Search Results

In the United States, most school buses are powered by diesel engines. Some have advocated replacing diesel school buses with natural gas school buses, but little research has been conducted to understand the emissions from school bus engines. This work provides a detailed characterization of exhaust emissions from school buses using a diesel engine meeting 1998 emission standards, a low emitting diesel engine with an advanced engine calibration and a catalyzed particulate filter, and a natural gas engine without catalyst. All three bus configurations were tested over the same cycle, test weight, and road load settings. Twenty-one of the 41 “toxic air contaminants” (TACs) listed by the California Air Resources Board (CARB) as being present in diesel exhaust were not found in the exhaust of any of the three bus configurations, even though special sampling provisions were utilized to detect low levels of TACs.

Researchers in the nitrosamine field were contacted on their views of the TEA analyzer and the ThermoSorb/N Air Sampler for nitrosamine analysis. Fifty-eight vehicle interiors were sampled to determine the effects of vehicle type, vehicle age, mode of operation, and ambient conditions on interior nitrosamines. Nitrosamines were found in passenger cars, station-wagons, passenger and cargo vans, pickup trucks, and in new and used heavy-duty trucks, but not in motor homes. The average daily intake of nitrosamines from vehicle interiors for a commuter in a vehicle 3 hours/day was estimated to be less than that from a can of beer or from a strip of bacon.

This paper reviews the use of additives to improve safety aspects associated with the use of methanol as a motor fuel. A survey of the literature was conducted to determine candidate additives for methanol that produce one or more of the following properties: provide a visible or luminous flame, reduce the potential for skin contact, give a foul or unpleasant taste and odor, and act as an emetic. Candidate additives were reviewed to determine potential effectiveness, cost, east of production, health problems, and effects on vehicle performance. Potential additives include complex hydrocarbon mixtures such as gasoline, alcohol soluble dyes and unpalatable compounds such as denatonium benzoate.

Digital bus standardization for new generation digital avionics has nearly been achieved for commercial and military aircraft applications. Installation and certification of first generation digital avionics for business aircraft and commuter transports is now becoming increasingly common. An urgent need exists for the business aviation community to adopt digital bus standards which will allow development of compatible second generation digital avionics equipment.