A method of measuring a flow rate of a fluid flowing along a path, the method comprising: transmitting successive pairs of periodic signals through the fluid, the respective signals of each pair being transmitted in opposite directions along, and from opposite ends of, the path; determining a difference in propagation times of each signal of each pair along the path; and determining a flow rate of fluid along the path based on the difference in propagation times of the signals of each pair along the path; wherein a phase of each signal is altered with respect to a phase of at least one other signal transmitted along the path.

An acoustic airspeed sensor system can include at least one acoustic transmitter configured to provide an acoustic pulse, a plurality of acoustic receivers including at least a first acoustic receiver, a second acoustic, receiver, and a third acoustic receiver, each positioned at a first radial distance from the at least one acoustic transmitter. The first acoustic receiver, the second acoustic receiver, and the third acoustic receiver are each configured to receive the acoustic pulse at a first time, a second time, and a third time, respectively, and output a first receiver signal, a second receiver signal, and a third receiver signal respectively. The system can include a computation unit operatively connected to the acoustic receivers and configured to generate a propagation function. The computation unit is further configured to determine true air speed based upon a receiver signals and the propagation function.

A method of determining a measure of wave speed or intensity in a fluid conduit uses ultrasound measurements to determine the conduit diameter and fluid velocity in a volume element, each as a function of time, and each at a same longitudinal position of the conduit. The ultrasound measurement to determine fluid velocity is effected by tracking objects within the fluid flow in successive frames sampling the volume element, and obtaining displacement vectors for the objects. A wave speed may be determined from a ratio of the change in fluid velocity at the longitudinal position as a function of time and the change in a logarithmic function of the conduit diameter as a function of time. A measure of wave intensity may be determined as a function of change in determined conduit diameter and corresponding change in fluid velocity.

A method of determining a measure of wave speed or intensity in a fluid conduit uses ultrasound measurements to determine the conduit diameter and fluid velocity in a volume element, each as a function of time, and each at a same longitudinal position of the conduit. The ultrasound measurement to determine fluid velocity is effected by tracking objects within the fluid flow in successive frames sampling the volume element, and obtaining displacement vectors for the objects. A wave speed may be determined from a ratio of the change in fluid velocity at the longitudinal position as a function of time and the change in a logarithmic function of the conduit diameter as a function of time. A measure of wave intensity may be determined as a function of change in determined conduit diameter and corresponding change in fluid velocity.

The present disclosure relates to a coupling member (20) for a flow metering device, the coupling member (20) being configured for acoustically coupling an ultrasonic transducer (26) to a fluid conduit (90), wherein the coupling member comprises a first face (22) adapted to be connected to an ultrasonic transducer (26) and a second face (24) adapted to be connected to a fluid conduit. At least one sidewall (30) connects the first and second faces (22, 24), wherein the at least one sidewall (30) comprises a recess (40) extending from the second face (24).

Systems and devices for airflow measurements in rooms and air delivery ducts with low-cost, low-power, accurate, calibration-free, and compact wireless airflow sensors are provided. The system uses room and duct flow sonic anemometers and processing to measure air velocities and temperatures as well as allow control over the environmental conditioning systems. The anemometers use arrays of transmitter/receivers to simultaneously measure multiple sound paths and determine velocity vectors and volumetric flow paths. By transmitting in both directions along the paths between transceivers, differential times of flight (TOF) are measured. These determine both the velocity and temperature of the air along each path.

A method for detecting wind using a microphone and a speaker of an electronic device. The method obtains a microphone signal produced by the microphone. The method obtains a speaker input signal produced by the speaker that is emulating a microphone capturing ambient sound in an environment through the speaker. The method determines a coherence between the microphone signal and the speaker input signal and determines whether the coherence is below a coherence intensity threshold. In response to determining that the coherence is below the coherence intensity threshold, the method determines a presence of wind in the environment.

In one illustrative configuration, an air quality monitoring system may enable wide-scale deployment of multiple air quality monitors with high-confidence and actionable data is provided. Further, the air quality monitoring system may enable identifying a target emission from a plurality of potential sources at a site based on simulating plume models. The simulation of plume models may take into consideration various simulation parameters including wind speed and direction. Further, methods of determining a plume flux of a plume of emissions at a site, and methods of transmitting data from an air quality monitor are disclosed.

An airborne acoustic vector sensor for simultaneously measuring triaxial particle acceleration in three dimensions and pressure includes a triaxial MEMS accelerometer sensitive to an Earth gravitational field. The airborne acoustic vector sensor includes one or multiple MEMS microphones sensitive to sound pressure and overlapping the accelerometer in frequency. The airborne acoustic vector sensor includes a solid body having a density approximating a density of air. The accelerometer is mounted in or upon the solid body. The airborne acoustic vector sensor includes a suspension system supporting the accelerometer and solid body within a framework.

Realized is a device capable of measuring a wind speed and a wind direction with high precision while reducing the effect of ambient noise. The device includes an acoustic wave transmitting section that transmits a measurement acoustic wave, an acoustic wave receiving section that receives the measurement acoustic wave transmitted from the acoustic wave transmitting section, a signal selecting section that determines a characteristic of the measurement acoustic wave, and a wind speed calculating section that calculates a wind speed by analyzing a signal received by the acoustic wave receiving section. The signal selecting section selects, as the measurement acoustic wave, an acoustic wave that includes a low-intensity frequency bandwidth selected from a noise signal which the acoustic wave receiving section receives when the measurement acoustic wave is not transmitted.