Orientador: Carlos Alberto Favarin Murari / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica / Made available in DSpace on 2018-07-13T21:51:42Z (GMT). No. of bitstreams: 1 Haffner_SergioLuis_M.pdf: 5766705 bytes, checksum: 2dd38aac5201f1b2d0e610b725549c54 (MD5) Previous issue date: 1990 / Resumo: Neste trabalho, a partir de um problema geral denominado fluxo de carga ótimo, formula-se o problema de planejamento de reativos em um sistema de energia elétrica. Apresenta-se um algoritmo, baseado na técnica da programação linear sucessiva, que permite determinar a localização e a capacidade dos componentes reativos necessários para a operação e a expansão do sistema de forma ótima. Utiliza-se, em cada problema linear, uma especialização do algoritmo Dual-Simplex que opera com uma função objetivo linear por partes. Para o modelo incremental linear, são apresentadas quatro matrizes de sensibilidade esparsas, oriundas de diferentes aproximações. Efetuam-se testes para verificar o funcionamento do método bem como comparar o desempenho das diversas matrizes de sensibilidade / Mestrado / Mestre em Engenharia Elétrica

Orientadores: Hermano de Medeiros Ferreira Tavares , Christiano Lyra Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica / Made available in DSpace on 2018-07-17T05:04:55Z (GMT). No. of bitstreams: 1 Friedlander_Ana_D.pdf: 5860003 bytes, checksum: 1ddc4e8e9761d2369c1f207eaae25cf3 (MD5) Previous issue date: 1986 / Resumo: Não informado / Abstract: Not informed. / Doutorado / Doutor em Engenharia Elétrica

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<p>An investigation of the steady state response of a non-linear system provided with an impact vibration absorber is made. The term non-linear in the present case refers to a system in which the spring restoring force is bi-linear./p><p> The effect of two main parameters viz. clearance d o (i.e. the free path of travel of the mass particle) and mass ratio μ = m/M (i.e. mass ratio between the mass particle and the primary system) on amplitude of vibration of the system has been investigated experimentally over a range of frequency.</p> <p>A numerical analysis of the problem is made with the aid of a digital computer to supplement the experimental results.</p> <p> It has been found that with proper choice of parameters an impact vibration absorber is effective in reducing vibration level of a nonlinear system undergoing sinusoidal excitation.</p> / Thesis / Master of Engineering (MEngr)

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published_or_final_version / abstract / Mathematics / Doctoral / Doctor of Philosophy

Design of buildings in earthquake regions requires that the building is made to withstand certain large earthquake magnitudes with a degree of permanent, but energy absorbing, damage. To accurately determine the behaviour of the building while damage occurs, a nonlinear analysis must be used as these effects are non-linear. These computations are often very slow as the building’s response must be calculated many times a second. This thesis seeks to find a faster alternative to the Newmark-β and similar numerical integration schemes commonly used in non-linear seismic structural analysis. Faster computation would enable rapid simulation thus speeding up the design process. It would also allow large Monte Carlo analyses to be done to improve research analysis and allow designers to better account for variability in materials, construction, soil site and other factors that can significantly affect response. For the purposes of this investigation simple two node finite elements were used. The nonlinear component consists of the well-accepted Ramberg-Osgood hysteresis model. The alternative approach used in this thesis is to solve non-linear first order differential equations using a Runge-Kutta based solution. This approach, with added new computational methods, should be more efficient than directly solving the second order equation of motion with Newmark-β. Different test cases were run to establish performance differences in a variety of potential user cases. These cases involved testing different models against both real earthquake data and synthetic input accelerations. In all test cases, the Newmark-β solution yielded the same results as the new solution, as long as a small enough time step was used. When a small time step was used and the results agreed, the new solution was much faster than the Newmark-β solution. In particular, the new numerical solution approach was significantly faster than Newmark-β when the accuracy demanded was 1% or less. As the tolerance was tightened the advantage of the new solution increased exponentially. From this project a set of MATLAB scripts has been created that will reproduce the results given and can also be used to analyse other building models. The overall approach used is also entirely generalisable.

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