Abstract: The present disclosure relates to Class D amplifier circuitry comprising: an input for receiving an input signal; first and second output nodes for driving a load connected between the first and second output nodes. A first driver stage is provided for switching the first node between a first supply rail and a second supply rail, and a second driver stage is provided for switching the second node between the first supply rail and the second supply rail. The Class D amplifier circuitry also includes first driver control circuitry configured to receive a first carrier wave and control the switching of the first driver stage based in part on the first carrier wave; second driver control circuitry configured to receive a second carrier wave and control the switching of the second driver stage based in part on the second carrier wave; and a carrier wave generator configured to provide the first carrier wave and the second carrier wave.

Abstract: This application relates to digital PWM modulation. A PWM modulator (400, 1100) has a PWM generator (402) configured to receive pulse width data (PWidth) and to output a PWM signal (SPWM) comprising a plurality of repeating PWM cycle periods, in which the duration of any pulse of the PWM signal in each PWM cycle period is based on the pulse width data. The PWM generator is configured to synchronise the PWM cycle periods, and the start and end of any PWM pulse, to a received first clock signal. The PWM generator is operable to generate pulses that have a positional error from a centred position within the PWM cycle period and a pulse position controller (403) is configured to control the position of a pulse in a PWM cycle period so as to at least partly compensate for the positional error of one or more preceding pulses.

Abstract: A water-soluble metal working oil agent which can be prevented from being scattered in the form of mists for a long period when used for the cutting processing, grinding processing and the like of metallic materials is provided. A method for producing the water-soluble metal working oil agent is described. The water-soluble metal working oil agent includes a polyalkylene oxide having a weight average molecular weight of 100,000 to 1,000,000 and water.

Abstract: The present disclosure relates to Class D amplifier circuitry comprising: an input for receiving an input signal; first and second output nodes for driving a load connected between the first and second output nodes. A first driver stage is provided for switching the first node between a first supply rail and a second supply rail, and a second driver stage is provided for switching the second node between the first supply rail and the second supply rail. The Class D amplifier circuitry also includes first driver control circuitry configured to receive a first carrier wave and control the switching of the first driver stage based in part on the first carrier wave; second driver control circuitry configured to receive a second carrier wave and control the switching of the second driver stage based in part on the second carrier wave; and a carrier wave generator configured to provide the first carrier wave and the second carrier wave.

Abstract: This application relates to digital PWM modulation. A PWM modulator (400, 1100) has a PWM generator (402) configured to receive pulse width data (PWidth) and to output a PWM signal (SPWM) comprising a plurality of repeating PWM cycle periods, in which the duration of any pulse of the PWM signal in each PWM cycle period is based on the pulse width data. The PWM generator is configured to synchronise the PWM cycle periods, and the start and end of any PWM pulse, to a received first clock signal. The PWM generator is operable to generate pulses that have a positional error from a centred position within the PWM cycle period and a pulse position controller (403) is configured to control the position of a pulse in a PWM cycle period so as to at least partly compensate for the positional error of one or more preceding pulses.

Abstract: This application relates to Class D amplifier circuits. A modulator controls a Class D output stage based on a modulator input signal (Dm) to generate an output signal (Vout) which is representative of an input signal (Din). An error block, which may comprise an ADC, generates an error signal (?) from the output signal and the input signal. In various embodiments the extent to which the error signal (?) contributes to the modulator input signal (Dm) is variable based on an indication of the amplitude of the input signal (Din). The error signal may be received at a first input of a signal selector block. The input signal may be received at a second input of the signal selector block. The signal selector block may be operable in first and second modes of operation, wherein in the first mode the modulator input signal is based at least in part on the error signal; and in the second mode the modulator input signal is based on the digital input signal and is independent of the error signal.

Abstract: The present disclosure relates to Class D amplifier circuitry comprising: an input for receiving an input signal; first and second output nodes for driving a load connected between the first and second output nodes. A first driver stage is provided for switching the first node between a first supply rail and a second supply rail, and a second driver stage is provided for switching the second node between the first supply rail and the second supply rail. The Class D amplifier circuitry also includes first driver control circuitry configured to receive a first carrier wave and control the switching of the first driver stage based in part on the first carrier wave; second driver control circuitry configured to receive a second carrier wave and control the switching of the second driver stage based in part on the second carrier wave; and a carrier wave generator configured to provide the first carrier wave and the second carrier wave.

Abstract: This application relates to Class D amplifier circuits (200). A modulator (201) controls a Class D output stage (202) based on a modulator input signal (Dm) to generate an output signal (Vout) which is representative of an input signal (Din). An error block (205), which may comprise an ADC (207), generates an error signal (?) from the output signal and the input signal. In various embodiments the extent to which the error signal (?) contributes to the modulator input signal (Dm) is variable based on an indication of the amplitude of the input signal (Din). The error signal may be received at a first input (204) of a signal selector block (203). The input signal may be received at a second input (206) of the signal selector block (203).

Abstract: This application relates to methods and apparatus for amplification of audio signals with improved audio performance. An audio driving circuit has an amplifier module in a forward signal path between an input for receiving an input audio signal (SIN) and an output for outputting an audio driving signal (VOUT). A pre-distortion module is operable to apply a first transfer function to the signal in the forward signal path upstream of the amplifier module, wherein the first transfer function comprises a non-linear distortion function based on at least one distortion setting. An error block is arranged to receive a first signal (SFF) derived from the input signal and a second signal (SFB) indicative of the voltage of the audio driving signal and determine a first error signal (?1) indicative of a difference between the first and second signals. The pre-distortion module is operable to control the distortion setting(s) based on the first error signal.

Abstract: The invention provides a drag reducer having an excellent frictional drag-reducing effect on an aqueous medium and the like and also provides a fire-extinguishing agent including this drag reducer. The drag reducer according to the present invention includes a polyalkylene oxide aqueous dispersion that includes a polyalkylene oxide, aluminum oxide, an electrolyte, and water, and that has the polyalkylene oxide dispersed therein. The drag reducer has an excellent frictional drag-reducing effect on an aqueous medium and the like.

Abstract: Provided is a method to produce an alkylene oxide polymer having a high polymerization degree on an industrial scale and with high reproducibility. The method includes the step of carrying out a polymerization reaction of an alkylene oxide in an inert hydrocarbon solvent in the presence of a zinc catalyst to produce an alkylene oxide polymer. The zinc catalyst is produced by reaction of an organozinc compound with a monohydric alcohol in an amount of 12-fold equivalent or less relative to the amount of the organozinc compound and an aliphatic polyhydric alcohol in an amount of 0.2- to 1.1-fold equivalent relative to the amount of the organozinc compound. The polymerization reaction is carried out under such a condition that the amount of the monohydric alcohol in the polymerization reaction system becomes 0.01-fold equivalent or less relative to the amount of the organozinc compound.

Abstract: This application relates to digital PWM modulation. A PWM modulator (400, 1100) has a PWM generator (402) configured to receive pulse width data (PWidth) and to output a PWM signal (SPWM) comprising a plurality of repeating PWM cycle periods, in which the duration of any pulse of the PWM signal in each PWM cycle period is based on the pulse width data. The PWM generator is configured to synchronise the PWM cycle periods, and the start and end of any PWM pulse, to a received first clock signal. The PWM generator is operable to generate pulses that have a positional error from a centred position within the PWM cycle period and a pulse position controller (403) is configured to control the position of a pulse in a PWM cycle period so as to at least partly compensate for the positional error of one or more preceding pulses.

Abstract: A fracturing fluid viscosity-controlling agent maintains the high viscosity of the fracturing fluid during fracture formation in hydraulic fracturing and reduces the viscosity during recovery of the fracturing fluid. A fracturing fluid which includes the viscosity-controlling agent is provided as well as a crude oil or natural gas drilling method using the fracturing fluid with the viscosity-controlling agent. This viscosity-controlling agent contains polyalkylene oxide and a viscosity-reducing agent and is in the form of a tablet.

Abstract: Methods and apparatus for Class-D amplifier circuits with improved power efficiency. The circuit has an output stage with at least first and second switches and a modulator that receives an input signal to be amplified, SIN, and a first clock signal fSW. The modulator controls the duty cycles of the first and second switches, within a switching cycle based on the input signal, wherein the switching cycle has a switching frequency based on the first clock signal. A frequency controller controls the frequency of the first clock signal in response to an indication of the amplitude of the input signal so as to provide a first switching frequency at a first input signal amplitude and a second, lower, switching frequency at a second, lower, input signal amplitude. A lower switching frequency can be tolerated at low signal amplitudes and varying the switching frequency in this way thus maintains stability whilst reducing switching power losses.

Abstract: This application relates to methods and apparatus for amplification of audio signals with improved audio performance. An audio driving circuit (200) has an amplifier module (102) in a forward signal path between an input (103) for receiving an input audio signal (SIN) and an output for outputting an audio driving signal (VOUT). A pre-distortion module (202) is operable to apply a first transfer function to the signal in the forward signal path upstream of the amplifier module, wherein the first transfer function comprises a non-linear distortion function based on at least one distortion setting. An error block (203) is arranged to receive a first signal (SFF) derived from the input signal and a second signal (SFB) indicative of the voltage of the audio driving signal and determine a first error signal (?1) indicative of a difference between the first and second signals. The pre-distortion module (202) is operable to control the distortion setting(s) based on the first error signal.

Abstract: Provided is a method to produce an alkylene oxide polymer having a high polymerization degree on an industrial scale and with high reproducibility. The method includes the step of carrying out a polymerization reaction of an alkylene oxide in an inert hydrocarbon solvent in the presence of a zinc catalyst to produce an alkylene oxide polymer. The zinc catalyst is produced by reaction of an organozinc compound with a monohydric alcohol in an amount of 12-fold equivalent or less relative to the amount of the organozinc compound and an aliphatic polyhydric alcohol in an amount of 0.2- to 1.1-fold equivalent relative to the amount of the organozinc compound. The polymerization reaction is carried out under such a condition that the amount of the monohydric alcohol in the polymerization reaction system becomes 0.01-fold equivalent or less relative to the amount of the organozinc compound.

Abstract: An aqueous solution and an aqueous dispersion of a composition that contains a polyalkylene oxide, a phenolic antioxidant and a sulfur-containing amine compound are less likely to impair the stability of the polyalkylene oxide even in the case of containing an alkali. In the above composition, the content of each of the phenolic antioxidant and the sulfur-containing amine compound is preferably set to 0.001 to 5 parts by mass based on 100 parts by mass of the polyalkylene oxide, and the ratio of the sulfur-containing amine compound relative to 100 parts by mass of the phenolic antioxidant is preferably set to 20 to 200 parts by mass.

Abstract: This application relates to circuitry for processing sense signals generated by MEMS capacitive transducers for compensating for distortion in such sense signals. The circuitry has a signal path between an input (204) for receiving the sense signal and an output (205) for outputting an output signal based on said sense signal. Compensation circuitry (206, 207) is configured to monitor the signal at a first point along the signal path and generate a correction signal (Scorr); and modify the signal at at least a second point along said signal path based on said correction signal. The correction signal is generated as a function of the value of the signal at the first point along the signal path so as to introduce compensation components into the output signal that compensate for distortion components in the sense signal. The first point in the signal path may be before or after the second point in the signal path.

Abstract: This application describes methods and apparatus for mitigating the effects of crosstalk in multichannel audio. An audio driver circuit (200) for driving first and second audio loads (103) having a common return path (RC), has first and second signal paths (Left and Right). A crosstalk compensation block (205) is configured to add a first compensation signal to the first signal path and add a second compensation signal to the second signal path. The first compensation signal is generated based on the second audio signal and a first compensation function and the second compensation signal is generated based on the first audio signal and a second compensation function. Each of the first and second compensation functions is based on a predetermined impedance value for at least part of the common return path (RH1) and is also based on a determined DC impedance value (ZL, ZR) for one of the first and second audio loads which is modified by a band correction factor (?).

Abstract: This application relates to Class D amplifier circuits (200). A modulator (201) controls a Class D output stage (202) based on a modulator input signal (Dm) to generate an output signal (Vout) which is representative of an input signal (Din). An error block (205), which may comprise an ADC (207), generates an error signal (?) from the output signal and the input signal. In various embodiments the extent to which the error signal (?) contributes to the modulator input signal (Dm) is variable based on an indication of the amplitude of the input signal (Din). The error signal may be received at a first input (204) of a signal selector block (203). The input signal may be received at a second input (206) of the signal selector block (203).