A mathematical model of liquid nitrogen system of a space environmental simulator is introduced and a quasi-stationary control method is developed in this paper.

Twenty-three spent 45 to 60 minutes on a treadmill or stationary bicycle four days a week for six months, while the other 10 "control" subjects did stretching exercises but kept their heart rate low.

Standing wave ultrasonic motors have many outstanding features for simple drive and control circuit, stationary speed of rotation, smaller undulation, etc.