Civilizações da cana-de-açúcar : dois paradigmas de atividades agroaçucareiras no novo mundo, séculos XVI a XIX

From the Brazilian coast to its inland, sugarcane molded economic, social and cultural landscapes with distinctive identities. The monotony of extensive sugarcane plantations was transformed as this culture started to grow along with other cultivations, with livestock, with several rural industries and with mineral extraction as well. The monopoly of engenho açucareiro was transformed into both, engenhos rapadureiros and engenhos aguardenteiros. These engenhos were immersed in consortiums grounded in the complementarity and interdependence of several actitivies. The fundamental characteristics dictated from the outside of the Colony unfolded into the autonomy and plasticity conformed by both, geographical isolation and decentralization of domestic markets. Distinct sugarcane plantation trajectories forged distinctive historical paradigms and later defined multiple rythms in the moving from the traditional to the modern. The civilization of sugar along the coast, with monolithic and compact inheritance, expanded into the plurality of inland sugarcane civilizations, with fragmentary and diffuse legacies.sugar plantation activities; historical paradigms; Brazil – Americas; 16th to 19th centuries

O primado do mercado interno: a proeminência do espaço canavieiro de Minas Gerais no último século de hegemonia das atividades agroaçucareiras tradicionais no Brasil

During 19th century and the beginning of the following century Minas Gerais was the most important sugarcane plantation area in Brazil. In the 1830's there were presumably 4.150 productive unities working with sugarcane transformation in Minas Gerais. Probably, the sum of all sugar mills in the main regions producing to foreign markets - northeast coast, north of Rio de Janeiro and the plains of São Paulo - did not reach half of the number of sugar mills in Minas Gerais. In the same period, it is estimated that approximately 40% of the slave working force of Minas - more than 85.000 captives - was employed seasonally in the fabrication of sugar, of rapadura and of aguardente. It is high the possibility that such a large contingent had neither been employed in any other sugarcane plantation area nor in any other period of Brazilian slavery history. Furthermore, it is estimated that in the 1830's Minas Gerais produced around 33.200 tons of sugar and of rapadura, and more than 22 million liters of aguardente. According to the available information, it is suggested that the sugar production of the state of São Paulo did not surpass 8.500 tons, and the production of the state of Pernambuco was about 27.000 tons. The sugar exportation of the state of Bahia was not more than 30.000 tons; the amount exported by Rio de Janeiro did not reach 17.000 tons; the provinces of Alagoas and Sergipe exported together less than 6.000 tons.Sugar plantation activities; domestic market; Minas Gerais; Brazil; 19th and 20th centuries

Persistência do tradicional: o processo de modernização da agroindústria canavieira do Brasil e a sobrevivência de formas produtivas não-capitalistas

Sugarcane plantations industry, the oldest and more important activity of rural transformation in Brazil, experienced profound metamorphosis in twentieth century. This process began in the last quarter of the previous century, and resulted in the progressive establishment of an essentially new reality. Those changes were grounded on technological modernization, which was always legitimated by the ideology of progress and led by the big rural, industrial and commercial capitals which controlled the sugarcane plantations sector. Among the political transformations which changed the Brazilian State profile and molded economic policies based on another institutional structure and on distinct instrumental resources, the incisive intervention by the State in sugarcane activities, since the beginning of the third decade of twentieth century, was regulated by meeting classes' interests. The State was protagonist of transformations which resulted in intensification of an age long process of expropriation and impoverishment for the great majority of producers and workers. Nevertheless, the perversion of the concept 'modern', expressed in economic and technological transformations along with the preservation or deterioration of archaic social structures, made possible the survival and reproduction of the traditional. The maintenance of non-capitalist forms as a way to amplify the exploration of work and optimize profit was of particular interest to the capital.Sugarcane plantation activities; modernization; Minas Gerais; Brazil

On the quantification of CMCs damage mechanisms by acoustic emission and machine learning

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2022.Compósitos de matriz cerâmica (CMCs) destacam-se devido a sua baixa densidade e marcantes propriedades mecânicas. Os constituintes que os formam podem ser todos não óxidos (NOx-CMCs), todos óxidos (Ox-CMCs) ou uma mistura de ambos. Em geral, o primeiro apresenta propriedades mecânicas mais desejáveis, enquanto o segundo se destaca em ambientes agressivos devido à sua resistência à oxidação. Uma mistura pode ser usada dependendo das condições de aplicação. Esses materiais são reconhecidos por não apresentarem comportamento frágil, mas quasi-dúctil. A tolerância a danos dos CMCs é possível devido a vários mecanismos de deflexão de trincas, como: trincamento (matrix cracking), desplacamento (interface debonding) e arrancamento (pull-out). Portanto, entender como esses mecanismos de tenacificação funcionam é crucial para o desenvolvimento posterior desses compósitos. Neste trabalho, testes mecânicos em conjunto com monitoramento por emissões acústicas (AE) foram realizados para estudar o desenvolvimento de danos durante o carregamento de CMCs. Testes mecânicos específicos forneceram meios para simular os mecanismos de tenacificação. Os sinais de AE foram relacionados a cada mecanismo e usados para obter um conjunto de dados de treinamento, utilizado para criar um modelo de aprendizado de máquina supervisionado. O modelo foi então usado para classificar sinais de AE medidos durante o carregamento de compósitos de matriz de carbeto de silício reforçada com fibras de carbono, e matriz de alumina reforçada com fibras de alumina (Cf/SiC e Al2O3f/Al2O3 respectivamente). Os resultados obtidos mostraram que o modelo pode ser aplicado com sucesso para identificar os mecanismos de tenacificação. A quantidade de mecanismos acionados, e energia dissipada por eles durante o carregamento mecânico é representada em percentuais totais de ocorrência. Amostras de placas compósitas de Cf/SiC foram previamente fadigadas, e as mudanças promovidas pelos ciclos de fadiga puderam ser avaliadas. Os ciclos de fadiga promoveram um aumento de eventos de arrancamento, desplacamento, e ruptura de fibras (fiber break). Amostras de minicompósitos e placas compósitas de Al2O3f/Al2O3 apresentaram desenvolvimento de falha distinto. Em geral, minicompósitos apresentaram a maior parte de sua energia dissipada pela ruptura de fibras (~86%), enquanto as placas compósitas apresentaram a maior parte de sua energia dissipada pelos mecanismos de deflexão (~57%).Abstract: Ceramic matrix composites (CMCs) stand out due to their low density and remarkable mechanical properties. The constituents that form them can be either all non-oxide (NOx-CMCs), all-oxide (Ox-CMCs), or a mixture of both. In general, the former has more desirable mechanical properties, while the second stands out in aggressive environments due to their oxidation resistance. A mixture can be used depending on the application and environment conditions. Unlike monolithic ceramics, these materials are known for presenting a non-brittle fracture. The damage tolerance of CMCs is possible due to several crack deflection mechanisms, such as matrix cracking, interface debonding, and fiber pull-out. Hence, understanding how these damage mechanisms work is crucial for the further development of these composites. In this work, mechanical tests jointly with acoustic emission (AE) monitoring were performed to study the damage development during the loading of CMCs. Specific mechanical tests provided means for simulating the damage mechanism. AE signals were related to each mechanism and used to obtain a training dataset for a supervised machine learning model. This approach is advantageous since each damage mechanism was analyzed individually. The model was then used to classify AE signals measured during mechanical tests of carbon fiber-reinforced silicon carbide matrix and alumina fiber-reinforced alumina matrix composites (Cf/SiC and Al2O3f/Al2O3 respectively). The results obtained have shown that the model can be successfully applied to identify the damage mechanisms. Furthermore, through this technique it is possible to evaluate the amount of mechanisms triggered, and energy dissipated by them during mechanical loading. These results are represented in total percentages of occurrence. Cf/SiC composite plate samples were previously fatigued, and the changes promoted by fatigue cycles could be evaluated. The fatigue cycles promoted an increase in pullout, debonding, and fiber break events. Al2O3f/Al2O3 minicomposite and composite plate samples showed distinct failure development. In general, minicomposites showed most of their energy dissipated by fiber break (~86%), while composite plates showed most of their energy dissipated by deflection mechanisms (~57%)

Uma outra modernização: transportes em uma província não-exportadora - Minas Gerais, 1850-1870

Between 1750 and 1880, Minas Gerais developed an economy predominantly non-exporting as well as relatively independent of external markets of other Brazilian regions and of foreign markets. Due to such unique historical evolution, contemporaries had to develop specific understanding and ways of dealing with transportation problems. In nineteenth century, mainly in its third quarter, it were established the conditions for the modernization process of transportation in Minas. Those conditions allowed such modernization to take place apart from the determinations resulting from the hegemony of a primarily exportation economic model, specially based on hastening the construction of an integrated system. This text enlarges considerations about the history of transportation in the province of Minas Gerais. It presents and analyses documental evidences which demonstrate it can be mistaken the understanding of modernization of Brazilian transportation considering a single model as well as the tendency to generalize to the whole country the historical experience of modernization based upon a railroad system.transportation; constitution of domestic market; modernization process; province of Minas Gerais