In particular, the presented results of analyses apply to a Special Issue of Symmetry which is characterized by security and privacy in communication systems and networks, signal processing, video and image processing, multimedia communications and electromagnetic compatibility. All these scientific and technical areas have either symmetrical or asymmetrical approaches, and they have to be taken into consideration as a whole in order to choose the best combinations to protect processed information.

Sensitization of glioblastoma cells to temozolomide by a helium gas discharge tube

Glioblastoma is one of the most aggressive brain cancers. Chemotherapy is a standard modality for its therapy. Here, we demonstrated a novel strategy using a helium gas discharge tube as a tunable electromagnetic emission source to sensitize glioblastoma cells to the cytotoxicity of temozolomide (TMZ), a widely used drug for glioblastoma. After a single 7-min of treatment, the efficacy of TMZ was enhanced in two typical glioblastoma cell lines U87MG and A172 without affecting a normal human astrocyte cell line hTERT/E6/E7. The discharge tube is a non-invasive approach, which provides a safe, controllable, stable, and low-cost modality to improve the conventional chemotherapy.

MILP, Pseudo-Boolean, and OMT Solvers for Optimal Fault-Tolerant Placements of Relay Nodes in Mission Critical Wireless Networks*

In critical infrastructures like airports, much care has to be devoted in protecting radio communication networks from external electromagnetic interference. Protection of such mission-critical radio communication networks is usually tackled by exploiting radiogoniometers: at least three suitably deployed radiogoniometers, and a gateway gathering information from them, permit to monitor and localise sources of electromagnetic emissions that are not supposed to be present in the monitored area. Typically, radiogoniometers are connected to the gateway through relay nodes. As a result, some degree of fault-tolerance for the network of relay nodes is essential in order to offer a reliable monitoring. On the other hand, deployment of relay nodes is typically quite expensive. As a result, we have two conflicting requirements: minimise costs while guaranteeing a given fault-tolerance. In this paper, we address the problem of computing a deployment for relay nodes that minimises the overall cost while at the same time guaranteeing proper working of the network even when some of the relay nodes (up to a given maximum number) become faulty (fault-tolerance). We show that, by means of a computation-intensive pre-processing on a HPC infrastructure, the above optimisation problem can be encoded as a 0/1 Linear Program, becoming suitable to be approached with standard Artificial Intelligence reasoners like MILP, PB-SAT, and SMT/OMT solvers. Our problem formulation enables us to present experimental results comparing the performance of these three solving technologies on a real case study of a relay node network deployment in areas of the Leonardo da Vinci Airport in Rome, Italy.

Nonstationary Quasiperpendicular Shock and Ion Reflection at Mars

AbstractCollisionless shocks in space plasma are regions of heating and acceleration of charged particles and dissipation of kinetic energy. These accelerated particles are the source of electromagnetic emissions from supernova remnants and other astrophysical structures. At high Mach numbers, shocks can be inherently nonstationary and exhibit modulated energy transfer and recurring plasma compression areas in the form of reformation. We use data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft to study reformation of the Martian bow shock, which has a relatively high curvature compared to that at Earth, and the upstream solar wind is often mass loaded with a population of pickup ions. We show evidence of ion reflection effects in reformation of a supercritical quasiperpendicular shock.

Research on high-rate and repeat frequency discharge lithium battery for electromagnetic launch primary power supply

Lithium battery with excellent comprehensive performance can effectively improve the firing frequency of railgun, firing times of railgun, system integration and security of electromagnetic launch weapon system. The development of lithium-ion batteries were introduced in this paper, mainly from the material system of lithium battery, analyzes all kinds of lithium battery, combined with electromagnetic emission weapon system for high voltage cascade characteristics of primary lithium battery power supply demand, points out the advantages and disadvantages of the lithium battery materials system, determine the improved after optimization of high ratio of lithium iron phosphate battery as primary power battery components. Two kinds of lithium batteries have been tested by high power discharge test, which proves that the high power lithium iron phosphate batteries have better performance. The high power lithium iron phosphate battery with soft package, high discharge rate, high power density and good security, can meet the requirements of high power, high power density and good integration of the primary source of electromagnetic emission.

Analysis and development of an electromagnetic exposure map based in spatial interpolation

The increasing demand for electricity has led humans to a growing exposure to artificial sources of electromagnetic emission, making it essential to determine the intensity of electromagnetic fields (EMFs), which is subject to the population of a given area. This Letter proposes an analysis of EMF exposure levels and spatial distribution over the region of the input and power circuits of a 230 kV/60 Hz air-insulated substation. For this, measurement protocols were determined based on current standards and from spatial interpolation methods, a contour map was developed, allowing a complete evaluation of the behaviour and levels of EMF throughout the region. The results obtained indicate that exposure levels in this region are below those recommended by regulatory agencies.

A New Electromagnetic Emission Source Frequency and Factor Identification Approach for Nonlinear Circuits From the Output Spectrum Data

For the practical nonlinear circuits, a number of new frequencies are generated in the output spectrum, which makes electromagnetic interference location quite challenging. To mitigate this problem, an approach is proposed to identify the electromagnetic emission source frequencies and nonlinear factors from the output spectrum of nonlinear circuits. The amplitude of the output spectrum with the input of two sine signals is first calculated based on the power series. Then, the Order Image (OI) is defined to reveal the output spectrum features, and its symmetry characteristic has been comprehensively analyzed. Results show that the maximum symmetry index is observed when the reference frequencies are equal to the excitation frequencies. Based on this observation, the electromagnetic emission source frequencies can be obtained. In addition, a Backward Algorithm (BA) has been introduced to extract nonlinear factors. The proposed approach only requires the output spectrum and the amplitude of one excitation. Compared with other techniques, like the Support Vector Machines and the Recurrent Neural Network, it needs much less prior information. Finally, several examples are carried out to verify the effectiveness of the proposed approach. Results show that the emission source frequencies and nonlinear factors can be accurately extracted. Therefore, the proposed approach shows great potential in electromagnetic interference location and characteristic analysis for nonlinear circuits.

A Search for Optical Emission from Binary Black Hole Merger GW170814 with the Dark Energy Camera

Abstract Binary black hole (BBH) mergers found by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo detectors are of immense scientific interest to the astrophysics community, but are considered unlikely to be sources of electromagnetic emission. To test whether they have rapidly fading optical counterparts, we used the Dark Energy Camera to perform an i-band search for the BBH merger GW170814, the first gravitational wave (GW) detected by three interferometers. The 87 deg2 localization region (at 90% confidence) centered in the Dark Energy Survey (DES) footprint enabled us to image 86% of the probable sky area to a depth of i ∼ 23 mag and provide the most comprehensive data set to search for electromagnetic (EM) emission from BBH mergers. To identify candidates, we perform difference imaging with our search images and with templates from pre-existing Dark Energy Survey (DES) images. The analysis strategy and selection requirements were designed to remove supernovae and to identify transients that decline in the first two epochs. We find two candidates, each of which is spatially coincident with a star or a high-redshift galaxy in the DES catalogs, and they are thus unlikely to be associated with GW170814. Our search finds no candidates associated with GW170814, disfavoring rapidly declining optical emission from BBH mergers brighter than i ∼ 23 mag (L optical ∼ 5 × 1041 erg s−1) 1–2 days after coalescence. In terms of GW sky map coverage, this is the most complete search for optical counterparts to BBH mergers to date.

Электромагнитная совместимость комплексной установки воздействия на боевых пловцов с близкорасположенной радиоэлектронной аппаратурой

The article deals witht hep roblem concerned with the effect the impulse electromagnetic field propagating from the electrohydraulic shock installation (EHSI) has on operation of the nearby radioelectronic devices. The problem of electromagnetic compatibility is extremely important for a llkinds of military forces, especially for warships, because they contain a multitude of radioelectronic devices and systems for various purposes within a very limited space. The impulse electromagnetic field distribution patternin the near-emission zone ofthe anti-sabotage electrohydraulic shock installation generating powerful electromagnetic impulse sisstudied. The EHSI application fields are classified in asystemati cmanner, and the operation principles of a particular EHSI adopted for service are considered. The performed analysis made it possible toreveal the key component serving as the main source of electromagnetic emission. The oretical dependenc esdescribing the distributions of magnetic and electrical field amplitudes as functions of the distance from the emission source are obtained. To verify the theoretical calculations, an experiment for determining the EMF induced in aerials from the impulse electromagnetic field generated by the considered EHSI was carried out. The graphs depicting the distributions of impulse magnetic and electrical fields trength amplitudes testify that the the oretical and experimental data are almost identical with each other.

Design of a High-Speed Solid-Rotor Induction Machine With an Asymmetric Winding and Suppression of the Current Unbalance by Special Coil Arrangements

High-speed solid-rotor induction machines (IMs) suffer from higher rotor eddy-current losses (as a result of the air-gap flux density harmonics) more than any other type of high-speed machines because of the solid-rotor steel. A double-layer short-pitch asymmetric winding arrangement with prefabricated coils is proposed in this paper to mitigate the solid-rotor losses and enable easier assembly. However, the asymmetric winding also brings some current unbalance because of three-phase asymmetric stator inductances, especially the winding leakage inductances. Current unbalance can cause harmful effects for both the machine and supply, e.g., torque ripples, unbalanced magnetic pulls, and unbalanced thermal loads of the supply network and supply power electronics. Additionally, a three-phase unbalanced current can cause an extra source of electromagnetic emission to the environment, which can be harmful to surrounding electronics and can cause extra eddy-current losses in surrounding solid surfaces (e.g., a metal terminal box). To mitigate the current unbalance, two methods are compared in this paper. The first method is a slight increase of the stator slot height and placing of the coil sides at the top or bottom within the slot height for different phases. The stator slot height is optimized based on the 2-D finite-element method (FEM) to achieve the best solution for mitigation of the current unbalance. The other method is based on the results of the first method, and the coil side position for a specific phase is further adjusted. Unlike conventional methods of mitigating the current unbalance by power electronics, the proposed method suppresses the current unbalance solely by adjusting the machine design, which avoids extra investments for power electronics devices. In addition, the machine control strategy remains unchanged compared with the traditional one.

Basic Emission Waveform Theory: A Novel Interpretation and Source Identification Method for Electromagnetic Emission of Complex Systems

Variable numerous types of equipment/subsystems may exist in complex systems, which makes it difficult to analyze and identify electromagnetic emission sources. A theory named “basic emission waveform theory” is presented in this paper to solve this problem. This innovation theory characterizes emission with four basic waveforms, including square wave, sine wave, damped oscillation, and spike wave. Then, the effectiveness of the theory is discussed in both theoretical and engineering ways. In particular, the basic waveforms reflect the physical characteristics of the equipment. Furthermore, the basic waveforms generally do not vary with the locations or loading conditions. Therefore, the identification and analysis of an emission source can be realized by analyzing the basic waveforms from the emission of a complex system. Finally, the applications of damped oscillation and square wave in emission source identification field are used as validations of the proposed theory. Moreover, an example of emission source identification for an electric vehicle is also presented. The examples show that the proposed theory can be used to simply and accurately identify and analyze the emission sources of complex systems.

Particle simulation of electromagnetic emissions from electrostatic instability driven by an electron ring beam on the density gradient

This paper presents the wave mode conversion between electrostatic and electromagnetic waves on the plasma density gradient. We use 2-D electromagnetic code KEMPO2 implemented with the generation of density gradient to simulate such a conversion process. In the dense region, we use ring beam instability to generate electron Bernstein waves and we study the temporal evolution of wave spectra, velocity distributions, Poynting flux, and electric and magnetic energies to observe the wave mode conversion. Such a conversion process can be a source of electromagnetic emissions which are routinely measured by spacecraft on the plasmapause density gradient.

Design and Analysis of the DC–DC Converter With a Frequency Hopping Technique for EMI Reduction

As more circuit functions are integrated within a single die or small integrated package, the number of electromagnetic interference (EMI) problems caused by dc–dc converters is growing. In this paper, the dominant electromagnetic emission source on the dc–dc converter is identified by analyzing the power spectrum of the nodes. The noise scanner method is applied to a packaged single-chip prototype dc–dc converter. The results show that the dominant source of electromagnetic emission is the switching node of the converter, not the output node. The frequency hopping technique (FHT) is applied to the dc–dc converter to reduce the emission at the switching node, and its effectiveness is analyzed mathematically and experimentally. The mathematical model of FHTs is proposed to analyze its effectiveness in reducing EMI, and the optimal design using the FHT and dead-time control is fabricated with 0.18- $\mu \text{m}$ CMOS technology. The measured power spectrum reduction by using the optimal FHT design and dead-time control at the switching node is 16 dB. The EMI reduction amount of the proposed design measured by the IC-stripline method is 12.6 dB at the fundamental switching frequency.

The influence of the structure of useful signal on the efficacy of sensitive emission of laser printers

The article presents issues related to the development of sensitive emission when laser printer is in operation. The article describes the possibility to control the efficacy of the source of emission, which is the printer's laser, through various selections of quality of the printout. Various laser printer modes were tested. Each of these modes was the source of electromagnetic emissions. The operating modes of laser printers were assessed from the effectiveness of the electromagnetic infiltration process point of view. The operation of a printer with a toner save option, which generates useful signal with a high degree of susceptibility to infiltration, is of a great importance. The obtained results were presented graphically in the form of images recreated from registered signals of adverse emission. The results show that the level of electromagnetic safety or susceptibility to electromagnetic infiltration of laser printers depends on the mode of operation of the device.