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Annular Solar Eclipses
Annulus (or anulus) or annular indicates a ring- or donut-shaped area or structure. It may refer to: Human anatomy * ''Anulus fibrosus disci intervertebralis'', spinal structure * Annulus of Zinn, a.k.a. annular tendon or ''anulus tendineus communis'', around the optic nerve * Annular ligament (other) * ''Digitus anularis'', a.k.a. ring finger * ''Anulus ciliaris'', a.k.a. ciliary body * ''Anulus femoralis'', a.k.a. femoral ring * ''Anulus inguinalis superficialis'', a.k.a. superficial inguinal ring * ''Anulus inguinalis profundus'', a.k.a. deep inguinal ring * ''Anuli fibrosi cordis'', a.k.a. fibrous rings of heart * ''Anulus umbilicalis '', a.k.a. umbilical ring Other * Annulus (construction), outer gear ring in an epicyclic gearing * Annulus (botany), structure on fern and moss sporangia * Annular lake, a ring-shaped lake caused by meteor impact * Annulus (mathematics), the shape between two concentric circles * Annulus (mycology), structure on mushroom * Annulus ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anulus Fibrosus Disci Intervertebralis
An intervertebral disc (or intervertebral fibrocartilage) lies between adjacent vertebrae in the vertebral column. Each disc forms a fibrocartilaginous joint (a symphysis), to allow slight movement of the vertebrae, to act as a ligament to hold the vertebrae together, and to function as a shock absorber for the spine. Structure Intervertebral discs consist of an outer fibrous ring, the anulus fibrosus disci intervertebralis, which surrounds an inner gel-like center, the nucleus pulposus. The ''anulus fibrosus'' consists of several layers (laminae) of fibrocartilage made up of both type I and type II collagen. Type I is concentrated toward the edge of the ring, where it provides greater strength. The stiff laminae can withstand compressive forces. The fibrous intervertebral disc contains the ''nucleus pulposus'' and this helps to distribute pressure evenly across the disc. This prevents the development of stress concentrations which could cause damage to the underlying vertebrae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annular Lake
An impact crater lake is a lake inside a depression caused by the impact of a meteor. It is also known as an annular lake in cases where the water body is shaped like a ring, as many impact crater lakes are. Examples One of the largest impact crater lakes is Lake Manicouagan in Canada; the crater is a multiple-ring structure about across, with its diameter inner ring its most prominent feature; it contains a diameter annular lake, surrounding an inner island plateau, René-Levasseur Island. It is Earth's sixth-largest confirmed impact crater according to rim-to-rim diameter. List See also * Volcanic crater lake A volcanic crater lake is a lake in a crater that was formed by explosive activity or a collapse during a volcanic eruption. Formation Lakes in calderas fill large craters formed by the collapse of a volcano during an eruption. Lakes in maars ... References {{Geo-term-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annular Tropical Cyclone
An annular tropical cyclone is a tropical cyclone that features a normal to large, symmetric eye surrounded by a thick and uniform ring of intense convection, often having a relative lack of discrete rainbands, and bearing a symmetric appearance in general. As a result, the appearance of an annular tropical cyclone can be referred to as akin to a tire or doughnut. Annular characteristics can be attained as tropical cyclones intensify; however, outside the processes that drive the transition from asymmetric systems to annular systems and the abnormal resistance to negative environmental factors found in storms with annular features, annular tropical cyclones behave similarly to asymmetric storms. Most research related to annular tropical cyclones is limited to satellite imagery and aircraft reconnaissance as the conditions thought to give rise to annular characteristics normally occur over open water, well removed from landmasses where surface observations are possible. Charac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annular Eclipse
A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth, totally or partially. Such an alignment occurs during an eclipse season, approximately every six months, during the new moon phase, when the Moon's orbital plane is closest to the plane of the Earth's orbit. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses, only part of the Sun is obscured. Unlike a lunar eclipse, which may be viewed from anywhere on the night side of Earth, a solar eclipse can only be viewed from a relatively small area of the world. As such, although total solar eclipses occur somewhere on Earth every 18 months on average, they recur at any given place only once every 360 to 410 years. If the Moon were in a perfectly circular orbit and in the same orbital plane as Earth, there would be total solar eclipses once a month, at every new moon. Instead, because the Moon' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annulet (other)
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Annulet may refer to: * Annulet (heraldry), a mark in distinction * Annulet (architecture), a fillet or ring encircling a column * Annulet or ''Charissa obscurata'', a species of moth in the family Geometridae See also * Annulus (other) Annulus (or anulus) or annular indicates a ring- or donut-shaped area or structure. It may refer to: Human anatomy * ''Anulus fibrosus disci intervertebralis'', spinal structure * Annulus of Zinn, a.k.a. annular tendon or ''anulus tendineus com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annulation
In organic chemistry annulation (from the Latin ''anellus'' for "little ring"; occasionally annelation) is a chemical reaction in which a new ring is constructed on a molecule. : Examples are the Robinson annulation, Danheiser annulation and certain cycloadditions. Annular molecules are constructed from side-on condensed cyclic segments, for example helicenes and acenes. In transannulation a bicyclic molecule is created by intramolecular carbon-carbon bond formation in a large monocyclic ring. An example is the samarium(II) iodide induced ketone - alkene cyclization of ''5-methylenecyclooctanone'' which proceeds through a ketyl intermediate: : Benzannulation The term benzannulated compounds refers to derivatives of cyclic compounds (usually aromatic) which are fused to a benzene ring. Examples are listed in the table below: In contemporary chemical literature, the term benzannulation also means "construction of benzene rings from acyclic precursors". upright=1.4, Protonatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annular Blowout Preventer
A blowout preventer (BOP) (pronounced B-O-P, not "bop") is a specialized valve or similar mechanical device, used to seal, control and monitor oil and gas wells to prevent blowouts, the uncontrolled release of crude oil or natural gas from a well. They are usually installed in stacks of other valves. Blowout preventers were developed to cope with extreme erratic pressures and uncontrolled flow ( formation kick) emanating from a well reservoir during drilling. Kicks can lead to a potentially catastrophic event known as a blowout. In addition to controlling the downhole (occurring in the drilled hole) pressure and the flow of oil and gas, blowout preventers are intended to prevent tubing (e.g. drill pipe and well casing), tools and drilling fluid from being blown out of the wellbore (also known as bore hole, the hole leading to the reservoir) when a blowout threatens. Blowout preventers are critical to the safety of crew, rig (the equipment system used to drill a wellbore) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annulus (well)
The annulus of an oil well or water well is any void between any piping, tubing or casing and the piping, tubing, or casing immediately surrounding it.SchlumbergeOilfield Glossary: Term 'annulus', retrieved 18 February 2010. It is named after the corresponding geometric concept. The presence of an annulus gives the ability to circulate fluid in the well, provided that excess drill cuttings have not accumulated in the annulus, preventing fluid movement and possibly sticking the pipe in the borehole. For a new well in the process of being drilled, this would be the void between the drill string and the formation being drilled. An easy way to visualise this would be to stand a straw (purple in diagram) straight up in the center of a glass of water. All of the water in between the straw and the sides of the glass would be the annulus (yellow area in diagram), with the straw itself representing the drill string and the sides of the glass representing the formation. While dril ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piston
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder. __TOC__ Piston engines Internal combustion engines An internal combustion engine is acted upon by the pressure of the expanding combustion gases in the combustion chamber space at the top of the cylinder. This force then acts downwards through the connecting rod and onto the crankshaft. The connecting rod is att ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annulus (firestop)
{{unreferenced, date=March 2015 The annulus, or annular space, is the space between a penetrant and whatever surrounds it, such as the sides of an opening or a sleeve A sleeve ( ang, slīef, a word allied to ''slip'', cf. Dutch ) is the part of a garment that covers the arm, or through which the arm passes or slips. The sleeve is a characteristic of fashion seen in almost every country and time period, acro ..., as the case may be. External links External examples of the use of the term. Annulus, a term used within a firestop patentAnnulus, as used in UL System C-AJ-1557 Firestop System, Configuration A Passive fire protection Firestops ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annulus (mycology)
An annulus is the ring-like or collar-like structure sometimes found on the stipe of some species of mushrooms. The annulus represents the remnants of the partial veil, after it has ruptured to expose the gills or other spore-producing surface. It can also be called a ring which is what the Latin word annulus directly translates as. The modern usage of the Latin word originates from the early days of botany and mycology when species descriptions were only written in Latin. Outside of the formal setting of scientific publications which still have a Latin requirement, it will often just be referred to as a ring or stem ring in field guide A field guide is a book designed to help the reader identify wildlife (flora or fauna) or other objects of natural occurrence (e.g. rocks and minerals). It is generally designed to be brought into the "field" or local area where such objects exi ...s and on identification websites. Ring descriptions The way in which the structure and appea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annulus (mathematics)
In mathematics, an annulus (plural annuli or annuluses) is the region between two concentric circles. Informally, it is shaped like a ring or a hardware washer. The word "annulus" is borrowed from the Latin word ''anulus'' or ''annulus'' meaning 'little ring'. The adjectival form is annular (as in annular eclipse). The open annulus is topologically equivalent to both the open cylinder and the punctured plane. Area The area of an annulus is the difference in the areas of the larger circle of radius and the smaller one of radius : :A = \pi R^2 - \pi r^2 = \pi\left(R^2 - r^2\right). The area of an annulus is determined by the length of the longest line segment within the annulus, which is the chord tangent to the inner circle, in the accompanying diagram. That can be shown using the Pythagorean theorem since this line is tangent to the smaller circle and perpendicular to its radius at that point, so and are sides of a right-angled triangle with hypotenuse , and the ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
