Using disparity for quality assessment of stereoscopic images

International audience3DTV has been widely studied these last years from a technical point of view but the related quality evaluations does not follow this enthusiasm. This article reviews the quality assessment for 3DTV. Compared to 2D quality measure, the third dimension adds several new problems and quality assessment becomes a complex issue. Nevertheless, efforts made for 2D content quality estimation can be used for an extension to 3D. In this paper we propose a first attempt to adapt such 2D metrics to 3D content and add the contribution of a measure of the distortion on the disparity map for stereoscopic image pairs. This 3D metric performances has been evaluated with subjective tests

Subjective quality assessment of error concealment strategies for 3DTV in the presence of asymmetric transmission errors

International audienceThe transmission of 3DTV sequences over packet based networks may result in degradations of the video quality due to packet loss. In the conventional 2D case, several different strategies are known for extrapolating the missing information and thus concealing the error. In 3D however, the residual error after concealment of one view might leads to binocular rivalry with the correctly received second view. In this paper, three simple alternatives are presented: frame freezing, a reduced playback speed, and displaying only a single view for both eyes, thus effectively switching to 2D presentation. In a subjective experiment the performance in terms of quality of experience of the three methods is evaluated for different packet loss scenarios. Error-free encoded videos at different bit rates have been included as anchor conditions. The subjective experiment method contains special precautions for measuring the Quality of Experience (QoE) for 3D content and also contains an indicator for visual discomfort. The results indicate that switching to 2D is currently the best choice but difficulties with visual discomfort should be expected even for this method

NAMA3DS1-COSPAD1: Subjective video quality assessment database on coding conditions introducing freely available high quality 3D stereoscopic sequences

Research in stereoscopic 3D coding, transmission and subjective assessment methodology depends largely on the availability of source content that can be used in cross-lab evaluations. While several studies have already been presented using proprietary content, comparisons between the studies are difficult since discrepant contents are used. Therefore in this paper, a freely available dataset of high quality Full-HD stereoscopic sequences shot with a semiprofessional 3D camera is introduced in detail. The content was designed to be suited for usage in a wide variety of applications, including high quality studies. A set of depth maps was calculated from the stereoscopic pair. As an application example, a subjective assessment has been performed using coding and spatial degradations. The Absolute Category Rating with Hidden Reference method was used. The observers were instructed to vote on video quality only. Results of this experiment are also freely available and will be presented in this paper as a first step towards objective video quality measurement for 3DTV

Contribution to the modeling and the ageing study of electrolytic aluminium capacitors dedicated to high temperature applications

Ce mémoire est consacré à la modélisation des condensateurs électrolytiques aluminium dédiés à des applications à hautes températures ainsi qu’à la compréhension de leur vieillissement lors d’utilisations réalistes. En effet, dans le cas d’onduleur de traction de véhicule électrique, les sollicitations, notamment en température, peuvent être parfois très variables. Or, il se trouve que pour ce type d’applications, ces derniers sont la plupart du temps de type électrolytiques aluminium, technologie étant parmi les plus fragiles. Par conséquent, ce manuscrit propose tout d’abord une nouvelle modélisation électrique s’appuyant des phénomènes de diffusion permettant d’obtenir une représentation très précise de l’impédance de ces condensateurs. Compte-tenu de leur forte dépendance en température, la modélisation thermique couplée au modèle électrique est également traitée. Le but premier est de développer un outil permettant d’estimer précisément les pertes à chaque instant pour permettre au contrôleur d’ajuster la température de ce dernier par une modification de la stratégie MLI. Une méthode d’identification en ligne est alors proposée par l’utilisation de filtres de Kalman conjoints avec de très bons résultats obtenus en simulation. Le dimensionnement ainsi que la création d’un banc de cyclage accéléré est développé et une comparaison du vieillissement obtenu après 12 000 heures entre des composants cyclés thermiquement et d’autres non cyclés est donnée. Les résultats montrent une très bonne tenue dans le temps des condensateurs étudiés que ce soit au niveau de l’impédance ou bien visuellement avec néanmoins un impact du cyclage thermique non négligeableThis thesis is devoted to the modeling of aluminum electrolytic capacitors dedicatedto high temperatures. The purpose is also to understand their ageing while submitted to realistic use. Indeed, in the case of electric vehicle traction inverter, solicitations like temperature can vary a lot. This type of stress has already been studied for active components, but not yet on passive ones such as decoupling capacitors. However, it turns out that for this kind of application, they are most of the time aluminum electrolytic capacitors which is among the weakest technology. Consequently, this manuscript proposes at first a new electric model based on a diffusion phenomena which leads to a very accurate impedance description. It permits also a better understanding of the physical phenomena involved in these components. Because of their important temperature dependence, thermal modeling coupled to the electric model is also discussed. The very first purpose is to develop a tool that is able to estimate losses accurately at every moment. Thanks to it, the controller could so change the PWM strategy in order to act on the temperature. An online identification method is then proposed with the use of joint Kalman filters which led to very good results in simulation. The design and the creation of an accelerated cycling bench is developed and comparisons about the ageing obtained after 12 000 hours between thermally cycled components and others non-cycled are given. Results show a very good stability over time of the studied capacitors (PEG225MF470Q Kemet©) either on the impedance or visually. Nevertheless a significant impact can be observed on the cycled ones

Ageing test bench for electrolytic capacitors in the context of electric vehicles — Electrical and thermal modeling from real-time identification viewpoint

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A methodology for studying aluminum electrolytic capacitors wear-out in automotive cases

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Advanced Electric Model of Aluminum Electrolytic Capacitor with Diffusive Element

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Impact of thermal stress on the ageing behaviour of aluminum electrolytic capacitors for automotive applications

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