D. Koolpiruck

Numerical modeling of inhaled charged aerosol deposition in human airways

A new numerical modeling of inhaled charge aerosol has been developed based on a modified Weibels model. Both the velocity profiles (slug and parabolic flows) and the particle distributions (uniform and parabolic distributions) have been considered. Inhaled particles are modeled as a dilute dispersed phase flow in which the particle motion is controlled by fluid force and external forces acting on particles. This numerical study extends the previous numerical studies by considering both space- and image-charge forces. Because of the complex computation of interacting forces due to space-charge effect, the particle-mesh (PM) method is selected to calculate these forces. In the PM technique, the charges of all particles are assigned to the space-charge field mesh, for calculating charge density. The Poissons equation of the electrostatic potential is then solved, and the electrostatic force acting on individual particle is interpolated. It is assumed that there is no effect of humidity on charged particles. The results show that many significant factors also affect the deposition, such as the volume of particle cloud, the velocity profile and the particle distribution. This study allows a better understanding of electrostatic mechanism of aerosol transport and deposition in human airways.

The role of electrostatic charge accumulated by respirable sized allergens with regard to thunderstorm asthma

Asthma is a chronic respiratory condition that renders the sufferer susceptible to attacks of airway inflammation characterised by wheezy breathlessness. Hospital asthma admissions of epidemic proportions can be triggered by numerous events including thunderstorms. Allergens consisting of starch granules with diameters /spl les/ 1/spl mu/m have been implicated as the causal agent of these thunderstorm epidemics and are released as pollen grains rupture via osmotic shock upon contact with moisture. The meteorological conditions associated with thunderstorms therefore produce an atmosphere with a sufficiently high concentration of respirable allergens that too great an inhalation challenge is presented to sensitive individuals. The wind and rains required to produce this atmospheric abundance of allergens are, however, also found in association with other phenomena not coincident with a rise in asthma incidence and therefore a more specific thunderstorm related cause has been sought. There has been little systematic investigation into the electrical effects of thunderstorms and in particular the accumulation of charge by atmospheric particulates. The effect of particle charge on deposition within the lungs has therefore been investigated using numerical modelling techniques. Initial simulations were carried out using a one-dimensional implementation of Weibels lung model of the complete airway. Applied particulate concentration was estimated based upon the levels of intact pollen available for rupture at the time of previously investigated asthma epidemics. Inhalation flow rate corresponded to 0.5 litres per second. The Rayleigh charging limit for particles with a 1 /spl mu/m diameter was calculated and deposition simulated using proportions of this unipolar charge level. It was found that increasing charge levels up to the Rayleigh limit affected a shift in peak deposition upward from the alveolar region. Particles of various diameters were then input into the simulation with charge equal to the half their Rayleigh limit. Reducing the particle size from 2 /spl mu/m to 0.25 /spl mu/m again affected a shift in peak deposition but this time into the alveolar region. Further simulation was then carried out using a two-dimensional implementation of Weibels model of the lower airway only, modified to incorporate the branching structure and alveolated walls found in this region. Multiple breath simulations were performed showing the complex nature of particle residence and deposition within the alveolar region. Deposition efficiencies in the lower airway regions were found to increase with particle charge. This effect was observed to be greater with smaller particle diameters due to their increased mobility. The results of both simple and more complex simulations of the inhalation of particles with diameters appropriate to the respirable allergens thought likely to be the causal agent with regard to thunderstorm asthma have been obtained. An increase in the charge resident on these particles was found to alter the deposition throughout the entire airway and promote proportional deposition efficiency within the alveolar region where provocation of an allergic response is most likely. These results have implications not only for an increased understanding of thunderstorm related asthma epidemics but for the deposition of deliberately introduced particles such as respiratory drugs.

A particle swarm optimization approach for optimal design of PID controller for position control using Shape Memory Alloys

This paper presents the optimal design of PID controller based on a particle swarm optimization (PSO) approach for position control using spring shape memory alloys (SMA) actuator. The mathematical model of experimental system had been approximate near the operating point for the PSO algorithm to adjust PID parameters for the minimum integrated absolute error (IAE) condition. The results show the adjustment of PID parameters converting into the optimal point and the good control response base on the optimal values by the PSO technique.

Cyber-Physical System Based Production Monitoring for Tapioca Starch Production

Tapioca starch is the important for Thai agricultural industry economy. According to the 4th industrial revolution, cyber-physical system becomes the key technology to enable vertical and horizontal automation system integration. This study aims to develop cyber-physical system based production monitoring for tapioca starch production. To achieve the service oriented architecture (SOA) based solution for industry, OPC UA standard used to develop the proposed system. The proposed CPS provided services involved production monitoring including production information management system associated with laboratory information management system. This system was selected due to the variation of raw material and process model for estimation of unknown parameters. The experiments were done with performance monitoring of separation process of 250 ton/day capacity plant. The results revealed that separation process performance can be shown in production dashboard.

Online fatigue detection of a SMA-based control valve using CUSUM algorithm

This paper describes a functional fatigue detection system for nonlinear SMA-based control valve. Any drift from the normal behavior of the valve is revealed using a model-based residual generator by means of a nonlinear auto-regressive with eXogenous input (NARX) model. Based on the optimisation property of cumulative sum (CUSUM), an online system for detecting changes in statistical properties of residuals due to fatigue of the valve is developed. The experimental results suggest that the variance of one step ahead (OSA) error and model predicted error (MPE) is a good indicator of fatigue states of the valve.

Optimization of Chemical Vapor Deposition Synthesis Conditions for Multiwall Carbon Nanotube by Statistical Analysis of Experiment

The optimization of chemical vapor deposition synthesis conditions for multiwall carbon nanotubes (MWCNTs) was experimentally investigated. Carbon nanotubes were grown on cobalt substrate thicknesses of 20, 100 and 1000 nm at 700 and 900 0C with 2 replications. The configuration and morphology of the carbon nanotubes were investigated by scanning electron microscope and Fourier transform raman spectrometer, respectively. The tendency of the parameters was evaluated by statistical design of experiment. Observations on samples produced under our optimised production process, showed that a large number of MWCNTs bundles were produced. Diameter of MWCNTs bundles ranges between 30 and 100 nm throughout the samples. From the variance analysis of the Raman spectra we observe that the thickness of cobalt and temperature of synthesis are highly significant in which the coherence length and innermost diameter increase for either the thickness increases or the temperature decreases.

Deposition of charged inhaled aerosols with transient airflow in sequential lung airway model

Transport and deposition of charged inhaled aerosols in double planar bifurcation representing generation three to five of human respiratory system has been studied under a light activity breathing condition. Both steady and oscillatory laminar inhalation airflow is considered. Particle trajectories are calculated using a Lagrangian reference frame, which is dominated by the fluid force driven by airflow, gravity force and electrostatic forces (both of space and image charge forces). The particle-mesh method is selected to calculate the space charge force. This numerical study investigates the deposition efficiency in the three-dimensional model under various particle sizes, charge values, and inlet particle distribution. Numerical results indicate that particles carrying an adequate level of charge can improve deposition efficiency in the airway model.