A multi-process scheduler applies a joint optimization criterion to jointly schedule multiple processes executed on a shared processor. The fluid composition includes a mixture of poly-functional compounds, a colorant compound, a photo-initiator and less than about 50 weight percent water based on a total weight of the fluid composition, wherein the fluid composition is substantially devoid of volatile organic carrier fluids. The power tool fixer includes a rotating element that rotates in a normal direction it the spring force of the coil spring as the drive member drives the coil spring, an outer edge of the rotating element, an engaging member and a lock avoiding mechanism.