Negahdari Hadi, Javadpour Sirus, Moattar Faramarz
1Department of Environmental Engineering,Faculty of Natural Resources and Environment,Science and Research Branch, Islamic Azad University, Tehran, Iran.
2Department of Materials Science and Engineering,School of Engineering, Shiraz University, Shiraz, Iran.
J Environ Health Sci Eng. 2019 Jul 23;17(2):507-527. doi: 10.1007/s40201-019-00357-y. eCollection 2019 Dec.
Nowadays, noise pollution is considered a major environmental problem which has affected the health and comfort of millions of people around the world. Solving the mentioned problems need to design a new generation of acoustic barriers. Acoustics experts believe that stopping and absorbing the low-frequency sound is difficult. The aims of this study were to remove the harmful frequency in industries and cities. This study concentrates on the reduction of the noise level and increasing the mass law and resonance at low frequencies.
Sound measurement and frequency analysis did to fix the harmful frequency in the Shiraz city and in the Shiraz Gas Power Plant. COMSOL 5.3a software used for simulation. Suitable material chose for the manufacture of the sound barrier through the Cambridge engineering selection software 2013. The meta-material sound barrier made and tested in the acoustic room and in the free space. Results analyzed and optimized by Design of Experiment (DOE) and Response Surface Methodology (RSM) software. Mini Tab. 18.1 software used for Statistical Calculations. New sound barriers manufactured with adding new strategies to previous studies to improve the performance of meta-materials like beautification inspired from the flowers of nature and increasing of resonance in internal pipes.
Three mechanisms used in this scatterer model which included, resonance phenomenon, Band Gap (BG) without absorption mechanism and inner-fractal-like structure. Our technique showed an advantage to reduce at frequencies below 100 Hz without adsorbent usage. The results showed that reduced noise exposures about 17.8 dB at frequency 50 Hz, about 9.1 dB within the range of 250 Hz according to EN 1793-2 standard (Lab Test for Airborne Sound Insulation). The sound barrier reported in this work provides the best and updated solution in the field of noise control.
A novel generation of sound barriers introduced. We called this structure Interior Quasi-Fractal Sonic Crystal Acoustic Barrier (IQFSCAB). In this study, several different gaps used to remove various frequencies. It could be concluded that the outcomes of the meta-material models based on the Sonic Crystal (SC) could be used for the purpose of noise control system and could be helpful for decision-makers on the noise control legislations. Graphical abstractInteraction of waves with noise barriers and wave propagation inside periodic media is a hot topic in many branches of science and technology. The acoustic metamaterial can create green environments by reducing the low frequencies of industrial noise or traffic jam. New barrier have added a number of new strategies to previous studies in order to improve the performance of meta-materials. Our technique shows a clear advantage over to absorb at frequencies below 100 Hz without adsorbent usage. Innovative use of several different gaps and diameters for to remove various frequencies was done in this study. We called this structure IQFSACB due to fractal like interior pipes as those seen in some of the flowers in nature.
如今，噪声污染被视为一个重大的环境问题，它影响了全球数百万人的健康和舒适度。解决上述问题需要设计新一代的隔音屏障。声学专家认为，阻止和吸收低频声音很困难。本研究的目的是消除工业和城市中的有害频率。本研究专注于降低噪声水平，并在低频下提高质量定律和共振。
在设拉子市和设拉子燃气发电厂进行了声音测量和频率分析，以确定有害频率。使用COMSOL 5.3a软件进行模拟。通过剑桥工程选择软件2013选择适合制造隔音屏障的材料。制作了超材料隔音屏障，并在声学实验室和自由空间中进行测试。通过实验设计（DOE）和响应面方法（RSM）软件对结果进行分析和优化。使用Mini Tab. 18.1软件进行统计计算。制造新的隔音屏障时，在先前研究的基础上增加了新策略，以提高超材料的性能，如从自然界花朵中获得灵感进行美化以及增加内部管道的共振。
该散射体模型采用了三种机制，包括共振现象、无吸收机制的带隙（BG）和内部类分形结构。我们的技术显示出在不使用吸附剂的情况下降低100Hz以下频率噪声的优势。结果表明，根据EN 1793-2标准（空气声隔声实验室测试），在50Hz频率下噪声暴露降低了约17.8dB，在250Hz范围内降低了约9.1dB。本研究中报道的隔音屏障在噪声控制领域提供了最佳且最新的解决方案。
引入了新一代隔音屏障。我们将这种结构称为内部准分形声晶体隔音屏障（IQFSCAB）。在本研究中，使用了几种不同的间隙来消除各种频率的噪声。可以得出结论，基于声晶体（SC）的超材料模型的结果可用于噪声控制系统，并且有助于噪声控制立法的决策者。图形摘要波与隔音屏障的相互作用以及波在周期性介质中的传播是许多科学和技术分支中的热门话题。声学超材料可以通过降低工业噪声或交通拥堵的低频来创造绿色环境。新的隔音屏障在先前研究的基础上增加了许多新策略，以提高超材料的性能。我们的技术在不使用吸附剂的情况下，在100Hz以下频率吸收方面显示出明显优势。本研究创新性地使用了几种不同的间隙和直径来消除各种频率的噪声。由于其内部管道类似自然界某些花朵中的分形结构，我们将这种结构称为IQFSACB。
