Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (December 19, 2006) Includes bibliographical references.

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Made available in DSpace on 2016-01-13T13:26:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-05-26. Added 1 bitstream(s) on 2016-01-13T13:31:19Z : No. of bitstreams: 1 000851768.pdf: 3778893 bytes, checksum: b3a75a88e3983197730f9c2b46ace93f (MD5) / Na indústria de cabos a qualidade do cabo de rede (LAN) só é conhecida no final da linha de produção, medindo a desempenho do cabo pronto (produto acabado). Há portanto uma deficiência no sistema de qualidade, incapaz de avaliar os materiais intermediários antes de comporem o cabo pronto. Este trabalho propõe uma ferramenta matemática para o tratamento das medições de reflexão (perda de retorno) em alta frequência de tais semi-elaborados, de forma a orientar a fábrica sobre a qualidade dos mesmos antes de avançarem na linha de produção. O método usa a área entre as curvas de perda de retorno do par e a norma de qualidade, sendo este valor chamado área de margem (AM). Verificou-se pelo método de correlação de Spearman que há uma correlação alta entre o valor de AM dos pares e AM do cabo pronto, com chance de erro menor que 1%. Utilizando a AM para selecionar os pares trançados, foram reunidos núcleos cujo desempenho foram diferenciados. Para avaliação automática da AM, foi desenvolvido também o programa SATLER para tratamento matemático das medidas / In cable industry, the LAN network cables quality is knew only in the end of prodution line, measuring the performance of finished cable. So thus, there is a deficiency on quality system, unable to evaluate the intermediate materials before cable layup. This paper proposes a new mathematical tool for handling signal reflection measurements (Return Loss) in high frequencies over the semi-finished ones, in order to guide factory about the quality before going forward on production flow. This method uses the between curves of return loss of twisted pair and the curve of normative limits, being this area the Margin Area (MA). It was verified a great correlation (using Spearman method) between pairs MA and final cable's MA, with and errors chance bellow 1%. Using such MA to select twisted pairs, there were laid up stranded cores with different performances. For automatic MA evaluation, it was also developed the software SATLER for mathematical processing of measurements

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017. / RF and microwave filters can be implemented using ceramic coaxial resonators. This technology has been widely employed in nanosatellite communications systems recently, owing to its large quality factor (Q), permitting them to have low loss and narrow bandwidth. Features such as high selectivity, high power handling, excellent rejection, and low passband insertion loss are just a few of the key performance areas offered by ceramic coaxial resonators. This feature makes them suitable for use in bandpass filters. Applications with demanding specifications requiring low volume and mass make use of this technology. Fulfilling the required performance goals can be challenging, given the size and weight restriction. Difficulties such as finding the correct length of resonators and the coupling capacitors’ structure to meet the size restriction, limit the type of ceramic coaxial resonators to use. This thesis presents the design of a bandpass filter using ceramic coaxial resonators, which provides evidence of the concept for F’SATI’s future needs. This design will be used in an imminent space mission and the intention is to mount the bandpass filter in the receiver communications system. An intensive investigation was conducted into the use of filters for nanosatellite communication systems. The Chebyshev LC ladder low pass prototype was used to derive the conventional bandpass filter. Thereafter, the coupled resonator bandpass filter was derived using the conventional bandpass filter topology combined with the admittance inverter. Following this, using the ceramic coaxial resonators datasheet and information provided by the manufacturers, the coupled resonator bandpass filter was converted into a 3D model for further simulations, using CST Microwave Studio®. The ceramic coaxial resonator filter fabricated using Rogers’s material provided satisfactory results at its operating frequency between 2.2 GHz and 2.3 GHz. A radiation level test was performed on the filter to justify the use of the metallic enclosure. The test presented a low level of radiation measured at the filter operating frequency (2.25 GHz). The filter was also subjected to temperature cycling. / French–South African Institute of Technology (F’SATI) National Research Foundation (NRF)

Neste trabalho são apresentados os aspectos mais relevantes do comportamento dos cabos, a descrição dos comportamentos estático e dinâmicos e aplicação da análise dinâmica na determinação da força de um cabo a partir de ensaios de vibração livre. Serão analisados dois estudos de caso onde esse método foi aplicado : nos tirantes da cobertura do estádio Castelão em Fortaleza e nos estais da ponte sobre o rio Sergipe. Em seguida serão discutidas as vantagens e limitações do método. / In this work the most important characteristics of the cables are presented: their static and dynamic behavior and the vibration method to evaluate the cable force from free vibration tests results. Two study cases are described: the cables of the Castelao Stadium at Fortaleza and the stays of the bridge over Sergipe river. The advantages and limitations of this method are discussed.

Em estruturas estaiadas de pontes e viadutos, a determinação das forças dos estais necessariamente está relacionada à ação direta dos carregamentos mais a interação com a deformabilidade do estaiamento, incluindo principalmente o sistema tabuleiro e mastro. Por outro lado, é necessário conhecer estas forças ao longo das fases de montagem, assim como sua adequada implantação na estrutura e a determinação de possíveis ajustes nas forças devido ao processo construtivo da ponte, garantindo assim que os esforços desejados sejam alcançados e a correta distribuição espacial das forças do estaiamento. O conhecimento das forças dos estais é de extrema importância no controle dos deslocamentos e esforços da estrutura em questão, tendo este trabalho foco no greide e nos esforços finais do tabuleiro da ponte estaiada. As forças podem ser obtidas a partir da solução de um problema fundamental que consiste na determinação de acréscimos de força nos estais, necessários para atingir ou controlar um vetor de deslocamentos, ou um vetor de momentos fletores. De maneira geral, no caso de pontes construídas com aduelas (balanços sucessivos), para cada aduela anexada os esforços e deslocamentos são alterados nas aduelas já executadas, e principalmente nos estais já montados. A montagem deve garantir o greide final do tabuleiro e o conjunto de esforços desejados, o que se consegue com uma criteriosa definição dos esforços de montagem dos cabos. No mais, em função da sequência construtiva e do programa de tensionamento dos estais estabelecido para a obra, pode se tornar necessária a aplicação de uma correção sequencial das forças dos estais para se chegar às forças finais previstas em projeto.Será apresentado neste trabalho o procedimento de controle do greide final e dos esforços do tabuleiro da ponte e o de montagem dos estais, sendo este último, dividido na definição das forças dos cabos ao longo da montagem, na implantação destas forças na estrutura e num procedimento de correção sequencial das forças dos estais a partir da determinação de forças de ajuste. / In cable-stayed structures of bridges and viaducts, the determination of the stay forces is necessarily related to the direct action of loads plus interaction with the deformability of the staying, including especially the system deck and mast. On the other hand, it is necessary to know these forces along the assembly phases, as well as their proper implementation in the structure and determination of possible adjustments in forces due to bridge construction process, ensuring that the desired forces are achieved and the correct spatial distribution of forces of the staying. The knowledge of the stay forces is extremely important in controlling of the displacements and forces of the structure in question, having this work focus on shape and final forces of the cable-stayed bridge deck. The forces can be obtained from the solution to a fundamental problem that consists in the determination of increases strength in the stays, required to reach or control an array of displacements, or a vector of bending moments. In general, in the case of bridges constructed with staves (cantilever procedure), for each attached stave the forces and displacements are changed in staves already implemented, and especially in the stays already assembled. The assembly must ensure final shape of the deck and all forces desired, what can be achieved with a careful definition of the assembly forces of the cable. In addition, according to the sequence of constructive and the program tensioning of the stays established for the construction, may become necessary to apply a sequential correction of the strengths of the stays to reaching at the final forces provided in project.It will be presented in this work the procedure of control final shape and bridge deck forces and the assembly of stays, the latter divided in defining the forces of the cables along the assembly, deployment of these forces in the structure and a sequential correction procedure of the stay forces from the determination of adjustment forces.

Dissertation submitted in compliance with the requirements for Master's Degree in Technology: Electrical Engineering (Light Current), Durban Institute of Technology, 2002. / Modern society as a whole seems destined to have an ever-increasing demand for power for both industrial and domestic use, as continued population growth means that cities, suburbs and industrial areas become larger and denser. At the same time the trend toward increased productivity in all segments of industry is influencing the development and techniques employed at locating faults in power cables and networks to ensure only limited downtime and reduced direct and indirect costs associated with the location of faults / M

No autorizada por el autor para ser publicada a texto completo / Un cable es un elemento estructural utilizado fundamentalmente para transmitir carga axial. Sin embargo existen otros tipos de esfuerzos, que se pueden transmitir en el cable, tales como la flexión. La modelación analítica de un cable es compleja debido a que los elementos que lo forman están sometidos a diversos tipos de esfuerzos internos, posibles deslizamientos relativos entre sus elementos, a la naturaleza no lineal de su geometría y eventualmente a la no linealidad de las leyes constitutivas de los materiales que lo forman. En particular, la investigación en el campo de la modelación de cables en flexión ha propuesto numerosos modelos analíticos que permiten predecir su comportamiento mecánico. Sin embargo, pocos estudios comparan estos modelos entre sí, o discuten los rangos de aplicabilidad en que son válidos. El objetivo de este trabajo es describir siete modelos analíticos discretos lineales, comúnmente citados en la literatura, desarrollados para predecir el comportamiento de cables sujetos principalmente a flexión. Estos modelos consideran una ley constitutiva de los elementos que forman el cable lineal y el potencial deslizamiento relativo entre éstos producto de incrementos en la curvatura del cable. Dichos modelos se comparan con datos experimentales reportados en la literatura (cables cuyos diámetros varían entre 0.5 y 15 mm) y con modelos propuestos basados en la combinación de las hipótesis de los siete modelos descritos. Basado en las comparaciones con datos experimentales, el modelo que mejor predice el comportamiento de un cable en flexión es el modelo propuesto C-P basado en los modelos individuales de los autores Costello y Papailiou. Este modelo además incorpora los efectos de la carga axial y torsión en el cable. El modelo C-P predice las tensiones normales en los elementos que forman el cable y la relación momento-curvatura del cable con un error promedio no superior al 20% con respecto a los datos experimentales.

Ingeniero Civil / En el presente trabajo se presenta un modelo mecánico no lineal simplificado para estimar la curva de capacidad residual de un cable dañado en forma asimétrica. Se considera daño la degradación de las propiedades mecánicas de los componentes que forman el cable incluyendo la fractura de éstos. Este modelo es capaz de predecir el gradiente de tensiones y deformaciones en la sección transversal de un cable dañado asimétricamente producto de la concentración de tensiones y deformaciones en los componentes adyacentes al daño. Esta concentración puede producir una falla temprana de los componentes del cable y por consiguiente reducir la carga axial máxima y la deformación axial de fractura en comparación a un cable sin daño. El modelo propuesto (MP) se basa en un análisis de una viga plana no lineal con pequeñas deformaciones considerando hipótesis de Bernoulli. Se asume que el cable está sometido a una carga axial y a una fuerza de corte por unidad de longitud, distribuida en forma uniforme, e inducida por la pérdida de la simetría de la sección transversal del cable. Esta fuerza de corte presenta componentes en los planos vertical y horizontal de manera de representar la geometría helicoidal inicial de los componentes que forman el cable. La solución de la ecuación diferencial resultante en los planos vertical y horizontal permite estimar la deformada del cable para posteriormente, realizando un análisis seccional iterativo, estimar las distribuciones de tensiones y deformaciones; la capacidad axial y deformación de fractura. El modelo propuesto es validado mediante comparaciones con modelos 3D de elementos finitos (Vargas, 2010), datos experimentales de cables de poliéster dañados simétricamente de 6 mm de diámetro con diferentes grados de asimetría (Li et al., 2002), y con modelos mecánicos propuestos en la literatura. (Lanteigne, 1985; MacDougall y Bartlett, 2006). A partir de los resultados obtenidos en este estudio, se concluye que los modelos reportados en la literatura estiman de forma satisfactoria la respuesta de un cable dañado en forma asimétrica en aquellos casos en que el grado de asimetría de su sección transversal, cuantificado a través del índice de asimetría IA, es menor que 0.2. Por el contrario, el modelo propuesto en este estudio abarca un mayor rango de asimetría de daño (desde IA=0.093 para el cable W(136) hasta IA=0.538 para el cable W(1234), este último corresponde al cable de mayor asimetría presentado en este trabajo) y presenta diferencias, en relación a los datos dados por los modelos de elementos finitos, de un 9.6% promedio en relación a la capacidad residual, un 3% promedio para la distribución de tensiones y deformaciones y menos de un 1% promedio para la deformación de fractura del cable. Los resultados de MP indican que la configuración inicial recta del cable es ligeramente perturbada producto de la asimetría de su sección transversal, induciendo una flexión que se traduce, considerando la máxima asimetría analizada en este estudio (IA =0.538), en una disminución de la capacidad de deformación del cable de un 7% con respecto al cable sin daño y en una reducción adicional de un 8% en capacidad residual axial sobre el valor entregado por el área neta. Este modelo además de entregar buenos resultados, tiene la ventaja por sobre los modelos de elementos finitos que los tiempos de análisis son reducidos.

A large number of building inventory in Canada and elsewhere in the world consists of non-ductile reinforced concrete frames, with or without masonry infill panels. These structures suffer damage when seismic force demands are higher than their force capacities. Therefore, seismic retrofitting of such frame buildings for drift control remains to be a viable option for improved building performance. A retrofit methodology has been developed in the current research project, which involves diagonal bracing of frames with prestressing strands. An experimental research project has been conducted to assess the effectiveness of diagonal prestressing in non-ductile reinforced concrete frame buildings. The experimental program consists of two large-scale single-bay single-storey reinforced concrete frames, with a height of 3.0m and a span length of 3.5 m. The frames were designed and built to reflect the 1960’s practice in Canada, without the seismic requirements of current building codes, and hence are seismically deficient. They were retrofitted with diagonally placed prestressing strands, having two different areas of steel, prestressed to 40% of the strand capacity. One of the frames was retested after the failure of the strands, with a new set of strands without any prestressing, forming the third test. The results indicate that lateral bracing reinforced concrete frames with high-strength prestressing strands is an effective strategy for controlling lateral drift and hence potential damage in buildings during strong earthquakes. Prestressing of the strands increases initial stiffness, as compared to non-prestressed cables, and provide superior performance. The area of diagonally placed steel (including the number of strands) and the level of initial prestressing depend on the required level of upgrade in the building in terms of seismic force requirements. The design procedure recommended in this thesis may be employed for implementing the technology. The thesis presents the details of the experimental program, and the test results. It also provides analytical verification of the approach, with a step-by-step design procedure.