The use of alternative fuels is considered to be an effective measure to meet strict emissions regulations of particulate matter (PM) and oxides of nitrogen (NO x ). In response to these requirements, emissions data from inuse alternative fuel and diesel-powered heavy-duty vehicles have been measured and collected from 32 transit agencies in 17 states using the two West Virginia University (WVU) transportable heavy-duty vehicle emissions testing laboratories (THDVETLs). More than 600 tests have been performed on over 300 buses and heavy trucks operating on alternative fuels such as natural gas, methanol, and ethanol and also operating on conventional fuel diesel. Regulated emissions of PM, NO x , carbon monoxide (CO), and total hydrocarbon (HC) have been measured and analyzed. In this study, emissions data from alternative fuel buses and diesel control buses are carefully compared. The results show that natural gas, methanol, and ethanol have a strong potential to reduce PM and NO x emissions levels.
<div class="htmlview paragraph">For adapting the demands of the rapid changing and enhancing the competing capability of enterprise in the international market, various modern manufacturing systems have been put forward, which are aimed at various specifications, perfect performance and high quality, low production cost and short manufacturing cycle of products, virtual manufacturing system (VMS) has been emerged as the times require, which is effective technology to meet the challenge of 21 century's manufacturing industries. Based on analyzing modern manufacturing systems, according to the characteristics and requirement of VMS, in this paper, the architecture, the key technologies and the implement way of VMS were explored, and development environment for VMS was put forward, which is a powerful tool for building VMS.</div>
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