Browsing by Author "Belinha, J."
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- Computational simulation of the vestibular system using a meshless particle methodPublication . Santos, C.F.; Parente, Marco; Belinha, J.; Natal Jorge, R.M.; Gentil, FernandaVestibular rehabilitation is the most used therapy in cases of unbalance diagnosis. The vertigo symptoms are commonly related with inner ear diseases, affecting 20%-30% of the world population (von Brevern & Neuhauser, 2011). Its prevalence is higher in elders. In this work, a three-dimensional model of the semi-circular canal of the vestibular system, containing the fluids that pro-mote body balance, will be used. The Smoothed-Particle Hydrodynamics (SPH) method, a meshless particle method, will be the discrete numerical technique used to simulate the fluid behaviour. In the SPH the discretization is represented by particles with constant mass (G.R. Liu & Liu, 2003). The obtained results allow to understand the behaviour of the vestibular structures during the rehabilitation manoeuvres.
- Cupula response to otoconia debris in the semicircular canalPublication . Santos, Carla F.; Belinha, J.; Gentil, Fernanda; Parente, Marco; Jorge, Renato NatalThe vertigo symptoms are commonly related with inner ear diseases and it affects 20%-30% of the world population, and its prevalence increases with age. In this work, a three-dimensional computational model of the semicircular canal of the vestibular system, containing the fluids which promote the body balance, was used. The smoothed-particle hydrodynamics method was the computational process used to simulate the fluid behaviour, in which the elements are represented by particles and have constant mass. The other vestibular components were discretized using the finite element method. The movement performed to endolymph/cupula interaction analysis was reproduced in the simulation through the acquisition of the displacement field based on image analysis. The results obtained with the frames of the video recorded during the process is the appropriate method to simulate the real moves, due to the analysis of the region of interest located near the inner ear. The data obtained from the video acquisition were the input in the simulation with the semicircular model. The principal stress cupular response allowed to understand the interaction of the vestibular structures during a vertigo episode, and the influence of the otoconia in the cupula displacement. This model is the first step to improve the vestibular rehabilitation and the quality of life of patients suffering from vertigo.
- The free vibrations analysis of the cupula in the inner ear using a natural neighbor meshless methodPublication . Santos, Carla F.; Belinha, J.; Gentil, Fernanda; Parente, Marco; Jorge, Renato NatalThe cupula is a part of the inner ear semi-circular canals that plays an important role in the maintenance of the human balance. In order to understand the dynamic response of the cupula, first it is necessary to obtain its vibration frequencies. A two-dimensional and three-dimensional geometrical model of the cupula was built. Then, a free vibration analysis was performed using two distinct numerical techniques, the finite element method (FEM) and the natural neighbor radial point interpolation method (NNRPIM). Besides the fundamental analysis, other scenarios were studied, aiming to analyze the environment of the cupula (in healthy and pathologic scenarios). The results obtained with the geometrical models show that NNRPIM is capable to deliver results very close with the FEM. Additionally, the NNRPIM formulation possesses a high convergence and acceptable computational costs. This work presents for the first time a computational study on the free vibration analysis of the cupula and shows an alternative numerical technique to calculate with precision the natural frequency of the cupula. The outcomes of this work will allow the development of alternative therapies for cupulolithiasis, which causes severe dizziness.
- Using meshless methods to simulate the free vibrations of the cupula under pathological conditionsPublication . Santos, C.F.; Parente, Marco; Belinha, J.; Natal Jorge, R.M.; Gentil, FernandaEach canal of the vestibular system of the inner ear is composed of a circular path of continuum fluid. Inside each semicircular canal, it is possible to find a cupula, a gelatinous body contain-ing sensory hair cells, and the focus of this work. One of the causes of vestibular disorders is the abnormal concentration of otoconia particles near the cupula. The accurate determination of the natural frequency (first vibration frequency) of the cupula would allow to know which external frequency could be induce to stimulate externally the cupula. Thus, theoretically, the resonance effect would induce physical vibra-tion to the cupula and disperse the otoconia particles, reducing the vertigo symptoms. Hence, in this wok, two-dimensional and three-dimensional geometrical models of the cupula were constructed. Then, a free vibration analysis was performed using three distinct numerical techniques, the Finite Element Method (FEM), and two meshless methods: the Radial Point Interpolation Meshless Method (RPIM) and the Natural Neighbour Radial Point Interpolation Method (NNRPIM).