Katherine Kirk | University of the West of Scotland (UWS) (original) (raw)
Papers by Katherine Kirk
Applied Physics Letters, 2001
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Résumé/Abstract The Superconducting QUantum Interference Device, or SQUID, is the most sensitive ... more Résumé/Abstract The Superconducting QUantum Interference Device, or SQUID, is the most sensitive detector of magnetic fields. As such, a potential use is in electromagnetic NDT. Although its impact has so far been limited by the impracticality and cost of systems ...
2002 IEEE Ultrasonics Symposium, 2002. Proceedings., 2002
The synthetic aperture focusing (SAF) technique allows exploration of ultrasonic array imaging pe... more The synthetic aperture focusing (SAF) technique allows exploration of ultrasonic array imaging performance with minimal hardware and it can provide excellent imaging results for point defects, such as fatigue crack tips, commonly found in non-destructive testing (NDT). However, it performs less well when imaging defects which are flat or curved with radii large relative to the ultrasonic wavelength. Here, we report an enhanced time-domain algorithm which can deal with flat and curved defects and which we have termed "synthetic aperture correlation". It is based on processing signals from multiple overlapping subsets of elements from an entire array. The algorithm has roots in SAF, matched filtering, beam steering and biomedical ultrasonic imaging. The data collection process is the same as for SAF and the new algorithm operates entirely in reception, off-line. It has been tested using a 96-element linear array operating at 6 MHz on aluminum test objects. We present simulated and experimental results and compare these with B-scans showing timer-of-flight diffraction (TOFD) characteristics and with conventional SAF. We highlight the advantages of the new algorithm, such as its enhanced capability to deal with noise, and drawbacks such-as increased computational expense.
2007 IEEE Ultrasonics Symposium Proceedings, 2007
2002 IEEE Ultrasonics Symposium, 2002. Proceedings., 2002
... CK Lee, F. Placido, S. Cochran and KJ Kirk School of Information and Communication Technologi... more ... CK Lee, F. Placido, S. Cochran and KJ Kirk School of Information and Communication Technologies, University of Paisley, Paisley, PA1 2BE ... CK Lee would like to thank the University of Paisley for the studentship and funding for this research. REFERENCES ...
IEEE Ultrasonics Symposium, 2005., 2005
ABSTRACT Not Available
We describe the design and fabrication of ultrasonic transducers for the high frequency range 50-... more We describe the design and fabrication of ultrasonic transducers for the high frequency range 50-100MHz. Y/36°-cut single crystal lithium niobate was used as the active material. A bonded copper substrate was used to improve manufacturability. The behaviour of transducers was investigated with different thicknesses of lithium niobate, with and without the bonded copper substrate. Time-domain results are presented to compare the performance. Although the copper substrate enabled transducers with a thinner lithium niobate to be more easily manufactured, they exhibited some ringing in the copper layer. Results showed that use of a tungsten-loaded epoxy backing layer was most effective in reducing the ringing, compared to Araldite epoxy as a backing layer.
IEEE Transactions on Applied Superconductivity, 1993
The superconducting proximity effect can be used to produce Josephson junctions in high-temperatu... more The superconducting proximity effect can be used to produce Josephson junctions in high-temperature superconducting structures with a normal conducting carrier. The authors describe work on edge-microbridge junctions made by defining 10-30-micron-wide Au bridges to link the upper and lower layers of a YBa2Cu3O(7-delta)-Y2O3-YBa2Cu3O(7-delta) trilayer. The structures are patterned by photolithography and ion milling from multilayers grown in situ by electron-beam
IEEE Ultrasonics Symposium, 2004, 2004
IEEE Ultrasonics Symposium, 2004, 2004
This paper reports 2-layer piezocomposite elements for high-density arrays operating in the 1-5 M... more This paper reports 2-layer piezocomposite elements for high-density arrays operating in the 1-5 MHz range. Investigation in air without any ancillary acoustic components highlighted undesirable effects, showing that pillar misalignment led to extraneous twisting modes. In practical use, such elements include matching and backing layers, and the effects of acoustic loading must also be considered. Therefore, we report here on work to quantify the influence of pillar misalignment for a complete transducer operating in water. To evaluate performance, our analysis includes electrical impedance data and measurements of the transmit-receive transfer function which relates to device performance in practical situations. We present results from finite element analysis incorporating unidirectional and bidirectional pillar misalignments from 0% to the maximum possible. These results are validated with data from a prototype two-layer 1-3 piezocomposite transducer tested in air and underwater. We comment on the degree of acceptable pillar misalignment compared with previous studies.
Magnetic Hysteresis in Novel Magnetic Materials, 1997
ABSTRACT
Insight - Non-Destructive Testing and Condition Monitoring, 2015
2007 IEEE Ultrasonics Symposium Proceedings, 2007
Ultrasonics, 2002
We have designed, manufactured and tested a piezoelectric composite material to operate at temper... more We have designed, manufactured and tested a piezoelectric composite material to operate at temperatures above 400 degrees C. The material is a 1-3 connectivity composite with pillars of Z-cut lithium niobate in a matrix of alumina cement. The composite material produced shorter pulses than a monolithic plate of lithium niobate and remained intact upon cooling. Results are presented from room temperature and high temperature testing. This material could be bonded permanently to a test object, making it possible to carry out condition monitoring over an extended period. A new excitation method was also developed to enable remote switching between array elements.
IEEE Ultrasonics Symposium, 2005., 2005
The use of ultrasonic array transducers for non- destructive testing is presently growing rapidly... more The use of ultrasonic array transducers for non- destructive testing is presently growing rapidly, supported by the introduction of several new commercial array controllers. However, practical problems with the flexibility of 1D arrays have been realized. For example, it is impossible to skew the beam on curved surfaces without losing acoustic coupling. As 2D ultrasonic arrays allow 3D beam steering,
Applied Physics Letters, 2001
... RRRRR R RRRRRRRRRRRRRRRRRRRRR RRRR R RRRRRRRRRRRRRRRRRRRRR ... R RRRRRRRRRRRRRRRRR R RRRRRRRR... more ... RRRRR R RRRRRRRRRRRRRRRRRRRRR RRRR R RRRRRRRRRRRRRRRRRRRRR ... R RRRRRRRRRRRRRRRRR R RRRRRRRRRRRRRRRR R RRRRRRRRRRRRRRR R RRRRRRRRRRRRRR R RRRRRRRRRRRRR R RRRRRRRRRRRR R RRRRRRRRRRR R ...
Résumé/Abstract The Superconducting QUantum Interference Device, or SQUID, is the most sensitive ... more Résumé/Abstract The Superconducting QUantum Interference Device, or SQUID, is the most sensitive detector of magnetic fields. As such, a potential use is in electromagnetic NDT. Although its impact has so far been limited by the impracticality and cost of systems ...
2002 IEEE Ultrasonics Symposium, 2002. Proceedings., 2002
The synthetic aperture focusing (SAF) technique allows exploration of ultrasonic array imaging pe... more The synthetic aperture focusing (SAF) technique allows exploration of ultrasonic array imaging performance with minimal hardware and it can provide excellent imaging results for point defects, such as fatigue crack tips, commonly found in non-destructive testing (NDT). However, it performs less well when imaging defects which are flat or curved with radii large relative to the ultrasonic wavelength. Here, we report an enhanced time-domain algorithm which can deal with flat and curved defects and which we have termed "synthetic aperture correlation". It is based on processing signals from multiple overlapping subsets of elements from an entire array. The algorithm has roots in SAF, matched filtering, beam steering and biomedical ultrasonic imaging. The data collection process is the same as for SAF and the new algorithm operates entirely in reception, off-line. It has been tested using a 96-element linear array operating at 6 MHz on aluminum test objects. We present simulated and experimental results and compare these with B-scans showing timer-of-flight diffraction (TOFD) characteristics and with conventional SAF. We highlight the advantages of the new algorithm, such as its enhanced capability to deal with noise, and drawbacks such-as increased computational expense.
2007 IEEE Ultrasonics Symposium Proceedings, 2007
2002 IEEE Ultrasonics Symposium, 2002. Proceedings., 2002
... CK Lee, F. Placido, S. Cochran and KJ Kirk School of Information and Communication Technologi... more ... CK Lee, F. Placido, S. Cochran and KJ Kirk School of Information and Communication Technologies, University of Paisley, Paisley, PA1 2BE ... CK Lee would like to thank the University of Paisley for the studentship and funding for this research. REFERENCES ...
IEEE Ultrasonics Symposium, 2005., 2005
ABSTRACT Not Available
We describe the design and fabrication of ultrasonic transducers for the high frequency range 50-... more We describe the design and fabrication of ultrasonic transducers for the high frequency range 50-100MHz. Y/36°-cut single crystal lithium niobate was used as the active material. A bonded copper substrate was used to improve manufacturability. The behaviour of transducers was investigated with different thicknesses of lithium niobate, with and without the bonded copper substrate. Time-domain results are presented to compare the performance. Although the copper substrate enabled transducers with a thinner lithium niobate to be more easily manufactured, they exhibited some ringing in the copper layer. Results showed that use of a tungsten-loaded epoxy backing layer was most effective in reducing the ringing, compared to Araldite epoxy as a backing layer.
IEEE Transactions on Applied Superconductivity, 1993
The superconducting proximity effect can be used to produce Josephson junctions in high-temperatu... more The superconducting proximity effect can be used to produce Josephson junctions in high-temperature superconducting structures with a normal conducting carrier. The authors describe work on edge-microbridge junctions made by defining 10-30-micron-wide Au bridges to link the upper and lower layers of a YBa2Cu3O(7-delta)-Y2O3-YBa2Cu3O(7-delta) trilayer. The structures are patterned by photolithography and ion milling from multilayers grown in situ by electron-beam
IEEE Ultrasonics Symposium, 2004, 2004
IEEE Ultrasonics Symposium, 2004, 2004
This paper reports 2-layer piezocomposite elements for high-density arrays operating in the 1-5 M... more This paper reports 2-layer piezocomposite elements for high-density arrays operating in the 1-5 MHz range. Investigation in air without any ancillary acoustic components highlighted undesirable effects, showing that pillar misalignment led to extraneous twisting modes. In practical use, such elements include matching and backing layers, and the effects of acoustic loading must also be considered. Therefore, we report here on work to quantify the influence of pillar misalignment for a complete transducer operating in water. To evaluate performance, our analysis includes electrical impedance data and measurements of the transmit-receive transfer function which relates to device performance in practical situations. We present results from finite element analysis incorporating unidirectional and bidirectional pillar misalignments from 0% to the maximum possible. These results are validated with data from a prototype two-layer 1-3 piezocomposite transducer tested in air and underwater. We comment on the degree of acceptable pillar misalignment compared with previous studies.
Magnetic Hysteresis in Novel Magnetic Materials, 1997
ABSTRACT
Insight - Non-Destructive Testing and Condition Monitoring, 2015
2007 IEEE Ultrasonics Symposium Proceedings, 2007
Ultrasonics, 2002
We have designed, manufactured and tested a piezoelectric composite material to operate at temper... more We have designed, manufactured and tested a piezoelectric composite material to operate at temperatures above 400 degrees C. The material is a 1-3 connectivity composite with pillars of Z-cut lithium niobate in a matrix of alumina cement. The composite material produced shorter pulses than a monolithic plate of lithium niobate and remained intact upon cooling. Results are presented from room temperature and high temperature testing. This material could be bonded permanently to a test object, making it possible to carry out condition monitoring over an extended period. A new excitation method was also developed to enable remote switching between array elements.
IEEE Ultrasonics Symposium, 2005., 2005
The use of ultrasonic array transducers for non- destructive testing is presently growing rapidly... more The use of ultrasonic array transducers for non- destructive testing is presently growing rapidly, supported by the introduction of several new commercial array controllers. However, practical problems with the flexibility of 1D arrays have been realized. For example, it is impossible to skew the beam on curved surfaces without losing acoustic coupling. As 2D ultrasonic arrays allow 3D beam steering,