This thesis presents the research done towards the development of the final mirror suspension stage for the high power test facility at AIGO, Western Australia. One of the goals of the facility is to test advanced suspension methods that may be useful in future gravitational wave detectors. An in depth study of current mirror suspension techniques is presented and areas of possible improvement are highlighted. The extension of an existing suspension modelling toolkit written in Mathematica is also presented, where added functions allow one to include the violin modes of a suspension into their analysis. Through this tool, new suspension geometries boasting a lower number of violin modes with lower Q factors where developed. The orthogonal ribbon suspension and the thin tube suspension boast a lower number of lower Q violin modes compared to typical ribbon suspensions. For the latter, a reduction in the number of violin modes below 5kHz down to 5 and peak thermal noise amplitude by approximately 30dB is predicted. Presented also is the affect that such suspension geometries have on pendulum mode dilution factor and overall suspension thermal noise. It is seen that the violin mode improvement comes at a cost of a small increase in thermal noise above approximately 50Hz. A theoretical analysis of the AIGO cavity locking control scheme is also given. Issues of sensor noise and dynamic range are considered to produce a possible hierarchical locking method that would be compatible with advanced detectors. The resulting actuator force range requirements for AIGO at each actuation location on the vibration isolation system are given. Requirements of local controls before achieving cavity lock are also discussed. Finally, the suspension of a dummy sapphire mirror using removable modular niobium ribbons is presented. The design and performance of an electrostatic actuator and sensor for suspended mirror control is given. Initial experimental results of positioning and control of the final stage suspension through a digital interface is also included.

The healthy condition of a rotating machine leads to safe and cheap operation of almost all industrial facilities and mechanical systems. To achieve such a goal, vibration-based condition monitoring has proved to be a well-accepted technique that detects incipient fault symptoms. The conventional way of On-Bearing Vibration Measurement (OBVM) captures symptoms of different faults, however, it requires a relatively expensive setup, an additional space for the auxiliary devices and cabling in addition to an experienced analyst. On-Shaft Vibration Measurement (OSVM) is an emerging method proposed to offer more reliable Faults Diagnosis (FD) tools with less number of sensors, minimal processing time and lower system and maintenance costs. The advancement in sensor and wireless communications technologies enables attaching a MEMS accelerometer with a miniaturised wireless data acquisition unit directly to the rotor without altering the machine dynamics. In this study, OSVM is analysed during constant speed and run-up operations of a test rig. The observations showed response modulation, hence, a Finite Element (FE) analysis has been carried out to help interpret the experimental observations. The FE analysis confirmed that the modulation is due to the rotary motion of the on-shaft sensor. A demodulation method has been developed to solve this problem. The FD capability of OSVM has been compared to that of OBVM using conventional analysis where the former provided more efficient diagnosis with less number of sensors. To incorporate more features, a method has been developed to diagnose faults based on Principal Component Analysis and Nearest Neighbour classifier. Furthermore, the method is enhanced using Linear Discriminant Analysis to do the diagnosis without the need for a classifier. Another faults diagnosis method has been developed that ensures the generalisation of extracted faults features from OSVM data of a specific machine to similar machines mounted on different foundations.

Vibration measurements conducted in three vehicles windshields are used to determine frequency content in the windshield of moving vehicles. A piezoelectric energy harvester is modeled, and used in simulations to determine output voltage and power with measured acceleration signal as input.

Thesis (M. Tech.) - Central University of Technology, Free State, 2011 / The objectives of this research were to investigate and establish a procedure to determine the self-damping characteristics of transmission line conductors subjected to free and forced vibrations. The TERN and Aero-Z IEC62219-REV240609 conductor cables were the transmission line conductors that were readily available at the Vibration Research and Testing Centre (VTRC) of the University of KwaZulu-Natal (UKZN). The question to be answered was whether the self-damping characteristics of the TERN and Aero-Z IEC62219-REV240609 conductors were adequate to suppress Aeolian or wake-induced vibrations. In other words, is it necessary for external damping mechanisms to be used with these conductors? This study confirmed that the self-damping characteristics of conductors are not adequate to suppress Aeolian or wake-induced vibrations. Governing partial differential equations describing the characteristics of the catenary and parabolic cable conductors were developed to validate the experimental results. The experimental tests involved both conductors being subjected to an impulse function (a free vibration method) and also to a harmonic function (a forced vibration method). Measurements were carried out using accelerometers, and the recording equipment consisted of oscilloscopes and the PUMA system. With both the free and forced vibration methods, the damping factor of the TERN conductor was confirmed to be ζ ≤ 0.05, whereas the damping factor of the Aero-Z IEC62219-REV240609 was confirmed to be ζ ≤ 0.2. A procedure for determining the self-damping characteristics of the TERN and Aero-Z IEC62219-REV240609 conductors was developed, with the damping factor found to be ζ ≤ 0.2 for both conductors. These methods can assist in the implementation of procedural analysis of the self-damping behaviour of different types of transmission conductors and in finding the most suitable mass absorber (damper) to use in reducing the rate of failure of transmission line conductors. The results of this study can be used to improve the mathematical modelling of Aeolian and wind-induced vibrations where both self-damping properties and a mass absorber are incorporated.

L'interférométrie à rétro-injection optique, également connu sous le nom de Self-Mixing, permet de concevoir des capteurs qui sont compacts, auto-alignés et sans contact. Dans ce phénomène, une partie du faisceau laser de retour réfléchi par la cible rentre dans la cavité active de laser et fait varier ses propriétés spectrales. La diode laser agit alors comme une source de lumière, un microinterféromètre ainsi qu'un détecteur de lumière. Dans cette thèse, un capteur de déplacement, basé sur la rétro-injection optique, a été optimisé de sorte que des mesures précises peuvent être obtenues en temps réel. Le capteur est robuste à la disparition des franges de self-mixing pour des vibrations harmoniques. Il est également capable de s'adapter à un changement dans le régime de feedback optique et peut donc extraire le déplacement dans les cas les plus répandus expérimentalement, à savoir un feedback faible puis modéré. L'utilisation de l'optique adaptative, sous la forme d'une lentille liquide, a également été démontrée pour ce capteur, ce qui nous a permis de maintenir le capteur dans un régime de feedback favorable. L'influence du speckle a également été réduite de telle sorte que le capteur mesure jusqu'à la gamme centimétrique pour des cibles non- oopératives. Une nouvelle technique est également présentée, elle permet de rendre le capteur insensible aux vibrations mécaniques parasites qui fausseraient la mesure pour des conditions industrielles. / Optical Feedback Interferometry, also known as Self-Mixing, results in compact, selfaligned and contact-less sensors. In this phenomenon, a portion of the laser beam is back reflected from the target and enters the active laser cavity to vary its spectral properties. The laser diode then simultaneously acts as a light source, a micro- nterferometer as well as a light detector. In this thesis, a self-mixing displacement sensor has been optimised so that precise measurement can be obtained in real-time. The sensor is robust to the disappearance of self-mixing fringes for harmonic vibrations. It is also able to auto-adapt itself to a change in the optical feedback regime and so can extract displacement from the weak as well as moderate feedback regime signals. The use of adaptive optics, in the form of a liquid lens, has also been demonstrated for this sensor, which has allowed us to maintain the sensor in a fringe-loss less regime. The influence of speckle has also been reduced so that the sensor can now measure up to the centimetric range for non-cooperative targets. A novel technique has also been presented that makes the sensor insensitive to parasitic mechanical vibrations that would falsify the measurement under industrial conditions.

[Truncated abstract] Interferometric gravitational wave detectors are being built around the world with continually improving measurement sensitivities. Noise levels from sources that are intrinsic to these detectors must be reduced to a level below the gravita- tional wave signal. Seismic noise in the low frequency range, which is within the gravitational wave detection bandwidth, is a concern for earth-based detectors. This thesis presents research and development of a high performance vibration isolation system that is designed to attenuate seismic noise. The final design will be used as part of a fully working interferometer at the Australian International Gravitational Observatory (AIGO). Pendulums and springs are conventionally used for the horizontal and vertical vibration isolation components respectively. A complete system comprises of a cascade of these components, each stage dramatically improving the level of isola- tion. The residual motion at the test mass level is thus reduced but is dominated by the normal mode resonances of the chain. A simple and effective method to reduce residual motion further is to add ultra-low frequency pre-isolation stages which suspend the chain. The Roberts Linkage is a relatively new and simple geometrical structure that is implemented in the pre-isolation stages. Here we present experimental results of improving isolation based on mathematical mod- elling. The attenuation of seismic noise in the vertical direction is almost as important as that in the horizontal direction, due to cross-coupling between the two planes. To help improve the vertical performance a lightweight Euler spring that stores no static energy was implemented into the AIGO suspension system. ... Theoretical and experimental results are presented and discussed. Currently the AIGO laboratory consists of two 80 m length arms. They are aligned along the east and south directions. One of AIGO's top priorities is the installation of two complete vibration isolators in the east arm to form a Fabry-Perot cavity. Assembling two suspension systems will enable more accurate performance measurements of the tuned isolators. This would significantly reduce the measurement noise floor as well as eliminate the seismic noise spectrum due to referencing with the ground motion. The processes involved in preparing such a task is presented, including clean room preparation, tuning of each isolator stage, and local control schematics and methods. The status of the AIGO site is also presented.

Made available in DSpace on 2015-03-26T13:23:57Z (GMT). No. of bitstreams: 1 texto completo.pdf: 4894950 bytes, checksum: 03378345c210236f7d7657ab6a6d6d87 (MD5) Previous issue date: 2014-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Coffee manual harvesting is a complex and costly activity due to factors such as plant height, land slope, weather conditions, correct time for harvesting, beyond high production cost with manpower. Then, mechanization arises as a solution by increasing the process' operational capability and the reduction of physical effort for harvesting. The development of efficient harvesting machines requires the knowledge about the plant s dynamic behavior, aiming a greater overthrowing efficiency and less breakage of branches and leaf fall. This study aimed to analyze the dynamic behavior of the fruit-stem-branch system of the coffee plant subjected to mechanical vibration. This study was carried out using samples of Arabica coffee Red Catuaí variety collected in an experimental area of the Universidade Federal de Viçosa (Federal University of Viçosa) in Viçosa City/Minas Gerais State, Brazil, from May to July, 2013. This study is composed by five papers: (1) in the first paper, mass, volume, specific density, elasticity modulus, Poisson's ratio, and the constituents' damping ratio of the fruit-stem-branch system were experimentally determined. Damping ratio values obtained for the stem and the branch were lower than one, characterizing them as an underdamped system; (2) in the second paper, certain methodology was developed for determining the elasticity modulus of the fruit and stem by comparing the natural frequencies obtained by the finite elements method with the natural frequencies obtained experimentally. The average values for the elasticity modulus were 15.74; 23.90, and 4645.90 MPa for stem in green and ripe ripeness stages, and for the branch, respectively; (3) in the third study, the natural frequencies and the modes shapes were determined for the fruit- stem, branch, and fruit-stem-branch systems using the stochastic finite elements method, in which the specific density and elasticity modulus of fruits, stems, and branches were treated as random values. The natural frequencies were reduced to the extent that the ripeness stage evolved or according as the system total mass increased. For the fourth and fifth modes shapes, larger deformations in the stems were found; (4) in the fourth paper, the stresses in the fruit-stem, branch and fruit-stem-branch systems were determined when subjected to mechanical vibration with frequency related to the natural frequency, peak to peak displacement of 10 mm, and stimulation time of 10 s. The von Mises stresses were higher for systems in green ripeness stage and in the jointing regions of the stem to the branch and of the branch to the stem due to higher frequency vibrations applied on this ripeness stage and to the higher bending moments in these regions, respectively; (5) in the fifth paper, a overthrowing efficiency test with a fruits' bunch samples were subjected to mechanical vibrations at different frequencies (16.4; 20.3; 24.0; 25.6; 30.0; and 33.0 Hz), peak to peak displacement (5.0; 7.0; and 9.0 mm), and vibration times (10.0 and 20.0 s). For the studied amplitudes, the overthrowing efficiency of ripe fruits tended to be higher than the overthrowing efficiency of the green fruits. The overthrowing efficiency increased according as the frequency and vibration amplitude increased. / A colheita manual do café é considerada uma atividade complexa e onerosa, devido a fatores como altura das plantas, inclinação dos terrenos, condições climáticas, necessidade da colheita no período correto, além do elevado custo de produção com mão de obra. A mecanização surge, então, como uma solução pelo aumento da capacidade operacional do processo e redução dos esforços físicos para a colheita. O desenvolvimento de máquinas de colheita eficientes exige conhecimento acerca do comportamento dinâmico da planta, visando à maior eficiência de derriça, além de menor quebra de galhos e queda de folhas. Objetivou-se neste trabalho analisar o comportamento dinâmico do sistema fruto-pedúnculo- ramo do cafeeiro submetido a vibrações mecânicas. O trabalho foi desenvolvimento empregando amostras de café arábica, variedade Catuaí Vermelho, coletados em uma Área Experimental da Universidade Federal de Viçosa, em Viçosa/MG, no período maio a julho/2013. O trabalho foi dividido por cinco artigos. No primeiro artigo, foram determinados experimentalmente a massa, o volume, a massa específica, o módulo de elasticidade, o coeficiente de Poisson e a razão de amortecimento dos constituintes do sistema fruto-pedúnculo-ramo. Os módulos de elasticidade dos frutos e dos pedúnculos no estádio de maturação verde foram superiores aos valores para o estádio de maturação cereja. Foram obtidos valores de razão de amortecimento para o pedúnculo e ramo menores que o unitário, caracterizando-os como um sistema subamortecido. No segundo, foi desenvolvida uma metodologia para determinação do módulo de elasticidade do fruto e do pedúnculo pela comparação entre as frequências naturais obtidas pelo método de elementos finitos e as frequências naturais obtidas experimentalmente. Os valores médios para os módulos de elasticidades foram de 15,74; 23,90 e 4645,90 MPa para o pedúnculo nos estágios de maturação verde, cereja e para o ramo, respectivamente. No terceiro artigo, foram determinados as frequências naturais e os modos de vibração dos sistemas fruto-pedúnculo, ramo e fruto-pedúnculo-ramo, empregando o método de elementos finitos estocástico, em que a massa específica e o módulo de elasticidade dos frutos pedúnculos e ramos foram tratados como valores aleatórios. As frequências naturais foram reduzidas na medida em que evoluiu o estádio de maturação ou na medida em que aumentou a massa total do sistema. Para o quarto e o quinto modos de vibração, foram constatadas maiores deformações nos pedúnculos. No quarto artigo, foram determinadas as tensões nos sistemas fruto-pedúnculo, ramo e fruto-pedúnculo-ramo, quando submetidos à vibração mecânica com frequência referente à frequência natural, deslocamento pico a pico de 10 mm e tempo de excitação de 10 s. As tensões de von Mises foram superiores para sistemas no estádio de maturação verde e nas regiões de engaste do pedúnculo ao ramo e no engaste do ramo ao tronco devidas às maiores frequências de vibrações aplicadas neste estádio de maturação e aos maiores momentos fletores nestas regiões, respectivamente. E no quinto artigo, foi feito um ensaio de eficiência de derriça, em que amostras com um cacho de frutos foram submetidas a vibrações mecânicas em diferentes frequências (16,4; 20,3; 24; 25,6; 30,0 e 33,0 Hz), deslocamento pico-a-pico (5,0; 7,0 e 9,0 mm) e tempos de vibração (10,0 e 20,0 s). Para as amplitudes estudadas, houve tendência de a eficiência de derriça dos frutos cereja ser superior à dos frutos verdes. A eficiência de derriça aumentou na medida em que foram aumentadas a frequência e a amplitude de vibração.

CAPES; CNPq; FINEP; Fundação Araucária / Neste trabalho apresenta-se um sistema ótico inteligente apto a localizar a posição de impactos mecânicos aplicados em uma estrutura plana. Para isso, os transdutores foram caracterizados, preliminarmente, quanto à deformação mecânica. Nesta aplicação, quatro redes de Bragg em fibra ótica foram instaladas em uma placa quadrada de polimetil-metacrilato, submetida a um conjunto de impactos em condições controladas. As respostas fornecidas pelos transdutores foram utilizadas para modelar e testar redes neurais artificiais. O sistema demonstrou possuir a capacidade para realizar a tarefa de encontrar a posição do distúrbio, mesmo em pontos de impacto diferentes daqueles apresentados na etapa de treinamento. O maior erro médio quadrático medido na fase de testes foi de 1,1 cm em relação ao ponto de impacto, sendo que os pontos localizavam-se a uma distância de 5 cm uns dos outros e estavam demarcados em uma superfície de prova com 60 cm de comprimento, 60 cm de largura e 6 mm de espessura. / In this work is presented an intelligent optical sensor capable to localize the position of mechanical impacts on a flat surface structure. The transducers were previously characterized relatively to mechanical strain. In this application, four optical fiber Bragg gratings were installed on a polymethyl methacrylate square plate, subjected to a set of mechanical impacts under controlled conditions. The responses provided by the transducers were used to model and test Artificial Neural Networks. The system showed the capacity to determine the disturbance positions, even at impact points different from the ones used in the training stage. The higher mean square error obtained in the test stage was 1,1 cm relatively to the impact position, wherein the points were located at a distance of 5 cm from each other on a test surface with 60 cm length , 60 cm width and 6 mm height.

CAPES; CNPq; FINEP; Fundação Araucária / Neste trabalho apresenta-se um sistema ótico inteligente apto a localizar a posição de impactos mecânicos aplicados em uma estrutura plana. Para isso, os transdutores foram caracterizados, preliminarmente, quanto à deformação mecânica. Nesta aplicação, quatro redes de Bragg em fibra ótica foram instaladas em uma placa quadrada de polimetil-metacrilato, submetida a um conjunto de impactos em condições controladas. As respostas fornecidas pelos transdutores foram utilizadas para modelar e testar redes neurais artificiais. O sistema demonstrou possuir a capacidade para realizar a tarefa de encontrar a posição do distúrbio, mesmo em pontos de impacto diferentes daqueles apresentados na etapa de treinamento. O maior erro médio quadrático medido na fase de testes foi de 1,1 cm em relação ao ponto de impacto, sendo que os pontos localizavam-se a uma distância de 5 cm uns dos outros e estavam demarcados em uma superfície de prova com 60 cm de comprimento, 60 cm de largura e 6 mm de espessura. / In this work is presented an intelligent optical sensor capable to localize the position of mechanical impacts on a flat surface structure. The transducers were previously characterized relatively to mechanical strain. In this application, four optical fiber Bragg gratings were installed on a polymethyl methacrylate square plate, subjected to a set of mechanical impacts under controlled conditions. The responses provided by the transducers were used to model and test Artificial Neural Networks. The system showed the capacity to determine the disturbance positions, even at impact points different from the ones used in the training stage. The higher mean square error obtained in the test stage was 1,1 cm relatively to the impact position, wherein the points were located at a distance of 5 cm from each other on a test surface with 60 cm length , 60 cm width and 6 mm height.

Theoretical analysis (i.e. simulation) promoted by the laboratory tests of final product is the important aspect for determination relating to choice and using the new infrastructural constituent. However, the laboratory analysis does not need to make conclusive results in some cases. At that time, it is necessary to complete the process of validation by the measurement in-situ (directly in the track section). The European legislation requires the long-term monitoring of the test constructions in this case. During this time, both the periodic monitoring of the chosen parameters and the following comparison with reference construction are recommended. The reference construction shall be inserted to the same track section and in the same time period as well as the test construction. The track gauge, the longitudinal shifts of rails vis-a-vis the sleepers, the clamping force of fastening, the rail head profile, the sleepers and the state of rail fastenings are possible to classify like the long-term monitored parameters. All these characteristics are so-called static. They are checked in time when no carriages pass through the monitored track section. However, the analysis and determination of the test construction behaviour (dynamic characteristic) are the most accurate by the moving load. Dissertation thesis is focused on measurement and analysis of the dynamic effects at the plain line. The aim of the thesis is the completion of recent system of the new track structures verification for the dynamic parameters observe. Methodology of the measurement and convenient mathematical apparatus for analysing the dynamic effects is proposed.