Abstract: A sample having a known mass and stiffness is rigidly secured to an axially elongated beam having a mass and a stiffness that are very large as compared to the mass and stiffness of the sample. The beam is then caused to resonate in the free-free mode. This subjects the sample to cyclical unidirectional stress. Advantageously, resonance of the beam occurs at an audio frequency, permitting severe fatigue tests requiring tens of millions of cycles to be completed in a relatively short time.

Abstract: An electro-thermal or hot gas anti-icer of the “running-wet” type is mounted at the leading edge of an airfoil. Mechanical de-icers are mounted on the surfaces aft of the anti-icer. The mechanical de-icers throw off ice without creating runback water, thereby eliminating runback refreeze ridges caused by a known hybrid ice-protection system. Advantageously, the de-icers are of a type in which the airfoil has a semi-rigid skin that forms an aerodynamic surface of the airfoil, and in which there is at least one mechanical actuator for flexing the skin.

Abstract: An electro-thermal or hot gas anti-icer of the "running-wet" type is mounted at the leading edge of an airfoil. Mechanical de-icers are mounted on the surfaces aft of the anti-icer. The mechanical de-icers throw off ice without creating runback water, thereby eliminating runback refreeze ridges caused by a known hybrid ice-protection system. Advantageously, the de-icers are of a type in which the airfoil has a semi-rigid skin that forms an aerodynamic surface of the airfoil, and in which there is at least one mechanical actuator for flexing the skin.

Abstract: A pass network includes a switching element having a non-smooth conduction characteristic in the transition region about zero-crossover of an AC signal to be switched. A bypass network is connected in parallel with the pass network and has a smooth conduction characteristic in that transition region.