Portail des publications scientifiques IMT Mines Alès
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From Dredging to Restoration: Enhancing Coastal Ecosystems with Reused Sediments
No full textInternational audiencePort areas, located at the land-sea interface, are crucial coastal socio-ecosystems exposed to local pollution and terrigenous inputs from watersheds. Silting and sedimentation in ports pose complex management challenges. It is essential to understand port environments, which requires regular monitoring of water and sediment quality. In-depth knowledge, especially under varying hydroclimatic conditions, helps better understand and manage the effects of dredging operations, including the potential reuse of sediments based on their quality.Special attention has been given to data acquisition and comparing dredging operations at two Mediterranean observatories: the Ghar El Melah lagoon (GEM) in Tunisia, an UNESCO-IHP Ecohydrology Demonstration Site through the Observatory of MEdjerda LIttoral (OMELI) and the Gulf of Aigues-Mortes (GAM) (France), studied by the Human-Environment Observatory Mediterranean Coastline (OHM-LM). Research at these sites focuses on knowing, understanding, and better managing coastal ecosystems. Extensive fieldwork, including spatio-temporal monitoring during various cycles and dredging operations, has been conducted between 2019 and 2023 to determine chemical contamination and characterisation of water and sediments. The resulting database, analyzed with chemical tracers, helps identify major contamination sources, understand contaminant dynamics and distribution and sediment proprieties. A crucial aspect of this work involves the precise characterization of sediments. detailed characterizations of dredged sediments (composition, classification, distribution, ...) open up opportunities for valorization.At the GEM lagoon site, sampling campaigns revealed heterogeneous trace metal contamination in the water column. High arsenic concentrations, exceeding environmental quality standards (EQS), were systematically observed. The northeast zone showed very high copper levels (7 times the EQS), and most water samples had high zinc concentrations. To assess contamination profiles and sediment quality for potential reuse in beach nourishment, sediment toxicity was evaluated using ERL (Effects Range Low) and ERM (Effects Range Median) calculations. Very high cadmium, copper, lead, and zinc levels were found in sediments near ports, likely due to active navigation and high hydrodynamic processes. These spatio-temporal data coupled with physical and mineralogical characterizations will allow for the selection of the most suitable sediments for dune cordon replenishment.In the GAM case, monitoring of chemical contamination in several ports was done before, during and after dredging. Dredging increased chemical concentrations in the water, resuspending trace metals (As, Cu, Zn, Ni) and organotin compounds from sediments. Sediments in concrete formulation was explored. Concrete formulated with 15 or 30% sediments showed properties like the control. Finally, the potential release of contaminants was studied through dynamic leaching tests. While surface leaching followed by diffusion for certain metals was observed, the released quantities remained very low and all below environmental quality standards. These concretes were tested in maritime structures.This approach aims to promote the rational reuse of dredged materials in maritime construction, fostering sustainable and equitable management practices. This includes circular economy principles and nature-based solution, such as beach nourishment, contributing to ecosystem restauration. These efforts are crucial for the sustainable management of port ecosystems, balancing economic development and environmental preservation. The results guide port managers’ decisions, considering meteorology, port usage changes, occupancy and traffic
Compressive Strength Properties Related to Microstructure of Chemically Blown Tannin Foams
No full textInternational audienceBiophenolic foams are of great interest in many applications for their renewability and lightness. In this paper, five formulations of tannin foams produced via chemical foaming using harmless reactants such as tannins, hexamine, and a non‐toxic blowing agent are prepared and characterized. Foams with apparent density varying from 0.072 to 0.087 g/cm 3 have been obtained. The study focuses on the influence of the surfactant and the blowing agent on the physical properties of these foams. First, foam microstructure is analyzed by determining mean window diameter thanks to SEM image treatment and mean cell wall thickness, mean cell diameter, cellular porosity, and internal cell wall porosity thanks to X‐ray tomography. Results show an average window diameter that ranges from 132 to 192 μm. The average cell diameter ranges from 603 to 985 μm and the wall thickness is from 55 to 70 μm. Mechanical properties, in terms of compressive strength, have been determined and a maximum elastic modulus of 2 MPa and a maximum compressive strength of 105 kPa have been obtained for 1.5%w of blowing agent. Microstructure analysis showed that these results in the most homogeneous and the finest cell size distribution. In addition, compressive strength is influenced more by the size of the cells, windows, and walls than by how apparently dense the material appears
A call for robust evaluations of the impacts of serious games for climate change mitigation: example with The Climate Fresk conducted among 2 million participants from 150 countries
No full textSerious games and gamified workshops are increasingly used in sustainability education, yet their actual cognitive, emotional, attitudinal, and behavioral impacts remain under-evaluated. The Climate Fresk is a widely implemented example, with over two million participants in more than 150 countries. Designed to raise climate awareness through collaborative learning and emotional engagement, its growing popularity contrasts with the limited scientific assessment of its effectiveness. This perspective paper uses The Climate Fresk as a case study to examine the broader challenges of evaluating serious games in climate education. Drawing on insights from environmental psychology, educational and behavioral sciences, we analyze its potential mechanisms of action, identify key moderating factors, such as participant characteristics, facilitator attributes, and implementation context, and highlight limitations in current evaluation practices. We conclude by outlining a research agenda that emphasizes the need for rigorous, theory-driven experimental designs, including randomized controlled trials focused on relevant psychological determinants of behavior change. Such efforts are essential to establish the evidence base required to improve the effectiveness, reproducibility, and scalability of gamified climate education interventions
Validation of the French version of the Fremantle Back Awareness Questionnaire in patients with chronic low back pain
No full textInternational audienceImpaired body perception could contribute to the pain experience and be a possible treatment target. The Fremantle Back Awareness Questionnaire (FreBAQ) is the only self-report questionnaire to assess back-specific self-perception. Observational study
Can virtual reality replace conventional vestibular rehabilitation tools in multisensory balance exercises for vestibular disorders? A non-inferiority study
No full textInternational audienceVestibular rehabilitation uses multisensory balance exercises to optimize the integration and weighting of sensory inputs, including visual, vestibular, and proprioceptive signals. Head-mounted displays (HMDs) have emerged as a promising tool for these exercises, offering the ability to generate unreliable or conflicting visual stimuli, thereby enhancing vestibular and proprioceptive input weighting. This study aimed to determine whether a virtual reality (VR)-based rehabilitation program using HMDs is non-inferior to a conventional program employing an optokinetic stimulator and slaved environmental surround for multisensory balance exercises.Methods: seventy-six participants with vestibular disorders were randomized into either the VR-based or conventional rehabilitation program for three weeks in a randomized controlled non-inferiority trial with blinded assessment. The non-inferiority margin was set at 5% of the control group’s score. Both programs were multidisciplinary and included multisensory balance exercises designed to challenge sensory re-weighting. The primary outcome was the stability score, measured with eyes closed on an unstable platform using posturography, to evaluate postural control. Secondary outcomes included other variables from posturography, perceived disability assessed using the Dizziness Handicap Inventory (DHI), and tolerance to the multisensory balance exercises with unreliable or conflicting visual stimuli, assessed using the Simulator Sickness Questionnaire (SSQ).Results: the results showed that multisensory balance exercises with unreliable or conflicting visual stimuli were well tolerated in both groups, as indicated by low SSQ scores. Both rehabilitation programs led to significant pre-post improvements in postural control and perceived disability. However, the VR program did not meet the non-inferiority criterion compared to the conventional program. The primary outcome analysis revealed a difference of − 13.36 (95% CI − 29.84 to 3.11), with the lower bound of the confidence interval (− 29.84) falling below the non-inferiority margin of -2.01. Similarly, secondary outcomes, including other variables from posturography and the DHI, also failed to meet the non-inferiority criterion.Conclusion: although VR rehabilitation shows innovative potential for multisensory balance training, its effectiveness was not demonstrated to be non-inferior to the conventional approach. Therefore, we recommend considering it as a complementary tool rather than a primary device for vestibular rehabilitation. Further research is needed to enhance the efficacy of VR-based rehabilitation for vestibular disorders while maintaining its tolerance
Predicting the Impact of Mobile Field Hospital Deployment in Reducing Patients Mean Wait Times in Emergency Departments: An Agent-Based Simulation Approach
No full textAbstract Mean wait time (MWT) in emergency departments refer to the average time patients spend undergoing evaluation, or treatment at each stage, which can be significantly affected by sudden onsets of a disaster. Agent-based modeling (ABM) is a computational technique that simulates the interactions and behaviors of individual agents in a defined environment and enables the study of complex systems by observing the emergent outcomes of agent-agent and agent-environment interactions. This study examines the capability of ABMs in assessing the impact of response operations on hospital emergency departments mean wait time in a post-explosion scenario for an oil and gas industry. The methodology of this study involves the use of an agent-based modelling and simulation tool (NetLogo 6.3.0) to represent the interaction of agents within an emergency response system defined by rules, goals and decision protocols. The response policy includes both a traditional approach and a collaborative intervention through the use of a mobile field hospital (MFH). The dataset was generated, sampled and analyzed using the BehaviorSpace and Pandas tools, respectively. The results of the simulation study show that the strategic use of MFH for a collaborative response resulted in lower MWT, indicating higher effectiveness and efficiency of response efforts. This study highlights the need to generate potential results and test how response strategies might influence emergency department wait times and demonstrates the capability of simulation techniques in modeling complex systems. This could serve as an important tool for training health workers and disaster managers on emergency response and preparedness
Monitoring of cardiac adaptation in elite soccer players over a season through machine learning
No full textInternational audienceThe aim of this study was to assess the evolution of professional soccer players’ training status bymonitoring an indicator of cardiovascular fitness (ΔHR) over an entire season. The locomotor activity(GPS) and heart rate (HR) of 31 professional soccer players were recorded during small-sided games (SSG)during the 2022–2023 season. Individual predictive models of HR responses built using machine learningmethods (i.e. Linear Regression, Support Vector Machine, Random Forest, and eXtreme Gradient Boosting)were trained on a dataset that contains GPS and weather data, Borg CR-10 scale scores andcumulative load. ΔHR was defined as the difference between predicted and measured HR responses.Robustness of models was assessed through a resampling procedure (n = 20). A difference in ΔHRbetween months was found (p < .05), with a decrease of ΔHR between the early and the middle of theseason, and an increase between the middle and the end of the season. The best HR predictiveperformance was obtained by Random Forest models trained on data including GPS, weather andpreceding training load (Mean Absolute Error = 6.59 ± 1.41). Given its ease of use in the context of elitefootball, ΔHR represents an invisible method to follow elite football players’ training status
Multiscale structural analysis of plant fibre-reinforced thermoplastic biocomposites: Towards realistic 2D and 3D descriptors for advanced modelling
No full textInternational audienceThis study presents an in-depth microstructural analysis of injection-moulded polypropylene composites reinforced with flax shives (FS) of different sizes and compounded by twin-screw extrusion. A multi-scale approach, using laser diffraction, 2D scanning, scanning electron microscopy (SEM) and X-ray tomography, is developed to investigate the influence of initial FS size distribution on composite microstructure, including FS size and shape distribution, orientation, and dispersion. The 2D scanner proves to be the most practical and user-friendly tool for measuring FS size and shape distribution. Fibre size reduction during extrusion was successfully modelled, particularly for aspect ratio estimation, with medium-sized particles yielding the highest aspect ratios in injection moulded specimens. SEM observations reveals that fine particles give the best dispersion. FS orientation analysis using X-ray tomography shows that medium-sized particles align more along the injection flow compared to coarser particles. Such 2D and 3D microstructural analyses are required for advanced modelling of biocomposite properties