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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.
201

Hanging Load Mock-Up For Experimental Setup To Test Flight System Stability

Gundstedt, Anthony January 2023 (has links)
Can we reduce disturbance, swing, and errors by delegating some of the tasks to a subsystem on the tool hanging from a drone to gain precision and dependability? This project covers developing and implementing a user-controlled prototype with an automatic control system and gripper for functionality and controlled movement in 5 DOF. AirForestry is developing a new way of working in the forestry business to provide a greener and healthier solution for the soil and the environment. The forestry industry emits approximately one million tons of CO2 per year from heavy diesel-fueled vehicles. With a renewable energy battery-powered drone of a diameter of 6.2 m and a hanging harvesting tool, they can significantly improve the environmental impact of forestry. The harvesting tool has an automatic control system and is user controlled to perform the thinning and cutting of trees. The main focus is to use IMU sensor data to produce accurate angle estimation to control the stability of a scaled prototype and to implement physical restrictions to make it able to be attached safely and tested on a drone but not limit the controlled mobility of the prototype with a system independent of the control system of the drone itself. The user can control the attitude and elevation and receive real-time sensor data wireless during operation. With the intended spacing of the attachment points on the drone, it can prevent unwanted swing from a push or displaced drop. It uses the accelerometer on the IMUsensor to calculate the angle of roll and pitch, although the accelerometer is sensitive to vibrations and rotations. The control system has a fast response and rise time, but it experiences noise and oscillations. Sensor fusion of the accelerometer and gyroscope in a complementary filter can be implemented to increase the accuracy of the angle estimations and decrease the noise, which will be reflected in the speed of the servos and thereby improve the stability and mobility of the system.
202

NON-ISOTHERMAL NUMERICAL INVESTIGATIONS OF THE EFFECT OF SPEED RATIO AND FILL FACTOR IN AN INTERNAL MIXER FOR TIRE MANUFACTURING PROCESS

Ahmed, Istiaque 13 September 2018 (has links)
No description available.
203

A TOP-DOWN METHODOLOGY FOR SYNTHESIS OF RF CIRCUITS

VIJAY, VIKAS January 2004 (has links)
No description available.
204

Design of a Digitally Enhanced, Low Power, High Gain, High Linearity CMOS Mixer and CppSim Evaluation

Saidev, Sriram 28 September 2016 (has links)
No description available.
205

Design and Evaluation of an L-Band Current-Mode Class-D Power Amplifier Integrated Circuit

Shusta, Michael J 29 August 2014 (has links) (PDF)
Power amplifiers (PAs) convert energy from DC to high frequencies in all radio and microwave transmitter systems be they wireless base stations, handsets, radars, heaters, and so on. PAs are the dominant consumers of energy in these systems and, therefore, the dominant sources of system cost and inefficiency. Research has focused on efficient solid-state PA circuit topologies and their optimization since the 1960s. The 2000s saw the current-mode class-D (CMCD) topology, potentially suitable for today's wireless communications systems, show promise in the UHF frequency band. This thesis describes the design and testing of a high-efficiency CMCD amplifier with an integrated driver stage. In addition, analysis of a merged PA-mixer circuit based on the CMCD is provided.
206

UTBB FDSOI mosfet dynamic behavior study and modeling for ultra-low power RF and mm-Wave IC Design / Étude et modélisation du comportement dynamique du transistor MOS du type UTBB FDSOI pour la conception de circuits integrés analogiques à hautes fréquences et très basse consommation

El Ghouli, Salim 22 June 2018 (has links)
Ce travail de recherche a été principalement motivé par les avantages importants apportés par la technologie UTBB FDSOI aux applications analogiques et RF de faible puissance. L'objectif principal est d'étudier le comportement dynamique du transistor MOSFET du type UTBB FDSOI et de proposer des modèles prédictifs et des recommandations pour la conception de circuits intégrés RF, en mettant un accent particulier sur le régime d'inversion modérée. Après une brève analyse des progrès réalisés au niveau des architectures du transistor MOSFET, un état de l’art de la modélisation du transistor MOSFET UTBB FDSOI est établi. Les principaux effets physiques impliqués dans le transistor à double grille avec une épaisseur du film de 7 nm sont passés en revue, en particulier l’impact de la grille arrière, à l’aide de mesures et de simulations TCAD. La caractéristique gm/ID en basse fréquence et la caractéristique ym/ID proposée pour la haute fréquence sont étudiées et utilisées dans une conception analogique efficace. Enfin, le modèle NQS haute fréquence proposé reproduit les mesures dans toutes les conditions de polarisation y compris l’inversion modérée jusqu’à 110 GHz. / This research work has been motivated primarily by the significant advantages brought about by the UTBB FDSOI technology to the Low power Analog and RF applications. The main goal is to study the dynamic behavior of the UTBB FDSOI MOSFET in light of the recent technology advances and to propose predictive models and useful recommendations for RF IC design with particular emphasis on Moderate Inversion regime. After a brief review of progress in MOSFET architectures introduced in the semiconductor industry, a state-of-the-art UTBB FDSOI MOSFET modeling status is compiled. The main physical effects involved in the double gate transistor with a 7 nm thick film are reviewed, particularly the back gate impact, using measurements and TCAD. For better insight into the Weak Inversion and Moderate Inversion operations, both the low frequency gm/ID FoM and the proposed high frequency ym/ID FoM are studied and also used in an efficient first-cut analog design. Finally, a high frequency NQS model is developed and compared to DC and S-parameters measurements. The results show excellent agreement across all modes of operation including very low bias conditions and up to 110 GHz.
207

Dvojitě vyvážený směšovač – laboratorní přípravek / Doble-balanced mixer - laboratory equipment

Dušek, Libor January 2008 (has links)
The aim of this work was double-balanced mixer implementation, which will be used like laboratory equipment. This thesis deals with design of the double-balanced mixer from first theoretical principles to a practical design of a laboratory equipment. For the practical design the integrated mixer SA612 was used. Input signal to the mixer up to 500 MHz frequency can be used. For required operation external oscillator and fifth-order low pass filter were constructed. Oscillator was designed for fixed frequency 32 MHz. Fifth-order low pass filter was inserted between the mixer and the oscillator, because of filtering higher harmonics. The second aim of the work was measuring double-balanced mixer basic parameters, such as Compression Point (P-1dB) and Intercept Point (IP3). For the IP3 measurement, another one device was required. It consists of the power combiner for mixing two frequency close signals and third-order bandpass filter, which selects required frequency band. Finally, the laboratory equipment was fabricated and its real parameters were measured.
208

Mécanismes de dispersion de suspensions concentrées de silices nanométriques dans un élastomère : impact de la stratégie de mélange sur l'efficacité et la cinétique de dispersion / Mechanisms of dispersion for nanoscale and concentrated suspensions of silica in an elastomer : impact of the strategy of mixing on the efficiency and the kinetics of dispersion

Vincent, Frédéric 04 November 2011 (has links)
L’objectif de ce travail est une approche pluridisciplinaire dans le but de comprendre l’impact des phénomènes microscopiques, l’interaction charge-matrice avec ou sans agent de couplage et la dispersion des charges sur les propriétés macroscopiques. La caractérisation de l’impact de la stratégie de mélange avec ou sans un agent de couplage, la cinétique, l’état final et les différents scénarii de dispersion possibles sont ainsi étudiés. L’incorporation de microperles de silice dans une matrice SBR est réalisée dans un mélangeur interne. Finalement, la silice est dispersée à l’échelle nanométrique (10-100 nm). Les nanocomposites obtenus sont alors caractérisés par des techniques complémentaires (spectroscopie mécanique, MET, mesure du taux d’élastomère lié à la charge) dans le but de caractériser quantitativement les interactions charge-matrice et charge-charge. L’outil rhéologique est un outil très sensible pour caractériser l’évolution de la dispersion de charges dans une matrice élastomère. En particulier, le module de conservation G’ montre un plateau significatif pour les faibles fréquences de déformation. Ce plateau est très sensible à l’état de dispersion ainsi qu’à la nature des interactions entre les charges. En couplant les mesures rhéologiques, l'analyse d'image faite sur des photos MET et la mesure du taux d’élastomère lié, il est possible d’établir un scénario de dispersion de la silice dans l'élastomère en fonction des conditions de mélange et de mettre en évidence les paramètres élémentaires de la dispersion impliqués. En complément, la modélisation de certains modules montre toute sa pertinence dans la caractérisation de la rupture des agglomérats ou de l’évolution des interactions charge-charge au cours du mélangeage. Enfin, la dimension fractale des réseaux de charges obtenus est déterminée à partir de nos descripteurs de la dispersion / Filler dispersion in an elastomeric matrix, states and mechanisms of dispersion had to be investigated throughout the mixing process. This work focuses on a multidisciplinary approach to understand how microscopic phenomena, like rubber-filler interaction or filler dispersions, affect macroscopic properties such as rheological behavior. The incorporation of silica is realized in an internal mixer under temperature control. Finally, silica is dispersed at the nanoscale (10-100 nm). Afterwards, nanocomposites are characterized using complementary techniques in order to discuss quantitatively the nature of rubber-filler and filler-filler interactions and their effect on rheological properties. Thus, the global evolution of dispersion during the mixing is understood through these various tests. Different mechanisms in the dispersion have been observed. First, intense particle size reduction occurs at the earliest mixing times. Then, the aggregate size does not change while the amount of physically bound rubber at the surface of aggregate increases and levels off. For some silica, a second dispersion stage has been observed after the diffusion of the elastomer to the core of the aggregates. Rheology has showed to be a very sensitive tool to characterize the evolution of the dispersion in the system. Particularly, the complex shear modulus exhibits a significant plateau (Ge), at low frequency, which is very sensitive to the dispersion state and the nature of the interaction between the fillers. There is a striking correlation between the value of plateau Ge and the bound rubber content. Finally, a dispersion scenario has been established and fundamental interaction parameters have been identified
209

Validation de la chaîne d'émission pour la conception d'un capteur RF autonome

Thabet, Hanen 08 July 2013 (has links)
Ce travail s’inscrit dans un projet consistant à développer un prototype de capteur RF autonome et intelligent permettant la réalisation d’un réseau de capteurs sans fil dans un environnement industriel. Cette thèse traite de l’étude, la conception et la réalisation de la partie radiofréquence de la chaîne d’émission sans fils du capteur RF dans la bande ISM 863-870 MHz en technologie CMOS AMS 0.35µm. Cette chaîne inclut toutes les fonctions depuis l’oscillateur local jusqu’à l’amplificateur de puissance. L’émetteur occupe une surface de 0.22mm² et consomme environ 27mA sous une tension d’alimentation de 3.3V. De nombreux principes innovants ont été mis en œuvre et validés. Tous ces principes peuvent être facilement transposés à d’autres standards de communication et dans d’autres bandes de fréquences. Les résultats de simulations du dessin des masques vérifient complètement les spécifications et confirment les simulations. Une caractérisation expérimentale partielle valide les nouvelles architectures proposées. / This work joins in a project consisting in developing prototype of an autonomous and smart RF sensor allowing the realization of a wireless sensor network in an industrial environment. This thesis deals with the study, the design and the realization of the radio-frequency part of the transmitter using the 863-870 MHz ISM band and the CMOS AMS 0.35µm technology. This transmitter includes all the functions from the local oscillator to the power amplifier. The integrated circuit occupies a surface of 0.22mm² and consumes approximately 27mA under a supply voltage of 3.3V. Numerous innovative principles were implemented and validated. All these principles can be easily transposed into other standards of communication and in other frequency bands. The results of the post-layout simulation completely satisfy the specifications and confirm the simulations. Partial experimental characterization validates new architectures proposed.
210

Polymérisation in-situ en milieu fondu et sous écoulement élongationnel pour l'élaboration de nouveaux matériaux / In-situ melt polymerization under elongational flow for the development of new materials

Pierrot, François 13 September 2018 (has links)
Dans ce travail de thèse, des mélanges réactifs de polymères thermoplastiques immiscibles PMMA,PE et PS ont été réalisés dans un mélangeur (RMX®) qui génère principalement des écoulements élongationnels connus pour leurs pouvoirs distributifs et dispersifs même lorsque les composants ont une différence de viscosité importante. La polymérisation in-situ du styrène a été conduite par auto-polymérisation thermique et grâce à des amorceurs radicalaires. Différentes méthodes de préparations et paramètres de mélanges ont été testés puis évalués par l’analyse d’images de microscopie électronique. Les plus petits nodules de PS que nous avons obtenus ont un rayon moyen de l’ordre de 50 nm. Des mélanges binaires 90/10 à base de PS ou PE et d’un thermodur polyépoxyde (MDEA/DGEBA) ont également été réalisés. Les nodules sphériques les plus petits que nous avons obtenus ont un rayon moyen de l’ordre de 65 nm. / In this work, binary and ternary reactive blends based on immiscible thermoplastic polymers PMMA,PE and PS were realized. The in-situ polymerization of the styrene, precursor of PS, was led by thermal self-polymerization or still thanks to radical initiator. Blends were realized in a mixer named RMX who generates mainly extensional flows known for their distributive and dispersive skill even if components have an important viscosity difference. Various methods of preparation and parameters of mixtures were tested. Morphology was evaluated by the analysis of electronic microscopy images.The average radiuses of the dispersed PS phase were compared with those observed in the literature. The smallest that we obtained have an average radius of 50 nm. Binary mixtures 90/10 %m with PS or PE and with a thermodur polyepoxide (MDEA/DGEBA) were also realized. The smallest spherical nodules that we obtained have an average radius of the order of 65 nm.

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