Abstract: Embodiments of the present disclosure help to increase the reliability of differential static pressure sensor readings used to remotely monitor the performance of an HVAC air filter. Embodiments of the present disclosure solve two problems, one related to degraded reliability of a differential pressure sensor and the second due to airflow properties such as turbulence impacting the accuracy and repeatability of differential pressure readings. Sensor reliability and lifetime are improved by reducing the access to and accumulation of dust at the sensor element by design of the air column to the sensor. The loss of accuracy and repeatability of sensor readings produced by properties of the airflow such as turbulence, among others, is reduced by a design and placement of a manifold that extends into the incoming air flow from the filter frame.

Abstract: A device for collecting and distributing material into a receptacle having a receptacle curvature includes: a tapered wall; and a tamping flange adjoining the tapered wall. The tapered wall has a tapered wall curvature that approximates the receptacle curvature. The tamping flange is configured to compact the material into the receptacle.

Abstract: An apparatus, system and method are provided for testing a battery-powered electronic device-under-test in a transport frame engaged with a test fixture. A transport frame power supply is arranged to provide power to the DUT in a pre-testing stage. A switching circuit is arranged to switch from the transport frame power supply to a test fixture power supply in response to receiving a power switching signal indicating satisfaction of a pre-testing condition. Power from the test fixture power supply can then be switched back to the first transport frame, or to a second transport frame, to begin testing a second DUT. The ability to start a DUT test without having to wait for the DUT to boot-up in the test fixture reduces test time and increases efficiency of use of test equipment.

Abstract: A loudspeaker comprising a horn waveguide having a throat and a waveguide surface; an acoustic radiator assembly, located at the throat of the waveguide, comprising a diaphragm having a rigid acoustically radiating surface shaped as a section from a toroidal surface for generating acoustic wavefronts, the waveguide surface being adapted to match the shape of the wavefronts coming from the assembly.

Abstract: An apparatus, system and method are provided for testing a battery-powered electronic device-under-test in a transport frame engaged with a test fixture. A transport frame power supply is arranged to provide power to the DUT in a pre-testing stage. A switching circuit is arranged to switch from the transport frame power supply to a test fixture power supply in response to receiving a power switching signal indicating satisfaction of a pre-testing condition. Power from the test fixture power supply can then be switched back to the first transport frame, or to a second transport frame, to begin testing a second DUT. The ability to start a DUT test without having to wait for the DUT to boot-up in the test fixture reduces test time and increases efficiency of use of test equipment.

Abstract: An electro-acoustic transducer with a front part having an acoustically radiating surface, a supporting part that supports the front part and that extends from a peripheral region of the front part in a direction away from the acoustically radiating surface, and a reinforcing part that provides rigidity to the transducer. The reinforcing part extends from the supporting part to the front part such that a portion of the reinforcing part is spaced from the front part and/or the supporting part.

Abstract: A phase plug comprises a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body. The input side comprises an input surface which includes a plurality of slots constituting entrances for the channels, each slot being arranged in a substantially radial orientation on the input surface about a central axis extending through the input surface. Substantially the entire input surface situated between the slots is concave and substantially part of a sphere or an ellipsoid in shape.

Abstract: A phase plug comprises a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body. The input side comprises an input surface which includes a plurality of openings constituting entrances for the channels, the input surface being substantially part of a sphere or an ellipsoid in shape. The areas of the openings vary with radial position on the input surface, the radial position being measured in a direction extending perpendicularly from a central axis extending through the input surface. The variation in the areas is a function of the cosine of an angle subtended at the centre of the sphere or a focus of the ellipsoid between the central axis and the radial position.

Abstract: A loudspeaker comprises a horn waveguide having a waveguide surface, and a transducer located in, or adjacent to, a throat of the horn waveguide. The transducer has a substantially rigid convex dome-shaped acoustically radiating surface. A horn angle subtended between a longitudinal axis of the horn waveguide and the waveguide surface at the throat of the horn, is in the range 20 to 60 degrees. An intersection angle subtended between a plane tangential to the dome shape of the acoustically radiating surface and a plane tangential to the waveguide surface at a point where the dome shape or an extrapolation of the dome shape meets the waveguide surface or an extrapolation of the waveguide surface, is in the range 85 to 110 degrees.

Abstract: A loudspeaker comprising a horn waveguide having a throat and a waveguide surface; an acoustic radiator assembly, located at the throat of the waveguide, comprising a diaphragm having a rigid acoustically radiating surface shaped as a section from a toroidal surface for generating acoustic wavefronts, the waveguide surface being adapted to match the shape of the wavefronts coming from the assembly.

Abstract: An apparatus, system and method are provided for testing a battery-powered electronic device-under-test in a transport frame engaged with a test fixture. A transport frame power supply is arranged to provide power to the DUT in a pre-testing stage. A switching circuit is arranged to switch from the transport frame power supply to a test fixture power supply in response to receiving a power switching signal indicating satisfaction of a pre-testing condition. Power from the test fixture power supply can then be switched back to the first transport frame, or to a second transport frame, to begin testing a second DUT. The ability to start a DUT test without having to wait for the DUT to boot-up in the test fixture reduces test time and increases efficiency of use of test equipment.

Abstract: A phase plug comprises a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body. The input side comprises an input surface which includes a plurality of slots constituting entrances for the channels, each slot being arranged in a substantially radial orientation on the input surface about a central axis extending through the input surface. Substantially the entire input surface situated between the slots is concave and substantially part of a sphere or an ellipsoid in shape.

Abstract: A phase plug comprises a body having an input side for receiving acoustic waves and an output side for transmitting acoustic waves, the body including a plurality of channels extending from the input side to the output side for propagating acoustic waves through the body. The input side comprises an input surface which includes a plurality of openings constituting entrances for the channels, the input surface being substantially part of a sphere or an ellipsoid in shape. The areas of the openings vary with radial position on the input surface, the radial position being measured in a direction extending perpendicularly from a central axis extending through the input surface. The variation in the areas is a function of the cosine of an angle subtended at the centre of the sphere or a focus of the ellipsoid between the central axis and the radial position.

Abstract: A loudspeaker comprises a horn waveguide having a waveguide surface, and a transducer located in, or adjacent to, a throat of the horn waveguide. The transducer has a substantially rigid convex dome-shaped acoustically radiating surface. A horn angle subtended between a longitudinal axis of the horn waveguide and the waveguide surface at the throat of the horn, is in the range 20 to 60 degrees. An intersection angle subtended between a plane tangential to the dome shape of the acoustically radiating surface and a plane tangential to the waveguide surface at a point where the dome shape or an extrapolation of the dome shape meets the waveguide surface or an extrapolation of the waveguide surface, is in the range 85 to 110 degrees.

Abstract: An electro-acoustic transducer comprises a front part having an acoustically radiating surface, a supporting part that supports the front part and that extends from a peripheral region of the front part in a direction away from the acoustically radiating surface, and a reinforcing part that provides rigidity to the transducer. The reinforcing part extends from the supporting part to the front part such that a portion of the reinforcing part is spaced from the front part and/or the supporting part.

Abstract: A protective guard for reducing injury to a shin of a person is provided. The protective guard includes an elastomeric substrate having a pocket disposed therein. A central core is carried by the pocket of the elastomeric substrate. The central core includes a plurality of rigid plates, a first of which is joined by at least one hinge to a second of the plates.

Abstract: A loudspeaker or other enclosure 10 constituting a humidity sensitive region the moisture of which is to be reduced contains a heater 18A. The tube 12 having a bore narrow enough to prevent diffusion of gases therethrough leads from the enclosure 10. The heater is operated cyclically by a switching circuit 19 to heat the interior of the enclosure to expel moist air through the tube 12 and thereby control the humidity of the air in the enclosure. A dessicant 16 may be provided in the tube 12. A heater 18B may be provided in the tube instead of in the enclosure.

Abstract: A drive assembly for a loudspeaker comprises a permanent magnet (42) and pole pieces (44a, 44b, 44c, 44d, 4e, 44f, 44g, 44h, 46a, 46b, 46c, 46d) of ferromagnetic material. The pole pieces define an air gap (43) in which a coil formed from windings (40a, 40b) on a former (41) is movable. The shaping of the pole pieces to form air-filled recesses extending to the air gap has the result that the path of the magnetic flux of the permanent magnet is split in the region of the gap and the magnetic permeability of the path of the magnetic flux of the secondary magnetic field induced in the coil upon energisation thereof is reduced. The effect of the secondary field is thereby also reduced and a particularly linear response and a reduction in harmonic distortion can thereby be achieved.

Abstract: A hydraulic valve assembly for selectably delivering hydraulic fluid from a supply of hydraulic fluid to one of a first hydraulic operator and a second hydraulic operator is disclosed. The assembly includes first and second supply ports which communicate with the supply and four operator ports. First and third ports communicate with the first hydraulic operator. Second and fourth ports communicate with the fourth hydraulic operator. First and second chambers are provided. The first chamber communicates with the first supply port and first and second operator ports. The second chamber communicates with the second supply port and third and fourth operator ports. Two selection valves operating in unison are each located in each chamber. The selection valves operate between a first position at a first hydraulic fluid pressure and a second position at a second hydraulic fluid pressure.