Electromagnetic Balance Research Articles

Combustion-Assisted construction of Defect-Enriched hierarchical carbon composites towards efficient Low-Frequency electromagnetic wave absorption

Due to the high intrinsic conductivity of graphitized carbon-based composite materials, it induces a serious skin effect of incident electromagnetic waves, which deteriorates impedance matching and limits the wave absorption performance in the low-frequency regions. The introduction of defects can change the electrical and physical and chemical properties of carbon-based materials, affect the density of skin current, and thereby improve the overall performance of carbon-based absorbers. Therefore, it is important to develop a simple, low-cost, and fast preparation method for defect-rich structures. Herein, the defect-enriched hierarchical composites have been synthesized successfully via the soaking-burning-annealing process. The combustion treatment introduced numerous defects and oxygen vacancies while inducing a non-graphitization transition that reduced conductivity and improved electromagnetic balance in the low-frequency region. As expected, the charred sample exhibited notable enhancements in reflection loss (RL) and the effective absorption bandwidth within the low-frequency range of 2–8 GHz. The value of RL reached −52.2 dB, marking a 199 % increase over the unburned sample, while the effective absorption bandwidth increased by 28 % to 2.70 GHz. Even at a filling rate of only 10 %, the RLmin values of the optimal sample were lower than −30 dB across the S, C, X, and Ku bands. Additionally, the combination-induced defects led to phonon scattering, thereby reducing the thermal conductivity of the material. Thus, combustion can enhance the low-frequency microwave properties and thermal insulation of carbon-layered composites.

Regulating the electromagnetic balance of materials by electron transfer for enhanced electromagnetic wave absorption

The fact that single dielectric loss materials have disadvantages of excessive conductivities and impedance mismatches has given rise to a large effort to develop effective strategies to fabricate electromagnetic wave (EMW) absorbing materials comprised of components that bring about a balance between dielectric loss and magnetic loss. Moreover, little is known about the essential features that regulate EMW absorption propensities. This study focused on the development of a new EMW absorbing material and gaining information about factors that govern EMW absorption abilities. The materials at the center of the effort are light weight and porous cobalt sulfonated phthalocyanine-reduced graphene oxide (CoSPc-rGO) aerogels that were synthesized by using a simple hydrothermal method followed by freeze-drying. The properties of these materials that contribute to the electromagnetic balance between dielectric and magnetic loss were elucidated by first formulating a reasonable hypothesis about how the relative orientation of the components in CoSPc-rGO govern p-conjugation and electron transfer from rGO to CoSPc, which is proposed to be a key factor contributing to the regulation of the electromagnetic balance. Polarization relaxation process of materials was analyzed in detail using a variety of approaches including theoretical calculation, spectroscopic measurements, and experimental and simulation studies. The fabricated CoSPc-rGO aerogels that contain an ultra-low content of 4 % were found to exhibit an extraordinary microwave absorption performance associated with a strong reflection loss of -53.23 dB and a broad effective absorption bandwidth of 8.04 GHz. The results of this study should provide an effective guide for new designs of composite materials for EMW absorption.

Cell phone radiation effect on osteocalcin and bone alkaline phosphatase

Background: Electromagnetic fields are forces associated with moving electric charges and have electrical, magnetic components and contain electromagnetic energy, one of which is radio frequency (RF) energy which is commonly used in telecommunications. Cell phones are one of the RF electromagnetic radiation devices that can emit 90-2450 MHz waves and are often placed near the head. The human body works like an electromagnetic field in that each cell has its own electrical circuit characteristics. As the number of electromagnetic radiation devices in the environment increases, the electromagnetic balance in the human body may be disturbed by the magnetic waves produced by cell phones. Electromagnetic radiation is known to have the ability to induce oxidative stress, which is characterized by the accumulation of reactive oxygen species (ROS) in tissues. The accumulation of ROS in the body leads to osteoblast cell death. Osteoblasts are needed for mineralization of the extracellular matrix during bone growth. Therefore, bone growth is not optimal and can caused malocclusion. Purpose: This study aims to evaluate the relationship between electromagnetic radiation and osteocalcin and bone alkaline phosphatase (BALP) serum levels. Methods: Experimental laboratory research with a pre- and post-control group design approach was carried out on 12 Rattus norvegicus Wistar strain. Osteocalcin and BALP serum levels were calculated before and after treatment. This study used the t-test as a comparative study (p<0.05). Results: There are significant differences in osteocalcin and BALP values between the treatment groups before and after treatment. Conclusion: Cell phone radiations (electromagnetic field exposure) reduce osteocalcin and BALP serum levels.

MOF-derived Co-C composites with 3D star structure for enhanced microwave absorption

The demand of microwave absorption materials (MAMs) with unique morphologies and electromagnetic (EM) balance has become necessary in recent years. Due to the ease of synthesis and tunable structure, metal–organic frameworks (MOFs) are widely used for this special MAMs. In this study, a new three-dimensional hybrid MOF is proposed that is co-doped with six equally branched star morphologies. The Co-C composite has the same six-branched morphology as that of the precursor. When the EM wave is incident, this special structure makes it easier for the EM wave to enter the material vertically due to the expansion of the incident surface, which is effective in adjusting the transmission path of the electron and the reflection and distribution of the EM wave. Because of the special morphology and magneto-dielectric synergy, the Co-C composite shows a minimum reflection loss (RLmin) of −48.5 dB at 11.0 GHz at an absorption thickness of 3.0 mm, with a microwave absorption bandwidth (EAB) of 6.1 GHz. This research provides a practical guidance for preparing the MAMs of special star structure.

Research on Novel Electromagnetic Automatic Balancing System for High-end Mechanical Equipment

Research on Novel Electromagnetic Automatic Balancing System for High-end Mechanical Equipment

Impedance amelioration of coaxial-electrospun TiO2@Fe/C@TiO2 vesicular carbon microtubes with dielectric-magnetic synergy toward highly efficient microwave absorption

An impedance-optimized hierarchical TiO 2 @Fe/C@TiO 2 vesicular carbon microtube is constructed for the first time via coaxial electrospinning and solvothermal method. Benefit from the integration of cavities, highly dispersed magnetic nanoparticles, and dielectric coating, the impedance is effectively improved by dielectric-magnetic synergy. The unique structure simultaneously fulfills a dual-network of micron-scale magnetic interaction and charge transfer, embedding the composite with enhanced magnetic and dielectric loss. The interfacial polarization and multiple reflections further promote microwave absorption. • 1D vesicular structure was successfully constructed via coaxial electrospinning. • Structural and compositional integration progressively improved impedance. • Strong magnetic-dielectric synergy of quaternary components in this absorber. • Electron holography confirmed magnetic coupling and charge transfer dual-network. Impedance matching ( Z ) is a key issue requested by high-efficient microwave absorption materials, which remains a major challenge. Lacking magnetic loss capacity and electromagnetic impedance balance, the microwave attenuation capacity of carbon-based absorbers urgently needs to be improved. Herein, a TiO 2 @Fe/C@TiO 2 vesicular carbon microtube was reasonably constructed by coaxial electrospinning. The characteristic impedance was gradually improved by introducing cavities, magnetic Fe particles and dielectric TiO 2 coating. The composite achieves an enhanced microwave performance with a maximum reflection loss of as strong as − 60.98 dB and a broad absorption bandwidth of 4.8 GHz at only 2.0 mm thickness. Such a well-integrated hierarchically vesicular carbon microtube with a tubular porous structure endows the assembly with high magnetic anisotropy and multiple interfaces, further offers the composites: i) the dual-networks of micron-scale 1D anisotropic magnetic coupling and charge conduction, ii) dielectric-magnetic synergy of quaternary components, iii) progressively matched impedance, proved by micromagnetic simulation and electron holography. This finding might have great significance in the impedance matching control of high-performance microwave absorbents.

Target Force Curve Searching Method for Axial Electromagnetic Dynamic Balance of Scroll Compressor

In order to explore the axial electromagnetic dynamic balance force curve of a scroll compressor under the action of thermal energy, radial clearance, mechanism friction, and other factors in actual working conditions, an axial force exploration method that can automatically approach sections is proposed in this paper. Considering the dynamic response ability of the electromagnetic balance system, an automatic optimization algorithm of the partition number was proposed to find the optimal partition number in order to achieve the optimal tracking effect. An experimental platform was built to test the effect of the segmented tracking method on calibrating the deviation between the theoretical axial force curve and the real curve. The results show that the curve construction method proposed in this paper has convergence. This method can automatically and accurately construct the axial balance force curve required by the electromagnetic dynamic balance. Through the automatic optimization algorithm, the standard error (RMSE) between the target curve and the theoretical curve was reduced from 290 to 22.6, and the number of partitions with the lowest standard error was 20. The results provide a useful reference for the accurate, automatic, and efficient exploration of the actual axial sealing force of the scroll compressor.

Relationships between geomagnetic Ар-indeх and parameters of the acupuncture points as well as neuroendocrine-immune complex in patients with its dysfunction

Background. Back in 1990, YuP Limansky hypothesized acupuncture points (AP) as polymodal receptors of the ecoceptive sensitivity system. In the process of hypothesis development in 2003 an existence of separate functional system of regulation of electromagnetic balance of organism has been substantiated and a working conception of light therapy has been formulated. In line with this hypothesis, we set out to analyze the relationships between the disturbances of the geomagnetic field (Ap-index) and the electrical conductivity of a number of AP, on the one hand, and the parameters of the neuroendocrine-immune complex in patients with its dysfunction, on the other. Material and methods. The object of observation were 21 men (24-63 y) and 20 women (30-72 y) with neuroendocrine-immune complex dysfunction. Each patient was tested twice with an interval of 4 days. Retrospectively we recorded the geomagnetic Ap-Index on the day of testing and during the previous 7 days, using resource https://www.spaceweatherlive.com/. Recorded the electrical conductivity of 9 pairs of AP, electroencephalogram (EEG) and heart rate variability (HRV) parameters, determined the plasma level of cortisol, triiodothyronine and testosterone, the content of lymphocytes expressing CD3, CD4, CD25, CD8, CD22 and CD56 receptors, the serum level of circulating immune complexes, immunoglobulins classes M, G, A as well as C-reactive protein, IL-1β and IL-6. The state of phagocytic function of neutrophils estimated by microbial count and phagocytic and killing indices against Staphylococcus aureus and Escherichia coli. Results. During the week, the average level of Ap-index ranged from 7 to 13 nT. Maximum coefficients of multiple correlation with APs parameters were detected for Ap-index on 6 day before (R=0,552) and on the day of testing (R=0,470), with EEG parameters on the eve of registration (R=0,708) and on 6 day before its (R=0,685), with immunity parameters on the eve of blood sampling (R=0,768) and on 5 day before its (R=0,758), with HRV&Hormonal parameters on 2 (R=0,506) and 7 (R=0,403) days before testing. The canonical correlation between Ap-indices for 7 days before and on the day of testing, and the parameters APs is 0,661; EEG parameters is 0,886; HRV&Hormonal parameters is 0,766 and immunity parameters is 0,921. APs parameter are closely related to the EEG (R=0,997) and HRV&Hormonal parameters (R=0,740). In turn, the immune parameters are closely related to the EEG (R=0,944) and HRV&Hormonal parameters (R=0,714). Conclusion. Disturbances of the geomagnetic field (Ap-index) causes a significant immediate modulating effect on the parameters of neuroendocrine-immune complex, apparently through acupuncture points as polymodal receptors of the ecoceptive sensitivity system.

Multipurpose Flexible Positioning Device Based on Electromagnetic Balance for EVs Wireless Charging

The electric vehicles (EVs) have played an important role in people's traveling due to the clean energy and friendly environment. Considering the endurance issue of EVs, wireless charging is regarded as a convenient and effective solution. However, the charging power and the efficiency would be greatly affected when the transmitting coil (TC) and the receiving coils are nonaligned. In this article, we present a flexible and high-accuracy positioning device based on electromagnetic balance, which could automatically achieve wireless charging and two-level positioning without communication between TC and EVs during the location. Besides, a six-coil cross-coupled circuit model has been built to optimize the key parameters that affect the positioning accuracy. The theoretical analysis and experimental results show that the proposed structures and location method have certain advantages in positioning accuracy, operation complexity, and practicability. Within the range of first-level positioning, the accuracy could achieve 1 cm. There is a high fitting performance between the simulation and experimental results, which verify the correctness of the theoretical analysis and the validity of the structures. Moreover, an additional comparative experiment has been designed to verify the correctness of the proposed method used in the wireless charging positioning system with ferrite cores and a magnetic shielding layer.

Cathode Spot Velocity of Atmospheric Arc Plasma after Arc Ignition Affected by Self and External Electromagnetic Force between Parallel Electrodes Using 3D Numerical Simulation

For visually and quantitatively elucidating the contribution of self and external electromagnetic forces of the cathode spot area to the cathode spot movement, a three‐dimensional electromagnetic thermal fluid simulation program was used to simulate the arc movement between parallel electrodes. According to the analysis results, the cathode spot first step occurred when the electromagnetic force balance of cathode spot area was broken, and the direction of total electromagnetic force at the right side control volume pointed forward. When the current path changes from straight to reentry model, the cathode spot movement became faster because of the self electromagnetic force derived from electrodes. The rapid of cathode spot first step significantly increased along with the arc current increasing, and the increment of self electromagnetic force was more significant than the external electromagnetic force. In conclusion, the application of external magnetic field or the self magnetic field derived from the parallel electrodes benefit to break the electromagnetic force balance of cathode spot area and promote the rapid of cathode spot first step. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Modelling of a miniature microwave driven nitrogen plasma jet and comparison to measurements

The MMWICP (miniature microwave ICP) is a new plasma source using the induction principle. Recently Klute et al presented a mathematical model for the electromagnetic fields and power balance of the new device. In this work the electromagnetic model is coupled with a global chemistry model for nitrogen, based on the chemical reaction set of Thorsteinsson and Gudmundsson and customized for the geometry of the MMWICP. The combined model delivers a quantitative description for a non-thermal plasma at a pressure of p = 1000 Pa and a gas temperature of T g = 650–1600 K. Comparison with published experimental data shows a good agreement for the volume averaged plasma parameters at high power, for the spatial distribution of the discharge and for the microwave measurements. Furthermore, the balance of capacitive and inductive coupling in the absorbed power is analyzed. This leads to the interpretation of the discharge regime at an electron density of n e ≈ 6.4 × 1018 m−3 as E/H-hybridmode with an capacitive and inductive component.

Effects of Nonpharmacological Interventions on Balance Function in Patients with Osteoporosis or Osteopenia: A Network Meta-Analysis of Randomized Controlled Trials.

Objective To evaluate the clinical efficacy of nonpharmacological interventions in improving balance function of patients with osteoporosis or osteopenia using network meta-analysis (NMA). Methods We searched seven databases (PubMed, the Cochrane Library, Embase, CKNI, Wanfang Data, VIP, and CBM) for relevant randomized controlled trials (RCTs) up to August 31, 2020. Berg Balance Scale (BBS) and Time Up and Go Test (TUGT) were used as outcome measures. Two researchers independently screened studies, collected data from the studies, and estimated risk of study bias. Divergence in the evaluation process was settled by consulting a third researcher. We used Stata 15.1 software for network meta-analysis (NMA). Results We identified 10 eligible RCTs, with a total of 737 patients and four intervention methods, including traditional Chinese medicine (TCM) exercises, pulsed electromagnetic fields (PEMFs), strength training, and balance and strength training. The results revealed that all nonpharmacological interventions could improve balance function, but the effect of balance and strength training was better than other interventions. Conclusion Exercise can significantly improve the balance function of patients with osteoporosis and osteopenia, and balance combined with strength training has the best effect, followed by TCM exercises.

Revisiting the limits of photon momentum based optical power measurement method, employing the case of multi-reflected laser beam

In this work, we review the viability and precision of the photon-momentum-based optical power measurement method that employs an amplification effect caused by a multi-reflected laser beam trapped in an optical cavity. Measuring the total momentum transfer of the absorbed and re-emitted photons from a highly reflective surface (reflection of the laser beam from an optical mirror) as a force provides the possibility of measuring the optical power with direct traceability to SI units. Trial measurements were performed at two different metrology laboratories: the laboratory for mass/force at the Technical University of Ilmenau, and the clean room laser radiometry laboratory at PTB, with a portable force measurement setup consisting of two electromagnetic force compensation balances. We compared the results of the optical power measurements performed with the force measurement setup, via the photon-momentum-based method, with those performed using a calibrated reference standard detector traceable to PTB’s primary standard for optical power, the cryogenic radiometer. The comparison was carried out for an optical power range between 1 W and 10 W at a wavelength of 532 nm, which corresponds to a force of approximately 2000 nN at the upper limit, yielding approximately 2.3% relative standard uncertainty in the case of 33 reflections. Thus, conflating the high-precision force metrology technique at μN to nN levels with the optical setup required to achieve specular multi-reflection configuration of the laser beam, where a macroscopic optical cavity with ultra-high reflective mirrors (>99.995%) can adjustably be suspended from the force sensors, depending on required geometry of reflections, we show that the uncertainty of the optical power measurements upon further increase of the nominally applied optical power, the number of laser beam reflections, or the reflectivity coefficient of the mirrors can be markedly reduced.

Analytical Solution of Magnetically Dominated Astrophysical Jets and Winds: Jet Launching, Acceleration, and Collimation

Abstract We present an analytical solution of a highly magnetized jet/wind flow. The left side of the general force-free jet/wind equation (the “pulsar” equation) is separated into a rotating and a nonrotating term. The two equations with either term can be solved analytically, and the two solutions match each other very well. Therefore, we obtain a general approximate solution of a magnetically dominated jet/wind, which covers from the nonrelativistic to relativistic regimes, with the drift velocity well matching the cold plasma velocity. The acceleration of a jet includes three stages. (1) The jet flow is located within the Alfvén critical surface (i.e., the light cylinder), has a nonrelativistic speed, and is dominated by toroidal motion. (2) The jet is beyond the Alfvén critical surface where the flow is dominated by poloidal motion and becomes relativistic. The total velocity in these two stages follows the same law vΓ = ΩR. (3) The evolution law is replaced by , where θ is the half-opening angle of the jet and 0 ≤ ν ≤ 2 is a free parameter determined by the magnetic field configuration. This is because the earlier efficient acceleration finally breaks the causality connection between different parts in the jet, preventing a global solution. The jet has to carry local charges and currents to support an electromagnetic balance. This approximate solution is consistent with known theoretical results and numerical simulations, and it is more convenient to directly compare with observations. This theory may be used to constrain the spin of black holes in astrophysical jets.

Generation of static and dynamic small calibration forces and their measurements by electromagnetic force compensation balance

The paper presents some of the results of the static and dynamic force measurements at 100 nN to sub-10 µN ranges which are generated due the photon-momentum. The force sensor with resolution about 20 nN and operating in differential measurement mode is developed by two electromagnetic force compensation balances. In order to generate these calibration forces, CW lasers with different operational modes, power levels, and wavelengths are used. Multi-reflection configuration of the laser beam inside the macroscopic cavity with highly reflective mirrors are used to test and variate the total amount of the forces.

Development of special measuring tool for trace of micro force value

This paper introduces the development of the special traceability measuring tool for microforce value with the test force range of 0.009807 N ~ 9.807 N (1 gf ~ 1 kgf) and the accuracy of better than ± 0.1 %, including the selection of the electromagnetic balance module, the design of the hardware structure, and the compilation of the software program. Finally, the special traceability measuring tool integrating the test measurement, automatic data collection and automatic data processing is realized, and the test verification result is given. It provides a method to solve the problem of trace the small force value of existing micro Vickers hardness tester and Knoop hardness tester.

Electromagnetic port boundary conditions: Topological and variational perspective

AbstractWe present a comprehensive and variational approach to the coupling of electromagnetic field models with circuit‐type models. That coupling relies on integral nonlocal quantities like voltage and current for electric ports, magnetomotive force, and magnetic flux for magnetic ports, and linked currents and fluxes for “tunnels” in the field domain. These quantities are closely linked to nonbounding cycles studied in algebraic topology and they respect electromagnetic power balance laws. We obtain two dual variational formulations, called E‐based and H‐based, which provide a foundation for finite‐element Galerkin discretization.

Application and uncertainty analysis of a balance weighing system used in natural gas primary standard up to 60 bar

A new 3-ton balance weighing system was designed and built up for a high level mass-time primary standard of natural gas up to 60 bar in CVB. The system is composed of a 3-ton electromagnetic balance, two tanks with thermal isolation, two platforms, two roller guide rails and two big weights which are used for special test. To achieve a lower uncertainty and the security application in natural gas measurement, several special methods were used in the system. Firstly, the tanks and platforms can be moved together steadily on the roller guide rail to be connected with pipeline system or to be weighted by the balance which also reduces the pipeline length between tanks and pipeline system. Secondly, the substitute weighing method is used for high accurate weighing. Finally, the whole system is located in a thermal isolated room with temperature and humidity controlling. Technical details, performance tests, uncertainty analysis and the future improvement ideas of the balance system are presented in the paper. The uncertainty analysis shows that the mass measurement uncertainty of gas can achieve less than 1.0g and the maximum relative standard uncertainty of natural gas mass measurement would be no more than 0.022%.

Electromagnetic Field Energy Balance for Dispersive Medium

In this paper electromagnetic field energy balance equation for linear homogeneous dispersive stationary medium is deduced in general form. No dispersive limitations on e′, e″, μ′, and μ″ are used. Thus the following question is answered: why do existing equations not provide correct values for accumulated energy and dissipated energy in dispersive media? An electromagnetic field energy balance equation for harmonic processes is obtained. This equation separates into active energy and reactive energy equations. Each of these equations contains four terms. For active energy equation the first two terms determine dissipation energy per unit volume. Each of these two terms can be expressed as a sum of three terms: the first one determines dissipation energy for unit volume without dispersion; the other two terms describe dissipation energy density due to dispersion. The third term is a Poynting vector real part change rate for frequency and coordinate, the last term—determines external source active energy density. The first two terms for reactive energy determine electromagnetic field accumulated energy density per unit volume. Each of these two terms of electromagnetic field accumulated energy density can be expressed as a sum of three terms: the first one determines accumulated energy for unit volume without dispersion; the other two terms are accumulated energy additions due to dispersion. The third term is a Poynting vector imaginary part change rate for frequency and coordinate. The last term—determines external source reactive energy density. Presented electromagnetic field energy characteristics definitions satisfy the second law of thermodynamics.

Design of Control System Based on Electromagnetic Balance Vehicle

This paper introduces the design of control system of electromagnetic balance vehicle based on kea128. From two aspects of hardware and software, the control system is designed. The hardware layer includes micro controller, vehicle model attitude measurement and road information recognition module. According to the collected information, combined with filtering algorithm and closed-loop control of upright, speed, direction, etc., through repeated practice verification, the balance car can achieve independent tracking, and can maintain upright state under different track elements, fast and stable operation.