Abstract: A heating circuit has at least three series-connected resistance-heating elements, each resistance-heating element being connected between a pair of nodes, each pair of adjacent resistance-heating elements in the series being connected via one of the nodes, each node being connectable to a voltage. Optionally, the heating circuit may have one or more switching elements to allow selective connection of one or more voltages to the resistance heating elements.

Abstract: Waste water assessment apparatus, a method and a computer program are provided. The waste water assessment apparatus comprises: transceiver circuitry configured to transmit a microwave signal and to receive one or more reflections of the microwave signal; and processing circuitry configured to process the one or more reflections of the microwave signal to determine one or more characteristics of waste water flowing through a conduit.

Abstract: Waste water flow quantifying apparatus, a method and a computer program is provided. The waste water flow quantifying apparatus comprises microwave transceiver circuitry configured to transmit a first microwave signal into a closed conduit and configured to receive a first superposition microwave signal formed from a combination of the first microwave signal and a reflection, from within the closed conduit, of the first microwave signal. The microwave transceiver circuitry is configured to transmit a second microwave signal into the closed conduit. The second microwave signal has a different frequency from the first microwave signal or is out of phase with the first microwave signal. The microwave transceiver circuitry is configured to receive a second superposition microwave signal formed from a combination of the second microwave signal and a reflection, from within the closed conduit, of the second microwave signal.

Abstract: Waste water assessment apparatus, a method and a computer program are provided. The waste water assessment apparatus comprises: transceiver circuitry configured to transmit a microwave signal and to receive one or more reflections of the microwave signal; and processing circuitry configured to process the one or more reflections of the microwave signal to determine one or more characteristics of waste water flowing through a conduit.

Abstract: Waste water assessment apparatus, a method and a computer program are provided. The waste water assessment apparatus comprises: transceiver circuitry configured to transmit a microwave signal and to receive one or more reflections of the microwave signal; and processing circuitry configured to process the one or more reflections of the microwave signal to determine one or more characteristics of waste water flowing through a conduit.

Abstract: Waste water assessment apparatus, a method and a computer program are provided. The waste water assessment apparatus comprises: transceiver circuitry configured to transmit a microwave signal and to receive one or more reflections of the microwave signal; and processing circuitry configured to process the one or more reflections of the microwave signal to determine one or more characteristics of waste water flowing through a conduit.

Abstract: A controller for a high-frequency agitation source includes a signal generator to generate a drive signal having a variable duty cycle. The drive signal is used to drive the high-frequency agitation source. The controller also includes a temperature detector to detect the temperature of the high-frequency agitation source. The controller is configured to vary the duty cycle of the drive signal in response to the temperature of the high-frequency agitation source. By varying the duty cycle of the drive signal, the average power supplied to the piezoelectric crystal can be varied while still maintaining a fixed amplitude of oscillation. This allows the temperature of a high-frequency agitator, for example, a piezoelectric crystal, to be controlled.

Abstract: The invention relates to a system for transferring a liquid consumable product, such as milk, from a bulk storage tank to a transport vehicle receiving tank or from one bulk tank to another whether stationary or mobile. The system increases the efficiency with which the milk is transferred from the bulk tank to the transport vehicle by providing a centrifugal pump permanently positioned on the milk producer's premises proximal the bulk tank. The system includes an air-purge system for removing any residual milk from the pump and transfer lines once pumping has ceased, as well as a wash system for cleaning the pump system components after use. In addition to transferring milk from the bulk tank to the transport truck, the centrifugal pump is conveniently adaptable for use in the washing operations, thereby adding to the efficiency of the overall system.

Abstract: A controller for a high-frequency agitation source includes a signal generator to generate a drive signal having a variable duty cycle. The drive signal is used to drive the high-frequency agitation source. The controller also includes a temperature detector to detect the temperature of the high-frequency agitation source. The controller is configured to vary the duty cycle of the drive signal in response to the temperature of the high-frequency agitation source. By varying the duty cycle of the drive signal, the average power supplied to the piezoelectric crystal can be varied while still maintaining a fixed amplitude of oscillation. This allows the temperature of a high-frequency agitator, for example, a piezoelectric crystal, to be controlled.

Abstract: A parametric loudspeaker system using improved modulators to compensate for the non-linearity of the parametric process in air when driving the air at saturation levels and below saturation levels. The parametric loudspeaker uses a pre-processed single sideband modulator that offers ideal linearity as characterized by square root pre-processed double sideband modulators but with a lower carrier frequency and without the wide bandwidth requirements. By eliminating some or all of the lower sideband the carrier frequency can be reduced without producing sideband frequencies in the audible range. Lower operational frequencies result in greater translation efficiency and greater output capability before reaching the saturation limit of air. A pre-processor minimizes the effects of saturation limits for double sideband, truncated double sideband or single sideband processing to achieve superior output.

Abstract: A virtual headset for enabling isolated listening to audio material by a listener without need for earphones or other physical audio producing devices attached to the listener. The virtual headset includes a parametric ultrasonic signal source 504 supplying at least a first parametric ultrasonic channel signal comprised of an ultrasonic carrier signal and at least one sideband, and configured to be emitted and directed substantially exclusively at a first ear 506 of the listener 502. The parametric ultrasonic signal source is coupled to an electro-acoustical emitter structure, which is configured to emit and direct a first parametric ultrasonic wave corresponding to the first parametric ultrasonic channel signal at the listener such that a first resultant decoupled audio wave will be heard substantially exclusively at the first ear of the listener, with minimal audible sound at a second ear 514 of the listener.

Abstract: A substantially single-ended planar-magnetic transducer comprises a thin film, diaphragm having a first surface side and a second surface side and including a conductive surface area for converting an input electrical signal into a corresponding acoustic output, said at least one diaphragm including a predetermined active region. A high energy magnetic structure has sufficient magnetic field strength and is configured with respect to the diaphragm to drive the diaphragm as a substantially single-ended audio transducer. Mounting structure is coupled to the diaphragm to hold the diaphragm in a predetermined state of tension and at a predetermined distance from the high energy magnetic structure over an extended period of time including periods of use and nonuse. The diaphragm provides improved performance characteristics by using a polyethylenenaphthalate film as a base material for the diaphragm.

Abstract: A bandpass loudspeaker enclosure having three sub chambers, a first subchamber being a Helmholtz-reflex chamber with a passive acoustic radiator operating in parallel with the transducer, and the remaining two chambers utilizing two passive acoustic radiators to achieve three Helmholtz-reflex vent tunings and a multiple of low pass acoustic filters that provide an acoustic bandpass with reduced diaphragm displacement and substantially reduced distortion and pipe resonances above the pass band. A further embodiment provides a reduced lowest frequency vent size for a given low frequency subchamber size and tuning frequency.

Abstract: A system for providing audio information to persons in an approach path (12) includes an interaction point (14), and an approach path (12) leading to the interaction point. A parametric sound system (18) is provided, which includes a parametric speaker (20) disposed adjacent to the interaction point. The parametric sound system is configured for limited delivery of sound in a spatially limited audio zone (24) along the approach path (12), within a decibel level above ambient noise levels in the area of the interaction point (14), and sufficiently high to be heard primarily by a person progressing along the approach path (12). The interaction point can be a cashier station, and the system can also include a video display (16) configured to provide video information to persons in the approach path along with the audio information.

Abstract: A system and method is disclosed for a parametric emitter array with enhanced emitter-to-air acoustic coupling. The system comprises a plate support member having opposing first and second faces separated by an intermediate plate body. The plate body can have a plurality of conduits configured as an array of acoustic horns. Each horn can have a small throat opening at the first face and an intermediate horn section which diverges to a broad mouth opening at the second face. An emitter membrane can be positioned in direct contact with the first face and extending across the small throat openings. The emitter membrane can be biased by (i) applying tension to the emitter membrane extending across the throat openings, (ii) displacing the emitter membrane into a non-planar configuration, and (iii) capturing the emitter membrane at the first face using an adhesive substance.

Abstract: A planar magnetic transducer having enhanced magnetic structures which increases performance over a signal-ended device but mitigates some of the drawback of double ended devices, including a supporting structure, a diaphragm incorporating a coil conductor at least primary magnetic structure, and a secondary magnetic structure can be added, including mitigation of high frequency resonance and attenuation by providing a more open architecture, including spacing the magnets wider apart, configuring the inter-magnet spaces to provide better acoustic performance, using high-energy magnets, which magnets can be shaped to form at least a part of the shaped inter-magnet space.

Abstract: A compact lightweight electro-acoustic transducer system for generating high intensity, highly directional audio output. The transducer system can generate acoustic intensity levels that can drive the transmission medium to non-linearity such that highly directional secondary sound also can appear in the audible range allowing direct and parametric sound generation from a single acoustic emission system. The device can be used for both distant and/or high intensity communications to convey information, provide high intensity acoustical targeting and/or disrupt or mask other communications.

Abstract: A parametric loudspeaker system and method for reducing distortion in a decoupled audio wave by creating a double sideband parametric ultrasonic signal that substantially approximates a non-square-rooted modulation envelope and emitting a parametric ultrasonic wave that corresponds to the double sideband parametric ultrasonic signal from a parametric loudspeaker at a sufficient amplitude to drive the surrounding air into saturation.

Abstract: A method is disclosed for generating parametric audio output based on the interaction of multiple ultrasonic outputs within air as a nonlinear medium. The method includes the step of generating an electronic signal comprising at least two ultrasonic signals having a difference in value which falls within an audio frequency range. The electronic signal can be transferred to an electrostatic emitter diaphragm which couples directly with the air as part of a single stage energy conversion process. The electronic signal can be converted at the diaphragm directly to a mechanical displacement as a driver member of a parametric speaker. The ultrasonic signals can be mechanically emitted from the diaphragm into the air as ultrasonic compression waves which interact within the air to generate the parametric audio output.

Abstract: A sound emitting device (10) for providing at least one new sonic or subsonic frequency as a by-product of emitting a waveform of at least two ultrasonic frequencies whose difference in value corresponds to the desired new sonic or subsonic frequency. The device includes a parametric emitting perimeter or plurality of emitter segments (13) positioned around a central open section (15). This open section (15) is structured with a diagonal width greater than a cross-sectional diagonal of the parametric emitting perimeter. An ultrasonic frequency source (60) and sonic/subsonic frequency generator (62) arc coupled together to a modulating circuit (61) for mixing an ultrasonic frequency signal with an electrical signal corresponding to the at least one new sonic or subsonic frequency.