scholarly journals Acoustic absorption mechanism and optimization of a rubber slab with cylindrical cavities

2014 ◽  
Vol 63 (13) ◽  
pp. 134303
Author(s):  
Zhao Hong-Gang ◽  
Wen Ji-Hong ◽  
Yang Hai-Bin ◽  
L Lin-Mei ◽  
Wen Xi-Sen
Keyword(s):  
Acoustic Absorption ◽  
Absorption Mechanism ◽  
Cylindrical Cavities

scholarly journals Low-frequency acoustic absorption mechanism of a viscoelastic layer with resonant cylindrical scatterers

2013 ◽  
Vol 62 (15) ◽  
pp. 154301
Author(s):  
Yang Hai-Bin ◽  
Li Yue ◽  
Zhao Hong-Gang ◽  
Wen Ji-Hong ◽  
Wen Xi-Sen
Keyword(s):  
Low Frequency ◽  
Viscoelastic Layer ◽  
Acoustic Absorption ◽  
Absorption Mechanism

scholarly journals Excess acoustic absorption attributable to the biological modification of seawater viscosity

2008 ◽  
Vol 65 (9) ◽  
pp. 1747-1750 ◽  
Author(s):  
Christopher J. Rhodes
Keyword(s):  
Rheological Properties ◽  
Acoustic Measurement ◽  
Acoustic Absorption ◽  
Absorption Mechanism ◽  
Phaeocystis Globosa ◽  
Additional Absorption ◽  
Excess Viscosity ◽  
Absorption Component ◽  
Using Data ◽  
Biological Modification

Abstract Rhodes, C. J. 2008. Excess acoustic absorption attributable to the biological modification of seawater viscosity. – ICES Journal of Marine Science, 65: 1747–1750. There is increasing evidence that a ubiquitous species of oceanic phytoplankton (Phaeocystis globosa) can significantly modify the rheological properties of seawater. The effect is seasonal and, during spring when the species multiplies rapidly, one can observe large increases in the viscosity of the seawater they inhabit. One of the principal determinants of acoustic absorption in a fluid is viscosity, so in addition to the well-understood modulations attributable to temperature- and salinity-dependent molecular relaxation, there may be an additional absorption component resulting from the presence of phytoplankton. Using data from recent measurements of biologically induced excess viscosity during blooms of P. globosa, the additional acoustic absorption attributable to the presence of this organism is estimated. This suggests that a novel, biologically induced acoustic-absorption mechanism may be observable in seawater for frequencies >100 kHz. The implications for a variety of at-sea acoustic-measurement activities are noted.

Plasmon-assisted interaction of Si with light, for cancer hyperthermia and electromagnetic energy harvest

2020 ◽  
Vol 92 (2) ◽  
pp. 20101
Author(s):  
Behnam Kheyraddini Mousavi ◽  
Morteza Rezaei Talarposhti ◽  
Farshid Karbassian ◽  
Arash Kheyraddini Mousavi
Keyword(s):  
Silicon Nanowires ◽  
Metallic Nanoparticles ◽  
Near Infrared ◽  
Optical Transition ◽  
Electromagnetic Energy ◽  
Energy Harvest ◽  
Absorption Enhancement ◽  
Ir Absorption ◽  
Absorption Mechanism ◽  
Near Ir

Metal-assisted chemical etching (MACE) is applied for fabrication of silicon nanowires (SiNWs). We have shown the effect of amorphous sheath of SiNWs by treating the nanowires with SF6 and the resulting reduction of absorption bandwidth, i.e. making SiNWs semi-transparent in near-infrared (IR). For the first time, by treating the fabricated SiNWs with copper containing HF∕H2O2∕H2O solution, we have generated crystalline nanowires with broader light absorption spectrum, up to λ = 1 μm. Both the absorption and photo-luminescence (PL) of the SiNWs are observed from visible to IR wavelengths. It is found that the SiNWs have PL at visible and near Infrared wavelengths, which may infer presence of mechanisms such as forbidden gap transitions other can involvement of plasmonic resonances. Non-radiative recombination of excitons is one of the reasons behind absorption of SiNWs. Also, on the dielectric metal interface, the absorption mechanism can be due to plasmonic dissipation or plasmon-assisted generation of excitons in the indirect band-gap material. Comparison between nanowires with and without metallic nanoparticles has revealed the effect of nanoparticles on absorption enhancement. The broader near IR absorption, paves the way for applications like hyperthermia of cancer while the optical transition in near IR also facilitates harvesting electromagnetic energy at a broad spectrum from visible to IR.

DFT Study on the Chemical Absorption Mechanism of CO2 in Diamino Protic Ionic Liquids

2021 ◽  
Vol 125 (5) ◽  
pp. 1416-1428
Author(s):  
Jing Ma ◽  
Yutong Wang ◽  
Xueqing Yang ◽  
Mingxuan Zhu ◽  
Baohe Wang
Keyword(s):  
Ionic Liquids ◽  
Dft Study ◽  
Protic Ionic Liquids ◽  
Absorption Mechanism ◽  
Chemical Absorption

Low-frequency sound absorption of a tunable multilayer composite structure

2021 ◽  
pp. 107754632110082
Author(s):  
Hanbo Shao ◽  
Jincheng He ◽  
Jiang Zhu ◽  
Guoping Chen ◽  
Huan He
Keyword(s):  
Porous Material ◽  
Absorption Coefficient ◽  
Composite Structure ◽  
Low Frequency ◽  
Acoustic Absorption ◽  
Multilayer Composite ◽  
Absorption Frequency ◽  
Acoustic Absorption Coefficient ◽  
Simulation And Experiment ◽  
Single Material

Our work investigates a tunable multilayer composite structure for applications in the area of low-frequency absorption. This acoustic device is comprised of three layers, Helmholtz cavity layer, microperforated panel layer, and the porous material layer. For the simulation and experiment in our research, the absorber can fulfill a twofold requirement: the acoustic absorption coefficient can reach near 0.8 in very low frequency (400 Hz) and the range of frequency is very wide (400–3000 Hz). In all its absorption frequency, the average of the acoustic absorption coefficient is over 0.9. Besides, the absorption coefficient can be tunable by the scalable cavity. The multilayer composite structure in our article solved the disadvantages in single material. For example, small absorption coefficient in low frequency in traditional material such as microperforated panel and porous material and narrow reduction frequency range in acoustic metamaterial such as Helmholtz cavity. The design of the composite structure in our article can have more wide application than single material. It can also give us a novel idea to produce new acoustic devices.

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