4,042 research outputs found
Fast Two-Robot Disk Evacuation with Wireless Communication
In the fast evacuation problem, we study the path planning problem for two
robots who want to minimize the worst-case evacuation time on the unit disk.
The robots are initially placed at the center of the disk. In order to
evacuate, they need to reach an unknown point, the exit, on the boundary of the
disk. Once one of the robots finds the exit, it will instantaneously notify the
other agent, who will make a beeline to it.
The problem has been studied for robots with the same speed~\cite{s1}. We
study a more general case where one robot has speed and the other has speed
. We provide optimal evacuation strategies in the case that by showing matching upper and lower bounds on the
worst-case evacuation time. For , we show (non-matching)
upper and lower bounds on the evacuation time with a ratio less than .
Moreover, we demonstrate that a generalization of the two-robot search strategy
from~\cite{s1} is outperformed by our proposed strategies for any .Comment: 18 pages, 10 figure
Evacuation time estimate for a total pedestrian evacuation using queuing network model and volunteered geographic information
Estimating city evacuation time is a non-trivial problem due to the
interaction between thousands of individual agents, giving rise to various
collective phenomena, such as bottleneck formation, intermittent flow and
stop-and-go waves. We present a mean field approach to draw relationships
between road network spatial attributes, number of evacuees and resultant
evacuation time estimate (ETE). We divide medium sized UK cities into a
total of catchment areas which we define as an area where all agents
share the same nearest exit node. In these catchment areas, 90% of agents are
within km of their designated exit node. We establish a characteristic
flow rate from catchment area attributes (population, distance to exit node and
exit node width) and a mean flow rate in free-flow regime by simulating total
evacuations using an agent based `queuing network' model. We use these
variables to determine a relationship between catchment area attributes and
resultant ETE. This relationship could enable emergency planners to make rapid
appraisal of evacuation strategies and help support decisions in the run up to
a crisis.Comment: 6 pages, 8 figure
Time-Energy Tradeoffs for Evacuation by Two Robots in the Wireless Model
Two robots stand at the origin of the infinite line and are tasked with
searching collaboratively for an exit at an unknown location on the line. They
can travel at maximum speed and can change speed or direction at any time.
The two robots can communicate with each other at any distance and at any time.
The task is completed when the last robot arrives at the exit and evacuates. We
study time-energy tradeoffs for the above evacuation problem. The evacuation
time is the time it takes the last robot to reach the exit. The energy it takes
for a robot to travel a distance at speed is measured as . The
total and makespan evacuation energies are respectively the sum and maximum of
the energy consumption of the two robots while executing the evacuation
algorithm.
Assuming that the maximum speed is , and the evacuation time is at most
, where is the distance of the exit from the origin, we study the
problem of minimizing the total energy consumption of the robots. We prove that
the problem is solvable only for . For the case , we give an
optimal algorithm, and give upper bounds on the energy for the case .
We also consider the problem of minimizing the evacuation time when the
available energy is bounded by . Surprisingly, when is a
constant, independent of the distance of the exit from the origin, we prove
that evacuation is possible in time , and this is optimal up
to a logarithmic factor. When is linear in , we give upper bounds
on the evacuation time.Comment: This is the full version of the paper with the same title which will
appear in the proceedings of the 26th International Colloquium on Structural
Information and Communication Complexity (SIROCCO'19) L'Aquila, Italy during
July 1-4, 201
Deceleration in The Micro Traffic Model and Its Application to Simulation for Evacuation from Disaster Area
Referring to the NagelâSchreckenbergâs (NaSch) model, we have studied the impact of agent and diligent driver into the micro traffic model in the case of evacuation. This study is attention to the deceleration that added in the micro traffic model. The effect of deceleration to simulation for evacuation from disaster area is considered. The traffic flow property is studied by analyzing the time-space diagram. The simulation results show that deceleration caused the evacuation time increases when we compare it by without deceleration
Optimising Pedestrian Flow Around Large Stadiums
This study proposes a method that combines the cellular automaton model and the differential evolution algorithm for optimising pedestrian flow around large stadiums. A miniature version of a large stadium and its surrounding areas is constructed via the cellular automaton model. Special mechanisms are applied to influence the behaviour of an agent that leaves from a certain stadium gate. The agent may be attracted to a nearby business facility and/or guided to uncongested areas. The differential evolution algorithm is then used to determine the optimal probabilities of the influencing agents for each stadium gate. The main goal is to reduce the evacuation time, and other goals such as reducing the costs for the influencing agentsâ behaviours and the individual evacuation time are also considered. We found that, although they worked differently in different scenarios, the attraction and guidance of agents significantly reduced the evacuation time. The optimal evacuation time was achieved with moderate attraction to the business facilities and strong guidance to the detouring route. The results demonstrate that the proposed method can provide a goal-dependent, exit-specific strategy that is otherwise hard to acquire for optimising pedestrian flow
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