Electromagnetic Approach Research Articles

A Quantum-Classical Model of Brain Dynamics.

The study of the human psyche has elucidated a bipartite structure of logic reflecting the quantum-classical nature of the world. Accordingly, we posited an approach toward studying the brain by means of the quantum-classical dynamics of a mixed Weyl symbol. The mixed Weyl symbol can be used to describe brain processes at the microscopic level and, when averaged over an appropriate ensemble, can provide a link to the results of measurements made at the meso and macro scale. Within this approach, quantum variables (such as, for example, nuclear and electron spins, dipole momenta of particles or molecules, tunneling degrees of freedom, and so on) can be represented by spinors, whereas the electromagnetic fields and phonon modes can be treated either classically or semi-classically in phase space by also considering quantum zero-point fluctuations. Quantum zero-point effects can be incorporated into numerical simulations by controlling the temperature of each field mode via coupling to a dedicated Nosé-Hoover chain thermostat. The temperature of each thermostat was chosen in order to reproduce quantum statistics in the canonical ensemble. In this first paper, we introduce a general quantum-classical Hamiltonian model that can be tailored to study physical processes at the interface between the quantum and the classical world in the brain. While the approach is discussed in detail, numerical calculations are not reported in the present paper, but they are planned for future work. Our theory of brain dynamics subsumes some compatible aspects of three well-known quantum approaches to brain dynamics, namely the electromagnetic field theory approach, the orchestrated objective reduction theory, and the dissipative quantum model of the brain. All three models are reviewed.

Comparison study of different forward modeling approaches by using the finite-element method for 3D magnetotelluric data in anisotropic media

We have examined three approaches for analyzing 3D magnetotelluric (MT) data with general anisotropy. These included the direct electromagnetic (EM) approach, which solved the electric field Helmholtz equation directly, and the Coulomb-gauged and Ungauged approaches. The three approaches are discretized using finite-element (FE) methods. First, the correctness of the three approaches is validated using a typical isotropic 3D model and a 2D anisotropic model. The FE solutions of each approach obtained by the direct solver MUMPS are compared with the analytical solutions to demonstrate that all approaches generated accurate results. Subsequently, an anisotropic 3D model is designed to investigate the forward characteristics of the different approaches. The FE solutions are obtained using the quasi-minimum residual (QMR) solver with a symmetric successive overrelaxation (SSOR) preconditioner in this model. The forward modeling results of each approach were compared in terms of stiffness matrices, the convergence of the iterative solver, and apparent resistivity and phase. We find that the FE solution of the Coulomb-gauged and Ungauged approaches produces larger stiffness matrices, but the proportion of non-zero elements in the Coulomb-gauged approach is the least. The Ungauged approach can yield faster solutions over a wide range of frequencies. Finally, a complex numerical example is provided to demonstrate the good convergence behavior of the Ungauged approach.

A novel technique for wall parameter estimation for through wall imaging systems

AbstractAccurate estimating of wall parameters is crucial for precisely locating targets and obtaining well‐focused through wall radar images. Recently, machine learning has been introduced for quick and precise estimation of wall parameters. One of the significant concerns with this approach is the generation of training and testing data, which require the fabrication of walls with different permittivity, thickness, and conductivity. Creating walls with varying permittivity, thickness, and conductivity can be difficult and expensive. Therefore, a cost‐effective method for estimating wall parameters is proposed in this paper. The proposed method uses an electromagnetic approach to train the artificial neural network to retrieve the relative permittivity and thickness of the wall. The proposed estimation approach has the advantages of high precision and low computational complexity. The performance of the proposed approach is validated on simulated and experimental data. The applicability of the proposed method has been shown with measured data from two real building walls. It is shown that the proposed method retrieved wall parameters with high accuracy.

The Shannon Information Capacity of an Arbitrary Radiating Surface: An Electromagnetic Approach

Utilizing a cross-disciplinary approach, we explore Shannon information-theoretic characterizations of the information capacity limits of generic electromagnetic (EM) surfaces intended for possible use in wireless communication links. Our principal task is to first formulate at a general and rigorous level the EM theory of the information that can be extracted from the Maxwellian fields radiated by an arbitrarily shaped continuous surface. This is then followed by a detailed derivation and illustration of practical physics-informed algorithms for computing approximations of the Shannon capacity of surfaces with any given geometry operating in Gaussian channels. Our formalism can address both near- and far-field information capacity scenarios, with a mathematical treatment that includes a complete characterization of the source-field polarization structure, mutual coupling, and interactions.

An Advanced 3-D Electromagnetic Analysis and Experimental Validation of a Bipolar Subnanosecond Pulse Generation System

This article presents an advanced 3-D electromagnetic co-simulation approach developed using the CST software to evaluate the characteristics of a bipolar subnanosecond pulse forming system for application in the biomedical and defense domains. To the best of the authors’ knowledge, the simulation technique presented in this article, which integrates transient switching devices in the 3-D electromagnetic model of the bipolar subnanosecond pulse forming system, was not presented previously in the open literature. The design of the bipolar subnanosecond pulse forming system is based on a thorough analytical calculation with predictions verified using the 3-D numerical modeling to generate a voltage of up to 500 kV peak-to-peak amplitude with a duration of around 1.8 ns when connected to a 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$</tex-math> </inline-formula> load. A good agreement between the experimental results and the CST predictions was obtained, providing the correctness of the proposed modeling technique. Future plans involve connecting the bipolar subnanosecond pulse forming system to an ultra-wideband (UWB) antenna.

An Accurate Model for InP HEMT Small-Signal Equivalent Circuit Based on EM Simulation

A high-reliability small-signal equivalent circuit model for indium-phosphide-based high-electron-mobility transistors (InP-based HEMTs) is proposed. A de-embedding scheme for the representative structure is utilized in this model with an electromagnetic simulation approach to consider the distributed extrinsic parasitic elements. The intrinsic part of the small-signal model is directly extracted with the Y-parameter of the intrinsic two-port network. The extraction of the parametric elements was performed under different biases and three different gate widths ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 20\,\,\mu \text{m}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 30\,\,\mu \text{m}$ </tex-math></inline-formula> , and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 50\,\,\mu \text{m}$ </tex-math></inline-formula> ), our S-parameter predictions showed good agreement with measurements in the 1–50-GHz frequency range. The proposed model performs an electromagnetic simulation of different gate-width devices, considers the devices’ distribution and radio-frequency behavior, and avoids errors caused by traditional tests’ extraction of parasitic parameters. The proposed model solves the problem that the conventional indium phosphide-based HEMT small-signal model is limited by the device topology, making the high-frequency modeling more accurate.

Light transport through a magneto-optical medium: simple theory revealing fruitful phenomena.

Electromagnetic wave transmission in a magneto-optical (MO) medium is a basic and old topic but has raised new interest in recent years, because MO medium plays a vital role in optical isolator, topological optics, electromagnetic field regulation, microwave engineering, and many other technological applications. Here, we describe several fascinating physical images and classical physical variables in MO medium by using a simple and rigorous electromagnetic field solution approach. We can easily obtain explicit formulations for all relevant physical quantities, such as the electromagnetic field distribution, energy flux, reflection/transmission phase, reflection/transmission coefficients, and Goos-Hänchen (GH) shift in MO medium. This theory can help to deepen and broaden our physical understanding of basic electromagnetics, optics, and electrodynamics in application to gyromagnetic and MO homogeneous medium and microstructures, and might help to disclose and develop new ways and routes to high technologies in optics and microwave.

Electromagnetic simulation and microwave circuit approach of heat transport in superconducting qubits

The study of quantum heat transport in superconducting circuits is significant for further understanding the connection between quantum mechanics and thermodynamics, and for possible applications for quantum information. The first experimental realisations of devices demonstrating photonic heat transport mediated by a qubit have already been designed and measured. Motivated by the analysis of such experimental results, and for future experimental designs, we numerically evaluate the photonic heat transport of qubit-resonator devices in the linear circuit regime through electromagnetic simulations using Sonnet software, and compare with microwave circuit theory. We show that the method is a powerful tool to calculate heat transport and predict unwanted parasitic resonances and background.

Evaluation of the Strengthening Effect of Different Surface Treatment Techniques in Steel Crankshaft Manufacturing Industry

At present, electromagnetic induction quenching and nitriding are two commonly used surface strengthening approaches applied in improving the strength of the steel parts. In this paper, a comparative study was proposed to research the strengthening effect of these two technologies in improving the fatigue strength of steel crankshaft. First a modified statistical analysis approach of the fatigue limit load was proposed to obtain the distribution of the fatigue limit load. Then two types of steel crankshafts were selected to be the object of research and treated by these two techniques. Finally the standard T and F hypothesis testing methods were conducted in evaluation the strengthening effect. The results showed that compared with the nitriding approach, the electromagnetic induction approach can improve the fatigue strength of the steel crankshaft more obviously, thus is more suitable for engineering applications.

Absolute displacement measurement using an inertial reference generated by linearised electromagnetic levitation

This paper proposes a novel passive absolute displacement measurement system (ADMS) utilising the electromagnetic levitation approach, instead of any mechanical spring. The most distinctive feature of the proposed ADMS is its measuring amplitude range of 30μm–1.2 mm with a lower frequency limit of 2 Hz. Consequently, a wider measuring bandwidth and higher measurement accuracy for absolute displacement signals can be realised without feedback/serve-type inertia sensors, which are usually expensive and vulnerable. Both features make the proposed system promising for of low-frequency measurement applications, such as precision vibration isolation of optical platforms in vibrational environments, anti-shake UAV platforms, monitoring of seismic wave signals, ship equipment protection and safety inspection of long-span bridges. First, the principles of the proposed ADMS are introduced. Subsequently, the measuring performance of the proposed ADMS is simulated and analysed. Finally, a prototype of the ADMS is constructed and tested. The experimental results confirm the validity of the proposed ADMS design and demonstrate its capability to measure the absolute displacement with a low-frequency and wider amplitude range.

Исследование системы беспроводной передачи энергии

New approach to wireless power transfer for electrical vehicles battery charging is discussed in a paper. The system of power transfer consists of generating unit with VSWR meter, two electromagnetic structures, and rectifying unit. Electromagnetic structure which is represented as microstrip device does not emit electromagnetic energy at its stand alone position. When electromagnetic structures approach each other ones are transformed into alone directional coupler; and effective power transfer takes place. System simulation in AWR design environment was carried out at different mutual arrangements of microstrip units. It was shown the power loss did not exceed 1 dB in a wide range between system parts and its mutual arrangements. Experimental model of system for power transfer was made and experimental study was carried out. Experimental and simulation results are well agreed. The reasonable system size and weight are well situated for its use for battery charging of electrical vehicle.

A new approach to determine/design the eutectic composition of binary, ternary, and high-entropy alloys using electromagnetic directional crystallization

Eutectic materials have been widely employed in many high-tech fields, and recently, eutectic high-entropy alloys (EHEAs) have become a research focus of eutectic materials; however, it is challenging to determine/design the eutectic composition of alloys accurately, especially multi-component alloys and EHEAs. In this study, a new electromagnetic directional crystallization approach was proposed to determine/design eutectic alloy compositions. First, standard eutectic Al-Si, Al-Si-Fe, Al-Si-Ti, and Al-Si-Fe-Mn alloys were obtained by directly separating their respective melts using electromagnetic directional crystallization. Then their eutectic compositions were accurately determined by inductively coupled plasma-optical emission spectroscopy. Conflicting reports about the eutectic reactions and phase transformations occurring in the Al-Si-Ti system were also resolved. Thereafter, the application of electromagnetic directional crystallization was extended to EHEAs. The widely investigated AlCoCrFeNi 2.1 EHEA was confirmed to have a eutectic composition, and a new EHEA Al 16.8 Co 12.6 Cr 13.8 Fe 11.8 Ni 45.1 with a combination of high strength and high ductility was obtained in this study by separating the AlCoCrFeNi 3 melt via electromagnetic directional crystallization. Therefore, in the absence of thermodynamic data, electromagnetic directional crystallization provides a promising approach for determining and designing the eutectic composition of alloys, especially EHEAs. This new approach is more direct, efficient, and simpler than the conventional thermodynamic-calculation approach because the application of the latter is significantly limited when thermodynamic data are not available. • A new approach is proposed to design eutectic high-entropy alloys without thermodynamic calculation. • A new eutectic high-entropy alloys, Al 16.8 Co 12.6 Cr 13.8 Fe 11.8 Ni 45.1 , was designed and reported. • Standard eutectic alloys were prepared through one-step electromagnetic directional crystallization. • Controversial research results about AlCoCrFeNi 2.1 alloy and the Al-Si-Ti system were finally solved.

Electromagnetic origin of femtosecond laser-induced periodic surface structures on GaP crystals.

The formations of different types of laser-induced periodic surface structures (LIPSS) on the surface of GaP crystals with different laser fluence are researched in experiments. The transition from the high spatial frequency LIPSS (HSFL) to the low spatial frequency LIPSS (LSFL) occurred as the number of the irradiated laser pulse increased. The finite difference time domain method combined with the holographic ablation model is used to simulate the LIPSS formation under the irradiation of multiple pulses. Different types of ripples are predicted by the electromagnetic approach. Results demonstrate that the electromagnetic origins of HSFL and LSFL are due to the interference of incident field and the scattering field under the multi-pulse irradiation.

A Combined Electromagnetic and Mechanical Approach for EU-DEMO Toroidal Field Coils

The roadmap to fusion electricity of the European scientific program aims at the realization of the future DEMOnstration (DEMO) fusion power plant. In 2020, the pre-concept design phase of DEMO was completed, defining the concept and characteristics of the main magnets and structures of the machine. Sixteen toroidal D-shaped magnets, six poloidal annular coils and a central solenoid constitute the functioning system core. The reactor is subjected to huge mechanical loads, mainly due to the Lorentz force produced by the combination of the high magnetic fields and operative currents. As a consequence, the loading conditions are extremely demanding for the structural components, and it is crucial to complete a comprehensive static and fatigue assessment before proceeding with the next design iteration. This work focuses on the electromagnetic and structural analyses performed on the toroidal field coil system and its support structures to present the methodological approach developed. Exploiting the finite element method, a three-dimensional model has been defined to obtain the electromagnetic loads on the main time points of the reference plasma scenario and then transfer them to a related 3D structural model, corresponding to the discretization of the electromagnetic one. The structural model was used to obtain the displacement and stress fields at the various time points to perform the mechanical evaluation as well as the fatigue assessment.

Toward better metal flow control in electrohydraulic sheet forming by combining with electromagnetic approach

Electrohydraulic sheet forming is a high-velocity manufacturing process, which utilizes a pressure pulse induced by underwater electrical discharge to plastically shape metals. It has attracted wide interest for its potential to shape metal materials with poor formability. Such advantages can be exploited by combining this process with the conventional stamping process or by using it solely. In both cases, the dominant deformation mode is stretching, implying substantial thinning of sheet metal. The goal of this paper is to improve the material flow control in electrohydraulic sheet forming. A controllable drawing deformation mode is introduced into the electrohydraulic sheet forming process by using a radial inward pulsed Lorentz force at sheet edge induced by an electromagnetic coil, which can substantially enhance the draw-in of the sheet flange. The flexible combination of the stretching deformation and the introduced drawing deformation allows active control of the high-velocity material flow behavior, thus enabling much better control of the final forming quality. About 20 % improvement of the forming height limit is observed from the experimental results. Furthermore, a numerical model is established to better understand the process mechanism, and the critical roles of the amplitude and the action timing of the radial inward Lorentz force are identified.

Increasing the measurement of soil water content with the characterization of magnetic field induction sensors using model equations for the internet of thing application

This study proposes an increase in the measurement of soil water content with sensor characterization that can be integrated with the internet of things. The main contribution of this work is the improvement in measurement accuracy compared to measurements using a moisture meter. This is achieved through an electromagnetic approach using a pair of transceiver coils as a sensor. Determination of water content in the soil is carried out through the formulation of an equation model that connects the measured voltage on the receiving coil with the mass of water contained. It is known that the use of the equation model in the test data results in better accuracy with an error of 2.03% - 17.43%, compared to measurements using a moisture measuring device with an error of 13.21% - 32%. This equation model that uses the electromagnetic method provides an alternative solution for determining the soil water for wider land use so that can be used for internet of things application.

A Computational Electromagnetics and Sparsity-Based Feature Extraction Approach to Ground-Penetrating Radar Imaging

In this paper, a feature extraction technique based on the electromagnetic representation of radar signals is presented. In particular, we focus on ground penetrating radar imaging, where we model the backscatter from varying two dimensional geometric shapes with arbitrary local coordinate rotations. Due to the electrically small nature of buried targets, and the bending of the radar signal at the air-soil interface we focus on exact methods to model the surface current density induced on scattering surfaces. Overcomplete basis sets are derived from the electromagnetic descriptions to represent the scene in a sparse manner. From this proposed modeling framework we devise a novel methodology to exploit the prediction of scattering behavior to extract features for classification from radar scenes when multiple buried scattering surfaces are present. We see that our method can identify and reconstruct buried scattering geometries in the presence of false targets that are brought about from the nonlinear nature of the exact electromagnetic modelling methods. A noniterative algorithm based on the conjugate of Green&#x2019;s function is developed to solve for the surface current in an unknown domain using multi-frequency, multi-aperture data. Our modeling and feature extraction algorithms are numerically validated for different target shapes buried in lossy soil profiles.

Foundation of Ultradeep Boundary Detection Based on the Electric Field Characteristics

An ultradeep boundary detection method based on the characteristics of the electric field in a single well is proposed. Unlike any conventional azimuthal electromagnetic (EM) wave logging approach, the new design employs an open-loop half-circle antenna other than the tilted or transverse closed-loop coil antenna as the receiver. The voltage on the half-circle antenna varies periodically with the tool-face angle, which provides the azimuthal information of the boundary. To explore how this new measuring method works, we investigate the electric field characteristics around the receiving antenna. The voltage is calculated by the integral of the electric field. By analyzing the voltages on each segment and their serial connection, the reason is revealed for the significantly enhanced voltage on the half-circle antenna compared to the tilted/transverse closed-loop coil. It lays a new foundation of ultradeep boundary detection based on the electric field characteristic. The voltage response behaviors are further investigated with respect to the tool offset, frequency, distance to the boundary (DTB), and conductivity anomaly. The monotonous changing of the voltage is observed within a wide range of those parameters. The results show that the half-circle antenna has great potential in realizing ultradeep boundary detection with a small offset.

Design and analysis of compact 8-port dual-element MIMO antenna for wireless applications utilizing classical electromagnetic CMA approach

A compact 8-port antenna of size 0.64λ0× 0.64λ0× 0.01λ0 (λ0 is lowest operating wavelength at 3.2 GHz) with dual-element MIMO configuration is proposed in this study. The integrated multi-port system has 4 × different antenna configurations, assisting discrete operating modes (Ant-On as odd numbered antennas, Ant-En as even numbered antennas, where n = 1, 2, 3,….., 8) and are investigated through electromagnetic modal analysis using CMA approach. The Ant-On elements has an inverted L-shaped monopole with broadened feed and narrowed at junctions. To improve impedance matching,4-nested CSRR loops are loaded as magnetically coupled induced resonator. The 4 × Ant-On operates from (3.35–4.08) GHz of IBW ≈ 20%. Similarly, the Ant-En elements has an linear monopole element with electrically coupled two L-shaped resonating stubs assisting wideband performance. The 4 × Ant-En operates from (3.2–5.32) GHz of IBW ≈ 40%. There is no decoupling network and the coupling coefficient is > 15 dB, by splitting the grounds of each antenna elements with L-shaped and stepped ground topologies. To invoke pattern diversity, Ant-On and Ant-En elements are placed side-by-side and are sorted orthogonally to mimic radiation diversity. The ECCFar-field(ρ1n)< 0.13 with (4–5.4) dBi as realized gain and radiation efficiency > 60% in the operating spectrum. A prototype antenna was fabricated and measured with good results to be potentially explored in wireless applications.

3‐D low numerical dispersion WLP‐FDTD method with artificial anisotropy parameters

Based on the weighted Laguerre polynomials (WLPs) and artificial anisotropic (AA) parameters, a 3-D unconditionally stable finite-difference time-domain (FDTD) electromagnetic simulation approach is proposed. The implementation of WLPs in time domain effectively eliminates the time step and AA parameters in spatial difference, resulting in suppressed numerical dispersion error. The monochromatic wave is employed as an example to obtain the numerical dispersion relationship of 3-D AA-WLP-FDTD under AA parameter, in which reduced numerical dispersion error is observed. Compared with the conventional WLP-FDTD technique, this approach demonstrates smaller numerical dispersion error under similar calculation cost.