Electromagnetic Field Simulation Research Articles

Safety Distance Analysis of 500kV Transmission Line Tower UAV Patrol Inspection

Aiming at the problem that UAV (Unmanned Aerial Vehicle) is widely used in transmission line inspections, and the inspection safety distance control is not clear enough. Based on the relevant domestic standards and regulations for UAV inspection operations, this letter establishes a 500kV cat head Tower UAV inspection operation electromagnetic field simulation finite element model. The model uses the field decomposition method to decompose the three-dimensional unbounded field into bounded sub-areas, and calculates and obtains the electric and magnetic field changes around the wire and when the UAV is at different positions on the wire. Combined with the average breakdown field strength of the bar-to-plate gap and the UAV electromagnetic compatibility limit, the safe distance calculation method for the UAV power inspection is comprehensively determined. The application of this safety distance calculation method can improve the reliability and safety of the transmission line UAV when conducting inspection operations, and is of great significance for ensuring the safety of lines and equipment.

Design and Research on Tapped Inductor of Large Step-up Ratio DC/DC Converter

The design and manufacture of magnetic components such as inductors need to estimate theoretical parameters based on the working characteristics of circuit on the one hand, and select the magnetic core and winding method by experience to determine the manufacturing plan. The parameters and performance of magnetic components obtained by different winding methods are usually different, so the design results have certain uncertainty. In order to better obtain system indicators, a design method for the design of the tapped inductor of large step-up ratio DC/DC converter is proposed to calculate the key parameters such as the turn ratio and inductance of the tapped inductor. The optimized winding scheme method of the tapped inductor is proposed by combining electromagnetic field simulation and circuit simulation. The simulation results show that the theoretical parameters obtained under the proposed method are correct, and multiple performance indicators of the tapped inductance corresponding to the converter circuit under different winding modes can be obtained, which is convenient for the designer to find the best appropriate production plan according to actual needs.

The Effect of Boreal Summer Intraseasonal Oscillation on Evaporation Duct and Electromagnetic Propagation over the South China Sea

Intraseasonal oscillation of the evaporation duct, lasting 30–60 days, has been identified over the South China Sea (SCS) summer monsoon region based on multiple reanalyses and observational data. The boreal summer intraseasonal oscillation (BSISO) causes anomalies at the air–sea boundary and thus plays a dominant role in modulating the variation of the evaporation duct. The height and strength of the duct enhance/suppress during the negative/positive phase of the BSISO over the SCS. This results from the fact that active BSISO convection reduces solar radiation reaching the sea surface by increasing cumulus cloud cover, whereupon precipitation and water vapor transported by the enhanced southwest jet increase humidity over the air–sea boundary. Reduced air–sea temperatures and humidity differences lead to a weaker evaporation duct. Usually, the temporal evolution of the evaporation duct lags 2–4 days behind the BSISO, with the center of evaporation duct anomalies farther south than the BSISO. Simulated electromagnetic fields substantively influence the condition of the evaporation duct, with obvious over-the-horizon and radar blind spot effects in the typical negative phase of the BSISO, which is very different from standard atmospheric conditions.

Fast Simulation of Electromagnetic Fields in Doubly Periodic Structures With a Deep Fully Convolutional Network

The simulation of electromagnetic fields in many applications with double periodicity can be viewed as an image-to-image translation problem, where the structure is known and the fields need to be predicted. In this work, we take extreme ultraviolet (EUV) lithography as an example and propose a very efficient technique based on the U-Net architecture, a deep fully convolutional network (FCN). The U-Net is trained with data of some typical patterns in a 128 nm $\times\,\,128$ nm unit cell, and good accuracy can be obtained in the prediction of the near field on much larger unit cells with complex patterns. Furthermore, numerical experiments demonstrate that the proposed method is three orders of magnitude faster than conventional state-of-the-art methods, such as the spectral-element spectral-integral method.

Parametric Analysis of Negative and Positive Refractive Index Lens Antenna by ANSYS HFSS

Lens antennas with multibeam, high gain, and low sidelobe level are potential candidates for base station antennas in 5G mobile communication. In this paper, the authors perform simulation and parametric analysis of a lens antenna with positive and negative refractive indexes (NRI) using the modern electromagnetic field simulation software ANSYS HFSS. The simulation results of structures and theoretical calculations are analyzed and compared. The simulation results show the effectiveness of using negative refractive index lens antennas to minimize the dimension. The lens thickness with a negative refractive index decreased from 24.5 mm to 6.1 mm compared to the positive refractive index lens’s thickness. The results also indicate the similarities in gain, sidelobe level, amplitude, and electric field distribution on the aperture plane of the negative and positive refractive indexes (PRI) lens antennas compared to the theoretical calculation. In addition, the authors simulate a lens structure with additional quarter wavelength matching layers (MLs) to estimate the antireflection performance.

Analysis of Vibration and Noise for the Powertrain System of Electric Vehicles under Speed-Varying Operating Conditions

Whine noise from the electric powertrain system of electric vehicles, including electromagnetic noise and gear-meshing noise, significantly affects vehicle comfort and has been getting growing concern. In order to identify and avoid whine problems as early as possible in the powertrain development process, this paper presents a vibration and noise simulation methodology for the electric powertrain system of vehicles under speed-varying operating conditions. The electromagnetic forces on the stator teeth of the motor and the bearing forces on the gearbox for several constant-speed operating conditions are obtained first by electromagnetic field simulation and multi-body dynamic simulation, respectively. Order forces for the speed-varying operating condition are generated by interpolation between the obtained forces, before they are applied on the mechanical model whose natural modes have been calibrated in advance by tested modes. The whine noise radiated from the powertrain is then obtained based on acoustic boundary element analysis. The simulated bearing forces indicate that the overlooking of the motor torque ripple does not result in significant loss in simulation accuracy of electromagnetic noise. The simulation results and tested data show good consistency, with the relative frequency deviation of local peaks being less than 8% and the error of the average sound pressure level (SPL) being mostly below 10 dB (A).

Numerical Simulation and Analysis of Electromagnetic Fields Induced by a Moving Ship Based on a Three-Layer Geoelectric Model

In this paper, we present a numerical simulation method of electromagnetic (EM) fields induced by a moving ship (EMFMS), which consist of both the shaft-rate EM field and the static EM field. The shaft-rate EM fields in the frequency domain are first obtained by solving the partial differential equations together with suitable boundary conditions, and then they are transformed into the time domain by using the inverse Fourier transform. Finally, the static fields are added to obtain the EM fields of a moving ship. The effects of the source current intensity and the source position on the EM fields of a moving ship are discussed in detail. A field example of EM response of a moving ship is presented and its characteristics are analyzed.

Simulation of electromagnetic field and its effect during electromagnetic stirring in continuous casting mold

A mathematical model of in-mold electromagnetic stirrer has been developed to calculate the three-dimensional time-varying magnetic field for electromagnetic stirring in the continuous casting mold. The calculated magnetic field is coupled with the magneto-hydrodynamic and solidification model to analyze the effect of stirrer width at different current and frequency applied to the stirrer. The enthalpy porosity technique is used to track the liquid-solid transformation while the realizable k-ε turbulence model is used to account the turbulence in the fluid flow. The coupling of the time-varying electromagnetic field with solidification model makes the model complicate which leads to having divergence problem and large computation time. The model efficiently computes the electromagnetic field, fluid flow, solidification behavior of an electromagnetically stirred continuous casting mold, which have been validated against the reported results. From the initial results it is observed that magnetic flux density significantly increases with increase in stirrer width and current while, frequency has a marginal effect on magnetic flux density. The result obtained from coupled model shows that increase in frequency has a large influence on stirring intensity and hence on solidification behavior. However, stirrer width and current marginally affect the stirring intensity and solidification behavior.

Low concentration noroxin detection using terahertz spectroscopy combined with metamaterial.

The unreasonable use of antibiotics in poultry breeding has led to the frequent occurrence of antibiotic residues in poultry products, affecting food safety and posing a threat to human health. Accurate and rapid detection of antibiotic drug content is therefore of great significance. In this study, a new metamaterial method based on terahertz (THz) spectroscopy for the detection of the quinolone antibacterial drug noroxin in low concentrations was developed and tested. First, a new metamaterial structure was designed using a computational electromagnetics simulation tool with experimental verification. Three-dimensional full-wave electromagnetic field simulations and measured transmission spectra for the metamaterials were observed. Second, the transmission spectra of photoresists with different thicknesses (0-40µm) on the metamaterials surface were simulated, and the transmission spectra of noroxin thin films of different concentrations on the metamaterial surface were measured. Finally, using a purchased standard sample of noroxin in ethanol (100µg/mL) as the mother liquor, test samples of different concentrations were prepared, and experiments and multivariate data analysis were carried out. The noroxin detection limit for the method presented in this paper was determined as 0.01µg/mL. Thus, the new metamaterial method based on terahertz spectroscopy designed in this study was shown to effectively detect low concentrations of noroxin, providing a theoretical and experimental basis for the rapid detection of quinolone antibiotic residues in food matrices.

Mathematical approach for the design configuration of magnetic system with multiple electromagnets

Magnetic actuation techniques and microrobots have attracted great interest since they have potential in biomedicine applications. Interventional techniques have emerged as a tool to handle a wide range of minimally invasive surgeries (MIS). However, current MIS procedures are constrained by the limitation of manual operation by surgeon. Thus, various microrobotic solutions including magnetic navigation systems have been proposed for MIS, which carries many potential benefits such as reduced incision, less intraoperative hemorrhaging and postoperative pain, and faster recovery time. In recent decades, many electromagnetic actuation (EMA) systems have been reported and involved to general surgery. The EMA system allows to generate efficiently magnetic source for microrobot control when its specifications are further investigated and satisfied for the desired application. To precisely manipulate the biomedical microrobot, a key issue still relies on the design of a suitable EMA platform. In this paper, we demonstrate a mathematical approach for the design configuration of magnetic system with multiple electromagnets. Especially, the required magnetic coil number has been investigated where the heading motion control, magnetic force control and their combination control are discussed respectively. The singular cases of control are pre-evaluated by a mathematical analysis of the simulated electromagnetic field. In addition, the placed positions and tilted orientations of the applied electromagnets are investigated for the optimization regarding the six typical configurations of EMA platform with 4, 6 and 8 coils. The various configurations of EMA systems have been comprehensively analyzed. Therefore, with the number of electromagnets and their optimal configuration obtained by the proposed approach, the EMA system can be initially established.

Effects of Filling Material Roughness on Scattering from a Rectangular Groove

This study investigated the effects of filling material roughness on the H-polarized scattering signatures of a two-dimensional (2D) rectangular groove embedded on an infinite ground plane. Under the assumption of a weakly rough surface on the groove, simplifying suppositions can be used to estimate Green’s functions inside and outside the groove. Enforcing continuity in the tangential magnetic field on the rough surface enables the construction and resolution of a Fredholm’s integral equation with logarithmic singularity. The results were verified via two full-wave electromagnetic field simulations carried out using the finite element method and the method of moments. The findings showed that even a weakly rough surface, such as a polished exterior with weak residual roughness, can considerably affect and change 2D scattering patterns.

Manipulation System for Measuring Heat Flux in Radioactive Melt

Abstract This article is focused on introducing of the manipulation system, which is used to insert equipment or measuring probes into the chamber of a cold crucible during experimental induction skull melting. The measuring probe could be, e.g., calorimeter for measuring heat flux from a melt, which is created in the cold crucible by electromagnetic induction. The first part describes the technical parameters of the manipulator and the possibilities of manipulator controlling. The manipulation system is controlled by the algorithm implemented in the programmable logic controller CompactRIO or by mechanical controller called manual pulse generator, which is independent of the programmable logic controller. Different control methods increase the safety of the system. The next part contents basic information about the control algorithm based on LabVIEW software and the user interface of the touch screen. The article also deals with testing the manipulator, which was used in an experiment simulating corium behavior under conditions of the severe accident of a nuclear power plant. The last part describes simulations of electromagnetic field and temperature field in the chamber of the cold crucible, which were confirmed with real measuring. The goal of the simulations was to determine the effect on the manipulation system and calculation of Joule's losses in the calorimeter before immersion into the melt. The most significant heat transfer to the calorimeter was the radiation from a melt, which was also calculated.

Methods of the diffraction theory for microwave aquametry of paper materials

We present a short review of several fundamental results, which have been obtained within frameworks of one trend of the wide spread of investigations, carried out during 1970 –2010s under the leadership of doctor of science, corresponding member of the National Academy of Sciences of Belarus P. D. Kukharchik, whose scientific interests were connected with the study of physical properties of heterogeneous dielectric and metal-containing industrial materials by the methods of holography, holographotomography, digital radiography, microwave and infrared introscopy. In this review, by the example of several base problems, we describe the semi-analytical methods of rigorous theoretical simulation of electromagnetic fields, arising under electromagnetic diffraction by slots in perfectly conducting screens of arbitrary thickness in absence and in the presence of plane dielectrics in the plane and cylindrical geometries of electromagnetic propagation. It demonstrates application of the these methods to simulation of processes of moisture measuring of paper sheet using microwave cavities with slots, which are employed on enterprises of pulp and paper industry.

Silver nanoparticle on aluminum mirror: active spectroscopy and decay rate enhancement

Recent advances in nanotechnology and optics have paved the way for new plasmonic devices. One of them are nanopatch antennas that are simple and, at the same time, effective devices for localizing the electromagnetic field on a scale of less than 10 nm and can be used in photonic integrated circuits as effective sources of photons, including single-photon sources. In the present study, we investigate the radiative characteristics of a submonolayer of colloidal CdSe/CdS quantum dots that form island structures in a resonator: a cubic silver nanoparticle on an aluminum mirror. For detecting plasmonic nanoparticles on glass or metal surfaces, we propose a new technique involving a tunable laser and a confocal microscope. We provide a comparative study of the luminescence enhancement factors for QDs in the NPAs upon off-resonance excitation and at a wavelength close to the resonance; a significant difference in the luminescence enhancement factors (by order of magnitude) is demonstrated. A 60-fold reduction in the spontaneous emission time, as well as an increase in the radiation intensity by a factor of 330, has been obtained in the experiments. The increase in the spontaneous emission rate demonstrated for the quantum dots is explained by the Purcell effect. Full-wave simulations of electromagnetic fields were carried out for the model of the developed nanopatch antenna; luminescence enhancement factors and radiative efficiencies were calculated as well.

Optimization of an extremely high Q-factor terahertz perfect absorber for environmental refractive index sensing using quasi-analytical solutions

Terahertz (THz) radiation can be used to monitor the environment by sensing its variation of refractive index. Previous studies have shown that a THz perfect absorber with several hundred Q-factors can function as sensitive THz refractive-index sensors (THz-RISs). However, the electromagnetic field simulation of THz-RIS is currently based on the numerical methods, which are inefficient when THz-RIS has extremely high Q-factors in several orders of magnitude. In this study, we present the quasi-analytical solutions of THz-RIS made by a 2D metallic hole array coated by polymer thin-film (2D-HACP) for the efficient optimization of extremely sensitive THz-RIS. It is found that the optimized 2D-HACP shows the absorption peak about 96.7% at the resonant frequency close to 1 THz. The absorption peak has full width at half-maximum about 39.1 MHz, yielding the Q-factor equal to 25,555. It is shown that the figure of merit associated with the variations of the real part and imaginary part of environment’s complex refractive index are equal to 2.56 × 10 4 1/RIU and 4.12 × 10 8 1/(RIU·THz), respectively. Therefore, the optimized 2D-HACP may work as an extremely sensitive environmental sensor by monitoring the tiny variation of the environment’s complex refractive index.

Response of Organic Lime Mortars to Thermal and Electrical Shocks Due to Lightning Strikes

Lightning strikes are prevalent and inevitable natural phenomena that might cause damages during interaction with building structures and, in some cases, culminate in fires. During the last decades, several lightning strikes have caused considerable damages to cultural and heritage buildings. Furthermore, recent studies indicated a plausible connection between climate changes due to global warming and variations in the frequency and intensity of lightning. The evaluation of the structural efficiency and resilience of cultural buildings to global changes and natural risks appears significant in the light of the current scientific debate. This research aims at the assessment of lightning strikes’ effects on ancient heritage binding materials through the characterization of their thermal and electrical conductivity properties. This study focused on the performance evaluation of green and low-cost mortars based on the use of organic additives. Lime samples were reverse engineered by using a mixture of organics (fig, jaggery, black grape, banana, kadukai), which comprises the most common additives used in traditional Indian mortars. The reliability of the organic mixture in enhancing the resilience of masonry to lightning strikes was analyzed by using electromagnetic field simulation.

Thermal Distortion of Signal Propagation Modes Due to Dynamic Loading in Medium-Voltage Cables

Temperature variation from dynamic cable loading affects the propagation characteristics of transient signals. The distortion of modal signal components as a function of temperature in a three-phase medium-voltage cable is investigated. The temperature influence arises mainly through the complex insulation permittivity, which has a non-linear relationship with temperature. Near the maximum operating temperature of the cross-linked polyethylene insulation, the propagation velocity increases by 0.56% per degree centigrade but is an order of magnitude less sensitive at ambient temperature. The paper presents modeling results based on cable impedance and admittance matrices obtained from electromagnetic field simulation, taking into account the time-varying temperature distribution in the cable cross-section. The results are verified by applying Rayleigh–Schrödinger perturbation analysis. In the time domain, signal patterns shift when the modal propagation velocities change upon cable loading. Moreover, separation of degenerate modes is observed when the cable phase conductors carry an unbalanced current. The perspectives for exploiting the temperature dependency of signal propagation for pinpointing cable defects and for dynamic rating of underground power cables are discussed.

The Polarization Effect in Surface‐Plasmon‐Induced Photocatalysis on Au/TiO2 Nanoparticles

AbstractControlling the interaction of polarization light with an asymmetric nanostructure such as a metal/semiconductor heterostructure provides opportunities for tuning surface plasmon excitation and near‐field spatial distribution. However, light polarization effects on interfacial charge transport and the photocatalysis of plasmonic metal/semiconductor photocatalysts are unclear. Herein, we reveal the polarization dependence of plasmonic charge separation and spatial distribution in Au/TiO2 nanoparticles under 45° incident light illumination at the single‐particle level using a combination of photon‐irradiated Kelvin probe force microscopy (KPFM) and electromagnetic field simulation. We quantitatively uncover the relationship between the local charge density and polarization angle by investigating the polarization‐dependent surface photovoltage (SPV). The plasmon‐induced photocatalytic activity is enhanced when the polarization direction is perpendicular to the Au/TiO2 interface.

The Polarization Effect in Surface-Plasmon-Induced Photocatalysis on Au/TiO2 Nanoparticles.

Controlling the interaction of polarization light with an asymmetric nanostructure such as a metal/semiconductor heterostructure provides opportunities for tuning surface plasmon excitation and near-field spatial distribution. However, light polarization effects on interfacial charge transport and the photocatalysis of plasmonic metal/semiconductor photocatalysts are unclear. Herein, we reveal the polarization dependence of plasmonic charge separation and spatial distribution in Au/TiO2 nanoparticles under 45° incident light illumination at the single-particle level using a combination of photon-irradiated Kelvin probe force microscopy (KPFM) and electromagnetic field simulation. We quantitatively uncover the relationship between the local charge density and polarization angle by investigating the polarization-dependent surface photovoltage (SPV). The plasmon-induced photocatalytic activity is enhanced when the polarization direction is perpendicular to the Au/TiO2 interface.

Application of Magnetic Metal 3-D Printing on the Integration of Axial-Flow Impeller Fan Motor Design

This article aims to implement a fan motor design with an airfoil-shaped rotor via the newly developed 3-D printing method. This integrated design is originated from a flux-switching permanent magnet motor, in which the motor rotor can directly produce airflow without any external impellers. Such a design and manufacturing process can effectively enhance the robustness of the fan motor structure and increase its power density. This article adopts 3-D finite element analysis for electromagnetic and fluid field simulation. Moreover, a new metal 3-D printing method with a low core loss feature during high frequency operation is applied. Finally, the experimental results with a prototype are presented to verify the designed performance.