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Fractalopolis : un outil d’aide à la décision pour une approche multi-échelle des projets de territoire
No full textInternational audienceCette communication porte sur la présentation d’une nouvelle méthodologie d’analyse multi-échelle des aires métropolitaines. Reposant sur l’utilisation du logiciel Fractalopolis (https://sourcesup.renater.fr/www/fractalopolis/), cette approche vise à mieux comprendre l'organisation polycentrique de l’armature urbaine des territoires à travers l’identification et la spatialisation des différentes centralités qui la compose. Il en résulte la construction d’un système emboîté de différents zonages décomposant l’organisation fonctionnelle des zones d’étude, en tenant compte des scénarios d’aménagement développés dans les documents locaux d’urbanisme et de différents indicateurs spatiaux. À partir des zonages ainsi obtenus, il est notamment possible d’évaluer l’accessibilité aux commerces, services et espaces verts ou d’observer la répartition de la population selon les différents niveaux de centres urbains. L’intérêt de cette approche est d’assurer une meilleure compréhension des projets d’aménagement et des enjeux du développement urbain durable à toutes les échelles du territoire, passant d’une analyse globale des principaux « bassins de vie » à une lecture fine des centralités locales. Cette méthodologie sera présentée avec une application sur le territoire de Grand Besançon Métropole, dont le PLUi est actuellement en phase d’élaboration et dont le SCoT est en cours de révision. Nous évoquerons ainsi les principales orientations stratégiques d’un projet de territoire résilient à l’horizon 2040, « garant des équilibres et des proximités »
Tariffs time-dynamics in competitive electricity retail markets with differentiated consumer reactions
No full textInternational audienceTime-varying retail tariffs play a key role in activating demand-side flexibility in power systems.In retail markets, such tariffs compete with constant-in-time, or flat, tariffs. We investigate how the coexistence of these two tariff types influences their respective pricing levels and adoption rates among a diverse consumer base. To this end, we propose a multi-leader-followers model featuring a continuum of consumers characterized by their penalization of responding to price changes at the lower level and two competing retailers at the upper level. One retailer offers a time-varying tariff and the other a flat one. We derive the equilibria of the retail market under various assumptions about each retailer's responsiveness to the other's decisions, and compare the outcomes with those under a regulated monopolist retailer. We then provide a numerical application of the results based on the French electricity retail market.At equilibrium, the time-varying tariff's dynamics is dampened relative to the first-best real time price due to competitive pressure from the flat tariff and the distribution of consumers. When the time-varying tariff is known ex-ante, competition leads to lower or more uncertain adoption of the time-varying tariff compared to a monopolistic retailer offering both tariffs. When it is not, the monopolistic retailer option seems less attractive in terms of mobilized demand-side flexibility than retail competition, notably if consumers overestimate electricity prices on average. In that case, less flexible consumers bear the cost of imperfectly forecasting the tariff levels
Demand response control structure in imperfectly competitive power markets: independent or integrated?
No full textThis article interrogates the effects of different types of actors controlling load-shifting operations and the subsequent market impacts under Cournot competition. Analytical results linking load-shifting capacity and market equilibrium are obtained for independently triggered load-shifting by a regulated, price-taker, or price-maker actor and for an integrated generator. An application to a 2035 French power system with a bottom-up description of demand response constraints is also proposed.This paper has two main results. Firstly, at the initial deployment stages, prices are smoothed and lowered with load-shifting (LS), whatever the control structure of LS is. Secondly, at larger installed LS capacity, we find an ordering of the structures regarding market power exercise. Sorting by increasing market power, regulated pure LS players, private pure players are close ; then LS integrated to peak generation, then uniformly spread across all generators. Integrated LS-base generation induces the most market power through LS capacity withholding
Explorer les changements perçus dans la fréquence des déplacements privés et des déplacements locaux après l’adoption du télétravail en France
No full textInternational audienceThis article analyses how teleworking arrangements and the characteristics of the teleworkers influence the perceived changes in the frequency of private trips and local trips (i.e. trips with a destination located close to the homeplace) after telework adoption. The data comes from an online survey in mainland France in spring 2022. The private trips considered here include firstly regular activities (errands, accompanying children, etc.), secondly weekend departures, and thirdly local trips. The results show that most teleworkers perceive no change before and after teleworking adoption. However, teleworking is more often associated with a reduction in errands trips than their increase. The extent of the decrease vary depending on the place of residence. On the other hand, the perceived frequency of other personal and family activities is mainly on the rise. Our results also show the influence of teleworking frequency and commuting duration on these trends. Finally, we find a positive relationship between teleworking and the frequency of local trips. In particular, the presence of amenities around the place of residence encourages an increase in local travel. These results show the diversity and complexity of the rebound effects of teleworking on private trips, and the need to support its current development with appropriate transport and land-use policies.Cet article analyse comment les modalités de télétravail et les caractéristiques des télétravailleurs influencent les changements perçus dans la fréquence des déplacements privés et des déplacements locaux (c’est-à-dire les déplacements dont la destination est située à proximité du domicile) après l’adoption du télétravail. Les données proviennent d’une enquête en ligne réalisée en France métropolitaine au printemps 2022. Les déplacements privés considérés ici incluent : premièrement, les activités régulières (courses, accompagnement des enfants, etc.) ; deuxièmement, les départs en week-end ; et troisièmement, les déplacements locaux.Les résultats montrent que la majorité des télétravailleurs ne perçoivent pas de changement entre l’avant et l’après télétravail. Toutefois, le télétravail est plus souvent associé à une diminution des déplacements pour les courses qu’à une augmentation. L’ampleur de cette diminution varie selon le lieu de résidence. En revanche, la fréquence perçue d’autres activités personnelles et familiales tend principalement à augmenter.Nos résultats mettent également en évidence l’influence de la fréquence de télétravail et de la durée des trajets domicile-travail sur ces tendances. Enfin, nous observons une relation positive entre télétravail et fréquence des déplacements locaux. En particulier, la présence de commodités autour du domicile favorise une augmentation des déplacements de proximité.Ces résultats illustrent la diversité et la complexité des effets rebond du télétravail sur les déplacements privés, et soulignent la nécessité d’accompagner son développement par des politiques de transport et d’aménagement adaptées
Uniform generation of large traces
No full textWe introduce an algorithm for the uniform generation of infinite traces, i.e., infinite words up to commutation of some letters. The algorithm outputs on-the-fly approximations of a theoretical infinite trace, the latter being distributed according to the exact uniform probability measure. The average size of the approximation grows linearly with the time of execution of the algorithm, hence its output can be effectively used while running.Two versions of the algorithm are given. A version without rejection has a good production speed, provided that some precomputations have been done, but these may be costly. A version with rejection requires much fewer computations, at the expense of a production speed that can be small.We also show that, for some particular trace monoids, one or the other version of the algorithm can actually be very good: few computations for a good production speed
Selective carbon credits: Market preferences and ecosystem restoration in Senegal
No full textInternational audienceThe voluntary carbon market is presented as a solution to fund land and ecosystem restoration in developing economies. While the empirical literature has focused on assessing its ecological effectiveness, limited attention has been given to how this market interacts with other funding streams within national contexts. Delineating the types of projects that the voluntary carbon market can effectively fund is essential for designing a coherent and integrated funding strategy at the national level. This paper investigates the contribution of the voluntary carbon market to ecological restoration projects in Senegal. Grounded in transaction costs and organizational economics and drawing on a novel dataset of restoration projects from 2007 to 2023, we identify a pattern in which the voluntary carbon market focuses on significantly less context-specific and more certain restoration protocols. The uncertainty of ecological outcomes and the specificity of natural capital explain the recourse to the market, and the market shapes specificity by attempting to standardize assets and facilitate transactions. This impacts restoration protocols, ecosystem targeted and local benefits. Our analysis offers a detailed understanding of how market preferences influence funding allocation and project implementation. Our findings underscore the need to integrate market-based funding with other mechanisms to address land degradation
Homogeneous multigrid for hybrid discretizations: application to HHO methods
No full textInternational audienceWe prove the uniform convergence of the geometric multigrid V- cycle for hybrid high-order (HHO) and other discontinuous skeletal methods. Our results generalize previously established results for HDG methods, and our multigrid method uses standard smoothers and local solvers that are bounded, convergent, and consistent. We use a weak version of elliptic regularity in our proofs. Numerical experiments confirm our theoretical results
Uniform-in-time propagation of chaos for Consensus-Based Optimization
No full textWe study the derivative-free global optimization algorithm Consensus-Based Optimization (CBO), establishing uniform-in-time propagation of chaos as well as an almost uniform-in-time stability result for the microscopic particle system. The proof of these results is based on a novel stability estimate for the weighted mean and on a quantitative concentration inequality for the microscopic particle system around the empirical mean. Our propagation of chaos result recovers the classical Monte Carlo rate, with a prefactor that depends explicitly on the parameters of the problem. Notably, in the case of CBO with anisotropic noise, this prefactor is independent of the problem dimension
Dynamical reweighting for estimation of fluctuation formulas
No full textWe propose a variance reduction method for calculating transport coefficients in molecular dynamics using an importance sampling method via Girsanov's theorem applied to Green--Kubo's formula. We optimize the magnitude of the perturbation applied to the reference dynamics by means of a scalar parameter~ and propose an asymptotic analysis to fully characterize the long-time behavior in order to evaluate the possible variance reduction. Theoretical results corroborated by numerical results show that this method allows for some reduction in variance, although rather modest in most situations
Fast Large Deformation Matching with the Energy Distance Kernel
No full textInternational audienceWe propose an efficient framework for point cloud and measure registration using bi-Lipschitz homeomorphisms, achieving O(n log n) complexity, where n is the number of points. By leveraging the Energy-Distance (ED) kernel, which can be approximated by its sliced one-dimensional projections, each computable in O(n log n), our method avoids hyperparameter tuning and enables efficient large-scale optimization. The main issue to be solved is the lack of regularity of the ED kernel. To this goal, we introduce two models that regularize the deformations and retain a low computational footprint. The first model relies on TV regularization, while the second model avoids the non-smooth TV regularization at the cost of restricting its use to the space of measures, or cloud of points. Last, we demonstrate the numerical robustness and scalability of our models on synthetic and real data