Her Majesty the Queen in Right of Canada, As Represented by the Minister

Carleton University

Minister of National Defence

Douglas B George

Robert W Kempster

L Robert Morris

A device to detect the presence of particles, principally metallic particles, in fluid lines. The fluid to be sampled flows through a former on which is wound a coil assembly comprising a sensor coil flanked upstream and downstream by two field coils. The former is constructed with a double wall and air gap such that pressure fluctuations in the fluid are not transmitted to the coil assembly to adversely affect the positions and readings of the coils. The field coils are driven by a high frequency signal derived from a crystal oscillator and the upstream and downstream sections are wound in opposite directions such that the magnetic field from each section is cancelled out in the plane of the sense coil. When a ferromagnetic or conductive particle passes through the winding structure, the coupling in the sense coil is disturbed as the particle first interacts with the field in the upstream section of the field coil and later with the field in the downstream section of the field coil as it passes through the Sensor Coil Assembly (SCA). A characteristic signature is generated in the sense coil which results from the vector summation of these transient imbalance signals with the steady-state signal from the opposed field coils. Analysis of the phase of this signature can be used to detect and distinguish between the presence of ferromagnetic and non-ferromagnetic conductive particles. Since ferromagnetic and non-ferromagnetic conductive particles interact with the field via permeability and eddy current effects respectively, the transient phase signature has a characteristic lag-lead or lead-lag sequence depending on the nature of the particle.

Method and apparatus for detecting particles in a fluid having coils

A device to detect the presence of particles, principally metallic particles, in fluid lines. The fluid to be sampled flows through a sensor coil which is flanked upstream and downstream by two field coils. The field coils are driven by a high frequency signal derived from a crystal oscillator and the upstream and downstream sections are wound in opposite directions such that the magnetic field from each section is cancelled out in the plane of the sense coil. When a ferromagnetic or conductive particle passes through the winding structure, the coupling in the sense coil is disturbed as the particle first interacts with the field in the upstream section of the field coil and later with the field in the downstream section of the field coil as it passes through the Sensor Coil Assembly (SCA). A characteristic signature is generated in the sense coil which results from the vector summation of these transient imbalance signals with the steady-state signal from the opposed field coils. Analysis of the phase of this signature can be used to detect and distinguish between the presence of ferromagnetic and non-ferromagnetic conductive particles. Since ferromagnetic and non-ferromagnetic conductive particles interact with the field via permeability and eddy current effects respectively, the transient phase signature has a characteristic lag-lead or lead-lag sequence depending on the nature of the particle.

Detection and discrimination between ferromagnetic and non-ferromagnetic

A method of operating a telescope is provided herein for a telescope having an eyepiece. The method uses a graphics display having a data base of celestial bodies, and means for generating and displaying a graphics display comprising graphics artefacts, each representing an associated celestial body. The method includes the first step of correlating, as a datum, the position of that telescope and the position of that graphics display corresponding to the field of view of the telescope. The second step involves displacing that graphics display or the position of the telescope to show an artefact representing a celestial body of interest. The third step involves detecting the effective distance moved in such displacing step. The final step involves either moving the telescope a corresponding distance, or changing that graphics display effectively to track movement of the telescope, respectively, such that the celestial body of interest is visible in the telescope eyepiece, and a corresponding graphics artifact is visible in that graphics display. Further in a preferred embodiment, that graphics display is superimposed on the telescope image in the eyepiece such that the graphics artifact is aligned with the celestial body of interest.

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Kanata, Canada

Douglas B George