- 标题
- 摘要
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- 实验方案
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UPML-ABC of dispersive materials for the unconditionally stable 2-D WLP-FDTD method
摘要： In this paper, uniaxial anisotropic perfectly matched layer (UPML) absorbing boundary condition (ABC) of dispersive materials is presented for 2-D finite-difference time-domain (FDTD) method with weighted Laguerre polynomials (WLP). Taking advantage of the auxiliary differential equation (ADE) technique, our proposed algorithm avoids not only the complicated formulations but also the convolution integral. Using ADE scheme, the relationship between field components and auxiliary differential variables is derived in Laguerre domain. Substituting auxiliary differential variables into UPML-ABC, the electric field E of order q can be expressed directly by magnetic field H in Laguerre domain. Inserting magnetic field H of order q into electric field, and using central difference scheme, the formulations of uniaxial anisotropic dispersive media PML are obtained. One numerical example of wave propagation in 2-D dispersive materials is simulated. Numerical results validate the efficiency of the presented method.
关键词： finite-difference time-domain (FDTD),weighted laguerre polynomials (WLP),uniaxial anisotropic dispersive materials,perfectly matched layer (PML),Auxiliary differential equation (ADE)
更新于2025-09-23 15:23:52
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An Enzyme-free “ON-OFF” Electrochemiluminescence Biosensor for Ultrasensitive Detection of PML/RARα based on Target-Switched DNA Nanotweezer
摘要： Herein, an enzyme-free "ON-OFF" electrochemiluminescence (ECL) biosensor for ultrasensitive detection of fusion gene PML/RARα is constructed based on a simple target-switched DNA nanotweezer as hemin concentration controller. In this biosensor, the hemin concentration is primarily controlled by the conversion of "opened-closed" DNA nanotweezers and low concentration hemin is first used as electrochemically regenerable enhancer. In the absence of the target, the nanotweezers are in an opened state which lead to a low concentration of hemin in the solution, resulting in an enhanced Ru(bpy)3 2+ ECL signal. In the presence of the target, the closed nanotweezers absorbed onto the surface of electrode can capture the hemin, which achieves a high concentration of hemin and then quenches the ECL signal. The developed method achieves ultrasensitive detection of PML/RARα with a wide linear range from 1 fM to 1 nM and limit of detection as low as 0.125 fM. In addition, the ECL biosensor shows excellent specificity to the other subtypes of PML/RARα (subtype "S", "V", "PML" and "RARα"). Moreover, due to the high designable character of DNA nanotweezer, this method might provide a pragmatic Ru(bpy)3 2+ ECL platform for ultrasensitive detection of nucleic acid in the future.
关键词： Hemin,DNA nanotweezer,Enzyme-free,Electrochemiluminescence,PML/RARα
更新于2025-09-23 15:22:29
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A Domain Decomposition Finite Element Method for Modeling Electromagnetic Scattering from Rough Sea Surfaces with Emphasis on Near-Forward Scattering
摘要： A high fidelity full-wave simulator is presented to perform numerical experiments for rough sea scattering problem by considering different polarizations, frequencies, grazing angles, wind speeds and sea surface spectra. The simulator is based on a novel Finite Element Domain Decomposition (FEDD) method for solving the problem of two dimensional electromagnetic scattering over one-dimensional sea surface. This non-iterative method partitions the computational domain into a number of overlapping subdomains and solves each domain individually by employing the Locally-Conformal Perfectly Matched Layer (LC-PML) at the truncation boundaries. LC-PML has a unique feature such that it can be applied to irregular domains on the contrary to standard PML methods, and hence inspired the birth of FEDD. The FEDD method is used at each Monte Carlo realization corresponding to a sample from random rough surfaces, and decreases the computational load especially for electrically-large problems. The accuracy and computational efficiency of the method is investigated through several simulations. Using the FEDD method, the statistical behavior of the bistatic Radar Cross Section (RCS) is obtained for both horizontal and vertical polarizations. A special emphasis is given to forward-scattered RCS and the mean reflection coefficient for sea surface especially at low grazing angles, and it is shown that the simulator produces results in agreement with the Ament and Miller-Brown approximations, and experimental data, proving the reliability of the simulation approach. The results are also compared with the standard finite element method and method of moments. Rough sea surfaces are created by using both Pierson-Moskowitz and Elfouhaily spectra.
关键词： Locally-Conformal Perfectly Matched Layer (PML),forward scattering,sea surface,Domain decomposition,Monte Carlo,rough surface scattering,Finite Element Method (FEM),propagation,reflection coefficient,bistatic Radar Cross Section (RCS),multipath
更新于2025-09-23 15:21:21
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Error analysis of PML-FEM approximations for the Helmholtz equation in waveguides
摘要： In this paper, we study ?nite element approximate solutions to the Helmholtz equation in waveguides by using a perfectly matched layer (PML). The PML is de?ned in terms of a piecewise linear coordinate stretching function with two parameters for absorbing propagating and evanescent components respectively, and truncated with a Neumann condition on an arti?cial boundary rather than a Dirichlet condition for cuto? modes that waveguides may allow. In the ?nite element analysis for the PML problem, we have to deal with two di?culties arising from the lack of full regularity of PML solutions and the anisotropic nature of the PML problem with, in particular, large PML damping parameters. Anisotropic ?nite element meshes in the PML regions depending on the damping parameters are used to handle anisotropy of the PML problem. As a main goal, we establish quasi-optimal a priori error estimates, that does not depend on anisotropy of the PML problem (when no cuto? mode is involved), including the exponentially convergent PML error with respect to the width and the strength of PML. The numerical experiments that con?rm the convergence analysis will be presented.
关键词： PML,Helmholtz equation,waveguide,?nite element method
更新于2025-09-23 15:19:57
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Perfusion und Spektroskopie in der multimodalen Bildgebung der progressiven multifokalen Leukenzephalopathie
摘要： Die progressive multifokale Leukenzephalopathie (PML) ist eine seltene Erkrankung, die zur Demyelinisierung des zentralen Nervensystems führt. Diese wird ausgel?st durch eine Reaktivierung des John-Cunningham-Virus (JC-Virus) in den Oligodendrozyten, welches bei etwa 50 % der Menschen in der Allgemeinbev?lkerung nachweisbar ist und nur bei einer Immundefizienz eine PML bedingen kann. Typische Ursachen der PML sind deswegen eine HIV-Infektion, h?matologische Erkrankungen oder – heutzutage von besonderer Wichtigkeit – die immunsuppressive Therapie, wie die Natalizumab-Therapie der multiplen Sklerose. Die Diagnosestellung kann aufgrund der Vielzahl von m?glichen Differenzialdiagnosen erschwert sein, ist jedoch für den Patienten von gro?er Therapierelevanz.
关键词： John-Cunningham-Virus,Spektroskopie,Perfusion,progressive multifokale Leukenzephalopathie,JC-Virus,Immunsuppression,PML,Natalizumab-Therapie,multimodale Bildgebung
更新于2025-09-10 09:29:36
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Machine Learning Based PML for the FDTD Method
摘要： In this paper, a novel absorbing boundary condition (ABC) computation method for Finite-Difference Time-Domain (FDTD) is proposed based on the machine learning approach. The hyperbolic tangent basis function (HTBF) neural network is introduced to replace traditional perfectly matched layer (PML) ABC during the FDTD solving process. The field data on the interface of conventional PML are employed to train HTBF based PML model. Compared to the conventional approach, the novel method greatly decreases the size of computation domain and the computation complexity of FDTD because the new model only involves the one-cell boundary layer. Numerical examples are provided to benchmark the performance of the proposed method. The results demonstrate that the newly proposed method could replace conventional PML and could be integrated into FDTD solving process with satisfactory accuracy and compatibility to FDTD. According to our knowledge, this proposed model combined ANN model is an unreported new approach based on machine learning based for FDTD.
关键词： PML,machine learning,FDTD,HTBF neural network
更新于2025-09-09 09:28:46
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The implementation of unconditionally stable higher order PML based on the implicit CNAD-FDTD algorithm
摘要： An unconditionally stable implementation of the higher order complex frequency-shifted perfectly matched layer (CFS-PML) based on the Crank–Nicolson-approximate-decoupling (CNAD) algorithm and the bilinear transform (BT) method is proposed to terminate the finite-difference time-domain (FDTD) lattice. The proposed scheme not only takes advantage of the CNAD algorithm in terms of reducing computational time but also has the advantage of the conventional FDTD algorithm in terms of absorbing performance. Two numerical examples are provided to validate the proposed implementation in the homogenous free space and lossy FDTD domains. The results show that the proposed scheme can overcome the Courant–Friedrich–Levy condition compared with the conventional FDTD method and further enhance the absorbing performance compared with the first order PML implementation.
关键词： finite-di?erence time-domain (FDTD),Bilinear transform (BT),Crank-Nicolson-approximate-decoupling (CNAD),complex frequency-shifted perfectly matched layer (CFS-PML)
更新于2025-09-04 15:30:14
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[IEEE 2018 Global Smart Industry Conference (GloSIC) - Chelyabinsk, Russia (2018.11.13-2018.11.15)] 2018 Global Smart Industry Conference (GloSIC) - Numerical Simulation of the Transverse and Longitudinal Shifts of Reflected Beam
摘要： The effects of the spin-orbit interaction of light are observed at the wavelength scale and can be used in nanophotonics. The computer simulation of these effects is a necessary tool for creating devices, based on the spin-orbit interaction of light. We have developed a software package in Python to simulate two known effects, namely, transverse and longitudinal shifts of the center of gravity of beams at the total internal reflection. The package is based on the algorithm for the numerical solution of Maxwell's equations by the finite difference time domain method. We have used the modification of PML – UPML as absorbing boundary conditions. We simulated the refraction and total internal reflection of an electromagnetic wave at the plane interface between two transparent dielectrics and calculated the depth of penetration of a non-uniform electromagnetic wave, occurring at total internal reflection in the optically less dense medium. To test the software package, we have compared the reflection coefficients of the electromagnetic wave for the normal and oblique incidence on the plane interface, calculated by the simulation with the coefficients, obtained by Fresnel formulas for the s-polarization of the wave. We have numerically simulated the shifts of the center of gravity of beams of finite size in the plane of incidence and perpendicular to it, namely, the effects of Goos-H?nchen and Fedorov. The dependence of the direction of the transverse shift on the sign of the circular polarization of the incident beam was demonstrated. The dependence of the longitudinal shift on the direction of linear polarization is also demonstrated. It should be stressed that the developed software package can be applied for simulating of the longitudinal and transverse shifts in anisotropic media, media with optical activity, as well as thin films on the dielectric surface.
关键词： Goos-H?nchen effect,Fedorov-Imbert effect,spin-orbit interaction of light,FDTD,PML
更新于2025-09-04 15:30:14