Staghorn Calculi: an Unusual and Serious Clinical Case

Introdução: Este artigo tem como objectivo apresentar um caso clínico de litíase coraliforme que exemplifica a gravidade resultante desta patologia. Caso Clínico: Caso clínico de uma doente do sexo feminino, 43 anos, sem antecedentes pessoais de relevo, que recorreu ao Serviço de Urgência por prostração, astenia e anorexia. Foi-lhe diagnosticada insuficiência renal grave, litíase coraliforme bilateral e hidronefrose com conteúdo não puro no excretor. A doente foi submetida a colocação bilateral de nefrostomias e uma semana depois, num contexto de pionefrose à esquerda e sépsis, foi submetida a nefrectomia total à esquerda. Ficou a realizar hemodiálise em ambulatório. Posteriormente concluiu-se perda irreversível da função renal, com consequente nefrectomia direita. Discussão: Este caso constitui um exemplo da gravidade resultante da litíase coraliforme. Mesmo sem manifestação clínica prévia, pode causar insuficiência renal avançada, com infecção urinária grave e sépsis que colocam a vida em risco

Fractional order modeling and control of a smart beam

Smart beams are one of the most frequently used means of studying vibrations in airplane wings. Their mathematical models have been so far solely based on classical approaches that ultimately involve integer order transfer functions. In this paper, a different approach towards modeling such smart beams is considered, an approach that is based on fractional calculus. In this way, a fractional order model of the smart beam is obtained, which is able to better capture the dynamics of the system. Based on this novel fractional order model, a fractional order PD mu controller is then tuned according to a set of three design constraints. This design leads to a closed loop system that exhibits a much smaller resonant peak compared to the uncompensated smart beam system. Experimental results are provided, considering both passive and active control responses of the smart beam, showing that a significant improvement of the closed loop behavior is obtained using the designed controller

Mathematical modelling with experimental validation of viscoelastic properties in non-Newtonian fluids

The paper proposes a mathematical framework for the use of fractional-order impedance models to capture fluid mechanics properties in frequency-domain experimental datasets. An overview of non-Newtonian (NN) fluid classification is given as to motivate the use of fractional-order models as natural solutions to capture fluid dynamics. Four classes of fluids are tested: oil, sugar, detergent and liquid soap. Three nonlinear identification methods are used to fit the model: nonlinear least squares, genetic algorithms and particle swarm optimization. The model identification results obtained from experimental datasets suggest the proposed model is useful to characterize various degree of viscoelasticity in NN fluids. The advantage of the proposed model is that it is compact, while capturing the fluid properties and can be identified in real-time for further use in prediction or control applications. This article is part of the theme issue 'Advanced materials modelling via fractional calculus: challenges and perspectives'