Eddy Viscosity as a Possible Acoustic Absorption Mechanism in the Ocean

Morris Schulkin

doi:10.1121/1.1918444

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

Acta Physica Sinica ◽

10.7498/aps.63.134303 ◽

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

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

Acta Physica Sinica ◽

10.7498/aps.62.154301 ◽

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

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Excess acoustic absorption attributable to the biological modification of seawater viscosity

ICES Journal of Marine Science ◽

10.1093/icesjms/fsn174 ◽

2008 ◽

Vol 65 (9) ◽

pp. 1747-1750 ◽

Cited By ~ 5

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.

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

The European Physical Journal Applied Physics ◽

10.1051/epjap/2020200071 ◽

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.

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