Kiao Inthavong - Academia.edu (original) (raw)

Papers by Kiao Inthavong

Journal of Aerosol Science, 2008

The inhalation of toxic particles such as asbestos fibres through the nasal airway has been found... more The inhalation of toxic particles such as asbestos fibres through the nasal airway has been found to cause harmful damage to the respiratory system. This study made use of CFD techniques to investigate deposition of fibrous particles in a human nasal cavity. A 3D computational model was created from CT scans which provided the framework to study the flow and

ABSTRACT The use of CFD in biomedical applications has emerged as a legitimate alternative to tra... more 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 Ultimately, the goal of Computational Fluid Dynamics (CFD) is to provide a numerical des... more 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 A BCI enables a new communication channel that bypasses the standard neural pathways and... more 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.

The computational model was created for computational fluid dynamics (CFD) analysis which provide... more The computational model was created for computational fluid dynamics (CFD) analysis which provides details on the geometry and airflow dynamics such as the pressure drop. A comparison between the two models was undertaken to determine the disparities in the inhalation efforts and the airway branch diameters caused by physiological changes in the airway trees. It was found that in general the right side of the reconstructed airway tree is larger in diameter than the left side. Additionally the right airway exhibited greater dilation from the acute-asthma model to the recovered model in comparison with the left airway especially from the fifth generation onwards. The required pressure difference at the inlet for the AA-model was 5.98 Pa, which is nearly twice the value for the recovered model (3.73 Pa).

Biological and Medical Physics, Biomedical Engineering, 2015

ABSTRACT Over the last three decades there has been considerable progress in computational modell... more ABSTRACT Over the last three decades there has been considerable progress in computational modelling. However many issues still need to be resolved. Advances in computational resources and techniques will enable significant progress to be made in modelling realistic physiological scenarios of the respiratory system. The materials presented in this book thus far serve as an introduction to some of the current trends and modeling achievements, and in this chapter we present the latest developments and address some of the important issues and challenges that are currently faced by many researchers.

Journal of Aerosol Science, 2008

The inhalation of toxic particles such as asbestos fibres through the nasal airway has been found... more The inhalation of toxic particles such as asbestos fibres through the nasal airway has been found to cause harmful damage to the respiratory system. This study made use of CFD techniques to investigate deposition of fibrous particles in a human nasal cavity. A 3D computational model was created from CT scans which provided the framework to study the flow and

ABSTRACT The use of CFD in biomedical applications has emerged as a legitimate alternative to tra... more 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 Ultimately, the goal of Computational Fluid Dynamics (CFD) is to provide a numerical des... more 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 A BCI enables a new communication channel that bypasses the standard neural pathways and... more 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.

The computational model was created for computational fluid dynamics (CFD) analysis which provide... more The computational model was created for computational fluid dynamics (CFD) analysis which provides details on the geometry and airflow dynamics such as the pressure drop. A comparison between the two models was undertaken to determine the disparities in the inhalation efforts and the airway branch diameters caused by physiological changes in the airway trees. It was found that in general the right side of the reconstructed airway tree is larger in diameter than the left side. Additionally the right airway exhibited greater dilation from the acute-asthma model to the recovered model in comparison with the left airway especially from the fifth generation onwards. The required pressure difference at the inlet for the AA-model was 5.98 Pa, which is nearly twice the value for the recovered model (3.73 Pa).

Biological and Medical Physics, Biomedical Engineering, 2015

ABSTRACT Over the last three decades there has been considerable progress in computational modell... more ABSTRACT Over the last three decades there has been considerable progress in computational modelling. However many issues still need to be resolved. Advances in computational resources and techniques will enable significant progress to be made in modelling realistic physiological scenarios of the respiratory system. The materials presented in this book thus far serve as an introduction to some of the current trends and modeling achievements, and in this chapter we present the latest developments and address some of the important issues and challenges that are currently faced by many researchers.