ESS - AUD - Comunicações em eventos científicos
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Browsing ESS - AUD - Comunicações em eventos científicos by Author "Areias, Bruno"
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- Biomechanical study of the vestibular system of the inner ear using a numerical methodPublication . Santos, Carla F.; Belinha, Jorge; Gentil, Fernanda; Parente, Marco; Areias, Bruno; Jorge, Renato NatalThe inner ear has two main parts, the cochlea, dedicated to hearing, and the vestibular system, dedicated to balance. Dizziness and vertigo are the main symptoms related to vestibular disorders, which commonly affects older people. In order to eliminate these symptoms a vestibular rehabilitation is performed; this consists in a range of movements of the head, known as maneuvers, performed by a clinical professional. This procedure does not always work as expected. The aim of this work is to contribute to a better understanding on how the vestibular system works. This knowledge will help in the development of new techniques that will facilitate a more efficient rehabilitation. In order to achieve that goal, a three-dimensional numerical model of the vestibular system, containing the fluids which promote the body balance, was constructed. The vestibular components will be discretized using the finite element method and the fluid flow will be analyzed using the Smoothed Particle Hydrodynamics The results obtained with the numerical model of the semicircular canal built to study the rehabilitation process are presented and compared with other authors. The solution achieved is similar with literature.
- Efeitos biomecânicos da evolução do colesteatoma sobre a corda do tímpanoPublication . Gentil, Fernanda; Mendonça, Leonor; Santos, Carla; Parente, Marco; Areias, Bruno; Natal, RenatoA otite média crónica pode levar ao aparecimento de um tumor benigno do ouvido, chamado colesteatoma. Esta patologia, se não for devidamente tratada, pode ter graves consequências. Uma delas pode resultar em paralisia facial se comprimir um ramo do nervo facial que atravessa o ouvido médio. Neste trabalho foram avaliadas as tensões exercidas do tumor contra o nervo. A maior tensão foi obtida na área de contacto entre o nervo e a bigorna.
- How the computational methods can contribute to better knowledge of the earPublication . Gentil, Fernanda; Parente, Marco; Santos, Carla; Areias, Bruno; Belinha, Jorge; Jorge, Renato NatalThe biomechanical behavior of the human ear can be studied using mathematical approaches, such as the finite element method. This methodology allows to perform simulations to evaluate the influence of sound transmission through all way of the ear, since the sound is selected by the outer ear to the inner ear. The finite element method is currently the preferred method for the numerical solution of partial differential equations, and it is used in several fields of the biological sciences. Due to its large applicability and efficiency, there are several works where this methodology is applied in different specialties, to analyze loads, strains or displacements, as in the case of the biomechanical study of the ear. From CT images, three-dimensional accurate computational models are created. The technique employs a set of calculations of numerical analysis for solutions of kinematic (displacements and rotations) and mechanical aspects (strength, stress, pressure, deformation). The use of these computer models enables the motion analysis of all ossicular chain points at any moment.
- A numerical study of the human earPublication . Areias, Bruno; Parente, Marco; Gentil, Fernanda; Santos, Carla; Jorge, Renato NatalHearing is one of the five senses in humans and one of the most important for their social life. The human ear is a complex organ which allows to understand and interpret sound waves for a band of frequencies between 16 Hz and 20 kHz and intensities ranging from 0 to 130 dB. The numerical model used in this work was built based on the geometrical information obtained from The visible ear project. A cryosectioning procedure was applied to the temporal bone of an 85 years old woman, without hearing pathologies, to obtain the anatomical data. Afterwards, the different tissues were hand-segmented and a 3D model was constructed. The finite element method was employed to obtain the umbo and stapes footplate displacements. A study of the external auditory meatus was carried out in order to study its influence on the human hearing. The model without the external auditory meatus was validated by comparing the displacements obtained for the umbo and stapes footplate, with other data in the literature. Subsequently, the external auditory meatus was introduced in the numerical model. The air was modelled with acoustic elements available in the Abaqus Standard software. In total, the model was discretized with 255 343 nodes and 1 345 379 elements. The results obtained showed the important role that the external auditory meatus has in amplifying the sound at higher frequencies. In the frequency band between 100 Hz and 10 kHz, two resonant frequencies were found. There was a significant gain in sound pressure near the tympanic membrane for the frequencies of 3 and 8 kHz. A phase shift of 180◦ near these frequencies, accompanied by a rapid increase in the displacement amplitude showed the presence of such resonances. The study can now proceed into the middle and inner ear in order to study the different types of pathologies and prostheses. The acoustic transmission in the cochlea remains understudied in this area.
- The free vibration computational analysis of the cupula in the inner earPublication . Santos, Carla F.; Belinha, Jorge; Gentil, Fernanda; Parente, Marco; Areias, Bruno; Jorge, Renato NatalThe three semicircular canals, arranged in three orthogonal planes, are the main components of the inner ear with the balance function. They are sensitive to angular acceleration [1,2]. Each canal is composed of a circular path of fluid continuity, interrupted at the cupula, where the sensory epithelium is placed - known as hair cells, which is the focus of this work. The hair cells exhibit constant discharge of neurotransmitters that are modified by the direction of cupula deflection. One of the causes of vestibular disorders is the abnormal concentration of otoconia particles in the vicinity of the cupula. Thus, the accurate determination of the natural frequency (first vibration mode) of the cupula will allow to stimulate externally the cupula. Theoretically, the resonance phenomena will disperse the otoconia particles, reducing the vertigo symptoms. In order to understand the dynamic response of the cupula, first it is necessary to obtain its free vibration modes. Thus, a 2D and 3D geometrical model of the cupula was constructed. Then, a free vibration analysis was performed using two distinct numerical techniques, such as the finite element method (FEM) and a radial point interpolation meshless method (RPIM). Meshless methods are advanced discretization techniques that allow to discretize the problem domain using only a cloud of points, allowing them to discretize geometrical models directly from medical images. The results obtained with the 2D and 3D geometrical model show that RPIM is capable to deliver results very similar with the FEM. However, the RPIM solution is smoother. On the other hand, the FEM computational cost is lower than the RPIM.