Abstract: An airflow guiding mechanism includes a housing and a shielding assembly. The housing includes an airflow guiding portion and a guiding track. The shielding assembly is movably connected to the guiding track. The shielding assembly is able to move within the airflow guiding portion along the guiding track. In an embodiment, the shielding assembly may include a first shielding plate and at least one second shielding plate. The first shielding plate is connected to the housing. The at least one second shielding plate and the first shielding plate are movably connected to each other. The at least one second shielding plate are able to move with respect to each other to be folded and unfolded, so as to open and shield the airflow guiding portion.

Abstract: 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.

Abstract: A blower with a silencer has the blower including an axial fan including a casing, a motor attached to the casing, and a rotor having a shaft portion attached to the motor and rotated and a blade formed to protrude to an outer side of the shaft portion in a radial direction, and a silencer attached to the casing, in which the silencer includes a resonator that selectively silences a dominant sound generated by the axial fan, the silencer is disposed at a position in which at least a part of the silencer overlaps with the shaft portion, as viewed from a rotation axis direction of the rotor, and in a case in which, in a cross section perpendicular to a rotation axis of the rotor, a circle around the rotation axis, which has a radius of a line connecting the rotation axis and a point of a most distal end of the blade, is defined as a rotation region, an area of the silencer in the cross section perpendicular to the rotation axis is smaller than an area of the rotation region.

Abstract: A fracturing device, including a power unit, wherein the power unit comprises a muffling compartment, a turbine engine, an air intake unit, and a starter; the air intake unit is communicated with the turbine engine through an intake pipe, and configured to provide a combustion-supporting gas to the turbine engine; the air intake unit is located at the top of the muffling compartment, the muffling compartment comprises an accommodation space, the turbine engine and the starter are located in the accommodation space, and the starter is configured to start the turbine engine, the starter comprises a first electric motor.

Abstract: A laminated sheet includes a first porous layer including a plurality of fibers of at least one of inorganic fiber or carbonized fiber; and a second porous layer formed of a plurality of organic fibers, wherein the laminated sheet has a surface density of greater than or equal to 400 g/m2 and less than or equal to 1550 g/m2, wherein the second porous layer is formed of the plurality of organic fibers having a mean diameter of fibers being greater than or equal to 0.5 ?m and less than or equal to 14 ?m, and wherein, expressing a total volume of solids and voids filling a unit volume of the second porous layer as 100%, a percentage of the solids is greater than or equal to 1.0% and less than or equal to 8.0%.

Abstract: A package-type fluid machine includes a compressor unit including a compression portion that compresses a fluid, a motor that drives the compression portion, and a cooling fan that is driven by the motor; a machine chamber in which the compressor unit is disposed; an inverter chamber which is adjacent to the machine chamber and in which an inverter is disposed; a partition wall that partitions off the machine chamber from the inverter chamber and has an opening; and an inverter intake port that is disposed in the inverter chamber to take in a cooling gas. The cooling fan is disposed on a side of the machine chamber, the opening being located on the side. The cooling fan is driven to cause the cooling gas to flow from the inverter intake port to the opening to cool the inverter.

Abstract: 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.

Abstract: An engine intake structure comprises an intake passage member 18 which defines an intake passage 36 for supplying air to an internal combustion engine 12, and which also defines a resonator chamber 40 in communication with the intake passage 36; and an in-vehicle device 14 located in an engine room 10 of a vehicle and having a preset reference temperature for temperature control, the intake passage member 18 being located above and adjacent to the in-vehicle device 14. The intake passage 36 extends above the in-vehicle device 14 so as to at least partially overlap the resonator chamber 40 as viewed in a vertical direction, thereby forming a two-layer structure, which makes the in-vehicle device 14 less affected by ambient temperature in the upper part of the engine room 10.

Abstract: The present disclosure relates to a silencer module for a silencer bank of an air handling unit. The silencer module includes a support shell having a first inner wall and a second inner wall opposite the first inner wall. The silencer module also includes a first baffle coupled to the first inner wall, where the first baffle includes a first perforated baffle sheet, and a second baffle coupled to the second inner wall, where the second baffle includes a second perforated baffle sheet. The silencer module further includes an air flow gap that extends between the first perforated baffle sheet and the second perforated baffle sheet, where the air flow gap has a width that is substantially constant along a dimension of the first perforated baffle sheet and the second perforated baffle sheet that extends generally parallel to a direction of air flow through the air flow gap.

Abstract: A cooling system for a wind tunnel is disclosed. The heat exchanger of the present disclosure is formed as a turning vane in an airflow duct of a re-circulating wind tunnels. The individual vanes are formed from extruded aluminum with coolant fluid channels running continually down the length of the vane. One or more channels can be used, depending on the application of vane and the cooling capacity needed. The exterior of the vanes are formed in an airfoil shape to efficiently turn the air flow the desired amount in a manner well known in the art. The turning vanes are connected to a fluid supply with single piece connectors that removably attach to the turning vanes. In the depicted embodiment the connectors are attached with screws. In the depicted embodiment the connectors are formed as a single piece in a two-piece injection mold.

Abstract: Embodiments of the invention are shown in the figures, where a nacelle cowling structure for a turbomachine having a bypass duct defining a path for an airflow is provided, the nacelle cowling structure including: an outer layer defining an external surface of the nacelle cowling structure, an inner layer defining a surface of the bypass duct, a front mounting area for fixation to the turbomachine and a rear mounting area for fixation to the turbomachine downstream the front mounting area with respect to the bypass duct flow path, wherein a space between the outer and inner layers and between the front and rear mounting areas is filled with acoustic material.

Abstract: A noise suppression apparatus for an air handling unit includes an inlet section connectable to a fan of the air handling unit. The inlet section includes a forward wall spaced apart from an aft wall to define an internal chamber, and an inlet wall extending between the forward wall and the aft wall, the inlet wall defining an inlet air opening. A plurality of internal walls in the inlet wall define a plurality of resonator openings that each open to at least one of a plurality of resonator sections within the internal chamber. The plurality of resonator sections include at least one quarter wave tube section and at least one Helmholtz resonator section. One or more resonator sections are configured to attenuate noise generated by the fan at two or more frequencies. At least one resonator opening of the plurality of resonator openings opens to a plurality of resonator sections.

Abstract: Compact sound attenuation systems for fluid ducts are provided having one or more sound attenuation units that can be absorptive or reflective, depending on design. Each sound attenuation unit has one or more encircling Helmholtz resonators that fully encircle the duct in a lateral direction. Sound attenuation units can be coincident with the duct well and either interior or exterior to the duct, or in some instances can be partly interior and partly exterior to the duct. Sound attenuation systems can be tuned for maximum attenuation of a single resonance frequency, or can include multiple units of different frequencies for broadband attenuation.

Abstract: The present disclosure relates to a silencer module for a silencer bank of an air handling unit. The silencer module includes a support shell having a first inner wall and a second inner wall opposite the first inner wall. The silencer module also includes a first baffle coupled to the first inner wall, where the first baffle includes a first perforated baffle sheet, and a second baffle coupled to the second inner wall, where the second baffle includes a second perforated baffle sheet. The silencer module further includes an air flow gap that extends between the first perforated baffle sheet and the second perforated baffle sheet, where the air flow gap has a width that is substantially constant along a dimension of the first perforated baffle sheet and the second perforated baffle sheet that extends generally parallel to a direction of air flow through the air flow gap.

Abstract: A flow combiner is provided for a gas turbine engine. The flow combiner includes an outlet duct, a compressor bleed inlet duct coupled to the outlet duct, and a ventilation inlet duct coupled to the outlet duct. The compressor bleed inlet duct is configured to receive a bleed flow from a compressor of the gas turbine engine. The ventilation inlet duct is configured to receive a ventilation flow from an enclosure surrounding the gas turbine engine. The bleed flow and the ventilation flow are combined as an outlet flow through the outlet duct.

Abstract: An assembly is provided for an aircraft propulsion system. This assembly includes an exhaust center body and a duct system. The exhaust center body includes an exterior skin. The duct system is fluidly coupled with a plurality of exterior skin perforations in the exterior skin. The duct system is configured to direct bypass air received from a bypass flow path within the aircraft propulsion system to the exterior skin perforations.

Abstract: The present disclosure relates to the technical field of aerodynamic and acoustic measurement, in particular to a comprehensive performance test platform for acoustic liner. Based on this comprehensive performance test platform for acoustic liner, the stress of the measured acoustic liner under high sound intensity can be measured by using strain gauges arranged on the measured acoustic liner, the aerodynamic drag of the measured acoustic liner can be measured by using the drag balance, and the acoustic performance parameters of the measured acoustic liner can be calculated based on the sound pressure data obtained by the microphone array. With this test platform, the stress, the aerodynamic drag and the acoustic performance parameters of the measured acoustic liner can be measured simultaneously, which overcomes the problem of inaccurate experimental data obtained in inconsistent experimental conditions caused by conventional separate acoustic liner tests.

Abstract: A package-type compressor includes a body unit, a controller, a casing, a first cooling air inlet, a second cooling air inlet, a cooling air outlet, a fan duct, a cooling fan, an air cooling type heat exchanger, a machine chamber, and a cooling duct. The cooling duct is provided below the fan duct, the cooling duct causing the cooling air taken in at the second cooling air inlet to flow along the controller toward the suction port of the fan duct. A vertical projection plane of the cooling fan overlaps the machine chamber and the cooling duct.

Abstract: A sound damper and associated system are disclosed for damping sound. In embodiments, the sound damper is utilized within an automotive HVAC system. A passage wall defines an air passageway that transmits air. The sound damper includes a micro perforated panel (MPP) located within an opening formed into a passage wall. A back wall is spaced from the MPP, and a cavity is provided between the back wall and the MPP that is outside the air passageway. In embodiments, the MPP can be covered by a non-perforated film that is acoustically transparent and air impermeable.

Abstract: An active laminar flow control arrangement may comprise an outer skin having an inner surface, an outer surface, and a perforated area, and a panel coupled to the inner surface. The panel may comprise a longitudinal wall, a sidewall extending from the longitudinal wall, a ridge intersecting the sidewall, a cavity disposed in the panel and at least partially defined by the sidewall and the longitudinal wall, and a division wall disposed in the cavity and extending from the longitudinal wall, wherein the division wall divides the cavity into a first plenum and a second plenum. The longitudinal wall, the sidewall, the ridge, and the division wall may comprise a single, monolithic piece.

Abstract: A centrifugal blower having high efficiency and reduced noise is provided. A centrifugal blower to be accommodated in a housing having an air inlet includes a spiral casing having a bell mouth and a centrifugal fan housed in the casing. The bell mouth includes a first region and a second region. The first region is disposed closest to the air inlet. A distance from a rotational axis of the centrifugal fan to a downstream end in the first region is greater than a distance from the rotational axis to the downstream end in the second region. A curvature of a surface of the first region in a cross section including the rotational axis is smaller than a curvature of a surface of the second region in a cross section including the rotational axis.

Abstract: A method and apparatus for determining a direction of infrasound. Infrasound is received by a directional infrasound sensor comprising a plurality of channels and a plurality of sensor devices. Each channel in the plurality of channels comprises a single opening at a first end of the channel and a closed end opposite the opening. The opening of each channel in the plurality of channels is pointed in a different direction from the opening of each other channel in the plurality of channels. The plurality of sensor devices includes a sensor device at the closed end of each channel in the plurality of channels. Each sensor device in the plurality of sensor devices is configured to generate a sensor signal in response to pressure. The sensor signals generated by the plurality of sensor devices are processed to determine the direction of the infrasound received by the directional infrasound sensor.

Abstract: A high frequency attenuating device for an air flow induction system of a vehicle employing a thermoformed fibrous mat of any shape that fits robustly inside the duct. The dissipative nature of the fibrous mat helps in achieving broadband attenuation in the high frequency regime. The ability to manufacture the fibrous mat into any shape helps with restriction, targets different attenuation bands, and makes it more feasible to manufacture. Hybrid solutions are possible when combined with low frequency perforated silencers or high frequency QWT arrays injection molded onto them.

Abstract: A sound absorber includes a side surface section (a first wall section) in which a plurality of first holes are provided, the side surface section including a first surface and a second surface, a thin film stuck to the first surface of the side surface section, a partition wall (a second wall section) opposed to the second surface and provided in a position separated from the second surface, at least one second hole being provided in the partition wall, and a porous material provided to be opposed to the second wall section in a position separated from the partition wall.

Abstract: 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.

Abstract: A fan comprises a fan housing which includes a shroud having an upstream end that defines an inlet of the fan housing, a motor which is connected to the fan housing, and an impeller which is connected to the motor. The impeller includes an impeller hub and a number of impeller blades which extend radially outwardly from the impeller hub. The shroud includes a cylindrical micro-perforated panel (“MPP”) liner which extends axially from proximate the inlet to proximate the impeller.

Abstract: An airflow turning device with airflow control channels for an outlet of a heating, ventilation, and air conditioning (HVAC) case that directs airflow to a plurality of different vehicle outlets. The airflow control channels extend from an inner upstream side of the outlet to an outer downstream side of the outlet. Different ones of the plurality of channels have different lengths to generate a varied pressure drop at the outer downstream side in response to airflow blown into the plurality of channels from the inner upstream side.

Abstract: An inlet duct for an internal combustion engine includes a duct member made of a compression molded fiber material. The duct member includes a main body and end portions provided on opposite sides in an axial direction of the main body. The main body includes at least one high-compression portion and at least one low-compression portion, which is made through compression molding at a compression ratio lower than that of the at least one high-compression portion. The at least one low-compression portion extends throughout a length in the axial direction of the main body.

Abstract: A noise reducing structure includes a first resonance tube that extends in a first direction, that takes in from a sound absorbing opening portion a sound wave that is generated from a noise source, and that causes the sound wave to resonate to reduce leakage to outside; and a second resonance tube that extends in a second direction differing from the first direction, and that, along with the first resonance tube, causes the sound wave that is generated from the noise source to resonate to reduce the leakage to the outside.

Abstract: A soundproof structure includes two or more kinds of resonant type sound absorbing cells including different kinds of a first resonant type sound absorbing cell and a second resonant type sound absorbing cell that are adjacent to each other; and an opening part provided in the second resonant type sound absorbing cell, in which a resonance frequency of the first resonant type sound absorbing cell and a resonance frequency of the second resonant type sound absorbing cell match each other. As a result, the soundproof structure is capable of achieving an absorptance of more than 50%, preferably, close to 100% even in a compact, light, and thin structure which is much smaller than a wavelength, thereby obtaining a high soundproofing effect. Further, the soundproof structure is capable of obtaining air permeability and/or heat conductivity by providing a passage of air and/or heat.

Abstract: A pneumatic system includes a fluidic switching module having an air passage and a vent in fluid communication with the air passage. The pneumatic system also includes a sound attenuator coupled to the fluidic switching module, the sound attenuator having a first chamber in fluid communication with the vent, a first orifice in fluid communication with the vent via the first chamber, a second chamber in fluid communication with the first chamber via the first orifice, and a second orifice in fluid communication with the first orifice via the second chamber.

Abstract: Described is an acoustic absorbing structure and system provided from a composite material having one or more channels provided therein with each of the one or more channels having an aperture opening onto a surface of the composite material. The channels are provided having a cross-sectional shape and dimensions selected to exhibit a low frequency resonance in response to a low frequency sound wave provided thereto such that acoustic absorbing structure has a predetermined response characteristic in response to an acoustic signal provided thereto. Techniques for operating an acoustic absorbing system are also described.

Abstract: An exhaust assembly for use with a gas turbine engine includes an exhaust duct and a damper system coupled to the exhaust duct. The exhaust duct is configured for fluid communication with the gas turbine engine to receive hot exhaust gases produced by the gas turbine engine. The exhaust duct includes a plurality of panels that define an exhaust passageway. The damper system is coupled to one of the plurality of panels and is configured to dampen vibration of the exhaust duct during use of the gas turbine engine.

Abstract: An air cleaner of an internal combustion engine is provided with a first housing including an inlet, a second housing including an outlet, and a filter element located between the first housing and the second housing. A Helmholtz resonator is arranged inside the first housing. An upright wall projects from a bottom wall of the first housing toward the filter element and extends in an axial direction of the inlet. The upright wall forms a chamber of the Helmholtz resonator. A noise-absorption region is defined by the upright wall, a side wall of the first housing, the bottom wall, and the filter element. The noise-absorption region leads to the inlet and extends in the axial direction.

Abstract: A fan includes a frame, a first impeller, a motor, a base, and a noise silencer. The frame is provided with a flow channel for air to flow through. The first impeller is disposed in the frame. The motor connects with and drives the first impeller to rotate. The base is disposed in the frame and supports the motor. The noise silencer is located adjacent to the flow channel. The noise silencer includes at least one hollow chamber, and the hollow chamber has at least one hole communicating with the flow channel.

Abstract: An air conditioner and a control method thereof perform cooling through an outlet if room temperature or room humidity is high to reduce the room temperature or the room humidity, and closing the outlet to perform cooling at low velocity through an outlet hole if room temperature or room humidity reaches a predetermined value so that a user can little feel the wind velocity of cooling of the air conditioner, while maintaining indoor space at pleasant temperature or humidity. By performing cooling at low velocity through the outlet hole formed in the lower portion of the air conditioner, it is possible to cool the lower area of indoor space at pleasant temperature when a user is asleep.

Abstract: Systems and methods are directed to an air handler that reduces noise without reducing the pressure of air supplied to a space below minimum levels. The air handler includes a plenum forming a passageway for air. The plenum has a return side, a supply side, a fan within the plenum having a suction side and a pressure side to move air through the plenum, and a conditioning apparatus in the plenum for conditioning air through the plenum. The air handler further includes a sound-attenuating panel having a first side and an opposed second side that extend at least partially across the plenum. The panel is configured and positioned to interact with the flow of air to attenuate sound. The fan provides a pressure boost to air flowing through the plenum to counteract a pressure drop resulting from interaction between the air, the panel, and the conditioning apparatus.

Abstract: An acoustic attenuation assembly includes a low frequency sound attenuation device having at least one sound attenuation chamber containing a volume and mass of air. First and second openings are associated with each low frequency chamber through which excited air resonates. The first and second openings extend through the first sheet into each low frequency chamber. Each chamber has an open side. A high frequency sound attenuation device is secured to the low frequency attenuation device and closes the open side of each chamber. The high frequency sound attenuation device includes a plurality of projections formed from a sound absorbing material that absorbs excited air.

Abstract: There is provided a soundproof structure having two or more soundproof units. Each soundproof unit has a frame having an opening portion and a sound absorbing member attached to the opening portion of the frame. Two adjacent soundproof units are disposed such that at least parts of the sound absorbing members face each other. The sound absorbing members at least parts of which face each other are spaced apart from each other. An average distance between the sound absorbing members at least parts of which face each other is less than 20 mm. Therefore, it is possible to provide a soundproof structure and a soundproof system that can soundproof low frequency side sound with a simple configuration, is small and lightweight, and can easily change its frequency characteristics.

Abstract: An apparatus includes a housing, one or more storage drives, one or more fans, and one or more acoustic barriers. The housing includes a bottom side bounded by a front side, a back side, a first side, and a second side opposite the first side. The housing may further include a top cover removably attached to the housing. The storage drives may be disposed within the housing at a first location. The fans may be disposed within the housing at a second location spaced from the first location. The fans may generate a flow of air through the housing, while simultaneously generating sound waves that travel throughout the housing. The acoustic barriers may be disposed between the storage drives and the fans, and configured to attenuate the sounds waves prior to the sound waves reaching the storage drives in order to reduce the throughput performance degradation of the drives.

Abstract: This technology provides a splitter comprising: a first sound absorber; a second sound absorber; a perforated plate member interposed between the first sound absorber and the second sound absorber; and an outer frame surrounding the first sound absorber, the second sound absorber and the perforated plate member; and a sound attenuator comprising: a protective case; a plurality of splitters according to above embodiment formed in the protective case and spaced from each other; and an air passage formed among the plurality of splitters.

Abstract: Methods, systems and apparatuses configured to isolate and/or damp vibration of refrigerant lines caused by, for example, the compressor are disclosed. A vibration control device can be configured hold a refrigerant line at a position that is away from the compressor. The vibration control device can help isolate the vibration, reducing or preventing the vibration from passing the vibration control device along the refrigerant line. A vibration-damping device can be configured to engage the refrigerant line so as to absorb/damp the vibration of the refrigerant line.

Abstract: A Sodar apparatus is disclosed for sounding the atmosphere. The apparatus includes a transducer for converting an electrical signal to an acoustic wave and/or vice-versa and transferring means associated with the transducer for transferring the acoustic wave towards the atmosphere and/or for transferring a reflected acoustic wave from the atmosphere. The apparatus further includes isolating means or structure for isolating or attenuating the acoustic wave such that energy of the acoustic wave transferred in a substantially horizontal direction is reduced below energy of the acoustic wave transferred in a substantially vertical direction by a factor of at least 45 dB and more preferably by a factor of at least 70 dB. A method for sounding the atmosphere is also disclosed.

Abstract: A variable refrigerant package air conditioner is shown that is easy to install in new construction with a unique base that causes collected mixture that overflows to drain outside the building. A control system is shown that has motors and compressor that are pulse width modulated so the air conditioner is infinitely variable while maintaining the highest possible power factor. Dehumidification of outside air occurs as it is mixed with inside air. By gradually approaching a temperature set point and even reheating after dehumidification, moisture is removed from the room. A snorkel that delivers fresh air to be mixed with inside entering air in front of the evaporator for a maximum dehumidification is also shown.

Abstract: An enclosure for a generator includes an air inlet formed at a first end of the enclosure, and an air inlet opening formed in a sidewall of the enclosure. The air inlet includes an air inlet duct formed in an interior space of the enclosure, and in fluid communication with the air inlet opening. The air inlet duct receives the airflow from the air inlet opening to direct the airflow towards an air outlet of the enclosure. The air outlet includes an air outlet duct formed at a second end of the enclosure which receives the airflow from the air inlet opening. The air outlet duct directs the airflow towards an air outlet opening formed in a top plate of the enclosure which provides an exit for the airflow to escape from the interior space to an ambient environment of the enclosure.

Abstract: An air flow mixer that mixes two or more air streams that may enter air moving equipment at significantly different temperatures. In particular, methods, systems and apparatuses are disclosed that are directed to an air flow mixer that is structured and arranged to promote cross flow of portions of the air streams relative to each other through the air flow mixer. The cross flow resulting from the structure and arrangement of the air flow mixer avoids sharp delineations or fluid borders between the air streams that can be caused, for example, by a relatively higher temperature of one of the air streams and a relatively lower temperature of another one of the air streams.

Abstract: A noise suppression system for an electric generator having a housing including an internal combustion engine and air-cooled alternator. A fan draws ambient cooling air into the housing for cooling the alternator. The system may include an acoustically designed noise suppression shroud forming a cavity which contains a plurality of parallel flow baffles. The baffles define air flow passages there-between which receive cooling air heated by the alternator. In one system, the baffles are configured and arranged to block a straight line of sight between the entrance and exit of each passage. The baffles may each further include sound deadening materials on one or both sides in some configurations. Heated cooling air flows into the shroud and through the passages before being discharged from the housing. The shroud is operable to suppress noise produced by the cooling air discharge flow. Various shroud configurations may include additional sound proofing features.

Abstract: A sound attenuating baffle mounts within the duct section of an air distribution HVAC system, a ventilation system, or other air movement system for either air or gas streams, in which the duct section can be mounted directly to a fan or incorporated into a transmission duct. The sound attenuating baffle is typically oriented in the flow direction through the duct, and includes an outer casing containing sound absorbing material therein. An internal mass layer formed of a sound barrier material is suspended within the sound absorbing material which fills the outer casing. The mass layer increases the low frequency sound attenuation of the sound attenuating baffle.

Abstract: A method is provided that includes: weaving one first portion including warp and weft threads intertwined according to the fundamental weave of each portion of woven wall corresponding to this first portion, stopping introduction of weft threads after insertion of a weft thread associated with the positioning of one elongated element having a main axis, the weft thread being intertwined with the warp threads of each portion of woven wall, introducing each elongated element between the warp threads defining with the associated weft thread, the insertion position of this elongated element, and maintaining in position each elongated element and introducing one new weft thread intertwining warp threads of the structure according to the fundamental weave of each wall portion or according to at least one new weave, to resume production of the structure, with each elongated element not being taken in the structure.

Abstract: A signal processing device includes a coefficient updater configured to calculate a filter coefficient based on a reference signal, an error signal, and an update parameter to set the filter coefficient in a noise cancelling filter. A parameter adjuster adjusts the update parameter according to fluctuation of the reference signal produced from an output of a reference microphone.