Performance comparison for the detection of defects in thermal insulating materials using microwave holograms acquired manually and with a robotized scanner

ABSTRACT

In many cryogenic systems, during useful life, defects or degradation of performance are found. Frequently these malfunctions are due to the presence of alterations in the characteristics of the thermal insulating materials used to coat the metal parts of the system. It is useful to evaluate methods for investigating the quality of insulating coatings by means of instruments, with low cost, that can be easily used during production. Thermal insulating materials are characterized by a relative dielectric constant close to the unit and a low Loss Factor: this work aims to investigate the use of microwave holographic radar for the detection of defects in such materials. The results show good detectability of defects when they are oriented as the antenna axis. Finally, it is shown that the robotic scan can examine large areas with the same detection performances of manual scan but with less set up and scanning time.

KEYWORDS:

• Microwave holograms
• holographic radar
• cryogenic industry
• thermal insulating material
• robotic scanner
• non-destructive testing

Acknowledgement

The authors also wish to acknowledge Dr. Ing. Joerg Stelzer of BSH Hausgeräte GmbH, Germany, for providing the thermal insulation samples for experiments.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Luca Bossi http://orcid.org/0000-0003-0093-1713

Pierluigi Falorni http://orcid.org/0000-0001-5523-9375

Lorenzo Capineri http://orcid.org/0000-0003-4432-3197

Additional information

Notes on contributors

Luca Bossi

Luca Bossi was born in Prato, Tuscany, Italy, in 1973. He received the M.S. degree in Electronic Engineering from the University of Florence, in Florence in 2018 and is a PhD student in Information Engineering at University of Florence from the same year. He has owned a commercial business and worked as an entrepreneur since 1996. From 2017 to 2018, he got a research grant from the Department of Information Engineering of the University of Florence to develop algorithms to improve the quality of information contained in microwave subsurface holographic radar images. He worked on an international research project in collaboration with NATO SPS. He is the co-author of eight scientific articles. His research interests include microwaves, penetrating radars, Industry 4.0 and non-destructive testing. He has dealt with sensors and electronic devices for diagnostics on wooden structures and cultural heritage infested from xylophagous insects.

Pierluigi Falorni

Pierluigi Falorni. Collaboration with University of Florence. Date 2001 – Present. Started a collaboration with the Department of Information Engineering of the University of Florence that is still in place today that mainly regards international humanitarian de-mining by processing the output of devices such as GPR and microwave holography systems. Collaborated with CNR (the Italian National Research Council) in the field of chlorophyll characterization by means of signal processing of satellite measurements in the oxygen lines range. Published 46 papers on international scientific journals and conference proceedings.

Lorenzo Capineri

Lorenzo Capineri received his degree in electronic engineering in 1988, his doctorate in non-destructive testing in 1993 and post-doctorate in 1994. In 1995, he became Associate Researcher and in 2004 Associate Professor of Electronics in the Department of Information Engineering. In 2017, he received the National Scientific Qualification as Full Professor in Electronics. His current research activities are in the design of ultrasonic guided waves devices, buried objects detection with ground penetrating radar and holographic radar. He has worked on several research projects in collaboration with national (Gilardoni spa) and international industries (National Semiconductors, Texas Instruments), and research institutions: the Italian Research Council (CNR), the Italian Space Agency (ASI) and the European Space Agency (ESA), AEA Technology and UKAEA (England), ISTC (International Science and Technology Centre) (Moscow, Russia), European Commission Joint Research Centre (ISPRA) and NATO (Brussels, Belgium). He is co-author of 6 Italian patents and co-author of 4 book chapters and about 200 scientific and technical papers. He is IEEE senior member since 2007 and member since 1983, co-chair of IWAGPR2015 conference and member of scientific and technical committee of GPR, PIERS and IGARSS conferences, Fellow of Electromagnetic Academy. He is also the delegate for International Relationships of the Department of Information Engineering of the University of Florence.