811 research outputs found
Product Quality and Worker Quality
We study the relation between product quality and worker quality using an economic model that, under certain conditions, provides a direct link between product price, product quality and work force quality. Our measures of product quality are the evolution in the detailed product price relative to its product group and the level of the product price relative to this group. Our worker quality measures are the firm's average person effect and personal characteristics effect from individual wage rates. We find a very weak, generally positive, relation between worker quality and product quality using detailed firm-level data from the French Producer Price Index surveys.
Choix d'un associateur 2-D pour le balayage multiple et optimisation de l'estimation des pistes
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal
Mesure de la réfractivité atmosphérique par radar météorologique : comparaison avec un réseau de capteurs au sol.
International audienceLes radars météorologiques peuvent mesurer les changements de l'indice de réfraction de l'air dans les basses couches de l'atmosphère (Fabry et al., 1997, Fabry 2004). En utilisant les changements de phase provenant de cibles fixes aux alentours du radar, cette mesure permet d'obtenir une mesure de la réfractivité atmosphérique. Celle-ci dépend de la pression, la température et l'humidité. Les échos exploitables proviennent en général des cibles fixes telles que des châteaux d'eau, des tours ou des pylônes électriques. Pendant la campagne HyMeX (Hydrological cycle in Mediterranean expriment), cette mesure a été implémentée avec succès sur les radars bande S du réseau opérationnel de Météo-France. Afin de mieux comprendre les sources d'erreur autour de cette mesure, en particulier lorsque l'on monte en fréquence, Besson et al. 2012 a mené une simulation à partir des données de stations météorologiques automatiques. Cela a permis de mettre en avant une plus forte variabilité du signal l'été et en fin d'après-midi, quand la réfractivité est très sensible aux changements d'humidité. Cette simulation a ensuite été confirmée par des mesures radar. Est-il alors possible d'obtenir une information sur la turbulence à partir de cette mesure ? Pour échantillonner la variabilité spatiale et temporelle de la réfractivité, une analyse a été menée sur un an de données provenant du radar en bande C de Trappes, conjointement à une comparaison avec les stations automatiques alentours. L'étude présentée ici a permis de montrer qu'un lien qualitatif et quantitatif peut être établi entre les variabilités de la réfractivité mesurée par radar ou par les stations automatiques, qui sont liées à la turbulence atmosphérique de basses couches
Brugada Type 1 Pattern and Risk Stratification for Sudden Death: Does the Key Hide in the ECG Analysis?
Primary prevention of ventricular fibrillation is at the heart of the management of Brugada syndrome. Several recent studies have shown that the analysis of simple electrocardiographic criteria could help to stratify the risk of sudden death. In the present work, 12 markers were studied: spontaneous and permanent type 1 pattern, first-degree atrioventricular block, sinus node dysfunction, wide QRS in V2, aVR sign, fragmented QRS, S-waves in DI, early repolarization pattern, atrial fibrillation, type 1Â in peripheral leads pattern, and long Tpeak-Tend interval. These electrical markers reflect abnormalities in conduction, depolarization, and repolarization that may indicate the severity of the disease. In this chapter, we carry out a review of these markers, their method of determination on the surface ECG, and the main studies highlighting their prognostic impact. We also review the main underlying pathophysiological hypotheses of Brugada syndrome
Buttock pressure management of able-bodied people seated on a rigid surface for two hours.
International audienceIt is now well known that deep pressure ulcers are due to excessive pressure intensity (leading to soft tissues internal strains above 50 % for some minutes) and prolonged compression (leading to internal strains above 20 % for about two hours). This paper aims at better understanding why able-bodied individuals put in quite extreme conditions (i.e seated for 2 hours long on a rigid surface) do not get pressure ulcers. Thirty young healthy subjects agreed to stay seated on a rigid surface during two hours while watching a movie. The buttocks/seat interface pressures were recorded by a pressure mapping system
The Effect of Dietary Protein Levels in Isocaloric Diets on the Composition of Avian Pancreatic Juice 1 ' 2
ABSTRACT A permanent indwelling cannula was placed in the main pancreatic duct of 10-weekold commercial strain male chickens. The birds were fed isocaloric corn-soybean meal diets containing either 11.5% or 18.5% crude protein for two 5-day periods in a reversal experimental design. Irrespective of diet, chickens consumed more feed and secreted more pancreatic juice during the daytime than during the nighttime (P-C01). The concentrations of crude protein and chloride ion and the activities of trypsin, chymotrypsin, and amylase in the pancreatic juice were the same for the daytime and nighttime periods. Significant differences were observed between the two collection periods for the total quantities of these materials secreted (P<.01). Although the chicksns consumed equal amounts of the two rations, trypsin and chymotrypsin responded to the dietary change. Greater proteolytic enzyme activities were found in the pancreatic juice as a response to eating the 18.5% protein diet. The chickens remained in excellent condition throughout the experiment, the cannulas remained unobstructed, and the pancreata secreted up to seven weeks with no cessation of flow
Multi-input genetic algorithm for experimental optimization of the reattachment downstream of a backward-facing step with surface plasma actuator
The practical interest of flow control approaches is no more debated as flow control provides an effective mean for considerably increasing the performances of ground or air transport systems, among many others
applications. Here a fundamental configuration is investigated by using non-thermal surface plasma discharge. A dielectric barrier discharge is installed at the step corner of a backward-facing step (Reh=30000, ReÂż=1650). Wall pressure sensors are used to estimate the reattaching location downstream of the step. The primary objective of this paper is the coupling of a numerical optimizer with an experiment. More specifically, optimization by genetic algorithm is implemented experimentally in order to minimize the reattachment point downstream of the step model. Validation through inverse problem is firstly demonstrated. When coupled with the plasma actuator and the wall pressure sensors, the genetic algorithm finds the optimum forcing conditions with a good convergence rate, the best control design variables being in agreement with the literature that uses other types of
control devices than plasma. Indeed, the minimum reattaching position is achieved by forcing the flow at the shear layer mode where a large spreading rate is obtained by increasing the periodicity of the vortex street and by enhancing the vortex pairing phenomena. At the best forcing conditions, the mean flow reattachment is reduced by 20%. This article, with its experiment-based approach, demonstrates the robustness of a single-objective multi-design optimization method, and its feasibility for wind tunnel experiments.Postprint (published version
Experimental optimization by genetic algorithm for flow separation control with surface plasma actuator
Postprint (published version
THE IMPACT OF STORAGE CONDITIONS ON THE FOREST BIOMASS QUALITY FOR BIOFUELS PRODUCTION
Biomass quality is an essential parameter for the production of biofuels both by thermal ways (gasification, pyrolysis, torrefaction, etc) or biochemical ways (enzymatic hydrolysis and yeast saccharification). Storage is one of the most important parameters to be taken in account in the logistics chains of biomass supply for biofuel conversion sites. Morever, some benefits in terms of biomass quality can be obtained by storing biomass prior transportation or usage. In this case, storage can be considered as a pre-treatment of biomass for biofuel production.
In this project, we have studied the evolution of biomass quality of different wooden resources (softwoods and hardwoods; short/very-short rotation coppices and residues of forest exploitation) stored under different conditions : seasons (spring/summer or autumn/winter), sites (forest roadside and storage platforms; uncovered and covered; under water sprinkling). Two locations were also tested, one in Bordeaux area (southwest of France) and the second in Dijon area (northeast of France). Different piles of approximately 10 m3 (2.5 to 3.5 tons of wood chips) were constituted for each modality. Samples were taken from two different levels of the piles at different intervals of storage (0 to 6 months).
The following biomass quality parameters were followed : moisture content, elemental (C, H, O, N, S, Cl) and chemical (extractives, lignin, polysaccharides – cellulose and hemicelluloses, C5 and C6 sugars contents) composition; heating value; ash content, fusibility behaviour and composition.
The results obtained indicated that the conditions of storage strongly influence the biomass quality, especially for the thermal conversion. The type of initial raw material (softwoods or hardwoods / short/very-short rotation coppices and residues of forest exploitation) are also of major importance, especially if the biomass material is stored with or without leaves. In that way, the season aspect becomes very important. Water sprinkling is an interesting way to remove certain compounds, such ash constituents or extractives, partially responsible for tar formation. On the other way, in this case a compulsory drying step is needed and a careful energy balance is needed in order to evaluate the pertinence or not of this technology. Concerning the biochemical conversion, no major differences were observed for the mono/polysaccharides contents. However, the removal of certain elements/substances could impact the enzymatic hydrolysis and fermentation for bioethanol production
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