Acoustic Transmission Spectra in the Penrose Lattice

1995 ◽  
Vol 75 (17) ◽  
pp. 3106-3109 ◽  
Author(s):  
Taku Komuro ◽  
Keiya Shirahama ◽  
Kimitoshi Kono
Keyword(s):  
Transmission Spectra ◽  
Acoustic Transmission

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 Non-reciprocal acoustics in a viscous environment

2020 ◽  
Vol 476 (2244) ◽  
pp. 20200657
Author(s):  
Hyeonu Heo ◽  
Ezekiel Walker ◽  
Yurii Zubov ◽  
Dmitrii Shymkiv ◽  
Dylan Wages ◽  
...  
Keyword(s):  
Time Reversal ◽  
Phononic Crystal ◽  
Circular Cylinders ◽  
Inviscid Fluid ◽  
Transmission Spectra ◽  
Acoustic Transmission ◽  
Viscous Losses ◽  
Anisotropic Solid ◽  
Reported Study ◽  
Passive Acoustic

It is demonstrated that acoustic transmission through a phononic crystal with anisotropic solid scatterers becomes non-reciprocal if the background fluid is viscous. In an ideal (inviscid) fluid, the transmission along the direction of broken P symmetry is asymmetric. This asymmetry is compatible with reciprocity since time-reversal symmetry ( T symmetry) holds. Viscous losses break T symmetry, adding a non-reciprocal contribution to the transmission coefficient. The non-reciprocal transmission spectra for a phononic crystal of metallic circular cylinders in water are experimentally obtained and analysed. The surfaces of the cylinders were specially processed in order to weakly break P symmetry and increase viscous losses through manipulation of surface features. Subsequently, the non-reciprocal part of transmission is separated from its asymmetric reciprocal part in numerically simulated transmission spectra. The level of non-reciprocity is in agreement with the measure of broken P symmetry. The reported study contradicts commonly accepted opinion that linear dissipation cannot be a reason leading to non-reciprocity. It also opens a way for engineering passive acoustic diodes exploring the natural viscosity of any fluid as a factor leading to non-reciprocity.

Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite

2020 ◽  
Vol 92 (1) ◽  
pp. 10901
Author(s):  
Saloua El Asri ◽  
Hamid Ahamdane ◽  
Lahoucine Hajji ◽  
Mohamed El Hadri ◽  
Moulay Ahmed El Idrissi Raghni ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Single Phase ◽  
Sol Gel ◽  
Complex Impedance ◽  
Transmission Spectra ◽  
Electrical Measurements ◽  
Cation Type ◽  
Edx Analyses ◽  
The Fourier Transform

Forsterite single phase powder Mg2SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2SiO4. The formation of forsterite started at 680–740  °C and at 630–700  °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.

Software system for numerical simulation of broadband laser gas analysis of the atmosphere

2018 ◽  
pp. 66-73 ◽  
Author(s):  
S. A. Sadovnikov
Keyword(s):  
Numerical Simulation ◽  
Laser Radiation ◽  
Gas Analysis ◽  
Modular System ◽  
Software System ◽  
Transmission Spectra ◽  
Molecular Absorption ◽  
Molecular Scattering ◽  
Atmospheric Transmission ◽  
Wide Range

Introduction: Successful monitoring of environmental parameters requires the development of flexible software complexes with evolvable calculation functionality. Purpose: Developing a modular system for numerical simulation of atmospheric laser gas analysis. Results: Based on differential absorption method, a software system has been developed which provides the calculation of molecular absorption cross-sections, molecular absorption coefficients, atmospheric transmission spectra, and lidar signals. Absorption line contours are calculated using the Voigt profile. The prior information sources are HITRAN spectroscopic databases and statistical models of the distribution of temperature, pressure and gas components in the atmosphere. For modeling lidar signals, software blocks of calculating the molecular scattering coefficient and aerosol absorption/scattering coefficients were developed. For testing the applicability of various laser sources in the problems of environmental monitoring of the atmosphere, a concentration reconstruction error calculation block was developed for the atmospheric gas components, ignoring the interfering absorption of laser radiation by foreign gases. To verify the correct functioning of the software, a program block was developed for comparing the results of the modeling of atmospheric absorption and transmission spectra by using the standard SPECTRA information system. The discrepancy between the calculation of the atmospheric transmission spectra obtained using the developed system as compared to the SPECTRA results is less than 1%. Thus, a set of the presented program blocks allows you to carry out complex modeling of remote atmospheric gas analysis. Practical relevance: The software complex allows you to rapidly assess the possibilities of using a wide range of laser radiation sources for the problems of remote gas analysis.

Tunable asymmetric acoustic transmission via binary metasurface and zero-index metamaterials

2021 ◽  
Vol 118 (11) ◽  
pp. 113501
Author(s):  
Zhongming Gu ◽  
Xinsheng Fang ◽  
Tuo Liu ◽  
He Gao ◽  
Shanjun Liang ◽  
...  
Keyword(s):  
Acoustic Transmission ◽  
Zero Index

scholarly journals Visual Comfort Analysis of Semi-Transparent Perovskite Based Building Integrated Photovoltaic Window for Hot Desert Climate (Riyadh, Saudi Arabia)

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1043 ◽  
Author(s):  
Aritra Ghosh ◽  
Abdelhakim Mesloub ◽  
Mabrouk Touahmia ◽  
Meriem Ajmi
Keyword(s):  
Saudi Arabia ◽  
Cognitive Performance ◽  
Office Building ◽  
Transmission Range ◽  
Transmission Spectra ◽  
Visual Comfort ◽  
Building Integrated Photovoltaic ◽  
Transparent Windows ◽  
Desert Climate

Buildings consume considerable amount of energy to maintain comfortable interior. By allowing daylight, visual comfort inside a building is possible which can enhance the occupant’s health, mood and cognitive performance. However, traditional highly transparent windows should be replaced with semitransparent type window to attain a comfortable daylight inside a building. Evaluation of visual comfort includes both daylight glare and colour comfort analysis. Building integrated photovoltaic (BIPV) type windows are promising systems and can possess a range of semitransparent levels depending on the type of PV used. In this work, the semitransparent Perovskite BIPV windows was investigated by employing daylight glare analysis for an office building located in Riyadh, KSA and three wavelength dependent transmission spectra for colour comfort analysis. The results showed that the transmissions range between 50–70% was optimum for the comfortable daylight for south facing vertical pane BPV-windows. However, excellent colour comfort was attained for the transmission range of 90% which provided glare issues. Colour comfort for 20% transparent Perovskite was compared with contemporary other type of PV which clearly indicated that wavelength dependent transmittance is stronger over single value transmittance.

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