Multispectral camera is the principal payload in China's first hazards mitigation satellite, which is designed for hazards
monitoring, assessment, and management. However, the camera's dynamic range of scenery is not as wide as expected
and partly influences imaging quality on-orbit. This paper analyzed the reason of this phenomenon, discussed potential
solutions and proposed a strategy of on-orbit gain control. The key point of this strategy is to update the radiation
property of imaging area dynamically, to effectively narrow down the flux range and sufficiently employ system
capability of quantification. A case study on urban scene achieved gains for different latitudes and different seasons to
generate a lookup table. And the effect of the strategy was validated by simulation and comparison between before and
after use of the strategy. The result demonstrated that the strategy could effectively improve dynamic range and
imaging performance. This study can provide guidance for future camera design.
We present here a pretty simple method for matching the indices of refraction between a solid and a liquid, which is needed for flow visualization inside porous media. With this technique, a matched medium, consisting of Duran glass beads and a mixture of Dow Corning 550 and Dow Corning 556 is made. Experiments are conducted in an open channel with a porous bed and overlying fluid to investigate fluid dynamics in the interface region of fluid and porous. Using Particle Image Velocimetry, flow fields both in the fluid region and within porous region are obtained.