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Burm
A berm is a level space, shelf, or raised barrier (usually made of compacted soil) separating areas in a vertical way, especially partway up a long slope. It can serve as a terrace road, track, path, a fortification line, a border/separation barrier for navigation, good drainage, industry, or other purposes. Etymology The word is one of Middle Dutch and came into usage in English via French. Military use History In medieval military engineering, a berm (or berme) was a level space between a parapet or defensive wall and an adjacent steep-walled ditch or moat. It was intended to reduce soil pressure on the walls of the excavated part to prevent its collapse. It also meant that debris dislodged from fortifications would not fall into (and fill) a ditch or moat. In the trench warfare of World War I, the name was applied to a similar feature at the lip of a trench, which served mainly as an elbow-rest for riflemen. Modern usage In modern military engineering, a berm is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Defensive Wall
A defensive wall is a fortification usually used to protect a city, town or other settlement from potential aggressors. The walls can range from simple palisades or earthworks to extensive military fortifications with towers, bastions and gates for access to the city. From ancient to modern times, they were used to enclose settlements. Generally, these are referred to as city walls or town walls, although there were also walls, such as the Great Wall of China, Walls of Benin, Hadrian's Wall, Anastasian Wall, and the Atlantic Wall, which extended far beyond the borders of a city and were used to enclose regions or mark territorial boundaries. In mountainous terrain, defensive walls such as '' letzis'' were used in combination with castles to seal valleys from potential attack. Beyond their defensive utility, many walls also had important symbolic functions representing the status and independence of the communities they embraced. Existing ancient walls are almost always mason ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Border Wall
A border barrier is a separation barrier that runs along or near an international border. Such barriers are typically constructed for border control purposes such as curbing illegal immigration, human trafficking, and smuggling. Some such barriers are constructed for defence or security reasons. In cases of a disputed or unclear border, erecting a barrier can serve as a ''de facto'' unilateral consolidation of a territorial claim that can supersede formal delimitation. A border barrier does not usually indicate the location of the actual border, and is usually constructed unilaterally by a country, without the agreement or cooperation of the other country. Examples of border walls include the ancient Great Wall of China, a series of walls separating China from nomadic empires to the north. The construction of border barriers increased in the early 2000s; half of all the border barriers built since World War II which ended in 1945, were built after 2000. List of current barrier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wall
A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including: * Walls in buildings that form a fundamental part of the superstructure or separate interior rooms, sometimes for fire safety *Glass walls (a wall in which the primary structure is made of glass; does not include openings within walls that have glass coverings: these are windows) * Border barriers between countries * Brick walls * Defensive walls in fortifications * Permanent, solid fences * Retaining walls, which hold back dirt, stone, water, or noise sound * Stone walls * Walls that protect from oceans ( seawalls) or rivers ( levees) Etymology The term ''wall'' comes from Latin ''vallum'' meaning "...an earthen wall or rampart set with palisades, a row or line of stakes, a wall, a rampart, fortification..." while the Latin word ''murus'' means a defensive stone wall. English uses th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, despite not providing food, energy or organic micronutrients. Its chemical formula, H2O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. "Water" is also the name of the liquid state of H2O at standard temperature and pressure. A number of natural states of water exist. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is steam or water vapor. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies. Velocity is a physical vector quantity; both magnitude and direction are needed to define it. The scalar absolute value ( magnitude) of velocity is called , being a coherent derived unit whose quantity is measured in the SI ( metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object is said to be undergoing an ''acceleration''. Constant velocity vs acceleration To have a ''constant velocity'', an object must have a constant speed in a constant direction. Constant dire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Runoff
Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when the soil is saturated by water to its full capacity, and the rain arrives more quickly than the soil can absorb it. Surface runoff often occurs because impervious areas (such as roofs and pavement) do not allow water to soak into the ground. Furthermore, runoff can occur either through natural or man-made processes. Surface runoff is a major component of the water cycle. It is the primary agent of soil erosion by water. The land area producing runoff that drains to a common point is called a drainage basin. Runoff that occurs on the ground surface before reaching a channel can be a nonpoint source of pollution, as it can carry man-made contaminants or natural forms of pollution (such as rotting leaves). Man-made contaminants in runoff i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone (sedimentary rocks) through lithification. Sediments are most often transported by water ( fluvial processes), but also wind ( aeolian processes) and glaciers. Beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of aeolian transport and deposition. Glacial moraine deposits and till are ice-transported sediments. Classification Sediment can be classified based on its grain size, grain sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and waves; glacial plucking, abrasion, and scour; areal flooding; wind abrasion; groundwater processes; and mass movement processes in steep landscapes like landslides and debris flows. The rates at which such processes act control how fast a surface is eroded. Typically, physical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moroccan Western Sahara Wall
The Moroccan Western Sahara Wall or Berm is an approximately sand wall or berm running south to north through Western Sahara and the southwestern portion of Morocco. It separates the Moroccan-controlled areas (the Southern Provinces) on the west from the Polisario-controlled areas ( Free Zone, nominally Sahrawi Arab Democratic Republic) on the east. The main function of the barriers is to exclude guerrilla fighters of the Polisario Front, who have sought Western Saharan independence since before Spain ended its colonial occupation in 1975, from the Moroccan-controlled western part of the territory. According to maps from the United Nations Mission for the Referendum in Western Sahara (MINURSO) or the United Nations High Commissioner for Refugees (UNHCR), in some places the wall extends several kilometers into internationally recognized Mauritanian territory. Names The Moroccan Western Sahara Wall is also called the Western Sahara berm and the Western Sahara separa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Construction
Construction is a general term meaning the art and science of forming Physical object, objects, systems, or organizations."Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 It comes from the Latin word ''constructio'' (from ''com-'' "together" and ''struere'' "to pile up") and Old French ''construction''. To 'construct' is a verb: the act of building, and the noun is construction: how something is built or the nature of its structure. In its most widely used context, construction covers the processes involved in delivering buildings, infrastructure, industrial facilities, and associated activities through to the end of their life. It typically starts with planning, financing, and design that continues until the asset is built and ready for use. Construction also covers repairs and maintenance work, any works to expand, extend and improve the asset, and its eventual demolition, dismantling or wikt:de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infantry
Infantry is a military specialization which engages in ground combat on foot. Infantry generally consists of light infantry, mountain infantry, motorized infantry & mechanized infantry, airborne infantry, air assault infantry, and marine infantry. Although disused in modern times, heavy infantry also commonly made up the bulk of many historic armies. Infantry, cavalry, and artillery have traditionally made up the core of the combat arms professions of various armies, with the infantry almost always comprising the largest portion of these forces. Etymology and terminology In English, use of the term ''infantry'' began about the 1570s, describing soldiers who march and fight on foot. The word derives from Middle French ''infanterie'', from older Italian (also Spanish) ''infanteria'' (foot soldiers too inexperienced for cavalry), from Latin '' īnfāns'' (without speech, newborn, foolish), from which English also gets ''infant''. The individual-soldier te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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