The cavity inside microphone of two-way radio can induced noise when involved in outdoor and windy condition. An investigation was performed in Viwika wind tunnel involving a flow visualizations techniques to clarify the flow noise behavior generated by the wind, particularly within the cavity. A smoke wire test was conducted using a cavity model at varying aspect ratio (L/D) between 0.7 and 3 in angle of attack of 0º with Reynolds number of 7831. A two-dimensional Computational Fluid Dynamic (CFD) models based on k-Epsilon turbulence model were conducted to validate the flow visualization result. The results revealed that the deep cavity with an aspect ratio (L/D) of 0.7 produced a single clockwise vortical flow structure and the aspect ratio (L/D) of 3 show the complex flow structure which two recirculation flow vortices were produced inside the cavity. The flow behavior in the CFD simulation was similar to the smoke test. It is shown the flow behaviour inside cavities was control by the aspect ratio (L/D).
An experimental study was conducted to investigate the wind noise produced inside the cavity model that replicate the two-way radio’s cavity. The experiment conducted with varies of cavity distance from the wind source of P1 (0.01m), P3 (0.078m), and P5 (0.146m) at the wind speed of 3.75m/s. The cavity has a length to depth ratios of 1.4. This preliminary measurement was to highlight the relationship between cavity positions and low speed wind flow that affect the sound pressure level occurred inside the cavity. The study also look on the impact this factor on the performance of two-way radio that causes unclear signal interference during windy condition. The results show that by increasing the distance of cavity position, the sound pressure level decreased. It shows that the farthest distance from the wind source, the noise level reduces.
The objective of this paper is to examine the relationship between different forms of social capital and subjective well-being in Malaysia. Subjective well-being is observed based on two aspects: happiness and life satisfaction. The analysis using data from the World Value Survey with 1300 respondents. Based on the ordered probit regression analysis, it is found that bonding and linking social capital contribute to happiness. Happiness also increases for those who are more active in associations. However, bridging social capital based on trust of people from other religion and ethnic group as well as people whom an individual does not know have adverse contribution to happiness. Only linking social capital has a positive relationship with life satisfaction. In terms of religiosity, importance of God seems to have positive relationship with both happiness and life satisfaction. Other factors such as health status, income, marital status and education also have the influence on Malaysians’ happiness and life satisfaction levels.
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