Transmission loss measurement in time domain using an impulse technique in ducts

The study of the three-dimensional acoustic field inside an exhaust muffler is usually performed through the numerical solution of the linearized equations. In this paper, an alternative procedure is proposed, in which the full equations are solved in the time domain. The procedure is based on the CFD simulation of an impulsive test, so that the transmission loss may be computed and compared with measurements and other numerical approaches. Also, the details of the flow inside the muffler may be studied, both in the time and the frequency domains. The results obtained compare favorably with a conventional FEM calculation, mostly in the ability of the procedure to account for dissipative processes inside the muffler.

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Investigation on the effects of resistive loading on wrapped bow-tie antennas

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078718001630 ◽

2019 ◽

Vol 11 (4) ◽

pp. 390-400 ◽

Cited By ~ 2

Author(s):

Doojin Lee ◽

George Shaker ◽

William Melek

Keyword(s):

Numerical Analysis ◽

Time Domain ◽

Group Delay ◽

Transmission Loss ◽

Flexible Substrate ◽

Resistive Loading ◽

Communication Ability ◽

Radar Applications ◽

The Time Domain ◽

Bow Tie

AbstractThe pulse radiating characteristic of a wrapped bow-tie antenna (WBA) and wrapped resistively loaded bow-tie antenna (WRLBA) is presented for impulse radar applications in this paper. The numerical analysis of the WRLBA is performed by comparing that of the WBA. The wrapped antennas are realized on a flexible substrate. The antennas are fed by an impedance tapered balun, which has an overall transmission loss of −1.4 dB over the balun length. The characteristics of the resistive loading to the wrapped antenna, such as reflection coefficient, reflected pulse in the time domain, voltage standing wave ratio, and input impedance, are experimentally investigated and compared with simulated results. The fidelity factor of the radiated electric field on the boresight direction for the WBA and WRLBA is calculated as 0.82 and 0.96, respectively. The wireless communication ability is evaluated by the transmission coefficient, group delay, boresight gain, and received waveform. The calculated fidelity factor of the received waveform for the WBA and WRLBA is 0.79 and 0.85, respectively. The average and variations of the group delay of both wrapped antennas are observed to be around 2.5 ns and less than 1.5 ns, respectively.

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Accuracy Improvement of Small Acoustic Chamber for Sound Transmission Loss Measurement

Journal of the Korean Society for Environmental Technology ◽

10.26511/jkset.19.1.7 ◽

2018 ◽

Vol 19 (1) ◽

pp. 58-64

Author(s):

Da Rae Kim ◽

Tae Min Kim ◽

Jeong Tae Kim ◽

Jung Soo Kim

Keyword(s):

Transmission Loss ◽

Sound Transmission ◽

Sound Transmission Loss ◽

Accuracy Improvement ◽

Loss Measurement ◽

Acoustic Chamber

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The design of small reverberation chambers for transmission loss measurement

Applied Acoustics ◽

10.1016/0003-682x(76)90015-3 ◽

1976 ◽

Vol 9 (3) ◽

pp. 165-175 ◽

Cited By ~ 1

Author(s):

Chung Y. Tsui ◽

Carl R. Voorhees ◽

Jackson C.S. Yang

Keyword(s):

Transmission Loss ◽

Loss Measurement ◽

Reverberation Chambers

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Finite-Difference Time-Domain Analysis of Sound Insulation Performance of Wall Systems

Building Acoustics ◽

10.1260/135101009789877004 ◽

2009 ◽

Vol 16 (3) ◽

pp. 267-281 ◽

Cited By ~ 9

Author(s):

Takumi Asakura ◽

Shinichi Sakamoto

Keyword(s):

Numerical Analysis ◽

Finite Difference ◽

Energy Loss ◽

Time Domain ◽

Finite Difference Time Domain ◽

Transmission Loss ◽

Fdtd Method ◽

Sound Insulation ◽

Insulation Performance ◽

Difference Time

A prediction method for the sound insulation of walls by vibro-acoustical numerical analysis using the finite-difference time-domain (FDTD) method is described. In order to accurately predict the sound insulation performance of walls, numerical modeling of the vibration energy loss of walls in the vibration analysis is necessary. In this study, the energy loss at the boundary part of the plates and the internal damping of the plates are modeled and the sound transmission loss of glass plates and plasterboard walls is calculated. A reasonable agreement is found between the calculation and measurement results and the applicability of the numerical analysis is confirmed.

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