Crossover phenomenon in vehicle emissions with DFA Wei Pan College of Physical Science and Technology, Guangxi University, China. August 13, 2013

Introduction Data collection of vehicle emission Detrended Fluctuation Analysis (DFA) Crossover Phenomenon in vehicle emission Notes

Introduction Why so stuck! The problem in the traffic flow:

The problem behind the traffic flow: gasoline oxygen Vehicle emissions

Data collection Place ： Nathan Road, Mong Kok, Hong Kong Time : Rush hours ( 6:59:25~9:01:56 in the morning 16:52:31~18:16:12 in the afternoon ) Instrument : TSI model 982 Target : CO and CO 2 Cooperate with the City University of Hong Kong

Sequence of concentration for carbon emission

Normalized distributions of concentrations

DFA Detrended fluctuation analysis (DFA), first proposed by Peng et al. in 1994 [Phys. Rev. E 49, 1685–1689] And now it becomes a scaling analysis method for detection of long-range correlations embedded in data sequence.

whereis the length of the signal. Then divide the integrated signal into boxes of equal lengthand fit them by using a polynomial function. For a given box size, Integrate the time series

For different scales (box sizes ), we get is long-rang anticorrelation is long-rang correlation is no correlation

DFA fluctuation functionversus the scalein log-log plots Crossover phenomenon

Statistical analysis suggests that the major concentration distributions of carbon emission have little change. A crossover phenomenon has been found, which verifies the long-term dependence of carbon emission from vehicles. Notes

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