1.
Troopship
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A troopship is a ship used to carry soldiers, either in peacetime or wartime. Attack transports, a variant of ocean-going troopship adapted to transporting invasion forces ashore, landing ships beach themselves and bring their troops directly ashore. Ships to transport troops were used in Antiquity. Ancient Rome used the navis lusoria, a vessel powered by rowers and sail, to move soldiers on the Rhine. HMT Olympic even rammed and sank a U-boat during one of its wartime crossings, individual liners capable of exceptionally high speed transited without escorts, smaller or older liners with poorer performance were protected by operating in convoys. The British government aided both Cunard and the White Star Line to construct the liners RMS Mauretania, RMS Aquitania, RMS Olympic, when the vulnerability of these ships to return fire was realized most were used instead as troopship or hospital ships. RMS Queen Mary and RMS Queen Elizabeth were two of the most famous converted liners of World War II, when they were fully converted, each could carry well over 10,000 troops per trip. Queen Mary holds the record, with 15,740 troops on a single passage in late July 1943. The modified Liberties were capable of transporting up to 450,550,30 Type C4 ship-based General G. O. Squier-class, the largest carrying over 6,000 passengers. A class of Victory ship-based dedicated troopship was developed late in World War II, a total of 84 such VC2-S-AP2 hull conversions was completed. A class of Type C3 ship – comprising mainly C3-S-A2 and C3-S-A3 hulls – was also converted to dedicated troopships, at least 15 classes of Attack Transport, consisting of at least 400 ships specially equipped for landing invasion forces rather than general troop movement. The designation HMT would normally replace RMS, MV or SS for ships converted to troopship duty with the United Kingdoms Royal Navy, initially troopships adapted as attack transports were designated AP, starting in 1942 keel-up attack transports received the designation APA. In the era of the Cold War the United States designed the SS United States so that it could easily be converted from a liner to a troopship, in case of war. More recently, RMS Queen Elizabeth 2 and the SS Canberra were requisitioned by the Royal Navy to carry British soldiers to the Falklands War, by the end of the twentieth century, nearly all long-distance personnel transfer was done by airlift in military transport aircraft
2.
Propeller
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A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the blade, and a fluid is accelerated behind the blade. Their disadvantages are higher mechanical complexity and higher cost, the principle employed in using a screw propeller is used in sculling. It is part of the skill of propelling a Venetian gondola but was used in a less refined way in parts of Europe. For example, propelling a canoe with a paddle using a pitch stroke or side slipping a canoe with a scull involves a similar technique. In China, sculling, called lu, was used by the 3rd century AD. In sculling, a blade is moved through an arc. The innovation introduced with the propeller was the extension of that arc through more than 360° by attaching the blade to a rotating shaft. Propellers can have a blade, but in practice there are nearly always more than one so as to balance the forces involved. The origin of the screw propeller starts with Archimedes, who used a screw to lift water for irrigation and bailing boats and it was probably an application of spiral movement in space to a hollow segmented water-wheel used for irrigation by Egyptians for centuries. Leonardo da Vinci adopted the principle to drive his theoretical helicopter, in 1784, J. P. Paucton proposed a gyrocopter-like aircraft using similar screws for both lift and propulsion. At about the time, James Watt proposed using screws to propel boats. This was not his own invention, though, Toogood and Hays had patented it a century earlier, by 1827, Czech-Austrian inventor Josef Ressel had invented a screw propeller which had multiple blades fastened around a conical base. He had tested his propeller in February 1826 on a ship that was manually driven. He was successful in using his bronze screw propeller on an adapted steamboat and his ship Civetta with 48 gross register tons, reached a speed of about six knots. This was the first ship successfully driven by an Archimedes screw-type propeller, after a new steam engine had an accident his experiments were banned by the Austro-Hungarian police as dangerous. Josef Ressel was at the time a forestry inspector for the Austrian Empire, but before this he received an Austro-Hungarian patent for his propeller. This new method of propulsion was an improvement over the paddlewheel as it was not so affected by either ship motions or changes in draft as the burned coal
3.
Steam turbine
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A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Sir Charles Parsons in 1884, in 1551, Taqi al-Din in Ottoman Egypt described a steam turbine with the practical application of rotating a spit. Steam turbines were described by the Italian Giovanni Branca and John Wilkins in England. The devices described by Taqi al-Din and Wilkins are today known as steam jacks, in 1672 an impulse steam turbine driven car was designed by Ferdinand Verbiest. A more modern version of car was produced some time in the late 18th century by an unknown German mechanic. The modern steam turbine was invented in 1884 by Sir Charles Parsons, the invention of Parsons steam turbine made cheap and plentiful electricity possible and revolutionized marine transport and naval warfare. Parsons design was a reaction type and his patent was licensed and the turbine scaled-up shortly after by an American, George Westinghouse. The Parsons turbine also turned out to be easy to scale up. Parsons had the satisfaction of seeing his invention adopted for all major world power stations, a number of other variations of turbines have been developed that work effectively with steam. The de Laval turbine accelerated the steam to full speed before running it against a turbine blade, De Lavals impulse turbine is simpler, less expensive and does not need to be pressure-proof. It can operate with any pressure of steam, but is less efficient. He taught at the École des mines de Saint-Étienne for a decade until 1897, one of the founders of the modern theory of steam and gas turbines was Aurel Stodola, a Slovak physicist and engineer and professor at the Swiss Polytechnical Institute in Zurich. His work Die Dampfturbinen und ihre Aussichten als Wärmekraftmaschinen was published in Berlin in 1903, a further book Dampf und Gas-Turbinen was published in 1922. It was used in John Brown-engined merchant ships and warships, including liners, the present-day manufacturing industry for steam turbines is dominated by Chinese power equipment makers. Other manufacturers with minor market share include Bhel, Siemens, Alstom, GE, Doosan Škoda Power, Mitsubishi Heavy Industries, the consulting firm Frost & Sullivan projects that manufacturing of steam turbines will become more consolidated by 2020 as Chinese power manufacturers win increasing business outside of China. There are several classifications for modern steam turbines, Turbine blades are of two basic types, blades and nozzles. Blades move entirely due to the impact of steam on them and this results in a steam velocity drop and essentially no pressure drop as steam moves through the blades. A turbine composed of alternating with fixed nozzles is called an impulse turbine, Curtis turbine, Rateau turbine
4.
5"/38 caliber gun
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The Mark 12 5/38 caliber gun was a US naval gun. The gun was installed into Single Purpose and Dual Purpose mounts used primarily by the US Navy, the 38 caliber barrel was a mid-length compromise between the previous United States standard 5/51 low-angle gun and 5/25 anti-aircraft gun. The increased barrel length provided greatly improved performance in both anti-aircraft and anti-surface roles compared to the 5/25 gun, however, except for the barrel length and the use of semi-fixed ammunition, the 5/38 gun was derived from the 5/25 gun. Both weapons had power ramming, which enabled rapid fire at high angles against aircraft, the 5/38 entered service on USS Farragut, commissioned in 1934. The base ring mount, which improved the rate of fire, entered service on USS Gridley. Even this advanced system required nearly 100 rounds of ammunition expenditure per aircraft kill, however, the planes were normally killed by shell fragments and not direct hits, barrage fire was used, with many guns firing in the air at the same time. Base ring mounts with integral hoists had a rate of fire of 15 rounds per minute per barrel, however. On pedestal and other mounts lacking integral hoists,12 to 15 rounds per minute was the rate of fire, useful life expectancy was 4600 effective full charges per barrel. The 5/38 cal gun was mounted on a large number of US Navy ships in the World War II era. It was backfitted to many of the World War I-era battleships during their wartime refits and it has left active US Navy service, but it is still on mothballed ships of the United States Navy reserve fleets. It is also used by a number of nations who bought or were given US Navy surplus ships, each mount carries one or two Mk 12 5/38cal Gun Assemblies. The gun assembly shown is used in single mounts, and it is the gun in twin mounts. It is loaded from the left side, the left gun in twin mounts is the mirror image of the right gun, and it is loaded from the right side. The Mk12 gun assembly weighs 3,990 lb, the major Mk12 Gun Assembly characteristics are,158 Semi-automatic During recoil, some of the recoil energy is stored in the counter-recoil system. That stored energy is used during counter-recoil to prepare the gun for the next round, the firing pin is cocked, the breech is opened, the spent powder case is ejected, and the bore is air cleaned. Hand loaded A Projectile-Man and a Powder-Man are stationed at each gun assembly and their job is to move the round, consisting of a projectile and a powder case, from the hoists to the rammer tray, and then start the ram cycle. The hydraulically driven Rammer Spade, called the Power Spade in that picture, is at the back of the Rammer Tray, if the multiple names of the Spade is confusing, look at this footnote. Vertical sliding-wedge breech block The breech block closes the chamber behind the powder case and it also holds the firing pin assembly
5.
Bofors 40 mm gun
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The Bofors 40 mm gun, often referred to simply as the Bofors gun, is an anti-aircraft/multi-purpose autocannon designed in the 1930s by the Swedish arms manufacturer AB Bofors. It was one of the most popular medium-weight anti-aircraft systems during World War II, a small number of these weapons remain in service to this day, and saw action as late as the Gulf War. In the post-war era the original design was not suitable for action against jet powered aircraft, so Bofors introduced a new model of more power. In spite of sharing almost nothing with the design other than the calibre and the distinctive conical flash hider. Although not as popular as the original L/60 model, the L/70 remains in service to this day, especially as a weapon for light armored vehicles. Bofors itself has been part of BAE Systems AB since March 2005, the Swedish Navy purchased a number of 2 pounder Pom-Poms from Vickers as anti-aircraft guns in 1922. The Navy approached Bofors about the development of a capable replacement. Bofors signed a contract in late 1928, Bofors produced a gun that was a smaller version of a 57 mm semi-automatic gun developed as an anti-torpedo boat weapon in the late 19th century by Finspong. Their first test gun was a re-barreled Nordenfelt version of the Finspong gun, testing of this gun in 1929 demonstrated that a problem existed feeding the weapon in order to maintain a reasonable rate of fire. A mechanism that was enough to handle the stresses of moving the large round was too heavy to move quickly enough to fire rapidly. One attempt to solve this problem used zinc shell cases that burned up when fired and this proved to leave heavy zinc deposits in the barrel, and had to be abandoned. This seemed to be the solution they needed, improving firing rates to a level. During this period Krupp purchased a share of Bofors. Krupp engineers started the process of updating the Bofors factories to use equipment and metallurgy. The prototype was completed and fired in November 1931, and by the middle of the month it was firing strings of two and three rounds. Changes to the mechanism were all that remained, and by the end of the year it was operating at 130 rounds per minute. Continued development was needed to turn it into a suitable for production. Since acceptance trials had been passed the year before, this known as the 40 mm akan M/32
6.
Anti-aircraft warfare
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Anti-aircraft warfare or counter-air defence is defined by NATO as all measures designed to nullify or reduce the effectiveness of hostile air action. They include ground-and air-based weapon systems, associated sensor systems, command and control arrangements and it may be used to protect naval, ground, and air forces in any location. However, for most countries the main effort has tended to be homeland defence, NATO refers to airborne air defence as counter-air and naval air defence as anti-aircraft warfare. Missile defence is an extension of air defence as are initiatives to adapt air defence to the task of intercepting any projectile in flight, a surface-based air defence capability can also be deployed offensively to deny the use of airspace to an opponent. Until the 1950s, guns firing ballistic munitions ranging from 20 mm to 150 mm were the weapons, guided missiles then became dominant. The term air defence was probably first used by Britain when Air Defence of Great Britain was created as a Royal Air Force command in 1925. However, arrangements in the UK were also called anti-aircraft, abbreviated as AA, after the First World War it was sometimes prefixed by Light or Heavy to classify a type of gun or unit. Nicknames for anti-aircraft guns include AA, AAA or triple-A, an abbreviation of anti-aircraft artillery, ack-ack, NATO defines anti-aircraft warfare as measures taken to defend a maritime force against attacks by airborne weapons launched from aircraft, ships, submarines and land-based sites. In some armies the term All-Arms Air Defence is used for air defence by nonspecialist troops, other terms from the late 20th century include GBAD with related terms SHORAD and MANPADS. Anti-aircraft missiles are variously called surface-to-air missile, abbreviated and pronounced SAM, non-English terms for air defence include the German FlaK, whence English flak, and the Russian term Protivovozdushnaya oborona, a literal translation of anti-air defence, abbreviated as PVO. In Russian the AA systems are called zenitnye systems, in French, air defence is called DCA. The maximum distance at which a gun or missile can engage an aircraft is an important figure, however, many different definitions are used but unless the same definition is used, performance of different guns or missiles cannot be compared. For AA guns only the part of the trajectory can be usefully used. By the late 1930s the British definition was that height at which an approaching target at 400 mph can be engaged for 20 seconds before the gun reaches 70 degrees elevation. However, effective ceiling for heavy AA guns was affected by nonballistic factors, The maximum running time of the fuse, the capability of fire control instruments to determine target height at long range. The essence of air defence is to detect aircraft and destroy them. The critical issue is to hit a target moving in three-dimensional space, Air defence evolution covered the areas of sensors and technical fire control, weapons, and command and control. At the start of the 20th century these were very primitive or non-existent
7.
Oerlikon 20 mm cannon
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The Oerlikon 20 mm cannon is a series of autocannons, based on an original German 20 mm Becker design that appeared very early in World War I. It was widely produced by Oerlikon Contraves and others, with various models employed by both Allied and Axis forces during World War II, and many still in use today. During World War I, the German Reinhold Becker developed a 20 mm caliber cannon and this used a 20x70 RB cartridge and had a cyclic rate of fire of 300 rpm. It was used on a scale as an aircraft gun on Luftstreitkräfte warplanes. Because the Treaty of Versailles banned further production of weapons in Germany. SEMAG continued development of the weapon, and in 1924 had produced the SEMAG L, the Oerlikon firm, named after the Zürich suburb where it was based, then acquired all rights to the weapon, plus the manufacturing equipment and the employees of SEMAG. In 1927 the Oerlikon S was added to the product line. This fired a larger cartridge to achieve a muzzle velocity of 830 m/s, at the cost of increased weight. The purpose of development was to improve the performance of the gun as an anti-tank and anti-aircraft weapon. An improved version known as the 1S followed in 1930, three sizes of gun with their different ammunition and barrel length, but very similar mechanisms, continued to be developed in parallel. In 1930 Oerlikon reconsidered the application of its gun in aircraft and introduced the AF and AL, designed to be used in flexible mounts, the 15-round box magazine used by earlier versions of the gun was replaced by drum magazine holding 15 or 30 rounds. In 1935 it made an important step by introducing a series of guns designed to be mounted in or on the wings of fighter aircraft, designated with FF for Flügelfest meaning wing-mounted, these weapons were again available in the three sizes, with designations FF, FFL and FFS. The FF fired a larger cartridge than the AF, 20x72RB. The FF weighed 24 kg and achieved a velocity of 550 to 600 m/s with a rate of fire of 520 rpm. The FFL of 30 kg fired a projectile at a velocity of 675 m/s with a rate of fire of 500 rpm. And the FFS, which weighed 39 kg, delivered a high velocity of 830 m/s at a rate of fire of 470 rpm. Apart from changes to the design of the guns for wing-mounting and remote control, for the FF series drum sizes of 45,60,75 and 100 rounds were available, but most users chose the 60-round drum. The 1930s were a period of global re-armament, and a number of foreign firms took licenses for the Oerlikon family of aircraft cannon
8.
Type C4-class ship
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The Type C4 class ship were the largest cargo ships built by the United States Maritime Commission during World War II. The design was developed for the American-Hawaiian Lines in 1941. Eighty-one ships were built as cargo or troopships in four shipyards, Kaiser Richmond, CA, Kaiser Vancouver, WA, Sun Shipbuilding and Drydock in Chester PA, all ships were capable of 17 knots, driven by a single screw steam turbine generating 9,900 shp. Among the variations of the design were the Haven class hospital ship and they were followed post-war by thirty-seven of the larger C4-S-1 class, also known as the Mariner class. Built by Kaiser Shipyards at Permanente No.3 in Richmond, USS General G. O. Squier USS General T. H. Bliss USS General J. R. Brooke USS General O. H. Ernst USS General R. L. Howze USS General W. M. Black USS General H. L. Scott USS General S. D. Sturgis USS General C. G. Morton USS General R. E. Callan, later USNS General H. H. Langfitt USS General Omar Bundy USS General R. M. Blatchford USS General LeRoy Eltinge USS General A. W. Brewster USS General D. E. Aultman USS General C. C. Ballou USS General W. G. Haan USS General Stuart Heintzelman C4-S-B1, C4-S-B2, C4-S-B5 DWT,15,300 Built by Sun Yards of Chester, Pennsylvania. SS Mount Davis SS Mount Greylock SS Mount Mansfield SS Mount Rogers SS Mount Whitney C4-S-A3 DWT,14,863 Built by Kaiser Shipyards in Vancouver, land SS Willis Vickery SS Louis McH. Howe SS Ernie Pyle C4-S-B2 DWT,15,300 Built by Sun Yards in Chester, SS Santa Magdelena SS Santa Mariana SS Santa Maria SS Santa Mercedes C4-S-49b DWT,13,915. Built in 1965 by Bethlehem Steel of Sparrows Pt, the last two C4 ships were constructed in 1966 for the Prudential Lines. SS Prudential Seajet SS Prudential Oceanjet Marine Perch a C4-S-A3, was renamed the SS Yellowstone was in a collision, Type C1 ship Type C2 ship Type C3 ship T2 tanker Liberty ship Victory ship Hog Islander U. S. A. Sawyer and W. H. Mitchell. London,1981, World Ship Society Ships for Victory, A History of Shipbuilding under the U. S. Maritime Commission in World War II, by Frederic C. Lane ISBN 0-8018-6752-5
9.
United States Army
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The United States Armed Forces are the federal armed forces of the United States. They consist of the Army, Marine Corps, Navy, Air Force, from the time of its inception, the military played a decisive role in the history of the United States. A sense of unity and identity was forged as a result of victory in the First Barbary War. Even so, the Founders were suspicious of a permanent military force and it played an important role in the American Civil War, where leading generals on both sides were picked from members of the United States military. Not until the outbreak of World War II did a standing army become officially established. The National Security Act of 1947, adopted following World War II and during the Cold Wars onset, the U. S. military is one of the largest militaries in terms of number of personnel. It draws its personnel from a pool of paid volunteers. As of 2016, the United States spends about $580.3 billion annually to fund its military forces, put together, the United States constitutes roughly 40 percent of the worlds military expenditures. For the period 2010–14, the Stockholm International Peace Research Institute found that the United States was the worlds largest exporter of major arms, the United States was also the worlds eighth largest importer of major weapons for the same period. The history of the U. S. military dates to 1775 and these forces demobilized in 1784 after the Treaty of Paris ended the War for Independence. All three services trace their origins to the founding of the Continental Army, the Continental Navy, the United States President is the U. S. militarys commander-in-chief. Rising tensions at various times with Britain and France and the ensuing Quasi-War and War of 1812 quickened the development of the U. S. Navy, the reserve branches formed a military strategic reserve during the Cold War, to be called into service in case of war. Time magazines Mark Thompson has suggested that with the War on Terror, Command over the armed forces is established in the United States Constitution. The sole power of command is vested in the President by Article II as Commander-in-Chief, the Constitution also allows for the creation of executive Departments headed principal officers whose opinion the President can require. This allowance in the Constitution formed the basis for creation of the Department of Defense in 1947 by the National Security Act, the Defense Department is headed by the Secretary of Defense, who is a civilian and member of the Cabinet. The Defense Secretary is second in the chain of command, just below the President. Together, the President and the Secretary of Defense comprise the National Command Authority, to coordinate military strategy with political affairs, the President has a National Security Council headed by the National Security Advisor. The collective body has only power to the President
10.
United Nations
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The United Nations is an intergovernmental organization to promote international co-operation. A replacement for the ineffective League of Nations, the organization was established on 24 October 1945 after World War II in order to prevent another such conflict, at its founding, the UN had 51 member states, there are now 193. The headquarters of the UN is in Manhattan, New York City, further main offices are situated in Geneva, Nairobi, and Vienna. The organization is financed by assessed and voluntary contributions from its member states, the UNs mission to preserve world peace was complicated in its early decades by the Cold War between the US and Soviet Union and their respective allies. The organization participated in actions in Korea and the Congo. After the end of the Cold War, the UN took on major military, the UN has six principal organs, the General Assembly, the Security Council, the Economic and Social Council, the Secretariat, the International Court of Justice, and the UN Trusteeship Council. UN System agencies include the World Bank Group, the World Health Organization, the World Food Programme, UNESCO, the UNs most prominent officer is the Secretary-General, an office held by Portuguese António Guterres since 2017. Non-governmental organizations may be granted consultative status with ECOSOC and other agencies to participate in the UNs work, the organization won the Nobel Peace Prize in 2001, and a number of its officers and agencies have also been awarded the prize. Other evaluations of the UNs effectiveness have been mixed, some commentators believe the organization to be an important force for peace and human development, while others have called the organization ineffective, corrupt, or biased. Following the catastrophic loss of life in the First World War, the earliest concrete plan for a new world organization began under the aegis of the US State Department in 1939. It incorporated Soviet suggestions, but left no role for France, four Policemen was coined to refer to four major Allied countries, United States, United Kingdom, Soviet Union, and China, which emerged in the Declaration by United Nations. Roosevelt first coined the term United Nations to describe the Allied countries, the term United Nations was first officially used when 26 governments signed this Declaration. One major change from the Atlantic Charter was the addition of a provision for religious freedom, by 1 March 1945,21 additional states had signed. Each Government pledges itself to cooperate with the Governments signatory hereto, the foregoing declaration may be adhered to by other nations which are, or which may be, rendering material assistance and contributions in the struggle for victory over Hitlerism. During the war, the United Nations became the term for the Allies. To join, countries had to sign the Declaration and declare war on the Axis, at the later meetings, Lord Halifax deputized for Mr. Eden, Wellington Koo for T. V. Soong, and Mr Gromyko for Mr. Molotov. The first meetings of the General Assembly, with 51 nations represented, the General Assembly selected New York City as the site for the headquarters of the UN, and the facility was completed in 1952. Its site—like UN headquarters buildings in Geneva, Vienna, and Nairobi—is designated as international territory, the Norwegian Foreign Minister, Trygve Lie, was elected as the first UN Secretary-General
11.
Vietnam
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Vietnam, officially the Socialist Republic of Vietnam, is the easternmost country on the Indochina Peninsula in Southeast Asia. With an estimated 92.7 million inhabitants as of 2016, it is the worlds 14th-most-populous country, and its capital city has been Hanoi since the reunification of North and South Vietnam in 1976, with Ho Chi Minh City as a historical city as well. The northern part of Vietnam was part of Imperial China for over a millennium, an independent Vietnamese state was formed in 939, following a Vietnamese victory in the Battle of Bạch Đằng River. Following a Japanese occupation in the 1940s, the Vietnamese fought French rule in the First Indochina War, thereafter, Vietnam was divided politically into two rival states, North Vietnam, and South Vietnam. Conflict between the two sides intensified in what is known as the Vietnam War, the war ended with a North Vietnamese victory in 1975. Vietnam was then unified under a communist government but remained impoverished, in 1986, the government initiated a series of economic and political reforms which began Vietnams path towards integration into the world economy. By 2000, it had established relations with all nations. Since 2000, Vietnams economic growth rate has been among the highest in the world and its successful economic reforms resulted in its joining the World Trade Organization in 2007. It is also a member of the Asia-Pacific Economic Cooperation and the Organisation Internationale de la Francophonie, Vietnam remains one of the worlds four remaining one-party socialist states officially espousing communism. The name Việt Nam is a variation of Nam Việt, a name that can be traced back to the Triệu Dynasty of the 2nd century BC. The word Việt originated as a form of Bách Việt. The form Vietnam is first recorded in the 16th-century oracular poem Sấm Trạng Trình, the name has also been found on 12 steles carved in the 16th and 17th centuries, including one at Bao Lam Pagoda in Haiphong that dates to 1558. Then, as recorded, rewarded Yuenan/Vietnam as their nations name, to also show that they are below the region of Baiyue/Bach Viet. Between 1804 and 1813, the name was used officially by Emperor Gia Long and it was revived in the early 20th century by Phan Bội Châus History of the Loss of Vietnam, and later by the Vietnamese Nationalist Party. The country was usually called Annam until 1945, when both the government in Huế and the Viet Minh government in Hanoi adopted Việt Nam. Archaeological excavations have revealed the existence of humans in what is now Vietnam as early as the Paleolithic age, Homo erectus fossils dating to around 500,000 BC have been found in caves in Lạng Sơn and Nghệ An provinces in northern Vietnam. The oldest Homo sapiens fossils from mainland Southeast Asia are of Middle Pleistocene provenance, teeth attributed to Homo sapiens from the Late Pleistocene have also been found at Dong Can, and from the Early Holocene at Mai Da Dieu, Lang Gao and Lang Cuom. The Hồng Bàng dynasty of the Hùng kings is considered the first Vietnamese state, in 257 BC, the last Hùng king was defeated by Thục Phán, who consolidated the Lạc Việt and Âu Việt tribes to form the Âu Lạc, proclaiming himself An Dương Vương
12.
Artificial reef
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Many reefs are built using objects that were built for other purposes, for example by sinking oil rigs, scuttling ships, or by deploying rubble or construction debris. Other artificial reefs are built from PVC or concrete. Shipwrecks may become artificial reefs when preserved on the sea floor, the construction of artificial reefs is thousands of years old. Since at least the 1830s, US fishermen used interlaced logs to build artificial reefs, more recently, castaway junk, such as old refrigerators, shopping carts, ditched cars, out-of-service vending machines replaced the logs in ad hoc reefs. Officially sanctioned projects have incorporated decommissioned subway cars, vintage battle tanks, armored personnel carriers, artificial reefs tend to develop in more or less predictable stages. Next come creatures seeking protection from the oceans lethal openness—hole and crevice dwellers such as grouper, snapper, squirrelfish, eels, opportunistic predators such as jack and barracuda also appear, waiting for their prey to venture out. Over months and years the structure becomes encrusted with algae, tunicates, hard and soft corals. Mineral accretion involves applying a low voltage current to a structure to cause limestone to crystallize on the surface, to which coral planulae can attach. The electric current also speeds post-attachment growth, EMA works like charging a battery with a positive pole, the cathode, and a negative pole, the anode. Applying electric current attracts various dissolved minerals to either the cathode or the anode, chemical reactions take place at both poles. On the anode, bubbles of oxygen and chlorine gas form and these bubbles float to the surface and dissolve into the air. On the cathode, bubbles of gas and a limestone precipitate appear. The voltage is low enough that it can be generated by floating solar panels or from wave motion, artificial surfing reefs have been created in several locations around the world. Supporters cite subsidiary benefits such as protection, habitat enhancement. The worlds first attempt was made in El Segundo, near Los Angeles, the next attempt was at Mosman Beach, Perth, Western Australia. This reef was constructed of granite rocks placed in a pyramidal shape to form an appropriate breaking wave form that would suit surfers. An artificial reef constructed of over 400 massive, geotextile bags filled with sand was constructed in 2000 at Narrowneck on the Gold Coast of Queensland and this artificial reef had two objectives, stabilizing beach nourishment and improving surfing conditions. Europes first artificial reef was approved in 2008, construction began August 30,2008, in Boscombe, Bournemouth, UK, and opened in November 2009
United States