Browsing by Issue Date, starting with "2008-07"
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- A comparative study between eardrum perforations and myringosclerosisPublication . Gentil, Fernanda; Jorge, R.M. Natal; Ferreira, A.J.M.; Parente, M.P.L.; Martins, P.A.L.S.; Alexandre, Fátima; Almeida, E.Anatomically, the ear is divided into three parts (external, middle, and inner ear). The eardrum divides external from middle ear and can develop some pathology. The majority of the eardrum is composed by pars tensa being the superior area known as pars flaccida. Myringosclerosis (formation of dense connective tissue in the eardrum) is a common sequel of the ventilation tube insertion used for the treatment of the media otitis with effusion. It can affect tympanometric evaluation by decreasing mobility of the eardrum. However, usually, it is not associated with hearing loss.
- Análisis de requisitos software para un weblabPublication . Zubía, J. García; Ipña, D. López de; Alves, Gustavo R.; Fernández, P. OrduñaEl trabajo presenta un análisis detallado de las diferentes tecnologías software que pueden ser utilizadas para implementar el cliente de un laboratorio remoto o WebLab. Dicho análisis viene precedido de un estudio elaborado por diferentes investigadores internacionales del área para establecer cuáles son los requisitos deseables en un WebLab en términos de universalidad y potencia.
- An evolutionary approach to the trajectory planning of redundant robotsPublication . Marcos, Maria da Graça; Tenreiro Machado, J. A.; Azevedo-Perdicoúlis, T. P.Several kinematic techniques for the trajectory optimization of redundant manipulators control the gripper using the pseudoinverse of the Jacobian. Nevertheless, these algorithms lead to a kind of chaotic motion with unpredictable arm configurations. This paper presents a new technique for solving the inverse kinematics problem for redundant manipulators that combines the closed-loop pseudoinverse method with genetic algorithms.
- Fractional modelling of the electrical conduction in nacl electrolytePublication . Jesus, Isabel S.; Tenreiro Machado, J. A.; Barbosa, RamiroThe fractional calculus (FC) constitutes a mathematical tool that presently is being applied in many emerging scientific areas, such as electricity, magnetism, mechanics, fluid dynamics and medicine. This paper describes the use of an electrolytic process for developing fractional order capacitors. The study includes several experiments for measuring the electrical impedance of the devices. The results are analyzed through the frequency response revealing capacitances of fractional order.
- Algorithmic music composition: a surveyPublication . Ferreira, Isabel M.; Tenreiro Machado, J. A.This paper surveys some of the methods used for algorithmic composition and their evolution during the last decades. Algorithmic composition was motivated by the natural need to assist and to develop the process of music creation. Techniques and applications of algorithmic composition are broad spectrum, ranging from methods that produce entire works with no human intervention, up to methods were both composer and computer work closely together in real-time. Common algorithms used for music composition are based in stochastic, deterministic, chaotic and artificial intelligence methods.
- Implementing an electrical fractional potential through a genetic algorithmPublication . Jesus, Isabel S.; Tenreiro Machado, J. A.; Barbosa, RamiroSeveral phenomena present in electrical systems, motivated the development of comprehensive models based on the theory of fractional calculus (FC). Bearing these ideas in mind, in this work, are applied the FC concepts to define, and to evaluate, the electrical potential of fractional order based in a genetic algorithm optimization scheme. Research on the approximation feasibility and convergence is also developed.
- Fractional Derivatives and Their ApplicationsPublication . Tenreiro Machado, J. A.
- Computational intelligence techniques in engineeringPublication . Marques, Viriato M.; Reis, Cecília; Roseiro, Luís; Tenreiro Machado, J. A.This article shows how CI techniques overpass the strict limits of Artificial Intelligence (AI) field and can help solving real problems from distinct engineering areas: Mechanical, Computer Science and Electrical Engineering. An introduction to each of the CI main areas is made and three systems are briefly described. The results are, in each case, very promising
- Evolutionary perspectives in computer musicPublication . Reis, Cecília; Marques, Viriato M.; Tenreiro Machado, J. A.This paper presents a brief overview of music evolution - western and non-western music - from its genesis to serialism and the Darmstadt school. Some mathematical aspects of music are then presented and confronted with music as a form of art. Some questions follow: are these two (very) distinct aspects compatible? Can computers be of real help in automatic composition? Evolutionaty Algorithms (EAs) - Genetic Algorithms (GAs), Genetic Programming (GP), Particle Swarm Optimization (PSO) and Ant Colony Optimization (ACO) - are then introduced and some results of GAs and GPs application to music generation are analysed. Variable fitness functions and PSO application seems a promising way to explore. However, what output should be envisaged? Should we expect that computer music sounds as human music, or should we look for a totally different way to explore and listen? How far can go computer creativity and in what direction?
- On the Fractional PID Control of a Laboratory Servo SystemPublication . Barbosa, Ramiro; Tenreiro Machado, J. A.; Jesus, Isabel S.In this paper are investigated several types of fractional-order PID controllers in the velocity control of a servo system. The fractional controller is more flexible and gives the possibility of adjusting carefully the dynamical properties of a control system. The servo system is controlled by using a real-time digital control system based on MATLAB/Simulink. Results are compared with those obtained from classical PID controllers. Experimental responses are presented and analyzed, showing the effectiveness of the proposed fractional-order algorithms.