Current seismic design practice promotes inelastic response in order to reduce the design forces. By allowing the structure to yield while increasing the ductility of the structure, the global forces can be kept within the limited bounds dictated by the yield strength. However, during severe earthquakes, the structures undergo significant inelastic deformations leading to stiffness and strength degradation, increased interstory drifts, and damage with residual drift. The research presented in this thesis has three components that seek to address these challenges. To prevent the inelastic effects observed in yielding systems, a new concept “apparent weakening” is proposed and verified through shake table studies in this thesis. “Apparent weakening” is introduced in the structural system using a complementary “adaptive negative stiffness device” (NSD) that mimics "yielding” of the global system thus attracting it away from the main structural system. Unlike the concept of weakening and damping, where the main structural system strength is reduced, the new system does not alter the original structural system, but produces effects compatible with an early yielding. Response reduction using NSD is achieved in a two step sequence. First the NSD, which is capable of exhibiting nonlinear elastic stiffness, is developed based on the properties of the structure. This NSD is added to the structure resulting in reduction of the stiffness of the structure and NSD assembly or “apparent weakening”-thereby resulting in the reduction of the base shear of the assembly. Then a passive damper, designed for the assembly to reduce the displacements that are caused due to the “apparent weakening”, is added to the structure-thereby reducing the base shear, acceleration and displacement in a two step process. The primary focus of this thesis is to analyze and experimentally verify the response reduction attributes of NSD in (a) elastic structural systems (b) yielding systems and (3) multistory structures. Experimental studies on 1:3 scale three-story frame structure have confirmed that consistent reductions in displacements, accelerations and base shear can be achieved in an elastic structure and bilinear inelastic structure by adding the NSD and viscous fluid damper. It has also been demonstrated that the stiffening in NSD will prevent the structure from collapsing. Analogous to the inelastic design, the acceleration and base shear and deformation of the structure and NSD assembly can be reduced by more than 20% for moderate ground motions and the collapse of structure can be prevented for severe ground motions. Simulation studies have been carried on an inelastic multistoried shear building to demonstrate the effectiveness of placing NSDs and dampers at multiple locations along the height of the building; referred to as “distributed isolation”. The results reported in this study have demonstrated that by placing a NSD in a particular story the superstructure above that story can be isolated from the effects of ground motion. Since the NSDs in the bottom floors will undergo large deformations, a generalized scheme to incorporate NSDs with different force deformation behavior in each storey is proposed. The properties of NSD are varied to minimize the localized inter-story deformation and distribute it evenly along the height of the building. Additionally, two semi-active approaches have also been proposed to improve the performance of NSD in yielding structures and also adapt to varying structure properties in real time. The second component of this thesis deals with development of a novel device to control the response of structural system using adaptive length pendulum smart tuned mass damper (ALP-STMD). A mechanism to achieve the variable pendulum length is developed using shape memory alloy wire actuator. ALP-STMD acts as a vibration absorber and since the length is tuned to match the instantaneous frequency, using a STFT algorithm, all the vibrations pertaining to the dominant frequency are absorbed. ALP-STMD is capable of absorbing all the energy pertaining to the tuned-frequency of the system; the performance is experimentally verified for forced vibration (stationary and non-stationary) and free vibration. The third component of this thesis covers the development of an adaptive control algorithm to compensate hysteresis in hysteretic systems. Hysteretic system with variable stiffness hysteresis is represented as a quasi-linear parameter varying (LPV) system and a gain scheduled controller is designed for the quasi-LPV system using linear matrix inequalities approach. Designed controller is scheduled based on two parameters: linear time-varying stiffness (slow varying parameter) and the stiffness of friction hysteresis (fast varying parameter). The effectiveness of the proposed controller is demonstrated through numerical studies by comparing the proposed controller with fixed robust H∞ controller. Superior tracking performance of the LPV-GS over the robust H∞ controller in different displacement ranges and various stiffness switching cases is clearly evident from the results presented in this thesis. The LPV-GS controller is capable of adapting to the parameter changes and is effective over the entire range of parameter variations.

Liquid sloshing with unrestrained free surface in a moving container is associated with various engineering problems, such as tankers on highways, liquid oscillations in large storage tanks caused by earthquakes, sloshing of liquid cargo in ocean-going vessels, and the motion of liquid fuel in aircraft and spacecraft. The purpose of this study is to develop a three-dimensional (3D) numerical wave tank with or without internal structures to investigate the mechanism of liquid sloshing and the interaction between the fluid and internal structures. The developed 3D time-independent finite difference method is applied on solving liquid sloshing in tanks with or without the influence of baffles under the ground motion of six-degrees of freedom. The 3D Navier-Stokes equations were solved and transformed to a tank-fixed coordinate system, and the fully nonlinear kinematic and dynamic free surface boundary conditions for fluid sloshing in a rectangular tank with a square base were considered. The fluid is assumed incompressible in this study. The complicated interaction in the vicinity of the fluid-structure interface was solved by implementing one dimensional ghost cell approach and the stretching grid technique near the fluid-structure boundaries were used to catch the detailed evolution of local flow field. A PC-cluster was established by linking several single computers to reduce the computational times due to the implementation of the 3D numerical model. The Message Passing Interface (MPI) parallel language and MPICH2 software were utilized to code the computer codes and to carry out the circumstance of parallel computation, respectively. The developed numerical scheme was verified by rigorous benchmark tests. Not only the reported analytical, numerical and experimental studies were compared with the present numerical results, the experimental investigation was also involved in the present work to further validate the accuracy of the numerical scheme. All the benchmark tests of this study showed excellent accuracy of the developed numerical scheme. For a tank without internal structures, the coupled motions of surge and sway are simulated with various excitation angles, excitation frequencies and water depths. The characteristics of sloshing waves are dissected in terms of the classification of sloshing wave types, sloshing amplitude, beating phenomenon, sloshing-induced forces and energy transfer of sloshing waves. Six types of sloshing waves, named single-directional, diagonal, square-like, swirling-like, swirling and irregular waves, were found and classified in the present study and the occurrence of these waves are tightly in connection with the excitation frequency of the tank. The effect of excitation angle on the characteristics of sloshing waves is explored and discussed, especially for swirling waves. The spectral analyses of sloshing displacement of various sloshing waves are examined and a clear evidence of the correlation between sloshing wave patterns and resonant modes of sloshing waves are demonstrated. The mechanism of switching direction of swirling waves is discussed by investigating the situation of circulatory flow, the instantaneous free surface, the gravitational effect and the instantaneous direction of external forcing. The coupling effects of heave, surge and sway motions were also included in this study and the result showed an unstable influence of heave motion on the kinematic and dynamic characteristics of sloshing waves when the vertical excitation frequency of the tank is twice as large as the fundamental natural frequency. Except irregular waves, the other types of sloshing waves are converted into swirling waves due to the effect of heave motion. The study related to tuned liquid damper (TLD) in 2D and 3D tanks were considered. A comprehensive investigation for a 2D tank with vertically tank bottom-mounted baffles (baffled tank) are demonstrated and discussed with respect to the influence of baffle height on the natural mode of the tank, the evolution of vortices and vortex shedding phenomenon, the relationship between the vortex shedding frequency and the excitation frequency of the tank, the vortex size generated in the vicinity of the baffle tip, the interaction of vortices inside the tank. The baffle height shows a significant influence on the shift of the first natural frequency of the baffled tank and the liquid depth also plays an important part in determining this influence. In other words, the shift of the first natural mode due to various baffle height is varied with water depths. The design of two baffles separated by 0.2 times the tank breadth is an efficient tool to not only reduce the sloshing amplitude but switch the first natural frequency of the tank. The sloshing displacement is affected distinctly by different numbers of baffles mounted vertically on the tank bottom. The more baffles mounted onto the tank bottom, the smaller the sloshing displacement is presented in both the transient and steady-state periods. The processes of the evolution of vortices near the baffle tip are categorized into four phases: the formation of separated shear layer and generation of vortices, the formation of a vertical jet and shedding of vortices, the interaction between shedding vortices and sloshing flow (the generation of snaky flow) and the interaction between snaky flow and sloshing waves. Vortex shedding phenomenon due to stronger vertical jets occurs when the excitation frequency is close to the first natural mode of the baffled tank. The size of the vortex generated near the baffle tip is discussed and the vortex size is closely correlated with the baffle height. Two types of 3D tuned liquid dampers, a vertically tank bottom-mounted baffle and a vertical plate, are discussed for a tank under coupled surge-sway motions. The wave types of diagonal and single-directional waves switch to the swirling type due to the influence of the baffle. The phenomenon of square-like waves or irregular waves coexisting with swirling waves is found in the baffled tank under diagonal excitation. The baffle and the vertical plate mounted parallel to the east (west) wall of the tank can effectively reduce the sloshing amplitude when the excitation angle is between 0 degree and 10 degree and the corresponding sloshing displacement in the sway (z) direction becomes more dominant with the increase of the excitation angle. The shift of the first natural mode of the baffled tank due to various baffle heights in the x direction is dominated in this design of baffled tank. The length of the plate can cause a significant influence on not only the variation of the natural frequencies but the type of the sloshing waves. The influence of the vertical plate on the irregular waves is insignificant and several peaks appear in the spectral analysis of the sloshing displacement for the irregular waves and the numbers of peaks are more than that of the baffled tank.

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.

Le piano, instrument de musique occidental, détient une position historique unique dans la musique persane. La musique d’Iran est constituée à partir d’un repértoire canonique classique qui fait état de caractéristiques transmises de génération en génération, avec quelques innovations apportées au fil du temps. Lorsque des échelles musicales ont été portées sur un piano à Téhéran dans les années 1870, les membres de la cour impériale étaient le seul public témoin de l’évènement. À l’époque, Sorourolmolk, musician du palais Qajar sous le règne de Nāsseredin Shah Qajar (1848-1896), a tenté de changer l’accordage du piano et de jouer les airs traditionnels persans, inspirés par les techniques du santur et du tār. Ainsi, la pratique du piano en Iran a immédiatement été associée à la musique qui existait déjà depuis des générations. On parlera alors de “piano persan.” Plus tard, l’élite instruite de la société et les étudiants de la première école de musique militaire à Téhéran (Sho’beh-ye Music-e Dārolfonoun) ont été parmi les premiers “praticiens” du piano Persan. Cette thèse étudie l’art du piano persan à Téhéran depuis son introduction dans les années 1880 jusqu’à la revolution de 1979. Durant cette période, la pratique du piano persan a progressivement mûri, culminant dans les compositions et interprétations de Moshir Homāyoun-e Shahrdār (1886-1969), Mortezā Mahjoubi (1900-1965), et Javād Ma’roufi (1915-1993). Mahjoubi est considéré comme le plus eminent compositeur et interprète qui a instauré le piano traditionnel persan (Piano-ye Sonnati) comme une forme d’art distinctive. Les éléments les plus remarquables du piano persan traditionnel, les techniques de jeu, et les systèmes de réglage en microtones, de même que les innovations apportées à la pratique canonique par Ma’roufi, constituent les axes principaux de cette recherche. En outre, avec l’essor de la musique classique occidentale, la pratique du piano persan qui était presque entièrement fondée sur des techniques instrumentales ainsi que sur des formules et mélodies persanes autochtones n’a pas été maintenue au sein du Téhéran du XXe siècle. Le piano classique occidental coexista alors avec le style persan. Ce mémoire s’attache donc à étudier la place du piano classique occidental dans la société persane en présentant les contributeurs majeures en ce demaine, ce qui comprend aussi le style de Emanuel Melik-Aslāniān (1915- 2003). Cette recherche met aussi un accent particulier sur les claviéristes femmes, leur enseignement, leur style de jeu et leur performances publiques de la période de Qajar à celle de Pahlavi. Aujourd’hui, on constate de plus en plus de tentatives prometteuses pour revitalizer l’art du piano persan. Cela est particulièrement vrai pour le style de Mahjoubi dont l’héritage remarquable marque l’histoire d’évolution de la pratique du piano persan. Actuellement, la meilleure élève de Mahjoubi, Madame Fakhri Malekpour, enseigne le style traditionnel du piano persan en cours privés à Téhéran. L’effort fait pour éveiller l’interêt et former une nouvelle génération de pianistes pourrait faire en sorte qu’à l’avenir, cette forme unique d’art de piano sera plus connue et advantage pratiquée aux côtés des autres styles pianistiques. / Piano, a western musical instrument has a unique historical position in Persian music. Iran has its own music as part of its culture, a classical canon with an enduring repertoire and characteristic techniques handed down from generation to generation with some improvements made along the way. When the first keys were played on a piano in Tehran in the 1870s, the members of the imperial court were the exclusive audience. At the time, Sorourolmolk, the master musician of the Qajar palace during the reign of Nāsseredin Shah Qajar (1848-1896), attempted to change the tuning of piano and play traditional Persian tunes in a way inspired by santur and tār techniques. Thus, the practice of piano in Iran was immediately associated with the music that had already existed for generations. This would eventually become known as “Persian piano.” Later, the educated elite of the society, and students of the first military music school in Tehran (Sho’beh-ye Music-e Dārolfonoun) were among the first practitioners of Persian piano. This dissertation studies the art of Persian piano in Tehran from its introduction in 1880s until the Revolution of 1979. During this period, Persian piano practice gradually matured, culminating in the compositions and performances of Moshir Homāyoun-e Shahrdār (1886-1969), Mortezā Mahjoubi (1900-1965), and Javād Ma’roufi (1915-1993). Of this group, Mahjoubi is considered the most prominent composer and performer, and is the one credited with establishing Persian piano as a distinctive art form. This study looks at his work, and also focuses a spotlight on Ma’roufi’s style and contributions to Persian piano. With regard to the most notable elements in traditional Persian piano, the dissertation offers a thorough analysis of the techniques and tuning systems linked to the Persian microtone, and explores innovations in the canonic practice of traditional Persian piano. With the rapid expansion of western classical music in Iran in the twentieth century, the practice of Persian piano based almost entirely on indigenous Persian instrumental techniques, forms, and melodies, no longer held an exclusive place in piano performance. Accordingly the dissertation moves on to the practice of piano in Iran in the twentieth century and finds that Western classical piano co-existed with the Persian style. The study delves into the establishment of the western classical piano in Persian society and presents the major contributors in this field including Emanuel Melik-Aslāniān (1915- 2003). The dissertation places particular emphasis on female keyboard players, their musical education, style of play, and public performances from the Qajar period through the Pahlavi era. Today, promising attempts to revitalize the art of Persian piano are on the rise. This is especially true for Mahjoubi’s style whose outstanding legacy marks a milestone in the evolution of Persian piano practice. Presently, Mahjoubi’s best student, Fakhri Malekpour, is teaching the traditional style of Persian piano in private lessons in Tehran. The effort to awaken interest, and to train a new generation of practitioners just might mean that this unique form of piano art will become more well known and practiced alongside other pianistic trends on into the future.

[pt] No presente trabalho estuda-se a aplicação do controle estrutural na proteção de estruturas submetidas a carregamentos dinâmicos contra níveis de vibração indesejáveis que possam causar desconforto e, até mesmo, comprometer a segurança e integridade da edificação. Os três tipos de controle estrutural, passivo, ativo e híbrido, são analisados de forma a evidenciar as vantagens do uso do controle híbrido. O mecanismo de controle utilizado é o denominado amortecedor de massa sintonizado (AMS), devido à sua vasta aplicação na Engenharia Civil, tendo uma grande quantidade sido instalada em edifícios, pontes e chaminés industriais para controle de vibrações causadas pelo vento. Verifica-se a influência da não- linearidade da rigidez do AMS no comportamento do sistema principal. A utilização de amortecedores de massa sintonizados múltiplos é também estudada como uma forma de vencer certas limitações quanto à robustez deste tipo de sistema e melhorar sua performance. Analisa-se por fim o comportamento e eficiência do amortecedor de massa híbrido (AMH), em relação ao AMS passivo. Para cálculo da força de controle são utilizados os seguintes algoritmos: controle ótimo linear clássico, controle ótimo instantâneo e controle ótimo não-linear. Uma estratégia para definição das matrizes de ponderação, utilizadas no algoritmo de controle ótimo instantâneo, que minimizem a amplitude da resposta harmônica permanente é apresentada. Exemplos numéricos são apresentados ao longo de todo o trabalho. Verifica-se que a utilização do controle híbrido é mais eficiente que os controles passivo e ativo isolados, requerendo forças de magnitude inferiores, o que reduz bastante o custo deste tipo de sistema. O sistema de controle híbrido se mostrou eficiente na redução de vibrações causadas por carregamentos cujas freqüências eram diversas das consideradas no projeto do sistema de controle passivo. Verificou-se, ainda que o mesmo se comportou de forma satisfatória no caso de discrepância na freqüência natural da estrutura. / [en] In this work the use of structural control is studied to protect dynamically loaded building structures against undesirable vibration levels, which can cause human discomfort and, even more, compromise the building safety and integrity. The three types of structural control, passive, ative and hybrid, are analysed to show the advantages of hybrid control in reducing undesirable vibration levels. The chosen control mechanism is the so called tuned mass damper (TMD), due to its large application in Civil Engineering, having a great number of these devices been installed in buildings, bridges and industrial chimneys to control structural vibrations induced by wind loads. It is also verified the influence of TMD non linear stiffness on the main system behaviour. The use of multiple tuned mass dampers is studied as a possible way of improving the TMD robustness and performance. The hybrid mass damper (HMD) behaviour and efficiency comparing to the passive mass damper is analysed in detail. To calculate the control force the following control algorithms are used: classical optimum linear control, instantaneous optimum control and non-linear optimum control. A strategy to define the weighting matrices used in the instantaneous optimum control algorithm that minimizes the harmonic response amplitude is presented. Several numerical examples are presented aalong the work. The results show that the hybrid control is more efficient that the passive or active control used separately, requiring smaller forces reducing in this way the cost of the control system. The hybrid control system showed to be more efficient in reducing vibrations caused by loadings which had different frequencies from that considered on the passive control design. Moreover it was shown that hybrid control has a satisfactory perfomance when discrepancies in natural frequency occur.

No description available.

The performance of an acoustic filter (or muffler) is measured in terms of one of the following parameters: Insertion Loss (IL), Level difference (LD) and Transmission loss (TL). All these three parameters may be evaluated in terms of the four-pole or transfer matrix parameters. Appropriate experimental setups have been designed and developed and practical considerations are described. Measured values of TL are compared with the analytically predicted values. It is shown that the Two-Source-Location method is relatively the best. To start with, the matrizant analysis of conical concentric tube resonators is validated experimentally. The effect of mean flow is investigated. The experimental setup is specially designed to measure the pressure transfer function across the test muffler. It is shown that there is reasonably good agreement between the predicted values of the transfer function and the measured ones for incompressible mean flow as well as stationary medium. To measure insertion loss of muffler, one needs to calculate the source impedance. The internal impedance of a sound source can be measured using direct or indirect methods. The four-load SPL measurement method is one such indirect method wherein there are three nonlinear equations in terms of two unknowns which makes one of the equations redundant. This leads to erroneous results. To overcome this inherent weakness, two alternatives multi-load methods have been offered in the literature; namely, the least squares and the direct least squares method, to analyze the measured data used for four (or more) different loads. These two methods produce better results than the four-load SPL measurement method used earlier. These measurement methods have been tested on a loudspeaker to measure its source impedance and the results are validated with a known additional acoustic load. Simple expansion chambers, the simplest of the muffler configurations, have very limited practical application due to the presence of periodic troughs in the transmission loss (TL) spectrum which drastically lower the overall TL of the muffler. Many of the present days automobile exhaust systems make use of the extended tube mufflers, often with perforated ducts because of their low back pressure and good acoustic performance. Tuned extended inlet and outlet can be designed to nullify three-fourths of these troughs, making use of the plane wave theory. However, these cancellations would not occur unless one altered the geometric lengths for the extended tube and perforated tube resonators in order to incorporate the effect of the evanescent higher-order modes (multidimensional effect) through end corrections or lumped inertance approximation at the area discontinuities or junctions. This is investigated here experimentally as well as numerically (through use of 3-D FEM software) for a moving medium as well as stationary medium. The effect of temperature on the end corrections is also investigated. These tuned extended-tube chambers, however, suffer from the disadvantages of high back pressure and aerodynamic noise generation at the area discontinuities. These two disadvantages can be overcome by means of a perforated bridge between the extended inlet and the extended outlet. One dimensional control volume approach is used to analyze this muffler configuration. It is validated experimentally making use of the two source-location method, which is proven to be the best method available to us. It is thus shown that the inertance of holes plays a role similar to the lumped inertance generated by evanescent 3-D modes at the terminations of the quarter wave resonators in the case of the double-tuned extended tube chambers. The effect of mean flow is also investigated. The resultant transfer matrix is then used to carry out a systematic parametric study in order to arrive at empirical expressions for the differential lengths as well as the end corrections. Thus, an extended concentric tube resonator can be tuned such that the first three troughs that characterize the corresponding simple chamber transmission loss (TL) curve may be eliminated making use of the proposed procedure. In fact, the entire TL curve at low and medium frequencies may be substantially lifted, making the tuned extended concentric tube resonator a viable design option.

The Well Trained Algorithm is a composition that challenges prevailing conceptions of the use of AI tools in music through the reconceptualising of JukeBox, a generative AI model for music, as an instrument in its own right. Here, I am coining the term ‘instrumentisation’ to describe a methodology for applying the qualities and associations of a musical instrument to a traditionally non-musical object. To showcase this conceptual approach, this model of thinking is applied to aid in the composition of the AI-generated musical piece, The Well Trained Algorithm. Through this process of ‘instrumentisation’, musical terms such as tuning and timbre are redefined to better relate to the specific affordances of an artificially intelligent system. The composition is informed, then, by an exploration of a system's instrumental possibilities, leading to a more effective and artistic use of the technology in the creative process. The seminal works of J. S. Bach and La Monte Young, The Well Tempered Clavier and The Well Tuned Piano, respectively, provide a historical, musical, and theoretical context for the piece as well as the datasets used to fine-tune the JukeBox model. With this thesis, I ask if, through a process of ‘instrumentisation’ AI technology can be successfully reconceptualised as a musical instrument as a means to promote artistic expression.

<p> A numerical algorithm has been developed to solve the sloshing motion of liquid in a Tuned Liquid Damper (TLD) outfitted by slat screens under large and random amplitude of excitation. It is based on the finite-difference method. The free surface has been reconstructed using volume of fluid method. Donor-acceptor technique has been used for tracking the volume fraction field. The effect of slat screen has been included and modeled using the partial cell treatment method. </p> <p> The algorithm is an integrated fluid-structure model where the response of the structure is determined considering the effects of TLD. The structure is assumed as a single degree of freedom system (SDOF) and its response is calculated using the Duhamel integral method. </p> <p> The algorithm has been validated against experimental data for the cases with and without screens. An excellent agreement was obtained between numerical and experimental results. </p> <p> An extensive parametric study has been carried out investigating the effect of slat screens and screen pattern on the TLD performance and on the structure response. A new parameter termed as slat ratio was introduced to characterize the slat screens based on their pattern. Results indicated that screen pattern has a significant effect on the TLD performance and it could lead up to 33 % reduction in structure response. It was found that decreasing the slat ratio will increase the damping effect of a TLD outfitted by slat screen. </p> <p> The validity of the most commonly used approach, Baines and Peterson model, to calculate pressure drop of slat screens has been investigated. A conelation factor as a function of Reynolds number and solidity ratio of screen has been proposed to improve the results of this model. A new concept termed as effective solidity ratio has been proposed to account for the physical significant of screen pattern on TLD performance. </p> / Thesis / Doctor of Philosophy (PhD)

No description available.