Lim Eng Aik
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Lim Eng Aik
Official Name
Lim, Eng Aik
Alternative Name
Aik, Limeng
Lim, E. A.
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Scopus Author ID
23491376300
Researcher ID
EKL-8415-2022

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In-situ Noise Measurement and Analysis for the Motorcycle Muffler

2020-01-01 , Tan Wei Hong , Chuah H.G. , Cheng Ee Meng , Lim Eng Aik , Lok, Chip Hao

Noise from the vehicles is one of the noise pollutions to the environment. The noises emitted by the vehicles have to obey the requirement of regulation of maximum sound pressure level permitted for respective vehicles. In this study, the aim is to reduce the noise emitted from the motorcycle muffler. The noise emitted from the motorcycle muffler is analyzed and measured using a sound level meter. The average sound pressure level of the motorcycle muffler is determined in certain conditions. The sound pressure levels for original installed muffler are recorded as 76.4dB, 79.5dB and 82.3dB under the constant speed of 10km/hr, 20km/hr and 30km/hr respectively by engaging 2nd gear. For the acceleration with the scope of 0 km/hr to 30 km/hr, the difference of sound pressure level between 2nd and 4th gear engaged is 5.4dB. The study is continued by using a modified muffler which contains sound absorptive materials. The absorptive materials chosen are glass wool, cotton and Styrofoam and they are taking turn to be placed into the modified muffler to reduce the sound pressure level. Then the experiment is repeated. By applying 100g absorptive materials in the modified muffler, the reduction of sound pressure level are recorded as 12.6% (glass wool), 7.5% (cotton) and 4.4% (Styrofoam) compared with original installed muffler while 2nd gear engaged. Styrofoam is observed does not perform significantly in absorbing sound or noise in this study. Glass wool demonstrates relatively better sound energy absorption compared with cotton. In general, soft and porous materials are considered good performance in sound absorption. Denser materials are better at soundproofing or sound blocking. Therefore, glass wool with relatively higher density among the investigated absorptive materials in this study has the greatest sound absorption performance.

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MICROWAVE ABSORPTION ANALYSIS ON HEATED EDIBLE SPIRULINA WITH VARIOUS TEMPERATURES

2023-05-01 , Cheng Ee Meng , Tan Wei Hong , Tan Wee Choon , Lim Eng Aik

This paper discusses the microwave absorption analysis of edible Spirulina by using WR62 and WR90 rectangular waveguides in conjunction with Agilent P-series Vector Network Analyzer (PNA). Heat might lead to the degradation of spirulina. This phenomenon involves the chemical and physical reaction that is associated with the variation of dielectric properties. These properties determine the propagation mechanism of microwaves within the sample or material. Hence, an assessment method to detect a nutrient change in spirulina due to heat is necessary. In this context, a microwave absorption measurement system was developed to study the reflection coefficient, transmission coefficient, and absorption coefficient of Spirulina tablets over temperature. The transmission/Reflection line method is well-known because it is non-destructive and rapid in analyzing chemical and physical properties. In this work, Spirulina tablet is used since it is a popular food supplement that is believed to be able to treat diseases is and good for health. The reflection, transmission, and absorption measurements were conducted on Spirulina from 12.4GHz to 18GHz.

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Acoustical simulation and analysis on the resonator muffler

2022-10-01 , Tan Wei Hong , Cheng Ee Meng , Lim Eng Aik , Tan Wee Choon , Amaresh S.G.

With the modernisation of transport during the period of industrial urbanization, vehicles on the road are increasing, and it brings noise disturbances caused by the internal combustion engine of vehicles. This study involves the acoustical model development and analysis of the vehicle muffler. In this study, the resonator type of muffler is considered, and the transmission loss (TL) is used as the parameter to evaluate the acoustic performance of the muffler. The muffler CAD model is created using Solid works, and the acoustical analysis is conducted using COMSOL Multiphysics. The developed muffler model is tuned several times to obtain the optimum TL. The study yielded a wide range of TL across a range of frequencies. It is found that constrictions to the intake and exhaust pipes generated a higher TL by ~20dB than the original dimensions. Using an acoustic dampener further increases the TL of the muffler with a maximum increase of 18%. The inclusion of an acoustic dampener paired with the reduced diameter of the intake and exhaust pipes resulted in the analytical model generating the highest TL in the resonator muffler.

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