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|Title: ||On the use of lattice-gas model for studying pedestrian flow in built environment|
|Other Titles: ||Ying yong ge zi qi mo xing yan jiu jian zhu wu nei de ren liu wen ti|
|Authors: ||Liang, Jing (梁靜)|
|Department: ||Department of Building and Construction|
|Degree: ||Master of Philosophy|
|Issue Date: ||2009|
|Publisher: ||City University of Hong Kong|
|Subjects: ||Pedestrian facilities design.|
|Notes: ||CityU Call Number: NA2543.P4 L53 2009|
xii, 80 leaves : ill. 30 cm.
Thesis (M.Phil.)--City University of Hong Kong, 2009.
Includes bibliographical references (leaves 73-75)
|Abstract: ||Pedestrian flow in built environment has attracted considerable attention
and been extensively studied, to research its characteristic is important for our life.
Computational simulation is one of the main methods. In this thesis, lattice-gas
model will be chosen to study pedestrian flow for two conditions.
Based on the traditional lattice-gas model of biased random walkers, new
improved models are established. In the new models the occupied cell of a
pedestrian is divided into 8*8 small grids. This improvement brings some
advantages: the discrete model is made to close to be continuous in space, and the
walkers could not have to align in order, moreover for ConditionⅠ the width of
exit could be more accurate, not must be an integer times of a pedestrian size.
Also the influence from built environment is taken into account. Simulation
model A and B are built up for ConditionⅠ, model C and D are for ConditionⅡ.
ConditionⅠ is evacuation from the room. Firstly, some simulation results
obtained by new improved models are compared with those by the social force
model. It is found that some important phenomena which have been observed by
social force model could also be reproduced by the new improved model with
much less time. Then a serious of numerical study is done by the new improved
model. The results show that with the width of exit and occupancy loading
increasing, the evacuation time will decrease dramatically, and different steps in
unit time do not change the general trend. However, when the width and
occupancy loading reach a certain value, evacuation time will nearly have no
change. The sensitivity of drift point, which is an important parameter for the new
model, has been also investigated. It is found that with increase of the drift point
forward, evacuation time will decrease and then tend to be smooth when drift
point forward reaches a certain value. And the proportion of drift point forward and to go left (right) is also found to be mainly affected by the shape of the room,
but slight impact from the width of the exit.
ConditionⅡ is pedestrian counter flow. At first the data from a previous
experimental study is used to compare with the simulation results by the new
improved model with totally the same condition to found appreciate parameters.
The results show that when the step in unit time is chosen as 1/2*cnt or 1/4*cnt
and drift point is selected between 0.5 and 0.7, the simulation result will agree
with the experimental data well. Then some numerical study for the jamming
transition has been done for the pedestrian counter flow in a channel with
constant density on two boundaries. The results show that the system size and
ratio of total density of two boundaries have little influence on the general trend
of velocity and occupancy against total density, and also the transition point has
almost no change. However the value of total density corresponding to transition
point is greatly affected by the step in unit time and drift point. With the decrease
of the step in unit time, the transition point will decrease apparently. But with the
increase of the drift point, the transition point will decrease dramatically.|
|Online Catalog Link: ||http://lib.cityu.edu.hk/record=b2374878|
|Appears in Collections:||BC - Master of Philosophy |
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