Dissertations / Theses on the topic 'Structures actives'

Les recherches effectuées sont centrées sur l'intégration de composants piézoélectriques dans des matrices thermodurcissables. Cependant, le problème de recyclage constitue un grand axe nécessitant le remplacement des matériaux thermodurcissables par des matériaux thermoplastiques. Toutefois, les procédés actuels de fabrication des pièces en composite actif à matière thermoplastique ne sont pas directement exploitables pour l'intégration de composants fragiles tels que les composants piézoélectriques. Le travail présenté dans ce mémoire de thèse est dédié à une contribution à la fabrication des structures thermoplastiques intelligentes. Dans ce contexte, l'objectif de la thèse est de déterminer le rapport entre le procédé de fabrication et les modèles de comportement à développer pour l'utilisation des composants piézoélectriques intégrés. Deux études sont réalisées séparément : Une première étude traite les conditions thermiques et mécaniques qui accompagnent la fabrication des structures thermoplastiques. L'influence de ces conditions sur le matériau piézocéramique intégré est analysée dans une deuxième étude. Les résultats des deux études permettent de choisir le matériau approprié pour chaque procédé et condition de mise en œuvre, de manière à minimiser l'endommagement du matériau intelligent. Cet apport permet de surmonter les obstacles relatifs à l'utilisation du thermoplastique dans les structures intelligentes.

Les récentes découvertes sur les phénomènes hyperfréquences et nonlinéaires dans les structures minces ferromagnétiques actives planaires ont fait émerger un grand nombre de nouvelles études et applications pratiques prometteuses. La conversion de l'énergie magnétoélastique peut être beaucoup plus efficace à proximité de la transition de réorientation de spin (TRS). Les structures minces ferromagnétiques actives planaires fournissent un grand nombre de caractéristiques haute fréquence uniques : par exemple, les conditions pour l'effet Doppler anomal peuvent être satisfaites. Les cristaux magnoniques représentent également un domaine prometteur pour les futures investigations.Dans le présent travail nous avons établi la description théorique de la propagation des ondes hyperfréquences et non-linéaires dans les structures minces ferromagnétiques actives planaires de compositions différentes. Il a été démontré expérimentalement et théoriquement que les vibrations basse fréquence d'un cantilever peuvent être amplifiées quand la résonance ferromagnétique est excitée par un champ électromagnétique HF à proximité de la TRS. En outre, l'effet de la démodulation magnétoélastique peut être complété par un effet magnétoélectrique nonlinéaire. La possibilité de l'apparition de l'effet Doppler anomal lors de la propagation d'une onde de surface magnétostatique dans une structure ferrite-diélectrique-métal, dans une certaine plage de paramètres du système, est démontrée. La dispersion d'une onde magnétostatique de surface se propageant dans un film dont l'épaisseur varie linéairement, et possédant une structure périodique sous la forme de bandes parallèles gravées, a été calculée

Le bassin Ionien, en Méditerranée centrale, abrite une zone de subduction à vergence Nord-Ouest où la plaque Afrique plonge sous les blocs Calabro-Péloritain au Nord-Est de la Sicile. Cette subduction résulte de la lente convergence entre les plaques tectoniques Afrique et Eurasiatique. Bien que de nombreuses campagnes d’exploration scientifique ont été menées dans cette zone particulière, plusieurs questions géodynamiques restent débattues. Tout d’abord la croûte pavant le bassin Ionien pourrait être soit de nature continentale amincie et représenter une extension de la plaque Afrique, soit océanique (Néo-Téthys) faisant de ce bassin l’un des plus anciens domaines océaniques au monde. L’escarpement de Malte représente un vestige de l’ouverture du bassin, mais les mécanismes de rifting et notamment la géométrie d’ouverture du bassin restent débattus. Cette subduction est en retrait vers le Sud-Est depuis les derniers 35 Ma, mais est aujourd’hui confinée à l’étroit bassin Ionien. Afin d’accommoder ce retrait de la plaque plongeante dans le bassin, une grande faille de déchirure lithosphérique de bord de subduction (STEP fault en anglais pour « subduction Transform Edge Propagator ») doit se propager le long de la marge Est-Sicilienne. Cependant, sa position en surface reste difficile à déterminer dans l’épais prisme d’accrétion recouvrant le bassin. Ces questions ont été explorées par modélisation des données de sismique grand angle de la campagne DIONYSUS (Octobre 2014, R/V Meteor) le long de deux profils perpendiculaires à la marge Est-Sicilienne. Des modélisations gravimétriques en 3D ont aussi été réalisées dans le but de localiser la plaque plongeante en profondeur sous les blocs Calabro-Péloritains. La sismicité des trois structures majeures du bassin : l’escarpement de Malte, l’AFS (Alfeo Fault System), et l’IFS (Ionian Fault System) a permis d’étudier leurs activités à l’actuel. Les résultats obtenus permettent d’observer une croûte océanique au fond du bassin. La structure profonde de l’escarpement de Malte est observée comme une zone d’amincissement crustal abrupt, ce qui est caractéristique des marges transformantes. Un profond bassin sédimentaire asymétrique (11 km) est observé au Sud du détroit de Messine. Il s’est probablement ouvert récemment entre les blocs continentaux Péloritain et Calabre. Dans le lobe Ouest du prisme d’accrétion Calabrais, le modèle de vitesse permet d’observer l’indentation du prisme clastique interne dans le prisme évaporitique externe. Des modélisations analogiques utilisant sable et silicone ont permis de démontrer la récente activité de ce lobe. L’interprétation des modèles de vitesse permet de localiser la faille STEP le long de l’AFS sur les deux profils
In the Ionian Sea (central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo-Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreats toward the south-east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian basin. A major lateral slab tear fault is required to accommodate the slab rollback.This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial.This PhD project focussed on the deep sedimentary and crustal structures of the eastern Sicily margin and the Malta Escarpment (ME). Two two-dimensional P wave velocity models were modelled by forward Modelling of wide-angle seismic data, acquired onboard the R/V Meteor during the DIONYSUS cruise in 2014.A 3D gravity model of the region was also performed to constrain the depth of the subducting slab bellow the Calabro-Peloritan backstops. The seismicity of the three structures identified in the velocity models (ME, Alfeo fault System, Ionian Fault System) permits to study their recent activity. The results image an oceanic crust within the Ionian basin as well as the deep structure of the Malta Escarpment, which presents characteristics of a transform margin. A deep and asymmetrical sedimentary basin is imaged south of the Messina strait and seems to have opened between the Calabrian and Peloritan continental terranes. In the western lobe of the Calabrian accretionary prism, the southern velocity model allows to observe the indentation of the internal clastic wedge into the external evaporitic wedge, thus showing the recent activity of this lobe. The interpretation of the velocity models suggests that the major STEP fault is located east of the Malta Escarpment, along the Alfeo Fault System

La zone de relais aux philippines, limitee par les extremites de deux fosses n-s, permet le transfert du mouvement entre la plaque mer des philippines et le bloc de la sonde. L'objectif de ce travail est de determiner le role des structures actives de la zone de relais et de les integrer dans un modele de deformation. Ces structures actives, a savoir, la faille de mindoro, le so de luzon comprenant le couloir du macolod, le nord de la fosse philippine, le sud de la fosse de manille, la faille d'infanta ont ete etudiees selon une approche sismologique ou geologique. Le so de l'ile de luzon, une region situee a l'arriere de la fosse de manille est caracterisee par deux reseaux de failles soumises a un meme regime extensif no-se. Le premier, ne-so est neoformee et le second, heritee, suit une direction n-s. Il comprend egalement la faille de mindoro situee au sud de luzon, qui a rompu en 1994 (ms = 7. 1). La relocalisation des repliques telesismiques et l'inversion des ondes de volume large-bande du choc principal, ont permis de determiner une source composee de deux sous-evements decrochants. Au nord de la fosse philippine, les donnees sismologiques mettent en evidence une discontinuite structurale de la plaque plongeante qui coincide en surface avec un bassin localise sur le lineament de legaspi. Ces resultats et l'analyse des donnees geodesiques, montrent que la ceinture mobile philippine est controlee par un mecanisme de decomposition du mouvement oblique entre deux zones de subduction et schematiquement constituee de deux lanieres. Ce modele original, explique la presence d'une zone extensive au so de luzon, d'une zone compressive dans les visayas et d'une laniere rigide en face de la fosse philippine ainsi que l'existence d'une faille philippine non continue.

Les alliages à mémoire de forme (AMF) sont des matériaux métalliques qui présentent des propriétés thermomécaniques particulières, et notamment l’effet mémoire de forme. L’étude réalisée durant la thèse concerne la création de systèmes actifs double-sens à l'aide de fils AMF à effet mémoire simple-sens. Trois modèles analogiques simples, représentant trois catégories de solutions constructives, ont été développés. Ces modèles correspondent à des types de couplages mécaniques différents entre un (ou des) fil(s) AMF et une structure mécanique. Par exemple, le modèle le plus simple consiste à utiliser un unique fil AMF couplé à un système mécanique constitué d’une structure monolithique déformable. Lorsque l’on chauffe l’AMF, on active l’effet mémoire de forme, ce qui entraîne une déformation de la structure. Lorsque l’on refroidit l’AMF, la rigidité propre de la structure entraîne une déformation dans le sens inverse à celui de la phase de chauffage. Plusieurs démonstrateurs ont été également construits et analysés durant la thèse. Cette étude montre la possibilité de concevoir des structures actives pilotées par des AMF, ce qui ouvre des perspectives pour le contrôle des déformations ou des contraintes dans des structures
Shape memory alloys (SMA) are metallic materials that have particular thermomechanical properties, including the shape memory effect. The study carried out during the thesis concerns the creation of two-way active systems using SMA wires exhibiting one-way memory effect. Three simple analog models, representing three classes of constructive solutions, have been developed. These models correspond to different types of mechanical coupling between one (or more) SMA wire(s) and a mechanical structure. For example, the simplest configuration is a single SMA wire coupled to a mechanical system consisting of a deformable monolithic structure. When the SMA is heated, the shape memory effect is activated, which causes the deformation of the structure. When cooling the SMA, the inherent rigidity of the structure causes a deformation in the opposite direction to that of the heating phase. Several demonstrators were also constructed and analyzed during the thesis. This study demonstrates the possibility of designing active structures driven by SMAs, which opens prospects for the control of deformations or stresses in structures

La pathogenie du diabete non-insulino-dependant (dnid) est encore loin d'etre elucidee. Cependant, il est a present reconnu que l'hyperglycemie des sujets qui en sont atteints est la consequence d'une diminution de l'efficacite de l'insuline et/ou d'une alteration de sa secretion. La liberation de cette hormone est inhibee, entre autres, par la fixation d'antagonistes sur les recepteurs alpha-2. Ces derniers, presentant une activite insulinosecretrice, portent pour leur grande majorite, un cycle imidazoline. Ainsi, nous avons etudie une serie de molecules presentant d'une part un noyau imidazolinique et d'autre part, la piperazine, charpente alliant a la fois flexibles et rigidite. Grace aux outils de la modelisation moleculaire nous nous sommes proposes d'analyser et eventuellement de prevoir les effets des cinquante molecules de cette serie d'antidiabetiques oraux sur l'homeostasie glucidique et la secretion d'insuline. L'evaluation biologique de nos composes s'est faite par le biais de trois parametres interdependants, g30, k et g. Le graphe k/g qui presente la meilleure discrimination, a ete decoupe en quadrants definissant des familles de molecules d'activite analogue. Vue la grande flexibilite des molecules etudiees, nous avons mesure, sur leurs geometries optimisees, les valeurs des angles diedres consideres comme caracteristiques, et constitue a nouveau des familles appelees gdin. Une analyse de la distribution de ces groupes d'angles diedres sur le quadrant pharmacologique tente de relier cette caracteristique geometrique a l'activite biologique. Le pms 812, molecule phare de notre serie, normalise la tolerance au glucose et stimule fortement la secretion d'insuline in vivo chez le rat diabetique. Son etude conformationnelle complete a ete realisee et nous a permis de distinguer cinq conformeres. Ces derniers ont d'abord ete optimises dans la base am1 puis en bases mini-1' et 6-31 g. La comparaison des differents angles diedres ainsi que des energies relatives obtenues a egalement ete effectuee. Au ph physiologique (ph=7,4) le pms 812 est partiellement protone. Une comparaison des energies relatives des conformeres charges obtenus a ete etudiee et a confirme l'incidence de la protonation sur la geometrie. La caracteristique majeure de cette serie de molecules etant la liberte conformationnelle, refaire l'investigation en details de la piperazine elle-meme au niveau de calcul ab initio en base double 6-31 g etait important. L'etude des proprietes electroniques de nos molecules a ete realisee. Le calcul des charges ponctuelles, sur chacun des atomes d'azote selon la methode cndo, sur des conformations dans leur geometrie optimisee au niveau am1 a permis de degager quelques tendances. Par exemple, une forte charge sur l'atome d'azote n9 semble favoriser une activite moyenne voire forte. Pour finir, une etude du potentiel electrostatique en ab initio a ete conduite sur une molecule par famille biologique. La comparaison des differents niveaux de contours energetiques de ces molecules apporte des explications quant a l'activite biologique.

L'etude des relations existantes entre la structure des toxines de scorpions anti-nsectes et leur fonction s'est faite selon deux approches, la comparaison de sequences et des modifications chimiques, et les structures secondaires (dichroisme circulaire). Deux toxines de scorpions agissant uniquement sur les insectes, aah it1 et aah it2, ont ete purifiees a partir du venin de scorpions androctonus australis hector collectes dans l'oasis de tozeur en tunisie. La structure primaire de ces deux proteines a ete determinee et revele une forte homologie de sequence entre elles. Les acides amines basiques de aah it1 ont ete modifies chimiquement de maniere selective. Six derives ont pu etre isoles, identifies et leur proprietes pharmacologiques etudiees. Les lysines 28 et 51 s'averent etre importantes pour la toxicite de ces proteines. Une etude par dichroisme circulaire a permis de constater les homologies conformationnelles de ces deux toxines. Le pourcentage des differentes structures secondaires presentes dans aah it2 a pu etre estime grace a l'analyse du spectre dichroique assistee par ordinateur et montre la presence d'une helice supplementaire par rapport aux toxines de scorpions anti-mammiferes. Trois toxines de scorpions, l'une etant active sur les mammiferes (css ii), l'autre active sur les insectes (aah it2) et enfin la derniere a la fois active sur les mammiferes et les insectes (ts vii) ont ete etudiees et comparees par dichroisme circulaire. Leur flexibilite a ete evaluee par l'amplitude des modifications de leurs structures secondaires, lorsque l'hydrophobicite du milieu est changee. Il apparait que le caractere non specifique d'une de ces toxines est associe a une plus grande flexibilite comparee aux deux autres, plus specifiques dans leur cible pharmacologique, mais egalement plus rigides. La specificite des toxines anti-insectes serait liee a la presence d'une helice

Le transport de micro-organismes et de fluides biologiques au moyen de cils et flagelles est un phénomène universel que l’on retrouve chez presque tous les êtres vivants. Le but de cette thèse est la modélisation, l’analyse mathématique et la simulation numérique de problèmes d’interaction fluide-structure qui font intervenir des structures actives, capables de se déformer d’elles-mêmes grâce à des contraintes internes, et un fluide à faible nombre de Reynolds, modélisé par les équations de Stokes. Le Chapitre 2 traite de la modélisation de ces structures actives en considérant la loi de Saint Venant-Kirchhoff dans les équations de l’élasticité et en ajoutant un terme d’activité au second tenseur de contraintes de Piola-Kirchhoff. Les équations fluide et structures sont couplées à l’interface fluide-structure et l’étude mathématique d’un problème linéarisé et discrétisé en temps est ensuite réalisée. Une reformulation sous forme d’un problème point-selle est proposée et utilisée pour la simulation numérique du problème. Le Chapitre 3 s’intéresse à l’analyse du problème d’interaction fluide-structure quasi-statique avec une structure active, pour lequel nous montrons l’existence et l’unicité, pour des données petites, d’une solution forte localement en temps. Le Chapitre 4 présente une nouvelle méthode de type domaine fictif (la méthode de prolongement régulier ) pour la résolution numérique de problèmes de transmission. La méthode est d’abord développée pour un problème de transmission de Laplace, puis étendue aux problèmes de transmission de Stokes et d’interaction fluide-structure
The transport of microorganisms and biological fluids by means of cilia and flagella is an universal phenomenon found in almost all living beings. The aim of this thesis is to model, analyze and simulate mathematical fluid-structure interaction problems involving active structures, capable of deforming themselves through internal stresses, and a low Reynolds number fluid, modeled by Stokes equations. In Chapter 2, these active structures are modeled as elastic materials satisfying Saint Venant-Kirchhoff law for elasticity whose activity comes from the addition of an activity term to the second Piola-Kirchhoff stress tensor. Elasticity and Stokes equations are coupled on the fluid-structure interface and the mathematical study of the linearized problem discretized in time is realized. Then, the problem is formulated as a saddle-point problem which isused for numerical simulations. Chapter 3 focuses on the analysis of a quasi-static fluid-structure with an active structure, for which we show existence and uniqueness, for small data, of a strong solution locally in time. Chapter 4 presents a new fictitious domain method (the smooth extension method) for the numerical resolution of transmission problems. The method is first developed for a Laplace transmission problem and further extended to Stokes transmission and fluid-structure interaction problems

Les avancées majeures des télécommunications optiques ont nécessité l'élaboration de circuits intégrés optiques (ClOs) pour émettre, recevoir, traiter et distribuer l'information. Historiquement, de nombreuses technologies de ClOs ont été développées en parallèle. Cependant, dans le but de réduire les dimensions et les coûts des futurs ClOs, il est nécessaire de pouvoir intégrer plusieurs fonctions élémentaires sur un même substrat Pour cela, nous avons étudié la possibilité de réaliser des structures hybrides sur verre composées d'une couche mince guidante de matériau actif ou passif reporté sur un guide d'ondes de surface réalisé par échange d'ions. Nous nous sommes particulièrement intéressés à la réalisation d'un amplificateur. Optique hybride grâce à la mise au point d'une technique de collage par adhésion moléculaire d'un verre silicate contenant des guides d'ondes. Et d'un verre phosphate codopé Er3+/Yb3+. Pour cela, nous avons développé un procédé d'échange d'ions T1+/K+ laissant la surface du verre intacte, un procédé de collage à basse température ainsi qu'une technique d'amincissement permettant de réduire l'épaisseur du verre actif à moins de 10μm. Un amplificateur hybride a été réalisé et un coefficient de gain de 3,66 dB/cm a été obtenu, ce qui est comparable aux meilleures performances publiées pour des amplificateurs classiques réalisés par échange d'ions. Un gain net positif a même été démontré dans un autre amplificateur hybride réalisé par un échange d'ions Ag+/Na+ et aminci par rodage/polissage. La réalisation d'autres fonctions en configuration hybride (encapsulation d'un réseau de Bragg, isolateur optique) a ensuite été étudiée
The need of optical fiber telecommunication systems has been the driving force for the tremendous development of integrated optical circuits (IOCs) with a vast number of technologies which are up to now incompatible. However, the integration of elementary functionson a single wafer seems to be required to reduce the dimension and the cost for future complex IOCs. Ln this perspective, we propose in this report the realization of hybrid structures on glass. These latter consist of a passive or active thin guiding layer on a glass wafer containing an ion-exchanged channel waveguide. This work has mainly been devoted to the study and the realization of an hybrid optical amplifier by wafer bonding and ion-exchange techniques. First, a T1+/K+ ion-exchange process has been developed in a passive silicate glass with the aim of keeping a fiat glass surface. Then, an Er3+/Yb3+ codoped phosphate glass layer with a thickness below 10 μm has been formed by a low temperature wafer bonding process (<150°C) foIlowed by a polishing thinning procedure. The realized hybrid structure has been characterized and a promising gain coefficient of 3. 66 dB/cm has been reached which is comparable with the best published values for standard ion-exchanged optical amplifiers. This result has been improved thanks to the implementation of an Ag+/Na+ ion-exchange and a grinding/polishing process and net gain operation has been demonstrated. Other hybrid structures have also been studied : a glass surface- and polarization-insensitive embedded Bragg filter and an hybrid optical isolator. Finally, the necessary future works for the integration of aIl hybrid structures on a single wafer have been described

A nos jours, la résistance des microorganismes aux antibiotiques est l'un des plus gros problèmes de la santé publique. La recherche de nouvelles familles de composés naturelles ou synthétiques nous amène vers la découverte des méthodologies innovantes conduisant à de nouveaux antibiotiques. Dans le présent travail, nous vous invitons à plonger dans le "nouveau monde" de la synthèse, la réactivité et l'activité biologique de 1,3-oxazoline-2-thiones (OXTs). En effet, cet hétérocycle peu exploré est un facilement obtenu par condensation entre _-hydroxycarbonyle et l'acide thiocyanique. Lorsque l'hétérocycle est ancré sur un modèle de glucides, des structures originales sont attendus tels que OZTs fusionnées à cinq ou six chaînons et OXTs liées par une liaison C-C aux sucres, avec un vaste potentiel chimique et biologique. Nous avons alors étudié la synthèse et la réactivité de OXT simple et thionocarbamates fusionnées ou liés à des glucides modèles, conduisant à la formation de nouveaux carbohydrates fusionnées aux oxazolidinones (OZOs) ainsi que des pseudo C-iminosucres et oxazoles. Nous avons également exploré l'électrophilie de la fonction thioamide dans les couplages croisés de type Suzuki et Stille. Une nouvelle modification de la réaction de Sonogashira a été élaborée en utilisant le cuivre (I) comme cofacteur en quantité catalytique, et sa faisabilité a été démontrée pour une variété de substrats
The resistance of microorganisms to antibiotics is, in our days, one of the biggest problems in terms of public health. The research for new artificial and natural families of compounds throws us towards innovative methodologies leading to novel antibiotics.In the present work, we are invited to dive in the “new world” of 1,3-oxazoline-2-thiones (OXTs) synthesis, reactivity and biological activity. In fact, this unexplored heterocycle is a simple synthon readily obtained by condensation of thiocyanic acid with an _-hydroxycarbonyl species. When the heterocycle is anchored on a carbohydrate template, original structures are expected such as OZTs fused to five- or six-membered rings and OXTs C-C linked to sugars, with a broad potential in organic chemistry and bioorganic applications. We have then investigated the synthesis and reactivity of simple OXT and thionocarbamates fused or linked to carbohydrate templates, leading to the formation of new carbohydrate-fused oxazolidinones (OZOs) as well as pseudo-C-iminosugars and oxazoles. We have also explored the use of thioxo compounds as electrophiles in Pd-assisted cross-coupling methods, such as Suzuki and Stille reactions. A new modified Sonogashira cross-coupling reaction, in which copper (I) is used in catalytic amount, was developed and its feasibility was proven for a variety of substrates. Finally, our attention was focused on the biological potential of the new molecules. We have targeted a broad spectrum of antimicrobial activity for some OXTs and OZTs, to which was added a screening of glycosidases inhibition for the pseudo C-iminosugars

Les modes de glissement sur l'interface de subduction varient du glissement asismique stable à la rupture sismique rapide en passant par des glissements transitoires lents dont la durée s'étend de quelques jours à plusieurs mois. Les séismes qui ont lieu peuvent refléter soit la sismicité de fond, soit des chocs principaux suivis de répliques, soit une organisation en essaim sismique généralement associée à un processus de glissement lent et/ou de diffusion de fluide.La densification des observations sismologiques a encouragé les sismologues à utiliser des algorithmes automatisant la lecture des arrivées des ondes P et S. L'arrivée de l'intelligence artificielle permet notamment la lecture plus précise et plus exhaustive des arrivées P et S. Néanmoins, même ces algorithmes n'évitent pas les fausses détections. Obtenir des catalogues de microsismicité fiables tels que les événements détectés soient bien des séismes est donc un enjeu majeur.Grâce au réseau sismologique qui s'est densifié depuis 2010 dans l'avant-arc équatorien, cette thèse vise à mieux comprendre la relation entre microsismicité et glissement lent ainsi qu'à extraire de la microsismicité des signaux précurseurs d'un séisme de subduction majeur afin d'améliorer la compréhension du cycle sismique.Le premier objectif de cette thèse est de déterminer une méthodologie pour la construction automatique de catalogues de microsismicité les plus exhaustifs possibles et avec la meilleure résolution spatiale. Cette méthodologie utilise des algorithmes d'intelligence artificielle pour la lecture des temps d'arrivée des ondes P et S dont la précision a été comparée aux lectures manuelles. Après détermination des solutions hypocentrales, nous avons développé une procédure de nettoyage du catalogue, essentielle pour éliminer les fausses détections.Cette méthodologie a été appliquée dans un premier temps à un réseau local grâce auquel un essaim sismique a été mis en évidence dans la plaque plongeante synchrone par rapport à un glissement lent de Mw 6.3 qui est localisé sur l'interface de subduction dans l'avant-arc central équatorien. La migration de cette sismicité montre la diversité des processus physiques contrôlant la distribution des séismes, avec l'imbrication de glissement asismique et de diffusion de fluide comme moteur de la sismicité. Dans un second temps, cette méthodologie a été appliquée aux données de l'ensemble des stations de la marge entre 2010 et avril 2016. Ce catalogue a permis d'établir une échelle de magnitude locale dans l'avant-arc et mettre en évidence une segmentation spatiale de la b-value de la relation fréquence - magnitude de Gutenberg-Richter. La b-value est corrélée au couplage intersismique le long de l'interface de subduction. L'augmentation du nombre d'événements et des magnitudes au cours du temps dans la zone englobant la rupture cosismique du séisme de Pedernales de 2016 suggère un signal précurseur pluri-annuel pour ce séisme de subduction.Mots clés : Zone de subduction, essaim sismique, glissement lent, migration de la sismicité
Slip modes at the subduction interface range from stable aseismic slip to rapid seismic rupture, via slow transient slip lasting from a few days to several months. The earthquakes that occur may reflect either background seismicity, main shocks followed by aftershocks, or seismic swarms generally associated with slow slip and/or fluid diffusion processes.The increasing density of seismological observations has encouraged seismologists to use algorithms that automate the reading of P and S wave arrivals. Artificial intelligence, in particular, enables more accurate and exhaustive reading of P and S arrivals. However, even these algorithms do not prevent false detections. Obtaining reliable microseismicity catalogs so that the detected events are indeed earthquakes is therefore a major challenge.Thanks to the seismological network in the Ecuadorian forearc, which has become denser since 2010, this thesis aims to better understand the relationship between microseismicity and slow slip, as well as to extract from microseismicity the precursor signals of a major subduction earthquake in order to improve our understanding of the seismic cycle.The first objective of this thesis is to determine a methodology for the automatic construction of microseismicity catalogs that are as exhaustive as possible and with the best spatial resolution. This methodology uses artificial intelligence algorithms to pick P and S-wave arrival times, the accuracy of which has been compared with manual readings. Following hypocentral determination, we developed a catalog cleaning procedure to remove false detections.This methodology was first applied to a local seismic network that revealed a seismic swarm located within the subducting plate synchronous to a Slow Slip Event of Mw 6.3 located on the subduction interface in the central Ecuadorian forearc. Seismicity migration shows that physical processes controlling the distribution of earthquakes are diverse, with the interplay of both aseismic slip and fluid diffusion. In a second phase, this methodology was applied to data acquired by all stations on the margin between 2010 and April 2016. The derived catalog has enabled us to establish a local magnitude scale in the forearc and highlight a spatial segmentation of the b-value. The b-value, an indicator of the Gutenberg-Richter frequency-magnitude relationship, correlates with interseismic coupling along the subduction interface. The increase in the number of events and magnitudes over time in the zone encompassing the coseismic rupture of the 2016 Pedernales earthquake suggests a multi-year precursory signal for this subduction earthquake.Keywords: Subduction zone, seismic swarm, slow slip, seismicity migration

Les technologies associées aux antennes imprimées, peu répandues dans les dispositifs grand public, peuvent apporter des solutions intéressantes aux spécifications de plus en plus strictes (coût, débit de transmission, dimensions) imposées aux divers systèmes de télécommunication actuels (téléphonie mobile, internet, télévision numérique, etc. ). La première partie de ce mémoire est consacrée à l'utilisation d'un nouveau matériau de faible permittivité et à faibles pertes, la mousse d'imide polyméthacrylate, pour la conception de réseaux d'antennes passives à polarisation circulaire pour les communications terrestres et satellitaires. (. . . ). Dans la deuxième partie du mémoire, de nouveaux concepts sont présentés dans le domaine des antennes actives à base d'antennes oscillantes. Tout d'abord, une antenne mélangeuse auto-oscillante utilisant une antenne à cavité a été conçue et mesurée. L'oscillateur fonctionnant à une fréquence de résonance de la cavité, les niveaux de bruit de phase et de rayonnement parasite de l'oscillateur sont faibles. La modulation de phase à 2 et 4 états d'une antenne oscillante est ensuite mise en oeuvre et a permis des débits supérieurs à 1 Mbit/s. Enfin, une nouvelle méthode de mise en réseau d'antennes oscillantes permettant, grâce à une configuration séquentielle, d'obtenir un réseau générant une polarisation circulaire de bonne qualité et de façon très fiable, est étudiée théoriquement et validée expérimentalement. (. . . )

Cette étude est consacrée à la fonctionnalisation d’un textile de poly (éthylène téréphtalate) avec des molécules bioactives d’origine biologique. La curcumine, la nisine et l’alginate, ont été appliqués au tissu de PET afin de lui conférer une activité antibactérienne. Différents procédés ont été utilisés, l’application des actifs par foulardage, par diffusion et/ou par adsorption, ainsi que des techniques de traitement de surface comme le plasma et l’UV-Excimère. Suite à cette fonctionnalisation, le PET a été caractérisé de point de vue physico-chimique et biologique, ceci en utilisant différentes techniques de caractérisation comme : l’étude du mouillage par tensiomètrie, l’AFM, l’XPS, la colorimétrie, la Spectroscopie UV-visible, la spectrofluorimétrie, …. . D’autre part les propriétés de durabilité du traitement ont été évaluées. Cette étude met en évidence les difficultés liées à l’utilisation de molécules d’origine biologique. En particulier, leur mise en œuvre est délicate à cause de leur manque de stabilité en fonction des paramètres extérieurs : Température, pH, UV,… Cependant ces molécules ont des caractéristiques antibactériennes intéressantes. Nous avons étudié différents modes d’accrochage des molécules actives sur le textile : diffusion dans la fibre, adsorption à la surface, inclusion dans un hydrogel. On montre que le caractère antibactérien du traitement est du à la fois au relargage des molécules actives mais aussi à des mécanismes plus complexes associant les produits de dégradation de cette molécule. La cinétique de relargage peut être contrôlée par les paramètres de mise en œuvre des traitements
This study aim to the functionalization of poly (ethylene terephthalate) (PET) fabric using active biomolecules. Curcumin, Nisin and Alginate, were applied to the PET fabric to give it an antibacterial activity. Various methods have been used, active molecules were applied by padding, diffusion and/or adsorption, and surface treatment techniques such as plasma and UV-Excimer. After the functionalization, physical, chemical and biological characterizations were carried out using various techniques such as: Wettability, AFM, XPS, Colorimetry, UV-visible Spectroscopy, Spectrofluorimetry. . . On the other hand, the properties of durability of treatment were evaluated. This study highlights the difficulties associated with the use of biomolecules. In particular, their use is difficult because of their lack of stability as a function of external parameters: temperature, pH, UV. . . However, these molecules have interesting antibacterial properties. We have studied different methods of active molecules attachment on textiles: diffusion in the fiber, surface adsorption and inclusion in a hydrogel. We show that the antibacterial property of the treatment is due to the active molecules release, but also due to more complex mechanisms involving the molecules degradation products. The kinetics of release can be controlled by the parameters used for the treatment

Aujourd'hui, les découvertes les plus passionnantes et les réalisations les plus fascinantes se déroulent à la périphérie de différents domaines. Un domaine peu connu qui a récemment démontré des résultats spectaculaires est l'application des principes de l'origami à la science et les technologies modernes. Cette approche présente des avantages qui justifient que l’on s’y attarde. Ce travail de thèse se concentre sur le développement de structures actives à base d’origami à la fois reconfigurables et adaptatives. Nous avons proposé une méthode de synthèse de structures actives à base d’origami. Elle est composée de plusieurs étapes : définition du cahier des charges, création du motif origami en 2D après un choix préalable de la base, conversion en 3D, modélisation multi-physique, choix des technologies de fabrication, intégration de systèmes d’actionnement, validation expérimentale et contrôle. Elle a été suivie du choix des outils logiciels assurant une interopérabilité mutuelle. Elle a ensuite été appliquée et validée pour une application en acoustique. Nous avons alors proposé un concept de résonateurs de Helmholtz adaptatifs à base d’origami pour le contrôle adaptatif-passif du bruit, et nous avons pu obtenir des résultats remarquables en termes de plage de fréquence et de largeur de bande. Un ensemble de modèle a été proposé pour décrire le fonctionnement des résonateurs de Helmholtz adaptatifs à base d’origami suivant leur flexibilité. Nous avons également étudié des actionneurs à base de matériaux actifs pour des structures à base d’origami. Plus précisément les polymères conducteurs qui sont capable de réaliser de grandes déformations à faible tension d’activation pour l’auto-pliage réversible
Today, the most exciting discoveries and fascinating accomplishments are performed on the peripheries of different areas. A not very well-known area which has recently demonstrated spectacular achievements is the application of origami principles in modern science and technology. This approach has advantages that justify the recent attention. This thesis work focuses on the development of origami-based active structures, both reconfigurable and adaptive. We proposed a new synthesis method of origami-based active structures. It is composed of several stages: definition of the application requirements, creation of the origami motif in 2D after a preliminary choice of the base, conversion in 3D, multi-physics modeling, selection of fabrication technologies, integration of the actuation system, experimental validation, and control. The method was followed by a choice of software tools that ensure mutual interoperability. It was then applied and validated for an acoustics application. A concept of tunable origami-based Helmholtz resonators for adaptive-passive noise control. The resonators were able to achieve remarkable results in terms of frequency range and bandwidth. A set of models has been proposed to describe the functioning of tunable origami-based Helmholtz resonators according to their flexibility. We also studied actuators based on active materials for origami-based structures. More specifically, conductive polymers which are capable of producing large deformations with a low activation voltage, and a reversible self-folding

La croissance du trafic de données a conduit à la généralisation des transmissions sur fibre optique dans les réseaux interurbains et transcontinentaux. Face à la montée en débit occasionnée, on assiste actuellement au développement du traitement tout-optique de l'information pour apporter une solution alternative au traitement électronique. La régénération " 3r " (reamplifying, reshaping and retiming) des signaux est un des éléments photoniques clés pour le traitement du signal à très haut débit. Les milieux à semi-conducteurs, de par leurs non-linéarités et leur temps de réponse rapide, apparaissent comme des candidats intéressants pour la réalisation de telles fonctions. Les propriétés du mélange à quatre ondes dans ces structures sont étudiées et appliquées à la réalisation de sous-fonctions optiques, nécessaires à régénération tout-optique, comme la récupération d'horloge, l'auto-synchronisation de trames multiplexées en longueurs d'onde et la régénération du taux d'extinction
Data traffic growth leads to generalisation of fibre optic in telecommunication networks. Optical technologies allow to overcome physical limitations in electronic data processing for high speed (> 40 gbit/s) transmission. All-optical 3r regeneration will be one of the key functions in such future networks. Semiconductor devices appear to be adapted thanks to nanosecond scale radiative lifetime. We propose to use four-wave mixing properties in semiconductor amplifiers and lasers to achieve fundamental elements of 3r regeneration such as frames synchronisation, clock recovery and d-bascule

Cette these decrit l'analyse, la conception et la caracterisation d'antennes imprimees passives et actives pour la bande millimetrique. La methode d'analyse retenue est basee sur la technique des equations integrales resolues par la methode des moments. Son extension a l'etude du chargement par des composants non-lineaires est developpee a partir de l'association de la methode d'analyse electromagnetique a celle de balance harmonique. Les premiers resultats sur une structure microruban permettent de valider la resolution globale du probleme electromagnetique. L'outil electromagnetique est ensuite applique a la conception d'antennes imprimees passives. Nous presentons des elements rayonnants a geometries simples fonctionnant a 38 et 60 ghz sur des substrats a forte permittivite (alumine, inp et asga). La permittivite relative et l'angle de pertes du substrat d'inp sont determines a partir de la technique de l'anneau resonant. Les problemes lies aux faibles dimensions des antennes ainsi que ceux poses par les contraintes technologiques et la fiabilite des mesures sont abordes. Les solutions apportees pour les mesures en champ proche et lointain sont discutees. Afin de remedier au faible gain des antennes imprimees sur substrat a forte permittivite, une antenne active integree est proposee. La phase de conception comprend de nombreuses etudes parametriques tant sur la dispersion des composants localises que sur l'environnement proche de l'antenne. Elles permettent de quantifier leurs effets sur le comportement de la structure. Enfin, la procedure de caracterisation des dispositifs actifs concus est presentee. Des mesures sous pointes ont permis d'identifier l'origine des problemes. Les resultats de mesure d'impedance et de rayonnement de l'antenne active sont confrontes a ceux de la simulation et les differences observees sont discutees. L'influence de l'environnement de mesure et l'apport de l'amplificateur sur les performances de l'antenne sont quantifies

L'elaboration d'un simulateur electromagnetique global de structures planaires actives est presentee dans cette these. Il permet une analyse en regime lineaire et non lineaire des structures etudiees. Ce simulateur est base sur la technique des equations integrales aux potentiels mixtes combinee avec une representation multipole du circuit actif pour l'etude en regime lineaire. Afin de representer au mieux les phenomenes electromagnetiques complexes dans la zone d'insertion du composant actif, un modele de conducteur vertical planaire est developpe. Il permettra notamment d'assurer une description numerique rigoureuse des dispositifs de mise a la masse des composants. Le probleme electromagnetique ainsi mis en equation est resolu numeriquement a l'aide de la methode des moments, etendue dans ce travail a l'analyse de structures comportant des metallisations verticales planaires. L'outil developpe permet de prendre en compte de facon globale, le composant et les parties passives de l'application au sein d'une meme analyse electromagnetique. De nombreuses structures de validations telles que l'antenne quart d'onde court-circuitee l'antenne agile en frequence, les amplificateurs hybrides et l'antenne active integree ont permis de confronter avec succes les resultats de notre analyse electromagnetique globale a l'experience. L'analyse en regime non lineaire est basee sur une approche de type compression associant le simulateur electromagnetique avec un logiciel d'analyse non lineaire commercial. Cette approche a ete etendue dans le cadre de cette these pour etudier l'influence sur les diagrammes rayonnes aux harmoniques. Cette technique a ete appliquee a l'etude d'une antenne chargee par une diode en regime non lineaire.

The demands of consumer electronic products to support multi-functionality such as computing, communication and multimedia applications with reduced form factor and low cost is the driving force behind packaging technologies such as System on Package (SOP). SOP aims to enhance the functionality of the package while providing form factor reduction by the integration of active and passive components. However, embedding components within mixed signal packages causes unwanted interferences across the digital and analog-radio frequency (RF) sections of the package, which is a major challenge yet to be addressed. This dissertation focused on the chip-last method of embedding chips within cavities in organic packages and addressed the challenges for preserving power integrity in such packages. The challenges associated with electromagnetic coupling in packages when chips are embedded within the substrate layers are identified, analyzed and demonstrated. The presence of the chip embedded within the package introduces new interaction mechanisms between the chip and package that have not been encountered in conventional packages with surface mounted chips. It is of significant importance to understand the chip-package interaction mechanisms, for ensuring satisfactory design of systems with embedded actives. The influence of the electromagnetic coupling from the package on the bulk substrate and bond-pads of the embedded chip are demonstrated. Solutions that remedy the noise coupling using Electromagnetic Band-Gap structures (EBGs) along with design methodologies for their efficient implementation in multilayer packages are proposed. This dissertation presents guidelines for designing efficient power distribution networks in multilayer packages with embedded chips.

Uncertainty involved in the safe and comfort design of the structures is a major concern of civil engineers. Traditionally, the uncertainty has been overcome by utilizing various and relatively large safety factors for loads and structural properties. As a result in conventional design of for example tall buildings, the designed structural elements have unnecessary dimensions that sometimes are more than double of the ones needed to resist normal loads. On the other hand the requirements for strength and safety and comfort can be conflicting. Consequently, an alternative approach for design of the structures may be of great interest in design of safe and comfort structures that also offers economical advantages. Recently, there has been growing interest among the researchers in the concept of structural control as an alternative or complementary approach to the existing approaches of structural design. A few buildings have been designed and built based on this concept. The concept is to utilize a device for applying a force (known as control force) to encounter the effects of disturbing forces like earthquake force. However, the concept still has not found its rightful place among the practical engineers and more research is needed on the subject. One of the main problems in structural control is to find a proper algorithm for determining the optimum control force that should be applied to the structure. The investigation reported in this thesis is concerned with the application of active control to civil engineering structures. From the literature on control theory. (Particularly literature on the control of civil engineering structures) problems faced in application of control theory were identified and classified into two categories: 1) problems common to control of all dynamical systems, and 2) problems which are specially important in control of civil engineering structures. It was concluded that while many control algorithms are suitable for control of dynamical systems, considering the special problems in controlling civil structures and considering the unique future of structural control, many otherwise useful control algorithms face practical problems in application to civil structures. Consequently a set of criteria were set for judging the suitability of the control algorithms for use in control of civil engineering structures. Various types of existing control algorithms were investigated and finally it was concluded that predictive optimal control algorithms possess good characteristics for purpose of control of civil engineering structures. Among predictive control algorithms, those that use ARMA stochastic models for predicting the ground acceleration are better fitted to the structural control environment because all the past measured excitation is used to estimate the trends of the excitation for making qualified guesses about its coming values. However, existing ARMA based predictive algorithms are devised specially for earthquake and require on-line measurement of the external disturbing load which is not possible for dynamic loads like wind or blast. So, the algorithms are not suitable for tall buildings that experience both earthquake and wind loads during their life. Consequently, it was decided to establish a new closed loop predictive optimal control based on ARMA models as the first phase of the study. In this phase it was initially established that ARMA models are capable of predicting response of a linear SDOF system to the earthquake excitation a few steps ahead. The results of the predictions encouraged a search for finding a new closed loop optimal predictive control algorithm for linear SDOF structures based on prediction of the response by ARMA models. The second part of phase I, was devoted to developing and testing the proposed algorithm The new developed algorithm is different from other ARMA based optimal controls since it uses ARMA models for prediction of the structure response while existing algorithms predict the input excitation. Modeling the structure response as an AR or ARMA stochastic process is an effective mean for prediction of the structure response while avoiding measurement of the input excitation. ARMA models used in the algorithm enables it to avoid or reduce the time delay effect by predicting the structure response a few steps ahead. Being a closed loop control, the algorithm is suitable for all structural control conditions and can be used in a single control mechanism for vibration control of tall buildings against wind, earthquake or other random dynamic loads. Consequently the standby time is less than that for existing ARMA based algorithms devised only for earthquakes. This makes the control mechanism more reliable. The proposed algorithm utilizes and combines two different mathematical models. First model is an ARMA model representing the environment and the structure as a single system subjected to the unknown random excitation and the second model is a linear SDOF system which represents the structure subjected to a known past history of the applied control force only. The principle of superposition is then used to combine the results of these two models to predict the total response of the structure as a function of the control force. By using the predicted responses, the minimization of the performance index with respect to the control force is carried out for finding the optimal control force. As phase II, the proposed predictive control algorithm was extended to structures that are more complicated than linear SDOF structures. Initially, the algorithm was extended to linear MDOF structures. Although, the development of the algorithm for MDOF structures was relatively straightforward, during testing of the algorithm, it was found that prediction of the response by ARMA models can not be done as was done for SDOF case. In the SDOF case each of the two components of the state vector (i.e. displacement and velocity) was treated separately as an ARMA stochastic process. However, applying the same approach to each component of the state vector of a MDOF structure did not yield satisfactory results in prediction of the response. Considering the whole state vector as a multi-variable ARMA stochastic vector process yielded the desired results in predicting the response a few steps ahead. In the second part of this phase, the algorithm was extended to non-linear MDOF structures. Since the algorithm had been developed based on the principle of superposition, it was not possible to directly extend the algorithm to non-linear systems. Instead, some generalized response was defined. Then credibility of the ARMA models in predicting the generalized response was verified. Based on this credibility, the algorithm was extended for non-linear MDOF structures. Also in phase II, the stability of a controlled MDOF structure was proved. Both internal and external stability of the system were described and verified. In phase III, some problems of special interest, i.e. soil-structure interaction and control time delay, were investigated and compensated for in the framework of the developed predictive optimal control. In first part of phase III soil-structure interaction was studied. The half-space solution of the SSI effect leads to a frequency dependent representation of the structure-footing system, which is not fit for control purpose. Consequently an equivalent frequency independent system was proposed and defined as a system whose frequency response is equal to the original structure -footing system in the mean squares sense. This equivalent frequency independent system then was used in the control algorithm. In the second part of this phase, an analytical approach was used to tackle the time delay phenomenon in the context of the predictive algorithm described in previous chapters. A generalized performance index was defined considering time delay. Minimization of the generalized performance index resulted into a modified version of the algorithm in which time delay is compensated explicitly. Unlike the time delay compensation technique used in the previous phases of this investigation, which restricts time delay to be an integer multiplier of the sampling period, the modified algorithm allows time delay to be any non-negative number. However, the two approaches produce the same results if time delay is an integer multiplier of the sampling period. For evaluating the proposed algorithm and comparing it with other algorithms, several numerical simulations were carried during the research by using MATLAB and its toolboxes. A few interesting results of these simulations are enumerated below: ARM A models are able to predict the response of both linear and non-linear structures to random inputs such as earthquakes. The proposed predictive optimal control based on ARMA models has produced better results in the context of reducing velocity, displacement, total energy and operational cost compared to classic optimal control. Proposed active control algorithm is very effective in increasing safety and comfort. Its performance is not affected much by errors in the estimation of system parameters (e.g. damping). The effect of soil-structure interaction on the response to control force is considerable. Ignoring SSI will cause a significant change in the magnitude of the frequency response and a shift in the frequencies of the maximum response (resonant frequencies). Compensating the time delay effect by the modified version of the proposed algorithm will improve the performance of the control system in achieving the control goal and reduction of the structural response.

Uncertainty involved in the safe and comfort design of the structures is a major concern of civil engineers. Traditionally, the uncertainty has been overcome by utilizing various and relatively large safety factors for loads and structural properties. As a result in conventional design of for example tall buildings, the designed structural elements have unnecessary dimensions that sometimes are more than double of the ones needed to resist normal loads. On the other hand the requirements for strength and safety and comfort can be conflicting. Consequently, an alternative approach for design of the structures may be of great interest in design of safe and comfort structures that also offers economical advantages. Recently, there has been growing interest among the researchers in the concept of structural control as an alternative or complementary approach to the existing approaches of structural design. A few buildings have been designed and built based on this concept. The concept is to utilize a device for applying a force (known as control force) to encounter the effects of disturbing forces like earthquake force. However, the concept still has not found its rightful place among the practical engineers and more research is needed on the subject. One of the main problems in structural control is to find a proper algorithm for determining the optimum control force that should be applied to the structure. The investigation reported in this thesis is concerned with the application of active control to civil engineering structures. From the literature on control theory. (Particularly literature on the control of civil engineering structures) problems faced in application of control theory were identified and classified into two categories: 1) problems common to control of all dynamical systems, and 2) problems which are specially important in control of civil engineering structures. It was concluded that while many control algorithms are suitable for control of dynamical systems, considering the special problems in controlling civil structures and considering the unique future of structural control, many otherwise useful control algorithms face practical problems in application to civil structures. Consequently a set of criteria were set for judging the suitability of the control algorithms for use in control of civil engineering structures. Various types of existing control algorithms were investigated and finally it was concluded that predictive optimal control algorithms possess good characteristics for purpose of control of civil engineering structures. Among predictive control algorithms, those that use ARMA stochastic models for predicting the ground acceleration are better fitted to the structural control environment because all the past measured excitation is used to estimate the trends of the excitation for making qualified guesses about its coming values. However, existing ARMA based predictive algorithms are devised specially for earthquake and require on-line measurement of the external disturbing load which is not possible for dynamic loads like wind or blast. So, the algorithms are not suitable for tall buildings that experience both earthquake and wind loads during their life. Consequently, it was decided to establish a new closed loop predictive optimal control based on ARMA models as the first phase of the study. In this phase it was initially established that ARMA models are capable of predicting response of a linear SDOF system to the earthquake excitation a few steps ahead. The results of the predictions encouraged a search for finding a new closed loop optimal predictive control algorithm for linear SDOF structures based on prediction of the response by ARMA models. The second part of phase I, was devoted to developing and testing the proposed algorithm The new developed algorithm is different from other ARMA based optimal controls since it uses ARMA models for prediction of the structure response while existing algorithms predict the input excitation. Modeling the structure response as an AR or ARMA stochastic process is an effective mean for prediction of the structure response while avoiding measurement of the input excitation. ARMA models used in the algorithm enables it to avoid or reduce the time delay effect by predicting the structure response a few steps ahead. Being a closed loop control, the algorithm is suitable for all structural control conditions and can be used in a single control mechanism for vibration control of tall buildings against wind, earthquake or other random dynamic loads. Consequently the standby time is less than that for existing ARMA based algorithms devised only for earthquakes. This makes the control mechanism more reliable. The proposed algorithm utilizes and combines two different mathematical models. First model is an ARMA model representing the environment and the structure as a single system subjected to the unknown random excitation and the second model is a linear SDOF system which represents the structure subjected to a known past history of the applied control force only. The principle of superposition is then used to combine the results of these two models to predict the total response of the structure as a function of the control force. By using the predicted responses, the minimization of the performance index with respect to the control force is carried out for finding the optimal control force. As phase II, the proposed predictive control algorithm was extended to structures that are more complicated than linear SDOF structures. Initially, the algorithm was extended to linear MDOF structures. Although, the development of the algorithm for MDOF structures was relatively straightforward, during testing of the algorithm, it was found that prediction of the response by ARMA models can not be done as was done for SDOF case. In the SDOF case each of the two components of the state vector (i.e. displacement and velocity) was treated separately as an ARMA stochastic process. However, applying the same approach to each component of the state vector of a MDOF structure did not yield satisfactory results in prediction of the response. Considering the whole state vector as a multi-variable ARMA stochastic vector process yielded the desired results in predicting the response a few steps ahead. In the second part of this phase, the algorithm was extended to non-linear MDOF structures. Since the algorithm had been developed based on the principle of superposition, it was not possible to directly extend the algorithm to non-linear systems. Instead, some generalized response was defined. Then credibility of the ARMA models in predicting the generalized response was verified. Based on this credibility, the algorithm was extended for non-linear MDOF structures. Also in phase II, the stability of a controlled MDOF structure was proved. Both internal and external stability of the system were described and verified. In phase III, some problems of special interest, i.e. soil-structure interaction and control time delay, were investigated and compensated for in the framework of the developed predictive optimal control. In first part of phase III soil-structure interaction was studied. The half-space solution of the SSI effect leads to a frequency dependent representation of the structure-footing system, which is not fit for control purpose. Consequently an equivalent frequency independent system was proposed and defined as a system whose frequency response is equal to the original structure -footing system in the mean squares sense. This equivalent frequency independent system then was used in the control algorithm. In the second part of this phase, an analytical approach was used to tackle the time delay phenomenon in the context of the predictive algorithm described in previous chapters. A generalized performance index was defined considering time delay. Minimization of the generalized performance index resulted into a modified version of the algorithm in which time delay is compensated explicitly. Unlike the time delay compensation technique used in the previous phases of this investigation, which restricts time delay to be an integer multiplier of the sampling period, the modified algorithm allows time delay to be any non-negative number. However, the two approaches produce the same results if time delay is an integer multiplier of the sampling period. For evaluating the proposed algorithm and comparing it with other algorithms, several numerical simulations were carried during the research by using MATLAB and its toolboxes. A few interesting results of these simulations are enumerated below: ARM A models are able to predict the response of both linear and non-linear structures to random inputs such as earthquakes. The proposed predictive optimal control based on ARMA models has produced better results in the context of reducing velocity, displacement, total energy and operational cost compared to classic optimal control. Proposed active control algorithm is very effective in increasing safety and comfort. Its performance is not affected much by errors in the estimation of system parameters (e.g. damping). The effect of soil-structure interaction on the response to control force is considerable. Ignoring SSI will cause a significant change in the magnitude of the frequency response and a shift in the frequencies of the maximum response (resonant frequencies). Compensating the time delay effect by the modified version of the proposed algorithm will improve the performance of the control system in achieving the control goal and reduction of the structural response.

Les travaux de recherche présentés dans ce mémoire s'inscrivent dans le contexte du problème d'isolation par jonction dans les circuits intégrés de puissance. Certains modes de fonctionnement du bloc de puissance induisent une injection conséquente de courant parasite dans le substrat. La plus contraignante est l'injection de porteurs minoritaires. Nous en détaillons l'origine ainsi que ses conséquences dangereuses sur les circuits intégrés. Nous présentons les solutions de protection existantes destinées à réduire ce courant parasite. Avec la réduction des dimensions des nouvelles technologies, ces solutions de protection ne sont plus adaptées en raison de leur dimension. Nous proposons donc une méthodologie de conception basée sur la simulation physique 3D et la simulation électrique pour créer ou adapter des structures de protections selon la filière technologique utilisée. Avant de les développer, nous proposons d'étudier les mécanismes d'injection de ces porteurs minoritaires selon la nature du substrat utilisé. Ainsi, dans un substrat P+, des techniques de protection simples, c'est-à-dire les protections passives par anneaux de garde, peuvent réduire considérablement le courant parasite. Dans un substrat P-, des techniques de protection plus complexes doivent être développées. Nous avons proposé des structures de protections actives. Son efficacité contre le courant parasite est validée par la caractérisation de structures de test spécifiques. Une solution de protection intégrée dans le composant de puissance améliorant également la robustesse vis-à-vis des décharges électrostatiques, a été validée sur silicium et a fait l'objet d'un brevet.

Active control of sound radiation from vibrating structures has been an area of much research in the past decade. In Active Structural Acoustic Control (ASAC), the minimization of sound radiation is achieved by modifying the response of the structure through structural inputs rather than by exciting the acoustic medium (Active Noise Control, ANC). The ASAC technique often produces global far-field sound attenuation with relatively few actuators as compared to ANC. The structural control inputs of ASAC systems are usually constructed adaptively in the time domain based on a number of error signals to be minimized. One of the primary concerns in active control of sound is then to provide the controller with appropriate ``error'' information. Early investigations have implemented far-field microphones, thereby providing the controller with actual radiated pressure information. Most structure-borne sound control approaches now tend to eliminate the use of microphones by developing sensors that are integrated in the structure. This study presents a new sensing technique implementing such an approach. A structural acoustic sensor is developed for estimating radiation information from vibrating structures. This technique referred to as Discrete Structural Acoustic Sensing (DSAS) provides time domain estimates of the radiated sound pressure at prescribed locations in the far field over a broad frequency range. The structural acoustic sensor consists of a set of accelerometers mounted on the radiating structure and arrays of digital filters that process the measured acceleration signals in real time. The impulse response of each filter is constructed from the appropriate radiation Green's function for the source area associated with each accelerometer. Validation of the sensing technique is performed on two different systems: a baffled rectangular plate and a baffled finite cylinder. For both systems, the sensor is first analyzed in terms of prediction accuracy by comparing estimated and actual sound pressure radiated in the far field. The analysis is carried out on a numerical model of the plate and cylinder as well as on the real structures through experimental testing. The sensor is then implemented in a broadband radiation control system. The plate and cylinder are excited by broadband disturbance inputs over a frequency range encompassing several of the first flexural resonances of the structure. Single-sided piezo-electric actuators provide the structural control inputs while the sensor estimates are used as error signals. The controller is based on the filtered-x version of the adaptive LMS algorithm. Results from both analytical and experimental investigations are again presented for the two systems. Additional control results based on error microphones allow a comparison of the two sensing approaches in terms of control performance. The major outcome of this study is the ability of the structural acoustic sensor to effectively replace error microphones in broadband radiation control systems. In particular, both analytical and experimental results show the level of sound attenuation achieved when implementing Discrete Structural Acoustic Sensing rivaled that achieved with far-field error microphones. Finally, the approach presents a significant alternative over other existing structural sensing techniques as it requires very little system modeling.
Ph. D.

Le nord de l'algerie est affecte par une importante activite sismique localisee generalement sur les bordures des bassins d'age mio-plio-quaternaire. La ville alger a ete detruite a plusieurs reprises par de violents seismes (1365, 1674, 1716). La ville de blida, situee a 30 km au sw, a connu le meme sort en 1716 et en 1825. La localisation et les caracteristiques geometriques et cinematiques failles actives de la region d'alger et de la kabylie sont les objectifs de ce travail. L'utilisation combinee des modeles numeriques de terrain (mnt), de la teledetection (images satellites landsat tm et photos aeriennes) et des cartes geologiques de la region d'alger et de la kabylie nous permet de mettre en evidence des deformations quaternaires associees aux chevauchements des chainons de l'atlas tellien et du massif kabyle sur les bassins neogenes post-nappes a quaternaire. Cette analyse couplee a l'etude de la sismicite (historique et instrumentale) debouche sur les resultats suivants: 1) l'activite sismique de la region ouest d'alger est associee aux failles de menaceur-sidi yahia, hadjout-meurad, oued djer-lalla aicha, blida-bouinan, mahelma, attatba-berard et tipasa (bordure sud du bassin de la mitidja et sahel d'alger). 2) la kabylie, consideree jusqu'a present comme asismique montre, en fait, des deformations dans le quaternaire associees aux failles de draa el kremis-oued tamarir et de m'chidellah-akbou (vallee de l'oued sahel-soummam). L'analyse de ces deformations suggere que ces failles sont susceptibles de generer de tres forts seismes dont les intervalles de recurrence seraient bien superieurs a la periode historique. Ce travail debouche sur une evaluation des magnitudes maximales associees a ces failles actives et permet de localiser des sites potentiels pour de futures investigations paleosismologiques

This thesis investigates the possibility of controlling the response of a general multi-degree of freedom structure to a relatively distant blast load using passive and semi-active devices. A relatively distant blast is one that applies significant momentum to the structure, but does not destroy the face of the structure. Three multi-storey structures, and one single-storey structure, are modelled using non-linear finite elements with structural columns discretised into multiple elements to accurately capture the effects of higher order modes that are typically excited in such blast load responses. The single-storey model structure is subjected to blast loads of varying duration, magnitude and shape, and the critical aspects of the response are investigated over a range of structural periods in the form of blast load response spectra. The optimal device arrangements are found to be those that reduce the first peak of the structural displacement and thus also reduce the subsequent free vibration of the structure. For a given blast load, various passive and semi-active devices, as well as device architectures, are investigated. The optimal device architecture was found to be one that spanned approximately two-thirds the height of the structure. Depending on what damage parameters are considered critical for a given structure, different devices and arrangements are appropriate. The main factors in choosing a semi-active device and its control architecture, or arrangement, are the tradeoffs between permanent deflection, free vibration, base shear and device capacity limitations. Overall, the results present a first analysis on the effectiveness of semi-active devices and the unique force-displacement properties they offer for mitigating non-catastrophic blast loads.

Les interactions intermoléculaires entre une protéine et ses différents partenaires représentent des cibles de plus en plus prisées pour l'élaboration de composés thérapeutiques capables d'intervenir dans des processus biologiques. La méthode FBDD (Fragment-Based Drug Design) permet de concevoir des molécules bioactives tels que des inhibiteurs, à partir de la structure tridimensionnelle du complexe formé entre la protéine et une molécule fragment. Dans le cadre de ce projet de thèse nous proposons d'utiliser le déplacement chimique pour l'étude des structures 3D de ces complexes protéine-ligand. Nous nous focaliserons sur la mesure des perturbations de déplacement chimique CSP (Chemical Shift Perturbations) des atomes d'une protéine cible, induites par la liaison d'un fragment. Nous démontrerons la puissance de cet outil RMN à travers la simulation des CSP induits par l'interaction d'un fragment sur une protéine cible et leur comparaison aux CSP expérimentaux. L'analyse sera réalisée sur deux protéines cibles et la comparaison des données expérimentales et simulées permettra dans un premier temps de mettre en évidence un réarrangement structural de la protéine Bcl-xL lors de son interaction avec un fragment. Puis, dans un second temps, nous montrerons que cette analyse quantitative des CSP peut permettre de déterminer l'orientation des fragments dans le site d'interaction de la protéine PRDX5. Nous comparerons alors les performances de la méthode pour différents types de protons proposant ainsi de nouvelles pistes pour la compréhension du comportement des CSP vis-à-vis de leurs contributions électroniques
Intermolecular interactions between protein and its partners represent highly attractive targets for the elaboration of therapeutic compounds abble to interfere in biological processes. A novel approach in drug design called Fragment-Based Drug Design (FBDD) consists of designing bioactive molecules like inhibitors, from the 3D structure of the complex formed between a protein and a fragment molecule (MW < 300g/mol). Here we suggest using the chemical shift, to study these protein-ligand structures. We will particularly focus on the measurement of Chemical Shift Perturbations (CSP) induced by the fragment-binding on protein’s nuclei. We will evidence the potency of this NMR tool through simulation of CSP induced by fragment interaction on protein target and the comparison with experimental CSP. Two protein targets will be used and the comparison between experimental and simulated data will evidence on one hand, the structural rearrangement of the protein Bcl-xL upon fragment-binding. On the other hand, we will demonstrate that this quantitative use of CSP is unable to determinate fragment orientations inside the protein PRDX5 binding site. We will compare the performances of the method for different kinds of protein and proposing answers to better understand the behaviour of CSP toward their different electronic contributions

As the engineering profession moves from prescriptive or “deemed-to-satisfy” approaches towards design methodologies based on quantification of performance, sophisticated modelling tools are increasingly needed, especially when complex combinations of demand and capacity are encountered. Recourse is invariably made to advanced computational tools to provide high fidelity solutions to large and complex problems, such as the response of structural systems or components to thermomechanical actions. Software packages based on the finite element method are most commonly used for such analyses. There are some essential prerequisites to effective use of advanced computational software for complex nonlinear problems, which are often ignored, particularly in professional practice. These include a thorough understanding of the underlying mechanics of the problem under consideration; a good appreciation of the approximation methods for modelling the problem properly (e.g. the choice between elements, continuum or structural, low or high order interpolation, degree of mesh refinement necessary and so on); and perhaps most importantly ensuring that the software is reliable and is able to reproduce established fundamental solutions to an acceptable degree of accuracy. This thesis attempts to address most of these issues but focusses primarily on the last mentioned prerequisite and provides a range of novel and unprecedented fundamental solutions for beams, plates, and shallow shells subject to moderate or extreme thermomechanical loads such as those resulting from a fire. Geometric and material nonlinearities are included in the proposed formulations along with the most common idealised boundary conditions. Thermally induced deformations generate large displacements and require the solutions to account for geometric nonlinearity, while material nonlinearity arises from the degradation of the material at elevated temperatures. In the context of structural performance under extreme thermal action (such as fire), a finite element procedure is employed to analytically characterise generic temperature distributions through the thickness of a structural component arising from different types of fire exposure conditions including: a “short hot” fire leading to a high compartment temperature over a relatively short duration; and a “long cool” fire with lower compartment temperatures, but over a longer duration. Results have shown that despite the larger area under the long cool fire time-temperature curve, which traditionally represented the fire severity, the effect of the short hot fire on the nonlinear responses of beams, plates, and shallow shells is more pronounced. Also, the effect of temperature-dependent material properties is found to be more pronounced during the short hot fire rather than the long cool fire. Comparison studies have confirmed that while the current numerical and theoretical approaches for analysing of thin plates and shells are often computationally intensive, the proposed approach offers an adequate level of accuracy with a rapid convergence rate for such structures. The solutions developed can be used to: verify software used for modelling structural response to thermomechanical actions; help students and professionals appreciate the fundamental mechanics better; provide relatively quick solutions for component level analyses; and visualise internal load paths and stress trajectories in complex structural components such as composite shells that can help engineers develop deeper insights into the relevant mechanics. The formulations developed are versatile and can be used for other applications such as laminated composite or orthotropic shallow shells. A very significant by-product of developing such fundamental solutions is their potential use in the development of highly accurate hybrid elements for very efficient modelling of large problems. While this has not been fully developed and implemented in the current work, the requisite theoretical framework has been developed and reported in one of the appendices, which can be used to develop such elements and implement on an appropriate software platform.

This thesis represents the work that has been done by the author during his Master of Engineering Science candidature in the area of vibration control of flexible structures at the School of Mechanical Engineering, The University of Adelaide, between March 2003 and June 2004. The aim of this research is to further extend the application of the Spatial Control Approach for two-dimensional flexible structures for attenuating global structural vibration with the possible implication of reduction in noise radiation. The research was concentrated on a simply supported thin flexible plate, using piezoelectric ceramic materials as actuators and sensors. In this work, active controllers were designed for the purpose of controlling only the first five vibration modes (0-500Hz) of the plate. A spatial controller was designed to minimize the total energy of the spatially distributed signal, which is reflected by the spatial H2 norm of the transfer function from the disturbance signal to the vibration output at every point over the plate. This approach ensures the vibration contributed by all the in bandwidth (0-500 Hz) vibration modes is minimized, and hence is capable of minimizing vibration throughout the entire plate. Within the control framework, two cases were considered here; the case when the prior knowledge of the incoming disturbance in terms of reference signal is vailable and the case when it is not available. For the case when the reference signal is available, spatial feedforward controller was designed; whereas for the case when the reference signal is not available, spatial feedback controller was designed to attenuate the global disturbance. The effectiveness of spatial controllers was then compared with that of the standard point-wise controllers numerically and experimentally. The experimental results were found to reflect the numerical results, and the results demonstrated that spatial controllers are able to reduce the energy transfer from the disturbance to the structural output across the plate in a more uniform way than the point-wise controllers. The research work has demonstrated that spatial controller managed to minimize the global plate vibrations and noise radiation that were due to the first five modes.
Thesis (M.Eng.Sc.)--School of Mechanical Engineering, 2005.

This thesis explores the creation and assessment of semi-active control algorithms for both squat shear buildings and tall flexible structures. If cost-effective, practicable, semi-active structural control systems can be developed, the potential reduction in loss of both property and lives due to seismic events is significant. Semi-active controllers offer many of the benefits of active systems, but have power requirements orders of magnitude smaller, and do not introduce energy to the structural system. Previous research into semi-active controllers has shown their potential in linear simulations with single earthquake excitations. The distinguishing feature of this investigation is the use of appropriate non-linear modelling techniques and realistic suites of seismic excitations in the statistical assessment of the semi-active control systems developed. Finite element time-history analysis techniques are used in the performance assessment of the control algorithms developed for three and nine story structural models. The models include non-linear effects due to structural plasticity, yielding, hysteretic behaviour, and P-delta effects. Realistic suites of earthquake records, representing seismic excitations with specific return period probability, are utilised, with lognormal statistical analysis used to represent the response distribution. In addition to displacement focused control laws, acceleration and jerk regulation control methods are developed, showing that potential damage reduction benefits can be obtained from these new control approaches. A statistical assessment of control architecture is developed and undertaken, examining the distribution of constant maximum actuator authority for both squat shear buildings, and tall slender structures, highlighting the need to consider non-linear structural response characteristics when implementing semi-active control systems. Finally, statistical analysis of all results and normalised values shows the efficacy of each control law and actuator type relative to different magnitude seismic events. As a result, this research clearly presents, for the first time, explicit tradeoffs between control law, architecture type, non-linear structural effects, and seismic input characteristics for the semi-active control of civil structures.

The purpose of this thesis was to design controllers by using H1 and ¹
control strategies in order to suppress the free and forced vibrations of smart structures. The smart structures analyzed in this study were the smart beam and the smart ¯
n. They were aluminum passive structures with surface bonded PZT (Lead-Zirconate-Titanate) patches. The structures were considered in clamped-free con¯
guration. The ¯
rst part of this study focused on the identi¯
cation of nominal system models of the smart structures from the experimental data. For the experimentally identi¯
ed models the robust controllers were designed by using H1 and ¹
-synthesis strategies. In the second part, the controller implementation was carried out for the suppression of free and forced vibrations of the smart structures. Within the framework of this study, a Smart Structures Laboratory was established in the Aerospace Engineering Department of METU. The controller implementations were carried out by considering two di®
erent experimental set-ups. In the ¯
rst set-up the controller designs were based on the strain measurements. In the second approach, the displacement measurements, which were acquired through laser displacement sensor, were considered in the controller design. The ¯
rst two °
exural modes of the smart beam were successfully controlled by using H1 method. The vibrations of the ¯
rst two °
exural and ¯
rst torsional modes of the smart ¯
n were suppressed through the ¹
-synthesis. Satisfactory attenuation levels were achieved for both strain measurement and displacement measurement applications.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1995.
Includes bibliographical references (leaves 94-98).
by Julio Cesar Maldonado-Mercado.
M.S.

An analysis is presented on the use of a proof-mass actuator as a regenerative force actuator for the mitigation of earthquake disturbances in civil structures. A proof-mass actuator is a machine which accelerates a mass along a linear path. Such actuators can facilitate two-way power flow. In regenerative force actuation, a bi- directional power-electronic drive is used to facilitate power flow both to and from the proof-mass actuator power supply. With proper control system design, this makes it possible to suppress a disturbance on a structure using mostly energy extracted from the disturbance itself, rather than from an external power source. In this study, three main objectives are accomplished. First, a new performance measure, called the "required energy capacity," is proposed as an assessment of the minimum size of the electric power supply necessary to facilitate the power flow required of the closed-loop system for a given disturbance. The relationship between the required energy capacity and the linear control system design, which is based on positive position feedback concepts, is developed. The dependency of the required energy capacity on hybrid realizations of the control law are discussed, and hybrid designs are found which minimize this quantity for specific disturbance characteristics. As the second objective, system identification and robust estimation methods are used to develop a stochastic approach to the performance assessment of structural control systems, which evaluates the average worst-case performance for all earthquakes "similar" to an actual data record. This technique is used to evaluate the required energy capacity for a control system design. In the third objective, a way is found to design a battery capacity which takes into account the velocity rating of the proof-mass actuator. Upon sizing this battery, two nonlinear controllers are proposed which automatically regulate the power flow in the closed-loop system to accommodate a power supply with a finite energy capacity, regardless of the disturbance size. Both controllers are based on a linear control system design. One includes a nonlinearity which limits power flow out of the battery supply. The other includes a nonlinearity which limits the magnitude of the proof-mass velocity. The latter of these is shown to yield superior performance.
Master of Science

Cette thèse s’intéresse au problème du contrôle actif des vibrations structurelles d’une aile d’avion induites par le ballottement du carburant dans les réservoirs qu’elle contient. L'étude proposée ici est concentrée sur l'analyse d'un dispositif expérimental composé d'une longue plaque rectangulaire en aluminium équipée d'actionneurs et de capteurs piézoélectriques et d'un réservoir cylindrique. La difficulté principale réside dans le couplage complexe entre les modes de vibration de l’aile et les modes de ballottement du liquide. Un modèle de ce dispositif à l’aide d’équations aux dérivées partielles est tout d’abord construit. Ce modèle de dimension infinie couple une équation des plaques avec l'équation de Bernoulli pour le mouvement du fluide dans le réservoir. En analysant la contribution énergétique des modes, une approximation en dimension finie, de type espace d'état est alors construite. Après une méthode de recalage fréquentiel du modèle, un contrôle est réalisé en utilisant dans un premier temps une méthode par placement de pôle et dans un deuxième temps, la théorie de la commande robuste H-infini. La dimension du modèle et les performances demandées imposent le calcul d’un contrôleur H-infini d'ordre réduit, conçu en utilisant la librairie HIFOO 2. 0 et testé sur le dispositif expérimental pour différents niveaux de remplissage. Finalement, le problème de la correction simultanée avec un correcteur HIFOO d'ordre réduit est aussi analysé
We consider the problem of the active reduction of structural vibrations of a plane wing induced by the sloshing of large masses of fuel inside partly full tank. This study focuses on an experimental device composed of an aluminum rectangular plate equipped with piezoelectric actuators/sensors at the clamped end and with a cylindrical tip-tank, more or less filled with liquid, at the opposite free end. The control is performed through piezoelectric actuators and the main difficulty comes from the complex coupling between the flexible modes of the wing and the sloshing modes of the fuel. First, a partial derivative equation model is computed by coupling a plate equation with a Bernoulli equation for the fluid motion. After analyzing the energetic contribution of each mode, a state space approximation is established. After a model matching procedure, a control is computed by using the pole placement method and the H-infinity theory. Due to the large scale of the synthesis model and to the simultaneous performance requirements, a reduced-order H-infinity controller is computed using the HIFOO 2. 0 package and tested on the experimental device for different filling levels. Finally, the problem of simultaneous control with a reduced order HIFOO controller is tackled. Experimental results of this non-convex optimization problem are given and commented

The main focus of this study is on the active and semi-active control of civil engineering structures subjected to seismic excitations. Among different candidate control strategies, the sliding mode control approach emerges as a convenient alternative, because of its superb robustness under parametric and input uncertainties. The analytical developments and numerical results presented in this dissertation are directed to investigate the feasibility of application of the sliding mode control approach to civil structures. In the first part of this study, a unified treatment of active and semi-active sliding mode controllers for civil structures is presented. A systematic procedure, based on a special state transformation, is also presented to obtain the regular form of the state equations which facilitates the design of the control system. The conditions under which this can be achieved in the general case of control redundancy are also defined. The importance of the regular form resides in the fact that it allows to separate the design process in two basic steps: (a) selection of a target sliding surface and (b) determination of the corresponding control actions. Several controllers are proposed and extensive numerical results are presented to investigate the performance of both active and semi-active schemes, examining in particular the feasibility of application to real size civil structures. These numerical studies show that the selection of the sliding surface constitutes a crucial step in the implementation of an efficient control design. To improve this design process, a generalized sliding surface definition is used which is based on the incorporation of two auxiliary dynamical systems. Numerical simulations show that this definition renders a controller design which is more flexible, facilitating its tuning to meet different performance specifications. This study also considers the situation in which not all the state information is available for control purposes. In practical situations, only a subset of the physical variables, such as displacements and velocities, can be directly measured. A general approach is formulated to eliminate the explicit effect of the unmeasured states on the design of the sliding surface and the associated controller. This approach, based on a modified regular form transformation, permits the utilization of arbitrary combinations of measured and unmeasured states. The resulting sliding surface design problem is discussed within the framework of the classical optimal output feedback theory, and an efficient algorithm is proposed to solve the corresponding matrix nonlinear equations. A continuous active controller is proposed based only on bounding values of the unmeasured states and the input ground motion. Both active and semi-active schemes are evaluated by numerical simulations, which show the applicability and performance of the proposed approach.
Ph. D.

The reduction of the structure-borne road noise inside the cabin of an automobile is investigated using an Active Structural Acoustic Control (ASAC) approach. First, a laboratory test bench consisting of a wheel/suspension/lower suspension A-arm assembly has been developed in order to identify the vibro-acoustic transmission paths (up to 250 Hz) for realistic road noise excitation of the wheel. Frequency Response Function (FRF) measurements between the excitation/control electrodynamic shakers and each suspension/chassis linkages are used to characterize the different transmission paths that transmit energy through the chassis of the car. Secondly, a FE/BE model (Finite/Boundary Elements) was developed to simulate the acoustic field of an automobile cabin interior. This model is used to predict the acoustic field inside the cabin as a response to the measured forces applied on the suspension/chassis linkages. Finally, an implemented optimal active control algorithm using a feedforward structure to perform the simulation of an optimal active structural acoustic control (ASAC) by using experimental and numerical FRFs is presented. The control approach relies on the use of an electrodynamic actuator to modify the vibration behavior of the suspension and the automotive chassis such that its noise radiation efficiency is decreased. To predict the noise level reduction inside the passenger compartment, the measured FRFs of a control actuator, connected to the lower suspension A-arm, have been implemented by using the optimal active control algorithm in MATLAB ª . Its contribution to noise reduction has been evaluated in term of acoustic radiation efficiency, as measured by the sound pressure level (SPL) located at the driver's head.

[ES] Hoy en día, la arquitectura moderna está orientada principalmente al empleo eficiente de materiales tecnológicos y sostenibles, la tecnificación del proceso de diseño, proyecto y construcción, y la búsqueda de soluciones muy ligeras. Estas ideas se reflejan en las estructuras flexo-activas, que recientemente han atraído considerable atención como nuevo paradigma para construir estructuras ligeras, tanto en el ámbito de la investigación como en la práctica. El término "flexión activa" hace referencia a una categoría de estructuras en las que la flexión se emplea en el proceso de configuración de su forma. Los sistemas estructurales flexo-activos incluyen barras o láminas incurvadas cuya geometría es el resultado de su deformación elástica desde una configuración inicial recta o plana. Hasta el momento, el número de realizaciones es limitado; se trata sobre todo de aplicaciones experimentales con funcionalidad arquitectónica o artística. La obtención de la configuración de equilibrio es una de las principales dificultades que aparecen en la fase de concepción, debido precisamente a la no linealidad de la respuesta estructural de las barras activas, así como a la posible interacción con otros elementos estructurales como membranas o cables, que trabajan por forma, y cuya geometría no se puede fijar de modo arbitrario. Los métodos computaciones de determinación de forma para estructuras flexo-activas incluyen modelos de elementos finitos con cables virtuales no lineales que se acortan hasta alcanzar la configuración final, o algoritmos de relajación dinámica que consideran las variables que caracterizan la deformación de las barras activas. Esta tesis doctoral tiene por objeto proporcionar un análisis en profundidad de la aplicabilidad del principio de flexión activa al diseño de estructuras ligeras, en particular a los puentes peatonales. Para ello, la investigación se aborda desde tres puntos de vista: a) modelización computacional; b) eficiencia estructural; c) diseño y construcción. En primer lugar, se lleva a cabo una revisión de la bibliografía existente, haciendo hincapié en los trabajos previos en el diseño de pasarelas con flexión activa. En el campo de la modelización computacional, se desarrolla un novedoso método numérico de determinación de forma para estructuras flexo-activas basado en el modelo geométricamente exacto para piezas alargadas (también conocido como la teoría de vigas de Reissner-Simó). Distintos ejemplos numéricos han sido reproducidos para mostrar la exactitud del método. La parte de la investigación relacionada con el análisis de la eficiencia estructural se centra en el comportamiento del sistema flexo-activo propuesto en esta tesis para el diseño de estructuras ligeras: el arco flexo-activo arriostrado (o atirantado). Se trata de un arco plano compuesto por una barra flexible y continuo que se activa por la acción de los cables principales que tiran de ambos extremos de la varilla, y de los puntales o cables secundarios que desvían el cable principal y actúan en ciertas secciones transversales. La parte computacional-analítica se completa con el desarrollo de un procedimiento numérico basado en algoritmos genéticos, con el fin de obtener configuraciones estructurales eficientes. La tesis finaliza con el diseño, fabricación y montaje de una pasarela flexo-activa hecha con tubos PRFV utilizando este tipo estructural, realizada en el laboratorio de modelos de la Universitat Politècnica de València.
[CA] Hui dia, l'arquitectura moderna està orientada principalment a l'ús eficient de materials tecnològics i sostenibles, la tecnificació del procés de disseny, projecte i construcció, i la cerca de solucions molt lleugeres. Aquestes idees es reflecteixen en les estructures flexo-actives, que recentment han atret considerable atenció com a nou paradigma per a construir estructures lleugeres, tant en l'àmbit de la investigació com en la pràctica. El terme "flexió activa" fa referència a una categoria d'estructures en les quals la flexió s'empra en el procés de configuració de la seua forma. Els sistemes estructurals flexo-actius inclouen barres o làmines incorbades, la geometria de les quals és el resultat de la seua deformació elàstica des d'una configuració inicial recta o plana. Fins al moment, el nombre de realitzacions és limitat; es tracta sobretot d'aplicacions experimentals amb funcionalitat arquitectònica o artística. L'obtenció de la configuració d'equilibri és una de les principals dificultats que apareixen en la fase de concepció, degut precisament a la no linealitat de la resposta estructural de les barres actives, així com a la possible interacció amb altres elements estructurals com a membranes o cables, que treballen per forma, i la geometria de la qual no es pot fixar de manera arbitrària. Els mètodes computacions de determinació de forma per a estructures flexo-actives inclouen models d'elements finits amb cables virtuals no lineals que s'escurcen fins a aconseguir la configuració final, o algorismes de relaxació dinàmica que consideren les variables que caracteritzen la deformació de les barres actives. Aquesta tesi doctoral té per objecte proporcionar una anàlisi en profunditat de l'aplicabilitat del principi de flexió activa al disseny d'estructures lleugeres, en particular als ponts per als vianants. Per a això, la investigació s'aborda des de tres punts de vista: a) modelització computacional; b) eficiència estructural; c) disseny i construcció. En primer lloc, es duu a terme una revisió de la bibliografia existent, amb recalcament en els treballs previs en el disseny de passarel·les amb flexió activa. En el camp de la modelització computacional, es desenvolupa un nou mètode numèric de determinació de forma per a estructures flexo-actives basat en el model geomètricament exacte per a peces allargades (també conegut com la teoria de bigues de Reissner-Simó). Diferents exemples numèrics han sigut reproduïts per a mostrar l'exactitud del mètode. La part de la investigació relacionada amb l'anàlisi de l'eficiència estructural se centra en el comportament del sistema flexo-actiu proposat en aquesta tesi doctoral per al disseny d'estructures lleugeres: l' arc flexo-actiu esbiaixat (o lligat). Es tracta d'un arc pla compost per un membre flexible i continu que s'activa per l'acció dels cables principals que tiren de tots dos extrems de la vareta, i dels puntals o cables secundaris que desvien el cable principal i actuen en certa secció transversal de la vareta. La part computacional-analítica es completa amb el desenvolupament d'un procediment numèric basat en algorismes de tipus genètic, amb la finalitat d'obtindre configuracions estructurals eficients. La tesi finalitza amb el disseny, fabricació i muntatge d'una passarel·la flexo-activa feta amb tubs PRFV utilitzant aquest tipus estructural, realitzada en el laboratori de models de la Universitat Politècnica de València.
[EN] Nowadays, modern architecture is focused on the search of efficient uses of technological and sustainable materials, high-tech concept-design-erection processes and the possibility to produce lightweight solutions with maximum elegance in shape. These ideas are reflected on bending-active structures, which recently attracted considerable attention as a new paradigm to build lightweight structures both in research and practice. The concept 'active bending' refers to a category of structures in which bending is used in the process of shape configuration. Bending-active structural systems include curved rods or shells which have been elastically bent from an initial straight or plane configuration. As of now, the number of realisations is limited; they are mostly experimental ones, with architectural or artistic nature. Form finding of the equilibrium configuration is one of the main difficulties during the conceptual phase, due to the non-linearity of the structural response of the active members, and also to the interaction with other form-active structural elements as membranes or cables, whose geometry cannot be prescribed in advance. Computational form-finding methods for bending-active structures include finite element models with non-linear virtual links that are shortened to reach the final form, or dynamic relaxation (explicit) algorithms to cope with the variables describing the response of the active members. This PhD thesis aims to provide an indepth analysis on the applicability of the active bending principle to the design of lightweight structures, in particular pedestrian bridges. For that purpose, the work is carried out from three points of view: (a) computational modelling and simulation; (b) structural performance and efficiency; (c) design and construction. First of all, a literature review on the topic and a overview of realisations in the fied of bending-active footbridges is provided. In the field of computational modelling, a novel form-finding method based on the geometrically exact rod model (or Reissner-Simo beam theory) is implemented. Numerical examples are also given to show the accuracy of the method. The part of the work related to the analysis of the structural performance and efficiency is focused on the bending-active configuration proposed in this PhD thesis for designing lightweight structures: the bending-active braced (or tied) arch. This is a simple planar arch composed of a continuous flexible member that is activated by the action of main cables pulling at both ends of the rod, and secondary struts or cables that deviate the main cable and act at certain cross-section of the rod. The computational-analytical part is completed with the development of a numerical procedure based on genetic algorithms to obtain efficient structural configurations. The thesis ends with the design, fabrication and assembling of a bending-active short footbridge made of GFRP tubes using this structural type, held in the laboratory of concept models of the Polytechnic University of Valencia.
The author has had the opportunity to join the research project: Sistemas estructuras flexo-activos- Concepción, desarrollo y análisis de nuevos prototipos (FLEXACT - grant BIA2105-69330- P)
Bessini Muñoz, JG. (2021). Form-finding and Performance of Bending-active Structures. Proposals of Application to Lightweight Braced Arches [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/165575
TESIS

Active control of sound and vibration fields has become an strong area of research over the past few decades. In regards to the active control of acoustic radiation from vibration fields, known as active structural acoustic control (ASAC), there have been many different methods employed to understand structural and acoustic relationships and to control vibrations to limit the acoustic radiation. With active sound field control, sensors, usually microphones, need to be dispersed in the sound field, or an array of microphones must be placed directly in the sound field which, in many cases, uses up too much space for practical applications. To remedy this, objective functions have been transferred to the structure, sensing vibrations rather than pressures. A small, integrated array of structural sensors can be placed on the structure, reducing the system's overall footprint. Acoustic energy density has become a well established objective function, which produces a more global effect using only a local measurement. Another benefit of acoustic energy density lies in the breadth of sensor placement. While acoustic energy density has proven successful in active noise control (ANC), the quantity deals with pressures, not surface vibrations. The problem with ASAC is that an objective function with the robustness of acoustic energy density does not yet exist. This thesis focuses on a structural error sensing technique that mimics the properties of acoustic energy density control in the sound field. The presented structural quantity has been termed Vcomp, as it is a composite of multiple terms associated with velocity. Both analytical and experimental results with the control of this quantity are given for a rectangular plate. The control of Vcomp is compared to other objective function including squared velocity, volume velocity and acoustic energy density. In the analytical cases, the benefits include: control at higher structural modes, control largely independent of sensor location, and need for only a single point measurement of squared Vcomp with a compact sensor. The control at higher frequencies can be explained by the control of multiple acoustic radiation modes. Experimental results offer some validity to the analytical benefits but alternate sensing techniques need to be investigates to more fully validate these benefits.

The buckling of compressively-loaded members is one of the most important factors limiting the overall strength and stability of a structure. I have developed novel techniques for using active control to wiggle a structural element in such a way that buckling is prevented. I present the results of analysis, simulation, and experimentation to show that buckling can be prevented through computer-controlled adjustment of dynamical behavior.sI have constructed a small-scale railroad-style truss bridge that contains compressive members that actively resist buckling through the use of piezo-electric actuators. I have also constructed a prototype actively controlled column in which the control forces are applied by tendons, as well as a composite steel column that incorporates piezo-ceramic actuators that are used to counteract buckling. Active control of buckling allows this composite column to support 5.6 times more load than would otherwise be possible.sThese techniques promise to lead to intelligent physical structures that are both stronger and lighter than would otherwise be possible.