A system and method are provided for reducing vibrations and loads in one or more rotor blades on a rotor hub of a wind turbine when the rotor hub is in a locked or idling condition. An electronically tunable mass damper is attached to a fixed location on one or more of the rotor blades. The mass damper is maintained on the rotor blades during the locked or idling condition of the rotor hub. The method includes sensing movement of a mass component of the mass damper from vibrations or oscillations induced in the rotor blade. The mass damper is automatically tuned based on the sensed movements of the mass component by automatically varying an electrical characteristic of the mass damper.

A portable device for precision plasma and oxy-fuel torch cutting is provided. Versions of an example portable cutting torch tool guide the gun of a cutting torch to make precision linear cuts or curved cuts in a metal workpiece. In an implementation, the device is a gun for a cutting torch, with an integrated rail follower and adjustable vertical and horizontal offsets from a workpiece. The cutting torch tool may use various kinds of rails for stable cuts, with optional movement damping, motorized drive, servos for vertical and horizontal offset, and remote control with user interface.

A vibration damper that damp vibrations transmitted between a drive unit and a support body. The vibration damper comprises: an elastic member interposed between the drive unit and the support body; a rotor supported by the drive unit or the support body; and a vibration translating mechanism that rotates the rotor and reciprocates the rotor between the drive unit and the support body, in response to the vibrations acting in a vibrating direction to isolate the drive unit and the support body away from each other and bring the drive unit and the support body closer together.

A novel rotation vibration damper and to vibration absorbers having the damper for wind turbines or other high and, relative to the height thereof, narrow installations or buildings. The disclosure particularly relates to vibration absorbers comprising at least one oscillating mass on a pendulum cable or pendulum rod, wherein the mass is caused to vibrate by an excitation frequency which can be damped by a rotation damper and, in particular, a rotating eddy current magnet damper which forms part of the absorber.

This disclosure relates to an active inerter damper configured to be disposed on or in a building structure. The active inerter damper includes a base, a lead screw, a rotational mass block, a driving device and a controller. The lead screw is movably disposed above the base along an axial direction. The rotational mass block is engaged with the lead screw so as to be rotatable with respect to the base. The driving device is connected to the lead screw. The controller is electrically connected to the driving device, and the controller is configured to activate the driving device to move the lead screw along the axial direction so as to rotate the rotational mass block via the lead screw.

A dynamic balance type vertical vibration isolator includes slide blocks, balance springs, mass blocks, a fixed block, rotation shafts, stiffness-adjustable springs, etc. When an earthquake force is upward, the stiffness-adjustable springs are compressed, upward forces of the stiffness-adjustable springs are increased, meanwhile, the slide blocks and the mass blocks move away from the fixed block, the balance springs are stretched to generate pull forces, and the pull forces have vertically upward components, so as to reduce compression degrees of the stiffness-adjustable springs, and further to reduce the upward forces of the stiffness-adjustable springs. Similarly, when the earthquake force is downward, the stiffness-adjustable springs are stretched, downward forces of the stiffness-adjustable springs are increased, meanwhile, the slide blocks and the mass blocks move close to the fixed block, the balance springs are compressed to generate compression forces, and the compression forces have vertical downward components.

An apparatus for damping an actuator includes an inerter. The inerter includes a first terminal and a second terminal movable relative to one another along an inerter axis and configured to be mutually exclusively coupled to a support structure and a movable device actuated by an actuator. The inerter further includes a rod coupled to and movable with the first terminal and a threaded shaft coupled to and movable with the second terminal. The inerter further includes a flywheel having a flywheel annulus coupled to one of the rod and the threaded shaft. The flywheel is configured to rotate in proportion to axial acceleration of the rod relative to the threaded shaft in correspondence with actuation of the movable device by the actuator.

The rotary inertial mass damper has a configuration in which the rotary shaft of the oil-pressure motor rotates due to oil pressure of operating oil that is extruded from an oil chamber through reciprocating movement of the piston rod, and viscosity resistance is produced in operating oil that circulates in the connection pipes.

A vibration absorber which, in addition to a main mass which is fixed thereto and moved along a curved trajectory by a driving mechanism, comprises a substantially smaller variably adjustable rotating flywheel mass which is moved together with the main mass along the trajectory thereof, enabling the adjustment of the frequency of the absorber. The rotating flywheel mass is driven by a novel belt device independently of the driving mechanism. A rotating vibration absorber which, along with the main mass and the rotating flywheel mass, comprises its own damping unit, such as an eddy-current damping unit.

A kit is described that comprises a device adapted to dampen the vibrations transmitted by the rotor to the fuselage; the device comprises two first elements movable along a first axis; two second elements rotatable about the first axis; a first inerter with a first female screw, a first screw, and first rollers rotatable about respective second axes and around the first axis with respect to the first female screw and first screw; a second inerter with a second female screw, a second screw operatively connected to the second female screw; and a plurality of second rollers rotatable about second axes and around the first axis with respect to the second female screw and second screw; the first and second female screws defining the first threaded elements, and the first and second screws defining the second threaded elements; or the first and second screws defining the first threaded elements and the first and second female screws defining the second threaded elements.