Projektionen

Die beiden Künstler Mathias Vetter und François Chalet haben für die Veranstaltung Passagen Übertragungen Medialitäten eine Installation mit dem Titel Projektionen realisiert.Das Essay von Renée Ener lässt ahnen, dass es sich bei Projektionen nicht nur um ein pathologisches Symptom handelt, sondern um einen immer auch medialen und sich neu medialisierenden Weltentwurf

Mapping the Insomnia Severity Index instrument to EQ-5D health state utilities: a United Kingdom perspective

Objective: This study aimed to map the Insomnia Severity Index (ISI) to the EQ-5D-3L utility values from a UK perspective. Methods: Source data were derived from the 2020 National Health and Wellness Survey (NHWS) for France, Germany, Italy, Spain, the UK and the US. Ordinary least squares regression, generalised linear model (GLM), censored least absolute deviation, and adjusted limited dependent variable mixture model (ALDVMM) were employed to explore the relationship between ISI total summary score and EQ-5D utility while accounting for adjustment covariates derived from the NHWS. Fitting performance was assessed using standard metrics, including mean-squared error (MSE) and coefficient of determination (R2). Results: A total of 17,955 respondent observations were included, with a mean ISI score of 12.12 ± 5.32 and a mean EQ-5D-3L utility (UK tariff) of 0.71 ± 0.23. GLM gamma-log and ALDVMM were the two best performing models. The ALDVMM had better fitting performance (R2 = 0.320, MSE 0.0347) than the GLM gamma-log (R2 = 0.303, MSE 0.0353); in train-test split-sample validation, ALDVMM also slightly outperformed the GLM gamma-log model, with an MSE of 0.0351 versus 0.0355. Based on fitting performance, ALDVMM and GLM gamma-log were the preferred models. Conclusions: In the absence of preference-based measures, this study provides an updated mapping algorithm for estimating EQ-5D-3L utilities from the ISI summary total score. This new mapping not only draws its strengths from the use of a large international dataset but also the incorporation of adjustment variables (including sociodemographic and general health characteristics) to reduce the effects of confounders

Projektionen

Die beiden Künstler Mathias Vetter und François Chalet haben für die Veranstaltung Passagen Übertragungen Medialitäten eine Installation mit dem Titel Projektionen realisiert.Das Essay von Renée Ener lässt ahnen, dass es sich bei Projektionen nicht nur um ein pathologisches Symptom handelt, sondern um einen immer auch medialen und sich neu medialisierenden Weltentwurf

Impact of Blow-By Gas and Endgap Ring Position on the Variations of Particle Emissions in Gasoline Engines

Particulate emission from internal combustion engines is a complex phenomenon that needs to be understood in order to identify its main factors. To this end, it appears necessary to study the impact of unburned gases, called blow-by gases, which are reinjected into the engine intake system. A series of transient tests demonstrate their significant contribution since the particle emissions of spark-ignition engines are 1.5 times higher than those of an engine without blow-by with a standard deviation 1.5 times greater. After analysis, it is found that the decanter is not effective enough to remove completely the oil from the gases. Tests without blow-by gases also have the advantage of having a lower disparity, and therefore of being more repeatable. It appears that the position of the “endgap” formed by the first two rings has a significant impact on the amount of oil transported towards the combustion chamber by the backflow, and consequently on the variation of particle emissions. For this engine and for this transient, 57% of the particulate emissions are related to the equivalence ratio, while 31% are directly related to the ability of the decanter to remove the oil of the blowby gases and 12% of the emissions come from the backflow. The novelty of this work is to relate the particles fluctuation to the position of the endgap ring

Consequence of Blowby Flow and Idling Time on Oil Consumption and Particulate Emissions in Gasoline Engine

Pollutant emission standards and, in particular, those concerning particles from an internal combustion engine (ICE) are becoming increasingly restrictive. Thus, it is important to determine the main factors related to the production of particulate matter. In this article, the phenomenon of oil sweeping by the blowby gases between the rings/piston/cylinder is investigated. First, a blowby gas simulation model based on experimental results from a Turbocharged Gasoline Direct Injection (TGDI) is developed. From this model, it is possible to characterise the amount of oil swept by the blowby gases. This depends on the endgap position of both the compression and sealing rings. It also depends on the intensity of the blowby flow rate, which is highest at low rpm and high load. At 1500 rpm and full load, this flowrate exceeds 25 mg.cycle−1. From this result, it is possible to quantify the amount of oil swept by these gases as a function of the endgap position. For θrings=180°,  the quantity of oil swept rises to 20 µg.cycle−1 while for θrings=30°, this decreases to 6 µg.cycle−1. The oil concentration of the blowby gas has a direct impact on the particulate emissions because the oil concentration of the backflow gas is inversely proportional to the blowby gas flowrate. As the backflow gases return to the cylinder, the oil oxidises and produces particles. Therefore, it is essential to control the oil concentration of the backflow gases. In addition, the simulation model shows the blowby flowrate becomes negative and decreases to −3.4 mg. cycle−1 in idle conditions. The amount of oil swept by the blowby is no longer directed towards the oil pan, but towards the piston crown. This phenomenon of oil storage of the piston crown in idle condition is proportional to the duration of the idle time. In order to confirm these results, experimental tests are carried out on a TGDI engine. It appears that when the idling time changes from 0 s to 7 s between two strictly identical accelerations, the level of particulate emissions is multiplied by 1.3. When the idling time changes from 0 s to 22 s between two strictly identical accelerations, the level of particulate emissions is multiplied by 3. These results confirm the mechanism of oil storage at idle highlighted by the simulation model

Étude et modélisation des ondes de pression dans les géométries complexes (application à la simulation du fonctionnement d'un moteur à combustion interne)

Cette thèse traite des phénomènes de propagation des ondes de pression dans les systèmes d'admission et d'échappement des moteurs à combustion interne. Ces derniers sont constitués d'éléments tubulaires reliés entre eux par différents type de singularités (coude, jonction, collecteur, boîtier papillon,) qui affectent la forme des ondes engendrées par l'ouverture et la fermeture des soupapes. La démarche mise en œuvre pour comprendre et analyser les phénomènes observés consiste à améliorer le logiciel SELENDIA (développé au laboratoire) simulant le fonctionnement d'un moteur complet. L'objectif est de remplacer la méthode de vidange remplissage pour les systèmes d'admission et d'échappement par une modélisation unidimensionnelle. La première étape repose sur la détermination du schéma numérique le mieux adapté à la résolution des équations de la dynamique des gaz. Puis, chacune des singularités est caractérisée par une étude au moyen d'un code de calcul CFD accompagnée d'une validation expérimentale sur un tube à chocs. L'ensemble des modèles développés est ensuite intégré au sein du logiciel de simulation du fonctionnement des moteurs. La validation de toute la procédure est finalement réalisée par comparaison avec des mesures effectuées sur un moteur test, instrumenté spécifiquement pour cette étude. Le logiciel ainsi obtenu se présente comme un moyen d'analyse des phénomènes observés au banc d'essais, mais aussi d'assistance à la conception et à l'optimisation des moteurs à combustion interne.NANTES-BU Sciences (441092104) / SudocNANTES-Ecole Centrale (441092306) / SudocSudocFranceF

Characterization of particle emissions of turbocharged direct injection gasoline engine in transients and hot start conditions

International audienc

A territorial diagnostic of the French region Pays de la Loire through the prism of energy metabolism

International audienc

Some basic elements to achieve a future 1D simulation of wave propagation in I.C.E. pipes

Design, Operation, and Application of Modern Internal Combustion Engines and Associated SystemsConference Sponsors: Internal Combustion Engine DivisionISBN: 0-7918-1688-5International audienceThe assumption of one-dimensional unsteady flows in the inlet and exhaust systems of turbocharged diesel engines is widely used although multi-dimensional simulations using fluid dynamics are also possible. However, difficulties persist concerning the boundary conditions, particularly at the pipe ends (inflow or outflow) and at the intra-pipe boundary conditions (sudden or gradual area changes, bends, junctions, etc.). This paper focuses on the two first steps leading to a 1D flow simulation code: the selection of a numerical scheme and the study of an open end boundary condition. The first section compares several numerical algorithms, including Lax-Wendoff, Flux-Corrected-Transport methods (FCT), and Harten-Lax-Leer (Riemann solver), extended to the second order. The selection criterion is the best compromise between numerical instabilities and computational time. A numerical study using the Fluent CFD code is then presented on a constant area duct in order to determine some characteristics at the pipe end, specifically the dead zone length and the throat area. Finally, a model parameterized by the pressure ratio between inlet and outlet is proposed