Performance of Averaging Algorithms in Time-Varying Networks

We study averaging algorithms in time-varying networks, and means tomeasure their performance. We present sufficient conditions on these algorithms, which ensure they lead to computation at each node, of the global average of measurements provided by each node in the network. Further, we present and use results from ergodic theory to define an accurate performance metric for averaging algorithms. This metric, the contraction coefficient, differs from previously used metrics such as the second largest eigenvalue of the expected weighting matrix, which gives an approximation of the real convergence rate only in some special cases which are hard to specify. On the other hand, the contraction coefficient as set forth herein characterizes exactly the actual asymptotic convergence rate of the system. Additionally, it may be bounded by a very concise formula, and simulations show that this bound is, at least in all studied cases, reasonably tight so as to be used as an approximation to the actual contraction coefficient. Finally, we provide a few results and observations which make use of the derived tools. These observations may be used to find new optima for design parameters of some averaging algorithms, and also open the door to new problems in the study of the underlying mathematical models

La notion de « cause » dans les sciences sociales : expliquer et comprendre

Ma thèse porte sur les difficultés des universités à s’engager dans la formation continue. J’ai, durant ma vie active, rencontré à maintes reprises le problème de la ségrégation sociale dans et par l’éducation, et j’ai engagé cette recherche pour voir de quelle façon, par la formation continue, l’enseignement supérieur pouvait compenser cette ségrégation. Les dispositions législatives et réglementaires qui l’ont instituée ont toujours mentionné un objectif de promotion sociale. J’ai examiné l..

Routes visualization: Automated placement of multiple route symbols along a physical network infrastructure

This paper tackles the representation of routes carried by a physical network infrastructure on a map. In particular, the paper examines the case where each route is represented by a separate colored linear symbol offset from the physical network segments and from other routes---as on public transit maps with bus routes offset from roads. In this study, the objective is to automate the placement of such route symbols while maximizing their legibility, especially at junctions. The problem is modeled as a constraint optimization problem. Legibility criteria are identified and formalized as constraints to optimize, while focusing on the case of hiking routes in a physical network composed of roads and pedestrian paths. Two solving methods are tested, based on backtracking and simulated annealing meta-heuristics respectively. Encouraging results obtained on real data are presented and discussed

La fermeture de l’aéroport Atatürk. Retour sur plus de 65 ans de trafic aérien dans le plus grand aéroport turc

[cite] Source : Archives nationales, Hava tehlikesi hakkında İstanbul ve Ankara gazetelerinde çıkan yazıların küpürleri. Le 29 octobre 2018, 95e anniversaire de la République turque, a eu lieu l’inauguration du plus grand aéroport du mondeau nord de la ville : İstanbul Havalimanı (Aéroport d’Istanbul - voir la note de J.-F. Pérouse du 1er novembre 2018). Cet événement signe également la fermeture annoncée au grand public de l’aéroport Atatürk, aéroport le plus fréquenté de Turquie pendant..

Routes visualization: Automated placement of multiple route symbols along a physical network infrastructure

This paper tackles the representation of routes carried by a physical network infrastructure on a map. In particular, the paper examines the case where each route is represented by a separate colored linear symbol offset from the physical network segments and from other routes—as on public transit maps with bus routes offset from roads. In this study, the objective is to automate the placement of such route symbols while maximizing their legibility, especially at junctions. The problem is modeled as a constraint optimization problem. Legibility criteria are identified and formalized as constraints to optimize, while focusing on the case of hiking routes in a physical network composed of roads and pedestrian paths. Two solving methods are tested, based on backtracking and simulated annealing meta-heuristics respectively. Encouraging results obtained on real data are presented and discussed

Inégalités sociales de santé (revue de la littérature à propos de la prévalence du tabagisme chez la femme enceinte)

PARIS6-Bibl. St Antoine CHU (751122104) / SudocSudocFranceF

Which distributed averaging algorithm should I choose for my sensor network

Average consensus and gossip algorithms have recently received significant attention, mainly because they constitute simple and robust algorithms for distributed information processing over networks. Inspired by heat diffusion, they compute the average of sensor networks measurements by iterating local averages until a desired level of convergence. Confronted with the diversity of these algorithms, the engineer may be puzzled in his choice for one of them. As an answer to his/her need, we develop precise mathematical metrics, easy to use in practice, to characterize the convergence speed and the cost (time, message passing, energy...) of each of the algorithms. In contrast to other works focusing on time-invariant scenarios, we evaluate these metrics for ergodic time-varying networks. Our study is based on Oseledec’s theorem, which gives an almost-sure description of the convergence speed of the algorithms of interest. We further provide upper bounds on the convergence speed. Finally, we use these tools to make some experimental observations illustrating the behavior of the convergence speed with respect to network topology and reliability in both average consensus and gossip algorithms. A. Problem statement. I