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اقدم اجمل التهاني والتبريكات إلى كل الأصدقاء وان شاء الله من عواده وعيد سعيد
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An oil tanker, also known as a petroleum tanker, is a merchant ship designed for the bulk transport of oil. There are two basic types of oil tankers: the crude tanker and the product tanker. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries. Product tankers, generally much smaller, are designed to move refined products from refineries to points near consuming markets.

Oil tankers are often classified by their size as well as their occupation. The size classes range from inland or coastal tankers of a few thousand metric tons of deadweight (DWT) to the mammoth ultra large crude carriers (ULCCs) of 550,000 DWT. Tankers move approximately 2,000,000,000 metric tons (2.2×109 short tons) of oil every year. Second only to pipelines in terms of efficiency, the average cost of oil transport by tanker amounts to only two or three United States cents per 1 US gallon (3.8 L).

Some specialized types of oil tankers have evolved. One of these is the naval replenishment oiler, a tanker which can fuel a moving vessel. Combination ore-bulk-oil carriers and permanently moored floating storage units are two other variations on the standard oil tanker design. Oil tankers have been involved in a number of damaging and high-profile oil spills. As a result, they are subject to stringent design and operational regulations.

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The Boeing 747 is a wide-body commercial airliner and cargo transport aircraft, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft and was the first wide-body produced. Manufactured by Boeing's Commercial Airplane unit in the United States, the original version of the 747 was two and a half times larger in capacity than the Boeing 707, one of the common large commercial aircraft of the 1960s. First flown commercially in 1970, the 747 held the passenger capacity record for 37 years.

The four-engine 747 uses a double deck configuration for part of its length. It is available in passenger, freighter and other versions. Boeing designed the 747's hump-like upper deck to serve as a first class lounge or extra seating, and to allow the aircraft to be easily converted to a cargo carrier by removing seats and installing a front cargo door. Boeing did so because the company expected supersonic airliners (development of which was announced in the early 1960s) to render the 747 and other subsonic airliners obsolete, while the demand for subsonic cargo aircraft would be robust well into the future. The 747 was expected to become obsolete after 400 were sold, but it exceeded critics' expectations with production passing the 1,000 mark in 1993. By April 2014, 1,487 aircraft had been built, with 51 of the 747-8 variants remaining on order.

The 747-400, the most common passenger version in service, has a high-subsonic cruise speed of Mach 0.85–0.855 (up to 570 mph or 920 km/h) with an intercontinental range of 7,260 nautical miles (8,350 mi or 13,450 km). The 747-400 passenger version can accommodate 416 passengers in a typical three-class layout, 524 passengers in a typical two-class layout, or 660 passengers in a high density one-class configuration. The newest version of the aircraft, the 747-8, is in production and received certification in 2011. Deliveries of the 747-8F freighter version to launch customer Cargolux began in October 2011; deliveries of the 747-8I passenger version to Lufthansa began in May 2012. The 747 is to be replaced by the Boeing Y3 (part of the Boeing Yellowstone Project) in the future.

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An airship or dirigible is a type of aerostat or lighter-than-air aircraft which can navigate through the air under its own power. Aerostats gain their lift from large gas bags filled with a lifting gas that is less dense than the surrounding air.

In early dirigibles, the lifting gas used was hydrogen, due to its high lifting capacity and ready availability. Helium gas has almost the same lifting capacity and is also nonflammable, but is rare and relatively expensive. Significant amounts were first discovered in the United States and, for a while, helium was rarely used for airships outside the United States. Most airships built since the 1960s have used helium, though some have used hot air.

The outer envelope of an airship may be formed from its single gas bag, or may be a separate supported skin. Besides the main envelope, an airship also has engines and crew and/or payload accommodation, typically in a gondola hung beneath the envelope.

The main types of airship are non-rigid, semi-rigid, and rigid. Non-rigid airships, often called "blimps", rely on internal pressure to maintain the shape of the airship. Semi-rigid airships maintain the envelope shape by internal pressure, but have some form of supporting structure, such as a fixed keel, attached to it. Rigid airships have an outer structural framework which maintains the shape and carries all structural loads, while the lifting gas is contained in one or more internal gas bags or cells. Rigid airships were first flown by Count Zeppelin and the vast majority of rigid airships built were manufactured by the firm he founded. As a result, all rigid airships are sometimes called zeppelins.

Airships were the first aircraft capable of controlled powered flight, and were most commonly used before the 1940s, but their use decreased over time as their capabilities were surpassed by those of aeroplanes. Their decline was accelerated by a series of high-profile accidents, including the 1930 crash and burning of British R101 in France, the 1933 storm-related crash of the USS Akron and the 1937 burning of the hydrogen-filled Hindenburg. From the 1960s, helium airships have been used in applications where the ability to hover in one place for an extended period outweighs the need for speed and maneuverability such as advertising, tourism, camera platforms, geological surveys, and aerial observation.

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A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes) are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are often used in conjunction with dams to generate electricity. A dam can also be used to collect water or for storage of water which can be evenly distributed between locations.

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November 16, 2004 The US Marine Corps' first 4x4 hybrid-electric tactical vehicle - the Shadow RST-V - has been tested by the Office of Naval Research (ONR) and the Defence Advanced Research Projects Agency (DARPA) and may soon challenge the Humvee as the dominant vehicle for military use. The Reconnaissance, Surveillance and Targeting Vehicle (RST-V) is a high mobility, electric drive technology demonstrator that incorporates a lightweight diesel engine coupled to a permanent-magnetic generator which drives four in-hub permanent-magnet electric wheel motors. The Shadow is ideally suited as a reconnaissance vehicle, as its lithium-ion battery pack enables silent movement for upwards of 20 miles with extremely low thermal and acoustic signatures.

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The Sen Toku I-400-class Imperial Japanese Navy submarines were the largest submarines of World War II and remained the largest ever built until the construction of nuclear ballistic missile submarines in the 1960s. They were submarine aircraft carriers able to carry three Aichi M6A Seiran aircraft underwater to their destinations. They were designed to surface, launch their planes, then quickly dive again before they were discovered. They also carried torpedoes for close-range combat.

The I-400-class was designed with the range to travel anywhere in the world and return. A fleet of 18 boats was planned in 1942, and work started on the first in January 1943 at the Kure, Hiroshima arsenal. Within a year the plan was scaled back to five, of which only three (I-400 at Kure, and I-401 and I-402 at Sasebo) were completed.

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NIST-F1 is a cesium fountain clock, a type of atomic clock, in the National Institute of Standards and Technology (NIST) in Boulder, Colorado, and serves as the United States' primary time and frequency standard. The clock took less than four years to test and build, and was developed by Steve Jefferts and Dawn Meekhof of the Time and Frequency Division of NIST's Physical Measurement Laboratory.

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The Northrop Grumman B-2 Spirit, also known as the Stealth Bomber, is an American strategic bomber, featuring low observable stealth technology designed for penetrating dense anti-aircraft defenses; it is able to deploy both conventional and nuclear weapons. The bomber has a crew of two and can drop up to eighty 500 lb (230 kg)-class JDAM GPS-guided bombs, or sixteen 2,400 lb (1,100 kg) B83 nuclear bombs. The B-2 is the only aircraft that can carry large air-to-surface standoff weapons in a stealth configuration.

Because of its considerable capital and operating costs, the project was controversial in the U.S. Congress and among the Joint Chiefs of Staff. The winding-down of the Cold War in the latter portion of the 1980s dramatically reduced the need for the aircraft, which was designed with the intention of penetrating Soviet airspace and attacking high-value targets. During the late 1980s and 1990s, Congress slashed plans to purchase 132 bombers to 21. In 2008, a B-2 was destroyed in a crash shortly after takeoff, and the crew ejected safely. A total of 20 B-2s remain in service with the United States Air Force, who plan to operate the B-2 until 2058.

The B-2 is capable of all-altitude attack missions up to 50,000 feet (15,000 m), with a range of more than 6,000 nautical miles (11,000 km) unrefuelled and over 10,000 nautical miles (19,000 km) with one refueling. Though originally designed primarily as a nuclear bomber, it was first used in combat to drop conventional bombs on Serbia during the Kosovo War in 1999, and saw continued use during the war in Iraq and in Afghanistan.

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Iron is a chemical element with the symbol Fe (from Latin: ferrum) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. Iron's very common presence in rocky planets like Earth is due to its abundant production as a result of fusion in high-mass stars.

Iron chemical compounds, which include ferrous and ferric compounds, have many uses. Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. It forms binary compounds with the halogens and the chalcogens. Among its organometallic compounds is ferrocene, the first sandwich compound discovered.

Iron plays an important role in biology, forming complexes with molecular oxygen in hemoglobin and myoglobin; these two compounds are common oxygen transport proteins in vertebrates. Iron is also the metal used at the active site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants and animals.
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