Global Positioning System
The Global Positioning System Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Air Force. It is a global navigation satellite system that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. Obstacles such as mountains and buildings block the weak GPS signals; the GPS does not require the user to transmit any data, it operates independently of any telephonic or internet reception, though these technologies can enhance the usefulness of the GPS positioning information. The GPS provides critical positioning capabilities to military and commercial users around the world; the United States government created the system, maintains it, makes it accessible to anyone with a GPS receiver. The GPS project was launched by the U. S. Department of Defense in 1973 for use by the United States military and became operational in 1995.
It was allowed for civilian use in the 1980s. Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS and implement the next generation of GPS Block IIIA satellites and Next Generation Operational Control System. Announcements from Vice President Al Gore and the White House in 1998 initiated these changes. In 2000, the U. S. Congress authorized the modernization effort, GPS III. During the 1990s, GPS quality was degraded by the United States government in a program called "Selective Availability"; the GPS system is provided by the United States government, which can selectively deny access to the system, as happened to the Indian military in 1999 during the Kargil War, or degrade the service at any time. As a result, several countries have developed or are in the process of setting up other global or regional satellite navigation systems; the Russian Global Navigation Satellite System was developed contemporaneously with GPS, but suffered from incomplete coverage of the globe until the mid-2000s.
GLONASS can be added to GPS devices, making more satellites available and enabling positions to be fixed more and to within two meters. China's BeiDou Navigation Satellite System is due to achieve global reach in 2020. There are the European Union Galileo positioning system, India's NAVIC. Japan's Quasi-Zenith Satellite System is a GPS satellite-based augmentation system to enhance GPS's accuracy; when selective availability was lifted in 2000, GPS had about a five-meter accuracy. The latest stage of accuracy enhancement uses the L5 band and is now deployed. GPS receivers released in 2018 that use the L5 band can have much higher accuracy, pinpointing to within 30 centimetres or 11.8 inches. The GPS project was launched in the United States in 1973 to overcome the limitations of previous navigation systems, integrating ideas from several predecessors, including classified engineering design studies from the 1960s; the U. S. Department of Defense developed the system, which used 24 satellites, it was developed for use by the United States military and became operational in 1995.
Civilian use was allowed from the 1980s. Roger L. Easton of the Naval Research Laboratory, Ivan A. Getting of The Aerospace Corporation, Bradford Parkinson of the Applied Physics Laboratory are credited with inventing it; the work of Gladys West is credited as instrumental in the development of computational techniques for detecting satellite positions with the precision needed for GPS. The design of GPS is based on similar ground-based radio-navigation systems, such as LORAN and the Decca Navigator, developed in the early 1940s. Friedwardt Winterberg proposed a test of general relativity – detecting time slowing in a strong gravitational field using accurate atomic clocks placed in orbit inside artificial satellites. Special and general relativity predict that the clocks on the GPS satellites would be seen by the Earth's observers to run 38 microseconds faster per day than the clocks on the Earth; the GPS calculated positions would drift into error, accumulating to 10 kilometers per day. This was corrected for in the design of GPS.
Winterberg, Friedwardt. “Relativistische Zeitdilatation eines künstlichen Satelliten ” When the Soviet Union launched the first artificial satellite in 1957, two American physicists, William Guier and George Weiffenbach, at Johns Hopkins University's Applied Physics Laboratory decided to monitor its radio transmissions. Within hours they realized that, because of the Doppler effect, they could pinpoint where the satellite was along its orbit; the Director of the APL gave them access to their UNIVAC to do the heavy calculations required. Early the next year, Frank McClure, the deputy director of the APL, asked Guier and Weiffenbach to investigate the inverse problem—pinpointing the user's location, given that of the satellite; this led them and APL to develop the TRANSIT system. In 1959, ARPA played a role in TRANSIT. TRANSIT was first tested in 1960, it used a constellation of five satellites and could provide a navigational fix once per hour. In 1967, the U. S. Navy developed the Timation satellite, which proved the feasibility of placing accurate clocks in space, a technology required for GPS.
In the 1970s, the ground-based OMEGA navigation system, based on phase comparison of signal transmission from pairs of stations
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
Culture is the social behavior and norms found in human societies. Culture is considered a central concept in anthropology, encompassing the range of phenomena that are transmitted through social learning in human societies. Cultural universals are found in all human societies; the concept of material culture covers the physical expressions of culture, such as technology and art, whereas the immaterial aspects of culture such as principles of social organization, philosophy and science comprise the intangible cultural heritage of a society. In the humanities, one sense of culture as an attribute of the individual has been the degree to which they have cultivated a particular level of sophistication in the arts, education, or manners; the level of cultural sophistication has sometimes been seen to distinguish civilizations from less complex societies. Such hierarchical perspectives on culture are found in class-based distinctions between a high culture of the social elite and a low culture, popular culture, or folk culture of the lower classes, distinguished by the stratified access to cultural capital.
In common parlance, culture is used to refer to the symbolic markers used by ethnic groups to distinguish themselves visibly from each other such as body modification, clothing or jewelry. Mass culture refers to the mass-produced and mass mediated forms of consumer culture that emerged in the 20th century; some schools of philosophy, such as Marxism and critical theory, have argued that culture is used politically as a tool of the elites to manipulate the lower classes and create a false consciousness, such perspectives are common in the discipline of cultural studies. In the wider social sciences, the theoretical perspective of cultural materialism holds that human symbolic culture arises from the material conditions of human life, as humans create the conditions for physical survival, that the basis of culture is found in evolved biological dispositions; when used as a count noun, a "culture" is the set of customs and values of a society or community, such as an ethnic group or nation. Culture is the set of knowledge acquired over time.
In this sense, multiculturalism values the peaceful coexistence and mutual respect between different cultures inhabiting the same planet. Sometimes "culture" is used to describe specific practices within a subgroup of a society, a subculture, or a counterculture. Within cultural anthropology, the ideology and analytical stance of cultural relativism holds that cultures cannot be objectively ranked or evaluated because any evaluation is situated within the value system of a given culture; the modern term "culture" is based on a term used by the Ancient Roman orator Cicero in his Tusculanae Disputationes, where he wrote of a cultivation of the soul or "cultura animi," using an agricultural metaphor for the development of a philosophical soul, understood teleologically as the highest possible ideal for human development. Samuel Pufendorf took over this metaphor in a modern context, meaning something similar, but no longer assuming that philosophy was man's natural perfection, his use, that of many writers after him, "refers to all the ways in which human beings overcome their original barbarism, through artifice, become human."In 1986, philosopher Edward S.
Casey wrote, "The word culture meant'place tilled' in Middle English, the same word goes back to Latin colere,'to inhabit, care for, worship' and cultus,'A cult a religious one.' To be cultural, to have a culture, is to inhabit a place sufficiently intensive to cultivate it—to be responsible for it, to respond to it, to attend to it caringly." Culture described by Richard Velkley:... meant the cultivation of the soul or mind, acquires most of its modern meaning in the writings of the 18th-century German thinkers, who were on various levels developing Rousseau's criticism of "modern liberalism and Enlightenment". Thus a contrast between "culture" and "civilization" is implied in these authors when not expressed as such. In the words of anthropologist E. B. Tylor, it is "that complex whole which includes knowledge, art, law and any other capabilities and habits acquired by man as a member of society." Alternatively, in a contemporary variant, "Culture is defined as a social domain that emphasizes the practices and material expressions, over time, express the continuities and discontinuities of social meaning of a life held in common.
The Cambridge English Dictionary states that culture is "the way of life the general customs and beliefs, of a particular group of people at a particular time." Terror management theory posits that culture is a series of activities and worldviews that provide humans with the basis for perceiving themselves as "person of worth within the world of meaning"—raising themselves above the physical aspects of existence, in order to deny the animal insignificance and death that Homo sapiens became aware of when they acquired a larger brain. The word is used in a general sense as the evolved ability to categorize and represent experiences with symbols and to act imaginatively and creatively; this ability arose with the evolution of behavioral modernity in humans around 50,000 years ago, is thought to be unique to humans, although some other species have demonstrated similar, though much less complex, abilities for social learning. It is used to denote the co
Jungle tourism is a subcategory of adventure travel defined by active multifaceted physical means of travel in the jungle regions of the earth. Although similar in many respects to adventure travel, jungle tourism pertains to the context of region and activity. According to the Glossary of Tourism Terms, jungle tours have become a major component of green tourism in tropical destinations and are a recent phenomenon of Western international tourism. Of the regions that take part in tourism-driven sustainable development practices and eco tourism, Mexican and South American practices are the most pervasive in the industry. Other regions include jungle territories in Africa and the South Pacific; the majority of jungle tour operators are concentrated in what is known as the Mayan World or "Ruta Maya". The Mayan World encompasses five different countries that hosted the entirety of the Mayan Civilization: Mexico, Belize, Honduras and El Salvador. Most tours consist of visits to popular Mayan archaeological sites such as Tikal, Chichen Itza, Copan.
These day visits will consist of a guided tour of a tourist-concentrated Mayan and archaeological site. Tikal and Chichen Itza are prime examples of popular day-visit sites; such sites involve a tour guide, designated either by the state government or by a private company, for the tourists. These tour guides are predominantly trained professionals, certified to take large parties of fifty through populated archaeological sites. Nicaragua and Costa Rica are popular destinations for this type of adventure travel. Although most of the visits to these more prominent sites involve day trips, there are many jungle tour operators that showcase less-known, remote Mayan jungle ruins such as Nakum, El Mirador; these tours involve much more preparation and funding to explore as they are in remote and inaccessible regions of the Mayan jungles. These ruins and sites are reached by alternative and physically taxing means of travel such as bicycle, horseback or hiking; this is what differentiates jungle tourism from any other sort of adventure travel tours.
There are several tour operators. Another difference is that the majority of tour operators that travel deep into the Central and South American jungle will cap the number of persons traveling in the group at ten to fifteen; this is done to minimize the impact on the jungle fauna. Federal laws in some countries prohibit any given group large than fifteen people traveling through the Mayan jungle, a protected region, but limited resources for enforcing such laws have allowed such practices to occur under the radar. In Guatemala it has become popular to hike through the jungle of the Mayan Biosphere due to the discovery of El Mirador known as the Lost City of Maya. There are no roads. Many take a quick flight from Flores while others hike through the jungles of the department of Petén. Groups should be smaller than 15 people in order not to reduce the impact on the environment. Ecotourism Encyclopedia of Tourism: pp. 341–342
Cycling called biking or bicycling, is the use of bicycles for transport, exercise or sport. People engaged in cycling are referred to as "cyclists", "bikers", or less as "bicyclists". Apart from two-wheeled bicycles, "cycling" includes the riding of unicycles, quadracycles and similar human-powered vehicles. Bicycles were introduced in the 19th century and now number one billion worldwide, they are the principal means of transportation in many parts of the world. Cycling is regarded as a effective and efficient mode of transportation optimal for short to moderate distances. Bicycles provide numerous benefits in comparison with motor vehicles, including the sustained physical exercise involved in cycling, easier parking, increased maneuverability, access to roads, bike paths and rural trails. Cycling offers a reduced consumption of fossil fuels, less air or noise pollution, much reduced traffic congestion; these lead to less financial cost to the user as well as to society at large. By fitting bicycle racks on the front of buses, transit agencies can increase the areas they can serve.
Among the disadvantages of cycling are the requirement of bicycles to be balanced by the rider in order to remain upright, the reduced protection in crashes in comparison to motor vehicles longer travel time, vulnerability to weather conditions, difficulty in transporting passengers, the fact that a basic level of fitness is required for cycling moderate to long distances. Cycling became an activity after bicycles were introduced in the 19th century. Today, over 50 percent of the human population knows. In many countries, the most used vehicle for road transport is a utility bicycle; these have frames with relaxed geometry, protecting the rider from shocks of the road and easing steering at low speeds. Utility bicycles tend to be equipped with accessories such as mudguards, pannier racks and lights, which extends their usefulness on a daily basis; as the bicycle is so effective as a means of transportation various companies have developed methods of carrying anything from the weekly shop to children on bicycles.
Certain countries rely on bicycles and their culture has developed around the bicycle as a primary form of transport. In Europe and the Netherlands have the most bicycles per capita and most use bicycles for everyday transport. Road bikes tend to have a more upright shape and a shorter wheelbase, which make the bike more mobile but harder to ride slowly; the design, coupled with low or dropped handlebars, requires the rider to bend forward more, making use of stronger muscles and reducing air resistance at high speed. The price of a new bicycle can range from US$50 to more than US$20,000, depending on quality and weight. However, UCI regulations stipulate. Being measured for a bike and taking it for a test ride are recommended before buying; the drivetrain components of the bike should be considered. A middle grade dérailleur is sufficient for a beginner, although many utility bikes are equipped with hub gears. If the rider plans a significant amount of hillclimbing, a triple-chainrings crankset gear system may be preferred.
Otherwise, the lighter and less expensive double chainring may be better. Much simpler fixed wheel bikes are available. Many road bikes, along with mountain bikes, include clipless pedals to which special shoes attach, via a cleat, enabling the rider to pull on the pedals as well as push. Other possible accessories for the bicycle include front and rear lights, bells or horns, child carrying seats, cycling computers with GPS, bar tape, baggage racks, baggage carriers and pannier bags, water bottles and bottle cages. For basic maintenance and repairs cyclists can carry a pump, a puncture repair kit, a spare inner tube, tire levers and a set of allen keys. Cycling can be more efficient and comfortable with special shoes and shorts. In wet weather, riding can be more tolerable with waterproof clothes, such as cape, jacket and overshoes and high-visibility clothing is advisable to reduce the risk from motor vehicle users. Items required in some jurisdictions, or voluntarily adopted for safety reasons, include bicycle helmets, generator or battery operated lights and audible signalling devices such as a bell or horn.
Extras include a bicycle computer. Bikes can be customized, with different seat designs and handle bars, for example. Many schools and police departments run educational programs to instruct children in bicycle handling skills and introduce them to the rules of the road as they apply to cyclists. In different countries these may be known as bicycle rodeos or operated as schemes such as Bikeability. Education for adult cyclists is available from organizations such as the League of American Bicyclists. Beyond riding, another skill is riding efficiently and safely in traffic. One popular approach to riding in motor vehicle traffic is vehicular cycling, occupying road space as car does. Alternately, in countries such as Denmark and the Netherlands, where cycling is popular, cyclists are segregated into bike lanes at the side of, or more separate from, main highways and roads. Many primary schools participate in the national road test in whi
Paragliding is the recreational and competitive adventure sport of flying paragliders: lightweight, free-flying, foot-launched glider aircraft with no rigid primary structure. The pilot sits in a harness suspended below a fabric wing. Wing shape is maintained by the suspension lines, the pressure of air entering vents in the front of the wing, the aerodynamic forces of the air flowing over the outside. Despite not using an engine, paraglider flights can last many hours and cover many hundreds of kilometres, though flights of one to two hours and covering some tens of kilometres are more the norm. By skillful exploitation of sources of lift, the pilot may gain height climbing to altitudes of a few thousand metres. In 1952 Canadian Domina Jalbert patented a governable gliding parachute with multi-cells and controls for lateral glide. In 1954, Walter Neumark predicted a time when a glider pilot would be "able to launch himself by running over the edge of a cliff or down a slope... whether on a rock-climbing holiday in Skye or ski-ing in the Alps."In 1961, the French engineer Pierre Lemongine produced improved parachute designs that led to the Para-Commander.
The PC had cutouts at the rear and sides that enabled it to be towed into the air and steered, leading to parasailing/parascending. Domina Jalbert invented the Parafoil, he filed US Patent 3131894 on January 10, 1963. About that time, David Barish was developing the "sail wing" for recovery of NASA space capsules – "slope soaring was a way of testing out... the Sail Wing." After tests on Hunter Mountain, New York, in September 1965, he went on to promote slope soaring as a summer activity for ski resorts. Author Walter Neumark wrote Operating Procedures for Ascending Parachutes, in 1973 he and a group of enthusiasts with a passion for tow-launching PCs and ram-air parachutes broke away from the British Parachute Association to form the British Association of Parascending Clubs. In 1997, Neumark was awarded the Gold Medal of the Royal Aero Club of the UK. Authors Patrick Gilligan and Bertrand Dubuis wrote the first flight manual, The Paragliding Manual in 1985, coining the word paragliding; these developments were combined in June 1978 by three friends, Jean-Claude Bétemps, André Bohn and Gérard Bosson, from Mieussy, Haute-Savoie, France.
After inspiration from an article on slope soaring in the Parachute Manual magazine by parachutist and publisher Dan Poynter, they calculated that on a suitable slope, a "square" ram-air parachute could be inflated by running down the slope. Bohn glided down to the football pitch in the valley 1000 metres below. "Parapente" was born. From the 1980s, equipment has continued to improve, the number of paragliding pilots and established sites has continued to increase; the first Paragliding World Championship was held in Verbier, Switzerland, in 1987, though the first sanctioned FAI World Paragliding Championship was held in Kössen, Austria, in 1989. Europe has seen the greatest growth in paragliding, with France alone registering in 2011 over 25,000 active pilots; the paraglider wing or canopy is what is known in engineering as a "ram-air airfoil". Such wings comprise two layers of fabric that are connected to internal supporting material in such a way as to form a row of cells. By leaving most of the cells open only at the leading edge, incoming air keeps the wing inflated, thus maintaining its shape.
When inflated, the wing's cross-section has the typical teardrop aerofoil shape. Modern paraglider wings are made of high-performance non-porous materials such as ripstop polyester or nylon fabric. In some modern paragliders higher-performance wings, some of the cells of the leading edge are closed to form a cleaner aerodynamic profile. Holes in the internal ribs allow a free flow of air from the open cells to these closed cells to inflate them, to the wingtips, which are closed; the pilot is supported underneath the wing by a network of suspension lines. These start with two sets of risers made of short lengths of strong webbing; each set is attached to the harness by a carabiner, one on each side of the pilot, each riser of a set is attached to lines from only one row of its side of wing. At the end of each riser of the set, there is a small delta maillon with a number of lines attached, forming a fan; these are 4 – 5 metres long, with the end attached to 2 − 4 further lines of around 2 m, which are again joined to a group of smaller, thinner lines.
In some cases this is repeated for a fourth cascade. The top of each line is attached to small fabric loops sewn into the structure of the wing, which are arranged in rows running span-wise; the row of lines nearest the front are known as the A lines, the next row back the B lines, so on. A typical wing will have A, B, C and D lines, but there has been a tendency to reduce the rows of lines to three, or two, to reduce drag. Paraglider lines are made from Dyneema/Spectra or Kevlar/Aramid. Although they look rather slender, these materials are immensely strong. For example, a single 0.66 mm-diameter line can have a breaking strength of 56 kg. Paraglider wings have an area of 20–35 square metres with a span of 8–12 metres and weigh 3–7 kilograms