Estudo sistemático de estrelas variáveis na era dos grandes surveys

The interest in the systematic analysis of astronomical time series data, as well as development in astronomical instrumentation and automation over the past two decades has given rise to several questions of how to analyze and synthesize the growing amount of data. These data have led to many discoveries in the areas of modern astronomy asteroseismology, exoplanets and stellar evolution. However, treatment methods and data analysis have failed to follow the development of the instruments themselves, although much effort has been done. In present thesis, we propose new methods of data analysis and two catalogs of the variable stars that allowed the study of rotational modulation and stellar variability. Were analyzed the photometric databases fromtwo distinctmissions: CoRoT (Convection Rotation and planetary Transits) and WFCAM (Wide Field Camera). Furthermore the present work describes several methods for the analysis of photometric data besides propose and refine selection techniques of data using indices of variability. Preliminary results show that variability indices have an efficiency greater than the indices most often used in the literature. An efficient selection of variable stars is essential to improve the efficiency of all subsequent steps. Fromthese analyses were obtained two catalogs; first, fromtheWFCAMdatabase we achieve a catalog with 319 variable stars observed in the photometric bands Y ZJHK. These stars show periods ranging between ∼ 0, 2 to ∼ 560 days whose the variability signatures present RR-Lyrae, Cepheids , LPVs, cataclysmic variables, among many others. Second, from the CoRoT database we selected 4, 206 stars with typical signatures of rotationalmodulation, using a supervised process. These stars show periods ranging between ∼ 0, 33 to ∼ 92 days, amplitude variability between ∼ 0, 001 to ∼ 0, 5 mag, color index (J - H) between ∼ 0, 0 to ∼ 1, 4 mag and spectral type CoRoT FGKM. The WFCAM variable stars catalog is being used to compose a database of light curves to be used as template in an automatic classifier for variable stars observed by the project VVV (Visible and Infrared Survey Telescope for Astronomy) moreover it are a fundamental start point to study different scientific cases. For example, a set of 12 young stars who are in a star formation region and the study of RR Lyrae-whose properties are not well established in the infrared. Based on CoRoT results we were able to show, for the first time, the rotational modulation evolution for an wide homogeneous sample of field stars. The results are inagreement with those expected by the stellar evolution theory. Furthermore, we identified 4 solar-type stars ( with color indices, spectral type, luminosity class and rotation period close to the Sun) besides 400 M-giant stars that we have a special interest to forthcoming studies. From the solar-type stars we can describe the future and past of the Sun while properties of M-stars are not well known. Our results allow concluded that there is a high dependence of the color-period diagram with the reddening in which increase the uncertainties of the age-period realized by previous works using CoRoT data. This thesis provides a large data-set for different scientific works, such as; magnetic activity, cataclysmic variables, brown dwarfs, RR-Lyrae, solar analogous, giant stars, among others. For instance, these data will allow us to study the relationship of magnetic activitywith stellar evolution. Besides these aspects, this thesis presents an improved classification for a significant number of stars in the CoRoT database and introduces a new set of tools that can be used to improve the entire process of the photometric databases analysis

Aplicação da metodologia seis sigma em uma empresa de médio porte do setor têxtil

The Six Sigma methodology has received considerable attention in the last two decades. This is due to its great potencial to reduce processes variability, through the use of accurate data, facts and statistical techniques. The methodology seeks to improve the quality of products and services, maximizing the company s financial performance. Specifically, its implementation and results in medium-sized textile enterprises is unknow, although there are signs that the methodology can be applied with success. Considering this scenario, the goal of this research is to describe the application of the Six Sigma methodology in a médium-sized textile company specialized in the production of male shirts in the satate of Rio Grande do Norte, Brazil. First, we present a literature review, seeking to highlight the themes of quality, Six Sigma and its methodology for improvement. Then, we show the implementation of the project selected, depicting the steps and procedures that must be performed. The results confirm the efficiency of Six Sigma in providing significant gains to companies. It is observed substantial improvements in the speed of product development and the flexibility of the parts produced, reducing the process lead time from 12.5 to 6.2 days, which means a performance improvement of over 50%. This leads also to cultural and behaviour change, creating motivation for implementation of new projects and a continuous search for knowledge

Uma proposta para preparação de pequenas e médias empresas brasileiras prestadoras de serviços ao setor de telecomunicações para implantação da metodologia Seis Sigma

The objective of this work consists of considering a script so that operating companies in the telecommunications sector, mainly small and medium-sized enterprises, can reach excellency in its operations and get, thus, conditions to compete with companies consolidated in its niche of market. The proposal intends to lead the enterprises to a level of qualification of processes that to become them apt to adopt the Six Sigma method as part of its culture. From the analysis of the essential processes of the sector, methods and tools will be suggested for guarantee the continuous improvement of these processes, without forgetting the internal peculiarities of each company

Seis sigma :uma proposta para implementação da metodologia em pequenas e médias empresas

The Six Sigma methodology consists of a program guided to the continuous improvement of enterprise processes, which aims at customer satisfaction, as well as increasing financial and operational profits. Considering that more than 99% of the Brazilian companies have up to five hundred employees, this study investigates how Six Sigma can be applied in small or medium size companies. This study was conducted based on literature review and application of the ideas in a medium size newspaper company, which manufactures newspapers that circulate daily in the state of Rio Grande do Norte. The results of the research point to the viability of use of the methodology in this market segment, as well as suggest a method that can be used in similar companies