Multiscale modeling of circular and elliptical particles in laminar shear flow

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Finite element cochlea box model – Mechanical and electrical analysis of the cochlea

© 2015 AIP Publishing LLC. The primary role of the cochlea is to transform external sound stimuli into mechanical vibrations and then to neural impulses which are sent to the brain. A simplified cochlea box model was developed using the finite element method. Firstly, a mechanical model of the cochlea was analyzed. The box model consists of the basilar membrane and two fluid chambers-the scala vestibuli and scala tympani. The third chamber, the scala media, was neglected in the mechanical analysis. The best agreement with currently available analytical and experimental results was obtained when behavior of the fluid in the chambers was described using the wave acoustic equation and behavior of the basilar membrane was modeled with Newtonian dynamics. The obtained results show good frequency mapping. The second approach was to use an active model of the cochlea in which the Organ of Corti was included. The operation of the Organ of Corti involves the generation of current, caused by mechanical vibration. This current in turn causes a force applied to the basilar membrane, creating in this way an active feedback mechanism. A state space representation of the electro-mechanical model from existing literature was implemented and a first comparison with the finite element method is presented

Finite element cochlea box model-Mechanical and electrical analysis of the cochlea

© 2015 AIP Publishing LLC. The primary role of the cochlea is to transform external sound stimuli into mechanical vibrations and then to neural impulses which are sent to the brain. A simplified cochlea box model was developed using the finite element method. Firstly, a mechanical model of the cochlea was analyzed. The box model consists of the basilar membrane and two fluid chambers-the scala vestibuli and scala tympani. The third chamber, the scala media, was neglected in the mechanical analysis. The best agreement with currently available analytical and experimental results was obtained when behavior of the fluid in the chambers was described using the wave acoustic equation and behavior of the basilar membrane was modeled with Newtonian dynamics. The obtained results show good frequency mapping. The second approach was to use an active model of the cochlea in which the Organ of Corti was included. The operation of the Organ of Corti involves the generation of current, caused by mechanical vibration. This current in turn causes a force applied to the basilar membrane, creating in this way an active feedback mechanism. A state space representation of the electro-mechanical model from existing literature was implemented and a first comparison with the finite element method is presented

Vibrational analysis of the beta system of (BO)-B-10-O-18

Ten bands of the system (B(2)Sigma(+)- X(2)Sigma(+)) of the (BO)-B-10-O-18 molecule have been observed for the first time. The spectrum was obtained by emission spectroscopy from a low-pressure arc, at medium dispersion, and vibrationally analyzed using isotope shift measurements. Vibrational analysis gave the constants omega(e) and omega(e)x(e) for both electronic states involved in the transitions

A computational study of trajectories of micro- and nano-particles with different shapes in flow through small channels

Transport of small particles, of micrometer and sub-micrometer size, by fluid occurs in many technological and biological systems. The channels through which the fluid flows are often with cross-sectional dimensions on the order of several to tens of micrometers. The aim of this study was to investigate effects of shape of micro- and nano-particles on particle trajectories when particles are transported within small channels as blood vessels. Efficiency of therapeutics by particles as the drug carriers is significantly dependent on particle trajectories. It is desirable to have particle trajectories approaching the vessel walls in order to increase therapeutic efficacy. We studied motion of particles in channels (pipes) for two physical conditions: Poiseuille flow, which is characteristic in pipe flow, and shear flow. Shear flow conditions are analyzed since the character of fluid flow near the wall in these systems can be approximated as shear, with a linear change of velocity with the distance from the wall. We here investigated trajectories of particles of different shapes in 2D flow using the finite element (FE) method, with a strong coupling approach for solid-fluid interaction and a remeshing procedure. The results give insight into the characteristics of the particle motion, e.g. trajectories and rotations, under various flow conditions in micron size channels, including flow in the presence of moving deformable discs. We demonstrate that the particle trajectories are essentially parallel to the wall for various conditions and that particle size and shape do not considerably alter the parallel nature of the trajectories

Finite element coiled cochlea model

© 2015 AIP Publishing LLC. Cochlea is important part of the hearing system, and thanks to special structure converts external sound waves into neural impulses which go to the brain. Shape of the cochlea is like snail, so geometry of the cochlea model is complex. The simplified cochlea coiled model was developed using finite element method inside SIFEM FP7 project. Software application is created on the way that user can prescribe set of the parameters for spiral cochlea, as well as material properties and boundary conditions to the model. Several mathematical models were tested. The acoustic wave equation for describing fluid in the cochlea chambers-scala vestibuli and scala timpani, and Newtonian dynamics for describing vibrations of the basilar membrane are used. The mechanical behavior of the coiled cochlea was analyzed and the third chamber, scala media, was not modeled because it does not have a significant impact on the mechanical vibrations of the basilar membrane. The obtained results are in good agreement with experimental measurements. Future work is needed for more realistic geometry model. Coiled model of the cochlea was created and results are compared with initial simplified coiled model of the cochlea

Modeling of radial well lateral screens using 1D finite elements

A water supply system including radial wells (RWs) is usually large, extending several tens of kilometers horizontally and is dozens of meters deep. An RW is a vertical shaft with lateral screens, which radially penetrate the soil. A large and complex 3D finite element (FE) mesh also needs to include laterals with cross-sectional dimensions measured in centimeters. An adequate representation of lateral screens by line elements, with nodes coinciding with the 3D FE mesh nodes, is desirable in order to simplify modeling, render the computation efficient, and present the results in an easily readable form. Line elements are introduced for the lateral screens and accuracy of the results is analyzed. It was found that the domain size of an RW (or laterals) has a more pronounced effect on accuracy than mesh density. The authors' conclusion is that the concept of 1D RW lateral screens representation is adequate for practical purposes. © IWA Publishing 2013

Numerical simulation of human hearing system

© 2018 Isailovic et al. Hearing impairment is a problem faced by many people, mostly the elderly population but occurs even in newborns. Experimental tests performed on patients give information of the level of hearing impairment and the place where the problem is located. In order to understand process of hearing and hearing impairments it would be very useful to have a look inside, but it is not possible with any experimental equipment. However, it is possible to make a virtual look inside human auditory system by development of numerical model. Using data obtained by experimental research it is possible to make sufficiently detailed model and use it to gain new knowledge that can help in understanding of hearing process and problems with hearing. In this paper one such model will be presented. The model contains mechanical and fluid elements of the middle and inner ear

Mechanical and electro-mechanical box cochlea model

The cochlea is the most important part of the hearing system, due to the fact that it receives sound in the form of vibrations and converts these vibrations into nerve impulses in the organ of Corti that sends information about sounds to the brain. Functioning of the cochlea components and behavior is still not investigated completely because of its complex structure. Human live cochlea is placed in almost inaccessible place. Because of that it is hard to collect experimental measurement. Cochlea works as an electro-mechanical system and it is important to investigate both electrical and mechanical behavior of the cochlea in order to improve treatment of hearing disorders. This study presents a mechanical model of the uncoiled cochlea using full 3D 8-noded finite elements, as well the electro-mechanical 1D state-space model of the cochlea. The results obtained from these two cochlea models show good matching with Greenwood function and properly simulate the behavior of the cochlea