Category Archives: Uncategorized

Flexible credit

vibrating rulerOne of the major credit card companies used to advertise their card as ‘your flexible friend’.  If you clamp your card over the edge of the table and flip it with your finger then it will vibrate at a resonant frequency which decreases with length of the overhang, or cantilever as engineers might call it.  You could say that your flexible friend can sing too.

I used to use a twelve-inch ruler as everyday example of free and forced vibrations until someone pointed out to me that most engineering students don’t carry them around any longer.  So the credit card is a nice alternative that everyone carries with them, although the embossed text of your name and account number makes them a little too stiff and you might find that your plastic driving licence works better.  Neither will produce middle C as well as a plastic twelve-inch ruler – you can calculate the resonant or natural frequency by equating the kinetic energy and strain energy of the cantilever, as illustrated in the attached 5E lesson plan.  For more on 5E lesson plans see: my post entitled ‘Disease of the modern age’ on June 26th, 2013 and ‘Sizzling Sausages’ on July 3rd, 2013.  By the way, kinetic energy is the energy possessed by an object due to its motion and strain energy is the energy stored in an object as result of elastic (reversible) deformation and is equal to the work done in producing the deformation.

5EplanNoD12_free&forcedvibrations

Chemical Imbalance

chemicalimbalance

Cover of the book to go with the film

 

 

 

 

 

 

 

 

 

 

A couple of weeks ago I blogged about population and its rapid rise (see ‘Population Control’ on September 25th, 2013).  Despite our burgeoning population many university engineering schools in the English-speaking world tend to recruit from only half the population, i.e. the male population.  Representation of females in engineering is woefully low, generally worse than in science.  To learn more how women feel about the situation in chemistry watch a short film called ‘A Chemical Imbalance’  – I highly recommend that you spare the 15 minutes to watch it at  http://chemicalimbalance.co.uk/

Go on do it now! The rest of this posting is boring stuff so watch the film which was made with support from the Royal Society.

In the film ‘the leaky pipeline’ is talked about in the context of women entering science and engineering not making it to the top.  Of course this is not unique to science and engineering; only about 20 of the Fortune 500 companies have a female CEO.  This is an important issue but the supply to the pipeline is a bigger problem.  Only 20% of the students awarded an A-level in Physics in the UK this year (equivalent to AP exams in the US) were female and since most university engineering programmes require Physics the supply of qualified women is almost decimated before it gets to the pipeline.  This year my school has taken the step of dropping the physics requirement and accepting that we will need to teach the necessary physics as part of our engineering courses; incidently we also raised the grades we require so this does not represent a lowering of standards!

Another sobering thought is that nearly half of co-education state schools in the UK had no females studying for A-level physics.  I don’t have statistics for the US but I suspect they would be the same.

Anne-Marie Slaughter, a political scientist at Princeton argues that ‘the way we view women [has] changed radically, [but] the way we view men not at all’ so that achieving further gender equality requires a cultural change about and by men, which is going to be tough in a male-dominated conservative profession like engineering but we have to do it.  So if you didn’t watch the film, do it now and think about how you can be an agent for change.

Sources:

http://www.bbc.co.uk/news/education-19603399

Eduardo Porter’s column ‘Economic Scene’ entitled ‘Is leaning in enough to fix the gender gap? in the New York Times on September 24th, 2013 see http://www.nytimes.com/2013/09/25/business/economy/for-american-women-is-it-enough-to-lean-in.html?ref=eduardoporter&_r=0

Detroit

978000655083970256Last week we drove from the south through downtown Detroit on Interstate 75.  Approaching from a distance along the shore of Lake Erie and the banks of the Detroit river, the city looks like many others in the US with glass-clad towers clustered together and stretching towards the clear blue sky.  Close-up and beyond the glass skyscrapers, Detroit offers a different view of derelict apartment blocks, factory buildings and offices covered in graffiti with weeds growing out of them.  These are not isolated buildings but whole city blocks.  It is reminiscent of Hadron in Doris Lessing’s book ‘Mara and Dann’, in which twenty-five towers built for city administrators are left abandoned in preference for fine houses in large gardens.  The mental picture that our drive brought to mind was from Lessing’s book; however, in searching out the book at home I remembered a similar image drawn by JG Ballard in ‘High Rise’ in which civilised life in a 42-storey degenerates as residents abandon all moral and social conventions and a hunter/gatherer culture of competing gangs developed.

Of course Detroit is infamous for having recently become the largest municipal bankruptcy when it filled for Chapter 9 Bankruptcy on July 18th, 2013.  However, not all is doom and gloom in Detroit; it might be suffering from entropic decay but they know how to conserve energy (available energy).  At Detroit  Metropolitan Airport they are replacing more than 6000 light fixtures with LED (light emitting diodes) lights in the parking structures (multi-storey car parks) as well as adding an extra thousand for a total cost of $6.2 million (£4M).  It is anticipated that the resultant reduction in energy consumption will be 7,345,000 kilowatt hours (kWh) worth about $1.2 million per year (£0.77M).  According to Ali Dib, Director of Infrastructure & Engineering for Wayne County Airport Authority, the energy saved by the light replacements will be “equivalent to powering 880 U.S. households for one year, and the reduction of 7,000 metric tons of CO2 per year is equal to taking 1,350 passenger vehicles off the road.” Not something they would be very happy about you doing in the ‘Motor Capital of the World’.  So the other way of looking at the CO2 production saved is that it is equivalent to  25,400,000 passenger air miles not flown or a thousand round-the-world flights.

Oh, and the LEDs will only need changing every ten years instead of every thirteen months for the current light bulbs.

For ‘Mara and Dann’ see: http://www.dorislessing.org/maraand.html And for reviews: http://www.nytimes.com/books/99/01/10/reviews/990110.10upch.html or http://www.theguardian.com/books/1999/may/29/books.guardianreview27

For ‘High Rise’ see: http://www.jgballard.ca/criticism/highrise.html

Information on changing light fixtures from The Metropolitan dEtroit, August 2013 (p.11) and http://www.themetropolitandetroit.com/

Passenger air miles CO2 production from http://www.transportdirect.info/Web2/JourneyPlanning/JourneyEmissionsCompare.aspx

I and the village

'I and the village' by Chagall

‘I and the village’ by Chagall

Last week’s post ended up a bit heavier, both in size and content, than I intend most posts to be so I thought this week’s should be short.

Recently, I visited the exhibition of Marc Chagall’s paintings at the Tate Liverpool and was particular inspired by ‘I and the Village’, which was painted in Paris in 1911 although Chagall was born in a small village in Belarus.  Apparently, the painting signifies the interconnectivity of human life and the surrounding natural world – notice the fine line connecting the eyes of the peasant and the animal also the peasant holding a sprig of a tree.  The orbits of the earth and moon are suggested by the circular shapes in the painting, which perhaps also represent the cyclical nature of life.

As you might guess from my posts over the last year, these ideas resonant with my own approach to our interaction with the earth and the natural resources available to us.  I like the layers of connections and interacting activities illustrated in the painting, including many that are not immediately obvious, just as in life.

The painting is part of the collection of the MoMA in New York [http://www.moma.org/collection/object.php?object_id=78984] but is part of the Chagall: Modern Master Exhibition at the Tate Liverpool until October 6th, 2013 [http://www.tate.org.uk/whats-on/tate-liverpool/exhibition/chagall-modern-master] for which it is their poster picture.  Either website will give you a better picture than the thumbnail above, or you could go and see it in person…