A brightness sensing system includes an image pickup unit for taking an image of a target space and a calculation unit for calculating the brightness of an image pickup area based on the image taken by the image pickup unit. The fuel cell stack includes a plurality of fuel cells stacked together in a stacking direction, and end plates provided at opposite ends of the fuel cells in the stacking direction. The width of the total reflection confinement waveguide is identical to or substantially identical to the width of the line defect portion. If the systems and methods determine that power costs can be optimized by moving the workflow from the datacenter currently handling the workflows to a different datacenter, service requests from corresponding client applications and any data resources associated with the workflows are migrated to the different datacenter. A clamp is also provided for engaging a cylindrical body, such as a torch. At last, the outlet of the micromixer is located in the downstream of the mixing chamber and further is able to connect with other elements.