- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Evaluating Scattered Electromagnetic Field from Fractal Surface Using its Components
摘要： In this paper, a novel method is proposed to evaluate the scattered field from rough surfaces by decomposition-reconstitution. The extended boundary condition method (EBCM) is employed in conjunction with a Weierstrass Mandelbrot (WM) function for fractal surface profile and its components. WM function can be decomposed into a series of sinusoidal profile. The properties of the sinusoidal profile and WM function to be periodic and almost periodic allow the deriving respective amplitudes of the scattered Floquet modes. The superposition of scattered fields from each sinusoidal component is consistent with the scattered field from WM surface. The result has compared with AIEM in backscattering coefficients. Thus, by calculating the scattered information for each sinusoidal component of the rough surface, we can obtain the overall scattered field.
关键词： Fractal,Scattered field superposition,Rough surface decomposition,Extended Boundary Condition Method,Electromagnetic Scattering
更新于2025-09-10 09:29:36
-
Understanding and predicting geometrical constraint ferroelectric charged domain walls in a BiFeO <sub/>3</sub> island via phase-field simulations
摘要： It has been known that ferroelectric charged domain walls (CDWs), which break the polarization continuity, may be electrically active with an elevated conductivity. However, the bound charge at CDWs may render them energetically unstable, and thus, forming CDWs naturally and manipulating them electrically is still challenging. Here, we theoretically utilize phase-field simulations to design spontaneously generated CDWs with center-type quad-domains in a single square-shaped BiFeO3 nanoisland. It is shown that the stability of the spontaneously emerging head-to-head domain walls with center-convergent quad-domains is mainly determined by three contributions, namely, the geometrical constraint from approximately 45°-tilted bottom edges, the electric boundary condition, and the necessary screening free charges to compensate head-to-head domain walls. It is demonstrated that the center-convergent quad-domains with head-to-head CDWs can be electrically switched to the center-divergent one with tail-to-tail CDWs, providing guidance for achieving ferroelectric domain-wall-based nanodevices with low-power dissipation.
关键词： phase-field simulations,electric boundary condition,ferroelectric charged domain walls,BiFeO3,screening free charges,geometrical constraint
更新于2025-09-10 09:29:36
-
Insight into phonon scattering in Si nanowires through high-field hole transport: Impacts of boundary condition and comparison with bulk phonon approximation
摘要： The impact of how to model phonon scattering on hole transport in Si nanowires was studied based on Boltzmann’s transport equation. Boundary conditions for atomistic description of phonons in nanowires and approximation by bulk acoustic and optical phonons were analyzed in terms of their impacts on high-field hole transport. The boundary conditions for phonons influence the drift velocity and momentum relaxation time, especially at low electric field, but the energy relaxation time hardly depends on the boundary conditions. The impacts by the change of boundary conditions can be approximated by the change of the strength of acoustic phonon scattering in bulk phonon picture, though the behavior of energy relaxation and distribution function of holes can not be reproduced by bulk phonon approximation.
关键词： Si nanowires,boundary condition,bulk phonon approximation,phonon scattering,high-field hole transport
更新于2025-09-10 09:29:36
-
[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Hybrid Physical Optics-Ray Tracing Method for the RCS Calculation of Electrically Large Objects Covered with Radar Absorbing Materials
摘要： A hybrid method based on Ray Tracing and Physical Optics for the estimation of the radar cross section of large metallic targets covered with radar absorbing materials is presented. The reflection coefficient of the multilayer structure composed by the metallic layer covered with radar absorbing materials is analytically evaluated through a transmission line model. The accuracy of the Radar Cross Section estimation is validated by full-wave simulations based on the Method of Moments. A corner reflector coated with Radar Absorbing Material (RAM) is used as a test-case of the proposed method. The obtained results exhibit a good agreement if compared against full-wave simulations.
关键词： Physical Optics (PO),Impedance Boundary Condition (IBC),Ray Tracing (RT),Radar Absorbing Material (RAM),Frequency Selective Surface (FSS)
更新于2025-09-04 15:30:14