WorldCat Identities

École doctorale Sciences pour l'ingénieur et microtechniques (Besançon / Dijon) (Belfort)

Overview
Works: 773 works in 1,138 publications in 2 languages and 1,134 library holdings
Roles: Other, Degree grantor, 996
Publication Timeline
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Most widely held works by École doctorale Sciences pour l'ingénieur et microtechniques (Besançon / Dijon) (Belfort)
Modélisation et optimisation d'un récupérateur d'énergie vibratoire électromagnétique non-linéaire multimodale by Issam Abed( Book )

2 editions published in 2016 in French and held by 2 WorldCat member libraries worldwide

Afin d'accomplir les promesses des récupérateurs d'énergie vibratoire (VEHs) qui s'imposent comme une alternative majeure pour garantir l'autonomie des capteurs pour la surveillance, leurs performances en termes debande passante et puissance récupérable doivent être améliorées. Dans cette thèse, à la différence des VEHs classiques linéaires et multimodales ou non-linéaires et mono-fréquence, on propose une approche de récupération d'énergie basée sur des réseaux d'aimants couplés en lévitation ou élastiquement guidés combinant les avantages des non-linéarités et des interactions modales. Une étude bibliographique sur les récupérateurs d'énergie vibratoire est effectuée. En particulier, les inconvénients des récupérateurs linéaires et les techniques de réglage de fréquence sont présentées. De plus, les méthodes non-linéaires sont présentées pour définir une procédure de résolution permettant l'étude de la dynamique des récupérateurs non-linéaires. Les équations du mouvement qui contiennent la non-linéarité magnétique, la non-linéarité géométrique et l'amortissement électromagnétique sont résolus en utilisant la méthode de la balance harmonique couplée avec la méthode asymptotique numérique. Une méthodologie d'optimisation multi-objectif basée sur l'algorithme Non Sorting Genetic Algorithm est appliquée afin de calculer les solutions optimales pour maximiser les performances du récupérateur d'énergie. Grâce au couplage non-linéaire et aux interactions modales, pour le cas des trois aimants couplés, l'approche proposée permet la récupération de l'énergie vibratoire dans la gamme fréquentielle 4;6 - 14;5 Hz, avec une bande passante d'environ190 % et une puissance normalisée de 20,2 mWcm-3g-2
Elaboration et caractérisation de nano-composites XNBR / graphène pour des applications tribologiques by Imen Smaoui( )

2 editions published in 2017 in French and held by 2 WorldCat member libraries worldwide

[...]L'objectif de ce travail consiste à étudier dans un premier temps l'influence de l'incorporation de nanoparticules carbonées dans la matrice élastomère sur les propriétés rhéologiques, viscoélastiques et mécaniques. Dans un deuxième temps, l'impact de l'ajout du graphène et de ses dérivés sur les réponses en frottement et à l'usure des nanocomposites élaborés sera également exploré.Pour la concrétisation des objectifs visés à travers ces travaux de recherche, la démarche expérimentale retenue s'articule autour de trois parties.La première partie a été consacrée à la synthèse des nanoparticules notamment le graphène et l'oxyde de graphène. Les nanofeuillets d'oxyde de graphène (OGe) ont été obtenus via oxydation chimique du graphite suivie d'une exfoliation via sonification. Une réduction chimique ou thermique, s'en suit pour aboutir au nanofeuillets de graphène. Des techniques de caractérisation expérimentales ont confirmé que les nanofeuillets de graphène et d'oxyde de graphène ont été bien formés en large quantité avec une haute qualité structurale. Les échantillons nanocomposites ont été préparés en adoptant deux procédés de mélangeage différents notamment la méthode du mélange maitre et celle du mélangeage à l'état fondu.La seconde partie a été réservée à la caractérisation des nanocomposites élaborés par des essais de rhéologie couplés à des tests de gonflement afin de déterminer la densité de réticulation de la matrice XNBR en présence de la charge. L'évolution du module de conservation lors du balayage en déformation a été effectuée par spectrométrie mécanique. Ces mesures ont permis de mettre en évidence l'influence des interactions charge-charge et charge-matrice sur l'effet Payne. L'effet de l'incorporation de charges sur le comportement viscoélastique des échantillons a été également étudié. De plus, la caractérisation mécanique des nanocomposites a été réalisée au moyen d'essais de traction uni-axiale. Des analyses thermogravimétriques ont été conduites pour étudier l'effet de l'ajout du graphène et de ses dérivés sur la stabilité thermique des nanocomposites. En outre, des caractérisations microstructurales des nanocomposites par microscopie électronique à balayage (MEB) couplées à des spectres de diffractions aux rayons-X (DRX) ont été exécutées afin de vérifier l'état de dispersion de la charge dans la matrice.La troisième partie a été consacrée à l'étude du comportement tribologique des nanocomposites élaborés. Cette étude a été conduite sur un tribomètre rotatif de type pion/disque avec des observations microscopiques afin de mettre en évidence l'effet des particules sur les comportements en frottement et en usure des échantillons élaborés. Les mécanismes qui régissent l'usure des nanocomposites ont été identifiés à partir des résultats de la perte de masse et des micrographies des faciès d'usure
Classification de menaces d'erreurs par analyse statique, simplification syntaxique et test structurel de programmes by Omar Chebaro( Book )

2 editions published in 2011 in French and held by 2 WorldCat member libraries worldwide

Software validation remains a crucial part in software development process. Two major techniques have improved in recent years, dynamic and static analysis. They have complementary strengths and weaknesses. We present in this thesis a new original combination of these methods to make the research of runtime errors more accurate, automatic and reduce the number of false alarms. We prove as well the correction of the method. In this combination, static analysis reports alarms of runtime errors some of which may be false alarms, and test generation is used to confirm or reject these alarms. When applied on large programs, test generation may lack time or space before confirming out certain alarms as real bugs or finding that some alarms are unreachable. To overcome this problem, we propose to reduce the source code by program slicing before running test generation. Program slicing transforms a program into another simpler program, which is equivalent to the original program with respect to certain criterion. Four usages of program slicing were studied. The first usage is called all. It applies the slicing only once, the simplification criterion is the set of all alarms in the program. The disadvantage of this usage is that test generation may lack time or space and alarms that are easier to classify are penalized by the analysis of other more complex alarms. In the second usage, called each, program slicing is performed with respect to each alarm separately. However, test generation is executed for each sliced program and there is a risk of redundancy if some alarms are included in many slices. To overcome these drawbacks, we studied dependencies between alarms on which we base to introduce two advanced usages of program slicing : min and smart. In the min usage, the slicing is performed with respect to subsets of alarms. These subsets are selected based on dependencies between alarms and the union of these subsets cover the whole set of alarms. With this usage, we analyze less slices than with each, and simpler slices than with all. However, the dynamic analysis of some slices may lack time or space before classifying some alarms, while the dynamic analysis of a simpler slice could possibly classify some. Usage smart applies previous usage iteratively by reducing the size of the subsets when necessary. When an alarm cannot be classified by the dynamic analysis of a slice, simpler slices are calculated. These works are implemented in sante, our tool that combines the test generation tool PathCrawler and the platform of static analysis Frama-C. Experiments have shown, firstly, that our combination is more effective than each technique used separately and, secondly, that the verification is faster after reducing the code with program slicing. Simplifying the program by program slicing also makes the detected errors and the remaining alarms easier to analyze
Amélioration de la transmission de contenus vidéo et de données dans les réseaux sans-fil by Wassim Ramadan( Book )

2 editions published in 2011 in French and held by 2 WorldCat member libraries worldwide

This thesis deals in improving the data transfer on wireless networks and for the continuous data such as video. To improve transmission over wireless networks, we were interested in congestion control transport protocols and we also proposed a practical method for adjusting the video rate to network conditions.This thesis composes of two parts. The first part concerns the loss differentiation between congestion losses and losses on the wireless network. It is known that when there is a loss, transport protocols reduce the current sending rate (e.g. by two). However, for wireless losses, it has no interest in reducing the rate. To differentiate these losses on the data senders side, we propose a novel method that uses both the ECN (Explicit Congestion Notification) and the change of RTT of the packet following the loss. The second part proposes a novel method for video adaptation at the application layer of the sender. With the advent of high bitrate video (e.g. HD, 3D) and steadily increasing but irregular network bandwidth, video quality to the user lags. It is non-optimal (bitrate is highly smaller or larger than the available bandwidth) and not adaptable (to the dynamic conditions of the network). We propose a simple method to implement, since it requires a change only at the application layer of the sender. It adapts the bitrate of the video to the network conditions, i.e. it is a congestion control on the transmitter. Videoconferencing is an ideal case for the application of adaptation. This method works over any transport protocol with congestion control (e.g. TCP, DCCP), which also confers the property of TCP-friendliness
Effective simulation model and new control strategy to improve energy efficiency in hybrid electric land vehicle by Zainab Asus( Book )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

The main objectives of this work is to develop an effective modeling method for an easydeployment of a control strategy, to review and study an optimal control strategy for a specific application, and to analyze improvement that can be effected to engine for better efficiency in hybrid vehicle architecture. The scopes of this work include the simulation part of the studied system and its validation with experimental results. Study cases are used to analyze optimization that can be effected to the original system. A well established optimization tool is chosen to optimize the actual control strategy and becomes a benchmark of a new optimal control strategy to be deployed in the system. A predictive method to know energy consumption of the system is developed in order to obtain an optimal control suitable with the vehicle application. Using the developed model, analysis is conducted to identify an optimal control strategy for a specific utilization. As perspectives, the main components of the system can be studied for improvements of its energy efficiency. The Energetic Macroscopic Representation (EMR) is a good method to represent dynamic model and it can be used to model any electromechanical machines and can be envisaged to model other system than a vehicle system, like a renewable energy system, a new electro-mechanical system or a robotic system
Gestion de l'énergie et de la connectivité dans les réseaux de capteurs sans fil statiques et mobiles by Yacouba Ouattara( )

2 editions published in 2015 in French and held by 2 WorldCat member libraries worldwide

A number of works based on wireless sensor networks are interested in the energy management of these sensors. This energy is in fact a critical factor in the operation of these networks. Proper construction of sensor clusters is a great way to minimize the consumption of this energy. The problems related to these networks and often lies in their lifetime but also in the need to maintain connectivity between all transducers. These two aspects are closely linked. In this thesis, we focused on these two aspects in the context of static sensor networks but also of mobile sensors.We propose, as a _rst step, a hybrid algorithm for setting up clusters and the management of theseclusters. The uniqueness of this solution lies in the establishment of geographic areas for designation fcluster heads but also in transmission, in the exchanged messages, the amount of remaining energy on the sensors. Thus, the sensor data will designate the cluster heads and their successors will determine the thresholds for other sensors and for their operation. The algorithm is tested through many simulations. The second part of the work is to adapt our _rst algorithm for mobile sensor networks. We a_ect the trajectory of sensors to maintain connectivity and reduce energy consumption. For this, we are guided echo-location practiced by bats. We're interested in changing and dynamic topology in sensor networks. We analyzed the loss of energy as a function of the distance and the power transmission between the nodes and the head cluster. We also evaluate our algorithm on sensors that have a random move. We apply these algorithms to a _eet of surveillance drones simulation
Dimensionality reduction and saliency for spectral image visualization by Steven Le Moan( Book )

2 editions published in 2012 in French and English and held by 2 WorldCat member libraries worldwide

Nowadays, digital imaging is mostly based on the paradigm that a combinations of a small number of so-called primary colors is sufficient to represent any visible color. For instance, most cameras usepixels with three dimensions: Red, Green and Blue (RGB). Such low dimensional technology suffers from several limitations such as a sensitivity to metamerism and a bounded range of wavelengths. Spectral imaging technologies offer the possibility to overcome these downsides by dealing more finely withe the electromagnetic spectrum. Mutli-, hyper- or ultra-spectral images contain a large number of channels, depicting specific ranges of wavelength, thus allowing to better recover either the radiance of reflectance of the scene. Nevertheless,these large amounts of data require dedicated methods to be properly handled in a variety of applications. This work contributes to defining what is the useful information that must be retained for visualization on a low-dimensional display device. In this context, subjective notions such as appeal and naturalness are to be taken intoaccount, together with objective measures of informative content and dependency. Especially, a novel band selection strategy based on measures derived from Shannon's entropy is presented and the concept of spectral saliency is introduced
From quantitative spatial operators to qualitative spatial relationships : a new approach applied to the detection and the semantic qualification of 3D objects by Helmi Ben Hmida( Book )

2 editions published in 2012 in English and held by 2 WorldCat member libraries worldwide

This work presents the 3D Spatial Qualification tool (3DSQ) which was created tocompute spatial data stored in OWL-DL ontology. By using the adjustment principle ofan existing ontology, it is then possible to add 3D data to existing objects and computetheir spatial relationships from their 3D models. The 3DSQ Platform makes an attempt toensure the interaction between heterogeneous environments. Actually, such a semanticplatform connects an adjusted OWL ontology structure, a 3D quantification engine, avisualization engine and a set of geometry via knowledge processing technologymaterialized via SWRL, SQWRL rules and SPARQL queries within its extended Built-Ins. The created Spatial Built-Ins are connected to the presented quantification engine andenable qualifying semantic spatial relationships. This will mainly help us to not just applysemantic queries selecting geometry based on such a qualified relationship, but also tobenefit from the richness of the knowledge based schema, from a logical point of view. Itincludes the semantic definition and the implementation of the standard 3D spatialrelationships and uses sophisticated geometry data structure like NEF Polyhedra. Itfurther describes the implementation of the suggested bridge by the means of the NEFPolyhedra operation and the DLs definition of spatial relation.In addition, this thesis presents an application of the 3DSQ platform. It is argued that therepresentation of spatial information is not a fundamental limitation of OWL, wherelinking top level semantic qualification with low level quantitative calculation is highlypossible and efficient via the OWL-DL expressive power. This efficiency is carried outby the semantic rule system, and the geometry data structure required for therepresentation of spatial regions. In fact, such a semantic qualification based ondescription logic (DLs), and OWL ontologies enable much more efficient and intelligentspatial analysis semantically. To prove the feasibility and to validate the 3DSQ Platformwithin its quantitative and qualitative 3D spatial operators, real applied areas related toBuilding Information Model (BIM), IFC and especially 3D point clouds data wereaddressed. Given the complexity of the underlying problems, the suggested new methodsresort to using semantic knowledge, in particular, to support the object detection andqualification. In this context, a novel approach which makes use of the 3DSQ platformand benefits from intelligent knowledge management strategies to qualify objects will bediscussed. It is based on the semantics of different associated domains to assist inknowledge formalization where Knowledge helps in the qualification process, and can beclearly palpable through the thesis.Such a conception will bring solutions to the problem raised by the syntactic exchangelevel between CAD software packages, IFCs or 3D point cloud geometries. Moreover, allrelations between the different geometries are defined by elements suggested in thisthesis. In fact, these relations define how elements can interact. Such a semantic can onlybe synthetized, used and invested by OWL ontology structure with all the robustness ofthe Description Logics
Study of photonic crystals on thin film lithium niobate for sensing applications - design, fabrication and characterization by Wentao Qiu( )

2 editions published in 2016 in English and held by 2 WorldCat member libraries worldwide

Light is incredibly versatile for measuring all kinds of physical quantities :temperature, electric field (E-field), displacement and strain etc. Photonic sensors are promising candidates for the new generation of sensors developments due to their virtues of high sensitivity, large dynamic range and compact size etc. Integrated and on-fiber end photonic sensors on thin film lithium niobate (TFLN) exploring the electro-optic (EO) and pyro-electric effects are studied in this thesis in order to design E-field sensors and temperature sensors (T-sensors). These studies aim to develop sensors with high sensitivity and compact size. To achieve that aim, sensors that are made of photonic crystals (PhC) cavities are studied by sensing the measurand through the resonance wavelength interrogation method. In integrated sensor studies, intensive numerical calculations by PWE method, mode solving technique and FDTD methods are carried out for the design of high light confinement waveguiding structures on TFLN and suitable PhC configurations. Four types of waveguide (WG) structures (ridge WG, strip loaded WG, slot WG and double slot WG) are studied with a large range of geometrical parameters. Among them, slot WG yields the highest confinement factor while strip loaded WG is an easier option for realizations. Bragg grating is designed in slot WG with an ultra compact size (about 0.5µm×0.7µm ×6µm) and is employed to design PhC cavity. A moderate resonance Q of about 300 in F-P like cavity where the mirrors are made of PhC is achieved with ER of about 70% of the transmission. Theoretical minimum E-field sensitivity of this slot Bragg grating structure can be as low as 200 µV/m. On the other hand, Si3N4 strip loaded WG is designed with 2D PhC structure and a low resonance Q of about 100 is achieved. Fabrications of nano-metrical WG such as ridge WG Si3N4 strip loaded are demonstrated. However, the realization of nanometric components on LN presents a big challenge.In the on-fiber end sensor studies, guided resonance, oftentimes referred to as Fano resonance due to its asymmetric lineshape, is studied with different PhC lattice types. A Suzuki phase lattice (SPL) PhC presenting a Fano resonance at the vicinity of 1500 nm has been studied and demonstrated as temperature sensor with sensitivity of 0.77 nm/oC with a size of only 25 µm × 24 µm. In addition, guided resonances on rectangular lattice PhC have been systematically studied through band diagram calculations, 2D-FDTD and 3D- FDTD simulations
Contribution au pronostic d'une pile à combustible de type PEMFC : approche par filtrage particulaire by Marine Jouin( )

2 editions published in 2015 in French and held by 2 WorldCat member libraries worldwide

The development of new energy converters, more efficient and environment friendly, such as fuelcells, tends to accelerate. Nevertheless, their large scale diffusion supposes some guaranties in termsof safety and availability. A possible solution to do so is to develop Prognostics and HealthManagement (PHM) on these systems, in order to monitor and anticipate the failures, and torecommend the necessary actions to extend their lifetime. In this spirit, this thesis deals with theproposal of a prognostics approach based on particle filtering dedicated to PEMFCs.The reasoning focuses first on setting a formalization of the working framework and theexpectations. This is pursued by the development of a physic-based modelling enabling a state ofhealth estimation and its evolution in time. The state estimation is made thanks to particle filtering.Different variants of filters are considered on the basis of the literature and new proposals adaptedto PHM are proposed and compared to existing ones. State of health estimates given by the filter areused to predict the future state of the system and its remaining useful life. All the proposals arevalidated on four datasets from PEMFC following different mission profiles. The results show goodperformances for predictions and remaining useful life estimates before failure
Design, simulation and fabrication of a vertical microscanner for phase modulation interferometry - Application to optical coherence tomography system for skin imaging by Justine Lullin( Book )

2 editions published in 2015 in English and held by 2 WorldCat member libraries worldwide

This thesis describes the design, simulation and fabrication of a vertically actuated 4x4 array ofmicromirrors with embedded position sensing function. The vertical microscanner is meant to beintegrated within an array-type Mirau microinterferometer realized with optical microcomponentsfabricated using collective techniques. The microscanner, developed in this thesis, provides areference signal that is used for the implementation of phase modulation interferometery in an opticalcoherence tomography (OCT) system. This thesis first introduces the need for adapted imagingsystems for the early diagnosis of skin cancer and establishes the optical specifications requiredby this specific application. Based on these specifications, the design of the OCT system based onthe Mirau microinterferometer is presented. In parallel, the state of the art of the microactuationtechnologies is discussed and comb drive electrostatic actuation is chosen, for its compatibilitywith the design of the Mirau microinterferometer, to actuate and sense the position of the array ofmicromirrors. Then, the core of the thesis deals with the development of the vertical microscanner, i.e. its design and simulations, its fabrication and its characterization
Brillouin scattering in photonic crystal fiber : from fundamentals to fiber optic sensors by Birgit Stiller( Book )

2 editions published in 2011 in English and held by 2 WorldCat member libraries worldwide

Le cadre général dans lequel s'insère ce travail de thèse est celui de l'étude de la diffusion Brillouin dans une nouvelle génération de fibres optiques à cristaux photoniques (PCFs). Ces fibres, qui présentent un arrangement périodique de micro-canaux d'air parallèles le long de la fibre, possèdent en effet des propriétés optiques et acoustiques remarquables et inédites par rapport aux fibres conventionnelles. De façon plus précise, nous montrons dans ce travail, par le biais de simulations numériques et de données expérimentales, que les fibres à cristaux photoniques offrent la possibilité de supprimer ou, à contrario, augmenter les interactions entre les photons et les phonons. Dans une première partie, nous présentons une méthode de cartographie des fluctuations longitudinales de la microstructure des fibres PCFs à l'aide d'un capteur distribué basé sur une méthode innovante d'écho Brillouin. Cette méthode, très sensible et à haute résolution, est directement intéressante pour caractériser et améliorer l'uniformité des PCFs lors de leur fabrication et également pour la détection des différentes contraintes de température et étirement induites le long des fibres. Sur le plan fondamental, notre système de mesure distribuée à haute résolution nous a également permis d'observer, pour la première fois à notre connaissance, le temps de vie des ondes acoustiques dans les fibres à cristaux photoniques et les fibres standard. Par ailleurs, sur le plan technique, nous avons développé une architecture simplifiée de capteur distribué combinant la technique des échos Brillouin et celle de la modulation différentielle par déplacement de phase avec un seul modulateur d'intensité. Nos résultats montrent une résolution centimétrique dans la zone de soudure entre deux fibres optiques à l'aide d'une impulsion de phase de 500 ps. Nous démontrons dans une deuxième partie la suppression directe et passive de la rétrodiffusion Brillouin stimulée dans une fibre optique micro structurée en faisant varier périodiquement le diamètre de la microstructure. Une augmentation de 4 dB du seuil de puissance Brillouin a été obtenue avec une variation de seulement 7% sur une période de 30m. Ce résultat est très intéressant car la diffusion Brillouin est un facteur limitant dans les systèmes de télécommunications par fibre optique et les lasers à fibre. La troisième et dernière partie est consacrée à l'étude numérique et expérimentale de la diffusion Brillouin en avant dans les fibres à cristaux photoniques. En plus de la suppression de la plupart des modes acoustiques transverses, nous montrons que cette diffusion Brillouin est fortement augmentée pour certains modes acoustiques à haute fréquence qui sont piégés au cœur de la microstructure. Nous avons également étudié une fibre à structure multi-échelle qui révèle l'excitation sélective de plusieurs phonons acoustiques à des fréquences allant jusqu'a 2GHz. Ces mesures ont étés confirmées par des simulations numériques basées sur une méthode vectorielle aux éléments finis. L'impact des irrégularités de la microstructure a aussi été mis en évidence.Mots clés : optique non linéaire, diffusion Brillouin, fibres optiques microstructurées, seuil Brillouin, capteurs Brillouin distribués
Développement d'un traitement acoustique basses-fréquences à base de résonateurs d'Helmholtz intégrés à membrane électroactive by Ahmed Abbad( )

2 editions published in 2018 in French and held by 2 WorldCat member libraries worldwide

This main goal of the project consists in proposing a technological solution of an adaptive Helmholtz resonator with variable volume, which allows to overcome the mono-frequency character of passive Helmholtz resonators. The volume control is achieved by the use of an electroactive polymer membrane (EAP), allowing the resonances of the Helmholtz resonator to be tuned. The mechanical behavior of these materials changes when they are stimulated by an electric field. Significant improvements in acoustic transmission loss are obtained at low frequencies by two effects: the variation of stiffness of the membrane and the increase of volume due to the deformation of the membrane. Numerical, analytical and experimental studies are carried out to determine the potential of the proposed concepts. Finally, a periodic structure containing 9 adaptive resonators with electroactive membranes is studied in diffuse fields to evaluate the acoustic performances of the distributed concept
Analyse par des méthodes de “reverse engineering” de résonateurs piézoélectriques hautes performances et modélisation du bruit by Alok Pokharel( )

2 editions published in 2020 in English and held by 2 WorldCat member libraries worldwide

Les résonateurs à ondes acoustiques de volume (BAW) ont été étudiés dans le domaine temps-fréquence à FEMTO-ST depuis longtemps et ont montré un rôle essentiel dans de nombreuses applications métrologiques telles que dans les dispositifs de positionnement comme GPS, Glonass, Galileo, etc. Ce travail de thèse présente la technique passive utilisée pour des mesures du bruit de phase dans les résonateurs BAW à quartz. Les résonateurs BAW de hautes performances ont été fabriqués par plusieurs fabricants européens et fournis par le CNES pour une étude de “reverse engineering” durant cette thèse. Le manuscrit commence par rappeler les bases de cristallographie du quartz, de piézoélectricité et de caractérisation du bruit dans les résonateurs ultra-stables. La deuxième partie du travail donne des détails sur la mesure de bruit dans les résonateurs par une technique de suppression de porteuse et sur une adaptation pour les résonateurs LGT d'impédance très faible (< 10 ohms).La troisième partie concerne l'interprétation avec le modèle de Steven-Tiersten des résultats de mesures du bruit de phase à différentes températures et leur classification en fonction du bruit. Une simulation par méthode d'éléments finis (FEM) permet de comparer ces résultats avec la théorie de Steven-Tiersten. La quatrième partie, présente un test de modélisation du bruit de phase à l'aide d'un modèle d'intermittence. Des comparaisons de nos résultats avec la distribution de Mittag-Leffler ainsi que des distributions stables semblent indiquer un rejet du modèle d'intermittence en loi de puissance, dans notre cas. Enfin, le travail de “reverse engineering” est réalisé en démontant les résonateurs pour l'analyse des défauts par diffraction des rayons X et diffusion laser. Le démontage du résonateur a révélé des imperfections macroscopiques. Les résultats préliminaires de diffraction des rayons X montrent la présence de dislocations qui pourraient être une cause de bruit de phase dans les résonateurs. Ceci devra être confirmé sur d'autres résonateurs
Mécanismes de dégradation sous sollicitations hydrothermomécaniques de biocomposites et renforts en fibres végétales : application au développement de mobiliers urbains ultralégers et mobiles by Michael Berges( )

2 editions published in 2018 in French and held by 2 WorldCat member libraries worldwide

With the current environmental concerns, research turns to alternative solutions to synthetic fibres. Vegetal fibers appears as good candidates, with good mechanical properties. However, their low durability is a major issue, especially when the composites are exposed to hydro(hygro)thermal loadings.The purpore of this thesis is to analyse and understand the degradation mechanisms when hydro-thermo-mechanical loadings are applied, in order to implement a predictive modelisation of the composite durability.The manufacturing process wasstudied and optimised to produce reproducible and strong composites. Two materials were produced. Their only difference is their volumetric fiber contents (37.7 % and 51.1 %).Experimental campaigns were led to characterize the composite mechanical behavior under different loadings. A hydrothermal ageing was studied through monotonic mechanical testing and cyclic mechanical testing (fatigue) with in situ immersion. A hydrothermal ageing was also studied in order to be closer to the aimed service conditions.These differents test campaigns showed an important loss of mechanical properties with the ageing processes. The volumetric fiber contents also showed almost no difference after the hydrothermal ageing. The industrial use of a high fiber content can then be questionned.After the first hygrothermal cycle, the composite mechanical elastic properties were found constant, which is reassuring for an industrial use. However, damages accumulated throughout the first 4 cycles before stabilizing.Fatigue results showed that the saturation can enhance the fatigue resistance below a certain maximal loading, which is very interesting for the aimed industrial use.A surfacic numeric modelisation was implemented with the evolution of the mechanical properties thoughout the diffusion process. This modelisation showed that the composite is mostly in compression, which is expected from the constrained swelling of the fibers within the resin, but also showed some developpement ideas which would be necessary to achieve an accurate predictive modelisation. Among these ideas, strong coupling between the diffusion process and the internal strains/stresses of the components.Numerous perspectives were discussed. Multiaxial loadings or breakage mode with impact or creep tests were mentionned. Moreover, the predictive modelisation that was aimed was not achieved yet, but amelioration axes were identified
Analyse mathématique et numérique de modèles gyrocinétiques by Céline Caldini-Queiros( Book )

2 editions published in 2013 in French and held by 2 WorldCat member libraries worldwide

The main subject of this thesis is the gyro-kinetic equation. We present a rigourous developpement of the Vlasov equation limits with different collision operator in a strong magnetic field and numerical methods.We start with a study of the gyro-average operator. The average operator has been introduced by M. Bostan in the case of an equation where part of the transport is highly penalised. Then weapply our results at the two approximation we study : the finite Larmor radius approximation and the guiding-center approximation.We first focus on the precise and explicit computation of the Fokker-Planck-Landau operator average in the finite Larmor radius approximation. The Fokker-Planck-Landau operator containsconvolution and diffusion terms, it is then reasonable to first compute the average of the Boltzmann relaxation operator.We then focus on the guiding-center approximation and present a numerical scheme based on amicro-macro decomposition of the particles distribution fonction which comes from a joint workwith N. Crouseilles and M. Lemou. We obtain a scheme which is uniformly consistant with the continuous model for any order of the magnetic field. Numerical simulation based on this approach are presented. The last chapter of this thesis presents a project which was realised during the Cemracs 2012concerning the modelisation of blood flow in cerebral veins
Triskèle-Bot : étude et développement d'un robot parallèle continu pour le micro-positionnement by Benjamin Mauzé( )

2 editions published in 2021 in French and held by 2 WorldCat member libraries worldwide

Parallel Continuum Robots (PCR) are new structures that present great interest in terms of workspace or miniaturization, but they are not known for their precision. This thesis studies the potential of RPCs for high precision positioning requiring a consequent workspace. For this purpose, a new concept of planar RPC with 3 degrees of freedom called Triskèle-Bot, composed of a mobile platform and three flexible continuously deformable limbs driven by linear actuators, is proposed. To study its behavior, direct and inverse geometric models are created by a numerical resolution of a system of non-linear partial derivative equations (based on a Kirchhoff beam model) constrained to boundary conditions. A prototype is built to validate these models while offering intrinsic repeatability and an innovative way to measure the intrinsic and extrinsic parameters of the robot. A vision measurement protocol is proposed to minimize the numerous sources of uncertainty inherent to the microscopic scale, and thus obtain measurements of poses with less than ten nanometers of uncertainties. This protocol is used to experimentally measure the repeatability of the Triskele-Bot which reaches 9.13 nanometers in position and 0.71 microradians in orientation. A study of the robot's accuracy, resulting from an original strategy of calibration, is performed on several trajectories exhibiting values lower than 4 micrometers and 0.6 milliradians. All these results demonstrate the potential of PCR for micro-positioning applications
Composants à ondes élastiques de surface pour le filtrage à gabarits maîtrisés aux fréquences radios pour applications spatiales et professionnelles by Loïc Braun( Book )

2 editions published in 2015 in French and held by 2 WorldCat member libraries worldwide

This thesis deals with the development of surface acoustic wave devices (SAW) for filtering applications in the VHF and UHF bands. Several filter structures are studied. The first ones are longitudinally coupled resonator filters (LCRF) manufactured on Quartz with a relative pass-band narrower than 0,1 % centered at about 1 GHz. These filters have been fabricated and characterized, yielding less than 5 dB insertion loss with rejection levels in excess of 20 dB as predicted by our P-matrix model. One of these filters has been mounted in an oscillator to validate its characteristics.To improve the design of such filters, we have developed a model accounting for transverse mode contributions on their spectral function. Comparisons between theory and experiment emphasizes the accuracy of the developed model. We also have investigated impedance element and slanted transducers (fan-shaped) filter structures to produce filters with relative pass-band ranging from 1 to 15 % in the 100 - 300 MHz frequency range. For each type of filters, we have developed a model to predict their electrical response. A balanced-bridge filter configuration with a 2 % relative pass-band and four fan-shaped filters with pass-band larger than 10 % have been fabricated and characterized. Finally, we have studied two approaches for the development of SAW devices operating at frequencies in the vicinity of 3 GHz. The first approach exploits Diamond-based substrates, providing phase velocity higher than 5 km.s-1. The second one uses a nano-imprint lithography process to reduce the pitch of electrode gratings
Transition d'échelle entre fibre végétale et composite UD : propagation de la variabilité et des non-linéarités by Alessandra Del Masto( Book )

2 editions published in 2018 in French and held by 2 WorldCat member libraries worldwide

Although plant-fiber reinforced composites (PFCs) represent an attractive solution for the design of lightweight, high performance and low environmental cost structures, their development requires in-depth studies of the mechanisms underlying their nonlinear tensile behavior, as well as variability of mechanical properties. Given their multi-scale nature, this thesis aims to contribute, using a numerical approach, to the study of the propagation of behavior across the scales of PFCs. Firstly, the study focuses on the fiber scale: a 3D model of the behavior of the wall is first implemented in an EF calculation, in order to establish the influence of fiber morphology on the tensile behavior. Once the non-negligible impact of the morphology has been determined, a study of the links between morphology, material and ultrastructure and tensile behavior is conducted via a sensitivity analysis in the case of flax and hemp. The second part of the work is dedicated to the composite ply scale. A new stochastic multi-scale approach is developed and implemented. It is based on the definition of an elementary volume (VE) with random microstructure to describe the behavior of the ply. The approach is then used to study the sensitivity of VE behavior to nano, micro and mesoscopic parameters. Sensitivity analysis, conducted via the development of the response on the basis of polynomial chaos, allows us to construct a metamodel of the tensile behavior of the ply
Développement de cavités Fabry-Perot ultra-stables pour références de fréquence optique de nouvelle génération by Alexandre Didier( Book )

2 editions published in 2016 in French and held by 2 WorldCat member libraries worldwide

Les travaux présentés dans cette thèse portent sur le développement de références de fréquence optique, ou lasers ultra-stables. Ceux-ci sont obtenus en asservissant la fréquence d'un laser sur une cavité Fabry-Perot de haute finesse. Un premier laser est asservi sur une cavité commerciale en verre ULE et une stabilité relative de fréquence de 1; 9x 10-15 est obtenue à1 s. Ce signal optique est transféré dans le domaine des fréquences micro-ondes par un laser femto-seconde.Le signal obtenu à10 GHz dispose d'un bruit de phase de -104 dBc=Hz à1 Hz. Dans un second temps, une cavité ultra-compacte de 25 mm est développée. Des simulations par éléments finispoussées ont conduit à la fabrication d'une nouvelle géométrie de cavité, dotée de coefficients de sensibilité accélérométriques simulés inférieurs à10-12=(m=s2) selon toutes les directions. Une enceinte à vide compacte, munie d'un banc optique embarqué, a été réalisée de façon à limiter le volume du système complet à environ 40 L. Enfin, une cavité cryogénique en silicium a été conçue. Régulée à une température de 17 K, elle sera limitée par son bruit thermique à un palier de stabilité relative de fréquence de 3x10-17. Un cryogénérateur à faibles vibrations est utilisé pour atteindre cette température. Des modélisations par éléments finis de la cavité ont permis d'obtenir une sensibilité accélérométrique simulée de 4:5 x10-12=(m=s2)
 
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Alternative Names
École doctorale SPIM (Dijon ; Besançon ; Belfort)

ED 037

ED 37

ED SPIM

ED037

ED37

Languages
French (27)

English (13)