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Transmission of droplets has been recognized as an important form of infection for the respiratory diseases. This study investigated the distribution of human respiratory droplets and assessed the effects of air change rate and generated velocity on droplet transmission using an active agent in an enclosed chamber (46 m3). Results revealed that the higher the air change rate was, the fewer viable droplets were detected in the range of <3.3 μm with ventilation; an increased air change rate can increase the attenuation of droplet aerosol. Without ventilation, the viable droplet size was observed to mainly distribute greater than 3.3 μm, which occupied up 87.5% of the total number. When the generated velocity was increased to 20 m/s, 29.38% of the viable droplets were detected at the position of 2.0 m. The findings are excepted to be useful for developing the technology of reducing droplet propagation and providing data verification for simulation research. [ABSTRACT FROM AUTHOR]

A novel tunable band-pass filter using yttrium-iron-garnet (YIG) disk and a coplanar-slotline structure is proposed. The filter is tunable from 0.76 to 14.5 GHz. Over this band of frequencies the maximum insertion loss was 4.9 db and the minimum loss 1.7 db. The planar type device is well suited for the microwave integrated circuits (MIC) planar technology.