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Effect of windbreak on the wind flow in a small existing urban structure
Published in J. Carmeliet, H. Hens, G. Vermeir, Research in Building Physics, 2020
The street with traffic density of about 1000 vehicles per hour and 20% of heavy vehicles borders on the west side with the buildings complex. To protect inhabitants from the traffic noise, acoustic screen has been proposed as the third option of the windbreaks. The acoustic screen width was 130 m, the height 4 m and length 0.25 m. In that case effectiveness of the noise barrier in reducing of sound levels is about 15 dB.
Evaluation of traffic noise in the State of Qatar
Published in Eyad Masad, Amit Bhasin, Tom Scarpas, Ilaria Menapace, Anupam Kumar, Advances in Materials and Pavement Performance Prediction, 2018
Md. Ohiduzzaman, Okan Sirin, Emad Kassem
A number of noise abatement procedures were adopted to reduce traffic noise. Noise barrier walls are one of the most commonly used mitigating solution for noise abatement in highway facility. The goal of using noise barrier is to reduce the noise level by about ‘8 dBA’ to the first receiver near to the highway vicinity (Wang et al. 2012). However, the use of noise barrier wall caused a number of practical problems. Firstly, the construction of barrier wall is very expensive (about 2.1 million dollars per mile) (Donavan et al. 2013). Secondly, in some location it is not possible to construct barrier wall due to the driveways or intersection, therefore sound tends to diffract over and around noise barriers walls (Rasmussen and Sohaney 2012). Presence of hilly tracks presents further challenges in the effectiveness of barrier wall. In addition, concrete noise barriers have very high acoustic reflectivity with limited absorption hence adversely affected passengers and driver comfort. Therefore, reducing noise at source is becoming an effective alternative option. Pioneering study conducted by researchers in Europe and USA demonstrated that constructing low noise surface is possible by modifying pavement surface and/or texture (Ohiduzzaman et al. 2016, Rochat et al. 2010, Rochat et al. 2012, Sandberg and Ejsmont 2002, Sirin 2016). A number of noise measurement techniques are used in the laboratory and field. Of all the available noise measurement systems, on board sound intensity (OBSI) technique is more precise when the goal is to analyze the noise at tire-pavement interaction. Researchers in this project are already established an OBSI testing setup and measured tire-pavement noise at roads in the State of Qatar (Ohiduzzaman et al. 2017). In OBSI measurement method, only tire-pavement interaction noise is measured and noise from other sources (i.e., engine and exhaust noise, aerodynamic noise) are discarded. However, transportation authorities generally determine the acceptable noise level based on the overall noise levels which include tire-pavement, engine and exhaust noises. Noise regulations are also in place in most countries to limit the noise production by traffic. For example, in the USA, the ‘Federal Highway Administration (FHWA) Noise Abatement Criteria’ states that the A-weighted sound pressure level must not exceed 67 dBA for residential areas (FHWA 2011). In Qatar, according to its environmental protection standards, the maximum noise level at the property line should not exceed 55 dBA during the day and 45 dBA at night in residential areas (Qatar Environmental Protection Standards 2012).
High-speed vision measurement of vibration based on an improved ZNSSD template matching algorithm
Published in Systems Science & Control Engineering, 2022
Jian Luo, Bingyou Liu, Pan Yang, Xuan Fan
The feasibility of using the high-speed visual vibration frequency measurement algorithm is confirmed in the first experiment. This section presents the second experiment, that is, the sound barrier experiment. Sound barrier, which is also known as sound wall or noise barrier, is a platform structure designed to protect residents from noise pollution coming from both sides of the railway or highway. Thus, this structure is the most effective method for reducing the impacts of road, railway, and industrial noises. However, with the increase in train speed, gravity and impact force are introduced when high-speed trains pass through the noise barrier. This phenomenon leads to the violent vibration of the barrier, which in turn, can cause material fatigue and loosened assemblies. In addition, when the sound barrier is damaged and falls on the railway track, disastrous consequences might occur.