Characteristics Of Electromagnetic Radiation Research Articles

Effects of rock pore and micromorphology on electromagnetic radiation characteristics

Electromagnetic radiation (EMR) is a crucial tool for monitoring and early warning of underground engineering disasters. Investigating the inherent pore characteristics of rocks is essential for a comprehensive understanding of the EMR phenomenon. The EMR was monitored during various types of rock splitting failures. The pore structure and micromorphology of rocks are studied using quantitative methods such as mercury intrusion porosimetry, fractal analysis, and the Gray Level Co-occurrence Matrix (GLCM). Results indicate that the fractal dimension of red sandstone is significantly lower than the other three rocks. The fractal complexity increases sequentially from red sandstone to marble, granite, and limestone. As the fractal dimension decreases, the signal waveform characteristics of the four rocks become more complex before the main fracture, with a significant increase in signals during the compaction and elasticity stages. Higher fractal dimensions lead to a shift in energy and count from elasticity stage to the post-peak stage. The main fracture amplitudes of the four rocks generally exhibited a consistent pattern, following the sequence of granite > marble > limestone > red sandstone. The main fracture amplitude decreases with increasing complexity of the rock's pore micromorphology. Rock pore characteristics affect frequency domain characteristics by influencing rock strength and crack expansion. An increase in the average pore diameter tends to decrease both the main and center frequencies.

Mathematical Modeling of Refraction Characteristics of Electromagnetic Radiation at Stochastic Gravitational Field

Numerical-analytical modeling is used for estimation of gravitational noise influence on propagation of electromagnetic radiation at gravitational field of a group of astrophysical objects. The method bases on numerical integrate of system of light differential equations in the Euler’s form, added differential equations for calculation of statistic moments of side fluctuations of light at a picture plane of observer. The influence of gravitation was taken into account by introducing of the effective refraction index of vacuum, expressed through a gravitational potential. Visions about spatial correlation function of inhomogeneities of effective refraction index of vacuum are used as model. Calculating of gravitation effects of group astrophysical objects are performed under assumption additive contribution of field of every objects in general gravitational field. Modeling of the refraction characteristics of electromagnetic radiation is performed for a various configurations of gravitation field. Results of calculating are shown at a picture plane of observer. The blurring effects of gravitational lensing are investigated at dependence from position of localized area of gravitational noise and astrophysical objects. It’s showed that for case of single-component gravitational field full coverage of object by area of gravitational noise match maximum blurring of lensing effect. The features of gravitational focusing are determined at dependence from position of area noise for asymmetrical twocomponent gravitational field, where one of objects coverage by area of gravitational noise. Offered tool of modeling can be used for both investigation of gravitational lensing of multi-component gravitational field in presence variety of limited area of gravitational noise and under conditions uniform spatial distribution of stochastic gravitational inhomogeneities. Also it can use for recovering of gravitational potentials of non-radiating (hidden) objects by characteristics of received electromagnetic radiation of remote space sources.

Damage evolution, acoustic emission and electromagnetic radiation of rock under uniaxial cyclic loading

Uniaxial cyclic loading compression experiments are conducted with synchronous monitoring of acoustic emission (AE) and electromagnetic radiation (EMR). The AE and EMR characteristics of rocks during cyclic loading are analyzed. Subsequently, the Kaiser and Felicity effects of AE and EMR are disclosed. Moreover, the b-value and fractal dimension are calculated to explore the cracking mechanism of rock materials. These results show that the AE and EMR are active during the 1st and 2nd loading cycles, and sparse during the 3rd and 4th loading cycles where the AE and EMR are only generated when the stress exceeds the previous peak stress due to the Kaiser effect. In the 5th loading cycle, AE and EMR accelerate and peak at rock failure. The variation of EMR-based FR is consistent with that for AE under cyclic loading. Hence, the FR associated with EMR is also well correlated with stress memory. The AE and EMR-based FR is greater than 1 in the 2nd-4th loading cycles, and less than 1 in the 5th cycle, indicating that FR can be used to reflect the damage evolution of rocks. The b-value and fractal dimension increase in the 1st-4th loading cycles, and turn to decrease in the 5th loading cycle. This pattern serves as a precursor to identify the rock failure.

Deep neural network‐based infinitesimal dipole modeling using either near or far electric‐field

AbstractThis paper presents the deep neural network‐based infinitesimal dipole model using either near‐ or far‐field radiation patterns. Based on the radiating characteristic of an infinitesimal dipole, we generated a data set including near and far field radiation patterns corresponding to the phases of infinitesimal dipoles. We used the data set to train and validate the deep neural network (DNN) model. After checking the statistic of the fit function and the average error in expecting the phases of the infinite dipoles, we conclude that the proposed infinitesimal dipole modeling using DNN is sufficient to predict the characteristics of electromagnetic radiation.

Characteristics of electromagnetic radiation of the veterinary physiotherapy device UMI-05-V

We studied some physical characteristics of the veterinary physiotherapeutic device UMI-V-05. The magnetic induction at different power levels was determined using TPU 02 militeslameter. The magnetic induction was measured for each power value. The probe of the milliteslameter was placed directly on the working surface, in the center of the inductor. It was found that the minimum magnetic induction of the device is 350±6.0 mTl, and the maximum is 1058±10.0 mTl. During the device operation, the heating of the inductor was determined using a thermal imager and a stopwatch. During the recommended time range (10 minutes), the inductor temperature did not exceed 46 °C. Determination of the pulse radiation frequency depending on the magnetic induction value was carried out using a stopwatch. At each working power the number of pulses per minute was counted and the number of pulses per second was calculated (frequency determination). It was revealed that UMI-V-05 is a low-frequency source of pulsed magnetic radiation with the maximum frequency of 1.3 Hz at the minimum magnetic induction of 350±6.0 mTl and the minimum frequency of 0.1 Hz at the maximum magnetic induction of 1058±10.0 mTl. Using a ruler and a TPU 02 milliteslameter, the degree of magnetic pulse attenuation depending on the distance to the working surface of UMI-V-05 was determined, it was fixed that the value of magnetic induction varies inversely proportional to the distance from the inductor. The penetration ability of the electromagnetic pulse through different media: biological and non-biological using TPU 02 militeslameter was studied. Biological tissues (muscle, bone) and some nonbiological media (paper, glass, wood, polyethylene, water) do not affect the passage of the electromagnetic pulse, while steel significantly reduces the passage of the pulse.

Simulation and Suppression Measure Analysis of Electromagnetic Radiation Interference Due to Frequency Converters in Coal Mines

Nowadays, due to their characteristics of high efficiency and energy saving, frequency converters are used in coal mine excavation machines and ventilation machines. They can cause serious electromagnetic radiation interference with the surrounding monitoring, sensing and other equipment. Therefore, it is necessary to explore the electromagnetic interference characteristics of mining converters. By choosing a ZJT-75/660SF mine frequency converter as the research object, an antenna model was established, and the method of moments was used to solve the problem. The electromagnetic radiation characteristics of the frequency converter were analyzed, and a field experiment was conducted to verify the effectiveness of the model by comparing the simulation and experimental data. According to the analysis of the electromagnetic intensity distribution characteristics of the near field and far field, the near-field intensity is concentrated in the inner part of the converter, but the far-field intensity has obvious directional characteristics, which are found to provide a reference value for the location of the underground mining converter. Finally, a method is proposed to improve electromagnetic radiation disturbance by changing the structure of the converter’s heat dissipation hole, and the feasibility of this method is verified.

A Study on the Time-Frequency Characteristics of Electromagnetic Radiation Signals during Concrete Cracking

At the moment of rupture, brittle materials such as concrete, coal, and rocks experience a sudden stress change that generates oscillating positive and negative charges on the crack surfaces, resulting in the emission of electromagnetic radiation (EMR) signals. While extensive investigations have focused on the EMR signals produced during the fracturing of coal and rocks, limited attention has been given to the signals arising from concrete cracking. Previous studies have predominantly concentrated on amplitude or frequency domain analysis, lacking a comprehensive exploration of the time-frequency domain characteristics of electromagnetic signals. In this study, various magnetic field sensors capable of collecting frequencies ranging from 50Hz to 50kHz are developed. A laboratory testing platform for concrete cracking is established with the utilization of data acquisition equipment and a rock point load tester. The EMR signals are subjected to time-frequency domain analysis using Short-Time Fourier Transform (STFT) methods. The study explores the relationship between the time-frequency domain characteristics of EMR signals and concrete dimensions, as well as the instantaneous stress drop at the moment of fracture. Experimental findings reveal that the dominant frequency of EMR signals generated during concrete cracking is in the low-frequency range. As the instantaneous stress drop at the moment of fracture increases, the frequency of the EMR signals shifts towards higher frequencies and the signals around 10kHz has a longer duration. When the frequency of EMR signals is lower than 20kHz, larger concrete dimensions result in greater stress drops at the moment of fracture, leading to higher intensity EMR signals. Utilizing the EMR characteristics of concrete cracking holds promise for monitoring the safety and stability of concrete structures.

An Efficient MLFMA for Accurately Analyzing Electromagnetic Radiation and Coupling Characteristics of Large-scale Antenna Arrays Mounted on Platform

A multilevel fast multipole algorithm (MLFMA) for analyzing electromagnetic radiation and coupling characteristics of large-scale antenna arrays mounted on the platforms is presented in this paper. Compared with the method of moments (MoM), the MLFMA can be used to calculate larger scale problems with limited resources. First, waveport model of the MLFMA based on the equivalence principle and mode matching theory is established to efficiently and accurately simulate the antenna array. Then, a preconditioning approach for solving the radiation problems with the waveports is designed to improve convergence of the MLFMA. An initial guess construction method is proposed to accelerate the MLFMA computation for the multi-excitation problems, which can reduce the iteration time by at least 50%. Numerical results demonstrate accuracy and efficiency of the proposed method.

High-Q quasi-bound states in the continuum in C2-symmetric metasurface with enhanced second harmonic generation in two-dimensional materials

Quasi-bound states in the continuum (Quasi-BIC) possess a high quality-factor (Q-factor) that can amplify local electromagnetic fields and nonlinear effects such as second harmonic generation (SHG). In this paper, we propose a silicon metasurface with C2 symmetry. By tuning the structural parameters without breaking the C2 symmetry, three symmetric protected BICs (SP-BICs) are transformed into sharp quasi-BICs dominated by different modes in the nearinfrared spectrum. The quasi-BICs exhibit Q-factors as high as 10370 in C2 symmetric metasurface. Numerical simulations reveal that the toroidal dipole (TD) and magnetic dipole (MD) enhance intercellular coupling and local electromagnetic fields, laying the foundation for generating metasurface with high Q-factor. Furthermore, the longitudinal radiative component of electric quadrupole (EQ) outside the facet promotes enhanced light interaction with the 2D material. Leveraging the robust local electromagnetic fields and radiation characteristics of these quasi-BICs, we have achieved substantial SHG enhancement across multiple wavelengths under continuous wave (CW) operation. The SHG from 2D GaSe flake reaches 14189-fold enhancement. Our results not only offer insights into designing metasurface structures with high Q-factors but also explore the methods of enhancing the interaction between metasurface and 2D materials. The proposed nanostructure has numerous potential applications in nonlinear optics, optoelectronics and signal processing.

ANALYSIS OF THE FACTORS CONTRIBUTING TO ENVIRONMENTAL POLLUTION IN THE SUBCARPATHIAN PROVINCE

The work presents an examination of Poland's environmental condition, with a focus on the contamination of air and surface waters by various chemical elements. The composition and quality of the air impact ecosystems, plant growth, the animal kingdom, and shape human living conditions. These factors play a significant role in driving global climate change. The repercussions of air pollution encompass phenomena such as smog, acid rain, ozone layer depletion, as well as impacts on industrial and municipal facilities, contributing to global warming. The article conducts an analysis of air pollution, surface water contamination, and electromagnetic radiation pollution in Subcarpathian, utilizing the city of Stalowa Wola and the Stalowa Wola county as case studies. This choice is informed by the fact that Stalowa Wola stands as one of the largest industrial cities in the Subcarpathian Voivodeship, suggesting that environmental pollution levels in this county might surpass those in other regions. The article also delineates the features of air and surface water pollution, along with electromagnetic radiation characteristics. It scrutinizes pollution sources in the mentioned county, explicates the causes of such pollution, and proposes strategies for environmental amelioration. The analysis of the environmental status of Stalowa Wola county during the years 2018 to 2020 is presented, accompanied by recommendations for initiatives that could enhance its condition. The research findings indicate that the condition of uniform segments of surface waters, as evaluated through conducted studies, is deemed poor. The discharge of wastewater from specific pollution points, particularly wastewater from municipal origins, emerges as the predominant cause of subpar water quality.

Characteristics of Electromagnetic Radiation from Quartz, Lithium Niobate, and Polymethyl Methacrylate Samples Subjected to Impact Loading

Characteristics of Electromagnetic Radiation from Quartz, Lithium Niobate, and Polymethyl Methacrylate Samples Subjected to Impact Loading

A study on the ambient electromagnetic radiation level of 5G base stations in typical scenarios

Knowledge of the electromagnetic radiation characteristics of 5G base stations under different circumstances is useful for risk prevention, assessment, and management. This paper selects several typical scenes (Open spaces, building concentration areas, user and building intensive areas) for electromagnetic radiation monitoring, and analyzes the relationship between ambient radiated power density and base station background. The results show that the factors that have significant impacts on the environmental radiation power density of 5G base stations including transmission distance, base station distribution, user density, building reflection superposition and so on. The radiation energy decays rapidly with distance. When the density of the building distribution is too large, the superposition effect caused by the reflected wave is concentrated at the distance of 50-70 meters. When the user density decreases (the superposition effect of reflected waves decreases), the 5G monitoring value follows the direct wave attenuation law and decreases rapidly with the increase of distance. Points with higher measured radiation in the simple access condition also had higher measured radiation in the high-speed download condition. With the popularization of 5G mobile phones and the increase of user density, the resource utilization of a single user will decline to the normal operation state, and the radiation environmental impact will be further reduced.

Essentials of Theranostics: A Guide for Physicians and Medical Physicists.

Radiopharmaceutical therapies (RPTs) are gaining increased interest with the recent emergence of novel safe and effective theranostic agents, improving outcomes for thousands of patients. The term theranostics refers to the use of diagnostic and therapeutic agents that share the same molecular target; a major step toward precision medicine, especially for oncologic applications. The authors dissect the fundamentals of theranostics in nuclear medicine. First, they explain the radioactive decay schemes and the characteristics of emitted electromagnetic radiation used for imaging, as well as particles used for therapeutic purposes, followed by the interaction of the different types of radiation with tissue. These concepts directly apply to clinical RPTs and play a major role in the efficacy and toxicity profile of different radiopharmaceutical agents. Personalized dosimetry is a powerful tool that can help estimate patient-specific absorbed doses, in tumors as well as normal organs. Dosimetry in RPT is an area of active investigation, as most of what we know about the relationship between delivered dose and tissue damage is extrapolated from external-beam radiation therapy; more research is needed to understand this relationship as it pertains to RPTs. Tumor heterogeneity is increasingly recognized as an important prognostic factor. Novel molecular imaging agents, often in combination with fluorine 18-fluorodeoxyglucose, are crucial for assessment of target expression in the tumor and potential hypermetabolic disease that may lack the molecular target expression. ©RSNA, 2023 Test Your Knowledge questions are available in the supplemental material.

Ni–Fe alloy soft magnetic protective coating of new energy vehicles and the internal electromagnetic radiation characteristics

Ni–Fe alloy soft magnetic protective coating of new energy vehicles and the internal electromagnetic radiation characteristics

Electrical properties and electromagnetic radiation characteristics of cement/Ba0.06Bi0.47Na0.47TiO3 composites

Electrical properties and electromagnetic radiation characteristics of cement/Ba0.06Bi0.47Na0.47TiO3 composites

Exploring the impact of varying notch-width ratios on electromagnetic radiation parameters at tensile fracture of C35000 brass

The paper discusses experimental research to analyze how the notch-width ratio (2a/w) impacts Electromagnetic Radiation (EMR) emission parameters at tensile fracture in C35000 brass. The EMR emission signals during tensile fracture were captured using a copper chip antenna and stored in an oscilloscope for further analysis. The EMR parameters and mechanical parameters at fracture showed a smooth correlation. Investigating the association between the EMR parameters and the plastic zone radius formed before the crack tip may help develop an innovative tool for crack growth monitoring. The interrelation between the EMR energy release rate and the Elastic strain energy release rate may help create an innovative method for assessing fracture toughness, a fundamental property of metallic materials. The EMR energy release rate exhibited a parabolic relationship with an analytical correlation of stacking fault energy. Field emission scanning electron microscopy (FESEM) examined the fractured specimen's microstructure. A thorough examination of the relationship between dislocations, EMR characteristics, and real-time applications could be a novel technique for understanding material behaviour in detail.

Research on the Influence of Pantograph Catenary Contact Loss Arcs and Zero-Crossing Stage on Electromagnetic Disturbance in High-Speed Railway

During train travel, various factors, such as body vibration, uneven contact lines, and hard spots on carbon sliding plates and over electric neutral zones, often lead to brief separation between the pantograph and the contact line, i.e., the pantograph catenary contact loss phenomenon. With the continuous increase in train speed and traction power, the probability of pantograph catenary contact loss occurrences rises with a gradual increase in the energy of electromagnetic radiation, making the pantograph catenary arc a primary source of interference affecting the electromagnetic safety of high-speed railways. Understanding the mechanism, characteristics, and influencing factors of electromagnetic interference caused by pantograph catenary contact loss discharges is of utmost importance for analyzing and resolving on-site equipment interference faults. Our analysis of the physical process of pantograph catenary contact loss reveals that when the distance between the pantograph and catenary is significant and the duration is lengthy, high-voltage breakdown occurs within the pantograph catenary gap as it comes close again after the complete extinguishing of the arc. To investigate the electromagnetic radiation characteristics resulting from high-voltage breakdown discharge arcs in the pantograph catenary contact loss process, we established a laboratory test platform for assessing the electromagnetic disturbance characteristics of high-voltage pantograph discharge. We designed a test procedure utilizing fixed-gap breakdown discharge to evaluate the impact of the arc zero-crossing stage on electromagnetic radiation disturbances. Our research indicates that when the pantograph catenary spacing remains constant, an increase in voltage level leads to an elevation in the current within the discharge circuit, resulting in an increased intensity of impulse radiation generated during pantograph catenary contact loss events. During the moment of gap breakdown, the antenna records the highest amplitude of electromagnetic radiation. Also, during the steady-state arc ignition phase of the pantograph catenary gap, the zero-crossing stage generates pulsed discharge currents within the circuit, accompanied by substantial electromagnetic radiation. As the arc current increases, the zero-crossing time shortens, and the pulse current during the zero-crossing process decreases, accompanied by a reduction in the excited electromagnetic radiation. These observations reveal novel characteristics of electromagnetic radiation disturbances during steady-state arc ignition. The outcomes of our study provide valuable insights that can contribute to our understanding of the characteristics and influencing factors of electromagnetic radiation in pantograph catenary contact loss discharges and offer theoretical guidance for the resolution of pantograph catenary contact loss interference faults.

A Study of the Characteristics of Micro-Seismic (ME) and Electromagnetic Radiation (EMR) Signals under the Static Load Conditions of Rocks

Geological hazards, such as the frequent occurrence of rock bursts in deep mining, emphasize the critical necessity for the early warning and prediction of dynamic fractures in coal and rock masses, as well as the destabilization of the surrounding rock. This study delves into the mechanisms of electromagnetic radiation (EMR) signals and their synchronous coupling with micro-seismic (ME) signals. EMR and ME signals from rock specimens were systematically collected during the uniaxial compression fracture process using a dedicated monitoring and acquisition system. Employing the wavelet analysis method, the original data underwent reconstruction and denoising, while the EMR and ME spectra, derived through fast Fourier transform, were subjected to detailed scrutiny. The comprehensive analysis unveiled that EMR signals arising from rock fractures exhibited precise timing synchronization with ME signals. Moreover, the dominant frequencies of both signals are closely aligned within the low-frequency band, indicating a remarkable degree of similarity and homology. These findings establish an experimental basis for the development of monitoring and early warning systems geared toward assessing damage to coal and rock masses using EMR and ME signals.

Investigation of mechanical behavior, AE and EMR characteristics of rocks under compression-shear loading via variable-angle shear tests

The surrounding rocks of underground engineering are usually subjected to the coupling of compressive and shear stresses. The mechanical characteristics of underground geomaterials subjected submitted to compression-shear loading have received considerable attention recently. The complex response arises from the microstructure redistribution under high in-situ stress and the resulting fracture behaviors at multiaxial stress states. Understanding the compression-shear behavior and failure mechanism of rocks is of essential importance for mechanical characterization and construction safety in deep underground engineering applications. In this study, variable-angle shear tests are conducted for cubic sandstone samples to investigate damage evolution under compression-shear loading, and the acoustic emission (AE) and electromagnetic radiation (EMR) are simultaneously monitored to record crack development. The mechanical behaviors of rock with AE and EMR responses in variable-angle shear tests with shear angle of 30°, 45° and 60° are analyzed. Then, correlation between AE and EMR is evaluated. Damage evolution of the rock specimen is described based on AE and EMR energy. Fractal dimension and b-value of AE and EMR time series are calculated to further reveal the microscopic crack mechanism of rocks. The results suggest that the continuous decline of fractal dimension and b-value of AE and EMR can act as the precursor of rock failure.

Statistical Characteristics of Emission from Stationary Plasma Thrusters Operating with Various Propellants

The procedure of experimental determination of statistical characteristics of own electromagnetic radiation of a laboratory mock-up of an SPT-70 stationary plasma thruster developed by the Research Institute of Applied Mechanics and Electrodynamics of the Moscow Aviation Institute is described. The study investigated the temporal complex implementation of the processes of radiation of the SPT-70 with a sampling duration of 1 ms and an analysis band of 140 MHz for characteristic central frequencies of 0.9, 1.050, 1.200, and 1.350 GHz (discharge power of 600 W, horizontal polarization) when working on various working bodies. The conducted studies allowed to obtain estimates of the statistical characteristics of the SPT-70 radiation for prospective working bodies The new results should be attributed to the fact that the obtained distribution laws for the common-phase and quadrature components of the complex envelope process of radiation differ significantly from the Gaussian one. As for the distribution of the amplitude envelope process, in general, there is a difference from the Rayleigh distribution law. In the transition from xenon to krypton, the degree of negativity and the difference from Rayleigh’s law increase. At the same time, the law of phase distribution of the complex envelope process is close to uniform and invariant to the type of working body.