scholarly journals CHARACTERISTICS OF MICROSEISMS AND ACOUSTIC NOISES IN THE TRANSPORT POLYGON CONDITIONS

2021 ◽  
Vol 4 (1) ◽  
pp. 118-125
Author(s):  
Vladimir I. Dobrorodny ◽  
Oksana A. Kopylova
Keyword(s):  
Acoustic Waves ◽  
Seismic Waves ◽  
Acoustic Noise ◽  
Anthropogenic Sources ◽  
Numerical Estimation ◽  
Noise Levels ◽  
Wave Processes ◽  
Geophysical Monitoring ◽  
Wave Fields ◽  
The Difference

The work is related to numerical estimation and comparative analysis of microseismic and acoustic noise levels in transport polygon conditions. The aim of the work is to study and further define the difference between the signal and noise to improve the ability to detect poorly distinguishable events, as well as to study the propagation features of the interrelated seismic and acoustic wave fields. It is related to the fact that wave processes generated by many natural and anthropogenic sources are conjugate nature. In particular, it is related to simultaneous propagation of seismic waves in the ground and acoustic waves in the atmosphere. It determines expediency of taking into account simultaneously parameters of both types of waves in the tasks of geophysical monitoring of the environment, as well as in solving some applied problems of seismics and acoustics.

scholarly journals The exploration of wave processes in the Arctics geological layers in the presence of the ice field.

2021 ◽  
Vol 13 (3) ◽  
pp. 383-388
Author(s):  
Polina V. Stogniy ◽  
◽  
Igor B. Petrov ◽  
Nikolay I. Khokhlov ◽  
◽  
...  
Keyword(s):  
Seismic Waves ◽  
The Arctic ◽  
Shelf Zone ◽  
Wave Processes ◽  
Wave Fields ◽  
Reflected Waves ◽  
Important Region ◽  
Problem Description ◽  
Ice Field ◽  
2D Model

The Arctic shelf zone is a very important region in our country due to the huge amounts of hydrocarbons, located there. The exploration of this region is difficult because of the presence of lots of various ice constructions, in particular, ice fields. While carrying out the seismic prospecting works, the reflected waves from the ice field contribute much to the seismograms. It sufficiently complicates the process of further interpretation of the seismograms. Only a few works are devoted to modelling the seismic waves spread through the geological layers of the Arctics in the presence of an ice field as this theme is rather new and needs deeper investigation. In this work we present the results of the investigation of the seismic waves spread in models with an ice field for the 3D case using the grid-characteristic method. The modelling results (wave fields of the velocity distribution and seismograms) allow to identify the reflected waves from the ice field from other waves. In addition, we carried out the comparative analysis of the wave fields and seismograms for the 2D model with an ice field on the surface of the calculated area for the problem description from the work of other authors. The results demonstrate a good qualitative coincidence under different approaches to the solution of the problem.

scholarly journals Characterization of Noise Level Inside a Vehicle under Different Conditions

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2471 ◽  
Author(s):  
Daniel Flor ◽  
Danilo Pena ◽  
Luan Pena ◽  
Vicente A. de Sousa ◽  
Allan Martins
Keyword(s):  
Regression Analysis ◽  
Noise Level ◽  
Acoustic Noise ◽  
Experimental Setup ◽  
Strongly Correlated ◽  
Noise Levels ◽  
Noise Sources ◽  
Statistical Tools ◽  
Window Position

Vehicular acoustic noise evaluations are a concern of researchers due to health and comfort effects on humans and are fundamental for anyone interested in mitigating audio noise. This paper focuses on the evaluation of the noise level inside a vehicle by using statistical tools. First, an experimental setup was developed with microphones and a microcomputer located strategically on the car’s panel, and measurements were carried out with different conditions such as car window position, rain, traffic, and car speed. Regression analysis was performed to evaluate the similarity of the noise level from those conditions. Thus, we were able to discuss the relevance of the variables that contribute to the noise level inside a car. Finally, our results revealed that the car speed is strongly correlated to interior noise levels, suggesting the most relevant noise sources are in the vehicle itself.

scholarly journals An Improved Sensitivity Method for the Simultaneous Identification of Unknown Parameters and External Loads of Nonlinear Structures

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Chongwen Wang ◽  
Chengbin Du
Keyword(s):  
Regularization Parameter ◽  
Parameter Distribution ◽  
Nonlinear Structures ◽  
Noise Levels ◽  
Unknown Parameters ◽  
Key Issues ◽  
The Difference ◽  
Sensitivity Method ◽  
Simultaneous Identification ◽  
External Loads

Because structures may be subject to unknown loads and may simultaneously involve unknown parameters and because simple load identification or parameter identification algorithms cannot be applied under such conditions, it is necessary to seek algorithms that can simultaneously identify unknown parameters and external loads of structures. The sensitivity method is one of them, and this paper extends this method to nonlinear structures. In addition, the key issues associated with the sensitivity method are systematically studied, and suggestions for improvement are put forward, including the use of the difference method instead of the derivative method to calculate the sensitivity, the use of a fixed regularization parameter instead of the traditional regularization parameter calculation methods, and measures for guarantee of iterative convergence. The improved sensitivity method is applied to two types of nonlinear structures, and the effects of the regularization parameter, distribution of measured points, response types, noise levels, and the magnitude of the perturbation on the identified results are discussed.

scholarly journals Linear traveltime perturbation interpolation: a novel method to compute 3-D traveltimes

2015 ◽  
Vol 203 (1) ◽  
pp. 548-552 ◽  
Author(s):  
Jianzhong Zhang ◽  
Junjie Shi ◽  
Lin-Ping Song ◽  
Hua-wei Zhou
Keyword(s):  
Seismic Waves ◽  
Homogeneous Medium ◽  
Cell Boundary ◽  
Routine Method ◽  
Bilinear Interpolation ◽  
Linear Distribution ◽  
Heterogeneous Model ◽  
Computational Errors ◽  
Novel Method ◽  
The Difference

Abstract The linear traveltime interpolation has been a routine method to compute first arrivals of seismic waves and trace rays in complex media. The method assumes that traveltimes follow a linear distribution on each boundary of cells. The linearity assumption of traveltimes facilitates the numerical implementation but its violation may result in large computational errors. In this paper, we propose a new way to mitigate the potential shortcoming hidden in the linear traveltime interpolation. We use the vertex traveltimes in a calculated cell to introduce an equivalent homogeneous medium that is specific to the cell boundary from a source. Therefore, we can decompose the traveltime at a point on the cell boundary into two parts: (1) a reference traveltime propagating in the equivalent homogeneous medium and (2) a perturbation traveltime that is defined as the difference between the original and reference traveltimes. We now treat that the traveltime perturbation is linear along each boundary of cells instead of the traveltime. With the new assumption, we carry out the bilinear interpolation over traveltime perturbation to complete traveltime computation in a 3-D heterogeneous model. The numerical experiments show that the new method, the linear traveltime perturbation interpolation, is able to achieve much higher accuracy than that based on the linear traveltime interpolation.

scholarly journals Моделирование проводимости Капицы через шероховатые интерфейсы между твердыми телами

2021 ◽  
Vol 63 (7) ◽  
pp. 982
Author(s):  
Б. Лю ◽  
В.И. Хвесюк ◽  
А.А. Баринов
Keyword(s):  
Experimental Data ◽  
Theoretical Prediction ◽  
Transmission Coefficient ◽  
Wide Temperature Range ◽  
Acoustic Waves ◽  
Theoretical Method ◽  
Interface Roughness ◽  
Kapitza Conductance ◽  
Acoustic Mismatch ◽  
The Difference

In this work, we have formulated and solved the problem of determining the Kapitza conductance across the interface between two solids, taking into account the interface roughness. We use a modified acoustic mismatch model (AMM). The difference from the classic model is that the dispersion properties of acoustic waves are considered. A significant advantage of this model is that the theoretical prediction agrees well with experimental data over a wide temperature range: from 30K to more than 300K. Finally, a theoretical method with the statistical distribution of roughness profiles is used to determine the energy transmission coefficient across the interface.

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.

A variety of surface waves in ocean-bottom DAS records

2021 ◽  
Author(s):  
Zack Spica ◽  
Loïc Viens ◽  
Jorge Castillo Castellanos ◽  
Takeshi Akuhara ◽  
Kiwamu Nishida ◽  
...  
Keyword(s):  
Surface Wave ◽  
Acoustic Waves ◽  
Fiber Optic ◽  
Acoustic Noise ◽  
Seismic Exploration ◽  
Ocean Bottom ◽  
Wide Range ◽  
Ocean Layer ◽  
Noise Cross Correlation ◽  
Low Amplitude

<p>Distributed acoustic sensing (DAS) can transform existing telecommunication fiber-optic cables into arrays of thousands of sensors, enabling meter-scale recordings over tens of kilometers. Recently, DAS has demonstrated its utility for many seismological applications onshore. However, the use of offshore cables for seismic exploration and monitoring is still in its infancy.<br>In this work, we introduce some new results and observations obtained from a fiber-optic cable offshore the coast of Sanriku, Japan. In particular, we focus on surface wave retrieved from various signals and show that ocean-bottom DAS can be used to extract dispersion curves (DC) over a wide range of frequencies. We show that multi-mode DC can be easily extracted from ambient seismo-acoustic noise cross-correlation functions or F-K analysis. Moderate magnitude earthquakes also contain multiple surface-wave packets that are buried within their coda. Fully-coupled 3-D numerical simulations suggest that these low-amplitude signals originate from the continuous reverberations of the acoustic waves in the ocean layer. </p>

scholarly journals Understanding the Legendary Sound Environment in the Lobby of Hotel Okura Tokyo

2020 ◽  
Vol 10 (13) ◽  
pp. 4552
Author(s):  
Ryoko Nojima ◽  
Natsuko Sugie ◽  
Akira Taguchi ◽  
Jun Kokubo
Keyword(s):  
Speech Intelligibility ◽  
Comprehensive Evaluation ◽  
The Other ◽  
Noise Levels ◽  
Sound Environment ◽  
Good Reputation ◽  
The Difference ◽  
Hotel Lobbies

The main lobby of Hotel Okura Tokyo has a good reputation for its sound environment, which affects the conversations of its users. We assumed that the lobby’s reputation was related to its speech intelligibility. In this study, first, the sound during hotel operations was measured to see if there was a difference in the sound environment between the lobby and the entrance hall. As a result, we clarified that the difference in noise levels affected by the degree of crowdedness of the room was smaller in the lobby than in the other rooms. Subsequently, the indoor noise and speech intelligibility were measured to clarify the correspondence of intelligibility with the lobby’s reputation. As a result, the indoor noise was found to be at a level suitable for hotel lobbies and the intelligibility was good. A comprehensive evaluation that included the results of other acoustical surveys revealed that the lobby of Okura is a space that is suitable for conversations, corresponding to the opinions of users.

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