Numerical approach for assessing combustion noise in compression-ignited Diesel engines

[EN] Diesel combustion noise has become a crucial aspect for the engine manufacturers due to its impact on human health and influence on the customer purchasing decision. The interaction of the pressure waves after mixture self-ignition induces cavity resonances inside the combustion chamber. This complex phenomenon produces high-frequency pressure oscillations, hence traditional in-cylinder measurements do not provide enough information to characterise the in-cylinder acoustic field. In this paper, a numerical methodology is proposed for assessing the Diesel combustion as a noise source and to overcome measurement limitations. An optimisation procedure is also presented in order to determine the numerical calculation parameters, boundary conditions definition and initialization. Results show that local flow conditions at the start of combustion have a strong influence on the acoustic response of the in-cylinder noise source. These particular conditions are only achievable by the proposed methodology which considers entire engine cycle simulations with the complete cylinder domain. Therefore, traditional Computational Fluid Dynamic (CFD) approaches, such those used for predicting combustion stability or pollutant emissions, are not suitable for reproducing the physical mechanisms of noise generation and they cannot be used for acoustic purposes. The reliability of the proposed methodology to simulate the acoustic field accurately inside the combustion chamber has been validated by comparison with experiments.The equipment used in this work has been partially supported by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energdtica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)", framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economia y Competitividad. J. Gomez-Soriano is partially supported through the "Programa de Apoyo para la Investigacion y Desarrollo (PAID)" of Universitat Politecnica de Valencia [Grant No. FPI-S2-2016-1353].Torregrosa, AJ.; Broatch, A.; Gil, A.; Gómez-Soriano, J. (2018). Numerical approach for assessing combustion noise in compression-ignited Diesel engines. Applied Acoustics. 135:91-100. https://doi.org/10.1016/j.apacoust.2018.02.006S9110013

Impact de la réactualisation de recommandations de pratiques cliniques sur l'évolution d'une base de connaissances.

International audienceL'évolution constante et rapide des connaissances médicales requiert une mise à jour des recommandations de pratiques cliniques (RPC). En conséquence, les systèmes d'aide à la décision médicale qui s'appuient sur ces RPC et qui favorisent leur mise en œuvre par les praticiens doivent suivre cesévolutions. Dans une perspective de modélisation, nous proposons une caractérisation formelle des différents modes d'évolution des connaissances au sein de 2 versions successives d'une RPC. Chaque recommandation atomique est représentée sous la forme d'une règle reliant un plan d'actions recommandé à une situation clinique particulière. En utilisant des comparaisons basées sur des mécanismes de subsomption, nous avons identifié 7 patrons d'évolution possibles pour une recommandation issue d'une mise à jour. La méthode a été appliquée sur les mises à jour de 2002 et 2004 des recommandations de prise en charge des tumeurs superficielles de la vessie. De façon surprenante, les résultats montrent un recouvrement faible, puisque plus de la moitié des recommandations 2002 (59 %) sont considérées obsolètes en 2004 et pr ès des 2/3 des recommandations 2004 (67 %) sont considérées comme nouvelles

How updating textual clinical practice guidelines impacts clinical decision support systems: a case study with bladder cancer management.

Guideline-based clinical decision support systems (CDSSs) can be effective in increasing physician compliance with recommendations. However, the ever growing pace at which medical knowledge is produced requires that clinical practice guidelines (CPGs) be updated regularly. It is therefore mandatory that CDSSs be revised accordingly. The French Association for Urology publishes CPGs on bladder cancer management every 2 years. We studied the impact of the 2004 revision of these guidelines, with respect to the 2002 version with a CDSS, UroDoc. We proposed a typology of knowledge base modifications resulting from the update of CPGs making the difference between practice, clinical conditions and recommendations refinement as opposed to new practice and new recommendations. The number of formalized recommendations increased from 577 in 2002 to 1,081 in 2004. We evaluated the two versions of UroDoc on a randomized sample of patient records. A single new practice that modifies a decision taken in 49% of all recorded decisions leads to a fall from 67% to 46% of the compliance rate of decisions

Clinical Anatomy of the Quadriceps Femoris and Extensor Apparatus of the Knee

Most descriptions of the extensor mechanism of the knee do not take into account its complexity and variability. The quadriceps femoris insertion into the patella is said to be through a common tendon with a three-layered arrangement: rectus femoris (RF) most superficially, vastus medialis (VM) and lateralis (VL) in the intermediate layer, and vastus intermedius (VI) most deeply. We dissected 20 limbs from 17 cadavers to provide a more detailed description of the anterior components of the knee: the tendon, the patellar retinacula, and the patellofemoral ligaments. Only three of the 20 specimens exhibited the typically described quadriceps pattern. The remainder had bilaminar and even more complex trilaminar and tetralaminar fiber arrangements. We found an oblique head of the vastus lateralis (VLO), separated from the longitudinal head by a layer of fat or fascia, in 60% of the specimens. However, we found no distinct oblique head of the vastus medialis (VMO) in any specimen. The medial patellofemoral ligament (MPFL) was more common than the lateral (LPFL), supporting its suggested role as the principal passive medial stabilizer of the patella. Because the quadriceps muscle group plays a direct role in patellofemoral joint function, investigation into the clinical applications of its highly variable anatomy may be worthwhile with respect to joint dysfunction and failures of TKAs