Based on communication theory, this study proposes a model to synthesize normal and wheezing sounds. The model included five parts: the flow source as a transmitter, the frequency and amplitude-modulated (FM-AM) sounds, the accompanying noise as a modulator, the airway wall as a medium, and the microphone as a receiver. The hypothesis of modulation builds on that the deviation of frequency and amplitude of the sounds which cause from the deviation of collision speed of the air flow on the wall. The model was successful to simulate the normal breath and wheezing sounds. Furthermore, it provided a correct proof for the CORSA description, which indicates that the wheeze was contained in the domain frequency at 400 Hz, but a number of investigators have suggested that the range is actually between 80-1,600 Hz and 350-950 Hz by filter theory. This study modifies the signal source in Wodicka et al. model, and describes it in functional blocks. In fact, the design of the signal source base on the knowledge of the lung sound studies, especially the analysis of components in the frequency and time domains. We synthesized the required components to reproduce the lung sounds, and proposed a mechanism of wheeze which was examined by the computer simulation in the points of the system engineering view.

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Powered wheelchairs are an important mobility aid for the elderly and for persons with disability. According to World Health Organization statistics, most of the accidents were due to personal mistakes; if there is an auto-navigating system such as auxiliary, mistaken manipulation will decrease efficiency. This study attempted to improve the global positioning system (GPS) navigation of electric powered wheelchairs (EPWs) through the addition of an electric compass (EC) and tested the navigation of EPWs with EC-aided and non-EC-aided GPS navigation along a 25 m road. According to these tests, the use of the EC significantly reduces the errors in GPS navigation during movements such as go straight ahead, turn right and turn left. Therefore, the navigation reduced the error of the expected trajectories with the EC-aided navigation.