816,133 research outputs found
A Distributed Trajectory-Oriented Approach to Managing Traffic Complexity
In order to handle the expected increase in air traffic volume, the next generation air transportation system is moving towards a distributed control architecture, in which ground-based service providers such as controllers and traffic managers and air-based users such as pilots share responsibility for aircraft trajectory generation and management. While its architecture becomes more distributed, the goal of the Air Traffic Management (ATM) system remains to achieve objectives such as maintaining safety and efficiency. It is, therefore, critical to design appropriate control elements to ensure that aircraft and groundbased actions result in achieving these objectives without unduly restricting user-preferred trajectories. This paper presents a trajectory-oriented approach containing two such elements. One is a trajectory flexibility preservation function, by which aircraft plan their trajectories to preserve flexibility to accommodate unforeseen events. And the other is a trajectory constraint minimization function by which ground-based agents, in collaboration with air-based agents, impose just-enough restrictions on trajectories to achieve ATM objectives, such as separation assurance and flow management. The underlying hypothesis is that preserving trajectory flexibility of each individual aircraft naturally achieves the aggregate objective of avoiding excessive traffic complexity, and that trajectory flexibility is increased by minimizing constraints without jeopardizing the intended ATM objectives. The paper presents conceptually how the two functions operate in a distributed control architecture that includes self separation. The paper illustrates the concept through hypothetical scenarios involving conflict resolution and flow management. It presents a functional analysis of the interaction and information flow between the functions. It also presents an analytical framework for defining metrics and developing methods to preserve trajectory flexibility and minimize its constraints. In this framework flexibility is defined in terms of robustness and adaptability to disturbances and the impact of constraints is illustrated through analysis of a trajectory solution space with limited degrees of freedom and in simple constraint situations involving meeting multiple times of arrival and resolving a conflict
Development and Validation of Functional Model of a Cruise Control System
Modern automobiles can be considered as a collection of many subsystems
working with each other to realize safe transportation of the occupants.
Innovative technologies that make transportation easier are increasingly
incorporated into the automobile in the form of functionalities. These new
functionalities in turn increase the complexity of the system framework present
and traceability is lost or becomes very tricky in the process. This hugely
impacts the development phase of an automobile, in which, the safety and
reliability of the automobile design should be ensured. Hence, there is a need
to ensure operational safety of the vehicles while adding new functionalities
to the vehicle. To address this issue, functional models of such systems are
created and analysed. The main purpose of developing a functional model is to
improve the traceability and reusability of a system which reduces development
time and cost. Operational safety of the system is ensured by analysing the
system with respect to random and systematic failures and including safety
mechanism to prevent such failures. This paper discusses the development and
validation of a functional model of a conventional cruise control system in a
passenger vehicle based on the ISO 26262 Road Vehicles - Functional Safety
standard. A methodology for creating functional architectures and an
architecture of a cruise control system developed using the methodology are
presented.Comment: In Proceedings FESCA 2016, arXiv:1603.0837
Prospects of a mathematical theory of human behavior in complex man-machine systems tasks
A hierarchy of human activities is derived by analyzing automobile driving in general terms. A structural description leads to a block diagram and a time-sharing computer analogy. The range of applicability of existing mathematical models is considered with respect to the hierarchy of human activities in actual complex tasks. Other mathematical tools so far not often applied to man machine systems are also discussed. The mathematical descriptions at least briefly considered here include utility, estimation, control, queueing, and fuzzy set theory as well as artificial intelligence techniques. Some thoughts are given as to how these methods might be integrated and how further work might be pursued
Controllability of Social Networks and the Strategic Use of Random Information
This work is aimed at studying realistic social control strategies for social
networks based on the introduction of random information into the state of
selected driver agents. Deliberately exposing selected agents to random
information is a technique already experimented in recommender systems or
search engines, and represents one of the few options for influencing the
behavior of a social context that could be accepted as ethical, could be fully
disclosed to members, and does not involve the use of force or of deception.
Our research is based on a model of knowledge diffusion applied to a
time-varying adaptive network, and considers two well-known strategies for
influencing social contexts. One is the selection of few influencers for
manipulating their actions in order to drive the whole network to a certain
behavior; the other, instead, drives the network behavior acting on the state
of a large subset of ordinary, scarcely influencing users. The two approaches
have been studied in terms of network and diffusion effects. The network effect
is analyzed through the changes induced on network average degree and
clustering coefficient, while the diffusion effect is based on two ad-hoc
metrics defined to measure the degree of knowledge diffusion and skill level,
as well as the polarization of agent interests. The results, obtained through
simulations on synthetic networks, show a rich dynamics and strong effects on
the communication structure and on the distribution of knowledge and skills,
supporting our hypothesis that the strategic use of random information could
represent a realistic approach to social network controllability, and that with
both strategies, in principle, the control effect could be remarkable
ANCOVA: A global test based on a robust measure of location or quantiles when there is curvature
For two independent groups, let be some conditional measure of
location for the th group associated with some random variable , given
that some covariate . When is a robust measure of location, or
even some conditional quantile of , given , methods have been proposed
and studied that are aimed at testing : that deal with
curvature in a flexible manner. In addition, methods have been studied where
the goal is to control the probability of one or more Type I errors when
testing for each . This paper suggests a
method for testing the global hypothesis : for when using a robust or quantile location estimator.
An obvious advantage of testing hypotheses, rather than the global
hypothesis, is that it can provide information about where regression lines
differ and by how much. But the paper summarizes three general reasons to
suspect that testing the global hypothesis can have more power. 2 Data from the
Well Elderly 2 study illustrate that testing the global hypothesis can make a
practical difference.Comment: 23 pp 2 Figure
Improving Workplace Expertise to Meet Increasing Customer Requirements: The Impact of Training
This article focuses upon the training of engineers at a factory producing integrated circuits. Inadequate use of statistical process techniques by the engineers meant that the production process was not being optimised in the context of increasing customer requirements. A training needs analysis was undertaken and a training programme was developed, implemented and evaluated. The results of this programme are presented and conclusions drawn
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