A device for determining and/or monitoring at least one process variable of a medium in a container includes four, rod-shaped elements arranged on a membrane, three piezoelectric elements and an electronics system, wherein one first and one second rod-shaped element are arranged and configured such that they form a mechanically vibratable unit, wherein the device is configured to excite the vibratable unit via an excitation signal to create mechanical oscillations, to receive the mechanical oscillations of the vibratable unit, to convert them into a first received signal, to transmit a transmitted signal, and to receive a second received signal, and wherein the electronics system is configured to determine the at least one process variable based on the first and/or second received signal.

In some examples, an aspiration system a catheter and a fluid flow sensor. The fluid flow sensor includes a fluid inlet, a fluid outlet, and a flow oscillator. The fluid inlet is configured to receive fluid from the catheter. The flow oscillator configured to oscillate flow of the fluid through the fluid flow sensor to generate flow-induced vibrations. The fluid outlet is configured to discharge the fluid.

An oxygen therapy monitoring device includes an oscillation chamber with in a gas flow path adapted to pass a gas flow from a source to a breathing interface for a person. The oscillation chamber induces an oscillation in the gas flow that varies as a function of a flow rate of the gas flow. A measurement arrangement measures the oscillation induced in the gas flow and determines the flow rate on the basis of the oscillation that is measured.

A device and a method for determining the flow velocity of a fluid in a hollow body, including at least one disturbance device disposed in the hollow body and at least one sensor for identifying disturbances that are induced in the flow by the disturbance device, which is disposed at a certain distance downstream in the direction of flow from the disturbance device, wherein the disturbance device includes means for generating changeable disturbances in the fluid flow.

In some examples, an aspiration system a catheter and a fluid flow sensor. The fluid flow sensor includes a fluid inlet, a fluid outlet, and a flow oscillator. The fluid inlet is configured to receive fluid from the catheter. The flow oscillator configured to oscillate flow of the fluid through the fluid flow sensor to generate flow-induced vibrations. The fluid outlet is configured to discharge the fluid.

A system and method for monitoring a dispensed fluid jet with an oscillation nozzle, comprising a main channel and at least one secondary channel surrounding the main channel, wherein the nozzle has an inlet and an outlet for an air flow defining a flow axis running centrally through the main channel, characterized in that the secondary channel comprises a drill hole.

A device and a method for determining the flow velocity of a fluid in a hollow body, including at least one disturbance device disposed in the hollow body and at least one sensor for identifying disturbances that are induced in the flow by the disturbance device, which is disposed at a certain distance downstream in the direction of flow from the disturbance device, wherein the disturbance device includes means for generating changeable disturbances in the fluid flow.

A method for configuring a learning machine to predict a flow rate of at least one phase of a fluid. The method comprises determining a feature set for the learning machine, the feature set including information derived from a signal generated by a flow of the fluid interacting with a fluidic oscillator in a wellbore. The method comprises configuring the learning machine with the feature set including information derived from the signal.

An asymmetric fluidic oscillator can generate acoustic signals in a wellbore. The asymmetric fluidic oscillator can include an inlet housing defining an inlet channel, a feedback system, and an outlet housing defining an outlet channel. The inlet channel can be sized to receive fluid from the wellbore. The feedback system can be coupled to the inlet channel to oscillate the fluid from the wellbore. The outlet channel can be coupled to the feedback system and can be sized to receive the oscillated fluid from the feedback system. The outlet channel can include an asymmetric feature to generate acoustic signals detectable in the wellbore.

A system and method for monitoring a dispensed fluid jet with an oscillation nozzle, comprising a main channel and at least one secondary channel surrounding the main channel, wherein the nozzle has an inlet and an outlet for an air flow defining a flow axis running centrally through the main channel, characterized in that the secondary channel comprises a drill hole.