A mill is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting. Such comminution is an important unit operation in many processes. There are many different types of many types of materials processed in them. Mills were powered by hand, working animal, wind or water. Today they are powered by electricity; the grinding of solid materials occurs through mechanical forces that break up the structure by overcoming the interior bonding forces. After the grinding the state of the solid is changed: the grain size, the grain size disposition and the grain shape. Milling refers to the process of breaking down, sizing, or classifying aggregate material. For instance rock crushing or grinding to produce uniform aggregate size for construction purposes, or separation of rock, soil or aggregate material for the purposes of structural fill or land reclamation activities. Aggregate milling processes are used to remove or separate contamination or moisture from aggregate or soil and to produce "dry fills" prior to transport or structural filling.
Grinding may serve the following purposes in engineering: increase of the surface area of a solid manufacturing of a solid with a desired grain size pulping of resources In spite of a great number of studies in the field of fracture schemes there is no formula known which connects the technical grinding work with grinding results. To calculate the needed grinding work against the grain size changing three semi-empirical models are used; these can be related to the Hukki relationship between particle size and the energy required to break the particles. In stirred mills, the Hukki relationship does not apply and instead, experimentation has to be performed to determine any relationship. Kick for d > 50 mm W K = c k Bond for 50 mm > d > 0.05 mm W B = c B Von Rittinger for d < 0.05 mm W R = c R with W as grinding work in kJ/kg, c as grinding coefficient, dA as grain size of the source material and dE as grain size of the ground material. A reliable value for the grain sizes dA and dE is d80; this value signifies.
The Bond's grinding coefficient for different materials can be found in various literature. To calculate the KICK's and Rittinger's coefficients following formulas can be used c K = 1.151 c B − 0.5 c R = 0.5 c B 0.5 with the limits of Bond's range: upper dBU = 50 mm and lower dBL = 0.05 mm. To evaluate the grinding results the grain size disposition of the source material and of the ground material is needed. Grinding degree is the ratio of the sizes from the grain disposition. There are several definitions for this characteristic value: Grinding degree referring to grain size d80 Z d = d 80, 1 d 80, 2 Instead of the value of d80 d50 or other grain diameter can be used. Grinding degree referring to specific surface Z S = S v, 2 S v, 1 = S m, 2 S m, 1 The specific surface area referring to volume Sv and the specific surface area referring to mass Sm can be found out through experiments. Pretended grinding degree Z a = d 1 a The discharge die gap a of the grinding machine is used for the ground solid matter in this formula.
In materials processing a grinder is a machine for producing fine particle size reduction through attrition and compressive forces at the grain size level. See crusher for mechanisms producing larger particles. In general, grinding processes require a large amount of energy. A typical type of fine grinder is the ball mill. A inclined or horizontal rotating cylinder is filled with balls stone or metal, which grind material to the necessary fineness by friction and impact with the tumblin
Louhi is a wicked queen of the land known as Pohjola in Finnish and Karelian mythology. As many mythological creatures and objects are conflated and separated in Finnish mythology, Louhi is an alter-ego of the goddess Loviatar. Louhi is described as a powerful and evil witch queen ruling over the northern realm of Pohjola, with the ability to change shape and weave mighty enchantments, she is the main opponent of Väinämöinen and his group in the battle for the magical artifact Sampo in the Kalevala. She has a number of beautiful daughters, whom Ilmarinen, Lemminkäinen and other heroes attempt to win in various legends. In true fairy tale form, Louhi sets them difficult to impossible tasks to perform in order to claim such a prize, which leads to the forging of the Sampo. Louhi was the main antagonist in the Finnish-Soviet film Sampo, played by Anna Orochko. There is an orchestral work Louhi by the Finnish composer Kalevi Aho, the wind orchestral work Louhi's Spells / Louhen loitsut by Finnish composer Tomi Räisänen.
Louhi is track 5 on Kesto, recorded by Pan Sonic. Louhi was an inspiration for a foe of Conan the Barbarian's in the Marvel comics version of the character and the Final Fantasy: The 4 Heroes of Light boss character Louhi the Witch of the North, as well as the Final Fantasy XI item Louhi's Mask. Louhi is the main antagonist of Michael Scott Rohan's fantasy trilogy The Winter of the World. Louhi is one of the names of the witch Iggwilv in the Dungeons & Dragons game's Greyhawk campaign by Gary Gygax. In his book Sea of Death, Iggwilv is mentioned as being called Louhi on an alternate Earth. Louhikäärme – Louhi's snake – is an archaic form of lohikäärme meaning dragon in Finnish. Laufey, the mother of Loki in Norse mythology Louhi -- Britannica Online Encyclopedia
An astrolabe is an elaborate inclinometer used by astronomers and navigators to measure the altitude above the horizon of a celestial body, day or night. It can be used to identify stars or planets, to determine local latitude given local time, to survey, or to triangulate, it was used in classical antiquity, the Islamic Golden Age, the European Middle Ages and the Age of Discovery for all these purposes. The astrolabe's importance not only comes from the early development of astronomy, but is effective for determining latitude on land or calm seas. Although it is less reliable on the heaving deck of a ship in rough seas, the mariner's astrolabe was developed to solve that problem. OED gives the translation "star-taker" for the English word astrolabe and traces it through medieval Latin to the Greek word astrolabos, from astron "star" and lambanein "to take". In the medieval Islamic world the Arabic word "al-Asturlāb" was given various etymologies. In Arabic texts, the word is translated as "ākhdhu al-Nujuum", a direct translation of the Greek word.
Al-Biruni quotes and criticizes medieval scientist Hamzah al-Isfahani who stated: "asturlab is an arabization of this Persian phrase". In medieval Islamic sources, there is a folk etymology of the word as "lines of lab", where "Lab" refers to a certain son of Idris; this etymology is mentioned by a 10th-century scientist rejected by al-Khwarizmi. An early astrolabe was invented in the Hellenistic civilization by Apollonius of Perga between 220 and 150 BC attributed to Hipparchus; the astrolabe was a marriage of the planisphere and dioptra an analog calculator capable of working out several different kinds of problems in astronomy. Theon of Alexandria wrote a detailed treatise on the astrolabe, Lewis argues that Ptolemy used an astrolabe to make the astronomical observations recorded in the Tetrabiblos; the invention of the plane astrolabe is sometimes wrongly attributed to Theon's daughter Hypatia, but it is, in fact, known to have been in use at least 500 years before Hypatia was born. The misattribution comes from a misinterpretation of a statement in a letter written by Hypatia's pupil Synesius, which mentions that Hypatia had taught him how to construct a plane astrolabe, but does not state anything about her having invented it herself.
Astrolabes continued in use in the Greek-speaking world throughout the Byzantine period. About 550 AD, Christian philosopher John Philoponus wrote a treatise on the astrolabe in Greek, the earliest extant treatise on the instrument. Mesopotamian bishop Severus Sebokht wrote a treatise on the astrolabe in the Syriac language in the mid-7th century. Sebokht refers to the astrolabe as being made of brass in the introduction of his treatise, indicating that metal astrolabes were known in the Christian East well before they were developed in the Islamic world or in the Latin West. Astrolabes were further developed in the medieval Islamic world, where Muslim astronomers introduced angular scales to the design, adding circles indicating azimuths on the horizon, it was used throughout the Muslim world, chiefly as an aid to navigation and as a way of finding the Qibla, the direction of Mecca. Eighth-century mathematician Muhammad al-Fazari is the first person credited with building the astrolabe in the Islamic world.
The mathematical background was established by Muslim astronomer Albatenius in his treatise Kitab az-Zij, translated into Latin by Plato Tiburtinus. The earliest surviving astrolabe is dated AH 315. In the Islamic world, astrolabes were used to find the times of sunrise and the rising of fixed stars, to help schedule morning prayers. In the 10th century, al-Sufi first described over 1,000 different uses of an astrolabe, in areas as diverse as astronomy, navigation, timekeeping, Salat, etc; the spherical astrolabe was a variation of both the astrolabe and the armillary sphere, invented during the Middle Ages by astronomers and inventors in the Islamic world. The earliest description of the spherical astrolabe dates back to Al-Nayrizi. In the 12th century, Sharaf al-Dīn al-Tūsī invented the linear astrolabe, sometimes called the "staff of al-Tusi", "a simple wooden rod with graduated markings but without sights, it was furnished with a plumb line and a double chord for making angular measurements and bore a perforated pointer".
The geared mechanical astrolabe was invented by Abi Bakr of Isfahan in 1235. Herman Contractus, the abbot of Reichman Abbey, examined the use of the astrolabe in Mensura Astrolai during the 11th century. Peter of Maricourt wrote a treatise on the construction and use of a universal astrolabe in the last half of the 13th century entitled Nova compositio astrolabii particularis. Universal astrolabes can be found at the History of Science Museum in Oxford. English author Geoffrey Chaucer compiled A Treatise on the Astrolabe for his son based on a work by Messahalla or Ibn al-Saffar; the same source was translated by others. The first printed book on the astrolabe was Composition and Use of Astrolabe by Christian of Prachatice using Messahalla, but original. In 1370, the first Indian treatise on the astrolabe was written by the Jain astronomer Mahendra Suri. A simplified astrolabe, known as a balesilha, was used by sailors to get an accurate reading of latitude while out to sea; the use of
Greek mythology is the body of myths told by the ancient Greeks. These stories concern the origin and the nature of the world, the lives and activities of deities and mythological creatures, the origins and significance of the ancient Greeks' own cult and ritual practices. Modern scholars study the myths in an attempt to shed light on the religious and political institutions of ancient Greece and its civilization, to gain understanding of the nature of myth-making itself; the Greek myths were propagated in an oral-poetic tradition most by Minoan and Mycenaean singers starting in the 18th century BC. Two poems by Homer's near contemporary Hesiod, the Theogony and the Works and Days, contain accounts of the genesis of the world, the succession of divine rulers, the succession of human ages, the origin of human woes, the origin of sacrificial practices. Myths are preserved in the Homeric Hymns, in fragments of epic poems of the Epic Cycle, in lyric poems, in the works of the tragedians and comedians of the fifth century BC, in writings of scholars and poets of the Hellenistic Age, in texts from the time of the Roman Empire by writers such as Plutarch and Pausanias.
Aside from this narrative deposit in ancient Greek literature, pictorial representations of gods and mythic episodes featured prominently in ancient vase-paintings and the decoration of votive gifts and many other artifacts. Geometric designs on pottery of the eighth century BC depict scenes from the Trojan cycle as well as the adventures of Heracles. In the succeeding Archaic and Hellenistic periods and various other mythological scenes appear, supplementing the existing literary evidence. Greek mythology has had an extensive influence on the culture and literature of Western civilization and remains part of Western heritage and language. Poets and artists from ancient times to the present have derived inspiration from Greek mythology and have discovered contemporary significance and relevance in the themes. Greek mythology is known today from Greek literature and representations on visual media dating from the Geometric period from c. 900 BC to c. 800 BC onward. In fact and archaeological sources integrate, sometimes mutually supportive and sometimes in conflict.
Mythical narration plays an important role in nearly every genre of Greek literature. The only general mythographical handbook to survive from Greek antiquity was the Library of Pseudo-Apollodorus; this work attempts to reconcile the contradictory tales of the poets and provides a grand summary of traditional Greek mythology and heroic legends. Apollodorus of Athens wrote on many of these topics, his writings may have formed the basis for the collection. Among the earliest literary sources are the Iliad and the Odyssey. Other poets completed the "epic cycle", but these and lesser poems now are lost entirely. Despite their traditional name, the "Homeric Hymns" have no direct connection with Homer, they are choral hymns from the earlier part of the so-called Lyric age. Hesiod, a possible contemporary with Homer, offers in his Theogony the fullest account of the earliest Greek myths, dealing with the creation of the world. Hesiod's Works and Days, a didactic poem about farming life includes the myths of Prometheus and the Five Ages.
The poet gives advice on the best way to succeed in a dangerous world, rendered yet more dangerous by its gods. Lyrical poets took their subjects from myth, but their treatment became less narrative and more allusive. Greek lyric poets, including Pindar and Simonides, bucolic poets such as Theocritus and Bion, relate individual mythological incidents. Additionally, myth was central to classical Athenian drama; the tragic playwrights Aeschylus and Euripides took most of their plots from myths of the age of heroes and the Trojan War. Many of the great tragic stories took on their classic form in these tragedies; the comic playwright Aristophanes used myths, in The Birds and The Frogs. Historians Herodotus and Diodorus Siculus, geographers Pausanias and Strabo, who traveled throughout the Greek world and noted the stories they heard, supplied numerous local myths and legends giving little-known alternative versions. Herodotus in particular, searched the various traditions presented him and found the historical or mythological roots in the confrontation between Greece and the East.
Herodotus attempted to reconcile the blending of differing cultural concepts. The poetry of the Hellenistic and Roman ages was composed as a literary rather than cultic exercise, it contains many important details that would otherwise be lost. This category includes the works of: The Roman poets Ovid, Valerius Flaccus and Virgil with Servius's commentary; the Greek poets of the Late Antique period: Nonnus, Antoninus Liberalis, Quintus Smyrnaeus. The Greek poets of the Hellenistic period: Apollonius of Rhodes, Pseudo-Eratosthenes, Parthenius. Prose writers from the same periods who make reference to myths includ
A blacksmith is a metalsmith who creates objects from wrought iron or steel by forging the metal, using tools to hammer and cut. Blacksmiths produce objects such as gates, railings, light fixtures, sculpture, agricultural implements and religious items, cooking utensils and weapons. While there are many people who work with metal such as farriers and armorers, the blacksmith had a general knowledge of how to make and repair many things, from the most complex of weapons and armor to simple things like nails or lengths of chain; the "black" in "blacksmith" refers to the black firescale, a layer of oxides that forms on the surface of the metal during heating. The origin of "smith" is debated, it may come from the old English word "smythe" meaning "to strike" or it may have originated from the Proto-German "smithaz" meaning "skilled worker." Blacksmiths work by heating pieces of wrought iron or steel until the metal becomes soft enough for shaping with hand tools, such as a hammer and chisel. Heating takes place in a forge fueled by propane, natural gas, charcoal, coke or oil.
Some modern blacksmiths may employ an oxyacetylene or similar blowtorch for more localized heating. Induction heating methods are gaining popularity among modern blacksmiths. Color is important for indicating the workability of the metal; as iron heats to higher temperatures, it first glows red orange and white. The ideal heat for most forging is the bright yellow-orange color; because they must be able to see the glowing color of the metal, some blacksmiths work in dim, low-light conditions, but most work in well-lit conditions. The key is to have consistent lighting, but not too bright. Direct sunlight obscures the colors; the techniques of smithing can be divided into forging, heat-treating, finishing. Forging—the process smiths use to shape metal by hammering—differs from machining in that forging does not remove material. Instead, the smith hammers the iron into shape. Punching and cutting operations by smiths re-arrange metal around the hole, rather than drilling it out as swarf. Forging uses seven basic operations or techniques: Drawing down Shrinking Bending Upsetting Swaging Punching Forge weldingThese operations require at least a hammer and anvil, but smiths use other tools and techniques to accommodate odd-sized or repetitive jobs.
Drawing lengthens the metal by reducing one or both of the other two dimensions. As the depth is reduced, or the width narrowed, the piece is lengthened or "drawn out." As an example of drawing, a smith making a chisel might flatten a square bar of steel, lengthening the metal, reducing its depth but keeping its width consistent. Drawing does not have to be uniform. A taper can result as in making a woodworking chisel blade. If tapered in two dimensions, a point results. Drawing can be accomplished with a variety of methods. Two typical methods using only hammer and anvil would be hammering on the anvil horn, hammering on the anvil face using the cross peen of a hammer. Another method for drawing is to use a tool called a fuller, or the peen of the hammer, to hasten the drawing out of a thick piece of metal. Fullering consists of hammering a series of indentations with corresponding ridges, perpendicular to the long section of the piece being drawn; the resulting effect looks somewhat like waves along the top of the piece.
The smith turns the hammer over to use the flat face to hammer the tops of the ridges down level with the bottoms of the indentations. This forces the metal to grow in length much faster than just hammering with the flat face of the hammer. Heating iron to a "forging heat" allows bending as if it were a soft, ductile metal, like copper or silver. Bending can be done with the hammer over the horn or edge of the anvil or by inserting a bending fork into the hardy hole, placing the work piece between the tines of the fork, bending the material to the desired angle. Bends can be dressed and tightened, or widened, by hammering them over the appropriately shaped part of the anvil; some metals are "hot short". They become like Plasticine: although they may still be manipulated by squeezing, an attempt to stretch them by bending or twisting, is to have them crack and break apart; this is a problem for some blade-making steels, which must be worked to avoid developing hidden cracks that would cause failure in the future.
Though hand-worked, titanium is notably hot short. Such common smithing processes as decoratively twisting a bar are impossible with it. Upsetting is the process of making metal thicker in one dimension through shortening in the other. One form is to heat the end of a rod and hammer on it as one would drive a nail: the rod gets shorter, the hot part widens. An alternative to hammering on the hot end is to place the hot end on the anvil and hammer on the cold end. Punching may be done to make a hole. For example, in preparation for making a hammerhead, a smith would punch a hole in a heavy bar or rod for the hammer handle. Punching is not limited to holes, it includes cutting and drifting—all done with a chisel. The five basic forging processes are combined to produce and refine the shapes necessary for finished products. For example, to fashion a cross-peen hammer head, a smith would start with a bar the diameter of the ham
The Kalevala is a 19th-century work of epic poetry compiled by Elias Lönnrot from Karelian and Finnish oral folklore and mythology. It is regarded as the national epic of Karelia and Finland and is one of the most significant works of Finnish literature; the Kalevala was instrumental in the development of the Finnish national identity, the intensification of Finland's language strife and the growing sense of nationality that led to Finland's independence from Russia in 1917. The first version of The Kalevala was published in 1835; the version most known today was first published in 1849 and consists of 22,795 verses, divided into fifty folk stories. Elias Lönnrot was a physician, botanist and poet. During the time he was compiling the Kalevala he was the district health officer based in Kajaani responsible for the whole Kainuu region in the eastern part of what was the Grand Duchy of Finland, he was the son of a tailor and Ulrika Lönnrot. At the age of 21, he entered the Imperial Academy of Turku and obtained a master's degree in 1826.
His thesis was entitled De Vainamoine priscorum fennorum numine. The monograph's second volume was destroyed in the Great Fire of Turku the same year. In the spring of 1828, he set out with the aim of poetry. Rather than continue this work, though, he decided to complete his studies and entered Imperial Alexander University in Helsinki to study medicine, he earned a master's degree in 1832. In January 1833, he started as the district health officer of Kainuu and began his work on collecting poetry and compiling the Kalevala. Throughout his career Lönnrot made a total of eleven field trips within a period of fifteen years. Prior to the publication of the Kalevala, Elias Lönnrot compiled several related works, including the three-part Kantele, the Old Kalevala and the Kanteletar. Lönnrot's field trips and endeavours not only helped him to compile the Kalevala, but brought considerable enjoyment to the people he visited. Before the 18th century the Kalevala poetry was common throughout Finland and Karelia, but in the 18th century it began to disappear in Finland, first in western Finland, because European rhymed poetry became more common in Finland.
Finnish folk poetry was first written down in the 17th century and collected by hobbyists and scholars through the following centuries. Despite this, the majority of Finnish poetry remained only in the oral tradition. Finnish born nationalist and linguist Kaarle Akseli Gottlund expressed his desire for a Finnish epic in a similar vein to The Iliad and the Nibelungenlied compiled from the various poems and songs spread over most of Finland, he hoped that such an endeavour would incite a sense of nationality and independence in the native Finnish people. In 1820, Reinhold von Becker founded the journal Turun Wiikko-Sanomat and published three articles entitled Väinämöisestä; these works were an inspiration for Elias Lönnrot in creating his masters thesis at Turku University. In the 19th century, collecting became more extensive and organised. Altogether half a million pages of verse have been collected and archived by the Finnish Literature Society and other collectors in what are now Estonia and the Republic of Karelia.
The publication Suomen Kansan Vanhat Runot published 33 volumes containing 85,000 items of poetry over a period of 40 years. They have archived 65,000 items of poetry that remain unpublished. By the end of the 19th century this pastime of collecting material relating to Karelia and the developing orientation towards eastern lands had become a fashion called Karelianism, a form of national romanticism; the chronology of this oral tradition is uncertain. The oldest themes have been interpreted to have their roots in distant, unrecorded history and could be as old as 3,000 years; the newest events seem to be from the Iron Age. Finnish folklorist Kaarle Krohn proposes that 20 of the 45 poems of The Kalevala are of possible Ancient Estonian origin or at least deal with a motif of Estonian origin, it is understood that during the Finnish reformation in the 16th century the clergy forbade all telling and singing of pagan rites and stories. In conjunction with the arrival of European poetry and music this caused a significant reduction in the number of traditional folk songs and their singers.
Thus the tradition faded somewhat but was never eradicated. In total, Lönnrot made eleven field trips in search of poetry, his first trip was made in 1828 after his graduation from Turku University, but it was not until 1831 and his second field trip that the real work began. By that time he had published three articles entitled Kantele and had significant notes to build upon; this second trip was not successful and he was called back to Helsinki to attend to victims of the Second cholera pandemic. The third field trip was much more successful and led Elias Lönnrot to Viena in east Karelia where he visited the town of Akonlahti, which proved most successful; this trip yielded over copious notes. In 1833, Lönnrot moved to Kajaani where he was to spend the next 20 years as the district health officer for the region, his fourth field trip was undertaken in conjunction with his work as a doctor. This trip resulted in 49 poem