Systems and methods to affect heat input to a weld and, therefore, an appearance of a deposited weld bead by modulating a mixing ratio of shielding gases andor one or more welding parameters. A number of policy settings are specified for the power center, including a power limit for the datacenter. Advantageously, the potentiometer and cursor are housed inside an armored case. Transistors, in which the gate and the back gate are connected to each other, are used for the circuit generating the back gate driving signal, and logic circuits having a heavy load such as circuit block output section, and the back gates are directly controlled according to the gate input signal. The third row squab can then be folded down to form a flat floor.