Rural area flooding digital prediction based on TELEMAC-2D

Hydrodynamic

Coastal sediment modelling (TELEMAC-2D / TOMAWAC / GAIA): scour in offshore wind farm

Hydrodynamic

Simulation of urban waterlogging with TELEMAC-2D/SWMM coupled model

Hydrodynamic

The atherogenic index of plasma (AIP) is a predictor for the severity of coronary artery disease

ObjectiveDyslipidemia is a key risk factor for coronary artery disease (CAD). This study aimed to investigate the correlation between the atherogenic index of plasma (AIP) and the severity of CAD.Methods2,491 patients were enrolled in this study and analyzed retrospectively, including 665 non-CAD patients as the control group and 1,826 CAD patients. The CAD patients were classified into three subgroups according to tertiles of SYNTAX score (SS). Non-high-density lipoprotein cholesterol (Non-HDL-C) was defined as serum total cholesterol (TC) minus serum high-density lipoprotein cholesterol (Non-HDL-C), atherogenic index (AI) was defined as the ratio of non-HDL-C to HDL-C; AIP was defined as the logarithm of the ratio of the concentration of triglyceride (TG) to HDL-C; lipoprotein combine index (LCI) was defined as the ratio of TC∗TG∗ low-density lipoprotein cholesterol (LDL)to HDL-C; Castelli Risk Index I (CRI I) was defined as the ratio of TC to HDL-C; Castelli Risk Index II (CRI II) was defined as the ratio of LDL-C to HDL-C.ResultsThe levels of AIP (P < 0.001), AI (P < 0.001), and LCI (P = 0.013) were higher in the CAD group compared with the non-CAD group. The Spearman correlation analysis showed that AIP (r = 0.075, P < 0.001), AI (r = 0.132, P < 0.001), and LCI (r = 0.072, P = 0.001) were positively correlated with SS. The multivariate logistic regression model showed CRI I (OR: 1.11, 95% CI: 1.03–1.19, P = 0.005), CRI II (OR: 1.26, 95% CI: 1.15–1.39, P < 0.001), AI (OR: 1.28, 95% CI: 1.17–1.40, P < 0.001), AIP (OR: 2.06, 95% CI: 1.38–3.07, P < 0.001), and LCI (OR: 1.01, 95% CI: 1.01–1.02, P < 0.001) were independent predictors of severity of CAD After adjusting various confounders.ConclusionCRI I, CRI II, AIP, AI, and LCI were independent predictors of the severity of CAD, which could be used as a biomarker for the evaluation of the severity of CAD

Comportement transitionnel et stabilisation de flammes-jets non-prémélangés de méthane dans un coflow d’air dilué en CO2

This work focuses on the understanding of the behaviours of non-premixed methane flame inside an air coflow diluted by carbon dyoxide (CO2) or by other chemically inert diluents in order to discriminate different phenomena involved in dilution. Transitional phenomena (liftoff and extinction) quantified trough the stability limits, are analyzed trough representative physical quantities. The flame stability domain is limited by 3D-surfaces (liftoff and extinction) in the physical domain (Qdiluant/Qair (dilution level), Uair (air velocity), UCH4 (methane velocity)) revealing a competitive effect between aerodynamics and dilution. Generic diagrams of flame liftoff and extinction are proposed for all the diluents. Physical quantities related to flame stabilization process are all submitted to, regardless of diluent, self-similar laws. This is explained by flame burning velocity which is considered as the key element in the flame stabilization mechanism with air-side dilution.Ce travail s'intéresse à la compréhension du comportement des flammes non-prémélangées issues d'un jet de méthane assisté par un coflow d'air dilué avec du CO2, ou d'autres gaz chimiquement inertes pour discriminer les différents phénomènes impliqués dans la dilution. Les phénomènes transitionnels, décrochage et extinction, quantifiés par des limites de stabilité, sont analysés à l'aide de grandeurs physiques représentatives. Le domaine de stabilité de flamme est limité par des surfaces 3D dans le domaine physique ( Qdiluant/Qair (taux de dilution), Uair (vitesse d'air), UCH4 (vitesse de méthane)), révélant un effet compétitif entre l'aérodynamique et la dilution. Des cartographies génériques de décrochage et d'extinction communes à tous ces diluants sont proposées. Des grandeurs liées à la stabilisation sont toutes soumises à des lois d'évolution auto-simlilaires. Il en ressort que la vitesse de propagation de flamme est l'élément clé du mécanisme de stabilisation lors de la dilution

Transition and stabilization behaviors of non-premixed methane jet flames insaide an air coflow diluted by carbon dioxide

Ce travail s'intéresse à la compréhension du comportement des flammes non-prémélangées issues d'un jet de méthane assisté par un coflow d'air dilué avec du CO2, ou d'autres gaz chimiquement inertes pour discriminer les différents phénomènes impliqués dans la dilution. Les phénomènes transitionnels, décrochage et extinction, quantifiés par des limites de stabilité, sont analysés à l'aide de grandeurs physiques représentatives. Le domaine de stabilité de flamme est limité par des surfaces 3D dans le domaine physique ( Qdiluant/Qair (taux de dilution), Uair (vitesse d'air), UCH4 (vitesse de méthane)), révélant un effet compétitif entre l'aérodynamique et la dilution. Des cartographies génériques de décrochage et d'extinction communes à tous ces diluants sont proposées. Des grandeurs liées à la stabilisation sont toutes soumises à des lois d'évolution auto-simlilaires. Il en ressort que la vitesse de propagation de flamme est l'élément clé du mécanisme de stabilisation lors de la dilution.This work focuses on the understanding of the behaviours of non-premixed methane flame inside an air coflow diluted by carbon dyoxide (CO2) or by other chemically inert diluents in order to discriminate different phenomena involved in dilution. Transitional phenomena (liftoff and extinction) quantified trough the stability limits, are analyzed trough representative physical quantities. The flame stability domain is limited by 3D-surfaces (liftoff and extinction) in the physical domain (Qdiluant/Qair (dilution level), Uair (air velocity), UCH4 (methane velocity)) revealing a competitive effect between aerodynamics and dilution. Generic diagrams of flame liftoff and extinction are proposed for all the diluents. Physical quantities related to flame stabilization process are all submitted to, regardless of diluent, self-similar laws. This is explained by flame burning velocity which is considered as the key element in the flame stabilization mechanism with air-side dilution

Comportement transitionnel et stabilisation de flammes-jets non-prémélangés de méthane dans un coflow d'air dilué en CO2

Ce travail s'intéresse à la compréhension du comportement des flammes non-prémélangées issues d'un jet de méthane assisté par un coflow d'air dilué avec du CO2, ou d'autres gaz chimiquement inertes pour discriminer les différents phénomènes impliqués dans la dilution. Les phénomènes transitionnels, décrochage et extinction, quantifiés par des limites de stabilité, sont analysés à l'aide de grandeurs physiques représentatives. Le domaine de stabilité de flamme est limité par des surfaces 3D dans le domaine physique ( Qdiluant/Qair (taux de dilution), Uair (vitesse d'air), UCH4 (vitesse de méthane)), révélant un effet compétitif entre l'aérodynamique et la dilution. Des cartographies génériques de décrochage et d'extinction communes à tous ces diluants sont proposées. Des grandeurs liées à la stabilisation sont toutes soumises à des lois d'évolution auto-simlilaires. Il en ressort que la vitesse de propagation de flamme est l'élément clé du mécanisme de stabilisation lors de la dilution.This work focuses on the understanding of the behaviours of non-premixed methane flame inside an air coflow diluted by carbon dyoxide (CO2) or by other chemically inert diluents in order to discriminate different phenomena involved in dilution. Transitional phenomena (liftoff and extinction) quantified trough the stability limits, are analyzed trough representative physical quantities. The flame stability domain is limited by 3D-surfaces (liftoff and extinction) in the physical domain (Qdiluant/Qair (dilution level), Uair (air velocity), UCH4 (methane velocity)) revealing a competitive effect between aerodynamics and dilution. Generic diagrams of flame liftoff and extinction are proposed for all the diluents. Physical quantities related to flame stabilization process are all submitted to, regardless of diluent, self-similar laws. This is explained by flame burning velocity which is considered as the key element in the flame stabilization mechanism with air-side dilution.ROUEN-INSA Madrillet (765752301) / SudocSudocFranceF

A Numerical Study on the Effects of CO2/N2/Ar Addition to Air on Liftoff of a Laminar CH4/Air Diffusion Flame

International audienceThe addition of exhaust gas to a combustor may cause liftoff of a diffusion flame due to several possible mechanisms. Understanding the relative influence of these mechanisms is of importance for the further development of exhaust gas recirculation combustion technology. The authors present a numerical study on the effects of CO2, N2 (two of primary exhaust gas components) and Ar addition on the liftoff of a laminar CH4/air diffusion flame. A gradual switch-off approach was used to identify the relative importance of the different mechanisms. A detailed reaction scheme and complex thermal and transport properties were employed. The simulation results were validated by comparing the calculated and previously measured critical ratios of the 3 additives for liftoff. The results show that the numerical simulation successfully reproduced the previously measured critical ratios of liftoff for all 3 studied additives. Detailed analysis of the numerical results suggests that the addition of N2 affects flame liftoff due to the sole effect of dilution. On the other hand, the addition of CO2 causes flame liftoff due to the dilution, thermal and chemical effects, with the dilution effect being the most significant one, followed by the thermal and chemical effects. All 3 effects tend to reduce combustion intensity and cause flame liftoff, leading to the smaller critical ratio of CO2 than that of N2. The radiation and transport property effects are negligible for CO2 addition. Ar addition affects flame liftoff due to dilution, thermal, and transport property effects. However, whereas the dilution effect tends to reduce combustion intensity and cause flame liftoff, the thermal and transport property effects tend to increase combustion intensity and resist flame liftoff for Ar addition, which results in the greater critical ratio of Ar than that of N2. Therefore, for the 3 studied additives in this paper, CO2 has the minimum critical ratio, whereas Ar has the maximum for liftoff