Dr. Matthew Hobbs: from undergraduate student to lecturer in the Department of Electronic and Electrical Engineering

Please can you give us the brief story of your academic career so far, and give an overview of your current work at Sheffield? 

I did an MEng within Electronic Engineering at Sheffield, graduating in 2009, followed by a PhD in Electronic Engineering at Sheffield, graduating in 2014. My PhD degree involved the characterisation and application of various infrared photodetectors for non-contact temperature measurements.

I then worked as KTP Associate between the EEE department and a local company for three years, before returning as a PDRA in 2016. I have also worked as Teaching Associate within EEE since March 2021, where I try to incorporate examples of my research within my teaching to give students a wider view of the research that takes place here. From February 2023, I have been working as a Lecturer within Semiconductor Materials and Devices within EEE.

What is your current research focused on?

My current research focuses on the development of novel non-contact temperature measurement instruments and the use of such instrumentation within new applications including process monitoring and scientific characterisation. One such new application is the characterisation of blast events, which is the focus of this paper.

Can you please explain simply what your published paper is about? 

The characterisation of blast events, and how they impact structures, is critical for the development of infrastructure. It informs engineers ways in which to protect such infrastructure from events such as terrorist attacks. However, there is a lack of high quality data regarding the characterisation blast events which take place within a confined space, in part due to the lack of suitable measurement instrumentation. This is where my research comes in. By incorporating a custom, high-speed, non-contact infrared radiation thermometer within a confined blast event measurement setup, the temperature of the fireball can be accurately characterised. By combining my new approach with traditional pressure gauges, new information can be elucidated regarding the early stages of fireballs as they expand and develop. 

What interests you about this area of research? 

This particular research interests me because it allowed me to take my research and experience within non-contact temperature measurements and apply it within a new application. When taking the measurements on site, it was particularly exciting when the results from my instrumentation matched what was expected from the temperature inferred from the pressure gauge measurements. This validated the use of the approach, indicating that non-contact temperature measurement instrumentation is a valuable new tool for the characterisation of confined blast loads. 

Can you tell us about the team who worked on this paper?

My research takes place within the Sensor Systems group within EEE, which is headed up by Prof. Jon Willmott. For this project, we worked closely with the Blast and Impact group within the department of Civil and Structural Engineering at Sheffield, led by Prof. Andy Tyas and Prof. Sam Clarke. By working closely together, we were able to develop instrumentation capable of measuring the temperature of a confined blast event. Such research would not have been possible without the mutual expertise of the two research groups; we were able to apply our novel research within temperature measurements within their novel application of blast load characterisation.

Please can you explain what 'blast loading' means? 

In order to better understand the effect a particular blast event has on specific structures, the blast loading needs to be characterised. This can be characterised based upon the type of explosive being detonated, the amount of explosive being detonated, the environment the explosion is detonated with and the distance the target is from the detonation. This fundamental understanding has allowed us to estimate the size of e.g. the Beirut explosion to help engineers to develop a better understanding of the damage caused in complex urban environments.

What are the problem/s you were focusing on in this paper? 

The primary motivation behind this work was to develop a new form of instrumentation for the characterisation of confined blasts loads, specifically through the non-contact measurement of temperature. The aim is to overcome the lack of high quality measurement instrumentation, and hence measurement data.

How does the Infrared Radiation Thermometer help overcome this problem/s? 

Traditional pressure gauges measure pressure, not temperature. Therefore, to infer temperature from a pressure gauge measurement is based upon ideal gas laws. To do this, an assumption needs to be made that ideal gas laws hold true throughout the whole duration of the blast event, which may not be the case. In contrast, Infrared Radiation Thermometers infer temperature based upon the infrared radiation emitted from an object; this can be directly calibrated to temperature. In addition, our measurement approach is faster and less noisy; it therefore provides a better measurement of temperature than is possible with a pressure gauge through the full duration of the blast event.   

What are the potential future uses for your results / what are the implications of this study? 

Several of these instruments have been created for use by the Blast and Impact Group. This will enable tests to be performed at multiple locations within the fireball, and are capable of measuring higher target temperature than those investigated within this study. This will allow numerous different explosives and blast conditions to be assessed and investigated. Aside from blast measurements, we are looking for opportunities to apply this instrumentation within other applications which involve inherently fast transient events; particularly within research that is taking place elsewhere within the University of Sheffield.

What are your future career plans? 

I would like to further expand my research within non-contact temperature measurement by applying it within new and exciting applications. I would like to "push the boundaries" of what is possible in terms of acquisition rate; we have a new PhD student who is currently  investigating this. It would be fascinating to see what new applications such high-speed temperature measurements could benefit. For example, if we could significantly increase the speed of the instrumentation used within this blast measurement, it would be interesting to see what else might we learn from a fundamental science point of view at various points within the fireball as it expands and develops.