694 research outputs found
A System of Tradable CO2 Permits Applied to Fuel Consumption by Motorists
Decentralized transferable permit systems in the transport sector can be of interest with regard to reducing greenhouse gas emissions, in spite of anticipated transaction costs. This paper describes a potential application of a domestic market for car fuel consumption permits. The marginal costs of consumption reduction vary sufficiently according to motorists' residential locations to consider permit exchanges. Economic evaluation of this system shows that there are transfers of surplus between the various groups of motorists according to their residential locations. The central government may lose significant revenues when compared with a conventional fuel tax. Lastly, the issue of transaction costs, the benefits and disadvantages in terms of social acceptability and equity are discussed. (JEL classification: D120; D450; R410; R480).Tradable permits ; Transport ; Greenhouse gas ; economic evaluation ; car fuel consumption ; carbon card ; motorists
A system of tradable permits applied to fuel consumption by motorists
Decentralized transferable permit systems in the transport sector can be of interest with regard to reducing greenhouse gas emissions, in spite of anticipated transaction costs. This paper describes a concrete application of a domestic market for motor vehicle fuel consumption permits. The marginal costs of consumption reduction vary sufficiently according to motorists' residential locations to consider permit exchanges. Economic evaluation of this system reveals that there are transfers of surplus between the various groups of motorists according to their residential locations. The central government may lose significant revenues when compared with a conventional fuel tax. Lastly, the issue of transaction costs, the benefits and disadvantages in terms of social acceptability and equity are discussed.Transferable permits ; Transport ; Greenhouse gas ; Surplus
Transport et effet de serre : un système de permis négociables appliqué aux automobilistes
Les transports sont parmi les plus importants émetteurs de gaz à effet de serre en France et aussi le secteur dont les émissions devraient le plus croître à l'avenir. Il est donc probable qu'il fera l'objet de mesures restrictives dans le cadre des engagements internationaux actuels et à venir en matière de réduction des émissions de gaz à effet de serre. Cependant, de nouvelles hausse des taxes sur les carburants semblent difficilement acceptables, d'autant plus que les prix du pétrole sont très volatiles. L'introduction dans le secteur des transports de systèmes de quotas connus sous le nom de permis négociables permettrait d'atteindre un niveau donné de réduction des émissions. Cet article analyse les avantages et les inconvénients des permis négociables par rapport aux taxes. Un système opérationnel de permis de consommation du carburant, appliqué aux automobilistes, est décrit et évalué.permis négociables ; carte carbone ; crédits carbone ; transport ; gaz à effet de serre ; automobilistes ; évaluation économique
Shape optimization with a level set based mesh evolution method
International audienceIn this article, we discuss an approach for geometry and topology optimization of structures which benefits from an accurate description of shapes at each stage of the iterative process - by means of a mesh amenable for mechanical analyses - while retaining the whole versatility of the level set method when it comes to accounting for their evolution. The key ingredients of this method are two operators for switching from a meshed representation of a domain to an implicit one, and conversely; this notably brings into play an algorithm for generating the signed distance function to an arbitrary discrete domain, and a mesh generation algorithm for implicitly-defined geometries
A mesh evolution algorithm based on the level set method for geometry and topology optimization
An approach for structural optimization is proposed, which combines the versatility of the level set method for handling large deformations and topology changes with the accurate description of the geometry provided by an exact mesh of the shape. The key ingredients of this method are efficient algorithms for (i) moving a level set function on an unstructured mesh, (ii) remeshing the surface corresponding to the zero level set and (iii) simultaneously adaptating the volumic mesh which fits to this surfacic mesh
Multi-phase structural optimization via a level set method
33 pagesInternational audienceWe consider the optimal distribution of several elastic materials in a fixed working domain. In order to optimize both the geometry and topology of the mixture we rely on the level set method for the description of the interfaces between the different phases. We discuss various approaches, based on Hadamard method of boundary variations, for computing shape derivatives which are the key ingredients for a steepest descent algorithm. The shape gradient obtained for a sharp interface involves jump of discontinuous quantities at the interface which are difficult to numerically evaluate. Therefore we suggest an alternative smoothed interface approach which yields more convenient shape derivatives. We rely on the signed distance function and we enforce a fixed width of the transition layer around the interface (a crucial property in order to avoid increasing "grey" regions of fictitious materials). It turns out that the optimization of a diffuse interface has its own interest in material science, for example to optimize functionally graded materials. Several 2-d examples of compliance minimization are numerically tested which allow us to compare the shape derivatives obtained in the sharp or smoothed interface cases
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