Ali Safari Variani¹, Ali Dastamoz¹, Sajad Zare², Ahmad Nikpey¹, Saeid Ahmadi^1,*

Sound & Vibration, Vol.54, No.1, pp. 43-55, 2020, DOI:10.32604/sv.2020.08636

Abstract This work investigated multiple jet nozzles with various geometrical shape, number of exits, and material on reducing noise radiated from jet flows. Nozzles are categorized in two groups with few and many exit numbers, each with various exit shapes, slot and circular, and geometry. Firstly, nozzles are designed and then fabricated by a 3D printer, Form Labs, Form2USA, with polymeric resin. Also, the nozzle with the most noise reduction made of stainless steel. Noise and air thrust were measured at three air pressure gauges, 3, 5, 7 BAR and directions from nozzle apex, 30°, 90°, 135°. Nozzles with slot exit… More >

Jahede Tekeykhah¹, Seyed Mohsen Hosseini^2,*, Gholamali Jalali³, Jalil Alavi⁴, Abbas Esmaili Sari⁵

Sound & Vibration, Vol.53, No.6, pp. 263-276, 2019, DOI:10.32604/sv.2019.07157

Abstract Sound pollution is one of the most important urban problems which endangers mental and physical health of the residents. This study was aimed to assess the influence of different tree species, including Fraxinus rotundifolia, Robinia pseudoacacia, Platanus orientalis, Platycladus orientalis, and Pinus eldarica, in reducing noise pollution in the Abidar Forest Park. A further objective was to identify the contaminated areas of Sanandaj city and to propose suitable noise absorbent tree species in consistent conditions. For each tree stands the noise measurements were performed during intervals at frequencies of 250, 500 and 1000 Hz, besides an open area with the… More >

Yongyun Zhu¹, Tao Zhang^1,*, Mohan Li², Di Wang¹, Shaoen Wu³

CMC-Computers, Materials & Continua, Vol.61, No.3, pp. 1305-1321, 2019, DOI:10.32604/cmc.2019.06406

Abstract The observation vectors in traditional coarse alignment contain random noise caused by the errors of inertial instruments, which will slow down the convergence rate. To solve the above problem, a real-time noise reduction method, sliding fixed-interval least squares (SFI-LS), is devised to depress the noise in the observation vectors. In this paper, the least square method, improved by a sliding fixed-interval approach, is applied for the real-time noise reduction. In order to achieve a better-performed coarse alignment, the proposed method is utilized to de-noise the random noise in observation vectors. First, the principles of proposed SFI-LS algorithm and coarse alignment… More >

Bin Dong^1,2,3, Changyong Jiang^1,3,*, Xiang Liu^1,3, Lixi Huang^1,3

The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.2, pp. 26-26, 2019, DOI:10.32604/icces.2019.05017

Abstract How to reduce fan noise has always been a significant research topic in equipment ranging from small-scale devices, such as computer cooling fans and building ventilation fans, to large high bypass ratio turbo engines. In recent years, in order to produce higher pressure rise or larger flow rate with lower noise level in the fan stage, interest in the contra-rotating fan (CRF) configuration has been rekindled. The Vold-Kalman order tracking filter technique was employed to separate tonal and broadband noise components from CRF acoustic data to study the characteristics of the noise spectrum. Based on the spectrum peaks, noise reduction… More >