A grain cleaning system for a combine harvester having a transmitter adapted to transmit a base signal at a known frequency and one or more spaced receivers for detecting signals of a different frequency as reflected from airborne grain and other materials within the duct of the grain cleaning system An Electronic Control Unit modulates the base signal and the reflected signals to obtain Doppler signals or frequencies from which an average particle velocity is determined. The particle velocity is used as an input parameter for the generation of control signals for the adjustment of various working units of the combine harvester including, by way of example, the fan and sieves.

This invention relates to a method of reducing error in a SODAR system adapted to locate discontinuities in the atmosphere over a range extending away from an acoustic transmitter and receiver, the method comprising the steps of: measuring wind to determine either a substantially upwind direction or a substantially downwind direction relative to the transmitter; transmitting one or more forward or reverse acoustic chirps in the substantially upwind or downwind direction; receiving one or more acoustic echoes of the transmitted chirps; and processing the acoustic echoes to provide an indication of the discontinuities in the atmosphere over the range, thereby providing a wind shear profile.

An airborne sound transducer comprises an electromechanical transducer, an air impedance matching layer arranged on an acoustically active surface of the electromechanical transducer, and a cover arranged on the air impedance matching layer, an outer surface of the cover forming an exposed acoustic area of the airborne sound transducer. The outer surface is hydrophilic such that a contact angle of water on the outer surface is less than 60°.

An electronic device for measuring a speed of flow of a fluid that includes at least two electroacoustic transducers adapted for emitting and/or receiving acoustic signals through the flow of the fluid, the electronic device being adapted for determining a measurement of the speed of flow of the fluid from the characteristics of an acoustic signal emitted and one or more acoustic signals received, these received acoustic signals corresponding to reflections of the emitted acoustic signal.

Externally generated noise can be coupled into a fluid carrying structure such as a pipe, well, or borehole so as to artificially acoustically illuminate the pipe, well, or borehole, and allow fluid flow in the structure or structural integrity to be determined. In the disclosed system, externally generated noise is coupled into the structure being monitored at the same time as data logging required to undertake the monitoring is performed. This has three effects. First, the externally generated sound is coupled into the structure so as to illuminate acoustically the structure to allow data to be collected from which fluid flow may be determined, and secondly the amount of data that need be collected is reduced, as there is no need to log data when the structure is not being illuminated. Thirdly, there are signal processing advantages in having the data logging being undertaken only when the acoustic illumination occurs.

A method for determining a flow speed of a liquid in a fluid conduit is provided. During a signal-generating phase, an impulse signal is applied to a first ultrasonic transducer. A response signal is then received at a second ultrasonic transducer. A measuring signal is later derived from the response signal, wherein the derivation comprises reversing a signal portion with respect to time. During a measurement phase, a liquid moves with respect to the fluid conduit. The measuring signal is then applied to one of the two transducers and a response signal of the measuring signal is measured at the other transducer. A flow speed is derived from the response signal of the measuring signal.

A system for determining a borehole shape may comprise a measurement assembly, wherein the measurement assembly may comprise a housing with an outer surface, a transducer disposed flush along the outer surface of the housing, and an extruded boss that connects to the outer surface of the housing. A method may comprise disposing a downhole tool that includes an instrument section into a wellbore and transmitting an excitation from the transducer into the wellbore, wherein the excitation is reflected off a wellbore wall as an echo.

A housing 6 is provided for a wind sensor 2. A sensing element 4 is mounted in the housing 6 to measure the speed of the passing fluid flow, and the housing 6 comprises at least one surface 40, 42 having shaped surface elements 38, such as protrusions from and/or indentations in the surface 40, 42, for inducing turbulence in fluid flowing across the surface 40, 42. The turbulence caused by the shaped surface elements 38 results in the speed measured by the wind sensor 2 being less affected by uncontrolled transitions between laminar and turbulent airflow, and thus enables more accurate calibration of the wind sensor 2.

An air data sensor can include an acoustic transmitter configured to output an acoustic signal into an airflow and a plurality of acoustic transducers configured to receive the acoustic signal output by the acoustic transducer. The air data sensor can also include a light source configured to output a light beam into the airflow, and a light receiver configured to receive scattered light from the light beam. The light source and the light receiver can be bistatic such that a measurement zone is formed away from the air data sensor.

Systems and methods for enabling consistent smooth takeoffs and landings of vertical and/or short-runway takeoff and landing aircraft at sites with gusty conditions. The system includes a network of wind measurement stations deployed around the perimeter of a takeoff/landing site for spatio-temporally characterizing wind fluctuations (e.g., wind gusts) that enter a volume of airspace overlying the site, data processing means for deriving information about the fluctuations from the wind measurements, communication means for transmitting disturbance information to the aircraft, and a flight control system onboard the aircraft that is configured to use the disturbance information to control the aircraft in a manner that compensates for the fluctuations. The wind measurement units may include laser Doppler anemometers, sound detection and ranging systems or other devices capable of simultaneous spatially and temporally resolved wind measurements.