A data-driven approach for studying tribology based on experimentation and artificial intelligence coupling tools

Tribology problems generally, and particularly high-temperature tribology (HTT), is a critical and complex topic based on the interaction between several intrinsic and extrinsic parameters. This involved complex phenomena, resulting in synergistic effects between mechanical, physical, chemical, and thermal solicitations. Introducing artificial intelligence tools, coupled with the design of the experiment, is an original approach to implement a successful transition from traditional "experimental guidance" to "experimental guidance associated with a data-driven" approach. The current study delves into the utilization of machine learning (ML) with simulation to help in the choice of the parameters for experimentation, and the development of predictive models. A detailed framework that takes into account the coupling between such tools is presented. Different scenarios are discussed to data drive the collaborative schema between the design of experiment, numerical development, and ML algorithms. This approach gives several opportunities such as the identification of the well-impacted parameters, optimization of the experimental design, and the proposition of predictive models. With the suitable proposed model, time loss, production costs, precision results, and man-hours could be saved or improved

Effect of the turbulence model on the aerodynamic structure around a Savonius wind rotor

Ce travail vise à étudier l'effet du modèle de turbulence sur les caractéristiques aérodynamiques de l'écoulement autour d'un rotor Savonius. Pour faire, nous avons développé une simulation numérique à l'aide du code commercial CFD Fluent. Le modèle numérique est basé sur la résolution des équations de Navier -Stokes. Ces équations sont résolues par une discrétisation volumes finis. Deux modèles de turbulence sont considérés : le modèle k-ԑ et le modèle k-ԑ RNG. Particulièrement, nous sommes intéressés à visualiser le champ de vitesse, la vitesse moyenne et la pression statique. L'accord entre nos résultats numériques et les résultats antérieurs confirme la validité de la méthode d'analyse adoptée

Characterization Shear Properties of PVC Foams Instrumented by Optical Fiber under Flexural Loading

International audienceThe bending behavior of foam core sandwich composites has increasingly attracted attention and application in industries such as shipbuilding, aircraft and wind turbine industries. The main objective of this research work is the assessment of shear strain in a foam core beam by means of optical fiber sensors during bending test. Experimental studies were conducted on a PVC foam beam in which three optical fibers were embedded in a longitudinal plane across the thickness of the foam core; straight optical fibers measure strains due to the tension/compression load, whereas the sinusoidal fibers catch strains due to the shear load. Finite element model (FEM) was used to predict strain levels in order to validate and explain optical fiber sensor measurements from 3-and 4-point bending tests. The concordance of the shear properties identified by optical-fiber sensor results and obtained by finite element simulation was evaluated to validate the new developed technique of characterization. Results shows good agreement between the experimental and numerical responses

Chemical characterisation and the anti-inflammatory, anti-angiogenic and antibacterial properties of date fruit (Phoenix dactylifera L.)

Ethnopharmacological relevance: Date fruit, Phoenix dactylifera L. has traditionally been used as a medicine in many cultures for the treatment of a range of ailments such as stomach and intestinal disorders, fever, oedema, bronchitis and wound healing. Aim of the review: The present review aims to summarise the traditional use and application of Phoenix dactylifera date fruit in different ethnomedical systems, additionally the botany and phytochemistry are identified. Critical evaluation of in vitro and in vitro studies examining date fruit in relation to anti-inflammatory, anti-angiogenic and antimicrobial activities are outlined. Key Findings: The ethnomedical use of Phoenix dactylifera in the treatment of inflammatory disease has been previously identified and reported. Furthermore, date fruit and date fruit co-products such as date syrup are rich sources of polyphenols, anthocyanins, sterols and carotenoids. In vitro studies have demonstrated that date fruit exhibits antibacterial, anti-inflammatory and anti-angiogenic activity. The recent interest in the identification of the numerous health benefits of dates using in vitro and in vivo studies have confirmed that date fruit and date syrup have beneficial health effects that can be attributed to the presence of natural bioactive compounds. Conclusions: Date fruit and date syrup have therapeutic properties, which have the potential to be beneficial to health. However, more investigations are needed to quantify and validate these effects

Infected pancreatic necrosis: outcomes and clinical predictors of mortality. A post hoc analysis of the MANCTRA-1 international study

: The identification of high-risk patients in the early stages of infected pancreatic necrosis (IPN) is critical, because it could help the clinicians to adopt more effective management strategies. We conducted a post hoc analysis of the MANCTRA-1 international study to assess the association between clinical risk factors and mortality among adult patients with IPN. Univariable and multivariable logistic regression models were used to identify prognostic factors of mortality. We identified 247 consecutive patients with IPN hospitalised between January 2019 and December 2020. History of uncontrolled arterial hypertension (p = 0.032; 95% CI 1.135-15.882; aOR 4.245), qSOFA (p = 0.005; 95% CI 1.359-5.879; aOR 2.828), renal failure (p = 0.022; 95% CI 1.138-5.442; aOR 2.489), and haemodynamic failure (p = 0.018; 95% CI 1.184-5.978; aOR 2.661), were identified as independent predictors of mortality in IPN patients. Cholangitis (p = 0.003; 95% CI 1.598-9.930; aOR 3.983), abdominal compartment syndrome (p = 0.032; 95% CI 1.090-6.967; aOR 2.735), and gastrointestinal/intra-abdominal bleeding (p = 0.009; 95% CI 1.286-5.712; aOR 2.710) were independently associated with the risk of mortality. Upfront open surgical necrosectomy was strongly associated with the risk of mortality (p < 0.001; 95% CI 1.912-7.442; aOR 3.772), whereas endoscopic drainage of pancreatic necrosis (p = 0.018; 95% CI 0.138-0.834; aOR 0.339) and enteral nutrition (p = 0.003; 95% CI 0.143-0.716; aOR 0.320) were found as protective factors. Organ failure, acute cholangitis, and upfront open surgical necrosectomy were the most significant predictors of mortality. Our study confirmed that, even in a subgroup of particularly ill patients such as those with IPN, upfront open surgery should be avoided as much as possible. Study protocol registered in ClinicalTrials.Gov (I.D. Number NCT04747990)

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity > 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI

Influence du couplage frottement-oxydation sur l’usure d’un acier à outil de travail à chaud : développement d’un tribomètre spécifique au cyclage de matriçage

Life time improvement of hot working tools becomes one of the major industrial issue unsufficiently mastered. Indeed, loadings induced by hot forming involve coupling between thermal, mechanical, tribological and physicochemical phenomena. They lead to multiple degradation modes (mainly by plastic deformation, thermo-mechanical fatigue, friction and oxidation). Friction induces one of the most detrimental damage, which is difficult to apprehend and to control allowing for the complexity of engaged couplings.This thesis deals with wear of tool steel X40CrMoV5-1 in the case of hot forging of brass. Damage and wear mechanisms were analyzed through an expertise of matrices after used in production. It reveals different types of damage, activated thanks to location and exposure of the matrix surface to cyclic loadings induced during forging. A scenario of a three-body abrasion is proposed maintained by working cycles and wherein brass and toll steel oxides are crucial.Oxidation and pre-oxidized tribological behavior of tool steel were investigated. An original test is proposed to study the influence of hot working cycling on friction-oxidation coupling and its effects on the wear of tool steel. A specific tribometer has been developed. The friction tests are defined by analogy with the hot-working cycle, without reproducing the forming process, favoring formation and trapping of oxides inside the contactL’amélioration de la durée de vie des outillages de mise en forme à chaud constitue un enjeu industriel important et encore mal maitrisé. En effet, les sollicitations induites lors de la mise en forme mettent en jeu des couplages impliquant des phénomènes thermiques, mécaniques, tribologiques et physicochimiques. Les modes de dégradation engendrés sont multiples, principalement par déformation plastique, par fatigue thermomécanique, par frottement et par oxydation. Les dégradations par frottement demeurent parmi les plus pénalisantes et les plus difficiles à appréhender et à maîtriser compte tenu de la complexité des couplages mis en jeu.Cette thèse aborde l’usure de l’acier à outil X40CrMoV5-1 dans le cas du matriçage à chaud du laiton. Les mécanismes d’endommagement et d’usure ont été analysés par le biais d’une expertise de matrices usées en production. Elle révèle différents types de dégradations, activés selon la localisation et l’exposition des surfaces aux sollicitations cycliques de matriçage. Elle a permis d’établir un scénario d’usure par abrasion à trois corps entretenu par le cyclage et dans lequel les oxydes du laiton et de l’acier à outil sont déterminants.L’oxydation de l’acier à outil et son comportement tribologique dans un état pré-oxydé ont été étudiés. Un essai original est proposé pour étudier l’influence du cyclage de matriçage sur le couplage frottement oxydation et ses conséquences sur l’usure. Un tribomètre spécifique a été développé et mis au point. Les essais de frottement reposent sur une analogie avec le cycle de matriçage, sans reproduire la mise en forme, et un contact conforme favorable à la formation et au piégeage des oxyde

Influence of friction-oxidation coupling on wear of a hot-working tool steel : development of a tribometer dedicated to hot-forging cycling

L’amélioration de la durée de vie des outillages de mise en forme à chaud constitue un enjeu industriel important et encore mal maitrisé. En effet, les sollicitations induites lors de la mise en forme mettent en jeu des couplages impliquant des phénomènes thermiques, mécaniques, tribologiques et physicochimiques. Les modes de dégradation engendrés sont multiples, principalement par déformation plastique, par fatigue thermomécanique, par frottement et par oxydation. Les dégradations par frottement demeurent parmi les plus pénalisantes et les plus difficiles à appréhender et à maîtriser compte tenu de la complexité des couplages mis en jeu.Cette thèse aborde l’usure de l’acier à outil X40CrMoV5-1 dans le cas du matriçage à chaud du laiton. Les mécanismes d’endommagement et d’usure ont été analysés par le biais d’une expertise de matrices usées en production. Elle révèle différents types de dégradations, activés selon la localisation et l’exposition des surfaces aux sollicitations cycliques de matriçage. Elle a permis d’établir un scénario d’usure par abrasion à trois corps entretenu par le cyclage et dans lequel les oxydes du laiton et de l’acier à outil sont déterminants.L’oxydation de l’acier à outil et son comportement tribologique dans un état pré-oxydé ont été étudiés. Un essai original est proposé pour étudier l’influence du cyclage de matriçage sur le couplage frottement oxydation et ses conséquences sur l’usure. Un tribomètre spécifique a été développé et mis au point. Les essais de frottement reposent sur une analogie avec le cycle de matriçage, sans reproduire la mise en forme, et un contact conforme favorable à la formation et au piégeage des oxydesLife time improvement of hot working tools becomes one of the major industrial issue unsufficiently mastered. Indeed, loadings induced by hot forming involve coupling between thermal, mechanical, tribological and physicochemical phenomena. They lead to multiple degradation modes (mainly by plastic deformation, thermo-mechanical fatigue, friction and oxidation). Friction induces one of the most detrimental damage, which is difficult to apprehend and to control allowing for the complexity of engaged couplings.This thesis deals with wear of tool steel X40CrMoV5-1 in the case of hot forging of brass. Damage and wear mechanisms were analyzed through an expertise of matrices after used in production. It reveals different types of damage, activated thanks to location and exposure of the matrix surface to cyclic loadings induced during forging. A scenario of a three-body abrasion is proposed maintained by working cycles and wherein brass and toll steel oxides are crucial.Oxidation and pre-oxidized tribological behavior of tool steel were investigated. An original test is proposed to study the influence of hot working cycling on friction-oxidation coupling and its effects on the wear of tool steel. A specific tribometer has been developed. The friction tests are defined by analogy with the hot-working cycle, without reproducing the forming process, favoring formation and trapping of oxides inside the contac