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Aircraft Rudder
A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane. A rudder operates by redirecting the fluid past the hull or fuselage, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with hinges to the craft's stern, tail, or after end. Often rudders are shaped so as to minimize hydrodynamic or aerodynamic drag. On simple watercraft, a tiller—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be turned by a helmsman. In larger vessels, cables, pushrods, or hydraulics may be used to link rudders to steering wheels. In typical aircraft, the rudder is operated by pedals via mechanical linkages or hydr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerodynamic Drag
In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers (or surfaces) or between a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, the drag force depends on velocity. Drag force is proportional to the velocity for low-speed flow and the squared velocity for high speed flow, where the distinction between low and high speed is measured by the Reynolds number. Even though the ultimate cause of drag is viscous friction, turbulent drag is independent of viscosity. Drag forces always tend to decrease fluid velocity relative to the solid object in the fluid's path. Examples Examples of drag include the component of the net aerodynamic or hydrodynamic force acting opposite to the di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phoenicia
Phoenicia () was an ancient thalassocratic civilization originating in the Levant region of the eastern Mediterranean, primarily located in modern Lebanon. The territory of the Phoenician city-states extended and shrank throughout their history, and they possessed several enclaves such as Arwad and Tell Sukas (modern Syria). The core region in which the Phoenician culture developed and thrived stretched from Tripoli and Byblos in northern Lebanon to Mount Carmel in modern Israel. At their height, the Phoenician possessions in the Eastern Mediterranean stretched from the Orontes River mouth to Ashkelon. Beyond its homeland, the Phoenician civilization extended to the Mediterranean from Cyprus to the Iberian Peninsula. The Phoenicians were a Semitic-speaking people of somewhat unknown origin who emerged in the Levant around 3000 BC. The term ''Phoenicia'' is an ancient Greek exonym that most likely described one of their most famous exports, a dye also known as Tyrian purpl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of China
The earliest known written records of the history of China date from as early as 1250 BC, from the Shang dynasty (c. 1600–1046 BC), during the reign of king Wu Ding. Ancient historical texts such as the '' Book of Documents'' (early chapters, 11th century BC), the '' Bamboo Annals'' (c. 296 BC) and the ''Records of the Grand Historian'' (c. 91 BC) describe a Xia dynasty before the Shang, but no writing is known from the period, and Shang writings do not indicate the existence of the Xia. The Shang ruled in the Yellow River valley, which is commonly held to be the cradle of Chinese civilization. However, Neolithic civilizations originated at various cultural centers along both the Yellow River and Yangtze River. These Yellow River and Yangtze civilizations arose millennia before the Shang. With thousands of years of continuous history, China is among the world's oldest civilizations and is regarded as one of the cradles of civilization. The Zhou dynasty (1046–256 BC) supp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Lefebvre Des Noëttes
Richard Lefebvre des Noëttes (1856–1936) was a French officer and early historian of technology. After his early retirement from the French army in 1901, Lefebvre devoted his time to technological studies, then quite a new field, becoming a main proponent of the negative impact of slavery on technological progress in classical antiquity. Although dissenting voices emerged as early as the 1930s, his primitivist views of ancient traction technology met with considerable success in the 1950s and 1960s when authorities like the medievalist Lynn White and the sinologist Joseph Needham, but also many classicists, relied rather uncritically on his research. Based on a thorough reexamination of the pictorial evidence, much of it not available in Lefebvre's time, as well as experimental archaeology, modern scholars like Georges Raepsaet have refuted Lefebvre's findings, particularly his glaring underestimation of the capacities of ancient horse-drawn ploughs and carriages. His depreciati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Needham
Noel Joseph Terence Montgomery Needham (; 9 December 1900 – 24 March 1995) was a British biochemist, historian of science and sinologist known for his scientific research and writing on the history of Chinese science and technology, initiating publication of the multivolume ''Science and Civilisation in China''. He was elected a fellow of the Royal Society in 1941 and a fellow of the British Academy in 1971. In 1992, Queen Elizabeth II conferred on him the Companionship of Honour, and the Royal Society noted he was the only living person to hold these three titles. Early life Needham's father, Joseph was a doctor, and his mother, Alicia Adelaïde, née Montgomery (1863–1945), was a music composer from Oldcastle, County Meath, Ireland. His father, born in East London, then a poor section of town, rose to became a Harley Street physician, but frequently battled with Needham's mother. The young Needham often mediated. In his early teens, he was taken to hear the Sun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxford Dictionary Of English Etymology
''The Oxford Dictionary of English Etymology'' is an etymological dictionary of the English language, published by Oxford University Press. The first editor of the dictionary was Charles Talbut Onions, who spent his last twenty years largely devoted to completing the first edition, published in 1966, which treated over 38,000 words and went to press just before his death. Editions * C. T. Onions, ed.; edited by C. T. Onions with the assistance of G. W. S. Friedrichsen and R. W. Burchfield (1966, reprinted 1983, 1992, 1994) Also published by OUP: *''The Concise Oxford Dictionary of English language'' **T. F. Hoad (1986) **T. F. Hoad (1993) *''An Etymological Dictionary of the English Language'' ** W. W. Skeat (1910; reprint 1963; now in the public domain) See also * ''Oxford English Dictionary'' *Onions (ed.) - The Oxford Dictionary of English Etymology (1966) : Allan R. Bomhard : Free Download, Borrow, and Streaming : Internet Archive References 1966 non-fiction books ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopædia Britannica
The (Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various times through the centuries. The encyclopaedia is maintained by about 100 full-time editors and more than 4,000 contributors. The 2010 version of the 15th edition, which spans 32 volumes and 32,640 pages, was the last printed edition. Since 2016, it has been published exclusively as an online encyclopaedia. Printed for 244 years, the ''Britannica'' was the longest running in-print encyclopaedia in the English language. It was first published between 1768 and 1771 in the Scottish capital of Edinburgh, as three volumes. The encyclopaedia grew in size: the second edition was 10 volumes, and by its fourth edition (1801–1810) it had expanded to 20 volumes. Its rising stature as a scholarly work helped recruit eminent con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mediterranean
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the east by the Levant. The Sea has played a central role in the history of Western civilization. Geological evidence indicates that around 5.9 million years ago, the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years during the Messinian salinity crisis before being refilled by the Zanclean flood about 5.3 million years ago. The Mediterranean Sea covers an area of about , representing 0.7% of the global ocean surface, but its connection to the Atlantic via the Strait of Gibraltar—the narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates the Iberian Peninsula in Europe from Morocco in Africa—is only wide. The Mediterranean Sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steering Oar
The steering oar or steering board is an over-sized oar or board, to control the direction of a ship or other watercraft prior to the invention of the rudder. It is normally attached to the starboard side in larger vessels, though in smaller ones it is rarely, if ever, attached. The steering oar was crucial in the invention of larger vessels in a time when the technology for rudders did not exist. Steering oars were the typical steering mechanism on larger Viking ship Viking ships were marine vessels of unique structure, used in Scandinavia from the Viking Age throughout the Middle Ages. The boat-types were quite varied, depending on what the ship was intended for, but they were generally characterized as bein ...s. References Sailboat components Sailing ship components {{Water-transport-stub, date=June 2018 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopædia Britannica 2006 Ultimate Reference Suite DVD
An encyclopedia (American English) or encyclopædia (British English) is a reference work or compendium providing summaries of knowledge either general or special to a particular field or discipline. Encyclopedias are divided into articles or entries that are arranged alphabetically by article name or by thematic categories, or else are hyperlinked and searchable. Encyclopedia entries are longer and more detailed than those in most dictionaries. Generally speaking, encyclopedia articles focus on '' factual information'' concerning the subject named in the article's title; this is unlike dictionary entries, which focus on linguistic information about words, such as their etymology, meaning, pronunciation, use, and grammatical forms.Béjoint, Henri (2000)''Modern Lexicography'', pp. 30–31. Oxford University Press. Encyclopedias have existed for around 2,000 years and have evolved considerably during that time as regards language (written in a major international or a verna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
