13,216 research outputs found
Evacuation in the Social Force Model is not stationary
An evacuation process is simulated within the Social Force Model. Thousand
pedestrians are leaving a room by one exit. We investigate the stationarity of
the distribution of time lags between instants when two successive pedestrians
cross the exit. The exponential tail of the distribution is shown to gradually
vanish. Taking fluctuations apart, the time lags decrease in time till there
are only about 50 pedestrians in the room, then they start to increase. This
suggests that at the last stage the flow is laminar. In the first stage,
clogging events slow the evacuation down. As they are more likely for larger
crowds, the flow is not stationary. The data are investigated with detrended
fluctuation analysis.Comment: 7 pages, 3 figures; PACS numbers: 89.75.Fb, 05.40.-a, 05.45.Tp,
89.40.B
Applications of physical methods in high-frequency futures markets
In the present work we demonstrate the application of different physical
methods to high-frequency or tick-by-tick financial time series data. In
particular, we calculate the Hurst exponent and inverse statistics for the
price time series taken from a range of futures indices. Additionally, we show
that in a limit order book the relaxation times of an imbalanced book state
with more demand or supply can be described by stretched exponential laws
analogous to those seen in many physical systems.Comment: 14 Pages and 10 figures. Proceeding to the SPIE conference, 4 - 7
December 2007 Australian National Univ. Canberra, ACT, Australi
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