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Flag of Denmark | Flag of Denmark | The national flag of Denmark (Danish: Dannebrog, pronounced [ˈtænəˌpʁoˀ]) is red with a white Nordic cross, which means that the cross extends to the edges of the flag and the vertical part of the cross is shifted to the hoist side. |
Flag of Denmark | Flag of Denmark | A banner with a white-on-red cross is attested as having been used by the kings of Denmark since the 14th century. An origin legend with considerable impact on Danish national historiography connects the introduction of the flag to the Battle of Lindanise of 1219. The elongated Nordic cross, which represents Christianity, reflects its use as a maritime flag in the 18th century. The flag became popular as a national flag in the early 16th century. Its private use was outlawed in 1834 but again permitted by a regulation of 1854. The flag holds the world record of being the oldest continuously used national flag. |
Flag of Denmark | Description | In 1748, a regulation defined the correct lengths of the two last fields in the flag as 6⁄4.
In May 1893 a new regulation to all chiefs of police stated that the police should not intervene, if the two last fields in the flag were longer than 6⁄4 as long as these did not exceed 7⁄4, and provided that this was the only rule violated.
This regulation is still in effect today and thus the legal proportions of the National flag today are 3:1:3 in width and anywhere between 3:1:4.5 and 3:1:5.25 in length.
No official definition of "Dannebrog rød" exists. The private company Dansk Standard, regulation number 359 (2005), defines the red colour of the flag as Pantone 186c. |
Flag of Denmark | History | 1219 origin legend A tradition recorded in the 16th century traces the origin of the flag to the campaigns of Valdemar II of Denmark (r. 1202–1241). The oldest of them is in Christiern Pedersen's "Danske Krønike", which is a sequel to Saxo's Gesta Danorum, written 1520–23. Here, the flag falls from the sky during one of Valdemar's military campaigns overseas. Pedersen also states that the very same flag was taken into exile by Eric of Pomerania in 1440. |
Flag of Denmark | History | The second source is the writing of the Franciscan friar Petrus Olai (Peder Olsen) of Roskilde (died c. 1570). This record describes a battle in 1208 near Fellin during the Estonia campaign of King Valdemar II. The Danes were all but defeated when a lamb-skin banner depicting a white cross fell from the sky and miraculously led to a Danish victory. In a third account, also by Petrus Olai, in Danmarks Tolv Herligheder ("Twelve Splendours of Denmark"), in splendour number nine, the same story is re-told almost verbatim, with a paragraph inserted correcting the year to 1219. Now, the flag is falling from the sky in the Battle of Lindanise, also known as the Battle of Valdemar (Danish: Volmerslaget), near Lindanise (Tallinn) in Estonia, of 15 June 1219. |
Flag of Denmark | History | It is this third account that has been the most influential, and some historians have treated it as the primary account taken from a (lost) source dating to the first half of the 15th century. |
Flag of Denmark | History | In Olai's account, the battle was going badly, and defeat seemed imminent. However the Danish Bishop Anders Sunesen, on top of a hill overlooking the battle, prayed to God with his arms raised, and the Danes moved closer to victory the more he prayed. When he raised his arms the Danes surged forward but when his arms grew tired and he let them fall, the Estonians turned the Danes back. Attendants rushed forward to raise his arms once again and the Danes again surged forward. But for a second time he grew so tired that he dropped his arms and the Danes again lost the advantage and were moving closer to defeat. He needed two soldiers to keep his hands up. When the Danes were about to lose, 'Dannebrog' miraculously fell from the sky and the King took it, showed it to the troops, their hearts were filled with courage, and the Danes won the battle. |
Flag of Denmark | History | The possible historical nucleus behind this origin legend was extensively discussed by Danish historians in the 19th to 20th centuries. One such example is Adolf Ditlev Jørgensen, who argued that Bishop Theoderich was the original instigator of the 1218 inquiry from Bishop Albert of Buxhoeveden to King Valdemar II which led to the Danish participation in the Baltic crusades. Jørgensen speculates that Bishop Theoderich might have carried the Knight Hospitaller's banner in the 1219 battle and that "the enemy thought this was the King's symbol and mistakenly stormed Bishop Theoderich tent. He claims that the origin of the legend of the falling flag comes from this confusion in the battle."The Danish church-historian L. P. Fabricius (1934) ascribes the origin to the 1208 Battle of Fellin, not the Battle of Lindanise in 1219, based on the earliest source available about the story. Fabricius speculated that it might have been Archbishop Andreas Sunesøn's personal ecclesiastical banner or perhaps even the flag of Archbishop Absalon, under whose initiative and supervision several smaller crusades had already been conducted in Estonia. The banner would then already be known in Estonia. Fabricius repeats Jørgensen's idea about the flag being planted in front of Bishop Theodorik's tent, which the enemy mistakenly attacked believing it to be the tent of the King. |
Flag of Denmark | History | A different theory is briefly discussed by Fabricius and elaborated more by Helge Bruhn (1949). Bruhn interprets the story in the context of the widespread tradition of the miraculous appearance of crosses in the sky in Christian legend, specifically comparing such an event attributed to a battle of 10 September 1217 near Alcazar, where it is said that a golden cross on white appeared in the sky, to bring victory to the Christians.In Swedish national historiography of the 18th century, there is a tale paralleling the Danish legend, in which a golden cross appears in the blue sky during a Swedish battle in Finland in 1157. |
Flag of Denmark | History | Middle Ages The white-on-red cross emblem originates in the age of the Crusades. In the 12th century, it was also used as war flag by the Holy Roman Empire. |
Flag of Denmark | History | In the Gelre Armorial, dated c. 1340–1370, such a banner is shown alongside the coat of arms of the king of Denmark. This is the earliest known undisputed colour rendering of the Dannebrog. At about the same time, Valdemar IV of Denmark displays a cross in his coat of arms on his Danælog seal (Rettertingsseglet, dated 1356). The image from the Armorial Gelre is nearly identical to an image found in a 15th-century coat of arms book now located in the National Archives of Sweden (Riksarkivet). The seal of Eric of Pomerania (1398) as king of the Kalmar union displays the arms of Denmark's chief dexter, three lions. In this version, the lions are holding a Dannebrog banner. |
Flag of Denmark | History | The reason why the kings of Denmark in the 14th century begin displaying the cross banner in their coats of arms is unknown. Caspar Paludan-Müller (1873) suggested that it may reflect a banner sent by the pope to support the Danish king during the Livonian Crusade. Adolf Ditlev Jørgensen (1875) identifies the banner as that of the Knights Hospitaller, which order had a presence in Denmark from the later 12th century.Several coins, seals, and images exist, both foreign and domestic, from the 13th to 15th centuries and even earlier, showing heraldic designs similar to Dannebrog, alongside the royal coat of arms (three blue lions on a golden shield.) There is a record suggesting that the Danish army had a "chief banner" (hoffuitbanner) in the early 16th century. Such a banner is mentioned in 1570 by Niels Hemmingsøn in the context of a 1520 battle between Danes and Swedes near Uppsala as nearly captured by the Swedes but saved by the heroic actions of the banner-carrier Mogens Gyldenstierne and Peder Skram. The legend attributing the miraculous origin of the flag to the campaigns of Valdemar II of Denmark (r. 1202–1241) was recorded by Christiern Pedersen and Petrus Olai in the 1520s. |
Flag of Denmark | History | Hans Svaning's History of King Hans from 1558 to 1559 and Johan Rantzau's History about the Last Dithmarschen War, from 1569, record the further fate of the Danish hoffuitbanner: According to this tradition, the original flag from the Battle of Lindanise was used in the small campaign of 1500 when King Hans tried to conquer Dithmarschen (in western Holstein in the north Germany). The flag was lost in a devastating defeat at the Battle of Hemmingstedt on 17 February 1500. In 1559, King Frederik II recaptured it during his own Dithmarschen campaign. |
Flag of Denmark | History | In 1576, the son of Johan Rantzau, Henrik Rantzau, also writes about the war and the fate of the flag, noting that the flag was in a poor condition when returned. He records that the flag after its return to Denmark was placed in the cathedral in Slesvig. Slesvig historian Ulrik Petersen (1656–1735) confirms the presence of such a banner in the cathedral in the early 17th century and records that it had crumbled away by about 1660. |
Flag of Denmark | History | Contemporary records describing the battle of Hemmingstedt make no reference to the loss of the original Dannebrog, although the capitulation state that all Danish banners lost in 1500 was to be returned. In a letter dated 22 February 1500 to Oluf Stigsøn, King John describes the battle but does not mention the loss of an important flag. In fact, the entire letter gives the impression that the lost battle was of limited importance. In 1598, Neocorus wrote that the banner captured in 1500 was brought to the church in Wöhrden and hung there for the next 59 years until it was returned to the Danes as part of the peace settlement in 1559. |
Flag of Denmark | History | Modern period Used as a maritime flag since the 16th century, the Dannebrog was introduced as a regimental flag in the Danish army in 1785, and for the militia (landeværn) in 1801. From 1842, it was used as the flag of the entire army.During the first half of the 19th century, in parallel to the development of Romantic nationalism in other European countries, the military flag increasingly came to be seen as representing the nation itself. Poems of this period invoking the Dannebrog were written by B.S. Ingemann, N.F.S. Grundtvig, Oehlenschläger, Chr. Winther and H.C. Andersen. By the 1830s, the military flag had become popular as an unofficial national flag, and its use by private citizens was outlawed in a circular enacted on 7 January 1834. |
Flag of Denmark | History | In the national enthusiasm sparked by the First Schleswig War during 1848–1850, the flag was still very widely displayed, and the prohibition of private use was repealed in a regulation of 7 July 1854, for the first time allowing Danish citizens to display the Dannebrog (but not the swallow-tailed Splitflag variant). Special permission to use the Splitflag was given to individual institutions and private companies, especially after 1870. In 1886, the war ministry introduced a regulation indicating that the flag should be flown from military buildings on thirteen specified days, including royal birthdays, the date of the signing of the Constitution of 5 June 1849 and on days of remembrance for military battles. In 1913, the naval ministry issued its own list of flag days. On 10 April 1915, the hoisting of any other flag on Danish soil was prohibited. From 1939 until 2012, the yearbook Hvem-Hvad-Hvor included a list of flag days. As of 2019 flag days can be viewed at the "Ministry of Justice (Justitsministeriet)" as well as "The Denmark Society (Danmarks-Samfundet)". |
Flag of Denmark | Variants | Maritime flag and corresponding Kingdom flag The size and shape of the civil ensign ("Koffardiflaget") for merchant ships is given in the regulation of 11 June 1748, which says: A red flag with a white cross with no split end. The white cross must be 1⁄7 of the flag's height. The two first fields must be square in form and the two outer fields must be 6⁄4 lengths of those. The proportions are thus: 3:1:3 vertically and 3:1:4.5 horizontally. This definition are the absolute proportions for the Danish national flag to this day, for both the civil version of the flag ("Stutflaget"), as well as the merchant flag ("Handelsflaget"). The civil flag and the merchant flag are identical in colour and design. |
Flag of Denmark | Variants | A regulation passed in 1758 required Danish ships sailing in the Mediterranean to carry the royal cypher in the center of the flag in order to distinguish them from Maltese ships, due to the similarity of the flag of the Sovereign Military Order of Malta. |
Flag of Denmark | Variants | According to the regulation of 11 June 1748 the colour was simply red, which is common known today as "Dannebrog rød" ("Dannebrog red"). The only available red fabric dye in 1748 was made of madder root, which can be processed to produce a brilliant red dye (used historically for British soldiers' jackets). A regulation of 4 May 1927 once again states that Danish merchant ships have to fly flags according to the regulation of 1748. |
Flag of Denmark | Variants | The first regulation regarding the Splitflag dates from 27 March 1630, in which King Christian IV orders that Norwegian Defensionskibe (armed merchants ships) may only use the Splitflag if they are in Danish war service. In 1685 an order, distributed to a number of cities in Slesvig, states that all ships must carry the Danish flag, and in 1690 all merchant ships are forbidden to use the Splitflag, with the exception of ships sailing in the East Indies, West Indies and along the coast of Africa. In 1741 it is confirmed that the regulation of 1690 is still very much in effect; that merchant ships may not use the Splitflag. At the same time the Danish East India Company is allowed to fly the Splitflag when past the equator. |
Flag of Denmark | Variants | Some confusion must have existed regarding the Splitflag. In 1696 the Admiralty presented the King with a proposal for a standard regulating both size and shape of the Splitflag. In the same year a royal resolution defines the proportions of the Splitflag, which in this resolution is called Kongeflaget (the King's flag), as follows: The cross must be 1⁄7 of the flags height. The two first fields must be square in form with the sides three times the cross width. The two outer fields are rectangular and 1+1⁄2 the length of the square fields. The tails are the length of the flag. |
Flag of Denmark | Variants | These numbers are the basic for the Splitflag, or Orlogsflag, today, though the numbers have been slightly altered. The term Orlogsflag dates from 1806 and denotes use in the Danish Navy.
From about 1750 to the early 19th century, a number of ships and companies which the government has interests in, received approval to use the Splitflag. |
Flag of Denmark | Variants | In the royal resolution of 25 October 1939 for the Danish Navy, it is stated that the Orlogsflag is a Splitflag with a deep red ("dybrød") or madder red ("kraprød") colour. Like the National flag, no nuance is given, but in modern days this is given as 195U. Furthermore, the size and shape is corrected in this resolution to be: "The cross must be 1⁄7 of the flag's height. The two first fields must be square in form with the height of 3⁄7 of the flag's height. The two outer fields are rectangular and 5⁄4 the length of the square fields. The tails are 6⁄4 the length of the rectangular fields". Thus, if compared to the standard of 1696, both the rectangular fields and the tails have decreased in size. |
Flag of Denmark | Variants | The Splitflag and Orlogsflag have similar shapes but different sizes and shades of red. Legally, they are two different flags. The Splitflag is a Danish flag ending in a swallow-tail, it is Dannebrog red, and is used on land. The Orlogsflag is an elongated Splitflag with a deeper red colour and is only used on sea.
The Orlogsflag with no markings, may only be used by the Royal Danish Navy. There are though a few exceptions to this. A few institutions have been allowed to fly the clean Orlogsflag. The same flag with markings has been approved for a few dozen companies and institutions over the years.
Furthermore, the Orlogsflag is only described as such if it has no additional markings. Any swallow-tail flag, no matter the colour, is called a Splitflag provided it bears additional markings. |
Flag of Denmark | Variants | Royal standards MonarchThe current version of the royal standard was introduced on 16 November 1972 when the Queen adopted a new version of her personal coat of arms. The royal standard is the flag of Denmark with a swallow-tail and charged with the monarch's coat of arms set in a white square. The centre square is 32 parts in a flag with the ratio 56:107. |
Flag of Denmark | Variants | Other members of the royal family |
Flag of Denmark | Other flags in the Kingdom of Denmark | Greenland and the Faroe Islands are autonomous territories within the Kingdom of Denmark. They have their own official flags.
Some areas in Denmark have unofficial flags. While they have no legal recognition or regulation, they can be used freely.
The regional flags of Bornholm and Ærø are occasionally used by locals of those islands and in tourist-related businesses. |
Flag of Denmark | Other flags in the Kingdom of Denmark | The proposal for a flag of Jutland has hardly found any actual use, maybe in part due to its peculiar design.The flag of Vendsyssel (Vendelbrog) is seen infrequently, but many locals recognise it. According to an article in the newspaper Nordjyske, the flag had been used in the former insignia of Flight Eskadrille 723 of Aalborg Air Base, in the 1980s. |
The Gene Bomb | The Gene Bomb | The Gene Bomb is a 1996 book by David E. Comings, self-published by Hope Press, that puts forth the theory that higher education and advanced technology may unintentionally favor the selection of genes that increase the likelihood of ADHD, autism, drug addiction, learning disorders, and behavior problems. Comings claims that the prevalence of these disorders is rising and I.Q. is decreasing; others argue that other factors may be responsible, including increased detection of these disorders. He claims that society is inadvertently creating delays for the highly educated that reduce their reproductivity and causes them to have children later in life, thus raising the odds of certain disorders like autism. On the other hand, he claims that those having learning disorders tend to drop out of school earlier and have more children, thus passing on learning disorders at a higher rate. Environmental and societal factors are usually accepted as the cause, but Comings argues the opposite.According to a review of the book in the British Developmental Medicine and Child Neurology journal, "The arguments are developed in this book with an alarming lack of scientific accuracy and satisfactory supporting evidence." The review concludes that the book "is an apocalyptic, irrational, and emotional treatise which opens up scientifically unsound issues that have already been formally buried". A book review in the Journal of Medical Genetics said, "This is the sort of book which gets geneticists a bad name", adding that some facts "are simply wrong", while vital facts "are simply missing". Comings replied, in a Letter to the Editor, that the review "missed the whole point of the book and presented to the readers of this journal a distorted view of the issues I attempted to raise".Other Tourette syndrome (TS) researchers say of Comings' Tourette's research that his "assertions fall outside of the mainstream of the very extensive TS literature that has developed over the past 2 decades". |
Virtual Volleyball | Virtual Volleyball | Virtual Volleyball is a video game developed and published by Imagineer Co. for the Sega Saturn. |
Virtual Volleyball | Gameplay | Virtual Volleyball is the first volleyball game using polygons to be published for any game system. |
Virtual Volleyball | Reception | Next Generation reviewed the Saturn version of the game, rating it one star out of five, and stated, "There are inherent problems in doing a volleyball game when considering the matter of trying to control an entire team, but Virtual Volleyball seems to make no effort to solve any of these problems, leaving the gamer with an extremely vacant feeling." |
Transcoder free operation | Transcoder free operation | In a telecommunication network Transcoder free operation, or TrFO, also known as Out of band transcoder control is the concept of removing transcoding function in a call path. In legacy GSM networks a call between two mobile stations involved two transcoding functions, one at each BSC. This transcoding functionality was generally implemented in a separate Transcoder and Rate Adaptation Unit, or TRAU. TRAU was connected to BSC and MSC through TDM E1 or STM-1. |
Transcoder free operation | Transcoder free operation | With the introduction of NGN and 3G networks the Radio Network Controller was connected to MGW through ATM or IP instead of TDM. Therefore, this external transcoder was removed and transcoding function was moved up to the MGW. NGN also introduced Nb interface over IP such that it became possible to carry compressed voice codecs such as AMR in the Nb interface. In a call scenario such as this the transcoding functionality in the MGW could be eliminated such that voice quality can be improved and resources in MGW also could be saved. Concept of TrFO became applicable for 2G networks also with the "A interface over IP" implementation. |
Rake angle | Rake angle | In machining, the rake angle is a parameter used in various cutting processes, describing the angle of the cutting face relative to the workpiece. There are three types of rake angles: positive, zero or neutral, and negative.
Positive rake: A tool has a positive rake when the face of the cutting tool slopes away from the cutting edge at inner side.
Zero rake: A tool has a zero (or neutral) rake when the face of the cutting tool is perpendicular to the cutting edge at inner side.
Negative rake: A tool has a negative rake angle when the face of the cutting tool slopes away from the cutting edge at outer side.Positive rake angles generally: Make the tool more sharp and pointed. This reduces the strength of the tool, as the small included angle in the tip may cause it to chip away.
Reduce cutting forces and power requirements.
Helps in the formation of continuous chips in ductile materials.
Can help avoid the formation of a built-up edge.Negative rake angles generally: Increase the strength of the cutting edge. The tool is more blunt.
Increases the cutting force.
Increases the power required for a cut.
Can increase friction, resulting in higher temperatures.
Can improve surface finish.Zero rake angles: Easier to manufacture.
Easier to resharpen.
Less power and cutting forces than a negative raked tool.
Chip will wear and 'crater' the rake face. |
Rake angle | Recommended rake angles | Recommended rake angles can vary depending on the material being cut, tool material, depth of cut, cutting speed, machine, setup and process. This table summarizes recommended rake angles for: single-point turning on a lathe, drilling, milling, and sawing. |
Radical 80 | Radical 80 | Radical 80 or radical do not (毋部) meaning "mother" or "do not" is one of the 34 Kangxi radicals (214 radicals in total) composed of 4 strokes. Chinese characters with a similar component 母 "mother" may also be classified under this radical.
In the Kangxi Dictionary, there are 16 characters (out of 49,030) to be found under this radical.
毋 is also the 99th indexing component in the Table of Indexing Chinese Character Components predominantly adopted by Simplified Chinese dictionaries published in mainland China.
In the Hokkien language, 毋 is often used to represent the negation particle [m̩], spelled m̄ in Peh-oe-ji and Tai-lo. |
Radical 80 | Literature | Fazzioli, Edoardo (1987). Chinese calligraphy : from pictograph to ideogram : the history of 214 essential Chinese/Japanese characters. calligraphy by Rebecca Hon Ko. New York: Abbeville Press. ISBN 0-89659-774-1.
Lunde, Ken (Jan 5, 2009). "Appendix J: Japanese Character Sets" (PDF). CJKV Information Processing: Chinese, Japanese, Korean & Vietnamese Computing (Second ed.). Sebastopol, Calif.: O'Reilly Media. ISBN 978-0-596-51447-1. |
Tarp tent | Tarp tent | A tarp tent is a tarpaulin, a plastic or nylon sheet, used in place of a tent. It is usually rigged with poles, tent pegs, and guy lines. Ultralight backpackers use tarp tents because they are lightweight compared to other backpacking shelters. |
Tarp tent | Tarp tent | In its simplest form it is floorless with open ends, as a fly or with the sides attached to the ground. It can also be set up as a loue with two adjacent sides by the ground and the opposite corner as highest point, giving more protection from wind and reflecting heat from an optional fire in front of the open side. |
Tarp tent | Tarp tent | A tarp tent is commonly lighter and cheaper than a tent and easier to set up. However, because it is more open, it does not provide as much protection from rain, snow, wind, or cold as a tent does. It provides no protection from insects. |
Tarp tent | Tarp tent | More sophisticated tarp tents are now manufactured or homemade with such things as bug screening and storm flaps on the ends and even floors and vents. According to Harvey Manning in his book Backpacking One Step at a Time (The REI Press Seattle), "The term 'tarp-tent' as used here denotes a broad category which at one boundary is nothing more than a shaped tarp and at the other end verges on a 'true' tent. The common characteristic is a single wall, in most cases, waterproof." In Mountaineering the Freedom of the Hills (4th ed. The Mountaineers, Seattle, WA) it says, "A tarp tent is both light in weight and low in cost, and offers adequate shelter from all but extreme weather in lowland forests and among subalpine trees." Tarp tents are frequently made of silnylon material because it is lightweight, strong, and waterproof. |
Tarp tent | Tarp tent | The basha is essentially a tarp tent used by the British and Australian armies. |
Fortezza | Fortezza | Fortezza is an information security system that uses the Fortezza Crypto Card, a PC Card-based security token. It was developed for the U.S. government's Clipper chip project and has been used by the U.S. Government in various applications.
Each individual who is authorized to see protected information is issued a Fortezza card that stores private keys and other data needed to gain access. It contains an NSA approved security microprocessor called Capstone (MYK-80) that implements the Skipjack encryption algorithm. |
Fortezza | Fortezza | The original Fortezza card (KOV-8) is a Type 2 product which means it cannot be used for classified information. The most widely used Type 1 encryption card is the KOV-12 Fortezza card which is used extensively for the Defense Message System (DMS). The KOV-12 is cleared up to TOP SECRET/SCI. A later version, called KOV-14 or Fortezza Plus, uses a Krypton microprocessor that implements stronger, Type 1 encryption and may be used for information classified up to TOP SECRET/SCI. It, in turn, is being replaced by the newer KSV-21 PC card with more modern algorithms and additional capabilities. |
Fortezza | Fortezza | The cards are interchangeable within the many types of equipment that support Fortezza and can be rekeyed and reprogrammed by the owners, making them easy to issue and reuse. This simplifies the process of rekeying equipment for crypto changes: instead of requiring an expensive fill device, a technician is able to put a new Fortezza card in the device's PCMCIA slot. |
Fortezza | Fortezza | The Fortezza Plus card and its successors are used with NSA's Secure Terminal Equipment voice and data encryption systems that are replacing the STU-III. It is manufactured by the Mykotronx Corporation and by Spyrus. Each card costs about $240 and they are commonly used with card readers sold by Litronic Corporation.
The Fortezza card has been used in government, military, and banking applications to protect sensitive data. |
Clifford bundle | Clifford bundle | In mathematics, a Clifford bundle is an algebra bundle whose fibers have the structure of a Clifford algebra and whose local trivializations respect the algebra structure. There is a natural Clifford bundle associated to any (pseudo) Riemannian manifold M which is called the Clifford bundle of M. |
Clifford bundle | General construction | Let V be a (real or complex) vector space together with a symmetric bilinear form <·,·>. The Clifford algebra Cℓ(V) is a natural (unital associative) algebra generated by V subject only to the relation v2=−⟨v,v⟩ for all v in V. One can construct Cℓ(V) as a quotient of the tensor algebra of V by the ideal generated by the above relation. |
Clifford bundle | General construction | Like other tensor operations, this construction can be carried out fiberwise on a smooth vector bundle. Let E be a smooth vector bundle over a smooth manifold M, and let g be a smooth symmetric bilinear form on E. The Clifford bundle of E is the fiber bundle whose fibers are the Clifford algebras generated by the fibers of E: Cℓ(E)=∐x∈MCℓ(Ex,gx) The topology of Cℓ(E) is determined by that of E via an associated bundle construction. |
Clifford bundle | General construction | One is most often interested in the case where g is positive-definite or at least nondegenerate; that is, when (E, g) is a Riemannian or pseudo-Riemannian vector bundle. For concreteness, suppose that (E, g) is a Riemannian vector bundle. The Clifford bundle of E can be constructed as follows. Let CℓnR be the Clifford algebra generated by Rn with the Euclidean metric. The standard action of the orthogonal group O(n) on Rn induces a graded automorphism of CℓnR. The homomorphism ρ:O(n)→Aut(CℓnR) is determined by ρ(A)(v1v2⋯vk)=(Av1)(Av2)⋯(Avk) where vi are all vectors in Rn. The Clifford bundle of E is then given by Cℓ(E)=F(E)×ρCℓnR where F(E) is the orthonormal frame bundle of E. It is clear from this construction that the structure group of Cℓ(E) is O(n). Since O(n) acts by graded automorphisms on CℓnR it follows that Cℓ(E) is a bundle of Z2-graded algebras over M. The Clifford bundle Cℓ(E) can then be decomposed into even and odd subbundles: Cℓ(E)=Cℓ0(E)⊕Cℓ1(E). |
Clifford bundle | General construction | If the vector bundle E is orientable then one can reduce the structure group of Cℓ(E) from O(n) to SO(n) in the natural manner. |
Clifford bundle | Clifford bundle of a Riemannian manifold | If M is a Riemannian manifold with metric g, then the Clifford bundle of M is the Clifford bundle generated by the tangent bundle TM. One can also build a Clifford bundle out of the cotangent bundle T*M. The metric induces a natural isomorphism TM = T*M and therefore an isomorphism Cℓ(TM) = Cℓ(T*M).
There is a natural vector bundle isomorphism between the Clifford bundle of M and the exterior bundle of M: Cℓ(T∗M)≅Λ(T∗M).
This is an isomorphism of vector bundles not algebra bundles. The isomorphism is induced from the corresponding isomorphism on each fiber. In this way one can think of sections of the Clifford bundle as differential forms on M equipped with Clifford multiplication rather than the wedge product (which is independent of the metric).
The above isomorphism respects the grading in the sense that Cℓ0(T∗M)=Λeven(T∗M)Cℓ1(T∗M)=Λodd(T∗M).
Local description For a vector v∈TxM at x∈M , and a form ψ∈Λ(TxM) the Clifford multiplication is defined as vψ=v∧ψ+v⌟ψ where the metric duality to change vector to the one form is used in the first term. |
Clifford bundle | Clifford bundle of a Riemannian manifold | Then the exterior derivative d and coderivative δ can be related to the metric connection ∇ using the choice of an orthonormal base {ea} by d=ea∧∇ea,δ=−ea⌟∇ea Using these definitions, the Dirac-Kähler operator is defined by D=ea∇ea=d−δ On a star domain the operator can be inverted using Poincare lemma for exterior derivative and its Hodge star dual for coderivative. Practical way of doing this is by homotopy and cohomotopy operators. |
Suprachoroidal drug delivery | Suprachoroidal drug delivery | Suprachoroidal drug delivery is an ocular route of drug administration. It involves using a microneedle to provide a minimally invasive method and injecting particles of a medication into the suprachoroidal space (SCS) between the sclera and choroid in the eye. |
Hyperpolarization (biology) | Hyperpolarization (biology) | Hyperpolarization is a change in a cell's membrane potential that makes it more negative. It is the opposite of a depolarization. It inhibits action potentials by increasing the stimulus required to move the membrane potential to the action potential threshold. |
Hyperpolarization (biology) | Hyperpolarization (biology) | Hyperpolarization is often caused by efflux of K+ (a cation) through K+ channels, or influx of Cl– (an anion) through Cl– channels. On the other hand, influx of cations, e.g. Na+ through Na+ channels or Ca2+ through Ca2+ channels, inhibits hyperpolarization. If a cell has Na+ or Ca2+ currents at rest, then inhibition of those currents will also result in a hyperpolarization. This voltage-gated ion channel response is how the hyperpolarization state is achieved. In neurons, the cell enters a state of hyperpolarization immediately following the generation of an action potential. While hyperpolarized, the neuron is in a refractory period that lasts roughly 2 milliseconds, during which the neuron is unable to generate subsequent action potentials. Sodium-potassium ATPases redistribute K+ and Na+ ions until the membrane potential is back to its resting potential of around –70 millivolts, at which point the neuron is once again ready to transmit another action potential. |
Hyperpolarization (biology) | Voltage-gated ion channels and hyperpolarization | Voltage gated ion channels respond to changes in the membrane potential. Voltage gated potassium, chloride and sodium channels are key components in the generation of the action potential as well as hyper-polarization. These channels work by selecting an ion based on electrostatic attraction or repulsion allowing the ion to bind to the channel. This releases the water molecule attached to the channel and the ion is passed through the pore. Voltage gated sodium channels open in response to a stimulus and close again. This means the channel either is open or not, there is no part way open. Sometimes the channel closes but is able to be reopened right away, known as channel gating, or it can be closed without being able to be reopened right away, known as channel inactivation. |
Hyperpolarization (biology) | Voltage-gated ion channels and hyperpolarization | At resting potential, both the voltage gated sodium and potassium channels are closed but as the cell membrane becomes depolarized the voltage gated sodium channels begin to open up and the neuron begins to depolarize, creating a current feedback loop known as the Hodgkin cycle. However, potassium ions naturally move out of the cell and if the original depolarization event was not significant enough then the neuron does not generate an action potential. If all the sodium channels are open, however, then the neuron becomes ten times more permeable to sodium than potassium, quickly depolarizing the cell to a peak of +40 mV. At this level the sodium channels begin to inactivate and voltage gated potassium channels begin to open. This combination of closed sodium channels and open potassium channels leads to the neuron re-polarizing and becoming negative again. The neuron continues to re-polarize until the cell reaches ~ –75 mV, which is the equilibrium potential of potassium ions. This is the point at which the neuron is hyperpolarized, between –70 mV and –75 mV. After hyperpolarization the potassium channels close and the natural permeability of the neuron to sodium and potassium allows the neuron to return to its resting potential of –70 mV. During the refractory period, which is after hyper-polarization but before the neuron has returned to its resting potential the neuron is capable of triggering an action potential due to the sodium channels ability to be opened, however, because the neuron is more negative it becomes more difficult to reach the action potential threshold. |
Hyperpolarization (biology) | Voltage-gated ion channels and hyperpolarization | HCN channels are activated by hyperpolarization.
Recent research has shown that neuronal refractory periods can exceed 20 milliseconds where the relation between hyperpolarization and the neuronal refractory was questioned. |
Hyperpolarization (biology) | Experimental technique | Hyperpolarization is a change in membrane potential. Neuroscientists measure it using a technique known as patch clamping that allows them to record ion currents passing through individual channels. This is done using a glass micropipette, also called a patch pipette, with a 1 micrometer diameter. There is a small patch that contains a few ion channels and the rest is sealed off, making this the point of entry for the current. Using an amplifier and a voltage clamp, which is an electronic feedback circuit, allows the experimenter to maintain the membrane potential at a fixed point and the voltage clamp then measures tiny changes in current flow. The membrane currents giving rise to hyperpolarization are either an increase in outward current or a decrease in inward current. |
Hyperpolarization (biology) | Examples | During the afterhyperpolarization period after an action potential, the membrane potential is more negative than when the cell is at the resting potential. In the figure to the right, this undershoot occurs at approximately 3 to 4 milliseconds (ms) on the time scale. The afterhyperpolarization is the time when the membrane potential is hyperpolarized relative to the resting potential. |
Hyperpolarization (biology) | Examples | During the rising phase of an action potential, the membrane potential changes from negative to positive, a depolarization. In the figure, the rising phase is from approximately 1 to 2 ms on the graph. During the rising phase, once the membrane potential becomes positive, the membrane potential continues to depolarize (overshoot) until the peak of the action potential is reached at about +40 millivolts (mV). After the peak of the action potential, a hyperpolarization repolarizes the membrane potential to its resting value, first by making it less positive, until 0 mV is reached, and then by continuing to make it more negative. This repolarization occurs in the figure from approximately 2 to 3 ms on the time scale. |
Infratrochlear nerve | Infratrochlear nerve | The infratrochlear nerve is a branch of the nasociliary nerve (itself a branch of the ophthalmic nerve (CN V1)) in the orbit. It exits the orbit inferior to the trochlea of superior oblique. It provides sensory innervation to structures of the orbit and skin of adjacent structures.: 631, 783 |
Infratrochlear nerve | Structure | The nasociliary nerve terminates by bifurcating into the infratrochlear and the anterior ethmoidal nerves. The infratrochlear nerve travels anteriorly in the orbit along the upper border of the medial rectus muscle and underneath the trochlea of the superior oblique muscle. It exits the orbit medially and divides into small sensory branches.
Distribution The infratrochlear nerve provides sensory innervation to the skin of the eyelids, the conjunctiva, lacrimal sac, lacrimal caruncle, and the side of the nose superior to the medial canthus.: 631, 783 Communications The infratrochlear nerve receives a descending communicating branch from the supratrochlear nerve.: 782 |
Infratrochlear nerve | Etymology | The infratrochlear nerve is named after a structure it passes under. Infratrochlear means "below the trochlea". The term trochlea means "pulley" in Latin. Specifically, the trochlea refers to a fibrocartilaginous loop at the superomedial surface of the orbit called the trochlea, through which the tendon of the superior oblique muscle passes. |
Spare parts management | Spare parts management | Service parts management is the main component of a complete strategic service management process that companies use to ensure that right spare part and resources are at the right place (where the broken part is) at the right time.
Spare parts, are extra parts that are available and in proximity to a functional item, such as an automobile, boat, engine, for which they might be used for repair. |
Spare parts management | Economic considerations | Spare parts are sometimes considered uneconomical since: the parts might never be used the parts might not be stored properly, leading to defects maintaining inventory of spare parts has associated costs parts may not be available when needed from a supplierBut without the spare part on hand, a company's customer satisfaction levels could drop if a customer has to wait too long for their item to be fixed. Therefore, companies need to plan and align their service parts inventory and workforce resources to achieve optimal customer satisfaction levels with minimal costs. |
Spare parts management | User considerations | The user of the item, which might require the parts, may overlook the economic considerations because: the expense is not the user's but the supplier's of a known high rate of failure of certain equipment of delays in getting the part from a vendor or a supply room, resulting in machine outage to have the parts on hand requires less "paperwork" when the parts are suddenly needed of the mental comfort it provides to the user in knowing the parts are on-hand when needed The parts are un-economic to be repaired i.e. it's cheaper to discard than to get it repaired |
Spare parts management | Cost-effect compromise | In many cases where the item is not stationary, a compromise is reached between cost and statistical probability. Some examples: an automobile carries a less-functional "donut" tire as replacement instead of a functionally equivalent tire.
a member of a household buys extra light bulbs since it is probable that one of the lights in the house will eventually burn out and require replacement.
a computer user will purchase a ream of computer paper instead of a sheet at a time.
a race car team will bring another engine to the race track "just in case".
a ship carries "spare parts" for its engine in case of breakdown at sea. |
Spare parts management | Measures of effectiveness | The effectiveness of spares inventory can be measured by metrics such as fill rate and availability of the end item. |
Spare parts management | Notes | SD-19 in conjunction with MIL-HDBK-512, Parts Management guidance MIL-HDBK-512 handbook is a guide for Military Acquisition Activities (AA) in the preparation of Requests for Proposals (RFPs) with respect to a parts management program, and will help determine to what extent parts management should be for a given program. It will also identify those elements in a proposal to manage the selection and use of parts. |
Refrigeration | Refrigeration | Refrigeration is any of various types of cooling of a space, substance, or system to lower and/or maintain its temperature below the ambient one (while the removed heat is ejected to a place of higher temperature). Refrigeration is an artificial, or human-made, cooling method.Refrigeration refers to the process by which energy, in the form of heat, is removed from a low-temperature medium and transferred to a high-temperature medium. This work of energy transfer is traditionally driven by mechanical means (whether ice or electromechanical machines), but it can also be driven by heat, magnetism, electricity, laser, or other means. Refrigeration has many applications, including household refrigerators, industrial freezers, cryogenics, and air conditioning. Heat pumps may use the heat output of the refrigeration process, and also may be designed to be reversible, but are otherwise similar to air conditioning units. |
Refrigeration | Refrigeration | Refrigeration has had a large impact on industry, lifestyle, agriculture, and settlement patterns. The idea of preserving food dates back to human prehistory, but for thousands of years humans were limited regarding the means of doing so. They used curing via salting and drying, and they made use of natural coolness in caves, root cellars, and winter weather, but other means of cooling were unavailable. In the 19th century, they began to make use of the ice trade to develop cold chains. In the late 19th through mid-20th centuries, mechanical refrigeration was developed, improved, and greatly expanded in its reach. Refrigeration has thus rapidly evolved in the past century, from ice harvesting to temperature-controlled rail cars, refrigerator trucks, and ubiquitous refrigerators and freezers in both stores and homes in many countries. The introduction of refrigerated rail cars contributed to the settlement of areas that were not on earlier main transport channels such as rivers, harbors, or valley trails. |
Refrigeration | Refrigeration | These new settlement patterns sparked the building of large cities which are able to thrive in areas that were otherwise thought to be inhospitable, such as Houston, Texas, and Las Vegas, Nevada. In most developed countries, cities are heavily dependent upon refrigeration in supermarkets in order to obtain their food for daily consumption. The increase in food sources has led to a larger concentration of agricultural sales coming from a smaller percentage of farms. Farms today have a much larger output per person in comparison to the late 1800s. This has resulted in new food sources available to entire populations, which has had a large impact on the nutrition of society. |
Refrigeration | History | Earliest forms of cooling The seasonal harvesting of snow and ice is an ancient practice estimated to have begun earlier than 1000 BC. A Chinese collection of lyrics from this time period known as the Shijing, describes religious ceremonies for filling and emptying ice cellars. However, little is known about the construction of these ice cellars or the purpose of the ice. The next ancient society to record the harvesting of ice may have been the Jews in the book of Proverbs, which reads, "As the cold of snow in the time of harvest, so is a faithful messenger to them who sent him." Historians have interpreted this to mean that the Jews used ice to cool beverages rather than to preserve food. Other ancient cultures such as the Greeks and the Romans dug large snow pits insulated with grass, chaff, or branches of trees as cold storage. Like the Jews, the Greeks and Romans did not use ice and snow to preserve food, but primarily as a means to cool beverages. Egyptians cooled water by evaporation in shallow earthen jars on the roofs of their houses at night. The ancient people of India used this same concept to produce ice. The Persians stored ice in a pit called a Yakhchal and may have been the first group of people to use cold storage to preserve food. In the Australian outback before a reliable electricity supply was available many farmers used a Coolgardie safe, consisting of a room with hessian (burlap) curtains hanging from the ceiling soaked in water. The water would evaporate and thereby cool the room, allowing many perishables such as fruit, butter, and cured meats to be kept. |
Refrigeration | History | Ice harvesting Before 1830, few Americans used ice to refrigerate foods due to a lack of ice-storehouses and iceboxes. As these two things became more widely available, individuals used axes and saws to harvest ice for their storehouses. This method proved to be difficult, dangerous, and certainly did not resemble anything that could be duplicated on a commercial scale.Despite the difficulties of harvesting ice, Frederic Tudor thought that he could capitalize on this new commodity by harvesting ice in New England and shipping it to the Caribbean islands as well as the southern states. In the beginning, Tudor lost thousands of dollars, but eventually turned a profit as he constructed icehouses in Charleston, Virginia and in the Cuban port town of Havana. These icehouses as well as better insulated ships helped reduce ice wastage from 66% to 8%. This efficiency gain influenced Tudor to expand his ice market to other towns with icehouses such as New Orleans and Savannah. This ice market further expanded as harvesting ice became faster and cheaper after one of Tudor's suppliers, Nathaniel Wyeth, invented a horse-drawn ice cutter in 1825. This invention as well as Tudor's success inspired others to get involved in the ice trade and the ice industry grew. |
Refrigeration | History | Ice became a mass-market commodity by the early 1830s with the price of ice dropping from six cents per pound to a half of a cent per pound. In New York City, ice consumption increased from 12,000 tons in 1843 to 100,000 tons in 1856. Boston's consumption leapt from 6,000 tons to 85,000 tons during that same period. Ice harvesting created a "cooling culture" as majority of people used ice and iceboxes to store their dairy products, fish, meat, and even fruits and vegetables. These early cold storage practices paved the way for many Americans to accept the refrigeration technology that would soon take over the country. |
Refrigeration | History | Refrigeration research The history of artificial refrigeration began when Scottish professor William Cullen designed a small refrigerating machine in 1755. Cullen used a pump to create a partial vacuum over a container of diethyl ether, which then boiled, absorbing heat from the surrounding air. The experiment even created a small amount of ice, but had no practical application at that time. |
Refrigeration | History | In 1758, Benjamin Franklin and John Hadley, professor of chemistry, collaborated on a project investigating the principle of evaporation as a means to rapidly cool an object at Cambridge University, England. They confirmed that the evaporation of highly volatile liquids, such as alcohol and ether, could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to quicken the evaporation; they lowered the temperature of the thermometer bulb down to −14 °C (7 °F), while the ambient temperature was 18 °C (65 °F). They noted that soon after they passed the freezing point of water 0 °C (32 °F), a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about a 6.4 millimetres (1⁄4 in) thick when they stopped the experiment upon reaching −14 °C (7 °F). Franklin wrote, "From this experiment, one may see the possibility of freezing a man to death on a warm summer's day". In 1805, American inventor Oliver Evans described a closed vapor-compression refrigeration cycle for the production of ice by ether under vacuum. |
Refrigeration | History | In 1820, the English scientist Michael Faraday liquefied ammonia and other gases by using high pressures and low temperatures, and in 1834, an American expatriate to Great Britain, Jacob Perkins, built the first working vapor-compression refrigeration system in the world. It was a closed-cycle that could operate continuously, as he described in his patent: I am enabled to use volatile fluids for the purpose of producing the cooling or freezing of fluids, and yet at the same time constantly condensing such volatile fluids, and bringing them again into operation without waste.His prototype system worked although it did not succeed commercially.In 1842, a similar attempt was made by American physician, John Gorrie, who built a working prototype, but it was a commercial failure. Like many of the medical experts during this time, Gorrie thought too much exposure to tropical heat led to mental and physical degeneration, as well as the spread of diseases such as malaria. He conceived the idea of using his refrigeration system to cool the air for comfort in homes and hospitals to prevent disease. American engineer Alexander Twining took out a British patent in 1850 for a vapour compression system that used ether. |
Refrigeration | History | The first practical vapour-compression refrigeration system was built by James Harrison, a British journalist who had emigrated to Australia. His 1856 patent was for a vapour-compression system using ether, alcohol, or ammonia. He built a mechanical ice-making machine in 1851 on the banks of the Barwon River at Rocky Point in Geelong, Victoria, and his first commercial ice-making machine followed in 1854. Harrison also introduced commercial vapour-compression refrigeration to breweries and meat-packing houses, and by 1861, a dozen of his systems were in operation. He later entered the debate of how to compete against the American advantage of unrefrigerated beef sales to the United Kingdom. In 1873 he prepared the sailing ship Norfolk for an experimental beef shipment to the United Kingdom, which used a cold room system instead of a refrigeration system. The venture was a failure as the ice was consumed faster than expected. |
Refrigeration | History | The first gas absorption refrigeration system using gaseous ammonia dissolved in water (referred to as "aqua ammonia") was developed by Ferdinand Carré of France in 1859 and patented in 1860. Carl von Linde, an engineer specializing in steam locomotives and professor of engineering at the Technological University of Munich in Germany, began researching refrigeration in the 1860s and 1870s in response to demand from brewers for a technology that would allow year-round, large-scale production of lager; he patented an improved method of liquefying gases in 1876. His new process made possible using gases such as ammonia, sulfur dioxide (SO2) and methyl chloride (CH3Cl) as refrigerants and they were widely used for that purpose until the late 1920s. |
Refrigeration | History | Thaddeus Lowe, an American balloonist, held several patents on ice-making machines. His "Compression Ice Machine" would revolutionize the cold-storage industry. In 1869, other investors and he purchased an old steamship onto which they loaded one of Lowe's refrigeration units and began shipping fresh fruit from New York to the Gulf Coast area, and fresh meat from Galveston, Texas back to New York, but because of Lowe's lack of knowledge about shipping, the business was a costly failure. |
Refrigeration | History | Commercial use In 1842, John Gorrie created a system capable of refrigerating water to produce ice. Although it was a commercial failure, it inspired scientists and inventors around the world. France's Ferdinand Carre was one of the inspired and he created an ice producing system that was simpler and smaller than that of Gorrie. During the Civil War, cities such as New Orleans could no longer get ice from New England via the coastal ice trade. Carre's refrigeration system became the solution to New Orleans' ice problems and, by 1865, the city had three of Carre's machines. In 1867, in San Antonio, Texas, a French immigrant named Andrew Muhl built an ice-making machine to help service the expanding beef industry before moving it to Waco in 1871. In 1873, the patent for this machine was contracted by the Columbus Iron Works, a company acquired by the W.C. Bradley Co., which went on to produce the first commercial ice-makers in the US. |
Refrigeration | History | By the 1870s, breweries had become the largest users of harvested ice. Though the ice-harvesting industry had grown immensely by the turn of the 20th century, pollution and sewage had begun to creep into natural ice, making it a problem in the metropolitan suburbs. Eventually, breweries began to complain of tainted ice. Public concern for the purity of water, from which ice was formed, began to increase in the early 1900s with the rise of germ theory. Numerous media outlets published articles connecting diseases such as typhoid fever with natural ice consumption. This caused ice harvesting to become illegal in certain areas of the country. All of these scenarios increased the demands for modern refrigeration and manufactured ice. Ice producing machines like that of Carre's and Muhl's were looked to as means of producing ice to meet the needs of grocers, farmers, and food shippers.Refrigerated railroad cars were introduced in the US in the 1840s for short-run transport of dairy products, but these used harvested ice to maintain a cool temperature. |
Refrigeration | History | The new refrigerating technology first met with widespread industrial use as a means to freeze meat supplies for transport by sea in reefer ships from the British Dominions and other countries to the British Isles. Although not actually the first to achieve successful transportation of frozen goods overseas (the Strathleven had arrived at the London docks on 2 February 1880 with a cargo of frozen beef, mutton and butter from Sydney and Melbourne ), the breakthrough is often attributed to William Soltau Davidson, an entrepreneur who had emigrated to New Zealand. Davidson thought that Britain's rising population and meat demand could mitigate the slump in world wool markets that was heavily affecting New Zealand. After extensive research, he commissioned the Dunedin to be refitted with a compression refrigeration unit for meat shipment in 1881. On February 15, 1882, the Dunedin sailed for London with what was to be the first commercially successful refrigerated shipping voyage, and the foundation of the refrigerated meat industry.The Times commented "Today we have to record such a triumph over physical difficulties, as would have been incredible, even unimaginable, a very few days ago...". The Marlborough—sister ship to the Dunedin – was immediately converted and joined the trade the following year, along with the rival New Zealand Shipping Company vessel Mataurua, while the German Steamer Marsala began carrying frozen New Zealand lamb in December 1882. Within five years, 172 shipments of frozen meat were sent from New Zealand to the United Kingdom, of which only 9 had significant amounts of meat condemned. Refrigerated shipping also led to a broader meat and dairy boom in Australasia and South America. J & E Hall of Dartford, England outfitted the SS Selembria with a vapor compression system to bring 30,000 carcasses of mutton from the Falkland Islands in 1886. In the years ahead, the industry rapidly expanded to Australia, Argentina and the United States. |
Refrigeration | History | By the 1890s, refrigeration played a vital role in the distribution of food. The meat-packing industry relied heavily on natural ice in the 1880s and continued to rely on manufactured ice as those technologies became available. By 1900, the meat-packing houses of Chicago had adopted ammonia-cycle commercial refrigeration. By 1914, almost every location used artificial refrigeration. The major meat packers, Armour, Swift, and Wilson, had purchased the most expensive units which they installed on train cars and in branch houses and storage facilities in the more remote distribution areas. |
Refrigeration | History | By the middle of the 20th century, refrigeration units were designed for installation on trucks or lorries. Refrigerated vehicles are used to transport perishable goods, such as frozen foods, fruit and vegetables, and temperature-sensitive chemicals. Most modern refrigerators keep the temperature between –40 and –20 °C, and have a maximum payload of around 24,000 kg gross weight (in Europe). |
Refrigeration | History | Although commercial refrigeration quickly progressed, it had limitations that prevented it from moving into the household. First, most refrigerators were far too large. Some of the commercial units being used in 1910 weighed between five and two hundred tons. Second, commercial refrigerators were expensive to produce, purchase, and maintain. Lastly, these refrigerators were unsafe. It was not uncommon for commercial refrigerators to catch fire, explode, or leak toxic gases. Refrigeration did not become a household technology until these three challenges were overcome. |
Refrigeration | History | Home and consumer use During the early 1800s, consumers preserved their food by storing food and ice purchased from ice harvesters in iceboxes. In 1803, Thomas Moore patented a metal-lined butter-storage tub which became the prototype for most iceboxes. These iceboxes were used until nearly 1910 and the technology did not progress. In fact, consumers that used the icebox in 1910 faced the same challenge of a moldy and stinky icebox that consumers had in the early 1800s.General Electric (GE) was one of the first companies to overcome these challenges. In 1911, GE released a household refrigeration unit that was powered by gas. The use of gas eliminated the need for an electric compressor motor and decreased the size of the refrigerator. However, electric companies that were customers of GE did not benefit from a gas-powered unit. Thus, GE invested in developing an electric model. In 1927, GE released the Monitor Top, the first refrigerator to run on electricity.In 1930, Frigidaire, one of GE's main competitors, synthesized Freon. With the invention of synthetic refrigerants based mostly on a chlorofluorocarbon (CFC) chemical, safer refrigerators were possible for home and consumer use. Freon led to the development of smaller, lighter, and cheaper refrigerators. The average price of a refrigerator dropped from $275 to $154 with the synthesis of Freon. This lower price allowed ownership of refrigerators in American households to exceed 50% by 1940. Freon is a trademark of the DuPont Corporation and refers to these CFCs, and later hydro chlorofluorocarbon (HCFC) and hydro fluorocarbon (HFC), refrigerants developed in the late 1920s. These refrigerants were considered — at the time — to be less harmful than the commonly-used refrigerants of the time, including methyl formate, ammonia, methyl chloride, and sulfur dioxide. The intent was to provide refrigeration equipment for home use without danger. These CFC refrigerants answered that need. In the 1970s, though, the compounds were found to be reacting with atmospheric ozone, an important protection against solar ultraviolet radiation, and their use as a refrigerant worldwide was curtailed in the Montreal Protocol of 1987. |
Refrigeration | Impact on settlement patterns in the United States of America | In the last century, refrigeration allowed new settlement patterns to emerge. This new technology has allowed for new areas to be settled that are not on a natural channel of transport such as a river, valley trail or harbor that may have otherwise not been settled. Refrigeration has given opportunities to early settlers to expand westward and into rural areas that were unpopulated. These new settlers with rich and untapped soil saw opportunity to profit by sending raw goods to the eastern cities and states. In the 20th century, refrigeration has made "Galactic Cities" such as Dallas, Phoenix and Los Angeles possible. |
Refrigeration | Impact on settlement patterns in the United States of America | Refrigerated rail cars The refrigerated rail car (refrigerated van or refrigerator car), along with the dense railroad network, became an exceedingly important link between the marketplace and the farm allowing for a national opportunity rather than a just a regional one. Before the invention of the refrigerated rail car, it was impossible to ship perishable food products long distances. The beef packing industry made the first demand push for refrigeration cars. The railroad companies were slow to adopt this new invention because of their heavy investments in cattle cars, stockyards, and feedlots. Refrigeration cars were also complex and costly compared to other rail cars, which also slowed the adoption of the refrigerated rail car. After the slow adoption of the refrigerated car, the beef packing industry dominated the refrigerated rail car business with their ability to control ice plants and the setting of icing fees. The United States Department of Agriculture estimated that, in 1916, over sixty-nine percent of the cattle killed in the country was done in plants involved in interstate trade. The same companies that were also involved in the meat trade later implemented refrigerated transport to include vegetables and fruit. The meat packing companies had much of the expensive machinery, such as refrigerated cars, and cold storage facilities that allowed for them to effectively distribute all types of perishable goods. During World War I, a national refrigerator car pool was established by the United States Administration to deal with problem of idle cars and was later continued after the war. The idle car problem was the problem of refrigeration cars sitting pointlessly in between seasonal harvests. This meant that very expensive cars sat in rail yards for a good portion of the year while making no revenue for the car's owner. The car pool was a system where cars were distributed to areas as crops matured ensuring maximum use of the cars. Refrigerated rail cars moved eastward from vineyards, orchards, fields, and gardens in western states to satisfy Americas consuming market in the east. The refrigerated car made it possible to transport perishable crops hundreds and even thousands of kilometres or miles. The most noticeable effect the car gave was a regional specialization of vegetables and fruits. The refrigeration rail car was widely used for the transportation of perishable goods up until the 1950s. By the 1960s, the nation's interstate highway system was adequately complete allowing for trucks to carry the majority of the perishable food loads and to push out the old system of the refrigerated rail cars. |
Refrigeration | Impact on settlement patterns in the United States of America | Expansion west and into rural areas The widespread use of refrigeration allowed for a vast amount of new agricultural opportunities to open up in the United States. New markets emerged throughout the United States in areas that were previously uninhabited and far-removed from heavily populated areas. New agricultural opportunity presented itself in areas that were considered rural, such as states in the south and in the west. Shipments on a large scale from the south and California were both made around the same time, although natural ice was used from the Sierras in California rather than manufactured ice in the south. Refrigeration allowed for many areas to specialize in the growing of specific fruits. California specialized in several fruits, grapes, peaches, pears, plums, and apples, while Georgia became famous for specifically its peaches. In California, the acceptance of the refrigerated rail cars led to an increase of car loads from 4,500 carloads in 1895 to between 8,000 and 10,000 carloads in 1905. The Gulf States, Arkansas, Missouri and Tennessee entered into strawberry production on a large-scale while Mississippi became the center of the tomato industry. New Mexico, Colorado, Arizona, and Nevada grew cantaloupes. Without refrigeration, this would have not been possible. By 1917, well-established fruit and vegetable areas that were close to eastern markets felt the pressure of competition from these distant specialized centers. Refrigeration was not limited to meat, fruit and vegetables but it also encompassed dairy product and dairy farms. In the early twentieth century, large cities got their dairy supply from farms as far as 640 kilometres (400 mi). Dairy products were not as easily transported over great distances like fruits and vegetables due to greater perishability. Refrigeration made production possible in the west far from eastern markets, so much in fact that dairy farmers could pay transportation cost and still undersell their eastern competitors. Refrigeration and the refrigerated rail gave opportunity to areas with rich soil far from natural channel of transport such as a river, valley trail or harbors. |
Refrigeration | Impact on settlement patterns in the United States of America | Rise of the galactic city "Edge city" was a term coined by Joel Garreau, whereas the term "galactic city" was coined by Lewis Mumford. These terms refer to a concentration of business, shopping, and entertainment outside a traditional downtown or central business district in what had previously been a residential or rural area. There were several factors contributing to the growth of these cities such as Los Angeles, Las Vegas, Houston, and Phoenix. The factors that contributed to these large cities include reliable automobiles, highway systems, refrigeration, and agricultural production increases. Large cities such as the ones mentioned above have not been uncommon in history, but what separates these cities from the rest are that these cities are not along some natural channel of transport, or at some crossroad of two or more channels such as a trail, harbor, mountain, river, or valley. These large cities have been developed in areas that only a few hundred years ago would have been uninhabitable. Without a cost efficient way of cooling air and transporting water and food from great distances, these large cities would have never developed. The rapid growth of these cities was influenced by refrigeration and an agricultural productivity increase, allowing more distant farms to effectively feed the population. |
Refrigeration | Impact on agriculture and food production | Agriculture's role in developed countries has drastically changed in the last century due to many factors, including refrigeration. Statistics from the 2007 census gives information on the large concentration of agricultural sales coming from a small portion of the existing farms in the United States today. This is a partial result of the market created for the frozen meat trade by the first successful shipment of frozen sheep carcasses coming from New Zealand in the 1880s. As the market continued to grow, regulations on food processing and quality began to be enforced. Eventually, electricity was introduced into rural homes in the United States, which allowed refrigeration technology to continue to expand on the farm, increasing output per person. Today, refrigeration's use on the farm reduces humidity levels, avoids spoiling due to bacterial growth, and assists in preservation. |
Refrigeration | Impact on agriculture and food production | Demographics The introduction of refrigeration and evolution of additional technologies drastically changed agriculture in the United States. During the beginning of the 20th century, farming was a common occupation and lifestyle for United States citizens, as most farmers actually lived on their farm. In 1935, there were 6.8 million farms in the United States and a population of 127 million. Yet, while the United States population has continued to climb, citizens pursuing agriculture continue to decline. Based on the 2007 US Census, less than one percent of a population of 310 million people claim farming as an occupation today. However, the increasing population has led to an increasing demand for agricultural products, which is met through a greater variety of crops, fertilizers, pesticides, and improved technology. Improved technology has decreased the risk and time involved for agricultural management and allows larger farms to increase their output per person to meet society's demand. |
Refrigeration | Impact on agriculture and food production | Meat packing and trade Prior to 1882, the South Island of New Zealand had been experimenting with sowing grass and crossbreeding sheep, which immediately gave their farmers economic potential in the exportation of meat. In 1882, the first successful shipment of sheep carcasses was sent from Port Chalmers in Dunedin, New Zealand, to London. By the 1890s, the frozen meat trade became increasingly more profitable in New Zealand, especially in Canterbury, where 50% of exported sheep carcasses came from in 1900. It wasn't long before Canterbury meat was known for the highest quality, creating a demand for New Zealand meat around the world. In order to meet this new demand, the farmers improved their feed so sheep could be ready for the slaughter in only seven months. This new method of shipping led to an economic boom in New Zealand by the mid 1890s.In the United States, the Meat Inspection Act of 1891 was put in place in the United States because local butchers felt the refrigerated railcar system was unwholesome. When meat packing began to take off, consumers became nervous about the quality of the meat for consumption. Upton Sinclair's 1906 novel The Jungle brought negative attention to the meat packing industry, by drawing to light unsanitary working conditions and processing of diseased animals. The book caught the attention of President Theodore Roosevelt, and the 1906 Meat Inspection Act was put into place as an amendment to the Meat Inspection Act of 1891. This new act focused on the quality of the meat and environment it is processed in. |
Refrigeration | Impact on agriculture and food production | Electricity in rural areas In the early 1930s, 90 percent of the urban population of the United States had electric power, in comparison to only 10 percent of rural homes. At the time, power companies did not feel that extending power to rural areas (rural electrification) would produce enough profit to make it worth their while. However, in the midst of the Great Depression, President Franklin D. Roosevelt realized that rural areas would continue to lag behind urban areas in both poverty and production if they were not electrically wired. On May 11, 1935, the president signed an executive order called the Rural Electrification Administration, also known as REA. The agency provided loans to fund electric infrastructure in the rural areas. In just a few years, 300,000 people in rural areas of the United States had received power in their homes. |