Abstract: Method and apparatus relating to ultrasound flow probes Measurement of time of flight of ultrasound pulses comprises: transmitting the pulses across a fluid flow; detecting a waveform (200) of the pulses, generating a cross-correlation between the waveform (200) and a tone (210) and identifying a plurality of peaks (220) in the cross-correlation; fitting a curve template (310) to the waveform at locations (300) corresponding to the peaks (220) and identifying the location (330) of the minimum error; performing a further cross-correlation (420) between the waveform (200) and the tone (210) over only a portion of the waveform (200) containing the minimum error location (330); and determining the temporal location corresponding to the maximum (430) of the further cross-correlation (430).

Abstract: A method and apparatus (1) for monitoring particles flowing in a stack are disclosed. The method comprises emitting light from a light source along an optical path for scattering from the particles, rotating a rotatable monitoring assembly (15) mounted in the optical path, and detecting the scattered light using a detector. The rotatable monitoring assembly (15) contains at least two in apertures, and the method further comprises rotating the rotatable monitoring assembly (15) into a plurality of different configurations. In an operation configuration, light passes through the rotatable monitoring assembly (15) and into the stack unimpeded. In a zero-check configuration, the rotatable monitoring assembly (15) blocks the light from reaching the stack. In a span-check configuration, light of varying intensity passes from the light source through the rotatable monitoring assembly (15) into the stack.

Abstract: A method of monitoring particles in a stack comprises generating on a first side of the stack a beam of light directed towards a second, opposite, side of the stack. The beam is reflected back towards the first side of the stack and through the particles in the stack. An image is obtained of light scattered from the particles. The image is obtained using an imager positioned and oriented to have a field of view that includes unwanted scattered light. The method includes the step of blocking the unwanted scattered light from the image.

Abstract: A method of monitoring particles in a stack comprises generating on a first side of the stack a beam of light directed towards a second, opposite, side of the stack. The beam is reflected back towards the first side of the stack and through the particles in the stack. An image is obtained of light scattered from the particles. The image is obtained using an imager positioned and oriented to have a field of view that includes unwanted scattered light. The method includes the step of blocking the unwanted scattered light from the image.

Abstract: An apparatus (7) for monitoring particles flowing in a stack (6), comprises: an electrical-interaction monitor (1) operable to provide a signal (300) resulting from electrical interaction of the particles with the monitor (1). a scattered-light monitor (10) operable to provide a signal (310) resulting from detection of light scattered from the particles, and a controller (320) arranged to alter the calibration of the electrical-interaction monitor 1 in response to changes in the relative magnitude of the electrical-interaction (signal 300) and the scattered-light signal (310).

Abstract: An instrument (10) for monitoring particles (67) flowing in a stack, includes: (a) a light source for providing a light beam (60); (b) a sensor/and (c) a probe housing. The housing comprises: (i) a mount (25); (ii) a proximal portion (30) including a first aperture (35) through which in use the light beam (60) exits; (iii) a distal portion (50), including a second aperture (55) through which the light beam (60) enters after having been scattered from particles (67) flowing in the stack, and a focusing mirror (70) arranged to reflect and focus the scattered light (90); (iv) a medial portion (40), connecting the distal portion (50) to the proximal portion (30); (v) a waveguide (80), passing from the distal portion (50) through the medial portion (40) and the proximal portion (30) to the sensor and arranged to guide to the sensor the light (90) reflected and focused by the focusing mirror (70).

Abstract: An instrument (10) for monitoring particles (67) flowing in a stack, includes: (a) a light source for providing a light beam (60); (b) a sensor/and (c) a probe housing. The housing comprises: (i) a mount (25); (ii) a proximal portion (30) including a first aperture (35) through which in use the light beam (60) exits; (iii) a distal portion (50), including a second aperture (55) through which the light beam (60) enters after having been scattered from particles (67) flowing in the stack, and a focusing mirror (70) arranged to reflect and focus the scattered light (90); (iv) a medial portion (40), connecting the distal portion (50) to the proximal portion (30); (v) a waveguide (80), passing from the distal portion (50) through the medial portion (40) and the proximal portion (30) to the sensor and arranged to guide to the sensor the light (90) reflected and focused by the focusing mirror (70).

Abstract: An apparatus (7) for monitoring particles flowing in a stack (6), comprises: an electrical-interaction monitor (1) operable to provide a signal (300) resulting from electrical interaction of the particles with the monitor (1). a scattered-light monitor (10) operable to provide a signal (310) resulting from detection of light scattered from the particles, and a controller (320) arranged to alter the calibration of the electrical-interaction monitor 1 in response to changes in the relative magnitude of the electrical-interaction (signal 300) and the scattered-light signal (310).

Abstract: An apparatus for detecting particles in a flow comprises a probe 1 positioned so that it projects into the flow and is charged triboelectrically by the particles in the flow. An electric circuit is coupled to the probe 1 and includes evaluating means for monitoring a signal from the probe 1 and for providing an output in dependence on the signal generated by the triboelectric charging of the probe 1. The part of the probe 1 that projects into the particle flow comprises an electrically conducting core covered with an insulating layer 2 which insulates the core from the particle flow.