scholarly journals Alarm Sound Propagation Characteristics of Gas Extinguishing System Installed in Computer Server Room

2020 ◽  
Vol 20 (4) ◽  
pp. 145-152
Author(s):  
Jeong-ho Jeong
Keyword(s):  
Protected Area ◽  
Noise Level ◽  
Sound Propagation ◽  
Propagation Characteristics ◽  
Acoustic Parameters ◽  
Safety Standards ◽  
Clean Agent ◽  
Protection Area ◽  
Alarm Sound ◽  
Prediction Techniques

Gas extinguishing systems are used for fire protection in server rooms and data centers. In the fire safety standards (NFSC 106, 107) of gas extinguishing systems (carbon dioxide, halon, and clean agent extinguishing system), sound alarm devices are installed in each protected area to provide an effective warning to personnel in the protected area or areas with objects to be protected. By measuring the noise level generated in a small server room, it was found that more than 70 dB of noise was generated. Therefore, to effectively transmit alarm sound to workers in all areas within the protection area, such as a server room, an acoustic alarm device must be designed and installed so that an alarm sound is transmitted at a level of 15 dB or higher than the noise level generated by equipment installed in the facility. As a result of predicting the alarm sound through the room acoustic simulation for a small server room equipped with an acoustic alarm system in a cabinet-type gas extinguishing system, it was found that it was insufficient in effectively delivering an alarm sound to the entire protection area. To effectively transmit an alarm sound inside the protection area where a gas extinguishing system is installed, the output of the alarm device needs to be increased and the room acoustic parameters should be predicted in advance using room acoustic prediction techniques and actively adjusting the acoustics according to the noise generated inside the protection area. Additionally, the distance between alarm devices needs to be shortened to deliver sufficient alarm volume throughout the protection area, and it is necessary to establish specific standards for this.

Short range sound propagation in shallow water and geo-acoustic parameters inversion

2012 ◽  
Vol 131 (4) ◽  
pp. 3280-3280
Author(s):  
Xuegang Zhang ◽  
Chunxia Meng ◽  
Haohao Hu ◽  
Jing Han
Keyword(s):  
Shallow Water ◽  
Short Range ◽  
Sound Propagation ◽  
Acoustic Parameters ◽  
Parameters Inversion

A Ternary Solution for Independent Acoustic Impedance and Speed of Sound Matching to Biological Tissues

1982 ◽  
Vol 4 (2) ◽  
pp. 163-170 ◽  
Author(s):  
Jonathan Ophir ◽  
Paul Jaeger
Keyword(s):  
Speed Of Sound ◽  
Acoustic Impedance ◽  
Soft Tissues ◽  
Sound Propagation ◽  
Biological Tissues ◽  
Liquid System ◽  
The Body ◽  
Acoustic Parameters ◽  
Wide Range

In applications requiring a liquid which is acoustically well matched to biological tissues, it is often difficult to find a material which is matched well in terms of both the acoustic impedance and speed of sound propagation in it; changing one parameter invariably affects the other. A three component liquid system is described, which allows independent adjustment of these two acoustic parameters over a wide range. This range encompasses the soft tissues of the body. Results of parameter measurements are presented in the form which allows simple determination of the mixture required to match any combination of acoustic impedance and speed of sound propagation over a given range.

THE METHOD OF SEQUENTIAL TRANSFORMATION OF THE SOUND FIELDS

Akustika ◽  
2021 ◽  
pp. 141
Author(s):  
Nickolay Ivanov ◽  
Gennady Kurtsev ◽  
Aleksandr Shashurin
Keyword(s):  
Noise Level ◽  
Sound Absorption ◽  
Sound Propagation ◽  
Sound Field ◽  
Structural Elements ◽  
Noise And Vibration ◽  
Main Assumption ◽  
Efficiency Calculation ◽  
Sound Fields ◽  
Sequential Transformation

A rule for describing the sequential transformation of the sound fields when properties of the surfaces or structural elements change due to such basic processes as sound absorption, reflection, diffraction, or sound divergence is proposed. The main assumption is that sound fields are non-coherent, i.e., resonant phenomena and sound interference are not considered. The examples show solutions to such problems: - sound propagation in space if there are artificial structures; - sound propagation in the rooms; - efficiency calculation of the noise protection structures; - calculation of the expected noise level of the machinery and separation of the contribution of noise and vibration sources to sound fields (for example, an external sound field, a sound field in the office, etc.)

A Novel Technique With a Magnetostrictive Transducer for In Situ Length Monitoring of a Distant Specimen

2003 ◽  
Author(s):  
Michael Pedrick ◽  
Michael Heckman ◽  
B. R. Tittmann
Keyword(s):  
High Precision ◽  
Temperature Effects ◽  
Sound Propagation ◽  
Sound Waves ◽  
Propagation Characteristics ◽  
Novel Technique ◽  
Flight Measurement ◽  
Magnetostrictive Sensor ◽  
Magnetostrictive Transducer

A Magnetostrictive sensor was used to generate sound waves in a specimen through thirty feet of wire. Many hardware aspects are discussed such as boundaries, materials, acoustic horn design, and sound propagation characteristics which facilitated the generation of sound energy in the specimen. Temperature effects on velocity and length were calculated and a model was developed to determine length from a time of flight measurement. The specimen was heated in an oven to various temperatures and times of flight were measured and compared to the model. Results show agreement between the measured values and the model as well as the ability for a high precision length measurement.

Effect of Guide’s Acoustic Parameters on Vertical Directivity of the Marine Ambient Noise

2014 ◽  
Vol 577 ◽  
pp. 1207-1210
Author(s):  
Chun Xia Meng ◽  
Hao Mu ◽  
Gui Juan Li
Keyword(s):  
Shallow Water ◽  
Sound Speed ◽  
Ambient Noise ◽  
Sound Propagation ◽  
Sea Water ◽  
Surface Boundary ◽  
Ray Theory ◽  
Directivity Characteristic ◽  
Acoustic Parameters ◽  
Equipment Performance

The vertical directivity characteristic of ambient noise is one inherent characteristic of the ocean in shallow water. And it includes the information of guide’s acoustic characteristic information. The marine guide is composed of sea water; seabed and surface boundary, there into, the acoustic parameters of seabed are hardly obtained exactly. In this paper, the model of vertical directivity for ambient noise is established. Based on the ray theory of sound propagation, the influence of guide’s acoustic parameters which include sound speed, density and attenuation coefficient on vertical directivity of marine ambient noise is simulated. The results are propitious to analysis and command the characteristics of ambient noise, and valuable to accelerate the exertion of acoustic equipment performance.

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