Modeling of Flowing Film Concentrators - Part 1. Water Split Behaviour

A large number of mineral processing equipment employs the basic principles of gravity concentration in a flowing fluid of a few millimetres thick in small open channels where the particles are distributed along the flow height based on their physical properties and the fluid flow characteristics. Fluid flow behaviour and slurry transportation characteristics in open channels have been the research topic for many years in many engineering disciplines. However, the open channels used in the mineral processing industries are different in terms of the size of the channel and the flow velocity used. Understanding of water split behaviour is, therefore, essential in modeling flowing film concentrators. In this paper, an attempt has been made to model the water split behaviour in an inclined open rectangular channel, resembling the actual size and the flow velocity used by the mineral processing industries, based on the Prandtl's mixing length approach. (c) 2006 Elsevier B.V. All rights reserved.

Aplicação da democracia deliberativa como mecanismo de efetivação do direito fundamental a uma administração pública proba

This study aims to analyze citizen participation in state policy decisions, as an essential element of legitimacy in the branches of government, especially in the sphere of the Executive, in the context of deliberative democracy. But, this study still has the desideratum to understand the citizen's role in public life, especially in the sphere of the Executive Branch, in order to effect the Fundamental Right to Public Administration proba, efficient and honest. Thus, to achieve this mister, the proposal is to expose the pesamento the classic contractualist, Thomas Hobbes, John Locke and Rousseau about the legitimacy of governments, through the statutes, and the question of the general will and majority rule as well how to present the comments of Thomas Jefferson on popular sovereignty and dialogical citizen participation in matters of local interest. After, it will be studied the theories of Fundamental Rights in order to demonstrate the need for the Civil Service should be veiled in a more specific custody rights, given the deep crisis in the Public Administrative practice due, especially, corruption. On the other side, the fundamentality of management also covers the aspect of the development of cities, which decisively affects the development of man, which, to join a deliberative governance program needs to be politicized, adopting full participation, dialogue, as duty citizen. Furthermore, taking as most heart, will be presented the doctrine of Jürgen Habermas, whose Discourse Theory element is to be followed for the implementation of a This study aims to analyze citizen participation in state policy decisions, as an essential element of legitimacy in the branches of the government, especially in the sphere of the Executive, in the context of deliberative democracy. But, this study also has the desideratum to understand the citizen's role in public life, especially in the sphere of the Executive Branch, in order to actualize the Fundamental Right to a just, efficient and honest Public Administration. Thus, to achieve this necessity, the proposal is to expose the thought of the classic contractualist thinkers, Thomas Hobbes, John Locke and Rousseau about the legitimacy of governments, through the statutes, and the question of the general will and majority rule as well as how to present the comments of Thomas Jefferson on popular sovereignty and dialogical citizen participation in matters of local interest. Later on, the theories of Fundamental Rights will be studied in order to demonstrate that the need for the Civil Service should be veiled in a more specific right custody, given the deep crisis in the Public Administrative practice due to, especially, the corruption. On the other hand, the fundamentality of management also covers the aspect of the development of cities, which decisively affects the development of man, who, to join a deliberative governance program, needs to be politicized, adopting full participation and dialogue as a citizen responsibility. Furthermore, taking as the major heart, it will be presented the doctrine of Jürgen Habermas whose Discourse Theory element is to be followed for the implementation of a broad deliberative and emancipatory democracy, with effective citizen participation. It will also be considered the Condorcet Constitution Project as a comparative link in the linking of the public deliberative will, and the Central Power, in the face of the Theory of “Sluice” Habermas. The proposal, based on communicative action, must allow a continuous flux and influx process of social interests towards the exercise of administrative power. The dialogical deal, brought to the center of the decisions, will allow discussions in the public scope, and may contribute to the legitimacy of government actions, inasmuch as it creates the feeling of politicization demanded by the man in a democratic state.

Vazão em soleiras controladas ou não por comportas

Os controladores de caudal, normalmente implementados em sistemas Supervisory control and data acquisition (SCADA), apresentam uma grande relevância no controlo automático de canais de adução. Para garantir que os controladores de caudal sejam fiáveis em todo o seu domínio de funcionamento (em situações de escoamento com ressalto livre ou submerso e de transição entre escoamentos com ressalto livre e ressalto submerso) foram comparados os resultados dos ensaios experimentais com diferentes métodos de cálculo da vazão em comportas e/ou sobre soleiras. O programa de ensaios foi realizado nos canais laboratorial e experimental da Universidade de Évora. Foram realizados ensaios em comportas planas verticais e em soleiras do tipo Waterways Experiment Station (WES) controladas ou não por comportas planas verticais. Em ambos os casos, foram contempladas as situações de escoamento com ressalto livre e submerso. Os resultados obtidos mostram que: a) para as comportas, o método Rajaratnam e Subramanya (1967a) conduz a bons resultados com um erro percentual médio absoluto MAPE < 1% para o escoamento com ressalto livre e MAPE < 4% para o submerso; a transição entre escoamentos foi identificada corretamente por este método; b) para as soleiras, obtiveram-se bons resultados para o escoamento com ressalto livre para o método USACE (1987), com MAPE < 2%, e para o submerso através do método Alves e Martins (2011), com MAPE < 5%; a transição entre escoamentos pode ser considerada adequada de acordo com a curva experimental de Grace (1963); c) para soleiras controladas por comporta, conseguiram-se bons resultados para o escoamento com ressalto livre recorrendo à equação dos orifícios de pequenas dimensões, com MAPE < 1, 5%, e para o submerso com a equação dos orifícios totalmente submersos com MAPE < 1, 6%; em ambos os casos foi necessária calibração do coeficiente de vazão; a transição entre escoamentos foi adequada pelo método de Grace (1963). Com base nos resultados obtidos, foi possível definir um algoritmo de vazão generalizado para comportas e/ou soleiras que permite a determinação da vazão para as situações de escoamento com ressalto livre e submerso incluindo a transição entre escoamentos; ABSTRACT: Flow controllers, usually implemented in Supervisory Control and Data Acquisition (SCADA) systems, are very important in the automatic control of irrigation canal systems. To ensure that flow controllers are reliable for the entire operating range (free or submerged flow and flow transitions) the experimental results were compared with different methods of flow measurement for gates and/or weirs. The test program was conducted in the laboratory flume and in the automatic canal of the University of ´Evora. Tests were carried in sluice gates and in broad-crested weirs controlled or not by sluice gate. In both cases free and submerged flow conditions were analyzed. The results show that: a) for the sluice gates, the method of Rajaratnam e Subramanya (1967a) leads to good results with a mean absolute percentage error (MAPE) < 1% for free flow and MAPE < 4% for submerged flow. The transition between flows is correctly identified by this method; b) for the uncontrolled weir, good results were obtained for free flow with the method USACE (1987) with MAPE < 2%, and for submerged flow by the method Alves e Martins (2011) with MAPE < 5%. The transition between flows can be accurately defined by the experimental curve of Grace (1963); c) for the controlled weir, good results were achieved for the free flow with the small orifice equation with MAPE < 1.5% and for submerged flow with the submerged orifice equation with MAPE < 1.6%; in both cases the calibration of the discharge coefficient is needed. The transition between flows can be accomplished through Grace (1963) method. Based on the obtained results, it was possible to define a generalized flow algorithm for gates and/or weirs that allows flow determination for free and submerged flow conditions including the transition between flows.