Human-powered transport is the transport of person and/or goods using human muscle power. Like animal-powered transport, human-powered transport has existed since time immemorial in the form of walking and swimming. Modern technology has allowed machines to enhance human-power. Although motorization has increased speed and load capacity, many forms of human-powered transport remain popular for reasons of lower cost, physical exercise and environmentalism. Human-powered transport is sometimes the only type available in underdeveloped or inaccessible regions. In the 1989 Race Across America, one team used an experimental device comprising a rear wheel hub, a sensor, a handlebar mounted processor, to measure each cyclist's power output. In lab experiments an average "in-shape" cyclist can produce about 3 watts/kg for more than an hour, with top amateurs producing 5 watts/kg and elite athletes achieving 6 watts/kg for similar lengths of time. Elite track sprint cyclists are able to attain an instantaneous maximum output of around 2,000 watts, or in excess of 25 watts/kg.
Crawling Walking Running Sprinting Swimming Climbing and mountaineering Ice skating, roller skating, inline skating Cross-country skiing Skateboards have the advantage of being so small and light that users can carry them when not skating. The most efficient human-powered land vehicle is the bicycle. Compared to the much more common upright bicycle, the recumbent bicycle may be faster on level ground or down hills due to better aerodynamics while having similar power transfer efficiency. Velomobiles are popular in colder and/or wetter countries due to the protection they offer against the environment. Freight bicycles are used to transport cargo. Cycle rickshaws can be used as taxicabs. In 2016, AeroVelo cyclist Todd Reichert achieved the human-powered speed record of 142.04 km/h with a velomobile at Battle Mountain, Nevada. Dutch cyclist Fred Rompelberg set a 268.8 km/h speed record at the Bonneville Salt Flats in Utah on October 3, 1995 while cycling in the wake of a motor dragster pace-car.
The wake of the pace-car reduced the aerodynamic drag against which Rompelberg pedalled to zero. Greg Kolodziejzyk set two world records recognized by both the International Human Powered Vehicle Association and Guinness World Records on July 17, 2006 on a race track in Eureka, California; the first record is for the most distance traveled in 24 hours by human power 1,041 km, the second for the worlds fastest 1,000 km time trial. Both records were broken on August 6, 2010 by Christian von Ascheberg who drove 1,000 km in 19 hours, 27 minutes and managed to go 1,219 km in 24 hours with his Milan SL Velomobile. In the same race he raised the 12-hour record to 664.97 km, an average of 55.41 km/h. In 1969, artists in a small Northern California town began the Kinetic sculpture race which has grown to a 42 mi, three-day all terrain, human-powered sculpture race and county wide event, it is held every year on the last weekend in May. The Pedaliante flew short distances under human power in 1936, but the distances were not significant enough to win the prize of the Italian competition for which it was built.
The flights were deemed to be a result of the pilot's significant strength and endurance, not attainable by a typical human. Additional attempts were made in 1937 and 1938 using a catapult system, launching the plane to a height of 9 m. With the catapult launch, the plane traveled the 1 km distance outlined by the competition, but was declined the prize due to the takeoff method; the first authenticated feasible take-off and landing of a human-powered aircraft was made on 9 November 1961 by Derek Piggott in Southampton University's Man Powered Aircraft. The best-known human-powered plane is the Gossamer Albatross, which flew across the English Channel in 1979; the current distance and duration record recognised by the FAI, a straight distance of 115.11 km in 3 hours and 54 minutes, was achieved on 23 April 1988 from Heraklion on Crete to Santorini in a MIT Daedalus 88 piloted by Kanellos Kanellopoulos. The current speed record is held by the Monarch B, built by a team at MIT in 1983, which won a Kremer Prize of £20,000 for sustaining a speed of over 30 km/h over a 1.5 km triangular course.
The first observed human-powered helicopter to have left the ground was the Da Vinci III in 1989. It was designed and built by students at Cal Poly San Luis Obispo in California, USA, it reached a height of 8 in. The second was the Yuri I in 1994, built by students at Nihon University in Japan, it reached an altitude of 20 cm. On 13 June 2013, the AeroVelo Atlas was the first to complete a flight that lasted 64 seconds and reached an altitude of 3.3 meters, thus winning the Sikorsky Prize. French inventors have built man-powered balloons. Solar balloons and solar airships are new types of airships; because lift is supplied through buoyancy, human power can be devoted to thrust. Human-powered watercraft include prehistoric and well-known traditional and sporting craft such as canoes, rowing boats and galleys; the term human-powered boat is used for more modern craft using propellers and wat
Total internal reflection
Total internal reflection is the phenomenon that makes the water-to-air surface in a fish-tank look like a silvered mirror when viewed from below the water level. Technically, TIR is the total reflection of a wave incident at a sufficiently oblique angle on the interface between two media, of which the second medium is transparent to such waves but has a higher wave velocity than the first medium. TIR occurs not only with electromagnetic waves such as light waves and microwaves, but with other types of waves, including sound and water waves. In the case of a narrow train of waves, such as a laser beam, we tend to speak of the total internal reflection of a "ray". Refraction is accompanied by partial reflection; when a wavetrain is refracted from a medium of lower propagation speed to a medium of higher propagation speed, the angle of refraction is greater than the angle of incidence. Hence, as the angle of incidence approaches a certain limit, called the critical angle, the angle of refraction approaches 90°, at which the refracted ray becomes tangential to the interface.
As the angle of incidence increases beyond the critical angle, the conditions of refraction can no longer be satisfied. In an isotropic medium such as air, water, or glass, the ray direction is the direction normal to the wavefront. If the internal and external media are isotropic with refractive indices n1 and n2 the critical angle is given by θ c = arcsin , is defined if n2 ≤ n1. For example, for visible light, the critical angle is about 49° for incidence from water to air, about 42° for incidence from common glass to air. Details of the mechanism of TIR give rise to more subtle phenomena. Unlike partial reflection between transparent media, total internal reflection is accompanied by a non-trivial phase shift for each component of polarization, the shifts vary with the angle of incidence. While total reflection, by definition, involves no continuing transfer of power across the interface, the external medium carries a so-called evanescent wave, which travels along the interface with an amplitude that falls off exponentially with distance from the interface.
The "total" reflection is indeed total if the external medium is lossless, of infinite extent, but can be conspicuously less than total if the evanescent wave is absorbed by a lossy external medium, or diverted by the outer boundary of the external medium or by objects embedded in that medium. The phase shifts in TIR are utilized by a polarization-modifying device called the Fresnel rhomb; the efficiency of the reflection is exploited by optical fibers, by reflective prisms, such as erecting prisms for binoculars. Although total internal reflection can occur with any kind of wave that can be said to have oblique incidence, including microwaves and sound waves, it is most familiar in the case of light waves. Total internal reflection of light can be demonstrated using a semicircular-cylindrical block of common glass or acrylic glass. In Fig. 3, a "ray box" projects a narrow beam of light radially inward. The semicircular cross-section of the glass allows the incoming ray to remain perpendicular to the curved portion of the air/glass surface, thence to continue in a straight line towards the flat part of the surface, although its angle with the flat part varies.
Where the ray meets the flat glass-to-air interface, the angle between the ray and the normal to the interface is called the angle of incidence. If this angle is sufficiently small, the ray is reflected but transmitted, the transmitted portion is refracted away from the normal, so that the angle of refraction is greater than the angle of incidence. For the moment, let us call the angle of incidence θi and the angle of refraction θt; as θi increases and approaches a certain "critical angle", denoted by θc, the angle of refraction approaches 90°, the refracted ray becomes fainter while the reflected ray becomes brighter. As θi increases beyond θc, the refracted ray disappears and only the reflected ray remains, so that all of the energy of the incident ray is reflected. In brief: If θi < θc, the incident ray is split, being reflected and refracted. The critical angle is the smallest angle of incidence. For light waves and other electromagnetic waves in isotropic media, there is a well-known formula for the critical angle in terms of the refractive indices.
For some other types of waves, it is more convenient to think in terms of propagation velocities rather than refractive indices. The latter approach is more direct and more general, will therefore be discussed first; when a wavefront is refracted from one medium to another, the incident and refracted portions of the wavefront meet at a common line on the
A vehicle is a machine that transports people or cargo. Vehicles include wagons, motor vehicles, railed vehicles, amphibious vehicles and spacecraft. Land vehicles are classified broadly by what is used to apply steering and drive forces against the ground: wheeled, railed or skied. ISO 3833-1977 is the standard internationally used in legislation, for road vehicles types and definitions; the oldest boats found by archaeological excavation are logboats, with the oldest logboat found, the Pesse canoe found in a bog in the Netherlands, being carbon dated to 8040 - 7510 BC, making it 9,500–10,000 years old, a 7,000-year-old seagoing boat made from reeds and tar has been found in Kuwait. Boats were used in the Indian Ocean. There is evidence of camel pulled wheeled vehicles about 4000–3000 BC; the earliest evidence of a wagonway, a predecessor of the railway, found so far was the 6 to 8.5 km long Diolkos wagonway, which transported boats across the Isthmus of Corinth in Greece since around 600 BC.
Wheeled vehicles pulled by men and animals ran in grooves in limestone, which provided the track element, preventing the wagons from leaving the intended route. In 200 CE, Ma Jun built a vehicle with an early form of guidance system. Railways began reappearing in Europe after the Dark Ages; the earliest known record of a railway in Europe from this period is a stained-glass window in the Minster of Freiburg im Breisgau dating from around 1350. In 1515, Cardinal Matthäus Lang wrote a description of the Reisszug, a funicular railway at the Hohensalzburg Fortress in Austria; the line used wooden rails and a hemp haulage rope and was operated by human or animal power, through a treadwheel. 1769 Nicolas-Joseph Cugnot is credited with building the first self-propelled mechanical vehicle or automobile in 1769. In Russia, in the 1780s, Ivan Kulibin developed a human-pedalled, three-wheeled carriage with modern features such as a flywheel, gear box and bearings. 1783 Montgolfier brothers first balloon vehicle 1801 Richard Trevithick built and demonstrated his Puffing Devil road locomotive, which many believe was the first demonstration of a steam-powered road vehicle, though it could not maintain sufficient steam pressure for long periods and was of little practical use.
1817 Push bikes, draisines or hobby horses were the first human means of transport to make use of the two-wheeler principle, the draisine, invented by the German Baron Karl von Drais, is regarded as the forerunner of the modern bicycle. It was introduced by Drais to the public in Mannheim in summer 1817. 1885 Karl Benz built the first automobile, powered by his own four-stroke cycle gasoline engine in Mannheim, Germany 1885 Otto Lilienthal began experimental gliding and achieved the first sustained, reproducible flights. 1903 Wright brothers flew the first controlled, powered aircraft 1907 First helicopters Gyroplane no.1 and Cornu helicopter 1928 Opel RAK.1 rocket car 1929 Opel RAK.1 rocket glider 1961 Vostok vehicle carried the first human, Yuri Gagarin, into space 1969 Apollo Program first manned vehicle landed on the moon 2010 The number of road motor vehicles in operation worldwide surpassed the 1 billion mark – one for every seven people. There are over 1 billion bicycles in use worldwide.
In 2002 there were an estimated 590 million cars and 205 million motorcycles in service in the world. At least 500 million Chinese Flying Pigeon bicycles have been made, more than any other single model of vehicle; the most-produced model of motor vehicle is the Honda Super Cub motorcycle, having passed 60 million units in 2008. The most-produced car model is the Toyota Corolla, with at least 35 million made by 2010; the most common fixed-wing airplane is the Cessna 172, with about 44,000 having been made as of 2017. The Soviet Mil Mi-8, at 17,000, is the most-produced helicopter; the top commercial jet airliner is the Boeing 737, at about 10,000 in 2018. Locomotion consists of a means that allows displacement with little opposition, a power source to provide the required kinetic energy and a means to control the motion, such as a brake and steering system. By far, most vehicles use wheels which employ the principle of rolling to enable displacement with little rolling friction, it is essential.
Energy can be extracted from external sources, as in the cases of a sailboat, a solar-powered car, or an electric streetcar that uses overhead lines. Energy can be stored, provided it can be converted on demand and the storing medium's energy density and power density are sufficient to meet the vehicle's needs. Human power is a simple source of energy. Despite the fact that humans cannot exceed 500 W for meaningful amounts of time, the land speed record for human-powered vehicles is 133 km/h, as of 2009 on a recumbent bicycle; the most common type of energy source is fuel. External combustion engines can use anything that burns as fuel, whilst internal combustion engines and rocket engines are designed to burn a specific fuel gasoline, diesel or ethanol. Another common medium for storing energy is batteries, which have the advantages of being responsive, useful in a wide range of power levels, environmentally friendly, simple to install, easy to maintain. Batteries facilitate the use of electric motors, which have thei
Clothing is a collective term for items worn on the body. Clothing can be made of animal skin, or other thin sheets of materials put together; the wearing of clothing is restricted to human beings and is a feature of all human societies. The amount and type of clothing worn depend on body type and geographic considerations; some clothing can be gender-specific. Physically, clothing serves many purposes: it can serve as protection from the elements and can enhance safety during hazardous activities such as hiking and cooking, it protects the wearer from rough surfaces, rash-causing plants, insect bites, splinters and prickles by providing a barrier between the skin and the environment. Clothes can insulate against cold or hot conditions, they can provide a hygienic barrier, keeping infectious and toxic materials away from the body. Clothing provides protection from ultraviolet radiation. Wearing clothes is a social norm, being deprived of clothing in front of others may be embarrassing, or not wearing clothes in public such that genitals, breasts or buttocks are visible could be seen as indecent exposure.
There is no easy way to determine when clothing was first developed, but some information has been inferred by studying lice which estimates the introduction of clothing at 42,000–72,000 years ago. The most obvious function of clothing is to improve the comfort of the wearer, by protecting the wearer from the elements. In hot climates, clothing provides protection from sunburn or wind damage, while in cold climates its thermal insulation properties are more important. Shelter reduces the functional need for clothing. For example, hats and other outer layers are removed when entering a warm home if one is living or sleeping there. Clothing has seasonal and regional aspects, so that thinner materials and fewer layers of clothing are worn in warmer regions and seasons than in colder ones. Clothing performs a range of social and cultural functions, such as individual and gender differentiation, social status. In many societies, norms about clothing reflect standards of modesty, religion and social status.
Clothing may function as a form of adornment and an expression of personal taste or style. Clothing can be and has in the past been made from a wide variety of materials. Materials have ranged from leather and furs to woven materials, to elaborate and exotic natural and synthetic fabrics. Not all body coverings are regarded as clothing. Articles carried rather than worn, worn on a single part of the body and removed, worn purely for adornment, or those that serve a function other than protection, are considered accessories rather than clothing, except for shoes. Clothing protects against many things. Clothes protect people from the elements, including rain, snow and other weather, as well as from the sun. However, clothing, too sheer, small, etc. offers less protection. Appropriate clothes can reduce risk during activities such as work or sport; some clothing protects from specific hazards, such as insects, noxious chemicals, weather and contact with abrasive substances. Conversely, clothing may protect the environment from the clothing wearer: for instance doctors wear medical scrubs.
Humans have been ingenious in devising clothing solutions to environmental or other hazards: such as space suits, air conditioned clothing, diving suits, bee-keeper gear, motorcycle leathers, high-visibility clothing, other pieces of protective clothing. Meanwhile, the distinction between clothing and protective equipment is not always clear-cut, since clothes designed to be fashionable have protective value and clothes designed for function consider fashion in their design; the choice of clothes has social implications. They cover parts of the body that social norms require to be covered, act as a form of adornment, serve other social purposes. Someone who lacks the means to procure reasonable clothing due to poverty or affordability, or lack of inclination, is sometimes said to be scruffy, ragged, or shabby. Serious books on clothing and its functions appear from the 19th century as imperialists dealt with new environments such as India and the tropics; some scientific research into the multiple functions of clothing in the first half of the 20th century, with publications such as J.
C. Flügel's Psychology of Clothes in 1930, Newburgh's seminal Physiology of Heat Regulation and The Science of Clothing in 1949. By 1968, the field of environmental physiology had advanced and expanded but the science of clothing in relation to environmental physiology had changed little. There has since been considerable research, the knowledge base has grown but the main concepts remain unchanged, indeed Newburgh's book is still cited by contemporary authors, including those attempting to develop thermoregulatory models of clothing development. In most cultures, gender differentiation of clothing is considered appropriate; the differences are in styles and fabrics. In Western societies, skirts and high-heeled shoes are seen as women's clothing, while neckties are seen as men's clothing. Trousers were once seen as male clothing, but can nowadays be worn by both genders. Male clothes are more practical, but a wider range of clothing styles are available for females. Males are allowed to bare their chests in a greater variety of public places.
A retroreflector is a device or surface that reflects radiation back to its source with a minimum of scattering. In a retroreflector the wavefront of the radiation is reflected straight back to the wave's source; this works at a wide range of angle of incidence, unlike a planar mirror, which does this only if the mirror is perpendicular to the wave front, having a zero angle of incidence. Being directed, the retroflector's reflection is brighter than that of a diffuse reflector. Corner reflectors and cat eye reflectors are the most used kinds. There are several ways to obtain retroreflection: A set of three mutually perpendicular reflective surfaces, placed to form the corner of a cube, work as a retroreflector; the three corresponding normal vectors of the corner's sides form a basis in which to represent the direction of an arbitrary incoming ray. When the ray reflects from the first side, say x, the ray's x-component, a, is reversed to −a, while the y- and z-components are unchanged. Therefore, as the ray reflects first from side x side y and from side z the ray direction goes from to to to and it leaves the corner with all three components of its direction reversed.
Corner reflectors occur in two varieties. In the more common form, the corner is the truncated corner of a cube of transparent material such as conventional optical glass. In this structure, the reflection is achieved either by total internal reflection or silvering of the outer cube surfaces; the second form uses mutually perpendicular flat mirrors bracketing an air space. These two types have similar optical properties. A large thin retroreflector can be formed by combining many small corner reflectors, using the standard hexagonal tiling. Another common type of retroreflector consists of refracting optical elements with a reflective surface, arranged so that the focal surface of the refractive element coincides with the reflective surface a transparent sphere and a spherical mirror. In the paraxial approximation, this effect can be achieved with lowest divergence with a single transparent sphere when the refractive index of the material is one plus the refractive index ni of the medium from which the radiation is incident.
In that case, the sphere surface behaves as a concave spherical mirror with the required curvature for retroreflection. In practice, the optimal index of refraction may be lower than ni + 1 ≅ 2 due to several factors. For one, it is sometimes preferable to have an imperfect divergent retroreflection, as in the case of road signs, where the illumination and observation angles are different. Due to spherical aberration, there exists a radius from the centerline at which incident rays are focused at the center of the rear surface of the sphere. High index materials have higher Fresnel reflection coefficients, so the efficiency of coupling of the light from the ambient into the sphere decreases as the index becomes higher. Commercial retroreflective beads thus vary in index from around 1.5 up to around 1.9. The spherical aberration problem with the spherical cat's eye can be solved in various ways, one being a spherically symmetrical index gradient within the sphere, such as in the Luneburg lens design.
This can be approximated by a concentric sphere system. Because the back-side reflection for an uncoated sphere is imperfect, it is common to add a metallic coating to the back half of retroreflective spheres to increase the reflectance, but this implies that the retroreflection only works when the sphere is oriented in a particular direction. An alternative form of the cat's eye retroreflector uses a normal lens focused onto a curved mirror rather than a transparent sphere, though this type is much more limited in the range of incident angles that it retroreflects; the term cat's eye derives from the resemblance of the cat's eye retroreflector to the optical system that produces the well-known phenomenon of "glowing eyes" or eyeshine in cats and other vertebrates. The combination of the eye's lens and the cornea form the refractive converging system, while the tapetum lucidum behind the retina forms the spherical concave mirror; because the function of the eye is to form an image on the retina, an eye focused on a distant object has a focal surface that follows the reflective tapetum lucidum structure, the condition required to form a good retroreflection.
This type of retroreflector can consist of many small versions of these structures incorporated in a thin sheet or in paint. In the case of paint containing glass beads, the paint adheres the beads to the surface where retroreflection is required and the beads protrude, their diameter being about twice the thickness of the paint. A third, much less common way of producing a retroreflector is to use the nonlinear optical phenomenon of phase conjugation; this technique is used in advanced optical systems such as high-power lasers and optical transmission lines. Phase-conjugate mirrors require a comparatively expensive and complex apparatus, as well as large quantities of power. However, phase-conjugate mirrors have an inherently much greater accuracy in the direction of the retroreflection, which in passive elements is limited by the mechanical accuracy of the construction. Retroreflectors are devices that operate by returning light back to the light source along the same light direction; the coefficient of luminous intensity, RI, is the measure of a r
A street light, light pole, street lamp, light standard, or lamp standard is a raised source of light on the edge of a road or path. When urban electric power distribution became ubiquitous in developed countries in the 20th century, lights for urban streets followed, or sometimes led. Many lamps have light-sensitive photocells that activate automatically when light is or is not needed: dusk, dawn, or the onset of dark weather; this function in older lighting systems could have been performed with the aid of a solar dial. Many street light systems are being connected underground instead of wiring from one utility post to another. Early lamps were used by Greek and Roman civilizations, where light served the purpose of security, both to protect the wanderer from tripping on the path over something or keeping the potential robbers at bay. At that time oil lamps were used predominantly as they provided a moderate flame; the Romans had a word'laternarius', a term for a slave responsible for lighting the oil lamps in front of their villas.
The use of street lighting was first recorded in the city of Antioch from the 4th century. It was recorded in the Caliphate of Córdoba from the 9th–10th centuries in Cordova. In the Middle Ages, so-called "link boys" escorted people from one place to another through the murky winding streets of medieval towns. Before incandescent lamps, candle lighting was employed in cities; the earliest lamps required that a lamplighter tour the town at dusk. According to some sources, illumination was ordered in London in 1417 by Sir Henry Barton, Mayor of London though there is no firm evidence of this. In 1524, Paris house owners were required to have lanterns with candles lit in front of their houses at night, but the law was ignored. Following the invention of lanterns with glass windows, which improved the quantity of light, in 1594 the police of Paris took charge of installing lanterns in each city neighborhood. Still, in 1662, it was a common practice for travelers to hire a lantern-bearer if they had to move at night through the dark, winding streets.
Lantern bearers were still common in Paris until 1789. In 1667, under King Louis XIV, the royal government began installing lanterns on all the streets. There were three thousand in place by 1669, twice as many by 1729. Lanterns with glass windows were suspended from a cord over the middle of the street at a height of twenty feet and were placed twenty yards apart. A much-improved oil lantern, called a réverbère, was introduced between 1745 and 1749; these lamps were attached to the top of lampposts. During the French Revolution, the revolutionaries found that the lampposts were a convenient place to hang aristocrats and other opponents; the first widespread system of street lighting used piped coal gas as fuel. Stephen Hales was the first person who procured a flammable fluid from the actual distillation of coal in 1726 and John Clayton, in 1735, called gas the "spirit" of coal and discovered its flammability by accident. William Murdoch was the first to use this gas for the practical application of lighting.
In the early 1790s, while overseeing the use of his company's steam engines in tin mining in Cornwall, Murdoch began experimenting with various types of gas settling on coal-gas as the most effective. He first lit his own house in Redruth, Cornwall in 1792. In 1798, he used gas to light the main building of the Soho Foundry and in 1802 lit the outside in a public display of gas lighting, the lights astonishing the local population. In Paris, gas lighting was first demonstrated in November 1800 at a private residence on the rue Saint-Dominique, was installed on a covered shopping street, the Passage des Panoramas, in 1817; the First gas lamps on the streets of Paris appeared in January 1829 on the place du Carrousel and the rue de Rivoli on rue de la Paix, place Vendôme, rue de Castiglione. A Parisian writer enthused in August, 1857: "That which most enchants the Parisians is the new lighting by gas of the boulevards... From the church of the Madeleine all the way to rue Montmartre, these two rows of lamps, shining with a clarity white and pure, have a marvelous effect."
The gaslights installed on the boulevards and city monuments in the 19th century gave the city the nickname "The City of Light." The first public street lighting with gas was demonstrated in Pall Mall, London on 28 January 1807 by Frederick Albert Winsor. In 1812, Parliament granted a charter to the London and Westminster Gas Light and Coke Company, the first gas company in the world came into being. Less than two years on 31 December 1813, the Westminster Bridge was lit by gas. Following this success, gas lighting spread to other countries; the use of gas lights in Rembrandt Peale's Museum in Baltimore in 1816 was a great success. Baltimore was the first American city with gas streetlights, provided by Peale's Gas Light Company of Baltimore; the first place outside London in England to have gas lighting, was Preston, Lancashire in 1816, this was due to the Preston Gaslight Company run by revolutionary Joseph Dunn, who found the most improved way of brighter gas lighting. Oil-gas appeared in the field as a rival of coal-gas.
In 1815, John Taylor patented an apparatus for the decomposition of "oil" and other animal substances. Public attention was attracted to "oil-gas" by the display of the patent apparatus at Apothecary's Hall, by Taylor & Martineau; the first modern street lamps to use kerosene were introduced in Lviv in what was the Austrian Empire in 1853. In Brest, street lighting with kerosene lamps reappeared in 2009 in the shoppi
Running is a method of terrestrial locomotion allowing humans and other animals to move on foot. Running is a type of gait characterized by an aerial phase; this is in contrast to walking, where one foot is always in contact with the ground, the legs are kept straight and the center of gravity vaults over the stance leg or legs in an inverted pendulum fashion. A characteristic feature of a running body from the viewpoint of spring-mass mechanics is that changes in kinetic and potential energy within a stride occur with energy storage accomplished by springy tendons and passive muscle elasticity; the term running can refer to any of a variety of speeds ranging from jogging to sprinting. It is assumed that the ancestors of humankind developed the ability to run for long distances about 2.6 million years ago in order to hunt animals. Competitive running grew out of religious festivals in various areas. Records of competitive racing date back to the Tailteann Games in Ireland between 632 BCE and 1171 BCE, while the first recorded Olympic Games took place in 776 BCE.
Running has been described as the world's most accessible sport. It is thought that human running evolved at least four and a half million years ago out of the ability of the ape-like Australopithecus, an early ancestor of humans, to walk upright on two legs; the theory proposed considered to be the most evolution of running is of early humans' developing as endurance runners from the practice of persistence hunting of animals, the activity of following and chasing until a prey is too exhausted to flee, succumbing to "chase myopathy", that human features such as the nuchal ligament, abundant sweat glands, the Achilles tendons, big knee joints and muscular glutei maximi, were changes caused by this type of activity. The theory as first proposed used comparative physiological evidence and the natural habits of animals when running, indicating the likelihood of this activity as a successful hunting method. Further evidence from observation of modern-day hunting practice indicated this likelihood.
According to Sears scientific investigation of the Nariokotome Skeleton provided further evidence for the Carrier theory. Competitive running grew out of religious festivals in various areas such as Greece, Egypt and the East African Rift in Africa; the Tailteann Games, an Irish sporting festival in honor of the goddess Tailtiu, dates back to 1829 BCE, is one of the earliest records of competitive running. The origins of the Olympics and Marathon running are shrouded by myth and legend, though the first recorded games took place in 776 BCE. Running in Ancient Greece can be traced back to these games of 776 BCE.... I suspect that the sun, earth and heaven, which are still the gods of many barbarians, were the only gods known to the aboriginal Hellenes. Seeing that they were always moving and running, from their running nature they were called gods or runners... Running gait can be divided into two phases in regard to the lower extremity: stance and swing; these can be further divided into absorption, initial swing and terminal swing.
Due to the continuous nature of running gait, no certain point is assumed to be the beginning. However, for simplicity, it will be assumed that absorption and footstrike mark the beginning of the running cycle in a body in motion. Footstrike occurs. Common footstrike types include forefoot and heel strike types; these are characterized by initial contact of the ball of the foot and heel of the foot and heel of the foot respectively. During this time the hip joint is undergoing extension from being in maximal flexion from the previous swing phase. For proper force absorption, the knee joint should be flexed upon footstrike and the ankle should be in front of the body. Footstrike begins the absorption phase as forces from initial contact are attenuated throughout the lower extremity. Absorption of forces continues as the body moves from footstrike to midstance due to vertical propulsion from the toe-off during a previous gait cycle. Midstance is defined as the time at which the lower extremity limb of focus is in knee flexion directly underneath the trunk and hips.
It is at this point that propulsion begins to occur as the hips undergo hip extension, the knee joint undergoes extension and the ankle undergoes plantar flexion. Propulsion continues until the leg is extended behind the body and toe off occurs; this involves maximal hip extension, knee extension and plantar flexion for the subject, resulting in the body being pushed forward from this motion and the ankle/foot leaves the ground as initial swing begins. Most recent research regarding the footstrike debate, has focused on the absorption phases for injury identification and prevention purposes; the propulsion phase of running involves the movement beginning at midstance until toe off. From a full stride length model however, components of the terminal swing and footstrike can aid in propulsion. Set up for propulsion begins at the end of terminal swing as the hip joint flexes, creating the maximal range of motion for the hip extensors to accelerate through and produce force; as the hip extensors change from reciporatory inhibitors to primary muscle movers, the lower extremity is brought back toward the ground, although aided by the stretch reflex and gravity.
Footstrike and absorption phases occur next with two types of outcomes. This phase can be only a continuation of momentum from the stretch reflex reaction to