A vibration attenuation device is provided. The vibration attenuation device includes one or more connectors configured to be attached to a primary structure, a plurality of beams mounted on the one or more connectors, and a plurality of weight materials attached to the beams. The primary structure comprises at least one of a pipe, a rod or a shaft.

Apparatuses and systems for damping vibration of a vacuum vessel mounted with a pump include a pump body and a damping element coupled to the pump body, wherein the pump body and the damping element form a mass-based damper, and wherein the pump body forms a mass component of the mass-based damper; and the damping element forms a damping component of the mass-based damper. The apparatuses and systems also include a pump body configured to be secured to a column of a charged-particle inspection apparatus, a sensor coupled to the pump body, an actuator coupled to the pump body, and a circuitry communicatively coupled to the sensor and the actuator for receiving motion data indicative of a vibration of the column; determining a damping based on the motion data; and actuate the actuator to react to the vibration of the column in accordance with the damping.

A method is provided for actively compensating for pressure changes of a working fluid within a conduit. A first cavity is provided in fluid communication with the conduit. A second cavity is in fluid communication with a control fluid. A plunger is in communication with both the first cavity and the second cavity and is movable in response to pressure changes of the working fluid in the conduit. The plunger is re-centered. Re-centering the plunger includes the following steps. Position data representative of movement of the plunger is collected. The position data is analyzed with a control unit to determine an average position of the plunger which is offset relative to a center position. The average position of the plunger is compared, with a control unit, to the center position. A signal is relayed from the control unit to a control valve to urge the plunger toward the center position.

An air supply duct for fan is used to guide air to an air intake port of a fan, and includes a duct main body portion in which an air passage extending in a predetermined x direction with one end side set as an air inlet port is formed inside, and an air supply port for supplying air travelling through the air passage to the air intake port of the fan is arranged. A peripheral region of the air supply port of the inside of the duct main body portion is surrounded by wall portions in the periphery except for a communication portion with the air passage, and is configured as a space portion for generating air column vibration and having a width in a y direction intersecting the x direction larger than a width of the air passage. A combustion device including the air supply duct is provided.

The invention relates to an assembly for centring a first elongate tubular element and a second elongate tubular element, such as an underwater pile accommodated within a noise mitigation screen, at a common central longitudinal axis along which axis both the first and second element extend, and wherein the centre system is provided with first coupling element for fixedly coupling the centre system with one of the first and second tubular elements, and second coupling element for engaging the other tubular element for centring the other tubular element at the central axis.

The invention relates to a device for active reduction of pressure fluctuations in a hydrodynamic system comprising a pump, a pressure fluctuation generator and at least one pressure sensor, and a controller unit. The controller unit is adapted to control the pressure fluctuation generator and to receive a pressure fluctuation signal from the pressure sensor. Furthermore, the present invention relates to a corresponding method and a pressure fluctuation generator for a corresponding device.

Liquid accumulators and methods for reducing pulsations of a liquid flow are disclosed. A liquid delivery system comprises a pump configured to drive liquid to a pipe. The pipe is configured to transmit a liquid flow. A liquid accumulator is fluidically connected to the pipe. The liquid accumulator comprises a chamber containing the liquid and a vapor column and a power source configured to input energy to the chamber to generate vapor from the liquid to form the vapor column. The vapor column constitutes a gas spring to reduce pulsations of the liquid flow in the pipe. The spring rate of the gas spring can be adjusted by changing the input energy level from the power source to the chamber.

A work vehicle has a chassis, and a member connected to the chassis for movement with respect to the chassis. An actuator is connected to the chassis and to the member to move the member with respect to the chassis. A hydraulic circuit is connected to the actuator and a pump pressurizes fluid in the hydraulic circuit. An adjustable quarter wave tuner is connected to the hydraulic circuit. The adjustable quarter wave tuner has a length that is adjustable within a range of lengths to thereby reduce noise caused by the pump across a corresponding range of frequencies. In some embodiments, the member is a linear actuator, such as a hydraulic cylinder. In other embodiments, the member is a rotary actuator, such as a hydraulic motor.

An engine exhaust flow meter and method of measuring engine exhaust flow rate includes a flow tube and a differential pressure meter that is adapted to measure differential pressure in exhaust flow through the flow tube. A computer samples the differential pressure meter at a rate that is greater than the pulsation of exhaust flow to obtain a differential pressure signal. The computer is responsive to the differential pressure signal to compute a mean differential pressure value. The computer is responsive to the differential pressure signal to compute a mean magnitude of pressure pulses. The computer determines a compensation factor as a function of the mean magnitude of pressure pulses and adjusts the mean differential pressure value as a function of the compensation factor to obtain an engine exhaust flow value that is flow pulsation compensated.

A water hammer prevention system using an operation state analysis algorithm to prevents water hammer. Data is measured in real time by a pressure sensor and a water level sensor are transmitted to a control unit and stored in a database. The control unit includes an air chamber which controls the operations of an air compressor and an air exhauster to prevent water hammer. The control unit performs calculations according to a water hammer algorithm, and determines the operation states of the air compressor and the air exhauster, and whether the water hammer prevention equipment is operating normally. Active operational control of the water hammer prevention equipment can be performed by applying a data analysis technique thereto, and a failure or operation error can be identified.