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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Étude de la Morphologie et des Propriétés de Biocomposites Poly(3-Hydroxybutyrateco- 3-Hydroxyvalerate) (PHBV)/Farine de Grignons d’Olive / Study of the Morphology and Properties of Poly(3- hydroxybutyrate-co-3-hydroxyvalérate) (PHBV) / Olive Husk Flour Biocomposites.

Hassaini, Leila 13 December 2016 (has links)
Ce travail a pour objectif de développer des biocomposites à base de poly(3-hydroxybutyrate-co-3-hydroxyvalérate) (PHBV) et de farine grignons d'olive (FGO) préparés par mélange fondu. Il s'articule autour de quatre parties. La première partie comprend une étude de la morphologie et des propriétés physiques des échantillons biocomposites PHBV/FGO aux taux de charge de 10, 20 et 30% en masse. Les résultats indiquent que le système PHBV/FGO se caractérise par une séparation de phase dont le nombre et la taille des particules de FGO augmentent avec le taux de charge. De plus, la stabilité thermique et les propriétés barrières vis à vis de la vapeur d'eau et de l'oxygène ont diminué. Par contre, l'incorporation de la FGO dans le PHBV induit une augmentation du module d'Young qui s'accentue avec le taux de charge. La même tendance est également observée avec le module de conservation déterminé par DMA. Dans la seconde partie, l'impact du PHBV-g-MA comme agent compatibilisant dans les biocomposites PHBV/FGO a été évalué en fonction du taux de charge. La caractérisation morphologique du système ternaire a révélé que la présence du PHBV-g-MA dans les biocomposites PHBV/FGO induit une meilleure adhésion interfaciale entre les particules de la FGO et la matrice PHBV en raison des interactions charge-matrice. En conséquence, une nette amélioration des propriétés mécaniques, viscoélastiques et barrières aux gaz (vapeur d'eau et oxygène) est observée. Dans la troisième partie, une modification chimique de la FGO avec le trimethoxy (octadecyl)-silane (TMOS) et son influence sur la morphologie et les propriétés physiques de biocomposites PHBV/FGO: 80/20 ont été étudiées. Les résultats révèlent une dispersion fine et homogène de la FGO traitée au TMOS dans la matrice PHBV avec en apparence moins de microvides en comparaison avec le biocomposite non modifié. Les propriétés physico-mécaniques du biocomposite PHBV/FGO modifiée sont sensiblement améliorées. La dernière partie consacrée à une étude du vieillissement hygrothermique dans l'eau de mer à 25 et 40°C de films de biocomposites PHBV/FGO: 80/20 avant et après modification, révèle que la FGO favorise la cinétique de dégradation du système PHBV/FGO indépendamment du traitement. Toutefois, le biocomposite PHBV/FGO traité avec des organo-silanes se caractérise relativement par une résistance à la dégradation hygrothermique à 25 et 40°C par rapport au reste des échantillons biocomposites. / This work aims to develop a biocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyvalérate) (PHBV) and olive husk flour (OHF) prepared by melt compounding. It's articulated around four parts. The first part includes a study of the morphology and physical properties of the PHBV/OHF biocomposite samples at the loading rates of 10, 20 and 30 wt%. The results indicate that the PHBV/OHF system is characterized by a phase separation whose number and size of OHF particles increases with the loading rate. Moreover, the thermal stability and the barrier properties against water vapor and oxygen have decreased. On the other hand, the incorporation of the OHF in the PHBV matrix induces an increase in the Young's modulus which is accentuated with filler content. The same trend is also observed with the storage modulus determined by DMA. In the second part, the effects of PHBV-g-MA used as the compatibilizer for PHBV/OHF biocomposites were evaluated as a function of the loading rate. The morphological characterization of the ternary system revealed that the presence of PHBV-g-MA in the PHBV/OHF biocomposites induces better interfacial adhesion between the OHF particles and the PHBV matrix due to filler-matrix interactions. Consequently, a significant improvement in the mechanical, viscoelastic and gas barrier properties (water vapor and oxygen) is observed. In the third part, a chemical modification of OHF with trimethoxy(octadecyl)-silane (TMOS) and its influence on the morphology and physical properties of PHBV/OHF: 80/20 biocomposites was studied. The results reveal a fine and homogeneous dispersion of the TMOS-treated OHF in the PHBV matrix with apparently fewer microvides compared to the unmodified biocomposite. The physical and mechanical properties of the modified PHBV/OHF biocomposite are significantly improved. The last part devoted to a study of the hygrothermal aging in sea water at 25 and 40°C of films of biocomposites PHBV/OHF: 80/20 before and after modification reveals that the OHF promotes the degradation kinetics of the PHBV/OHF system regardless of treatment. However, the organo-silane-treated PHBV/OHF biocomposite is relatively characterized by a resistance to hygrothermal degradation at 25 and 40°C compared to the rest of the biocomposite samples.
2

Estimating Relative Position and Orientation Based on UWB-IMU Fusion for Fixed Wing UAVs

Sandvall, Daniel, Sevonius, Eric January 2023 (has links)
In recent years, the interest in flying multiple Unmanned Aerial Vehicles (UAVs) in formation has increased. One challenging aspect of achieving this is the relative positioning within the swarm. This thesis evaluates two different methods for estimating the relative position and orientation between two fixed wing UAVs by fusing range measurements from Ultra-wideband (UWB) sensors and orientation estimates from Inertial Measurement Units (IMUs). To investigate the problem of estimating the relative position and orientation using range measurements, the performance of the UWB nodes regarding the accuracy of the measurements is evaluated. The resulting information is then used to develop a simulation environment where two fixed wing UAVs fly in formation. In this environment, the two estimation solutions are developed. The first solution to the estimation problem is based on the Extended Kalman Filter (EKF) and the second solution is based on Factor Graph Optimization (FGO). In addition to evaluating these methods, two additional areas of interest are investigated: the impact of varying the placement and number of UWB sensors, and if using additional sensors can lead to an increased accuracy of the estimates. To evaluate the EKF and the FGO solutions, multiple scenarios are simulated at different distances, with different amounts of changes in the relative position, and with different accuracies of the range measurements. The results from the simulations show that both solutions successfully estimate the relative position and orientation. The FGO-based solution performs better at estimating the relative position, while both algorithms perform similarly when estimating the relative orientation. However, both algorithms perform worse when exposed to more realistic range measurements. The thesis concludes that both solutions work well in simulation, where the Root Mean Square Error (RMSE) of the position estimates are 0.428 m and 0.275 m for the EKF and FGO solutions, respectively, and the RMSE of the orientation estimates are 0.016 radians and 0.013 radians respectively. However, to perform well on hardware, the accuracy of the UWB measurements must be increased. It is also concluded that by adding more sensors and by placing multiple UWB sensors on each UAV, the accuracy of the estimates can be improved. In simulation, the lowest RMSE is achieved by fusing barometer data from both UAVs in the FGO algorithm, resulting in an RMSE of 0.229 m for the estimated relative position.

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