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Thursday, March 31, 2011
Honeypot Paranoiaeveral of you regular blogreaders - may the FSM bless your naive little assumed souls - have sent me links to newspaper articles with what purports to be an FBI appeal for crypto-assistance. my interest in codebreaking it piques my curiosity, BUT I shan't be providing any feedback. Consider please :-
The FBI - claiming to be unable to break the code themselves - would have asked the NSA for some intra-agency help. The NSA would have replied they too could not decode it, regardless of whether that was true or not, the NSA does not tell people what they can and cannot do, I can promise you that!
The FBI then ask for public help from naive geeks. Or do they? Or is it a honeypot? There isn't even a pecuniary reward, so it is only a 'reputation' thing for crypto-geeks. Let us assume - just for the sake of argument, I'm not claiming anything - that I break this code. Do I want to tell the FBI and the NSA that I can do that? No! I too do not tell people what I can and cannot do. After all, they have given us no information about their capabilities either. That's the honeypot paranoid dilemma of cryptographers everywhere ;-)
Tuesday, March 29, 2011
Map Distortions Reduxust last week, when I wrote about map distortions, Carol (UK) asked "...what would [the] maps look like if the Earth was not a ball?". Well, if the Earth were flat, as in Terry Pratchett's Discworld®, making a flat chart would be very simple. Similarly, for Larry Niven's Ringworld® you would just need to 'cut' the cylindrical ring in one place and maybe attach 2 copies adjacently to avoid any discontinuity along the cut. A Möbius strip would need to map both 'sides' of course. A donut-shaped world would need one cut through a side of the donut and another along the inner diameter. Making a map of Russel's teapot is too hard for me to do in my head, but I DO know that it would take 7 instead of 4 colours to colour such a teapot map ;-)
As chance would have it, my friend Lothar - a geography teacher - and I were talking about map projections just last month. So I made him a little present. Most of the maps we have seen so far aim to produce a rectangular flat chart. But we also saw a Martin Waldseemüller style world map with 12 non-contiguous gores. So for Lothar's present I gave him a printout of the same map projected onto the 5 regular convex polyhedra ( = the Platonic solids) using non-contiguous gores. By cutting out the maps (leaving tabs on the outside of the gores so that he could glue them together in 3D) he got a view of 'the Earth' as a tetrahedron, a cube, an octahedron, an icosohedron and a dodecahedron. Conversely, Carol, if the world were any of the 5 convex regular polyhedra, we could use the appropriate gored map to which I link in the paragraph below.
The Center for Spatially Integrated Social Science has some PDF download files for the 5 polyhedral projections. If you are a teacher, get your class to print these out, cut them out (adding tabs to the gores) and glue them together. If you also include a knotted thread inside each, you can hang them up together as a mobile. Hey presto : you have a lesson synergising maths and geography! :-)
Thursday, March 24, 2011
Elizabeth Taylor, R.I.PElizabeth Taylor has gone for a Burton. Again?
Wednesday, March 23, 2011
Map Distortions continuedhis is basically a continuation of monday's essay. Derek (UK) asked me to "...provide some examples of choosing a projection depending upon its intended use...". Here are 3 alternatives to Mercator maps.
Example 1 : The Mercator projection is not suited for airplane pilots because the north-south scale varies with the tangent of the latitude. Pilots want the scale to be a) constant over the map and b) the same in N-S and E-W directions and all various directions in between. They also want directions to be conserved over the projection.
For this we choose a conic projection. Please imagine putting a cone over the globe; it would touch the globe along one latitude, but the ends would be raised far above the surface, distorting the map more than necessary. So we let the section of the cone sink into the globe at the middle of the map (the red line in profile) and the cone touches the surface of the globe along two latitudes (shown here as green lines). Result? the distortions on the map can be kept below any chosen limit depending on the scale of the map. Correspondingly, the meridians will slope in towards the top of the map (northern hemisphere). So directions for the best rhumb line ( loxodrome/compass course) are best measured midway between start and finish of the planned journey.
Example 2 : Cast your mind back to the Cold War. Assume you are the commander of a Soviet submarine (equipped with intermediate range nuke missiles) hiding beneath the waves anywhere in the seven seas. When the prepare-for-nuke-missile-war signal comes you are told your target and are to proceed along the shortest possible route to get within range of that target, then signal back 'on position'. Let's say you are told your target will be Washington DC. You pull out a gnomic azimuthal projection map centered on Washington DC from your map locker and draw a straight line from your present position (which only you know) to Washington DC. That straight line of the gnomic azimuthal projection will be a great circle track on the globe, giving you the shortest distance. Cruise along that straight line/great circle until within range, then call back, confirming 'on position'. On a Mercator projection the orthodrome line (aka Great Circle) would be curved, making your navigation task much more difficult :-( If your target was an AFB missile base near New Orleans, you would use a different map (same projection, different centre). One map/target.
Example 3 : Assume you are a manufacturer of classroom globes. Of course your printing press can only print on flat sheets of paper. So you need to print this projection then glue it (with abutting gores) onto the globe :-
This is based on Martin Waldseemüller's 1507 world map, it does look like a single piece of orange-peel, doesn't it? [a gore is a triangular gusset, not Al Gore].
Comments (2) :
Monday, March 21, 2011
Map Distortions :-(ecently a teenage friend was showing me her new Tablet computer and we were playing with Google Maps. At one point - reason unknown to me - she zoomed all the way out, getting this map :-
She thought for a while and then surprised me by saying "I knew Greenland is big, but I didn't know it's as big as Africa!" I burst out laughing and said "But it isn't. It's only about as big as Zaire, which is what the Congo was called when Mobuto was running the place. The map distorts areas, especially at high latitudes. Compare them on a globe." Which we did :-
Then I showed her where Zaire was (the area shown in white below) :-
A quick diversion into Wikipedia showed us that Greenland covers some 2,166,086 square kilometers and that Zaire (which was a single country from 1965-1997, when Mobuto was overthrown) was 8% larger, covering 2,345,410 square kilometers. That 8% is more than the area of England!
"So the map is wrong! ? " she asked, confused.
"No, all maps are projections. You can't make a flat map out of the (surface) peel from a sphere without distorting one or more things. Some maps conserve area, some scale, some direction. You choose what map to use depending on what property you want to conserve and accept that other properties will be distorted." I explained.
"This is a Mercator projection, in use since 1569 afaik. 16th century navigators found it easy to use because lines of constant course (called loxodromes, constant angle relative to the meridians) are shown as straight lines. But the meridians are distortedly shown as parallels instead of running together at the poles, so their 'straight' lines really spiral around the globe."
She interrupted "But why does that make Greenland look so big, when it isn't? Why are the areas distorted too?"
So I explained how Mercator projections are made; I refer you to the sketch on the left.
Pretend the Earth is a transparent ball wrapped in a transparent plastic cylinder (the black lines in the diagram). I've marked the equator as a horizontal red line across the centre. The lower red line drooping down by an angle θ from this exits the ball at the lower end of Zaire, so Zaire gets projected onto the cylinder as shown by the green line.
The two red lines on the upper right of the sketch also subtend the same angle θ at the centre of the Earth and cut the ball at the northern and southern ends of Greenland. Projected onto the cylinder, we see that Greenland is shown by the blue line. It appears larger, although the angles subtended (θ) are the same. So the areas get progressively more distorted as the latitudes increase. In fact, the Mercator projection - tangential to the equator - is pretty useless above the arctic circle (latitude 66° 33' 44'' north).
"So why does Google use it then, if it's so wrong?" she asked.
I think that Google uses the Mercator projection because that is what their users are used to. The users learned ONLY that map in school, because mapmakers and atlas makers were loathe to risk showing other projections for fear of losing the school atlas market :-(
In fact I would prefer it if Google used its influence for good to change the map projection they use to Canters W10 Low-error projection with 40 coefficients. Apart from the Antarctic, Canters W10 has the lowest distortions (areas, directions, distances) of all. It's just unconventional.
Frank Canters is a professor at the Vrije Universiteit in Brussels, Belgium and is one of the world's leading cartographers. His work deserves to be better known; let this blog article be a small contribution in that direction.
PS : For those of you who can read German : I would like to point you to Dr.Ralf Böhm's excellent webpages, inter alia on all the different cartographic nets. The W10 map above is a direct link to one of his maps :-)
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Saturday, March 19, 2011
Common interests ;-)hy do you think Silvio Berlusconi is still a great friend of Gadaffi?
What possible common interest could they share?
Unfounded rumour has it that the Italian Secret Service informed Berlusconi that Gadaffi has the world's largest collection of great camel toe photos ;-)
Have a nice weekend, folks!
Thursday, March 17, 2011
In Memoriam : Heinz Nixdorfyears ago today Heinz Nixdorf died during the CeBit trade fair in Hanover. He was the founder, chairman and principle owner of Nixdorf Computer AG, a company for whom I worked 1975-1990 (when it was taken over by Siemens). Those 15 years were the most pleasurable of my working life, Heinz Nixdorf was an excellent employer. I am sure many thousands of his ex-employees still miss him and will be thinking of his memory today. On sunday the HNF, which is the world's largest computer museum, will be holding an open day in his memory, 10-18:00 hours :-)
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Wednesday, March 16, 2011
Half Lives of Fallout Isotopesack in Monday's comments, Jenny (Ibiza) asked "So how long is the Japanese fallout going to be a problem?"
First of all, let me borrow this map from the Bad Astronomy blog to point out that the Fukushima type of reactor does not produce the same kind of heavy materials as Chernobyl did. The map that showed up 2 days ago is IMHO a fraud. It is unlikely that the fallout cloud will reach the USA at any dangerous levels let alone Europe, which is 9000 kms away against the prevailing winds!
The explosions at Fukushima were chemical hydrogen explosions and were NOT nuclear explosions. The exposed core reacts with the high pressure steam at about 2000°C to form zirconium and hydrogen. What we DO have is effectively three dirty bombs, ejecting radioactive isotopes in the form of dust particles into the atmosphere :-(
It takes a dosage of 4 Sieverts to kill 50% of the population, one Sievert would kill 5% of the population. Background level is 1-2 mS/y, smokers inhale an additional 5-10mS/y. 30 milliSieverts/year is regarded as the maximum occupational danger level (airline pilots, etc get about 5-9 mS/y). Some areas in Japan may get that level, Europe almost certainly will not.
If you prefer to use Bequerels instead of Sieverts, think of it like this : Background level here for foodstuffs is about 40 Bequerels/kilogramm, warning levels for foods after Chernobyl were set (arbitrarily?) at 800 B/Kg. But before my cancer operation I had a scintigramm at 4 MEGA-Bequerels = 47 THOUSAND Bequerels/kilogramm without any negative effects :-)
That said, your questions was about the duration of the fallout. Most of the fallout cloud should go out over the Pacific where it will be washed out of the sky by rain. Each component of the fallout has a different duration depending on which isotope it is. Each isotope has a so-called half-life. This means that half its radiation is gone after this half-life. Since 210 =1,000 and 220 = 1,000,000 it takes 10 respectively 20 half-lives for that isotope's radiation to fall to 1 thousandth resp. one millionth of its initial value.
The dangerous elements which accumulate in the body are iodine, cesium and plutonium (reactor Fukushima #3 is a MOX reactor).
Iodine 131 has a half-life of 8 days. It is a β and γ emitter. Iodine congregates in the thyroid gland. You can take non-radioactive I127 pills to saturate your thyroid preemptively, so that it doesn't take up any I131 :-)
Cesium137 has a half-life of about 33 years, β and γ emitter. The body treats cesium like potassium, so it is eventually excreted. but can cause many different types of cancer, particularly in the excretion filters (liver and kidneys). Afaik, special dialysis needed :-(
Plutonium239 has a half-life of about 24,000 years, so it doesn't go away. It is an α and γ emitter which congregates in the bone marrow where the α particles can do serious damage quickly. I presume the only help would be bone-marrow transplants if there is enough material available :-(
My 2 tips : 1) don't eat any Kobe beef, imported Sushi or Pacific fish (fishing area #61) unless it has been officially checked for radiation first. 2) if you have a Japanese car or motorcycle etc., buy any spares you might need over the next three years now; they may not be available long until the factories get restarted. I'm talking Honda, Toyota etc.
We are living in interesting times :-(
Keep safe! :-)
Comments (5) :
Tuesday, March 15, 2011
PI day in the US yesterdayYesterday was day (3.14) in the US, so called because of the way they write dates (month first, then day). So 7 of us went to the pub and had 22 beers, thus averaging 22/7 beers per person. I remember when at university 113 of us students shared 355 beers for 7 digits of precision, averaging 355/113. Or, as the great physicist Albert Einstein once said after reading a paper by Dirac, : "How I need a drink, alcoholic of course, after the heavy chapters involving quantum mechanics!"
PS: You might like to write down the number of letters in each word of that italicised quotation (15 digits in total) to get the mnemonic joke there ;-)
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"Now I will a rhyme construct By chosen words the young instruct. Cunningly devised endeavour, Con it and remember ever. Widths of circle here you see Sketched out in strange obscurity."Charles wrote : "My daughter sent this to me. I thought you might enjoy it."
Monday, March 14, 2011
Nuclear core meltdown :-(n view of the unfortunate events following the earthquake and tsunami in Japan, I thought I'd just give you a layman's summary of how nuclear core meltdowns occur, referring to the sketch below.
The reactor core (1) consists of uranium pellets each one or two cms long fitted into the socalled fuel rods. The steel container (shown in yellow, lower left) around the reactor core (shown in orange) is really just a big kettle. High pressure water as primary coolant is circulated via the coolant pumps (at 2). The chain reaction is controlled by raising or lowering the reaction-dampening rods (shown at 3). The dampening rods absorb neutrons and slow them down so the chain reaction is slowed or even stopped. The overheated high-pressure water (shown in orange) enters the heat exchanger (4) and is cooled (shown there in yellow) and pumped(2) around again. The cooler flow keeps the core(1) sufficiently cooled. In the heat exchanger secondary coolant (water) boils(4) generating steam (5) which is used to drive a steam turbine coupled to an electrical generator (neither shown) before being condensed and recycled to the heat exchanger.
When the reactor is scrammed (shut down in an emergency) the damper rods (3) drop (by gravity) into the core, absorbing enough neutrons to stop the chain reaction. The fuel rods and the core are still very hot. Normal spontaneous emission of neutrons from the uranium pellets continues(!!!) [= radioactivity], although the chain reaction is stopped. This spontaneous emission (which may be 10-15% of peak capacity) keeps the core hot for quite a long while , which is why it is important that the primary coolant keeps circulating.
In Japan, the electricity supply to the coolant pumps failed due the earthquake. So the backup diesel generators should kick in immediately. If these were fatally damaged by the earthquake (e.g. the diesel tanks split open), then the 3rd line of defense (batteries) kick in. But the batteries can only power the pumps for 5 or 6 hours [only 2 here in Germany :-(]:-(
If neither the electrical supply nor the diesel generators can be restarted within this time, the energy-hungry primary coolant pumps stop :-(
The reactor is still generating heat from the spontaneous emissions and so gets hotter. The primary coolant boils, blowing radioactive steam through a safety valve in the containment housing(6). As it boils off, the fuel rods become exposed. The water which was working as a moderator to dampen the reactions is gone and the core can get hotter a lot faster. When 540°C is reached, the uranium pellets melt, flowing to the bottom of the reactor. They are now closer together (liquid) and so could even restart a chain reaction afaik. Even without that they are hot enough to eat their way through the concrete containment vessel (6) and a huge heap of highly radioactive slag seeps into the earth below the reactor, boiling any water it finds there (reactors are built next to rivers or the sea to ensure a permanent supply of secondary heat exchanger coolant). The pressure of the steam will be enough to blow off (the top of) the containment vessel (6) taking radioactive fallout from the slag with it, as it did in Tschenobyl :-(
Core meltdown is to be avoided by all means possible. In Japan they are pumping seawater into the reactor now as replacement primary coolant. If this works, the corrosion will mean they will have to write off the reactor permanently. Adding boric acid is done because the boron will absorb more of the spontaneous neutrons which are still feeding the nuclear fire.
The fallout will contain plutonium and strontium-90 particles as well as radioactive isotopes of iodine. Normal iodine pills are to be taken to pre-occupy your glands so that there is no/less room left for the radioactive isotopes. If Japan is lucky, the prevailing winds will carry the fallout out over the Pacific where rains should wash a lot of the cloud out of the sky. Expect remaining fallout to reach the Phillipines by thursday :-( However meteorological data predicts a wind flow from the north by then, so the fallout might reach Tokio on the same time scale.
Depending on the intensity of the fallout, there may be hundreds of thousands of longer term cancer deaths in the area :-(
I hope this helps you blogreaders understand what is happening in Japan.
Comments (4) :
Friday, March 11, 2011
Precautionary Landing made nearby
A VFR pilot flying an Alpi 300S from Tannheim to Melle on Wednesday got caught out by the cloud lowering to the hilltops ( = the terrain rising into the clouds) about 16:15 local time. He decided (correctly, IMHO) to put the plane down in a field just down the road from us in Dalheim rather than continue any hair-raising scud-running. Unfortunately the right undercart leg broke on the rough ground (no bush wheels used). Pilot and passenger walked away unhurt, across the field, down the lane and into Frau Brandt's pub to call the nearest tower calling off any rescue efforts. If you are going to have to make a precautionary landing, be sure you do it next to a pub ;-)
Wednesday, March 9, 2011
Polyglottal Stop 'n GoSanibonani. Ukhuluma isiNgisi na? Ngisaqala ukufunda isiZulu*.
t a recent multinational dinner party the talk drifted around between being in French, English, Bengali and German depending on who was talking/listening. And since there was a retired classics teacher there too, I was half expecting a contribution in Latin also ;-) Apart from an American guest who was restricted to a subset of English, everyone else was multilingual. But it got me interested in the size of different language speaking groups. Here's what I found out :-
The UN says there are 6909 languages (sic!), but 80 languages comprise 80% of those spoken. Mandarin is the largest (850 million speakers), Spanish and English have about 350 million (but over 1,000 million can understand some English). Then Hindi, Urdu, Arabian, Bengali etc. German comes in tenth with over 100 million speakers (including even Bavarians ;-).
The smallest languages here in Germany are North Friesan (10,000) and Saterfresian(2,000 speakers). Wikipedia claims the smallest language group is Yaghan, spoken only by Cristina Calderón of Ukika Village on Isla Navarino, Chile. Presumably she talks to herself a lot ;-)
Some Trekkies can even converse in Klingon ;-) Hab SoSlI' Quch!**
What languages can you understand? Which ones do you speak fluently?
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Tuesday, March 8, 2011
Dear Pentagon Visitors...
Dear Pentagon Visitors, what is it that you are looking for exactly whenever you make one of your flash-in flash-out visits to this blog? I've been doing some traffic analysis on your visits, but they don't tell a consistent tale.
Sometimes you look at my crypto pages, but that it is all very simple public domain stuff. Yes, I have published some crypto stuff at West Point, so you can read that there, not here. In the unlikely event that I know some crypto that your guys at the NSA don't, I can assure you I wouldn't be publishing it.
If you like, I could write an article on the design errors in some US and UK nuclear weapons; being careful to stay within the confines of the Official Secrets Act, because, let's face it, you're going to extradite Julian Assange, and punish him, merely for exposing your (not his) war crimes :-(
Or is it the list of EDU sites (down at the bottom of the right sidebar)? This is just a spinoff of my analyses to see what my university readers like to read, after all, they are a large part (16%?) of my readership. Don't think I'm corrupting US youth, do you? Yes, I used to do some Bush-bashing, but less now that Obama is CinC. Or did you come to read about the Irak War Justification ?
Update 15/3/2011 : United States Army Intelligence Center @ Fort Huachuca came for a visit too. Welcome aboard, guys ;-) Find anything useful?
Monday, March 7, 2011
Her Majesty's Venn Diagram
Kate Middleton's recent homework ;-)
This post is to help you distinguish between the UK, GB, the British Isles, the Commonwealth, B.O.T etc etc. Posted especially for 4D and as a welcome to the blogosphere for Mick Daly, a fellow ex-pat, just starting blogging ;-)
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Saturday, March 5, 2011
Recommended movie for the weekend : The Motorcycle Diaries, a motivational road movie from 2004 showing us how Ernesto gradually turned into Che :-)
"Every generation needs a journey story; every generation needs a story about what it is to be transformed by geography, what it is to be transformed by encounters with cultures and people that are alien from yourself, and you know that age group 15 to 25, that’s the perfect generation to get on a motorcycle, to hit the road, to put on your backpack and just go out." - José Rivera, screenwriter, NPR.
This posting was triggered by the announcement of the death of Alberto Granado, the motorcycle companion of Ernesto Che Guevara, who has died in Cuba at the age of 88. R.I.P. The pair's 8-month journey around Latin America was immortalised in the aforementioned film The Motorcycle Diaries.
Posting this for Kees Kennis; just as a biographical/history lesson ;-)
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Friday, March 4, 2011
Get a head start
Now that the 2011 motorcycling season is starting (well, it is here in Germany) just stop for a second and ask yourself how old your helmet is. Need a new one?
It's a good idea to replace them every 5-6 years or so, they don't last forever you know, even without any knocks and scrapes :-)
Wednesday, March 2, 2011
Only the Brits! ;-)Only the Brits could send a Navy ship named after a pork sausage to rescue British citizens from a muslim country (Libya) ....
All speed, HMS Cumberland!
Comments (1) :
23 Recent Writings
FWIW : 23 is the number of the Illuminati, folks ;-)
Honeypot Paranoia ;-)
Map Distortions Redux
Elizabeth Taylor, R.I.P
Map Distortions cont'd
Common Interests ;-)
Heinz Nixdorf, RIP.
Half Lives :-(
day in the US ;-)
Nuclear core meltdown :-(
Polyglottal Stop 'n Go
Dear Pentagon Visitors...
H.M's Venn Diagramm
Get a head start
Only the Brits! ;-)
P51 cockpit, pilot's view
Prostate Cancer Age Hist.
US Bankruptcy ?
Dr.Copy and Paste :-(
Spam forward ;-)
Tarzan and Jane ;-)
Rosy Posy, Bunga Bunga
Greased Lightning :-)
Tide comes in, tide...
On-Target correlation :-(
Irak War Justification :-(
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Blog Dewey Decimal Classification : 153
FWIW, 153 is a triangular number, meaning that you can arrange 153 items into an equilateral triangle (with 17 items on a side). It is also one of the six known truncated triangular numbers, because 1 and 15 are triangular numbers as well. It is a hexagonal number, meaning that you can distribute 153 points evenly at the corners and along the sides of a hexagon. It is the smallest 3-narcissistic number. This means it’s the sum of the cubes of its digits. It is the sum of the first five positive factorials. Yup, this is a 153-type blog. QED ;-)
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