74,562 research outputs found
Empirical exploration of air traffic and human dynamics in terminal airspaces
Air traffic is widely known as a complex, task-critical techno-social system,
with numerous interactions between airspace, procedures, aircraft and air
traffic controllers. In order to develop and deploy high-level operational
concepts and automation systems scientifically and effectively, it is essential
to conduct an in-depth investigation on the intrinsic traffic-human dynamics
and characteristics, which is not widely seen in the literature. To fill this
gap, we propose a multi-layer network to model and analyze air traffic systems.
A Route-based Airspace Network (RAN) and Flight Trajectory Network (FTN)
encapsulate critical physical and operational characteristics; an Integrated
Flow-Driven Network (IFDN) and Interrelated Conflict-Communication Network
(ICCN) are formulated to represent air traffic flow transmissions and
intervention from air traffic controllers, respectively. Furthermore, a set of
analytical metrics including network variables, complex network attributes,
controllers' cognitive complexity, and chaotic metrics are introduced and
applied in a case study of Guangzhou terminal airspace. Empirical results show
the existence of fundamental diagram and macroscopic fundamental diagram at the
route, sector and terminal levels. Moreover, the dynamics and underlying
mechanisms of "ATCOs-flow" interactions are revealed and interpreted by
adaptive meta-cognition strategies based on network analysis of the ICCN.
Finally, at the system level, chaos is identified in conflict system and human
behavioral system when traffic switch to the semi-stable or congested phase.
This study offers analytical tools for understanding the complex human-flow
interactions at potentially a broad range of air traffic systems, and underpins
future developments and automation of intelligent air traffic management
systems.Comment: 30 pages, 28 figures, currently under revie
The effect of short-term changes in air pollution on respiratory and cardiovascular morbidity in Nicosia, Cyprus.
Presented at the 6th International Conference on Urban Air Quality, Limassol, March, 2007. Short-paper was submitted for peer-review and appears in proceedings of the conference.This study investigates the effect of daily changes in levels of PM10 on the daily volume of respiratory and cardiovascular
admissions in Nicosia, Cyprus during 1995-2004. After controlling for long- (year and month) and short-term (day of the
week) patterns as well as the effect of weather in Generalized Additive Poisson models, some positive associations were
observed with all-cause and cause-specific admissions. Risk of hospitalization increased stepwise across quartiles of days with
increasing levels of PM10 by 1.3% (-0.3, 2.8), 4.9% (3.3, 6.6), 5.6% (3.9, 7.3) as compared to days with the lowest
concentrations. For every 10μg/m3 increase in daily average PM10 concentration, there was a 1.2% (-0.1%, 2.4%) increase in
cardiovascular admissions. With respects to respiratory admissions, an effect was observed only in the warm season with a
1.8% (-0.22, 3.85) increase in admissions per 10μg/m3 increase in PM10. The effect on respiratory admissions seemed to be
much stronger in women and, surprisingly, restricted to people of adult age
A Simulation Framework for Fast Design Space Exploration of Unmanned Air System Traffic Management Policies
The number of daily small Unmanned Aircraft Systems (sUAS) operations in
uncontrolled low altitude airspace is expected to reach into the millions. UAS
Traffic Management (UTM) is an emerging concept aiming at the safe and
efficient management of such very dense traffic, but few studies are addressing
the policies to accommodate such demand and the required ground infrastructure
in suburban or urban environments. Searching for the optimal air traffic
management policy is a combinatorial optimization problem with intractable
complexity when the number of sUAS and the constraints increases. As the
demands on the airspace increase and traffic patterns get complicated, it is
difficult to forecast the potential low altitude airspace hotspots and the
corresponding ground resource requirements. This work presents a Multi-agent
Air Traffic and Resource Usage Simulation (MATRUS) framework that aims for fast
evaluation of different air traffic management policies and the relationship
between policy, environment and resulting traffic patterns. It can also be used
as a tool to decide the resource distribution and launch site location in the
planning of a next-generation smart city. As a case study, detailed comparisons
are provided for the sUAS flight time, conflict ratio, cellular communication
resource usage, for a managed (centrally coordinated) and unmanaged (free
flight) traffic scenario.Comment: The Integrated Communications Navigation and Surveillance (ICNS)
Conference in 201
Improving accessibility at airports
Analyse and evaluate the accessibility at airports to improve the role of this infrastructure at regional level
Introducing the STAMP method in road tunnel safety assessment
After the tremendous accidents in European road tunnels over the past decade, many risk assessment methods have been proposed worldwide, most of them based on Quantitative Risk Assessment (QRA). Although QRAs are helpful to address physical aspects and facilities of tunnels, current approaches in the road tunnel field have limitations to model organizational aspects, software behavior and the adaptation of the tunnel system over time. This paper reviews the aforementioned limitations and highlights the need to enhance the safety assessment process of these critical infrastructures with a complementary approach that links the organizational factors to the operational and technical issues, analyze software behavior and models the dynamics of the tunnel system. To achieve this objective, this paper examines the scope for introducing a safety assessment method which is based on the systems thinking paradigm and draws upon the STAMP model. The method proposed is demonstrated through a case study of a tunnel ventilation system and the results show that it has the potential to identify scenarios that encompass both the technical system and the organizational structure. However, since the method does not provide quantitative estimations of risk, it is recommended to be used as a complementary approach to the traditional risk assessments rather than as an alternative. (C) 2012 Elsevier Ltd. All rights reserved
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