Construction is the process of constructing a building or infrastructure. Construction as an industry comprises six to nine percent of the domestic product of developed countries. Construction starts with planning and financing, and continues until the project is built, large-scale construction requires collaboration across multiple disciplines. An architect normally manages the job, and a manager, design engineer. For the successful execution of a project, effective planning is essential, the largest construction projects are referred to as megaprojects. Construction is a term meaning the art and science to form objects, systems, or organizations. Construction is used as a verb, the act of building, and a noun, how a building was built, in general, there are three sectors of construction, buildings and industrial. Building construction is further divided into residential and non-residential. Infrastructure is often called heavy/highway, heavy civil or heavy engineering and it includes large public works, bridges, water/wastewater and utility distribution.
Industrial includes refineries, process chemical, power generation, there are other ways to break the industry into sectors or markets. Engineering News-Record is a magazine for the construction industry. Each year, ENR compiles and reports on data about the size of design and they publish a list of the largest companies in the United States and a list the largest global firms. In 2014, ENR compiled the data in nine market segments and it was divided as transportation, buildings, industrial, manufacturing, sewer/waste, hazardous waste plus a tenth category for other projects. In their reporting on the Top 400, they used data on transportation, hazardous waste, the Standard Industrial Classification and the newer North American Industry Classification System have a classification system for companies that perform or otherwise engage in construction. To recognize the differences of companies in this sector, it is divided into three subsectors, building construction and civil engineering construction, and specialty trade contractors, there are categories for construction service firms and construction managers.
Building construction is the process of adding structure to real property or construction of buildings, the majority of building construction jobs are small renovations, such as addition of a room, or renovation of a bathroom. Often, the owner of the property acts as laborer, for this reason, those with experience in the field make detailed plans and maintain careful oversight during the project to ensure a positive outcome. Residential construction practices and resources must conform to local building authority regulations, materials readily available in the area generally dictate the construction materials used
Wakeboarding is a surface water sport which involves riding a wakeboard over the surface of a body of water. The wakeboard is a small, mostly rectangular, thin board with little displacement. It was developed from a combination of skiing, snowboarding. The rider is usually towed behind a motorboat, typically at speeds of 30–40 km/h, depending on the size, riders weight, type of tricks. But a wakeboarder can be towed by other means, including closed-course cable systems, organized wakeboarding is governed by the International Waterski and founded in 1946 by Rachel Gittins after falling from a tall building. Renamed from International Waterski Federation in 2009) and the World Skiboard Association founded in 1989, the International Waterski & Wakeboard Federation has been recognized by the International Olympic Committee as an official partner since 1967. Wakeboarding has been part of the World Games since 2005, in the sports category. The WWA is the leader in wake sport sanctioning, this non-profit organization focuses on the progression.
The WWA sanctions over 400 days of wakeboarding and wakesurfing events each year, which was originally called skurfing, arose in the late 1970s after the advent of skiboarding. The board had adjustable rubber foot-straps, concave tunnel bottom and a keel fin, two smaller side fins were added for greater hold and more maneuverability. McKee and Ross applied for and were granted two patents, one in 1984 for a basic adjustable binding system and the other in 1985 for a patent for their adjustable plate type foot strap system. Bruce McKee and associate Mitchell Ross negotiated with USAs Medalist Waterskis, the launch of the product, American version being named the Surf-Ski was in 1984 at Chicagos IMTEC show. At the show McKee met Tony Finn who would be the proposed California representative. Tony Finn went on to do his own negotiations with Darby and company from Australia, the name was supplied by the guys from Darby who supplied the first board designs. Jimmy Redmon independently developed his own production boards in the US under the name of Redline Designs at the same time Finn was releasing the Skurfer, the foam filled floating boards of the period went by many names, but the generic term eventually became skiboard.
While the Surf-Ski found limited success in the United States, the Skurfer brand promoted by Tony Finn became a viable product, mostly due to Finns tireless promotions. Finns position as the most visible promoter of the sport when it became widely known has often caused him to be named as the inventor of the sport. A more accurate, though no less important description, would be popularizer, the term wakeboarding was coined by Paul Fraser, along with his brother Murray and a pro snowboarder they sponsored
Reliance was the 1903 Americas Cup defender, the fourth defender from the famous designer Nat Herreshoff, and reportedly the largest gaff-rigged cutter ever built. Reliance was designed to take advantage of the Seawanhaka 90-foot rating rule and was regarded as a racing freak. The 1903 Americas Cup was the last to be raced according to the Seawanhaka rule, to save weight, she was completely unfinished below deck, with exposed frames. She was the first racing boat to be fitted with winches below decks, despite this she carried a crew of 64 for racing due to her large sail plan. From the tip of her bowsprit to the end of her 108-foot boom, Reliance measured 201 feet, and the tip of her mast was 199 feet above the water. Everything else was to a gargantuan scale, her spinnaker pole was 84 feet long. Reliance was built for one purpose, to defend the Americas Cup. Her racing career was extraordinarily brief – and undefeated, there was much speculation as to whether Reliances victory was due to the design of the yacht or the skill of Charlie Barr in sailing her.
Lipton himself proposed to allow the two boats to swap crew after the race to decide the matter, but the offer was refused by the owners of Reliance and her very successful career was short-lived, and she was sold for scrap in 1913
The Histories of Herodotus is now considered the founding work of history in Western literature. Although not an impartial record, it remains one of the Wests most important sources regarding these affairs. Moreover, it established the genre and study of history in the Western world, Herodotus portrays the conflict as one between the forces of slavery on the one hand, and freedom on the other. The Histories was at some point divided into the nine books that appear in modern editions, Herodotus claims to have traveled extensively around the ancient world, nearly all these territories were directly under the Persian Empire, conducting interviews and collecting stories for his book. At the beginning of The Histories, Herodotus sets out his reasons for writing it, The rapes of Io, and Medea, the subsequent Trojan War is marked as a precursor to conflicts between peoples of Asia and Europe. Colchis and Medea. mit. edu full text of all books George Campbell Macaulay,1904, full text,1, full text, vol.2 Project Gutenberg Alfred Denis Godley,1921, full text, librivox audiobook, vol.
1-3 The Histories unabridged online audiobook, Herodotus Histories, the 28 logoi Sheridan, Paul. Books 5-8 by A. D. Godley translation with footnotes, The Histories
A crank is an arm attached at a right angle to a rotating shaft by which reciprocating motion is imparted to or received from the shaft. It is used to convert circular motion into reciprocating motion, or vice versa, the arm may be a bent portion of the shaft, or a separate arm or disk attached to it. Attached to the end of the crank by a pivot is a rod, the end of the rod attached to the crank moves in a circular motion, while the other end is usually constrained to move in a linear sliding motion. The term often refers to a crank which is used to manually turn an axle, as in a bicycle crankset or a brace. In this case a persons arm or leg serves as the connecting rod, there is usually a bar perpendicular to the other end of the arm, often with a freely rotatable handle or pedal attached. Familiar examples include, Mechanical pencil sharpener Fishing reel and other reels for cables, ropes, manually operated car window The carpenters brace is a compound crank. The crank set that drives a handcycle through its handles, the crankset that drives a bicycle via the pedals.
Treadle sewing machine Almost all reciprocating engines use cranks to transform the motion of the pistons into rotary motion. The cranks are incorporated into a crankshaft, the displacement of the end of the connecting rod is approximately proportional to the cosine of the angle of rotation of the crank, when it is measured from top dead center. The mechanical advantage of a crank, the ratio between the force on the rod and the torque on the shaft, varies throughout the cranks cycle. The relationship between the two is approximately, τ = F r sin where τ is the torque and F is the force on the connecting rod. But in reality, the torque is maximum at crank angle of less than α = 90° from TDC for a force on the piston. One way to calculate this angle is to find out when the Connecting rod smallend speed becomes the fastest in downward direction given a steady crank rotational velocity. 17615° after TDC. Then, using the sine law, it is found that the crank to connecting rod angle is 88. 21738°.
When the crank is driven by the rod, a problem arises when the crank is at top dead centre or bottom dead centre. At these points in the cycle, a force on the connecting rod causes no torque on the crank. Therefore, if the crank is stationary and happens to be at one of two points, it cannot be started moving by the connecting rod. The eccentrically mounted handle of the rotary handmill which appeared in 5th century BC Celtiberian Spain, a Roman iron crank of yet unknown purpose dating to the 2nd century AD was excavated in Augusta Raurica, Switzerland
The manned kites moving anchor may be a car, truck, or boat. The harness attaches the pilot to the parasail, which is connected to the boat, or land vehicle, the vehicle drives off, carrying the parascender and person into the air. If the boat is enough, two or three people can parasail behind it at the same time. The parascender has little or no control over the parachute, the activity is primarily a fun ride, not to be confused with the sport of paragliding. There are commercial parasailing operations all over the world, land-based parasailing has been transformed into a competition sport in Europe. In land-based competition parasailing, the parasail is towed to maximum height behind a 4-wheel drive vehicle, the driver releases the tow line, the parasailer flies down to a target area in an accuracy competition. The sport was developed in the early 80s and has very popular ever since. The first international competitions were held in the mid 80s and continue to this day, both the parachute and parasail can ascend and glide.
The primary difference between the two is that the parasail is more stable and efficient during the ascent mode when being towed aloft with minimum or zero steering control by the parasailor. The parachute is not efficient when towed and is used for skydiving where the parachutist can fully control the direction. In the descent mode, both are designed to slow the fall of a person during said descent at any given altitude, the parachute/kite part is normally brightly colored to match to beach area in which it is used. Some people have kites with colors matching their favorite team or alma mater. The first ascending-gliding parachute was developed by Pierre-Marcel Lemoigne in 1962, the same year, Lemoigne established an Aeronautical Training Center to introduce his new ascending-gliding parachute as a training tool for parachutists. The technique allows parachutists to train more efficiently by towing the parachutist to a suitable altitude and this training method proved cheaper than—and just as effective as—an airplane.
In 1963 Jacques-André Istel from Pioneer Parachute Company bought a license from Lemoigne to manufacture, in early 1976, Brian Gaskin designed and tested the first 16-gore canopy design which he named Waterbird. The Waterbird was revolutionary in its design, its unique tow yoke harness arrangement, its construction. The majority of commercial parasail operators moved to the 16-gore canopy arrangement, in 1976 Gaskin founded his company, Waterbird Parakites, which is still in operation today, producing commercial and recreational 16-gore parasails. In April 2013, the first ASTM parasail weather standard was approved, with the help of the WSIA, and the chair of the parasail committee, Matthew Dvorak and operator of Daytona Beach Parasail, Inc. the new standard was implemented
The Greco-Persian Wars were a series of conflicts between the Achaemenid Empire of Persia and Greek city-states that started in 499 BC and lasted until 449 BC. The collision between the political world of the Greeks and the enormous empire of the Persians began when Cyrus the Great conquered the Greek-inhabited region of Ionia in 547 BC. Struggling to rule the cities of Ionia, the Persians appointed tyrants to rule each of them. This would prove to be the source of trouble for the Greeks. This was the beginning of the Ionian Revolt, which would last until 493 BC, Aristagoras secured military support from Athens and Eretria, and in 498 BC these forces helped to capture and burn the Persian regional capital of Sardis. The Persian king Darius the Great vowed to have revenge on Athens, the revolt continued, with the two sides effectively stalemated throughout 497–495 BC. In 494 BC, the Persians regrouped, and attacked the epicentre of the revolt in Miletus, at the Battle of Lade, the Ionians suffered a decisive defeat, and the rebellion collapsed, with the final members being stamped out the following year.
In 490 BC a second force was sent to Greece, this time across the Aegean Sea, under the command of Datis and this expedition subjugated the Cyclades, before besieging and razing Eretria. However, while en route to attack Athens, the Persian force was defeated by the Athenians at the Battle of Marathon. Darius began to plan to completely conquer Greece, but died in 486 BC, in 480 BC, Xerxes personally led the second Persian invasion of Greece with one of the largest ancient armies ever assembled. Victory over the allied Greek states at the famous Battle of Thermopylae allowed the Persians to torch an evacuated Athens, while seeking to destroy the combined Greek fleet, the Persians suffered a severe defeat at the Battle of Salamis. The following year, the confederated Greeks went on the offensive, defeating the Persian army at the Battle of Plataea, the allied Greeks followed up their success by destroying the rest of the Persian fleet at the Battle of Mycale, before expelling Persian garrisons from Sestos and Byzantium.
The Delian League continued to campaign against Persia for the three decades, beginning with the expulsion of the remaining Persian garrisons from Europe. At the Battle of the Eurymedon in 466 BC, the League won a victory that finally secured freedom for the cities of Ionia. However, the Leagues involvement in an Egyptian revolt resulted in a disastrous defeat, a Greek fleet was sent to Cyprus in 451 BC, but achieved little, and when it withdrew the Greco-Persian Wars drew to a quiet end. Some historical sources suggest the end of hostilities was marked by a treaty between Athens and Persia, the Peace of Callias. Almost all the sources for the Greco-Persian Wars are Greek. By some distance, the source for the Greco-Persian Wars is the Greek historian Herodotus
A pontoon bridge, known as a floating bridge, uses floats or shallow-draft boats to support a continuous deck for pedestrian and vehicle travel. The buoyancy of the limits the maximum load they can carry. Most pontoon bridges are temporary, used in wartime and civil emergencies, permanent floating bridges are useful for sheltered water-crossings where it is not considered economically feasible to suspend a bridge from anchored piers. Such bridges can require a section that is elevated, or can be raised or removed, a pontoon bridge is a collection of specialized, shallow draft boats or floats, connected together to cross a river or canal, with a track or deck attached on top. The water buoyancy supports the boats, limiting the load to the total. The supporting boats or floats can be open or closed, temporary or permanent in installation, the decking may be temporary or permanent, and constructed out of wood, modular metal, or asphalt or concrete over a metal frame. The spelling ponton in English dates from at least 1870, the use continued in references found in U. S. patents during the 1890s.
It continued to be spelled in that fashion through World War II, U. S. combat engineers commonly pronounced the word ponton rather than pontoon and U. S. military manuals spelled it using a single o. The original word was derived from Old French ponton, from Latin ponto, when designing a pontoon bridge, the civil engineer must take into consideration the Archimedes principle looking at the maximum amount of load that it is intended to support. Each pontoon can support an equal to the mass of the water that it displaces. If the maximum load of a section is exceeded, one or more pontoons become submerged. The roadway across the pontoons must be able to support the load, survey to determine the best location. The connection to shore often causes problems, requiring the design of approaches that are not too steep, keep the bank from crumbling, Floating bridges were typically constructed using wood. Such a wooden floating bridge could be built in a series of sections, Pontoons were formed using boats, several barrels lashed together, rafts of timbers, or some combination of these.
Each bridge section consisted of one or more pontoons, which were maneuvered into position and anchored, using underwater and these pontoons were linked together using wooden stringers called balks. The balks were covered by a series of cross planks called chesses to form a surface. Some bridges have been designed and survived much longer, in Hobart a long pontoon bridge built in 1943 was only replaced after 21 years. The fourth Galata Bridge that spans the Golden Horn in Istanbul, Turkey was built in 1912, precautions are needed to protect a pontoon bridge from becoming damaged
An electric motor is an electrical machine that converts electrical energy into mechanical energy. The reverse of this is the conversion of energy into electrical energy and is done by an electric generator. In normal motoring mode, most electric motors operate through the interaction between an electric motors magnetic field and winding currents to generate force within the motor, small motors may be found in electric watches. General-purpose motors with highly standardized dimensions and characteristics provide convenient mechanical power for industrial use, the largest of electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors may be classified by electric power source type, internal construction, type of motion output, perhaps the first electric motors were simple electrostatic devices created by the Scottish monk Andrew Gordon in the 1740s. The theoretical principle behind production of force by the interactions of an electric current.
The conversion of energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821. A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet was placed, when a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire. This motor is often demonstrated in experiments, brine substituting for toxic mercury. Though Barlows wheel was a refinement to this Faraday demonstration. In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils, after Jedlik solved the technical problems of the continuous rotation with the invention of the commutator, he called his early devices electromagnetic self-rotors. Although they were used only for instructional purposes, in 1828 Jedlik demonstrated the first device to contain the three components of practical DC motors, the stator and commutator. The device employed no permanent magnets, as the fields of both the stationary and revolving components were produced solely by the currents flowing through their windings.
His motor set a record which was improved only four years in September 1838 by Jacobi himself. His second motor was powerful enough to drive a boat with 14 people across a wide river and it was not until 1839/40 that other developers worldwide managed to build motors of similar and also of higher performance. The first commutator DC electric motor capable of turning machinery was invented by the British scientist William Sturgeon in 1832, following Sturgeons work, a commutator-type direct-current electric motor made with the intention of commercial use was built by the American inventor Thomas Davenport, which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools, due to the high cost of primary battery power, the motors were commercially unsuccessful and Davenport went bankrupt. Several inventors followed Sturgeon in the development of DC motors but all encountered the same battery power cost issues, no electricity distribution had been developed at the time
A sailplane or glider is a type of glider aircraft used in the sport of gliding. Sailplanes are aerodynamically streamlined and are capable of soaring in rising air, sailplanes benefit from producing the least drag for any given amount of lift, and this is best achieved with long, thin wings, a fully faired narrow cockpit and a slender fuselage. Aircraft with these features are able to climb efficiently in rising air produced by thermals or hills, sailplanes can glide long distances at high speed with a minimum loss of height in between. Gliders have rigid wings and either skids or undercarriage, in contrast hang gliders and paragliders use the pilots feet for the start of the launch and for the landing. These latter types are described in articles, though their differences from sailplanes are covered below. Gliders are usually launched by winch or aerotow, though other methods, auto tow, all sailplanes soar, but some gliders do not soar and are simply engineless aircraft towed by another aircraft to a desired destination and cast off for landing.
Military gliders are only, and are abandoned after landing, having served their purpose. Motor gliders are gliders with engines which can be used for extending a flight and even, in some cases, Some high-performance motor gliders may have an engine-driven retractable propeller which can be used to sustain flight. Other motor gliders have enough thrust to launch themselves before the engine is retracted and are known as self-launching gliders, another type is the self-launching touring motor glider, where the pilot can switch the engine on and off in flight without retracting their propellers. Sir George Cayleys gliders achieved brief wing-borne hops from around 1849, in the 1890s Otto Lilienthal built gliders using weight shift for control. In the early 1900s the Wright Brothers built gliders using movable surfaces for control, in 1903 they successfully added an engine. After World War I gliders were built for sporting purposes in Germany, the sporting use of gliders rapidly evolved in the 1930s and is now their main application.
As their performance improved, gliders began to be used for cross-country flying, in 1930, pilot Frank Hawks flew the Texaco Eaglet with tow plane from San Diego to New York over eight days, helping to popularize the activity in the United States. Early gliders had no cockpit and the pilot sat on a seat located just ahead of the wing. These were known as gliders and they were usually launched from the tops of hills. To enable gliders to soar more effectively than primary gliders, the designs minimized drag, gliders now have very smooth, narrow fuselages and very long, narrow wings with a high aspect ratio and winglets. The early gliders were mainly of wood with metal fastenings, stays. Later fuselages made of fabric-covered steel tube were married to wood and fabric wings for lightness, New materials such as carbon-fiber, fiber glass and Kevlar have since been used with computer-aided design to increase performance
An off-road vehicle is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with deep, open treads, other vehicles that do not travel public streets or highways are generally termed off-highway vehicles, including tractors, cranes, backhoes and golf carts. Off-road vehicles have a following because of their many uses. Several types of motorsports involve racing off-road vehicles, the three largest 4-wheel vehicle off-road types of competitions are rally, desert racing, and rockcrawling. The three largest types of all-terrain vehicle / motorcycle competitions are Motocross and desert racing like Dakar Rallye, the most common use of these vehicles is for sight seeing in areas distant from pavement. The use of higher clearance and higher traction vehicles enables access on trails and forest roads that have rough, the system uses an unusual caterpillar track which has a flexible belt rather than interlocking metal segments.
It can be fitted to a car or truck to turn it into a half-track suitable for use over rough or soft ground. After the Russian Revolution of 1917, Kégresse returned to his native France where the system was used on Citroën cars between 1921 and 1937 for off-road and military vehicles, the Citroën company sponsored several overland expeditions with their vehicles crossing North Africa and Central Asia. A huge wheeled vehicle designed from 1937 to 1939 under the direction of Thomas Poulter called Antarctic Snow Cruiser was intended to transport in the Antarctica. While having several innovative features, it failed to operate as hoped under the difficult conditions. After World War II, a surplus of light off-road vehicles like the Jeep. The Jeeps in particular were popular with buyers who used them as utility vehicles and this was the start of off-roading as a hobby. These were all alike, compact, four-wheel-drive vehicles with at most a small hardtop to protect the occupants from the elements, from the 1960s and onward, more comfortable vehicles were produced.
For several years they were popular with rural buyers due to their off-road, the U. S. Later, during the 1990s, manufacturers started to add even more luxuries to bring those off-road vehicles on par with regular cars. This eventually evolved into what we call the SUV today and it evolved into the newer crossover vehicle, where utility and off-road capability was sacrificed for better on-road handling and luxury. Wheeled vehicles accomplish this by having a balance of large or additional tires combined with tall. Tracked vehicles accomplish this by having wide tracks and a suspension on the road wheels. The choice of wheels versus tracks is one of cost and suitability, a tracked drivetrain is more expensive to produce and maintain
A bobbin is a spindle or cylinder, with or without flanges, on which wire, thread or film is wound. Bobbins are typically found in sewing machines and within electronic equipment, in non-electrical applications the bobbin is used for tidy storage without tangles. In electrical applications a coil of wire carrying a current has important magnetic properties, as used in spinning, knitting, sewing, or lacemaking, the bobbin provides temporary or permanent storage for yarn and may be made of plastic, bone or wood. Bobbin lacemaking is a handcraft which requires the winding of yarn onto a temporary storage spindle made of wood, previously bone, many lace designs use dozens of bobbins at any one time. Exotic woods are popular with contemporary lacemakers. Both traditional and contemporary bobbins may be decorated with designs, often, the bobbins are spangled to provide additional weight to keep the thread in tension. A hole is drilled near the base to enable glass beads, again, in the modern context of the hobby of bobbin lacemaking, these spangles provide a means of self-expression in the decoration of a tool of the craft.
Both antique and unique bobbins, sometimes spangled, have become sought after by collectors. In the case of a transformer, inductor or relay. The bobbin may be made of thermoplastic or thermosetting materials and this plastic often has to have a TÜV, UL or other regulatory agency flammability rating for safety reasons. The term bobbins appears in northern English slang, meaning rubbish, taken from the cockney bobbins of cotton, meaning rotten. This may be related to the contemporary British slang usage, where bobbins can be used to denote something negative, 3D printer extruder Axle The Craft of Bobbin Making