http://www.seipub.org/AIAAS/RSS.aspxen-US2013-08<p class="abstract">Diesel Engine Air-borne Acoustic Signals Analysis Using Continuous Wavelet Transform</p><ul><li>Pages 77-82</li><li>Author A. Albarba</li><li>Abstract This paper studies the characteristics of Diesel engine air-borne acoustic signals using time-frequency domain techniques. One analysis technique is investigated: Continuous Wavelet Transform (CWT) which is reviewed from the mathematical point of view, based on its developmental stages, drawbacks and the subsequent improvements. The detection capabilities of this technique are evaluated using air-borne acoustic signals collected from diesel engine in acoustically untreated laboratory. Some engine conditions and faults are investigated using CWT techniques. The achieved results prove the technique’s sensitivity to engine’s speed and load variations. More important, the CWT shows excellent capabilities in detecting engine’s injection process and lubrication related faults at early stages. At the end of the paper, summary is given.</li></ul>http://www.seipub.org/AIAAS/PaperInfo.aspx?ID=5643Advances in Applied Acousticshttp://www.seipub.org/AIAAS/PaperInfo.aspx?ID=56432013-08<p class="abstract">Investigation of Noise Pollution Levels of Four Selected Sawmill Factories in Delta State, Nigeria</p><ul><li>Pages 83-90</li><li>Author E. O AgbalagbaA.N. O AkpataS.A. Olal</li><li>Abstract A survey on noise pollution levels in four selected sawmill factories in Delta State has been conducted. The investigations involve physical measurement of the noise pollution levels using a BK precision digital sound level meter model IEC 651 type and a social survey, using questionnaire. The physical measurement assessed the different machines noise level in the factories and the background noise levels measured at 50 meters away from the factories. A mean level of machine noise pollution (and background noise level) of 103.77±4.71dBA (78.25dBA), 96.55 1.48(72.08), 99.02±3.20 (72.54), 99.97±3.66 (79.89) dBA was recorded in Ozoro, Ughelli, Warri and Sapele respectively. These values obtained show that the noise levels in the four factories investigated are well above the FEPA recommended maximum permissible limits for an industrial environment. This may cause hearing impairment and some psychological effect like susceptibility to mistake, irritation, and sleeping and social discomfort among staff and resident living in close to these factories. This is further affirmed by the social survey result which revealed the level of social discomfort and health menace caused by machines noise from the factories on the workers and those residing close to these factories. Recommendations were therefore made to control, and abate this health threatening pollution effects.</li></ul>http://www.seipub.org/AIAAS/PaperInfo.aspx?ID=5668Advances in Applied Acousticshttp://www.seipub.org/AIAAS/PaperInfo.aspx?ID=5668