Fondements normatifs des inégalités environnementales pour l’analyse économique : définition et enjeux

The article proposes a presentation of the different possible normative foundations for an economic analysis of environmental inequalities. For this purpose, the article begins by putting the analysis of inequalities in a context of fairness economics. Four different forms of environmental inequality that can provide a basis for the normative consideration of environmental inequalities in economics are then presented. Finally, the different trade-offs between this normative goal of justice and those concerning other valuable aspects of a society are presented. All in all, the article provides a guide for the economic analysis of environmental inequalities from a normative perspective.L’article propose une présentation des différents fondements normatifs possibles pour une analyse économique des inégalités environnementales. Pour cela, l’article replace tout d’abord l’analyse des inégalités dans un contexte d’économie de la justice. Quatre formes différentes d’inégalités environnementales pouvant fonder la prise en compte normative des inégalités environnementales en économie sont ensuite présentées. Enfin, les différents arbitrages entre cet objectif normatif de justice et ceux concernant les autres aspects valorisables d’une société sont présentés. Au final, l’article fournit un guide pour l’analyse économique des inégalités environnementales dans une perspective normative

Analyse économique des inégalités environnementales : Fondements normatifs, mesures et application au contexte brésilien

This thesis studies the environmental inequalities in an objective of social justice. The first part offers an interdisciplinary definition of these inequalities in order to catch their multidimensional nature and to show their usefulness in environmental economics and ecological economics. Based on a philosophy of economics perspective, the fairness of environmental inequalities is analysed by using different egalitarian conceptions of justice with a consideration of the existence of other societal objectives. Following this theoretical development, the second part is devoted to an analysis of the issues of access to water and sanitation services in the context of Brazil. After a discussion over the situation related to the water and sanitation sector in Brazil, the socioeconomic and institutional determinants of the access to these services are identified using econometric analyses at the household level. These analyses enable to expose key determinants in the perspective of environmental justice including income level and ethnicity. In addition, they show the role of the state level thanks to the use of multilevel models. By using an indicator of the access to water and sanitation services elaborated through a factor analysis, the inequalities associated to these services are then measured by different methods which correspond to each conception of justice developed in the first part.Cette thèse étudie les inégalités environnementales dans un objectif de justice sociale. La première partie propose une définition interdisciplinaire de ces inégalités afin de capter son caractère multidimensionnel et de montrer son utilité en économie de l’environnement et en économie écologique. À partir de la littérature en philosophie économique, le caractère juste ou injuste des inégalités environnementales est ensuite analysé en mobilisant différentes conceptions égalitaristes de la justice et en considérant l’existence d’autres objectifs sociétaux. À la suite de ce travail théorique, la seconde partie s’articule autour d’une application aux enjeux de l’accès à l’eau et à l’assainissement au Brésil. Après avoir présenté la situation relative à ces services dans le contexte brésilien, les déterminants socioéconomiques et institutionnels de cet accès sont identifiés par des analyses économétriques sur des données à l’échelle des ménages. Ces analyses permettent de mettre en lumière des déterminants au cœur des problématiques de justice environnementale comme le revenu, l’ethnicité, mais aussi le rôle des États en ayant recours à des modèles multi-niveaux. En utilisant un indicateur d’accès à l’eau et à l’assainissement construit à partir d’une analyse factorielle, les inégalités associées à ces services sont ensuite mesurées par différentes méthodes correspondant à chacune des conceptions de la justice développées dans la première parti

Justice environnementale, justice alimentaire et OGM. Analyse à partir de l’agriculture indienne

Depuis une quinzaine d’années, le débat sur les Organismes génétiquement modifiés (OGM) a pris une ampleur considérable en s’appuyant sur des mouvements protestataires. L’originalité de ces protestations est d’associer la justice environnementale et la justice alimentaire. Cet article examine la façon dont ces deux notions s’articulent dans le contexte de l’agriculture indienne. Trois cas d’études, dont les problématiques ont émergé successivement, sont mobilisés pour montrer l’évolution des argumentaires développés par les mouvements protestataires. Ces exemples permettent de mettre en lumière la force des discours récents, qui amènent à revoir en profondeur le concept de justice environnementale pour intégrer celui de justice alimentaire. Par ailleurs, les auteurs montrent que le discours a connu un changement en passant d’arguments en faveur du maintien des traditions culturelles à des arguments soulignant les externalités négatives des OGM.For fifteen years, the debate on GMOs (Genetically Modified Organisms) has grown considerably in India. The originality of the movements of protestation is to combine environmental justice and food justice. This article examines how these two concepts are articulated in the context of Indian agriculture. Three case studies, which have emerged successively, are mobilised to show the evolution of the arguments developed. These examples highlight the strength of the recent speeches that lead to modify the concept of environmental justice to include the food justice. Furthermore, the authors show the speech known a change, starting with arguments related to the preservation of cultural traditions to arguments stressing the negative externalities of GMOs

Mother and newborn survival according to point of entry and type of human resources in a maternal referral system in Kayes (Mali)

The study assesses maternal and newborn survival in women presenting with an obstetric complication in Kayes (Mali). It compares the effects of the point of entry into the referral system on joint mother-newborn survival, and the effects of the configuration of healthcare teams at the community health centers (CHC). Results show that entry at the CHC while coming from a distance of less than 5 km increased the likelihood of joint survival by 8.50%. The size of the healthcare team at the CHC is significantly associated with mother-newborn survival only when distance traveled is 5 km or less

European Journal of Mechanics - A/Solids

A method coupling experiments and simulations, is developed to characterize the yield stress and strain hardening of several metals loaded at 106 s−1 and < 25 ns, typically involved during Laser Shock Peening. It was applied to four materials: pure aluminum, 2024-T3 and 7175-T7351 aluminum alloys and Ti6Al4V-ELI titanium alloy. Thin foils have been irradiated with high-power laser to induce high-pressure shock wave. Plastic deformation is activated through the thickness up to the rear free-surface of the foils. These experiments have been simulated using three material constitutive equations: Elastic–Perfectly Plastic model considering static yield stress, Johnson–Cook model without strain hardening and Johnson–Cook model with strain hardening. The material parameters of Johnson–Cook law were identified by comparison of the experimental and calculated velocity profiles of the rear-free surface. Results are shown and discussed

Propagation of laser-generated shock waves in metals: 3D axisymmetric simulations compared to experiments

This work aims at demonstrating the ability of an acoustic linear code to model the propagation of a shock wave created by a laser impact over a metallic surface. In this process, a high pressure surface level is reached using a ns laser pulse that heats the surface of the material and generates a dense plasma expansion. The pressure reaches few GPa so shock waves are generated and propagate into the bulk of the material. Currently, shock wave propagation is modeled using continuity equations and an ad hoc equation of state for the illuminated mate-rial, very limiting because it is numerically intensive. Here, we propose to model the shock wave bulk propagation using a linear acoustic code. A nonlinear surface pressure term, resulting from the laser–matter interaction, is used as a boundary condition. The applied numerical scheme is based on the Virieux scheme, including a fourth order finite difference discretization of the linearized elastomechanical equations. The role of longitudinal and transverse waves and their origins are highlighted. The importance of considering 3D geometries is pointed out. Simulations are finally confronted with experimental results obtained with the Hephaistos Laserlab facility (energy up to 14 J at 532 nm wavelength laser; pulse duration: 7 ns). Illuminations up to the optical breakdown in water are easily achieved with laser focal spots of 5 mm width. Excellent agreement between experiments and simulations is observed for several sets of experimental parameters for titanium, a material of high elastic limit, while limitations are founded for aluminum. The code is available in the MetaData

Novel Confinement Possibility for Laser Shock: Use of Flexible Polymer Confinement at 1064 nm Wavelength

Through the years, laser shock peening became a treatment of choice in the aerospace industry to prolong the life of certain critical pieces. Water flow is commonly used as a confinement to improve the process capability but some applications cannot allow for water presence in the area of interest. In a previous article, an alternative to the water confinement was presented, a flexible polymer confinement was used and demonstrated the production of pressures equivalent to the water configuration treatment. However, laser parameters have been restricted to a wavelength in the visible range at 532 nm. In this paper, the study is extended to 1064 nm which is commonly used in LSP applications and with two different pulse durations. A 1064 nm near infra-red laser is used to do pressure characterization of shots with polymer confinement through Velocity Interferometer System for Any Reflector (VISAR) measurements coupled with Finite Element Modelling on Abaqus software. The results show that the pressures produced by the confinement is slightly lower with the 1064 nm wavelength, similar to what is observed with the classic water confined regime when switching from 532 nm to a near infra-red wavelength. Nevertheless, the high level of pressure produced by laser shock under the polymer confinement configuration allows for the treatment of common types of metal alloys used in the aerospace industry. Although the use of such a confinement has yet to be applicable to peening setups, it has already uses in some single shot configurations such as LasAT where it allows the avoidance of the water flow optimization

Laser induced plasma characterization in direct and water confined regimes: new advances in experimental studies and numerical modelling

Optimization of the laser shock peening (LSP) and LASer Adhesion Test (LASAT) processes requires control of the laser-induced target's loading. Improvements to optical and laser technologies allow plasma characterization to be performed with greater precision than 20 years ago. Consequently, the processes involved during laser-matter interactions can be better understood. For the purposes of this paper, a self-consistent model of plasma pressure versus time is required. The current approach is called the inverse method, since it is adjusted until the simulated free surface velocity (FSV) corresponds to the experimental velocity. Thus, it is not possible to predict the behavior of the target under shock without having done the experiments. For the first time, experimental data collected in different labs with the most up-to-date laser parameters are used to validate a self-consistent model for temporal pressure-profile calculation. In addition, the parameters characterizing the plasma (temperature, thickness and duration) are obtained from the ESTHER numerical code, together with the amount of ablated matter. Finally, analytic fits are presented that can reproduce any pressure-temporal profiles in the following domains of validity: Intensities, I, ranging from 10 to 500 GW cm-2 and pulse durations, T pul, between 5 and 40 ns for the direct-illumination regime at 1053 nm, I ranging from 1 to 6 GW cm-2 and T pul between 10 to 40 ns in the water-confined regime at 1053 nm, and I from 1 to 10 GW cm-2 and T pul between 7 and 20 ns in the water-confined regime at 532 nm. These temporal pressure profiles can then be used to predict the aluminum target's behavior under laser shock using mechanical simulation software

Towards selective laser paint stripping using shock waves produced by laser-plasma interaction for aeronautical applications on AA 2024 based substrates

Laser stripping is a process which typically includes different forms of ablation phenomena. The presented work investigates a mechanical stripping process using high pressure laser-induced shock waves in a water confined regime. Power density is studied as a parameter for selective laser stripping on painted specimens and for adhesion relations with single layer epoxy targets. A flashlamp-pumped Nd:YAG laser with fixed spot size (4 mm) is shot on single layer epoxy and several layers of polymeric paint applied on a AA 2024-T3 (Aluminium) substrate. After laser treatment, samples are investigated with optical microscopy, profilometer and chemical analysis (FTIR & TGA). The results show that selective laser stripping is possible between different layers of external aircraft coatings and without any visual damage on the substrate material. In parallel to the experimental work, a numerical model has been developed to explain the background of the physical mechanisms and to qualitatively evaluate the detailed stress analysis and interfacial failure simulation for a single layer of epoxy on an aluminium substrate. The predicted failure patterns agree with the surfaces of the tested specimens observed by a microscope

Beam size dependency of a laser-induced plasma in confined regime: Shortening of the plasma release. Influence on pressure and thermal loading

Processes using laser-shock applications, such as Laser Shock Peening or Laser Stripping require a deep understanding of both mechanical and thermal loading applied. We hereby present new experimental measurements of the plasma pressure release regarding its initial dimension, which depends on the laser beam size. Our data were obtained through shock waves’ velocity analysis and radiometric assessments. A new model to describe the adiabatic release behavior of a laser-induced plasma with a dependency to the beam size is developed. The results and the associated model exhibit that the plasma release duration is shortened with smaller laser spots. As a consequence, with chosen smaller laser spots (0.6 mm to 1 mm), the thermal loading applied during the plasma lifetime will also decrease. These new results shall help for a better understanding of laser-matter interaction for laser-shock applications by giving more accurate plasma profiles. Thus, process simulations can be improved as well. Eventually, by considering recent developments with high-power Diode Pumped Solid-State lasers (DPSS), we now expect to develop a new configuration for LSP which could be applicable both without any thermal coating and deliverable by an optical fiber.This research was funded by Thales company, institutions (CEA,NRS, ENSAM), and by the ANR (Agence Nationale de la Recherche), Forge Laser Project (Grant No.: ANR-18-CE08-0026)