Teses / dissertações sobre o tema "Indice de qualité du signal"
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Cherif, Safa. "Effective signal processing methods for robust respiratory rate estimation from photoplethysmography signal". Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2018. http://www.theses.fr/2018IMTA0094/document.
Texto completo da fonteOne promising area of research in clinical routine involves using photoplethysmography (PPG) for monitoring respiratory activities. PPG is an optical signal acquired from oximeters, whose principal use consists in measuring oxygen saturation. Despite its simplicity of use, the deployment of this technique is still limited because of the signal sensitivity to distortions and the non-reproducibility between subjects, but also for the same subject, due to age and health conditions. The main aim of this work is to develop robust and universal methods for estimating accurate respiratory rate regardless of the intra- and inter-individual variability that affects PPG features. For this purpose, firstly, an adaptive artefact detection method based on template matching and decision by Random Distortion Testing is introduced for detecting PPG pulses with artefacts. Secondly, an analysis of several spectral methods for Respiratory Rate (RR) estimation on two different databases, with different age ranges and different respiratory modes, is proposed. Thirdly, a Spectral Respiratory Quality Index (SRQI) is attributed to respiratory rate estimates, in order that the clinician may select only RR values with a large confidence scale. Promising results are found for two different databases
Khreis, Soumaya. "Fusion par lisseur de Kalman pour l’estimation de la fréquence respiratoire à partir de l’électrocardiogramme ou du photoplethysmogramme". Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S047/document.
Texto completo da fonteThe presented work in this dissertation concerns the development of approaches to estimate the breathing rate (BR) accurately from the electrocardiogram (ECG) and photoplethysmogram (PPG), to avoid wearing cumbersome and uncomfortable sensors for direct measurements. In fact, the respiration influences ECG and PPG signals. Several modulations are extracted to describe breathing cycles based on amplitude, frequency and baseline. However, it is difficult to determine the optimal combination to estimate the BR due to the noise and patient-dependency. Since few works have studied the quality of these modulations, we propose to study the quality of modulations using respiratory quality indices (RQI). To do so, we present two methods: the first automatically selects the modulations with the highest RQI for BR estimation, the second tracks the respiration signal using Kalman smoother. The obtained results show superior performance comparing to the methods in the literature. In addition, an extension of fusion approach is presented based on a multi-mode model. These proposed methods are tested on several datasets with different clinical contexts: monitoring post-operative care (where patients are immobile), daily physical activities and neonatal monitoring. The experimental results show that the RQIs coupled with a fusion algorithm increase the accuracy of the BR estimation from the derived modulations
Chehbani, Amel. "Etude et mise en œuvre d’un système communicant sans fil et sans radio pour la mesure de paramètres physiologiques des nouveau-nés". Electronic Thesis or Diss., Limoges, 2024. http://www.theses.fr/2024LIMO0009.
Texto completo da fonteThe weak immune systems in the elderly, newborns and preterm infants increase their susceptibility to cardiovascular disease and heart failure. Indeed, symptoms of cardiac pathology can be quite unusual and sporadic in this population. This requires continuous monitoring of cardiac activity by electrocardiogram (ECG), which enables early detection of abnormalities. Conventionally, ECG systems are wired, limiting continuous monitoring and patient comfort. Thanks to technology, portable and wireless ECG systems have also been developed, based mainly on efficient radio frequency (RF) technologies, which enable these users to be monitored regularly. However, security and privacy requirements, interference generation, potential harmful effects on patient health, spectrum congestion and energy efficiency are challenges for the massive deployment of RF technologies in healthcare scenarios. Instead of relying on the limitations of RF systems, this thesis focuses on an alternative solution based on optical wireless technologies that enable safe and environmentally-friendly communications. This solution consists of a monitoring system using an infrared link between a transmitter embedded in an ECG sensor placed on the user's body and receivers placed on the ceiling of the environment. In order to study the three monitoring contexts, the corresponding optical channel was simulated using a ray-tracing technique combined with the numerical Monte-Carlo method. Considering the specificities of the monitoring scenario, the population (age and mobility) and the modeled environment (transparent material of premature baby incubators), the static gain characterizing the channel was obtained. This gain was used in a chain developed to simulate ECG transmission in each context. The reliability of the proposed remote monitoring system is thus conditioned by the quality of the transmitted ECG signal. This has been assessed at application level using the Signal Quality Index (SQI) method, which consists in extracting spectral and statistical characteristics from the ECG. In addition, given its usefulness in monitoring the development of premature infants, heart rate variability (HRV) has also been analyzed by computing the temporal parameters that characterize RR intervals in an ECG. The main objective is to assess the impact of time-varying optical transmission performance on the quality of the received ECG signal, in order to design a less intrusive, reliable and cost-effective system for remote ECG signal monitoring. SQIs consist in extracting spectral and statistical characteristics from the ECG. In addition, given its usefulness in monitoring the development of premature infants, heart rate variability (HRV) was also analyzed by computing the temporal parameters that characterize RR intervals. The main objective is to assess the impact of optical transmission performance on ECG quality metrics. For this purpose, a general analysis approach was implemented to jointly study the evolution of (SQIs) and VFC temporal parameters at the application level as a function of classical metrics at the physical level, namely (SNR) and (BER). The results of this research showed the potential of using wireless optics in such medical contexts to provide a reliable and energy-efficient solution. Indeed, in all three cases investigated, ECG signals of sufficient quality for reliable diagnoses were obtained at moderate levels of transmitted optical power, which is important for a portable medical remote monitoring system
Ouzennou, Hakim. "Indice de qualité de station des pessières noires irrégulières". Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24648/24648.pdf.
Texto completo da fonteLinnemer, Laurent. "Publicité et signal de la qualité". Paris, EHESS, 1996. http://www.theses.fr/1996EHES0037.
Texto completo da fonteIn a context of an experience quality good, we reinforce the role of dissipative advertising as a signal of product quality by analysing a two period model. The conclusions of nelson (1974) are strengthened. Next, we widen this point of view, showing that other long term effects such as investment in capacity or learning by doing induce to the use of dissipative advertising. We extract the role of barrier of entry of advertising in merging the static model of quality signal and a model of limit pricing. Finally, we highlight that dissipative advertising is an efficient signal when the hidden characteristic is multidimensional
Novanda, Happy. "Monitoring of power quality indices and assessment of signal distortions in wind farms". Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/monitoring-of-power-quality-indices-and-assessment-of-signal-distortions-in-wind-farms(403a470c-279a-4b00-94dc-eaa2507dc579).html.
Texto completo da fonteStronach, Natalie. "Élaboration d'un indice global de qualité de l'environnement urbain pour la ville de Sherbrooke". Mémoire, Université de Sherbrooke, 2004. http://savoirs.usherbrooke.ca/handle/11143/2392.
Texto completo da fonteMontard, Nathalie. "Estimation de la qualité perceptuelle de signaux numériques audiovisuels : de la qualité à l'acceptabilité du service". Saint-Etienne, 2001. http://www.theses.fr/2002STET4009.
Texto completo da fonteThe development of digital technologies and multimedia landscape has led to the creation of several new services, a nex generation of terminals and new broadcasting conditions. These changes bring about new audio-visual monitoring techniques and re-open the whole question of the assessment of quality of service. . . [etc. ]
Burlacu, Radu. "Emission d'obligations convertibles : un signal riche sur la qualité de l'entreprise". Grenoble 2, 2000. http://www.theses.fr/2000GRE21050.
Texto completo da fonteBarrette, Valérie. "Élaboration d'un indice global de qualité de vie par intégration de données multisources cas de la Ville de Sherbrooke". Mémoire, Université de Sherbrooke, 2003. http://savoirs.usherbrooke.ca/handle/11143/2367.
Texto completo da fonteZhangh-Ge, Lu. "Modèles Numériques pour l'Évaluation Objective de la Qualité d'Images Médicales". Phd thesis, Université d'Angers, 2012. http://tel.archives-ouvertes.fr/tel-00995416.
Texto completo da fonteBriolle, Françoise. "Evaluation de la qualité sonore de casques d'écoute par simulation numérique des fonctions de transfert". Aix-Marseille 2, 1993. http://www.theses.fr/1993AIX22008.
Texto completo da fonteRuiz, Camacho Nuria. "Mise au point d'un système de bioindication de la qualité du sol base sur l'étude des peuplements de macroinvertebrés". Paris 6, 2004. http://www.theses.fr/2004PA066293.
Texto completo da fonteCony, Louis. "Élaboration et développement d’un indice de la qualité sanitaire de l’habitat : outil de quantification de la « favorabilité » à la santé". Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROS002.
Texto completo da fonteWithout lessening the importance of outdoor air quality (especially in areas with heavy road traffic or near industrial sites...) or transport (such as confined underground spaces) in people's exposure to air pollutants, considering the exposure of occupants to pollutants in their dwellings is essential since people spend around 80% of their time there. The first step of this work consisted in defining a reduced number of pollutants to be considered inside the dwellings through a prioritization process consisting in comparing the levels of exposure to the different pollutants in relation to their health reference values. The analysis of the existing single and multi-pollutant indices led to the definition of a new multi-pollutant index, called ULR-IAQ, which was used as the main indicator in the rest of the study. The second chapter was dedicated to the development of the numerical tool necessary to reproduce the various and varied situations that can be encountered in dwellings. The objective here was to reproduce the transport of pollutants from outdoor to indoor, indoor sources of pollutants as well as the main physical phenomena (pollutant transfers between the different rooms, variation in air relative humidity, deposition of particles, filtration...) for the evaluation of the concentration levels of the target pollutants defined in the previous chapter. Thus, a simulation environment combining energy, airflow and pollutant transport for multizone buildings has been developed by coupling TRNSYS and CONTAM software. Finally, an analysis of the elements impacting the IAQ of dwellings was developed in the last chapter. The goal here was not only to observe the influence of certain parameters but also to quantify and prioritize, through the ULR-IAQ index calculation, the pollutants, their sources, the systems as well as the actions that can be taken by the occupants to improve the IAQ of their dwellings
Zhang, Lu. "Modèles Numériques pour l'Évaluation Objective de la Qualité d'Images Médicales". Phd thesis, Université d'Angers, 2012. http://tel.archives-ouvertes.fr/tel-00782522.
Texto completo da fonteBorshchevskiy, Valentin. "L'obtention des données cristallographiques de qualité supérieure des états fonctionnels de la bactériorhodopsine". Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY007.
Texto completo da fonteThe synthesis of adenosine triphosphate (ATP) is a key event in the cell bioenergetics. ATP synthesis is only possible when a proton electrochemical potential gradient is present on the membranes of cell or organelle. This gradient is produced by enzyme-controlled redox or photochemical reactions. Bacteriorhodopsin (bR) is the simplest and most studied protein that converts light energy into electrochemical potential. Being transmembrane protein of Halobacterium salinarum it absorbs light photon and transfers a proton from the cytoplasmic to the extracellular space. Due to its availability of relatively large quantities, easy purification procedure and protein stability bR remains one of the most extensively studied membrane proteins during the past 40 years.Current state of investigated problems. To understand the molecular mechanism of bR functioning is necessary to know the structural changes caused by light absorption which accompany the protein working cycle and lead to the directional transport of the proton. It implies obtaining of X-ray structures of bR functional states with atomic resolution. Following this approach it is important to have highly ordered three-dimensional protein crystals on the one hand and effective methods of trapping protein molecules in intermediate states on the other one. Trapping procedures for bR intermediate states under cryogenic conditions have been developed previously. Crystals of the desired quality can be obtained by in meso crystallization where lipid bicontinuous mesophase is used for the crystallization of membrane proteins. The mechanism of in meso crystallization is currently poorly investigated. This situation greatly limits its potential applicability for membrane proteins. Despite its limitations in meso approach have recently made possible to obtain the ground and some intermediate states structures of bR. However, different scientific groups have published different X-ray models of the same bR intermediate states. The proposed by different authors mechanisms of proton transport are contradictory. The reasons for the lack of the consensus in intermediate structures remain unclear. The possible reasons for this contradiction which have been discussed in literature are: insufficient quality of diffraction data, merohedral twinning and radiation damage of protein crystals, as well as the generation of new protein states caused by X-ray illumination.The aim of the study was to sort out the reasons for contradictions in the field of X-ray crystallographic analysis of bR functional states and to find ways to overcome related problems. This implies several separate subgoals: study of merohedral twinning of bR crystals; study of X-ray-radiation-induced changes in bR structure; study of low-dose radiation-induced structural changes in bR structure. An additional goal of the work was to study a role of molecules of the in meso crystallization matrix in the stabilization of membrane protein crystals
Bernadet, Caroline. "Biodiversité des communautés de macroinvertébrés benthiques de la Martinique : conception d'un indice de qualité biologique des rivières et écologie fonctionnelle des bioindicateurs". Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2580/.
Texto completo da fonteThe implementation of the European Water Framework Directive (WFD) in 2000 led many European states to modify or create biomonitoring methods directed towards the achievement of a 'good ecological status' of surface waters, as well as their preservation and restoration. The Directive applies to overseas territories such as the West Indies, with the same objectives and deadlines as in continental Europe, despite a forty-year delay in the implementation of water policies in these tropical areas and little scientific attention paid to freshwater ecosystems. In particular, there was no tool bioassessment of the ecological quality of rivers adapted to tropical Caribbean island environments, while the regional fauna has been largely understudied in terms of ecology, biology and systematics. In this context, the main objective of this thesis was to design a biotic index to assess the ecological quality of rivers in Martinique, according to the criteria of the WFD. In parallel, the biodiversity and ecology of benthic macroinvertebrates inhabiting the French Antilles were studied. We first established an updated inventory of the benthic macroinvertebrate fauna of the French Antilles and quantified the ecological preferences of the dominant benthic macroinvertebrates at the microhabitat scale (substrates and current preferential rate) and at the regional scale along the altitudinal gradient. A biotypology of communities enabled us to bring out patterns in community structure in relation to environmental conditions. Finally, a stable isotope approach to food webs analysis provides new information on the trophic ecology of macroinvertebrate communities. Despite a poor species pool compared to the continent, the macroinvertebrate fauna of the French Antilles is one of the most diverse of the Lesser Antilles, and has a large number of endemic species. Only a few taxa show a narrow altitudinal range and strict microhabitat preferences. Despite this, this largely ubiquitous fauna shows clear distribution patterns along environmental gradients, geomorphological factors being the most significant controlling factors. Based on these distributions patterns and the identification of unimpacted reference stations, we created a multimetric index of biological quality of rivers measuring the deviation of community diversity from the reference conditions. This index takes into account the diversity and abundance of taxa, as well as some biological traits. Thus, it meets as much as far as possible the requirements of the WFD, given our current knowledge of the local fauna. Food webs show a generalized omnivory, so it is difficult to categorize taxa into functional groups or trophic guilds which would be useful to understand the ecological functioning of communities under natural and disturbed conditions. Future research should thus enhance fundamental knowledge on the biology and ecology of the regional fauna, and more broadly on the fauna of the Lesser Antilles
Barland, Rémi. "Évaluation objective sans référence de la qualité perçue : applications aux images et vidéos compressées". Nantes, 2007. http://www.theses.fr/2007NANT2028.
Texto completo da fonteThe conversion to the all-digital and the development of multimedia communications produce an ever-increasing flow of information. This massive increase in the quantity of data exchanged generates a progressive saturation of the transmission networks. To deal with this situation, the compression standards seek to exploit more and more the spatial and/or temporal correlation to reduce the bit rate. The reduction of the resulting information creates visual artefacts which can deteriorate the visual content of the scene and thus cause troubles for the end-user. In order to propose the best broadcasting service, the assessment of the perceived quality is then necessary. The subjective tests which represent the reference method to quantify the perception of distortions are expensive, difficult to implement and remain inappropriate for an on-line quality assessment. In this thesis, we are interested in the most used compression standards (image or video) and have designed no-reference quality metrics based on the exploitation of the most annoying visual artefacts, such as the blocking, blurring and ringing effects. The proposed approach is modular and adapts to the considered coder and to the required ratio between computational cost and performance. For a low complexity, the metric quantifies the distortions specific to the considered coder, only exploiting the properties of the image signal. To improve the performance, to the detriment of a certain complexity, this one integrates in addition, cognitive models simulating the mechanisms of the visual attention. The saliency maps generated are then used to refine the proposed distortion measures purely based on the image signal
Préault, Marina. "Sélection sexuelle et qualité individuelle chez le merle noir (Turdus merula)". Paris 6, 2003. http://www.theses.fr/2003PA066268.
Texto completo da fonteIrrera, Paolo. "Traitement d'images de radiographie à faible dose : Débruitage et rehaussement de contraste conjoints et détection automatique de points de repère anatomiques pour l'estimation de la qualité des images". Thesis, Paris, ENST, 2015. http://www.theses.fr/2015ENST0031/document.
Texto completo da fonteWe aim at reducing the ALARA (As Low As Reasonably Achievable) dose limits for images acquired with EOS full-body system by means of image processing techniques. Two complementary approaches are studied. First, we define a post-processing method that optimizes the trade-off between acquired image quality and X-ray dose. The Non-Local means filter is extended to restore EOS images. We then study how to combine it with a multi-scale contrast enhancement technique. The image quality for the diagnosis is optimized by defining non-parametric noise containment maps that limit the increase of noise depending on the amount of local redundant information captured by the filter. Secondly, we estimate exposure index (EI) values on EOS images which give an immediate feedback on image quality to help radiographers to verify the correct exposure level of the X-ray examination. We propose a landmark detection based approach that is more robust to potential outliers than existing methods as it exploits the redundancy of local estimates. Finally, the proposed joint denoising and contrast enhancement technique significantly increases the image quality with respect to an algorithm used in clinical routine. Robust image quality indicators can be automatically associated with clinical EOS images. Given the consistency of the measures assessed on preview images, these indices could be used to drive an exposure management system in charge of defining the optimal radiation exposure
Thomas, Marielle. "Biodétection en temps réel. Contribution à la réalisation d'un nouveau système de détection biologique précoce de la pollution des eaux de surface, fondé sur l'exploitation des décharges autostimulatrices d'un poisson électrique tropical : Apteronotus albifrons, Apteronotidae-Gymnotiformes". Nancy 1, 1996. http://docnum.univ-lorraine.fr/public/SCD_T_1996_0018_THOMAS.pdf.
Texto completo da fonteAlso, Alio Ramatou. "Influence de la densité mammaire, du traitement hormonal substitutif et de l'indice de masse corporelle sur la sensibilité et la spécificité de la mammographie de dépistage : Programme Québécois de Dépistage du Cancer du Sein (PQDCS) 2000-2005". Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28624/28624.pdf.
Texto completo da fonteChoquette, Stéphane. "Exercice et isoflavones chez les femmes ménopausées en surplus de poids effets sur la composition corporelle, le profil métabolique et la capacité physique". Thèse, Université de Sherbrooke, 2011. http://savoirs.usherbrooke.ca/handle/11143/201.
Texto completo da fonteRamin, Nicolas. "Vers une métrique sans -référence de la qualité spatiale d'un signal vidéo dans un contexte multimédia". Nantes, 2009. http://www.theses.fr/2009NANT2070.
Texto completo da fonteThe various services of real-time video communication over packet networks still do not guarantee the quality of the delivered signals. Quality evaluation then proves necessary in the design, optimization and control of robust communication chains. In this respect, subjective evaluation is naturally acknowledged as the most reliable approach. However, subjective testing may not be resorted to when it comes to real-time measuring anywhere in the data flow. We can then infer the need for automatic quality evaluation tools and especially the necessity to rely on the delivered signal only : « no-reference quality metrics following a signo-perceptual approach ». The analysis of the existing methods shows that foreseeing the spatial quality of video signals represents a substantial effort. Our contribution to this effort translates into various propositions of psychophysical studies, models and quality metrics
Beretta, Patricia. "Compression d'images appliquée aux angiographies cardiaques : aspects algorithmiques, évaluation de la qualité diagnostique". Lyon, INSA, 1997. http://theses.insa-lyon.fr/publication/1997ISAL0107/these.pdf.
Texto completo da fonteMahieux, Yannick. "Algorithmes de codage par transformée pour la réduction de débit des voies son hautes qualité". Rennes 1, 1989. http://www.theses.fr/1989REN1A003.
Texto completo da fonteSundborg, Maude. "Diagnostic d'érosion hydrique dans un bassin versant agricole au moyen d'indices topographiques dérivés d'un relevé lidar aéroporté". Mémoire, Université de Sherbrooke, 2009. http://savoirs.usherbrooke.ca/handle/11143/2599.
Texto completo da fonteAllard, Luc. "Élaboration d'un indice de qualité des eaux basé sur la structure taxonomique et fonctionnelle des assemblages de poissons des petits cours d'eau de Guyane". Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2960/.
Texto completo da fonteAccording Water Framework Directive, European oversea regions should develop water quality assessment bio-indication tools until 2015. This Phd aims to develop such a Fish-based index for French Guianese streams. Fish sampling and habitat description protocol were developped and tested, and subsequently used during data sampling phases in 2011 and 2012. Data was collected on more than 150 sites encompassing the entire French Guiana territory, and permitted to quantify the impact of anthropogenic disturbances (illegal gold mining and reduced impact logging) on fish assemblages and physical habitats. Those results were then used to build up preliminary Fish-based index for French Guianese streams
Shi, Jie. "Influence des erreurs de transmission sur la qualité de la parole synthétique d'un vocodeur à prédiction linéaire". Toulouse 3, 1990. http://www.theses.fr/1990TOU30175.
Texto completo da fonteKengne, Fotsing Joséphine. "Bio-évaluation des cours d’eau de la région Ouest du Cameroun à l’aide des macroinvertébrés benthiques et construction d’un indice multimétrique régional". Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1R067/document.
Texto completo da fonteBenthic macroinvertebrates have always been recognized as better tools for bio-assessment of the ecological quality of streams in both tropical and temperate areas. The main objective of this work was to evaluate the water quality of the Western region of Cameroon most degraded by various and multiple anthropogenic activities. From these communities of macroinvertebrates benthic and their ecological preferences at the mesohabitat scale, we resulted to the construction of a bio-assessment index of the ecological quality of streams adapted to this region. From multivariate analyzes, a stream biotypology into the sampled sites, allowed us to identify different distribution patterns, with on the one hand reference sites or non-impacted and the other hand, impacted sites based on the level of urbanization and the nature of the effluents in the different sub-watersheds. A multimetric index of biological quality (MMIWC), measuring the deviation from the reference, could be created, thanks to these two groups of stations. Among the 18 candidate metrics (transformed into Ecological Quality Ratio), we selected metrics with high discrimination efficiency and a low coefficient of variation in the reference conditions. The best performing index include two metrics derived to the taxonomic diversity (Shannon index) and taxonomic composition (1-GOLD). From a test dataset different to learning dataset, we were able to verify that MMIWC was stable in the reference conditions and sensitive to the full range of anthropogenic pressures present in this region, thus confirming its generalist character
Alsawah, Ayman. "Algorithmes d'allocation de ressources en OFDM multi-utilisateurs sous contraintes de qualité de service". Phd thesis, Cergy-Pontoise, 2008. http://biblioweb.u-cergy.fr/theses/08CERG0394.pdf.
Texto completo da fonteWe consider in this thesis the resource allocation problems in multi-user OFDM downlink systems under various Quality of service (QoS) constraints. Our goal is to propose practical solutions given partial channel-state information (CSI). We first look for the optimal subcarrier sharing in a single cell subject to differentiated QoS constraints among users. Although users are allowed to share the same subcarrier simultaneously, we prove that an orthogonal sharing (an OFDMA scheme), along with an appropriate power allocation, maximizes the weighted sum-rate. Then, we generalize OFDMA optimality to other performance criteria such as the common rate, the proportional rates, etc. Assuming an OFDMA downlink, we focus on QoS fairness by first considering the single cell case. We assume also a partial CSI consisting in the average channel gain for each user. Thus, we describe the optimal subcarrier and rate allocation that maximizes a common user rate under bounded outage probabilities. Finally, we consider the multi-cell case and we propose to use the frequency reuse partitioning as an inter-cell interference mitigation technique. Under realistic QoS fairness constraints and partial CSI, we provide a practical solution for subcarrier, base station and rate allocation that allows us to maximize the user data rate
Alsawah, Ayman. "Algorithmes d'Allocation de Ressources en OFDM Multi-Utilisateurs sous Contraintes de Qualité de Service". Phd thesis, Université de Cergy Pontoise, 2008. http://tel.archives-ouvertes.fr/tel-00767925.
Texto completo da fonteGuéguin, Marie. "Evaluation objective de la qualité vocale en contexte de conversation". Phd thesis, Université Rennes 1, 2006. http://tel.archives-ouvertes.fr/tel-00132550.
Texto completo da fonteEtame, Etame Thierry. "Conception de signaux de référence pour l'évaluation de la qualité perçue des codeurs de la parole et du son". Rennes 1, 2008. http://www.theses.fr/2008REN1S112.
Texto completo da fonteSubjective assessment is the most reliable way to determine overall perceived voice quality of network equipment, as digital codecs. Reference conditions are useful in subjective tests to provide anchors so that results from different tests can be compared. The Modulated Noise Reference Unit (MNRU) provides a simulated and calibrated degradation qualitatively similar to quantization distortion of waveform codecs. The introduction of new technologies for telecommunications services introduce new types of distortions and so the MNRU is not representative any more of the current degradations. The purpose of our work is to produce a reference system that can simulate and calibrate current degradations of speech and audio codec. The first step of the work consists in producing the multidimensional perceptive space underlying the perception of current degradations. The characterization of these perceptive dimensions should help to simulate and calibrate similar degradations
Irrera, Paolo. "Traitement d'images de radiographie à faible dose : Débruitage et rehaussement de contraste conjoints et détection automatique de points de repère anatomiques pour l'estimation de la qualité des images". Electronic Thesis or Diss., Paris, ENST, 2015. http://www.theses.fr/2015ENST0031.
Texto completo da fonteWe aim at reducing the ALARA (As Low As Reasonably Achievable) dose limits for images acquired with EOS full-body system by means of image processing techniques. Two complementary approaches are studied. First, we define a post-processing method that optimizes the trade-off between acquired image quality and X-ray dose. The Non-Local means filter is extended to restore EOS images. We then study how to combine it with a multi-scale contrast enhancement technique. The image quality for the diagnosis is optimized by defining non-parametric noise containment maps that limit the increase of noise depending on the amount of local redundant information captured by the filter. Secondly, we estimate exposure index (EI) values on EOS images which give an immediate feedback on image quality to help radiographers to verify the correct exposure level of the X-ray examination. We propose a landmark detection based approach that is more robust to potential outliers than existing methods as it exploits the redundancy of local estimates. Finally, the proposed joint denoising and contrast enhancement technique significantly increases the image quality with respect to an algorithm used in clinical routine. Robust image quality indicators can be automatically associated with clinical EOS images. Given the consistency of the measures assessed on preview images, these indices could be used to drive an exposure management system in charge of defining the optimal radiation exposure
Vlad, Raluca Ioana. "Une méthode pour l'évaluation de la qualité des images 3D stéréoscopiques". Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00925280.
Texto completo da fonteRaut, Jean-Christophe. "Synergie expérimentale impliquant la mesure lidar pour la caractérisation optique et microphysique de l'aérosol : applications à la qualité de l'air et au transfert radiatif". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00323901.
Texto completo da fonteLe, Quyet Tien. "Vers une analyse et une compréhension de la qualité d'image". Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALT060.
Texto completo da fonteIn this thesis, the main contributions are to study 2 main aspects of image quality including image aesthetic, image naturalness and the relations between the 2 concepts. More specifically, image aesthetic is the measure of how aesthetically a photo fulfills the observer’s expectation while the image naturalness definition is both related to artifacts induced by some image processing algorithms and to the individual feeling about how a picture matches with image memory. On the side of image aesthetic, the thesis deals with the problem of evaluating the roles of pre-processing operations in image aesthetic assessment. Image aesthetic assessment models based on prior image segmentation (region of interest extraction) and prior image classification (large field / close-up image classification) have been developed and compared with image aesthetic assessment models without pre-processing stages. At the same time different models base either on handcrafted features or learned features have been studied for the purpose of image aesthetic estimation. Based on the obtained results, an image aesthetic assessment model based on image classification and region segmentation has been introduced and evaluated. On the side of image naturalness, image naturalness of standard dynamic range images, especially tone-mapped images have been studied with both subjective and objective methodologies. A subjective experiment has been organized to collect human evaluations about image naturalness first. Then, various objective algorithms have been validated on the collected subjective data for the image naturalness assessment task. This work focuses on the problem of developing a model firstly to estimate if an image looks natural or not to humans and the second purpose is to try to understand how the unnaturalness feeling is induced by a photo: "Are there specific unnaturalness clues or is unnaturalness a general feeling when looking at a photo?". Finally, the relations between the 2 aspects: image aesthetic and image naturalness have been evaluated and discussed
Tiemounou, Sibiri. "Développement d'une méthode de diagnostic technique des dégradations de qualité vocale perçue des communications téléphoniques à partir d'une analyse du signal de parole". Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S097/document.
Texto completo da fonteQuality of service is a huge issue for telecommunications operators since they have to master and evaluate it in order to satisfy their customers. To replace expensive and time-consuming human judgment methods, objective methods, integrating objective models providing a prediction of the perceived quality, have been conceived. Our research aimed at developing a technical diagnostic method, complementary to objective voice quality models, which provides specific information about the nature of the perceived voice quality impairments and identifies the underlying technical causes. Assuming that speech quality is a multidimensional phenomenon, our technical diagnostic method is built on the modelling of the four perceptual dimensions identified in the literature: “Noisiness” relative to the perceived background noise, “Continuity” linked to discontinuity, “Coloration” related to frequency–response degradations and “Loudness” corresponding to the impact of the speech level, each one being quantified by quality degradation indicators based on audio signal analysis. A crucial step of our research was to find and/or to develop relevant quality degradation indicators to perfectly characterize each dimension. To do so, we identified quality degradation indicators in the most recent objective voice quality models (particularly the ITU-T P.863 recommendation, known as POLQA) and we analysed the performance of identified indicators. Then, the most relevant indicators have been considered in our diagnostic method. Finally, for each dimension, we proposed a detection block which automatically classifies a perceived degradation according to the nature of the defect detected in the audio signal, and an additional block providing information about the impact of degradations on speech quality. The proposed technical diagnostic method is designed to cover three bandwidths (Narrowband, Wideband and Super Wideband) used in telecommunications systems with a priority investigation to Super Wideband speech signals which remain very useful for future telephony applications
Wolf, Rémi. "Quantification de la qualité d'un geste chirurgical à partir de connaissances a priori". Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00965163.
Texto completo da fonteChetouani, Aladine. "Vers un système d'évaluation de la qualité d'image multi-critères". Phd thesis, Université Paris-Nord - Paris XIII, 2010. http://tel.archives-ouvertes.fr/tel-00560808.
Texto completo da fonteBosc, Emilie. "Compression des données Multi-View-plus-Depth (MVD) : De l'analyse de la qualité perçue à l'élaboration d'outils pour le codage des données MVD". Phd thesis, INSA de Rennes, 2012. http://tel.archives-ouvertes.fr/tel-00777710.
Texto completo da fonteChistyakova, Maria. "Trois problèmes sur le marché d'un produit vert : évitement fiscal, signal et différenciation verticale". Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTD039/document.
Texto completo da fonteEnvironmental quality having features of a public good is the subject of the thesis. In a theoretical framework, we study a means of environmental regulation of a polluting firm endowed with market power and then determine the optimal decentralized choice of environmental quality. We start with examining how tax avoidance affects the optimal second-best tax on polluting emissions in a monopoly setting. The firm is owned by shareholders who differ in their cost of tax dodging. The optimal tax should correct two negative externalities of avoidance: the firm's free-riding effect and a tax base erosion effect. This free-riding makes the regulator either impotent or unfair, depending on the severity of the environmental damage and the firm's efficiency. Next, we analyze the impact of an environmental tax on the signaling price strategy of a monopoly that communicates to consumers the unobservable information about firm's highenvironmental performance. We use the intuitive and undefeated criteria of equilibrium selection. Asymmetric information places the optimal second-best tax below the level required under complete information. In the case of undefeated equilibria selection, the tax may induce a "migration" from separating equilibrium to pooling making the firm prefer to conceal the private information about environmental quality. Finally, we show that market choice of environmental quality by a firm that internalizes environmental damage from polluting emissions is yet suboptimal
Ibrahim, Abbas. "Protocoles d'accès multiple orientés qualité de service en constellation de satellite à orbite basse". Phd thesis, Télécom ParisTech, 2002. http://tel.archives-ouvertes.fr/tel-00005647.
Texto completo da fonteNotre but est de développer une couche d'accès MAC au canal satellitaire tout en respectant les contraintes de la constellation LEO. Un grand nombre d'utilisateurs de différents types vont essayer d'accéder au canal satellite (sens montant) afin d'envoyer leurs paquets. Il faut distribuer les ressources disponibles entre les différents utilisateurs de façon à respecter la QoS de chaque utilisateur et à minimiser le gaspillage. Nous avons traité dans cette thèse les ponts suivants :
·Nous avons adopté les techniques CDMA (Code Division Multiple Access) et TDMA (Time Division Multiple Access) pour définir les protocoles d'accès proposés en système LEOS. Ces techniques sont adaptées afin d'être utilisées d'une manière efficace dans le cas spécifique de satellites LEO (long RTD (Round Trip Delay), Handover, ).
·Nous avons utilisé un contrôle d'admission pour les différents types de services qui agit au niveau d'appel afin d'accepter un maximum d'utilisateurs de différents types tout en respectant la QoS de chacun. Ce contrôle utilise une fonction à capacité équivalente adaptée aux différents contextes de nos études.
·Nous avons défini des services au niveau MAC d'une façon générique. Les services sont supportés au niveau MAC par des MTCs (MAC Transfer Capabilities) afin de garantir la QoS demandée par chaque service. Nous avons proposé des MTCs qui supportent tous les services et applications possibles.
·Nous avons étudié le système pour des utilisateurs hétérogènes ce qui rend l'intégration de services nécessaire. La comparaison dépend de l'intégration et de la QoS de chaque utilisateur. Le but est toujours de maximiser la capacité totale du système.
·Nous avons étudié le multiplexage de services et l'allocation de ressources pour les différents protocoles d'accès. Des techniques d'ordonnancement et de partage de ressources sont proposées afin d'atteindre pour un protocole d'accès donné la performance maximale.
L'intégration de satellite avec l'UMTS et l'utilisation de l'ATM au sein du réseau de cur sont deux facteurs essentiels qui dirigent nos propositions sur la couche MAC. Les services vus par cette couche sont appelés les MTCs (MAC Transfer Capabilities) et doivent se coordonner avec les services de l'UMTS et l'ATM. Le choix est basé aussi sur les sources de trafics utilisées dans les différents chapitres.
Belgued, Youssef. "Amélioration de la qualité géométrique des images spatiales radar : méthodes de localisation et restitution du relief par radargrammétrie". Toulouse, INPT, 2000. http://www.theses.fr/2000INPT019H.
Texto completo da fonteLi, Jing. "Méthodes pour l'évaluation et la prédiction de la Qualité d'expérience, la préférence et l'inconfort visuel dans les applications multimédia. Focus sur la TV 3D stéréoscopique". Phd thesis, Université de Nantes, 2013. http://tel.archives-ouvertes.fr/tel-01061107.
Texto completo da fonteDerviaux, Christian. "Evaluation de la visibilité des effets de blocs dans le codage MPEG : application à l'amélioration de la qualité visuelle de séquences video". Valenciennes, 1998. http://www.theses.fr/1998VALE0032.
Texto completo da fontePéchard, Stéphane. "Qualité d'usage en télévision haute définition : évaluations subjectives et métriques objectives". Phd thesis, Université de Nantes, 2008. http://tel.archives-ouvertes.fr/tel-00348586.
Texto completo da fonteMoukarzel, Camille. "Modélisation mathématique des transferts de masse et de chaleur dans des fours de verre plat". Paris, ENMP, 2003. http://www.theses.fr/2003ENMP1208.
Texto completo da fonteDumoulin, Jean-Pierre. "Traitement du signal adapté au contrôle de matériau composite par ultrasons : représentation conjointe temps-fréquence". Compiègne, 1986. http://www.theses.fr/1986COMPD020.
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