How many engineers do you need when the lights go out?

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An exemplar adverse outcome pathway for microplastics in aquatic species

From Galloway & Lewis, 2016

One to change the lightbulb and five to perform a Fault Tree Analysis (FTA).  A fault tree is a diagram that illustrates the relationship between failures at component and system levels.  Engineers use them to understand the mechanisms or logic that lead from component malfunctions to system breakdowns and to identify components that are critical to system reliability.  They are useful in optimizing designs, demonstrating compliance with safety requirements and as diagnostic tools when things go wrong.  There are some simple examples of fault trees for ‘no light in room’ and ‘missing the bus’ amongst others available from Visual Paradigm Online.  All of these examples illustrate qualitative relationships but we can also establish quantitative relationships using the rate of occurrence of each initiating event to arrive at a probability of failure (PoF) for the system.  There is an example for an indicator light in an automobile in a 2016 paper by Nabarun Das and William Taylor (see figure 2 in the paper).  An equivalent in biology are Adverse Outcome Pathways (AOPs) that identify the relationship between a molecular initiating event and a toxic effect through a series of key events.  For instance, microplastics causing altered gene expression and oxidative damage leading to altered fatty acid metabolism, stress response and altered cellular division resulting ultimately in population decline in aquatic species as shown in the graphic from a paper by Tamara Galloway and Ceri Lewis also published in 2016. Most AOPs are qualitative; however, quantitative Adverse Outcome Pathways (qAOPs) are starting to be developed as tools for quantitative risk assessment of chemicals.  Biologists and engineers are not using the same words, actually they are using entirely different vocabularies; nevertheless they are talking about the same methodologies.  An AOP network and an FTA are essentially the same concept and a probabilistic fault tree analysis is a quantitative adverse outcome pathway.  However, it seems unlikely that either biologists or engineers will adopt the language used by the other so they will be reliant on a few foolhardy interlocutors prepared to cross the discipline boundaries and highlight the opportunities for cross-fertilization of ideas and solutions.

Sources

Das N, Taylor W. Quantified fault tree techniques for calculating hardware fault metrics according to ISO 26262. In2016 IEEE Symposium on Product Compliance Engineering (ISPCE), pp. 1-8. IEEE, 2016. Also available at https://incompliancemag.com/article/quantified-fault-tree-techniques-for-calculating-hardware-fault-metrics-according-to-iso-26262/

Galloway TS, Lewis CN. Marine microplastics spell big problems for future generations. Proceedings of the national academy of sciences. 113(9):2331-3, 2016.

Slicing the cake equally or engineering justice

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Decorative photograph of sliced chocolate cakeIn support of the research being performed by one of the PhD students that I am supervising, I have been reading about ‘energy justice’.  Energy justice involves the equitable sharing of the benefits and burdens of the production and consumption of energy, including the fair treatment of individuals and communities when making decisions about energy.  At the moment our research is focussed on the sharing of the burdens associated with energy production and ways in which digital technology might improve decision-making processes.  Justice incorporates the distribution of rights, liberties, power, opportunities, and money – sometimes known as ‘primary goods’.  The theory of justice proposed by the American philosopher, John Rawls in the 1970’s is a recurring theme: that these primary goods should be distributed in a manner a hypothetical person would choose, if, at the time, they were ignorant of their own status in society.  In my family, this is the principle we use to divide cakes and other goodies equally between us, i.e., the person slicing the cake is the last person to take a slice.  While many in society overlook the inequalities and injustices that sustain their privileged positions, I believe that engineers have a professional responsibility to work towards the equitable distribution of the benefits and burdens of engineering on the individuals and communities, i.e., ‘engineering justice’ [see ‘Where science meets society‘ on September 2nd, 2015].  This likely involves creating a more diverse engineering profession which is better equipped to generate engineering solutions that address the needs of the whole of our global society [see ‘Re-engineering engineering‘ on August 30th, 2017].  However, it also requires us to rethink our decision-making processes to achieve  ‘engineering justice’.  There is a clear and close link to ‘procedure justice’ and ‘fair process’ [see ‘Advice to abbots and other leaders‘ November 13th, 2019] which involves listening to people, making a decision, then explaining the decision to everyone concerned.  In our research, we are interested in how digital environments, including digital twins and industrial metaverses, might enable wider and more informed involvement in decision-making about major engineering infrastructure projects, with energy as our starting point.

Sources:

Derbyshire J, Justice, fairness and why Rawls still matters today, FT Weekend, April 20th, 2023.

MacGregor N, How to transcend the culture wars, FT Weekend, April 29/30th, 2023.

Rawls J, A Theory of Justice, Cambridge MA: Belknap Press, 1971

Sovacool BK & Dworkin MH, Global Energy Justice: Problems, Principles and Practices, Cambridge: Cambridge University Press, 2014.

Image: https://www.alsothecrumbsplease.com/air-fryer-chocolate-cake/

Reasons I became an engineer: #3

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Decorative image of photoelastic fringe pattern in section of jet engine componentThis is third in a series of posts reflecting on my path to becoming an engineer.  In the previous one, I described how I left the Royal Navy and became a research assistant at the University of Sheffield in the Department of Mechanical Engineering [see ‘Reasons I became an engineer: #2’ on May 3rd, 2023].  My choice of research topic was dictated by the need for a job because I had to buy myself out of the Royal Navy after they had sponsored my undergraduate degree and I needed a salary to allow me to make the monthly payments.  So, I accepted the first job that was offered when I went back to the University to talk about my options.  I worked on investigating the load and stress distributions in threaded connections with a view to designing bolted joints that would be lighter, stronger and with a longer life.  We used a combination of finite element modelling [see ‘Did cubism inspire engineering analysis?’ on January 25th 2017] and three-dimensional photoelasticity, which is an experimental technique that has fallen out of fashion [see ‘Art and Experimental Mechanics’ on July 17th, 2012].  I was fortunate because all of my work as a research assistant went into my PhD thesis which although not ground-breaking resulted in several journal papers [see ’35 years later and still working on a PhD thesis’ on September 16th 2020] and, with the help of personal contacts, a post-doctoral fellowship at the Medical School at the University of Calgary, Canada.  In Calgary, I worked on the design of experiments to measure the stress in the pericardium, which is a sac that surrounds the heart – still engineering but a major shift in focus from industrially-focussed mechanical engineering toward biomedical engineering.

Image: Fringe pattern in section of photoelastic model of jet engine showing distribution of stress from Patterson EA, Brailly P & Taroni M, High frequency quantitative photoelasticity applied to jet engine components, Experimental Mechanics, 46(6):661-668, 2006.

Taking an aircraft’s temperature as a health check

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The title of this post is the title of a talk that I will deliver during the Pint of Science Festival in Liverpool later this month.  At last year’s festival I spoke about the very small: Revealing the invisible: real-time motion of virus particles [see ‘Fancy a pint of science‘ on April 27th, 2022].  This year I am moving up the size scale and from biomedical engineering to aerospace engineering to talk about condition monitoring in aircraft structures based on our recent research in the INSTRUCTIVE [see ‘INSTRUCTIVE final reckoning‘ on January 9th 2019] and DIMES [see ‘Our last DIMES‘ on September 22, 2021] projects.  I am going describe how we have reduced the size and cost of infrared instrumentation for monitoring damage propagation in aircraft structures while at the same time increasing the resolution so that we can detect 1 mm increments in crack growth in metals and 6 mm diameter indications of damage in composite materials.  If you want to learn more how we did it and fancy a pint of science, then join us in Liverpool later this month for part of the world’s largest festival of public science.  This year we have a programme of engineering talks on Hope Street in Frederiks on May 22nd and in the Philharmonic Dining Rooms on May 23rd where I be the second speaker.

The University of Liverpool was the coordinator of the DIMES project and the other partners were Empa, Dantec Dynamics GmbH and Strain Solutions Ltd.  Strain Solutions Limited was the coordinator of the INSTRUCTIVE project in which the other participant was the University of Liverpool.  Airbus was the project manager for both projects.

The DIMES and INSTRUCTIVE projects  received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 820951 and 6968777 respectively.

The opinions expressed in this blog post reflect only the author’s view and the Clean Sky 2 Joint Undertaking is not responsible for any use that may be made of the information it contains.