Iron Ore | Understanding and definition of Iron Ore | How to iron ore mining

Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, deep purple, to rusty red. The iron itself is usually found in the form of magnetite (Fe₃O₄), hematite (Fe₂O₃), goethite (FeO(OH)), limonite (FeO(OH).n(H₂O)) or siderite (FeCO₃). Hematite is also known as "natural ore", a name which refers to the early years of mining, when certain hematite ores containing up to 66% iron could be fed directly into iron-making blast furnaces. Iron ore is the raw material used to make pig iron, which is one of the main raw materials to make steel. 98% of the mined iron ore is used to make steel. Indeed, it has been argued that iron ore is "more integral to the global economy than any other commodity, except perhaps oil”.

Metallic iron is virtually unknown on the surface of the Earth except as iron-nickel alloys from meteorites and very rare forms of deep mantle xenoliths. Although iron is the fourth most abundant element in the Earth's crust, comprising about 5%, the vast majority is bound in silicate or more rarely carbonate minerals. The thermodynamic barriers to separating pure iron from these minerals are formidable and energy intensive, therefore all sources of iron used by human industry exploit comparatively rarer iron oxide minerals, the primary form which is used being hematite.

Prior to the industrial revolution, most iron was obtained from widely available goethite or bog ore, for example during the American Revolution and the Napoleonic wars. Prehistoric societies used laterite as a source of iron ore. Historically, much of the iron ore utilized by industrialized societies has been mined from predominantly hematite deposits with grades in excess of 60% Fe. These deposits are commonly referred to as "direct shipping ores" or "natural ores". Increasing iron ore demand, coupled with the depletion of high-grade hematite ores in the United States, after World War II led to development of lower-grade iron ore sources, principally the utilization of taconite in North America. Lower-grade sources of iron ore generally require beneficiation. Magnetite is often utilized because it is magnetic, and hence easily separated from the gangue minerals and capable of producing a high-grade concentrate with very low levels of impurities. Due to the high density of hematite relative to associated silicate gangue, hematite beneficiation usually involves a combination of crushing, milling, gravity or heavy media separation, and silica froth flotation. One method relies on passing the finely crushed ore over a bath of solution containing bentonite or other agent which increases the density of the solution. When the density of the solution is properly calibrated, the hematite will sink and the silicate mineral fragments will float and can be removed.

Iron ore mining methods vary by the type of ore being mined. There are four main types of iron ore deposits worked currently, depending on the mineralogy and geology of the ore deposits. These are magnetite, titanomagnetite, massive hematite and pisolitic ironstone deposits.

The mining involves moving tremendous amounts of ore and waste. The waste comes in two forms, bedrock in the mine (mullock) that isn't ore, and unwanted minerals which are an intrinsic part of the ore rock itself (gangue). The mullock is mined and piled in waste dumps, and the gangue is separated during the beneficiation process and is removed as tailings. Taconite tailings are mostly the mineral quartz, which is chemically inert. This material is stored in large, regulated water settling ponds.

The key economic parameters for magnetite ore being economic are the crystallinity of the magnetite, the grade of the iron within the BIF host rock, and the contaminant elements which exist within the magnetite concentrate. The size and strip ratio of most magnetite resources is irrelevant as BIF formations can be hundreds of metres thick, with hundreds of kilometers of strike, and can easily come to more than 3,000 million or more, tonnes of contained ore.

The typical grade of iron at which a magnetite-bearing banded iron formation becomes economic is roughly 25% Fe, which can generally yield a 33% to 40% recovery of magnetite by weight, to produce a concentrate grading in excess of 64% Fe by weight. The typical magnetite iron ore concentrate has less than 0.1% phosphorus, 3–7% silica and less than 3% aluminium.

The grain size of the magnetite and its degree of commingling with the silica groundmass determine the grind size to which the rock must be comminuted to enable efficient magnetic separation to provide a high purity magnetite concentrate. This determines the energy inputs required to run a milling operation. Generally most magnetite BIF deposits must be ground to between 32 and 45 micrometres in order to produce a low-silica magnetite concentrate. Magnetite concentrate grades are generally in excess of 63% Fe by weight and usually are low phosphorus, low aluminium, low titanium and low silica and demand a premium price.

Currently magnetite iron ore (taconite) is mined in Minnesota and Michigan in the U.S., and Eastern Canada. Magnetite bearing BIF is currently mined extensively in Brazil, which exports significant quantities to Asia, and there is a nascent and large magnetite iron ore industry in Australia.

Occasionally granite and ultrapotassic igneous rocks segregate magnetite crystals and form masses of magnetite suitable for economic concentration. A few iron ore deposits, notably in Chile, are formed from volcanic flows containing significant accumulations of magnetite phenocrysts. Chilean magnetite iron ore deposits within the Atacama Desert have also formed alluvial accumulations of magnetite in streams leading from these volcanic formations.

Some magnetite skarn and hydrothermal deposits have been worked in the past as high-grade iron ore deposits requiring little beneficiation. There are several granite-associated deposits of this nature in Malaysia and Indonesia.

Other sources of magnetite iron ore include metamorphic accumulations of massive magnetite ore such as at Savage River, Tasmania, formed by shearing of ophiolite ultramafics.

Another, minor, source of iron ores are magmatic accumulations in layered intrusions which contain a typically titanium-bearing magnetite often with vanadium. These ores form a niche market, with specialty smelters used to recover the iron, titanium and vanadium. These ores are beneficiated essentially similar to banded iron formation ores, but usually are more easily upgraded via crushing and screening. The typical titanomagnetite concentrate grades 57% Fe, 12% Ti and 0.5% V₂O₅.

Hematite iron ore deposits are currently exploited on all continents except Antarctica, with the largest intensity in South America, Australia and Asia. Most large hematite iron ore deposits are sourced from altered banded iron formations and rarely igneous accumulations.

Hematite iron is typically rarer than magnetite bearing BIF or other rocks which form its main source or protolith rock, but it is considerably cheaper to process as it generally does not require beneficiation due to its higher iron content. However, hematite ores are harder than magnetite ores and therefore require considerably more energy to crush and grind if benefication is required. Hematite ores can also contain significantly higher concentrations of penalty elements, typically being higher in phosphorus, water content (especially pisolite sedimentary accumulations) and aluminium (clays within pisolites). Export grade hematite ores are generally in the 62–64% Fe range.

Iron is the world's most commonly used metal - steel, of which iron ore is the key ingredient, representing almost 95% of all metal used per year. It is used primarily in structural engineering applications and in maritime purposes, automobiles, and general industrial applications (machinery).

Iron-rich rocks are common worldwide, but ore-grade commercial mining operations are dominated by the countries listed in the table aside. The major constraint to economics for iron ore deposits is not necessarily the grade or size of the deposits, because it is not particularly hard to geologically prove enough tonnage of the rocks exist. The main constraint is the position of the iron ore relative to market, the cost of rail infrastructure to get it to market and the energy cost required to do so.

Mining iron ore is a high volume low margin business, as the value of iron is significantly lower than base metals. It is highly capital intensive, and requires significant investment in infrastructure such as rail in order to transport the ore from the mine to a freight ship. For these reasons, iron ore production is concentrated in the hands a few major players.

World production averages two billion metric tons of raw ore annually. The world's largest producer of iron ore is the Brazilian mining corporation Vale, followed by Anglo-Australian companies BHP Billiton and Rio Tinto Group. A further Australian supplier, Fortescue Metals Group Ltd has helped bring Australia's production to second in the world.

The seaborne trade in iron ore, that is, iron ore to be shipped to other countries, was 849m tonnes in 2004. Australia and Brazil dominate the seaborne trade, with 72% of the market. BHP, Rio and Vale control 66% of this market between them.

In Australia iron ore is won from three main sources: pisolite "channel iron deposit" ore derived by mechanical erosion of primary banded-iron formations and accumulated in alluvial channels such as at Pannawonica, Western Australia; and the dominant metasomatically-altered banded iron formation related ores such as at Newman, the Chichester Range, the Hamersley Range and Koolyanobbing, Western Australia. Other types of ore are coming to the fore recently, such as oxidised ferruginous hardcaps, for instance laterite iron ore deposits near Lake Argyle in Western Australia.

The total recoverable reserves of iron ore in India are about 9,602 million tones of hematite and 3,408 million tones of magnetite. Madhya Pradesh, Karnataka, Jharkhand, Orissa, Goa, Maharashtra, Andhra Pradesh, Kerala, Rajasthan and Tamil Nadu are the principal Indian producers of iron ore.

World consumption of iron ore grows 10% per annum on average with the main consumers being China, Japan, Korea, the United States and the European Union.

China is currently the largest consumer of iron ore, which translates to be the world's largest steel producing country. It is also the largest importer, buying 52% of the seaborne trade in iron ore in 2004. China is followed by Japan and Korea, which consume a significant amount of raw iron ore and metallurgical coal. In 2006, China produced 588 million tons of iron ore, with an annual growth of 38%.

Iron ores consists of oxygen and iron atoms bonded together into molecules. To convert it to metallic iron it must be smelted or sent through a direct reduction process to remove the oxygen. Oxygen-iron bonds are strong, and to remove the iron from the oxygen, a stronger elemental bond must be presented to attach to the oxygen. Carbon is used because the strength of a carbon-oxygen bond is greater than that of the iron-oxygen bond, at high temperatures. Thus, the iron ore must be powdered and mixed with coke, to be burnt in the smelting process.

However, it is not entirely as simple as that; carbon monoxide is the primary ingredient of chemically stripping oxygen from iron. Thus, the iron and carbon smelting must be kept at an oxygen deficient (reducing) state to promote burning of carbon to produce CO not CO₂.

• Air blast and charcoal (coke): 2 C + O₂ → 2 CO.


• Carbon monoxide (CO) is the principal reduction agent.


• Stage One: 3 Fe₂O₃ + CO → 2 Fe₃O₄ + CO₂


• Stage Two: Fe₃O₄ + CO → 3 FeO + CO₂


• Stage Three: FeO + CO → Fe + CO₂


• Limestone calcining: CaCO₃ → CaO + CO₂


• Lime acting as flux: CaO + SiO₂ → CaSiO₃

Silica (SiO₂) is almost always present in iron ore. Most of it is slagged off during the smelting process. At temperatures above 1300 °C some will be reduced and form an alloy with the iron. The hotter the furnace, the more silicon will be present in the iron. It is not uncommon to find up to 1.5% Si in European cast iron from the 16th to 18th centuries.

The major effect of silicon is to promote the formation of gray iron. Gray iron is less brittle and easier to finish than white iron. It is preferred for casting purposes for this reason. Turner (1900, pp. 192–197) reported that silicon also reduces shrinkage and the formation of blowholes, lowering the number of bad castings.

Adidas Products | History of Adidas | Understanding Adidas | Latest Products Adidas

Adidas

Adidas AG is a German sports apparel manufacturer and parent company of the Adidas Group, which consists of the Reebok sportswear company, golf company (including Ashworth), and Rockport. Besides sports footwear, the company also produces other products such as bags, shirts, watches, eyewear and other sports and clothing-related goods. The company is the largest sportswear manufacturer in Europe and the second biggest sportswear manufacturer in the world, after its American rival Nike.

Adidas was founded in 1948 by Adolf "Adi" Dassler, following the split of Gebrüder Dassler Schuhfabrik between him and his older brother, Rudolf. Rudolf later established Puma, which was the early rival of Adidas. Registered in 1949, Adidas is currently based in Herzogenaurach, Germany, along with Puma.

The company's clothing and shoe designs typically feature three parallel bars, and the same motif is incorporated into Adidas's current official logo. The "Three Stripes" were bought from the Finnish sport company Karhu Sports in 1951. The company revenue for 2009 was listed at €10.38 billion and the 2008 figure at €10.80 billion.

Adolf "Adi" Dassler started to produce his own sports shoes in his mother's wash kitchen in Herzogenaurach, Bavaria, after his return from World War I. On July 1, 1924, his brother Rudolf "Rudi" Dassler joined the business which became Gebrüder Dassler Schuhfabrik (Dassler Brothers Shoe Factory) and prospered. The pair started the venture in their mother's laundry,[6]:5 but at the time, electricity supplies in the town were unreliable, and the brothers sometimes had to use pedal power from a stationary bicycle to run their equipment.

By the 1936 Summer Olympics, Adi Dassler drove from Bavaria on one of the world's first motorways to the Olympic village with a suitcase full of spikes and persuaded U.S. sprinter Jesse Owens to use them, the first sponsorship for an African American. Following Owens's haul of four gold medals, his success cemented the good reputation of Dassler shoes among the world's most famous sportsmen. Letters from around the world landed on the brothers' desks, and the trainers of other national teams were all interested in their shoes. Business boomed and the Dasslers were selling 200,000 pairs of shoes each year before World War II.

Late in World War II, the shoe factory shifted to production of the Panzerschreck anti-tank weapon.

After a period of trouble following the death of Adolf Dassler's son Horst Dassler in 1987, the company was bought in 1989 by French industrialist Bernard Tapie, for ₣1.6 billion (now €243.918 million), which Tapie borrowed. Tapie was at the time a famous specialist of rescuing bankrupt companies, an expertise on which he built his fortune.

Tapie decided to move production offshore to Asia. He also hired Madonna for promotion. He sent, from Christchurch, New Zealand, a shoe sales representative to Germany and met Adolf Dassler's descendants (Amelia Randall Dassler and Bella Beck Dassler) and was sent back with a few items to promote the company there.

In 1992, unable to pay the loan interest, Tapie mandated the Crédit Lyonnais bank to sell Adidas, and the bank subsequently converted the outstanding debt owed into equity of the enterprise, which was unusual as per the prevalent French banking practice. Apparently, the state-owned bank had tried to get Tapie out of dire financial straits as a personal favour to Tapie, reportedly because Tapie was Minister of Urban Affairs (ministre de la Ville) in the French government at the time.

In February 1993, Crédit Lyonnais sold Adidas to Robert Louis-Dreyfus, a friend of Bernard Tapie for a much higher amount of money than what Tapie owed, 4.485 billion (€683.514 million) francs rather than 2.85 billion (€434.479 million). Tapie later sued the bank, because he felt "spoiled" by the indirect sale.

Robert Louis-Dreyfus became the new CEO of the company. He was also the president of Olympique de Marseille, a team Tapie had owned until 1993.

Tapie filed for personal bankruptcy in 1994. He was the object of several lawsuits, notably related to match fixing at the football club. During 1997, he served 6 months of an 18-month prison sentence in La Santé prison in Paris. In 2005, French courts awarded Tapie a €135 million compensation (about 886 million francs).

Adidas currently manufactures several running shoes, including the adiStar Control 5, the adiStar Ride (the replacement for the adiStar Cushion 6), the Supernova Sequence (the replacement for the Supernova Control 10), and the Supernova Cushion 7 (which will soon be replaced by the Supernova Glide), among others. In addition, their performance apparel is widely used by runners. Adidas also uses kangaroo leather to make their more expensive shoes.

One of the main focuses of Adidas is football kit and associated equipment. Adidas remain a major company in the supply of team kits for international football teams.

Adidas also makes referee kits that are used in international competition and by many countries and leagues in the world. The company has been an innovator in the area of footwear for the sport with notable examples including development of the Copa Mundial moulded boot used for matches on firm dry pitches for almost forty years. The studded equivalent was named World Cup follow in celebration of the 1978 tournament won by Argentina, one of the nations it supplied at the time. Some of the most famous football teams are currently sponsored by Adidas.

Adidas became renowned for advancing the Predator boot design developed by ex-Liverpool and Australian international player Craig Johnston. This design featured a ribbed rubber structure for the upper leather of the shoe, used to accent the movement of the ball when struck; highly skilled players claimed they were able to curve the flight of the ball more easily when wearing this new contoured design. The Predator also features the Craig Johnston-invented Traxion sole.

FIFA, the world governing body of football, commissioned specially designed footballs for use in its own World Cup tournaments to favour more attacking play. The balls supplied for the 2006 World Cup, the Teamgeist, were particular noteworthy for their ability to travel further than previous types when struck, leading to longer range goal strikes that were intended to increase the number of goals scored. Goalkeepers were believed to be less comfortable with the design, claiming it would move significantly and unpredictably in flight.

Adidas also introduced another new ball for the 2010 World Cup. The Jabulani ball was designed and developed by Loughborugh University in conjunction with Chelsea FC. It received much criticism from players, managers and pundits for being too hard to control. The lighter and more aerodynamic ball led to many shots and passes being over hit. The Jabulani was widely blamed for the low numbers of long range goals or even remotely accurate attempts in the opening stage of the tournament.

As well as the aforementioned Predator boot, adidas also manufacture the F50 and adiPure range of football boots.

Adidas also provides apparel and equipment for all teams in Major League Soccer.

Chemical plant | Understanding and definition of Chemical plant

A chemical plant is an industrial process plant that manufactures (or otherwise processes) chemicals, usually on a large scale. The general objective of a chemical plant is to create new material wealth via the chemical or biological transformation and or separation of materials. Chemical plants use special equipment, units, and technology in the processes. Other kinds of plants, such as polymer, pharmaceutical, food, and some beverage production facilities, power plants, oil refineries or other refineries, natural gas processing and biochemical plants, water and wastewater treatment, and pollution control equipment use many technologies which have similarities to chemical plant technology such as fluid systems. Some would consider an oil refinery or a pharmaceutical or polymer manufacturer to be effectively a chemical plant.

Petrochemical plants (plants using petroleum as a raw material) are usually located adjacent to an oil refinery to minimize transportation costs for the feedstocks produced by the refinery. Specialty chemical plants are usually much smaller and not as sensitive to location.

Chemical plants typically use chemical processes, which are detailed industrial-scale methods, to produce the chemicals. The same chemical process can be used at more than one chemical plant, with possibly differently scaled capacities at each plant. Also, a chemical plant at a site may be constructed to utilize more than one chemical process.

A chemical plant commonly has usually large vessels or sections called units that are interconnected by piping or other material-moving equipment which can carry streams of material. Such material streams can include fluids (gas or liquid carried in piping) or sometimes solids or mixtures such as slurries. An overall chemical process is commonly made up of steps called unit operations which occur in the individual units. A raw material going into a chemical process or plant as input to be converted into a product is commonly called a feedstock, or simply feed. In addition to feedstocks for the plant as a whole, an input stream of material to be processed in a particular unit can similarly be considered feed for that unit. Output streams from the plant as a whole are final products and output streams from individual units may be considered intermediate products for their units. However, final products from one plant may be intermediate chemicals used as feedstock in another plant for further processing. For example, some products from an oil refinery may used as feedstock in petrochemical plants.

Either the feedstock(s), the product(s), or both may be individual compounds or mixtures. It is often not worthwhile separating the components in these mixtures completely based on product requirements and economics.

Various kinds of unit operations are conducted in various kinds of units. Although some units may operate at ambient temperature or pressure, many units operate at higher or lower temperatures or pressures. Vessels in chemical plants are often cylindrical with rounded ends, a shape which can be suited to hold either high pressure or vacuum. Chemical reactions can convert certain kinds of compounds into other compounds in chemical reactors. Chemical reactors may be packed beds and may have solid heterogeneous catalysts which stay in the reactors as fluids move through. Since the surface of solid heterogeneous catalysts may sometimes become poisoned from deposits such as coke, regeneration of catalysts may be necessary. Fluidized beds may also be used in some cases. There can also be units (or subunits) for mixing (including dissolving), separation, heating, cooling, or some combination of these. For example, chemical reactors often have stirring for mixing and heating or cooling going on in them. When designing plants on a large scale, heat produced or absorbed by chemical reactions should be considered. Some plants may have units with organism cultures for biochemical processes such as fermentation or enzyme production.

Separation processes include filtration, settling (sedimentation), extraction or leaching, distillation, recrystallization or precipitation (followed by filtration or settling), reverse osmosis, drying, and adsorption. Heat exchangers are often used for heating or cooling, including boiling or condensation, often in conjunction with other units such as distillation towers. There may also be storage tanks for storing feedstock, intermediate or final products, or waste. Storage tanks commonly have level indicators to show how full they are. There may be structures holding or supporting sometimes massive units and their associated equipment. There are often stairs, ladders, or other steps for personnel to reach points in the units for sampling, inspection, or maintenance. An area of a plant or facility with numerous storage tanks is sometimes called a tank farm, especially at an oil depot.

Fluid systems for carrying liquids and gases include piping and tubing of various diameter sizes, various types of valves for controlling or stopping flow, pumps for moving or pressurizing liquid, and compressors for pressurizing or moving gases. Vessels, piping, tubing, and sometimes other equipment at high or very low temperature are commonly covered with insulation for personnel safety and to maintain temperature inside. Fluid systems and units commonly have instrumentation such as temperature and pressure sensors and flow measuring devices at select locations in a plant. Online analyzers for chemical or physical property analysis have become more common. Solvents can sometimes be used to dissolve reactants or materials such as solids for extraction or leaching, to provide a suitable medium for certain chemical reactions to run, or so they can otherwise be treated as fluids.

In process control, information gathered automatically from various sensors or other devices in the plant is used to control various equipment for running the plant, thereby controlling operation of the plant. Instruments receiving such information signals and sending out control signals to perform this function automatically are process controllers. Previously, pneumatic controls were sometimes used. Electrical controls are now common. A plant often has a control room with displays of parameters such as key temperatures, pressures, fluid flow rates and levels, operating positions of key valves, pumps and other equipment, etc. In addition, operators in the control room can control various aspects of the plant operation, often including overriding automatic control. Process control with a computer represents more modern technology. Based on possible changing feedstock composition, changing products requirements or economics, or other changes in constraints, operating conditions may be re-optimized to maximize profit.

As in any industrial setting, there are a variety of workers working throughout a chemical plant facility, often organized into departments, sections, or other work groups. Such workers typically include engineers, plant operators, and maintenance technicians. Other personnel at the site could include chemists, management/administration and office workers. Types of engineers involved in operations or maintenance may include chemical process engineers, mechanical engineers for maintaining mechanical equipment, and electrical/computer engineers for electrical or computer equipment.

Large quantities of fluid feedstock or product may enter or leave a plant by pipeline, railroad tank car, or tanker truck. For example, petroleum commonly comes to a refinery by pipeline. Pipelines can also carry petrochemical feedstock from a refinery to a nearby petrochemical plant. Natural gas is a product which comes all the way from a natural gas processing plant to final consumers by pipeline or tubing. Large quantities of liquid feedstock are typically pumped into process units. Smaller quantities of feedstock or product may be shipped to or from a plant in drums. Use of drums about 55 gallons in capacity is common for packaging industrial quantities of chemicals. Smaller batches of feedstock may be added from drums or other containers to process units by workers.

In addition to feeding and operating the plant, and packaging or preparing the product for shipping, plant workers are needed for taking samples for routine and troubleshooting analysis and for performing routine and non-routine maintenance. Routine maintenance can include periodic inspections and replacement of worn catalyst, analyzer reagents, various sensors, or mechanical parts. Non-routine maintenance can include investigating problems and then fixing them, such as leaks, failure to meet feed or product specifications, mechanical failures of valves, pumps, compressors, sensors, etc.

The actual production or process part of a plant may be indoors, outdoors, or a combination of the two. The actual production section of a facility usually has the appearance of a rather industrial environment. Hard hats and work shoes are commonly worn. Floors and stairs are often made of metal grating, and there is practically no decoration. There may also be pollution control or waste treatment facilities or equipment. Sometimes existing plants may be expanded or modified based on changing economics, feedstock, or product needs. As in other production facilities, there may be shipping and receiving, and storage facilities. In addition, there are usually certain other facilities, typically indoors, to support production at the site.

Although some simple sample analysis may be able to be done by operations technicians in the plant area, a chemical plant typically has a laboratory where chemists analyze samples taken from the plant. Such analysis can include chemical analysis or determination of physical properties. Sample analysis can include routine quality control on feedstock coming into the plant, intermediate and final products to ensure quality specifications are met. Non-routine samples may be taken and analyzed for investigating plant process problems also. A larger chemical company often has a research laboratory for developing and testing products and processes where there may be pilot plants, but such a laboratory may be located at a site separate from the production plants.

A plant may also have a workshop or maintenance facility for repairs or keeping maintenance equipment. There is also typically some office space for engineers, management or administration, and perhaps for receiving visitors. The decorum there is commonly more typical of an office environment.

Gucci | History and definition of the Gucci | The Logo Gucci

Gucci

The House of Gucci, better known simply as Gucci is an Italian fashion and leather goods label, part of the Gucci Group, which is owned by French company PPR. Gucci was founded by Guccio Gucci in Florence in 1921.

Gucci generated circa € 4.2 billion in revenue worldwide in 2008 according to BusinessWeek magazine and climbed to 41st position in the magazine's annual 2009 "Top Global 100 Brands" chart created by Interbrand. Gucci is also the biggest-selling Italian brand. Gucci operates about 278 directly operated stores worldwide (as of September 2009) and it wholesales its products through franchisees and upscale department stores.

From modest beginnings at the end of the nineteenth century, the Gucci company became one of the world’s most successful manufacturers of high-end leather goods, clothing, and other fashion products. As an immigrant in Paris and then London, working in exclusive hotels, young Guccio Gucci (1881–1953) was impressed with the luxurious luggage he saw sophisticated guests bring with them. Upon returning to his birthplace of Florence, a city distinguished for high-quality materials and skilled artisans, he established a shop in 1920 that sold fine leather goods with classic styling. Although Gucci organized his workrooms for industrial methods of production, he maintained traditional aspects of fabrication. Initially Gucci employed skilled workers in basic Florentine leather crafts, attentive to finishing. With expansion, machine stitching was a production method that supported construction.

Together with three of his sons, Aldo, Vasco, and Rodolfo, Gucci expanded the company to include stores in Milan and Rome as well as additional shops in Florence. Gucci’s stores featured such finely crafted leather accessories as handbags, shoes, and his iconic ornamented loafer as well as silks and knitwear in a signature pattern. The Gucci loafer is the only shoe in the collection of the Museum of Modern Art in New York.

The company made handbags of cotton canvas rather than leather during World War II as a result of material shortages. The canvas, however, was distinguished by a signature double-G symbol combined with prominent red and green bands. After the war, the Gucci crest, which showed a shield and armored knight surrounded by a ribbon inscribed with the family name, became synonymous with the city of Florence.

Aldo and Rodolfo Gucci further expanded the company’s horizons in 1953 by establishing offices in New York City. Film stars and jet-set travelers to Italy during the 1950s and 1960s brought their glamour to Florence, turning Gucci’s merchandise into international status symbols. Movie stars posed in Gucci’s clothing, accessories, and footwear for lifestyle magazines around the world, contributing to the company’s growing reputation.

Gucci’s distinctive lines made its products among the most frequently copied in the world in the early 2000s. Pigskin, calf, and imported exotic animal skins were subjected to various methods of fabrication. Waterproof canvas and satin were used for evening bags. Bamboo was first used to make handbag handles by a process of heating and molding in 1947, and purses made with a shoulder strap and snaffle-bit decoration were introduced in 1960. In 1964 Gucci’s lush butterfly pattern was custom-created for silk foulards, followed by equally luxuriant floral patterns. The original Gucci loafer was updated by a distinctive snaffle-bit ornament in 1966, while the “Rolls-Royce” luggage set was introduced in 1970. Watches, jewelry, ties, and eyewear were then added to the company’s product lines. A particularly iconic touch, introduced in 1964, was the use of the double-G logo for belt buckles and other accessory decorations.

The company prospered through the 1970s, but the 1980s were marked by internal family disputes that brought Gucci to the brink of disaster. Rodolfo’s son Maurizio took over the company’s direction after his father’s death in 1983, and dismissed his uncle Aldo—who eventually served a prison term for tax evasion. Maurizio proved to be an unsuccessful president; he was compelled to sell the family-owned company to Investcorp, a Bahrain-based company, in 1988. Maurizio disposed of his remaining stock in 1993. Tragically, Maurizio was murdered in Milan in 1995, and his former wife, Patrizia Reggiani, was convicted of hiring his killers. Meanwhile, the new investors promoted the American-educated Domenico De Sole from the position of family attorney to president of Gucci America in 1994 and chief executive in 1995.

The company had previously brought in Dawn Mello in 1989 as editor and ready-to-wear designer in order to reestablish its reputation. Well aware of Gucci’s tarnished image and the value of its name brand, Mello hired Tom Ford in 1990 to design a ready-to-wear line. He was promoted to the position of creative director in 1994. Before Mello returned to her post as president of the American retailer Bergdorf Goodman, she initiated the return of Gucci’s headquarters from the business center of Milan to Florence, where its craft traditions were rooted. There she and Ford reduced the number of Gucci products from twenty thousand to a more reasonable five thousand.

Tom Ford came to the foundering company with vision and style. Having the strong support of Dominico De Sole, Ford wished to maintain a sense of the company’s history while updating Gucci’s trademarks. In 1994 Ford became responsible for creative direction, and by 1996 he directed all aspects of the company—including ready-to-wear clothing, visual merchandising, packaging, interior design, and advertising. Ford and De Sole struggled to restore the former reputation of Gucci, while redirecting the growing brand to a new level for the market of the late 1990s.

There were seventy-six Gucci stores around the world in 1997, along with numerous licensing agreements. Ford was instrumental in the process of decision-making with De Sole when the Gucci Group acquired Yves Saint Laurent Rive Gauche, Bottega Veneta, Boucheron, Sergio Rossi, and, in part-ownership with Stella McCartney, Alexander McQueen and Balenciaga. By 2001 Ford and De Sole shared the responsibility for major business decisions, while Ford concurrently directed design at Yves Saint Laurent as well as at Gucci.

The French conglomerate Pinault-Printemps-Redouté, however, gained ownership of 60 percent of the Gucci Group’s stock in 2003. Women’s Wear Daily then announced the departure of both Domenico De Sole and Tom Ford from the Gucci Group when their contracts expired in April 2004. The last spring collection under the direction of Ford and De Sole was a critical and commercial success. Amid widespread speculation in the fashion press about Ford’s heir, the company announced in March 2004 that he would be replaced by a team of younger designers promoted from the ranks of the company’s staff.

In 2005, Frida Giannini was appointed as the creative director for women’s ready-to-wear and accessories, previously joining Gucci in 2002. In 2006, she also became the creative director for men's ready-to-wear and the entire Gucci label.

A turnaround of the company devised in the late 1980s made Gucci a global contender and notable fashion label. In October 1995 Gucci went public and had its first initial public offering on the AMEX and NYSE for $22 per share. November 1997 also proved to be a successful year as Gucci acquired a watch licensee, Severin-Montres, and renamed it Gucci Timepieces. The firm was named "European Company of the Year 1998" by the European Business Press Federation for its economic and financial performance, strategic vision as well as management quality. Gucci world offices and headquarters are in Florence, Milan, Paris, London, Hong Kong, Japan, and New York. PPR headquarters are in Paris.

In 1989, Maurizio managed to persuade Dawn Mello, whose revival of New York's Bergdorf Goodman in the 1970s made her a star in the retail business, to join the newly formed Gucci Group as Executive Vice President and Creative Director Worldwide. At the helm of Gucci America was Domenico De Sole, a former lawyer who helped oversee Maurizio’s takeover of ten 1987 and 1989. The last addition to the creative team, which already included designers from Geoffrey Beene and Calvin Klein, was a young designer named Tom Ford.

Raised in Texas and New Mexico, he had been interested in fashion since his early teens but only decided to pursue a career as a designer after dropping out of Parsons School of Design in 1986 as an architecture major. Dawn Mello hired Ford in 1990 at the urging of his partner, writer and editor Richard Buckley.

In the early 1990s, Gucci underwent what is now recognized as the poorest time in the company's history. Maurizio riled distributors, Investcorp shareholders, and executives at Gucci America by drastically reining in on the sales of the Gucci Accessories Collection, which in the United States alone generated $110 million in revenue every year. The company’s new accessories failed to pick up the slack, and for the next three years the company experienced heavy losses and teetered on the edge of bankruptcy. Maurizio was a charming man who passionately loved his family's business, but after four years most of the company's senior managers agreed that he was incapable of running the company. His management had had an adverse effect on the desirability of the brand, product quality, and distribution control. He was forced to sell his shares in the company to Investcorp in August 1993. Dawn Mello returned to her job at Bergdorf Goodman less than a year after Maurizio’s departure, and the position of creative director went to Tom Ford, then just 32 years old. Ford had worked for years under the direction of Maurizio and Mello and wanted to take the company’s image in a new direction. De Sole, who had been elevated to President and Chief Executive Officer ofGucci Group NV, realized that if Gucci was to become a profitable company, it would require a new image, and so he agreed to pursue Ford’s vision.

In early 1999 the luxury goods conglomerate LVMH, headed by Bernard Arnault, increased its shareholdings in Gucci with a view to a takeover. Domenico De Sole was incensed by the news and declined Arnault’s request for a spot on the board of directors, where he would have access to Gucci’s confidential earnings reports, strategy meetings, and design concepts. De Sole reacted by issuing new shares of stock in an effort to dilute the value of Arnault’s holdings. He also approached French holding company Pinault-Printemps-Redoute (PPR) about the possibility of forming a strategic alliance. Francois Pinault, the company’s founder, agreed to the idea and purchased 37 million shares in the company, or a 40% stake. Arnault’s share was diluted to a paltry 20%, and a legal battle ensued to challenge the legitimacy of the new Gucci-PPR partnership, with the law firm of Skadden, Arps, Slate, Meagher & Flom representing Gucci. Courts in the Netherlands ultimately upheld the PPR deal, as it did not violate that country's business laws. The second largest shareholder is Crédit Lyonnais with 11%. As of September 2001 a settlement agreement was put into place between Gucci Group, LVMH, and PPR.

Following Ford's departure, Gucci Group retained three designers to continue the success of the company's flagship label: John Ray, Alessandra Facchinetti and Frida Giannini, all of whom had worked under Ford's creative direction. Facchinetti was elevated to Creative Director of Womenswear in 2004 and designed for two seasons before leaving the company. Ray served as Creative Director of Menswear for three years. 32-year-old Giannini, who had been responsible for designing men's and women's accessories, currently serves as Creative Director for the entire brand.

Frida Giannini, formerly Creative Director of accessories, is named sole Creative Director in 2006. In 2009, Patrizio di Marco replaces Mark Lee as CEO of Gucci.

Gucci’s president and chief executive officer Patrizio di Marco revealed that Gucci is set to launch a children’s line in June 2010. The line will initially be unveiled in Italy and to 40 stores around the world. Frida Giannini serves as the creative director of the line. Giannini has been applauded on her fresh, feminine take on contemporary fashion. Born in Rome in 1972 to an architect father and art history professor mother she studied fashion design at Rome's Fashion Academy. Once she completed her education she went on to apprentice at a small-scale fashion house. In 1997 Giannini began a career at fashion house Fendi, where after just three seasons of designing for ready-to-wear she was promoted to designer of leather goods. In 2002 she moved to Gucci as director of handbags, and in 2004 was promoted to designer of all accessories. A year later in 2005 the designer was promoted to creative director of women's ready-to-wear at Gucci, in addition to her role as designer of accessories. In 2006 Giannini was named creative director of the label when she became responsible for design of menswear. In addition to clothing design, she has also developed retail concepts for Gucci stores, and creative control of advertising.

Aldo Gucci expanded into new markets including an agreement with American Motors Corporation (AMC). The 1972 and 1973 AMC Hornet compact "Sportabout" station wagon became one of the first American cars to offer a special luxury trim package created by a famous fashion designer. The Gucci cars sported boldly striped green, red, and buff upholstery and on the door panels, as well as the designer's emblems and exterior color selections. American Motors also offered a Pierre Cardin Edition of its Javelin automobile.

In 1979 and 1980, a Miami-based aftermarket company offered the Cadillac Seville by Gucci edition. The exterior included a "facing double G" Gucci logo, an emblem actually featuring Guccio Gucci’s initials, as a hood ornament and the c-pillar covered vinyl roof. The interior had a headliner of the logo and headrests adorned with the logo as well. The dashboard carried the "Gucci script" logo in bold lettering. Inside the trunk was a full set of Gucci luggage.

A 1989 Gucci Series Lincoln Town Car was scheduled to be offered, per pricing guides, but never came to fruition. Lincoln offered Emilio Pucci, Bill Blass, Gianni Versace, Hubert de Givenchy, and Valentino designer editions during the 1970s and 1980s.

Gucci has had a partnership with UNICEF since 2005. Gucci stores worldwide donate a percentage of the sales for special collections made specifically for UNICEF to go toward the United Nations Children's Fund. The annual Gucci Campaign to Benefit UNICEF supports education, healthcare, protection and clean water programs for orphans and children affected by HIV/AIDS in sub-Saharan Africa. For the campaign in 2009, Michael Roberts promoted a children's book, "Snowman in Africa" with proceeds going to UNICEF. In five years, Gucci donated over $7 million to UNICEF. Gucci is the largest corporate donor to UNICEF's "Schools for Africa" that was established in 2004 by UNICEF, the Nelson Mandela Foundation, and the Hamburg Society. Its goal is to increase access to basic schooling for all, with a special emphasis on children orphaned by HIV/AIDS and children living in extreme poverty.

Turbine | Understanding and definition of Turbine | Types of turbines

A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.

The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and impart rotational energy to the rotor. Early turbine examples are windmills and water wheels.

Gas, steam, and water turbines usually have a casing around the blades that contains and controls the working fluid. Credit for invention of the steam turbine is given both to the British engineer Sir Charles Parsons (1854–1931), for invention of the reaction turbine and to Swedish engineer Gustaf de Laval (1845–1913), for invention of the impulse turbine. Modern steam turbines frequently employ both reaction and impulse in the same unit, typically varying the degree of reaction and impulse from the blade root to its periphery.

A device similar to a turbine but operating in reverse, i.e., driven, is a compressor or pump. The axial compressor in many gas turbine engines is a common example. Here again, both reaction and impulse are employed and again, in modern axial compressors, the degree of reaction and impulse typically vary from the blade root to its periphery.

Claude Burdin coined the term from the Latin turbo, or vortex, during an 1828 engineering competition. Benoit Fourneyron, a student of Claude Burdin, built the first practical water turbine.

A working fluid contains potential energy (pressure head) and kinetic energy (velocity head). The fluid may be compressible or incompressible. Several physical principles are employed by turbines to collect this energy:

Impulse turbines

These turbines change the direction of flow of a high velocity fluid or gas jet. The resulting impulse spins the turbine and leaves the fluid flow with diminished kinetic energy. There is no pressure change of the fluid or gas in the turbine blades (the moving blades), as in the case of a steam or gas turbine, all the pressure drop takes place in the stationary blades (the nozzles).

Before reaching the turbine, the fluid's pressure head is changed to velocity head by accelerating the fluid with a nozzle. Pelton wheels and de Laval turbines use this process exclusively. Impulse turbines do not require a pressure casement around the rotor since the fluid jet is created by the nozzle prior to reaching the blading on the rotor. Newton's second law describes the transfer of energy for impulse turbines.

Reaction turbines

These turbines develop torque by reacting to the gas or fluid's pressure or mass. The pressure of the gas or fluid changes as it passes through the turbine rotor blades. A pressure casement is needed to contain the working fluid as it acts on the turbine stage(s) or the turbine must be fully immersed in the fluid flow (such as with wind turbines). The casing contains and directs the working fluid and, for water turbines, maintains the suction imparted by the draft tube. Francis turbines and most steam turbines use this concept. For compressible working fluids, multiple turbine stages are usually used to harness the expanding gas efficiently. Newton's third law describes the transfer of energy for reaction turbines.

In the case of steam turbines, such as would be used for marine applications or for land-based electricity generation, a Parsons type reaction turbine would require approximately double the number of blade rows as a de Laval type impulse turbine, for the same degree of thermal energy conversion. Whilst this makes the Parsons turbine much longer and heavier, the overall efficiency of a reaction turbine is slightly higher than the equivalent impulse turbine for the same thermal energy conversion.

Steam turbines and later, gas turbines developed continually during the 20th Century, continue to do so and in practice, modern turbine designs use both reaction and impulse concepts to varying degrees whenever possible. Wind turbines use an airfoil to generate lift from the moving fluid and impart it to the rotor (this is a form of reaction). Wind turbines also gain some energy from the impulse of the wind, by deflecting it at an angle. Crossflow turbines are designed as an impulse machine, with a nozzle, but in low head applications maintain some efficiency through reaction, like a traditional water wheel. Turbines with multiple stages may utilize either reaction or impulse blading at high pressure. Steam Turbines were traditionally more impulse but continue to move towards reaction designs similar to those used in Gas Turbines. At low pressure the operating fluid medium expands in volume for small reductions in pressure. Under these conditions (termed Low Pressure Turbines) blading becomes strictly a reaction type design with the base of the blade solely impulse. The reason is due to the effect of the rotation speed for each blade. As the volume increases, the blade height increases, and the base of the blade spins at a slower speed relative to the tip. This change in speed forces a designer to change from impulse at the base, to a high reaction style tip.

Classical turbine design methods were developed in the mid 19th century. Vector analysis related the fluid flow with turbine shape and rotation. Graphical calculation methods were used at first. Formulae for the basic dimensions of turbine parts are well documented and a highly efficient machine can be reliably designed for any fluid flow condition. Some of the calculations are empirical or 'rule of thumb' formulae, and others are based on classical mechanics. As with most engineering calculations, simplifying assumptions were made.

Types of turbines

• Steam turbines are used for the generation of electricity in thermal power plants, such as plants using coal, fuel oil or nuclear power. They were once used to directly drive mechanical devices such as ships' propellers (e.g. the Turbinia), but most such applications now use reduction gears or an intermediate electrical step, where the turbine is used to generate electricity, which then powers an electric motor connected to the mechanical load. Turbo electric ship machinery was particularly popular in the period immediately before and during WWII, primarily due to a lack of sufficient gear-cutting facilities in US and UK shipyards.
• Gas turbines are sometimes referred to as turbine engines. Such engines usually feature an inlet, fan, compressor, combustor and nozzle (possibly other assemblies) in addition to one or more turbines.
• Transonic turbine. The gasflow in most turbines employed in gas turbine engines remains subsonic throughout the expansion process. In a transonic turbine the gasflow becomes supersonic as it exits the nozzle guide vanes, although the downstream velocities normally become subsonic. Transonic turbines operate at a higher pressure ratio than normal but are usually less efficient and uncommon.
• Contra-rotating turbines. With axial turbines, some efficiency advantage can be obtained if a downstream turbine rotates in the opposite direction to an upstream unit. However, the complication can be counter-productive. A contra-rotating steam turbine, usually known as the Ljungström turbine, was originally invented by Swedish Engineer Fredrik Ljungström (1875–1964), in Stockholm and in partnership with his brother Birger Ljungström he obtained a patent in 1894. The design is essentially a multi-stage radial turbine (or pair of 'nested' turbine rotors) offering great efficiency, four times as large heat drop per stage as in the reaction (Parsons) turbine, extremely compact design and the type met particular success in backpressure power plants. However, contrary to other designs, large steam volumes are handled with difficulty and only a combination with axial flow turbines (DUREX) admits the turbine to be built for power greater than ca 50 MW. In marine applications only about 50 turbo-electric units were ordered (of which a considerable amount were finally sold to land plants) during 1917-19, and during 1920-22 a few turbo-mechanic not very successful units were sold. Only a few turbo-electric marine plants were still in use in the late 1960s (ss Ragne, ss Regin) while most land plants remain in use 2010.
• Statorless turbine. Multi-stage turbines have a set of static (meaning stationary) inlet guide vanes that direct the gasflow onto the rotating rotor blades. In a statorless turbine the gasflow exiting an upstream rotor impinges onto a downstream rotor without an intermediate set of stator vanes (that rearrange the pressure/velocity energy levels of the flow) being encountered.
• Ceramic turbine. Conventional high-pressure turbine blades (and vanes) are made from nickel based alloys and often utilise intricate internal air-cooling passages to prevent the metal from overheating. In recent years, experimental ceramic blades have been manufactured and tested in gas turbines, with a view to increasing Rotor Inlet Temperatures and/or, possibly, eliminating aircooling. Ceramic blades are more brittle than their metallic counterparts, and carry a greater risk of catastrophic blade failure. This has tended to limit their use in jet engines and gas turbines, to the stator (stationary) blades.
• Shrouded turbine. Many turbine rotor blades have shrouding at the top, which interlocks with that of adjacent blades, to increase damping and thereby reduce blade flutter. In large land-based electricity generation steam turbines, the shrouding is often complemented, especially in the long blades of a low-pressure turbine, with lacing wires. These wires pass through holes drilled in the blades at suitable distances from the blade root and are usually brazed to the blades at the point where they pass through. Lacing wires reduce blade flutter in the central part of the blades. The introduction of lacing wires substantially reduces the instances of blade failure in large or low-pressure turbines.
• Shroudless turbine. Modern practice is, wherever possible, to eliminate the rotor shrouding, thus reducing the centrifugal load on the blade and the cooling requirements.
• Bladeless turbine uses the boundary layer effect and not a fluid impinging upon the blades as in a conventional turbine.
• Water turbines : Pelton turbine, a type of impulse water turbine.,Francis turbine, a type of widely used water turbine., Kaplan turbine, a variation of the Francis Turbine.
• Wind turbine. These normally operate as a single stage without nozzle and interstage guide vanes. An exception is the Éolienne Bollée, which has a stator and a rotor, thus being a true turbine.

Almost all electrical power on Earth is produced with a turbine of some type. Very high efficiency steam turbines harness about 40% of the thermal energy, with the rest exhausted as waste heat.

Most jet engines rely on turbines to supply mechanical work from their working fluid and fuel as do all nuclear ships and power plants.

Turbines are often part of a larger machine. A gas turbine, for example, may refer to an internal combustion machine that contains a turbine, ducts, compressor, combustor, heat-exchanger, fan and (in the case of one designed to produce electricity) an alternator. Combustion turbines and steam turbines may be connected to machinery such as pumps and compressors, or may be used for propulsion of ships, usually through an intermediate gearbox to reduce rotary speed.

Reciprocating piston engines such as aircraft engines can use a turbine powered by their exhaust to drive an intake-air compressor, a configuration known as a turbocharger (turbine supercharger) or, colloquially, a "turbo".

Turbines can have very high power density (i.e. the ratio of power to weight, or power to volume). This is because of their ability to operate at very high speeds. The Space Shuttle's main engines use turbopumps (machines consisting of a pump driven by a turbine engine) to feed the propellants (liquid oxygen and liquid hydrogen) into the engine's combustion chamber. The liquid hydrogen turbopump is slightly larger than an automobile engine (weighing approximately 700 lb) and produces nearly 70,000 hp (52.2 MW).

An emerging renewable energy technology is the shrouded tidal turbine enclosed in a venturi shaped shroud or duct producing a sub atmosphere of low pressure behind the turbine. It is often claimed that this allows the turbine to operate at higher efficiency (than the Betz limit of 59.3%) because the turbine can typically produce 3 times more power than a turbine of the same size in free stream. This, however, is something of a misconception because the area presented to the flow is that of the largest duct cross-section. If this area is used for the calculation, it shows that the turbine still cannot exceed the Betz limit. Further, due to frictional losses in the duct, it is unlikely that the turbine will produce as much power as a free-stream turbine with the same radius as the duct.

As shown in the CFD generated figure, it can be seen that a down stream low pressure (shown by the gradient lines) draws upstream flow into the inlet of the shroud from well outside the inlet of the shroud. This flow is drawn into the shroud and concentrated (as seen by the red coloured zone). This augmentation of flow velocity corresponds to a 3-4 times increase in energy available to the turbine. Therefore a turbine located in the throat of the shroud is then able to achieve higher efficiency, and an output 3-4 times the energy the turbine would be capable of if it were in open or free stream. However, as mentioned above, it is not correct to conclude that this circumvents the Betz limit. The figure shows only the near-field flow, which is accelerated through the duct. A far-field image would show a more complete picture of how the free-stream flow is affected by the obstruction.

Considerable commercial interest has been shown in recent times in shrouded tidal turbines as it allows a smaller turbine to be used at sites where large turbines are restricted. Arrayed across a seaway or in fast flowing rivers shrouded tidal turbines are easily cabled to a terrestrial base and connected to a grid or remote community. Alternatively the property of the shroud that produces an accelerated flow velocity across the turbine allows tidal flows formerly too slow for commercial use to be utilised for commercial energy production.

Razor | History and definition Razor | Razor type and shape

A razor is a bladed tool primarily used in the removal of unwanted body hair through the act of shaving.

Razors have been identified from many Bronze Age cultures. These were made of bronze or obsidian and were generally oval in shape, with a small tang protruding from one of the short ends.

Various forms of razors were used throughout history, which are different in appearance but similar in use to modern straight razors. In prehistoric times clam shells, shark's teeth, and flint were sharpened and used to shave with. Drawings of such blades were found in prehistoric caves. Some tribes still use blades made of flint to this day. Excavations in Egypt have unearthed solid gold and copper razors in tombs dating back to the 4th millennium BCE. The Roman historian Livy reported that the razor was introduced in ancient Rome in the 6th century BCE. by legendary king Lucius Tarquinius Priscus. Priscus was ahead of his time because razors did not come to general use until a century later.

The first modern straight razor complete with decorated handles and hollow ground blades was constructed in Sheffield, in England, the centre of the cutlery industry, in the 18th and 19th centuries. Benjamin Huntsman produced the first superior hard steel grade, through a special crucible process, suitable for use as blade material in 1740. Huntsman's process was adopted by the French sometime later; albeit reluctantly at first due to nationalist sentiments. The English manufacturers were even more reluctant than the French to adopt the process and only did so after they saw its success in France. Sheffield steel, a highly polished steel, also known as Sheffield silver steel' and famous for its deep gloss finish, is considered a superior quality steel and is still used to this day in France by such manufacturers as Thiers Issard.

In the 18th and 19th centuries the wealthy had servants to shave them or could frequent barbershops. Daily shaving was not a widespread practice in the 19th century so some people never shaved. The custom of shaving every day among American men is a 20th century innovation. In the 19th century, cutlers in Sheffield, England and Solingen, Germany produced a variety of razors.

Straight razors were the most common form of shaving before the 20th century and remained that common in many countries until the 1950s. Barbers were specially trained to give customers a thorough and quick shave, and a collection of straight razors ready for use was a common sight in most barbershops. Barbers still have them, but they use them less often.

Straight razors eventually fell out of fashion. Their first challenger was manufactured by King C. Gillette: a double-edged safety razor with replaceable blades. Gillette's idea was the use of the "loss leader" concept, in which the razors were sold at a loss, but the replacement blades earned a high margin and provided continuous sales. They provided a less effective shave, yet were immensely successful due to advertising campaigns and slogans denigrating the straight razor's effectiveness and questioning its safety.

These new safety razors did not require any serious tutelage to use. The blades were extremely hard to sharpen, and were meant to be thrown away after one use, and rusted quickly if not discarded. They also required a smaller initial investment, though they cost more over time. Despite its long-term advantages, the straight razor lost significant market share. And as shaving became less intimidating and men began to shave themselves more, the demand for barbers providing straight razor shaves decreased.

Around 1960, stainless steel blades which could be used more than once became available, reducing the cost of safety-razor shaving. The first such blades were made by the Wilkinson firm, famous maker of ceremonial swords, in Sheffield. Soon Gillette, Schick, and other manufacturers were making stainless-steel blades.

These were followed by multiple-blade cartridges and disposable razors. For each type of replaceable blade, there is generally a disposable razor.

In the 1930s, electric razors became available. These can rival the cost of a good straight razor, although the whole straight-razor shaving kit can exceed the cost of even an expensive electric razor.

Straight razors with open steel blades, also commonly known as cut-throats, were the most commonly used razors before the 20th century. However, they are now chiefly used by barbers.

Straight razors consist of a blade sharpened on one edge. The blade can be made of either stainless steel, which is slower to hone and strop, and holds an edge longer, or high carbon steel, which hones and strops quickly, but has a less durable edge. At present, stainless-steel razors are harder to find than carbon steel, but both are still in production.

The blade rotates on a pin through its tang between two protective pieces called scales: when folded into the scales, the blade is protected from damage, and the user is protected from injury. Handle scales are made of various materials, including mother-of-pearl, celluloid, bone, plastic and wood. They were once made of ivory, but this has been discontinued, though fossil ivory is still used occasionally.

Razors which are similar in use and appearance to straight razors but which use either a standard double edged blade or specially made blades are available.

Disposable bladed straights have many of the advantages of straight razors without needing the stropping and honing of ordinary straight razors.

Disposable razors can be resharpened.

The first safety razor protected the skin from all but the very edge of the blade and was invented in the late 19th century by a Frenchman, Jean-Jacques Perret, who was inspired by the joiner's plane. In 1875 it was marketed by the Kampfe Brothers as "the best available shaving method on the market that won’t cut a user, like straight steel razors."

In 1901, the American inventor King Camp Gillette, with the assistance of William Nickerson, invented a safety razor with disposable blades. Gillette realized that a profit could be made by selling an inexpensive razor with disposable blades. This has been called the Razor and blades business model, or a "loss leader", and has become a very common practice for a wide variety of products.

There are also safety razors that are made of inexpensive materials that are meant to be wholly disposable. One such device was patented in the late 1950s by American entertainer and inventor Paul Winchell.

The electric razor (also known as the electric dry shaver) has a rotating or oscillating blade. The electric razor usually does not require the use of shaving cream, soap, or water. The razor may be powered by a small DC motor, which is either powered by batteries or mains electricity. Many modern ones are powered using rechargeable batteries. Alternatively, an electro-mechanical oscillator driven by an AC-energized solenoid may be used. Some very early mechanical shavers had no electric motor and had to be powered by hand, for example by pulling a cord to drive a flywheel.

The first electric razor was patented in 1928 by the American manufacturer Col. Jacob Schick. The Remington Rand Corporation developed the electric razor further, first producing the Remington brand of razor in 1937. Another important inventor was Prof. Alexandre Horowitz, from Philips Laboratories in the Netherlands, who invented the very successful concept of the revolving (rotary) electric razor. It has a shaving head consisting of cutters that cut off the hair entering the head of the razor at skin level. The major manufacturers introduce new improvements to the hair cutting mechanism of their products each few years. Each manufacturer sells several different generations of cutting mechanism at the same time, and for each generation, several models with different features and accessories to reach various price points. The improvements to the cutting mechanisms tend to 'trickle-down' to lower priced models over time.

Early versions of electric razors were meant to be used on dry skin only. Many recent electric razors have been designed to allow for wet/dry use, which also allows them to be cleaned using running water or an included cleaning machine, reducing cleaning effort. Some patience is necessary when starting to use a razor of this type, as the skin usually takes some time to adjust to the way that the electric razor lifts and cuts the hairs. Moisturizers designed specifically for electric shaving are available.

Until recently, most electric razors plugged directly into an AC outlet, but in recent years many contained rechargeable batteries sealed inside the razor's case. Most of these batteries are nickel cadmium or nickel metal hydride batteries, sometimes soldered in place.

Some modern styles of electric hair clippers include bulk hair clippers, which are used to remove a bulk of the hair being shaved; main hair clippers, on which guards are attached to achieve a perfect length all over the head; and mini clippers, which are used to trim the edges of the haircut.

Spare tire | Understanding and definition of Spare tire | Usefulness and benefits of Spare tire

A spare tire is an additional tire (or tyre - see spelling differences) carried in a motor vehicle as a replacement for one that goes flat, a blowout, or other emergency. Spare tire is generally a misnomer, as almost all vehicles actually carry an entire wheel as a spare, as fitting a tire to a wheel is very difficult without specialised equipment, and is not practical in an emergency. However, some spare tires ("space-saver" and "donut" types) are not meant to be driven long distances and most of them have maximum speed of around 50 mph (80 km/h).

The early days of motor travel took place on primitive roads that were littered with stray horseshoe nails. Punctures (flat tires) were all too common, and required the motorist to remove the wheel from the car, demount the tire, patch the inner tube, re-mount the tire, inflate the tire, and re-mount the wheel. The first to equip cars with a spare wheel-and-tire assembly were the Ramblers made by Thomas B. Jeffery Company. The Rambler's interchangeable wheel and mounted spare tire meant the motorist could quickly exchange it for the flat one. The punctured tire could then be repaired at a more convenient time and place.

The pre-mounted spare tire and wheel combination proved so popular with motorists that carrying up to two spare tires became common. Automakers often equipped cars with one or dual sidemounts. The spares were mounted behind the front fenders as they blended into the running boards (a narrow footboard serving as a step beneath the doors).

In 1941, the U.S. government prohibited spare tires on new cars. Shortages of resources caused by World War II led to quotas and laws designed to force conservation, including rubber that was produced overseas and difficult to get. A similar ban was also implemented by the U.S. during the Korean War in 1951.

Contemporary vehicles may come equipped with full-size spares, limited use minispares, or have run-flat capability.

• The spare tire may be identical type and size to those on the vehicle. The spare may either be mounted on a plain steel rim or a matching road wheel as found on the vehicle. Among passenger vehicles, full-sized spares are usually provided for sport utility vehicles and light trucks, since a "limited use" spare would adversely affect such vehicles with higher centers of gravity. Due to the size of the full-sized spare, it is often mounted on the outside, such as the rear door of SUVs, and occasionally on the front hood.
• Certain vehicles are provided with a "limited use" spare tire, also known as "spacesaver" or "compact" spare tire — in an attempt to reduce cost, lower the vehicle's weight, and/or to save on the space that would be needed for a full-size spare tire. The spare is usually mounted on a plain steel rim. They are typically smaller than the normal tires on the vehicle and can only be used for limited distances because of their short life expectancy and low speed rating. As well, due to the different size of a donut compared to regular wheel, electronic stability control and traction control systems will not operate properly and should be disabled until the original wheel is restored.
• In some cases, automobiles may be equipped with run-flat tires and thus not require a separate spare tire. Other vehicles may carry a can of tire repair foam, to repair punctured tires, although these often do not work in the case of larger punctures, and are useless in the event of a blow-out.

Spare tires in automobiles are often stored in a spare tire well – a recessed area in the trunk of a vehicle, usually in the center, where the spare tire is stored while not in use. In most cars, the spare tire is secured with a bolt and wing-nut style fastener. Usually a stiff sheet of cardboard lies on top of the spare tire well with the trunk carpet on top of it to hide the spare tire and provide a pleasant look to and a flat surface for the trunk space.

Other storage solutions include storing the spare in a cradle underneath the rear of the vehicle. This cradle is usually secured by a bolt that is accessible from inside the trunk, for security. This arrangement has several advantages over storing the tire inside the trunk, chiefly that it is not necessary to empty the contents of the trunk in order to access the wheel. The arrangement may also save space in some applications; however it has disadvantages too, such as the fact that the tire gets very dirty, making the act of changing the tire more unpleasant. The mechanism may also rust on older cars, making it very difficult to free the spare. The cradle arrangement is usually only practical on front wheel drive cars, as the cradle would get in the way of the rear axle on most rear or four wheel drive cars. A similar arrangement is also often found on trucks where the spare is often stored beneath the truck bed.

Many SUVs and off-road vehicles have the spare wheel mounted externally – usually on the rear door, but others may mount them on the bonnet, the side or even the roof.

In mid-engined and rear-engined cars the spare tire is generally stored in the front boot and a dedicated spare tire well is seldom used.

Some vehicles stored the spare tire in the engine bay, such as the Renault 14 and older Subaru vehicles, such as the Subaru Leone.

Vehicles like the Volkswagen Beetle used spare tires for ancillary purposes such as supplying air pressure for a utility system.