The Hellenic Navy (HN) (Greek: Πολεμικό Ναυτικό, Polemikó Naftikó, abbreviated ΠΝ) is the naval force of Greece, part of the Greek Armed Forces. The modern Greek navy has its roots in the naval forces of various Aegean Islands, which fought in the Greek War of Independence. During the periods of monarchy (1833–1924 and 1936–1973) it was known as the Royal Navy (Βασιλικόν Ναυτικόν, Vasilikón Naftikón, abbreviated ΒΝ).The total displacement of all the navy's vessels is approximately 150,000 tons.The motto of the Hellenic Navy is "Μέγα το της Θαλάσσης Κράτος" from Thucydides' account of Pericles' oration on the eve of the Peloponnesian War. This has been roughly translated as "Great is the country that controls the sea". The Hellenic Navy's emblem consists of an anchor in front of a crossed Christian cross and trident, with the cross symbolizing Greek Orthodoxy, and the trident symbolizing Poseidon, the god of the sea in Greek mythology. Pericles' words are written across the top of the emblem. "The navy, as it represents a necessary weapon for Greece, should only be created for war and aim to victory."...............The Hellenic Merchant Marine refers to the Merchant Marine of Greece, engaged in commerce and transportation of goods and services universally. It consists of the merchant vessels owned by Greek civilians, flying either the Greek flag or a flag of convenience. Greece is a maritime nation by tradition, as shipping is arguably the oldest form of occupation of the Greeks and a key element of Greek economic activity since the ancient times. Nowadays, Greece has the largest merchant fleet in the world, which is the second largest contributor to the national economy after tourism and forms the backbone of world shipping. The Greek fleet flies a variety of flags, however some Greek shipowners gradually return to Greece following the changes to the legislative framework governing their operations and the improvement of infrastructure.Blogger Tips and Tricks
This is a bilingual blog in English and / or Greek and you can translate any post to any language by pressing on the appropriate flag....Note that there is provided below a scrolling text with the 30 recent posts...Αυτό είναι ένα δίγλωσσο blog στα Αγγλικά η/και στα Ελληνικά και μπορείτε να μεταφράσετε οποιοδήποτε ποστ σε οποιαδήποτε γλώσσα κάνοντας κλικ στη σχετική σημαία. Σημειωτέον ότι παρακάτω παρέχεται και ένα κινούμενο κείμενο με τα 30 πρόσφατα ποστς....This is a bilingual blog in English and / or Greek and you can translate any post to any language by pressing on the appropriate flag....Note that there is provided below a scrolling text with the 30 recent posts...Αυτό είναι ένα δίγλωσσο blog στα Αγγλικά η/και στα Ελληνικά και μπορείτε να μεταφράσετε οποιοδήποτε ποστ σε οποιαδήποτε γλώσσα κάνοντας κλικ στη σχετική σημαία. Σημειωτέον ότι παρακάτω παρέχεται και ένα κινούμενο κείμενο με τα 30 πρόσφατα ποστς.........

Thursday, March 25, 2010

NASA Image of the Day, March 25th..[ 799 ]


The latest NASA "Image of the Day" image.

Learning Can Be a 'Drag'
When Ajay Ramesh and Prithvi Aiyaswamy, two seventh graders from Chaboya Middle School, San Jose, Calif., visited the Fluid Mechanics Laboratory at NASA Ames Research Center they found that the principles of fluid mechanics are not such a 'drag' after all.

The two youngsters both showed up for their experiment with a half dozen toy cars they found at home. "Our project is to find the best design shape that has the least amount of drag," said Aiyaswamy. "As we began the experiment, we realized that cars with a sloping shape perform better."

The orange liquid behind the car illustrates the wake, which can be used to determine drag for the car. The green lines across illustrate the air moving across the car. The boys were fortunate to request their visit when the Fluid Mechanics Laboratory was uniquely set up to accommodate their request. Kurtis Long, test engineer at the Fluid Mechanics Lab received permission for the boys to visit and donated his lunch hour to help the boys perform their test.

The boys placed the cars in a pool of water. Dye was added to the water and photos were taken of the dye flowing around the toy cars. "Air and water have the same flow characteristics, but by using water we can slow down time and see the flow more clearly," explained Long.

With these photos, the boys could measure the drag of each car. The orange liquid behind the car illustrates the wake, which can be used to determine the car's drag. The green lines across illustrate air moving across the car. Image Credit: NASA/Eric James


Πέμπτη, 25 Μάρτιος 2010 6:00:00 πμ

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