scholarly journals Sound Power Characteristics of Chinese Traditional Wind Instrument Qudi

2021 ◽  
Vol 7 (1) ◽  
pp. 8
Author(s):  
Jianzhen Qiu ◽  
Shuoxian Wu ◽  
Yuezhe Zhao ◽  
Hong Huang ◽  
Liling Wu
Keyword(s):  
Sound Power ◽  
Power Characteristics ◽  
Wind Instrument

Design and Verification of Cooling Fans for Engine Rooms of Mobile Hydraulics Vehicles

2019 ◽  
Author(s):  
J.-H. Kim ◽  
G.-P. Lee ◽  
C.-H. Lim ◽  
S. Lee
Keyword(s):  
Acoustic Noise ◽  
Power Level ◽  
Design Parameters ◽  
Sound Power ◽  
Axial Fan ◽  
Noise Sources ◽  
Sweep Angle ◽  
Angle Variation ◽  
Power Characteristics ◽  
A Charge

Abstract To provide an engine room of mobile hydraulic vehicle with an effective cooling for the combination set of a radiator, a charge air cooler, and an oil cooler, a 500mm-diameter, axial fan is designed to have a 8,800 m3/hr at a resistance of 20mm Aq static pressure with a sound power level less than 86 LwA. The design parameters of sweep angle amplitude, wavelength of sweep angle change, airfoil type, and stagger angle are examined in terms of fan performance and its sound power generation. The surface curvatures generated by the sinusoidal sweep angle variation in the radial direction are proved to result in quite different flow patterns, thereby different types of specific sound power characteristics at the same flowrate. The acoustic noise sources are examined and discussed by using an acoustic imaging technique.

Sound power level measurement of Sheng, a Chinese wind instrument

2008 ◽  
Vol 123 (5) ◽  
pp. 3240-3240
Author(s):  
Yue Zhe Zhao ◽  
Shuo Xian Wu ◽  
Jian Zhen Qiu ◽  
Li Ling Wu ◽  
Hong Huang
Keyword(s):  
Power Level ◽  
Sound Power ◽  
Level Measurement ◽  
Wind Instrument ◽  
Sound Power Level

scholarly journals Influence of Vertical Fastener Stiffness on Rail Sound Power Characteristics: Numerical Study and Field Measurement

2020 ◽  
Vol 10 (5) ◽  
pp. 1682
Author(s):  
Xi Sheng ◽  
Ying Zhang ◽  
Xiaozhou Liu
Keyword(s):  
Decay Rate ◽  
Numerical Study ◽  
Power Level ◽  
Field Measurements ◽  
Spectral Element ◽  
Center Frequency ◽  
Sound Power ◽  
Power Characteristics ◽  
Sound Power Level ◽  
Rolling Noise

The aim of this paper is to investigate the influence of vertical fastener stiffness on the sound power characteristics of rail rolling noise. The rail mobility is obtained by using the Timoshenko-beam track model and the spectral element method. The decay rate is obtained by using the periodic track model and the spectral transfer matrix method. Then, the simulation results of the rail mobility and the decay rate are used to calculate the sound power level of the rail subjected to a harmonic point excitation. Furthermore, the influence of vertical fastener stiffness on the rail sound power level is investigated. Finally, field measurements of the rail accelerance and the decay rate are performed to verify the accuracy of models and calculation methods. The results show that the sound power level of the rail subjected to a harmonic point excitation increases with the increase of the frequency and peaks at the center frequency of 800 Hz. When the vertical fastener stiffness decreases from 50 kN/mm, the rail sound power level below the center frequency of 200 Hz gets increased. The increase of the sound power level is most significant at the center frequency which is close to the decreased vertical rail resonance frequency, because in the corresponding one-third octave band the rail mobility amplitude increases significantly while the decay rate decreases considerably. The simulations of the rail accelerance and the decay rate both coincide well with the measurements.

DEPENDENCES OF POWER CHARACTERISTICS OF CIRCUIT AT CHARGE OF SUPERCAPACITORS

2016 ◽  
Vol 2016 (1) ◽  
pp. 3-10 ◽  
Author(s):  
O.A. Beletsky ◽  
◽  
N.I. Suprunovska ◽  
A.A. Shcherba ◽  
◽  
...  
Keyword(s):  
Power Characteristics

SPATIAL AND POWER CHARACTERISTICS OF FOCUSED MODES OF THE METAL CAVITY OF A TERAHERTZ LASER

2019 ◽  
Vol 78 (5) ◽  
pp. 373-383 ◽  
Author(s):  
S. A. Vlasenko ◽  
А. V. Degtyarev ◽  
M. M. Dubinin ◽  
V. A. Maslov
Keyword(s):  
Power Characteristics

Active control of compressor noise in the machinery room of refrigerators

2019 ◽  
Vol 67 (5) ◽  
pp. 350-362
Author(s):  
J. M. Ku ◽  
W. B. Jeong ◽  
C. Hong
Keyword(s):  
Control System ◽  
Active Control ◽  
Weighting Function ◽  
Reference Signal ◽  
Active Noise Control ◽  
Dominant Frequency ◽  
Time Signal ◽  
Frequency Noise ◽  
Sound Power ◽  
Fxlms Algorithm

The low-frequency noise generated by the vibration of the compressor in the machinery room of refrigerators is considered as annoying sound. Active noise control is used to reduce this noise without any change in the design of the compressor in the machinery room. In configuring the control system, various signals are measured and analyzed to select the reference signal that best represents the compressor noise. As the space inside the machinery room is small, the size of a speaker is limited, and the magnitude of the controller transfer function is designed to be small at low frequencies, the controller uses FIR filter structure converged by the FxLMS algorithm using the pre-measured time signal. To manage the convergence speed for each frequency, the frequency-weighting function is applied to FxLMS algorithm. A series of measurements are performed to design the controller and to evaluate the control performance. After the control, the sound power transmitted by the refrigerator is reduced by 9 dB at the first dominant frequency (408 Hz in this case) and 3 dB at the second dominant frequency (459 Hz here), and the overall sound power decreases by 2.6 dB. Through this study, an active control system for the noise generated by refrigerator compressors is established.

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