Abstract: A method and apparatus for generating, propagating, encoding, decoding, modulating and detecting acoustic signals in a well borehole that comprises a signal generator (10) located at a first location for generating an acoustic source signal; a medium for the propagation the acoustic source signal to a second location and the propagation of the reflections and partial reflections of acoustic signals as it propagates through the medium; an apparatus to remove a detectable amount of energy from propagated acoustic signals; a controllable signal modulator (11) for attenuating the transmitted acoustic source signal; and a receiver (12) for receiving the modulated acoustic signals reflected, partially reflected or both by at least one reflector respectively located at one or more other locations.

Abstract: Embodiments relate to systems and methods for an active damping device for stabilizing a power grid of active sources and loads. In power system networks or grids which incorporate active power sources and active loads, such as motors, the output voltage transfer function can exhibit instabilities due to the presence of poles in the positive real portion (right hand side) of the complex plane. Those poles can induce uncontrolled ringing, oscillations, or other artifacts or instabilities. According to implementations, an active damping element can be introduced into the power system grid, which operates to drive the poles of the output transfer function to the negative real (left hand) portion of the complex plane. Output voltage and other parameters can thereby be stabilized. In implementations, the damping element can include an R-C network for DC output systems, or a controller including a voltage source inverter for AC output systems.

Abstract: Embodiments relate to systems and methods for tuning the control of a shunt active power filter over a variable frequency. In aspects, a shunt active power filter is provided to filter current harmonics from the output delivered to a dc load via a recitifier. The shunt active power filter control can be configured as a set of resonant regulators connected in a parallel configuration. Each of the resonant regulators can be tuned to dampen or eliminate a particular harmonic, such as the 5th, 7th, 11th, 13th, 17th or 19th harmonics. The shunt active power filter can be configured to target those or other harmonics over a range of source voltage frequencies, such as 360-800 Hz. The harmonics can be tuned over that or other source frequency ranges by determining the root locus poles of the filter as a function of feedback loop gain.

Abstract: Embodiments relate to systems and methods for selecting circuit element values for a hybrid active power filter operating over a variable frequency. In aspects, a hybrid active power filter (HAPF) circuit can eliminate current harmonics present in an AC power source which are caused by an AC load network.—In implementations, the AC voltage source—may be a source having a variable frequency range, for instance 360-800 Hz. Since the source voltage can encompass a significant frequency range, a simple determination of the correct or desirable values of capacitive and inductive elements in the filtering section of the HAPF may not be possible. According to aspects, analytic techniques are provided which allow the values of those circuit elements to be derived from impedance and other circuit values to provide satisfactory suppression of identified harmonics, which can include the 5th, 7th, 11th, 13th, 17th, 19th, 23rd, 25th harmonics in the output voltage.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may receive a calculated value indicative of a physiological rate. Based on the value, the system may select pairs of values of the physiological signal that are particularly spaced. The system may determine a state for each pair of values. The state may correspond to a set of criteria such as, for example, equalities, inequalities, logical operators, or other criteria. The system may determine a number of state transitions based on the determined states, and qualify or disqualify the calculated value based on the number of state transitions.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may receive a calculated value indicative of a period associated with a physiological rate. The system may generated a first sorted difference signal based on a segment of the physiological signal having a size corresponding to the period. The system may generate second and third sorted difference signals based on segments of the physiological signal having sizes corresponding to a fraction of the period and a multiple of the period. The system may analyze the first, second, and third sorted difference signals, and qualify or disqualify the calculated value based on the analysis.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may generate a window of data, and determine physiological information based on the window of data. The generated window of data may include one or more samples of physiological data, from the physiological signal, and one or more initialization values. The initialization values may include random numbers, noise values, sample values, scaled values thereof, or a combination thereof.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may apply a digital filter to the physiological signal to assist in the determination of the physiological information. The system may determine a metric based on the physiological signal, and selectively apply the digital filter to the physiological signal based on the metric. The digital filter, which may include two or more filter coefficients, may correspond to a weighted sum of the physiological signal and a difference signal corresponding to the physiological signal. The filter coefficients may be adjustable, allowing selectivity in the characteristics of the digital filter between weighting the physiological signal and difference signal.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may condition the physiological signal to assist in the determination of the physiological information. The system may generate absolute values of the physiological signal, filter the absolute values, and modify the physiological signal based on the filtered signal. The filtered signal may be shifted in amplitude prior to modifying the physiological signal. The modification may include dividing the physiological signal by the filtered signal to normalize the physiological signal.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may process a physiological signal such a photoplethysmograph signal from a subject. The system may determine physiological information, such as a physiological rate, from the physiological signal. The system may use search techniques and qualification techniques to determine one or more initialization parameters. The initialization parameters may be used to calculate and qualify a physiological rate. The system may use signal conditioning to reduce noise in the physiological signal and to improve the determination of physiological information. The system may use qualification techniques to confirm determined physiological parameters. The system may also use autocorrelation techniques, cross-correlation techniques, fast start techniques, and/or reference waveforms when processing the physiological signal.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may filter the physiological signal based on an adjustable filter to generate a filtered physiological signal. The system may perform calculations over time based on the filtered physiological signal to determine values indicative of a physiological parameter. The adjustable filter may be adjusted based on the values indicative of the physiological parameter. Some of the calculations are qualified and some of the calculations are disqualified. The system may determine a metric based on the physiological signal that is used to determine whether to output a value based on one or more previously calculated values when a current calculation is disqualified. The system may output a value based on one or more previously calculated values when a current calculation is disqualified and when a criterion based on the metric is satisfied.

Abstract: A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may receive a calculated value indicative of a physiological rate. The system may generate and sort multiple difference signals based on the physiological signal. The system may analyze a first sorted difference signal and a second sorted difference signal to determine at least one first metric, and analyze a third sorted difference signal and a fourth sorted difference signal to determine at least one second metric. The system may qualify or disqualify the calculated value based on the at least one first and second metrics. The segments used to generate the third and fourth sorted difference signals may, for example, be subsets of the segments used to generate the first and second sorted difference signals.