Abstract: The human behaviors during evacuations are quite complex. One of the critical behaviors which affect the efficiency of evacuation is route choice. Therefore, the respective simulation modeling work needs to function properly. In this paper, Simulation of Urban Mobility’s (SUMO) current dynamic route modeling during evacuation, i.e. the rerouting functions, is examined with a real case study. The result consistency of the simulation and the reality is checked as well. Four influence factors (1) time to get information, (2) probability to cancel a trip, (3) probability to use navigation equipment, and (4) rerouting and information updating period are considered to analyze possible traffic impacts during the evacuation and to examine the rerouting functions in SUMO. Furthermore, some behavioral characters of the case study are analyzed with use of the corresponding detector data and applied in the simulation. The experiment results show that the dynamic route modeling in SUMO can deal with the proposed scenarios properly. Some issues and function needs related to route choice are discussed and further improvements are suggested.
Abstract: The Trustworthy link failure recovery algorithm is
introduced in this paper, to provide the forwarding continuity even
with compound link failures. The ephemeral failures are common in
IP networks and it also has some proposals based on local rerouting.
To ensure forwarding continuity, we are introducing the compound
link failure recovery algorithm, even with compound link failures.
For forwarding the information, each packet carries a blacklist, which
is a min set of failed links encountered along its path, and the next
hop is chosen by excluding the blacklisted links. Our proposed
method describes how it can be applied to ensure forwarding to all
reachable destinations in case of any two or more link or node
failures in the network. After simulating with NS2 contains lot of
samples proved that the proposed protocol achieves exceptional
concert even under elevated node mobility using Trustworthy link
Failure Recovery Algorithm.
Abstract: Signalized intersections on high-volume arterials are
often congested during peak hours, causing a decrease in through
movement efficiency on the arterial. Much of the vehicle delay
incurred at conventional intersections is caused by high left-turn
demand. Unconventional intersection designs attempt to reduce
intersection delay and travel time by rerouting left-turns away from
the main intersection and replacing it with right-turn followed by Uturn.
The proposed new type of U-turn intersection is geometrically
designed with a raised island which provides a protected U-turn
movement. In this study several scenarios based on different
distances between U-turn and main intersection, traffic volume of
major/minor approaches and percentage of left-turn volumes were
simulated by use of AIMSUN, a type of traffic microsimulation
software. Subsequently some models are proposed in order to
compute travel time of each movement. Eventually by correlating
these equations to some in-field collected data of some implemented
U-turn facilities, the reliability of the proposed models are approved.
With these models it would be possible to calculate travel time of
each movement under any kind of geometric and traffic condition. By
comparing travel time of a conventional signalized intersection with
U-turn intersection travel time, it would be possible to decide on
converting signalized intersections into this new kind of U-turn
facility or not. However comparison of travel time is not part of the
scope of this research. In this paper only travel time of this innovative
U-turn facility would be predicted. According to some before and
after study about the traffic performance of some executed U-turn
facilities, it is found that commonly, this new type of U-turn facility
produces lower travel time. Thus, evaluation of using this type of
unconventional intersection should be seriously considered.
Abstract: In this paper we propose a new traffic simulation
package, TDMSim, which supports both macroscopic and
microscopic simulation on free-flowing and regulated traffic systems.
Both simulators are based on travel demands, which specify the
numbers of vehicles departing from origins to arrive at different
destinations. The microscopic simulator implements the carfollowing
model given the pre-defined routes of the vehicles but also
supports the rerouting of vehicles. We also propose a macroscopic
simulator which is built in integration with the microscopic simulator
to allow the simulation to be scaled for larger networks without
sacrificing the precision achievable through the microscopic
simulator. The macroscopic simulator also enables the reuse of
previous simulation results when simulating traffic on the same
networks at later time. Validations have been conducted to show the
correctness of both simulators.
Abstract: To support mobility in ATM networks, a number of
technical challenges need to be resolved. The impact of handoff
schemes in terms of service disruption, handoff latency, cost
implications and excess resources required during handoffs needs to
be addressed. In this paper, a one phase handoff and route
optimization solution using reserved PVCs between adjacent ATM
switches to reroute connections during inter-switch handoff is
studied. In the second phase, a distributed optimization process is
initiated to optimally reroute handoff connections. The main
objective is to find the optimal operating point at which to perform
optimization subject to cost constraint with the purpose of reducing
blocking probability of inter-switch handoff calls for delay tolerant
traffic. We examine the relation between the required bandwidth
resources and optimization rate. Also we calculate and study the
handoff blocking probability due to lack of bandwidth for resources
reserved to facilitate the rapid rerouting.
Abstract: With the advantage of wireless network technology,
there are a variety of mobile applications which make the issue of
wireless sensor networks as a popular research area in recent years.
As the wireless sensor network nodes move arbitrarily with the
topology fast change feature, mobile nodes are often confronted with
the void issue which will initiate packet losing, retransmitting,
rerouting, additional transmission cost and power consumption.
When transmitting packets, we would not predict void problem
occurring in advance. Thus, how to improve geographic routing with
void avoidance in wireless networks becomes an important issue. In
this paper, we proposed a greedy geographical void routing algorithm
to solve the void problem for wireless sensor networks. We use the
information of source node and void area to draw two tangents to
form a fan range of the existence void which can announce voidavoiding
message. Then we use source and destination nodes to draw
a line with an angle of the fan range to select the next forwarding
neighbor node for routing. In a dynamic wireless sensor network
environment, the proposed greedy void avoiding algorithm can be
more time-saving and more efficient to forward packets, and improve
current geographical void problem of wireless sensor networks.