scholarly journals The Mount Meron infrasound array: an infrasound array without a noise reduction system

2019 ◽  
Vol 219 (2) ◽  
pp. 1109-1117
Author(s):  
Gil Averbuch ◽  
Yochai Ben-Horin ◽  
Pieter S M Smets ◽  
Läslo G Evers
Keyword(s):  
Noise Reduction ◽  
Site Location ◽  
Noise Levels ◽  
Seismic Arrays ◽  
Physical Constraints ◽  
Array Configuration ◽  
International Monitoring ◽  
Ctbt Verification ◽  
The Individual ◽  
Test Ban

SUMMARY Measurements of seismo-acoustic events by collocated seismic and infrasound arrays allow for studying the two wavefields that were produced by the same event. However, some of the scientific and technical constraints on the building of the two technologies are different and may be contradicting. For the case of a new station, an optimal design that will satisfy the constraints of the two technologies can be found. However, in the case of upgrading an existing array by adding the complementing technology, the situation is different. The site location, the array configuration and physical constraints are fixed and may not be optimal for the complementing technology, which may lead to rejection of the upgrade. The International Monitoring System (IMS) for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) includes 37 seismic arrays and 51 infrasound arrays. Although the CTBT verification regime is fixed in the treaty, an upgrade of the existing arrays by adding more technologies is possible. The Mount Meron seismic array (MMAI), which is part of the IMS, is composed of 16 sites. Microbarometers were installed at five MMAI sites to form the Mount Meron infrasound array. Due to regulation and physical constraints, it was not possible to relocate the sites nor to install analogue noise reduction filters (i.e. a pipe array). In this study, it is demonstrated that the installation of the MMAI infrasound array is beneficial despite the non-optimal conditions. It is shown that the noise levels of the individual array sites are between the high and median global noise levels. However, we claim that the more indicative measures are the noise levels of the beams of interest, as demonstrated by analysing the microbaroms originated from the Mediterranean Sea. Moreover, the ability to detect events relevant to the CTBT is demonstrated by analysing man-made events during 2011 from the Libya region.

scholarly journals Comparison and Validation of Acoustic Response Models for Wind Noise Reduction Pipe Arrays

2017 ◽  
Vol 34 (2) ◽  
pp. 401-414 ◽  
Author(s):  
Julien Marty ◽  
Stéphane Denis ◽  
Thomas Gabrielson ◽  
Milton Garcés ◽  
David Brown
Keyword(s):  
Noise Reduction ◽  
Acoustic Response ◽  
Detection Capability ◽  
Wind Noise ◽  
Response Models ◽  
Operational Conditions ◽  
Measurement Systems ◽  
International Monitoring ◽  
Wind Noise Reduction ◽  
Acoustic Responses

AbstractThe detection capability of the infrasound component of the International Monitoring System (IMS) is tightly linked to the performance of its wind noise reduction systems. The wind noise reduction solution implemented at all IMS infrasound measurement systems consists of a spatial distribution of air inlets connected to the infrasound sensor through a network of pipes. This system, usually referred to as “pipe array,” has proven its efficiency in operational conditions. The objective of this paper is to present the results of the comparison and validation of three distinct acoustic response models for pipe arrays. The characteristics of the models and the results obtained for a defined set of pipe array configurations are described. A field experiment using a newly developed infrasound generator, dedicated to the validation of these models, is then presented. The comparison between the modeled and empirical acoustic responses shows that two of the three models can be confidently used to estimate pipe array acoustic responses. This study paves the way to the deconvolution of IMS infrasound data from pipe array responses and to the optimization of pipe array design to IMS applications.

scholarly journals Adjoint backtracking for the verification of the Comprehensive Test Ban Treaty

2002 ◽  
Vol 2 (6) ◽  
pp. 2133-2150 ◽  
Author(s):  
J.-P. Issartel ◽  
J. Baverel
Keyword(s):  
Adjoint Operator ◽  
Real Data ◽  
Daily Basis ◽  
New Approach ◽  
Comprehensive Test Ban Treaty ◽  
Tracer Dispersion ◽  
International Monitoring ◽  
Comprehensive Test ◽  
Test Ban ◽  
Test Ban Treaty

Abstract. An international monitoring system is being built as a verification tool for the Comprehensive Test Ban Treaty. Forty stations will measure on a worldwide daily basis the concentration of radioactive noble gases. The paper introduces, by handling preliminary real data, a new approach of backtracking for the identification of sources after positive measurements. When several measurements are available the ambiguity about possible sources is reduced significantly. As an interesting side result it is shown that diffusion in the passive tracer dispersion equation is necessarily a self-adjoint operator.

Teleseismic response of a uniform dipping crust (part I of a series on crustal equalization of seismic arrays)

1966 ◽  
Vol 56 (4) ◽  
pp. 841-859
Author(s):  
Julius Kane
Keyword(s):  
Time Delays ◽  
The Other ◽  
Local Geometry ◽  
Signal Distortion ◽  
Seismic Arrays ◽  
Plane Parallel ◽  
Crustal Structures ◽  
Parallel Configuration ◽  
The Individual ◽  
Elastic Layers

abstract Most seismic theory is confined to a consideration of crustal structures that can be abstracted as plane parallel elastic layers. For such configurations, the response of each element of a seismic array will be similar to any other except for a time delay. Signal enhancement of an array located on such an idealized structure can be accomplished by suitable time delays of the individual traces followed by superposition. On the other hand, if the crustal structure is anything but a plane parallel configuration, the signals received by the individual elements will not be identical to one another, but will include distortion effects characteristic of the local geometry. As a result, the records of seismic arrays located on realistic crustal configurations will have to be equalized to some standard reference if optimum signal processing is to be achieved. In this paper we introduce a ray procedure for the calculation of theoretical seismograms for the teleseismic response of an array of stations located above a uniform dipping crust (wedge-shaped). In terms of this mathematical model, we demonstrate the signal distortion effects of the geometry and discuss equalization techniques that will permit a superior recovery of the desired signal.

Noise reduction of enhanced acoustic balconies on a high-rise building block

2021 ◽  
Vol 263 (1) ◽  
pp. 5327-5334
Author(s):  
SK Tang ◽  
Rudolf YC Lee
Keyword(s):  
Noise Reduction ◽  
Natural Ventilation ◽  
Traffic Noise ◽  
Elevation Angle ◽  
Noise Levels ◽  
Indoor Space ◽  
New Device ◽  
Air Inlet ◽  
The Difference ◽  
The Impact

A new device called 'enhanced acoustic balcony' is installed in a new housing estate in Hong Kong. It is intended to help reduce the impact of traffic noise on the residents. This balcony is basically an enlarged form of a plenum window and with three openings. Apart from the outdoor air inlet, there is the balcony door and a side-hung window on the interior balcony wall for natural ventilation of the indoor space. Sound absorption of NRC 0.7 is installed on the balcony ceiling and its sidewall facing the incoming traffic noise and an inclined panel is installed outside the balcony to provide noise screening. A site measurement of its noise reduction is carried out in the present study in a newly completed housing block. A 28 m long loudspeaker array is used as the sound source. The indoor noise levels are measured according to ISO standard. The results show that the difference between indoor and outdoor noise levels in the presence of this balcony form varies over a relatively narrow range between 10 to 13 dBA for an elevation angle from 25 to 60 deg. There is a weak increase of the noise level difference with elevation angle.

Infrasound station IS25 of the International Monitoring System of the Comprehensive Test Ban Treaty : from design to certification

2021 ◽  
Author(s):  
thomas philippe ◽  
sylvain carre
Keyword(s):  
Monitoring System ◽  
International Monitoring System ◽  
Comprehensive Test Ban Treaty ◽  
Monitoring Tools ◽  
International Monitoring ◽  
Deep Forest ◽  
International Data ◽  
Comprehensive Test ◽  
Test Ban ◽  
Test Ban Treaty

<p>CEA is operating the French segment of the International Monitoring System of the Comprehensive Test Ban Treaty (CTBT). Construction of IMS stations was started on the late 90’ and one last station was pending before completing commitment of France.</p><p>Taking into account experience learned over the years, design was thought to combine enhanced detection capability and robustness. It gives also the opportunity to improve out monitoring tools and technics.</p><p>Station run 9 sensors spread out on a deep forest in Guadeloupe; power is distributed with buried cable while data are received with optical fibre to a central facility from which frames are sent to the International Data Center to the CTBTO. Constructiion was carried out in 2019.</p><p>IS25 was certified by the PTS of the CTBTO in November 2020</p>

Teleseismic slowness-azimuth station corrections for the International Monitoring System Seismic Network

1999 ◽  
Vol 89 (4) ◽  
pp. 989-1003 ◽  
Author(s):  
István Bondár ◽  
Robert G. North ◽  
Gregory Beall
Keyword(s):  
Monitoring System ◽  
Global Network ◽  
Systematic Bias ◽  
International Monitoring System ◽  
Time Data ◽  
International Monitoring ◽  
Event Location ◽  
Systematic Biases ◽  
Predicted Values ◽  
Test Ban

Abstract The prototype International Data Center (PIDC) in Arlington, Virginia, has been developing and testing software and procedures for use in the verification of the Comprehensive Test Ban Treaty. After three years of operation with a global network of array and three-component stations, it has been possible to characterize various systematic biases of those stations that are designated in the Treaty as part of the International Monitoring System (IMS). These biases include deviations of azimuth and slowness measurements from predicted values, caused largely by lateral heterogeneity. For events recorded by few stations, azimuth and slowness are used in addition to arrival-time data for location by the PIDC. Corrections to teleseismic azimuth and slowness observations have been empirically determined for most IMS stations providing data to the PIDC. Application of these corrections is shown to improve signal association and event location. At some stations an overall systematic bias can be ascribed to local crustal structure or to unreported instrumental problems. The corrections have been applied in routine operation of the PIDC since February 1998.

scholarly journals Spectral Noise Levels and Roughness Severity Ratings for Normal and Simulated Rough Vowels Produced by Adult Males

1970 ◽  
Vol 13 (3) ◽  
pp. 489-502 ◽  
Author(s):  
Frank E. Sansone ◽  
Floyd W. Emanuel
Keyword(s):  
Correlation Coefficients ◽  
Adult Males ◽  
Noise Levels ◽  
Multiple Correlation ◽  
Acoustic Spectrum ◽  
Spectral Components ◽  
Multiple Correlation Coefficients ◽  
The Individual ◽  
Spectral Ranges ◽  
The Relationship

Twenty normal-speaking adult males sustained productions of each of the vowels /u/, /i/, /Λ/, /a/, and /æ/ first normally and then with simulated vocal roughness at one intensity. A tape recording of each production was rated for roughness on a five-point equal-appearing-intervals scale by 11 trained judges and was also analyzed to produce its 3-Hz bandwidth frequency-by-amplitude acoustic spectrum. The median roughness rating and the level of inharmonic spectral components, i.e., noise components, for each production were examined and related. Noise levels for the productions of each vowel averaged over selected spectral ranges between 100 Hz and 8000 Hz correlated highly with the median roughness ratings for those productions. Multiple correlation coefficients indicating the relationship between the median roughness rating and multiple measures of spectral noise in the range from 100 Hz to 2600 Hz for the individual productions of each test vowel were high (≥0.97) and significant for all five vowels.

Optimized Asphalt Mixtures for Noise Reduction in Lithuanian Roads

2014 ◽  
Vol 614 ◽  
pp. 618-621
Author(s):  
Audrius Vaitkus ◽  
Tadas Andriejauskas ◽  
Laura Čygaitė ◽  
Jurgita Židanavičiūtė
Keyword(s):  
Noise Reduction ◽  
Noise Pollution ◽  
Low Noise ◽  
Asphalt Pavements ◽  
Noise Levels ◽  
Road Noise ◽  
Negative Effects ◽  
Development Experience ◽  
Growing Economy ◽  
Generation Mechanisms

In the world of growing economy and population, the need of transportation is rapidly increasing also raising problems of noise pollution. Environmental noise levels are increasing in parallel with increasing traffic flows resulting negative effects for society, wildlife and economy. The article gives an overview about the main transport noise source tyre/road noise, its generation mechanisms and influencing factors. One of the most effective and promising tyre/road noise solutions is low noise pavements, which has different noise reduction approaches. Low noise asphalt pavements and theoretical noise reduction principles are analysed in the paper as well as the development experience of particular low noise asphalt pavements for Lithuanian conditions.

Noise and Other Environmental Considerations in the Design and Planning of Gas Compressor Stations in the U.K.

1972 ◽  
Author(s):  
A. Cleveland
Keyword(s):  
Ambient Noise ◽  
Noise Levels ◽  
Paper Briefly ◽  
Future Design ◽  
Natural Gas Transmission ◽  
Environmental Considerations ◽  
The Individual ◽  
The Uk ◽  
Gas Turbine Compressor ◽  
Alternative Designs

This paper briefly outlines some of the considerations taken into account in the design and planning of gas compressor stations for the UK Natural Gas Transmission System. Environmental considerations, and in particular the aspects of noise, play a large part in the design of these stations. The requirements for silencing to meet very low ambient noise levels and the development of gas turbine compressor unit enclosures is dealt with in some detail. The need for acoustically efficient and aesthetically pleasing structures is emphasized. The paper compares some representative alternative designs for individual enclosures with the design of an equivalent building and concludes that for small numbers of units, the individual enclosure is the economic solution. Other aspects of noise, including venting of gas are discussed and future design trends indicated. In the consideration of future designs, ease of maintenance and security are fundamental considerations, together with the need to ensure that noise emitted will not pollute the environment.

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