In computing, an icon is a pictogram or ideogram displayed on a computer screen in order to help the user navigate a computer system. The icon itself is a comprehensible symbol of a software tool, function, or a data file, accessible on the system and is more like a traffic sign than a detailed illustration of the actual entity it represents, it can file shortcut to access the program or data. The user can activate an icon using a mouse, finger, or voice commands, their placement on the screen in relation to other icons, may provide further information to the user about their usage. In activating an icon, the user can move directly into and out of the identified function without knowing anything further about the location or requirements of the file or code. Icons as parts of the graphical user interface of the computer system, in conjunction with windows, menus and a pointing device, belong to the much larger topic of the history of the graphical user interface that has supplanted the text-based interface for casual use.
The computing definition of "icon" can include three distinct semiotical elements: Icon, which resembles its referent. This category includes stylized drawings of objects from the office environment or from other professional areas such as printers, file cabinets and folders. Index, associated with its referent; this category includes stylized drawing used to refer to an actions printer" and "print", "scissors" and "cut" or "magnifying glass" and "search". Symbol, related to its referent only by convention; this category includes standardized symbols found across many electronic devices, such as the power on/off symbol and the USB icon. The majority of icons are encoded and decoded using Metonymy and Metaphor. An example of metaphorical representation characterizes all the major desktop-based computer systems including desktop that uses an iconic representation of objects from the 1980s office environment to transpose attributes from a familiar context/object to an unfamiliar one. Metonymy is in itself a subset of metaphors that use one entity to point to another related to it such as using a fluorescent bulb instead of a filament one to represent power saving settings.
Synecdoche is considered as a special case of metonymy, in the usual sense of the part standing for the whole such as a single component for the entire system, speaker driver for the entire audio system settings. Additionally, a group of icons can be categorised as brand icons, used to identify commercial software programs and are related to the brand identity of a company or software; these commercial icons serve as functional links on the system to the program or data files created by a specific software provider. Although icons are depicted in graphical user interfaces, icons are sometimes rendered in a TUI using special characters such as MouseText or PETSCII; the design of all computer icons is constricted by the limitations of the device display. They are limited in size, with the standard size about a thumbnail for both desktop computer systems and mobile devices, they are scalable, as they are displayed in different positions in the software, a single icon file such as the Apple Icon Image format can include multiple versions of the same icon optimized to work at a different size, in colour or grayscale as well as on dark and bright backgrounds.
The colors used, of both the image and the icon background, should stand out on different system backgrounds and among each other. The detailing of the icon image needs to be simple, remaining recognizable in varying graphical resolutions and screen sizes. Computer icons are by definition language-independent but not culturally independent; these visual parameters place rigid limits on the design of icons requiring the skills of a graphic artist in their development. Because of their condensed size and versatility, computer icons have become a mainstay of user interaction with electronic media. Icons provide rapid entry into the system functionality. On most systems, users can create and delete, select, click or double-click standard computer icons and drag them to new positions on the screen to create a customized user environment. A series of recurring computer icons are taken from the broader field of standardized symbols used across a wide range of electrical equipment. Examples of these are the power symbol and the USB icon, which are found on a wide variety of electronic devices.
The standardization of electronic icons is an important safety-feature on all types of electronics, enabling a user to more navigate an unfamiliar system. As a subset of electronic devices, computer systems and mobile devices use many of the same icons. On the hardware, these icons identify the functionality of specific plugs. In the software, they provide a link into the customizable settings. System warning icons belong to the broader area of ISO standard warning signs; these warning icons, first designed to regulate automobile traffic in the early 1900s, have become standardized and understood by users without necessity of further verbal explanations. In designing software operating systems, different companies have incorporated and defined these standard symbols as part of their graphical user interface. For example, the Microsoft MSDN defines the standard icon use of error, warning and question mark icons as part of their software development guidelines. Different organizations ar
One-way traffic is traffic that moves in a single direction. A one-way street is a street either facilitating only one-way traffic, or designed to direct vehicles to move in one direction. One-way streets result in higher traffic flow as drivers may avoid encountering oncoming traffic or turns through oncoming traffic. Residents may dislike one-way streets due to the circuitous route required to get to a specific destination, the potential for higher speeds adversely affecting pedestrian safety; some studies challenge the original motivation for one-way streets, in that the circuitous routes negate the claimed higher speeds. Signs are posted showing which direction the vehicles can move in: an upward arrow, or on a T junction where the main road is one-way, an arrow to the left or right. At the end of the street through which vehicles may not enter, a prohibitory traffic sign "Do Not Enter", "Wrong Way", or "No Entry" sign is posted, e.g. with that text, or a round red sign with a white horizontal bar.
Sometimes one portion of a street is another portion two-way. An advantage of one-way streets is that drivers do not have to watch for vehicles coming in the opposite direction on this type of street; the abstract "No Entry" sign was adopted for standardization at the League of Nations convention in Geneva in 1931. The sign was adapted from Swiss usage, derived from the practice of former European states that marked their boundaries with their formal shield symbols. Restrictions on entry were indicated by tying a blood-red ribbon horizontally around the shield; the sign is known as C1, from its definition in the Vienna Convention on Road Signs and Signals. The European "No Entry" sign was adopted into North American uniform signage in the late 1960s / 1970s, replacing a previous white square sign bearing only the English text in black "Do Not Enter". In addition to the standardized graphic symbol, the US version still retains the wording "Do Not Enter", while the European and Canadian versions have no text.
Since Unicode 5.2, the Miscellaneous Symbols block contains the glyph ⛔, representable in HTML as ⛔. One-way streets may be part of a one-way system, which facilitates a smoother flow of motor traffic through, for example, a city center grid; this is achieved by arranging one-way streets that cross in such a fashion as to eliminate right turns or left turns. Traffic light systems at such junctions may be simpler and may be coordinated to produce a green wave; some of the reasons one-way traffic is specified: The street is too narrow for movement in both directions and the road users unable to coordinate Prevent drivers from cutting through residential streets to bypass traffic lights or other requirements to stop Discourage drivers from cruising through a residential neighborhood Part of a one-way pair of two parallel one-way streets in opposite directions For a proper functioning of a system of paid parking or other restricted vehicular access To calm traffic in historic city centers Eliminate turns that involve crossing in front of oncoming traffic Increase traffic flow and reduce traffic congestion Eliminate the need for a center turn lane that can instead be used for travel Better traffic flow in densely built-up areas where road widening may not be feasible Simplify pedestrian crossing of the street due to walkers only needing to look for oncoming traffic in one direction Eliminate cars' driver-side doors opening into the travel lane in parallel parking spaces for parking lanes located on the left or right side of a street Locate a one-way bike lane on the opposite side of the street from parallel parking spaces to prevent dooring Limited-access highway entrance and exit ramps.
In the United States, 37 states and Puerto Rico allow left turns on red only if both the origin and destination streets are one way. See South Carolina law Section 56-5-970 C3, for example. Five other states – Alaska, Michigan and Washington – allow left turns on red into a one-way street from a two-way street. An attempt was made in 1617 to introduce one-way streets in alleys near the River Thames in London by The Worshipful Company of Carmen who were commissioned by the King to regulate traffic in the square mile of the City of London; the next one-way street in London was Albemarle Street in Mayfair, the location of the Royal Institution. It was so designated in 1800; the first one-way streets in Paris were the Place Charles de Gaulle around the Arc de Triomphe, the Rue de Mogador and the Rue de la Chaussée-d'Antin, created on 13 December 1909. According to the folklore of Eugene, the use of one-way streets in the United States started in Eugene itself. In 1941 6th Ave was converted into a one-way avenue by the Highway Department.
Other sources claim. On 9 September 1934, the on-fire SS Morro Castle was towed to the New Jersey shoreline near the Asbury Park Convention Center and the sightseeing traffic was enormous; the Asbury Park Police Chief decided to make the Ocean Avenue one-way going north and the street one block over in one-way going south, creating a circular route. By the 1950s this "cruising the circuit" became a draw to the area in itself since teens would drive around it looking to hook up with other
A tunnel is an underground passageway, dug through the surrounding soil/earth/rock and enclosed except for entrance and exit at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods. A tunnel may be for rail traffic, or for a canal; the central portions of a rapid transit network are in tunnel. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers. Utility tunnels are used for routing steam, chilled water, electrical power or telecommunication cables, as well as connecting buildings for convenient passage of people and equipment. Secret tunnels are built for military purposes, or by civilians for smuggling of weapons, contraband, or people. Special tunnels, such as wildlife crossings, are built to allow wildlife to cross human-made barriers safely. Tunnels can be connected together in tunnel networks. A tunnel is long and narrow; the definition of what constitutes a tunnel can vary from source to source.
For example, the definition of a road tunnel in the United Kingdom is defined as "a subsurface highway structure enclosed for a length of 150 metres or more." In the United States, the NFPA definition of a tunnel is "An underground structure with a design length greater than 23 m and a diameter greater than 1,800 millimetres."In the UK, a pedestrian, cycle or animal tunnel beneath a road or railway is called a subway, while an underground railway system is differently named in different cities, the "Underground" or the "Tube" in London, the "Subway" in Glasgow, the "Metro" in Newcastle. The place where a road, canal or watercourse passes under a footpath, cycleway, or another road or railway is most called a bridge or, if passing under a canal, an aqueduct. Where it is important to stress that it is passing underneath, it may be called an underpass, though the official term when passing under a railway is an underbridge. A longer underpass containing a road, canal or railway is called a "tunnel", whether or not it passes under another item of infrastructure.
An underpass of any length under a river is usually called a "tunnel", whatever mode of transport it is for. In the US, the term "subway" means an underground rapid transit system, the term pedestrian underpass is used for a passage beneath a barrier. Rail station platforms may be connected by pedestrian footbridges. Much of the early technology of tunneling evolved from military engineering; the etymology of the terms "mining", "military engineering", "civil engineering" reveals these deep historic connections. Predecessors of modern tunnels were adits to transport water for irrigation or drinking, sewerage; the first Qanats are known from before 2000 B. C. A major tunnel project must start with a comprehensive investigation of ground conditions by collecting samples from boreholes and by other geophysical techniques. An informed choice can be made of machinery and methods for excavation and ground support, which will reduce the risk of encountering unforeseen ground conditions. In planning the route, the horizontal and vertical alignments can be selected to make use of the best ground and water conditions.
It is common practice to locate a tunnel deeper than otherwise would be required, in order to excavate through solid rock or other material, easier to support during construction. Conventional desk and preliminary site studies may yield insufficient information to assess such factors as the blocky nature of rocks, the exact location of fault zones, or the stand-up times of softer ground; this may be a particular concern in large-diameter tunnels. To give more information, a pilot tunnel may be driven ahead of the main excavation; this smaller tunnel is less to collapse catastrophically should unexpected conditions be met, it can be incorporated into the final tunnel or used as a backup or emergency escape passage. Alternatively, horizontal boreholes may sometimes be drilled ahead of the advancing tunnel face. Other key geotechnical factors: "Stand-up time" is the amount of time a newly excavated cavity can support itself without any added structures. Knowing this parameter allows the engineers to determine how far an excavation can proceed before support is needed, which in turn affects the speed and cost of construction.
Certain configurations of rock and clay will have the greatest stand-up time, while sand and fine soils will have a much lower stand-up time. Groundwater control is important in tunnel construction. Water leaking into a tunnel or vertical shaft will decrease stand-up time, causing the excavation to become unstable and risking collapse; the most common way to control groundwater is to install dewatering pipes into the ground and to pump the water out. A effective but expensive technology is ground freezing, using pipes which are inserted into the ground surrounding the excavation, which are cooled with special refrigerant fluids; this freezes the ground around each pipe until the whole space is surrounded with frozen soil, keeping water out until a permanent structure can be built. Tunnel cross-sectional shape is very important in determining stand-up time. If a tunnel excavation is wider than it is high, it will have a harder time supporting itself, decreasing its stand-up time. A square or rectangular excavation is more difficult to make self-supporting, because of a concentration of stress at t
In navigation, a rhumb line, rhumb, or loxodrome is an arc crossing all meridians of longitude at the same angle, that is, a path with constant bearing as measured relative to true or magnetic north. The effect of following a rhumb line course on the surface of a globe was first discussed by the Portuguese mathematician Pedro Nunes in 1537, in his Treatise in Defense of the Marine Chart, with further mathematical development by Thomas Harriot in the 1590s. A rhumb line can be contrasted with a great circle, the path of shortest distance between two points on the surface of a sphere. On a great circle, the bearing to the destination point does not remain constant. If one were to drive a car along a great circle one would hold the steering wheel fixed, but to follow a rhumb line one would have to turn the wheel, turning it more as the poles are approached. In other words, a great circle is locally "straight" with zero geodesic curvature, whereas a rhumb line has non-zero geodesic curvature. Meridians of longitude and parallels of latitude provide special cases of the rhumb line, where their angles of intersection are 0° and 90°.
On a north–south passage the rhumb line course coincides with a great circle, as it does on an east–west passage along the equator. On a Mercator projection map, any rhumb line is a straight line, but theoretically a loxodrome can extend beyond the right edge of the map, where it continues at the left edge with the same slope. Rhumb lines which cut meridians at oblique angles are loxodromic curves which spiral towards the poles. On a Mercator projection the north and south poles are therefore never shown; however the full loxodrome on an infinitely high map would consist of infinitely many line segments between the two edges. On a stereographic projection map, a loxodrome is an equiangular spiral whose center is the north or south pole. All loxodromes spiral from one pole to the other. Near the poles, they are close to being logarithmic spirals, so they wind around each pole an infinite number of times but reach the pole in a finite distance; the pole-to-pole length of a loxodrome is the length of the meridian divided by the cosine of the bearing away from true north.
Loxodromes are not defined at the poles. Three views of a pole-to-pole loxodrome The word loxodrome comes from Ancient Greek λοξός loxós: "oblique" + δρόμος drómos: "running"; the word rhumb may come from Spanish or Portuguese rumbo/rumo and Greek ῥόμβος rhómbos, from rhémbein. The 1878 edition of The Globe Encyclopaedia of Universal Information describes a loxodrome line as: Loxodrom′ic Line is a curve which cuts every member of a system of lines of curvature of a given surface at the same angle. A ship sailing towards the same point of the compass describes such a line which cuts all the meridians at the same angle. In Mercator's Projection the Loxodromic lines are evidently straight. A misunderstanding could arise because the term “rhumb” had no precise meaning when it came into use, it applied well to the windrose lines as it did to loxodromes because the term only applied “locally” and only meant whatever a sailor did in order to sail with constant bearing, with all the imprecision that that implies.
Therefore, “rhumb” was applicable to the straight lines on portolans when portolans were in use, as well as always applicable to straight lines on Mercator charts. For short distances portolan “rhumbs” do not meaningfully differ from Mercator rhumbs, but these days “rhumb” is synonymous with the mathematically precise “loxodrome” because it has been made synonymous retrospectively; as Leo Bagrow states: "..the word is wrongly applied to the sea-charts of this period, since a loxodrome gives an accurate course only when the chart is drawn on a suitable projection. Cartometric investigation has revealed that no projection was used in the early charts, for which we therefore retain the name'portolan'." For a sphere of radius 1, the azimuthal and polar angles λ and −π/2 ≤ φ ≤ π/2 and Cartesian unit vectors i, j, k can be used to write the radius vector r as r = i + j + k. Orthogonal unit vectors in the azimuthal and polar directions of the sphere can be written λ ^ = sec φ ∂ r ∂ λ = i + j, φ ^
A church building or church house simply called a church, is a building used for Christian religious activities for Christian worship services. The term is used by Christians to refer to the physical buildings where they worship, but it is sometimes used to refer to buildings of other religions. In traditional Christian architecture, the church is arranged in the shape of a Christian cross; when viewed from plan view the longest part of a cross is represented by the aisle and the junction of the cross is located at the altar area. Towers or domes are added with the intention of directing the eye of the viewer towards the heavens and inspiring visitors. Modern church buildings have a variety of architectural layouts; the earliest identified Christian church building was a house church founded between 233 and 256. From the 11th through the 14th centuries, a wave of building of cathedrals and smaller parish churches were erected across Western Europe. A cathedral is a church building Roman Catholic, Eastern Orthodox, or Oriental Orthodox, housing a cathedra, the formal name for the seat or throne of a presiding bishop.
In Greek, the adjective kyriak-ós/-ē/-ón means "belonging, or pertaining, to a Kyrios", the usage was adopted by early Christians of the Eastern Mediterranean with regard to anything pertaining to the Lord Jesus Christ: hence "Kyriakós oíkos", "Kyriakē", or "Kyriakē proseukhē". In standard Greek usage, the older word "ecclesia" was retained to signify both a specific edifice of Christian worship, the overall community of the faithful; this usage was retained in Latin and the languages derived from Latin, as well as in the Celtic languages and in Turkish. In the Germanic and some Slavic languages, the word kyriak-ós/-ē/-ón was adopted instead and derivatives formed thereof. In Old English the sequence of derivation started as "cirice" Middle English "churche", "church" in its current pronunciation. German Kirche, Scots kirk, Russian церковь, etc. are all derived. According to the New Testament, the earliest Christians did not build church buildings. Instead, they synagogues; the earliest archeologically identified Christian church is a house church, the Dura-Europos church, founded between 233 and 256.
In the second half of the 3rd century AD, the first purpose-built halls for Christian worship began to be constructed. Although many of these were destroyed early in the next century during the Diocletianic Persecution larger and more elaborate church buildings began to appear during the reign of the Emperor Constantine the Great. From the 11th through the 14th centuries, a wave of building of cathedrals and smaller parish churches occurred across Western Europe. In addition to being a place of worship, the cathedral or the parish church was used by the community in other ways, it could serve as a hall for banquets. Mystery plays were sometimes performed in cathedrals, cathedrals might be used for fairs; the church could be used as a place to store grain. Between 1000 and 1200 the romanesque style became popular across Europe. While the name of the romanesque era refers to the tradition of Roman architecture, it was a West- and Central European trend. Romanesque buildings appear rather compact.
Typical features are circular arches, octagonal towers and cushion capitals on the pillars. In the early romanesque era, coffering on the ceiling was fashionable, while in the same era, groined vault was more popular; the rooms became the motivs of sculptures became more epic. The Gothic style emerged around 1140 in spread through all of Europe; the gothic buildings were less compact than they had been in the romanesque era and contained symbolic and allegoric features. For the first time, pointed arches, rib vaults and buttresses were used, with the result that massive walls were not longer needed to stabilise the building. Due to that advantage, the area of the windows became bigger, which resulted in a brighter and more friendly atmosphere inside the church; the nave so did the pillars and the church steeple. The amibition to test out the limits of the architectural possibilities resulted in the collapse of several towers. In Germany and the Netherlands, but in Spain, it became popular to build hall churches, in which every vault has the same height.
Cathedrals were built in a lavish way, as in the romanesque era. Examples for that are the Notre-Dame de Paris and the Notre-Dame de Reims in France, but the San Francesco d’Assisi in Palermo, the Salisbury Cathedral and the Wool Church in Lavenham, England. Many gothic churches contain features from the romanesque era; some of the most well-known gothic churches stayed unfinished for hundreds of years, after the gothic style was not popular anymore. About half of the Cologne Cathedral was for example build in the 19th century. In the 15th and 16th century, the change in e
In navigation, the course of a vessel or aircraft is the cardinal direction in which the craft is to be steered. The course is to be distinguished from the heading, the compass direction in which the craft's bow or nose is pointed; the path that a vessel follows over the ground is called a ground track, course made good or course over the ground. For an aircraft it is its track; the intended track is a route. For ships and aircraft, routes are straight-line segments between waypoints. A navigator determines the bearing of the next waypoint; because water currents or wind can cause a craft to drift off course, a navigator sets a course to steer that compensates for drift. The helmsman or pilot points the craft on a heading. If the predicted drift is correct the craft's track will correspond to the planned course to the next waypoint. Course directions are specified in degrees from north, either magnetic. In aviation, north is expressed as 360°. Navigators used ordinal directions, instead of compass degrees, e.g. "northeast" instead of 45° until the mid-20th century when the use of degrees became prevalent.
Acronyms and abbreviations in avionics Bearing Breton plotter E6B Ground track Navigation Navigation room Rhumb line Pilot's Handbook of Aeronautical Knowledge glossary