<p> Tuned Liquid Dampers (TLDs) are increasingly being used to suppress the dynamic vibration of tall buildings. An equivalent mechanical model is essential for rapid analysis and design of a TLD. The most common TLD tank geometries are circular, annular and rectangular. Rectangular tanks are utilized for 1-D and 2-D TLDs, whereas circular and annular are usually applied to axisymmetric structures. The amount of fluid that participates in the sloshing motion is directly influenced by the tank geometry. Although not commonly used, a TLD having a curved-bottom tank is expected to perform more effectively due to its relatively large value of effective mass. The main objective of this study is to develop mechanical models for seven TLDs with different tank geometries including the curved-bottom case, and to theoretically investigate the performance of rectangular, vertical-cylindrical and horizontal-cylindrical TLDs.</p> <p> Potential flow theory, linear long wave theory, Lagrange's equations and virtual work method are employed to develop the equivalent mechanical model parameters of TLDs with rectangular, vertical-cylindrical, horizontal-cylindrical, hyperboloid, triangular, sloped-bottom, and parabolic tank geometries. A rectangular, vertical-cylindrical and horizontal-cylindrical TLD are selected for further study using a single-degree-of-freedom (SDOF) model and a two degree of freedom structure-TLD system model applying the derived equivalent mechanical parameters.</p> <p> The dynamic characteristics of the TLDs as a SDOF system are investigated. The mechanical model is verified by comparing calculated values with experimental results for a rectangular TLD. The free surface motion, sloshing force and energy dissipation are found to be dependent upon the excitation amplitude. Analytical results also indicate that the horizontal-cylindrical TLD possesses the greatest normalized sloshing force and energy dissipation among the TLDs considered.</p> <p> The performances of various TLDs installed in a structure are studied in terms of effective damping, efficiency and robustness. Tuning ratio, structural response amplitude, mass ratio and liquid depth are adjusted to investigate their affect on the performance of the studied TLDs. Performance charts are developed and subsequently used to present the results. It is found that small liquid depth ratio and large mass ratio can lead to a robust structure-TLD system with small relative motion ratio between the structure and the vibration absorber. Comparisons of performance between the three TLDs are made and it can be concluded that the horizontal-cylindrical TLD is the most robust and effective device with the smallest relative motion ratio.</p> / Thesis / Master of Applied Science (MASc)

Perú está ubicado en uno de los continentes que presentan mayor actividad sísmica causando muchas pérdidas humanas y daños excesivos en elementos estructurales y no estructurales, así mismo para disminuir estos movimientos sísmicos se ha estudiado un sistema de protección sísmica llamado Amortiguamiento de masa sintonizada con el fin de aumentar el desempeño sísmico, El edificio analizado es: las dos torres de Salaverry ubicado en la ciudad de Chiclayo del territorio Peruano, Dicho amortiguamiento de masa sintonizada se ha colocado en la parte final del edifico con el propósito de disminuir los desplazamientos laterales ,Los Análisis utilizados han sido el Estatico,Dinamico Y el Análisis tiempo historia cumpliendo también con los requisitos de la Norma E030 , Para el análisis tiempo historia se han seleccionado los sismos ocurridos en Piura el 18 de octubre de 2021 y el 3 de febrero Condorcanqui Amazonas y uno de los sismos más fuertes de Perú que es de lima 1974, de los resultados obtenidos se ha concluido que este sistema de amortiguamiento de masas sintonizada al incorporar a edificios reduce considerablemente los desplazamientos laterales, resultando ser uno de sistemas de protección sísmica favorable / Peru is located in one of the continents that present the greatest seismic activity, causing many human losses and excessive damage to structural and non-structural elements. Likewise, in order to reduce these seismic movements, a seismic protection system called Tuned mass damping has been studied in order to increase the seismic performance, The analyzed building is the two Salaverry towers located in the city of Chiclayo in the Peruvian territory, This tuned mass damping has been placed in the final part of the building with the purpose of reducing lateral displacements, The Analyzes used have been the Static, Dynamic and Time History Analysis, also complying with the requirements of Standard E030. For the time history analysis, the earthquakes that occurred in Piura on October 18, 2021 and February 3, Condorcanqui Amazonas and one of the strongest earthquakes in Peru, which is from Lima 1974, of the results obtained It has been concluded that this tuned mass damping system when incorporated into buildings considerably reduces lateral displacements, turning out to be one of the favorable seismic protection systems.

This works demonstrates the feasibility of the inverse-Class-F harmonic tuning approach for mm-wave silicon PAs. This research addresses the challenges and limitations of the high efficiency inverse-Class-F PAs for mm-wave silicon technology. This work proposes different load networks to mitigate the challenges which are verified with implementations at different mm-wave frequencies with the highest power efficiency performances reported so far: PAE= 50% @ 24 GHz, PAE = 43% @ 41 GHz, and PAE = 23% @ 94 GHz. The design methodology and detailed analysis of the proposed load networks presented and verified with implementation and measured results. / Ph. D.

This masters project describes properties and primary parameters of active function blocks (OPA, VCA, OTA, CFA, CC) usable in construction of harmonic oscillators. Basic principles of harmonic generators, especially feedback oscillators, are introduced. In next section are presented five particular schematics of harmonic tuned oscillators. For this oscillators are indicated basic formulas, essential qualities performed by simulations and results of sensitivity and tolerance analysis. In the last part of diploma thesis there are selected three circuits which are made and their features are measured.

Electromagnetic compatibility (EMC) is an essential part in today’s society and there are more products around us that emit electromagnetic waves than ever before. To make sure that all these products function properly under all circumstances EMC testing is needed. One test that is conducted is radiated immunity testing. A susceptibility antenna is needed to perform immunity testing. This thesis aims to show that a tuneable antenna could be used for immunity testing in the frequency band 26-150 MHz and in the future replace the current antenna, which is not tuneable, used at SAAB Support and Services EMC in Östersund. A simulation program called EZNEC+ was used to simulate different antennas that were tested in the semi-anechoic chamber at SAAB. Two antenna types showed better efficiency and reached lower in frequency than SAAB’s current antenna. These antennas were a bowtie antenna and an x-shaped antenna, both extending in only two spacial directions instead of the normal three. Their drawback was a less uniform E-field at the lowest frequencies, where the E-field was much stronger to the sides compared to straight in front of the antenna. This results in a narrow lobe width, but if this drawback could be accepted or mitigated both antennas are possible replacements for the current antenna at SAAB and should be further investigated.

This thesis presents a state-of-the-art-review and twodifferent approaches for solving the moving load problem ofcable-stayed and suspension bridges. The first approach uses a simplified analysis method tostudy the dynamic response of simple cable-stayed bridgemodels. The bridge is idealized as a Bernoulli-Euler beam onelastic supports with varying support stiffness. To solve theequation of motion of the bridge, the finite difference methodand the mode superposition technique are used. The second approach is based on the nonlinear finite elementmethod and is used to study the response of more realisticcable-stayed and suspension bridge models considering exactcable behavior and nonlinear geometric effects. The cables aremodeled using a two-node catenary cable element derived using"exact" analytical expressions for the elastic catenary. Twomethods for evaluating the dynamic response are presented. Thefirst for evaluating the linear traffic load response using themode superposition technique and the deformed dead load tangentstiffness matrix, and the second for the nonlinear traffic loadresponse using the Newton-Newmark algorithm. The implemented programs have been verified by comparinganalysis results with those found in the literature and withresults obtained using a commercial finite element code.Several numerical examples are presented including one for theGreat Belt suspension bridge in Denmark. Parametric studieshave been conducted to investigate the effect of, among others,bridge damping, bridge-vehicle interaction, cables vibration,road surface roughness, vehicle speed, and tuned mass dampers.From the numerical study, it was concluded that road surfaceroughness has great influence on the dynamic response andshould always be considered. It was also found that utilizingthe dead load tangent stiffness matrix, linear dynamic trafficload analysis give sufficiently accurate results from theengineering point of view. / QC 20100511

Le phénomène de résonance sol (PRS) est une instabilité pouvant survenir lorsque l’hélicoptère est au sol et le rotor est en marche ; elle peut vite aboutir à la destruction de l’appareil. L’origine de l’instabilité est un couplage entre les mouvements de roulis du fuselage posée sur le train d’atterrissage et le mouvement asymétrique de l’ensemble des pales dans le plan du rotor principal. Etudier théoriquement des alternatives de stabilisation par des absorbeurs de vibration linéaires (tuned mass dampers - TMD) et non linéaires (nonlinear energy sinks - NES) c’est le sujet de ce travail de thèse. Ces possibilités sont étudiées en ajoutant à un modèle minimal d’un hélicoptère à quatre pales identiques (rotor isotrope),précédemment étudié par l’équipe de l’ISAE, d’abord, un TMD au fuselage, puis des TMD identiques auniveau de l’articulation des pales du rotor. Ensuite, des dispositifs à raideur purement non linéaire (NES)sont considérées, d’abord, au fuselage, puis, aux pales du rotor (NES identiques). / Helicopter ground resonance (HGR) is an instability phenomenon that can occur when helicopters exhibit a spinning rotor when grounded; it can lead the structure to rapidly break apart. The phenomenon originates from a coupling between asymmetric modes of in plane blade oscillations (lead/ lag) and the roll of a grounded fuselage. The verification of alternative stabilization devices such as tuned mass dampers (TMD) and nonlinear absorbers (nonlinear energy sinks - NES) is the objective of this thesis. These possibilities are theoretically investigated by embedding a four-bladed helicopter minimal model - proposed and previously studied by the ISAE team - first, with a TMD in the fuselage, then with four identical TMDs in each blade lag hinge. Then, a NES attached to the fuselage is considered and eventually a set of four identical NES attached to the blade lag hinges of the model is proposed and analyzed.

Le présent travail traite l’optimisation des paramètres des amortisseurs à masses accordées (AMA) accrochés sur des structures, linéaires. Les AMAs sont des dispositifs de contrôle passif utilisés pour atténuer les vibrations induites par des chargements dynamiques (en particulier stochastiques) appliqués sur des structures. L’efficacité de tels dispositifs est étroitement liée aux caractéristiques dynamiques qu’on doit imposer à ces systèmes. Dans ce cadre, plusieurs stratégies d’optimisation peuvent être utilisées dans des contextes déterministes et non déterministes, où les paramètres de la structure à contrôler sont incertains. Parmi les différentes approches qu’on peut trouver dans la littérature, l’optimisation structurale stochastique (OSS) et l’optimisation basée sur la fiabilité (OBF) étaient particulièrement traitées dans le présent travail.Dans la première partie de ce travail, en plus de la nature stochastique des chargements extérieurs appliqués à la structure linéaire à contrôler, la présence de paramètres structuraux de type incertains mais bornés (IMB) est prise en considération et les bornes optimales des paramètres AMA ont été calculées. Le calcul de ces bornes a été fait en utilisant une technique basée sur un développement de Taylor suivi d’une extension aux intervalles. La technique, permettant l’obtention d’une approximation des bornes optimales, a été appliquée dans les cas d’un système à un degré de liberté (1DDL) et un autre à plusieurs degrés de libertés (nDDL). Les résultats obtenus ont montrés que la technique utilisée était bien adaptée pour la stratégie OSS et elle l’est moins pour l’approche OBF.Comme suite logique aux résultats de la première partie, la seconde partie de la présente dissertation est consacrée à la présentation de deux méthodes permettant l’obtention des bornes exactes et des bornes approximées des paramètres optimaux de l’AMA et ce, en présence de paramètres structuraux de type IMB. La première méthode est celle de la boucle d’optimisation continue imbriquée, la seconde est celle des extensions aux intervalles basées sur la monotonie. Les méthodes présentées, qui ont été appliquées avec l’approche OBF, sont valables pour n’importe quel problème d’optimisation faisant intervenir des paramètres de type IMB. Mis à part le calcul de bornes optimisées du dispositif AMA, la question de la robustesse, vis-à-vis des incertitudes structurales, a été également traitée et il a été prouvé que la solution optimale correspondante au contexte déterministe était la plus robuste.L’introduction d’une nouvelle stratégie OBF des paramètres AMA a fait l’objet de la troisième partie de cette dissertation. En effet, un problème OBF est toujours relié à un mode de défaillance caractérisé par le franchissement d’une certaine réponse, de la structure à contrôler, d’un certain seuil limite pendant une certaine durée de temps. Le nouveau mode de défaillance, correspondant à la nouvelle stratégie OBF, consiste à considérer qu’une défaillance ait lieu lorsque la puissance dissipée au niveau de la structure à contrôler, pendant une période de temps, excède une certaine valeur. Faisant intervenir l’approche par franchissement ainsi que la formule de Rice, la nouvelle stratégie a été appliquée dans le cas d’un système 1DDL et l’expression exacte de la probabilité de défaillance est calculée. En se basant sur une approximation mettant en œuvre la technique du minimum d’entropie croisé, la nouvelle stratégie a été, également, appliquée dans le cas d’un système à nDDL et les résultats obtenus ont montrés la supériorité de cette stratégie par rapports à deux autres tirées de la bibliographie. / The present work deals with the parameters optimization of tuned mass dampers (TMD) used in the control of vibrating linear structures under stochastic loadings. The performance of the TMD device is deeply affected by its parameters that should be carefully chosen. In this context, several optimization strategies can be found in the literature and among them the stochastic structural optimization (SSO) and the reliability based optimization (RBO) are particularly addressed in this dissertation.The first part of this work in dedicated to the calculation of the optimal bounds solutions of the TMD parameters in presence of uncertain but bounded (UBB) structural parameters. The bounds of the optimal TMD parameters are obtained using an approximation technique based on Taylor expansion followed by interval extension. The numerical investigations applied with one degree of freedom (1DOF) and with multi-degree of freedom (multi-DOF) systems showed that the studied technique is suitable for the SSO strategy and that it’s less appropriate for the RBO strategy.As immediate consequence of the obtained results in the first part of this work, in the second part a method, called the continuous-optimization nested loop method (CONLM), providing the exact range of the optimal TMD parameters is presented and validated. The numerical studies demonstrated that the CONLM is time consuming and to overcome this disadvantage, a second method is also presented. The second method is called the monotonicity based extension method (MBEM) with box splitting. Both methods have been applied in the context of the RBO strategy with 1DOF and multi-DOF systems. The issue of effectiveness and robustness of the presented optimum bounds of the TMD parameters is also addressed and it has been demonstrated that the optimum solution corresponding to the deterministic context (deterministic structural parameters) provide good effectiveness and robustness.Another aspect of RBO approach is dealt in the third part of the present work. Indeed, a new RBO strategy of TMD parameters based on energetic criterion is presented and validated. The new RBO approach is linked to a new failure mode characterized by the exceedance of the power dissipated into the controlled structure over a certain threshold during some interval time. Based on the outcrossing approach and the Rice’s formula, the new strategy is firstly applied to 1DOF system and exact expression of the failure probability is calculated. After that, a multi-DOF system is considered and the minimum cross entropy method has been used providing an approximation to the failure probability and then the optimization is carried out. The numerical investigations showed the superiority of the presented strategy when compared with other from the literature.

The aim of my master’s thesis was to create models of the damping device and observing their behavior in interaction with the structure. First was the construction separately modeled with Java application named FyDiK2D like a model with one degree of freedom. Model of construction takes form like a high, thin rod with full circular cross section. The lower part was restrained into the subsoil. The design was to verify the correct functionality of the model by comparing the analytical and numerical solutions. For capturing the precise behavior of the structure was converted to a multi-stage model. Then the pendulum damper was applied on this construction and found amplitude lies in highest point of multi-stage model. He was then replaced by tuned mass damper. By comparing these amplitudes from both dampers was found which kind of damper is efficient for multi-stage model.

Tato diplomová práce uvádí dynamiku klikového mechanismu šestiválcového řadového motoru za účelem návrhu klikového hřídele v CAD programu Pro/Engineer. Následuje popis vibrací klikového mechanismu a analytický výpočet jeho torzních vibrací. Hlavní část diplomové práce se pak zabývá konverzí hřídele do konečno-prvkového modelu v programu ANSYS a jeho importem do prostředí Adams/Engine. V tom je provedena modální analýza klikového ústrojí pro získání vlastních frekvencí a tvarů. Na konec práce je porovnán výstup z analytického řešení a výsledky z multi-body systému.