Diesel engines produce high emissions of nitrogen oxide, smoke and particulate matter. The challenge is to reduce exhaust emissions but without making changing their mechanical configuration. This paper is an overview of the effect of natural gas on the diesel engine emissions. Literature review suggests that engine load, air-fuel ratio, and engine speed play a key role in reducing the pollutants in the diesel engine emissions with natural gas enrichment. It is found that increasing the percentage of natural gas (CNG) will affect emissions. Nitrogen oxide (NOx) is decreased and increased at part loads and high loads respectively when adding CNG. The reduction in carbon dioxide (CO2), particulate matter (PM) and smoke are observed when adding CNG. However, carbon monoxide (CO) and unburned hydrocarbon (HC) are increased when CNG is added.
The purpose of this research is to gain initial knowledge and to predict the sustainability of an all-weather
Micro-Aerial-Vehicle (MAV). The observed parameters are: the maximum coefficient of lift, CL and the
changes in CL after impact, the fluctuation of CL upon entering simulated rain environment, and length of
stability recovery in terms of time and flapping cycle, t and t/T, at flapping frequencies of 8, 16, and 24
Hz, at t/T = 3/8 and 7/8. At 24 Hz, the increase in peak CL value after impact of entering rain environment
is 0.59. The average fluctuations in CL occurred when entering the rain environment are 410.263. The
stability recovery time recorded is 0.006 seconds. Small birds (especially hummingbirds) have a very
high flapping frequency that enables them to efficiently withstand external disturbances caused by nature
and to instantly adapt to new environments.