Abstract: An active device for attenuating the acoustic emissions of an aircraft turbojet engine includes circulation conduits for a pressurized air flow rate supplying rotary elements each having a pulsation system for the delivered air. The rotary elements are controlled in amplitude and phase and deliver, to outlet diffusers, a pulsed air flow rate with a pulsation at the frequency of the noise to be attenuated having an amplitude and a phase adjusted according to a local feedback law with microphones to attenuate the radiated acoustic power.

Abstract: An in-line, contactless and non-destructive method for detecting and identifying defects in a moving cardboard structure is provided, as well as the associated system. The cardboard structure is of the type made of layered paper plies, such as cardboard tubes for example. The method includes the steps of emitting acoustic waves with predetermined frequencies toward the moving cardboard structure. The acoustic waves are converted into mechanical waves propagating through the moving cardboard structure. The method also includes a step of capturing the acoustic waves propagated, wherein said captured acoustic waves result from a conversion of the propagated mechanical waves through the moving cardboard structure. The method also provides steps of analyzing the captured acoustic waves; and detecting and identifying defects in the moving laminated cardboard structure based on predetermined propagation properties measured from the captured acoustic waves.

Abstract: An active device for attenuating the acoustic emissions of an aircraft turbojet engine includes circulation conduits for a pressurized air flow rate supplying rotary elements each having a pulsation system for the delivered air. The rotary elements are controlled in amplitude and phase and deliver, to outlet diffusers, a pulsed air flow rate with a pulsation at the frequency of the noise to be attenuated having an amplitude and a phase adjusted according to a local feedback law with microphones to attenuate the radiated acoustic power.

Abstract: An in-line, contactless and non-destructive method for detecting and identifying defects in a moving cardboard structure is provided, as well as the associated system. The cardboard structure is of the type made of layered paper plies, such as cardboard tubes for example. The method includes the steps of emitting acoustic waves with predetermined frequencies toward the moving cardboard structure. The acoustic waves are converted into mechanical waves propagating through the moving cardboard structure. The method also includes a step of capturing the acoustic waves propagated, wherein said captured acoustic waves result from a conversion of the propagated mechanical waves through the moving cardboard structure. The method also provides steps of analyzing the captured acoustic waves; and detecting and identifying defects in the moving laminated cardboard structure based on predetermined propagation properties measured from the captured acoustic waves.

Abstract: A method and apparatus for reducing a selected tonal noise generated by a fan operating in a non-uniform flow by locating at least one obstruction in the non-uniform flow such that the at least one obstruction generates a noise that is out of phase with the selected tonal noise. The noise generated by the at least one obstruction interferes with the selected tonal noise, thus reducing the selected tonal noise. It is also contemplated to use additional obstructions to reduce other tonal noises generated by the fan.

Abstract: A method and apparatus for reducing a selected tonal noise generated by a fan operating in a non-uniform flow by locating at least one obstruction in the non-uniform flow such that the at least one obstruction generates a noise that is out of phase with the selected tonal noise. The noise generated by the at least one obstruction interferes with the selected tonal noise, thus reducing the selected tonal noise. It is also contemplated to use additional obstructions to reduce other tonal noises generated by the fan.

Abstract: A method and apparatus for reducing a selected tonal noise generated by an axial flow fan operating in a non-uniform flow by locating at least one obstruction in the non-uniform flow such that the at least one obstruction generates a noise that is out of phase with the selected tonal noise. The noise generated by the at least one obstruction interferes with the selected tonal noise, thus reducing the selected tonal noise. It is also contemplated to use additional obstructions to reduce other tonal noises generated by the axial flow fan.

Abstract: An active suspension for a driver seat of a bus or a heavy vehicle which comprises an electric actuator allowing the exertion of the force between the floor of the vehicle and the bottom of the seat. The adjustment of the height of the seat is accomplished by an electric actuator or by an independent mechanical system. A controller generates a control force calculated from measurements obtained by sensors located at different locations on the suspension. Forces exerted by the electric actuator can be relieved by passive element placed in parallel which cannot assume by themselves the role of a suspension for a given application.