Endoscopy

Endoscopy is a fast moving field, and new techniques are continuously emerging. In recent decades, endoscopy has evolved and branched out from a diagnostic modality to enhanced video and computer assisting imaging with impressive interventional capabilities. The modern endoscopy has seen advances not only in types of endoscopes available, but also in types of interventions amenable to the endoscopic approach. To date, there are a lot more developments that are being trialed. Modern endoscopic equipment provides physicians with the benefit of many technical advances. Endoscopy is an effective and safe procedure even in special populations including pediatric patients and renal transplant patients. It serves as the tool for diagnosis and therapeutic interventions of many organs including gastrointestinal tract, head and neck, urinary tract and others

DYNAMIC PROPERTIES OF HUMAN MIDDLE EAR TISSUES

Middle ear tissues, including the tympanic membrane (TM), round window membrane (RWM) and stapedial annular ligament (SAL), play important roles in acoustic transmission function in the middle ear. Changes of mechanical properties of ear tissues caused by diseases may induce the conductive hearing loss. It is critical to measure the mechanical properties of these tissues for understanding the middle ear transfer function and the mechanism of hearing loss. However, there are limited reports about mechanical properties of middle ear tissues in the literature because of the extreme small size and complicated geometry of these tissues. Moreover, most of published studies focused on mechanical properties under the static or quasi-static condition. As the middle ear tissues undergo vibration in the auditory frequency range, the dynamic properties or complex moduli of the tissues may have more realistic value than the static properties. The dynamic properties of middle ear tissues will provide the accurate data for modeling of human ear.In this study, the dynamic properties of human TM, RWM and SAL specimens harvested from cadaver temporal bones were measured in the auditory frequency range. The generalized linear solid model was used to describe the viscoelastic behaviors of these tissues. Two different approaches were used to measure ear tissues. The first approach of using acoustic driving was developed for membrane tissues, such as TM and RWM. Vibration of the membrane specimens in response to acoustic driving load applied to the specimen was measured by laser Doppler vibrometer over the frequency range of 200-8000 Hz. The dynamic experiments were then simulated in finite element models by acoustic-structure coupled analysis in ANSYS. Dynamic properties of the TM and RWM were derived by inverse-problem solving method.The second approach was using dynamic mechanical analyzer based on the frequency-temperature superposition principle. The dynamic tests were conducted for the TM and SAL specimens at the frequencies from 1 Hz to 40 Hz at three different temperatures: 5o, 25o and 37oC. The frequency-temperature superposition principle was applied to expand the test frequency range to a much higher level (at least 3760 Hz). The viscoelastic parameters and the complex moduli in the frequency domain were obtained and the results were comparable to the published data. The potential effects of the experimental condition and specimen dimension measurement on the results were estimated.The methods and results reported in this study contribute to soft tissue biomechanics. The complex moduli of middle ear tissues can be applied into finite element model of human ear to improve the model accuracy

Computer-integrated finite element modeling and simulation of human middle ear.

The work reported in this dissertation is the result of a joint venture of biomedical scientists and engineers for understanding human middle ear mechanics through finite element modeling and analysis. The main objective of the research is to explore the middle ear dynamics by using an accurate finite element model of the human middle ear.The base-line finite element model was employed for three preliminary clinical applications. The results suggest that the base-line finite element model is very useful in the study of the middle ear mechanics, and the design and test of implantable hearing devices.The research started with developing a systematic and accurate geometric modeling method that can be employed to reconstruct the middle ear from the histological sections of a human temporal bone in the Computer-Aided Design (CAD) environment. Using the method, a solid model of human middle ear was constructed which reveals excellent accuracy in geometry.Then a finite element model of the human middle ear was built by using the geometry translated from the CAD model and the published material properties of the middle ear system. The finite element model was finalized as the base-line finite element model by adjusting physical parameters based on the stapes footplate displacements obtained by laser Doppler interferometry measurements. Finally, the accuracy of the base-line finite element model was verified by using four sets of published experimental measurements. These verifications demonstrate that the base-line model constructed using the geometric modeling method developed in this research is adequate in predicting the dynamic behaviors of the middle ear. Therefore, it is appropriate to employ the finite element model to simulate the middle ear frequency response characteristics, which are the main concerns in the middle ear sound transmission study

Psychoacoustic measurements of bone conducted sound

Bone-conduction hearing aids (BCHAs) are a widely used method of treating conductive hearing loss, but the benefit of bilateral implantation is severely limited due to interaural cross-talk. In theory two BCHAs could deliver improved stereo separation using cross-talk cancellation. Sound vibrations from each BCHA would be cancelled at the contralateral cochlea by an out-of-phase signal of the same level from the psilateral BCHA. In order to achieve this the phase and level of sound at each cochlea needs to be known. A method to measure the level and phase required for these cancellation signals was developed and cross-validated with a second technique that combines air- and bone-conducted sound in normal hearing subjects. Levels measured with each method differed by <1 dB between 3-5 kHz. The phase results also corresponded well for the cancelled ear (11° mean difference). The newly developed method using only bone transducers is potentially transferable to a clinical population. To demonstrate cross-talk cancellation tone and speech reception thresholds (TRT and SRT) were investigated with and without unilateral cross-talk cancellation. Band limited noise was emitted from one BT whilst signal +/- cancellation signal was produced by the other. Benefits of cross-talk cancellation under this atypical listening situation were found to be 12.08 and 13.7 dB for TRT and SRT thresholds. In order to estimate the potential benefits of cross-talk cancellation in spatially realistic environments, phase and level elements of impulse responses from a BAHA 4 were convolved with speech. This found that cross-talk cancellation had the potential to lower SRTs in a clinical population by approximately 4.4 dB. Future work will focus on real-time processing and examine using a clinical population

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Estimation of the Stapes-Bone Thickness in Stapedotomy Surgical Procedure Using a Machine-Learning Technique

Stapedotomy is a surgical procedure aiming at the treatment of hearing impairment, where the latter is due to otosclerosis, by drilling a hole through the stapes bone in the inner ear in order to insert a prosthesis. Safety requires knowledge of the non-measurable stapes thickness. The technical goal herein has been the design of high level controls for an intelligent mechatronics drilling tool in order to enable the estimation of stapes thickness from measurable drilling data. The goal has been met by learning a map between drilling features, hence no model of the physical system has been necessary. Learning has been achieved as explained in this paper by a scheme, namely d-s Fuzzy Lattice Neurocomputing (ds-FLN) scheme for classification, within the framework of Fuzzy Lattices. The successful application of the ds-FLN scheme is demonstrated in estimating the thickness of a stapes bone &quot;on-line&quot; using drilling data obtained experimentally in the laboratory. Index Terms - Intelligent ..

Multibody dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: Formulations and Numerical Methods, Efficient Methods and Real-Time Applications, Flexible Multibody Dynamics, Contact Dynamics and Constraints, Multiphysics and Coupled Problems, Control and Optimization, Software Development and Computer Technology, Aerospace and Maritime Applications, Biomechanics, Railroad Vehicle Dynamics, Road Vehicle Dynamics, Robotics, Benchmark Problems. The conference is organized by the Department of Mechanical Engineering of the Universitat Politècnica de Catalunya (UPC) in Barcelona. The organizers would like to thank the authors for submitting their contributions, the keynote lecturers for accepting the invitation and for the quality of their talks, the awards and scientific committees for their support to the organization of the conference, and finally the topic organizers for reviewing all extended abstracts and selecting the awards nominees.Postprint (published version