Friday 29 November 2013

Peltier Tiles and Toroid Beads

Producing a small current from a Peltier Tile


Recently I purchased some Peltier tiles from ebay. A Peltier device is something which is able to change a temperature differential into voltage (Seebeck Effect) and when a current is run through it, opposite sides of the tile have a temperature difference (one side will be hot and the other side will be cold - and in some cases will require a heatsink to prevent it from damaging the unit).

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Image Source: http://www.tellurex.com/technology/peltier-faq.php

The Peltier tile itself is a ceramic coated tile with tiny n-type and p-type semiconductors coupled together with a junction of copper between each pellet of semiconductor. Like the potato battery, the current is generated when electrons flow from the side absorbing the heat to the side that is releasing the heat.

Both n-type semiconductors and p-type semiconductors are extrinsic semiconductors which means they are "doped" or mixed with specific amounts of impurity. In a n-type semiconductor, each impurity atom produces a free electron which can drift to produce an electrical current. It is called n-type because most of the electrons carrying the charge are negatively charged free electrons produced by the doping process. In a p-type semiconductor, each impurity atom has a hole in the valence band. It is doped with a different element such as which has not enough electrons to form covalent bonds with all of the semiconductor's atoms, thus leaving a hole in the covalent bond structure. Electrons from the n-type semiconductor flow through to the holes of the p-type semiconductor, but because of the arrangement the charge and the heat are all flowing in the same direction...

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Image Source: http://www.tellurex.com/technology/peltier-faq.php

Initial results with the tile were as follows:

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Hand and cold air - 0.04v

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Hand and cup of ice - 0.23v

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Top of a Bowl of Soup (55ºC) and Cup of ice (11-15ºC) - 0.58v

More experiments may or may not ensue as the main motivation for this experiment was just that I just wanted to see and feel for myself how peltier tiles actually work...



Where to find a toroid bead (ferrite core) in your house


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I wanted to find a toroid bead to build a joule thief. I eventually found one inside a used fluorescent lightbulb. I've been hoarding some broken lightbulbs in the studio - finally they are of some use! My classmate Frank helped me crack up the casing with a pair of pliers. I found this broken bulb in September so the capacitor has had sufficient time to discharge - but apparently you will need to make sure that the capacitor has really discharged if the bulb was recently used.

It was interesting to see what was inside the lightbulb. It was a bit like discovering the existence of a new fruit or something; cutting it open to see what this strange fruit looked like from the inside and only eating the tasty bits. Note that it has to be a fluorescent lightbulb because a glass lightbulb obviously would not have the circuitry or the ferrite core for us to take out.

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Toroid bead

When I hear the word toroid I think of of torus prims in Second Life. I imagine big inflatable torus shapes floating about. WHICH IT IS. And speaking of donut shaped things...

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DONUTS! INFLATABLE MENORAH! DREIDEL!

It is Hanukkah in Stamford Hill and we noticed this because there were suddenly a lot of exciting donut flavours being displayed at Grodzinskis. Happy Hanukkah!

Monday 25 November 2013

Merlion Windmill

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Last night I dreamt that I had found a Merlion Windmill along Changi Road in Singapore, and I was trying to find out who was the mad and elusive millionaire who had ordered the construction of this giant 12-storey-high monster. Standing at the foot of the Merlion Windmill, I started googling for it on my phone and then I discovered that there was also another replica of this Merlion Windmill in Mexico and also a 24-hr convenience store in Western Australia that had also been named "Merlion Windmill". I was surprised that I had not yet encountered the Merlion Windmill before, considering I had always been living in the east side.

1. Does this mean I should build a new type of novelty merlion hand fan?
2. Is this my brain's way of telling me not to reinvent the windmill?
3. Am I thinking too much about my alternative energy school project?



A text on merlions I wrote a few years ago:

The Merlion was first sighted in 1843, shortly after a large sandstone slab (also known as the Singapore Stone) was blown up by the mouth of the harbour of Singapore. Eyewitnesses record having seen the half-fish, half-lion creature crawl out of the fragments and into the waters of the Singapore River. It is unclear whether the creature had been living underneath the rock, or whether it had been living within the stone. The origins of the Stone from which the merlion came from are also mysterious, and there were rampant rumours that the stone had come from outerspace as it had been present long before there was human habitation in the area, and was covered in a mysterious script that was never deciphered by mankind.

Since the introduction of the first merlion into Singapore waters, more merlions have been sighted around Singapore, although most Merlions no longer live under or inside rocks, but are more commonly sighted perched on top of "waves of rock" which are made of a substance secreted by the animal, which hardens into a rock.

Merlions (binomial name Singapura singalaut) are predominantly marine animals which have a body composed of three distinct parts.

1. Lion head: Many merlions show cephalisation and have a head region with eyes and other sense organs.
2. Scaly Torso: the soft-bodied portion with internal organs, covered with a mantle of decorative, interlocking "scales" which are actually a cuticle secreted by the merlion.
3. Fish foot: the strong muscular fish-finned portion sometimes used for swimming (and capable of limited locomotion). The terminal segments are modified into a tail fan, a region with high surface area that acts as the blade of a paddle in the escape response.

The division of the body into distinct areas seems to have allowed diversification to occur because there can be different types of Merlions adapted to various ways of life, distinguished by modifications to the thoractic area or the tail...

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(To be continued)

Sunday 24 November 2013

Growing Mushrooms, Moss and Lavender - Part I

Growing Mushrooms


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I'm currently trying to grow Oyster Mushrooms. I bought a small quantity of oyster mushroom spawn on ebay recently - the substrate used appears to be millet. After that, I boiled a bog roll (white, no inks, no fragrance) in a pot of water and then when the bog roll had cooled down, I scattered some mushroom spawn on it and inbetween its layers. To be honest I'm not sure if I'm doing it the right way, but we'll check back on these babies in a week's time. Right now they are hiding underneath a box in our rather warm room...

I have wondered about this but I do not think the mushroom spores pose any direct risk to humans - or do they? I mean, we are not going to have an outbreak of mushrooms everywhere in this room, right? Surely it can't be that easy to cultivate mushrooms. I mean, if it were so simple to have an outbreak of mushroom then wouldn't everyone with a slightly damp and dark house have mushrooms growing right out of everything, and wouldn't then people capitalise on that and eat home-cultivated mushrooms all day long?

Growing Moss


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Another thing I've been doing is attempting to grow Moss. MOSS! It is very plentiful on the walls and pavements of West Bank. One day I went out and scraped a container's worth of moss from one of the front walls of our house, after which I broke the moss down into little bits and mixed it down with some Sainsbury's Basics Yoghurt and leftover beer. The yoghurt and beer serve as food for the moss bits, I was actually going to do a comparison of which works better (beer or yoghurt) but I realised that the yoghurt actually acts as a glue, hence the prevalence of people using buttermilk or yoghurt as without this ingredient it will not stick to surfaces. So I just mixed in some yoghurt with all of the moss. I applied this strange smelling moss sludge to the balconey. It hasn't turned mouldy yet which is great, but it probably will take a few weeks to reconstitute together...

Growing Lavender


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Finally, this is a picture of Georges II the Lavender Plant, who has grown from a cutting from a pot of Lavender I bought in Paris last year. Last year around this time, George the human brought a small cutting back from my pot in Paris and stuck this bit of lavender into a pot of soil. Unexpectedly, the clipping of lavender now known as Georges II did not die from the trauma of being suddenly cut and rudely stuffed in a pocket and carried to London, but actually has continued to grow and thrive to this day. I hope that Georges II will have many more happy years on the West Bank Balcony....

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The plant formerly known as Georges I (RIP 2012, due to overzealous watering on my part)

See also: A Mini Tour-de-Paris for a Pot of Lavender

Crossing the English Channel / French Girolles

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Calais

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P&O Ferry

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Dover

I've taken the Eurostar quite a few times but tickets were really costly this time of year, so I decided to try to take the bus instead on my most recent trip to Paris. I got a National Express ticket, but the actual bus I took to and from France was devoid of any of the usual National Express livery. Instead we were in a strangely bright coloured bus with a drawing of a coconut tree on it. It was otherwise very fine and clean and lovely on the inside, except that on my outward journey there seemed to be someone onboard who was transporting a lot of potatoes or yams along with them, so it seemed a bit... um... earthy?


Eurotunnel Route - View Larger Map

The journey from London to Paris is very straightforward without any passport checks - only spot checks. We went via the Eurotunnel and there was no need to disembark from the bus at all. But the journey from Paris to London is more complicated as entering the UK requires one to go through a number of checkpoints. There is a checkpoint in France where you get off the bus and go through two posts (French Border Exit and UK Border Entry) with only your passport in hand. Following that, when you get to the Calais-Dover ferry crossing, you will be required to disembark from your vehicle for the full 1.5 hours of the ferry ride. Finally, our bus was picked out for an additional passport check at Dover; we were all asked to disembark with all luggage (handcarry and stowed luggage). They did a cursory check of people's nationalities and waved almost all of us along without much checking, but they took aside two people for questioning. To be honest it seemed like it had been some sort of pre-planned "sting" operation targeting some individuals which the authorities in Kent must already have known would be on this bus (it is after all the cheapest route and also involves a seemingly less stringently monitored border crossing compared to the planes or intercity trains). Consequently this entire episode caused an immense delay to our journey as our bus was delayed to the point that we met with London's peak hour london traffic all the way back to Victoria... Grr!

The lady bus driver on both my journeys was quite a character: she was quite old but still wore her hair in two blonde pigtails and wore ridiculously bright red blush on her cheeks despite being desperately pale. She also used the talking sat-nav for the ENTIRE EIGHT HOUR BUS JOURNEY FROM LONDON-PARIS, and on the way back from Paris to London. All whilst listening to ABBA. 8 HOURS OF A VERY-POLITELY-LOW-VOLUME PLAYBACK OF SEE THAT GIRL! WATCH THAT SCENE! DIGGING THE DANCING QUEEEEEEEEN! It was so soft and timid, you could not complain. She was a sweetheart. But some of the passengers were quite rude to her because of the delays which were out of her control.

In conclusion: I cannot in good faith recommend the eurolines bus as a means to getting from London to Paris the next time around. It is simply fraught with too many unpredictable factors and the land journey is really very very long and tiring, and on top of that prone to more delays. However, if you are on a severe budget and willing to lower your expectations, then it will be the lowest budget method of getting to and from Paris from London. Eurostar is usually in the £70 range and upwards, and a flight to Charles de Gaulle might be around £60+. A Friday Night bus on Eurolines/National Express booked only one week in advance will cost just £35. Apparently if you book well in advance it might be as low as £9... but who manages to do that?



Girolles / Chanterelles


Whilst visiting Paris, I brought back home a small bag of Golden Chanterelles, aka Girolles (if you're in France) or Pfifferlinge (if you're in Germany). They seem to be much more common on the continent and I don't see them around very often in shops in London unless I've gone to the wild mushroom corner of some farmer's market. They are quite delightful (although not cheap) and I find that these chanterelles have a lot more texture to them and a more 'meaty' taste - perhaps in some ways a little bit similar to an oyster mushroom, but very yellow and much more dense and intense in flavour.

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One morning I made a simple dish of girolle accompanied by couscous with raisins. FOR BREAKFAST! Because breakfast can be epic too. The chanterelles were cooked in a pan with some butter, onion and spinach, a splash of rice dream and a few shavings of parmigiano. This was really fast to prepare. It was kind of madeup but I think I like making up recipes as I go along. Couscous was also really simpler to prepare than I recalled; it is similar to the technique of preparing bulgur wheat, you just boil the same amount of water per ml for each gram of couscous, season the water with salt or a stock cube, and then throw the couscous in the boiling water. Take off the heat and cover with a cloth or a plate for 5 minutes. After which the couscous is done and you can fluff it with a fork. I've often seen couscous paired with sultanas or currents so I threw some on top...

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Wednesday 20 November 2013

Potato Battery and Lasagna Cell

Today I decided to do a preliminary experiment to see how difficult it would be to build a potato battery out of household items. This is probably something everyone does in science class when they're a kid but I don't remember it anymore and I wanted to see firsthand how effective (or ineffective) it would be as a kind of alternative vegetable power source. For some reason I lacked some very basic things such as a WORKING MULTIMETER (the battery has run out and we cannot open the screw compartment because it has been screwed together by an overzealous cretin) or COPPER WIRE (have left all of my gear in school, in desperation I began trying to strip down some random old electrical appliances for copper wire and then decided it doesn't matter if I have or do not have wire if the circuit just connects). In fact making a potato battery will be very fast if you don't have to spend half an hour rummaging in your house for a goddamned crocodile clip.

So, if you have four potatoes and a bunch of pennies and household screws/nails, you will be well on your way to spending an hour trying to use some potatoes to light one extremely tiny LED. WHAT FRUITFUL USE OF YOUR PRECIOUS TIME! Fortunately, if you do not wish to replicate this experiment, you can take it on my good authority (and based on the following documentation) that it works. Do note that the smaller the LED, the likelier you will be to be able to use all your combined potato power to light it. Also, I actually only had FOUR potatoes so it was a good thing that four potatoes was exactly what it takes to light this one LED. (3 baby potatoes seem to be insufficient...)

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Potato Battery

4 baby potatoes
4 shiny 1p or 2p coins
4 galvanised screws/nails
1 very tiny led
Some random bits of wire or a crocodile clip
A rolled towel to hold the potatoes in place

Poke the nail/screw on one end of each potato, and jam a penny halfway into the other end of each potato. Gingerly arrange the four baby potatoes in a sort of daisychain in which the penny of the previous touches the galvanised nail/screw of the next potato. Make a wire connection between a very very low power LED - and connect the longer leg to the first penny in the potato chain and the short leg to the last galvanised nails/screw.

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RESULT! Potato Battery

The electricity is generated because there are two electrodes - the copper coin and the galvanized (zinc coated) screw - and there is an electrolyte (the potato) between them. [FYI: The british 2p and 1p are technically made of bronze, which is 97% copper, so that is why it still works in this experiment]

From Wikipedia: "The energy for the battery comes from the chemical change in the zinc (or other metal) when it dissolves into the acid. The energy does not come from the lemon or potato. The zinc is oxidized inside the lemon, exchanging some of its electrons with the acid in order to reach a lower energy state, and the energy released provides the power. In current practice, zinc is produced by electrowinning of zinc sulfate or pyrometallurgic reduction of zinc with carbon, which requires an energy input. The energy produced in the lemon battery comes from reversing this reaction, recovering some of the energy input during the zinc production."

Apparently, all this electrochemical reaction can also lead to galvanic corrosion. The same principle for building a potato battery can apply to other foods such as lasagna. Apparently, if you cook a lasagna in a steel pan (cathode) and wrap it in aluminum foil (anode), the tasty and salty tomato-acid-laden lasagna will act as the electrolyte. The few points at which the aluminum foil touches the lasagna will cause a concentrated reaction at the point and eventually result in galvanic corrosion at that spot alone, where the aluminum foil will eventually appear to have melted onto the lasagna.

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Example of Lasagna Cell (Image Source: Flickr - Tom Arthur)

Finally, I've realised that this also explains why I have never enjoyed chewing aluminium foil or putting it into my mouth whilst I'm eating, as I have permanent retainers at the back of a number of my teeth. The steel wire ends can be said to be slightly exposed since it has been many years since I last saw an orthodontist and I have also rigorously chewed on it over time. The tasty salty tinfoil wrapped food reacts in my mouth with the salty and acidic food and saliva being the electrolyte, the tinfoil being the anode, and the surgical steel retainers (or any of my other potentially metal fillings) at the back of my teeth being the cathode, culminating in a strange taste/unpleasant sensation of a small potential difference in one's mouth.

The Flora and Fauna of the British Isles: Inis Mor

This post is way overdue. In September we went to the Aran Islands and we saw lots of plants and small animals (and a few large animals). I've noticed that for most of my time in Europe I have always been very excited about plants and animals but everytime I ask others, nobody around me can seem to tell me what they are called. Pish and Tosh! Uneducated heathens! I think its important to be able to identify plants and trees and animals (except that back in Singapore we didn't really have as many animals to identify). So in the face of this glut of animal and plant pictures harvested in September, here is an attempt to get to know the names of the plants and animals.... starting with some of what we saw in Inis Mor...

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This is the grove snail (Cepaea nemoralis) which is one of the most common types of European snails.

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I think this furry fellow is a Fox Moth Caterpillar (Macrothylacia rubi), also a very common european moth.

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This is likely to be a Viviparous lizard, a very common lizard in Europe. Viviparous means it gives birth to its young live, instead of laying eggs.

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This is a Fuchsia plant, a very distinctive and hardy plant which can be seen all over Inis Mor's sheltered areas. This was not apparently native to Ireland or the Aran Islands but is an import from Central or South America where it originates from.

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Ahem. And this is how I found out its name...

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This seems to be a type of Bluebell. I'm not too sure if its the main type or a hybrid bluebell as it seems very pale and seemingly less "formed" than the curly shape of what one would expect of a bluebell. I'm not sure. Any ideas?

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This is a small fern known as a Wall-rue, which mainly grows on limestone and other calcareous rocks. There's even a term for these sort of plants - "epipetric" - which means they grow on top of rocks.

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This is Rock Samphire (Crithmum maritimum) which is apparently edible and is said to have a "pleasant, hot and spicy taste". Sadly we didn't eat any. We did eat some raspberries on a bush but even that seemed risky because we were suspicious about doing it all wrong. Yes I suppose us paranoid city folk have a long way to go to becoming wild foragers living on nature's bounty...

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Not the sweetest of black raspberries but... still a raspberry. Also in case you are wondering what is the difference between a blackberry and black raspberry, I think its that black raspberries have smaller cells and are a bit more furry like in the picture above.

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I wish I could say I could identify this one but I actually don't know. It looked soft and inviting but when I tried to kick it with my foot, it was literally like a rock. You could jump on it and it would be unharmed although it looked like a pillow of green bursting out from between the rocks. It could not even be prised out from the rock with my fingers. It was like stone. This was a strange one... and mainly observed growing on the most extreme parts of the cliff...

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EXTREME CLIFF LIFE!

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MORE OF THE EXTREME CLIFF LIFE!

Well that's it for a short digression into the Flora and Fauna of Inis Mor. There were a lot more such as cows and a whole host of mysteriously similar red berries but finding out their names is quite hard so we'll go a few at a time. So next time: more on the flora and fauna of... Urban London?....

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EXTREME ROCK LIFE!

Everyone is reading the same book on Kindle Paperwhite

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The other day, I noticed that everyone on the Amazon Kindle Paperwhite adverts on the London tube (spotted along the Victoria Line and Jubilee Line) is actually reading the same book. You know those adverts where they have someone waving a Kindle and spouting something along the lines of "OH MY GOD I CAN READ IT AND ITS LIKE PAPER"? Yes. The book on screen in all of those ads is exactly the same! A simple search later revealed that the book in question was "The Hundred-Year-Old Man Who Climbed Out of the Window and Disappeared" by Jonas Jonasson. I wonder, did Jonas Jonasson or his publisher get a cut from doing this "spot"? I always look at books in display cases to see what they thought should be their mannequin's reading material. Has anyone else noticed that they put exactly the same book in every picture?

Curious as to how this book was selected, when I googled for information relating to "The Hundred-Year-Old Man" and its relationship to Amazon Kindle, the most prominent fact that seemed to come to the fore was that earlier this year the kindle version of the book had actually been sold for the staggeringly low price of 20p at one point. TWENTY PENCE! FOR A BOOK! Now I have not yet read the book, but the very idea of selling a book for 20p (0.40 SGD) naturally arouses suspicion that perhaps the book was a gimmick or had something seriously wrong with it to the point that they had to sell it for 20p to move those units. Perhaps it could even be a trashy novel with popular appeal like Fifty Shades of Grey. (Incidentally, there is also a parody novel called Fifty Sheds of Grey which is also on Kindle's 20p list). But a quick google of the book seems to indicate that it is a serious real book. In fact now it is now listed as being back to a 'normal' price of £3.99 on Amazon UK.

I think one tends to be immediately outraged to hear that any real books have been priced at 20p; I would be inclined to assume first that the person who has taken the cut must be the author or publisher rather than the massive e-retailer. But, in this case it was actually Amazon and Sony which had absorbed the cost of the book in the bid to attract more people to their e-book handsets. Turns out the 20p gimmick was simply a result of Amazon attempting to price-match Sony's discounts on those same books.

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Even if the author or publisher does not suffer financially from such a move, it seems like a very bad thing to value a book at something as low as 20p; like a a perfunctory token. Even if they are only to be temporarily priced at 20p, I wonder if in the long write people may come to expect that books CAN be expected to be valued at such prices in future. It is one of those things, like how writers often find that they do not get paid as much as they should do - when in actual fact all the content and meaning is in the writing itself! I do find it ludicrous that a designer and printer can always expect to get paid on time because they produce tangible deliverables, but something like being a copyeditor/writer is sometimes times harder to define and assign value to, when in fact it could very well be the most important part of the process! It seems like a bit of a mean-spirited thing to have a price war over e-books in particular - the thing is that they do not have a physical form, so the way in which we attach a price tag to them could in fact be completely arbitrary. The whole system and economy of the pricing of e-books could go either way right now, and I dislike the notion of a "price war" because I think you should either have it at a reasonable price (but then what would that be?) or completely free, rather than leveling it as CHEAP and almost worthless.

I think that in an ideal world, all e-books should be free because it is already in a format that cannot be controlled - in any case if consumers are used to not paying for e-books then it will be hard to ever re-institute prices on e-books after the precedent has been set on "selling" e-books for practically just pennies. Consequently, all printed books should understood to be sold at a price that must come at a reasonable premium because there is an inherent respect amongst people for the print format of the book. Logically, over time, as digital platforms become more and more prevalent but also cluttered and full of "noise" (due to the oversaturation of media and advertising) it will eventually become more and more desirable to have a physical, tangible form of a book that we can hold and touch and experience - the same way old physical playback formats like VHS and vinyl persistently retain a distinctive appeal despite there being many new digital methods of recording, playing, and distributing/selling music. On top of that, in an ideal situation, all readers should be educated and discerning of what they choose to read or not read. E-books in the public domain or which are offered for free do not pose a threat to the commercial viability of new books because people always desire good, intelligently written and fresh new literature to read and consume, and it will be commonly understood that this comes at a cost because of the immense amount of work, time, energy and authorial brilliance that is necessary to produce new literature.

Monday 4 November 2013

Visit to a Semi-Anechoic Chamber / Cone-of-Silence

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Today some of us managed to have the brief opportunity to visit an anechoic chamber in Imperial College at the Centre for Bio-inspired Technology. However, I must admit that I would classify it more as a semi-anechoic chamber as it had a solid floor (probably due to the need to hold heavy laser equipment and other machinery in the room). Nevertheless, it was very interesting to see it in person.

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Radiation absorbent material (RAM)

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To me, the room itself is visually impressive for its many striking angles. Which of course brings me to thinking of other "anechoic chambers" or radiation absorbing materials and its functions - not just for sound, but also other waveforms such as microwaves or radio waves (in the case of radar). The "look" of such rooms is not so much a design as it is functional. This sort of faceted/angular plane alignment helps reduce the "signature" of the interior space/object, because a curved surface usually reflects waves in a number of different directions whereas a singular plane will reflect them in one direction. As a result many examples of stealth ships and planes designed for military use have a particular look in order to minimise the directions in which radar signals will be reflected. Because there are only sharp angles and planes, this form of "purpose shaping" (as they call it) means that the surfaces that will inadvertently reflect energy can be designed to create some sort of "cone-of-silence" with regards to the object, as well as its intended direction of motion.

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Lockheed F-117 Nighthawk (Image source: Wikimedia Commons)

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Visby Corvette (Image source: Wikimedia Commons)

Thanks to the guys at Imperial for letting us visit their room and thanks to Sam for organising the visit.

Sunday 3 November 2013

Blue Station Door/Structure ID Number Signs on the London Underground

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Outside Green Park station on Piccadilly, there is a curious blue sign near the busstop where I wait for the bus to school. I realized it must be a tube specific sign since I had also seen it inside the tube station. But what do the numbers mean? I decided to collect a few to see if there was a pattern.

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A couple of signs from Baker Street Station, Green Park Station, South Kensington Station, and Seven Sisters Station.

I'm afraid some of the shots were blurry as tube stations were probably not made for people to stand around and take photos in the corridors and it seemed to me as if people wanted to intentionally bump into me to show how annoyed they were at me for standing in the middle of the corridor taking pictures of weird numbers - preventing them from running a few milliseconds faster. Oh london commuters, you so funny.

I noticed that some were on doors, but some were on walls. All doors had these signs, but sometimes there would be a different sign right next to the door. Sometimes the numbers were sequential, and then at other stations, they were not in sequence! It was not hard to see that the first number referred to the level number, but what was the other number? How was it determined?

Eventually, I've traced it to the TFL's official London Underground signs manual. It says this is the "Standard door and level number sign"; aka "Station area ID codes". Searching for more information on this online seems to suggest, from discussions on various forums, that the first number stands for level below ground (Ground level is 1). The second number apparently refers to a room/structure number which is for the reference of the London Fire Brigade, which can refer to these numbers on a special station plan.

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But... how is the second number derived? Why are the numbers so different?

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I tried to look for a detailed station plan but could not find one (I tried to find it for one example, Baker Street); I guess the unavailability of publicly available maps might be for security reasons. However, in the process I did find another great map - Detailed map of London Tube, Underground, Overground, DLR, Tramlink & National Rail:

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Further searching led me to this 3D visualisation of the station maps for certain stations by Andrew Godwin. Its a cool project but was apparently created from memory so it does not have the data that I am seeking:

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Nevertheless it is fantastic to have the complete overview of the position of the stations and all of their platforms. I like the idea of having the grand overview of how these transportation lines work together, bringing us one step closer to finding out the meaning behind each and every sign on the underground...

See Also:
Collection of 3D maps of London Underground/DLR stations
Detailed map of London Tube, Underground, Overground, DLR, Tramlink & National Rail
London Underground signs manual