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Technik+Digitales

Laserstrahlen für guten Grip

Der Reifenhersteller Continental hat ein neues, auf Laserstrahlen basierendes Verfahren zur Qualitätskontrolle von Autoreifen entwickelt. Dabei wird der Reifen in Windeseile von drei Laserstrahlen abgetastet. Ein Computerprogramm kann dann durch Analyse der reflektierten Strahlen eventuell bei der Produktion aufgetretene Fehlstellen aufspüren.

Das in Zusammenarbeit mit Ingenieuren aus Bratislava entwickelte Verfahren beruht auf drei Lasern, die den auf einer Achse befestigten Reifen von allen drei Seiten aus einer Entfernung von etwa 25 Zentimetern beleuchten (siehe Bild). Die Reflexionen der Strahlen werden von drei digitalen Kameras aufgefangen und mittels eines Computerprogramms zu einem Bild verarbeitet. Das Programm untersucht dann die digitalisierten Reifenabdrücke auf Fehlstellen.

Obwohl Einzelheiten des Verfahrens aus patentrechtlichen Gründen nicht bekannt sind, beruht es wohl auf den aus der Seefahrt bekannten Techniken der Triangulation. Dies ermöglicht die Herstellung eines dreidimensionalen Digitalbilds. Da das Computerprogramm Informationen in Echtzeit verarbeitet, kann ein gesamter Reifen innerhalb von nur etwa einer Sekunde unter den Strahlen um 360 Grad rotiert und somit vollständig untersucht werden.

Nachrichtendienst Optics.org Stefan Maier
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Phy|sik|un|ter|richt  〈m. 1; Pl. selten〉 (schulischer) Unterricht im Fach Physik

The Zodiac Killer murdered five or more people and sent four encrypted messages to newspapers. The case and three of the cryptograms have never been solved.

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The Zodiac Killer was a serial killer who operated in the San Francisco area in the late sixties. He was never caught. He killed at least five people and seriously injured two.

Source: Wikimedia

 

The Zodiac Killer

There are four confirmed crimes the Zodiac Killer committed:

  • Dezember 20, 1968: The Zodiac Killer murders 16-year-old Betty Lou Jensen and her 17-year-old boyfriend David Faraday in Vallejo, north of San Francisco.
  • July 4, 1969: The Zodiac Killer kills 22-year-old waitress Darlene Ferrin in a parking lot in Benicia. Her 19-year-old companion Michael Mageau survives badly injured.
  • September 27, 1969: In a park near Lake Berryessa, a man dressed in black kills 22-year-old Cecelia Shepard and seriously injures her 20-year-old boyfriend Bryan Hartnell (see picture below).
  • October 11, 1969: The Zodiac Killer shoots Taxi driver Paul Stine in his taxi.

It is well possible that the Zodiac Killer committed even more crimes. There are several unsolved murders and murder attempts where at least it is not excluded that the Zodiac Killer had something to do with it.

NSA-Symposium-03-Zodiac

Source: Schmeh

The Zodiac Killer wrote dozens of letters to regional newspapers and other recipients. In these notes he repeatedly made fun of the police and boasted of his deeds. Four of his letters contained encrypted messages. Three of them are unsolved to date.

 

Message #1 (Z408)

The first Zodiac cryptogram was received in three parts by three different regional newspapers in San Francisco on August 1, 1969. It is referred to as Z408 because it contains 408 letters.

Zodiac-1

Source: Wikimedia

Z408 is the only Zodiac cryptogram that was solved (in the picture above the plaintext is written above the ciphertext). The solution was found by a teacher couple who had learned about the encrypted message in the newspaper. Unfortunately this deciphering success did not help the police. The plaintext is reproduced in the following.

I LIKE KILLING PEOPLE BECAUSE IT IS SO MUCH FUN IT IS MORE FUN THAN KILLING WILD GAME IN THE FORREST BECAUSE MAN IS THE MOST DANGEROUE ANAMAL OF ALL TO KILL SOMETHING GIVES ME THE MOST THRILLING EXPERENCE IT IS EVEN BETTER THAN GETTING YOUR ROCKS OFF WITH A GIRL THE BEST PART OF IT IS THAE WHEN I DIE I WILL BE REBORN IN PARADICE AND THEI HAVE KILLED WILL BECOME MY SLAVES I WILL NOT GIVE YOU MY NAME BECAUSE YOU WILL TRY TO SLOI DOWN OR ATOP MY COLLECTIOG OF SLAVES FOR MY AFTERLIFE EBEORIETEMETHHPITI

In the following video made by blog reader Nils Kopal the solution of Z408 is explained in detail:

 

Message #2 (Z340)

The second Zodiac cryptogram (Z340) was received on November 8, 1969.

Zodiac-340

Source: Wikimedia

This cryptogram comprises 340 characters and thus offers a relatively large amount of analysis material. Anyway, it is unsolved to date.

Considering that the first Zodiac message (Z408) proved to be encrypted in a homophonic cipher (i.e., a plaintext letter may have several ciphertext counterparts), it seems reasonable to assume that Z340, which looks similar, was created with the same kind of encryption. However, all attempts to find a homophonic substitution table that decrypts Z340 have failed so far. Apparently, the Zodiac Killer, after his first cryptogram had been broken within a short time, tried to make his second try more difficult. It is, of course, also possible that Z340 is a hoax.

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