Monday, September 28, 2009
Dangerous Goods ?
ensorship thrives in Good Old Germany under the guise of 'child-safety' content filters for the web :-(
This blog got banned! And I was not even told about it :-(
The story : The wife was in a clinic recently recovering from a spinal OP. The clinic offers a coin-slot operated PC (just one for several hundred patients!) with internet access. So she checked her blog, our home page and my blog. But when she tried to access this blog, a 'child-protection' filter popped up, denying access. Like, the average patient's age in that clinic has to be over 60, so they need protection from my stuff?
Curious as to what might have prompted this censorship, and guessing it might be done by a context-free page-analysis bot, I've examined this month's blog.
The only thing I can find that might trigger some stupid (non-context sensitive) bot is that the F-word crops up in the article on cryptography as being in the list of the most frequently used 4-letter words in American English. And for this I got censored?
The wife has written in outrage to the filter manufacturer, we'll see what we get for an answer. I bet it'll be condemnation for the use of unsuitable language. WTF ;-)
Coarse (sic!), they'll probably object to me writing 'WTF' too. Very Orwellian. I think this whole political correctness thing has gone to far! And so do the eight-year-olds :-
Friday, September 25, 2009
Old Farts Joke ;-)Usually every friday my favourite Jewish blogger, Elisson, gives us a list of the top ten tunes currently on his iPod. So this joke (courtesy of Paul) is for you, Elisson :-)
"I was in the pub yesterday when I suddenly realized I desperately needed to fart. But my farts are never the quietest. The music was really, really loud, so I timed my farts with the beat so that no-one might hear them. After a couple of songs, I started to feel better. I finished my pint and noticed that everybody was staring at me in disgust. Then I suddenly remembered that I was still listening to my iPod." ;-)
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Thursday, September 24, 2009
Over 70 million served . . .
A company called Gremicha has filed for the bankruptcy of Ischmasch, who own the 'Molot' (The Hammer) division which makes the robust AK-47 Kalaschnikow automatic rifle. The court hearing is set for october 7th. Russian state corporation Rostechnologii owns 57% of Ischmasch, so it'll be interesting to see if there is a rescue-bid.
There are of course numerous plagiarised copies of the AK-47 being built worldwide. That and the fact that the Afghan army is replacing its AK-47s with the smaller bore american M-16s may have contributed to Ischmasch's 985 million Rubel debts last year; it wouldn't surprise me though...
So get yours now, while stocks (and barrels, sights, triggers, magazines etc) last ;-)
Here you are not even allowed to own a spud gun without a licence :-(
Tuesday, September 22, 2009
Old Books :-)e have several thousand books crammed in this house, so the walls are mostly hidden behind bookshelves, this (b)ookshelf alone has some 1200-1300 in it. But of course most of them are from the post-1960 era.
But recently a visitor asked what was the oldest book I own. I fished out a copy of Julius Caesar's De Bello Gallico (see photo, left), which was written about 50 BC, long before the Bible. This version is in the original Latin, with a preface in German. However, it turns out she had meant the date of publication of my particular copy. So I dug out the family bible which it turns out is a 1914 edition (see photo on the right).
Subsequent searching in the study turned up two slightly older ones, shown below. The Brockhaus lexicon is dated 1897, and the algebra textbook dates from 1861.
I also have a number of facsimile copies of older first editions, but being facsimiles they are younger, and thus don't count. Examples would be Chaucer's Canterbury Tales (1478) and Adam Riese's arithmetic textbook from 1533. Beautiful copies :-)
The copy of Beowulf (written in Old English [Anglo-Saxon and some Anglian] between the 8th and 11th century, and thus unreadable by me) is AFAIK a facsimile of the first printed edition (1815) and is thus much younger :-(
What are the oldest books YOU have?
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Friday, September 18, 2009
(Pro-)Creationism; life goes on ;-)
he bible saith :- "In the beginning was the Word...and the Word was god". But what were those words of (the) creation ?
And now, for your delectation, esteemed readers of this blog, His Very Words. Just do it ...
Alphabetise and append, copied in quotes, these very words: "these append, in Alphabetise very and words: quotes, copied." ;-)
Wednesday, September 16, 2009
How to trisect an angle !rom point A draw a vertical line and another line angling off to the right by angle β which you wish to trisect. At an arbitrary point B on the vertical line construct a right angle and draw the extended horizontal line BC. The distance h is the length of the hypoteneuse of the triangle BAC, namely AC.
Draw a large number of rays from A, marking their upper endpoints D such that the distance above the extended horizontal line BC is in each case 2h. The loci of the upper endpoints describe a curve known as the Conchoid of Nicomedes ( circa 200 BC).
In polar coordinates, the Conchoid of Nicomedes has r = a + b*secθ. See below :-
Forgive the inaccuracy of my hand-sketched (=not constructed) conchoid, please.
ow we have the conchoid, we can proceed with the actual trisection. I refer you to my sketch on the left.
From the end of the hypoteneuse at C raise a right angle vertical line from the horizontal side BC. Label the point where it intersects the conchoid D. Actually, this is the only tiny area where we need to construct a segment of the conchoid, we don't need the rest of it :-)
Draw a line DA connecting D on the conchoid with the origin at A. It intersects the horizontal BC at point E. DE=2h, remember.
Now angle BAE is one third of the angle BAC which we have successfully trisected :-)
The "impossible" trick? Note that I subtly deviated from Euclid's compass and straightedge only requirement. When I wrote, I implicitly changed the straightedge into a ruler, sneaking my change past most people :(
Although my construct shown above does in fact trisect the angle β (I won't bore you with the proof, suffice that it exists), it does remain impossible to do the trisection while complying with Euclid's compass and straightedge only requirement.
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Monday, September 14, 2009
Heavy Metal Flower Powerut Geocaching with the dogs near Blankenrode, I came across an old open cast lead/zinc mine. Already, 900 years ago, people were mining the easily accessible lead ores. From ~1850 to 1938 the focus turned to the remaining zinc ores. The heavy metal concentration is still 530 times more than in surrounding areas, soluble zinc is at 1835 times normal concentrations, even the remaining lead is still 27 times more than in surrounding areas. This is usually fatal to any vegetation (and any animals grazing there). However, the grass has evolved to adapt to the high heavy metal concentrations, as have the local violets. In fact this flower, the very rare Viola guestphalica grows ONLY here as it needs the high heavy metal concentration.
But we really need the opinion of Motörhead Headbanger Löst Jimmy to hear (if he still can) if there any other known bands describable as Heavy Metal Flower Power ;-)
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Saturday, September 12, 2009
Denali ViewShannyGirlMe sent this beautiful photo of Mount McKinley, in Denali National Park, Alaska, where another fantastically colourful Indian Summer is about to begin...
Good photographers love to share their photos; thanks, lass!
Comments (1) :
Stu sez: Mt. McKinley is 50 miles away in this teleshot; how clear the air is in Alaska!
Friday, September 11, 2009
Twenty years on, thanks lads :-)
years ago - when I was in charge of the AI research team at Nixdorf Computer AG - three of my computer linguists had just put the finishing touches to the manuscript of their textbook, shown on the left here.
The book is in German, the title translates as 'Knowledge based text generation'. This is considerably harder in German than in English, due to e.g. lexical, syntactical and flexion issues. It was published in 1990, the publisher was Gunter Narr Verlag, Tübingen. The ISBN is 3-87808-677-6, but as far as I know it is now out of print :-(
But then, so are the AI textbooks I had written in the preceding five years; twenty years is a long time in any research field and knowledge ages quickly, even if state-of-the-art at the time:-(
'One moment please ...' (20 years pass) ...
Konrad, Armin and Johannes each went on in their own successful careers, I just want to thank them again for working on my team; oh, and point them to xkcd 114 ;-)
Wednesday, September 9, 2009
999 : Squat Switch Sillinesss regular readers of this blog will know, I spent over a quarter of a century as a Flying Instructor for a couple of local flying clubs. A considerable part of the instruction was dedicated to safety procedures. Hence today's rant!
Any more advanced aeroplane will have a retractable undercarriage and inevitably the question arises 'When to raise the gear?'. Now since a plane climbs better with the gear retracted (thus causing less drag), people want to raise the gear as quickly as possible. However, airline safety procedures call for a positive rate of climb to have been established first. For smaller aircraft (retractable singles and small twins) which are not all that powerful, I go even further and say : Leave the gear down as long as you could land straight ahead on the runway in case of an engine failure/loss of lift!
The worst case, IMHO, is to select 'gear-up' while still on the runway, relying on the squat-switch to keep the gear down. The squat-switch is a safety device which determines if there is a download on the undercarriage legs and prevents the gear from cycling-up in case you have inadvertantly selected 'gear-up' already. Even then, you could just stagger into the air, unloading the squat-switch, the pre-selected gear-up would retract and - if you lost lift for any reason whatsoever - the plane would settle back onto the runway in a very expensive belly-flop. So, I say again, do not pre-select 'up' and thus rely on the squat-switch!
Here's a video of a show-off military pilot foolishly taking off from the squat switch :-(
See what I mean . . . :-((
Monday, September 7, 2009
Dragons' Teeth :-(ecause of all the hypocritical kerfuffle about civilian casualties in Afghanistan, I took a look at the mortality statistics there, to see how dangerous it is compared to here (Germany). And for symmetry's sake I looked at the birthrate too. SURPRISE! Using Wolfram Alpha, I compared the birthrate here (Germany, generally regarded as a safe environment) with the birthrate in Afghanistan (warzone).
Birthrate (German) 0.05%
Median Age (German) 43.4
"By the pricking of my thumbs..."
The Taliban are outbreeding us! What Dragons' Teeth have been sown?
Sunday, September 6, 2009
Codebreaking 102cores of you are sent daily by search engines to read my 2001 entry level cryptanalysis article How to solve Cryptograms. Cryptograms are puzzles made by consistently substituting each letter (e.g. P) by another (e.g. C). They are usually quotations attributed to famous persons. They are simple to crack by virtue of the punctuation and word-spacing being left in. Canadian blogger Diane Oser and I have been corresponding on how much harder they become when the punctuation and word-spacing are removed. Compare the difficulty of cracking this quotation by William Collins "RBKRAEESSTTEASTEEHSHEVTEXMIHNGYEBTEX" with the ease of breaking a regular cryptogram :- "t lvhi ba kh vyaf fetbh... klb t ixtcbhi. ----- jqh fhvb".
But a useful aid to your codebreaking toolkit is to know about lexical patterns in the target language. So I've collated some frequency analysis rankings for you here :-
There are 7 distinct groups in the order of frequency of single letters in English :- ETOANI/RSH/DL/CWUM/FYGPB/VK/XQJZ.
Analysing the first letters only of each word, we rank :- TOAWBCDSFMRHIYEGLNPUJK.
Analysing the last letters only of each word, we rank :- ESTDNRYFLOGHAKMPUW.
The most common doubles rank thus :- SS EE TT FF LL MM OO.
The most common two-letter words rank like this :- of,to,in,it,is,be,as,at,so,we,he,by,or,on,do,if,me,my,up, an,go,no,us,am.
Whereas the most common digraphs are ranked :- te,er,on,an,re,he,in,ed,nd,ha,at,en,es,of,or,nt,ea,ti,to,it, st,io,le,is,ou,ar,as,de,rt,ve.
The most common three-letter words rank in this order :- the,and,for,are,but,not,you,all,any,can,had,her,was,one, our,out,day,get,has, him,his,how,man,new,new,old,see,two,way,who,boy,did,its, let,put,say,she,too,use.
Whereas the most common trigraphs are ranked :- the,and,tha,ent,ion,tio,for,nde,has,nce,edt,tis,oft,sth,men.
Finally, the most frequent four letter words are ranked like this :- that,with,have,this,will,your,from,they,know,want,been, good,much,some,time,very,when, come,here,just,like,long,make,many,more,only,over,such, take,than,them,well,were.
Of coarse (sic!) if - instead of written English - you listen to modern spoken American, the 4 letter words would rank :- fuck, shit, Bush and other stupid obscenities ;-)
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Friday, September 4, 2009
Cornering as if on railsust the other day, I was watching a repeat episode of Top Gear (a Brit TV program for sports car drivers), when the presenter said of one of the sports cars "It goes around corners as if it were on rails!".
My brain went offline, sidetracked by the thought "How DO trains go around curves?"
After all, they don't have a differential on the axle as a car or truck does.
They have straight-through one-piece axles. So just how DO trains go around bends at all?
Look at my sketch on the left, which shows a cross-section through a 1-piece axle, wheels and rails. There are flanges on the insides of the wheels, but these are just there for safety reasons to stop the wheels sliding off the rails in corners.
Note that the running surfaces of the wheels have a conic cross-section.
Now when the train goes around a left curve, as shown in my sketch on the right, centrifugal force pushes the train over to the right a little, as shown above right. As a result, the right wheel runs on the inside next to the flange, which is higher up (radius R2 in my sketch) the conic section of the right wheel. Conversely, the left wheel runs on the outside away from the flange, and thus is lower down (radius R1 in my sketch) on the conic section of the left wheel. Since R2 is larger than R1 and we have a stiff one-piece axle, the axle/wheel assembly turns left. And vice versa of course. The safety flange stops the wheel running off the edge of the conical section, as shown.
For high-speed trains, the outside rail may be slightly higher than the inside rail too, in order to improve passenger comfort (less lateral forces).
In fact, when the train is running 'straight' any perturbations will cause the axle to oscillate so the train's direction is self-correcting, running as if on rails :-)
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Tuesday, September 1, 2009
Devine algebraic limerick :-)ost people don't think algebra is poetic, nor is poetry mathematical. But in her book Absolute Zero Gravity: Science Jokes, Quotes and Anecdotes (ISBN: 0671740601), Devine and Cohen, Prentice-Hall, 1992, blogger Betsy Devine gives us a beautiful example. It is so devine, I've videoed me quoting it ;-)
Or, to put it as a limerick, here's my caveat :-
This limerick of logs and cosine
Is no invention of mine
I merely recite.
The algebra - right -
Was written by Betsy Devine ;-)
Comments (5) :
Great comment limerick, Peter :-) In mime? You mean like Karaoke for the deaf ? ;-)
Carla chimes in with this ditty :-
Matthew points us to a hilarious song for mathematicians ;-)
English student Roz has us stumbling with this gem, English as she is writ vs. spake
"We poets think maths is quite tough
Stu sez : Roz, your rhyming's so freak, I need a break ;-)
Charles re-rhymes Roz's limerick :- "If you change the dough and bough so they rhyme with tough (i.e. Duff & buff, Duff is the beer that Homer Simpson drinks), and likewise beard to rhyme with heard (i.e. bird), you get a completely different picture." Yes. I'm sure the author (Roz) intended that; that's what makes it doubly funny :-)
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