Surface Field Distribution Research Articles

Overall particle size distribution estimation method based on kinetic modeling and transformer prediction

Estimating the overall particle size distribution (PSD) on the conveyor is one of the most important means of monitoring blast furnace production. Due to the harsh production environment and limited detection conditions, existing online detection methods can only estimate part of the PSD, but it is difficult to predict the overall PSD. Unlike segmentation methods that can only obtain surface PSD, we propose an overall PSD estimation method based on mechanistic modeling and local–global fused prediction networks. First, we constructed a kinetic mechanism model of particle accumulation, from which global field distribution features such as coordination number, moment of inertia, and spatial distribution were extracted. Then, a particle segmentation model is trained using surface images collected by detection means such as cameras to obtain surface PSDs as local surface features. Next, to predict the overall PSD, we propose a Local surface and Global field distribution feature Fusion-based Transformer network (LGFT). Among them, in order to better aggregate local and global features, we introduce orthogonal fusion and point cloud extractors in the encoder. Finally, we verify the accuracy and efficiency of our method through extensive ablation experiments.

Filtering linear polarization converters based on multi-mode unit for harmonic suppression

In this article, a class of filtering linear polarization converters based on a single quasi-single-layer triangular resonator unit is proposed. By loading the stub-line and slot lines, the degenerate modes of the single fundamental resonant mode of an isosceles right-angle patch are separated into two for a second-order filtering characteristic, and two additional resonant modes are then generated for the second conversion band. Attributed to the mixed electric and magnetic coupling in the coupling section of the loaded stub-line, several conversion zeros are introduced at the same time. As the contribution of this work, multiple resonant modes and conversion zeros can be independently controlled by the corresponding parameters, enabling second-order single- and dual-band response with multi-mode high selectivity side-band and harmonic rejection characteristics out-of-band. With the detailed analysis of the surface current and field distributions, the polarization conversion mechanisms are revealed. Finally, the single-band and dual-band linear polarization converters are processed, and the measured and simulated results are in good agreement. As expected, the two polarization converters show excellent filtering features, which is beneficial for improving modulation accuracy and avoiding unwanted electromagnetic interference in various applications of multi-passband and multi-functional metasurfaces.

Cutting performance and tool wear in laser-assisted grinding of SiCf/SiC ceramic matrix composites

Ceramic matrix composites have high hardness, so their machining requires high grinding forces that cause severe wear of the grinding head. To investigate this problem, the present study investigated the cutting performance of conventional grinding (CG) and laser-assisted grinding (LAG) of SiCf/SiC ceramic matrix composites using electroplated diamond grinding heads. Firstly, a three-dimensional transient heat transfer model based on a Gaussian heat source was developed to observe the surface and internal temperature field distributions of SiCf/SiC ceramic matrix composites subjected to laser irradiation. Secondly, the effects of laser heating temperature on the workpiece surface on the grinding forces were analysed. It was found that the axial and feed grinding forces were more than 40% lower under LAG than CG due to the removal mechanism of the SiC matrix changing from brittle fracture to ductile fracture and the oxidation reactions occurred in the SiCf/SiC ceramic matrix composites. Thirdly, the material removal mechanism was analysed by observing the morphology of machined surfaces, which showed that ductile removal from the SiC matrix occurs during LAG. Finally, it is also founded that the mean height of exposed abrasive grains from machined surface was reduced by 1.02 μm, 12.52 μm in LAG and CG respectively. The forms of wear caused by abrasive grains were studied. Under CG, the abrasive grains mainly exhibit cleavage fractures; while under LAG, micro-abrasion is the main wear form.

Localized Green's function using a beam-pattern for the fast modeling of 2D electromagnetic scattering

ABSTRACT This study presents an alternative approach to the numerical solution of 2D electromagnetic scattering problems using a hybrid numerical technique based on a beam pattern function combined with the method of moments (MoM). A surface field distribution with finite width radiates outward, and it is used to define the new Green's function. This new Green's function has a beam aperture localized on the surface, and its beam width can be reduced to a few basis function levels by using a generalized pencil of beam function method (GPOF). This localization of the new Green's function brings to the sparsity in the main matrix. Then, the memory storage and the overall running times are reduced significantly by applying this localized radiation of Green's function. Numerical results have been presented in both polarizations for the single perfectly electrically conducting (PEC) strip geometry and 2D PEC objects with closed polygonal cross-sections such as square, triangle and arbitrary shapes.

Opportunities and Challenges for Alternative Nanoplasmonic Metals: Magnesium and Beyond.

Materials that sustain localized surface plasmon resonances have a broad technology potential as attractive platforms for surface-enhanced spectroscopies, chemical and biological sensing, light-driven catalysis, hyperthermal cancer therapy, waveguides, and so on. Most plasmonic nanoparticles studied to date are composed of either Ag or Au, for which a vast array of synthetic approaches are available, leading to controllable size and shape. However, recently, alternative materials capable of generating plasmonically enhanced light–matter interactions have gained prominence, notably Cu, Al, In, and Mg. In this Perspective, we give an overview of the attributes of plasmonic nanostructures that lead to their potential use and how their performance is dictated by the choice of plasmonic material, emphasizing the similarities and differences between traditional and emerging plasmonic compositions. First, we discuss the materials limitation encapsulated by the dielectric function. Then, we evaluate how size and shape maneuver localized surface plasmon resonance (LSPR) energy and field distribution and address how this impacts applications. Next, biocompatibility, reactivity, and cost, all key differences underlying the potential of non-noble metals, are highlighted. We find that metals beyond Ag and Au are of competitive plasmonic quality. We argue that by thinking outside of the box, i.e., by looking at nonconventional materials such as Mg, one can broaden the frequency range and, more importantly, combine the plasmonic response with other properties essential for the implementation of plasmonic technologies.

Increasing the breakdown voltage in gate – Field plate High Electron Mobility Transistor using a surface field distribution layer and gate-drain edge passivation

We investigate the breakdown characteristics of AlGaN/GaN High Electron Mobility Transistor (HEMT) with surface field distribution layer (SFDL) and gate-drain edge passivation. We employ an SFDL to redistribute the surface electric field at the gate-drain edge. The combination of SFDL with gate-drain edge (Si3N4) passivation results in a considerable reduction in the peak electric field at the gate-drain edge, as well as a reduction in the HEMT device's gate-leakage current. The influence of field plate (FP) length on breakdown voltage is investigated and compared with our suggested HEMT. Our analysis reveals that the combined effect of SFDL and gate-drain edge passivation for optimized gate – Field Plate HEMT reduces the peak electric field at the gate-drain edge by five times and increases the breakdown voltage by three times.

Surface Field Distribution and Composite Scattering Characteristics of Three-dimensional Micro-nano Hemispherical Periodic Structure Optical Surface

Surface Field Distribution and Composite Scattering Characteristics of Three-dimensional Micro-nano Hemispherical Periodic Structure Optical Surface

Multiband reciprocal polarization insensitivity electromagnetically induced transparency in metasurfaces

A reciprocal electromagnetically induced transparency (EIT) effect is proposed in the complementary metasurface structure, which is composed of metal orthogonal strips beside a silicon substrate. The EIT effect of reciprocity is obtained whether the incident wave propagates from the positive (+z) or reverse (−z) direction. A multiband EIT window is also obtained in the structure of horizontal strip and substrate silicon as bright mode and vertical strip as dark mode by the finite difference time domain (FDTD) method. The transmission mechanism is interpreted by giving the current surface and electric field distributions at certain frequencies. A polarization insensitive EIT can be realized theoretically due to the structure is symmetrical in the x and y directions. The effective permittivity of the structure was calculated by the method of inversion to reveal the transmission spectra. These results can be applied in many areas, such as multiband slow-light devices, active sensing and bidirectional devices.

Improvement of SERS by the Optical Modulation of Photonic Crystal

Mesoporous silicon photonic crystal based composites containing silver nanoparticles are shown to provide new substrates for the improvement of SERS. The enhancement of SERS depends on the localized surface plasma resonance (LSPR) of the obtained material and the enhancement of Raman polarizability that results from the increasing interaction time of the light and matter of the multilayer structure. The electric field on the photonic crystal surface is stronger than that on the single-layer film by the finite-element time-domain method (FETD). While the surface field distribution of photonic crystals is in a narrower region from the surface than that of single-layer films. Thus, Ag nanoparticles are deposited on the two types of porous silicon samples, the enhanced electric field on the surface of photonic crystals is conducive to achieving stronger the strong LSPR response, which leads to the enhancement of Raman optical signal. SERS activity of the substrates was tested using rhodamine 6G as the probe molecules. SERS on photonic crystal device substrates are superior to that on the single-layer structure substrates, and shows a gain of five times. In addition, the enhancement of Raman signals also reduces the threshold of the detection down to $1.0\times 10^{-13}\text{M}$ . The strategy described here is a low-cost process with potential for a sensitive Raman sensor based photonic crystal for biological detection.

Electromagnetically Induced Absorption in Metamaterials and Applications in the Infrared Range

An analog of electromagnetically induced absorption is studied in a multilayer metamaterial composed of a similar double structure. The structure is designed by distributing metal rings with different radii between dielectric layers by using the finite integral time domain and effective medium method. The proposed structure exhibits near perfect narrow-band and wideband absorption, which is caused by a bright mode coupled with a dark mode. The absorption mechanism is determined from the current surface and electric field distributions at certain frequencies. The absorption of the structure is greatly influenced when the angle of incidence increases from 0° to 85°. This result can be achieved by angle or frequency select switches. The designed structure is sensitive to the surrounding refractive index, which can be applied as an environment monitor.

Design and verification of double band negative refraction metamaterial

Abstract This paper proposed a metamaterial with dual-band, wide bandwidth, high quality negative refractive band and quasi-zero refractive band. It consists of a symmetrical double-opening ring and bimetallic wire, and is verified by classical triangle method. The mechanism of dual-band negative refraction is studied, and the analysis of surface current and field distribution is completed. Through the novel test scheme, the free-space measurement of electromagnetic parameters was carried out. The test results are highly matched with the simulation results.

Optical non-reciprocity induced by asymmetrical dispersion of Tamm plasmon polaritons in terahertz magnetoplasmonic crystals.

Nonreciprocal light phenomena, including one-way wave propagation along an interface and one-way optical tunneling, are presented at terahertz frequencies in a system of magnetically controlled multi-layered structure. By varying the surface termination and the surrounding medium, it is found that the nonreciprocal bound or radiative Tamm plasmon polartions can be supported, manipulated, and well excited. Two different types of contributions to the non-reciprocity are analyzed, including the direct effect of magnetization-dependent surface terminating layer as well as violation of the periodicity in truncated multi-layered systems. Calculations on the asymmetrical dispersion relation of surface modes, field distribution, and transmission spectra through the structure are employed to confirm the theoretical results, which may potentially impact the design of tunable and compact optical isolators.

Supporting and friction properties of magnetic fluids bearings

Abstract A driblet of magnetic fluids (MFs) falls on an annular magnet, forming a closed liquid ring. The magnetized MFs can produce liquid support due to magnetostatic force. The air cushion enclosed by the MFs sealing ring may generate gas support as the magnet bottom combines with a substrate. The supporting capacity supplied by the liquid-gas contributes to friction reduction. Research shows such supporting is affected by the surface magnetic field and field distribution. Tribological results confirm that low friction can be obtained since the tribo-pairs are separated by the supporting force and the friction originates from the fluid viscosity. Such design would be significant for solving the “cold welding” as well as the “stick-slip” phenomenon, especially in precise sliding machine.

A dual-band metamaterial absorber with adjacent absorption peaks

A kind of nearly perfect metamaterials absorber (MMA) with super-close dual bands is designed and fabricated at microwave frequency. This super-compact and space saving structure integrates a cross-shaped resonator (CSR) and complementary cross-shaped resonator (CCSR) in one unit cell, corresponding to lower and higher resonances, respectively. This dual-band polarization-insensitive MMA operates well with a wide range of incident angles for TE polarization. On the other hand, the higher absorptive resonance is highly sensitive for TM polarization with oblique incident angles over 15°. Besides the surface current, field and power loss density distributions, effective material parameters are analyzed to figure out the physical mechanism of absorption. Furthermore, the influences of absorption intensity and resonant frequency by changing the geometric dimensions of the structure and thickness of the dielectric substrate have also been discussed. The experimental results agree well with numerical simulations and this definite polarization (TM) insensitive absorber with super-close bands can be applied in high sensitivitivy/resolution absorption detectors, switchable absorption devices between dual and single band, and sensors with TE or TM EM waves under oblique incidence.

The 90° Rotating Eaton Lens Synthesized by Metasurfaces

In this letter, the two-dimensional 90° rotating Eaton lens is designed and realized by flat metasurfaces. Two kinds of unit-cell metallization are employed, namely the square patch and the mushroom structure, the latter adopted to achieve the higher values of equivalent refractive indices required by the regions near the center of the circular lens. Designs by computer simulations have demonstrated the successful bending of impingent waves by right angles, via field distributions over the metasurface as well as by simulated gains towards the rotated direction. A prototype of the design was also manufactured, the measured surface field distribution and far-field radiation gain patterns of which corroborate the theoretical prediction of the lens' ability to rotate waves by 90°.

Bionic Optimization Design of Electronic Nose Chamber for Oil and Gas Detection

In this paper, a miniaturized bionic electronic nose system is developed in order to solve the problems arising in oil and gas detection for large size and inflexible operation in downhole. The bionic electronic nose chamber is designed by mimicking human nasal turbinate structure, V-groove structure on shark skin surface and flow field distribution around skin surface. The sensitivity of the bionic electronic nose system is investigated through experimentation. Radial Basis Function (RBF) and Support Vector Machines (SVM) of 10-fold cross validation are used to compare the recognition performance of the bionic electronic nose system and common one. The results show that the sensitivity of the bionic electronic nose system with bionic composite chamber (chamber B) is significantly improved compared with that with common chamber (chamber A). The recognition rate of chamber B is 4.27% higher than that of chamber A for the RBF algorithm, while for the SVM algorithm, the recognition rate of chamber B is 5.69% higher than that of chamber A. The three-dimensional simulation model of the chamber is built and verified by Computational Fluid Dynamics (CFD) simulation analysis. The number of vortices in chamber B is fewer than that in chamber A. The airflow velocity near the sensors inside chamber B is slower than that inside chamber A. The vortex intensity near the sensors in chamber B is 2.27 times as much as that in chamber A, which facilitates gas molecules to fully contact with the sensor surface and increases the intensity of sensor signal, and the contact strength and time between odorant molecules and sensor surface. Based on the theoretical investigation and test validation, it is believed that the proposed bionic electronic nose system with bionic composite chamber has potential for oil and gas detection in downhole.

Left‐handed meta‐surface loaded with ring resonator modelling for satellite application

SummaryA new geometry of compact meta‐surface, loaded with the ring resonator for satellite application (Ku‐band), is presented in this paper. The diamond‐shaped meta‐surface is designed by the metallic ring resonator with metallic ground plane separated by a dielectric substrate layer, while epoxy resin fibre is utilized as a dielectric substrate layer. The proposed meta‐surface structure is successfully simulated, fabricated, and measured. Effects of the design specifications on the surface current and field distribution are also investigated elaborately. Theoretical and simulated results show that the diamond‐shape structure resonance is at 15.84 GHz, whereas the measured results are slightly shifted around at 15.87 GHz. The designed meta‐surface structure also exhibits the left‐handed characteristics at 15.88 GHz, where the estimations of permittivity is −4 + 0.28j, permeability is −19.2 − 134.6j, and negative index is −5.51 − 3.86j. Further, the lumped element equivalent circuit model of the proposed meta‐surface unit cell is explained. Moreover, the 10 × 10 mm2 meta‐surface single‐unit‐cell prototype is compact in size and the impact on the performance by modifying the meta‐surface structure is investigated. Therefore, the meta‐surface integrated antenna shows resonance frequency bands from 14.0 to 14.50 GHz, which is used as INSAT‐4A communication satellite uplink frequency.

Quad band electric field‐driven LC resonator‐based polarisation‐insensitive metamaterial absorber

A quad band polarisation-insensitive metamaterial absorber comprising electric field-driven LC resonator has been proposed in this study. The unit cell of the proposed structure is designed with a metallic pattern on the top of a grounded dielectric substrate. The geometric parameters of the unit cell are optimised in such a way that the proposed absorber exhibits quad band absorption at C, X and Ku bands. The absorber exhibits polarisation insensitivity under normal incidence and provides high absorption for wide angles of the incident wave up to 60° for both TE and TM polarisation. The absorption mechanism has been studied by analysing the surface current and field distributions for all the four absorption frequencies. The proposed design is compact in its unit cell size and ultra-thin with a thickness of 0.019 λ 0 . Finally, a prototype of the proposed absorber structure has been fabricated and its performance is experimentally verified. The measured responses are observed in agreement with simulation results.

Uniqueness theorem and uniqueness of inverse problems for lossy anisotropic inhomogeneous structures with diagonal material tensors

The uniqueness theorem for lossy anisotropic inhomogeneous structures with diagonal material tensors is proven. For these materials, we prove that all the elements of the constitutive tensors must be lossy. Materials like cloaks and lenses designed based on transformation-optics (TO) could be examples of such materials. The uniqueness theorem is about the uniqueness of Maxwell's equations solutions for particular sets of boundary conditions. We prove the uniqueness theorem for three cases: Single medium, media composed of two lossy anisotropic inhomogeneous materials with diagonal constitutive parameters, and media composed of two materials, where a material with diagonal material tensors is surrounded by an isotropic material. The latter case can be considered for the TO-based materials like invisibility cloaks or hyper-lenses that usually have diagonal anisotropic inhomogeneous constitutive parameters and also because cloaks or hyper-lenses are usually surrounded by free space and the sources are usually outside. For the sake of our argument in the uniqueness theorem that loss is the main condition for the validity of this theory, for cloaks as an example case of our analysis, it is analytically and numerically proven that the ideal invisibility phenomenon is possible for a simple lossy structure. We also examine the uniqueness of the inverse problem for such structures. We prove that all these materials have the same surface field distribution on a surface enclosing the area of interest, while solutions to Maxwell's equations inside them are different. The uniqueness of the inverse problem suggests that within the surface, the same medium should exactly be present. However, for lossy anisotropic inhomogeneous structures with diagonal constitutive parameters, this paper illustrates that this might not be true, despite the result of a previous study that shows that uniqueness could be true for some anisotropic inhomogeneous structures. For the analysis, the transverse electric Z-polarization is used. The simulation results are obtained by using a commercial Finite-Element based simulator.

Photonic and plasmonic surface field distributions characterized with normal- and oblique-incidence multi-photon PEEM

Photonic and plasmonic fields at surfaces can have complicated spatial distributions, which are reflected in the corresponding photoelectron yields imaged in PEEM. These can include the intricate moiré patterns on the surfaces of photonic and plasmonic structures and bright fringe field patterns at their edges. Understanding field distributions requires an understanding of how the guided modes develop, propagate, and interfere with each other and with the incident far-field light. Recent efforts in PEEM include the use of normal incidence excitation in addition to or in lieu of oblique incidence to alter the yield distributions. In this paper we present three cases of surface near-fields imaged in PEEM: an indium tin oxide photonic waveguide, a large gold plasmonic patch antenna, and a small gold plasmonic slot antenna. We show that the surface fields of the waveguide are those of a dual-mode waveguide and that the fields of the plasmonic antennas arise from the asymmetric surface plasmon mode excited at the perimeter of the antennas. We analyze the photoelectron yield distributions and compare and contrast the use of normal and oblique incidence for each case.