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Acoustic Shadow
An acoustic shadow or sound shadow is an area through which sound waves fail to propagate, due to topographical obstructions or disruption of the waves via phenomena such as wind currents, buildings, or sound barriers. Short-distance acoustic shadow A short-distance acoustic shadow occurs behind a building or a sound barrier. The sound from a source is shielded by the obstruction. Due to diffraction around the object, it will not be completely silent in the sound shadow. The amplitude of the sound can be reduced considerably, however, depending on the additional distance the sound has to travel between source and receiver. Long-distance acoustic shadow Anomalous sound propagation in the atmosphere can occur in certain conditions of wind, temperature and pressure. Such conditions enable sound to travel in refraction channels over long distances until returning to the earth's surface, and it thus may not be heard in intervening locations. As one website refers to it, "an acoustic sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Topography
Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary science and is concerned with local detail in general, including not only relief, but also natural, artificial, and cultural features such as roads, land boundaries, and buildings. In the United States, topography often means specifically ''relief'', even though the USGS topographic maps record not just elevation contours, but also roads, populated places, structures, land boundaries, and so on. Topography in a narrow sense involves the recording of relief or terrain, the three-dimensional quality of the surface, and the identification of specific landforms; this is also known as geomorphometry. In modern usage, this involves generation of elevation data in digital form ( DEM). It is often considered to include the graphic representat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Civil War (TV Series)
''The Civil War'' is a 1990 American television documentary miniseries created by Ken Burns about the American Civil War. It was the first broadcast to air on PBS for five consecutive nights, from September 23 to 27, 1990. More than 39 million viewers tuned in to at least one episode, and viewership averaged more than 14 million viewers each evening, making it the most-watched program ever to air on PBS. It was awarded more than 40 major television and film honors. A companion book to the documentary was released shortly after the series aired. Its filmography was groundbreaking for the time, and spawned film techniques such as the Ken Burns effect. Its theme song, " Ashokan Farewell" is widely acclaimed. The series was extremely influential, and serves as the main source of knowledge about the Civil War to many Americans. However, some historians have criticized its historical accuracy, especially its lack of coverage of slavery as a cause of the war. The series was rebroadca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hearing
Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is auditory science. Sound may be heard through solid, liquid, or gaseous matter. It is one of the traditional five senses. Partial or total inability to hear is called hearing loss. In humans and other vertebrates, hearing is performed primarily by the auditory system: mechanical waves, known as vibrations, are detected by the ear and transduced into nerve impulses that are perceived by the brain (primarily in the temporal lobe). Like touch, audition requires sensitivity to the movement of molecules in the world outside the organism. Both hearing and touch are types of mechanosensation. Hearing mechanism There are three main components of the human auditory system: the outer ear, the middle ear, and the inner ear. Outer ear The ou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gobo (recording)
Gobo is a sound recording term for a movable acoustic isolation panel. In typical use, a recording engineer might put a gobo between two musicians to increase the isolation of their microphones from each other. The origin of the term "gobo" is obscure, but is most likely short for "go-between". Use Gobo panels control the acoustical properties of a room by absorbing and diffusing sound waves. Uses include treating recording and mixing areas for unwanted reverberation Reverberation (also known as reverb), in acoustics, is a persistence of sound, after a sound is produced. Reverberation is created when a sound or signal is reflected causing numerous reflections to build up and then decay as the sound is abso ..., or to separate two or more musicians so they can play close to each other with separate microphones. Gobo panels are typically constructed to accommodate portability and storage, an advantage over more permanent acoustical room treatments. Construction A gobo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deal, Kent
Deal is a coastal town in Kent, England, which lies where the North Sea and the English Channel meet, north-east of Dover and south of Ramsgate. It is a former fishing, mining and garrison town whose history is closely linked to the anchorage in the Downs. Close to Deal is Walmer, a possible location for Julius Caesar's first arrival in Britain. Deal became a 'limb port' of the Cinque Ports in 1278 and grew into the busiest port in England; today it is a seaside resort, its quaint streets and houses a reminder of its history along with many ancient buildings and monuments. In 1968, Middle Street was the first conservation area in Kent. The coast of France is approximately from the town and is visible on clear days. The Tudor-era Deal Castle, commissioned by then- King, Henry VIII, has a rose floor plan. History Deal is first mentioned as a village in the Domesday Book of 1086, where it appears as ''Addelam''. It is referred to as ''Dela'' in 1158, and ''Dale'' i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sayes Court
Sayes Court was a manor house and garden in Deptford, in the London Borough of Lewisham on the Thames Path and in the former parish of St Nicholas. Sayes Court once attracted throngs to visit its celebrated garden'' Diary and Correspondence of John Evelyn'' created by the seventeenth century diarist John Evelyn. Now completely buried beneath Convoys Wharf and Sayes Court Park, the area shows little sign of its former glory, despite having been a key factor in the creation of the National Trust. History Earliest information The Manor of Deptford was bestowed upon Gilbert de Magminot or Maminot by William the Conqueror and this is where he held the head of the barony of Maminot. In 1814 John Lyon wrote that Maminot built a castle, or castellated mansion, for himself at Deptford. Lyon noted that all traces had by then long since been buried in their ruins, but from the remains of some ancient foundations which had been discovered, the site was probably on the brow of Broomf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Four Days' Battle
The Four Days' Battle, also known as the Four Days' Fight in some English sources and as Vierdaagse Zeeslag in Dutch, was a naval battle of the Second Anglo-Dutch War. Fought from 1 June to 4 June 1666 in the Julian or Old Style calendar that was then used in England, in the southern North Sea, it began off the Flemish coast and ended near the English coast. It remains one of the longest naval engagements in history. Dutch accounts referred to its dates as 11 June to 14 June 1666 by using the New Style calendar. The Dutch inflicted significant damage on the English fleet, which lost ten ships in total, with over 1,000 men killed, including two vice-admirals, Sir Christopher Myngs and Sir William Berkeley, and almost 2,000 English were taken prisoner including a third vice-admiral, George Ayscue. Dutch losses were four ships destroyed by fire and over 1,550 men killed, including Lieutenant Admiral Cornelis Evertsen, Vice Admiral Abraham van der Hulst and Rear Admiral Frederik ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samuel Pepys
Samuel Pepys (; 23 February 1633 – 26 May 1703) was an English diarist and naval administrator. He served as administrator of the Royal Navy and Member of Parliament and is most famous for the diary he kept for a decade. Pepys had no maritime experience, but he rose to be the Chief Secretary to the Admiralty under both King Charles II and King James II through patronage, diligence, and his talent for administration. His influence and reforms at the Admiralty were important in the early professionalisation of the Royal Navy. The detailed private diary that Pepys kept from 1660 until 1669 was first published in the 19th century and is one of the most important primary sources for the English Restoration period. It provides a combination of personal revelation and eyewitness accounts of great events, such as the Great Plague of London, the Second Dutch War, and the Great Fire of London. Early life Pepys was born in Salisbury Court, Fleet Street, London, on 23 Feb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Evelyn
John Evelyn (31 October 162027 February 1706) was an English writer, landowner, gardener, courtier and minor government official, who is now best known as a diarist. He was a founding Fellow of the Royal Society. John Evelyn's diary, or memoir, spanned the period of his adult life from 1640, when he was a student, to 1706, the year he died. He did not write daily at all times. The many volumes provide insight into life and events at a time before regular magazines or newspapers were published, making diaries of greater interest to modern historians than such works might have been at later periods. Evelyn's work covers art, culture and politics, including the execution of Charles I, Oliver Cromwell's rise and eventual natural death, the last Great Plague of London, and the Great Fire of London in 1666. '' John Evelyn's Diary'' was first published posthumously in 1818, but over the years was overshadowed by that of Samuel Pepys. Pepys wrote a different kind of diary, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ken Burns
Kenneth Lauren Burns (born July 29, 1953) is an American filmmaker known for his documentary film, documentary films and television series, many of which chronicle United States, American History of the United States, history and Culture of the United States, culture. His work is often produced in association with WETA-TV and/or the National Endowment for the Humanities and distributed by PBS. His widely known documentary series include ''The Civil War (miniseries), The Civil War'' (1990), ''Baseball (TV series), Baseball'' (1994), ''Jazz (TV series), Jazz'' (2001), ''The War (miniseries), The War'' (2007), ''The National Parks: America's Best Idea'' (2009), ''Prohibition (miniseries), Prohibition'' (2011), ''The Roosevelts (miniseries), The Roosevelts'' (2014), ''The Vietnam War (TV series), The Vietnam War'' (2017), and ''Country Music (miniseries), Country Music'' (2019). He was also executive producer of both ''The West (miniseries), The West'' (1996), and ''Cancer (film), C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultrasonography Of Sludge And Gallstones, Annotated
Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies from person to person and is approximately 20 kilohertz (20,000 hertz) in healthy young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz. Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances. Ultrasound imaging or sonography is often used in medicine. In the nondestructive testing of products and structures, ultrasound is used to detect invisible flaws. Industrially, ultrasound is used for cleaning, mixing, and accelerating chemical processes. Animals such as bats and porpoises use ultrasound for locating prey and obstacles. History Acoustics, the science of sound, starts as far back as Pythagoras in the 6th century BC, who wrote on t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Battle Of Five Forks
The Battle of Five Forks was fought on April 1, 1865, southwest of Petersburg, Virginia, around the road junction of Five Forks, Dinwiddie County, at the end of the Siege of Petersburg, near the conclusion of the American Civil War. The Union Army commanded by Major General Philip Sheridan defeated a Confederate force from the Army of Northern Virginia commanded by Major General George Pickett. The Union force inflicted over 1,000 casualties on the Confederates and took up to 4,000 prisonersSome historians, such as Noah Andre Trudeau cited later, favor the lower Confederate casualty count of about 605 and lower prisoner count of about 2,400. while seizing Five Forks, the key to control of the South Side Railroad, a vital supply line and evacuation route. After the Battle of Dinwiddie Court House (March 31) at about 10:00 pm, V Corps infantry began to arrive near the battlefield to reinforce Sheridan's cavalry. Pickett's orders from his commander General Robert E. Lee were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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