Field Strength Levels Research Articles

MHD Simulation in Galactic Center Region with Radiative Cooling and Heating

We investigate the role of magnetic field on the gas dynamics in a galactic bulge region by three-dimensional simulations with radiative cooling and heating. While a high-temperature corona with T > 106 K is formed in the halo regions, the temperature near the midplane is ≲104 K following the thermal equilibrium curve determined by the radiative cooling and heating. Although the thermal energy of the interstellar gas is lost by radiative cooling, the saturation level of the magnetic field strength does not significantly depend on the radiative cooling and heating. The magnetic field strength is amplified to 10 μG on average and reaches several hundred microgauss locally. We find the formation of magnetically dominated regions at midlatitudes in the case with the radiative cooling and heating, which is not seen in the case without radiative effect. The vertical thickness of the midlatitude regions is 50–150 pc at the radial location of 0.4–0.8 kpc from the Galactic center, which is comparable to the observed vertical distribution of neutral atomic gas. When we take the average of different components of energy density integrated over the galactic bulge region, the magnetic energy is comparable to the thermal energy. We conclude that the magnetic field plays a substantial role in controlling the dynamical and thermal properties of the galactic bulge region.

COMBINING MAGNETICALLY ASSISTED AND MATRIX-ASSISTED 3D BIOPRINTING FOR ANISOTROPIC TISSUE ENGINEERING

A major obstacle in biofabrication is replicating the organization of the extracellular matrix and cellular patterns found in anisotropic tissues within bioengineered constructs. While magnetically-assisted 3D bioprinting techniques have the potential to create scaffolds that mimic natural biological structures, they currently lack the ability to accurately control the dispersion of magnetic substances within the bioinks without compromising the fidelity of the intended composite. To overcome this dichotomy, the concepts of magnetically- and matrix-assisted 3D bioprinting are combined here. This method preserves the resolution of printed structures by keeping low viscosity bioinks uncrosslinked during printing, which allows for the arrangement of magnetically-responsive microfibers without compromising the structural integrity of the design. Solidification is induced after the microfibers are arranged in the desired pattern. Furthermore, the precise design of these magnetic microfillers permits the utilization of low levels of inorganic materials and weak magnetic field strengths, which reduces the potential risks that may be associated with their use. The effectiveness of this approach is evaluated in the context of tendon tissue engineering, and the results demonstrate that combining the tendons like anisotropic fibrous microstructure with remote magneto-mechanical stimulation during in vitro maturation provides both biochemical and biophysical cues that effectively guide human adipose-derived stem cells towards a tenogenic phenotype In summary, the developed strategy allows the fabrication of anisotropic high-resolution magnetic composites with remote stimulation functionalities, opening new horizons for tissue engineering applications.Acknowledgments: ERC Grant CoG MagTendon nr 772817, BioChips PoC project nr 10106930, (PD/BD/129403/2017), (CEECIND/01375/2017), (2020.03410.CEECIND), (2022.05526.PTDC), (ED481B2019/025).

Formation of amyloid fibrils from ovalbumin under Ohmic heating

Ohmic heating (OH) is an alternative sustainable heating technology that has demonstrated its potential to modify protein structures and aggregates. Furthermore, certain protein aggregates, namely amyloid fibrils (AF), are associated with an enhanced protein functionality, such as gelation. This study evaluates how Ohmic heating (OH) influences the formation of AF structures from ovalbumin source under two electric field strength levels, 8.5 to 10.5 and 24.0–31.0 V/cm, respectively. Hence, AF aggregate formation was assessed over holding times ranging from 30 to 1200 sunder various environmental conditions (3.45 and 67.95 mM NaCl, 80, 85 and 90 °C, pH = 7). AF were formed under all conditions. SDS-PAGE revealed that OH had a higher tendency to preserve native ovalbumin molecules. Furthermore, Congo Red and Thioflavin T stainings indicated that OH reduces the amount of AF structures. This finding was supported by FTIR measurements, which showed OH samples to contain lower amounts of beta-sheets. Field flow fractioning revealed smaller-sized aggregates or aggregate clusters occurred after OH treatment. In contrast, prolonged holding time or higher treatment temperatures increased ThT fluorescence, beta-sheet structures and aggregate as well as cluster sizes. Ionic strength was found to dominate the effects of electric field strength under different environmental conditions.

Artificial Neural Network Based Prediction of Long-Term Electric Field Strength Level Emitted by 2G/3G/4G Base Station

Accurate predictions of radio frequency electromagnetic field (RF-EMF) levels can help implement measures to reduce exposure and check regulatory compliance. Therefore, this study aims to predict the RF-EMF levels in the medium using an artificial neural network (ANN). The work was conducted at Ondokuz Mayis University, Kurupelit Campus, where the measurement location has line-of-sight to the base stations. Band selective measurements were also performed to assess the contribution of 2G/3G/4G services to the total RF-EMF level, which was found to be the highest among all services within the total band. Long-term RF-EMF measurements were carried out for 35 days within the frequencies of 100 kHz to 3 GHz. Then, an ANN model with Levenberg–Marquardt (LM) and Bayesian Regulation (BR) algorithms was proposed, which utilized inputs from real-time RF-EMF measurements. The performance of the models was assessed in terms of mean squared error (MSE) and regression performance. The average MSE and regression performances of the models were similar, with the lowest testing MSEs of 2.78 × 10−3 and 3.76 × 10−3 for LM and BR methods, respectively. The analysis of the models showed that the proposed models help to predict the RF-EMF level in the medium with up to 99% accuracy.

Hygienic Studies of Electromagnetic Fields in the Work Environment during Operation of Ground-Based Radio Navigation and Aircraft Landing

Introduction: The development of navigation support for flights takes place in an environment of constantly increasing intensity of aeronautics, stricter requirements for accuracy, volume, and reliability of navigation information, efficiency of its processing. Radio navigation aids are improving, thus necessitating assessment of the electromagnetic situation at the workplaces of the personnel servicing modern equipment. Objective: To study and assess electromagnetic fields in the work environment of personnel engaged in the maintenance and operation of modern means of radio navigation and aircraft landing. Materials and methods: The research was carried out at three civil aviation facilities (two airports and an airfield) in 2021–2022. We established the composition, technical characteristics of the equipment, its operating modes, and parameters of radio frequency signals and measured the levels of electromagnetic fields at workplaces using the P3–42 electromagnetic radiation level meter. Results: The personnel are exposed to multi-frequency modulated electromagnetic fields of varying intensity. During the operation of glide and course radio beacons, radio transmitting devices at the dispatchers’ workplaces, levels of energy flux density and electric field strength exceeding hygienic standards are not created. In the premises of the hardware remote and near drive beacons, during the operation of the drive automatic radio station, an excess of the hygienic standards for the intensity of the electric field of the medium-wave range established for an 8-hour working day was registered; in the territory, the radiation from the antennas did not exceed the maximum permissible levels. Conclusions: The professional activity of the personnel servicing modern means of radio navigation and aircraft landing is carried out in a complex electromagnetic environment. A specific feature of working conditions is the effect on the body of multi-frequency, modulated electromagnetic fields of varying intensity and duration of exposure. These characteristics of radio frequency signals are essential adverse parameters that affect the formation of body responses. When choosing devices measuring the levels of electromagnetic fields, it is necessary to take into account the modulation parameters of radio frequency signals.

Reducing Emitter Clogging in Drip Fertigation Systems by Magnetization Technology

The issue of emitter clogging is a common phenomenon in drip fertigation systems, which causes uneven irrigation and fertilization. However, efficient and environmentally friendly methods are scarcely available for alleviating clogging. In the present study, we investigated the anti-fouling efficacy of three magnetic field strength levels (0, 0.4 T and 0.6 T) on emitter clogging in drip fertigation systems. Our results show that magnetized water treatment could effectively relieve emitter clogging and delay the occurrence time of clogging, which increased the average discharge variation rate (Dra) by 37.00–61.64% and decreased the dry weight (DW) by 53.00–69.29% compared with non-magnetized water treatments. X-rays were used to estimate the compositions of the main clogging substances, and the results show that phosphates were the dominant substances that induced emitter clogging. In addition, magnetized water treatment effectively reduced the contents of chemical and particulate fouling, as exhibited by a decrease in phosphates, silicate and quartz by 53.17–69.58%, 47.22–61.95% and 43.18–74.80%, respectively. In comparison, the higher strength of magnetized water treatment (0.6 T) was better in clogging control, which increased Dra and the Christiansen of uniformity (CU) by 24.64% and 43.96%, respectively, and the DW was reduced by 34.67% compared with that of 0.4 T. This study proves that magnetized water treatment is an effective, chemical-free treatment method with great potential for fouling control technology, and it is helpful for the further promotion of drip fertigation technology.

Efficient Use of a Hybrid Chamber for Radiated Susceptibility Tests

This letter describes the design and operation of a novel type of hybrid chamber used for radiated susceptibility tests. This is a semi-anechoic chamber with the possibility to install a vibrating intrinsic reverberation chamber inside. This testing environment can be used for the execution of the radiated susceptibility tests using both the deterministic and stochastic methodologies but without changing the test location, nor moving the device under test with its auxiliary equipment. This allows test engineers to combine the advantages of both reverberation and semi-anechoic chambers with a minimum effort, making it a very practical, cost- and time-efficient solution. The electric field into the reverberation chamber is monitored by eight electric field probes, permitting the closed-loop control of the electric field strength level and an efficient real-time analysis of the performance indicators discussed in this letter.

Electrons with Planckian scattering obey standard orbital motion in a magnetic field

In various so-called strange metals, electrons undergo Planckian dissipation1,2, a strong and anomalous scattering that grows linearly with temperature3, in contrast to the quadratic temperature dependence expected from the standard theory of metals. In some cuprates4,5 and pnictides6, a linear dependence of resistivity on a magnetic field has also been considered anomalous—possibly an additional facet of Planckian dissipation. Here we show that the resistivity of the cuprate strange metals Nd0.4La1.6−xSrxCuO4 (ref. 7) and La2−xSrxCuO4 (ref. 8) is quantitatively consistent with the standard Boltzmann theory of electron motion in a magnetic field, in all aspects—field strength, field direction, temperature and disorder level. The linear field dependence is found to be simply the consequence of scattering rate anisotropy. We conclude that Planckian dissipation is anomalous in its temperature dependence, but not in its field dependence. The scattering rate in these cuprates does not depend on field, which means that their Planckian dissipation is robust against fields up to at least 85 T.

Simulation of the electric field of a polymer bushing in the Ansys Maxwell software environment

The article analyses the software tools for modelling the maps of the electric field strength of insulators. The need to address this issue is dictated by the fact that the uneven electric field on the insulators increases the probability of partial discharges that destroy the insulating layer, so it is very important to optimize the electric field strength on the insulator. The design features of bushings and features of partial discharges in them are considered. The distribution of electric field strength in a polymer pass-through operating in an AC network without contaminants is considered. The results of modelling the electric field of insulators in the software environment Ansys Maxwell, which is based on the simulation of the finite element method, are presented. Points in the construction of a 35 kV bushing polymer insulator have been identified, where the highest level of electric field strength is concentrated. A method of influencing the area under study in the area of the flange connection to the ground plate is proposed. This defines the use of a conductive cover placed between the flange and the place of connection to the polymeric insulating layer, which significantly improves the overall electric field strength distribution on the surface of the bushing polymer insulator and makes it competitive compared to the most commonly used porcelain bushings, by increasing the electrical strength of the structure. According to the results of research, a means of optimizing the electric field of the pass-through polymer insulator is proposed, which allows to increase its electric resistance and reduce the electric field strength in the area of flange contact with the mounting surface, which in turn prevents premature partial discharges in the insulating bodies.

A Numerical Approach to Analyze the Performance of a PEF-Ohmic Heating System in Microbial Inactivation of Solid Food

Pulsed Electric Fields (PEF) technology has been recently proposed as a new ohmic-heating system for the heat treatment of solid products in short periods (less than 1 min). However, similar to traditional ohmic heating, non-homogeneous distribution of temperature has been observed and cold points appeared in the interphase between the solid treated product and the electrodes, which can limit the technology for assuring food safety for treated solid products. In this investigation, a computational axisymmetric model of a lab-scale PEF system for a solid product (agar cylinder) was developed. This model was used to predict the temperature and the electric field distribution, treatment time, and the microbial inactivation (Salmonella Typhimurium 878) in the solid product after a PEF-ohmic treatment. Using a factorial analysis, a total of 8 process conditions with different settings of applied field strength levels (2.5–3.75 kV/cm), frequencies (100–200 Hz), and initial agar and electrode temperature (40–50°C) were simulated for the agar cylinder in order to identify the effect and optimal values of these parameters, which offer the most temperature homogeneity. The results showed that the initial temperature of the agar and the electrodes was of great importance in achieving the best temperature uniformity, limiting the occurrence of cold points, and therefore, improving the homogeneity in the level of inactivation of Salmonella Typhimurium 878 all over the agar cylinder. A treatment of 2.3 s would be enough at 3.75 kV/cm, 200 Hz with an initial temperature of 50°C of the agar and the electrodes, for a 5-Log10 reduction of Salmonella Typhimurium 878 in the whole product with a deviation of 9°C between the coldest and hottest point of the solid.

Generation of a Flat-Top Magnetic Field With Multiple-Capacitor Power Supply

The flat-top magnetic field (FTMF) can meet scientific experimental requirements for higher magnetic intensity, longer flat-top pulse width, and lower ripple in physics, chemistry, biology, and other scientific fields. This paper proposes an FTMF system powered by the multiple-capacitor power supply (MCPS). The MCPS consists of several capacitor banks with customizable capacitance and given voltage. These banks discharge sequentially based on the designed time-series to yield an FTMF. Compared with other methods for generating the FTMF, the MCPS can easily generate FTMFs with high parameters and flexible adjustability of the pulse width. Due to the coupled variable parameters between and within the power supply and the magnet, a hybrid algorithm based on the genetic algorithm (GA) and particle swarm optimization (PSO) is applied to calculate the discharge parameters of the MCPS. The optimal solution from the GA-PSO hybrid algorithm is visualized and selected by the basis vector method. For verifying the effectiveness of the MCPS and the optimization method, a series of FTMFs at different magnetic field strength levels are modeled in MATLAB/Simulink and achieved in the experiment. The generated FTMF with the highest field strength is 50 T, its pulse width is 70 ms, and ripple is less than 0.7%.

Electrokinesis hypothesis of neuron selection for synapse formation and pruning

What neurons are connected and what neurons are disconnected? These are crucial questions since they determine the structural connectivity of the brain. We address this matter in question and propose a speculative hypothesis. We claim that the neuron selection for synapse formation and pruning process is an electrokinesis-based stochastic physical process. Propagating input signals generate a varying electromagnetic field in the interstitial fluid, which is filled with ions. Varying electromagnetic field exerts Lorentz force on the ions and causes local fluid flows. These fluid flows alter the position of presynaptic boutons and dendritic spines, and hence the likelihood of making contact. Above a certain level of field strength, the likelihood of pruning increases. If the proposed hypothesis is correct, in addition to explaining the natural process of neuron selection for synapse formation and pruning, it can also explain why and why not brain stimulation techniques work. Additionally, it will provide a controllable mechanism to alter brain connectivity as desired, which may have a profound impact on many connectivity-based psychiatric and neurological diseases.

Electromagnetic Pollution as a Possible Explanation for the Decline of House Sparrows in Interaction with Other Factors

In recent decades, there has been a decline of the House Sparrow (Passer domesticus), mainly in European cities, and several hypotheses have been proposed that attempt to determine the causes of this rapid decline. Previous studies indicated that house sparrows were significantly negatively associated with increasing electromagnetic radiation and sparrows disappeared from areas most polluted. In addition, there are many studies on the impact of radiation on other bird and non-bird species, as well as numerous laboratory studies that demonstrated detrimental effects at electric field strength levels that can be found in cities today. Electromagnetic radiation is the most plausible factor for multiple reasons, including that this is the only one that affects the other hypotheses proposed so far. It is a type of pollution that affects productivity, fertility, decreases insects (chicken feed), causes loss of habitat, decreases immunity and can promote disease. Additionally, the recent sparrow decline matches the deployment of mobile telephony networks. Further, there are known mechanisms of action for non-thermal effects of electromagnetic radiation that may affect sparrows causing their decline. Thus, electromagnetic radiation must be seriously considered as a factor for house sparrows’ decline, probably in synergy with the other factors previously proposed.

Methodology for determining the threshold distance for estimating the main EM exposure contribution in WLAN

The location of radiation sources in wireless networks is a key factor to characterize their contribution to electromagnetic exposure levels in order to deploy future networks that account for minimizing electromagnetic field levels. In relation to wireless local area networks, considering that mobile communication devices comply with the SAR (Specific Absorption Rate) limits imposed by the international standardization organizations for preserving human health, the interest is nowadays focused on the signal levels coming from the WiFi access points. This paper presents a methodology to determine the threshold distance at which the field strength levels from the AP are negligible in comparison with the radiation generated by a user equipment. The theoretical concepts, which can be applied to other technologies, were implemented by means of simulations and experimental measurements. For the simulations, actual WiFi antennas were modelled. Experimental measurements completed the results obtained in simulations, resulting in a greater number of real situations. Results showed that the threshold distance depends on the WiFi standard employed by the devices connected to the network.

ВИЗУАЛИЗАЦИЯ ГЕОДАННЫХ СЕЗОННЫХ КОЛЕБАНИЙ МАГНИТНЫХ ПОЛЕЙ НА БАЗЕ ESRI ARCGIS

Energy objects, installations of high and ultra-high voltage, are considered man-made, dangerous objects in terms of the intensity of the electric and magnetic field distribution, which create ion shells in high-altitude zones and spread a certain radius on the territory of a residential area. In this regard, during the construction and commissioning of low-frequency power facilities, it is necessary to conduct a specific environmental analysis on the selected territory. One of the main sanitary and epidemiological requirements for the construction and commissioning of high – voltage power lines is to take into account changes in the daily and seasonal distribution of electrical loads along high-voltage power lines, which have a continuous dynamic characteristic that increases the level of electric and magnetic field strength. In turn, the development of information support for environmental problems of the territory based on GIS technologies makes it possible to record information about the ecological state of the territory at a specific time and present this state with a set of thematic environmental maps of various territorial or district entities. It should be noted that the above characteristics increase the advantage of geoinformation technologies as an information platform of the database, which will make it possible to obtain data for processing operational analyses and conclusions about the state of the environment around high-voltage power lines.

Examining EMF Time Series Using Prediction Algorithms With R

In this study, electric field strength ( E) levels of high-voltage lines were measured monthly in Sütlüce (38°N, 41°E), Muş, Turkey, between 2014 and 2018, and the obtained 60 monthly mean values were used as time series (TS) to forecast next 12 months by using conventional statistical and deep learning (DL) algorithms. In addition to the conventional statistical and DL algorithms developed for R, advanced algorithms, such as long short-term memory (LSTM) and recurrent neural network (RNN) derivative, were also used in the prediction process. We applied a cross-validation technique to the electromagnetic field (EMF) data set obtained in a period of 60 months. Thus, multiple algorithm performances were compared for the same data set. In addition, the electrical field values measured in the Sütlüce neighborhood were found to exceed the International Commission on Non-Ionizing Radiation Protection (ICNIRP) values.

Mathematical modelling of the electric field of carbon nanotube arrays used in cold cathode electron emission devices

Influence of the ratios of the carbon nanotube arrays geometrical parameters (height to radius – H/R, distance between the individual nanotube to height – S/H) on their properties to enhance the electric field strength at their tips and to accumulate electrostatic charge have been investigated. It was done with the help of their electric field mathematical modelling. Such modelling has shown that dependences of the emission current density on S/H ratio have maximums that are determined both by H/R and the applied electric field strength levels.

Triboelectric charging of dust particles during hand-held circular sawing of wood and wood-based materials

ABSTRACT During machining, wood particles are generated, released, and accelerated at high speed. Wood dust is known to be unpleasant, causing technical problems, but bears also considerable health risks. Wood dust consists of fractured tissues and has a high, irregularly structured surface due to tiny hooks formed by abundant sticking out fibrillar fragments. Targeting at a novel approach for dust reduction, this communication investigates triboelectric charging of wood particles upon cutting of wood samples using a hand-guided miter saw. The impact of wood species, number of saw blade teeth, cutting direction, and wood moisture, on electric field strength levels and polarity of generated wood particles were measured, using a electrostatic detection apparatus. The generated wood particles have shown accumulated triboelectric charging, as indicated by electric field strengths, which varied between −4 and +10 V m−1. The intensity of the charge transfer was inversely proportional to the moisture content, especially when cut cross-sectionally. Highest field strengths were observed for beech, cut perpendicular to grain. Even though being a highly undesired effect, triboelectric charging of wood bears a novel opportunity for reducing the current dust burden in home and industrial wood processing environments, which is subject of ongoing and future research.

Impact of the pulsed electric field on physicochemical properties, fatty acid profiling, and metal migration of goat milk

Raw goat milk was treated with a continuous mode of pulsed electric field (PEF) system, at three levels of field strength (20, 30, and 40 kV/cm) with monopolar square-wave pulses of 5 and 10 µs treatment time. The physicochemical properties, particle size distribution, fatty acid profiling, and metal migrations of untreated and PEF-treated goat milk were evaluated. The results indicated that PEF-treated goat milk (40 kV/cm; 10 µs) had significant changes (p < .05) in pH and titratable acidity value of the samples due to the decrease in calcium ion (Ca2+), which leads to the protonation of the phosphate. The specific surface area (SSA) value significantly increased (p < .05) with the increase of PEF treatment time. PEF treatment was shown to reduce (p < .05) the total saturated fatty acids (∑SFAs) and total polyunsaturated fatty acids (∑PUFAs) of goat milk, while total monounsaturated fatty acids (∑MUFAs) were increased. The disintegration of fat and triacylglycerol breakdown from the fat globule (FG) membrane, together with heterogeneous metal catalysis oxidation may have caused the degradation of certain fatty acids (p < .05) in the study. Mean concentrations of micro-elements (Fe, Cr, Mn, and Ni) in all PEF-treated samples were within the permissible limit of heavy metals according to the USFDA drinking water quality standard. Practical applications PEF is an emerging alternative pasteurizing method, when applied correctly could prolong the shelf-life, while lessening the detrimental impacts on the organoleptic properties of goat milk. The results show that pasteurization via monopolar PEF can be recommended to enhance the quality of goat milk at the industry level.

ELECTROMAGNETIC SAFETY OF WORKPLACES EQUIPPED WITH COMPUTER HARDWARE

Methods and means of electromagnetic safety examination of automated workstations equipped with computer hardware are considered. National and international standards as well as the tools necessary for the examination are presented. The results of measuring the levels of electric field strength E, V/m, and magnetic flux density B, nT, at frequencies 5 Hz...2 kHz and 2...400 kHz in two office premises are discussed. It is established that there is an excess of safety standards for computer hardware in both rooms, as well as an increased level of general technogenic background frequencies of 5 Hz...2 kHz. Consideration of uncertainty of the measurement results by the method prescribed by the new normative documents confirms the made conclusions. The most probable reason for the established excess is the shortcomings in the installation of elements of the local area network connecting automated workstations. It is planned to continue the research involving students as part of the «Safe Computer» volunteer project.