The labyrinth seal is a non-contact annular type sealing device used to reduce the internal leakage of the working fluid which is caused by the pressure difference between each stage in a turbomachine. Reducing the leakage mass flow rate of the working fluid through the labyrinth seal is desirable because it improves the efficiency of the turbomachine. The carry-over coefficient, based on the divergence angle of the jet, changed with flow parameters with fixed seal geometry while earlier models expressed the carry-over coefficient solely as a function of seal geometry. For both compressible and incompressible flows, the Reynolds number based on clearance was the only flow parameter which could influence the carry-over coefficient. In the case of incompressible flow based on the simulations for various seal geometries and operating conditions, for a given Reynolds number, the carry-over coefficient strongly depended on radial clearance to tooth width ratio. Moreover, in general, the lower the Reynolds number, the larger is the divergence angle of the jet and this results in a smaller carry-over coefficient at lower Reynolds numbers. However, during transition from laminar to turbulent, the carry-over coefficient reduced initially and once the Reynolds number attained a critical value, the carry-over coefficient increased again. In the case of compressible flow, the carry-over coefficient had been slightly increased if radial clearance to tooth width ratio and radial clearance to tooth pitch ratio were increased. Further, the carry-over coefficient did not considerably change if only radial clearance to tooth width ratio was decreased. The discharge coefficient for compressible and incompressible flows depended only on the Reynolds number based on clearance. The discharge coefficient of the tooth in a single cavity labyrinth seal was equivalent to that in a multiple tooth labyrinth seal indicating that flow downstream had negligible effect on the discharge coefficient. In particular, for compressible fluid under certain flow and seal geometric conditions, the discharge coefficient did not increase with an increase in the Reynolds number. It was correlated to the pressure ratio, Pr. Moreover, it was also related to the fact that the flow of the fluid through the constriction became compressible and the flow eventually became choked. At low pressure ratios (less than 0.7), Saikishan’s incompressible model deviated from CFD simulation results. Hence, the effects of compressibility became significant and both the carry-over coefficient compressibility factor and the discharge coefficient compressibility factor needed to be considered and included into the leakage model. The carry-over coefficient compressibility factor, phi, had two linear relationships with positive and negative slopes regarding the pressure ratios. This result was not associated with the seal geometry because the seal geometry ratios for each instance were located within the nearly same ranges. Further, the phi-Pr relationship was independent of the number of teeth regardless of single and multiple cavity labyrinth seals. The discharge coefficient compressibility factor, psi, was a linear relationship with pressure ratios across the tooth as Saikishan predicted. However, in certain flow and seal geometric conditions, Saikishan’s model needed to be modified for the deviation appearing when the pressure ratios were decreased. Hence, a modified psi-Pr relationship including Saikishan’s model was presented in order to compensate for the deviation between the simulations and his model.

Le aflatossine sono potenti sostanze cancerogene presenti in natura. L'aflatossina b1 viene poco degradata nel rumine ed è escreta nel latte come aflatossina M1 con un carry over del 1-3%. Nel presente lavoro è stata studiata l'apparizione delle aflatossine nel sangue conseguente all'ingestione orale di un bolo contaminato per verificare come queste tossine sono assorbite nel tratto digestivo delle vacche da latte. La comparsa nel plasma e nel latte attraverso una mucosa tipicamente non di assorbimento per determinare il possibile meccanismo che regola l'assorbimento delle aflatossine è stato un ulteriore oggetto di studio. Un'altra prova è stata effettuata con vacche da latte per studiare il carry-over dell'aflatossina B1 nel latte in relazione al livello produttivo e alle cellule somatiche, come indicatore di processi infiammatori nella mammella. La capacità sequestrante di diversi tipi di adsorbenti è stata comparata in prove in vitro condotte in differenti condizioni sperimentali. Anche il comportamento del complesso aflattosina-adsorbente nel tratto digestivo di vacche in lattazione è stato studiato in vivo per mezzo della misurazione della presenza di aflatossina M1 nel latte. Una prova in vivo è stata effettuata per verificare l'effetto che la pellettatura o la semplice miscelazione di adsorbenti nei mangimi può avere nel migliorare l'efficienza di sequestro. / Aflatoxins are the most potent natural carcinogenic compound present in nature. Aflatoxin B1 is poorly degraded in the rumen and is excreted in milk as aflatoxin M1 with a carry-over rate of 1-3%. The present work investigated rate and schedule of aflatoxins plasma appearance following an oral contaminated bolus to verify how these toxins are absorbed in the gastro-intestinal tract of dairy cows. Aflatoxins plasma and milk appearances were also investigated using a non-absorbing mucosa to understand the possible aflatoxins absorption mechanism through mucous membranes. A trial was carried out in lactating dairy cows to study the carry over of ingested aflatoxin B1 in milk as aflatoxin M1 in relation to milk yield and somatic cells count, the latter as indicator of udder inflammatory processes. sequestering capacity of different kinds of mycotoxins sequestering agents were compared in vitro trial carried out at different experimental conditions. The behaviour of the aflatoxins-adsorbents complexes through digestive tract of lactating dairy cows were also investigated in vivo by measuring appearance of aflatoxin M1 into milk. An in vivo trial was conducted to verify if effect of pelletizing or simply mixing processes is useful to improve mycotoxins sequestering agents efficacy in dairy cow nutrition.

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Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2018-06-11T19:53:05Z No. of bitstreams: 2 Dissertação - Cássia Cardoso de Carvalho Vasconcelos - 2018.pdf: 1013495 bytes, checksum: 354b152bc79c9682f78ed5fbe130c19e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Rejected by Luciana Ferreira (lucgeral@gmail.com), reason: Olhei nas dissertações que já foram inseridas para checar a citação, veja como deve ser: Ex.: Dissertação (Mestrado em Administração Pública em Rede Nacional) - on 2018-06-12T12:17:16Z (GMT) / Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2018-06-12T16:49:51Z No. of bitstreams: 2 Dissertação - Cássia Cardoso de Carvalho Vasconcelos - 2018.pdf: 1013495 bytes, checksum: 354b152bc79c9682f78ed5fbe130c19e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-06-13T10:41:33Z (GMT) No. of bitstreams: 2 Dissertação - Cássia Cardoso de Carvalho Vasconcelos - 2018.pdf: 1013495 bytes, checksum: 354b152bc79c9682f78ed5fbe130c19e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-06-13T10:41:33Z (GMT). No. of bitstreams: 2 Dissertação - Cássia Cardoso de Carvalho Vasconcelos - 2018.pdf: 1013495 bytes, checksum: 354b152bc79c9682f78ed5fbe130c19e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-06-08 / The object of study of this research is expenses classified as carryovers, which are part of the public budget, and they are a challenge for public managers. The objective of the research is to propose a control instrument applicable to the budgetary and financial execution of an IFES, considering the legislation applicable to the public budget, that assists the manager in controlling and reducing the effects of expenses classified as carryovers. Descriptive analysis and application of Pearson's correlation index were carried out on data taken from the Federal Government's Portal, referring to the five universities in the Center-West region between 2008 and 2016. It is concluded that: carryovers are present in all universities evaluated; on average, more than a quarter of the budget started is not finalized in the same year; unprocessed leftovers account for more than 90% of the total unpaid debts of universities. Furthermore, it is found that: there is a moderate negative correlation to budget execution and unbundling of UNB; there is a moderate positive correlation between the remainders to be paid and the financial execution of the budget in the UFGD and the UNB, and negative correlation in the UFG. The intervention proposal has two stages: the first one is the collection of information on the budgetary and financial situation of IFES, through a control sheet, and the second step is the application of the GUT matrix in the budget balances of the carryovers, to prioritize the closure of such expenses. / O objeto desta pesquisa são as despesas classificadas como restos a pagar, que fazem parte da execução do orçamento público, e se apresentam como um desafio para os gestores públicos. O objetivo da pesquisa é propor um instrumento de controle aplicável à execução orçamentária e financeira de uma IFES, considerando a legislação aplicável ao orçamento público, que auxilie o gestor no controle e na redução dos efeitos das despesas classificadas como restos a pagar. Por meio da análise descritiva e aplicação do índice de correlação de Pearson de dados retirados do Portal Siga Brasil referentes às cinco universidades da região Centro-Oeste, entre os anos de 2008 e 2016, conclui-se que: os restos a pagar estão presentes em todas as universidades avaliadas; em média, mais de um quarto do orçamento iniciado não é finalizado no mesmo exercício; os restos a pagar não processados representam, em média, mais de 90% dos restos a pagar total das universidades, e constatou-se que: há correlação moderada negativa em relação à execução orçamentária e inscrição de restos a pagar na UNB; há correlação moderada positiva entre os restos a pagar e a execução financeira do orçamento na UFGD e na UNB, e correlação negativa na UFG. Apresenta-se a proposta de intervenção por meio de duas etapas: a primeira é o levantamento das informações a respeito da situação orçamentária e financeira da IFES, através de uma planilha de controle, e a segunda etapa é a aplicação da matriz GUT nos saldos orçamentários dos restos a pagar, para priorização de encerramento de tais despesas.