Encontrados 142 documentos, a visualizar página 1 de 15
Analysis of temperature time-series: embedding dynamics into the MDS method
Lopes, António M.; Machado, J. A. TenreiroGlobal warming and the associated climate changes are being the subject of intensive research due to their major impact on social, economic and health aspects of the human life. Surface temperature time-series characterise Earth as a slow dynamics spatiotemporal system, evidencing long memory behaviour, typical of fractional order systems. Such phenomena are difficult to model and analyse, demanding for alterna...
Mineral and Bone Disease (MBD) on a Kidney Transplant Patient
Birne, R; Adragão, T; Ferreira, A; Dickson, J; Silva, R; Casqueiro, A; Oliveira, R; Martins, AR; Torres, J; Matias, P; Branco, P; Jorge, C; Weigert, AA 50-year-old post-menopausal recipient of a kidney allograft with bone pain, osteoporosis, persistent hypercalcaemia and elevated parathormone (PTH) levels, despite a satisfactory graft function, was treated with bisphosphonates and cinacalcet starting, respectively, 5 and 6 months after renal transplantation (RT). Sixteen months after treatment, there was improvement of bone mineral density (BMD) measured by ...
Fractional dynamics and MDS visualization of earthquake phenomena
Lopes, António M.; Machado, J. A. Tenreiro; Pinto, Carla M. A.; Galhano, AlexandraThis paper analyses earthquake data in the perspective of dynamical systems and fractional calculus (FC). This new standpoint uses Multidimensional Scaling (MDS) as a powerful clustering and visualization tool. FC extends the concepts of integrals and derivatives to non-integer and complex orders. MDS is a technique that produces spatial or geometric representations of complex objects, such that those objects t...
Root-locus practical sketching rules for fractional-order system
Lopes, António M.; Machado, J. A. TenreiroFor integer-order systems, there are well-known practical rules for RL sketching. Nevertheless, these rules cannot be directly applied to fractional-order (FO) systems. Besides, the existing literature on this topic is scarce and exclusively focused on commensurate systems, usually expressed as the ratio of two noninteger polynomials. The practical rules derived for those do not apply to other symbolic expressi...
On a generalized laguerre operational matrix of fractional integration
Bhrawy, A. H.; Baleanu, Dumitru; Assas, L. M.; Machado, J. A. TenreiroA new operationalmatrix of fractional integration of arbitrary order for generalized Laguerre polynomials is derived.The fractional integration is described in the Riemann-Liouville sense.This operational matrix is applied together with generalized Laguerre tau method for solving general linearmultitermfractional differential equations (FDEs).Themethod has the advantage of obtaining the solution in terms of the...
Dynamic analysis of earthquake phenomena by means of pseudo phase plane
Lopes, António M.; Machado, J. A. TenreiroThis paper analyses earthquake data in the perspective of dynamical systems and its Pseudo Phase Plane representation. The seismic data is collected from the Bulletin of the International Seismological Centre. The geological events are characterised by their magnitude and geographical location and described by means of time series of sequences of Dirac impulses. Fifty groups of data series are considered, accor...
Analysis of the respiratory dynamics during normal breathing by means of pseudo...
Ionescu, Clara M.; Machado, J. A. Tenreiro; Keyser, Robin DeThis paper reports on the analysis of tidal breathing patterns measured during noninvasive forced oscillation lung function tests in six individual groups. The three adult groups were healthy, with prediagnosed chronic obstructive pulmonary disease, and with prediagnosed kyphoscoliosis, respectively. The three children groups were healthy, with prediagnosed asthma, and with prediagnosed cystic fibrosis, respect...
Fractional order models of leaves
Lopes, António M.; Machado, J. A. TenreiroLeaves are mainly responsible for food production in vascular plants. Studying individual leaves can reveal important characteristics of the whole plant, namely its health condition, nutrient status, the presence of viruses and rooting ability. One technique that has been used for this purpose is Electrical Impedance Spectroscopy, which consists of determining the electrical impedance spectrum of the leaf. In ...
Optimal location of the workpiece in a PKM-based machining robotic cell
Pires, E. J. Solteiro; Lopes, António M.; Machado, J. A. Tenreiro; Oliveira, P. B. MouraMost machining tasks require high accuracy and are carried out by dedicated machine-tools. On the other hand, traditional robots are flexible and easy to program, but they are rather inaccurate for certain tasks. Parallel kinematic robots could combine the accuracy and flexibility that are usually needed in machining operations. Achieving this goal requires proper design of the parallel robot. In this chapter, ...
Innovative architectural and structural design to preserve historical centers
Félix, D.; Feio, A.; Branco, Jorge M.; Machado, José S.Historical centers are important elements of our cities, representing their history and evolution. Many cities are facing the problem of having several vacant and degraded buildings needing intervention to avoid collapses. Also several examples of unforeseen events, like earthquakes, tsunamis, floods, etc., have severely damaged important historical cities. Beyond the risk of losing built heritage, these buildi...
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