The concept of mounting a loudspeaker on one end of a sound-absorbing tube has existed since at least 1936. Surprisingly, a detailed mathematical analysis of the configuration has not been performed, nor has a design method been established. This configuration, known as a transmission line loudspeaker, has received little consideration in the reviewed literature. Instead, it has become frequently featured in magazines for audio hobbyists, where it is experimentally designed with rules seemingly derived from hearsay and described with terms of high praise. In this dissertation, an electro-acoustical model of a fiberglass-filled transmission line is presented. This model represents the transmission line as two separate lines -- a mechanical line that models the mechanical motion of the fiberglass and an acoustical line that models the motion of the air. The lines are linked by the flow resistance of the fiberglass. From the model, solutions for the acoustic pressure, acoustical volume velocity of the air, mechanical velocity of the fiberglass fibers, and mechanical force on the fiberglass in the line are obtained. The fiberglass is characterized and empirical formulas that describe its characteristics are found. It is shown that the modeled input impedance to the transmission line is a good fit to measured data. The performance of the system is assessed by comparing it with the performances of typical loudspeaker mountings, i.e., the infinite baffle, the closed box, and the vented box. Finally, an example is shown of how the equations derived from the model can be used to evaluate the design of a transmission line loudspeaker system.

This dissertation presents findings from two disparate research projects relating to the cathodic protection (CP) of piles supporting bridge elements. The first was a proof of concept study for developing a new hybrid pile repair system incorporating embedded sacrificial zinc anodes within a fiber reinforced polymer (FRP) wrap. The second was to develop and remotely monitor the performance of magnesium anodes protecting steel H-piles supporting two bridges in Florida. The hybrid FRP-CP system involved a proof-of-concept laboratory study to refine pressure / vacuum bagging systems for pile repair and to quantify the improvement in the FRP concrete bond. Two different FRP systems, one epoxy based and the other urethane based, were evaluated. Improvement in bond was determined through destructive pullout tests conducted on full-size pile specimens that were wrapped while partially submerged in a fresh water tank. The results showed that pressure led to significant improvement in FRP-concrete bond. Pressure was optimal for the epoxy-based system, while vacuum proved better for the urethane-based system. The pressure system was subsequently used to install FRP over embedded anodes in a field demonstration project where four corroding piles were repaired using the hybrid FRP-CP system. Cathodic protection was provided by embedding eight zinc anodes in each concrete pile. Protection below the water line was provided by bulk anodes. Reference electrodes were installed to monitor the performance of the CP system and data loggers were used to monitor the anodic current. Results from over 12 months of monitoring showed that the hybrid FRP-CP system worked and the current demand of the steel was lower in the FRP wrapped piles compared to the unwrapped control. Numerical simulations were carried out to determine how the hybrid FRP-CP system could be improved. Initially the investigation focused on determining if bulk anodes alone could be used to provide the required protection. Results showed that while bulk anodes were more effective in FRP wrapped piles, they could not provide adequate protection over the entire splash-zone. In view of this, a preliminary three dimensional finite element analysis was carried out using commercially available software. The analysis showed that anode strips embedded in the pile just beneath the surface may provide adequate protection. Such anodes would be easier to install and are an improvement over the system investigated. The second project involved the development of a remote monitoring system to assess the performance of a sacrificial anode cathodic protection system used for steel piles on two bridges along I-75 in Florida. The problem was the inexplicable consumption rate of the magnesium anodes. Commercially available systems and sensors were used to successfully monitor the environment and the anodic current of the CP system for over 12 months. A solution for the excess magnesium consumption was proposed through the incorporation of an in-circuit variable resistor that could regulate the current draw from the anode. The system was implemented but its performance will be monitored by the Florida Department of Transportation who assumed responsibility for the equipment. Initial results were promising.

Made available in DSpace on 2014-12-17T14:07:02Z (GMT). No. of bitstreams: 1 FabioSCPpdf.pdf: 1533458 bytes, checksum: 0df903e6bea6c66d762b8b1bbe3c6937 (MD5) Previous issue date: 2009-11-30 / Due to the occurrence of diseases in the use of structural reinforcements in composites, with presentation of concrete blanket detachment, has been identified the need to evaluate the performance of concrete reinforced with glass fiber. This study aims to evaluate these concretes by means of testing methodologies, using concrete with low resistance with structural reinforcement for confinement by preimpregnated glass fiber and traditional fiberglass blanket. The first stage of work was the development of methodologies for analysis, opting for four types, such as the acoustic survey, strength to compressive, the pull-off and ultrasound. Next, tests were carried out using the four selected methodologies in 30 of proof-of-specimens by 5x10 cm, 15 were reinforced with the traditional fiberglass blanket with 5specimens exposed to test a marine environment of marine coastline of Natal-RN and 15 were reinforced with a pre-impregnated glass fiber blanket, as well as 5specimens exposed to a test environment of the marine coastline of Natal-RN. After conducting the acoustic survey, it has been verified a lack of delaminating and air bubbles in the samples, confirming the absence of gross shortcomings in the implementation of the ribs both the traditional fiberglass blanket and in the preimpregnated fiber glass blanket. After carrying out methods of pull-off and compressive strengthening test it was observed that the reinforced proof-bodies with pre-impregnated glass blanket showed maximum stresses higher than the traditional fiberglass blanket; consequently a greater grip with the formation of a smaller area of . fracture, unlike traditional glass mat, which showed lower maximum stresses, with a greater area of fracture. It was also found that the traditional fiberglass blanket presented detachment of blanket-concrete interface, unlike the pre-impregnated fiberglass blanket, which showed a better grip on the blanket-concrete interface. In the trial of ultrasound there was no presence of cracks in the blanket-concrete interface, yielding to both blankets good compactness of the concrete. At the end of this work, they were developed and proposed two methods of testing for evaluation of reinforced concrete structures with composites, for standardization, the acoustic survey and pull-off / Em virtude da ocorr?ncia de patologias na utiliza??o de refor?os estruturais com comp?sitos, com apresenta??o de descolamento da manta do concreto, foi identificada a necessidade de se avaliar o desempenho dos concretos refor?ados com a fibra de vidro. Sendo o objetivo principal deste trabalho, avaliar estes concretos, atrav?s de metodologias de ensaios, utilizando concretos com resist?ncias baixas com refor?o estrutural por confinamento por fibra de vidro pr?impregnada e por manta de fibra de vidro tradicional. A primeira etapa do trabalho consistiu na elabora??o das metodologias de an?lise, optando-se por quatro tipos, a sondagem ac?stica, resist?ncia ? compress?o,o pull-off e o ultra-som. Em seguida, foram realizados os ensaios utilizando as quatro metodologias escolhidas em 30 corpos-de-prova de 5x10 cm, sendo 15 refor?ados com a manta de fibra de vidro tradicional, com 5 corpos-de-prova expostos a um ambiente marinho da orla mar?tima de Natal-RN e sendo 15 refor?ados com a manta de fibra de vidro pr?impregnada, tamb?m com 5 corpos-de-prova expostos a um ambiente marinho da orla mar?tima de Natal-RN. Ap?s a realiza??o dos ensaios de sondagem ac?stica, verificou-se a inexist?ncia de delamina??es e bolhas de ar nas amostras analisadas, comprovando a inexist?ncia de falhas grosseiras na aplica??o dos refor?os tanto na manta de fibra de vidro tradicional, como na da manta de fibra de vidro pr?impregnada. Depois de executadas as metodologias de ensaios de resist?ncia ? compress?o e pull-off, observou-se que os corpos-de-prova refor?ados com a manta de vidro pr?-impregnada apresentaram tens?es m?ximas superiores ?s obtidas com a manta de fibra de vidro tradicional, consequentemente uma ader?ncia maior, com a forma??o de uma menor ?rea de fratura, ao contr?rio da manta de vi dro tradicional, que apresentou tens?es m?ximas inferiores, com uma maior ?rea de fratura. Verificou-se ainda que a manta de fibra de vidro tradicional apresentou descolamento da interface manta/concreto, ao contr?rio da manta de fibra de vidro pr?-impregnada, que apresentou uma maior ader?ncia na interface manta/concreto. No ensaio de ultra-som n?o se observou presen?a de fissuras na interface manta/concreto, obtendo-se para ambas as mantas, boas compacidades do concreto. Ao final do trabalho foram elaboradas e propostas duas metodologias de ensaios para avalia??o das estruturas de concreto armado refor?adas com comp?sitos, para normaliza??o, a sondagem ac?stica e o pull-off

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Made available in DSpace on 2014-10-09T12:54:48Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:32Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP / FAPESP:06/52788-7

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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-03-03T10:53:35Z No. of bitstreams: 0 / Made available in DSpace on 2015-03-03T10:53:35Z (GMT). No. of bitstreams: 0 / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:53:10Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:37Z (GMT). No. of bitstreams: 0 / É cada vez maior a utilização de polímeros reforçados com fibra de vidro no mercado nacional. Entre eles utiliza-se a poliamida 6 que apresenta ótima resistência à tração, ao impacto e à absorção de umidade comparada à poliamida 6 sem reforço de fibra de vidro, sendo atualmente utilizada na indústria automobilística em peças sob o capô, em especial em carcaças de radiadores. Este trabalho foi realizado com o objetivo de estudar o efeito da radiação ionizante nas propriedades mecânicas (resistência à tração, à flexão e ao impacto Izod) e térmicas (resistência ao fio incandescente e temperatura de fusão) da poliamida 6 com reforço de fibra de vidro, submetida à diferentes doses de radiação (100 a 600 kGy). As amostras foram preparadas e irradiadas em um acelerador JOB 188 com feixe de elétrons de energia de 1,5 MeV em diferentes doses e uma taxa de dose de 22,61 kGy/h. Após a irradiação, as propriedades das amostras da poliamida 6 com reforço de fibra de vidro irradiada foram determinadas e comparadas com as amostras não irradiadas e constatou-se que as propriedades mecânicas de resistência à flexão e à tração aumentaram e a de resistência ao impacto diminuiu. Em relação à propriedade térmica de temperatura de fusão diminuiu de 224,4ºC para 212,5ºC mas a perda de massa diante do aumento constante da temperatura também diminuiu. Em relação à propriedade de resistência ao fio incandescente a poliamida 6 com reforço de fibra de vidro irradiada teve um bom desempenho. As imagens captadas por Microscopia Eletrônica de Varredura mostram que a irradiação provocou uma boa integração entre a fibra de vidro e o polímero o que foi responsável pelo bom desempenho na propriedade de resistência ao fio incandescente. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:48:42Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:56Z (GMT). No. of bitstreams: 1 09150.pdf: 3154679 bytes, checksum: f1a5a4085f6acc6064953483dddb2281 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP