Made available in DSpace on 2014-10-09T12:36:48Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:30Z (GMT). No. of bitstreams: 1 02300.pdf: 1632925 bytes, checksum: bc27e10df4b0bc6c8147285747f6eccf (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-08-29T13:41:49Z No. of bitstreams: 1 DAMARES SANTOS SILVA BORGES - DISSERTAÇÃO (PPGF) 2018.pdf: 14903609 bytes, checksum: 19118754fe275415f701d012e1d4515e (MD5) / Made available in DSpace on 2018-08-29T13:41:49Z (GMT). No. of bitstreams: 1 DAMARES SANTOS SILVA BORGES - DISSERTAÇÃO (PPGF) 2018.pdf: 14903609 bytes, checksum: 19118754fe275415f701d012e1d4515e (MD5) Previous issue date: 2018-07-26 / Capes / Os defeitos topológicos são caracterizados como soluções estáveis de equações de movimento em uma ou mais dimensões espaciais e desempenham papel importante na ciência não-linear. Neste trabalho de dissertação, damos ênfase a defeitos em (1+1) e (2+1) dimensões espaço-temporais. No primeiro caso, abordamos configurações conhecidas como twistons (soluções topológicas tipo kink) presentes em cristais de polietileno. Nessa primeira abordagem, revisitamos trabalhos anteriores e, a partir do método de extensão, construímos novas famílias de potenciais que descrevem bem sistemas desse tipo. Apresentamos soluções topológicas analíticas e que não possuem problemas de degenerescência infinita. No segundo caso, estudamos estruturas conhecidas como skyrmions com base na sua descrição em materiais magnéticos, em que são denotados como configurações da magnetização em nanoescala e topologicamente estáveis.Recorremos novamente ao método de extensão e apresentamos um potencial, função de dois campos escalares acoplados, a partir do qual conseguimos modelar essas estruturas magnéticas. Além disso, o novo modelo de dois campos tem soluções analíticas conhecidas, permitindo análises interessantes como a determinação de uma quantidade topológica conservada, estudo das diferentes configurações da magnetização e cálculo do raio médio de matéria. / Topological defects are characterized as stable equation of motion solutions in one or more spatial dimensions and play an important role in nonlinear science. In this study, space-time (1 + 1) and (2 + 1) dimension defects are emphasized. In the first case, configurations known as twistons (kink-like topological solutions) present in polyethylene crystals are assessed. In this first approach, previous works were reviewed and new families of potentials that adequately describe these types of systems were constructed from the extension method, presenting analytical topological solutions that do not display infinite degeneracy problems. In the second case, structures known as skyrmions were studied based on their description in magnetic materials,where they are denoted as topologically stable nanoscale magnetization configurations. The extension method was applied and a potential from which such magnetic structures can be modelled, function of two coupled scalar fields was presented. In addition, the new two-field model possesses known analytical solutions, allowing for interesting analyses, such as the determination of a conserved topological quantity, the study of the different magnetization configurations and calculation of mean matter radius.

For this study, two analytical models were developed for predicting the depth-averaged velocity distribution (U) in trapezoidal, half-trapezoidal and rectangular channels with submerged and unsubmerged rigid cylinders. The first model uses linear superposition of momentum defects (MDS) and mass conservation, and is referred to as the MDS model. The second model uses linear superposition of velocity defects (VDS) and mass conservation, and is referred to as the VDS model. For implementing either the VDS or MDS model, a criterion is required for considering the wake created by an individual cylinder to be fully dissipated (i.e., a cutoff criterion). Also, implementing the MDS model requires numerical integration. Analyses were conducted to identify suitable cutoff criterion and an appropriate subinterval size for the numerical integration. Data from a physical model study conducted in a flume with a half-trapezoidal channel section was used to calibrate and validate the models. Data from a physical model study conducted in a rectangular channel section was also used to validate the model. Predicted values of U from the VDS and MDS models were within the range of ± 20 % of the trapezoidal channel section validation data. The models failed to accurately predict U for the rectangular channel section data. It is concluded that the models developed herein should be used only for half-trapezoidal channel sections. With respect to the trapezoidal channel section validation data, the MDS model yields a sum of squared errors that is 36% less than that yielded by the VDS model. Therefore, the MDS model is regarded as the best model overall for computing U in half-trapezoidal channel sections.

Lean techniques are tools that reduce waste in the process and create value for the end-customer. Initially, the concept of lean thinking started in manufacturing, but with the tremendous advantages it offers in terms of value creation for the customer, defect reduction, increase of profits for corporations, it has been recognized as an important tool across a wide spectrum of industries. Although Healthcare industry has started applying these techniques, there is very little work published on how to apply these techniques to this particular industry. In this study, a framework for applying lean thinking to healthcare industries is presented. The framework depicts a systematic methodology for identifying value streams. The framework was developed specifically for the healthcare industry, but it can be applied to service industry in general. A case study is presented on how to apply this framework. Value stream mapping has been conducted at a clinic to identify areas of improvement. The components of the developed framework have been used to define a future state of process based on input from process owners, nurses, physicians, and patient surveys. The study has identified factors that influence the success of implementation of lean techniques in healthcare. Also the potential for future work has been identified.

No description available.

The main aim of this work was the machining by hard turning of surfaces with optical surface quality. A numerical target had been set as a surface roughness Ra = 10nm. It has been shown that achieving roughness of that magnitude by hard turning is possible. Individual work pieces exhibited the desired surface properties for short lengths at a time, but it proved to be very difficult to achieve these surfaces consistently and over longer cuts. The factors influencing the surface roughness were identified as tool defects and machine vibration in addition to the standard cutting parameters and choice of cutting tool. A model of surface generation in hard turning has been developed and good correlation between simulated and experimentally determined surface roughnesses was achieved. By introducing a material partition equation which determines the proportional contribution of material removal mechanisms in the undeformed chip a comprehensive method for assessing the contributing factors in material removal was developed. While it has been shown that surfaces in hard turning are almost exclusively generated by chip removal and plastic deformation the developed model is versatile enough to include elastic deformation of the work piece. With the help of the model of surface generation in hard turning it has been possible to attribute magnitudes of the influencing factors with respect to the cutting parameters such as feed rate and tool corner radius, and the main disturbances - tool defects and machine vibration. From this conclusions were drawn on the requirements for machine tools and cutting tools, which will need to be realised to make ultra-precision hard turning of surfaces of optical quality a feasible manufacturing process.

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Made available in DSpace on 2014-10-09T12:24:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:22Z (GMT). No. of bitstreams: 1 01006.pdf: 8094548 bytes, checksum: 61ae42e710d289b8eb23e8b04cbefe14 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Fisica, Universidade de Sao Paulo - IF/USP