Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-26T18:46:17Z No. of bitstreams: 1 emanuelantonioefreitas.pdf: 387559 bytes, checksum: 6172ab4c13588ec4c374331340b9785d (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-07T20:48:36Z (GMT) No. of bitstreams: 1 emanuelantonioefreitas.pdf: 387559 bytes, checksum: 6172ab4c13588ec4c374331340b9785d (MD5) / Made available in DSpace on 2017-08-07T20:48:36Z (GMT). No. of bitstreams: 1 emanuelantonioefreitas.pdf: 387559 bytes, checksum: 6172ab4c13588ec4c374331340b9785d (MD5) Previous issue date: 2010-03-22 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / No estudo da Gravitação é possível escrever a métrica utilizando um fator conforme, sendo a simetria conforme um aspecto importante em Cosmologia. Assim, apresentamos nesta tese um estudo sobre esse tópico na primeira parte do trabalho, no qual estão incluidas técnicas de cálculo de termos lineares e quadráticos na curvatura em exemplos de interesse físico. A importância de tais técnicas está no fato de possibilitarem a obtenção das equações, necessárias no estudo da gravitação, através de um procedimento eficaz com maior simplicidade com relação ao método tradicional. Em seguida foi realizada uma investigação dos efeitos da torção na teoria de Einstein-Cartan para o universo primordial. Nesta tese foi realizado um estudo das soluções para um fluido de spin relativístico de Weyssenhoff homogêneo e isotrópico e uma corrente axial tipo-tempo, também homogênea e isotrópica. As soluções gerais podem ser descritas em termos de três soluções particulares. As propriedades e aspectos dessas soluções, tais como ausência de singularidade e expansão acelerada, foram analisadas e dependem das relações entre os parâmetros das fontes. / In gravitation, it is possible to write metric tensor using a conformal factor. In this sense, conformal symmetry is an important feature in Cosmology. We firstly present a useful study on this subject, along with several techniques of calculating linear and quadratic terms on curvature. Next, we investigate the effects of torsion in the framework of Einstein-Cartan theory in early cosmology. We study solutions for a homogeneous and study solutions for a homogeneous and isotropic relativistic Weyssenhoff spin fluid with dynamical timelike axial current, also homogeneous and isotropic. The general solutions can mostly be described by means of three particular solutions. The properties of these solutions (such as singularity avoidance and primordial or late accelerated expansion) are analysed and depend on the relations between the source parameters.

Few decades ago, there were no guidelines for torsion design of reinforced concrete (RC) beams. Hence, many existing beams in older buildings have a lack of adequate torsional strength since they were not properly designed for torsion. One way to regain/rehabilitate adequate torsional strength is through application of externally bonded carbon fiber reinforced polymers (CFRP). To date, American Concrete Institute (ACI) code, as well as other building codes, do not have recommendations or provisions for strengthening RC beams for torsion using fiber-reinforced polymer (FRP) composites due to the inexistence of conclusive experimental and analytical data. Of the very limited works on this behavior, the majority of the focus has been devoted to experimental works. Realistic spandrel beams in a building that lack torsional strength were modelled in this research, and strengthened to examine various behaviors such as load capacity, deflection, torque, twist, crack propagation, ductility, and failure modes. For this purpose, six RC beams were tested: four reference beams and two strengthened beams were used to observe additional capacity through the use of carbon fiber-reinforced polymer (CFRP) sheets. To strengthen the beams, one layer of sheets was completely wrapped around them. Results show an additional torsional capacity of 63% and 178% relative to their respective reference beams. Through strengthening, modes of failure of the beams changed from brittle torsion-dominated failure to shear-flexure failure in both beams. The study also included crack pattern and ductility of test beams. Cracks became smaller in width and more evenly distributed across the torsion-loaded area, and torsional ductility was enhanced by 266% and 165% respectively. Flexural ductility was also greatly enhanced by more than five folds. Finally, using ACI 318-14, ACI 440.2R-02, and available formulae in the literature, the beams were analyzed and the respective values were compared.

No description available.

Orientador: Euripedes G. O. Nobrega / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-24T03:12:13Z (GMT). No. of bitstreams: 1 Khater_Evaldo_D.pdf: 6371414 bytes, checksum: 2bbb7e16fb992bc5ae751840e548a367 (MD5) Previous issue date: 1998 / Resumo: O presente trabalho visa o desenvolvimento de estratégias de controle de vibração torcional em sistemas rotativos, com o objetivo de atenuar os modos significativos da vibração em regime. O controle ativo é empregado através de um controlador neural multicamada, usando o método da retropropagação do erro. O sistema é realimentado através do próprio motor elétrico (CC) do acionamento. Uma bancada experimental de um sistema rotativo é utilizada para o ajuste do modelo, teste do controlador ótimo (LQR) e na emulação do modelo experimental usando rede neural multicamada para treinar o controlador adequado ao sistema real. Um circuito eletrônico embarcado na extremidade do eixo flexível, transmite o sinal amplificado da deformação angular indicada por uma ponte de extensômetros elétricos. Resultados satisfatórios foram encontrados tanto na simulação computacional como nos testes experimentais, demonstrando que um controlador neural pode ser uma boa alternativa para os sistemas rotativos reais / Abstract: The purpose of this work is the development of control strategies of torsional vibration in rotating systems, with the objective of minimizing the significant modes of torsional vibration in steadystate. The active control was employed through a multilayer neural network controler, using back-propagation, feeding the system with the same driving electric motor (DC). A experimental model of the rotating system was employed to adjust the theorical model, test the optimal controler (LQR) and emulation the experimental model using a multilayer neural network to train the appropriate controler to the real system. A electronic circuit attached at the end of flexible shaft sends the amplified signal of angular strain measured. Satisfactory results were found both in the computacional simulation and in the experimental tests, showing that a neural controler can be a good choice for real rotating systems / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica

Orientador: Rene Brenzikofer / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação Fisica / Made available in DSpace on 2018-07-19T06:10:52Z (GMT). No. of bitstreams: 1 Ortale_RenataLanducci_M.pdf: 1976071 bytes, checksum: 279fd16f5e25de85f875d6b90acfe76d (MD5) Previous issue date: 1993 / Resumo: O propósito deste trabalho é apresentar um método para análise quantitativa e tridimensional da coluna vertebral em posição estática. O método apresentado utiliza registros fotográficos estereoscópicos, medição das imagens em mesa digitalizadora e análise dos dados através de programas computacionais, os quais foram desenvolvidos para agilizar os procedimentos da reconstrução e fornecer resultados quantitativos, sob a forma de gráficos, das curvaturas e das torções geométricas 3D da espinha. A reconstrução 3D dos pontos antõmicos, marcados na pele sobre os processos espinhosos da coluna vertebral, foi desenvolvido por BRENZIKOFER (1991, 1993). A análise matemática em termos de curvatura e torção geométrica 3D dos pontos anatômicos é obtida a partir de um ajuste polinomial por quadrados mínimos. Aplicamos este método em três voluntários, os quais foram submetidos a uma avaliação postural clinica, antes da realização dos experimentos fotográficos. Os pontos anatômicos foram marcados com adesivos autocolantes e contrastantes nos indivíduos na posição ereta e estática, prontos para serem fotografados. Os pontos de interesse, estenderam-se da base do occipital até o processo espinhoso da quarta vértebra lombar, somando um total de vinte pontos. Os resultados obtidos são apresentados sob a forma de seis gráficos, para cada sujeito: dois correspondem ao ajuste polinomial das projeções das curvas da coluna vertebral nos planos sagital e frontal, outros dois às curvaturas bidimensionais nos mesmos planos, um à curvatura 3D e finalmente à torção geométrica 3D. Em todos os gráficos estas variáveis estão representadas em função da coordenada vertical. Através do método ora proposto, detectamos as regiões da coluna onde aparecem as curvaturas e torções geométricas 3D. Também mostramos que o método desenvolvido permite quantificar, com boa sensibilidade, as deformidades da coluna vertebral, como por exemplo: lordoses, cifoses e escolioses. Os resultados obtidos mostraram uma boa correlação com os do diagnóstico clínico / Abstract: This paper aims at presenting a method for quantitative and tridimensional analysis of the spinal column in a static position. The method utilizes stereoscopic photographic registers, image measurement in digitalized table and data analysis using software developed in order to accelerate the reconstruction procedures and supply quantitative results in the format of graphs representing the 3D curvatures and geometrical torsions of the spinal column. The 3D reconstruction of the anatomic points, marked on the skin over the spinous processes, was developed by Brenzikofer (1991, 1993). The mathematical analysis of 3D curvature and torsion of the anatomic points is obtained through an adjustment of the parametric polynomial least square fit. This method was applied to three voluntary subjects who, before having their photographic registers taken, were submitted to a clinical posture evaluation. A total of twenty anatomic points were marked with contrasting adhesive disks. The subjects were in a static and upright position. The points of reference went from the occipital basis until the spinous process of the fourth lumbar vertebra. The results are presented in six graphs for each subject. Two graphs represent the polynomial fit of the projection of the spinal column curves in the sagittaland frontal plane. Two other graphs represent the bidimensional curvatures in the same planes. One graph represents the 3D curvature and the last one represents the geometric 3D torsion. In alI these graphs the variables are represented in function of the vertical coordinate. This method successfully detected in which areas of the spinal column 3D curvatures and geometrical torsions occur. It also enables the user to quantify, with accuracy, spinal column deformities such as, lordosis, kyphosis, and scoliosis. There is a positive correlation between the results of the proposed method and the clinical diagnosis / Mestrado / Mestre em Educação Física

The purpose of this thesis is design of a six-cylinder engine arrangement with given main parameters (bore, stroke, etc.), powertrain design, possibilities of firing order, balancing inertia forces and its moments, in case of need, balancing shaft design and calculation of torsion vibrations.

Diploma thesis is trying to analyze crank mechanism of a gas V-sixteen engine. Kinematics and balance crank mechanism are analyzed, dynamic model parameters are dermined, natural frequency of the torsional system are calculated, coupling parameters are designed and torsional problem with attached electric generator is analyzed.

The purpose of this thesis is design of a crank mechanism for diesel aircraft engine. Next then appropriately balance crank mechanism, strength tests and calculation of crankshaft torsional vibration. Developing of drawings documentation of crankshaft.

The primary objective of this thesis was to design a crankshaft according to given parameters. In this case the thesis also contains the balancing of inertia forces and its moments, modal analysis and calculation of torsion vibrations. The last chapter includes a calculation of the safety factor by using a Finite Element Method.

Martin Lhota Formula Student Front Chassis Part Design DW, IAE, 2011, 75 pp, 62 pics The aim of the thesis is to suggest a suitable configuration of Formula Student Car’s front part of a frame according to current rules of SAE organization in the Formula Student competition. In this proposal low weight, manufacturability and sufficient torsion rigidity were preferred, whereas previously suggested solutions were reflected. At first there is presented a list of important SAE rules for the construction of front part followed by a short recherché of development of the constructional solution of frames and frames suitable for Formula Students car. Secondly there is described process during frame construction design and its computational model for the analysis which simulates torsion with the support of MKP system. Gained results and some parameters of the frame are compared with similar version of the frame construction which was suggested and made for the first Formula Student Car of our University. Moreover, there is also presented summary of suggested frame and also recommendation with possible alternatives for the next development.