Abstract: A joint motion simulator to simulate biomechanical motion includes a mount to which a prosthetic device is mounted, actuators coupled to the mount to drive the mount, and a programmable controller to drive the actuators to translate the mount and to rotate the mount with a center of rotation controllable independent of translation. The simulator can include a linear actuator to translate the mount in a linear direction substantially parallel to the axis of rotation. The linear actuator can include a piston within a sleeve, the piston being coupled to the mount and being hydraulically driven to translate the mount, and the actuators can be coupled to the sleeve. The controller may be programmed to vary the center of rotation with linear translation and rotation of the mount. Sensors may be included that measure displacement of the actuators. The controller may drive the actuators based on the measured displacement.

Abstract: Corrosion of steel surfaces in a heat pump is inhibited by adding a rare earth metal salt to the heat pump's ammonia/water working fluid. In preferred embodiments, the rare earth metal salt includes cerium, and the steel surfaces are cerated to enhance the corrosion-inhibiting effects.