Portail HAL de l'Université du Littoral Côte d'Opale
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« J’ai un peu honte, mais je prends la voiture. » Les mobilités associées au trail-running face aux enjeux environnementaux contemporains
No full textInternational audienceEn France, les transports participent à 31 % des émissions de gaz à effet de serre, dont plus de la moitié avec les voiture particulières (Babet, 2022). Si ces mobilités relèvent majoritairement des trajets domicile-travail, les déplacements pour les loisirs, dont aller au sport (2,4 % des déplacements totaux ; MTECT, 2024), doivent aussi être étudiés. Ainsi, les trajets vers les sites de pratique, que ce soit les équipements dédiés comme les espaces appropriés en ville et surtout en nature, sont au cœur de notre travail. Nous nous intéressons plus particulièrement aux mobilités associées au trail-running. Le postulat initial de notre réflexion est que le trail-running irait de pair avec une sensibilité environnementale accrue se manifestant notamment dans les mobilités. Nous nous appuyons sur trois arguments : les traileurs seraient attachés à préserver l’environnement naturel qui constitue leur espace de pratique pour assurer la pérennité de leur activité, à l’image du lien entre l’engagement émotionnel dans la pratique et la conscience environnementale (Matsui, 2015) ; les catégories sociales favorisées sont sur-représentées dans la population des traileurs en France (Routier, 2023), or elles présentent une sensibilités écologique supérieure à la moyenne française (Comby, 2024) ; et s’adonner à cette activité physique pourrait faciliter le report modal vers les mobilités actives, à l’image du phénomène du run-commuting (Cook, 2021).Pour saisir ces mobilités, nous avons diffusé un questionnaire en ligne (n=627) et nous avons réalisé des entretiens sous forme de récits spatiaux (n=25). Premièrement, nous exposerons nos résultats au regard des déplacements des Français. Dans les mobilités locales, la répartition des modes de transport est assez semblable, avec une prévalence pour le vélo au détriment de la marche et des transports en commun chez les traileurs. Par ailleurs, l’autosolisme est bien plus répandu que le covoiturage dans le trail-running comparativement aux mobilités pour le sport et les promenades des Français. Deuxièmement, nous préciserons ces éléments selon les distances des trajets, les milieux d’évolution et en distinguant quatre situations de pratique. Nous montrerons notamment que si le covoiturage rattrape l’autosolisme pour les séjours dédiés au trail et pour les courses avec dossard, la voiture devient alors presque l’unique mode de transport. Troisièmement, nous relativiserons nos résultats au regard des trajets domicile-travail de nos répondants. Ils utilisent presque deux fois moins la voiture, un peu plus les transports en commun et la marche et nettement plus le vélo que les Français (Charrier et Perez, 2024)
Sustainable aroma absorption : exploring the potentiality of a β-cyclodextrin and lactic acid supramolecular eutectic solvent
No full textInternational audienceSupramolecular deep eutectic solvents (SUPRADESs), formed by combining cyclodextrins (CDs) with hydrogen bond donors, enhance solvation efficiency while retaining CD inclusion capabilities. This study presents the first detailed structural analysis of a SUPRADES composed of β-cyclodextrin (β-CD) and lactic acid (LA) (1:30 molar ratio) using Molecular Dynamics simulations and X-ray scattering. Results reveal a well-dispersed system where LA molecules form stabilising sheaths around isolated β-CDs, preventing coalescence through optimized hydrogen bonding and dispersive interactions. The SUPRADES significantly improved solubilisation and retention of water-insoluble trans-anethole (AN), demonstrating strong absorption capacity. While β-CD encapsulation of AN was limited, 2D ROESY NMR confirmed inclusion complex formation. These findings highlight the SUPRADES's unique microstructure and its potential as a sustainable, eco-friendly solvent for volatile organic compound (VOC) applications, offering insights for future green solvent design
CO<sub>2</sub> purification of industrial flue gas: effect of physico-chemical properties obtained by different preparation methods on CoCuAl oxide for the Selective Catalytic Reduction process
No full textInternational audienc
A lightweight spatial and spectral CNN model for classifying floating marine plastic debris using hyperspectral images
No full textInternational audienceMarine plastic debris poses a significant environmental threat. In order to study and combat this pollution, efficient and automated detection methods are essential. Hyperspectral imaging and deep learning provide a robust framework for classifying floating marine plastic debris. However, deep learning approaches often suffer from high computational complexity and limited interpretability. In addition, hyperspectral images are high-dimensional data that must be analyzed efficiently. To overcome these limitations, this paper proposes the Lightweight Spatial and Spectral Hyperspectral CNN (LSS-HCNN), a deep learning model designed to enhance classification accuracy while improving computational efficiency and interpretability. The proposed model first applies spatialwise convolutions to extract spatial features from individual spectral bands, then uses spectralwise convolutions to extract relationships between spectral bands. Additionally, a Squeeze-and-Excitation (SE) block improves interpretability by focusing on the most informative spectral bands. Experiments were conducted on three hyperspectral datasets containing various materials and four dedicated floating plastic datasets, including a new plastic waste dataset. It provides images in three spectral configurations: visible-near-infrared (VIS-NIR), near-infrared-shortwave-infrared (NIR-SWIR), and a fused domain. Results show that LSS-HCNN outperforms traditional handcrafted descriptors and deep-learning models, particularly for floating marine plastics. It achieves a mean classification accuracy of 97.64% while reducing model complexity. Compared to standard 2D-CNN, it reduces the number of parameters by over 80% and Floating Point Operations (FLOPS) by a factor of 7. Moreover, SE block analysis reveals that NIR-SWIR bands contribute the most to plastic classification. This highlights LSS-HCNN as an efficient marine plastic debris classification model, supporting environmental monitoring efforts
Chèque : pas de devoir de vigilance avant la remise à l'encaissement: note ss. Cass. com., 5 mars 2025, no 23-16944, in « Droit bancaire – Chronique de jurisprudence »
No full textInternational audienceLa banque n’est tenue de détecter les anomalies apparentes d’un chèque que lorsque celui-ci lui est remis à l’encaissement
L'emploi salarié du tourisme
No full texthttps://gisetudestouristiques.fr/encyclopedie/emploi-salarie-du-tourisme
CoAP/DTLS Protocols in IoT Based on Blockchain Light Certificate
No full textInternational audienceThe Internet of Things (IoT) is expanding rapidly, but the security of IoT devices remains a noteworthy concern due to resource limitations and existing security conventions. This research investigates and proposes the use of a Light certificate with the Constrained Application Protocol (CoAP) instead of the X509 certificate based on traditional PKI/CA. We start by analyzing the impediments of current CoAP security over DTLS with the certificate mode based on CA root in the constrained IoT device and suggest the implementation of LightCert4IoT for CoAP over DTLS. The paper also describes a new modified handshake protocol in DTLS applied for IoT devices and Application server certificate authentication verification by relying on a blockchain without the complication of the signed certificate and certificate chain. This approach streamlines the DTLS handshake process and reduces cryptographic overhead, making it particularly suitable for resource-constrained environments. Our proposed solution leverages blockchain to reinforce IoT gadget security through immutable device characters, secure device registration, and data integrity. The LightCert4IoT is smaller in size and requires less power consumption. Continuous research and advancement are pivotal to balancing security and effectiveness. This paper examines security challenges and demonstrates the effectiveness of giving potential solutions, guaranteeing the security of IoT networks by applying LightCert4IoT and using the CoAP over DTLS with a new security mode based on blockchain
N‐Type Molecular Thermoelectrics Based on Solution‐Doped Indenofluorene‐Dimalononitrile: Simultaneous Enhancement of Doping Level and Molecular Order
No full textInternational audienceThe development of n‐type organic thermoelectric materials, especially π‐conjugated small molecules, lags far behind their p‐type counterparts, due primarily to the scarcity of efficient electron‐transporting molecules and the typically low electron affinities of n‐type conjugated molecules that leads to inefficient n‐doping. Herein, the n‐doping of two functionalized (carbonyl vs dicyanovinylene) indenofluorene‐based conjugated small molecules, 2,8‐bis(5‐(2‐octyldodecyl)thien‐2‐yl)indeno[1,2‐b]fluorene‐6,12‐dione (TIFDKT) and 2,2′‐(2,8‐bis(3‐alkylthiophen‐2‐yl)indeno[1,2‐b]fluorene‐6,12‐diylidene)dimalononitrile (TIFDMT) are demonstrated, with n‐type dopant N‐DMBI. While TIFDKT shows decent miscibility with N‐DMBI, it can be hardly n‐doped owing to its insufficiently low LUMO. On the other hand, TIFDMT, despite a poorer miscibility with N‐DMBI, can be efficiently n‐doped, reaching a respectable electrical conductivity of 0.16 S cm −1 . Electron paramagnetic resonance measurements confirm the efficient n‐doping of TIFDMT. Based on density functional theory (DFT) calculations, the LUMO frontier orbital energy of TIFDMT is much lower, and its wave function is more delocalized compared to TIFDKT. Additionally, the polarons are more delocalized in the n‐doped TIFDMT. Remarkably, as indicated by the grazing‐incidence wide‐angle X‐ray scattering (GIWAXS), the molecular order for TIFDMT thin‐film is enhanced by n‐doping, leading to more favorable packing with edge‐on orientation and shorter π‐π stacking distances (from 3.61 to 3.36 Å). This induces more efficient charge transport in the doped state. Upon optimization, a decent thermoelectric power factor of 0.25 µWm −1 K −2 is achieved for n‐doped TIFDMT. This work reveals the effect of carbonyl vs dicyanovinylene on the n‐doping efficiency, microstructure evolution upon doping and thermoelectric performance, offering a stepping stone for the future design of efficient n‐type thermoelectric molecules
Spectral Walsh analysis and surrogate-assisted optimization: example of the bus stops spacing problem
No full textInternational audienceUsing surrogate-assisted optimization is an efficient way to deal with computationally expensive black-box problems. This method guides the search towards promising solutions and therefore reduces the time needed to find good solutions. In this paper, we focus on surrogates based on Walsh functions that are effective to solve pseudo-Boolean problems. An example is given with the bus stops spacing problem on single and multiple bus lines. One of the main issues with surrogate-assisted optimization is the growth of the number of terms of the model when the dimension gets high. To address this problem, we use a sparse model using only a small amount of relevant terms that is simpler to optimize. To choose the relevant terms, we use in this paper a spectral analysis that allows us to identify main terms and quantify their importance. An asynchronous surrogate-assisted master-workers optimization algorithm is also proposed to tackle this problem