Tesi sul tema "Structures actives"
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El, Soufi Louay. "Contribution à la fabrication des structures thermoplastiques actives". Phd thesis, Université de Technologie de Belfort-Montbeliard, 2009. http://tel.archives-ouvertes.fr/tel-00604087.
Ignatov, Yury. "Phénomènes hyperfréquences et nonlinéaires dans les structures actives ferromagnétiques planaires". Phd thesis, Ecole Centrale de Lille, 2012. http://tel.archives-ouvertes.fr/tel-00741407.
Dellong, David. "Failles actives et structures profondes de la Marge Est-Sicilienne". Thesis, Brest, 2018. http://www.theses.fr/2018BRES0065/document.
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
LE, ROUZIC SOPHIE. "Sismotectonique des structures actives dans la zone de relais, philipines". Paris 7, 1999. http://www.theses.fr/1999PA077142.
Waibaye, Adoum. "Création de structures actives à l'aide d'alliages à mémoire de forme". Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22724/document.
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
BELLAHSENE, TOUNES. "Modélisation moléculaire de structures pharmacologiquement actives sur le diabète non-insulino-dépendant". Paris 7, 1997. http://www.theses.fr/1997PA077009.
Loret, Erwann-Philippe. "Spécificité et structures secondaires des toxines de scorpions actives sur les insectes". Aix-Marseille 2, 1990. http://www.theses.fr/1990AIX22004.
Vergnet, Fabien. "Structures actives dans un fluide visqueux : modélisation, analyse mathématique et simulations numériques". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS169/document.
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
Gardillou, Florent. "Etude et réalisation de structures hybrides actives/passives en optique intégrée sur verre". Grenoble INPG, 2005. http://www.theses.fr/2005INPG0166.
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
Silva, Sandrina Ribeiro Martins da. "1,3-Oxazoline-2-thiones saccharidiques : synthèse et réactivité de structures bio-actives originales". Thesis, Orléans, 2009. http://www.theses.fr/2009ORLE2083.
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
Wickham-Piotrowski, Alexander. "Anatomie des structures actives au voisinage de la zone de contact interplaque de l'Équateur : apport de la sismicité". Electronic Thesis or Diss., Université Côte d'Azur, 2023. http://www.theses.fr/2023COAZ4126.
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
Dussopt, Laurent. "Technologies et concepts nouveaux d'antennes planaires pour systèmes de communication : structures passives et actives". Nice, 2000. http://www.theses.fr/2000NICE5425.
Kerkeni, Ahmed. "Biofonctionnalisation de structures fibreuses en PET avec des molécules d'origine biologique". Valenciennes, 2010. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/bb36f1e7-0c95-4e23-a87a-f35de1435762.
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
Benouhiba, Amine. "Structures actives à base d'origami pour des résonateurs de Helmholtz adaptatifs et la robotique souple". Thesis, Bourgogne Franche-Comté, 2020. http://indexation.univ-fcomte.fr/nuxeo/site/esupversions/7921d54f-9fb5-4ad3-a9f3-ec1957ef443b.
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
Gosset, Christophe. "Mélange à quatre ondes dans les structures semi-conductrices actives et ses applications à la regénération". Paris, ENST, 2002. http://www.theses.fr/2002ENST0035.
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
Gosset, Christophe. "Mélange à quatre ondes dans les structures semi-conductrices actives et ses applications à la régénération /". Paris : École nationale supérieure des télécommunications, 2003. http://catalogue.bnf.fr/ark:/12148/cb39092096t.
GOLIAS, FRANCOIS. "Analyse electromagnetique globale de structures actives microruban a fonctionnement non-lineaire. Conception et caracterisation en bande millimetrique d'antennes imprimees passives et actives sur substrats a forte permittivite". Rennes, INSA, 1997. http://www.theses.fr/1997ISAR0005.
DAUGUET, STEPHANE. "Simulateur electromagnetique global de structures planaires actives. Modelisation des interconnexions. Analyse en regime lineaire et non lineaire". Rennes, INSA, 1997. http://www.theses.fr/1997ISAR0006.
Sankaran, Nithya. "Electromagnetic coupling in multilayer thin-film organic packages with chip-last embedded actives". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43621.
Keyhani, Ali. "A Study On The Predictive Optimal Active Control Of Civil Engineering Structures". Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/223.
Keyhani, Ali. "A Study On The Predictive Optimal Active Control Of Civil Engineering Structures". Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/223.
LAINE, Jean Philippe. "Mécanismes d'injection de porteurs minoritaires dans les circuits intégrés de puissance et structures de protections associées". Phd thesis, INSA de Toulouse, 2003. http://tel.archives-ouvertes.fr/tel-00011035.
Maillard, Julien. "Advanced Time Domain Sensing For Active Structural Acoustic Control". Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30335.
Ph. D.
Boudiaf, Azzedine. "Etude sismotectonique de la région d'Alger et de la Kabylie (Algérie) : utilisation des modèles numériques de terrains (MNT) et de la télédétection pour la reconnaissance des structures tectoniques actives : contribution à l'évaluation de l'aléa sismique". Montpellier 2, 1996. http://www.theses.fr/1996MON20060.
Ewing, Cameron. "Semi-active management of blast load structural response". Thesis, University of Canterbury. Mechanical Engineering, 2007. http://hdl.handle.net/10092/1225.
Aguirre, Clémentine. "Analyse quantitative des perturbations de déplacement chimique pour la détermination de structures tridimensionnelles de complexes protéine-ligand". Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10217/document.
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
Griffin, Steven F. "Acoustic replication in smart structure using active structural/acoustic control". Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/13085.
Toews, von Riesen Eduard. "Active hyperhelical structures". Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612458.
Davis, Denny E. "Optimization of transducers for active structural acoustic control of complex structures using numerical techniques". Thesis, Virginia Tech, 1995. http://hdl.handle.net/10919/40657.
Khazaeinejad, Payam. "Fundamental solutions for beams, plates, and shells under thermomechanical actions". Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/19575.
Lee, Yong Keat. "Active vibration control of a piezoelectric laminate plate using spatial control approach". Title page, abstract and table of contents only, 2005. http://hdl.handle.net/2440/37711.
Thesis (M.Eng.Sc.)--School of Mechanical Engineering, 2005.
Hunt, Stephen J. "Semi-active smart-dampers and resetable actuators for multi-level seismic hazard mitigation of steel moment resisting frames". Thesis, University of Canterbury. Mechanical Engineering, 2002. http://hdl.handle.net/10092/1256.
Ulker, Fatma Demet. "Active Vibration Control Of Smart Structures". Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/4/1098409/index.pdf.
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.
Chang, Min-Yung. "Active vibration control of composite structures". Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-09162005-115021/.
Pennington, Philip Nigel. "Active integrated optic waveguide/laser structures". Thesis, University of Bath, 1989. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760599.
Maldonado-Mercado, Julio Cesar. "Passive and active control of structures". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36654.
Includes bibliographical references (leaves 94-98).
by Julio Cesar Maldonado-Mercado.
M.S.
Tsai, Frank J. (Frank Jin-Fong) 1976. "Distributed active control for tension structures". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/81544.
Scruggs, Jeffrey. "Active, Regenerative Control of Civil Structures". Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/34332.
Master of Science
Robu, Bogdan. "Active vibration control of a fluid/plate system". Phd thesis, Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1103/.
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
Matheu, Enrique E. "Active and Semi-Active Control of Civil Structures under Seismic Excitation". Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30310.
Ph. D.
Zubi, Stephan al. "Active shape structural model". [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=97445107X.
Douville, Hugo. "An approach using active structural acoustic control for the reduction of structure-borne road noise". Mémoire, Université de Sherbrooke, 2004. http://savoirs.usherbrooke.ca/handle/11143/1223.
Bessini, Muñoz Juan Gabriel. "Form-finding and Performance of Bending-active Structures. Proposals of Application to Lightweight Braced Arches". Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/165575.
[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
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