Condutividade térmica de rochas: uma aplicação para granitos ornamentais

This dissertation focuses on rock thermal conductivity and its correlations with petrographic, textural, and geochemical aspects, especially in granite rocks. It aims at demonstrating the relations of these variables in an attempt to enlighten the behavior of thermal effect on rocks. Results can be useful for several applications, such as understanding and conferring regional thermal flow results, predicting the behavior of thermal effect on rocks based upon macroscopic evaluation (texture and mineralogy), in the building construction field in order to provide more precise information on data refinement on thermal properties emphasizing a rocky material thermal conductivity, and especially in the dimension stone industry in order to open a discussion on the use of these variables as a new technological parameter directly related to thermal comfort. Thermal conductivity data were obtained by using Anter Corporation s QuicklineTM -30 a thermal property measuring equipment. Measurements were conducted at temperatures ranging between 25 to 38 OC in samples with 2cm in length and an area of at least 6cm of diameter. As to petrography data, results demonstrated good correlations with quartz and mafics. Linear correlation between mineralogy and thermal conductivity revealed a positive relation of a quartz percentage increase in relation to a thermal conductivity increase and its decrease with mafic minerals increase. As to feldspates (K-feldspate and plagioclase) they show dispersion. Quartz relation gets more evident when compared to sample sets with >20% and <20%. Sets with more than 20% quartz (sienogranites, monzogranites, granodiorites, etc.), exhibit to a great extent conductivity values which vary from 2,5 W/mK and the set with less than 20% (sienites, monzonites, gabbros, diorites, etc.) have an average thermal conductivity below 2,5 W/mK. As to textures it has been verified that rocks considered thick/porphyry demonstrated in general better correlations when compared to rocks considered thin/medium. In the case of quartz, thick rocks/porphyry showed greater correlation factors when compared to the thin/medium ones. As to feldspates (K-feldspate and plagioclase) again there was dispersion. As to mafics, both thick/porphyry and thin/medium showed negative correlations with correlation factor smaller than those obtained in relation to the quartz. As to rocks related to the Streckeisen s QAP diagram (1976), they tend to fall from alcali-feldspates granites to tonalites, and from sienites to gabbros, diorites, etc. Thermal conductivity data correlation with geochemistry confirmed to a great extent mineralogy results. It has been seen that correlation is linear if there is any. Such behavior could be seen especially with the SiO2. In this case similar correlation can be observed with the quartz, that is, thermal conductivity increases as SiO2 is incremented. Another aspect observed is that basic to intermediate rocks presented values always below 2,5 W/mK, a similar behavior to that observed in rocks with quartz <20%. Acid rocks presented values above 2,5 W/mK, a similar behavior to that observed in rocks with quartz >20% (granites). For all the other cases, correlation factors are always low and present opposite behavior to Fe2O3, CaO, MgO, and TiO2. As to Al2O3, K2O, and Na2O results are not conclusive and are statistically disperse. Thermal property knowledge especially thermal conductivity and its application in the building construction field appeared to be very satisfactory for it involves both technological and thermal comfort aspects, which favored in all cases fast, cheap, and precise results. The relation between thermal conductivity and linear thermal dilatation have also shown satisfactory results especially when it comes to the quartz role as a common, determining phase between the two variables. Thermal conductivity studies together with rocky material density can function as an additional tool for choosing materials when considering structural calculation aspects and thermal comfort, for in the dimension stone case there is a small density variation in relation to a thermal conductivity considerable variation

Depreciação no serviço público: reconhecimento e evidenciação nas demonstrações contábeis dos estados e municípios brasileiros

Public institutions, as well as other entities, if use of various assets for development of its activities. These assets are tools that help with the generation of benefit present and future. For the assets that compound the Property, Plant and Equipament, this loss of generation of future benefits is called Depreciation and must be recognized as an expense in the period in which it occurs. This way, be considered as an expense, the depreciation has negative influence on the composition of the entity’s income, as this is the result of the confrontation between revenue and expenditure incurred in the same period. The Brazilian legislation regulates it is necessary to recognize and disclosure in the financial statements, all of the situations that interfere with the composition of economic and financial income of the public institution. The main objective of this work was to verify if the states and cities recognize and disclosure the depreciation on their Statements of Financial Position. The data were extracted from datas of the Brazilian public administration’s entities.. The sample analyzed is 100% of the States (including the Federal District) and 91% of the Brazilian cities. The research found the historical evolution of the expenditure with depreciation, evidenced in the balance sheets of the Brazilian cities, in the last 10 years, in the period 1999 to 2008. The results indicate that 10 Brazilian states (37 %) did not show the depreciation of fixed assets in the Statements of Financial Position of the year 2008. The situation is even more worrying in relation to cities, because 4,971 (98.4 %) of 5,050 municipalities not evidenced the depreciation. The evidence found in this study indicate that public entities do not recognize the expense with depreciation, which may indicate that the economic income and financial position presented in the financial statements of these public entities does not accurately reflect the actual situation of institutional performance.