A portable human body pulsating apparatus has an air pulse generator mounted on a pedestal having wheels to facilitate movement of the apparatus on a surface. The accelerators have excellent long-term stability and work well with \u201cdifficult\u201d cements, such as some Japanese OPCs. The wafer handling traction control system may include a sensor that detects relative motion between the semiconductor wafer and the end effector. The mating body is configured to engage an upper substrate and the mounting body is configured to engage a lower substrate to mechanically interconnect the upper and lower substrates. Based on the deviation between the computed predictive engine speed and the actual engine speed of the engine, the regulators of the hydraulic pumps are controlled.