Fifty years of tribology

Severe wear in a bearing (photo: Jean-Jacques Milan)

Cambridge University is celebrating 50 years of tribology, the study of friction, wear, and lubrication.

Actually, this is a field that goes back to Leonardo da Vinci, but the name was only coined 50 years ago, when Peter Jost wrote an influential report on the costs associated with friction and wear. That report, published on 9 March 9 1966, estimated that that improvements in lubrication and maintenance in industry could save the British economy £500 million per year.

Today, tribology is recognised as an important part of mechanical engineering as well as of medical engineering. Thanks, Peter!

X-ray of an artificial hip joint


I’m too far south to have caught the solar eclipse today, but here is a nice photograph (by “Kenrick95”) taken in Singapore (taken, in fact, not far from where I once lived):

Did any of my readers catch it?

Donald Trump and Demographics

It has been pointed out in recent times that the death rate for Non-Hispanic White males and females in the USA is now higher than for the general US population (data above from the recent US National Vital Statistics Report). In fact, in 2013, age-adjusted death rates for Non-Hispanic Whites actually rose (by 0.6, from 876.2 to 876.8 per 100,000 for males, and by 0.8, from 637.6 to 638.4 per 100,000 for females).

A recent article in PNAS shows that this apparently small increase results from a substantial increase in death rates among middle-aged Non-Hispanic White men and women (ages 45-54), and blames an increase in drug and alcohol poisonings and in suicide. The increases in death rate and in poisonings and suicide are particularly pronounced among Non-Hispanic White men and women without a college education. The chart below shows the crude death rates over time for Non-Hispanic White men and women in this age group, but does not reflect the impact of level of education (data from CDC WONDER Online Database):

The NY Times is among those that has run the story, and it has also been pointed out that the increases appear to be greater among women than men, greater in Southern states, and partly due to a reversal of progress against diabetes and other diseases.

This tragic phenomenon seems to be linked to a loss of blue-collar jobs in the USA, and a lack of access to affordable healthcare (which, in the USA, is often linked to employment). The map below shows the overall death rates for Non-Hispanic Whites in this age group by state (data from CDC WONDER Online Database, averaged over 2010–2014):

Jeff Guo at the Washington Post demonstrates that it is this group of people who are voting for Donald Trump. This group seems to feel that both major US political parties have ignored their very real problems. The Guardian describes what some of those problems are. The support for Trump appears to be a case of desperately clutching at straws, but will presumably continue until the major parties (1) acknowledge that these people matter and (2) come up with a plan for addressing their problems.

US counties by poverty rate (image by “TastyCakes”)

CE+T Power wins Little Box Challenge

CE+T Power of Belgium has won the Google/IEEE Little Box Challenge. They receive a million-dollar prize for building an extremely small (13.77 in3 / 225.6 cm3) 2-kW power inverter (above). Their design documentation can be read online (Gallium Nitride power transistors are a key element).

Well done, guys! I look forward to the improvements this will bring to solar power and small-scale power generation for remote areas.

World Solar Challenge: Nach dem Spiel

Twente’s 2015 car, Red One (photo: Jérôme Wassenaar)

As Sepp Herberger famously said, “Nach dem Spiel ist vor dem Spiel.” With the 2015 World Solar Challenge well and truly over, solar car teams around the world are beginning to recruit the people who will build and race their 2017 car. These teams include Nuon, Twente, Eindhoven, Stanford, Punch Powertrain (Belgium), ITS (Turkey), and EcoPhoton (Malaysia). There is also a new German team from Aachen.

Nuon is also acquiring a new flightcase for their car, to replace the one they used in 2015. I’ll be very interested to see what the contents of that case will be in 2017!

Nuon’s 2015 flightcase (photo: Jorrit Lousberg)

Here in Australia, Clenergy Team Arrow is considering switching to the Cruiser class in 2017, while Flinders University will enter for the first time. In Turkey, Sakarya University (SAITEM), who competed in the WSC in 2009 and 2011, are planning to return.

In Chile, things are heating up for the Carrera Solar Atacama in April. Most teams are South American, but Onda Solare is making the trip from Italy to compete. I hope that the event is a great success!


I love my daily shot of caffeine, preferably in the form of a good espresso. Caffeine is a stimulant and vasoconstrictor. It can increase alertness, and will sometimes alleviate headaches (although a rebound effect means that withdrawal from caffeine may temporarily cause headaches). Alfréd Rényi famously said that “A mathematician is a device for turning coffee into theorems,” and that does seem to be true. In addition, moderate coffee intake seems to have minor health benefits, including a slight protective effect against some cancers.

There are, however, good reasons to limit caffeine intake to 400 mg day (and half that for pregnant women). That leads to the limits in the table below (data from here and here). I intend to keep on enjoying my coffee responsibly, within those limits!

Drink Volume Caffeine Max/day
Espresso 1 shot (30 ml) 60 mg 6
Brewed coffee 1 cup 200 mg 2
Starbucks coffee “venti” 400 mg 1
Black tea 1 cup 40–80 mg 5–10
Green tea 1 cup 30–60 mg 6–13
Coca-Cola 1 can 35 mg 11
Red Bull 1 can 80 mg 5