Electromagnetic Frequency Research Articles

Research on Electromagnetic NDE Inspection Method for Broken Wire of PCCP

预应力钢筒混凝土管(Pre-stressed Concrete Cylinder Pipe, PCCP)作为一种新型的输水管材，被广泛应用于水利工程。在PCCP运行过程中，环境腐蚀或操作不当会导致管内高强钢丝的腐蚀或断裂，进而导致泄漏、爆管等事故。目前国内外普遍采用电磁涡流检测技术，对PCCP的断丝与金属管壁健康状态进行无损检测，检测系统在管内运行并配合计程轮等工具实现断丝位置的定位。本文针对国内外两种常用的PCCP断丝电磁检测技术，即远场涡流检测方法和正交电磁检测方法，建立了简化分析模型，并给出了等效交流电路，通过仿真分析验证了模型的正确性。分析了电磁检测频率的选取原则，建议选取23 Hz作为检测频率。给出了电磁检测系统的设计与实现，并经过了管道断丝试验验证，有效提取了故障特征。 Pre-stressed Concrete Cylinder Pipe (PCCP), as a new type of pipeline for water delivery, has been widely used in water conservancy projects. During the operation of PCCP, environmental corrosion or improper operation will lead to corrosion or fracture of high-strength steel wire in the pipe, resulting in leakage, explosion and other accidents. Currently some nondestructive methods, such as electromagnetic eddy current inspection method, are widely used to test the broken wire and assess the health PCCP, and equipped with a counting-wheel or other tools to achieve the localization of broken wires. This paper presents a simple model of two famous electromagnetic detection technologies for PCCP broken wire, i.e. the remote field eddy current testing method and orthogonal electromagnetic detection method. Also the equivalent AC circuit is given. By simulation analysis the simple model is verified. The selection principle of electromagnetic detection frequency is analyzed, and 23 Hz is selected as the detection frequency. The design and implementation of the electromagnetic detection system are given, and the fault characteristics are effectively extracted through the broken wire tests.

Effects of pulsed electromagnetic field therapy at different frequencies and durations on rotator cuff tendon-to-bone healing in a rat model

Rotator cuff tears affect millions of individuals each year, often requiring surgical intervention. However, repair failure remains common. We have previously shown that pulsed electromagnetic field (PEMF) therapy improved tendon-to-bone healing in a rat rotator cuff model. The purpose of this study was to determine the influence of both PEMF frequency and exposure time on rotator cuff healing. Two hundred ten Sprague-Dawley rats underwent acute bilateral supraspinatus injury and repair followed by either Physio-Stim PEMF or high-frequency PEMF therapy for 1, 3, or 6 hours daily. Control animals did not receive PEMF therapy. Mechanical and histologic properties were assessed at 4, 8, and 16 weeks. Improvements in different mechanical properties at various endpoints were identified for all treatment modalities when compared with untreated animals, regardless of PEMF frequency or duration. Of note, 1 hour of Physio-Stim treatment showed significant improvements in tendon mechanical properties across all time points, including increases in both modulus and stiffness as early as 4 weeks. Collagen organization improved for several of the treatment groups compared with controls. In addition, improvements in type I collagen and fibronectin expression were identified with PEMF treatment. An important finding was that no adverse effects were identified in any mechanical or histologic property. Overall, our results suggest that PEMF therapy has a positive effect on rat rotator cuff healing for each electromagnetic fundamental pulse frequency and treatment duration tested in this study.

Effects of Crucible Size and Electromagnetic Frequency on Flow During Fabrication of Semisolid A356 Al Alloy Slurry

Effects of Crucible Size and Electromagnetic Frequency on Flow During Fabrication of Semisolid A356 Al Alloy Slurry

The application of a high-order discontinuous Galerkin time-domain method for the computation of electromagnetic resonant modes

• A high-order discontinuous time-domain method is presented for computing resonant frequencies and modes. • The method incorporates the exact boundary representation of the computational domain given by a CAD model. • The results demonstrates that the rate of convergence can be affected by an inaccurate geometric description. • The method is able to provide a broad band of resonant frequencies for two and three dimensional cavities. This work presents a highly accurate and efficient methodology for the computation of electromagnetic resonant frequencies and their associated modes in cavities. The proposed technique consists of a high–order discontinuous Galerkin time-domain solver combined with a signal processing algorithm for extracting the frequency content. The methodology is capable of incorporating the CAD boundary representation of the domain. The numerical results demonstrate that incorporating the exact boundary representation results in a improved convergence rate, a phenomenon that has not been previously reported. Several numerical examples in two and three dimensions show the potential of the proposed technique for cavities filled with non-dispersive or dispersive media.

Limitations of the effective field approximation for fluid modeling of high frequency discharges in atmospheric pressure air: Application in resonant structures

We study analytically and demonstrate numerically that the local effective field approximation (LEFA) for plasma fluid modeling of high-frequency (GHz-THz) discharges in atmospheric pressure air is not valid in regions where the time scale for electron energy transfer to heavy particles is less than the time-period of the electromagnetic (EM) wave. Greater than 50% modulation of the electron temperature around its mean value is found for frequencies around and under 10 GHz for atmospheric pressure air discharges. This modulation decreases significantly as the EM wave frequency increases. Fully coupled numerical simulation of a resonant metallic cut-array illuminated by high frequency EM waves demonstrates that the LEFA can lead to significant errors on both temporal and spatial evolution of the plasma, in cases where this modulation is significant. The LEFA for high pressure air discharges is found to be valid when the EM wave frequency is around or higher than 100 GHz. For lower frequencies or when the reduced electric fields are high enough, the Local Energy Approximation should be used for an accurate description of the plasma development. For low gas pressures, the modulation is very low rendering the LEFA valid over a large EM wave frequency range.

Bio-soliton model that predicts non-thermal electromagnetic frequency bands, that either stabilize or destabilize living cells

ABSTRACTSolitons, as self-reinforcing solitary waves, interact with complex biological phenomena such as cellular self-organization. A soliton model is able to describe a spectrum of electromagnetism modalities that can be applied to understand the physical principles of biological effects in living cells, as caused by endogenous and exogenous electromagnetic fields and is compatible with quantum coherence. A bio-soliton model is proposed, that enables to predict which eigen-frequencies of non-thermal electromagnetic waves are life-sustaining and which are, in contrast, detrimental for living cells. The particular effects are exerted by a range of electromagnetic wave eigen-frequencies of one-tenth of a Hertz till Peta Hertz that show a pattern of 12 bands, and can be positioned on an acoustic reference frequency scale. The model was substantiated by a meta-analysis of 240 published articles of biological electromagnetic experiments, in which a spectrum of non-thermal electromagnetic waves were exposed to living cells and intact organisms. These data support the concept of coherent quantized electromagnetic states in living organisms and the theories of Fröhlich, Davydov and Pang. It is envisioned that a rational control of shape by soliton-waves and related to a morphogenetic field and parametric resonance provides positional information and cues to regulate organism-wide systems properties like anatomy, control of reproduction and repair.

Numerical electromagnetic frequency domain analysis with discrete exterior calculus

In this paper, we perform a numerical analysis in frequency domain for various electromagnetic problems based on discrete exterior calculus (DEC) with an arbitrary 2-D triangular or 3-D tetrahedral mesh. We formulate the governing equations in terms of DEC for 3-D and 2-D inhomogeneous structures, and also show that the charge continuity relation is naturally satisfied. Then we introduce a general construction for signed dual volume to incorporate material information and take into account the case when circumcenters fall outside triangles or tetrahedrons, which may lead to negative dual volume without Delaunay triangulation. Then we examine the boundary terms induced by the dual mesh and provide a systematical treatment of various boundary conditions, including perfect magnetic conductor (PMC), perfect electric conductor (PEC), Dirichlet, periodic, and absorbing boundary conditions (ABC) within this method. An excellent agreement is achieved through the numerical calculation of several problems, including homogeneous waveguides, microstructured fibers, photonic crystals, scattering by a 2-D PEC, and resonant cavities.

Anti-fouling effect of axial alternating electromagnetic field on calcium carbonate fouling in U-shaped circulating cooling water heat exchange tube

Four indicators, namely, conductivity, fouling induction period (FIP), scanning electron microscopy, and particle size distribution, were adopted in this study based on an online evaluation experimental platform of the electromagnetic anti-fouling effect and an electromagnetic anti-fouling treatment (EAT) device to investigate the anti-fouling effect of axial alternating electromagnetic field with different magnetic induction intensities (i.e., 0, 10, 15, 17.5, 20, 22.5, and 25mT) on calcium carbonate (CaCO3) fouling in the U-shaped circulating cooling water heat exchange tube. The function model for FIP and magnetic induction intensity was established. Experimental results indicate that the anti-fouling effect was related to the magnetic induction intensity at a specified electromagnetic frequency (i.e., 1kHz). Moreover, the magnetic induction intensity of 20 mT was considered an inflection point, in which the axial alternating electromagnetic field exhibited the best anti-fouling effect. The following results were obtained at 20 mT in this study. The conductivity increased by 84.87µs/cm in average compared with that of the no-treatment group. FIP reached a maximum of 10,536min. The average diameter of CaCO3 particles decreased to 4.04µm. In summary, EAT can effectively prevent and mitigate CaCO3 fouling, and the magnetic induction intensity of 20 mT was found to be the best magnetic induction intensity for the EAT device in the current experiment.

Analysis and Verification of Core Factors in Radio Wave Propagation Loss

Radio wave propagation prediction can calculate the radio frequency link parameters such as field strength coverage and reception of power, which is an important foundation of electromagnetic compatibility (EMC) analysis and frequency coordination. This paper reviews the advances in the research of radio wave propagation by the International Telecommunication Union (ITU) and the International Radio Science Consortium (USRI), analyzes the core influencing factors related to the propagation of radio waves, including the propagation environment and the propagation model used in the calculation which EMC analysis system has been verified. The related content can provide reference for electromagnetic compatibility analysis and the border coordination.

Effects of 1.8 mT sinusoidal electromagnetic fields of different frequencies on bone mineral density and bone histomorphometry of young rats

To study the effects of different frequency sinusoidal electromagnetic fields on the bone mineral density and bone histomorphometry of SD young rats, and to screen suitable electromagnetic field frequency. In total 32 female SD rats of 8 weeks old were randomly divided into 4 groups: control group, 15 Hz group, 30 Hz group and 45 Hz group. Except for the control group, rats in experimental groups were treated with corresponding frequency of 1.8 mT sinusoidal electromagnetic field 90 minutes every day. Rats were measured for bone mineral density after 8 weeks by dual energy X-ray absorptiometry. Rats' femur and vertebral bones were measured by analyzing the static and dynamic forms on the right tibia bone for morphometrics. Rat serum was measured to estimate the index of bone formation and bone resorption. Bone mineral density of rats from 15 Hz group and 45 Hz group was higher than that of the control group (P<0.05). Serum osteocalcin level of rats from 15 Hz group and 45 Hz group was higher than that of the control group (P<0.05). Double fluorescence spacing and static parameters of bone tissue in experimental group rat tibia were higher than that of the control group (P<0.05). Our findings imply that 15 Hz and 45 Hz sinusoidal electromagnetic fields can effectively increase bone mineral density in young rats for preventing osteoporosis.

The effect of pulsed electromagnetic frequency therapy on health-related quality of life in military service members with chronic low back pain

BackgroundIn the U.S. military, chronic low back pain is among the most frequent complaints for medical visits, lost work time, and attrition from active duty and the deployed setting by service members. PurposeThe aim of this pilot study was to determine whether adjunctive treatment with pulsed electromagnetic frequency (PEMF) produced significant variability in chronic low back pain symptoms and secondary health-related quality of life, mental health and disability outcomes. MethodsProspective, randomized pilot study with repeated measures at baseline, post-treatment, and 1 month follow-up for two groups: usual care (UC) vs. UC + PEMF. FindingsIn a convenience sample of 75 service members, health-related quality of life mental and physical component scores were significant: F(2, 104) = 4.20, p = .018 (η2 = .075) and F(2, 104) = 4.75, p = .011 (η2 = .084), respectively; as was anxiety symptom severity: F(2, 104) = 5.28, p = .007 (η2 = .092). Discussion and RecommendationsAdjunctive treatment with PEMF demonstrated improvements in service members’ overall physical health-related quality of life with expected, yet statistically nonsignificant improvements in reported pain and LBP-related disability. There were significant between group differences in anxiety symptom severity with higher symptoms reported by the UC + PEMF group, surprising findings that warrant further investigation.

Electrical Modeling and Analysis of Differential Dielectric-Cavity Through-Silicon via Array

The parasitic parameters and equivalent electrical model of differential dielectric-cavity through-silicon via (DDC-TSV) array on traditional low-resistivity silicon (LRSi) are proposed in this letter. TSV plugs are placed in the dielectric-cavity etched on LRSi. Each analytical formula in the model is established as the fuction of various physical geometries. The resistance–inductance–capacitance–conductance model and S-parameters of the DDC-TSV array are constructed by the Advanced Design System (ADS), which is verified by the 3-D full-wave electromagnetic solver High Frequency Simulator Structure (HFSS). Simulation results of the ADS and HFSS accord well with each other with frequencies up to 100 GHz, which shows good accuracy of the proposed model.

Higher‐Order Interactions in Quantum Optomechanics: Revisiting Theoretical Foundations

The theory of quantum optomechanics is reconstructed from first principles by finding a Lagrangian from light’s equation of motion and then proceeding to the Hamiltonian. The nonlinear terms, including the quadratic and higher‐order interactions, do not vanish under any possible choice of canonical parameters, and lead to coupling of momentum and field. The existence of quadratic mechanical parametric interaction is then demonstrated rigorously, which has been so far assumed phenomenologically in previous studies. Corrections to the quadratic terms are particularly significant when the mechanical frequency is of the same order or larger than the electromagnetic frequency. Further discussions on the squeezing as well as relativistic corrections are presented.

Effects of Electromagnetic Stirring Frequency on the Microstructure and Mechanical Properties of Al-7Si-0.42 Mg-0.1Cu Alloy by Semi-Solid Processing

The effect of the different electromagnetic stirring frequency after low temperature pouring on microstructures and mechanical properties of Al-7Si-0.42 Mg-0.1Cu alloys was studied. It was found that the primary α-Al becomes smaller and tended to be spherical morphology, and the particles were uniformly distributed after electromagnetic stirring. The tensile strength of alloys improved gradually from 193.02 MPa to 212.54 MPa, and the elongation increased from 3.73% to 6.67% when the stirring frequency was 10 Hz. From the fracture morphology, the fracture for alloy stirred at frequency of 10 Hz showed more dimples than that without stirring. When the stirring frequency increased to 15 Hz, the microstructures of primary α-Al appeared to be dendritic structures, and the grains became coarse. As a result, the 10 Hz was the best electromagnetic stirring frequency.

The optical trapezoid model: A novel approach to remote sensing of soil moisture applied to Sentinel-2 and Landsat-8 observations

The “trapezoid” or “triangle” model constitutes the most popular approach to remote sensing (RS) of surface soil moisture based on coupled thermal (i.e., land surface temperature) and optical RS observations. The model, hereinafter referred to as Thermal-Optical TRAapezoid Model (TOTRAM), is based on interpretation of the pixel distribution within the land surface temperature - vegetation index (LST-VI) space. TOTRAM suffers from two inherent limitations. It is not applicable to satellites that do not provide thermal data (e.g., Sentinel-2) and it requires parameterization for each individual observation date. To overcome these restrictions we propose a novel OPtical TRApezoid Model (OPTRAM), which is based on the linear physical relationship between soil moisture and shortwave infrared transformed reflectance (STR) and is parameterized based on the pixel distribution within the STR-VI space. The OPTRAM-based surface soil moisture estimates derived from Sentinel-2 and Landsat-8 observations for the Walnut Gulch and Little Washita watersheds were compared with ground truth soil moisture data. Results indicate that the prediction accuracies of OPTRAM and TOTRAM are comparable, with OPTRAM only requiring observations in the optical electromagnetic frequency domain. The volumetric moisture content estimation errors of both models were below 0.04cm3cm−3 with local calibration and about 0.04–0.05cm3cm−3 without calibration. We also demonstrate that OPTRAM only requires a single universal parameterization for a given location, which is a significant advancement that opens a new avenue for remote sensing of soil moisture.

Electromagnetic radio frequency heating in the pulsed electric current sintering (PECS) process

Abstract

MCS and EHS: An Australian Perspective

Abstract Multiple chemical sensitivity (MCS) and electromagnetic hypersensitivity (EHS) are serious emerging health issues the world over. Despite evidence of a physiological etiology, MCS and EHS continue to be regarded as psychiatric disorders in some countries. Case study documents an Australian family sensitized to numerous everyday chemicals and electromagnetic frequencies as a consequence of exposure to organophosphate and organochlorine insecticides and phenoxy herbicides. Further exposure to toxicants additionally sensitized the mother to light, sound, and pain, the latter manifesting as chronic regional pain syndrome (CRPS). Ignoring documentation from her ecologist, skeptical social workers used the Mental Health Act to have her forcibly removed from her controlled environment. Placed in psychiatric care, she was diagnosed as psychotic on the rationale that, as neither MCS nor EHS existed, belief in their physicality constituted a delusion, which was in itself a manifestation of psychosis. The s...

A compact electron matter wave interferometer for sensor technology

Remarkable progress can be observed in recent years in the controlled emission, guiding, and detection of coherent, free electrons. Those methods were applied in matter wave interferometers leading to high phase sensitivities and precise sensor technologies for dephasing influences such as mechanical vibrations or electromagnetic frequencies. However, the previous devices have been large laboratory setups. For future sensor applications or tests of the coherence properties of an electron source, small, portable interferometers are required. Here, we demonstrate a compact biprism electron interferometer that can be used for mobile applications. The design was optimized for small dimensions by beam path simulations. The interferometer has a length between the tip and the superposition plane before magnification of only 47 mm and provides electron interference patterns with a contrast up to 42.7%. The detection of two dephasing frequencies at 50 and 150 Hz was demonstrated applying second order correlation and Fourier analysis of the interference data.

Nonlinear graphene quantum capacitors for electro-optics

Owing to its peculiar energy dispersion, the quantum capacitance property of graphene can be exploited in a two-dimensional layered capacitor configuration. Using graphene and boron nitride, respectively, as the electrodes and the insulating dielectric, a strongly nonlinear behavior at zero bias and small voltages is obtained. When the temperature is sufficiently low, the strong nonlinear interaction emerging from the quantum capacitance exhibits a diverse range of phenomena. The proposed structure could take over the functionalities of nonlinear elements in many cryogenic quantum systems, and in particular, quantum electro-optics. It is shown that ultrastrong coupling is easily reached with small number of pump photons at temperatures around 1 K and capacitor areas of the order of 1 μm2. A measure of anharmonicity is defined and as potential applications, a qubit design as well as schemes for non-reciprocal devices such as an electromagnetic frequency circulator are discussed.

Analysis of electromagnetic propagation in the magnetic plasma state in spin-ice systems

Low energy excitation states in magnetic structures of the so-called spin-ices are produced via spin flips among contiguous tetrahedrons of their crystal structure. When there are sufficient free positive and negative charges, the system behaves as a magnetic plasma, which could correspond to the highest temperature peak of the specific heat. The electromagnetic waves in both unconfined and confined systems (waveguides) filled with materials of magnetic charges can be able to transmit information and energy. The only problem is the low temperature for which these magnetic entities appear in the spin-ice materials. However, similar behaviour may be present in other compounds at higher temperatures. This analysis is addressed to study physical properties which should be present in those new materials. Therefore, in this paper, we obtain some magnetic linear responses, the effective masses of the magnetic charges from the precession movement of the monopoles which coincides with a strong electromagnetic absorption frequency, the plasmonic physical magnitude which is identified with the cut propagation frequency in a wave guide, and other properties of the electromagnetic propagation in these compounds with effective magnetic monopoles such as the modification of the electromagnetic fields of the wave in the presence of magnetic charges and currents. All these electromagnetic properties can serve as tests for detecting magnetic entities which mimic the behaviour of magnetic monopoles in other different new materials. Besides, these analyses can be illuminating for obtaining possible circuital applications of these materials that lead to “Magnetronic” devices.