Underwater unidirectional acoustic transmission through a plate with bilateral asymmetric gratings

2018 ◽  
Vol 32 (11) ◽  
pp. 1850133 ◽  
Author(s):  
Ailing Song ◽  
Tianning Chen ◽  
Xiaopeng Wang ◽  
Yanhui Xi ◽  
Qingxuan Liang
Keyword(s):  
Displacement Field ◽  
Slit Width ◽  
Transmission Spectra ◽  
Acoustic Transmission ◽  
The Finite Element Method ◽  
Acoustic Intensity ◽  
Field Distributions ◽  
Intensity Field ◽  
Potential Applications ◽  
Ultrasonic Devices

In this paper, a novel underwater unidirectional acoustic transmission (UAT) device consisting of a plate with bilateral asymmetric gratings is proposed and numerically investigated. The transmission spectra, the acoustic intensity field distributions, and the displacement field distributions are numerically calculated based on the finite element method. The transmission spectra show that the proposed device exhibits different UAT effects in three bands. The acoustic intensity field distributions demonstrate that the proposed device can realize UAT, which agree well with the transmission spectra. The mechanism is discussed by analyzing the displacement field distributions, and the UAT is attributed to the symmetric mode excited in brass plate. Furthermore, the effects of the lattice constant, the upper slit width, and the lower slit width on bands are discussed. Our design provides a good reference for designing underwater UAT devices and has potential applications in some fields, such as medical ultrasonic devices, acoustic barrier, and noise insulation.

scholarly journals Theoretical Analysis of Terahertz Dielectric–Loaded Graphene Waveguide

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 210
Author(s):  
Da Teng ◽  
Kai Wang
Keyword(s):  
Photonic Devices ◽  
Effective Index ◽  
The Finite Element Method ◽  
Index Method ◽  
Modal Properties ◽  
Terahertz Region ◽  
Effective Index Method ◽  
Integration Density ◽  
Device Integration ◽  
Potential Applications

The waveguiding of terahertz surface plasmons by a GaAs strip-loaded graphene waveguide is investigated based on the effective-index method and the finite element method. Modal properties of the effective mode index, modal loss, and cut-off characteristics of higher order modes are investigated. By modulating the Fermi level, the modal properties of the fundamental mode could be adjusted. The accuracy of the effective-index method is verified by a comparison between the analytical results and numerical simulations. Besides the modal properties, the crosstalk between the adjacent waveguides, which determines the device integration density, is studied. The findings show that the effective-index method is highly valid for analyzing dielectric-loaded graphene plasmon waveguides in the terahertz region and may have potential applications in subwavelength tunable integrated photonic devices.

scholarly journals A Metawindow with Optimised Acoustic and Ventilation Performance

2021 ◽  
Vol 11 (7) ◽  
pp. 3168
Author(s):  
Gioia Fusaro ◽  
Xiang Yu ◽  
Zhenbo Lu ◽  
Fangsen Cui ◽  
Jian Kang
Keyword(s):  
Natural Ventilation ◽  
Noise Control ◽  
Fem Analysis ◽  
The Finite Element Method ◽  
Noise Mitigation ◽  
Acoustic Performance ◽  
Potential Applications ◽  
Ventilation Performance ◽  
Sound Reduction ◽  
Window Design

Crucial factors in window performance, such as natural ventilation and noise control, are generally conceived separately, forcing users to choose one over the other. To solve this dualism, this study aimed to develop an acoustic metamaterial (AMM) ergonomic window design to allow noise control without dependence on the natural ventilation duration and vice versa. First, the finite element method (FEM) was used to investigate the noise control performance of the acoustic metawindow (AMW) unit, followed by anechoic chamber testing, which also served as the validation of the FEM models. Furthermore, FEM analysis was used to optimise the acoustic performance and assess the ventilation potential. The numerical and experimental results exhibited an overall mean sound reduction of 15 dB within a bandwidth of 380 to 5000 Hz. A good agreement between the measured and numerical results was obtained, with a mean variation of 30%. Therefore, the AMW unit optimised acoustic performance, resulting in a higher noise reduction, especially from 50 to 500 Hz. Finally, most of the AMW unit configurations are suitable for natural ventilation, and a dynamic tuned ventilation capacity can be achieved for particular ranges by adjusting the window’s ventilation opening. The proposed designs have potential applications in building acoustics and engineering where natural ventilation and noise mitigation are required to meet regulations simultaneously.

Three-Dimensional Potential and Electric Field Distributions in HV Cable Insulation Containing Multiple Cavities

2013 ◽  
Vol 845 ◽  
pp. 372-377 ◽  
Author(s):  
Nabipour Afrouzi Hadi ◽  
Zulkurnain Abdul-Malek ◽  
Saeed Vahabi Mashak ◽  
A.R. Naderipour
Keyword(s):  
Electrical Properties ◽  
Electric Field ◽  
High Voltage ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Low Dielectric ◽  
Underground Cable ◽  
Insulation Failure ◽  
Field Distributions ◽  
Hv Cable

Cross-linked polyethylene is widely used as electrical insulation because of its excellent electrical properties such as low dielectric constant, low dielectric loss and also due to its excellent chemical resistance and mechanical flexibility. Nevertheless, the most important reason for failure of high voltage equipment is due to its insulation failure. The electrical properties of an insulator are affected by the presence of cavities within the insulating material, in particular with regard to the electric field and potential distributions. In this paper, the electric field and potential distributions in high voltage cables containing single and multiple cavities are studied. Three different insulating media, namely PE, XLPE, and PVC was modeled. COMSOL software which utilises the finite element method (FEM) was used to carry out the simulation. An 11kV underground cable was modeled in 3D for better observation and analyses of the generated voltage and field distributions. The results show that the electric field is affected by the presence of cavities in the insulation. Furthermore, the field strength and uniformity are also affected by whether cavities are radially or axially aligned, as well as the type of the insulating solid. The effect of insulator type due the presence of cavities was seen most prevalent in PVC followed by PE and then XLPE.

scholarly journals A Nanoscale Structure Based on an MIM Waveguide Coupled with a Q Resonator for Monitoring Trace Element Concentration in the Human Body

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1384
Author(s):  
Tingsong Li ◽  
Shubin Yan ◽  
Pengwei Liu ◽  
Xiaoyu Zhang ◽  
Yi Zhang ◽  
...  
Keyword(s):  
Human Body ◽  
Figure Of Merit ◽  
Refractive Index Sensor ◽  
The Finite Element Method ◽  
Transmission Characteristics ◽  
Metal Insulator Metal ◽  
Potential Applications ◽  
Internal Mechanism ◽  
Nanoscale Structure ◽  
Mim Waveguide

In this study, a nano-refractive index sensor is designed that consists of a metal–insulator–metal (MIM) waveguide with a stub-1 and an orthogon ring resonator (ORR) with a stub-2. The finite element method (FEM) was used to analyze the transmission characteristics of the system. We studied the cause and internal mechanism of Fano resonance, and optimized the transmission characteristics by changing various parameters of the structure. In our experimental data, the suitable sensitivity could reach 2260 nm/RIU with a figure of merit of 211.42. Furthermore, we studied the detection of the concentration of trace elements (such as Na+) of the structure in the human body, and its sensitivity reached 0.505 nm/mgdL−1. The structure may have other potential applications in sensors.

Semi-Analytic Solution of Multiple Inhomogeneous Inclusions and Cracks in an Infinite Space

2015 ◽  
Vol 12 (01) ◽  
pp. 1550002 ◽  
Author(s):  
Kun Zhou ◽  
Rongbing Wei ◽  
Guijun Bi ◽  
Xu Wang ◽  
Bin Song ◽  
...  
Keyword(s):  
Analytic Solution ◽  
The Finite Element Method ◽  
Infinite Space ◽  
Equivalent Inclusion Method ◽  
Equivalent Inclusion ◽  
Dislocation Densities ◽  
Distributed Dislocation ◽  
Potential Applications ◽  
Novel Method ◽  
Dislocation Technique

This work develops a semi-analytic solution for multiple inhomogeneous inclusions of arbitrary shape and cracks in an isotropic infinite space. The solution is capable of fully taking into account the interactions among any number of inhomogeneous inclusions and cracks which no reported analytic or semi-analytic solution can handle. In the solution development, a novel method combining the equivalent inclusion method (EIM) and the distributed dislocation technique (DDT) is proposed. Each inhomogeneous inclusion is modeled as a homogenous inclusion with initial eigenstrain plus unknown equivalent eigenstrain using the EIM, and each crack of mixed modes I and II is modeled as a distribution of edge climb and glide dislocations with unknown densities. All the unknown equivalent eigenstrains and dislocation densities are solved simultaneously by means of iteration using the conjugate gradient method (CGM). The fast Fourier transform algorithm is also employed to greatly improve computational efficiency. The solution is verified by the finite element method (FEM) and its capability and generality are demonstrated through the study of a few sample cases. This work has potential applications in reliability analysis of heterogeneous materials.

scholarly journals FSW Numerical Simulation of Aluminium Plates by SYSWELD - Part II

2016 ◽  
Vol 66 (2) ◽  
pp. 29-36 ◽  
Author(s):  
Roland Jančo ◽  
Ladislav Écsi ◽  
Pavel Élesztős
Keyword(s):  
Numerical Simulation ◽  
Material Flow ◽  
Complex Interaction ◽  
Fluid Simulation ◽  
Stress And Strain ◽  
The Finite Element Method ◽  
Friction Stir ◽  
Simulation Process ◽  
Potential Applications ◽  
Solid State Joining

Abstract Friction Stir Welding (FSW) is one of the most effective solid state joining processes and has numerous potential applications in many industries. The simulation process can provide the evolution of physicals quantities such as temperature, metallurgical phase proportions, stress and strain which can be easily measured during welding. The numerical modelling requires the modelling of the complex interaction between thermal, metallurgical and mechanical phenomena. The aim of this paper is to describe the thermal-fluid simulation of FSW using the finite element method. In the theoretical part of paper heating is provided by the material flow and contact condition between the tool and the welded material. Thermal-mechanical results from the numerical simulation using SYSWELD are also presented for aluminium alloy.

Application of the Finite Element Method to Linear Elastic Fracture Mechanics

1991 ◽  
Vol 44 (10) ◽  
pp. 447-461 ◽  
Author(s):  
Leslie Banks-Sills
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Displacement Field ◽  
Three Dimensional ◽  
Linear Elastic Fracture Mechanics ◽  
The Finite Element Method ◽  
Linear Elastic ◽  
Elastic Fracture

Use of the finite element method to treat two and three-dimensional linear elastic fracture mechanics problems is becoming common place. In general, the behavior of the displacement field in ordinary elements is at most quadratic or cubic, so that the stress field is at most linear or quadratic. On the other hand, the stresses in the neighborhood of a crack tip in a linear elastic material have been shown to be square root singular. Hence, the problem begins by properly modeling the stresses in the region adjacent to the crack tip with finite elements. To this end, quarter-point, singular, isoparametric elements may be employed; these will be discussed in detail. After that difficulty has been overcome, the stress intensity factor must be extracted from either the stress or displacement field or by an energy based method. Three methods are described here: displacement extrapolation, the stiffness derivative and the area and volume J-integrals. Special attention will be given to the virtual crack extension which is employed by the latter two methods. A methodology for calculating stress intensity factors in two and three-dimensional bodies will be recommended.

An optical pressure sensor based on π-shaped surface plasmon polariton resonator

2016 ◽  
Vol 30 (21) ◽  
pp. 1650284 ◽  
Author(s):  
Gaoyan Duan ◽  
Peilin Lang ◽  
Lulu Wang ◽  
Li Yu ◽  
Jinghua Xiao
Keyword(s):  
Surface Plasmon ◽  
Pressure Sensor ◽  
Surface Plasmon Polariton ◽  
High Sensitivity ◽  
Wavelength Shift ◽  
The Finite Element Method ◽  
Metal Insulator Metal ◽  
Potential Applications ◽  
Plasmon Polariton ◽  
Optical Pressure

We propose a metal–insulator–metal (MIM) structure which consists of a [Formula: see text]-shaped resonator and a surface plasmon polariton (SPP) waveguide. The finite element method (FEM) is employed in the simulation. The results show that this structure forms an optical pressure sensor. The transmission spectra have a redshift with increasing pressure, and the relation between the wavelength shift and the pressure is linear. The nanoscale pressure sensor shows a high sensitivity and may have potential applications in biological and biomedical engineering.

Sign in / Sign up

Export Citation Format

Share Document