This disclosure describes, among other features, systems and methods for using multiple physiological parameter inputs to determine multiparameter confidence in respiratory rate measurements. For example, a patient monitoring system can programmatically determine multiparameter confidence in respiratory rate measurements obtained from an acoustic sensor based at least partly on inputs obtained from other non-acoustic sensors or monitors. The patient monitoring system can output a multiparameter confidence indication reflective of the programmatically-determined multiparameter confidence. The multiparameter confidence indication can assist a clinician in determining whether or how to treat a patient based on the patient's respiratory rate.

System for determining confidence in respiratory rate measurements

Respiratory rate can be calculated from an acoustic input signal using time domain and frequency domain techniques. Confidence in the calculated respiratory rate can also be calculated using time domain and frequency domain techniques. Overall respiratory rate and confidence values can be obtained from the time and frequency domain calculations. The overall respiratory rate and confidence values can be output for presentation to a clinician.

Respiratory pause detector

We review the study of rogue waves and related instabilities in optical and oceanic environments, with particular focus on recent experimental developments. In optics, we emphasize results arising from the use of real-time measurement techniques, whilst in oceanography we consider insights obtained from analysis of real-world ocean wave data and controlled experiments in wave tanks. Although significant progress in understanding rogue waves has been made based on an analogy between wave dynamics in optics and hydrodynamics, these comparisons have predominantly focused on one-dimensional nonlinear propagation scenarios. As a result, there remains significant debate about the dominant physical mechanisms driving the generation of ocean rogue waves in the complex environment of the open sea. Here, we review state-of-the-art of rogue wave studies in optics and hydrodynamics, aiming to clearly identify similarities and differences between the results obtained in the two fields. In hydrodynamics, we take care to review results that support both nonlinear and linear interpretations of ocean rogue wave formation, and in optics, we also summarise results from an emerging area of research applying the measurement techniques developed for the study of rogue waves to dissipative soliton systems. We conclude with a discussion of important future research directions.

Rogue waves and analogies in optics and oceanography

Freak or rogue waves are so called because of their unexpectedly large size relative to the population of smaller waves in which they occur. The 25.6 m high Draupner wave, observed in a sea state with a significant wave height of 12 m, was one of the first confirmed field measurements of a freak wave. The physical mechanisms that give rise to freak waves such as the Draupner wave are still contentious. Through physical experiments carried out in a circular wave tank, we attempt to recreate the freak wave measured at the Draupner platform and gain an understanding of the directional conditions capable of supporting such a large and steep wave. Herein, we recreate the full scaled crest amplitude and profile of the Draupner wave, including bound set-up. We find that the onset and type of wave breaking play a significant role and differ significantly for crossing and non-crossing waves. Crucially, breaking becomes less crest-amplitude limiting for sufficiently large crossing angles and involves the formation of near-vertical jets. In our experiments, we were only able to reproduce the scaled crest and total wave height of the wave measured at the Draupner platform for conditions where two wave systems cross at a large angle.

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Laboratory recreation of the Draupner wave and the role of breaking in crossing seas

An acoustic Doppler system comprising a plurality of acoustic transceivers, an acoustic subsystem controller and a main processing unit operatively connected to the acoustic subsystem controller. A first of the plurality of acoustic transceivers operates at a first acoustic frequency and is operatively connected to a first group of transducers producing an acoustic signal. A second of the plurality of acoustic transceivers operates at a second acoustic frequency and is operatively connected to a second group of transducers producing an acoustic signal. The first and second acoustic transceivers are adapted to operate concurrently at the first and second acoustic frequencies. The acoustic subsystem controller is operatively connected to the first and second acoustic transceivers and controls the acoustic signals produced by the first and second group of transducers. The main processing unit is adapted to execute instructions to the first and second group of transducers to produce acoustic signals having at least two frequencies and is adapted to run at least two processing methods concurrently. The main processing unit analyzes data received by the first and second group of transducers, automatically adjusts the acoustic frequencies of the acoustic signals produced by the first and second group of transducers, and automatically selects a method of processing the data received by the first and second group of transducers.

Multi-frequency, multi-beam acoustic doppler system

A system and method for measuring the directional spectrum of one or more waves in a fluid medium using a multi-beam sonar system. In an exemplary embodiment, range cells located within a plurality of acoustic beams are sampled to provide current velocity data. Optionally, wave surface height and pressure data is obtained as well. This velocity, wave height, and pressure data is Fourier-transformed by one or more signal processors within the system, and a surface height spectrum produced. A cross-spectral coefficient matrix at each observed frequency is also generated from this data. A sensitivity vector specifically related to the ADCP's transducer array geometry is used in conjunction with maximum likelihood method (MLM), iterative maximum likelihood method (IMLM), or other similar methods to solve a the wave equation at each frequency and produce a frequency-specific wave directional spectrum. Ultimately, the frequency-specific spectra are combined to construct a complete two-dimensional wave directional spectrum. The system is also capable of measuring current profile as a function of depth in conjunction with wave direction and wave height.

System and method for measuring wave directional spectrum and wave height

A system and method of horizontal wave measurement is disclosed. The system for measuring the directional spectrum of waves in a fluid medium having a substantially planar surface may include a sonar system having a plurality of transducers for generating respective acoustic beams and receiving echoes from one or more range cells located substantially within the beams, at least one of the plurality of acoustic beams being angled non-orthogonally to at least one other of the plurality of acoustic beams. The method may calculate the directional spectrum associated with the waves from the received echoes.

System and method of horizontal wave measurement

Extreme Water Waves off the West Coast of Ireland: Analysis of ADCP Measurements

PROBLEM TO BE SOLVED: To provide an invention related to an acoustic Doppler current meter used for measuring a wave direction spectrum and a surface pulse height SOLUTION: This system for measuring the wave direction spectrum in a flowing medium having a substantially flat water face may includes a sonor system having a plurality of probes for generating individual acoustic beams and for receiving an echo from one of more of range cells arranged substantially within the beam, at least one out of the plurality of acoustic beams is (are) generated at an angle not orthogonal to at least one of the other acoustic beams out of the plurality of acoustic beams In this method, the direction spectrum related to a wave may be calculated based on the received echo COPYRIGHT: (C)2005,JPO&NCIPI

Brandon S. Strong

Papers

System and method for measuring wave directional spectrum and wave height

System and method of horizontal wave measurement

Extreme Water Waves off the West Coast of Ireland: Analysis of ADCP Measurements

Horizontal wave measuring system and method