Com a crescente necessidade de projetos cada vez mais econômicos, bem como a valorização dos terrenos nos grandes centros urbanos, que leva a conseqüente necessidade de aumentar o aproveitamento destes, e com o desenvolvimento das técnicas construtivas e dos processos de análise estrutural, as edificações tornaram-se mais altas, leves, flexíveis, menos amortecidas, e, portanto, mais susceptíveis a problemas de vibrações, inclusive as induzidas pela ação do vento. Nessa situação, o amortecimento natural da edificação pode tornar-se insuficiente para reduzir os movimentos causados pela ação do vento, o que pode gerar desconforto aos usuários, quebra de vidros e até mesmo danos à estrutura. Para se atingir a redução destes deslocamentos, em alguns casos, requer-se um suplemento adicional de amortecimento, para evitar tais movimentações excessivas. Tal suplemento de amortecimento é alcançado pela instalação de um sistema de dissipação de energia na edificação. Os atenuadores dinâmicos sintonizados constituem-se em um destes sistemas de dissipação de energia, sendo utilizados para aumentar o amortecimento geral do sistema estrutural. Foram realizados testes com um modelo do edifício alto padrão “CAARC Standard Tall Building”, primeiramente sem nenhum atenuador e após com dois tipos de atenuadores com características diferentes instalados no modelo. No trabalho são apresentados e discutidos os resultados dos ensaios, realizados no Túnel de Vento Professor Joaquim Blessmann, da Universidade Federal do Rio Grande do Sul. Os atenuadores dinâmicos sintonizados (amortecedores de massa) mostraram-se eficazes na redução das vibrações transversais por desprendimento de vórtices, validando o túnel de vento como ferramenta de projeto para a prevenção e controle de fenômenos associados às vibrações induzidas pelo vento. / With the increasing need of more economic buildings, as well as the great valorization of the terrains in the center of big cities, which leads to a consequent need to improve the utilization of this terrains, and with the development of the construction techniques and of the structural analysis process, the buildings have become higher, lighter, more flexible and less damped, and, therefore, more susceptible to problems of vibrations, such as those induced by wind action. On this new situation, the natural damping of the building could become insufficient to reduce the motion caused by wind action, which can lead to discomfort to the users, break of glasses and even damage to the structure. In order to obtain a reduction on this displacements, in some cases, an additional supply of damping is needed, to avoid this excessive movements. This supply of damping is obtained by the installation of an energy dissipation system on the building. The tuned mass dampers constitute on one of this systems of energy dissipation, being used to improve the overall damping of the structural system. Tests with a model of the “CAARC Standard Tall Building” were conduced, first with no damper attached to it, and then with two different types of tuned mass dampers installed on the model in each time. The results obtained with these tests, conduced on the Túnel de Vento Professor Joaquim Blessmann, at the Universidade Federal do Rio Grande do Sul are presented and discussed. In the tests, the tuned mass dampers have shown good efficiency in the reduction of the transversal vibration caused by vortex shedding, which validates the wind tunnel as a design tool for the control and prevention of the phenomena of wind-induced vibrations.

Com a crescente necessidade de projetos cada vez mais econômicos, bem como a valorização dos terrenos nos grandes centros urbanos, que leva a conseqüente necessidade de aumentar o aproveitamento destes, e com o desenvolvimento das técnicas construtivas e dos processos de análise estrutural, as edificações tornaram-se mais altas, leves, flexíveis, menos amortecidas, e, portanto, mais susceptíveis a problemas de vibrações, inclusive as induzidas pela ação do vento. Nessa situação, o amortecimento natural da edificação pode tornar-se insuficiente para reduzir os movimentos causados pela ação do vento, o que pode gerar desconforto aos usuários, quebra de vidros e até mesmo danos à estrutura. Para se atingir a redução destes deslocamentos, em alguns casos, requer-se um suplemento adicional de amortecimento, para evitar tais movimentações excessivas. Tal suplemento de amortecimento é alcançado pela instalação de um sistema de dissipação de energia na edificação. Os atenuadores dinâmicos sintonizados constituem-se em um destes sistemas de dissipação de energia, sendo utilizados para aumentar o amortecimento geral do sistema estrutural. Foram realizados testes com um modelo do edifício alto padrão “CAARC Standard Tall Building”, primeiramente sem nenhum atenuador e após com dois tipos de atenuadores com características diferentes instalados no modelo. No trabalho são apresentados e discutidos os resultados dos ensaios, realizados no Túnel de Vento Professor Joaquim Blessmann, da Universidade Federal do Rio Grande do Sul. Os atenuadores dinâmicos sintonizados (amortecedores de massa) mostraram-se eficazes na redução das vibrações transversais por desprendimento de vórtices, validando o túnel de vento como ferramenta de projeto para a prevenção e controle de fenômenos associados às vibrações induzidas pelo vento. / With the increasing need of more economic buildings, as well as the great valorization of the terrains in the center of big cities, which leads to a consequent need to improve the utilization of this terrains, and with the development of the construction techniques and of the structural analysis process, the buildings have become higher, lighter, more flexible and less damped, and, therefore, more susceptible to problems of vibrations, such as those induced by wind action. On this new situation, the natural damping of the building could become insufficient to reduce the motion caused by wind action, which can lead to discomfort to the users, break of glasses and even damage to the structure. In order to obtain a reduction on this displacements, in some cases, an additional supply of damping is needed, to avoid this excessive movements. This supply of damping is obtained by the installation of an energy dissipation system on the building. The tuned mass dampers constitute on one of this systems of energy dissipation, being used to improve the overall damping of the structural system. Tests with a model of the “CAARC Standard Tall Building” were conduced, first with no damper attached to it, and then with two different types of tuned mass dampers installed on the model in each time. The results obtained with these tests, conduced on the Túnel de Vento Professor Joaquim Blessmann, at the Universidade Federal do Rio Grande do Sul are presented and discussed. In the tests, the tuned mass dampers have shown good efficiency in the reduction of the transversal vibration caused by vortex shedding, which validates the wind tunnel as a design tool for the control and prevention of the phenomena of wind-induced vibrations.

Offshore wind turbines (OWTs) are becoming an accepted method for generating electricity. The environmental conditions of offshore locations often impose high wind and wave forces on OWTs making them susceptible to intense loading and undesirable vibrations. One method to reduce system vibrations is through the use of structural control devices typically utilized in civil structures. Tuned liquid column dampers (TLCDs) show great promise in the application to OWTs due to their high performance and low cost. This thesis examines the use of TLCDs in OWTs. Equations of motion for limited degree-of-freedom TLCD-turbine models are presented. A baseline analysis of each OWT is performed to generate a quantitative comparison to show how a TLCD would affect the overall dynamics of the system. The models are then subjected to two methods of testing. Optimal TLCD dimensions are derived for the models using a deterministic sweep method. The TLCD configurations examined include those with a uniform and non-uniform column cross-sectional area. The TLCD is shown to successfully reduce overall tower top displacement of each of the OWTs as well as the platform pitch when applicable. In some cases, use of the TLCD actually increases overall tower and platform motion. This thesis also examines the use of idealized tuned mass dampers (TMDs) in OWTs. Comparisons between the optimized TLCD and the idealized TMD are made with regards to motion reduction and parameter values.

Offshore wind turbines have the potential to be an important part of the United States' energy production profile in the coming years. In order to accomplish this wind integration, offshore wind turbines need to be made more reliable and cost efficient to be competitive with other sources of energy. To capitalize on high speed and high quality winds over deep water, floating platforms for offshore wind turbines have been developed, but they suffer from greatly increased loading. One method to reduce loads in offshore wind turbines is the application of structural control techniques usually used in skyscrapers and bridges. Tuned mass dampers are one structural control system that have been used to reduce loads in simulations of offshore wind turbines. This thesis adds to the state of the art of offshore wind energy by developing a set of optimum passive tuned mass dampers for four offshore wind turbine platforms and by quantifying the effects of actuator dynamics on an active tuned mass damper design. The set of optimum tuned mass dampers are developed by creating a limited degree-of-freedom model for each of the four offshore wind platforms. These models are then integrated into an optimization function utilizing a genetic algorithm to find a globally optimum design for the tuned mass damper. The tuned mass damper parameters determined by the optimization are integrated into a series of wind turbine design code simulations using FAST. From these simulations, tower fatigue damage reductions of between 5 and 20% are achieved for the various TMD configurations. A previous study developed a set of active tuned mass damper controllers for an offshore wind turbine mounted on a barge. The design of the controller used an ideal actuator in which the commanded force equaled the applied force with no time lag. This thesis develops an actuator model and conducts a frequency analysis on a limited degree-of-freedom model of the barge including this actuator model. Simulations of the barge with the active controller and the actuator model are conducted with FAST, and the results are compared with the ideal actuator case. The realistic actuator model causes the active mass damper power requirements to increase drastically, by as much as 1000%, which confirms the importance of considering an actuator model in controller design.

Platinautvinning är antagligen en av the farligaste gruvindustrierna. På följd av det har gruvmaskiner som Slotborer utvecklats för att göra utvinningsprocessen säkrare. Slotborern är ett ganska nytt koncept och har problem med vibrationer i borrsträngen när den blir längre.Den här rapporten föreslår fyra koncept för att dämpa/stabilisera dessa vibrationer och ett av dessa koncept var sedan vidare utvecklat efter en evaluering. Det koncept som vidareutvecklats använder sig av massdämpare för att dämpa/stabilisera borrsträngen. Massdämparna är justerbara vilket gör dem effektiva över ett större frekvensområde. Några mätvärden från riktiga borrningar var analyserade och analytiska och matematiska modeller var utvecklade att ha ett liknande beteende som det från mätningarna. Modellerna var sedan utvidgade och massdämparna var implementerade in i modellerna för att analysera deras effekt på systemet. När de analytiska modellerna för massdämparna vara klara nog, började konstruktions- och dimensioneringsarbetet av projektet. Dämparen/stabilisatorn var från början konstruerad för att direkt dämpa vibrationer på 2 – 5 Hz, men på grund av väldigt höga spänningar i massdämparna var frekvensspannet ändrat till 3,5 – 6-7 Hz. Ingen verifiering genom empiriska studier var gjorda men några bra analytiska resultat åstadkoms. / Platinum excavation is probably one of the most dangerous mining businesses. Because of that machines like the Slotborer has been developed to make the excavation process much safer. The Slotborer is a pretty new concept and has problems with oscillations in the drill string when it gets extended.This paper suggests four concepts for dampening/stabilizing these oscillations and one of these concepts was then further developed after an evaluation. The further developed concept uses mass dampers to dampen/stabilize the drill string. The mass dampers are adjustable making them effective for a wider range of frequencies. Some measurements from actual drilling operations was analyzed and analytical and mathematical models were developed to have a similar behavior of that from the measurements. The models was then extended and the mass dampers was applied into the models to analyze their impact of the system. When the analytical models for the mass dampers where done enough, the construction and dimensioning of the project took place. The damper/stabilizer was initially design to directly dampen oscillations between 2 – 5 Hz, but due to very high stresses in the mass dampers the dampening frequency span was changed to 3,5 – 6,7 Hz. No verification through empirical studies was made but some good analytical results of damping was achieved.

The short-term jitter and longer-term wander of the frequency sweep profile of a Vernier-Tuned Distributed Bragg Reflector (VT-DBR) laser at 1550 nm used in optical coherence tomography (OCT) and other sensing applications is characterized in this work. The VT-DBR has demonstrated success in source-swept OCT (SSOCT), performing both intensity and phase-sensitive OCT. The purpose of this paper is to investigate one of the unique aspects of the VT-DBR laser that makes it successful in OCT: the stability of the linear optical frequency sweep. A highly stable linear optical frequency sweep implies benefits for further fiber sensing applications including fiber Bragg grating and spectroscopy sensors. Short-term jitter measurements of the optical frequency sweep are taken using a 3-cavity 100 GHz free spectral range solid etalon, an athermal fiber Bragg grating, a molecular-based gas absorption reference cell, and a Mach-Zehnder interferometer. These four optical filters are used to convert time fluctuations into intensity fluctuations that can be measured by high speed optical receivers. Short term jitter values on the order of 0.5 – 0.6 pm RMS (63 – 82 MHz RMS) are typical values in the VT-DBR lasers systems characterized in this work. This level of jitter is compelling for OCT and fiber-sensing applications. Longer-term wander is characterized using a multiple-gas absorption reference cell. The long term stability and temperature insensitivity of the absorption cell is ideal for long-term wander characterization of the laser frequency sweeps. Wander values on the order of 2.6 pm of wavelength shift over an 8 hour time frame are reported in this work. The slope of the frequency versus time function of the laser sweep, on the order of 100 MHz/sample, is found to deviate by no more than 0.03% over the same 8 hour time frame. Both the long term wavelength shift and consistency of the slope indicate that these sources will perform well in OCT and fiber sensing applications. Mechanisms responsible for short-term jitter and longer- term wavelength wander likely include contributions from the laser source itself and from the high speed electronic drive circuitry that creates the wavelength ramp. Investigation of ambient temperature’s influence on the wavelength wander is also highlighted in the work.

As the demand for wireless electronics is increasing, more and more gadgets are connected wirelessly and devices are being improved constantly. The need of the new research and development for advance electronics with high performances is the priority. The data transfer rates are improved for faster communication and better efficiency is to reduce the battery consumption in handheld devices. This thesis presents three single-stage power amplifiers (PAs): class-AB, class-F and inverse class-F (class-F-1) at 28 GHz. The PAs have identical input networks: input matching, base DC feed, and base stabilizing networks. At the load side, there is a different load network for each PA. Class-AB PA load network has a single inductor with a parasitic capacitor to create a resonance at 28GHz. Class-F PA load network is composed of a parallel network (one LC tank in series with an inductor) and a series network (one 3f0-resonance LC tank in series with a capacitor) to create a multi-resonance load network. Class-F-1 load network is composed of a parallel network (two LC tank in series with an inductor) and a series network (one 2f0-resonance LC tank in series with a capacitor) to have a multi-resonance network. The main purpose of using multi-resonance load networks in class-F and class-F-1 is to shape the collector currents and voltages in order to achieve the highest efficiency possible. The chosen bias point is VCE=2.3V and ICE~12mA. As the results, class-AB PA achieves the peak PAE of 44%, 15 dBm OP-1dB, >19 dBm Psat , and 10 dB Gp. Class-F PA achieves the peak PAE of 46%, 14.5 dBm OP-1dB, ~18 dBm Psat , and 10 dB Gp. Class-F-1 PA achieves the peak PAE of 45%, 15.1 dBm OP-1dB, >18 dBm Psat , and 10 dB Gp.. In order to compare the linearity performances among three PA classes, a two-tone signal and a modulated signal with different modulation schemes (QPSK, 16QAM, 64QAM, and 256QAM) are applied to the PAs to produce IM3, ACPR, and EVM. After the analysis and comparison on efficiency and linearity, class-F PA gives the highest efficiency but has the worst linearity while class-AB has the best linearity but has the worst efficiency among three. Class-F-1 PA results lies in the middle of two other classes in term of efficiency and linearity. / Master of Science

D’immenses progrès ont été réalisés ces dernières années dans le champ de production de condensats de Bose-Einstein moléculaires pour l’obtention et le piégeage de molécules ultrafroides ioniques et neutres. Ces échantillons de molécules ultrafroides trouvent des applications dans des domaines très variés tels que les mesures pectroscopiques de haute précision ou bien encore le stockage de l’information quantique. La volonté d’optimiser les procédés de refroidissement et des techniques de piégeage a stimulé un grand nombre d’études théoriques. La plupart de ces études sont dédiées au refroidissement des molécules en collision avec un gaz tampon (3 He). La surface d’énergie potentielle de l’état fondamental du complexe de van der Waals He–MnH(X7Σ+) est présentée, suivie du calcul des états liés correspondant au complexe ainsi que l’étude de la relaxation Zeeman associée au système en fonction du champ magnétique appliqué. Dans le domaine de l’astrochimie, l’étude de la désexcitation rotationnelle de CH+ en collision avec l’hélium est également présentée. / Tremendous progress in experimental production and trapping of ultracold neutral and ionic molecules has been achieved over the past few years which even allowed the production of molecular Bose–Einstein condensates. These ultracold molecules samples have potential applications in many different fields, such as precision spectroscopic measurements or quantum information storage and processing. The optimization of the cooling processes and the trapping techniques also stimulated a great number of theoretical studies. Many of them are dedicated to inelastic scattering of molecules in collisions with 3He atoms (buffer gas cooling method). The potential energy surface of the ground state of the He–MnH(X7Σ+) van der Waals complex is presented, followed by the calculations of the bound states of this system and the Zeeman relaxation in function of the magnetic field. In the field of astrochemistry, a quantum mechanical investigation of rotational energy transfer in cold collisions of CH+ with 4He atoms is presented.

Suite à la mise en place de politiques publiques favorisant les énergies renouvelables, la construction de fermes éoliennes offshore est en plein essor aux quatre coins du monde. Or, la technique de l'éolienne offshore posée, la seule utilisée actuellement, n'est pas viable économiquement dans des eaux trop profondes. Ceci représente un sérieux frein au développement de l'énergie éolienne. Pour cette raison, la communauté scientifique s'intéresse depuis plusieurs années aux éoliennes sur plates-formes flottantes. En eau profonde, cette technologie est intéressante. Mais le fait que l'éolienne ne soit pas encastrée au fond de la mer augmente très significativement les sollicitations mécaniques induites par les vagues.Pour réduire ces sollicitations qui ont de nombreux effets néfastes, différentes approches sont possibles. Essayer de compenser les oscillations « avant-arrière » du mât de l'éolienne en pilotant la force de poussée exercée au niveau du rotor a déjà été écarté dans la littérature. Nous nous sommes concentrés sur l'ajout d'un dispositif de stabilisation interne à la plate-forme, de type Tuned Liquid Column Damper (un tube en U contenant un liquide, TLCD, encore appelé tube anti-roulis), utilisé dans d'autres contextes. Le dispositif que nous proposons est un dispositif actif où les paramètres du TLCD sont ajustés en temps réel, au cours du mouvement induit par les vagues. La mise à jour des paramètres suit une stratégie reposant sur une analyse des interactions entre le TLCD et la plate-forme (appelée ici barge) sur laquelle est installée l'éolienne. Nous avons modélisé le mouvement de la barge seul et son couplage avec le TLCD dans le plan grâce à une approche Lagrangienne. Nous avons étudié les effets des interactions du TLCD avec la barge dans le cas où le coefficient de perte de charge dans le tube était constant. Les limites de cette approche ont été détaillées grâce aux résultats classiques de la littérature sur les oscillateurs mécaniques couplés. Nous nous sommes ensuite concentrés sur une approche active consistant à modifier les caractéristiques du système en temps réel. Nous avons proposé des stratégies de type Linear Quadratic Regulator et de type Model Predictive Control agissant sur le coefficient de perte de charge. Dans un deuxième temps, les simulations nous ont ensuite permis d'écarter la commande MPC dont le rapport performance / complexité n'est pas favorable par rapport à la commande LQR dans ce cas précis.Une étude plus générale du système, en trois dimensions, nous a permis de vérifier que le TLCD classique dans sa version passive ou dans la version active que nous proposions n'est pas du tout robuste à l'incidence de la houle. Nous avons donc imaginé et modélisé des dispositifs inspirés du TLCD mais permettant d'amortir les oscillations de la houle de manière efficace, indépendamment de l'incidence de la houle. Nous avons nommé ces dispositifs TLMCD, pour Tuned Liquid Multiple Columns Damper.Les dispositif que nous proposons sont des systèmes TLMCD actifs. Ils sont conçus d'après les modélisations 3D que nous avons développées et une étude des coûts. Pour ces dispositifs, nous avons aussi détaillé les spécificités de la synthèse des stratégies LQR pour amortir les oscillations de la barge indépendamment de l'incidence de la houle.La performance de ces solutions d'amortissement a finalement été évaluée par simulation pour un large éventail de conditions de houle, couvrant les spécifications d'un “ cahier des charges ” que nous présentons. On observe une réduction des oscillations en roulis de la barge qui peut atteindre un facteur 4 par rapport à l'éolienne flottante sans TLCD. Ces résultats nous montrent que le dispositif TLMCD que nous proposons est un dispositif intéressant pour amortir de manière significative, robuste et économiquement abordable notre système. / Thanks to the recent policies of subsidizing renewables energies, constructions of offshore wind farms are booming all over the world. Yet, fixed-bottom wind turbine technology, the only one currently deployed, are too costly for deep waters. This hinders the development of wind power. This is why the scientific community has an interest in floating wind turbines (FWT). The cost of these wind turbines does not depend much on water depth. But since the wind turbine is not fixed into the seabed, the mechanical stress caused by the waves significatively raises.To reduce these detrimental loads, different approaches can be used. The litterature already discarded the control of the wind thrust applied on the rotor to compensate the "fore-aft" oscillations of the tower. We focused on stabilizing floating wind turbine by means of an attached damping system placed inside the float, it is a Tuned Liquid Column Damper (a U-tube containing a liquid, TLCD, also known as anti-roll tank), used in other areas. The damper we propose is an active system where TLCD parameters are continuously modified. Parameters are updated according to a strategy defined thanks to an analysis of the interactions between TLCD and the float (referred to as barge) supporting the wind turbine. We modelled the coupled dynamics of the barge and the TLCD in the vertical plan using a Lagrangian approach. We studied the motions of the damped system for a constant head-loss coefficient in the TLCD. The limits of this approach were detailed thanks to the classic results in double oscillators literature. Then, we focused on an active approach involving a time varying of the head-loss coefficient. We proposed Linear Quadratic Regulator and Model Predictive Control strategies to determine the head-loss coefficient. At a later stage, simulations enabled us to discard the MPC strategy as its complexity/performance ratio is rather bad compared to the LQR strategy in this particular case.A more general study of the system, in three dimensions, showed us that the TLCD is not robust against wave incidence. Therefore, we imagined and modeled new dampers inspired by the TLCD, which can damp the float effectively, regardless of the wave incidence. We named those dampers Tuned Liquid Multiple Column Damper (TLMCD).The dampers we propose are active TLMCD. Their designs are based on their dynamic properties and a cost study. We also detailed the specificities of LQR design to ensure the best possible robustness against wave incidence.The performance of the proposed TLMCD dampers was assessed through numerical simulations for a wide range of sea conditions. We observe that barge roll can be reduced by a factor of four compared to the undamped FWT. These results show us that the TLMCD we propose is interesting to damp significantly, robustly and economically our FWT.

Em um sistema came-seguidor a dinâmica do sistema seguidor faz com que o movimento final se desvie daquele especificado. Este efeito pode ser compensado considerando-se o modelo dinâmico inverso do sistema seguidor no projeto da lei de movimento do came. Considerando-se constante a velocidade do came, o sistema seguidor tem dinâmica linear. Entretanto, devido à razão de transmissão variável, e devido a outros efeitos não lineares, o sistema de acionamento como um todo é não linear, e procedimentos não lineares devem ser utilizados para se ajustar a lei de movimento do came. Uma análise teórica, suportada por simulações, mostra o potencial deste procedimento, ao menos no caso de uma dinâmica simples do sistema seguidor: uma considerável redução do erro de movimento, e uma boa robustez relativa a erros na freqüência de ressonância e razão de amortecimento estimadas. Experimentos com o acionamento por um servomotor sub-dimensionado, como é de se esperar, mostram resultados diferentes, devido à velocidade angular não constante. A flutuação observada na velocidade angular em torno do valor constante é então levada em consideração para o projeto da lei de movimento com nonlinear feedforward. / In a cam-follower system the dynamics of the follower-train mechanism cause an actual motion which deviates from the desired one. This effect can be compensated by taking into account the inverse dynamic model of the follower-train in the design of the cam motion law. By considering a constant cam velocity, the follower-train has linear dynamics. However, due to the varying transmission ratio, and due to other nonlinear effects, the whole drive train is a nonlinear system, and nonlinear procedures should be used to fit a motion law. A theoretical analysis with only the linear feed-forward compensation, supported by simulation results, has shown the potential of this approach, at least in the case of simple follower-train dynamics: a considerable reduction of the motion error, and a good robustness with respect to errors in the estimated resonance frequency and damping ratio of the follower-train. Experiments with a small driving servomotor, as expected, show differerit results, due to the non-constant angular velocity. The observed cam angular velocity ripple is then taken into account to design a complete nonlinear feedforward motion law.