Mr. Douglas J. Thomson Profile

Douglas J. Thomson

Professor at Univ of Manitoba

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Publications (11)

Proceedings Article | 4 November 2016 Presentation

Torque-mixing magnetic resonance spectroscopy (Conference Presentation)

Joseph Losby, Fatemeh Fani Sani, Dylan Grandmont, Zhu Diao, Miro Belov, Jacob Burgess, Shawn Compton, Wayne Hiebert, Doug Vick, Kaveh Mohammad, Elham Salimi, Gregory Bridges, Douglas Thomson, Mark Freeman

Proceedings Volume 9931, 993110 (2016) https://doi.org/10.1117/12.2239173

KEYWORDS: Magnetism, Magnetic sensors, Magnetic resonance imaging, Electromagnetism, Sensors, Spectroscopy, Nanotechnology, Error control coding, Bridges, Molecular bridges

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Proceedings Article | 6 April 2012 Paper

Inductively coupled corrosion potential sensor for steel reinforced concrete with time domain gating interrogation

D. Thomson, K. Perveen, G. Bridges, S. Bhadra

Proceedings Volume 8345, 83454P (2012) https://doi.org/10.1117/12.921332

KEYWORDS: Sensors, Corrosion, Diodes, Capacitance, Electrodes, Sensing systems, Electronics, Inductance, Circuit switching, Computer engineering

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Proceedings Article | 26 April 2007 Paper

A passive wireless displacement sensor for structural health monitoring of civil structures

A. Hladio, D. Card, D. Thomson, G. Bridges, C. Klowak, A. Mufti

Proceedings Volume 6531, 653114 (2007) https://doi.org/10.1117/12.716940

KEYWORDS: Sensors, Signal detection, Structural health monitoring, Switches, Bridges, Antennas, Statistical analysis, Servomechanisms, Electromagnetism, Actuators

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Proceedings Article | 10 April 2007 Paper

Side-polished and tilted fiber Bragg grating sensors for structural health monitoring applications

C-F. Chan, G. Ferrier, D. Thomson, C. Chen, J. Albert, A. Vincelette, P. Lefebvre

Proceedings Volume 6530, 65300F (2007) https://doi.org/10.1117/12.715879

KEYWORDS: Fiber Bragg gratings, Refractive index, Cladding, Sensors, Structural health monitoring, Polishing, Environmental sensing, Spectrum analysis, Water, Liquids

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Proceedings Article | 20 March 2006 Paper

Evanescent field fiber Bragg grating sensors for index of refraction sensing with applications to structural health monitoring

C.-F. Chan, G. Ferrier, D. Thomson, T. Coroy, P. Lefebvre, A. Vincelette

Proceedings Volume 6176, 617614 (2006) https://doi.org/10.1117/12.655702

KEYWORDS: Refractive index, Fiber Bragg gratings, Sensors, Cladding, Structural health monitoring, Polishing, Optical fibers, Refraction, Fiber optics sensors, Water

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Proceedings Article | 19 May 2005 Paper

Comparison of recoated fiber Bragg grating sensors under tension on a steel coupon

E. Rivera, D. Thomson, A. Mufti

Proceedings Volume 5767, (2005) https://doi.org/10.1117/12.607483

KEYWORDS: Sensors, Fiber Bragg gratings, Fiber optics sensors, Manufacturing, Structural health monitoring, Seaborgium, Refractive index, Fiber coatings, Chemical elements, Sensing systems

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One of the key elements in a structural health monitoring system is the sensing element and data acquisition system. One type of fiber optic sensor used to measure strain is the fiber Bragg grating. Bragg gratings are fabricated using different methods. One method involves placing a mask pattern over the optical fiber and projecting UV light through it to change the refractive index of the core. However, before the grating is written into the core of the fibre, the outer fibre coatings must be stripped away either mechanically or chemically. Fibre Bragg gratings are then recoated after the grating has been written to maintain the strength and flexibility of the fibre by protecting the exposed glass from damage. Acrylate and polyimide are two types of recoat material typically used on fibre Bragg grating sensors. This work is a controlled comparison of polyimide and acrylate recoated fibres for Bragg grating strain sensors. The comparison was carried out using a tension test coupon with recoated FBG and electrical strain gauges bonded to its surface. The tension test specimen was made of cold rolled steel and was designed according to ASTM A30-97a standard. The dimensions were chosen such that three fibre optic sensors and a strain gauge can be attached on each side. The load was applied in 40 με steps until the strain reached approximately 200 µε. The load was then incrementally decreased back to zero. FBG sensors from 2 manufacturers were compared. For the first manufacturer the Acrylate coated sensors required a gauge factor is 0.75 in order for electrical and FBG strain readings to agree. For Polyimide coated sensors, the appropriate gauge factor was very close to the theoretically predicted value of 0.8. Using these gauge factors, the error between the first manufacturers sensor readings and the strain gauges was well within ±5µε. On the other hand, the second manufacturers sensors did not perform nearly as well. Their readings were substantially lower than the corresponding electrical strain gauges readings and varied from 7% to 13% below expected strain readings. This study demonstrates that bonded FBG sensors can reliably measure strain, but that not all manufacturers are producing recoated FBG sensors to the standard required for strain sensing in civil structures.

Proceedings Article | 9 May 2005 Paper

Noise reduction in RF cavity wireless strain sensors

Jenny Chuang, D. Thomson

Proceedings Volume 5768, (2005) https://doi.org/10.1117/12.600041

KEYWORDS: Sensors, Signal detection, Antennas, Signal to noise ratio, Denoising, Structural health monitoring, Fiber optics sensors, Switches, Interference (communication), Environmental sensing

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Proceedings Article | 27 July 2004 Paper

Accurate strain measurements with fiber Bragg grating sensors and wavelength references

Evangeline Rivera, Douglas Thomson

Proceedings Volume 5384, (2004) https://doi.org/10.1117/12.542107

KEYWORDS: Fiber Bragg gratings, Fabry–Perot interferometers, Sensors, Signal to noise ratio, Absorption, Fiber optics sensors, Gas lasers, Interference (communication), Sensor technology, Structural health monitoring

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Proceedings Article | 26 July 2004 Paper

Wireless strain sensor based on resonant RF cavities

Jenny Chuang, Douglas Thomson, Greg Bridges

Proceedings Volume 5390, (2004) https://doi.org/10.1117/12.541073

KEYWORDS: Sensors, Signal detection, Resonators, Switches, Amplifiers, Signal to noise ratio, Antennas, Metals, Modulation, Electromagnetism

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Proceedings Article | 20 July 2004 Paper

Civionics specifications for fiber optic sensors for structural health monitoring

Evangeline Rivera, Aftab Mufti, Douglas Thomson

Proceedings Volume 5393, (2004) https://doi.org/10.1117/12.548117

KEYWORDS: Sensors, Fiber optics sensors, Structural health monitoring, Bridges, Fiber Bragg gratings, Connectors, Optical fiber cables, Civil engineering, Fiber reinforced polymers, Structural engineering

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Proceedings Article | 4 November 2002 Paper

Dynamic heterodyned polarization imaging: a scanning probe technique for studying polarization dynamics in materials

Derek Oliver, Anle Pu, Douglas Thomson, Greg Bridges

Proceedings Volume 4809, (2002) https://doi.org/10.1117/12.450482

KEYWORDS: Dielectric polarization, Polarization, Electrodes, Acoustics, Dielectrics, Modulation, Heterodyning, Scanning probe microscopy, Ferroelectric materials, Polishing

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Showing 5 of 11 publications

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