Conflicto lingüístico y separatismo en Canadá

Este artículo analiza la historia del conflicto lingüístico entre el pueblo francófono y el pueblo anglófono dentro de la doble realidad cultural de Canadá y muestra el imperialismo inglés hacia el pueblo québécois a lo largo de su historia. Con respecto a la posible independencia de Quebec, el artículo habla a favor de un Canadá unido sin miedo de ofender a los québécois. Y se desprenden dos conclusiones: una emocional y otra racional. La emocional nos recuerda las palabras del profesor Russell: “Amo a Canadá”, “Canadá es un gran país”. En la racional se nos recuerda las trágicas consecuencias de la desintegración de imperios y naciones. Y se afirma que los québécois no van a vivir mejor si se separan del resto de Canadá. Lo que se necesita verdaderamente es un federalismo más interactivo y más económicamente independiente de los Estados Unidos. This article examines the history of the linguistic conflict between Francophones and Anglophones within the double cultural reality of Canada and shows the English imperialism towards the Quebecois throughout their history. With regard to the possible independence of Quebec, the article discusses Canadian unity without fear of offending the Quebecois. Two conclusions stand out: one emotional and another rational. The emotional one reminds us of Professor Russell’s words: “I love Canada”, “Canada is a great place”. The rational conclusion reminds us of the tragic consequences of the disintegration of empires and nations. It is asserted that the Quebecois will not live better if they separate from the rest of Canada. What the country really needs is a federalism, more interactive and more economically independent from the United States

Reinforced sol–gel thermal barrier coatings and their cyclic oxidation life

Cyclic oxidation life enhancement of sol–gel thermal barrier coatings is obtained via the reinforcement of the controlled micro-crack network that forms during the initial sintering of the deposit. Two different sol–gel methods are used to fill in the process-induced cracks, namely dipcoating and spray-coating. Filling parameters, for instance the number of passes or the viscosity of the sol are adjusted, using various techniques such as profilometry and microstructural analysis, to optimise crack filling. Cyclic oxidation tests are implemented at both 1100C and 1150C to investigate the efficiency of the various reinforcement procedures developed and address the influence of the specific microstructure on the oxidation behaviour

Temperature correction of radiometric and geometric models for an uncooled CCD camera in the near infrared

International audienceThis paper presents radiometric and geometric models for both temperature and displacement noncontact measurements using an uncooled charge-coupled device (CCD) video camera. Such techniques (''one sensor-two measures'') represent an interest in many industrial low cost applications and scientific domains. To benefit from both measurements, we have to use the camera's spectral response in the near infrared spectral band from 0.75 to 1.1 mum. In this spectral band, the temperature variations of an uncooled CCD camera are taken into account in the radiometric and geometric models. By using physical models for CCD camera, we quantify detector's quantum efficiency, sensor noise and spatial resolution as a function of the wavelength and of the detector temperature. These models are confirmed by experimental results of calibration with a low cost uncooled camera based on a Sony detector and operating over the detector temperature range of -30 to -50degrees

Identification of the temperature dependent relation between thermo-optical properties and morphology of semi-crystalline thermoplastics for thermoforming process

International audienceHeating stage of the thermoforming of thermoplastics are critical as it has great effect on their formability under forming and therefore product quality. As radiation heat transfer is widely used for the heating of thermoplastic preforms, physical background of the radiation heating of bulk thermoplastic polymers has to be understood well for an accurate prediction on their temperature profile. In the past, many numerical approaches were developed based on thermo-optical characteristics of thermoplastics whereas little attention was given to the relation between their microstructure and thermo-optical parameters. Considering semi-crystalline thermoplastics the effect of microcrystalline structure is key to identify the thermo-optical properties and develop an accurate numerical radiative heat transfer model for optimization of thermoforming process. Previous studies in literature showed that there is a strong coupling between microstructure of semi-crystalline thermoplastics and their thermo-optical properties in the near-infrared spectral region. In the present work, the relation between thermo-optical characteristics and microstructure of polyolefin-based (PO) polymer was studied considering the change in its morphology at various temperatures. The optical characteristics of the PO were experimentally analyzed under heating conditions using an in-house developed device that is built using a Fourier Transform Infrared spectroscopy, integrating sphere and heating plate. Thanks to the analyses, the changes in the thermo-optical properties of the PO were correlated to its varying morphology under increasing temperature. As semi-crystalline thermoplastics are heated up to melting temperature to soften enough for successful forming process, their microcrystalline structure may show variation above glass transition temperature and this temperature-dependent relation cannot be neglected for building an accurate numerical model for infrared heating assisted thermoforming

Assessment of the single-mixture gas assumption for the correlated K-distribution fictitious gas method in H2O-CO2-CO mixture at high temperature

International audienceThis paper deals with the comparison of spectral narrow band models based on the correlated-K (CK) approach in the specific area of remote sensing of plume signatures. The CK models chosen may or may not include the fictitious gas (FG) idea and the single-mixture-gas assumption (SMG). The accuracy of the CK and the CK-SMG as well as the CKFG and CKFG-SMG models are compared, and the influence of the SMG assumption is inferred. The errors induced by each model are compared in a sensitivity study involving the plume thickness and the atmospheric path length as parameters. This study is conducted in two remote-sensing situations with different absolute pressures at sea level (10(5) Pa) and at high altitude (16.6 km, 10(4) Pa). The comparisons are done on the basis of the error obtained for the integrated intensity while leaving a line of sight that is computed in three common spectral bands: 2000-2500 cm(-1), 3450-3850 cm(-1) and 3850-4150 cm(-1). In most situations, the SMG assumption induces negligible differences. Furthermore, compared to the CKFG model, the CKFG-SMG model results In a reduction of the computational time by a factor of 2

Infra-red sheet heating assisted Superplastic Forming

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Contribution à l'étude de l'effet mirage (application aux mesures dimensionnelle et thermique par caméras visible proche infrarouge)

L Institut Clément Ader Albi (ICAA) et l Institut von Karman (IVK) mènent depuis un certain nombre d années des travaux sur la radiométrie IR dans le but de faire de la thermographie quantitative (mesure de température vraie sans contact). Ces travaux ont permis d explorer les potentialités de plusieurs bandes spectrales : 8-12 m, 3-5 m et plus récemment la bande 0,75-1,7 m (proche IR) à l aide de caméras CCD (Si) ou VisGaAs. Les travaux effectués dans ce domaine spectral ont permis de mettre en évidence un certains nombre de perturbations renforcées par les hautes températures(T>800C). Cette thèse aborde de façon détaillée le traitement d un certain nombre de grandeurs d influence liées à la mesure de différents paramètres dans le domaine du proche IR mais également étendus aux domaines du visible et de l IR. La première de ces grandeurs est l émissivité dont le traitement a déjà été abordé par d autres études. La seconde grandeur d influence touche plus particulièrement à la localisation des points chauds sur l objet et la distorsion du champ de température apportée par les effets convectifs présents autour d un objet à haute température, elle est le coeur de cette thèse. En effet, lorsqu une pièce chaude se trouve dans un milieu ambiant beaucoup plus froid, il se crée un gradient de température et donc d indice de réfraction autour de la pièce. Or les caméras travaillant dans les différentes bandes spectrales vont être plus ou moins sensibles à ces variations d indices de réfraction du fait de la dépendance de l indice optique avec la longueur d onde et de la résolution spatiale de la caméra utilisée. Ce phénomène, appelé effet mirage, entraîne inévitablement une déformation des informations spatiales reçues par la caméra. Le but de cette thèse a donc été d estimer et de proposer une première approche pour corriger l erreur faite sur la mesure de température et/ou de déformation faites par caméras sur des pièces chaudes. La démarche générale du travail a donc été dans un premier temps de calculer le champ de température autour de l objet considéré en se ramenant d abord à des cas simplifiés. On en a déduit alors le champ de réfraction entraînant une déformation de l objet, en faisant le lien entre T et n. Cette étape correspond à l approche numérique de notre étude. Cette étape numérique a été réalisé à l aide d un outil de lancer de rayons développée à l ICA. L approche expérimentale a consisté à l utilisation de méthodes telle que la BOS (Background Oriented Schlieren), la PIV, la srtioscopie afin de déduire le champ de déplacements provoqué par le panache convectif. Ces résultats ont été comparés à la méthode numérique et ceci pour différentes longueurs d ondes. Enfin, une stratégie de correction d images perturbées a été abordé à l aide de méthodes telles que la transformée d Abel inverse afin de remonter au champ d indice de réfraction 2D axisymétrique à partir d une déformation plane.The Clement Ader Institute of Albi and the von Karman Institute follow since numerous years works about IR radiometry with the aim to do quantitative thermography (true temperature measurement without contact). These works allowed to explore potentiality several spectral bands : 8-12 m, 3-5 m and recently the 0.75-1.7 m band (near IR) with the help of CCD camera (Si) or VisGaAs camera. Studies done in this specific domain have underlined some perturbations emphasized at high-temperature(T>800C). This work has to deal in details with the treatment of parameters playing a role in camera measurements. The first of these parameters is the emissivity, this treatment is made in another thesis. The second parameter affects particularly the hot spot location and the spatial distortion. This perturbation comes from convective effect present around every hot objects.The purpose of this thesis is to analyze this effect and to correct it. Indeed, when a hot object is in a colder surrounding media, a temperature gradient is shaped around the object and thus a refractive index gradient too. This phenomena brings inevitably distortions of the spatial information received by the camera. The goal of this work will be to estimate and correct error made on temperature and/or distortion measurement by CCD or VisGaAs camera on hot object.We chose to focus our work on the convective plume created by a hot horizontal disk. This study will be done with an experimental and a numerical approach. For the numerical approach, a raytracing code has been developed in order to obtain numerically the displacement due to the light deviation occurring in the perturbation. The input data of the code is the refractive index of the hot air present around the object. This refractive index, depending on the wavelength, can be found directly from the temperature thanks to the Gladstone-Dale law. The temperature is given by a CFD software such as FLUENT. Experimentally, we will use the Background Oriented Schlieren (BOS) method in order to retrieve the displacement. We can see that the displacement can reach 4 pixels in the plume (corresponding to 1mm in this case). This perturbation has been studied for several spectral bands (visible, near infrared, infrared). Finally, some solutions of correction are given, like using the inverse Abel Transform in order to retrieve from the 2D displacement, a 3D (axisymmetric) refractive index field that we will implement in the ray-tracing code and consequently predict the displacement for any kind of wavelength or distance (distance between the camera and the object).TOULOUSE-INP (315552154) / SudocSudocFranceF

Characterisation of thermal barrier sensor coatings synthesised by sol–gel route

Further improvements in the efficiency of gas turbines are recognised to come from increases in turbine entry temperatures. Accurate temperature measurements are crucial to achieve these increases whilst maintaining reliability and economic component life. The combination of phosphor thermometry and thermal barrier coating (TBC) technology has led to the development of functional temperature sensor coatings which have several advantages over conventional temperature measurement techniques. Developments in sol–gel processing indicate that this method could be used for the production, or particularly, the repair of TBCs in the future. This paper demonstrates, for the first time, that sol–gel processing can be used to make sensor TBCs. The optimum concentration of SmO1.5 was 2 wt.% in YSZ to achieve the brightest phosphorescence emission. Above this concentration the overall intensity of the emission reduces and the transitions from 4F3/2 were suppressed. Furthermore, a similar suppression of these transitions was observed when the product of the sol–gel was heat treated to 1100 ◦C. This was concluded to be due to a higher degree of crystallinity allowing a greater interaction between the dopant ions. The dependence of the phosphorescence spectrum on heat treatment temperature provides the first indication that YSZ produced through sol–gel could be used to detect historic temperatures. An evaluation of the subsurface measurement and temperature capabilities has shown that the phosphorescence can be detected from relatively thin layers, 20 µm, even under 50 µm of undoped YSZ coating. Although the temperature detection range, 400–700 ◦C, is too low for advanced TBCs the material could be used in low temperature regimes or for health monitoring purposes

Processing, repairing and cyclic oxidation behaviour of sol–gel thermal barrier coatings

Sol–gel Thermal Barriers Coatings (TBCs) are manufactured using the dip-coating technique optimised in terms of process parameters including sol formulation, rate of withdrawing and heat treatment. The specific mechanisms of sol–gel TBCs, deposited on either NiAl or NiPtAl bond-coated superalloy substrates, are described. The possibility to reinforce and stabilise the crack network formed during the heat treatment or the first oxidation cycles using supplementary dip-coatings and appropriate process parameters is investigated. It is shown that implementing this technique that can be further regarded as an attractive way for repairing TBCs, significantly improves the cyclic oxidation behaviour of the multi-materials systems

Experimental study and numerical simulation of preform or sheet exposed to infrared radiative heating

International conference on Advances in Materials and Processing Technology, DUBLIN, IRELAND, AUG 03-06, 1999International audienceThermoplastic processing like the injection stretch blow moulding and thermoforming processes provide the heating stage with infrared oven. This is a critical stage of the process, as the final part thickness is strongly dependent on the preform or sheet temperature distribution prior to forming. Optimisation of the infrared oven is therefore necessary. Experiments have been conducted in order to characterise the heat source of the infrared emitter and the interaction between the heaters and a semi-transparent PET sheet. An 880 LW AGEMA infrared camera has been used to determine the surface distribution of the transmitted heat flux by measuring the temperature distribution on the surface of the thermoplastic sheet. In addition, numerical simulations of the temperature distribution using control-volume method have been carried out and compared with experimental data