CS4FN Advent – Day 16: candy cane or walking aid: designing for everyone, human computer interaction

Welcome to Day 16 of the CS4FN Christmas Computing Advent Calendar in which we’re posting a blog post every day in December until (and including) Christmas Day.

We’re celebrating the breadth of computing research and also the history of CS4FN, a project which has been distributing free magazines to subscribing UK schools since 2005 (ask your teacher to subscribe for next year’s magazine).

Today’s advent calendar picture is of a candy cane which made me think both of walking aids and of support sticks that alert others that the person using it is blind or visually impaired.

A white candy cane with green and red stripes.

We’ve worked with several people over the years to write about their research into making life easier for people with a variety of disabilities. Issue 19 of our magazine (“Touch it, feel it, hear it!”) focused on the DePiC project (‘Design Patterns for Inclusive Collaboration’) which included work on helping visually impaired sound engineers to use recording studio equipment, and you can read one of the articles (see ‘2. The Haptic Wave’) from that magazine below.

Our most recent CS4FN magazine (issue 27, called “Smart Health: decisions, decisions, decisions“) was about Bayesian mathematics and its use in computing, but one of those uses might be an app with the potential to help people with arthritis get medical support when they most need it (rather than having to wait until their next appointment) – download the magazine by clicking on its title and scroll to page 16 & 17 (p9 of the 11 page PDF). Our writing also supports the (obvious) case, that disabled people must be involved at the design and decision-making stages.

 

1. Design for All (and by All!)

by Paul Curzon, QMUL. This article was originally published on the CS4FN website.

Making things work for everyone

Designing for the disabled – that must be a niche market mustn’t it? Actually no. One in five people have a disability of some kind! More surprising still, the disabled have been the inspiration behind some of the biggest companies in the world. Some of the ideas out there might eventually give us all super powers.

Just because people have disabilities doesn’t mean they can’t be the designers, the innovators themselves of course. Some of the most innovative people out there were once labelled ‘disabled’. Just because you are different doesn’t mean you aren’t able!

Where do innovators get their ideas from? Often they come from people driven to support people currently disadvantaged in society. The resulting technologies then not only help those with disabilities but become the everyday objects we all rely on. A classic example is the idea of reducing the kerbs on pavements to make it possible for people in wheelchairs to get around. Turns out of course that they also help people with pushchairs, bikes, roller-blades and more. That’s not just a one-off example, some of the most famous inventors and biggest companies in the world have their roots in ‘design for all’.

Designing for more extreme situations pushes designers into thinking creatively, thinking out of the box. That’s when totally new solutions turn up. Designing for everyone is just a good idea!

2. Blind driver filches funky feely sound machine! The Haptic Wave

by Jane Waite, QMUL. This article was originally published on the CS4FN website.

The blind musician Joey Stuckey in his recent music video commandeers then drives off in a car, and yes he is blind. How can a blind person drive a car, and what has that got to do with him trying to filch a sound machine? So maybe taking the car was just a stunt, but he really did try and run off with a novel sound machine!

As well as fronting his band Joey is an audio engineer. Unlike driving a car, which is all about seeing things around you – signs, cars pedestrians – being an audio engineer seems a natural job for someone who is blind. Its about recording, mixing and editing music, speech and sound effects. What matters most is that the person has a good ear. Having the right skills could easily lead to a job in the music industry, in TV and films, or even in the games industry. It’s also an important job. Getting the sound right is critical to the experience of a film or game. You don’t want to be struggling to hear mumbling actors, or the sound effects to drown out a key piece of information in a game.

Peter Francken in his studio. Image from Wikimedia Commons.

Mixing desks

Once upon a time Audio engineers used massive physical mixing desks. That was largely ok for a blind person as they could remember the positions of the controls as well as feel the buttons. As the digital age has marched on, mixing desks have been replaced by Digital Audio Workstations. They are computer programs and the trouble is that despite being about sound, they are based on vision.

When we learn about sound we are shown pictures of wavy lines: sound waves. Later, we might use an oscilloscope or music editing software, and see how, if we make a louder sound, the curves get taller on the screen: the amplitude. We get to hear the sound and see the sound wave at the same time. That’s this multimodal idea again, two ways of sensing the same thing.

But hang on, sound isn’t really a load of wavy lines curling out of our mouths, and shooting away from guitar strings. Sound is energy and atoms pushing up against each other. But we think of sound as a sound wave to help us understand it. That’s what a computer scientist calls abstraction: representing things in a simpler way. Sound waves are an abstraction, a simplified representation, of sound itself.

Sound waveform image by Gordon Johnson from Pixabay

The representation of sound as sound waves, as a waveform, helps us work with sound, and with Digital Audio Workstations it is now essential for audio engineers. The engineer works with lines, colors, blinks and particularly sound waves on a screen as they listen to the sound. They can see the peaks and troughs of the waves, helping them find the quiet, loud and distinctive moments of a piece of music, at a glance, for example. That’s great as it makes the job much easier…but only if you are fully sighted. It makes things impossible for someone with a visual impairment. You can’t see the sound waves on the editing screen. Touching a screen tells you nothing. Even though it’s ultimately about sounds, doing your job has been made as hard as driving a car. This is rather sad given computers have the potential to make many kinds of work much more accessible to all.

Feel the sound

The DePIC research team, a group of people from Goldsmiths, Queen Mary University of London and Bath Universities with a mission to solve problems that involve the senses, decided to fix it. They’ve created the first ever plug-in software for professional Digital Audio Workstations that makes peak level meters completely accessible. It uses ‘sonification’: it turns those visual signals in to sound! decided to fix the problems. They brought together Computer Scientists, Design experts, and Cognitive Scientists and most importantly of all audio engineers who have visual impairments. Working together over two years in workshops sharing their experiences and ideas, developing, testing and improving prototypes to figure out how a visually impaired engineer might ‘see’ soundwaves. They created the HapticWave, a device that enables a user to feel rather than see a sound wave.

The HapticWave

The HapticWave combines novel hardware and software to provide a new interface to the traditional Digital Audio Workstation. The hardware includes a long wooden box with a plastic slider. As you move the slider right and left you move forward and backwards through the music. On the slider there is a small brass button, called a fader. Tiny embossed stripes on the side of the slider let you know where the fader is relative to the middle and ends of the slider. It moves up and down in sync with the height of the sound wave. So in a quiet moment the fader returns to the centre of the slider. When the music is loud, the fader zooms to the top of the handle. As you slide forwards and backwards through the music the little button shoots up and down, up and down tracing the waveform. You feel its volume changing. Music with heavy banging beats has your brass button zooming up and down, so mind your fingers!

So back to the title of the article! Joey trialled the HapticWave at a research workshop and rather wanted to take one home, he loved it so much he jokingly tried distracting the researchers to get one. But he didn’t get away with it – maybe his getaway car just wasn’t fast enough!

3. An audio illusion, and an audiovisual one

This one-minute video illustrates an interesting audio illusion, demonstrating that our brains are ‘always using prior information to make sense of new information coming in’.

The McGurk Effect

You can read more about the McGurk effect on page 7 of issue 5 of the CS4FN magazine, called ‘The Perception Deception‘.

 

4. Previous Advent Calendar posts

CS4FN Advent – Day 1 – Woolly jumpers, knitting and coding (1 December 2021)

 

CS4FN Advent – Day 2 – Pairs: mittens, gloves, pair programming, magic tricks (2 December 2021)

 

CS4FN Advent – Day 3 – woolly hat: warming versus cooling (3 December 2021)

 

CS4FN Advent – Day 4 – Ice skate: detecting neutrinos at the South Pole, figure-skating motion capture, Frozen and a puzzle (4 December 2021)

 

CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle (5 December 2021)

 

CS4FN Advent – Day 6 – patterned bauble: tracing patterns in computing – printed circuit boards, spotting links and a puzzle for tourists (6 December 2021)

 

CS4FN Advent – Day 7 – Computing for the birds: dawn chorus, birds as data carriers and a Google April Fool (plus a puzzle!) (7 December 2021)

 

CS4FN Advent – Day 8: gifts, and wrapping – Tim Berners-Lee, black boxes and another computing puzzle (8 December 2021)

 

CS4FN Advent – Day 9: gingerbread man – computing and ‘food’ (cookies, spam!), and a puzzle (9 December 2021)

 

CS4FN Advent – Day 10: Holly, Ivy and Alexa – chatbots and the useful skill of file management. Plus win at noughts and crosses – (10 December 2021)

 

CS4FN Advent – Day 11: the proof of the pudding… mathematical proof (11 December 2021)

 

CS4FN Advent – Day 12: Computer Memory – Molecules and Memristors – (12 December 2021)

 

CS4FN Advent – Day 13: snowflakes – six-sided symmetry, hexahexaflexagons and finite state machines in computing (13 December 2021)

 

CS4FN Advent – Day 14 – Why is your internet so slow + a festive kriss-kross puzzle (14 December 2021)

 

CS4FN Advent – Day 15 – a candle: optical fibre, optical illusions (15 December 2021)

 

CS4FN Advent – Day 16: candy cane or walking aid: designing for everyone, human computer interaction – this post

 

 

 

CS4FN Advent – Day 12: Computer Memory – Molecules and Memristors

Computer memory molecular style, memristors, maths puzzle answer and a “20 questions” activity

Remember remember the 24th of December – as that’s the day to hang out your Christmas stocking! That’s the picture for today’s door on the CS4FN Christmas Computing Advent Calendar and I’ve made the somewhat stretched link between a stocking as a store for your presents and computer memory as a store for all your data.

A Christmas stocking. No presents though. Yet…

If your own memory needs a prod you can find a list of our previous posts at the end of this one.

Molecular memory

by Charlie Tizzrd, QMUL. This article was originally published on the CS4FN website.

What happens when computers need so much memory that they start to test the laws of physics? Charlie Tizzard investigates.

A new way to store data in individual molecules might put some life back into an old law of computing. Back in 1965, the founder of Intel, Gordon Moore, noticed that computer chips doubled their performance about every 18 months. Not only was he right in 1965, he kept on being right. Ten, twenty, even thirty years later, chip power still doubled every 18 months. This observation was so strong that it began to seem like a law of nature. It was named “Moore’s law” after Gordon Moore himself.

But some experts believe that Moore’s law is beginning to waver. As electronics continue to get smaller and smaller they are pushing the law to the limit. Electronics are now so small that even the laws of physics are even getting in the way. An esteemed physicist, Michio Kaku, said that “we already see a slowing down of Moore’s law. Computing power simply cannot maintain its rapid exponential rise using standard silicon technology.”
What to do?

Unless we move away from silicon-based storage in computing, we will run into some serious issues in the near future. Fortunately, scientists and engineers are experimenting with alternative ways of storing data. One way is to use molecules whose atoms can be shifted around within them. Storing data is all about making physical changes to something. That means you can put information in molecules by representing it as different atomic states. Best of all, those states can be changed and read by the same technology we have today: changes to the amount of electricity the molecules conduct.

Our only problem is that this idea works great inside a lab setting, but it can be difficult in the real world. First of all, molecular storage needs to be mass produced, but so far it’s specialised equipment built only in labs. Not only that, but up until now the molecules had to be kept at almost absolute zero (that’s -273°C) in order to work. But now an international team of researchers at MIT led by Jagadeesh Moodera have pioneered a new technique that allows the molecules to be kept at roughly the freezing point of water. In physics that’s practically room temperature.

Even more importantly, the molecules, which previously had to be sandwiched between two electrical conductors, only require one conductor in the MIT setup. That will make mass manufacturing a lot simpler and cheaper for companies. “This is only the tip of tip of the iceberg” says Moodera, so don’t be surprised if you are using chemicals for storing your photos in the future!

 

Do you remember the birth of the memristor?

by Paul Curzon, QMUL. This article was originally published on the CS4FN website.

A memristor – photo from Wikimedia Commons.

Electronics! It’s all been done long ago, hasn’t it? Resistors, transistors, capacitors, and inductors: all invented. See. Done it, filled in the worksheet, nothing else to discover…but did you miss the birth of the memristor?

In 2008 a new member of the electronics family was born. It had been discussed in theory as the missing link. It was mathematically possible, but never actually built till electronic engineers at Hewlett Packard used nanotechnology to bring it into existence.

Memristors are resistors with memory. Doh! Clever name! It can work as a data store, being either off or on, but it can store this information without any power too. This ability to store binary data (1s and 0s) with no drain on a battery, combined with its tiny, nanotechnology size means that memristors can store more data than any normal hard drive, and can be accessed as quickly as RAM – the kind of memory computers currently use. That means that in the future computers may be able to store more, start faster and be eco friendly too.

Building brains? That would be amazing enough but it turns out that the memistor has another trick up its nano-sleeve. Rather than working in digital mode, saving on/off (1,0) data like normal computer components, it can also hold values in between! The values it holds change every time the memristor receives an electrical signal, which is exactly what happens in the neurones of our brain as we learn. In the future networks of memristors could mimic the way our brains work, storing the things they learned from their electronic experiences. That would open up the possibility of a compact, low power way to build artificial intelligences.

Not bad for a humble little addition to the family of electronic components. See what you can miss is you don’t pay attention!

 

2. Today’s activity – the 20 questions game

The game 20 Questions, as the name suggests, involves trying to guess which famous person someone is thinking about by asking a maximum of 20 questions, all of which can be answered by YES or NO. The trick – of course – is to use good questions.

You’d be there all day if you kept asking them “Is it this person?”, “Is it that person?”. Those types of questions don’t chip away at the enormity of ~8 billion or so possibilities. Better questions might include “Are they alive?”, “Are they European?”. A yes or no answer to those questions tells you much more and helps narrow things down.

The game is a great way to learn about information theory and how the best questions are ones that split the options in half (roughly!). Most of the 8 billion people on Earth aren’t that famous, let’s assume it’s around 1 million people (because the maths is handy if we do!). If each of your questions divides a population of famous people in half each time and we start with one million people, how many questions do you need to ask before you get down to one person?

Or, to put it another way 2 (dividing in half) to the power of 20 (the 20 questions) or 220 gives 1,048,576 people (or items).

We developed an activity for teachers and students to do in the classroom (you can do it at home too) that uses the game to explore different search algorithms and improving how computers (and we) find information. It was number 4 in our 10 most popular downloads last year.

Use the activity to find out more about these computing concepts, while seeing how efficiently you can guess what someone else is thinking about.

  • computational thinking
  • linear search
  • binary search
  • divide and conquer
  • comparing algorithms

The 20-questions Activity

 

3. Answer to yesterday’s puzzle

 

The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.

 

4. Previous Advent Calendar posts

CS4FN Advent – Day 1 – Woolly jumpers, knitting and coding (1 December 2021)

 

CS4FN Advent – Day 2 – Pairs: mittens, gloves, pair programming, magic tricks (2 December 2021)

 

CS4FN Advent – Day 3 – woolly hat: warming versus cooling (3 December 2021)

 

CS4FN Advent – Day 4 – Ice skate: detecting neutrinos at the South Pole, figure-skating motion capture, Frozen and a puzzle (4 December 2021)

 

CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle (5 December 2021)

 

CS4FN Advent – Day 6 – patterned bauble: tracing patterns in computing – printed circuit boards, spotting links and a puzzle for tourists (6 December 2021)

 

CS4FN Advent – Day 7 – Computing for the birds: dawn chorus, birds as data carriers and a Google April Fool (plus a puzzle!) (7 December 2021)

 

CS4FN Advent – Day 8: gifts, and wrapping – Tim Berners-Lee, black boxes and another computing puzzle (8 December 2021)

 

CS4FN Advent – Day 9: gingerbread man – computing and ‘food’ (cookies, spam!), and a puzzle (9 December 2021)

 

CS4FN Advent – Day 10: Holly, Ivy and Alexa – chatbots and the useful skill of file management. Plus win at noughts and crosses – (10 December 2021)

 

CS4FN Advent – Day 11: the proof of the pudding… mathematical proof (11 December 2021)

 

CS4FN Advent – Day 12: Computer Memory – Molecules and Memristors – (12 December 2021) – this post

 

 

 

CS4FN Advent – Day 9: gingerbread man – computing and ‘food’ (cookies, spam!), and a puzzle

Computing- and food-themed post on cookies and spam + a puzzle.

Welcome to Day 9 of our CS4FN Christmas Computing Advent Calendar. Every day between now and Christmas we’ll publish a post about computer science with a puzzle to print and solve. You can see all our previous posts in the list at the end.

Today’s post is inspired by the picture on the advent calendar’s door – a gingerbread man, so we have a food-themed post. Well… food-ish.

Festive gingerbread man, wearing a mask. Safety first!

1. Cookies, but not the biscuit kind

Imagine you have a Christmas gift voucher and want to spend it in an online shop. You visit the website and see an item you’d like so you click ‘add to basket’ and then look for some other things you’d like to buy. You click on another item to find out more about it but suddenly your basket is empty! Fortunately this doesn’t usually happen thanks to cookies, which are tiny computer files that can make your website visit run smoothly.

Websites ask you if they can put these cookies on your computer. If you say ‘yes’ that lets them see that you are the same person as you add new things to your basket. It would be no use if you added your second item and the website decided that you were now a completely different person. Some cookies help the organisation know that you’re still you, even when you’re viewing lots of different pages on their website.

Cookie image by congerdesign from Pixabay

Other cookies mean that you don’t have to keep logging in every time you click on a new page within the website. It would be very annoying if you had to do that.

Some cookies are there to help the organisation itself. They let them see what people are clicking on when they’re on the organisation’s website, and what path they follow as they visit different pages. They can also tell what device someone is using (a phone or a computer) so they can make sure the information is set to be the right size on their screen.

If people are logged in then the website knows who they are. Because of this, organisations have to be very careful about how they use this information, to protect their visitors’ privacy. If they don’t take care then they are breaking the law and can be fined a lot of money.

Further reading

Cookies (no publication date given) – from the ICO – the Information Commissioner’s Office.

 

 

2. The recipe for spam

These days when people talk about “spam” they are talking about unwanted emails from strangers. The word spam comes from a tinned meat product which, because of a comedy sketch by Monty Python, now also means “email messages that no-one can avoid”.

by Paul Curzon, QMUL. This post was originally published on the CS4FN website.

Fighting spam

Monitor screen showing spam in the mailbox

Shutting down spammers is tough for the authorities, so the internet’s arteries go on getting plugged up by spam. The best strategy against it so far seems to be filtering out junk emails from your inbox. Lots of early spam filtering relied on keeping lists of words that appear in spam and catching emails that contained them, but there were plenty of problems. For one thing, certain words that turn up in spam also appear sometimes in normal emails, so perfectly innocent messages sometimes ended up in the spam filter. What’s more, spammers have ways of eluding filters that simply check words against a list. Just me55 a-r-0-u-n-d w1th teh sp£lling.

Finally a simple but ingenious idea surfaced: instead of trying to keep a list of spammy words, why not try and teach computers to recognise spam for themselves? There’s a whole branch of maths about probability that researchers began to apply to spam, and a programmer called Paul Graham made the strategy famous in 2002 when he wrote an essay called A Plan for Spam.

Spammy maths

Paul Graham suggested that you could analyse the words you get in a sample of your email to see what the chances are that a particular word would appear in your real messages. You could do the same with a sample from your spam. Then you could look up any word in a new message and see whether it’s likely to be spam or your real email.

Of course, one word’s not enough to base your conclusion on, so Paul’s filter chose the fifteen most interesting words to look at. What that meant was that it grabbed the biggest clues to look at – words that, statistically, had the best chance of being in either spam or real mail, but not both. Then it used those clues to figure out the overall chance that an email is spam. It did this with an equation called Bayes’ theorem, which tells you how to figure out the chances of something being true given a set of facts. In this case Bayes’ theorem figures out the chances of a message being spam given the set of words in it.

What’s brilliant about the statistical approach is that not only does the computer learn as it goes on, meaning it keeps up with spammers’ tricks automatically, it can learn what words are normal for each person’s email, so scientists working on Viagra wouldn’t have to worry about all their emails going in the bin.

On guard online

Spam filters now work well enough that you can make your inbox pretty safe from the porky hordes of messages trying to invade. Wonderful news for the 99% of us who don’t have any use for dodgy meds, fake fashions and pyramid scams. As long as people keep buying into spam and the small group of overlords keeps turning computers into zombies, we’ll need to keep our defences up.

 

3. Today’s puzzle – the melting snowman

A picture showing several snowmen, drawn by Paul Curzon.

Instructions

One of the snowmen keeps disappearing! Is it melting or just flying
away, and which one is it?

Cut out the picture along the straight black lines, to give three
rectangular pieces. Then follow the simple algorithm and see the
snowman disappear before your eyes.

1. Put the three pieces together in the original positions to make the picture.
2. Count all the snowmen.
3. Swap the position of the top two pieces over so the top and bottom halves of the snowmen line up again
4. Count the snowmen again.

One snowman has disappeared!

Put the pieces back and you will find it reappears.

The explanation and answer will arrive in tomorrow’s (blog) post 🙂

 

4. Answer to yesterday’s puzzle

Here’s the answer to Daniel’s puzzle.

 

5. Previous Advent Calendar posts

CS4FN Advent – Day 1 – Woolly jumpers, knitting and coding (1 December 2021)

 

CS4FN Advent – Day 2 – Pairs: mittens, gloves, pair programming, magic tricks (2 December 2021)

 

CS4FN Advent – Day 3 – woolly hat: warming versus cooling (3 December 2021)

 

CS4FN Advent – Day 4 – Ice skate: detecting neutrinos at the South Pole, figure-skating motion capture, Frozen and a puzzle (4 December 2021)

 

CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle (5 December 2021)

 

CS4FN Advent – Day 6 – patterned bauble: tracing patterns in computing – printed circuit boards, spotting links and a puzzle for tourists (6 December 2021)

 

CS4FN Advent – Day 7 – Computing for the birds: dawn chorus, birds as data carriers and a Google April Fool (plus a puzzle!) (7 December 2021)

 

CS4FN Advent – Day 8: gifts, and wrapping – Tim Berners-Lee, black boxes and another computing puzzle (8 December 2021)

 

CS4FN Advent – Day 9: gingerbread man – computing and ‘food’ (cookies, spam!), and a puzzle (9 December 2021) – this post

 

CS4FN Advent – Day 8: gifts, and wrapping – Tim Berners-Lee, Right to Repair & another computing puzzle

Tim Berners-Lee, Right to Repair, and a maths puzzle.

Welcome to Day 8 of our CS4FN Christmas Computing Advent Calendar. It features a computing-themed post every day in December until Christmas Day. All the blog posts in the Advent Calendar so far have been inspired by the picture on the ‘door’ – and today’s post is also inspired by the picture, which is of a Christmas present.

Presents are something you give freely to someone, but they’re also something you hide behind wrapping paper. This post is about a gift and also about trying to uncover something that’s been hidden. Read on to find out about Tim Berners-Lee’s gift to the world, and about the Restart Project who are working to stop the manufacturers of electronic devices from hiding how people can fix them. At the bottom of the post you’ll find the answer to yesterday’s puzzle and a new puzzle for today, also all of the previous posts in this series. If you’re enjoying the posts, please share them with your friends 🙂

A present in blue wrapping paper with a large green bow.

 

1. “This is for everyone” – Tim Berner’s Lee

Audiences don’t usually cheer for computer scientists at major sporting events but there’s one computer scientist who was given a special welcome at the London Olympics Opening Ceremony in 2012.

Tim Berners-Lee invented the World Wide Web in 1989 by coming up with the way for web pages to be connected through links (everything that’s blue and clickable on this page is a link). That led to the creation of web browsers which let us read web pages and find our way around them by clicking on those links. If you’ve ever wondered what “www” means at the start of a link it’s just short for World Wide Web. Try saying “www” and then “World Wide Web” – which takes longer to say?

Tim Berners-Lee didn’t make lots of money from his invention. Instead he made the World Wide Web freely available for everyone to use so that they could access the information on the web. Unless someone has printed this onto paper, you’re reading this on a web browser on the World Wide Web, so three cheers Tim Berners-Lee.

In 2004 the Queen knighted him (he’s now Sir Tim Berners-Lee) and in 2017 he was given a special award, named after Alan Turing, for “inventing the World Wide Web and the first web browser.”

Below is the tweet he sent out during the Olympics opening ceremony.

 

 

Further reading

The Man Who Invented The Web (24 June 2001) Time
“I Was Devastated”: Tim Berners-Lee, the Man Who Created the World Wide Web, Has Some Regrets (1 July 2018) Vanity Fair

 

2. Do you have the right to repair your electronic devices?

A ‘black box’ is a phrase to describe something that has an input and an output but where ‘the bit in the middle’ is a complete mystery and hidden from view. An awful lot of modern devices are like this. In the past you might have been able to mend something technological (even if it was just changing the battery) but for devices like mobile phones it’s becoming almost impossible.

People need special tools just to open them as well as the skills to know how to open them without breaking some incredibly important tiny bit. Manufacturers aren’t always very keen for customers to fix things. The manufacturers can make more money from us if they have to sell us expensive parts and charge us for people to fix them. Some even put software in their devices that stops people from fixing them!

The cost of fixing devices can be very expensive and in some cases it can actually be cheaper to just buy a new device. Obviously it’s very wasteful too.

The Restart Project is full of volunteers who want to help everyone fix our electronic devices, and also fix our relationship with electronics (discouraging us from throwing away our old phone when a new one is on the market). The project began in London but they now run Repair Parties in several cities in the UK and around the world. At these parties people can bring their broken devices and rather than just ‘getting them fixed’ they can learn how to fix their devices themselves by learning and sharing new skills. This means they save money and save their devices from landfill.

Restart also campaign for people to have the Right to Repair their own devices. They want a change in manufacturing laws to make sure that devices are designed so that the people who buy and use them can easily repair them without having to spend too much money.

 

3. Today’s puzzle

A more mathematical puzzle today. Rather than writing letters into the kriss-kross you need to write the equation and its answer.

For example 5 + 2 = as the clue gives you 5 + 2 = 7 as the answer which takes up 5 characters (note that the answer is not “seven” which also takes up 5 characters!). There are several places in the puzzle where a 5 character answer could go, but which one is the right one? Start with the clues that have only one space they can fit into (the ones with 7 symbols and 9 symbols) then see what can fit around them.

This puzzle was created by Daniel, aged 6. For an explanation of the links to computer science and how these puzzles can be used in the classroom please see the Maths Kriss-Kross page on our site for teachers. Note that the page does include the answer sheet, but no cheating, we’ll post the answer tomorrow. Also, if you don’t have a printer you can use the editable PDF linked on that page.

4. Answer to yesterday’s puzzle

 

The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.

 

5. Previous Advent Calendar posts

CS4FN Advent – Day 1 – Woolly jumpers, knitting and coding (1 December 2021)

 

CS4FN Advent – Day 2 – Pairs: mittens, gloves, pair programming, magic tricks (2 December 2021)

 

CS4FN Advent – Day 3 – woolly hat: warming versus cooling (3 December 2021)

 

CS4FN Advent – Day 4 – Ice skate: detecting neutrinos at the South Pole, figure-skating motion capture, Frozen and a puzzle (4 December 2021)

 

CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle (5 December 2021)

 

CS4FN Advent – Day 6 – patterned bauble: tracing patterns in computing – printed circuit boards, spotting links and a puzzle for tourists (6 December 2021)

 

CS4FN Advent – Day 7 – Computing for the birds: dawn chorus, birds as data carriers and a Google April Fool (plus a puzzle!) (7 December 2021)

 

CS4FN Advent – Day 8: gifts, and wrapping – Tim Berners-Lee, black boxes and another computing puzzle (8 December 2021) – this post

 

 

CS4FN Advent – Day 7 – Computing for the birds: dawn chorus, birds as data carriers and a Google April Fool (plus a puzzle!)

Welcome to Day 7 of our advent calendar. Yesterday’s post was about Printed Circuit Birds Boards, today’s theme is the Christmas robin redbreast which features on lots of Christmas cards and today is making a special appearance on our CS4FN Computing advent calendar.

A little robin redbreast.

In this longer post we’ll focus on the ways computer scientists are learning about our feathered friends and we’ll also make room for some of the bird-brained April Fools jokes in computing too.

We hope you enjoy it, and there’s also a puzzle at the end.

 

1. Computing Sounds Wild – bird is the word

Our free CS4FN magazine, Computing Sounds Wild (you can download a copy here), features the word ”bird” 60 times so it’s definitely very bird-themed.

An interest in nature and an interest in computers don’t obviously go well together. For a band of computer scientists interested in sound they very much do, though. In this issue we explore the work of scientists and engineers using computers to understand, identify and recreate wild sounds, especially those of birds. We see how sophisticated algorithms that allow machines to learn, can help recognize birds even when they can’t be seen, so helping conservation efforts. We see how computer models help biologists understand animal behaviour, and we look at how electronic and computer-generated sounds, having changed music, are now set to change the soundscapes of films. Making electronic sounds is also a great, fun way to become a computer scientist and learn to program.”

 

2. Singing bird – a human choir singing birdsong

by Jane Waite, QMUL
This article was originally published on the CS4FN website and can also be found on page 15 in the magazine linked above.

“I’m in a choir”. “Really, what do you sing?” “I did a blackbird last week, but I think I’m going to be woodpecker today, I do like a robin though!”

This is no joke! Marcus Coates a British artist, got up very early, and working with a wildlife sound recordist, Geoff Sample, he used 14 microphones to record the dawn chorus over lots of chilly mornings. They slowed the sounds down and matched up each species of bird with different types of human voices. Next they created a film of 19 people making bird song, each person sang a different bird, in their own habitats, a car, a shed even a lady in the bath! The 19 tracks are played together to make the dawn chorus. See it on YouTube below.

Marcus didn’t stop there, he wrote a new bird song score. Yes, for people to sing a new top ten bird hit, but they have to do it very slowly. People sing ‘bird’ about 20 times slower than birds sing ‘bird’ ‘whooooooop’, ‘whooooooop’, ‘tweeeeet’. For a special performance, a choir learned the new song, a new dawn chorus, they sang the slowed down version live, which was recorded, speeded back up and played to the audience, I was there! It was amazing! A human performance, became a minute of tweeting joy. Close your eyes and ‘whoop’ you were in the woods, at the crack of dawn!

Computationally thinking a performance

Computational thinking is at the heart of the way computer scientists solve problems. Marcus Coates, doesn’t claim to be a computer scientist, he is an artist who looks for ways to see how people are like other animals. But we can get an idea of what computational thinking is all about by looking at how he created his sounds. Firstly, he and wildlife sound recordist, Geoff Sample, had to focus on the individual bird sounds in the original recordings, ignore detail they didn’t need, doing abstraction, listening for each bird, working out what aspects of bird sound was important. They looked for patterns isolating each voice, sometimes the bird’s performance was messy and they could not hear particular species clearly, so they were constantly checking for quality. For each bird, they listened and listened until they found just the right ‘slow it down’ speed. Different birds needed different speeds for people to be able to mimic and different kinds of human voices suited each bird type: attention to detail mattered enormously. They had to check the results carefully, evaluating, making sure each really did sound like the appropriate bird and all fitted together into the Dawn Chorus soundscape. They also had to create a bird language, another abstraction, a score as track notes, and that is just an algorithm for making sounds!

 

3. Sophisticated songbird singing – how do they do it?

by Dan Stowell, QMUL
This article was originally published on the CS4FN website and can also be found on page 14 in the magazine linked above.

How do songbirds make such complex sounds? The answer is on a different branch of the tree of evolution…
We humans have a set of vocal folds (or vocal cords) in our throats, and they vibrate when we speak to make the pitched sound. Air from your lungs passes over them and they chop up the column of air letting more or less through and so making sound waves. This vocal ‘equipment’ is similar in mammals like monkeys and dogs, our evolutionary neighbours. But songbirds are not so similar to us. They make sounds too, but they evolved this skill separately, and so their ‘equipment’ is different: they actually have two sets of vocal folds, one for each lung.

Image by Dieter_G from Pixabay

Sometimes if you hear an impressive, complex sound from a bird, it’s because the bird is actually using the two sides of their voice-box together to make what seems like a single extra-long or extra-fancy sound. Songbirds also have very strong muscles in their throat that help them change the sound extremely quickly. Biologists believe that these skills evolved so that the birds could tell potential mates and rivals how healthy and skillful they were.

So if you ever wondered why you can’t quite sing like a blackbird, now you have a good excuse!

 

4. Data transmitted on the wing

Computers are great ways of moving data from one place to another and the internet can let you download or share a file very quickly. Before I had the internet at home if I wanted to work on a file on my home computer I had to save a copy from my work computer onto a memory stick and plug it in to my laptop at home. Once I ‘got connected’ at home I was then able to email myself with an attachment and use my home broadband to pick up file. Now I don’t even need to do that. I can save a file on my work computer, it synchronises with the ‘cloud’ and when I get home I can pick up where I left off. When I was using the memory stick my rate of data transfer was entirely down to the speed of road traffic as I sat on the bus on the way to work. Fairly slow, but the data definitely arrived in one piece.

In 1990 a joke memo was published for April Fool’s Day which suggested the use of homing pigeons as a form of internet, in which the birds might carry small packets of data. The memo, called ‘IP over Avian Carriers’ (that is, a bird-based internet), was written in a mock-serious tone (you can read it here) but although it was written for fun the idea has actually been used in real life too. Photographers in remote areas with minimal internet signal have used homing pigeons to send their pictures back.

The beautiful (and quite possibly wi-fi ready, with those antennas) Victoria Crowned Pigeon. Not a carrier pigeon admittedly, but much more photogenic.  Image by Foto-Rabe from Pixabay

A company in the US which offers adventure holidays including rafting used homing pigeons to return rolls of films (before digital film took over) back to the company’s base. The guides and their guests would take loads of photos while having fun rafting on the river and the birds would speed the photos back to the base, where they could be developed, so that when the adventurous guests arrived later their photos were ready for them.

Further reading

Pigeons keep quirky Poudre River rafting tradition afloat (17 July 2017) Coloradoan.

 

5. Serious fun with pigeons

On April Fool’s Day in 2002 Google ‘admitted’ to its users that the reason their web search results appeared so quickly and were so accurate was because, rather than using automated processes to grab the best result, Google was actually using a bank of pigeons to select the best results. Millions of pigeons viewing web pages and pecking picking the best one for you when you type in your search question. Pretty unlikely, right?

In a rather surprising non-April Fool twist some researchers decided to test out how well pigeons can distinguish different types of information in hospital photographs. They trained pigeons by getting them to view medical pictures of tissue samples taken from healthy people as well as pictures taken from people who were ill. The pigeons had to peck one of two coloured buttons and in doing so learned which pictures were of healthy tissue and which were diseased. If they pecked the correct button they got an extra food reward.

Pigeon, possibly pondering people’s photographs. Image by Davgood Kirshot from Pixabay

The researchers then tested the pigeons with a fresh set of pictures, to see if they could apply their learning to pictures they’d not seen before. Incredibly the pigeons were pretty good at separating the pictures into healthy and unhealthy, with an 80 per cent hit rate.

Further reading

Principle behind Google’s April Fools’ pigeon prank proves more than a joke (27 March 2019) The Conversation.

 

6. Today’s puzzle

You can download this as a PDF to PRINT or as an editable PDF that you can fill in on a COMPUTER.

You might wonder “What do these kriss-kross puzzles have to do with computing?” Well, you need to use a bit of logical thinking to fill one in and come up with a strategy. If there’s only one word of a particular length then it has to go in that space and can’t fit anywhere else. You’re then using pattern matching to decide which other words can fit in the spaces around it and which match the letters where they overlap. Younger children might just enjoy counting the letters and writing them out, or practising phonics or spelling.

We’ll post the answer tomorrow.

7. Answer to yesterday’s puzzle

 

The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.

 

Previous Advent Calendar posts

CS4FN Advent – Day 1 – Woolly jumpers, knitting and coding (1 December 2021)

 

CS4FN Advent – Day 2 – Pairs: mittens, gloves, pair programming, magic tricks (2 December 2021)

 

CS4FN Advent – Day 3 – woolly hat: warming versus cooling (3 December 2021)

 

CS4FN Advent – Day 4 – Ice skate: detecting neutrinos at the South Pole, figure-skating motion capture, Frozen and a puzzle (4 December 2021)

 

CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle (5 December 2021)

 

CS4FN Advent – Day 6 – patterned bauble: tracing patterns in computing – printed circuit boards, spotting links and a puzzle for tourists (6 December 2021)

 

CS4FN Advent – Day 7 – Computing for the birds: dawn chorus, birds as data carriers and a Google April Fool (plus a puzzle!) (7 December 2021) – this post

 

 

 

 

CS4FN Advent – Day 6 – patterned bauble: tracing patterns in computing – printed circuit boards, spotting links and a puzzle for tourists

Welcome to Day 6 of the CS4FN Christmas Computing Advent Calendar – every day until Christmas we’ll post a little something about computer science. Some of it will even relate (…vaguely) to the picture on the advent calendar’s door.

Today’s picture is of a festive bauble with a pattern engraved on it. That obviously made us think of printed circuit boards. Read on to see why.

A brightly coloured (pink!) Christmas bauble, ready to go on a tree.

At the very end of this article you can see a list of all the previous Advent Calendar posts.

 

Printed Circuit Boards

Yesterday we looked at computers made of water, in which the flow of water (and where it ends up) let people do some quite advanced calculations. Today it’s the electrons that are doing the flowing… through tiny little copper channels.

Circuit board traces image by Gordon Johnson from Pixabay

Printed circuit boards (aka PCBs) contain and connect the bits that computers and electronic devices need to run properly. PCBs have two main functions: to act as a sort of ‘bookshelf’ for all the electronic components (such as transistors, sensors etc), but also to support electrical connections between those components so that electricity can flow through them and the device can work. Some of the components are soldered directly to the board, others are connected by being clipped into sockets that have previously been attached. A circuit board is generally only a few inches long with, smaller ones for smaller (or simpler) devices – they have to fit inside after all.

Printed circuit board image by Michael Schwarzenberger from Pixabay

They look like the image above and generally consist of a stiff flat board (which itself does not conduct electricity) and on that there’s a coating of copper foil which has had a pattern etched into it. Etching uses chemicals to ‘delete’ all the bits of copper that aren’t needed, leaving behind only the pattern that forms the correct connecting circuits.

Printed circuit board image by nanoslavic from Pixabay

 

Complete circuit

This next article was originally published on the CS4FN website.

Follow the circuit…

1. Kirchhoff’s famous circuit laws describe the conservation of charge and energy in electrical circuits. They form the basis for circuit design as well, leading to many a homework assignment working out the current at different places in a circuit. Their creator, physicist Gustav Kirchhoff, was born in the town of Koenigsberg in what is now Russia.

2. Koenigsberg sits on several islands originally connected by seven bridges. It was this town plan that helped mathematician Leonhard Euler to pose and solve the famous Seven Bridges of Koenigsberg Problem. It helped develop the useful mathematical area called graph theory.

3. Graph theory is used by engineers when building mobile phone networks. Your mobile phone finds the nearest base station and locks onto it to send and receive information. Researchers recently revealed a midget drone plane called WASP, built on the cheap with parts bought on the Internet. It could fly unseen over a city mimicking a ‘local tower’ to intercept phone messages and wi-fi data.

4. Wi-fi is a set of agreed standards that allow radio links between all manner of electronic gadgets. These worldwide rules are based around the idea of ‘frames’. Frames contain the data that is to be sent or received in a particular format. Devices have to know these rules of conversation to talk to each other. They range from asking nicely in the ‘association request frame’ if the receiver is ready, willing and able to connect, to the ‘association response frame’ where the receiver answers “yes” or “no”.

5. Yes or no is an example of a binary encoding: only two options exist. Many electronic devices these days use binary coding. The signal has only two possible values. That makes turning them mathematically into numbers and the subsequent calculations easier and more accurate. Analogue electronics, where voltage and currents can vary across a range of values are more difficult to design but are still useful in some applications. They can have surprising advantages. For example, before digital radio took over it was possible to build a working ‘crystal radio set’ using analogue techniques with simple household items like wire and a rusty nail. This radio was powered by the radio waves and didn’t need batteries.

6. Batteries store energy and many see them as a big unsolved problem of electronics. They are heavy, need space and charging, and when they run out your gadget stops. Researchers are now looking at using common everyday stuff like plastics and concrete to store the energy we need. Another idea is to use energy from our walking on the go. Whatever way energy is created and stored in the future, it will still swirl round the circuit obeying Kirchhoff’s laws.

GO TO 1!

 

Today’s puzzle

Instead of an electron whizzing around a circuit board imagine you’re a tourist guide looking after some guests visiting London. Your task is to get your group to visit each one of the visitor attractions listed in the printed circuit ‘map’ below, once (without revisiting it). Can you plan a route that does this? (The answer will be in tomorrow’s advent calendar ‘door’).

Note for parents and teachers: we have a classroom activity that features this puzzle and teachers can use this to talk about things like an introduction to algorithmic thinking, sequences, graphs / nodes / edges, representation and abstraction. Access The Tour Guide activity here (the image above comes from the free PDF which you can download on that page).

 

Answer to yesterday’s puzzle

Yesterday’s puzzle was about compressing information and the answer is a line from Charles Dickens’ A Christmas Carol – “When Scrooge awoke, it was so dark, that looking out of bed, he could scarcely distinguish the transparent window from the opaque walls of his chamber” which we shortened to “NG1 AMH5 IBEC2 84F6JKO 7JDLC93”. You can read the whole book here at Project Gutenberg.

 

Previous Advent Calendar posts

CS4FN Advent – Day 1 – Woolly jumpers, knitting and coding (1 December 2021)

 

CS4FN Advent – Day 2 – Pairs: mittens, gloves, pair programming, magic tricks (2 December 2021)

 

CS4FN Advent – Day 3 – woolly hat: warming versus cooling (3 December 2021)

 

CS4FN Advent – Day 4 – Ice skate: detecting neutrinos at the South Pole, figure-skating motion capture, Frozen and a puzzle (4 December 2021)

 

CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle (5 December 2021)

 

CS4FN Advent – Day 6 – patterned bauble: tracing patterns in computing – printed circuit boards, spotting links and a puzzle for tourists (6 December 2021) – this post

 

 

CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle

This post is behind the 5th ‘door’ of the CS4FN Christmas Computing Advent Calendar – we’re publishing a computing-themed (and sometimes festive-themed) post every day until Christmas Day. Today’s picture is a snowman, and what’s a snowman made of but frozen water?

You can make a computer out of water!

1n 1936 Vladimir Lukyanov got creative with some pipes and pumps built a computer, called a water (or hydraulic) integrator, which could store water temporarily in some bits and pump water to other bits. The movement of water and where it ended up used the ‘simplicity of programming’ to show him the answer – a physical representation of some Very Hard Sums (sums, equations and calculations that are easier now thanks to much faster computers).

A simple and effective way of using water to show a mathematical relationship popped up on QI and the video below demonstrates Pythagoras’ Theorem rather nicely.

In 1939 Lukyanov published an article about his analog hydraulic computer for the (‘Otdeleniye Technicheskikh Nauk’ or ‘Отделение технических наук’ in Russian which means Section for Technical Scientific Works although these days we’d probably say Department of Engineering Sciences) and in 1955 this was translated by the Massachusetts Institute of Technology (MIT) for the US army’s “Arctic Construction and Frost Effects Laboratory”. You can see a copy of his translated ‘Hydraulic Apparatus for Engineering Computations‘ at the Internet Archive.

In a rather pleasing coincidence for this blog post (that you might think was by design rather than just good fortune) this device was actually put to work by the US Army to study the freezing and thawing not of snowmen but of soil (ie, the ground). It’s particularly useful if you’re building and maintaining a military airfield (or even just roads) to know how well the concrete runway will survive changes in weather (and how well your aircraft’s wheels will survive after meeting it).

For a modern take on the ‘hydrodynamic calculating machine’ aka water computer see this video from science communicator Steve Mould in which he creates a computer that can do some simple additions.

The puzzle of digital compression

Our snowman’s been sitting around for a while and his ice has probably become a bit compacted, so he might be taking up less space (or he might have melted). Compression is a technique computer scientists use to make big data files smaller.

Big files take a long time to transfer from one place to another. The more data the longer it takes, and the more memory is needed to store the information. Compressing the files saves space. Data on computers is stored as long sequences of characters – ultimately as binary 1s and 0s. The idea with compression is that we use an algorithm to change the way the information is represented so that fewer characters are needed to store exactly the same information.

That involves using special codes. Each common word or phrase is replaced by a shorter sequence of symbols. A long file can be made much shorter if it has lots of similar sequences, just as the message below has been shortened. A second algorithm can then be used to get the original back. We’ve turned the idea into a puzzle that involves pattern matching patterns from the code book. Can you work out what the original message was? (Answer tomorrow).

The code: NG1 AMH5 IBEC2 84F6JKO 7JDLC93 (clue: Spooky apparitions are about to appear on Christmas Eve)

The code book (match the letter or number to the word it codes for).

Answer to yesterday’s puzzle

 

The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.

 

CS4FN Advent – Day 4 – Ice skate: detecting neutrinos at the South Pole, figure-skating motion capture, Frozen and a puzzle

This post is part of the CS4FN Christmas Computing Advent Calendar and we are publishing a small post every day, about computer science, until Christmas Day. This is the fourth post and the picture on today’s door was an ice skate, so today’s theme is Very Cold.

A bright red ice skate.

 

IceCube

The South Pole is home to the IceCube Neutrino Observatory. It’s made of thousands of light (optical) sensors which are stretch down deep into the ice, to almost 3,000 metres (3 kilometres) below the surface – this protects the sensors from background radiation so that they can focus on detecting neutrinos, which are teeny tiny particles.

Building the IceCube Observatory – photo from Wikipedia.

Neutrinos can be created by nuclear reactions (lots are produced by our Sun) and radioactive decay. They can whizz through matter harmlessly without notice (as the name suggests, they are pretty neutral), but if a neutrino happens to interact with a water molecule in the ice then they can produce a charged particle which can produce enough radiation of its own for its signal to be picked up by the sensors. The IceCube observatory has even detected neutrinos that may have arrived from outside of our solar system.

These light signals are converted to digital form and the data stored safely on a computer hard drive, then later collected by ship (!) and are taken away for further analysis. (Although there is satellite internet connection on Antarctica the broadband speeds are about 20 times slower than we’d have in our own homes!).

 

Computer science can help skaters leap to new heights

Researchers at the University of Delaware use motion capture to map a figure skater’s movements to a virtual version in a computer (remember the digital twins mentioned on Day Two of the advent calendar). When a skater is struggling with a particular jump the scientists can use mathematical models to run that jump as a computer simulation and see how fast the skater should be spinning, or the best position for their arms. They can then share that information with the skater to help them make the leap successfully (and land safely again afterwards!).

Frozen defrosted

by Peter McOwan, Queen Mary University of London

The hit musical movie Frozen is a mix of hit show tunes, 3D graphics effects, a moral message and loads of topics from computer science. The lead character Princess Elsa creates artificial life in the form of snowman, Olaf, the comedy sidekick, uses nanotechnology based ice dress making, employs 3D printing to build an ice palace by simply stamping her foot and singing and must be complimented for the outstanding mathematical feat of including the word ‘fractal’ in a hit song. In the USA the success of the movie has been used to get girls interested in coding by creating new ice skating routines for the film’s princesses, and devising their own frozen fractals…and let it go, let it go, … you all know the rest.

 

Today’s puzzle

This is a kriss-kross puzzle and you solve it by fitting the words into the grid. Answer tomorrow.

 

Answer to yesterday’s puzzle

Yesterday we posed this puzzle –

“One of Santa’s Elves Mikey Muddlebug has the job making giant novelty crackers each out of a piece of paper that is 1m long. They need 120 crackers and start with a strip of paper 120m long. Mikey Muddlebug sets the cracker machine to make 120 cuts that each take one second to do. Elven expects to be finished in exactly 2 minutes and he will then head off for a snooze: job done. Does he get the snooze he is expecting or is he in a muddle?”

Cutting the crackers

It only takes 119 cuts to split a strip in to 120 pieces (just as in only takes one cut to cut something in to two pieces) You get the last piece without an extra cut. If Mikey makes 120 cuts then he will have made a mistake. He won’t get that snooze. He will end up with pieces that are too short and have to start all over again.

There’s a link to programming: Programmers make similar thinking mistakes to this and it leads to bugs in programs. It is important that you can think clearly and avoid making this kind of muddle. They often lose track of how many times they need to do something, and do one too few or one too many.

Here is an actual example for those with some coding experience. When coding Bubble sort to sort an array, you run a loop down the array comparing pairs of items and swapping them if they are in the wrong order. It is a mistake to run the loop right to the end of the array, though. You stop one short of the end. Why? Because each comparison you do is of the current entry and the next entry, and there is no next entry at the end! You stop one place earlier.

Bubble sort does lots of passes like this gradually swapping everything in to the right place. You can make a similar thinking mistake to the above when working out how many passes of the array you need too. Each pass slots a single value into the right place (as you take the biggest value found so far with you as you scan down the array on each pass, drop it at it’s correct position). That means on every pass you put one thing in the correct position. So how many passes do you need to guarantee sorting 10 things? 9 not 10! Once 9 things are in the right position the 10th must be too as there is no where else for it to go!

CS4FN Advent – Day 3 – woolly hat: warming versus cooling

Welcome to Day 3 of the CS4FN Christmas Computing Advent Calendar. The picture on the ‘box’ was a woolly bobble / pom-pom hat, so let’s see if we can find something computer-ish that might vaguely relate to that in a fairly tenuous way 🙂

Red woolly bobble hat with a white pom-pom on top. Very festive.

Keeping your (computer) cool

Hats help keep your head warm on a chilly day, keeping the warmth IN but computers need to have a way of keeping excess heat OUT to prevent damage to the components (…which are the things creating the heat in the first place of course). You don’t want to fry your graphics card or the Central Processing Unit (the CPU which is your computer’s brain).

I’m your biggest fan

Most computers have a fan which helps regulate the temperature and there are other design features that help heat flow away, including heat sinks which are designed so that a large surface area (which lets heat radiate away) can fit into a small area (see examples below).

Computer fan image by fancycrave1 from Pixabay showing black fan blades (just below the green, yellow and blue wires attached to the blue Intel sticker) above the grey metallic heat sink.

 

Above: three different types of heat sink, from Wikipedia.

 

Cooling fluids

A much rarer way to remove heat from a computer has been to use a special coolant liquid. In 1985 the Cray-2 supercomputer (which was the fastest computer at the time) was cooled by being immersed in a cooling fluid called Fluorinert which, somewhat ironically, had a very high Global Warming Potential (very similar to the fluorocarbons that were once used to cool fridges).

A Cray-2 supercomputer.

Reducing power

Another way of keeping computers cooled is to reduce their power so that they generate less heat in the first place. A modern computer in danger of overheating can run its processors and chips at a lower speed.

 

Bubble Sort

If you want to re-order a bobble hat you can just buy a new one but if you want to re-order lots of bobble hats (that is, put them in a particular order) you might use bobble sort, sorry – bubble sort, to re-order them by size or colour etc.

Bubble sort is an algorithm that lets you work your way through a list of items, comparing any two items and deciding which one goes before the other. You keep going through your list repeatedly until all the items are in the correct order. Computer scientists use lots of different ways to sort information but you can see the bubble sort danced out in the video below.

Teachers can try out the bubble sort activity in class, as a way of introducing arrays and logical / algorithmic thinking.

 

Answer to yesterday’s puzzle

Did you work out Elisa Huen’s puzzle from yesterday? Here’s the answer.

 

Today’s puzzle: Elvish Muddle Bugs

The Elves help Santa, but sometimes get in a muddle and make mistakes. Can you spot their mistakes, and help make sure all their work is done and so ultimately all the presents are delivered. Oddly, Elves and programmers make similar kinds of mistakes! The answer will be in Day Four’s post tomorrow.

Cutting the crackers

One of Santa’s Elves Mikey Muddlebug has the job making giant novelty crackers each out of a piece of paper that is 1m long. They need 120 crackers and start with a strip of paper 120m long. Mikey Muddlebug sets the cracker machine to make 120 cuts that each take one second to do. Elven expects to be finished in exactly 2 minutes and he will then head off for a snooze: job done. Does he get the snooze he is expecting or is he in a muddle?

(Answer tomorrow)

 

 

 

CS4FN Advent – Day 2 – Pairs: mittens, gloves, pair programming, magic tricks

Welcome to the second ‘window’ of the CS4FN Christmas Computing Advent Calendar. The picture on the ‘box’ was a pair of mittens, so today’s focus is on pairs, and a little bit on gloves. Sadly no pear trees though.

A pair of cyan blue Christmas mittens with a black and white snowflake pattern on each.

In this article, by a pair (ho ho) of computer scientists (Jane Waite and Paul Curzon), you can find out how paired devices can be used to steal money from people, picking pockets at a distance.

Credit cards denim jeans blue image by TheDigitalWay from Pixabay

i-pickpocket

 

 

Gestural gloves

Working with scientists musician Imogen Heap developed Mi.Mu gloves, a wearable musical instrument in glove form which lets the wearer map hand movements (gestures) to a particular musical effect (pairing a gesture to an action). The gloves contain sensors which can measure the speed and position of the hands and can send this information wirelessly to a controlling computer which can then trigger the sound effect that the musician previously mapped to that hand movement.

You can watch Imogen talk about and demo the gloves here and in the video below, which also looks at the ways in which the gloves might help disabled people to make music.

Further reading

The glove that controls your cords… (a CS4FN article by Jane Waite)

 

Pair programming

‘Pair programming’ involves having two people working together on one computer to write and edit code. One person is the ‘Driver’ who writes the code and explains what it’s going to do, the other person is the ‘Navigator’ who observes and makes suggestions and corrections. This is a way to bring two different perspectives on the same code, which is being edited, reviewed and debugged in real-time. Importantly, the two people in the mini-team switch roles regularly. Pair programming is widely used in industry and increasingly being used in the classroom – it can really help people who are learning about computers and how to program to talk through what they’re doing with someone else (you may have done this yourself in class). However, some people prefer to work by themselves and pair programming takes up two people’s time instead of one, but it can also produce better code with fewer bugs. It does need good communication between the two people working on the task though (and good communication is a very important skill in computer science!).

Here’s a short video from Code.org which shows how it’s done.

 

Digital Twins

A digital twin is a computer-based model that represents a real, physical thing (such as a jet engine or car component) and which behaves as closely as possible to the real thing. Taking information from the real-world version and applying it to the digital twin lets engineers and designers test things virtually, to see how the physical object would behave under different circumstances and to help spot (and fix) problems.

Reflections Image by beate bachmann from Pixabay

A magic trick: two cards make a pair

You will need

  • some playing cards
  • your hands (no mittens)
  • another pair of mitten-free hands to do the trick on

Find a pack of cards and take out 15 (doesn’t matter which ones, pick a card, any card, but 15 of them). Ask someone to put their hands on a table but with their fingers spread as if they’re playing a piano. You are going to do a magic trick that involves slotting pairs of cards between their fingers (10 fingers gives 8 spaces). As you do this you’ll ask them to say with you “two cards make a pair”. Take the first pair and slot them between the first space on their left hand (between their little finger and their ring finger) and both of you say “two cards make a pair”.

The magician puts pairs of cards between the assistant’s fingers.

Repeat with another pair of cards between ring finger and middle finger (“two cards make a pair”) and twice again between middle and index, and between index and thumb – saying “two cards make a pair” each time you do. You’ve now got 8 cards in 4 pairs in their left hand.

Repeat the same process on their right hand saying “two cards make a pair” each time (but you only have 7 cards left so can only make 3 pairs). There’s one card left over which can go between their index finger and thumb.

The magician removes the cards and puts them into two piles.

Then you’ll take back each pair of cards and lay them on the table, separating them into two different piles – each time saying “two cards make a pair”. Again you’ll have one left over. Ask the person to choose which pile it goes on. You, the magician, are going to magically move the card from the pile they’ve chosen to the other pile, but you’re going to do it invisibly by hiding the card in your palm (‘palming’). To find out how to do the trick, and how this can be used to think about the ways in which “self-working” magic tricks are like algorithms have a look at the full instructions and video below.

The Invisible Palming Activity

 

Something to print and colour in

Did you work out yesterday’s colour-in puzzle from Elaine Huen? Here’s the answer.

Today’s Christmas colour-in puzzle is by Elisa Huen. A clue is “helps deliver the Christmas presents”. (The answer will be in Day 3 of the CS4FN advent calendar, tomorrow).

 

The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.