The other ocean: probing Europa’s interior with natural ambient noise sources

2001 ◽  
Vol 109 (5) ◽  
pp. 2371-2371
Author(s):  
Aaron M. Thode ◽  
Michele Zanolin ◽  
Sunwoong Lee ◽  
Purnima Ratilal ◽  
Josh Wilson ◽  
...  
Keyword(s):  
Ambient Noise ◽  
The Other ◽  
Noise Sources

A Method for Noise Source Levels Inversion with Underwater Ambient Noise Generated by Typhoon in Deep Ocean

2018 ◽  
Vol 26 (02) ◽  
pp. 1850007 ◽  
Author(s):  
Qiulong Yang ◽  
Kunde Yang ◽  
Shunli Duan
Keyword(s):  
Ambient Noise ◽  
Noise Source ◽  
Surface Wind ◽  
Deep Ocean ◽  
Noise Sources ◽  
Noise Field ◽  
Sea Surface Wind ◽  
Source Level ◽  
The Western Pacific ◽  
Good Agreement

Sea-surface wind agitation can be considered the dominant noise sources whose intensity relies on local wind speed during typhoon period. Noise source levels in previous researches may be unappreciated for all oceanic regions and should be corrected for modeling typhoon-generated ambient noise fields in deep ocean. This work describes the inversion of wind-driven noise source level based on a noise field model and experimental measurements, and the verification of the inverted noise source levels with experimental results during typhoon period. A method based on ray approach is presented for modeling underwater ambient noise fields generated by typhoons in deep ocean. Besides, acoustic field reciprocity is utilized to decrease the calculation amount in modeling ambient noise field. What is more, the depth dependence and the vertical directionality of noise field based on the modeling method and the Holland typhoon model are evaluated and analyzed in deep ocean. Furthermore, typhoons named “Soulik” in 2013 and “Nida” in 2016 passed by the receivers deployed in the western Pacific (WP) and the South China Sea (SCS). Variations in sound speed profile, bathymetry, and the related oceanic meteorological parameters are analyzed and taken into consideration for modeling noise field. Boundary constraint simulated annealing (SA) method is utilized to invert the three parameters of noise source levels and to minimize the objective function value. The prediction results with the inverted noise source levels exhibit good agreement with the measured experiment data and are compared with predicted results with other noise sources levels derived in previous researches.

Long-term structural monitoring of multi-story RC structures, based on data extracted from ambient noise and earthquake vibrations

2021 ◽  
Author(s):  
Alexandru Tiganescu ◽  
Bogdan Grecu ◽  
Iolanda-Gabriela Craifaleanu ◽  
Dragos Toma-Danila ◽  
Stefan-Florin Balan
Keyword(s):  
Monitoring System ◽  
Ambient Noise ◽  
Critical Issue ◽  
Seismic Events ◽  
Noise Sources ◽  
Rc Structures ◽  
Infrastructure Monitoring ◽  
Human Operators ◽  
The Impact

<p>The impact of natural hazards on structures and infrastructures is a critical issue that needs to be properly addressed by both public and private entities. To better cope with seismic hazard and to mitigate the risk, long-term multi-sensor infrastructure monitoring represents a useful tool for acquiring information on their condition and vulnerability. However, the current increasing data volume collected using sensors is not suitable to be processed with classical standalone methods. Thus, automatic algorithms and decision-making frameworks should be developed to use this data, with minimum intervention from human operators. A case-study for the application of advanced methods is focused on the headquarters of the Institute for Atomic Physics, a 11-story reinforced concrete building, located near Bucharest, Romania. The instrumentation scheme consists of accelerometers installed at the basement, at an intermediate floor and at the top of the structure. The data were continuously recorded, starting with December 2013. More than 80 seismic events with moment magnitude, M<sub>W</sub>, larger than 3.8 were recorded during the monitoring period. The current study covers the long-term evolution and variation of dynamic parameters (one value per hour), based on both ambient noise sources and small and medium magnitude seismic events. The seasonal variation of these parameters will be determined, as well as their daily variation and the differences between values obtained from ambient noise and from earthquake-induced vibrations. Other atmospheric parameters (e.g. temperature, precipitation, wind speed) will be considered in future studies. The goal of the PREVENT project, in the framework of which the research is performed, is to collect multi-disciplinary data and to integrate them into a complex monitoring system. The current study achieved the first step, focusing on data from the seismic sensors and setting up the premises for a multi-sensor, multi-parameter, more reliable infrastructure monitoring system.  </p>

Descriptors and Indicators of the Acoustic Environment in Andorra and Escaldes-Engordany

Proceedings ◽  
2019 ◽  
Vol 44 (1) ◽  
pp. 6
Author(s):  
Rosa Alsina-Pagès ◽  
Laura Echevarría-Garuz
Keyword(s):  
Quality Of Life ◽  
Noise Pollution ◽  
The Other ◽  
Physical Parameters ◽  
Noise Sources ◽  
Acoustic Environment ◽  
Audio Recordings ◽  
Using Data ◽  
The City

Noise pollution is one of the growing issues in our cities. Every day the streets are full of vehicles of all kinds and works using noisy machinery; it seems difficult to find a quiet area that away from this acoustic environment. Presently, multiple studies are being carried out in the area of engineering in order to be able to attenuate the causes of this noise pollution, in order to improve citizens’ lives. Nevertheless, are cars the only cause of the noise in the city? Are there other noise sources that may affect the quality of life of the citizens? What defines a city as heavily polluted or not? Maybe it can be assumed that truck noise is annoying and that it contributes to noise pollution, while the sound of birds does not and it is pleasant for people. This paper pretends to analyze the physical parameters that allow us to define if any sound causes annoyance, taking into account its acoustic environment. To do this, a specific case will be analysed; we will study three locations measured in Andorra La Vella and Escaldes-Engordany. The audio recordings will be studied deeply, and compared one to the other using data from two different days and all day schedule. We will finally evaluate the annoyance of each location using parameters such as loudness, sharpness and roughness, and taking into account both day and time, as well as giving details about the several types of sound labelled in each recording.

Source-structure trade-offs in noise correlation functions in 3-D

2020 ◽  
Author(s):  
Korbinian Sager ◽  
Christian Boehm ◽  
Victor Tsai
Keyword(s):  
Correlation Functions ◽  
Ambient Noise ◽  
Hessian Matrix ◽  
Seismic Wave Propagation ◽  
Source Distribution ◽  
Earth Structure ◽  
Noise Correlation ◽  
Noise Sources ◽  
Trade Offs ◽  
Source Structure

<p>Noise correlation functions are shaped by both noise sources and Earth structure. The extraction of information is thus inevitably affected by source-structure trade-offs. Resorting to the principle of Green’s function retrieval deceptively renders the distribution of ambient noise sources unimportant and existing trade-offs are typically ignored. In our approach, we consider correlation functions as self-consistent observables. We account for arbitrary noise source distributions in both space and frequency, and for the complete seismic wave propagation physics in 3-D heterogeneous and attenuating media. We are therefore not only able to minimize the detrimental effect of a wrong (homogeneous) source distribution on 3D Earth structure by including it as an inversion parameter, but also to quantify underlying trade-offs.</p><p>The forward problem of modeling correlation functions and the computation of sensitivity kernels for noise sources and Earth structure are implemented based on the spectral-element solver Salvus. We extend the framework with the evaluation of second derivatives in terms of Hessian-vector products. In the context of probabilistic inverse problems, the inverse Hessian matrix in the vicinity of an optimal model with vanishing first derivatives and under the assumption of Gaussian statistics can be interpreted as an approximation of the posterior covariance matrix. The Hessian matrix therefore contains all the information on resolution and trade-offs that we are trying to retrieve. We investigate the geometry of trade-offs and the effect of the measurement type. In addition, since we only invert for sources at the surface of the Earth, we study how potential scatterers at depth are mapped into the inferred source distribution.</p><p>A profound understanding of the physics behind correlation functions and the quantification of trade-offs is essential for full waveform ambient noise inversion that aims to exploit waveform details for the benefit of improved resolution compared to traditional ambient noise tomography.</p>

SPRI participation in the Winter Weddell Gyre Study 1989

Polar Record ◽  
1991 ◽  
Vol 27 (160) ◽  
pp. 29-38 ◽  
Author(s):  
P. Wadhams ◽  
D. R. Crane
Keyword(s):  
Sea Ice ◽  
Aerial Photography ◽  
Ambient Noise ◽  
The Other ◽  
Sidescan Sonar ◽  
Ice Thickness ◽  
Research Groups ◽  
Weddell Gyre ◽  
International Group ◽  
Polar Research Institute

AbstractThe Winter Weddell Gyre Study was conducted by an international group of scientists, including members of the Scott Polar Research Institute, from FS Polarstern (FRG) in September and October 1989, in collaboration with RV Akademk Federov (USSR). This was a multi-disciplinary experiment involving biologists, chemists, oceanographers and meteorologists. The SPRI involvement centred on sea-ice research, involving both our own experiments and a programme carried out in collaboration with the other research groups on board. The SPRI programme involved measuring ice thickness; studying the under-ice topography with an upward looking sidescan sonar; investigating the acceleration, tilt and strain of the ice; deploying Argos buoys; aerial photography; iceberg tracking; and two acoustic experiments, one to record ambient noise and the other to acoustically measure the ice thickness.

Ground Motion in the Presence of Complex Topography: Earthquake and Ambient Noise Sources

2013 ◽  
Vol 104 (1) ◽  
pp. 451-466 ◽  
Author(s):  
S. Hartzell ◽  
M. Meremonte ◽  
L. Ramirez-Guzman ◽  
D. McNamara
Keyword(s):  
Ground Motion ◽  
Ambient Noise ◽  
Complex Topography ◽  
Noise Sources

Multichannel myopic deconvolution using ambient noise sources

2014 ◽  
Vol 135 (4) ◽  
pp. 2360-2360
Author(s):  
Ning Tian ◽  
Justin Romberg ◽  
Karim Sabra
Keyword(s):  
Ambient Noise ◽  
Noise Sources

scholarly journals An adapted eigenvalue-based filter for ocean ambient noise processing

Geophysics ◽  
2020 ◽  
Vol 85 (1) ◽  
pp. KS29-KS38 ◽  
Author(s):  
Guoli Wu ◽  
Hefeng Dong ◽  
Ganpan Ke ◽  
Junqiang Song
Keyword(s):  
Covariance Matrix ◽  
Ambient Noise ◽  
Green's Functions ◽  
Green’S Functions ◽  
Homogeneous Distribution ◽  
Noise Sources ◽  
Data Set ◽  
Recording Time ◽  
Receiver Array ◽  
Sample Covariance

Accurate approximations of Green’s functions retrieved from the correlations of ambient noise require a homogeneous distribution of random and uncorrelated noise sources. In the real world, the existence of highly coherent, strong directional noise generated by ships, earthquakes, and other human activities can result in biases in the ambient-noise crosscorrelations (NCCs). We have developed an adapted eigenvalue-based filter to attenuate the interference of strong directional sources. The filter is based on the statistical model of the sample covariance matrix and can separate different components of the data covariance matrix in the eigenvalue spectrum. To improve the effectiveness and make it adaptable for different data sets, a weight is introduced to the filter. Then, the NCCs can be calculated directly from the filtered data covariance matrix. This approach is applied to a 1.02 h data set of ambient noise recorded by a permanent reservoir monitoring receiver array installed on the seabed. The power spectral density indicates that the noise recordings were contaminated by strong directional noise over nearly half of the whole observation period. Beamforming and crosscorrelation results indicate that the interference still exists even after applying traditional temporal and spectral normalization techniques, whereas the adapted eigenvalue-based filter can significantly attenuate it and help to obtain improved crosscorrelations. The approach makes it possible to retrieve reliable approximations of Green’s functions over a much shorter recording time.

Sign in / Sign up

Export Citation Format

Share Document