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O impacto do salário-mínimo e dos ciclos econômicos no desemprego juvenil brasileiro
(Universidade Federal de São Carlos, 2013-06-10) Lima, Tânia de Toledo; Rodrigues, Rodrigo Vilela; https://lattes.cnpq.br/7066100737307566; https://lattes.cnpq.br/2281900658271883; Almeida, Alexandre Nunes de; http://lattes.cnpq.br/8825551833619350; Bragagnolo, Cassiano; http://lattes.cnpq.br/3604206454925741
This research sought to understand the Brazilian youth unemployment in the period 2003 - 2011. The aim of this study is to verify if the business cycles and changes in the minimum wage have been affecting youth unemployment, considering the control of socioeconomic variables. In order to develop such analyses, this study has considered linear panel data as one estimation method and dynamic panel as the other method. In addition, the current research has been considered the four initial interviews contained in PME database. The results of the study show that the youth unemployment rate has been affected by economic cycles, wages and socioeconomic variables, like proportion of labor force non-white , formal sector and metropolitan region that the individual belongs to. Concerning the dynamic character, the previous level of youth unemployment and economic cycles are the main factors affecting the variability of youth unemployment rate. It is worth mentioning that the present study splits the youth group into two subcategories, "teens" and "young-adults", aiming at verifying whetherthe cycles and wages have been impacting in a similar fashion. Thus, the results show that the two distinct subcategories demonstrate different sensitiveness, making room for the creationof different public policies.
Influência da freqüência da corrente alternada da nitretação a plasma nas propriedades superficiais do aço inoxidável ASTM F138
(Universidade Federal de São Carlos, 2013-06-10) Silva, Edilaine Honorio da; Souza, Maristela Olzon Monteiro Dionysio de; https://lattes.cnpq.br/9452239672967881; https://lattes.cnpq.br/2669985375702449
Plasma nitriding is a technique which is used in surface treatments of stainless steel, in order to improve some properties like hardness, wear and corrosion resistance. The nitrided layer consists of some iron nitrides: the cubic y´ phase (Fe4N), the hexagonal yphase (Fe2-3N) and a nitrogen supersatured solid phase yN. Moreover, the phases which are formed and their amount are related to the nitriding parameters: time, temperature, gas mixture (N2/H2) and pressure. On the other hand, the equipment used in this study can be operated using AC or DC current. If the AC current is used, its frequency can vary and possibly influence the Fe-N phase formation as well. In order to study this influence, some ASTM F138 stainless steel disks, showing 19,00 ± 0,01 mm diameter and 2,00 ± 0,01 mm thickness, were plasma nitrided for 4h, at 400ºC, in a 80%H2 - N2 gas mixture, at a pressure of 6 Torr, using AC current, at 6, 12, 30, 60 e 100 kHz. The samples were characterized using Scanning Electron Microscopy, Magnetic Force Microscopy, X Ray Diffraction, Hardness Vickers and Mössbauer Spectroscopy. X Ray Diffractions results detected peaks of yN phase for all samples, which showed higher hardness when compared with matrix. Nitrided layer thickness seems not to be influenced by frequency, except for 12kHz, which produced a layer whose thickness (approximately 8 ym) was about 40% thicker than the average for the other samples. Magnetic Force Microscopy showed that nitrided layer is magnetic near the surface and is paramagnetic in the innermost layer near the matrix. Mössbauer Spectroscopy demonstrated the presence of the yN, yand y´ phases. Moreover, it showed that, although the most superficial region seems to be essentially magnetic, there is also a small contribution of paramagnetic phases. Finally, the samples which were nitrided using 12 kHz showed the best results.