Airborne urban mobility

Pop.Up_copyright Italdesign 2

At the Airbus PhD workshop that I attended a couple of weeks ago [see my post entitled Making Engineering Work for Society on September 13th 2017], Axel Flaig, Head of Airbus Research and Technology, gave us an excellent opening presentation describing their vision for the future.  Besides their vision for the next generation of passenger aircraft with reductions in CO2, NOx and noise emissions of 75%, 90% and 65% respectively against 2000 levels by 2050, they are also looking at urban air mobility.  We have 55 megacities [cities with a population of more than 10 million] and it is expected that this will increase to 93 by 2035 [see my post entitled ‘Hurrying Feet in Crowded Camps’ on August 16th, 2017].  These megacities are characterized by congestion and time-wasted moving around them; so, Airbus is working on designs for intra-city transport that takes us off the roads and into the air.  Perhaps the most exciting is the electric Pop.up concept that is being developed with Italdesign.  But, Airbus are beyond concepts: they have a demonstrator single-seater, self-pilot vehicle, the Vahana that will fly in 2017 and a multi-passenger demonstrator scheduled to fly in 2018.

Soon, we will have to look left, right and up before we cross the road, or maybe nobody will walk anywhere – though that would be bad news for creative thinking [see my post on ‘Gone Walking’ on 19th April 2017], amongst other things!


Image from http://www.airbus.com/newsroom/press-releases/en/2017/03/ITALDESIGN-AND-AIRBUS-UNVEIL-POPUP.html where there is also a video.


Hurrying feet in crowded camps

Five years ago I wrote about the potential ‘Population Crunch‘ [September 15th, 2012] that could lead to a large increase in the size and number of cities – perhaps upto 1500 new cities emerging over the next few decades as the global population rises from 7.6 billion to 9.8 billion by 2050 [see UN revised report, 2017].  It is a significant challenge to provide an acceptable quality of life to the citizens of these new cities as well as existing ones.  People have been concerned about the density of population in cities and its impact on individuals for more than a century.  In 1910, W.H. Hudson in ‘A Shepherd’s Life’ [Penguin Books, 1910] wrote, somewhat tongue-in-cheek, about London: ‘Some over-populated planet in our system discovered a way to relieve itself by discharging its superfluous millions on our globe – a pale people with hurrying feet and eager, restless minds, who live apart in monstrous, crowded camps, like wood ants that go not out to forage for themselves’  Nothing seems to have changed!

Uncertainty about Bayesian methods

I have written before about why people find thermodynamics so hard [see my post entitled ‘Why is thermodynamics so hard?’ on February 11th, 2015] so I think it is time to mention another subject that causes difficulty: statistics.  I am worried that just mentioning the word ‘statistics’ will cause people to stop reading, such is its reputation.  Statistics is used to describe phenomena that do not have single values, like the height or weight of my readers.  I would expect the weights of my readers to be a normal distribution, that is they form a bell-shaped graph when the number of readers at each value of weight is plotted as a vertical bar from a horizontal axis representing weight.  In other words, plotting weight along the x-axis and frequency on the y-axis as in the diagram.

The normal distribution has dominated statistical practice and theory since its equation was first published by De Moivre in 1733.  The mean or average value corresponds to the peak in the bell-shaped curve and the standard deviation describes the shape of the bell, basically how fat the bell is.  That’s why we learn to calculate the mean and standard deviation in elementary statistics classes, although often no one tells us this or we quickly forget it.

If all of you told me your weight then I could plot the frequency distribution described above.  And, if I divided the y-axis, the frequency values, by the total number of readers who sent me weight information then the graph would become a probability density distribution [see my post entitled ‘Wind power‘ on August 7th, 2013].  It would tell me the probability that the reader I met last week had a weight of 70.2kg – the probability would be the height of the bell-shaped curve at 70.2kg.  The most likely weight would correspond to the peak value in the curve.

However, I don’t need any of you to send me your weights to be reasonably confident that the weight of the reader I talked to last week was 70.2kg!  I cannot be certain about it but the probability is high.  The reader was female and lived in the UK and according to the Office of National Statistics (ONS) the average weight of women in the UK is 70.2kg – so it is reasonable to assume that the peak in the bell-shaped curve for my female UK readers will coincide with the national distribution, which makes 70.2kg the most probable weight of the reader I met last week.

However, guessing the weight of a reader becomes more difficult if I don’t know where they live or I can’t access national statistics.  The Reverend Thomas Baye (1701-1761) comes to the rescue with the rule named after him.  In Bayesian statistics, I can assume that the probability density distribution of readers’ weight is the same as for the UK population and when I receive some information about your weights then I can update this probability distribution to better describe the true distribution.  I can update as often as I like and use information about the quality of the new data to control its influence on the updated distribution.  If you have got this far then we have both done well; and, I am not going lose you now by expressing Baye’s law in terms of probability, or talking about prior (that’s my initial guess using national statistics) or posterior (that’s the updated one) distributions; because I think the opaque language is one of the reasons that the use of Bayesian statistics has not become widespread.

By the way, I can never be certain about your weight; even if you tell me directly, because I don’t know whether your scales are accurate and whether you are telling the truth!  But that’s a whole different issue!

Our place in the web of life

140-4032_IMGThe seven billion human beings who live on this planet weigh in about 300 million tonnes in total and if you add in our domesticated animals then the scales would hit about 700 million tonnes. Whereas if you weighed all of the animals left in the wild then their total weight would be less than 100 million tonnes, according to Yuval Noah Harari in his book ‘Sapiens: a brief history of mankind’. This explains why many of our landscapes appear empty and barren – they are, at least at the level of large mammals. That’s why you are unlikely to be chased by a tiger or any other predator, see last week’s post entitled ‘Running away from tigers’.

These landscapes are not really barren. We just can’t see what is there. Bacteria are too small for us to see but they have dominated the landscape for most of evolutionary time. They ‘invented’ all of life’s essential biotechnologies including fermentation, photosynthesis, nitrogen fixation, respiration and devices for rapid motion plus probably a few we have haven’t discovered yet. Bacteria exchange up to 15% of their genetic material on a daily basis across all strains so that they could be considered to form a single microscopic web of life.

This web of bacterial life is all around us as well as inside us. If you like to learn more than you probably ever want to know about the bacteria inside us then read Giulia Enders’book ‘Gut: The inside story of our bodies most underrated organ’. We are not alone in being immersed in this web of bacterial life; so is every other living thing which implies we are all intimately connected in a vast ecological network. This microbial web of life in which we are embedded is self-organising – there are no leaders, presidents, generals or CEOs – instead bacteria empower one another. It appears to be one of the secrets of their success.

In an interconnected world, power and control over others in a hierarchy is less appropriate than empowering one another in the network. Many people would find this approach difficult because they identify themselves with their position of power and, hence would tend to resist any attempt to empower the network. To them it begins to sound like anarchy, particularly in the narrow context of human society, but others might suggest it offers a better prospect for addressing the challenges posed by global climate change than world leaders have so far proposed. Well-informed individuals intimately connected in a network are likely to take decisions that support the network, and hence themselves. But, now we are straying into game theory…


Yuval Noah Harari, Sapiens: A brief history of mankind. London: Vintage (Penguin, Random House), 2014.

Capri F. & Luisi, P.L., The systems view of life: a unifying vision. Cambridge: Cambridge University Press, 2014.

Enders, G, Gut: the inside story of our bodies most underrated organ. Vancouver: Greystone Books, 2013.

70,000 trees needed


backyard‘70,000 trees needed to print graduation papers’.  This was a headline that I spotted in the China Daily (Thursday 24th April, 2014) while I was travelling in China last moth.  The article reported that the trees would be cut down to provide the graduation papers for this year’s 7.27 million university graduates in China.  Superficially, these are very large numbers, both of trees and graduates.  However,  China has a population of 1.38 billion, which is almost 20% of the global population, so the annual graduation rate is only about 0.5% of the population compared to about 1% in England.  There are concerns in China that there are insufficient graduate-level jobs for all of the students graduating this year, which is a familiar situation in the UK.  The idea of following the Finnish approach to higher education, with more universities of applied sciences than multi-disciplinary universities, is gaining ground in China.  In the UK, EngineeringUK has estimated the number of engineering graduates needs to double by 2020 in order to sustain our engineering industry whose turnover was £1.1 trillion in 2011-12, or 24.5% of UK turnover. The shortage of engineering graduates is reflected in average starting salaries that are 20% higher than for all graduate.

Back to those 70,000 trees; they would absorb between 2 and 20 kg of carbon dioxide per tree per year if they were not felled for the graduation papers.  Carbon dioxide sequestration by trees depends on their size, age and species, see for example the sources below.  The CO2 emissions in China are currently about 7  tonnes per capita, which is about the same as the UK and about 40% of the per capita emissions in the USA, according to the EDGAR or the World Bank, so that means that 70,000 trees might balance the emissions of between 20 and 200 graduates, i.e not many of the 7.27 million!