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Clock Position
A clock position, or clock bearing, is the direction of an object observed from a vehicle, typically a vessel or an aircraft, relative to the orientation of the vehicle to the observer. The vehicle must be considered to have a front, a back, a left side and a right side. These quarters may have specialized names, such as bow and stern for a vessel, or nose and tail for an aircraft. The observer then measures or observes the angle made by the intersection of the line of sight to the longitudinal axis, the dimension of length, of the vessel, using the clock analogy. In this analogy, the observer imagines the vessel located on a horizontal clock face with the front at 12:00. Neglecting the length of the vessel, and presuming that he is at the bow, he observes the time number lying on the line of sight. For example, ''12 o'clock'' means ''directly ahead'', ''3 o'clock'' means ''directly to the right'', ''6 o'clock'' means ''directly behind'', and ''9 o'clock'' means ''directly to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Civil Time
In modern usage, civil time refers to statutory time as designated by civilian authorities. Modern civil time is generally national standard time in a time zone at a fixed offset from Coordinated Universal Time (UTC), possibly adjusted by daylight saving time during part of the year. UTC is calculated by reference to atomic clocks and was adopted in 1972. Older systems use telescope observations. In traditional astronomical usage, civil time was mean solar time reckoned from midnight. Before 1925, the astronomical time 00:00:00 meant noon, twelve hours after the civil time 00:00:00 which meant midnight. HM Nautical Almanac Office in the United Kingdom used Greenwich Mean Time (GMT) for both conventions, leading to ambiguity, whereas the Nautical Almanac Office at the United States Naval Observatory used GMT for the pre-1925 convention and Greenwich Civil Time (GCT) for the post-1924 convention until 1952. In 1928, the International Astronomical Union introduced the term Univer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Middle Ages
The High Middle Ages, or High Medieval Period, was the periodization, period of European history that lasted from AD 1000 to 1300. The High Middle Ages were preceded by the Early Middle Ages and were followed by the Late Middle Ages, which ended around AD 1500 (by historiography, historiographical convention). Key historical trends of the High Middle Ages include the medieval demography, rapidly increasing population of Europe, which brought about great social and political change from the preceding era, and the Renaissance of the 12th century, including the first developments of rural exodus and urbanization. By 1250, the robust population increase had greatly benefited the European economy, which reached levels that would not be seen again in some areas until the 19th century. That trend faltered during the Late Middle Ages because of a Crisis of the Late Middle Ages, series of calamities, most notably the Black Death, but also numerous wars as well as economic stagnation. Fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Number
A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers can be represented by symbols, called ''numerals''; for example, "5" is a numeral that represents the number five. As only a relatively small number of symbols can be memorized, basic numerals are commonly organized in a numeral system, which is an organized way to represent any number. The most common numeral system is the Hindu–Arabic numeral system, which allows for the representation of any number using a combination of ten fundamental numeric symbols, called digits. In addition to their use in counting and measuring, numerals are often used for labels (as with telephone numbers), for ordering (as with serial numbers), and for codes (as with ISBNs). In common usage, a ''numeral'' is not clearly distinguished from the ''number'' th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
