I am in the midst of marking examination scripts. I have about two weeks to award a maximum of about 26,000 marks which is a huge number of decisions to make in a relatively short time [see ‘Depressed by exams‘ on January 31st 2018]. Although the pile of examination scripts is tall and the task can feel overwhelming, it represents a return to normality following the pandemic when we conducted on-line, open-book examinations [see ‘Limited bandwidth’ on June 2nd, 2021]. We have been teaching 100% on-campus for the whole semester and all of our examinations have returned to their pre-pandemic format, i.e., the majority have been in-person, closed-book and invigilated. I have enjoyed teaching thermodynamics in a huge lecture-theatre filled with students and it is relief that I do not have to set examination questions whose answers cannot be found using a search engine or solved using a programme. Anyway I need to pick up my red pen and return to my marking so only a brief post this week.
At the end of a lecture on energy flows in my first year undergraduate course on thermodynamics, I talk about nozzles and diffusers as examples of practical applications of the rest of the material in the lecture. It is hazardous to sit in the front row of the lecture theatre because I take in a water bottle with a trigger spray to demonstrate how the nozzle increases the velocity of the fluid at the expense of pressure while gently sprinkling water on the front row. I am always intrigued by the symmetry of nozzles and diffusers. Diffusers increase pressure of a fluid at the expense of its velocity, i.e., a mirror image of the action of a nozzle. The cross-sections are also mirror images because a nozzle has a cross-section that decreases in the flow direction while a diffuser has a cross-section that increases in the flow direction. At least for sub-sonic flows, because the shapes are reversed for super-sonic flow; so a sub-sonic nozzle looks like a super-sonic diffuser and a sub-sonic diffuser looks like a super-sonic nozzle. If that all sounds like fluid mechanics then the thermodynamic message is that, in nozzles and diffusers, the rates of heat and work transfer are approximately zero while the change in the kinetic energy of the fluid is very large. I finish the lecture with a video clip of a school quartet of trombones playing ‘Stars and Stripes Forever’ which wakes up the students who have slept through the lecture and allows me to point out the diffusers (bell of the trombone) transmitting acoustic pressure.
You can watch the video clip on YouTube at https://www.youtube.com/watch?v=mHw8P8NnUvI
I mentioned a couple of weeks ago that I am teaching thermodynamics at the moment [see ‘Conversations about engineering over dinner and a haircut‘ on February 16th, 2022]. I am using a blended approach [see ‘ Blended learning environments‘ on November 14th, 2018] to deliver the module to more than 300 first year undergraduate students with one hour in the lecture theatre each week while the students follow the components of the MOOC I developed some years ago [see ‘Free: Energy! Thermodynamics in Everyday Life‘ on November 11th, 2015, and ‘Engaging learners online‘ on May 25th, 2016]. I have found that first year undergraduates are reluctant to participate in the online discussions that are part of the MOOC and so last year I asked them to discuss each topic in small groups with their academic tutor. I got some very positive feedback from tutors who had interesting and stimulating discussions with their students. We are repeating the process again this year. The first discussion is about energy transformations: noting that energy is always conserved but constantly transformed into different forms, each student is asked to start from an energy state of their choice and to trace the transformations backwards until they can go no further. In the lecture preceding the discussion with their tutor I provide some examples for starting states, including breakfast cereal, a pole vaulter in mid-jump and a bullet train. I also describe the series of transformations from the Big Bang to tectonic plate movement: after the initial expansion caused by the Big Bang, the universe cooled sufficiently to allow the formation of sub-atomic particles followed by atoms of hydrogen and some helium and lithium that gravity caused to coalesce into clouds which became the early stars, or solar nebula. A crust formed on the solar nebula which broke away to form planets. Our planet has a molten core with temperatures varying from 4,400 to 6000 degrees Celsius, compared to around 5,500 degrees on the surface of the sun. The temperature variation in the Earth’s core cause thermal currents which drive the movement of tectonic plates and so on [see ‘The hills are shadows, and they flow from form to form, and nothing stands‘, on February 9th, 2022]. Most chains of energy transformation lead backwards to the sun and forwards to dissipation of energy into some unusable form which we might call ‘entropy’ [see ‘Life-time battle‘ on January 30th, 2013].
Recently, over dinner, someone I had just met asked me what type of engineering I do. I always find this a difficult question to answer because I am sure that they are just being polite and do not want to hear any technical details but I find it hard to give an interesting answer without diving into details. Earlier the same day I had given a lecture on thermodynamics to about 300 undergraduate students so I told my inquisitor about this experience and explained that thermodynamics was the science of energy and its transformation into different forms. Then, I muttered something about being interested in making and using measurements to ensure that computational models of aircraft and nuclear power stations are reliable and the conversation quickly moved on. A week or so earlier, I was having my hair cut when the barber asked me a similar question about what I did and I told him that I was a professor of engineering which led to a conversation about robots. We speculated about whether we would ever lose our jobs to robots and decided that we were both fairly secure against that threat. There is a high degree of creativity in both of our roles – while I always ask for the same haircut, my hair is in a different state every time I visit the barbers’ and I leave looking slightly different every time. I don’t think that I would like the uniformity that a row of robots in the barbers’ shop might produce. And, then there is the conversation during the haircut. A robot would need to pass the Turing test, i.e., to exhibit intelligent behaviour indistinguishable from a human, which no computer has yet achieved or is likely to do so in our lifetime, at least not a cost that would allow them to replace barbers. The same holds for professors – the shift to delivering lectures online during the pandemic might have made some professors worry that their jobs were at risk as recorded lectures replaced live performances; however, student feedback tells us that students have a strong preference for on-campus teaching and the high turnout for my thermodynamics lectures supports that conclusion.
For a new website I was asked to describe my research interests in about 25 words and used the following: ‘the acquisition of information-rich measurement data and its use to develop digital representations of complex systems in the aerospace, biological and energy sectors’. Fine for a website but not dinner conversation!
There have been some attempts to build a robot that cut your hair, for example see this video.
Image shows a colour contour map describing the shape of a facemask produced using fringe projection which could be used as part of the vision system for a robotic barber. For more information on fringe projection see: Ortiz, M. H., & Patterson, E. A. (2005). Location and shape measurement using a portable fringe projection system. Experimental mechanics, 45(3), 197-204 or watch this video from the INDUCE project that was active from 1998 to 2001.