A silencing device, an air purifier, and a method for producing the same are provided. The method includes that: a sound wave spectrum when an air purifier to be silenced performs operations is acquired; a frequency value, which exceeds a sound wave frequency limit for the air purifier, of the sound wave spectrum is calculated; and a silencing device adapted to the air purifier to be silenced is produced according to the frequency value. At least one structural parameter of the silencing device is configured according to the frequency value. The silencing device is configured to reduce a sound with the frequency value exceeding the sound wave frequency limit.

The invention relates to a method for operating a combined clutch and brake device (5) of a punch press (1) equipped with dry friction linings (7, 8). Thereby, the friction linings (7, 8) are arranged in a chamber (R) which is sealed off from the environment of the punch press (1), and which is filled with a dry and oil-free gaseous medium, in particular with dry oil-free air. This effectively prevents moisture and oil mist from entering the region of the friction linings from the environment of the press, and a constant friction coefficient can be achieved over the mechanical service life of the friction linings.

A terminal unit for a heating, ventilation, and air conditioning (HVAC) system includes a housing defining a plenum and having a first panel and a second panel disposed opposite each other. The first panel has a first outlet opening and a second outlet opening, and the second panel has a first inlet opening configured to receive a first air flow and a second inlet opening configured to receive a second air flow. The terminal unit includes a sound attenuator including an inlet configured to receive the first air flow and an outlet configured to discharge the first air flow into the housing via the first inlet opening. The terminal unit further includes first and second blowers. The first blower is configured to discharge air from the plenum via the first outlet opening, and the second blower is configured to discharge air from the plenum via the second outlet opening.

Systems and methods for noise suppression for aircraft are disclosed. The aircraft may include a fuselage. The aircraft may include a plurality of wings connected to or formed with the fuselage. The aircraft may include at least one engine configured to generate a propulsion force to propel the aircraft. The at least one engine may include a nozzle assembly having a nozzle body with an outlet that releases an exhaust air or a jet flow. The aircraft may include a noise suppression assembly. The noise suppression assembly may be configured to interact with the exhaust air or jet flow to substantially suppress, mitigate, reduce, or otherwise modify noise generated by the aircraft.

An ultrasonic flow measurement system (1) comprising a flow tube (11), an ultrasound damping layer (12), an ultrasound transmitter (13) covered by the ultrasound damping layer, and an ultrasound receiver (14) covered by the ultrasound damping layer, characterised in that the ultrasound damping layer comprises: —a first damping portion (121) that is at least partially positioned in between the ultrasound transmitter and the ultrasound receiver as well as—a second damping portion (122) that is at least partially positioned in between the ultrasound transmitter and the ultrasound receiver, wherein the first damping portion and the second damping portion of the ultrasound damping layer are spaced apart from each other by a distance (d) in an axial direction (A) of the flow tube.

A car having: two front wheels; two rear wheels; a bottom wall, which delimits a lower surface, which faces a road surface and, in use, is brushed by an air flow flowing under the car; an internal combustion engine; and an exhaust system, which is coupled to the internal combustion engine and is provided with an exhaust duct, which originates from the internal combustion engine and has an end chamber, which ends with an outlet opening, through which exhaust gases are released into the atmosphere. The end chamber of the exhaust duct has at least one movable partition, which can be moved to different positions so as to change the width of the outlet opening. The movable partition delimits a lower surface of the end chamber, which faces the road surface and, in use, is brushed by the air flow flowing under the car.

An exhaust system for an internal combustion engine and having an end chamber having a first inlet opening and a second inlet opening, which are separate from and independent of one another, and an outlet opening, through which exhaust gases are released into the atmosphere; an exhaust duct, which originates from the internal combustion engine and leads to the first inlet opening of the end chamber; a silencer device, which has an outlet opening, which directly leads to the second inlet opening of the end chamber; a bypass duct, which originates from the exhaust duct in the area of a bifurcation and ends in an inlet opening of the silencer device; and an adjustment valve, which can be electronically controlled, is arranged along the exhaust duct downstream of the bifurcation where the bypass duct originates and is designed to adjust the exhaust gas flow towards the first inlet opening of the end chamber.

A noise reduction apparatus includes a housing, a first baffle component, and a second baffle component. The housing includes a first installation chamber configured to contain diesel generating equipment, and the first installation chamber has a top plate, a bottom plate, and a first side plate, and a second side plate that is disposed opposite the first installation chamber from the first side plate. An air intake vent is disposed on the first side plate, and an air exhaust vent is disposed on the second side plate. A first serpentine channel is formed in the first baffle component, and one end of the first serpentine channel is connected to the air intake vent. A second serpentine channel is formed in the second baffle component, and one end of the second serpentine channel is connected to the air exhaust vent.

An engine cover covers an engine; and an intake pipe through which the air is introduced into the engine. An intake silencer is provided adjacent to the intake pipe and suppresses air pressure fluctuations of air in the intake pipe to reduce intake sound. A portion of the intake silencer is covered with the engine cover, and a remaining portion is exposed with respect to the engine cover. An advantage is that secondary noise generated by the intake silencer and a temperature increase of air suctioned into the engine are simultaneously suppressed.

A muffler device for use in a bicycle suspension system that has an axis is presented. The device includes a flow path permitting a pressurized fluid to flow therethrough, and a muffler member having a porous surface that at least partially defines the flow path. The device is provided to dampen the acoustic energy of the system.