1,135 research outputs found

    Wet air oxidation for industrial wastewater and sludge treatment: first results of a new research program in Quebec

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    Introduction Sub-critical water technologies, in particular wet air oxidation (WAO), have been developing across Europe in recent decades. This process is now used at the industrial scale for the effective treatment of wet organic material, mainly sludge from wastewater treatment plants (WWTP), and is done with energy self-sufficiency [1, 2]. In WAO, hot pressurised water (200-350 ˚C, 30-200 bars) is enriched with oxygen or air to initiate exothermic oxidation of organic material, mostly into CO2 and H2O. Since the operating temperature is much lower than typical incineration, no gaseous emissions of NOX, dioxins or furans are generated. Water is being kept in a liquid state due to high pressure, avoiding energy losses by vaporisation. These characteristics allow WAO to be a competitive and environmental friendly process for a variety of wet organic wastes and chemical effluents. However, WAO is still non-existent in the province of Quebec (Canada) and unknown to industries. In 2014, Centre de transfert technologique en Ă©cologie industrielle (CTTÉI), an applied research center in industrial ecology, acquired a WAO laboratory unit and launched the first research program in this field in the province of Quebec. This program, financed by NSERC (Natural Sciences and Engineering Research Council of Canada), Produits Chimiques Magnus and the City of Sorel-Tracy, aims to study the potential of this technology on various industrial wastes in Quebec and facilitate its transfer to industries. CTTÉI is also supported by European partners Innovation Fluides Supercritiques (IFS) and Aix-Marseille University. Please click Additional Files below to see the full abstract

    Displacement damage effects due to neutron and proton irradiations on CMOS image sensors manufactured in deep submicron technology

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    Displacement damage effects due to proton and neutron irradiations of CMOS image sensors dedicated to imaging are presented through the analysis of the dark current behavior in pixel arrays and isolated photodiodes. The mean dark current increase and the dark current nonuniformity are investigated. Dark current histogram observations are compared to damage energy distributions based on GEANT 4 calculations. We also discuss, through annealing analysis, which defects could be responsible for the dark current in CMOS image sensors

    Similarities Between Proton and Neutron Induced Dark Current Distribution in CMOS Image Sensors

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    Several CMOS image sensors were exposed to neutron or proton beams (displacement damage dose range from 4 TeV/g to 1825 TeV/g) and their radiation-induced dark current distributions are compared. It appears that for a given displacement damage dose, the hot pixel tail distributions are very similar, if normalized properly. This behavior is observed on all the tested CIS designs (4 designs, 2 technologies) and all the tested particles (protons from 50 MeV to 500 MeV and neutrons from 14 MeV to 22 MeV). Thanks to this result, all the dark current distribution presented in this paper can be fitted by a simple model with a unique set of two factors (not varying from one experimental condition to another). The proposed normalization method of the dark current histogram can be used to compare any dark current distribution to the distributions observed in this work. This paper suggests that this model could be applied to other devices and/or irradiation conditions

    Droits à produire transférables : Le marché des concessions conchylicoles et ses effets non désirés

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    Cet article propose une analyse de l'évolution du systÚme d'accÚs au foncier conchylicole en France ainsi qu'une étude de son fonctionnement actuel. Il traite la question de la répartition des moyens de production dans un secteur dominé par le modÚle de l'exploitation familiale et ayant vocation à maintenir une base sociale créatrice d'emplois dans certaines zones d'activité du littoral. Le régime d'accÚs au foncier conchylicole s'apparente à un systÚme de droits à produire transférables. Cependant, le développement spontané du marché des concessions conchylicoles dans un contexte de faible intervention de l'administration provoque des effets non désirés dont la manifestation est ici vérifiée empiriquement, sur données quantitatives et qualitatives. La discussion finale porte sur la recherche d'outils de régulation et d'indicateurs économiques pour un meilleur fonctionnement du marché des concessions.Foncier, Conchyliculture, Droits à produire, Répartition, Encadrement du marché

    Influence of displacement damage dose on dark current distributions of irradiated CMOS image sensors

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    Dark current increase distributions due to displacement damages are modeled using displacement damage dose concept. Several CMOS image sensors have been exposed to neutrons or protons and we have characterized their degradation in terms of dark current increase. We have been able to extract a set of two factors from the experimental dark current increase distributions. These factors are used to predict and build dark current increase distribution and leads to a better understanding of displacement damage effects on CMOS image sensors

    Banc de caractérisation pour lentilles panoramiques

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    Les particularitĂ©s des lentilles panoramiques font de leur caractĂ©risation un dĂ©fi. Pour les applications de vision, une connaissance de la distorsion est essentielle pour produire des vues naturelles. Aussi, toutes les directions Ă©tant importantes, la qualitĂ© de l'image doit ĂȘtre uniforme sur tout le champ de vue. Nous avons donc dĂ©veloppĂ© un banc de caractĂ©risation pour lentilles panoramiques. Avec des cibles rĂ©fĂ©rencĂ©es, nous avons obtenu avec rapiditĂ© et facilitĂ© les profils de distorsion, ce qui a permis de calculer la rĂ©solution instantanĂ©e linĂ©aire sur tout le champ de vue. Également, des cibles inclinĂ©es ont Ă©tĂ© utilisĂ©es pour dĂ©terminer la frĂ©quence spatiale oĂč la MTF est de 50% en fonction de l'angle dans le champ de vue. À l'aide de deux camĂ©ras, nous avons testĂ© deux lentilles panomorphes et deux lentilles fisheyes pour lesquelles nous avons calculĂ© la rĂ©solution instantanĂ©e et les courbes de MTF et comparĂ© certains rĂ©sultats Ă  des simulations

    Paire stĂ©rĂ©oscopique Panomorphe pour la reconstruction 3D d'objets d'intĂ©rĂȘt dans une scĂšne

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    Il existe dĂ©sormais une grande variĂ©tĂ© de lentilles panoramiques disponibles sur le marchĂ© dont certaines prĂ©sentant des caractĂ©ristiques Ă©tonnantes. Faisant partie de cette derniĂšre catĂ©gorie, les lentilles Panomorphes sont des lentilles panoramiques anamorphiques dont le profil de distorsion est fortement non-uniforme, ce qui cause la prĂ©sence de zones de grandissement augmentĂ© dans le champ de vue. Dans un contexte de robotique mobile, ces particularitĂ©s peuvent ĂȘtre exploitĂ©es dans des systĂšmes stĂ©rĂ©oscopiques pour la reconstruction 3D d’objets d’intĂ©rĂȘt qui permettent Ă  la fois une bonne connaissance de l’environnement, mais Ă©galement l’accĂšs Ă  des dĂ©tails plus fins en raison des zones de grandissement augmentĂ©. Cependant, Ă  cause de leur complexitĂ©, ces lentilles sont difficiles Ă  calibrer et, Ă  notre connaissance, aucune Ă©tude n’a rĂ©ellement Ă©tĂ© menĂ©e Ă  ce propos. L’objectif principal de cette thĂšse est la conception, l’élaboration et l’évaluation des performances de systĂšmes stĂ©rĂ©oscopiques Panomorphes. Le calibrage a Ă©tĂ© effectuĂ© Ă  l’aide d’une technique Ă©tablie utilisant des cibles planes et d’une boĂźte Ă  outils de calibrage dont l’usage est rĂ©pandu. De plus, des techniques mathĂ©matiques nouvelles visant Ă  rĂ©tablir la symĂ©trie de rĂ©volution dans l’image (cercle) et Ă  uniformiser la longueur focale (cercle uniforme) ont Ă©tĂ© dĂ©veloppĂ©es pour voir s’il Ă©tait possible d’ainsi faciliter le calibrage. Dans un premier temps, le champ de vue a Ă©tĂ© divisĂ© en zones Ă  l’intĂ©rieur desquelles la longueur focale instantanĂ©e varie peu et le calibrage a Ă©tĂ© effectuĂ© pour chacune d’entre elles. Puis, le calibrage gĂ©nĂ©ral des systĂšmes a aussi Ă©tĂ© rĂ©alisĂ© pour tout le champ de vue simultanĂ©ment. Les rĂ©sultats ont montrĂ© que la technique de calibrage par zone ne produit pas de gain significatif quant Ă  la qualitĂ© des reconstructions 3D d’objet d’intĂ©rĂȘt par rapport au calibrage gĂ©nĂ©ral. Cependant, l’étude de cette nouvelle approche a permis de rĂ©aliser une Ă©valuation des performances des systĂšmes stĂ©rĂ©oscopiques Panomorphes sur tout le champ de vue et de montrer qu’il est possible d’effectuer des reconstructions 3D de qualitĂ© dans toutes les zones. De plus, la technique mathĂ©matique du cercle a produit des rĂ©sultats de reconstructions 3D en gĂ©nĂ©ral Ă©quivalents Ă  l’utilisation des coordonnĂ©es originales. Puisqu’il existe des outils de calibrage qui, contrairement Ă  celui utilisĂ© dans ce travail, ne disposent que d’un seul degrĂ© de libertĂ© sur la longueur focale, cette technique pourrait rendre possible le calibrage de lentilles Panomorphes Ă  l’aide de ceux-ci. Finalement, certaines conclusions ont pu ĂȘtre dĂ©gagĂ©es quant aux facteurs dĂ©terminants influençant la qualitĂ© de la reconstruction 3D Ă  l’aide de systĂšmes stĂ©rĂ©oscopiques Panomorphes et aux caractĂ©ristiques Ă  privilĂ©gier dans le choix des lentilles. La difficultĂ© Ă  calibrer les optiques Panomorphes en laboratoire a menĂ© Ă  l’élaboration d’une technique de calibrage virtuel utilisant un logiciel de conception optique et une boĂźte Ă  outils de calibrage. Cette approche a permis d’effectuer des simulations en lien avec l’impact des conditions d’opĂ©ration sur les paramĂštres de calibrage et avec l’effet des conditions de calibrage sur la qualitĂ© de la reconstruction. Des expĂ©rimentations de ce type sont pratiquement impossibles Ă  rĂ©aliser en laboratoire mais reprĂ©sentent un intĂ©rĂȘt certain pour les utilisateurs. Le calibrage virtuel d’une lentille traditionnelle a aussi montrĂ© que l’erreur de reprojection moyenne, couramment utilisĂ©e comme façon d’évaluer la qualitĂ© d’un calibrage, n’est pas nĂ©cessairement un indicateur fiable de la qualitĂ© de la reconstruction 3D. Il est alors nĂ©cessaire de disposer de donnĂ©es supplĂ©mentaires pour juger adĂ©quatement de la qualitĂ© d’un calibrage.A wide variety of panoramic lenses are available on the market. Exhibiting interesting characteristics, the Panomorph lens is a panoramic anamorphic optical system. Its highly non-uniform distortion profile creates areas of enhanced magnification across the field of view. For mobile robotic applications, a stereoscopic system for 3D reconstruction of objects of interest could greatly benefit from the unique features of these special lenses. Such a stereoscopic system would provide general information describing the environment surrounding its navigation. Moreover, the areas of enhanced magnification give access to smaller details. However, the downfall is that Panomorph lenses are difficult to calibrate, and this is the main reason why no research has been carried out on this topic. The main goal of this thesis is the design and development of Panomorph stereoscopic systems as well as the evaluation of their performance. The calibration of the lenses was performed using plane targets and a well-established calibration toolbox. In addition, new mathematical techniques aiming to restore the symmetry of revolution in the image and to make the focal length uniform over the field of view were developed to simplify the calibration process. First, the field of view was divided into zones exhibiting a small variation of the focal length and the calibration was performed for each zone. Then, the general calibration was performed for the entire field of view. The results showed that the calibration of each zone does not lead to a better 3D reconstruction than the general calibration method. However, this new approach allowed a study of the quality of the reconstruction over the entire field of view. Indeed, it showed that is it possible to achieve good reconstruction for all the zones of the field of view. In addition, the results for the mathematical techniques used to restore the symmetry of revolution were similar to the results obtained with the original data. These techniques could therefore be used to calibrate Panomorph lenses with calibration toolboxes that do not have two degrees of freedom relating to the focal length. The study of the performance of stereoscopic Panomorph systems also highlighted important factors that could influence the choice of lenses and configuration for similar systems. The challenge met during the calibration of Panomorph lenses led to the development of a virtual calibration technique that used an optical design software and a calibration toolbox. With this technique, simulations reproducing the operating conditions were made to evaluate their impact on the calibration parameters. The quality of 3D reconstruction of a volume was also evaluated for various calibration conditions. Similar experiments would be extremely tedious to perform in the laboratory but the results are quite meaningful for the user. The virtual calibration of a traditional lens also showed that the mean reprojection error, often used to judge the quality of the calibration process, does not represent the quality of the 3D reconstruction. It is then essential to have access to more information in order to asses the quality of a lens calibration
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