Fluid and Diffusion Limits for Bike Sharing Systems

Bike sharing systems have rapidly developed around the world, and they are served as a promising strategy to improve urban traffic congestion and to decrease polluting gas emissions. So far performance analysis of bike sharing systems always exists many difficulties and challenges under some more general factors. In this paper, a more general large-scale bike sharing system is discussed by means of heavy traffic approximation of multiclass closed queueing networks with non-exponential factors. Based on this, the fluid scaled equations and the diffusion scaled equations are established by means of the numbers of bikes both at the stations and on the roads, respectively. Furthermore, the scaling processes for the numbers of bikes both at the stations and on the roads are proved to converge in distribution to a semimartingale reflecting Brownian motion (SRBM) in a $N^{2}$-dimensional box, and also the fluid and diffusion limit theorems are obtained. Furthermore, performance analysis of the bike sharing system is provided. Thus the results and methodology of this paper provide new highlight in the study of more general large-scale bike sharing systems.Comment: 34 pages, 1 figure

From local to World Heritage: a comparative analysis

This paper aims to assess the implementation of the 1972 Convention in 10 countries (Australia, China, France, Germany, Italy, Japan, Spain, Switzerland, the United Kingdom and the United States) which were part of a research network funded by the UK’s Arts and Humanities Research Council in 2012–15 by examining the selection process of cultural properties at the national level through a survey. The survey consisted of a questionnaire that aimed to identify national practices regarding the identification and nomination of sites for submission on the state’s Tentative List and then onto the World Heritage List. It highlighted that despite the efforts of the World Heritage Committee to unify the submission process through long and detailed Operational Guidelines, there are important differences at a national level that lead to the List’s lack of representativity and an heterogeneous implementation of the Convention

A global experiment on motivating social distancing during the COVID-19 pandemic

Finding communication strategies that effectively motivate social distancing continues to be a global public health priority during the COVID-19 pandemic. This cross-country, preregistered experiment (n = 25,718 from 89 countries) tested hypotheses concerning generalizable positive and negative outcomes of social distancing messages that promoted personal agency and reflective choices (i.e., an autonomy-supportive message) or were restrictive and shaming (i.e., a controlling message) compared with no message at all. Results partially supported experimental hypotheses in that the controlling message increased controlled motivation (a poorly internalized form of motivation relying on shame, guilt, and fear of social consequences) relative to no message. On the other hand, the autonomy-supportive message lowered feelings of defiance compared with the controlling message, but the controlling message did not differ from receiving no message at all. Unexpectedly, messages did not influence autonomous motivation (a highly internalized form of motivation relying on one’s core values) or behavioral intentions. Results supported hypothesized associations between people’s existing autonomous and controlled motivations and self-reported behavioral intentions to engage in social distancing. Controlled motivation was associated with more defiance and less long-term behavioral intention to engage in social distancing, whereas autonomous motivation was associated with less defiance and more short- and long-term intentions to social distance. Overall, this work highlights the potential harm of using shaming and pressuring language in public health communication, with implications for the current and future global health challenges

Modelling and Performance Analysis of Electric Car-Sharing Systems Using Petri Nets

Car sharing systems emerged as a new answer to mobility challenges in smart and sustainable cities. Despite their apparent success, design and exploitation of such systems raise crucial strategic and operational challenges. To help planners and decision makers, simulation, analysis and optimization models are unavoidable. Based on the formal modelling and analysis power of stochastic Petri nets, this paper proposes a discrete event simulation model for electric car sharing systems for performance and analysis purposes, taking into account their complex dynamic behaviour, organization and parameters including capacities of the stations, battery and energy availability, locations of charging stations and also their car maintenance activities, not negligible compared to the case of bike-sharing systems

L'épidémie de Méningite au Mali et la circulation atmosphérique à grande échelle en Afrique de l'Ouest

International audienc

L'épidémie de Méningite au Mali et la circulation atmosphérique à grande échelle en Afrique de l'Ouest

International audienc

Petri Net-Based Approach for “Cyber” Risks Modelling and Analysis for Industrial Systems

Today, industrial systems are large, complex, and increasingly vulnerable. Specifically, due to the current digital transformation, the industry 4.0 creates crucial cyber-risks and cyber-security challenges. In this context, risk modelling and impact analysis has become a crucial research topic. Based on the formal modelling and performance analysis power of Petri Nets (PN), this paper represents a summary of our methodological approach for “risk” modelling and “impact” analysis of cyber vulnerabilities and / or other critical events. The applicability of the developed approach is demonstrated on a real-life industrial system