De la modélisation du broyage

Cet article recense les diverses approches mises en œuvre dans le domaine du broyage des solides depuis des décennies (approche minéralurgique, approche mécanique, approche génie des procédés et approche statistique des distributions). Ces approches disciplinaires ne peuvent à elles seules traduire toute la complexité de cette opération unitaire. Elles ne peuvent au mieux que trouver des applications limitées. Seules les approches globales, qui intègrent la complexité du matériau (densité, microstructure, ...), le procédé technologique de broyage (vertical, horizontal, à corps fixes, ...) et les caractéristiques du matériau divisé convoité, permettront de concevoir, de dimensionner ou d’optimiser l’opération de broyage industriel

Reprocessing of artificial UV-weathered wood flour reinforced polypropylene composites

This work aims to determine and understand the influence of UV weathering on the reprocessing of a wood-plastic composite (WPC), i.e. of a wood flour reinforced polypropylene (PP) composites. Two wood flour contents (10% w/w and 30% w/w) were studied in comparison with neat PP. Compounds were produced by twin-screw extrusion. Then, ISO1A “dog bone” samples were obtained by injection molding and exposed to an artificial UV weathering using a xenon arc climatic chamber in order to simulate a long-term outdoor exposure. After this weathering stage, photo-degraded samples were submitted to grinding and injection cycles and characterized through different experimental technics. The visual evolution of the surface was followed by optical microscopy and scanning electron microscopy. In order to understand the material physical degradation, the mechanical behavior was measured thanks to tensile, Charpy impact and DMTA (Dynamic Mechanical Thermal Analysis) tests. The assessment of the microstructural evolution was performed by differential scanning calorimetry (crystallinity ratio), size exclusion chromatography (average molecular weights) tests and infrared spectroscopy (chemical structure). Additional rheological tests assessed assumptions on degradation mechanisms

Managed ventricular pacing compared with conventional dual-chamber pacing for elective replacement in chronically paced patients: results of the Prefer for Elective Replacement Managed Ventricular Pacing randomized study.

BACKGROUND Several studies have shown that unnecessary right ventricular pacing has detrimental effects. OBJECTIVE To evaluate whether minimization of ventricular pacing as compared with standard dual-chamber pacing (DDD) improves clinical outcomes in patients referred for pacemaker or implantable cardioverter-defibrillator (ICD) replacement. METHODS In an international single-blind, multicenter, randomized controlled trial, we compared DDD with managed ventricular pacing (MVP), a pacing mode developed to minimize ventricular pacing by promoting intrinsic atrioventricular conduction. We included patients referred for device replacement with >40% ventricular pacing, no cardiac resynchronization therapy upgrade indication, no permanent atrial fibrillation (AF), and no permanent complete atrioventricular block. Follow-up was for 2 years. The primary end point was cardiovascular hospitalization. The intention-to-treat analysis was performed by using Kaplan-Meier method and the log-rank test

MACVIA-LR, Reference site of the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) in Languedoc Roussillon

International audienc

Introduction

International audienc