scholarly journals Study of Acoustic Waves in a Teaching Classroom using Finite Element Method

2021 ◽  
pp. 65-75
Author(s):  
C. A. Wilson Bárcenas ◽  
J. M. Horta Rangel ◽  
M. A. Pérez Lara y Hernández ◽  
J. B. Hernández Zaragoza ◽  
M. L. Pérez Rea ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Acoustic Waves ◽  
Continuous Medium ◽  
The Finite Element Method ◽  
Computational Tools ◽  
Internal Surfaces ◽  
Engineering Department ◽  
Acoustic Physics ◽  
Element Method

Aims: To understand the behavior of acoustic waves in a specific classroom in order to get a configuration of panels and ceilings configuration to improve reception and clarity of internal sounds. This was possible by the modification of the properties of the enclosure, sush as the absorption coefficients of internal surfaces. The analysis was carried out through the implementation of a model by using Finite Element Method. Study Design: The acoustic behavior that enclosure for academic use require is discussed, indicating that it is common to find deficiencies in the acoustic architecture of enclosures, and the risks that this causes to cognitive and academic development, as a consequence of low understanding. Place and Duration of Study: Graduate Engineering Department, Universidad Autónoma de Querétaro, between August 2020 and June 2021. Methodology: The problem is solved by applying the finite element method. This implies that the essential concepts for the understanding of this subject are reviewed, such as; acoustic physics, mechanics of the continuous medium and finite element method. Results: After multiple analized scenarios, it was observed that while there is an absorption greater than the surface, the material of the panel or ceiling is not relevant. On the other hand, the size and surface where is located the panels turned out to be more relevant parameters. Conclusion: Considering the proposed alternatives, an increase in the Sound Pressure Level and a uniform distribution can be observed. The use of computational tools help to understand the behavior and distribution of acoustic waves in the classroom, which can provide an overview of different adaptations.

Ladder Type of Leaky Surface Acoustic Waves Filters on Substrate of Lithium Niobate

2021 ◽  
Vol 23 (3) ◽  
pp. 139-147
Author(s):  
A.S. Koigerov ◽  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Acoustic Waves ◽  
Communication Systems ◽  
Surface Acoustic Waves ◽  
Bandpass Filters ◽  
The Finite Element Method ◽  
Frequency Responses ◽  
Method Of Extraction ◽  
Element Method

High requirements on the electrical parameters of the filters are made in wireless radio communication systems. A number of tasks require bandpass filters with relative bandwidths of 8-12 %. In this case, the filter must have insertion losses of not more than 10 dB, have a rejection is not worse than 40 dB, unevenness in the bandwidth of not more than 1 dB. In addition, the amplitude frequency responses of the filter must have steep slopes due to the closely spaced frequency bands of neighboring communication systems. Due to its small size and other advantages, ladder resonator filters on surface acoustic waves are widely used in communication systems. To realize the high requirements of this type of filters, it is necessary not only to select all the topology parameters of the individual resonators included in the filter very accurately, but also to have a good computational theory and the necessary material parameters for the selected model at the design stage. Purpose: to show on the example of comparison of calculated and experimental frequency responses of ladder filters the validity of the method of extraction of the necessary parameters obtained for an infinite periodic structure by the finite element method for calculating of finite structures of real inter digital transducer and reflective gratings. Results: the method of extraction of parameters necessary for calculation by the method of connected modes on the basis of P-matrices is offered. The technique is based on the analysis of infinite periodic electrodes by the finite element method. Bandpass filters with a relative bandwidth 8-12 % on a piezosubstrate 49° YX LiNbO3 were designed and manufactured based on the proposed theory. It is shown that for this material, the calculation must take into account the direct radiation of bulk acoustic waves, since the design of ladder type filters, the radiation falls into the projected bandwidth of the filters. These calculations are confirmed by the results of experiments.

ANALYSIS OF SAW EXCITATION AND PROPAGATION UNDER PERIODIC METALLIC GRATING STRUCTURES

2000 ◽  
Vol 10 (03) ◽  
pp. 685-734 ◽  
Author(s):  
KEN-YA HASHIMOTO ◽  
TATSUYA OMORI ◽  
MASATSUNE YAMAGUCHI
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Field Analysis ◽  
The Finite Element Method ◽  
Numerical Techniques ◽  
Metallic Grating ◽  
Propagation Properties ◽  
Element Method

This paper reviews numerical techniques used for the analysis of excitation and propagation properties of surface acoustic waves (SAWs) under periodic metallic grating structures. First, the finite element method (FEM), the boundary element method (BEM) and the spectral domain analysis (SDA) are compared for the SAW field analysis. Then it is shown how skillfully excitation and propagation properties are characterized by using the FEM/SDA technique. Extended FEM/SDA theories are also detailed for the analysis of multi-finger grating structures.

Simulation of tuning graphene plasmonic behaviors by ferroelectric domains for self-driven infrared photodetector applications

Nanoscale ◽  
2019 ◽  
Vol 11 (43) ◽  
pp. 20868-20875 ◽  
Author(s):  
Junxiong Guo ◽  
Yu Liu ◽  
Yuan Lin ◽  
Yu Tian ◽  
Jinxing Zhang ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Interfacial Effect ◽  
Infrared Photodetector ◽  
The Finite Element Method ◽  
Ferroelectric Domains ◽  
Element Method

We propose a graphene plasmonic infrared photodetector tuned by ferroelectric domains and investigate the interfacial effect using the finite element method.

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