English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

Emission factors for black carbon (BC) and particle number (PN) were measured from 226 individual heavy-duty (HD) diesel trucks driving through a 1-km-long California highway tunnel in August 2006. Emission factors were based on concurrent increases in BC, PN, and CO2 concentrations (measured at 1 Hz) that corresponded to the passage of individual HD trucks. The distributions of BC and PN emission factors from individual HD trucks are skewed, meaning that a large fraction of pollution comes from a small fraction of the in-use vehicle fleet. The highest-emitting 10% of trucks were responsible for approximately 40% of total BC and PN emissions from all HD trucks. BC emissions were log-normally distributed with a mean emission factor of 1.7 g kg(-1) and maximum values of approximately 10 g kg(-1). Corresponding values for PN emission factors were 4.7 x 10(15) and 4 x 10(16) # kg(-1). There was minimal overlap among high-emitters of these two pollutants: only 1 of the 226 HD trucks measured was found to be among the highest 10% for both BC and PN. Monte Carlo resampling of the distribution of BC emission factors observed in this study revealed that uncertainties (1sigma) in extrapolating from a random sample of n HD trucks to a population mean emission factor ranged from +/- 43% for n=10 to +/- 8% for n=300, illustrating the importance of vehicle sample sizes in emissions studies. When n=10, sample means are more likely to be biased due to misrepresentation of high-emitters. As vehicles become cleaner on average in the future, skewness of the emissions distributions will increase, and thus sample sizes needed to extrapolate reliably from a subset of vehicles to the entire in-use vehicle fleet will become more of a challenge.

Measurement of Black Carbon and Particle Number Emission Factors from Individual Heavy-Duty Trucks