The flow rate of light scattering fluid is measured more easily and at a higher speed.

A flow rate measuring method according to the present disclosure includes: generating two or more speckle images by continually imaging light scattering fluid to be measured, while defining time shorter than spatial correlation disappearance time corresponding to time in which spatial correlation between speckle patterns generated by the light scattering fluid disappears as exposure time, at a time interval shorter than the spatial correlation disappearance time; and calculating direction and speed of flow of the light scattering fluid from time variation of the speckle patterns between the two or more speckle images, in which the speckle images are imaged by using an imaging device mounted with an area sensor and a pixel group of a part of the area sensor or by using an imaging device mounted with a line sensor.

There is provided a speckle measurement apparatus to improve accuracy of flow velocity measurement or the like of particulates such as erythrocytes, the speckle measurement apparatus including an imager that captures scattered light images returned from an object to be measured when the object to be measured is irradiated with coherent light as speckle images, and a controller that determines a measurement area that is the same site of the object to be measured in a plurality of the speckle images captured continuously in time series by the imager by incorporating a displacement amount of a relative positional relationship between the object to be measured and the imager.

There is provided a speckle measurement apparatus to improve accuracy of flow velocity measurement or the like of particulates such as erythrocytes, the speckle measurement apparatus including an imager that captures scattered light images returned from an object to be measured when the object to be measured is irradiated with coherent light as speckle images, and a controller that determines a measurement area that is the same site of the object to be measured in a plurality of the speckle images captured continuously in time series by the imager by incorporating a displacement amount of a relative positional relationship between the object to be measured and the imager.

Provided herein are improved methods for estimating the flow velocity of a fluid in a vessel. Systems and methods are provided herein related to making and/or refining velocity measurements for flowing fluids, both single and multi-phase fluids, in vessels, such as pipes or conduits, utilizing contrast media property agent variations. In one aspect, this disclosure provides a method of determining a flow velocity of a fluid flow in a vessel including: providing a fluid flow having contrast media, the contrast media having a contrast media property variation; providing a detectable signal corresponding to the contrast media property variation; collecting the detectable signal at an upstream receiver to produce a first received signal; collecting the detectable signal at a downstream receiver to produce a second received signal, the downstream receiver being located downstream of the upstream receiver at a distance (L); filtering the first received signal and the second received signal through a contrast media variant filter to produce a first filtered signal and a second filtered signal; cross-correlating the first filtered signal and the second filtered signal to determine a time shift (t) between the first filtered signal and the second filtered signal; and estimating the velocity of the fluid flow using this relationship vflow=L/t.

Techniques are provided for determining a moving body's position and velocity in the presence of motion of a measuring device relative to the body. For example, a swimmer's position and velocity may be determined by compensating for bias that may result from a swimmer's arm swing. This may help avoid over-estimating a swimmer's velocity that results in inaccurate position estimation along the swimmer's path. To compensate for the swimmer's arm swing, an estimate of translational velocity due to arm rotation may be removed, e.g., from pseudo-range rates (PRRs) from satellite positioning system measurements, to reduce the systematic bias errors. A scale factor is applied to an estimated velocity of the swimmer's body to estimate the velocity of a mobile device on the swimmer's wrist, e.g., while above water.

Techniques are provided for determining a moving body's position and velocity in the presence of motion of a measuring device relative to the body. For example, a swimmer's position and velocity may be determined by compensating for bias that may result from a swimmer's arm swing. This may help avoid over-estimating a swimmer's velocity that results in inaccurate position estimation along the swimmer's path. To compensate for the swimmer's arm swing, an estimate of translational velocity due to arm rotation may be removed, e.g., from pseudo-range rates (PRRs) from satellite positioning system measurements, to reduce the systematic bias errors. A scale factor is applied to an estimated velocity of the swimmer's body to estimate the velocity of a mobile device on the swimmer's wrist, e.g., while above water.

An optically based combustion off-gas stream velocity sensor assembly is provided for detecting in real-time off-gas flow velocity and/or volume as it moves through a flue duct. The sensor assembly includes two paired coherent light emitters and optic sensors, positioned in a spaced orientation in the flow path direction. The light emitter/optic sensor pairs operate to emit and detect across the off-gas stream coherent light beam energy having a wavelength component corresponding to an absorption profile of an off-gas species component. The detection of non-absorbed portions of the emitted beam is used to identify and detect the movement of a flow species signature at different locations along the flue duct.

An optically based combustion off-gas stream velocity sensor assembly is provided for detecting in real-time off-gas flow velocity and/or volume as it moves through a flue duct. The sensor assembly includes two paired coherent light emitters and optic sensors, positioned in a spaced orientation in the flow path direction. The light emitter/optic sensor pairs operate to emit and detect across the off-gas stream coherent light beam energy having a wavelength component corresponding to an absorption profile of an off-gas species component. The detection of non-absorbed portions of the emitted beam is used to identify and detect the movement of a flow species signature at different locations along the flue duct.

The invention relates to a method for measuring a flow velocity (v) of a gas stream (14) featuring the steps: (a) time-resolved measurement of an IR radiation parameter (E) of IR radiation of the gas stream (14) at a first measurement point (P1) outside of the gas stream (14), thereby obtaining a first IR radiation parameter curve (E.sub.g1,1(t)), (b)time-resolved measurement of an IR radiation parameter (E) at a second measurement point (P2) outside of the gas stream (14), thereby obtaining a second IR radiation parameter curve (E.sub.g1,2(t)), (c) calculation of a transit time (?1) from the first IR radiation parameter curve (E.sub.g1,1(t)) and the second IR radiation parameter curve (E.sub.g1,2(t)), in particular by means of cross-correlation, and (d) calculation of the flow velocity (vG) from the transit time (?1), (e) wherein the IR radiation parameter (E.sub.g1) is measured photoelectrically at a wavelength (g1) of at least 780 nm, and (f) a measurement frequency (f) is at least 1 kilohertz.

A method for determining the velocity of a moving fluid surface, which comprises the following steps S1 to S5: S1) taking a sequence of images of the moving fluid surface by at least one camera; S2) comparing a first image from the sequence with a second image from the sequence in order to distinguish moving patterns of the fluid surface from non-moving parts and to obtain a first processed image (im_1f) comprising the moving patterns; S3) comparing a third image from the sequence with a fourth image from the sequence in order to distinguish moving patterns of the fluid surface from non-moving parts and to obtain a second processed image (im_2f) comprising the moving patterns; S4) comparing the first and second processed images in order to determine the spatial displacements of the moving patterns; and S5) determining from the spatial displacements the velocity.