Sonar is a machine that uses underwater sound waves to find other objects in the sea. A sonar can work by sending out sound and listening for echoes (active sonar), like a radar, or by listening for sound made by the object it is trying to find (passive sonar).
The basic parts of an active sonar are:
The first use of passive sonar was in 1490 by Leonardo da Vinci, when he put a tube onto water and listened. Active sonar was first used in 1917 by Paul Langevin. The word "SONAR" was created during the Second World War as an acronym for Sound Navigation and Ranging. This acronym replaced the British acronym ASDIC. The word is now thought by many people as a regular word, no longer as an acronym.
Rococo
Rococo is an artistic style which originated in the 18th century in France. Often referred to merely as Late Baroque, the Rococo developed from the Baroque artistic movement. Whilst it kept several characteristics of the original style, including elaboration and ornate themes, it was also more playful and asymmetrical. The Rococo is associated with the reign of French king Louis XV (Louis XIV is associated with the Baroque, whilst Louis XVI with Neoclassicism, albeit his style started off as Rococo at the beginning of reign). Rococo's popularity was at its height towards the middle of the 18th century, fading out by the end in favour of Neoclassicism.
Rococo art and architecture was feminine, graceful, florid and ornate. Creamy and pastel-like colours were used for paintings, unlike the darker shades in Baroque art. Religion and politics were no longer necessarily the core theme of Rococo art, unlike the Baroque, and everyday life became more commonly represented. In such a way, Rococo art revolved around themes such as love, romance, fun, landscapes, and mere portraits. Additionally, Far Eastern themes became popular in Rococo, especially Chinoiserie. Famous Rococo artists include Boucher, Watteau and Fragonard, amongst several others.
The Rococo has been the focus of much discussion, analysis and criticism by art historians throughout history. It has been criticised over the years for being over-the-top, superficial and frivolous; in such a way, the term has even been used derogatively in various points of history. Nevertheless, Rococo art and theatre has also received praise for the elegance, "beauty", and "charm" of its artwork.
Azerbaijani food
Azerbaijani food is what people cook and eat in Azerbaijan. Foods from different cultures have influenced Azerbaijani food. However, it remained different from foods in other countries. Many foods that started in Azerbaijan are now part of other cultures. For the Azerbaijanis, food is an important part of the country's culture and is very connected with the history, traditions and values of the nation.
Out of 11 climate types in the world, Azerbaijan has nine. This adds to the fertility of the soil, so there are many kinds of vegetables used according to seasons and the dishes. The climate helps to create the richness of the food. Fresh herbs, including mint, coriander, dill, basil, parsley, tarragon, leek, chive, thyme, marjoram, green onion and watercress, are very popular and are often put in the main dishes. The Caspian Sea has many edible species of fish, including the sturgeon, Caspian salmon, kutum, sardines, grey mullet, and others. Black caviar from the Caspian Sea is one of Azerbaijan’s best known delicacies wanted in many parts of the world.
The main courses of Azerbaijani cuisine are over 30 kinds of soups, including those prepared from plain yogurt. One of the most famous dishes is plov. Plov is a saffron-covered rice, served with different herbs. The Azerbaijani cuisine has more than 40 different plov recipes. Other second courses include many kinds of kebabs and shashliks, including lamb, beef, chicken, and fish ("baliq") kebabs. Sturgeon, a common fish, is normally skewered (skewer is a thin metal or wood stick used to hold pieces of food together) and grilled as a shashlik, being served with a tart pomegranate sauce called "narsharab". Dried fruits and walnuts are used in many dishes. The traditional condiments are salt, the spices black pepper, sumac, and especially saffron. Much of the saffron comes from the Absheron Peninsula.
Black tea is the national drink, and is drunk after food is eaten. It is also popular on its own or with dried fruits.
Another popular drink is sherbet, a sweet cold drink made of fruit juice mixed or boiled with sugar, often perfumed with rose water. Azerbaijani sherbet is not sorbet, the cold dessert.
Genji
The "nengō" "Genji" means "original rule".
Kde domov můj?
"Kde domov můj" ( [ɡdɛ ˈdomof muːj] ) is the national anthem of the Czech Republic. It—combined with the lyrics of "Nad Tatrou sa blýska"—was used as the anthem of Czechoslovakia, and after Czechoslovakia splitted into Czechia and Slovakia, "Kde domov můj" became the anthem of the former (Czechia, the short-form name for the Czech Republic). It was created by Josef Kajetán Tyl and František Škroup in 1834 and was first published in the play "Fidlovačka aneb žádný hněv a žádná rvačka".
The lyrics were written by Fidlovačka in 1834. Only the first verse is used as the anthem.
See also "Nad Tatrou sa blýska".
This version was translated into English by Czech poet Václav Sládek (1845–1912).
Between 1918 and 1938 there was an official version in German by Karl Wenzel Ernst.
Between the same years there was an official version in Hungarian.
Synchrotron
A synchrotron is a type of particle accelerator where particles travel around many times in a circle. It uses a magnetic field to turn the particles in the circle and an electric field to speed up the particles. The components are carefully matched up with the travelling particle beam so that the circle stays the same size while the particles go faster. Mark Oliphant invented the proton synchrotron. Vladimir Veksler was the first to publish the idea. Edwin McMillan constructed the first electron synchrotron.
The synchrotron is an improvement over the cyclotron where the particles travel in a spiral pattern. A cyclotron uses a constant magnetic field and a constant-frequency applied electric field. (One of these is varied in the synchrocyclotron). Both of these fields are varied in the synchrotron to change the path from a spiral to a circle. By carefully making the fields bigger as the particles gain energy, the width of the circular path can be kept the same as the machine accelerates the particles. This allows the vacuum chamber for the particles to be a large thin circular pipe torus (donut shape). It is easier to use some straight sections between the bending magnets and some bent sections within the magnets giving the torus the shape of a round-cornered polygon. A path that acts like a very large circle can be constructed using simple straight and curved pipe segments, unlike the disc-shaped chamber of the cyclotron type devices. The shape also requires the use of multiple magnets to bend the particle beams. Straight sections are required at spacings around a ring for both radiofrequency cavities, and in third generation setups space is allowed for insertion of energy extraction devices such as wigglers and undulators. Most synchrotrons use two types of magnets: dipole magnets to bend the particle beam and quadrupole magnets to focus the beam.
The maximum energy that a cyclic accelerator can impart is typically limited by the strength of the magnetic field(s) and the minimum radius (maximum curvature) of the particle path. So, over time, physicist have built accelerators with bigger magnets and larger circles to reach higher particle energy levels.