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Recently, Radio Frequency Identification (RFID) technology has become commonplace in many applications. It is based on storing and remotely retrieving the data embedded on the tags. The tag structure can be chipped or chipless. In chipped tags, an integrated IC attached to the antenna is biased by an onboard battery or interrogating signal. Compared to barcodes, the chipped tags are expensive because of the existence of the chip. That was why chipless RFID tags are demanded as a cheap candidate for chipped RFID tags and barcodes. As its name expresses, the geometry of the tag acts as both modulator and scatterer. As a modulator, it incorporates data into the received electric field launched from the reader antenna and reflects it back to the receiving antenna. The scattered signal from the tag is captured by the antenna and transferred to the reader for the detection process. By employing the singularity expansion method (SEM) and the characteristic mode theory (CMT), a systematic design process is introduced by which the resonant and radiation characteristics of the tag are monitored in the pole diagram versus structural parameters. The antenna is another component of the system. Taking advantage of ultra-wideband (UWB) technology, it is possible to study the time and frequency domain characteristics of the antenna used in chipless RFID system. A new omni-directional antenna element useful in wideband and UWB systems is presented. Then, a new time-frequency technique, called short-time matrix pencil method (STMPM), is introduced as an efficient approach for analyzing various scattering mechanisms in chipless RFID tags. By studying the performance of STMPM in early-time and late-time responses of the scatterers, the detection process is improved in cases of multiple tags located close to each other. A space-time-frequency algorithm is introduced based on STMPM to detect, identify, and localize multiple multi-bit chipless RFID tags in the reader area. The proposed technique has applications in electromagnetic and acoustic-based detection of targets. / Ph. D.

Radio frequency interference (RFI) poses significant challenges for passive microwave radiometry used in climate studies and Earth science. Despite operating in protected frequency bands, microwave radiometers often encounter RFI from sources like air surveillance radars, 5G communications, and unmanned aerial vehicles. Traditional RFI detection methods rely on handcrafted algorithms designed for specific RFI types. This study proposes a deep learning (DL) approach, leveraging convolutional neural networks to detect various RFI types on a global scale. By learning directly from radiometer data, this data-driven method enhances detection accuracy and generalization. The DL framework processes raw moment data and Stokes parameters, dynamically labeled using quality flags, offering a robust and efficient solution for RFI detection. This approach demonstrates the potential for improved RFI mitigation in passive remote sensing applications.

Bone formation and bone healing were studied in the mandible, tibia and skull bones in adult, healthy and estrogen deficient rabbits implanted with different bone substitutes. In the first study an evaluation of the differences in bone regeneration in and around solid (Alveograf *) and porous hydroxyapatite (Interpore 200*) was undertaken. The implant material was placed into experimentally made bone defects and in half of the defects hydroxyapatite was mixed with a fibrin sealant (Tisseel *). The material alone or mixed with Tisseel was also placed subperiostally in the mandible. The observation time was six month. No difference in bone regeneration was found between solid or porous hydroxyapatite granulas and the addition of Tisseel* did not seem to disturb the bone healing process. The implant material placed subperiostally did not induce bone formation nor did it provoke any bone resorption. The addition of Tisseel made the implant material much easier to handle and retain in the tissue during surgery. Bone healing around hydroxyapatite implants was also evaluated in the second study. Experimental cavities in the mandible and tibia were filled with hydroxyapatite in granules or blocks (Interpore 200*) but now with or without autolyzed, antigen-extracted, allogeneic bone (AAA). Also in this study Tisseel* was used to facilitate the handling of the material. All cavities implanted with AAA-bone, regardless of the combination with hydroxyapatite or Tisseel, demonstrated excessive bone formation resembling exostosis formation. Thus, hydroxyapatite, both as granules and blocks, can be successfully combined with AAA bone utilizing the bone inductive capacity of AAA bone. The same model was used to study the healing in ovariectomized animals in the third study. Bone cavities were implanted with or without AAA bone and left to heal. The results indicate that the osteoinductive capacity of AAA bone is in operation also in animals deprived of a normal estrogen production. The effect of using AAA bone prior to implant insertion was studied in paper four. The bone-implant contact was significant higher when AAA bone had been used. The implant stability did not seem to be affected. In paper five defects were made in skull and tibial bone in estrogen deficient animals. The deficiency of estrogen was confirmed through blood analysis, the decrease in the weight of uterus and bone mineral density. The whole body scanning with DEXA showed that the ovariectomized animals developed osteopenia. Various degree of bone formation was seen in the defects due to the influence of the bone inductive substance AAA bone. The studies indicate that a conductive material like hydroxyapatite in granules or blocks could be useful in oral reconstructive surgery. The combination with AAA bone enhanced the bone formation in calvarial and tibial bone in healthy and estrogen deficient animals. Tisseel* could be used to facilitate handling and retention of the material in the intended position during the healing process without negative effects.

Cette thèse traite de la variabilité temporelle intrinsèque de l'éclairement solaire reçu au sol. Les échelles caractéristiques de variabilité sont mises en évidence par l'analyse de longues séries temporelles de moyennes journalières de l'éclairement, pour différents endroits du monde, issues de mesures pyranométriques au sol, d'estimations satellitaires ou de réanalyses météorologiques .Compte-tenu de la nature non linéaire et non stationnaire des données, la transformée adaptative de Hilbert-Huang est utilisée comme outil d'analyse pour tenir compte de la diversité de ces échelles temporelles. On montre ainsi la nature variable des échelles caractéristiques et de leur intensité, ainsi que leur dépendance vis-à-vis du climat.L'application d'une technique adaptative de ré-échantillonnage fractionnaire montre la juxtaposition d'une composante déterministe et d'une stochastique. Pour tous les jeux de données, le cycle annuel déterministe représente la plus grande partie de la variabilité. Toutes les séries temporelle contiennent une composante de variabilité stochastique à haute fréquence, qui est modulée en amplitude par le cycle annuel.L'approche permet également d'évaluer, échelle par échelle, les performances des estimations satellitaires ou issues de ré-analyses par comparaison avec des mesures pyranométriques au sol. Une étude de cas confirme que les estimations satellitaires surpassent les ré-analyses à toutes les échelles temporelles. / The center of focus for this PhD thesis is the intrinsic temporal variability of the surface solar irradiance (SSI). The characteristic time-scales of variability are revealed by analysing long-term time-series of daily means of SSI, such as ground measurements, satellite estimates, or radiation products from global atmospheric re-analyses, for different geographical locations around the world.To account for the wide range of the time-scales of variability, and given the non-linear and non-stationary nature of the data, the adaptive, data-driven Hilbert-Huang Transform is employed as an analysis tool. The time-varying nature of the characteristic time-scales of variability, along with variations in intensity, are thus revealed.An adaptive fractional re-sampling technique is used to discriminate between the deterministic and the stochastic variability constituents. For all datasets, the deterministic yearly cycle is found to account for the largest part of variability. Furthermore, all time-series are found to contain a high-frequency stochastic variability component, that exhibit cross-scale amplitude modulation by the yearly cycle.A refinement to existing methods for assessing the fitness for use of surrogate SSI products in lieu of ground measurements is also proposed. A case study confirms that satellite estimates outperform re-analyses across all time-scales.

De nos jours, les opérations chirurgicales sont impossibles à imaginer sans anesthésie générale, qui implique la perte de conscience, l'immobilité, l'amnésie et l'analgésie. La compréhension des mécanismes sous-jacents de chacun de ces effets garantit un traitement médical bien contrôlé. Cette thèse se concentre sur l'effet analgésique de l'anesthésie générale, précisément, sur la réaction du patient aux stimuli nociceptifs. Nous étudions également les différences des réactions entre différents médicaments anesthésiques. L'étude a été effectuée sur un ensemble de données constituées de 230 signaux EEG : enregistrements pré- et post-incision obtenus sur 115 patients qui ont reçu du desflurane et du propofol. La première phase de l'étude comprend l'analyse spectrale de puissance, qui est une méthode très répandue dans le traitement du signal. L'information spectrale a été décrite en ajustant l'activité de fond, qui exhibe un comportement $1/f$, aux estimations de la densité spectrale de puissance des signaux d'EEG et en mesurant la puissance contenue dans des bandes delta et alpha par rapport à la puissance de l'activité de fond. Une autre amélioration a été réalisée par l'expansion des spectres avec des informations de temps en raison de la nature non stationnaire observée dans les signaux EEG. Pour obtenir les représentations temps-fréquence des signaux nous appliquons trois méthodes différentes: scalogramme (basé sur la transformée en ondelettes continue), spectrogramme classique, et réaffectation de spectrogramme. Celle-ci permet d'améliorer la lisibilité d'une représentation temps-fréquence en réaffectant l'énergie contenue dans le spectrogramme à des positions plus précises. Par la suite, les spectrogrammes obtenus ont été utilisés pour la reconstruction de l'espace de phase, pour l'analyse récurrence et pour sa quantification par une mesure de complexité. L'analyse de récurrence permet de décrire et visualiser les dynamiques récurrentes d'un système et de découvrir des motifs structurels contenus dans les données. Ici, les diagrammes de récurrence ont été utilisés comme réécriture de grammaire pour transformer le signal original en une séquence symbolique, où chaque symbole représente un certain état du système. Trois mesures de complexité différentes sont alors calculées à partir de ces séquences symboliques afin de les utiliser comme éléments de classification. Enfin, en combinant les caractéristiques obtenues avec l'analyse spectrale de puissance et avec l'analyse symbolique de récurrence, nous effectuons la classification des données en utilisant deux méthodes de classification~: l'analyse discriminante linéaire et les machines à vecteurs de support. La classification a été effectuée sur des problèmes à deux classes, la distinction entre les signaux EEG pré- / post-incision, ainsi qu'entre les deux différents médicaments anesthésiques, desflurane et propofol. / Nowadays, surgical operations are impossible to imagine without general anesthesia, which involves loss of consciousness, immobility, amnesia and analgesia. Understanding mechanisms underlying each of these effects guarantees well-controlled medical treatment. This thesis focuses on analgesia effect of general anesthesia, more specifically, on patients reaction to nociceptive stimuli. We also study differences in the reaction between different anesthetic drugs. The study was conducted on dataset consisting of 230 EEG signals: pre- and post-incision recordings obtained form 115 patients, who received desflurane and propofol. The first stage of the study comprise power spectral analysis, which is a widespread approach in signal processing. Spectral information was described by fitting the background activity, that exposes $1/f$ behavior, to power spectral density estimates of the EEG signals and measuring power contained in delta and alpha bands relatively to the power of background activity. A further improvement was done by expanding spectra with time information due to observed non-stationary nature of EEG signals. To obtain time-frequency representations of the signals we apply three different methods: scalogram (based on continuous wavelet transform), conventional spectrogram, and spectrogram reassignment. The latter allows to ameliorate readability of a time-frequency representation by reassigning energy contained in spectrogram to more precise positions. Subsequently, obtained spectrograms were used as phase space reconstruction in recurrence analysis and its quantification by complexity measure. Recurrence analysis allows to describe and visualize recurrent dynamics of a system and discover structural patterns contained in the data. Here, recurrence plots were used as rewriting grammar to turn an original signal into a symbolic sequence, where each symbol represents a certain state of the system. After computing three different complexity measures of resulting symbolic sequences they are used as features for classification. Finally, combining features obtained with power spectral analysis and recurrence symbolic analysis, we perform classification of the data using two classification methods: linear discriminant analysis and support vector machines. Classification was carried out on two-class problem, distinguishing between pre-/post-incision EEG signals, as well as between two different anesthetic drugs, desflurane and propofol.

Avaliou-se o comportamento biomecânico, quanto à área de estabilidade protética, extensão de cantilever e estabilidade por análise freqüência de ressonância (AFR); parâmetros clínicos: índice de placa (IP), índice de sangramento (IS), supuração, distância da plataforma do implante-margem da mucosa (DPM), profundidade de sondagem (PS), nível de inserção (NI), sangramento à sondagem (SS), largura (LM), espessura (EM) da mucosa e análise radiográfica, em dois sistemas de reabilitações implanto-suportadas. Foram instalados 104 implantes, submetidos à ativação imediata, em 26 pacientes, divididos em dois grupos: A (n= 16, All-on-4®-Nobel Biocare) e B (n=10, Neopronto®-Neodent). As próteses foram instaladas em tempo médio de 32h. (T0), e controles realizados em seis (T6), doze (T12) e 24 meses (T24). Como resultado, a taxa de sucesso foi de 100% para o grupo A e 90% para o grupo B para implantes e próteses. Diferenças significantes (p<0,05) foram apresentadas entre o cantilever posterior 10,96mm e 18,81mm e o braço de resistência (BR) 13,87mm e 5,50mm, respectivamente para os grupos A e B. A área de estabilidade, no grupo A foi de 373,5mm2 e no B de 112,8mm2; a média da AFR (em ISQ) do grupo A T0= 68,62; T6=64,40; T12=67,07; T24=66,53 e do grupo B T0= 68,37; T6=66,29; T12=67,09; T24=67,10, com diferenças (p<0,05) entre os tempos (grupo A) e posição dos implantes (grupo B). O IP no grupo A=1,0 e 0,7; grupo B=0,6 e 0,9, o IS (0,7), supuração (ausente) e SS (presença) no grupo A=50% e 37,9%; grupo B=70,1 e 52,1%, no controle de 12 e 24 meses, não mostraram diferenças estatísticas entre os grupos. As médias (em mm) da LM para o grupo A (2,05 e 2,21) e B (2,29 e 2,40) e EM grupo A (1,53 e 1,56) e B (1,31 e 1,43), DPM do grupo A (2,54e 2,52) e B (0,18mm e -0,12mm), PS grupo A (3,52 e 3,52) e B (3,52 e 4,0), NI grupo A (0,98 e 0,99) e B (3,05 e 3,57) e perda óssea grupo A (0,45mm e 0,23mm ) grupo B(0,66mm e 0,22mm), respectivamente para 12 e 24 meses, apresentaram diferenças estatísticas entre os controles. Concluindo-se que 1- O grupo A apresentou área de estabilidade e extensão de cantilever anterior e posterior, com comportamento biomecânico mais favorável do que no grupo B; 2- A estabilidade primária e secundária (AFR) foi diferente entre os tempos (grupo A) e posição dos implantes (grupo B), mas semelhantes entre os grupos; 3- Os parâmetros clínicos de índice de placa, sangramento marginal, supuração, profundidade de sondagem (exceto para os períodos de controle no grupo B), sangramento a sondagem, largura e espessura de mucosa ceratinizada foram semelhantes entre os grupos; 4- A distância da plataforma do implante-margem da mucosa foi maior no grupo A e o nível de inserção foi maior no grupo B; 5- A perda na altura da crista óssea foi semelhante entre os grupos; 6- A perda óssea foi menor nos implantes anteriores do que nos posteriores, nos grupos. / Two implant-supported rehabilitation systems were evaluated considering their biomechanical behavior, the area of prosthetic stability, cantilever extensions, stability using resonance frequency analysis (RFA) and clinical parameters, such as: modified plaque index (PI), modified bleeding index (BI), suppuration, distance between the implant shoulder and the mucosal margin (DIM), probing pocket depth (PD), probing attachment level (PAL), bleeding on probing (BP), thickness (TM) width (WM) of keratinized mucosa and radiographic analysis. One hundred and four implants had been installed in twenty six patients, submitted to immediate loading and divided into two groups: A (n=16, All-on-4®-Nobel Biocare) e B (n=10, Neopronto®-Neodent). The prosthesis had been installed in average time of 32h (T0), and controls made in (T6), 12 (T12) and 24 months (T24). As result, the success rate was 100% for the group A and 90% for the group B for both implants and prosthesis. Significant differences (p<0,05) 10,96mm and 18,81mm had been presented between posterior cantilever and the resistance arm (RA) 13,87mm and 5,50mm, respectively for the groups A and B. The stability area, in the group A was of 373,5mm2 and in B of 112,8mm2; the average of RFA (in ISQ) of the group A T0= 68,62; T6=64,40; T12=67,07; T24=66,53 and of the group B T0= 68,37; T6=66,29; T12=67,09; T24=67,10, with differences (p<0,05) between the periods (Group A) and implant position (Group B). The PI in group A was of 1,0 and 0,7 and 0,6 and 0,9 for group B, o BI (0,7), suppuration (absent), DP (presence) in group A=50% and 37,9%; group B=70,1 and 52,1%, in the control of 12 and 24 months, did not present statistical differences between the groups. The average (in mm) of WM for the group A (2,05 and 2,21) and B (2,29 and 2,40) and TM group A (1,53 and 1,56) and B (1,31 and 1,43), DIM of group A (2,54 and 2,52) and B (0,18mm and -0,12mm), DP group.

De nombreux signaux physiques incluant des signaux audio (musique, parole), médicaux (ECG, PCG), de mammifères marins ou d'ondes gravitationnelles peuvent être modélisés comme une superposition d'ondes modulées en amplitude et en fréquence (modes AM-FM), appelés signaux multicomposantes (SMCs). L'analyse temps-fréquence (TF) joue un rôle central pour la caractérisation de tels signaux et, dans ce cadre, diverses méthodes ont été développées au cours de la dernière décennie. Néanmoins, ces méthodes souffrent d'une limitation intrinsèque appelée le principe d'incertitude. Dans ce contexte, la méthode de réallocation (MR) a été développée visant à améliorer les représentations TF (RTFs) données respectivement par la transformée de Fourier à court terme (TFCT) et la transformée en ondelette continue (TOC), en les concentrant autour des lignes de crête correspondant aux fréquences instantanées. Malheureusement, elle ne permet pas de reconstruction des modes, contrairement à sa variante récente connue sous le nom de transformée synchrosqueezée (TSS). Toutefois, de nombreux problèmes associés à cette dernière restent encore à traiter tels que le traitement des fortes modulations en fréquence, la reconstruction des modes d'un SMC à partir de sa TFCT sous-échantillonnée or l'estimation des signatures TF de modes irréguliers et discontinus. Cette thèse traite principalement de tels problèmes afin de construire des nouvelles méthodes TF inversibles plus puissantes et précises pour l'analyse des SMCs.Cette thèse offre six nouvelles contributions précieuses. La première contribution introduit une extension de TSS d'ordre deux appliqué à la TOC ainsi qu'une discussion sur son analyse théorique et sa mise en œuvre pratique. La seconde contribution propose une généralisation des techniques de synchrosqueezing construites sur la TFCT, connue sous le nom de transformée synchrosqueezée d'ordre supérieur (FTSSn), qui permet de mieux traiter une large gamme de SMCs. La troisième contribution propose une nouvelle technique utilisant sur la transformée synchrosqueezée appliquée à la TFCT de second ordre (FTSS2) et une procédure de démodulation, appelée DTSS2, conduisant à une meilleure performance de la reconstruction des modes. La quatrième contribution est celle d'une nouvelle approche permettant la récupération des modes d'un SMC à partir de sa TFCT sous-échantillonnée. La cinquième contribution présente une technique améliorée, appelée calcul de représentation des contours adaptatifs (CRCA), utilisée pour une estimation efficace des signatures TF d'une plus grande classe de SMCs. La dernière contribution est celle d'une analyse conjointe entre l'CRCA et la factorisation matricielle non-négative (FMN) pour un débruitage performant des signaux phonocardiogrammes (PCG). / Many physical signals including audio (music, speech), medical data (ECG, PCG), marine mammals or gravitational-waves can be accurately modeled as a superposition of amplitude and frequency-modulated waves (AM-FM modes), called multicomponent signals (MCSs). Time-frequency (TF) analysis plays a central role in characterizing such signals and in that framework, numerous methods have been proposed over the last decade. However, these methods suffer from an intrinsic limitation known as the uncertainty principle. In this regard, reassignment method (RM) was developed with the purpose of sharpening TF representations (TFRs) given respectively by the short-time Fourier transform (STFT) or the continuous wavelet transform (CWT). Unfortunately, it did not allow for mode reconstruction, in opposition to its recent variant known as synchrosqueezing transforms (SST). Nevertheless, many critical problems associated with the latter still remain to be addressed such as the weak frequency modulation condition, the mode retrieval of an MCS from its downsampled STFT or the TF signature estimation of irregular and discontinuous signals. This dissertation mainly deals with such problems in order to provide more powerful and accurate invertible TF methods for analyzing MCSs.This dissertation gives six valuable contributions. The first one introduces a second-order extension of wavelet-based SST along with a discussion on its theoretical analysis and practical implementation. The second one puts forward a generalization of existing STFT-based synchrosqueezing techniques known as the high-order STFT-based SST (FSSTn) that enables to better handle a wide range of MCSs. The third one proposes a new technique established on the second-order STFT-based SST (FSST2) and demodulation procedure, called demodulation-FSST2-based technique (DSST2), enabling a better performance of mode reconstruction. The fourth contribution is that of a novel approach allowing for the retrieval of modes of an MCS from its downsampled STFT. The fifth one presents an improved method developed in the reassignment framework, called adaptive contour representation computation (ACRC), for an efficient estimation of TF signatures of a larger class of MCSs. The last contribution is that of a joint analysis of ACRC with non-negative matrix factorization (NMF) to enable an effective denoising of phonocardiogram (PCG) signals.

Le corps humain possède une grande redondance musculo-squelettique, se traduisant par une infinité de coordinations musculaires possibles pour produire un effort résultant. Lors d'un mouvement, le système nerveux central est confronté à la gestion de cette redondance. A travers l’analyse de cohérence entre les signaux électromyographiques, ce travail de thèse étudie le rôle fonctionnel du couplage intermusculaire et explore la contribution des mécanismes nerveux impliqués dans la régulation de la redondance musculaire en termes de contrôle de l’activité des muscles agonistes, et antagonistes impliqués dans le phénomène de co-contraction. Nos résultats ont révélé que le couplage intermusculaire entre deux muscles agonistes est modulé en présence de fatigue et en fonction de l’expertise sportive. De plus, le couplage entre muscles agonistes et antagonistes dépend des contraintes mécaniques et du rôle fonctionnel des muscles, et semble directement lié au niveau de co-contraction. La cohérence intermusculaire est modulée dans plusieurs bandes de fréquence, témoignant de l’implication de différentes commandes centrales communes d’origines spinales et supra-spinales. Nos conclusions amènent à penser que la coordination musculaire est en partie contrôlée par des commandes nerveuses communes dont la contribution est modulée suivant les propriétés fonctionnelles des muscles concernées, pour s’adapter de manière optimale aux contraintes internes ou externes de la tâche. Les travaux déjà engagés proposent de contribuer à une meilleure compréhension des mécanismes sous-jacents l’altération de la fonction motrice chez des patients cérébro-lésés. / The human motor system is characterized by high musculoskeletal redundancy, implying that a given resultant effort can result from infinity of feasible muscle coordinations. During a movement, the central nervous system has to manage such redundancy. Through coherence analysis between electromyographic signals, this thesis work aims at investigating the functional role of intermuscular coupling and at better understanding the contribution of central nervous mechanisms responsible for the regulation of muscle redundancy, in terms of agonist muscle activity and also antagonist muscles activity involved in co-contraction. Our results revealed that intermuscular coupling between agonist muscles is modulated according to both the fatigue level and the training status. We also showed that the coupling between agonist and antagonist muscles depends on the mechanical configuration and functional role of muscle pairs, and seems directly related to co-contraction. The modulation of intermuscular coherence occurs in several frequency bands, suggesting the involvement of different common central drives of spinal and supra-spinal origins according to task constraints. Taken together, our results lead us to conclude that common neural drives take part in the control of muscular coordination, with different relative contribution according to the functional properties of recruited muscles, in order to optimally adapt to both internal and external task contraints. Work already undertaken proposes to provide a better understanding of the mechanisms underlying impairment of motor function in brain-injured patients.