scholarly journals Electromagnetic Imaging of Two-Dimensional Geometries by Multipulse Interference Using the Inverse FDTD Method

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Naoki Okada ◽  
James B. Cole
Keyword(s):  
Fdtd Method ◽  
Simple Calculation ◽  
The Body ◽  
Two Dimensional ◽  
Multiple Objects ◽  
Incident Wavelength ◽  
Electromagnetic Imaging ◽  
Imaging Results ◽  
Phase Interference ◽  
Difference Time

The size, shape, and location of unknown objects in the ground and in the body can be estimated by an electromagnetic imaging technique. An imaging approach to clear detection of two-dimensional geometries is proposed in this paper. Based on the inverse finite-difference time-domain (FDTD) method, a phase interference technique using multidirectional pulses is employed. The advantage of the proposed method is that it can clearly reconstruct the geometry in a simple calculation. Sample imaging results are demonstrated. The analysis of the FDTD results shows that the detectable object size is limited by the incident wavelength and the measurement spacing and illustrates the detectability of multiple objects.

Investigation of Contact Conditions During Stamping of a Thin Plate

2020 ◽  
Author(s):  
Harshal Y. Shahare ◽  
Rohan Rajput ◽  
Puneet Tandon
Keyword(s):  
Wave Propagation ◽  
Material Properties ◽  
High Speed ◽  
Fdtd Method ◽  
Propagation Model ◽  
Transmitted Wave ◽  
Two Dimensional ◽  
Contact Conditions ◽  
Simulation Based ◽  
Difference Time

Abstract Stamping is one of the most used manufacturing processes, where real-time monitoring is quite difficult due to high speed of the mechanical press, which leads to deterioration of the accuracy of the products In the present work, a method is developed to model elastic waves propagation in solids to measure contact conditions between die and workpiece during stamping. A two-dimensional model is developed that reduces the wave propagation equations to two-dimensional equations. To simulate the wave propagation inside the die-workpiece model, the finite difference time domain (FDTD) method and modified Yee algorithm has been employed. The numerical stability of the wave propagation model is achieved through courant stability condition, i.e., Courant-Friedrichs-Lewy (CFL) number. Two cases, i.e., flat die-workpiece interface and inclined die-workpiece interface, are investigated in the present work. The elastic wave propagation is simulated with a two-dimension (2D) model of the die and workpiece using reflecting boundary conditions for different material properties. The experimental and simulation-based results of reflected and transmitted wave characteristics are compared for different materials in terms of reflected and transmitted wave height ratio and material properties such as acoustic impedance. It is found that the numerical simulation results are in good agreement with the experimental results.

Two Dimensional Photonic Filter with a Circular Resonant Cavity

2013 ◽  
Vol 712-715 ◽  
pp. 1751-1754
Author(s):  
Zhao Xia Wu ◽  
Yuan Long Shao ◽  
Wen Chao Li ◽  
Er Dan Gu
Keyword(s):  
Dielectric Constant ◽  
Resonant Cavity ◽  
Fdtd Method ◽  
Circular Ring ◽  
Two Dimensional ◽  
Transmission Characteristics ◽  
New Type ◽  
Micro Cavity ◽  
The Impact ◽  
Difference Time

A new type of the two dimensional photonic filter which includes two in-line waveguides and a circular ring resonant cavity is presented in this paper. By using Finite Difference Time Domain (FDTD) method, we calculated and demonstrated the broadband frequency response of the filter and analyzed the impact of changing the dielectric constant of the inner rods on the transmission characteristics of the filter. Compared with the transmission characteristics of a micro-cavity,our numerical results show that such a filter can transmit multiple narrowband signals simultaneously. The number of the passbands of the filter increases with the rings of inner dielectric rods in the cavity. The center wavelength of the passbands can be tuned by adjusting the dielectric constant of the whole rods and inner rods without changing the size of the cavity..

Design Two Dimensional Nanocavity Photonic Crystal Biosensor Detection in Malaria

2018 ◽  
Vol 6 (6) ◽  
pp. 16 ◽  
Author(s):  
Varsha Sharma ◽  
Vijay Laxmi Kalyani
Keyword(s):  
Photonic Crystal ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Fdtd Method ◽  
Expansion Method ◽  
Two Dimensional ◽  
Plane Wave Expansion ◽  
Plane Wave Expansion Method ◽  
Output Terminal ◽  
Difference Time

In this paper we design a two dimensional (2-D) photonic crystal based biosensor implemented by linear waveguide and nanocavity detection in malaria. The bio molecules such as a red blood cell, infected red blood cell, trapped inside the nanocavity cause transmission shift at the output terminal.  The sensing mechanism of biosensor is change in refractive index of analytes. The layout biosensor is consists a linear waveguide with a nanocavity in square symmetry For the proposed photonic based biosensor, the band gap from 2210nm to 1420 nm and input wavelength of 1550nm are used in this design. The simulation results have analysed by using the finite difference time domain (FDTD) method, bandgap calculation is performed using plane wave expansion method.

Analysis of Effective Numerical Aperture in 2-D Photonic Crystal Waveguide

2014 ◽  
Vol 979 ◽  
pp. 455-458
Author(s):  
T. Chantakit ◽  
S. Kamoldilok ◽  
K. Srinuanjan ◽  
P.P. Yupapin
Keyword(s):  
Photonic Crystal ◽  
Fiber Optics ◽  
Numerical Aperture ◽  
Two Dimensional ◽  
Photonic Crystal Waveguide ◽  
Incident Wavelength ◽  
Dimensional Photonic Crystal ◽  
Near Future ◽  
Two Dimensional Photonic Crystal ◽  
Difference Time

The effective numerical aperture calculation in two-dimensional Photonic crystal waveguide has been proposed. In this paper we present the analysis of ray optics refracted inside nanorods and at the boundaries between rods, which separates rod gap is much smaller than the incident wavelength assumed to reflect on the region. In operation, the resolving numerical aperture was compared with the finite difference time domain method via OptiFDTD software. Although numerical aperture mentioned above was found to be extremely close to fiber optics, a transmission passes though compartments of the rods are observed due to significant estimation of transmission and reflection of electric field. The compared simulation results will be discussed. By the aforementioned is that in the near future we will modify wave equation in periodic media of waveguide structures reached to the transverse electric equation of beam propagation in the two-dimensional Photonic crystal waveguide analysed.

Wavelet-Based FDTD and High Resolution Spectral Estimation for Calculation of Band Structures in Two-Dimensional Phononic Crystals

2014 ◽  
Vol 575 ◽  
pp. 108-114
Author(s):  
Zhi Zhong Yan
Keyword(s):  
High Resolution ◽  
Spectral Estimation ◽  
Phononic Crystal ◽  
Fdtd Method ◽  
Phononic Crystals ◽  
Two Dimensional ◽  
Band Structures ◽  
Time Stepping ◽  
Long Time ◽  
Difference Time

This paper discusses the wavelet-based Finite Difference Time Domain (FDTD) method and high resolution spectral estimation with a specific problem of sound wave propagation through phononic crystals. If the band structures of a phononic crystal are calculated by the traditional FDTD method combined with the fast Fourier transform (FFT), good estimation of the eigenfrequencies can only be ensured by the postprocessing of sufficiently long time series generated by a large number of FDTD iterations. In this paper, a postprocessing method based on the high-resolution spectral estimation via the Yule-Walker method is proposed to overcome the difficulty. Numerical simulation results for two-dimensional phononic crystal show that, the wavelet-based FDTD method improves the efficiency of the time stepping algorithm, and high resolution spectral estimation shows the advantages over the classic FFT-based postprocessing.

scholarly journals 2D Anisotropic Photonic Crystals of Hollow Semiconductor Nanorod with Liquid Crystals

2013 ◽  
Vol 394 ◽  
pp. 38-44
Author(s):  
Filiz Karaomerlioglu ◽  
Sevket Simsek ◽  
Amirullah M. Mamedov ◽  
Ekmel Ozbay
Keyword(s):  
Optical Properties ◽  
Photonic Crystals ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Light Wave ◽  
Fdtd Method ◽  
Two Dimensional ◽  
Plane Wave Expansion ◽  
Control Light ◽  
Difference Time

Photonic crystals (PCs) have many applications in order to control light-wave propagation. A novel type of two-dimensional anisotropic PC is investigated band gap and optical properties as a hollow semiconductor nanorod with nematicliquid crystals (LC). The PC structure composed of an anisotropic nematicLC in semiconductor square hollow nanorod is designed using the plane wave expansion (PWE) method and finite-difference time-domain (FDTD) method. It has been used 5CB (4-pentyl-4`-cyanobiphenyl) as LC core, and Tellurium (Te) as square hollow nanorod material.The PC with hollow Tenanorod with nematicLC is compared with the PC with solid Tenanorodand the PC with hollow Tenanorod.

scholarly journals Simulation of laser light focusing with two-layer dielectric microcyl-inders

2021 ◽  
Vol 45 (2) ◽  
pp. 208-213
Author(s):  
A.A. Savelyeva ◽  
E.S. Kozlova
Keyword(s):  
Focal Spot ◽  
Laser Light ◽  
Optical Axis ◽  
Fdtd Method ◽  
Circular Cross Section ◽  
Depth Of Focus ◽  
Incident Wavelength ◽  
The Core ◽  
Linearly Polarized ◽  
Difference Time

Focusing of a linearly polarized laser beam of wavelength 633 nm with two-layer dielectric microcylinders of a circular cross-section and 2-um diameter was simulated using a finite-difference time-domain (FDTD) method, implemented using the FullWAVE software. It was shown that using a cladding whose refractive index (1.8 or 1.9) is higher than that of the core (1.45), it is possible to increase the depth of focus by a factor of 2.57 multiplied by the incident wavelength and shift the focal spot position along the optical axis away from the microcylinder boundary. It was also shown that parameters of the microcylinder could be chosen in such a way that a tighter focal spot was generated, with its full width at half maximum of intensity being 2.27 of the incident wavelength. The intensity at this focus was shown to be 1.4 times higher than that at the focus generated with a homogeneous microcylinder.

scholarly journals ADE-FDTD method for study of two-dimensional electromagnetic wave propagation in lossy lorentz medium

2020 ◽  
Vol 309 ◽  
pp. 01002
Author(s):  
Bingkang Chen
Keyword(s):  
Electromagnetic Wave ◽  
Plane Electromagnetic Wave ◽  
Fdtd Method ◽  
Two Dimensional ◽  
One Dimensional ◽  
Coefficient Of Reflection ◽  
Difference Formula ◽  
Medium Layer ◽  
The Difference ◽  
Difference Time

In order to study the reflection of electromagnetic wave in Lorentz medium layer, the finite difference time domain method of auxiliary differential equation (ADE-FDTD) is used to derive the difference formula of two-dimensional TM wave propagating in lossy Lorentz medium, and the reflection coefficient of reflection field is calculated in one-dimensional case. The calculated reflection coefficients coincide very well, which shows that the derived propagation formula of two-dimensional TM wave in lossy Lorentz medium is correct. In addition, the reflection of plane electromagnetic wave by infinite high Lorentz medium layer is also simulated. The results show that the reflection of plane electromagnetic wave by Lorentz dispersive medium layer is correct.

The motions of a floating slender torus

1977 ◽  
Vol 83 (4) ◽  
pp. 721-735 ◽  
Author(s):  
J. N. Newman
Keyword(s):  
Circular Cylinder ◽  
Asymptotic Expansions ◽  
The Body ◽  
Ship Motions ◽  
Two Dimensional ◽  
Scattering Problems ◽  
Incident Wavelength ◽  
Strip Theory ◽  
Incident Waves ◽  
Body Section

The motions of a floating torus oscillating in response to incident waves are analysed under the assumptions that the incident wavelength is comparable with the radius of the body section and small compared with the larger radius of the torus. This problem serves to illustrate certain features of the strip theory for ship motions, but the axisymmetric geometry and absence of body ends greatly simplify the analysis. Matched asymptotic expansions are used, with the inner solution close to the body section composed of suitable radiation and scattering problems for the two-dimensional circular cylinder. Resonant standing-wave modes in the internal basin have a singular effect upon the hydrodynamic forces acting on the body, and its response to incident waves.

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