Voyage dans le temps

Le voyage dans le temps est un des grands thèmes de la science-fiction, au point d’être considéré comme un genre à part entière. L’idée d’aller revivre le passé ou de découvrir à l’avance le futur est un rêve humain causé par le fait que l’être humain avance dans le temps de manière permanente, mais irréversible (et, à l’état de veille, apparemment de façon linéaire). La première mention d’un voyage dans le temps serait le personnage de Merlin l’Enchanteur dans le cycle arthurien des chevaliers de la Table ronde, qui visitait les temps passés. Les Celtes croyaient en la possibilité de voyager dans le temps et dans un monde parallèle, à partir des tombes, des tertres ou de certains lieux. Mais le problème du voyage dans le temps est assez lié à celle de l’oracle, qui existait déjà chez les Grecs et pouvait entraîner les mêmes paradoxes. Les physiciens et les philosophes, tout autant que les auteurs de science-fiction, s’intéressent au voyage dans le temps, aux effets théoriques des vo

Elaboration d'un système de navigation auto-alimenté (SNA) et évaluation de ses performances

Alexandre Torday

This research deals with self-supplied navigation systems (SNS), a combination of the technology of gathering travel time using floating car data (FCD) and dynamic route guidance (DRG). Using similar on-board equipment, these two systems can easily be combined in the same vehicle. The main goal is to prove the relationship between the percentage of SNS-equipped vehicles and the performance that can be expected from the use of this technology. After the description of the SNS architecture, an evaluation method based on microscopic traffic simulation results is proposed. The different components of a SNS are introduced, particularly the statistics and treatment module, which estimates and predicts travel times from the data transmitted by equipped vehicles. An innovative approach, resulting from the disaggregated observation of these travel times, is proposed in order to improve existing estimation techniques. The description of the parameters influencing this estimation's performance is followed by an analysis of their combined impact. It stresses the necessity of adopting a combination of these parameters, depending on the equipment rate of the vehicles, in order to maximise the estimation's precision. Before the comparison between the performances of equipped and non-equipped vehicles, based on the Lausanne city centre road network, the realism of existing traffic assignment models is analysed. As a consequence, a new alternative for traffic assignment is proposed, consisting of an iterative approach based on the use of historic knowledge of a "typical" day and on a differentiation of three driver categories: standard, expert and tourist. The SNS performance evaluation, mainly in terms of travel time, shows that an equipment rate of only 1 to 2 0/00 is sufficient in order for equipped vehicles to show similar performances to standard drivers, this category representing the majority of drivers. An equipment rate of 5 to 50 0/00 is needed in order to pass above the expert category, which has a perfect knowledge of the road network. For higher equipment rates the benefit compared with the other drivers is less noticeable, but the overall performance of all vehicles is highly improved. Finally, a behaviour study of SNS-equipped vehicles in the case of an incident on the network shows certain limits implied by the fact that the guided vehicles and the ones providing traffic data are the same ones.

EPFL2005

Increasing Traffic Flows with DSRC Technology: Field Trials and Performance Evaluation

Aurélien Pomini

As traffic congestion becomes a huge problem for most developing and developed countries across the world, intelligent transportation systems (ITS) are becoming a hot topic that is attracting attention of researchers and the general public alike. In this paper, we demonstrate a specific implementation of an ITS system whereby traffic lights are actuated by DSRC radios installed in vehicles. More specifically, we report the design of prototype of a DSRC-Actuated Traffic Lights (DSRC-ATL) system. It is shown that this system can reduce the travel time and commute time significantly, especially during rush hours. Furthermore, the results reported in this paper do NOT assume or require all vehicles to be equipped with DSCR radios. Even with low penetration ratios, e.g., when only 20% of all vehicles in a city are equipped with DSRC radios, the overall performance of the designed system is superior to the current traffic control systems.

IEEE2018

Elaboration d'un système de navigation auto-alimenté (SNA) et évaluation de ses performances

Alexandre Torday

EPFL2005

Assessment of solar panel efficiency under realistic conditions

Elaboration d'un système de navigation auto-alimenté (SNA) et évaluation de ses performances

Increasing Traffic Flows with DSRC Technology: Field Trials and Performance Evaluation

Increasing Traffic Flows with DSRC Technology: Field Trials and Performance Evaluation

Assessment of solar panel efficiency under realistic conditions

Elaboration d'un système de navigation auto-alimenté (SNA) et évaluation de ses performances