Tuesday, 28 October 2008

Operational Reesearch and the urban cyclist

I am committed to cycling as a sensible means of transport, even though my own cycling has not been completely accident-free. The other day I was musing on whether there is much literature about O.R. and cycling. And then I heard about eBourbaki, which describes itself as "a mathematical problem-solving company" (no mention of O.R.!) and the competition that had been run to model cycle-hire facilities in London. Readers of "OR/MS Today" will have seen that one of the political conventions modeled the location of cycle-loan facilities in 2008. eBourbaki run their problems as competitions, and the winners created two mathematical models with one describing commuter flow and the other examining the possible configuration of any bicycle stations.

It is to be hoped that the city will work with the winners and consider using their solutions and models in the network design.

The models suggested that, for a London-based scheme to be successful, 12 large bicycle stations should be placed near railway stations in central London with 250 smaller stations distributed throughout the West End and the City of London. An average of 20 bikes per small station was found to be the most efficient number.

Monday, 20 October 2008

Visualising numbers

It is only distantly related to OR/MS, but I have touched on the problem of guesstimates before, as it is a sign of numeracy (an essential OR skill) to know when numbers "feel" right. So I was pleased to see the megapenny site which has pictures of what large numbers of one cent pieces will look like and weigh. In these days of governments bailing out banks and othe financial concerns, it is instuctive to note that $18 billion is just enough to fill the Empire State Building with one cent coins.

Monday, 6 October 2008

The Harvest Thanksgiving Supply Chain

In an earlier blog I mentioned links between O.R. and Christianity. September and October are the months when (in the Northern Hemisphere's temperate regions) churches celebrate harvest thanksgiving. (Cue for the traditional harvest hymn: "We plough the fields and scatter, The good seed on the land, But it is fed and watered, By God's Almighty hand." You can tell that I am a Brit, because I spell plough without a "w".) Increasingly church services also give thanks for the makers and producers of food -- and at our service yesterday the preacher thanked God for the drivers of delivery trucks -- she almost used the words "supply chain", but the congregation would not have been familiar with that technical term.

Operational Research and the Bible

An interesting diagram has been posted in a forum for vsiualising information.
The picture has one entry along the x-axis for each chapter in the Bible and there are coloured arcs between chapters which cross-reference to one another. (This means that there is a word, phrase or idea that occurs in one chapter that also appears in another; "The Lord is my Shepherd" in Psalms links with "I am the Good Shepherd" in the gospels.) There are 63779 such arcs -- the picture is beautiful. Mathematicians and O.R. scientists will recognise that the structure is a graph, with each chapter a vertex, and that leads to assorted questions about the graph. How many components does it have? Are there isolated vertices? What are the properties of the components?

I'd like to hear answers.