Wednesday, 27 February 2013

Talk : The future of Diesel's Engine

A recent talk at Nottingham Café Scientifique was presented by Prof Richard Stobart entitled “What is the Future for Diesel’s Engine?”

To begin with, Prof Stobart pointed out the key point that a mid-sized diesel engine (such as used in construction equipment) might cost £40k to buy - but would use about 24 times this value in fuel over its lifetime.

The Prof then moved on to give an outline of the broad range of diesel engines that are available:

The range of diesel engines available

Perhaps the first example of attempts to make internal combustion engines can be found in 13th century Chinas’ invention of rockets.

This was followed in the 17th century by Christian Huygen’s designs for a basic form of internal combustion engine (powered by gunpowder) which was developed by his partner Denis Papin.
Huygens was ahead of his time in many ways, not least in adopting the tight perm hairstyle that would not become widespread until the 1970s

Work in such “gunpowder engines” then ceased as steam powered “atmospheric engines” were developed and began to succeed commercially Steam engines ruled for over a hundred years, until the brilliant French military engineer and physicist Sadi Carnot undertook a serious study of the science behind combustion (published as “Reflections on the Motive Power of Fire) in 1824. The most important part of this wide-ranging work was the presentation of what is now knows as the “Carnot Cycle”
An ideal Carnot Cycle

1 to 2 : 300K Heat applied and applied pressure reduced - gas expands and takes in heat to maintain constant temp

2 to 3 : Heat source removed and applied pressure further reduced - gas expands and cools

3 to 4 : 200K heat applied and applied pressure increased - gas is squeezed and gives out heat to maintain constant temp

4 to 1 : Heat source removed and applied pressure increased - gas contracts and heats

Work performed is the area bounded by 1-2-3-4

Although Diesel patented his concept (see here), the wording of the claims meant that his patent could be challenged and this prevented him from obtaining the level of royalties he might otherwise have been able to obtain.

Diesel died in 1913, seemingly by committing suicide by jumping from a steamer travelling to London.

Diesel's original engine

Other noteworthy events in the development of the diesel engine were..

1905 : Alfred Buchi obtains a patent for turbocharging

1920’s : Sir Harry Ricardo develops many improvements to engine design

1930 : Junkers Jumo lightweight horizontally opposed engine

1932 : Citroen Rosalie - the first production diesel car.

1946 : Compact, powerful Napier Deltic Engine

1980s : The arrival of electronics

1997 : First automotive application of the Common Rail Fuel System (initially developed by Fiat who sold the technology to Bosch.

2000’s : Increasingly strict Emissions regulations

Prof Stobart then considered how the efficiency of the diesel engine might be improved to 50%.

One way of considering where improvements can be made is to consider the thermodynamics of the Otto cycle and investigate areas where current engines do not follow the cycle optimally.

For example, energy is lost in diesel engines as exhaust heat and friction, attempts can be made to recover these with waste heat recovery systems and by using electrical rather than mechanical power for engine subsystems

Another area where research may be of value is to consider how a larger volume of air can the introduced into the engine. This may seem like a trivial issue to address, but is actually very difficult as there is not a lot of time for the air to enter the cyclinder.

Finally, Prof Stobart mentioned a technique that his group was using to quickly undertake research - using virtual systems modelling to fool an engine into thinking that, say, an exhaust heat recovery system has been added, to see how the engine behaves in response.

The question and answer session, much longer than the actual talk, is one of the best features of Cafe Sci - and is often a source of much interesting information in its own right.

In this case, the Q&A included the following little nuggets of information...

Petrol and Diesel have a very high energy density, and filling a 40litre car tank (which takes around 60 seconds) represents an energy transfer rate of some 24,000 kW. To get an idea of just how high a density this is, compare it to a typical electric vehicle charging station, which charges at about 6kW. And a kilogram of diesel contains the same amount of energy as 20-40kg of battery. On the othe rhand, the efficiency of an electric motor is much higher than a diesel engine (90% comapred to ~35%) and is further boosted by technologies such as regenerative braking.

One reason that there is so much pollution in China is that the refineries there often buy cheaper "sour" oil that is high in sulphur, and then do not fully remove this contaminant during distillation (see 2004 article here)

Prof Stobarts team is part of the TEG energy recovery group .

Image Sources
Huygens, Engine

Saturday, 23 February 2013

Talk : Cochlea Ear Implants

A recent talk at Nottingham Café Scientifique was presented by Prof. Alan Palmer from the MRC Institute of Hearing Research at the University of Nottingham.

Prof Palmer began by describing how remarkable an organ the ear is before moving onto the technology of cochlea implants and future developments in this area.

The Ear
There are three main parts to the ear. . .

The Human Ear

The Outer Ear comprises the visible ear and the ear canal, both of which gather and focus sound energy onto the eardrum, amplifying frequencies around 3kHz (the frequency of human speech) by some 10 times.

The Middle Ear comprises three tiny bones that transfer energy from the eardrum (that is vibrated by air pressure) to the inner ear (which is filled with salty water). In doing so the bones act as levers so the large displacement - low pressure vibrations of the eardrum is converted to a small displacement - high pressure vibration in the inner ear. This transformation is important as sound behaves differently in air and in water, Indeed, without the middle ear ossicles, only about 0.1 percent of sound energy would make it into the inner ear. The development of the bones of the middle ear is fascinating, with their original location being on the jaw of the growing embryo before they move to their final location later in the embyro’s development.

The Inner Ear is fluid filled and comprises a number of structures, of which the most important here is the Cochlea. This spiral structure contains a central membrane that runs almost all the whole way along it and it is on this membrane that the hair cells which actually detect sound are located. The membrane is thinner and stiffer at the entrance to the cochlea (so the membrane here resonates at higher frequencies) and less stiff towards the apex of the cochlea (so the membrane here resonates at lower frequencies

The Cochlea

Frog Hair Cells

The vibrations of the membrane bend the "hairs" of the hair cells mechanically opening channels in their structure which allow in charged ions from the surrounding liquid, and it is this which generates the electrical potential in the nerve fibres attached to the hair cells.

Ion Channels

History of electrical stimulation of the ear
Prof Palmer briefly covered the history of electrical stimulation of the inner ear by mentioning the experiments of Volta (~1780) and Simmins (1966) - both of which are covered here

The Cochlear Implant
For those who suffer profound deafness due to damage to the hair cells (either congenital or though illness/hearing damage/drug use) it may be possible to use a cochlear implant, which has the following key components :

Extenally, there is a microphone, a speech processor that splits sound into different channels and a transmitter to send the signals through the skin.

Internally there is a receiver and stimulator secured in bone beneath the skin, which converts the signals into electric impulses and sends them through an internal cable to an array of up to 22 electrodes wound through the cochlea and lying just under the central membrane. The electrodes stimulated the nerves coming out of the hair cells, which are stimulated to send impulses to the brain through the auditory nerve.

Schematic of a Cochlea Implant

During development of cochlea implants, there was some skepticism that would be effective, given that they only had a couple of dozen electrodes against the thousands of hair cells and that these electrodes only indirectly activated the hair cell nerves - and this seemed to be born out with the results from initial implants, which were given to adults who had become deaf at some point after learning language. In these cases the recipient often had difficulty adjusting to the implant.

Implants are now given to children as young as 10 months old. In many of these cases, the implant has given the child sufficient hearing to allow them to learn language, go to a standard school and live a very normal life, including participating in the job market on equal terms with the rest of the population. There are now some 100,000 in use worldwide, although they remain a technology that is much more prevalent in the developed world, given that the cost in the range of a few tens of thousands of pounds.

Prof Palmer mentioned how great work was being done by Nottingham based charity “The Ear Foundation” in treating people who had deafness - and also, critically, giving them support post-implant to ensure that they are able to adjust to the use of the implant as well as possible. As Prof Palmer explained, these implants can literally be life-changing to the recipient.

Other technologies
Finally, Prof Palmer gave a quick look at some of the technologies that are under development. Perhaps the most interesting of these is research into implants into the part of the brain that receives the auditory signals. These are currently only having partial success, but this is perhaps to be expected since the technology is at the same point on its development as cochlear implants were some 20 years ago.

One of the best features of Café Sci is that the talks are short - but the Q&A session is long. Indeed, one can sometimes learn more from the Q&A than from the talk itself!

In this case, two things that came out of the discussion were comments describing how some in the deaf community viewed cochlear implants as a form of euthanasia and were very much against their use in small children. A view that BFTF finds difficult to understand.

And the other item was a suggestion to look up a video link on Youtube of a baby’s reaction on first having their new cochlea implant, which you can see below.

Image Sources Ear, Cochlea, Frog Hair Cells, Ion Channel, Implant,

Sunday, 17 February 2013

"Beyond the Final Boss" and Bullying

Schoolkids who are talented at their studies can sometimes find themselves at the receiving end of bullying - and this can have a lastign effect on their lives.

Someone who has decided to do something to reach out to youngsters suffering bullying is Shahid Kamal Ahmad, a London based computer games designer, who has got together with industry colleagues Mike Bithell and Byron Atkinson-Jones to detail examples of people in the computer games industry who have overcome bullying in their school days to find success, friends and a wide social circle in adulthood.

Shahid and friends put the stories on a website called "Beyond the Final Boss". There are some very touching stories on the site, and it no doubt has relevance for many yougsters who are facing bullying.

It would be easy to try and distill some common themes from the accounts of the people who gave their testimony on the site, but that would be to ignore the fact that evertyones experience is different. You really need to read it for yourself..

The site has received coverage elsewhere in gaming circles, most notably Kill Screen , The Penny Arcade Report and (rather awesomely) NBC news.

One aspect of this project that is worth noting is the speed with which the site was put together. As the Penny Arcade Report describes:
"Once Shahid joined the conversation, events didn’t so much snowball as they were fired from a rail gun. “It was very quick, Shahid doesn’t like to wait around,” Atkinson-Jones said. “He, like me, is a grab it and run with it kind of person so in all took less than a couple of hours before it was up on the blog for everybody to read. All it took was a relatively quick email where I poured out the story.”"

But perhaps the last word should go to Sam Hulick, now a widely respected composer in the video game industry, who was bullied as a youngster and comments that:
"In so many cases, the unique qualities that make you a target when you’re young are the very same traits that are appreciated as an adult: thinking differently than others, dancing to the beat of your own drum. Focus on what’s positive. Focus on your hobbies and interests, and think about how great the future will be. You are not worthless, you are not undeserving of respect, and there ARE people out there in the world who will love you and appreciate you. "

Some other resources
BFTF was also touched by this homily from an anti-bullying Facebook page
A teacher in New York was teaching her class about bullying and gave them the following exercise to perform. She had the children take a piece of paper and told them to crumple it up, stamp on it and really mess it up but do not rip it. Then she had them unfold the paper, smooth it out and look at how scarred and dirty is was. She then told them to tell it they’re sorry. Now even though they said they were sorry and tried to fix the paper, she pointed out all the scars they left behind. And that those scars will never go away no matter how hard they tried to fix it. That is what happens when a child bully’s another child, they may say they’re sorry but the scars are there forever. The looks on the faces of the children in the classroom told her the message hit home. Pass it on or better yet, if you're a parent or a teacher, do it with your child/children.

And Childline also has some relevant resources.