The Comparison of Bottom Parameter Inversion in Geoacoustic Space and in (P,Q) Space

2017 ◽  
Vol 25 (02) ◽  
pp. 1750011 ◽  
Author(s):  
Z. D. Zhao ◽  
E. C. Shang ◽  
Daniel Rouseff
Keyword(s):  
Sound Speed ◽  
Shift Parameter ◽  
Matched Field Processing ◽  
Acoustical Properties ◽  
Model Free ◽  
Parameter Inversion ◽  
Sea Bottom ◽  
Potential Possibility ◽  
Profile Estimation

The acoustical properties of the sea-bottom can be described by geoacoustic (GA) parameters or by reflective parameters: [Formula: see text] (phase shift parameter) and [Formula: see text] (absorption parameter). Both in GA space and in ([Formula: see text], [Formula: see text]) space, the parameters are difficult to measure and are instead estimated by inversion methods such as matched field inversion (MFI). In GA space, an assumed model is needed to mount the GA parameters for inverting (model dependent), while the reflective parameters ([Formula: see text], [Formula: see text] are model-free. In this paper, the efficiency and quality of matched field processing (MFP) in GA space as well as in ([Formula: see text]) space are compared and the potential possibility of bottom sound-speed-profile estimation is discussed.

ANALYSIS OF SOUND SPEED IN LONGITUDINAL DIRECTION AT REFERENCE MOISTURE CONTENT (w = 12 %) IN SAWMILL ASSORTMENTS (FAGUS SYLVATICA, L.)

Akustika ◽  
2020 ◽  
pp. 45-50
Author(s):  
Alena Rohanová
Keyword(s):  
Moisture Content ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Sound Speed ◽  
Longitudinal Direction ◽  
Structural Timber ◽  
Sound Speeds ◽  
Dynamic Modulus Of Elasticity ◽  
Round Timber

This paper explores the analysis of sound speeds in the longitudinal direction and their reduction to the reference moisture content w = 12 %. The sound speed cw was determined with Sylvatest Duo device. Moisture content of beech sawmill assortments (round timber: N = 16, logs: N = 2 × 16, structural boards: N = 54) in the range of 12 – 72 % was measured. For the analysis purposes, the sound speed was converted to reference conditions (c12, uref = 12%). A second-degree polynomial (parabola) with a regression equation of the form: c// = 5649 - 27,371 × w + 0.0735 × w2 was used to convert cw to c12, and correction of measured and calculated values was used as well. The sound speeds c12 in sawmill assortments (c12,round, c12,log, c12,board) were evaluated by linear dependences. Dependence was not confirmed for c12,round and c12,board1 (r = 0.168), in contrast for c12,round and c12,log2 the dependence is statistically very significant (r = 0.634). The results of testing showed that the most suitable procedure for predicting quality of structural timber is the first step round timber – log2, the second step: log2 - board2. More exact results of the construction boards were obtained from log2 than from log1. The sound speed is used in the calculation of dynamic modulus of elasticity (Edyn). EN 408 mentions the possibility of using dynamic modulus of elasticity as an alternative method in predicting the quality of structural timber.

ИССЛЕДОВАНИЯ АКУСТИЧЕСКИХ ХАРАКТЕРИСТИК ВЕРХНЕГО СЛОЯ МОРЯ МЕТОДОМ МНОГОЧАСТОТНОГО АКУСТИЧЕСКОГО ЗОНДИРОВАНИЯ

2020 ◽  
Author(s):  
V.A. Bulanov ◽  
I.V. Korskov ◽  
A.V. Storozhenko ◽  
S.N. Sosedko
Keyword(s):  
High Frequency ◽  
Wave Motion ◽  
High Spatial Resolution ◽  
Wind Waves ◽  
Acoustic Parameter ◽  
Sea Surface ◽  
Near Surface ◽  
Acoustical Properties ◽  
Acoustic Spectroscopy ◽  
Sea Bottom

Описано применение акустического зондирования для исследования акустических характеристик верхнего слоя моря с использованием широкополосных остронаправленных инвертированных излучателей,устанавливаемых на дно. В основу метода положен принцип регистрации обратного рассеяния и отраженияот поверхности моря акустических импульсов с различной частотой, позволяющий одновременно измерятьрассеяние и поглощение звука и нелинейный акустический параметр морской воды. Многочастотное зондирование позволяет реализовать акустическую спектроскопию пузырьков в приповерхностных слоях моря,проводить оценку газосодержания и получать данные о спектре поверхностного волнения при различных состояниях моря вплоть до штормовых. Применение остронаправленных высокочастотных пучков ультразвукапозволяет разделить информацию о планктоне и пузырьках и определить с высоким пространственным разрешением структуру пузырьковых облаков, образующихся при обрушении ветровых волн, и структуру планктонных сообществ. Участие планктона в волновом движении в толще морской воды позволяет определитьпараметры внутренних волн спектр и распределение по амплитудам в различное время.This paper represents the application of acoustic probingfor the investigation of acoustical properties of the upperlayer of the sea using broadband narrow-beam invertedtransducers that are mounted on the sea bottom. Thismethod is based on the principle of the recording of thebackscattering and reflections of acoustic pulses of differentfrequencies from the sea surface. That simultaneouslyallows measuring scattering and absorption of the soundand non-linear acoustic parameter of seawater. Multifrequencyprobing allows performing acoustic spectroscopy ofbubbles in the near-surface layer of the sea, estimating gascontent, and obtaining data on the spectrum of the surfacewaves in various states of the sea up to a storm. Utilizationof the high-frequency narrow ultrasound beams allows us toseparate the information about plankton and bubbles and todetermine the structure of bubble clouds, created during thebreaking of wind waves, along with the structure of planktoncommunities with high spatial resolution. The participationof plankton in the wave motion in the seawater columnallows determining parameters of internal waves, such asspectrum and distribution of amplitudes at different times.

Compressive acoustic sound speed profile estimation using wavelets

2016 ◽  
Vol 139 (4) ◽  
pp. 2167-2167 ◽  
Author(s):  
Michael J. Bianco ◽  
Haiqiang Niu ◽  
Peter Gerstoft
Keyword(s):  
Sound Speed ◽  
Speed Profile ◽  
Sound Speed Profile ◽  
Profile Estimation

Acoustic reflection from a sea bottom with linearly increasing sound speed

1979 ◽  
Vol 66 (6) ◽  
pp. 1836-1841 ◽  
Author(s):  
A. O. Williams ◽  
Douglas R. MacAyeal
Keyword(s):  
Sound Speed ◽  
Acoustic Reflection ◽  
Sea Bottom

An Experimental Study to Find the Acoustic Quality Indicators of Mulberry Wood

2010 ◽  
Author(s):  
Hossein Mansour ◽  
Mehdi Behzad
Keyword(s):  
Wood Species ◽  
Musical Instrument ◽  
Musical Instruments ◽  
Raw Material ◽  
Test Case ◽  
High Quality ◽  
Perceptual Knowledge ◽  
Acoustical Properties ◽  
Acoustic Quality

Morus Alba or mulberry is a wood species that is broadly used in making musical instruments in Eastern countries. However, the mechanical and acoustical properties of this type of wood are not investigated properly. In this study a set of features, previously examined for other species, are applied to this wood and its acoustic quality is evaluated. Setar, a Persian musical instrument made of mulberry wood, is selected as the test case of this experiment. Different samples of wood are gathered and categorized based on their appropriateness for Setar construction. The quality of each sample is identified based on the Perceptual knowledge of professional Setar makers. The most effective features are then selected and their average values are calculated for high quality samples. The result of this study helps Setar makers to select proper raw material before making an instrument. In addition, this approach can be applied to other wood species used in music industry.

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