Jiyuan Tu

ABSTRACT The use of CFD in biomedical applications has emerged as a legitimate alternative to traditional cast models and human experimental methods. With recent developments in computational hardware, biomedical imaging instruments and CFD techniques, new and exciting research possibilities for the human respiratory system have emerged—some of which were discussed in Chap. 1. In the preceding chapters important fundamental steps were described in relation to the development of computational models of the respiratory system. The morphology and physiological nature of the respiratory system outlined in Chap. 2 highlights the increased level of complexity that is involved in biomedical CFD applications. For example, small scales, surface irregularities, and high curvatures are all characteristic of the nasal cavity, larynx and upper lung airway. These issues bring to fore the need for convergence of multi-disciplines, involving biomedical imaging, reverse engineering in Computer-Aided-Design (CAD), and finally CFD. In Chap. 3 the needed steps for reconstructing the respiratory passage were discussed. In fact, these preparatory steps can be viewed as a prerequisite for construction of any complex geometry. From the reconstructed CAD model, CFD simulations can then be undertaken by first developing a computational mesh (Chap. 4), and then applying the appropriate physics to suit the problem at hand. For example, fluid flow problems, such as inhalation and humidification of the inhaled air, need to consider the fundamentals of fluid dynamics as described in Chap. 5, whereas the inclusion of inhaled particles for drug delivery or for harmful particles suspended in the atmosphere require additional particle equations and models which were discussed in Chap. 6. The correctly defined problem is then ready to be solved computationally. The numerical schemes and algorithms found in Chap. 7 are the cornerstone of any CFD analysis. Fundamental understanding of the conservation equations and numerical approximations is prerequisite for generating efficient solutions.

ABSTRACT A BCI enables a new communication channel that bypasses the standard neural pathways and output channels and in order to control an external device. BCI technology has been developed to enable lost body or communication functions in handicapped persons. Recently BCI systems are used for communication purposes, to control robotic devices to control games or for rehabilitation. This means BCI systems are not only built for user groups with special needs but also for healthy people. A limiting factor in the wide-spread application is the usage of abrasive gel and conductive paste to mount EEG electrodes. Therefore many research groups are now working on the practical usability of dry electrodes to completely avoid the usage of electrode gel. In this chapter results for endogenous and exogenous BCI approaches are presented and discussed based on the g.SAHARA dry electrode sensor concept. Raw EEG data, power spectra, the time course of evoked potentials, ERD/ERS values and BCI accuracy are compared for three BCI setups based on P300, SMR and SSVEP BCIs. Although the focus in this study was set to P300 evoked potentials it could be demonstrated that the used electrode concept works well for BCI based on P300, SMR and SSVEP BCI.

ABSTRACT Ultimately, the goal of Computational Fluid Dynamics (CFD) is to provide a numerical description of fluid flow behaviour. This is achieved through solving the governing equations that are mathematical statements of the physical conservation laws: conservation of mass; balance of momentum (Newton’s second law, the rate of change of momentum equals the sum of forces acting on the fluid) and; conservation of energy (first law of thermodynamics, the rate of change of energy equals the sum of rate of heat addition to, and the rate of work done on, the fluid).

ABSTRACT Before delving into the computational methods of reconstructing the respiratory models, we first discuss the respiratory system from a functional point of view. In addition, descriptions, locations, geometry, and naming conventions for the anatomical parts are discussed in order to establish a basis for decision-making when reconstructing the model. This chapter provides the fundamentals of the anatomy and physiology of the respiratory system and may be skipped if the reader has an established background in this field.