Dynamically tunable ultralong photonic nanojet by a curved surface truncated dielectric microcylinder

2021 ◽  
Author(s):  
yi xing ◽  
fengfeng shu ◽  
huaming xing ◽  
yihui wu
Keyword(s):  
Finite Element Method ◽  
Electric Field Intensity ◽  
Dynamic Range ◽  
Effective Length ◽  
Full Width ◽  
Micro Particles ◽  
Photonic Nanojet ◽  
Half Height ◽  
Working Distance ◽  
Peak Electric Field

Abstract As for micro-particles (microspheres or microcylinders) that form Photonic nanojet (PNJ) in near fied,a curved truncated dielectric microcylinder structure (CSTDM) is investigated by finite element method(FEM) which can form ultralong PNJ with the longest effective length:209.49λ. We found that changing parameter h of structure can realize long dynamic range tuning of the effective length of PNJ. The effective length varies quasi-periodically with h; the law of the variation of main indicators of microcylinder are further discussed, such as the effective length,the working distance, peak electric field intensity and full width half height

Method to Detect Bolting Devices Based on Ultrasonic Guided Wave

2012 ◽  
Vol 226-228 ◽  
pp. 1906-1909
Author(s):  
Min Hui Xu ◽  
Qiao Qian Lan ◽  
Wei Jian Jin
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Theoretical Analysis ◽  
Guided Waves ◽  
Test System ◽  
Guided Wave ◽  
Effective Length ◽  
Engineering Practice ◽  
Ultrasonic Guided Wave

Bolting devices is very popular in industrial application, this paper presents a new solution aimed at the problem faced in detecting the construction quality. The solution is based on the engineering practice, and we introduce Ultrasonic Guided Wave NDT technology in the detecting process. Under laboratory conditions, Longitudinal Guided Waves are used in detecting the bolting devices, the experimental results are consistent with the theoretical analysis. At the same time, finite element method is applied into the Numerical Simulation of the propagation of Longitudinal Guided Waves in bolts, thus a test system utilized in detecting the effective length and defects of bolts developed.

scholarly journals Effect of Material Thickness on Attenuation (dB) of PTFE Using Finite Element Method at X-Band Frequency

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Abubakar Yakubu ◽  
Zulkifly Abbas ◽  
Mansor Hashim
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Electric Field ◽  
Rectangular Waveguide ◽  
Electric Field Intensity ◽  
Reflection Coefficients ◽  
Band Frequency ◽  
Ptfe Sample ◽  
X Band ◽  
Element Method

PTFE samples were prepared with different thicknesses. Their electric field intensity and distribution of the PTFE samples placed inside a rectangular waveguide were simulated using finite element method. The calculation of transmission/reflection coefficients for all samples thickness was achieved via FEM. Amongst other observable features, result from calculation using FEM showed that the attenuation for the 15 mm PTFE sample is −3.32 dB; the 30 mm thick PTFE sample has an attenuation of 0.64 dB, while the 50 mm thick PTFE sample has an attenuation of 1.97 dB. It then suffices to say that, as the thickness of the PTFE sample increases, the attenuation of the samples at the corresponding thicknesses increases.

Predicting Effective Electromechanical Properties of Pb-Free Polymer Composite Using Finite Element Method

2020 ◽  
Vol 978 ◽  
pp. 337-343
Author(s):  
Neelam Mishra ◽  
Chaitanya Shah ◽  
Kaushik Das
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Polymer Composite ◽  
Lead Zirconate Titanate ◽  
Polyvinylidene Fluoride ◽  
Volume Fraction ◽  
Lead Zirconate ◽  
Sensors And Actuators ◽  
Micro Particles ◽  
Element Method

Polyvinylidene fluoride (PVDF) – Lead Zirconate Titanate (PZT) is a polymer composite that is becoming increasingly popular in micro-scale sensors and actuators because of its unique properties such as high flexibility, low density and high piezoelectric constants. However, lead-based piezoceramics, despite their superior properties, are toxic and are known to damage the environment, and as such a conscientious effort is being made by the scientific community towards replacing lead-containing piezoceramics with environmentally-friendlier and lead-free piezoceramics. Barium Titanate (BaTiO3) is one such piezoceramics that is widely studied today to be a potential replacement of PZT in many applications. As such, in this work, effort has been made to predict the effective mechanical, dielectric and piezoelectric properties of PVDF-BaTiO3 composite system using Finite Element Method (FEM). Kinematic Uniform Boundary Conditions (Displacement and Voltage) are used for this analysis. For evaluation of the effective material constants of the composite, several types of representative volume elements are considered. The effects of volume fraction, effect of the size of the micro-particles i.e. mono-modal versus multi-modal size distribution, effect of periodic versus quasi-random distribution of microparticles in the matrix, the effect of clustering of the particles, effect of orientation of the microparticles i.e. unidirectional or randomly oriented are discussed. Finally, a comparison of properties between PVDF-PZT and PVDF-BaTiO3 is made, so as to see whether PVDF-BaTiO3 can be a potential replacement for PVDF-PZT composite.

Electric Field Analysis Based on FEM and Corona Test of 330 kV Dampers

2014 ◽  
Vol 672-674 ◽  
pp. 773-777
Author(s):  
Tian Xi Xie ◽  
Zong Ren Peng ◽  
Zhi Cheng Zhou ◽  
Yong Ma
Keyword(s):  
Finite Element Method ◽  
Electric Field ◽  
Electric Field Intensity ◽  
Computational Models ◽  
Three Dimensional ◽  
Field Analysis ◽  
Test Results ◽  
Field Distributions ◽  
Maximum Electric Field ◽  
Electric Field Analysis

At high altitudes, 330 kV dampers usually have corona discharges on their weights, which affects the lives of the surrounding residents. To suppress the corona, optimizing the structures of the dampers is a recommended measure to reduce the electric field intensities on their weights. In this paper, three-dimensional computational models of 330 kV FDN dampers were constructed to calculate the electric field distributions on their weights, based on finite element method (FEM). The structure of the small end was optimized to reduce the electric field strength on its surface. When the radius was increased from 25 to 35 mm, the maximum electric field intensity could be decreased from 2987 V/mm to 2390V/mm. According to the results, new dampers were manufactured to test their corona characteristics. The test results show that the new dampers can prevent corona discharge at altitudes below 3500 m.

Droplet–turbulence interaction in a confined polydispersed spray: effect of droplet size and flow length scales on spatial droplet–gas velocity correlations

2014 ◽  
Vol 741 ◽  
pp. 98-138 ◽  
Author(s):  
S. Sahu ◽  
Y. Hardalupas ◽  
A. M. K. P. Taylor
Keyword(s):  
Droplet Size ◽  
Gas Flow ◽  
Dynamic Range ◽  
Energy Content ◽  
Effective Length ◽  
Flow Structures ◽  
Stream Velocity ◽  
Gas Velocity ◽  
Length Scales ◽  
Velocity Fluctuations

AbstractThis paper discusses the interaction between droplets and entrained turbulent air flow in the far-downstream locations of a confined polydispersed isothermal spray. Simultaneous and planar measurements of droplet and gas velocities in the spray along with droplet size are obtained with the application of a novel experimental technique, developed by Hardalupaset al. (Exp. Fluids, vol. 49, 2010, pp. 417–434), which combines interferometric laser imaging for droplet sizing (ILIDS) with particle image velocimetry (PIV). These measurements quantified the spatial correlation coefficients of droplet–gas velocity fluctuations ($R_{dg}$) and droplet–droplet velocity fluctuations ($R_{dd}$) conditional on droplet size classes, for various separation distances, and for axial and cross-stream velocity components. At the measurement location close to the spray edge, with increasing droplet size,$R_{dg}$was found to increase in axial direction and decrease in cross-stream direction. This suggests that as the gas-phase turbulence becomes more anisotropic away from the spray axis, the gravitational influence on droplet–gas correlated motion tends to increase. The effective length scales of the correlated droplet–gas motion were evaluated and compared with that for gas and droplet motion. The role of different turbulent eddies of the gas flow on the droplet–gas interaction was examined. The flow structures were extracted using proper orthogonal decomposition (POD) of the instantaneous gas velocity data, and their contribution on the spatial droplet–gas velocity correlation was evaluated, which quantified the momentum transfer between the two phases at different length scales of the gas flow. The droplets were observed to augment turbulence for the first three POD modes (larger scales) and attenuate it for the rest of the modes (smaller scales). It has been realized that apart from droplet Stokes number and mass loading, the dynamic range of length scales of the gas flow and the relative turbulent kinetic energy content of the flow structures (POD modes) must be considered in order to conclude if the droplets enhance or reduce the carrier-phase turbulence especially at the lower wavenumbers.

Digital Least Squares Smoothing of Spectra

1974 ◽  
Vol 28 (6) ◽  
pp. 541-545 ◽  
Author(s):  
T. H. Edwards ◽  
Paul D. Willson
Keyword(s):  
Least Squares ◽  
Response Curve ◽  
Original Data ◽  
Full Width ◽  
Multiple Use ◽  
Least Squares Fitting ◽  
Significant Parameter ◽  
Half Height ◽  
Least Squares Fit ◽  
Cubic Polynomial

We show that the most significant parameter in digital smoothing of spectra by least squares fitting to a cubic polynomial is the length of the smoothing range, and to avoid loss of resolution we recommend that the smoothing range be chosen approximately 0.7 FWHH (full width at half-height) of the narrowest single lines or components. Multiple use of digital smooths is shown not to be equivalent to a least squares fit of the original data but gives nearly the same response curve in smoothing of Gaussian lines.

Simulation about Multi-Needle Electrospinning Based on Finite Element Method

2011 ◽  
Vol 332-334 ◽  
pp. 2157-2160 ◽  
Author(s):  
Ling Ling Guo ◽  
Yan Bo Liu ◽  
Yu Zheng
Keyword(s):  
Finite Element Method ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Electric Field ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Needle Diameter ◽  
Design And Manufacture

In the current study, the finite element analysis was used to simulate the change in electric field intensity due to the change of needle diameter and length, receiving distance，voltage and the spacing between needles located in a row. The resulting conclusion could be used to guide the design and manufacture of electrospinning machines at industrial scale.

scholarly journals Study on Surface Enhanced Raman Scattering of Au and Au@Al2O3 Spherical Dimers Based on 3D Finite Element Method

2020 ◽  
Author(s):  
Baoxin Yan ◽  
Yanying Zhu ◽  
Yong Wei ◽  
Huan Pei
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Electric Field ◽  
Enhancement Factor ◽  
Field Enhancement ◽  
Electric Field Enhancement ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Peak Electric Field

Abstract In this paper, the surface enhanced Raman scattering (SERS) characteristics of Au and Au@Al2O3 nanoparticle dimers were calculated and analyzed by using finite element method (3D-FEM). Firstly, the electric field enhancement factors of Au nanoparticles at the dimer gap were optimized from three aspects: the incident angle of the incident light, the radius of nanoparticle and the distance of the dimer. Then, aluminum oxide is wrapped on the Au dimer. What is different from the previous simulation is that Al2O3 shell and Au core are regarded as a whole and the total radius of Au@Al2O3 dimer is controlled to remain unchanged. By comparing the distance of Au nucleus between Au and Au@Al2O3 dimer, it is found that the electric field enhancement factor of Au@Al2O3 dimer is much greater than that of Au dimer with the increase of Al2O3 thickness. The peak electric field of Au@Al2O3 dimer moves towards the middle of the resonance peak of the two materials, but the peak electric field of Au dimer is more concentrated than that of Au dimer, so that the excitation wavelength has less influence on Raman enhancement. The maximum electric field enhancement factor 583 is reached at the shell thickness of 1 nm. Our results provide a theoretical reference for the design of SERS substrate and the extension of the research scope.

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