scholarly journals Biomass from Paddy Waste Fibers as Sustainable Acoustic Material

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
A. Putra ◽  
Y. Abdullah ◽  
H. Efendy ◽  
W. M. F. W. Mohamad ◽  
N. L. Salleh
Keyword(s):  
Absorption Coefficient ◽  
Single Layer ◽  
Normal Incidence ◽  
Polyester Fabric ◽  
Glass Wool ◽  
Sample Thickness ◽  
Fiber Density ◽  
Acoustic Performance ◽  
Average Value ◽  
Absorbing Material

Utilization of biomass for green products is still progressing in the effort to provide alternative clean technology. This paper presents the utilization of natural waste fibers from paddy as acoustic material. Samples of sound absorbing material from paddy waste fibers were fabricated. The effect of the fiber density, that is, the fiber weight and the sample thickness, and also the air gap on the sound absorption coefficient is investigated through experiment. The paddy fibers are found to have good acoustic performance with normal incidence absorption coefficient greater than 0.5 from 1 kHz and can reach the average value of 0.8 above 2.5 kHz. This result is comparable against that of the commercial synthetic glass wool. Attachment of a single layer of polyester fabric is shown to further increase the absorption coefficient.

Material Parameter Determination in Glass Wool Mat for Sound Absorption

2011 ◽  
Vol 148-149 ◽  
pp. 1271-1275 ◽  
Author(s):  
Cheng Dong Li ◽  
Zhao Feng Chen ◽  
Jie Ming Zhou ◽  
Bin Bin Li ◽  
Wang Ping Wu ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Prediction Error ◽  
Fiber Length ◽  
Normal Incidence ◽  
Glass Wool ◽  
Parameter Determination ◽  
Frequency Range ◽  
Material Parameters ◽  
Refrigeration Equipment ◽  
Building Engineering

Glass wool mat is widely used in the fields of building engineering, transport facilities and refrigeration equipment. In this paper, the effect of material parameters such as density, thickness, porosity, and flow resistivity on the normal incidence absorption coefficient has been studied. In addition, fiber length is also investigated to achieve appropriate strength. The prediction error of normal incidence absorption coefficient by modified Johnson–Allard model is less than 5% in the frequency range between 800 Hz and 5 kHz. We could use the modified Johnson–Allard model to determine the parameter of glass wool mat for better development.

Sound Absorption Characteristics of Porous Steel Manufactured by Lost Carbonate Sintering

2009 ◽  
Vol 1188 ◽  
Author(s):  
Miao Lu ◽  
Carl Hopkins ◽  
Yuyuan Zhao ◽  
Gary Seiffert
Keyword(s):  
Absorption Coefficient ◽  
Pore Size ◽  
Sound Absorption ◽  
Single Layer ◽  
Normal Incidence ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Impedance Tube ◽  
Absorption Characteristics

AbstractThis paper investigates the sound absorption characteristics of porous steel samples manufactured by Lost Carbonate Sintering. Measurements of the normal incidence sound absorption coefficient were made using an impedance tube for single-layer porous steel discs and assemblies comprising four layers of porous steel discs. The sound absorption coefficient was found not to vary significantly with pore size in the range of 250-1500 μm. In general, the absorption coefficient increases with increasing frequency and increasing thickness, and peaks at specific frequencies depending on the porosity. An increase in porosity tends to increase the frequency at which the sound absorption coefficient reaches this peak. An advantage was found in using an assembly of samples with gradient porosities of 75%-70%-65%-60% as it gave higher and more uniform sound absorption coefficients than an assembly with porosities of 75%.

Acoustic Benefits of Ecofriendly Spent Tea Leaves Filled Porous Material

2017 ◽  
Vol 739 ◽  
pp. 125-134
Author(s):  
Kylie Wong ◽  
Qumrul Ahsan ◽  
Azma Putra ◽  
Sivarao Subramonian ◽  
Noraiham Mohamad ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
High Resistance ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Acoustic Property ◽  
Tea Plant ◽  
Sound Absorption Coefficient ◽  
Acoustic Performance ◽  
Absorbing Material ◽  
Tea Leaf

This paper demonstrates the feasibility of spent tea leaf (STL) fiber as an eco-friendly sound absorbing material. STL fiber is a by-product which was extracted from tea plant. STL are rich in polyphenols (tannins) which cause high resistance to fungal and termites, and high resistance to fire. In addition, STL are hollow and cellular in nature and thus perform well as acoustic and thermal insulators. Three different grades of STL were studied and the acoustic property was analyzed in terms of sound absorption coefficient and transmission loss. Experimental measurements of sound absorption coefficient in impedance tube are conducted. It was found that finest STL fiber grade exhibits better acoustic performance among others. Furthermore, the effect of latex binder on the acoustic property of STL fiber was also analyzed. Results suggest that the types of binder such as polyurethane and latex influenced the acoustic performance of STL fiber.

scholarly journals Analysis of the Influence of Thickness and Density on Acoustic Absorption of Materials Made from Used Cigarette Butts

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4524
Author(s):  
Valentín Gómez Escobar ◽  
Celia Moreno González ◽  
Guillermo Rey Gozalo
Keyword(s):  
Absorption Coefficient ◽  
Maximum Absorption ◽  
Acoustic Absorption ◽  
Acoustic Characteristics ◽  
Acoustic Performance ◽  
Varying Thickness ◽  
Cigarette Butts ◽  
Continuous Generation ◽  
Absorbing Material ◽  
Good Agreement

The effects of the density and thickness of samples made from used cigarette butts on acoustic characteristics were analyzed in this study. All the analyzed samples showed high acoustic performance, indicating that the fabrication of acoustic absorbing material may be a good use for this problematic waste (due to its toxicity, continuous generation, lack of recycling method, etc.). An increase in either density or thickness shifted the absorption characteristics of the samples to lower frequencies and increased the overall absorption. The relationships of the frequency and value of the maximum absorption coefficient with thickness and/or density were analyzed. The shift of the maximum absorption coefficient value due to varying thickness is in good agreement with previous studies.

The Sound Absorption Properties Comparison of Metal Foams and Flexible Cellular Materials

2018 ◽  
Vol 933 ◽  
pp. 357-366 ◽  
Author(s):  
Li Si Liang ◽  
Xiao Lei Wu ◽  
Na Ni Ma ◽  
Jin Jing Du ◽  
Man Bo Liu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Metal Foam ◽  
Metal Foams ◽  
Cellular Materials ◽  
Glass Wool ◽  
Sound Absorption Coefficient ◽  
Absorption Properties ◽  
Average Value ◽  
Peak Value

The third octave sound absorption coefficient testing is conducted to compare the sound absorption properties metal foam and flexible cellular materials, by using sound absorption tester with the method of trasfer function sound absorption tester with the method of trasfer function. The sound absorption mechanisms are discussed by changing the parameters of sound absorption structure, such as the thickness of matrix materials and the thickness of cavity. The results show that pearl wool and glass wool exhibited excellent sound absorption properties. The peak value of sound absorption coefficient for pearl wool reaches to 0.991, and for glass wool, 0.985. The average sound absorption coefficient for pearl wool is 0.729, and for glass wool, 0.679. Among of three metal foams, the foamed aluminum material exhibited optimum sound absorption properties, and is superior to flexible sound absorption materials. The peak value of sound absorption coefficient reaches to 0.993, and the average value reaches to 0.781. This can be attributed to the flow resistance, porosity, thickness, cavity and structure factor, which influence the sound absorption of open cell materials.

scholarly journals Air permeability and sound absorption coefficient changes from ultrasonic treatment in a cross section of Malas (Homalium foetidum)

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Chun-Won Kang ◽  
Eun-Suk Jang ◽  
Nam-Ho Lee ◽  
Sang-Sik Jang ◽  
Min Lee
Keyword(s):  
Absorption Coefficient ◽  
Ultrasonic Treatment ◽  
Sound Absorption ◽  
Gas Permeability ◽  
Treated Wood ◽  
Untreated Wood ◽  
Sound Absorption Coefficient ◽  
Permeability Constant ◽  
Average Value ◽  
Permeability Increase

AbstractWe investigated the effect of ultrasonic treatment on Malas (Homalium foetidum) gas permeability and sound absorption coefficient using the transfer function method. Results showed a longitudinal average Darcy permeability constant of 2.02 (standard deviation SD 0.72) for untreated wood and 6.15 (SD 3.07) for ultrasound-treated wood, a permeability increase of 3.04 times. We also determined the average sound absorption coefficients in the range of 50 to 6.4 kHz and NRC (noise reduction coefficient: average value of sound absorption coefficient value at 250, 500, 1000, and 2000 Hz) of untreated Malas. Those values were 0.23 (SD 0.02) and 0.13 (SD 0.01), respectively, while those of ultrasonic-treated Malas were 0.28 (SD 0.02) and 0.14 (SD 0.02), a 19.74% increase in average sound absorption coefficient.

scholarly journals The Simulation Design of Microwave Absorption Performance for the Multi-Layered Carbon-Based Nanocomposites Using Intelligent Optimization Algorithm

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1951
Author(s):  
Danfeng Zhang ◽  
Congai Han ◽  
Haiyan Zhang ◽  
Bi Zeng ◽  
Yun Zheng ◽  
...  
Keyword(s):  
Layer Structure ◽  
Optimal Solution ◽  
Single Layer ◽  
Simulation Design ◽  
Wide Bandwidth ◽  
Abc Algorithm ◽  
Bee Colony ◽  
Absorbing Material ◽  
Important Means ◽  
Carbon Based

The optimal design objectives of the microwave absorbing (MA) materials are high absorption, wide bandwidth, light weight and thin thickness. However, it is difficult for single-layer MA materials to meet all of these requirements. Constructing multi-layer structure absorbing coating is an important means to improve performance of MA materials. The carbon-based nanocomposites are excellent MA materials. In this paper, genetic algorithm (GA) and artificial bee colony algorithm (ABC) are used to optimize the design of multi-layer materials. We selected ten kinds of materials to construct the multi-layer absorbing material and optimize the performance. Two algorithms were applied to optimize the two-layer MA material with a total thickness of 3 mm, and it was found that the optimal bandwidth was 8.12 GHz and reflectivity was −53.4 dB. When three layers of MA material with the same thickness are optimized, the ultra-wide bandwidth was 10.6 GHz and ultra-high reflectivity was −84.86 dB. The bandwidth and reflectivity of the optimized material are better than the single-layer material without optimization. Comparing the GA and the ABC algorithm, the ABC algorithm can obtain the optimal solution in the shortest time and highest efficiency. At present, no such results have been reported.

Optical properties of silicene-dielectric interfaces from IR to far UV

2021 ◽  
pp. 2150235
Author(s):  
Yujun Hou ◽  
Chun Jiang
Keyword(s):  
Optical Properties ◽  
Single Layer ◽  
Normal Incidence ◽  
Complex Surface ◽  
Optical Characterization ◽  
Potential Candidate ◽  
Dielectric Interfaces ◽  
Uv Absorbers ◽  
Uv Range

Since the growth of single layer of Si has emerged, silicene became a potential candidate material to make up the disadvantage of graphene. In this paper, the complex surface conductivity is applied to characterize the properties of silicene and we investigate the optical characterization of silicene-dielectric interfaces from IR to far UV range. The silicene-Si and silicene-Ge interfaces along both parallel and perpendicular polarization directions of electromagnetic field with normal incidence are considered in this work. The optical properties of the silicene-dielectric systems proposed in this paper lay a foundation for the performance of complex silicene-based optoelectronic devices such as sensors, detectors, filters, UV absorbers and so on.

Numerical and experimental study of an active control logic for modifying the acoustic performance of single-layer panels

2021 ◽  
pp. 116608
Author(s):  
Francesco Ripamonti ◽  
Anthony Giampà ◽  
Riccardo Giona ◽  
Ling Liu ◽  
Roberto Corradi
Keyword(s):  
Experimental Study ◽  
Active Control ◽  
Single Layer ◽  
Control Logic ◽  
Acoustic Performance

scholarly journals SEASONAL VARIABILITY OF LIGHT ABSORPTION COEFFICIENT OF SURFACE WATER

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Bisman Nababan ◽  
Denny A. Wiguna ◽  
Risti E. Arhatin
Keyword(s):  
Gulf Of Mexico ◽  
Absorption Coefficient ◽  
Loop Current ◽  
Surface Absorption ◽  
Average Value ◽  
Run Off ◽  
Significant Difference ◽  
Coefficient Measurement ◽  
Northeastern Gulf Of Mexico ◽  
Offshore Region

Absorption coefficient measurement can be used in estimating water quality, optical characteristic of water column, and marine bio-optical models. The purposes of this research were to determine values and variability of sea surface absorption coefficient in the northeastern Gulf of Mexico (NEGOM) based on various seasons. The data were collected in spring, summer, and fall seasons in 1999-2000 with AC-9 instrument. The spatial distribution of absorption coefficient showed that relatively high values were generally found along the run off Missisippi, Mobile, Chochawati, Escambia, Apalachicola, and Suwannee rivers, as well as Tampa Bay. Meanwhile, relatively low values were found in offshore region. This pattern followed the distribution pattern of chlorophyll and CDOM. Based on the local region comparison of spectral average value of absorption coefficient, we found a significant difference (α = 95%) among regions with the highest value in the run off of the Mississippi and Mobile rivers, and the lowest value in the offshore region. Comparison of spectral average value of absorption coefficient among seasons at the three primary wavelengths (blue=440 nm, green=510 nm, and red=676 nm) also showed a significant difference (α = 95%) with the highest value during the summer 1999 (Su-99) and the lowest value during the spring of 2000 (Sp-00). Absorption coefficient values were influenced by oceanographic factors that varied in every season such as wind, surface currents, upwelling, the location and speed of the Loop Current, and the river discharge of fresh water into the NEGOM.Keywords: absorption coefficient, seasons, chlorophyll, CDOM, northeastern Gulf of Mexico

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