Preventing Adverse Environmental And Social Outcomes In Sustainable Value Chains In Nickel Extraction And Refining: Possible Approaches From The Literature

This paper investigates and analyses sustainable value chains in the nickel production. Nickel is crucial for the global transition to renewable energy sources as battery-grade nickel contributes to the development and scalability of the electric vehicle (EV) industry. At the same time, the nickel industry faces several significant environmental and social challenges, such as inefficiency in resource use including overconsumption of energy and water, and minimal community engagement. These challenges must be urgently addressed to achieve sustainable solutions, particularly as the EV industry and other battery users grow to meet global demand. In this paper, we investigate how the mitigation of these adverse environmental and social impacts was discussed in the literature

Description and validation of a " non path-dependent " model for projecting contrasting urban growth futures

International audienceThis paper presents a model (SLEUTH*) for projecting contrasting urban growth futures.It is derived from the SLEUTH model, which has been modified in order to incorporate an additional spatially explicit factor, and to be used in a fully controlled forecasting mode. Our aim is to spatially allocate urban growth, its amount and pattern, according to predefined prospective scenarios and assuming a non path-dependency approach. This modelling approach aims at being used under a "story and simulation" (SAS) approach, which constrains the model validation. To assess model efficiency, three types of tests have been undertaken: (1) sensitivity tests; (2) reproduction of known changes over a past period; and (3) simulation of changes that break trends. Results show that SLEUTH* conveniently simulates expected urban changes for exploring contrasting scenarios that are the basis for land planning strategies

How to anticipate the level of activity of a sustainable collaborative network: the case of urban freight delivery through logistics platforms

International audienceIn this paper, we elaborate a methodology to study a particular case of collaborative network: city logistics. We identify that many solutions for urban logistics are, most of time, badly evaluated. Indeed, the theory often predicts a positive effect but the reality is most of time counterbalanced. We tried to fill this gap by making use of innovative methods. To do so, we mobilize several domains of knowledge: operational research, game theory and transportation studies on real cases. We suggest a solution to anticipate the level of activity of an Urban Consolidation Center and determine the condition under which it generates benefit for a carrier using or not, the collaborative network. We present the result obtained by application of our method on the real case of the city of Saint-Etienne

Microscale heterogeneity explains experimental variability and non-linearity in soil organic matter mineralisation

Soil respiration represents the second largest CO2 flux from terrestrial ecosystems to the atmosphere, and a small rise could significantly contribute to further increase in atmospheric CO2. Unfortunately, the extent of this effect cannot be quantified reliably, and the outcomes of experiments designed to study soil respiration remain notoriously unpredictable. In this context, the mathematical simulations described in this article suggest that assumptions of linearity and presumed irrelevance of micro-scale heterogeneity, commonly made in quantitative models of microbial growth in subsurface environments and used in carbon stock models, do not appear warranted. Results indicate that microbial growth is non-linear and, at given average nutrient concentrations, strongly dependent on the microscale distribution of both nutrients and microbes. These observations have far-reaching consequences, in terms of both experiments and theory. They indicate that traditional, macroscopic soil measurements are inadequate to predict microbial responses, in particular to rising temperature conditions, and that an explicit account is required of microscale heterogeneity. Furthermore, models should evolve beyond traditional, but overly simplistic, assumptions of linearity of microbial responses to bulk nutrient concentrations. The development of a new generation of models along these lines, and in particular incorporating upscaled information about microscale processes, will undoubtedly be challenging, but appears to be key to understanding the extent to which soil carbon mineralization could further accelerate climate change

3D tomography of the giant Lyα nebulae of z ≈ 3–5 radio-loud AGN

Lyα emission nebulae are ubiquitous around high-redshift galaxies and are tracers of the gaseous environment on scales out to ≳100 pkpc (proper kiloparsec). High-redshift radio galaxies (HzRGs, type-2 radio-loud quasars) host large-scale nebulae observed in the ionised gas differ from those seen in other types of high-redshift quasars. In this work, we exploit MUSE observations of Lyα nebulae around eight HzRGs (2.92 < z < 4.51). All of the HzRGs have large-scale Lyα emission nebulae with seven of them extended over 100 pkpc at the observed surface brightness limit (∼2 − 20 × 10−19 erg s−1 cm−2 arcsec−2). Because the emission line profiles are significantly affected by neutral hydrogen absorbers across the entire nebulae extent, we performed an absorption correction to infer maps of the intrinsic Lyα surface brightness, central velocity, and velocity width, all at the last scattering surface of the observed Lyα photons. We find the following: (i) that the intrinsic surface brightness radial profiles of our sample can be described by an inner exponential profile and a power law in the low luminosity extended part; (ii) our HzRGs have a higher surface brightness and more asymmetric nebulae than both radio-loud and radio-quiet type-1 quasars; (iii) intrinsic nebula kinematics of four HzRGs show evidence of jet-driven outflows but we find no general trends for the whole sample; (iv) a relation between the maximum spatial extent of the Lyα nebula and the projected distance between the active galactic nuclei (AGN) and the centroids of the Lyα nebula; and (v) an alignment between radio jet position angles and the Lyα nebula morphology. All of these findings support a scenario in which the orientation of the AGN has an impact on the observed nebular morphologies and resonant scattering may affect the shape of the surface brightness profiles, nebular kinematics, and relations between the observed Lyα morphologies. Furthermore, we find evidence showing that the outskirts of the ionised gas nebulae may be ‘contaminated’ by Lyα photons from nearby emission halos and that the radio jet affects the morphology and kinematics of the nebulae. Overall, this work provides results that allow us to compare Lyα nebulae around various classes of quasars at and beyond cosmic noon (z ∼ 3)

Experimentation versus simulation du transport réactif en milieu poreux, capture de profils de concentration et évolution texturale des solides.

237 pagesA new type of plug flow reactor is developed to provide an experimental validation of reactive transport simulations. It reproduces a long (6 m) 1D porous medium composed of unreactive quartz and reactive solids exposed to the percolation of an aqueous phase, where sampling ports allow the concentration profiles in the fluid phase to be captured. The reaction of CO2 saturated solutions (5-8 bar) at 40-50 °C with carbonate (calcite, dolomite) gives rise to reproducible dissolution fronts migrating downflow. Some discrepancies between reactive transport simulations and experiments concern the sharpness of the reaction front and the outlet concentrations. A proper projection of experimental data for dolomite evidences the stationary shape of the moving dissolution front. This shape allows the variations in reactive surface area to be documented as a function of solid consumption, and the increasing reactive surface under far from equilibrium conditions is related to the observed skeletal textures. Diopside dissolution in HNO3 solutions (pH = 2) at 60 °C, allow verifying the predicted linearity of concentration profiles under stationary, far from equilibrium conditions. In the non-stoichiometric, transient stages of dissolution, mass balance calculations point to the formation of a Si-dominated surface layer. Direct SEM observations of reacted grains suggest this layer to be anisotropically distributed on the diopside surface.Nous présentons un nouveau réacteur de type plug-flow dédié à valider expérimentalement les simulations de transport réactif. Il reproduit un milieu poreux 1D de grande longueur (6 m) dans lequel un excipient (quartz) et un solide réactif sont percolés par un fluide aqueux dont l'échantillonnage en différents points permet la capture de profils de concentration. La percolation de solutions saturées en CO2 (5-8 bar) à 40-50 °C sur des carbonates (calcite, dolomite) génère un front de dissolution mobile et reproductible. Les écarts entre simulation et expérience concernent la raideur des fronts et la concentration de sortie. Une projection des données expérimentales pour la dolomite montre la stationnarité de la forme du front dans un repère mobile. Cette forme permet d'accéder à l'évolution de la surface réactive en fonction de la proportion de solide dissous, et l'accroissement marqué de celle-ci loin de l'équilibre est relié aux textures ruiniformes observées au MEB. La dissolution du diopside par HNO3 (pH = 2) à 60 °C permet de vérifier la linéarité des profils de concentration prédits par le modèle à l'état stationnaire, loin de l'équilibre. Lors des phases transitoires de dissolution non stœchiométrique, le bilan élémentaire montre l'apparition d'une couche de surface riche en Si. Les observations MEB suggèrent une répartition anisotrope de cette couche à la surface des grains

La mutualisation des livraisons urbaines : quels impacts sur les coûts et la congestion ?

International audienceThis paper presents a framework for the analysis of logistics pooling among transport carriers based on residual capacity management, in the context of urban delivery logistics. First, an overview is presented of the different forms of logistics collaboration, cooperation, pooling and sharing to set up the context of this study : logistics sharing among urban delivery carriers. After that, a framework is proposed for analysing the impacts of logistics pooling and the main assumptions, and the analytical method for estimating the impacts of logistics pooling. Then, the assessment of five scenarios of logistics pooling is presented to illustrate the proposed framework. Finally, the results are presented and the suitability and development issues of urban logistics pooling are discussed.Cet article propose un cadre d’analyse de la mutualisation entre transporteurs basée sur la gestion des capacités résiduelles, dans un contexte de livraisons urbaines. Dans un premier temps, l’article dresse un panorama de la recherche sur la mutualisation logistique pour ensuite recadrer le contexte de cette étude : la mutualisation horizontale des livraisons urbaines. Ensuite un cadre d’analyse des impacts de la mutualisation est proposé, comprenant les choix et hypothèses, ainsi que la méthode analytique d’estimation des impacts de la mutualisation utilisée. Puis, à titre d’exemple, cinq scénarios de mutualisation sont présentés sur lesquels la méthode est appliquée. Enfin, les résultats de cette simulation sont présentés et ses principaux résultats sont discutés

A methodology to anticipate the activity level of a collaborative network : an urban consolidation center

International audienceThis article presents a methodology relative to the assessment of a particular measure in city logistics: Urban Consolidation Centers (UCCs). We identify that this kind of collaborative network is, often, poorly evaluated and thus operates in a way that is neither sustainable nor efficient. By mobilizing several fields of knowledge, such as operational research, game theory, and transportation studies on real cases, we propose a solution to anticipate the activity level of a UCC and determine the condition under which it generates benefits for carriers. The aim is to provide a suitable aid to public decision makers in territorial management. The study concludes by an application of the method on the test case of the city of Saint-Etienne, France

A methodology to anticipate the activity level of a collaborative network : an urban consolidation center

International audienceThis article presents a methodology relative to the assessment of a particular measure in city logistics: Urban Consolidation Centers (UCCs). We identify that this kind of collaborative network is, often, poorly evaluated and thus operates in a way that is neither sustainable nor efficient. By mobilizing several fields of knowledge, such as operational research, game theory, and transportation studies on real cases, we propose a solution to anticipate the activity level of a UCC and determine the condition under which it generates benefits for carriers. The aim is to provide a suitable aid to public decision makers in territorial management. The study concludes by an application of the method on the test case of the city of Saint-Etienne, France