Carbon fiber reinforced polymer
Carbon fiber reinforced polymer, carbon fiber reinforced plastic, or carbon fiber reinforced thermoplastic, is an strong and light fiber-reinforced plastic which contains carbon fibers. The alternative spelling'fibre' is common in British Commonwealth countries. CFRPs can be expensive to produce but are used wherever high strength-to-weight ratio and stiffness are required, such as aerospace, superstructure of ships, civil engineering, sports equipment, an increasing number of consumer and technical applications; the binding polymer is a thermoset resin such as epoxy, but other thermoset or thermoplastic polymers, such as polyester, vinyl ester, or nylon, are sometimes used. The composite material may contain aramid, ultra-high-molecular-weight polyethylene, aluminium, or glass fibers in addition to carbon fibers; the properties of the final CFRP product can be affected by the type of additives introduced to the binding matrix. The most common additive is silica, but other additives such as rubber and carbon nanotubes can be used.
The material is referred to as graphite-reinforced polymer or graphite fiber-reinforced polymer. CFRPs are composite materials. In this case the composite consists of two parts: a reinforcement. In CFRP the reinforcement is carbon fiber; the matrix is a polymer resin, such as epoxy, to bind the reinforcements together. Because CFRP consists of two distinct elements, the material properties depend on these two elements. Reinforcement gives CFRP its rigidity. Unlike isotropic materials like steel and aluminum, CFRP has directional strength properties; the properties of CFRP depend on the layouts of the carbon fiber and the proportion of the carbon fibers relative to the polymer. The two different equations governing the net elastic modulus of composite materials using the properties of the carbon fibers and the polymer matrix can be applied to carbon fiber reinforced plastics; the following equation, E c = V m E m + V f E f is valid for composite materials with the fibers oriented in the direction of the applied load.
E c is the total composite modulus, V m and V f are the volume fractions of the matrix and fiber in the composite, E m and E f are the elastic moduli of the matrix and fibers respectively. The other extreme case of the elastic modulus of the composite with the fibers oriented transverse to the applied load can be found using the following equation: E c = − 1 The fracture toughness of carbon fiber reinforced plastics is governed by the following mechanisms: 1) debonding between the carbon fiber and polymer matrix, 2) fiber pull-out, 3) delamination between the CFRP sheets. Typical epoxy-based CFRPs exhibit no plasticity, with less than 0.5% strain to failure. Although CFRPs with epoxy have high strength and elastic modulus, the brittle fracture mechanics present unique challenges to engineers in failure detection since failure occurs catastrophically; as such, recent efforts to toughen CFRPs include modifying the existing epoxy material and finding alternative polymer matrix. One such material with high promise is PEEK, which exhibits an order of magnitude greater toughness with similar elastic modulus and tensile strength.
However, PEEK is more expensive. Despite its high initial strength-to-weight ratio, a design limitation of CFRP is its lack of a definable fatigue limit; this means, that stress cycle failure cannot be ruled out. While steel and many other structural metals and alloys do have estimable fatigue or endurance limits, the complex failure modes of composites mean that the fatigue failure properties of CFRP are difficult to predict and design for; as a result, when using CFRP for critical cyclic-loading applications, engineers may need to design in considerable strength safety margins to provide suitable component reliability over its service life. Environmental effects such as temperature and humidity can have profound effects on the polymer-based composites, including most CFRPs. While CFRPs demonstrate excellent corrosion resistance, the effect of moisture at wide ranges of temperatures can lead to degradation of the mechanical properties of CFRPs at the matrix-fiber interface. While the carbon fibers themselves are not affected by the moisture diffusing into the material, the moisture plasticizes the polymer matrix.
The epoxy matrix used for engine fan blades is designed to be impervious against jet fuel and rain water, external paint on the composites parts is applied to minimize damage from ultraviolet light. The carbon fibers can cause galvanic corrosion; the primary element of CFRP is a carbon filament.
Odawa
The Odawa, said to mean "traders", are an Indigenous American ethnic group who inhabit land in the northern United States and southern Canada. They have long had territory that crosses the current border between the two countries, they are federally recognized as Native American tribes in the United States and have numerous recognized First Nations bands in Canada, they are one of the Anishinaabeg, related to but distinct from the Potawatomi peoples. After migrating from the East Coast in ancient times, they settled on Manitoulin Island, near the northern shores of Lake Huron, the Bruce Peninsula in the present-day province of Ontario, Canada, they considered this their original homeland. After the 17th century, they settled along the Ottawa River, in the states of Michigan and Wisconsin, as well as through the Midwest south of the Great Lakes in the latter country. In the 21st century, there are 15,000 Odawa living in Ontario, Michigan and Oklahoma; the Ottawa dialect is part of the Algonquian language family.
This large family has numerous smaller tribal groups or “bands,” called “Tribe” in the United States and “First Nation” in Canada. Their language is considered a divergent dialect of Ojibwe, characterized by frequent syncope. Odawaa; the Potawatomi spelling of Odawa and the English derivative "Ottawa" are common. The Anishinaabe word for "Those men who trade, or buy and sell" is Wadaawewinini. Fr. Frederic Baraga, a Catholic missionary in Michigan, transliterated this and recorded it in his A Dictionary of the Otchipwe Language as "Watawawininiwok," noting that it meant "men of the bulrushes", associated with the many bulrushes in the Ottawa River. But, this recorded meaning is more appropriately associated with the Matàwackariniwak, a historical Algonquin band who lived along the Ottawa River; the only American tribe, Odawa are the Little Traverse Bay Band of Odawa Indians, the rest are considered Ottawa. Their neighbors applied the "Trader" name to the Odawa because in early traditional times, during the early European contact period, they were noted as intertribal traders and barterers.
The Odawa were described as having dealt "chiefly in cornmeal, sunflower oil and skins, rugs and mats and medicinal roots and herbs."Like the Ojibwe, the Odawa identify as Nishnaabe, meaning "original people". The Odawa name in its English transcription is the source of the place names of Ottawa and the Ottawa River; the Odawa home territory at the time of early European contact, but not their trading zone, was well to the west of the city and river named after them. The tribe is the namesake for Tawas City and Tawas Point, which reflect the syncope-form of their name. Ottawa, Ohio is the county seat of Putnam County, developed at the site of the last Ottawa reservation in Ohio; the Odawa dialect is considered one of several divergent dialects of the Ojibwe language group, noted for its frequent syncope. In the Odawa language, the general language group is known as Nishnabemwin, while the Odawa language is called Daawaamwin. Of the estimated 5,000 ethnic Odawa and additional 10,000 people with some Odawa ancestry, in the early 21st century an estimated 500 people in Ontario and Michigan speak this language.
The Ottawa Tribe of Oklahoma has three fluent speakers. According to Anishinaabeg tradition, from recordings in Wiigwaasabak, the Odawa people came from the eastern areas of North America, or Turtle Island, from along the East Coast. Directed by the miigis beings, the Anishinaabe peoples moved inland along the Saint Lawrence River. At the "Third Stopping Place" near what is now Detroit, the southern group of Anishinaabeg divided into three groups, the Ojibwe and Potawatomi. There is archaeological evidence that the Saugeen Complex people, a Hopewell-influenced group who were located on the Bruce Peninsula during the Middle Woodland period, may have evolved into the Odawa people; the Hopewell tradition was a extended trading network operating from about 200BCE to 500 CE. Some of these peoples constructed earthwork mounds for burials, a practice that ended about 250 CE; the Saugeen mounds have not been excavated. The Odawa, together with the Ojibwe and Potawatomi, were part of a long-term tribal alliance called the Council of Three Fires, which fought the Iroquois Confederacy and the Dakota people.
In 1615 French explorer Samuel de Champlain met 300 men of a nation which, he said, "we call les cheueux releuez" near the French River mouth. Of these, he said: "Their arms consisted only of a bow and arrows, a buckler of boiled leather and the club, they wore no breech clouts, their bodies were tattooed in many fashions and designs, their faces painted and their noses pierced." In 1616, Champlain left the Huron villages and visited the "Cheueux releuez," who lived westward from the lands of the Huron Confederacy. The Jesuit Relations of 1667 report three tribes living in the same town: the Odawa, the Kiskakon Odawa, the Sinago Odawa. All three tribes spoke the same language. Due to the extensive trade network maintained by the Odawa, many of the North American interior nations became known by names which their trading partners used for them, rather than by the nations’ own names. For example, these exonyms include Winnebago for t
Hainan
Hainan is the smallest and southernmost province of the People's Republic of China, consisting of various islands in the South China Sea. Hainan Island, separated from Guangdong's Leizhou Peninsula by the Qiongzhou Strait, is the largest and most populous island under PRC control and makes up the majority of the province; the province has an area of 33,920 square kilometers, with Hainan Island making up 32,900 square kilometers and the rest divided among 200 islands scattered across three archipelagos. It was administered as part of Guangdong until 1988. There are ten counties in Hainan Province. Haikou on the northern coast of Hainan Island is the capital while Sanya is a well-known tourist destination on the southern coast; the other major cities are Wenchang, Wanning, Wuzhishan and Danzhou. According to China's territorial claims several territories in the South China Sea, including the Spratly Islands and Paracel Islands, are notionally administered as part of the province; the provincial name derives from its major island, Hainan, in Hainanese "Hai Nam", named after its position south of the Qiongzhou Strait.
Former names for Hainan Island include Zhuya and Qiongzhou. The two gave rise to the provincial abbreviation 瓊 or 琼. Hainan was attached to the Northeastern part of what is now Vietnam. Hainan Island first entered written history in 110 BC, when the Han dynasty of China established a military garrison there following the arrival of General Lu Bode. In 46 BC the Han court abandoned the island. Around that time, Han Chinese people together with military personnel and officials began to migrate to Hainan Island from the mainland. Among them were the offspring of those who were banished to Hainan for political reasons. Most of them arrived in Hainan Island from the southern Chinese provinces of Guangdong and Guangxi. Li people are the original Kra-Dai inhabitants of Hainan, they are believed to be the descendants of the ancient tribes from the mainland, who settled on the island between 7 and 27 thousand years ago. The Li people reside in the nine cities and counties in the middle and southern part of Hainan – the cities of Sanya and Dongfang, the Li autonomous counties of Baisha, Ledong and the'Li and Miao Autonomous Counties of Qiongzhong and Baoting'.
Some others live elsewhere on Hainan with other ethnic groups in Danzhou, Qionghai and Tunchang. The area inhabited by the Li ethnic group totals 18,700 square kilometers, about 55 percent of the province's total. During the Three Kingdoms Period, Hainan was the Zhuya Commandery under the control of Eastern Wu. At the time of the Song dynasty, Hainan became part of Guangxi, for the first time large numbers of Han Chinese arrived, settling in the north. Under the Mongol Empire the island became an independent province in 1370 was placed under the administration of Guangdong by the ruling Ming dynasty. In the sixteenth and seventeenth centuries, large numbers of Han people from Fujian and Guangdong began migrating to Hainan, pushing the Li into the highlands in the southern half of the island. In the eighteenth century, the Li rebelled against the Qing Empire, which responded by bringing in mercenaries from the Miao regions of Guizhou. Many of the Miao settled on the island and their descendants live in the western highlands to this day.
During the 17th and 18th centuries, explorers referred to the island as "Aynam", which remains the pronunciation of its name in the local Hainanese dialect. In 1906, the revolutionary leader Sun Yat-sen proposed that Hainan should become a separate province although this did not happen until 1988. Hainan was part of Guangdong and Guangxi Provinces and as such was the Qiongya Circuit under the 1912 establishment of the Republic of China. In 1921, it was planned to become a special administrative region. During the 1920s and 30s, Hainan was a hotbed of Communist activity after a bloody crackdown in Shanghai, the Republic of China in 1927 drove many Communists into hiding; the Communists and the indigenous Hlai people fought a vigorous guerrilla campaign against the Imperial Japanese occupation, the Hainan Island Operation, but in retaliation the Japanese launched numerous massacres against Li villages. Feng Baiju led the Hainan Independent Column of fighters throughout the 1940s. After the Japanese surrender in 1945, the Kuomintang reestablished control.
Hainan was one of the last areas of the Chinese mainland controlled by Nationalist forces: Landing Operation on Hainan Island From March to May 1950, the Landing Operation on Hainan Island captured the island for the Chinese communists. Hainan had been left to the command of Xue Yue. Feng Baiju and his column of guerrilla fighters played an essential role in scouting for the landing operation and coordinated their own offensive from their jun
Ancient Greek art
Ancient Greek art stands out among that of other ancient cultures for its development of naturalistic but idealized depictions of the human body, in which nude male figures were the focus of innovation. The rate of stylistic development between about 750 and 300 BC was remarkable by ancient standards, in surviving works is best seen in sculpture. There were important innovations in painting, which have to be reconstructed due to the lack of original survivals of quality, other than the distinct field of painted pottery. Greek architecture, technically simple, established a harmonious style with numerous detailed conventions that were adopted by Roman architecture and are still followed in some modern buildings, it used a vocabulary of ornament, shared with pottery and other media, had an enormous influence on Eurasian art after Buddhism carried it beyond the expanded Greek world created by Alexander the Great. The social context of Greek art included radical political developments and a great increase in prosperity.
The earliest art by Greeks is excluded from "ancient Greek art", instead known as Aegean art. The art of ancient Greece is divided stylistically into four periods: the Geometric, Archaic and Hellenistic; the Geometric age is dated from about 1000 BC, although in reality little is known about art in Greece during the preceding 200 years, traditionally known as the Greek Dark Ages. The 7th century BC witnessed the slow development of the Archaic style as exemplified by the black-figure style of vase painting. Around 500 BC, shortly before the onset of the Persian Wars, is taken as the dividing line between the Archaic and the Classical periods, the reign of Alexander the Great is taken as separating the Classical from the Hellenistic periods. From some point in the 1st century BC onwards "Greco-Roman" is used, or more local terms for the Eastern Greek world. In reality, there was no sharp transition from one period to another. Forms of art developed at different speeds in different parts of the Greek world, as in any age some artists worked in more innovative styles than others.
Strong local traditions, the requirements of local cults, enable historians to locate the origins of works of art found far from their place of origin. Greek art of various kinds was exported; the whole period saw a steady increase in prosperity and trading links within the Greek world and with neighbouring cultures. The survival rate of Greek art differs starkly between media. We have huge quantities of pottery and coins, much stone sculpture, though more Roman copies, a few large bronze sculptures. Missing are painting, fine metal vessels, anything in perishable materials including wood; the stone shell of a number of temples and theatres has survived, but little of their extensive decoration. By convention, finely painted vessels of all shapes are called "vases", there are over 100,000 complete surviving pieces, giving unparalleled insights into many aspects of Greek life. Sculptural or architectural pottery very painted, are referred to as terracottas, survive in large quantities. In much of the literature, "pottery" means only painted vessels, or "vases".
Pottery was the main form of grave goods deposited in tombs as "funerary urns" containing the cremated ashes, was exported. The famous and distinctive style of Greek vase-painting with figures depicted with strong outlines, with thin lines within the outlines, reached its peak from about 600 to 350 BC, divides into the two main styles reversals of each other, of black-figure and red-figure painting, the other colour forming the background in each case. Other colours were limited to small areas of white and larger ones of a different purplish-red. Within the restrictions of these techniques and other strong conventions, vase-painters achieved remarkable results, combining refinement and powerful expression. White ground technique allowed more freedom in depiction, but did not wear well and was made for burial. Conventionally, the ancient Greeks are said to have made most pottery vessels for everyday use, not for display. Exceptions are the large Archaic monumental vases made as grave-markers, trophies won at games, such as the Panathenaic Amphorae filled with olive oil, pieces made to be left in graves.
In recent decades many scholars have questioned this, seeing much more production than was thought as made to be placed in graves, as a cheaper substitute for metalware in both Greece and Etruria. Most surviving pottery consists of vessels for storing, serving or drinking liquids such as amphorae, hydria, libation bowls and perfume bottles for the toilet and cups. Painted vessels for serving and eating food are much less common. Painted pottery was affordable by ordinary people, a piece "decently decorated with about five or six figures cost about two or three days' wages". Miniatures were produced in large numbers for use as offerings at temples. In the Hellenistic period a wider range of pottery was produced, but most of it is of little artistic importance. In earlier periods quite small Greek cities produced pottery for their own locale. These
Middle East
The Middle East is a transcontinental region centered on Western Asia and Egypt. Saudi Arabia is geographically the largest Middle Eastern nation; the corresponding adjective is Middle Eastern and the derived noun is Middle Easterner. The term has come into wider usage as a replacement of the term Near East beginning in the early 20th century. Arabs, Persians and Azeris constitute the largest ethnic groups in the region by population. Arabs constitute the largest ethnic group in the region by a clear margin. Indigenous minorities of the Middle East include Jews, Assyrians, Copts, Lurs, Samaritans, Shabaks and Zazas. European ethnic groups that form a diaspora in the region include Albanians, Circassians, Crimean Tatars, Franco-Levantines, Italo-Levantines. Among other migrant populations are Chinese, Indians, Pakistanis, Pashtuns and sub-Saharan Africans; the history of the Middle East dates back to ancient times, with the importance of the region being recognized for millennia. Several major religions have their origins in the Middle East, including Judaism and Islam.
The Middle East has a hot, arid climate, with several major rivers providing irrigation to support agriculture in limited areas such as the Nile Delta in Egypt, the Tigris and Euphrates watersheds of Mesopotamia, most of what is known as the Fertile Crescent. Most of the countries that border the Persian Gulf have vast reserves of crude oil, with monarchs of the Arabian Peninsula in particular benefiting economically from petroleum exports; the term "Middle East" may have originated in the 1850s in the British India Office. However, it became more known when American naval strategist Alfred Thayer Mahan used the term in 1902 to "designate the area between Arabia and India". During this time the British and Russian Empires were vying for influence in Central Asia, a rivalry which would become known as The Great Game. Mahan realized not only the strategic importance of the region, but of its center, the Persian Gulf, he labeled the area surrounding the Persian Gulf as the Middle East, said that after Egypt's Suez Canal, it was the most important passage for Britain to control in order to keep the Russians from advancing towards British India.
Mahan first used the term in his article "The Persian Gulf and International Relations", published in September 1902 in the National Review, a British journal. The Middle East, if I may adopt a term which I have not seen, will some day need its Malta, as well as its Gibraltar. Naval force has the quality of mobility; the British Navy should have the facility to concentrate in force if occasion arise, about Aden and the Persian Gulf. Mahan's article was reprinted in The Times and followed in October by a 20-article series entitled "The Middle Eastern Question," written by Sir Ignatius Valentine Chirol. During this series, Sir Ignatius expanded the definition of Middle East to include "those regions of Asia which extend to the borders of India or command the approaches to India." After the series ended in 1903, The Times removed quotation marks from subsequent uses of the term. Until World War II, it was customary to refer to areas centered around Turkey and the eastern shore of the Mediterranean as the "Near East", while the "Far East" centered on China, the Middle East meant the area from Mesopotamia to Burma, namely the area between the Near East and the Far East.
In the late 1930s, the British established the Middle East Command, based in Cairo, for its military forces in the region. After that time, the term "Middle East" gained broader usage in Europe and the United States, with the Middle East Institute founded in Washington, D. C. in 1946, among other usage. The description Middle has led to some confusion over changing definitions. Before the First World War, "Near East" was used in English to refer to the Balkans and the Ottoman Empire, while "Middle East" referred to Iran, the Caucasus, Central Asia, Turkestan. In contrast, "Far East" referred to the countries of East Asia With the disappearance of the Ottoman Empire in 1918, "Near East" fell out of common use in English, while "Middle East" came to be applied to the re-emerging countries of the Islamic world. However, the usage "Near East" was retained by a variety of academic disciplines, including archaeology and ancient history, where it describes an area identical to the term Middle East, not used by these disciplines.
The first official use of the term "Middle East" by the United States government was in the 1957 Eisenhower Doctrine, which pertained to the Suez Crisis. Secretary of State John Foster Dulles defined the Middle East as "the area lying between and including Libya on the west and Pakistan on the east and Iraq on the North and the Arabian peninsula to the south, plus the Sudan and Ethiopia." In 1958, the State Department explained that the terms "Near East" and "Middle East" were interchangeable, defined the region as including only Egypt, Israel, Jordan, Saudi Arabia, Kuwait and Qatar. The Associated Press Styleboo
Art
Art is a diverse range of human activities in creating visual, auditory or performing artifacts, expressing the author's imaginative, conceptual ideas, or technical skill, intended to be appreciated for their beauty or emotional power. In their most general form these activities include the production of works of art, the criticism of art, the study of the history of art, the aesthetic dissemination of art; the three classical branches of art are painting and architecture. Music, film and other performing arts, as well as literature and other media such as interactive media, are included in a broader definition of the arts; until the 17th century, art referred to any skill or mastery and was not differentiated from crafts or sciences. In modern usage after the 17th century, where aesthetic considerations are paramount, the fine arts are separated and distinguished from acquired skills in general, such as the decorative or applied arts. Though the definition of what constitutes art is disputed and has changed over time, general descriptions mention an idea of imaginative or technical skill stemming from human agency and creation.
The nature of art and related concepts, such as creativity and interpretation, are explored in a branch of philosophy known as aesthetics. In the perspective of the history of art, artistic works have existed for as long as humankind: from early pre-historic art to contemporary art. One early sense of the definition of art is related to the older Latin meaning, which translates to "skill" or "craft," as associated with words such as "artisan." English words derived from this meaning include artifact, artifice, medical arts, military arts. However, there are many other colloquial uses of all with some relation to its etymology. Over time, philosophers like Plato, Aristotle and Kant, among others, questioned the meaning of art. Several dialogues in Plato tackle questions about art: Socrates says that poetry is inspired by the muses, is not rational, he speaks approvingly of this, other forms of divine madness in the Phaedrus, yet in the Republic wants to outlaw Homer's great poetic art, laughter as well.
In Ion, Socrates gives no hint of the disapproval of Homer. The dialogue Ion suggests that Homer's Iliad functioned in the ancient Greek world as the Bible does today in the modern Christian world: as divinely inspired literary art that can provide moral guidance, if only it can be properly interpreted. With regards to the literary art and the musical arts, Aristotle considered epic poetry, comedy, dithyrambic poetry and music to be mimetic or imitative art, each varying in imitation by medium and manner. For example, music imitates with the media of rhythm and harmony, whereas dance imitates with rhythm alone, poetry with language; the forms differ in their object of imitation. Comedy, for instance, is a dramatic imitation of men worse than average. Lastly, the forms differ in their manner of imitation—through narrative or character, through change or no change, through drama or no drama. Aristotle believed that imitation is natural to mankind and constitutes one of mankind's advantages over animals.
The more recent and specific sense of the word art as an abbreviation for creative art or fine art emerged in the early 17th century. Fine art refers to a skill used to express the artist's creativity, or to engage the audience's aesthetic sensibilities, or to draw the audience towards consideration of more refined or finer work of art. Within this latter sense, the word art may refer to several things: a study of a creative skill, a process of using the creative skill, a product of the creative skill, or the audience's experience with the creative skill; the creative arts are a collection of disciplines which produce artworks that are compelled by a personal drive and convey a message, mood, or symbolism for the perceiver to interpret. Art is something that stimulates an individual's thoughts, beliefs, or ideas through the senses. Works of art can be explicitly made for this purpose or interpreted on the basis of images or objects. For some scholars, such as Kant, the sciences and the arts could be distinguished by taking science as representing the domain of knowledge and the arts as representing the domain of the freedom of artistic expression.
If the skill is being used in a common or practical way, people will consider it a craft instead of art. If the skill is being used in a commercial or industrial way, it may be considered commercial art instead of fine art. On the other hand and design are sometimes considered applied art; some art followers have argued that the difference between fine art and applied art has more to do with value judgments made about the art than any clear definitional difference. However fine art has goals beyond pure creativity and self-expression; the purpose of works of art may be to communicate ideas, such as in politically, spiritually, or philosophically motivated art. The purpose may be nonexistent; the nature of art has been described by philosopher Richard Wollheim as "one of the most elusive of the traditional problems of human culture". Art has been defined as a vehicle for the expression or communication of emotions and ideas, a means for exp
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. Encyclopædia Britannica. 3 (11th ed.). 1911.
