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C2 A spear point blade is a symmetrically-shaped blade with a point aligned with the centerline of the blade's long axis. True spear-point blades are double-edged with a central spine, like a dagger or spear head. The spear point is one of the stronger blade point designs in terms of penetration stress, and is found on many thrusting knives such as the dagger. The term spear point is occasionally and confusingly used to describe small single-edged blades without a central spine, such as that of the pen knife, a small folding-blade pocket knife formerly used in sharpening quills for writing. Pen-knife may also nowadays refer to a knifelike weapon blade pattern of some of larger pocket knife blades that would otherwise be termed drop-point designs.
C3 A needle point blade has a sharply-tapered acuminated point. It is frequently found on daggers such as the stiletto (which had no sharpened edges) and the Fairbairn–Sykes fighting knife. Its long, narrow point reduces friction and increases the blade's penetrative capabilities, but is liable to stick in bone and can break if abused. When the needle point is combined with a reinforced 'T' section running the length of the blade's spine, it is called a reinforced tip. One example of a knife with a reinforced tip is the pesh-kabz.
C4 Kris or flame-bladed sword. These blades have a distinct recurved blade form and are sharpened on both sides, typically tapering to (or approximating) a symmetrical point. | Blade | Wikipedia | 319 | 315320 | https://en.wikipedia.org/wiki/Blade | Technology | Rigid components | null |
C5 Referred to in English speaking countries as a "tanto" or "tanto a corruption of the Japanese word tantō, despite the tip bearing no resemblance to a or as a chisel point, referring to the straightness of the edge that comprises the end of the blade (and not to be confused with a blade said to have a "chisel grind", which would refer to a blade ground on only one side, even though chisels can be ground on one or both sides). It is similar to, but not the same as, some early Japanese swords that had kamasu kissaki ("barracuda tip"), a nearly straight edge at the tip whereas the typical "tanto point" as found in the west has a straight edge. The barracuda tip sword was sharp but also fragile whereas modern tanto points are often advertised as being stronger at the tip for having nearly the whole thickness of the blade present until quite close to the end of the knife. The geometry of the angle under the point gives tanto blades excellent penetration capabilities. For this reason, tanto blades are often found on knives designed for combat or fighting applications, where the user may need to pierce heavy clothing or low-level soft body armor. With a modified tanto, the end is clipped and often sharpened. This brings the tip closer to the center of the blade increasing control of the blade and improves penetration potential by having a finer point and a sharpened back edge.
C6 A hawkbill blade is sharpened on the inside edge and is similar to carpet and linoleum knives. The point will tear even if the rest of the knife is comparatively dull. The karambit from Far South-East Asia is a hawkbill knife which is held with the blade extending from the bottom of the fist and the tip facing forward. The outside edge of a karambit may be sharp and if so may also feature a backward-facing point. | Blade | Wikipedia | 394 | 315320 | https://en.wikipedia.org/wiki/Blade | Technology | Rigid components | null |
C7 An ulu (lit. 'woman's knife' in Inuktitut) knife is a sharpened segment of a circle. This blade type has no point, and has a handle in the middle. It is good for scraping and sometimes chopping. The semi-circular version appears elsewhere in the world and is called a head knife. It is used in leatherworking both to scrape down leather (reducing thickness, i.e. skiving), and to make precise, rolling cuts for shapes other than straight lines. The circular version is a popular tool for slicing pizzas. One corner is placed at the edge of the pizza and the blade is rolled across in a diameter cut.
Sword patterns
The sharp edges of a sword may be either curved or straight. Curved blades tend to glide more easily through soft materials, making these weapons more ideal for slicing. Techniques for such weapons feature drawing the blade across the opponent's body and back. For straight-edged weapons, many recorded techniques feature cleaving cuts, which deliver the power out to a point, striking directly in at the target's body, done to split flesh and bone rather than slice it. That being said, there also exist many historical slicing techniques for straight-edged weapons. Hacking cuts can be followed by a drawing action to maximize the cut's effectiveness. For more information see Western Martial Arts or kenjutsu.
Some weapons are made with only a single leading edge, such as the sabre or dusack. The dusack has a 'false edge' near the tip, which only extends down a portion of the blade's backside. Other weapons have a blade that is entirely dull except for a sharpened point, like the épée or foil, which prefer thrusts over cuts. A blade cannot perform a proper cut without an edge, and so in competitive fencing such attacks reward no points.
Some variations include:
The flame blade (an undulated blade, for both psychological effect and some tactical advantage of using a non-standard blade: vibrations and easier parry)
The colichemarde, found in smallsword
Marks and decoration
Blades are sometimes marked or inscribed, for decorative purposes, or with the mark of either the maker or the owner. Blade decorations are often realized in inlay in some precious metal (gold or silver). | Blade | Wikipedia | 468 | 315320 | https://en.wikipedia.org/wiki/Blade | Technology | Rigid components | null |
Early blade inscriptions are known from the Bronze Age, a Hittite sword found at Hattusa bears an inscription chiseled into the bronze, stating that the blade was deposited as an offering to the storm-god by king Tuthaliya.
Blade inscriptions become particularly popular in the 12th century knightly sword, based on the earlier, 9th to 11th century, the tradition of the so-called Ulfberht swords. | Blade | Wikipedia | 85 | 315320 | https://en.wikipedia.org/wiki/Blade | Technology | Rigid components | null |
In geometry, an isosceles triangle () is a triangle that has two sides of equal length or two angles of equal measure. Sometimes it is specified as having exactly two sides of equal length, and sometimes as having at least two sides of equal length, the latter version thus including the equilateral triangle as a special case.
Examples of isosceles triangles include the isosceles right triangle, the golden triangle, and the faces of bipyramids and certain Catalan solids.
The mathematical study of isosceles triangles dates back to ancient Egyptian mathematics and Babylonian mathematics. Isosceles triangles have been used as decoration from even earlier times, and appear frequently in architecture and design, for instance in the pediments and gables of buildings.
The two equal sides are called the legs and the third side is called the base of the triangle. The other dimensions of the triangle, such as its height, area, and perimeter, can be calculated by simple formulas from the lengths of the legs and base. Every isosceles triangle has an axis of symmetry along the perpendicular bisector of its base. The two equal angles at the base (opposite the legs) are always acute, so the classification of the triangle as acute, right, or obtuse depends only on the angle between its two legs.
Terminology, classification, and examples
Euclid defined an isosceles triangle as a triangle with exactly two equal angles or two equal sides, but modern treatments prefer to define isosceles triangles as having at least two equal sides. The difference between these two definitions is that the modern version makes equilateral triangles (with three equal sides) a special case of isosceles triangles. A triangle that is not isosceles (having three unequal sides) is called scalene.
"Isosceles" is made from the Greek roots "isos" (equal) and "skelos" (leg). The same word is used, for instance, for isosceles trapezoids, trapezoids with two equal sides, and for isosceles sets, sets of points every three of which form an isosceles triangle. | Isosceles triangle | Wikipedia | 436 | 315428 | https://en.wikipedia.org/wiki/Isosceles%20triangle | Mathematics | Two-dimensional space | null |
In an isosceles triangle that has exactly two equal sides, the equal sides are called legs and the third side is called the base. The angle included by the legs is called the vertex angle and the angles that have the base as one of their sides are called the base angles. The vertex opposite the base is called the apex. In the equilateral triangle case, since all sides are equal, any side can be called the base.
Whether an isosceles triangle is acute, right or obtuse depends only on the angle at its apex. In Euclidean geometry, the base angles can not be obtuse (greater than 90°) or right (equal to 90°) because their measures would sum to at least 180°, the total of all angles in any Euclidean triangle. Since a triangle is obtuse or right if and only if one of its angles is obtuse or right, respectively, an isosceles triangle is obtuse, right or acute if and only if its apex angle is respectively obtuse, right or acute. In Edwin Abbott's book Flatland, this classification of shapes was used as a satire of social hierarchy: isosceles triangles represented the working class, with acute isosceles triangles higher in the hierarchy than right or obtuse isosceles triangles.
As well as the isosceles right triangle, several other specific shapes of isosceles triangles have been studied.
These include the Calabi triangle (a triangle with three congruent inscribed squares), the golden triangle and golden gnomon (two isosceles triangles whose sides and base are in the golden ratio), the 80-80-20 triangle appearing in the Langley's Adventitious Angles puzzle, and the 30-30-120 triangle of the triakis triangular tiling.
Five Catalan solids, the triakis tetrahedron, triakis octahedron, tetrakis hexahedron, pentakis dodecahedron, and triakis icosahedron, each have isosceles-triangle faces, as do infinitely many pyramids and bipyramids.
Formulas | Isosceles triangle | Wikipedia | 435 | 315428 | https://en.wikipedia.org/wiki/Isosceles%20triangle | Mathematics | Two-dimensional space | null |
Height
For any isosceles triangle, the following six line segments coincide:
the altitude, a line segment from the apex perpendicular to the base,
the angle bisector from the apex to the base,
the median from the apex to the midpoint of the base,
the perpendicular bisector of the base within the triangle,
the segment within the triangle of the unique axis of symmetry of the triangle, and
the segment within the triangle of the Euler line of the triangle, except when the triangle is equilateral.
Their common length is the height of the triangle.
If the triangle has equal sides of length and base of length ,
the general triangle formulas for
the lengths of these segments all simplify to
This formula can also be derived from the Pythagorean theorem using the fact that the altitude bisects the base and partitions the isosceles triangle into two congruent right triangles.
The Euler line of any triangle goes through the triangle's orthocenter (the intersection of its three altitudes), its centroid (the intersection of its three medians), and its circumcenter (the intersection of the perpendicular bisectors of its three sides, which is also the center of the circumcircle that passes through the three vertices). In an isosceles triangle with exactly two equal sides, these three points are distinct, and (by symmetry) all lie on the symmetry axis of the triangle, from which it follows that the Euler line coincides with the axis of symmetry. The incenter of the triangle also lies on the Euler line, something that is not true for other triangles. If any two of an angle bisector, median, or altitude coincide in a given triangle, that triangle must be isosceles.
Area
The area of an isosceles triangle can be derived from the formula for its height, and from the general formula for the area of a triangle as half the product of base and height:
The same area formula can also be derived from Heron's formula for the area of a triangle from its three sides. However, applying Heron's formula directly can be numerically unstable for isosceles triangles with very sharp angles, because of the near-cancellation between the semiperimeter and side length in those triangles.
If the apex angle and leg lengths of an isosceles triangle are known, then the area of that triangle is: | Isosceles triangle | Wikipedia | 493 | 315428 | https://en.wikipedia.org/wiki/Isosceles%20triangle | Mathematics | Two-dimensional space | null |
This is a special case of the general formula for the area of a triangle as half the product of two sides times the sine of the included angle.
Perimeter
The perimeter of an isosceles triangle with equal sides and base is just
As in any triangle, the area and perimeter are related by the isoperimetric inequality
This is a strict inequality for isosceles triangles with sides unequal to the base, and becomes an equality for the equilateral triangle.
The area, perimeter, and base can also be related to each other by the equation
If the base and perimeter are fixed, then this formula determines the area of the resulting isosceles triangle, which is the maximum possible among all triangles with the same base and perimeter.
On the other hand, if the area and perimeter are fixed, this formula can be used to recover the base length, but not uniquely: there are in general two distinct isosceles triangles with given area and perimeter . When the isoperimetric inequality becomes an equality, there is only one such triangle, which is equilateral.
Angle bisector length
If the two equal sides have length and the other side has length , then the internal angle bisector from one of the two equal-angled vertices satisfies
as well as
and conversely, if the latter condition holds, an isosceles triangle parametrized by and exists.
The Steiner–Lehmus theorem states that every triangle with two angle bisectors of equal lengths is isosceles. It was formulated in 1840 by C. L. Lehmus. Its other namesake, Jakob Steiner, was one of the first to provide a solution.
Although originally formulated only for internal angle bisectors, it works for many (but not all) cases when, instead, two external angle bisectors are equal.
The 30-30-120 isosceles triangle makes a boundary case for this variation of the theorem, as it has four equal angle bisectors (two internal, two external).
Radii
The inradius and circumradius formulas for an isosceles triangle may be derived from their formulas for arbitrary triangles.
The radius of the inscribed circle of an isosceles triangle with side length , base , and height is: | Isosceles triangle | Wikipedia | 460 | 315428 | https://en.wikipedia.org/wiki/Isosceles%20triangle | Mathematics | Two-dimensional space | null |
The center of the circle lies on the symmetry axis of the triangle, this distance above the base.
An isosceles triangle has the largest possible inscribed circle among the triangles with the same base and apex angle, as well as also having the largest area and perimeter among the same class of triangles.
The radius of the circumscribed circle is:
The center of the circle lies on the symmetry axis of the triangle, this distance below the apex.
Inscribed square
For any isosceles triangle, there is a unique square with one side collinear with the base of the triangle and the opposite two corners on its sides. The Calabi triangle is a special isosceles triangle with the property that the other two inscribed squares, with sides collinear with the sides of the triangle,
are of the same size as the base square. A much older theorem, preserved in the works of Hero of Alexandria,
states that, for an isosceles triangle with base and height , the side length of the inscribed square on the base of the triangle is
Isosceles subdivision of other shapes
For any integer , any triangle can be partitioned into isosceles triangles.
In a right triangle, the median from the hypotenuse (that is, the line segment from the midpoint of the hypotenuse to the right-angled vertex) divides the right triangle into two isosceles triangles. This is because the midpoint of the hypotenuse is the center of the circumcircle of the right triangle, and each of the two triangles created by the partition has two equal radii as two of its sides.
Similarly, an acute triangle can be partitioned into three isosceles triangles by segments from its circumcenter, but this method does not work for obtuse triangles, because the circumcenter lies outside the triangle. | Isosceles triangle | Wikipedia | 382 | 315428 | https://en.wikipedia.org/wiki/Isosceles%20triangle | Mathematics | Two-dimensional space | null |
Generalizing the partition of an acute triangle, any cyclic polygon that contains the center of its circumscribed circle can be partitioned into isosceles triangles by the radii of this circle through its vertices. The fact that all radii of a circle have equal length implies that all of these triangles are isosceles. This partition can be used to derive a formula for the area of the polygon as a function of its side lengths, even for cyclic polygons that do not contain their circumcenters. This formula generalizes Heron's formula for triangles and Brahmagupta's formula for cyclic quadrilaterals.
Either diagonal of a rhombus divides it into two congruent isosceles triangles. Similarly, one of the two diagonals of
a kite divides it into two isosceles triangles, which are not congruent except when the kite is a rhombus.
Applications
In architecture and design
Isosceles triangles commonly appear in architecture as the shapes of gables and pediments. In ancient Greek architecture and its later imitations, the obtuse isosceles triangle was used; in Gothic architecture this was replaced by the acute isosceles triangle.
In the architecture of the Middle Ages, another isosceles triangle shape became popular: the Egyptian isosceles triangle. This is an isosceles triangle that is acute, but less so than the equilateral triangle; its height is proportional to 5/8 of its base. The Egyptian isosceles triangle was brought back into use in modern architecture by Dutch architect Hendrik Petrus Berlage.
Warren truss structures, such as bridges, are commonly arranged in isosceles triangles, although sometimes vertical beams are also included for additional strength.
Surfaces tessellated by obtuse isosceles triangles can be used to form deployable structures that have two stable states: an unfolded state in which the surface expands to a cylindrical column, and a folded state in which it folds into a more compact prism shape that can be more easily transported. The same tessellation pattern forms the basis of Yoshimura buckling, a pattern formed when cylindrical surfaces are axially compressed, and of the Schwarz lantern, an example used in mathematics to show that the area of a smooth surface cannot always be accurately approximated by polyhedra converging to the surface. | Isosceles triangle | Wikipedia | 485 | 315428 | https://en.wikipedia.org/wiki/Isosceles%20triangle | Mathematics | Two-dimensional space | null |
In graphic design and the decorative arts, isosceles triangles have been a frequent design element in cultures around the world from at least the Early Neolithic to modern times. They are a common design element in flags and heraldry, appearing prominently with a vertical base, for instance, in the flag of Guyana, or with a horizontal base in the flag of Saint Lucia, where they form a stylized image of a mountain island.
They also have been used in designs with religious or mystic significance, for instance in the Sri Yantra of Hindu meditational practice.
In other areas of mathematics
If a cubic equation with real coefficients has three roots that are not all real numbers, then when these roots are plotted in the complex plane as an Argand diagram they form vertices of an isosceles triangle whose axis of symmetry coincides with the horizontal (real) axis. This is because the complex roots are complex conjugates and hence are symmetric about the real axis.
In celestial mechanics, the three-body problem has been studied in the special case that the three bodies form an isosceles triangle, because assuming that the bodies are arranged in this way reduces the number of degrees of freedom of the system without reducing it to the solved Lagrangian point case when the bodies form an equilateral triangle. The first instances of the three-body problem shown to have unbounded oscillations were in the isosceles three-body problem.
History and fallacies
Long before isosceles triangles were studied by the ancient Greek mathematicians, the practitioners of Ancient Egyptian mathematics and Babylonian mathematics knew how to calculate their area. Problems of this type are included in the Moscow Mathematical Papyrus and Rhind Mathematical Papyrus.
The theorem that the base angles of an isosceles triangle are equal appears as Proposition I.5 in Euclid. This result has been called the pons asinorum (the bridge of asses) or the isosceles triangle theorem. Rival explanations for this name include the theory that it is because the diagram used by Euclid in his demonstration of the result resembles a bridge, or because this is the first difficult result in Euclid, and acts to separate those who can understand Euclid's geometry from those who cannot. | Isosceles triangle | Wikipedia | 456 | 315428 | https://en.wikipedia.org/wiki/Isosceles%20triangle | Mathematics | Two-dimensional space | null |
A well-known fallacy is the false proof of the statement that all triangles are isosceles, first published by W. W. Rouse Ball in 1892, and later republished in Lewis Carroll's posthumous Lewis Carroll Picture Book. The fallacy is rooted in Euclid's lack of recognition of the concept of betweenness and the resulting ambiguity of inside versus outside of figures. | Isosceles triangle | Wikipedia | 78 | 315428 | https://en.wikipedia.org/wiki/Isosceles%20triangle | Mathematics | Two-dimensional space | null |
The caravel (Portuguese: , ) is a small sailing ship that may be rigged with just lateen sails, or with a combination of lateen and square sails. It was known for its agility and speed and its capacity for sailing windward (beating). Caravels were used by the Portuguese and Spanish for the voyages of exploration during the 15th and 16th centuries, in the Age of Discovery.
The caravel is a poorly understood type of vessel. Though there are now some archaeologically investigated wrecks that are most likely caravels, information on this type is limited. We have a better understanding of the ships of the Greeks and Romans of classical antiquity than we do of the caravel.
History
The long development of the caravel was probably influenced by various Mediterranean tending or coastal craft. Among these influences might have been the boats known as , that were introduced to the Islamic controlled parts of Iberia Al-Andalus from the Maghreb.
The earliest caravels appeared in the thirteenth century along the coasts of Galicia and Portugal as single-masted fishing vessels. They were small, lightly built vessels of up to 20 tons at most, carrying, in one example, a crew of five men. Evidence suggests that these were . They carried a single-masted, triangular lateen sail rig. By the fourteenth century, their size had increased and their use had spread; for instance, there is mention, in 1307, of larger caravels of up to 30 tons in Biscay. Caravels were a common type of vessel in the coastal waters of the Iberian Peninsula in the fifteenth century.
The caravel was the preferred vessel of Portuguese explorers like Diogo Cão, Bartolomeu Dias, Gaspar, and Miguel Corte-Real, and was also used by Spanish expeditions like those of Christopher Columbus. They were agile and easier to navigate than the barca and barinel, with a tonnage of 50 to 160 tons and 1 to 3 masts. Being smaller and having a shallow keel, the caravel was suited for sailing shallow coastal waters and up rivers. With the Mediterranean-type lateen sails attached it was highly maneuverable in shallow waters, while with the square Atlantic-type sails attached it was very fast when crossing the open sea. Its economy, speed, and agility made it esteemed as the best sailing vessel of its time. Its main drawback was its limited capacity for cargo and crew but this did not hinder its success. | Caravel | Wikipedia | 506 | 315598 | https://en.wikipedia.org/wiki/Caravel | Technology | Naval transport | null |
The exploration done with caravels made the spice trade of the Portuguese and the Spanish possible. However, for the trade itself, the caravel was soon replaced by the larger carrack (nau), which could carry larger, more profitable cargoes. The caravel was one of the pinnacle ships in Iberian ship development from 1400 to 1600.
Etymology
The English name caravel derives from the Portuguese , which in turn may derive from the or the perhaps indicating some continuity of its carvel build through the ages.
Design
The earliest caravels in the thirteenth century were small and are believed to have been un-decked, carrying one mast with lateen sails, while later types were larger and had two or three masts and decks. Caravels such as the caravela tilhlda of the 15th century had an average length of between , an average capacity of 50 to 60 tons, a high length-to-beam ratio of around 3.5 to 1, and narrow ellipsoidal frame (unlike the circular frame of the nau), making them very fast and maneuverable but with a limited cargo capacity. It was in such ships that Christopher Columbus set out on his expedition in 1492, while the Santa María was a small carrack of about 150 tons and served as the flagship, the Pinta and ' were caravels of around 15–20 m with a beam of 6 m and a displacement of around 60–75 tons. The Niña was re-rigged by Columbus with square rig to give better performance on the Atlantic crossingmost of which was following favourable winds, for which lateen was less suitable.
Square-rigged caravel
Towards the end of the 15th century, the Portuguese developed a larger version of the caravel, bearing a forecastle and sterncastle – though not as high as those of a carrack, which would have made it unweatherly – but most distinguishable for its square-rigged foremast, and three other masts bearing lateen rig. In this form it was referred to in Portuguese as a "round caravel" () as in Iberian tradition, a bulging square sail is said to be round.
It was employed in coast-guard fleets near the Strait of Gibraltar and as an armed escort for merchant ships between Portugal and Brazil and in the Cape Route. Some consider this a forerunner of the fighting galleon and it remained in use until the 17th century. | Caravel | Wikipedia | 490 | 315598 | https://en.wikipedia.org/wiki/Caravel | Technology | Naval transport | null |
The cockatiel (; Nymphicus hollandicus), also known as the weero/weiro or quarrion, is a medium-sized
parrot that is a member of its own branch of the cockatoo family endemic to Australia. They are prized as exotic household pets and companion parrots throughout the world and are relatively easy to breed compared to other parrots. As a caged bird, cockatiels are second in popularity only to the budgerigar.
The cockatiel is the only member of the genus Nymphicus. It was previously unclear whether the cockatiel is a crested parakeet or small cockatoo; however, more recent molecular studies have assigned it to its own subfamily, Nymphicinae. It is, therefore, now classified as the smallest subfamily of the Cacatuidae (cockatoo family). Cockatiels are native to Australia, favouring the Australian wetlands, scrublands, and bushlands. There are many different mutations of this bird.
Taxonomy and etymology
Originally described by Scottish writer and naturalist Robert Kerr in 1793 as Psittacus hollandicus, the cockatiel (or cockateel) was moved to its own genus, Nymphicus, by Wagler in 1832. Its genus name reflects the experience of one of the earliest groups of Europeans to see the birds in their native habitat; the travellers thought the birds were so beautiful that they named them after mythical nymphs. The specific name hollandicus refers to New Holland, a historical name for Australia.
Its biological relationships were for a long time uncertain; it is now placed in a monotypic subfamily Nymphicinae, but was sometimes in the past classified among the Platycercinae, the broad-tailed parrots. This issue was settled with molecular studies. A 1984 study of protein allozymes signalled its closer relationship to cockatoos than to other parrots, and mitochondrial 12S rRNA sequence data places it among the Calyptorhynchinae (dark cockatoos) subfamily. The unique, parakeet (meaning long-tailed parrot) morphological feature is a consequence of the decrease in size and accompanying change of ecological niche.
Sequence analysis of intron 7 of the nuclear β-fibrinogen gene, on the other hand, indicates that it may yet be distinct enough as to warrant recognition of the Nymphicinae rather than inclusion of the genus in the Calyptorhynchinae. | Cockatiel | Wikipedia | 503 | 315729 | https://en.wikipedia.org/wiki/Cockatiel | Biology and health sciences | Psittaciformes | Animals |
The cockatiel is now biologically classified as a genuine member of Cacatuidae on account of sharing all of the cockatoo family's biological features, namely, the erectile crest, a gallbladder, powder down, suppressed cloudy-layer (which precludes the display of blue and green structural colours), and facial feathers covering the sides of the beak, all of which are rarely found outside the family Cacatuidae. This biological relation to other cockatoos is further supported by the existence of at least one documented case of a successful hybrid between a cockatiel and a galah, another cockatoo species.
Description
Appearance
The cockatiel's distinctive crest expresses the animal's emotional state. The crest is dramatically vertical when the cockatiel is startled or excited, gently oblique in its neutral or relaxed state, and flattened close to the head when the animal is angry or defensive. The crest is also held flat but protrudes outward in the back when the cockatiel is trying to appear alluring or flirtatious. When the cockatiel is tired, the crest is seen positioned halfway upwards, with the tip of the crest usually curling upward. In contrast to most cockatoos, the cockatiel has long tail feathers roughly making up half of its total length. At , the cockatiel is the smallest of the cockatoos, which are generally larger at between .
The "normal grey" or "wild-type" cockatiel's plumage is primarily grey with prominent white flashes on the outer edges of each wing. The face of the male is yellow or white, while the face of the female is primarily grey or light grey, and both sexes feature a round orange area on both ears, often referred to as "cheddar cheeks". This orange colouration is generally vibrant in adult males, and often quite muted in females. Visual sexing is often possible with this variant of the bird. | Cockatiel | Wikipedia | 400 | 315729 | https://en.wikipedia.org/wiki/Cockatiel | Biology and health sciences | Psittaciformes | Animals |
Sexual dimorphism
Most wild cockatiel chicks and juveniles look female, and are virtually indistinguishable from the time of hatching until their first moulting. They display horizontal yellow stripes or bars on the ventral surface of their tail feathers, yellow spots on the ventral surface of the primary flight feathers of their wings, a grey coloured crest and face, and a dull orange patch on each of their cheeks. However some modern-day mutations are sex linked and the male and female chicks are easily distinguishable as soon as their feathers come in.
Adult cockatiels with common coloring (grey body with yellow head) are sexually dimorphic, though to a lesser degree than many other avian species. This is only evident after the first moulting, typically occurring about six to nine months after hatching: the male loses the white or yellow barring and spots on the underside of his tail feathers and wings. The grey feathers on his cheeks and crest are replaced by bright yellow feathers, while the orange cheek patch becomes brighter and more distinct. The face and crest of the female will typically remain mostly grey with a yellowish tint, and a less vibrant orange cheek patch. Additionally, the female commonly retains the horizontal barring on the underside of her tail feathers.
The colour in cockatiels is derived from two pigments: melanin (which provides the grey colour in the feathers, eyes, beak, and feet), and psittacofulvins (which provide the yellow colour on the face and tail and the orange colour of the cheek patch). The grey colour of the melanin overrides the yellow and orange of the psittacofulvins when both are present.
The melanin content decreases in the face of the males as they mature, allowing the yellow and orange psittacofulvins to be more visible, while an increase in melanin content in the tail causes the disappearance of the horizontal yellow tail bars.
In addition to these visible characteristics, the vocalisation of adult males is typically louder and more complex than that of females. But like most things this is not a hard and fast rule.
Colour mutations | Cockatiel | Wikipedia | 441 | 315729 | https://en.wikipedia.org/wiki/Cockatiel | Biology and health sciences | Psittaciformes | Animals |
Worldwide there are currently 22 cockatiel colour mutations established in aviculture, of which eight are exclusive to Australia. Mutations in captivity have emerged in various colours, some quite different from those observed in nature. Wild cockatiels are grey with visible differences between males and females. Male grey cockatiels typically have yellow heads while the female has a grey head. Juveniles tend to look like females with pinker beaks. The pied mutation first appeared in California in 1949. This mutation is a blotch of colour on an otherwise solid-coloured bird. For example, this may appear as a grey blotch on a yellow cockatiel.
Lutino colouration was first seen in 1958. These birds lack the grey of their wild counterparts and are white to soft yellow. This is a popular colour; due to inbreeding, these cockatiels often have a small bald patch behind their crests. The cinnamon mutation, first seen in the 1950s, is very similar in appearance to the grey; however, these birds have a warmer, browner colouring. Pearling was first seen in 1967. This is seen as a feather of one colour with a different coloured edge, such as grey feathers with yellow tips. This distinctive pattern is on a bird's wings or back. The albino colour mutation is a lack of pigment. These birds are white with red eyes. Fallow cockatiels first appeared sometime in the 1970s. This mutation shows as a bird with cinnamon colouring with yellow sections. Other mutations include emerald/olive, dominant and recessive silver, and mutations exclusive to Australia: Australian fallow, faded (west coast silver), dilute/pastel silver (east coast silver), silver spangle (edged dilute), platinum, suffused (Australian olive), and pewter. Other mutations, such as face altering mutations, include whiteface, , dominant yellow cheek, sex-linked yellow cheek, gold cheek, cream face, and the Australian yellow cheek.
Cockatiel colour mutations can become even more complex as one bird can have multiple colour mutations. For example, a yellow lutino cockatiel may have pearling – white spots on its back and wings. This is a double mutation. An example of a quadruple mutation would be cinnamon cockatiel with yellowface colouring with pearling and pied markings. | Cockatiel | Wikipedia | 483 | 315729 | https://en.wikipedia.org/wiki/Cockatiel | Biology and health sciences | Psittaciformes | Animals |
Breeding and life span
Breeding is triggered by seasonal rainfall. Cockatiels nest in tree hollows near a source of fresh water, often choosing eucalyptus/gum trees. The hen lays 4-7 eggs, one every other day, which she incubates for 17–23 days. The chicks fledge after 5 weeks. Cockatiels are the only cockatoo species which may reproduce by the end of their first year.
The cockatiel's average life span is 12 to 15 years, though in captivity and under appropriate living conditions, a cockatiel could be expected to live from 16 to 25 years. The oldest living and confirmed specimen of cockatiel was reportedly 36 years old.
Distribution and habitat
Cockatiels are native to Australia, where they are found largely in arid or semi-arid country but always close to water. Largely nomadic, the species will move to where food and water is available. They are typically seen in pairs or small flocks. Sometimes, hundreds will flock around a single body of water. Wild cockatiels typically eat seeds, particularly Acacia, wheat, sunflower and Sorghum. To many farmers' dismay, they often eat cultivated crops. Cockatiels may be observed in and around western New South Wales and Queensland, Alice Springs, The Kimberley region and the northwestern corner of Western Australia. They are absent from the most fertile southwest and southeast corners of the country, the deepest Western Australian deserts, and Cape York Peninsula.
Speech and vocalization
Cockatiels can be very vocal and learn many spoken words and phrases by mimicking. Usually, males are faster to learn speech, mimicking or singing; their calls are also more varied.
Cockatiels can also be taught to sing specific melodies, to the extent that some cockatiels have been demonstrated to synchronise their melodies with the songs of humans. Without being taught how to both male and female cockatiels repeat household sounds, including alarm clocks, phones, tunes or other birds from the outdoors. | Cockatiel | Wikipedia | 405 | 315729 | https://en.wikipedia.org/wiki/Cockatiel | Biology and health sciences | Psittaciformes | Animals |
Secure Digital, officially abbreviated as SD, is a proprietary, non-volatile, flash memory card format the SD Association (SDA) developed for use in portable devices.
Because of their small physical dimensions, SD cards became widely used in many consumer electronic devices, such as digital cameras, camcorders, video game consoles, mobile phones, action cameras such as the GoPro Hero series, and camera drones.
The standard was introduced in August 1999 by SanDisk, Panasonic (Matsushita) and Toshiba as an improvement on MultiMediaCards (MMCs). SDs have become an industry standard. The three companies formed SD-3C, LLC, a company that licenses and enforces intellectual property (IP) rights associated with SD memory cards and SD host-and-ancillary products.
In January 2000, the companies formed the SD Association (SDA), a non-profit organization to create and promote SD card standards. , the SDA has approximately 1,000 member companies. It uses several SD-3C-owned trademarked logos to enforce compliance with its specifications and denote compatibility.
History
1999–2005: Creation and introduction of smaller formats
In 1999, SanDisk, Panasonic (Matsushita) and Toshiba agreed to develop and market the Secure Digital (SD) memory card. The card was derived from the MultiMediaCard (MMC) and provided digital rights management (DRM) based on the Secure Digital Music Initiative (SDMI) standard and a high memory density ("data/bits per physical space"), i.e. a large quantity of data could be stored in a small physical space.
SD was designed to compete with the Memory Stick, a flash storage format with DRM Sony had released the year before. Toshiba hoped the SD card's DRM would encourage music suppliers concerned about piracy to use SD cards.
The trademarked SD logo was originally developed for the Super Density Disc, which was the unsuccessful Toshiba entry in the DVD format war. For this reason, the letter "D" is styled to resemble an optical disc. | SD card | Wikipedia | 428 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
At the 2000 Consumer Electronics Show (CES), the three companies announced the creation of the SD Association (SDA) to promote SD cards. The SD Association, which was headquartered in San Ramon, California, United States, then had 30 member companies and product manufacturers that made interoperable memory cards and devices. Early samples of the SD card became available in the first quarter of 2000, and production quantities of 32 and 64 megabyte (MB) cards became available three months later. The first 64 MB cards were offered for sale for US$200. SD was envisioned as a single memory card format for several kinds of electronic devices, that could also function as an expansion slot for adding new capabilities for a device. The first 256 MB and 512 MB SD cards were announced in 2001.
miniSD
At March 2003 CeBIT, SanDisk Corporation introduced, announced and demonstrated the miniSD form factor. The SDA adopted the miniSD card in 2003 as a small-form-factor extension to the SD card standard. While the new cards were designed for mobile phones, they were usually packaged with a miniSD adapter that provided compatibility with a standard SD memory card slot.
microSD
MicroSD form-factor memory cards were introduced in 2004 by SanDisk at CeBIT and originally called T-Flash, and later TransFlash, commonly abbreviated to "TF". T-Flash was renamed microSD in 2005 when it was adopted by the SDA. TransFlash and microSD cards are functionally identical, allowing either to operate in devices made for the other. A passive adapter allows the use of microSD and TransFlash cards in SD card slots.
2006–2008: SDHC and SDIO
In September 2006, SanDisk announced the 4 GB miniSDHC. Like the SD and SDHC, the miniSDHC card has the same form factor as the older miniSD card but the HC card requires HC support built into the host device. Devices that support miniSDHC work with miniSD and miniSDHC, but devices without specific support for miniSDHC work only with the older miniSD card. Since 2008, miniSD cards are no longer produced, due to market domination of the even smaller microSD cards.
2009–2019: SDXC | SD card | Wikipedia | 459 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
The storage density of memory cards increased significantly throughout the 2010s, allowing the earliest devices to offer support for the SD:XC standard, such as the Samsung Galaxy S III and Samsung Galaxy Note II mobile phones, to expand their available storage to several hundreds of gigabytes.
In January 2009, the SDA announced the SDXC family, which supports cards up to 2 TB and speeds up to 300 MB/s. SDXC cards are formatted with the exFAT file system by default. SDXC was announced at the Consumer Electronics Show (CES) 2009 (January 7–10). At the same show, SanDisk and Sony also announced a comparable Memory Stick XC variant with the same 2 TB maximum as SDXC, and Panasonic announced plans to produce 64 GB SDXC cards. On March 6, Pretec introduced the first SDXC card, a 32 GB card with a read/write speed of 400 Mbit/s. But only early in 2010 did compatible host devices come onto the market, including Sony's Handycam HDR-CX55V camcorder, Canon's EOS 550D (also known as Rebel T2i) Digital SLR camera, a USB card reader from Panasonic, and an integrated SDXC card reader from JMicron. The earliest laptops to integrate SDXC card readers relied on a USB 2.0 bus, which does not have the bandwidth to support SDXC at full speed.
In early 2010, commercial SDXC cards appeared from Toshiba (64 GB), Panasonic (64 GB and 48 GB), and SanDisk (64 GB).
In early 2011, Centon Electronics, Inc. (64 GB and 128 GB) and Lexar (128 GB) began shipping SDXC cards rated at Speed Class 10. Pretec offered cards from 8 GB to 128 GB rated at Speed Class 16. In September 2011, SanDisk released a 64 GB microSDXC card. Kingmax released a comparable product in 2011.
In April 2012, Panasonic introduced MicroP2 card format for professional video applications. The cards are essentially full-size SDHC or SDXC UHS-II cards, rated at UHS Speed Class U1. An adapter allows MicroP2 cards to work in current P2 card equipment. | SD card | Wikipedia | 485 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Panasonic MicroP2 cards shipped in March 2013 and were the first UHS-II compliant products on market; initial offer includes a 32 GB SDHC card and a 64 GB SDXC card. Later that year, Lexar released the first 256 GB SDXC card, based on 20 nm NAND flash technology.
In February 2014, SanDisk introduced the first 128 GB microSDXC card, which was followed by a 200 GB microSDXC card in March 2015. September 2014 saw SanDisk announce the first 512 GB SDXC card.
Samsung announced the world's first EVO Plus 256 GB microSDXC card in May 2016, and in September 2016 Western Digital (SanDisk) announced that a prototype of the first 1 TB SDXC card would be demonstrated at Photokina.
In August 2017, SanDisk launched a 400 GB microSDXC card.
In January 2018, Integral Memory unveiled its 512 GB microSDXC card. In May 2018, PNY launched a 512 GB microSDXC card. In June 2018 Kingston announced its Canvas series of microSD cards which were capable of capacities up to 512 GB, in three variations, Select, Go! and React.
In February 2019, Micron and SanDisk unveiled their microSDXC cards of 1 TB capacity.
2019–present: SDUC
The Secure Digital Ultra Capacity (SDUC) format supports cards up to 128 TB and offers speeds up to 985 MB/s.
In April 2024, Western Digital (SanDisk) revealed the world's first 4 TB SD card at NAB 2024, which will make use of the SDUC format. It is set to release in 2025.
Capacity
Secure Digital includes five card families available in three form factors. The five families are the original standard capacity (SDSC), high capacity (SDHC), extended capacity (SDXC), ultra capacity (SDUC) and SDIO, which combines input/output functions with data storage.
SD (SDSC)
The second-generation Secure Digital (SDSC or Secure Digital Standard Capacity) card was developed to improve on the MultiMediaCard (MMC) standard, which continued to evolve, but in a different direction. Secure Digital changed the MMC design in several ways: | SD card | Wikipedia | 466 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Asymmetrical shape of the sides of the SD card prevents inserting it upside down (whereas an MMC goes in most of the way but makes no contact if inverted).
Most standard size SD cards are thick, with microSD versions being thick, compared to for MMCs. The SD specification defines a card called Thin SD with a thickness of 1.4 mm, but they occur only rarely, as the SDA went on to define even smaller form factors.
The card's electrical contacts are recessed beneath the surface of the card, protecting them from contact with a user's fingers.
The SD specification envisioned capacities and transfer rates exceeding those of MMC, and both of these functionalities have grown over time. For a comparison table, see below.
While MMC uses a single pin for data transfers, the SD card added a four-wire bus mode for higher data rates.
The SD card added Content Protection for Recordable Media (CPRM) security circuitry for digital rights management (DRM) content-protection.
Addition of a write-protect notch
Full-size SD cards do not fit into the slimmer MMC slots, and other issues also affect the ability to use one format in a host device designed for the other.
SDHC
The Secure Digital High Capacity (SDHC) format, announced in January 2006 and defined in version 2.0 of the SD specification, supports cards with capacities up to 32 GB. The SDHC trademark is licensed to ensure compatibility.
SDHC cards are physically and electrically identical to standard-capacity SD cards (SDSC). The major compatibility issues between SDHC and SDSC cards are the redefinition of the Card-Specific Data (CSD) register in version 2.0 (see below), and the fact that SDHC cards are shipped preformatted with the FAT32 file system.
Version 2.0 also introduces a high-speed bus mode for both SDSC and SDHC cards, which doubles the original Standard Speed clock to produce 25 MB/s.
SDHC host devices are required to accept older SD cards. However, older host devices do not recognize SDHC or SDXC memory cards, although some devices can do so through a firmware upgrade. Older Windows operating systems released before Windows 7 require patches or service packs to support access to SDHC cards.
SDXC | SD card | Wikipedia | 478 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
The Secure Digital eXtended Capacity (SDXC) format, announced in January 2009 and defined in version 3.01 of the SD specification, supports cards up to 2 TB, compared to a limit of 32 GB for SDHC cards in the SD 2.0 specification. SDXC adopts Microsoft's exFAT file system as a mandatory feature.
Version 3.01 also introduced the Ultra High Speed (UHS) bus for both SDHC and SDXC cards, with interface speeds from 50 MB/s to 104 MB/s for four-bit UHS-I bus. (this number has since been exceeded with SanDisk proprietary technology for 170 MB/s read, which is not proprietary anymore, as Lexar has the 1066x running at 160 MB/s read and 120 MB/s write via UHS 1, and Kingston also has their Canvas Go! Plus, also running at 170 MB/s).
Version 4.0, introduced in June 2011, allows speeds of 156 MB/s to 312 MB/s over the four-lane (two differential lanes) UHS-II bus, which requires an additional row of physical pins.
Version 5.0 was announced in February 2016 at CP+ 2016, and added "Video Speed Class" ratings for UHS cards to handle higher resolution video formats like 8K. The new ratings define a minimal write speed of 90 MB/s.
SDXC cards are required to be formatted using exFAT, but many operating systems will support others.
Windows Vista (SP1) and later and OS X (10.6.5 and later) have native support for exFAT. (Windows XP and Server 2003 can support exFAT via an optional update from Microsoft.)
Most BSD and Linux distributions did not have exFAT support for legal reasons, though in Linux kernel 5.4 Microsoft open-sourced the spec and allowed the inclusion of an exFAT driver. Users of older kernels or BSD can manually install third-party implementations of exFAT (as a FUSE module) in order to be able to mount exFAT-formatted volumes. However, SDXC cards can be reformatted to use any file system (such as ext4, UFS, VFAT or NTFS), alleviating the restrictions associated with exFAT availability.
The SD Association provides a formatting utility for Windows and Mac OS X that checks and formats SD, SDHC, SDXC and SDUC cards. | SD card | Wikipedia | 505 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Except for the change of file system, SDXC cards are mostly backward compatible with SDHC readers, and many SDHC host devices can use SDXC cards if they are first reformatted to the FAT32 file system.
SDUC
The Secure Digital Ultra Capacity (SDUC) format, described in the SD 7.0 specification, and announced in June 2018, supports cards up to 128 TB, regardless of form factor, either micro or full size, or interface type including UHS-I, UHS-II, UHS-III or SD Express.
Speed
SD card speed is customarily rated by its sequential read or write speed. The sequential performance aspect is the most relevant for storing and retrieving large files (relative to block sizes internal to the flash memory), such as images and multimedia. Small data (such as file names, sizes and timestamps) falls under the much lower speed limit of random access, which can be the limiting factor in some use cases.
With early SD cards, a few card manufacturers specified the speed as a "times" ("×") rating, which compared the average speed of reading data to that of the original CD-ROM drive. This was superseded by the Speed Class Rating, which guarantees a minimum rate at which data can be written to the card.
The newer families of SD card improve card speed by increasing the bus rate (the frequency of the clock signal that strobes information into and out of the card). Whatever the bus rate, the card can signal to the host that it is "busy" until a read or a write operation is complete. Compliance with a higher speed rating is a guarantee that the card limits its use of the "busy" indication.
Bus
Default Speed
SD cards will read and write at speeds of 12.5 MB/s.
High Speed
High-Speed Mode (25 MB/s) was introduced to support digital cameras with 1.10 spec version.
UHS (Ultra High Speed)
The Ultra High Speed (UHS) bus is available on some SDHC and SDXC cards. | SD card | Wikipedia | 424 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Cards that comply with UHS show Roman numerals 'I', 'II' or 'III' next to the SD card logo, and report this capability to the host device. Use of UHS-I requires that the host device command the card to drop from 3.3-volt to 1.8-volt operation over the I/O interface pins and select the four-bit transfer mode, while UHS-II requires 0.4-volt operation.
The higher speed rates of UHS-II and III are achieved by using two-lane 0.4 V low-voltage differential signaling (LVDS) on a second row of pins. Each lane is capable of transferring up to 156 MB/s. In full-duplex mode, one lane is used for Transmit while the other is used for Receive. In half-duplex mode both lanes are used for the same direction of data transfer allowing a double data rate at the same clock speed. In addition to enabling higher data rates, the UHS-II interface allows for lower interface power consumption, lower I/O voltage and lower electromagnetic interference (EMI).
The following ultra-high speeds are specified:
UHS-I
Specified in SD version 3.01. Supports a clock frequency of 100 MHz (a quadrupling of the original "Default Speed"), which in four-bit transfer mode could transfer 50 MB/s (SDR50). UHS-I cards declared as UHS104 (SDR104) also support a clock frequency of 208 MHz, which could transfer 104 MB/s. Double data rate operation at 50 MHz (DDR50) is also specified in Version 3.01, and is mandatory for microSDHC and microSDXC cards labeled as UHS-I. In this mode, four bits are transferred when the clock signal rises and another four bits when it falls, transferring an entire byte on each full clock cycle, hence a 50 MB/s operation could be transferred using a 50 MHz clock. | SD card | Wikipedia | 417 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
There is a proprietary UHS-I extension, called DDR200, originally created by SanDisk that increases transfer speed further to 170 MB/s. Unlike UHS-II, it does not use additional pins. It achieves this by using the 208 MHz frequency of the standard SDR104 mode, but using DDR transfers. This extension has since then been used by Lexar for their 1066x series (160 MB/s), Kingston Canvas Go Plus (170 MB/s) and the MyMemory PRO SD card (180 MB/s).
UHS-II
Specified in version 4.0, further raises the data transfer rate to a theoretical maximum of 156 MB/s (full-duplex) or 312 MB/s (half-duplex) using an additional row of pins for LVDS signalling (a total of 17 pins for full-size and 16 pins for micro-size cards). While first implementations in compact system cameras were seen three years after specification (2014), it took many more years until UHS-II was implemented on a regular basis. At the beginning of 2025, 100 DSLR and mirrorless cameras support UHS-II.
UHS-III
Version 6.0, released in February 2017, added two new data rates to the standard. FD312 provides 312 MB/s while FD624 doubles that. Both are full-duplex. The physical interface and pin-layout are the same as with UHS-II, retaining backward compatibility.
SD Express
The SD Express bus was released in June 2018 with SD specification 7.0. It uses a single PCIe lane to provide full-duplex 985 MB/s transfer speed. Supporting cards must also implement the NVM Express storage access protocol. The Express bus can be implemented by SDHC, SDXC and SDUC cards. For legacy application use, SD Express cards must also support High-Speed bus and UHS-I bus. The Express bus re-uses the pin layout of UHS-II cards and reserves the space for additional two pins that may be introduced in the future.
Hosts which implement version 7.0 of the spec allow SD Cards to do direct memory access, which increases the attack surface of the host dramatically in the face of malicious SD cards. | SD card | Wikipedia | 474 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Version 8.0 was announced on 19 May 2020, with support for two PCIe lanes with an additional row of contacts and PCIe 4.0 transfer rates, for a maximum bandwidth of 3,938 MB/s.
Version 9.0 was released in February 2022.
Version 9.1 was announced in October 2023.
microSD Express
In February 2019, the SD Association announced microSD Express. The microSD Express cards offer PCI Express and NVMe interfaces, as the June 2018 SD Express release did, alongside the legacy microSD interface for continued backwards compatibility. The SDA also released visual marks to denote microSD Express memory cards to make matching the card and device easier for optimal device performance.
Class
The SD Association defines standard speed classes for SDHC/SDXC cards indicating minimum performance (minimum serial data writing speed). Both read and write speeds must exceed the specified value. The specification defines these classes in terms of performance curves that translate into the following minimum read-write performance levels on an empty card and suitability for different applications:
The SD Association defines three types of Speed Class ratings: the original Speed Class, UHS Speed Class and Video Speed Class.
Speed Class
Speed Class ratings 2, 4 and 6 assert that the card supports the respective number of megabytes per second as a minimum sustained write speed for a card in a fragmented state.
Class 10 asserts that the card supports 10 MB/s as a minimum non-fragmented sequential write speed and uses a High Speed bus mode. The host device can read a card's speed class and warn the user if the card reports a speed class that falls below an application's minimum need. By comparison, the older "×" rating measured maximum speed under ideal conditions, and was vague as to whether this was read speed or write speed.
The graphical symbol for the speed class has a number encircled with 'C' (C2, C4, C6 and C10).
"×" rating | SD card | Wikipedia | 400 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
The "×" rating, which was used by some card manufacturers and made obsolete by speed classes, is a multiple of the standard CD-ROM drive speed of 150 KB/s (approximately 1.23 Mbit/s). Basic cards transfer data at up to six times (6×) the CD-ROM speed; that is, 900 kbit/s or 7.37 Mbit/s. The 2.0 specification defines speeds up to 200×, but is not as specific as Speed Classes are on how to measure speed. Manufacturers may report best-case speeds and may report the card's fastest read speed, which is typically faster than the write speed. Some vendors, including Transcend and Kingston, report their cards' write speed. When a card lists both a speed class and an "×" rating, the latter may be assumed a read speed only.
UHS Speed Class
UHS-I and UHS-II cards can use UHS Speed Class rating with two possible grades: class 1 for minimum write performance of at least 10 MB/s ('U1' symbol featuring number 1 inside 'U') and class 3 for minimum write performance of 30 MB/s ('U3' symbol featuring 3 inside 'U'), targeted at recording 4K video. Before November 2013, the rating was branded UHS Speed Grade and contained grades 0 (no symbol) and 1 ('U1' symbol). Manufacturers can also display standard speed class symbols (C2, C4, C6 and C10) alongside, or in place of UHS speed class.
UHS memory cards work best with UHS host devices. The combination lets the user record HD resolution videos with tapeless camcorders while performing other functions. It is also suitable for real-time broadcasts and capturing large HD videos.
Video Speed Class
Video Speed Class defines a set of requirements for UHS cards to match the modern MLC NAND flash memory and supports progressive 4K and 8K video with minimum sequential writing speeds of 6 – 90 MB/s. The graphical symbols use a stylized 'V' followed by a number designating write speed (i.e. V6, V10, V30, V60 and V90). | SD card | Wikipedia | 456 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
SD Express Speed Class
Version 9.1 of the SD specification, introduced in October 2023, defines new SD Express speed classes. The graphical symbols use a stylized 'E' followed by a number designating the minimum read/write speed. The specified classes are E150, E300, E450 and E600.
Application Performance Class
Application Performance Class is a newly defined standard from the SD Specification 5.1 and 6.0 which not only define sequential Writing Speeds but also mandates a minimum IOPS for reading and writing. Class A1 requires a minimum of 1,500 reading and 500 writing operations per second using 4 kbytes blocks, while class A2 requires 4,000 and 2,000 IOPS. A2 class cards require host driver support as they use command queuing and write caching to achieve their higher speeds. Without they are guaranteed to at least reach A1 speeds. As of Linux kernel 5.15, it fully supports A2.
Real-world performance
In applications that require sustained write throughput, such as video recording, the device might not perform satisfactorily if the SD card's class rating falls below a particular speed. For example, a high-definition camcorder may require a card of not less than Class 6, suffering dropouts or corrupted video if a slower card is used. Digital cameras with slow cards may take a noticeable time after taking a photograph before being ready for the next, while the camera writes the first picture.
The speed class rating does not totally characterize card performance. Different cards of the same class may vary considerably while meeting class specifications. A card's speed depends on many factors, including:
The frequency of soft errors that the card's controller must re-try
Write amplification: The flash controller may need to overwrite more data than requested. This has to do with performing read-modify-write operations on write blocks, freeing up (the much larger) erase blocks, while moving data around to achieve wear leveling.
File fragmentation: where there is not sufficient space for a file to be recorded in a contiguous region, it is split into non-contiguous fragments. This does not cause rotational or head-movement delays as with electromechanical hard drives, but may decrease speed—for instance, by requiring additional reads and computation to determine where on the card the file's next fragment is stored. | SD card | Wikipedia | 482 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
In addition, speed may vary markedly between writing a large amount of data to a single file (sequential access, as when a digital camera records large photographs or videos) and writing a large number of small files (a random-access use common in smartphones). A study in 2012 found that, in this random-access use, some Class 2 cards achieved a write speed of 1.38 MB/s, while all cards tested of Class 6 or greater (and some of lower Classes; lower Class does not necessarily mean better small-file performance), including those from major manufacturers, were over 100 times slower. In 2014, a blogger measured a 300-fold performance difference on small writes; this time, the best card in this category was a class 4 card.
Features
Card security
Commands to disable writes
The host device can command the SD card to become read-only (to reject subsequent commands to write information to it). There are both reversible and irreversible host commands that achieve this.
Write-protect notch
Most full-size SD cards have a "mechanical write protect switch" allowing the user to advise the host computer that the user wants the device to be treated as read-only. This does not protect the data on the card if the host is compromised: "It is the responsibility of the host to protect the card. The position [i.e., setting] of the write protect switch is unknown to the internal circuitry of the card." Some host devices do not support write protection, which is an optional feature of the SD specification, and drivers and devices that do obey a read-only indication may give the user a way to override it.
The switch is a sliding tab that covers a notch in the card. The miniSD and microSD formats do not directly support a write protection notch, but they can be inserted into full-size adapters which do.
When looking at the SD card from the top, the right side (the side with the beveled corner) must be notched. | SD card | Wikipedia | 414 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
On the left side, there may be a write-protection notch. If the notch is omitted, the card can be read and written. If the card is notched, it is read-only. If the card has a notch and a sliding tab which covers the notch, the user can slide the tab upward (toward the contacts) to declare the card read/write, or downward to declare it read-only. The diagram to the right shows an orange sliding write-protect tab in both the unlocked and locked positions.
Cards sold with content that must not be altered are permanently marked read-only by having a notch and no sliding tab.
Card password
A host device can lock an SD card using a password of up to 16 bytes, typically supplied by the user. A locked card interacts normally with the host device except that it rejects commands to read and write data. A locked card can be unlocked only by providing the same password. The host device can, after supplying the old password, specify a new password or disable locking. Without the password (typically, in the case that the user forgets the password), the host device can command the card to erase all the data on the card for future re-use (except card data under DRM), but there is no way to gain access to the existing data.
Windows Phone 7 devices use SD cards designed for access only by the phone manufacturer or mobile provider. An SD card inserted into the phone underneath the battery compartment becomes locked "to the phone with an automatically generated key" so that "the SD card cannot be read by another phone, device, or PC". Symbian devices, however, are some of the few that can perform the necessary low-level format operations on locked SD cards. It is therefore possible to use a device such as the Nokia N8 to reformat the card for subsequent use in other devices.
smartSD cards
A smartSD memory card is a microSD card with an internal "secure element" that allows the transfer of ISO 7816 Application Protocol Data Unit commands to, for example, JavaCard applets running on the internal secure element through the SD bus. | SD card | Wikipedia | 436 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Some of the earliest versions of microSD memory cards with secure elements were developed in 2009 by DeviceFidelity, Inc., a pioneer in near-field communication (NFC) and mobile payments, with the introduction of In2Pay and CredenSE products, later commercialized and certified for mobile contactless transactions by Visa in 2010. DeviceFidelity also adapted the In2Pay microSD to work with the Apple iPhone using the iCaisse, and pioneered the first NFC transactions and mobile payments on an Apple device in 2010.
Various implementations of smartSD cards have been done for payment applications and secured authentication. In 2012 Good Technology partnered with DeviceFidelity to use microSD cards with secure elements for mobile identity and access control.
microSD cards with Secure Elements and NFC (near-field communication) support are used for mobile payments, and have been used in direct-to-consumer mobile wallets and mobile banking solutions, some of which were launched by major banks around the world, including Bank of America, US Bank and Wells Fargo, while others were part of innovative new direct-to-consumer neobank programs such as moneto, first launched in 2012.
microSD cards with Secure Elements have also been used for secure voice encryption on mobile devices, which allows for one of the highest levels of security in person-to-person voice communications. Such solutions are heavily used in intelligence and security.
In 2011, HID Global partnered with Arizona State University to launch campus access solutions for students using microSD with Secure Element and MiFare technology provided by DeviceFidelity, Inc. This was the first time regular mobile phones could be used to open doors without need for electronic access keys.
Vendor enhancements | SD card | Wikipedia | 341 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Vendors have sought to differentiate their products in the market through various vendor-specific features:
Integrated Wi-Fi – Several companies produce SD cards with built-in Wi-Fi transceivers supporting static security (WEP 40/104/128, WPA-PSK and WPA2-PSK). The card lets any digital camera with an SD slot transmit captured images over a wireless network, or store the images on the card's memory until it is in range of a wireless network. Examples include: Eye-Fi / SanDisk, Transcend Wi-Fi, Toshiba FlashAir, Trek Flucard, PQI Air Card and LZeal ez Share. Some models geotag their pictures.
Pre-loaded content – In 2006, SanDisk announced Gruvi, a microSD card with extra digital rights management features, which they intended as a medium for publishing content. SanDisk again announced pre-loaded cards in 2008, under the slotMusic name, this time not using any of the DRM capabilities of the SD card. In 2011, SanDisk offered various collections of 1000 songs on a single slotMusic card for about $40, now restricted to compatible devices and without the ability to copy the files.
Integrated USB connector – The SanDisk SD Plus product can be plugged directly into a USB port without needing a USB card reader. Other companies introduced comparable products, such as the Duo SD product of OCZ Technology and the 3 Way (microSDHC, SDHC and USB) product of A-DATA, which was available in 2008 only.
Different colors – SanDisk has used various colors of plastic or adhesive label, including a "gaming" line in translucent plastic colors that indicated the card's capacity. In 2006, the first 256MB microSD to used color-coded cards by Kingmax, which later other brands (e.g., SanDisk, Kioxia) had been implemented to this day.
Integrated display – In 2006, ADATA announced a Super Info SD card with a digital display that provided a two-character label and showed the amount of unused memory on the card.
SDIO cards | SD card | Wikipedia | 436 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
A SDIO (Secure Digital Input Output) card is an extension of the SD specification to cover I/O functions. SDIO cards are only fully functional in host devices designed to support their input-output functions (typically PDAs like the Palm Treo, but occasionally laptops or mobile phones). These devices can use the SD slot to support GPS receivers, modems, barcode readers, FM radio tuners, TV tuners, RFID readers, digital cameras and interfaces to Wi-Fi, Bluetooth, Ethernet and IrDA. Many other SDIO devices have been proposed, but it is now more common for I/O devices to connect using the USB interface.
SDIO cards support most of the memory commands of SD cards. SDIO cards can be structured as eight logical cards, although currently, the typical way that an SDIO card uses this capability is to structure itself as one I/O card and one memory card.
The SDIO and SD interfaces are mechanically and electrically identical. Host devices built for SDIO cards generally accept SD memory cards without I/O functions. However, the reverse is not true, because host devices need suitable drivers and applications to support the card's I/O functions. For example, an HP SDIO camera usually does not work with PDAs that do not list it as an accessory. Inserting an SDIO card into any SD slot causes no physical damage nor disruption to the host device, but users may be frustrated that the SDIO card does not function fully when inserted into a seemingly compatible slot. (USB and Bluetooth devices exhibit comparable compatibility issues, although to a lesser extent thanks to standardized USB device classes and Bluetooth profiles.)
The SDIO family comprises Low-Speed and Full-Speed cards. Both types of SDIO cards support Serial Peripheral Interface (SPI) and one-bit SD bus types. Low-Speed SDIO cards are allowed to also support the four-bit SD bus; Full-Speed SDIO cards are required to support the four-bit SD bus. To use an SDIO card as a "combo card" (for both memory and I/O), the host device must first select four-bit SD bus operation. Two other unique features of Low-Speed SDIO are a maximum clock rate of 400 kHz for all communications, and the use of Pin 8 as "interrupt" to try to initiate dialogue with the host device. | SD card | Wikipedia | 490 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Compatibility
Host devices that comply with newer versions of the specification provide backward compatibility and accept older SD cards. For example, SDXC host devices accept all previous families of SD memory cards, and SDHC host devices also accept standard SD cards.
Older host devices generally do not support newer card formats, and even when they might support the bus interface used by the card, there are several factors that arise:
A newer card may offer greater capacity than the host device can handle (over 4 GB for SDHC, over 32 GB for SDXC).
A newer card may use a file system the host device cannot navigate (FAT32 for SDHC, exFAT for SDXC)
Use of an SDIO card requires the host device be designed for the input/output functions the card provides.
The hardware interface of the card was changed starting with the version 2.0 (new high-speed bus clocks, redefinition of storage capacity bits) and SDHC family (ultra-high speed (UHS) bus)
UHS-II has physically more pins but is backwards compatible to UHS-I and non-UHS for both slot and card.
Some vendors produced SDSC cards above 1 GB before the SDA had standardized a method of doing so.
Markets
Due to their compact size, Secure Digital cards are used in many consumer electronic devices, and have become a widespread means of storing several gigabytes of data in a small size. Devices in which the user may remove and replace cards often, such as digital cameras, camcorders and video game consoles, tend to use full-sized cards. Devices in which small size is paramount, such as mobile phones, action cameras such as the GoPro Hero series, and camera drones, tend to use microSD cards.
Mobile phones
The microSD card has helped propel the smartphone market by giving both manufacturers and consumers greater flexibility and freedom. | SD card | Wikipedia | 383 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
While cloud storage depends on stable internet connection and sufficiently voluminous data plans, memory cards in mobile devices provide location-independent and private storage expansion with much higher transfer rates and no network delay, enabling applications such as photography and video recording. While data stored internally on bricked devices is inaccessible, data stored on the memory card can be salvaged and accessed externally by the user as mass storage device. A benefit over USB on the go storage expansion is uncompromised ergonomy. The usage of a memory card also protects the mobile phone's non-replaceable internal storage from weardown from heavy applications such as excessive camera usage and portable FTP server hosting over WiFi Direct. Due to the technical development of memory cards, users of existing mobile devices are able to expand their storage further and priceworthier with time.
Recent versions of major operating systems such as Windows Mobile and Android allow applications to run from microSD cards, creating possibilities for new usage models for SD cards in mobile computing markets, as well as clearing available internal storage space.
SD cards are not the most economical solution in devices that need only a small amount of non-volatile memory, such as station presets in small radios. They may also not present the best choice for applications that require higher storage capacities or speeds as provided by other flash card standards such as CompactFlash. These limitations may be addressed by evolving memory technologies, such as the new SD 7.0 specifications which allow storage capabilities of up to 128 TB.
Many personal computers of all types, including tablets and mobile phones, use SD cards, either through built-in slots or through an active electronic adapter. Adapters exist for the PC card, ExpressBus, USB, FireWire and the parallel printer port. Active adapters also let SD cards be used in devices designed for other formats, such as CompactFlash. The FlashPath adapter lets SD cards be used in a floppy disk drive.
Some devices such as the Samsung Galaxy Fit (2011) and Samsung Galaxy Note 8.0 (2013) have an SD card compartment located externally and accessible by hand, while it is located under the battery cover on other devices. More recent mobile phones use a pin-hole ejection system for the tray which houses both the memory card and SIM card.
Counterfeits | SD card | Wikipedia | 467 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Commonly found on the market are mislabeled or counterfeit Secure Digital cards that report a fake capacity or run slower than labeled.
Software tools exist to check and detect counterfeit products,
and in some cases it is possible to repair these devices to remove the false capacity information and use its real storage limit.
Detection of counterfeit cards usually involves copying files with random data to the SD card until the card's capacity is reached, and copying them back. The files that were copied back can be tested either by comparing checksums (e.g. MD5), or trying to compress them. The latter approach leverages the fact that counterfeited cards let the user read back files, which then consist of easily compressible uniform data (for example, repeating 0xFFs).
Digital cameras
Secure Digital memory cards can be used in Sony XDCAM EX camcorders with an adapter.
Personal computers
Although many personal computers accommodate SD cards as an auxiliary storage device using a built-in slot, or can accommodate SD cards by means of a USB adapter, SD cards cannot be used as the primary hard disk through the onboard ATA controller, because none of the SD card variants support ATA signalling. Primary hard disk use requires a separate SD host controller or an SD-to-CompactFlash converter. However, on computers that support bootstrapping from a USB interface, an SD card in a USB adapter can be the boot disk, provided it contains an operating system that supports USB access once the bootstrap is complete.
In laptop and tablet computers, memory cards in an integrated memory card reader offer an ergonomical benefit over USB flash drives, as the latter sticks out of the device, and the user would need to be cautious not to bump it while transporting the device, which could damage the USB port. Memory cards have a unified shape and do not reserve a USB port when inserted into a computer's dedicated card slot.
Since late 2009, newer Apple computers with installed SD card readers have been able to boot in macOS from SD storage devices, when properly formatted to Mac OS Extended file format and the default partition table set to GUID Partition Table. | SD card | Wikipedia | 443 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
SD cards are increasing in usage and popularity among owners of vintage computers like Atari 8-bit computers. For example SIO2SD (SIO is an Atari port for connecting external devices) is used nowadays. Software for an 8-bit Atari may be included on one SD card that may have less than 4–8 GB of disk size (2019).
Embedded systems
In 2008, the SDA specified Embedded SD, "leverag[ing] well-known SD standards" to enable non-removable SD-style devices on printed circuit boards. However this standard was not adopted by the market while the MMC standard became the de facto standard for embedded systems. SanDisk provides such embedded memory components under the iNAND brand.
While some modern microcontrollers integrate SDIO hardware which uses the faster proprietary four-bit SD bus mode, almost all modern microcontrollers at least have SPI units that can interface to an SD card operating in the slower one-bit SPI bus mode. If not, SPI can also be emulated by bit banging (e.g. a SD card slot soldered to a Linksys WRT54G-TM router and wired to GPIO pins using DD-WRT's Linux kernel achieved only throughput).
Music distribution
Prerecorded microSDs have been used to commercialize music under the brands slotMusic and slotRadio by SanDisk and MQS by Astell & Kern.
Technical details
Physical size
The SD card specification defines three physical sizes. The SD and SDHC families are available in all three sizes, but the SDXC and SDUC families are not available in the mini size, and the SDIO family is not available in the micro size. Smaller cards are usable in larger slots through use of a passive adapter.
Standard
SD (SDSC), SDHC, SDXC, SDIO, SDUC
(as thin as MMC) for Thin SD (rare)
MiniSD
miniSD, miniSDHC, miniSDIO
microSD
The micro form factor is the smallest SD card format.
microSD, microSDHC, microSDXC, microSDUC
Transfer modes | SD card | Wikipedia | 445 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Cards may support various combinations of the following bus types and transfer modes. The SPI bus mode and one-bit SD bus mode are mandatory for all SD families, as explained in the next section. Once the host device and the SD card negotiate a bus interface mode, the usage of the numbered pins is the same for all card sizes.
SPI bus mode: Serial Peripheral Interface Bus is primarily used by embedded microcontrollers. This bus type supports only a 3.3-volt interface. This is the only bus type that does not require a host license.
One-bit SD bus mode: Separate command and data channels and a proprietary transfer format.
Four-bit SD bus mode: Uses extra pins plus some reassigned pins. This is the same protocol as the one-bit SD bus mode which uses one command and four data lines for faster data transfer. All SD cards support this mode. UHS-I and UHS-II require this bus type.
Two differential lines SD UHS-II mode: Uses two low-voltage differential signaling interfaces to transfer commands and data. UHS-II cards include this interface in addition to the SD bus modes.
The physical interface comprises 9 pins, except that the miniSD card adds two unconnected pins in the center and the microSD card omits one of the two VSS (Ground) pins. | SD card | Wikipedia | 275 | 315794 | https://en.wikipedia.org/wiki/SD%20card | Technology | Non-volatile memory | null |
Technology transfer (TT), also called transfer of technology (TOT), is the process of transferring (disseminating) technology from the person or organization that owns or holds it to another person or organization, in an attempt to transform inventions and scientific outcomes into new products and services that benefit society. Technology transfer is closely related to (and may arguably be considered a subset of) knowledge transfer.
A comprehensive definition of technology transfer today includes the notion of collaborative process as it became clear that global challenges could be resolved only through the development of global solutions. Knowledge and technology transfer plays a crucial role in connecting innovation stakeholders and moving inventions from creators to public and private users.
Intellectual property (IP) is an important instrument of technology transfer, as it establishes an environment conducive to sharing research results and technologies. Analysis in 2003 showed that the context, or environment, and motives of each organization involved will influence the method of technology transfer employed. The motives behind the technology transfer were not necessarily homogenous across organization levels, especially when commercial and government interests are combined. The protection of IP rights enables all parties, including universities and research institutions to ensure ownership of the scientific outcomes of their intellectual activity, and to control the use of IP in accordance with their mission and core values. IP protection gives academic institutions capacity to market their inventions, attract funding, seek industrial partners and assure dissemination of new technologies through means such as licensing or creation of start-ups for the benefit of society.
In practice
Technology transfers may occur between universities, businesses (of any size, ranging from small, medium, to large), governments, across geopolitical borders, both formally and informally, and both openly and secretly. Often it occurs by concerted effort to share skills, knowledge, technologies, manufacturing methods, samples, and facilities among the participants.
While the Technology Transfer process involves many activities, which can be represented in many ways, in reality, technology transfer is a fluid and dynamic process that rarely follows a linear course. Typical steps include:
Knowledge creation
Disclosure
Assessment and evaluation
IP protection
Fundraising and technology development
Marketing
Commercialization
Product development, and
Impact.
Technology transfer aims to ensure that scientific and technological developments are accessible to a wider range of users who can then further develop and exploit the technology into new products, processes, applications, materials, or services. It is closely related to (and may arguably be considered a subset of) knowledge transfer. Horizontal transfer is the movement of technologies from one area to another. | Technology transfer | Wikipedia | 497 | 315952 | https://en.wikipedia.org/wiki/Technology%20transfer | Technology | General | null |
Transfer of technology is primarily horizontal. Vertical transfer occurs when technologies are moved from applied research centers to research and development departments.
Spin-outs
Spin-outs are used where the host organization does not have the necessary will, resources, or skills to develop new technology. Often these approaches are associated with raising of venture capital (VC) as a means of funding the development process, a practice common in the United States and the European Union. Research spin-off companies are a popular vehicle of commercialization in Canada, where the rate of licensing of Canadian university research remains far below that of the US. Local venture capital organizations such as the Mid-Atlantic Venture Association (MAVA) also sponsor conferences at which investors assess the potential for commercialization of technology.
Technology brokers are people who discovered how to bridge the emergent worlds and apply scientific concepts or processes to new situations or circumstances. A related term, used almost synonymously, especially in Europe, is "technology valorisation". While conceptually the practice has been utilized for many years (in ancient times, Archimedes was notable for applying science to practical problems), the present-day volume of research, combined with high-profile failures at Xerox PARC and elsewhere, has led to a focus on the process itself.
Whereas technology transfer can involve the dissemination of highly complex technology from capital-intensive origins to low-capital recipients (and can involve aspects of dependency and fragility of systems), it also can involve appropriate technology, not necessarily high-tech or expensive, that is better disseminated, yielding robustness and independence of systems.
Informal promotion
Technology transfer is also promoted through informal means, such as at conferences organized by various groups, including the Ewing Marion Kauffman Foundation and the Association of University Technology Managers (AUTM), and at "challenge" competitions by organizations such as the Center for Advancing Innovation in Maryland. AUTM represents over 3,100 technology transfer professionals, and more than 800 universities, research centers, hospitals, businesses and government organizations.
The most frequently used informal means of technology transfer are through education, studies, professional exchange of opinions, movement of people, seminars, workshops. .
There are numerous professional associations and TTO Networks enhancing different forms of collaboration among technology managers in order to facilitate this "informal" transfer of best practices and experiences. | Technology transfer | Wikipedia | 469 | 315952 | https://en.wikipedia.org/wiki/Technology%20transfer | Technology | General | null |
In addition to AUTM, other regional and international associations include the Association of European Science and Technology Transfer Professionals (ASTP), the Alliance of Technology Transfer Professionals (ATTP), Licensing Executives Society (LES), Praxis Auril and others. There are also national Technology transfer associations and networks, such as the National Association of Technology Transfer Offices in Mexico (Red OTT Mexico), the Brazilian Forum of Innovation and Technology Transfer Managers (FORTEC), the Alliance of TechTransfer Professionals of the Philippines (AToP), the South African Research and Innovation Management Association (SARIMA), and other associations.
They promote cooperation in technology transfer and the exchange of best practices and experiences among professionals, as today international technology transfer is considered one of the most effective ways to bring people together to find solutions to global problems such as COVID-19, climate change or cyber-attacks.
IP policies
Universities and research institutions seeking to partner with industry or other organizations can adopt an institutional intellectual property policy for effective intellectual property management and technology transfer. Such policies provide structure, predictability, and a n environment, in which commercialization partners (industrial sponsors, consultants, non-profit organizations, SMEs, governments) and research stakeholders (researchers, technicians, students, visiting researchers, etc.) can access and share knowledge, technology and IP. National IP strategies are measures taken by a government to realize its IP policy objectives.
Organizations
A research result may be of scientific and commercial interest, but patents are normally only issued for practical processes, and so someone—not necessarily the researchers—must come up with a specific practical process. Another consideration is commercial value; for example, while there are many ways to accomplish nuclear fusion, the ones of commercial value are those that generate more energy than they require to operate. The process to commercially exploit research varies widely. It can involve licensing agreements or setting up joint ventures and partnerships to share both the risks and rewards of bringing new technologies to market. Other corporate vehicles, e.g. spin-outs, are used where the host organization does not have the necessary will, resources, or skills to develop new technology. Often these approaches are associated with raising of venture capital (VC) as a means of funding the development process. Research spin-off companies are a popular vehicle of commercialization in Canada, where the rate of licensing of Canadian university research remains far below that of the US. | Technology transfer | Wikipedia | 485 | 315952 | https://en.wikipedia.org/wiki/Technology%20transfer | Technology | General | null |
Scholars Jeffrey Stoff and Alex Joske have argued that the Chinese Communist Party's united front "influence apparatus intersects with or directly supports its global technology transfer apparatus."
Technology transfer offices
Many universities and research institutions, and governmental organizations now have an Office of Technology Transfer (TTO, also known as "Tech Transfer" or "TechXfer") dedicated to identifying research that has potential commercial interest and strategies for how to exploit it. Technology Transfer Offices are usually created within a university in order to manage IP assets of the university, and the transfer of knowledge and technology to industry. Sometimes, their mandate includes any interaction or contractual relation with the private sector, or other responsibilities, depending on the mission of the institutions. Common names for such offices differ. Some examples include Technology Licensing Office (TLO), Technology Management Office, Research Contracts and IP Services Office, Technology Transfer Interface, Industry Liaisons Office, IP and Technology Management Office, and Nucleus of Technological Innovation.
Technology transfer offices may work on behalf of research institutions, governments, and even large multinationals. Where start-ups and spin-outs are the clients, commercial fees are sometimes waived in lieu of an equity stake in the business. As a result of the potential complexity of the technology transfer process, technology transfer organizations are often multidisciplinary, including economists, engineers, lawyers, marketers and scientists. The dynamics of the technology transfer process have attracted attention in their own right, and there are several dedicated societies and journals.
Technology and Innovation Support Centers
Technology and Innovation Support Centers (TISCs) help innovators access patent information, scientific and technical literature and search tools and databases and make more effective use of these resources to promote innovation, technology transfer, commercialization and utilization of technologies. The WIPO TISCs program currently supports over 80 countries. WIPO supports its member states in establishing and developing TISCs in universities and other institutions in numerous countries around the world. Services offered by TISCs may include:
access to online patent and non-patent (scientific and technical) resources and IP-related publications;
assistance in searching and retrieving technology information;
training in database search;
on-demand searches (novelty, state-of-the-art and infringement);
monitoring technology and competitors;
basic information on industrial property laws, management and strategy, and technology commercialization and marketing. | Technology transfer | Wikipedia | 473 | 315952 | https://en.wikipedia.org/wiki/Technology%20transfer | Technology | General | null |
Science technology parks
Science and technology parks (STP) are territories usually affiliated with a university or a research institution, which accommodate and foster the growth of companies based therein through technology transfer and open innovation.
Technology incubators
Technology business incubators (TBIs) are organizations that help startup companies and individual entrepreneurs develop their businesses by providing a range of services, including training, brokering and financing.
IP marketplaces
Intellectual Property marketplaces are Internet-based platforms that allow innovators to connect with potential partners and/or clients. For example, online platform WIPO GREEN enable collaborations in specific areas of knowledge transfer and facilitate matchmaking between technology providers and technology seekers.
Government and intellectual property support
There has been a marked increase in technology transfer intermediaries specialized in their field since 1980, stimulated in large part by the Bayh–Dole Act and equivalent legislation in other countries, which provided additional incentives for research exploitation. Due to the increasing focus on technology transfer there are several forms of intermediary institutions at work in this sector, from TTOs to IP 'trolls' that act outside the Bayh–Dole Act provisions. Due to the risk of exploitation, intellectual property policy, training and systems support for technology transfer by government, research institutes and universities, have been international and regionally-focused organisation, such as the World Intellectual Property Organisation and the European Union.
Partnership intermediaries
The U.S. government's annual budget funds over $100 billion in research and development activity, which leads to a continuous pipeline of new inventions and technologies from within government laboratories. Through legislation including the Bayh–Dole Act, Congress encourages the private sector to use those technologies with commercial potential through technology transfer mechanisms such as Cooperative Research and Development Agreements, Patent License Agreements, Educational Partnership Agreements, and state/local government partnerships. | Technology transfer | Wikipedia | 368 | 315952 | https://en.wikipedia.org/wiki/Technology%20transfer | Technology | General | null |
The term "partnership intermediary" means an agency of a state or local government—or a nonprofit entity owned, chartered, funded, or operated by or on behalf of a state or local government—that assists, counsels, advises, evaluates, or otherwise cooperates with small business firms; institutions of higher education defined in section 201(a) of the Higher Education Act of 1965 (20 USC § 1141 [a]); or educational institutions within the meaning of section 2194 of Title 10, United States Code, that need or can make demonstrably productive use of technology-related assistance from a federal laboratory, including state programs receiving funds under cooperative agreements entered into under section 5121 of the Omnibus Trade and Competitiveness Act of 1988 (15 USC § 2781).
During COVID-19 pandemic
Technology transfer had a direct impact on contributing to global public health issues, by enabling global access to COVID-19 vaccines. During 2021, vaccine developers concluded over 200 technology transfer agreements. One example was AstraZeneca concluding the licensing and technology transfer agreements on AstraZeneca with the Serum Institute of India and with Daiichi Sankyo of Japan to supply vaccines for COVID-19, which were developed in collaboration with the University of Oxford. In this process Intellectual Property was part of the solution and an important tool for facilitation of affordable global access to COVID 19 treatments – as it was the case in two licensing agreements between Medicines Patent Pool (MPP) and pharmaceutical companies Merck and Pfizer.
Drawbacks
Despite incentives to move research into production, the practical aspects are sometimes difficult to perform in practice. Using DoD technology readiness levels as a criterion (for example), research tends to focus on TRL (technology readiness level) 1–3 while readiness for production tends to focus on TRL 6–7 or higher. Bridging TRL-3 to TRL-6 has proven to be difficult in some organizations. Attempting to rush research (prototypes) into production (fully tested under diverse conditions, reliable, maintainable, etc.) tends to be more costly and time-consuming than expected.
Power political and realpolitik incentives in technology transfer are cognized to be negative factors in destructive applications. Technology transfer to dictatorial regimes is thought to be disruptive for the scientific purposes. | Technology transfer | Wikipedia | 476 | 315952 | https://en.wikipedia.org/wiki/Technology%20transfer | Technology | General | null |
Private transport (as opposed to public transport) is the personal or individual use of transportation which are not available for use by the general public, where in theory the user can decide freely on the time and route of transit ('choice rider' vs. 'captive rider'), using vehicles such as: private car, company car, bicycle, dicycle, self-balancing scooter, motorcycle, scooter, aircraft, boat, snowmobile, carriage, horse, etc., or recreational equipment such as roller skates, inline skates, sailboat, sailplane, skateboard etc.
Definition
Private transport is in contrast to public transport, and commercial non-public transport. While private transportation may be used alongside nearly all modes of public transportation, private railroad cars are rare (e.g. royal train), although heritage railways are not. Unlike many forms of public transportation, which may be government subsidized or operated by privately owned commercial organizations for mass or general public use, the entire cost of private transportation is born directly or indirectly by the individual user(s). However some scholars argue that it is inaccurate to say that the costs are covered by individual user because big (and often dominant) part of cost of private transportation is the cost of infrastructure on which individual trips rely. They therefore work also with model of quasi-private mobility.
Personal transport
Private transportation includes both non-motorized methods of private transit (pedestrians, cyclists, skaters, etc.) and all forms of self-propelled transport vehicles.
Shared personal transport
Non-public passenger transport in vehicles owned by the driver or passenger or operated by the driver.
Commercial transport
Shared vehicle fleets without driver
Self driven transport in vehicles not owned by either the passengers or driver.
Shared vehicle fleets with driver
Non-scheduled transit vehicles, taxicabs and rickshaws, which are rented or hired in the short-term on-demand with driver, belong, even if the user can freely decide on the time and route of transit, to the special forms of 'public transport'.
Shared individual vehicle journeys
Means of transport are fixed route and fixed schedule passenger services, for example, excursion riverboats, tourist cable cars, resort ski lifts.
Usage
Private transport is the dominant form of transportation in most of the world. In the United States, for example, 86.2% of passenger miles are by passenger vehicles, motorcycles, and trucks.
Examples of private transport | Private transport | Wikipedia | 488 | 315973 | https://en.wikipedia.org/wiki/Private%20transport | Technology | Basics_7 | null |
Motorized:
Automobile
Motorboat
Electric bicycle
Electric skateboard
Hovercraft
Moped
Motorcycle
Motorized wheelchair
Private aviation
Private jet
Motor ship
Submarine
Electric scooter
Electric unicycle
Mobility scooter
SUV
Pick-up truck
Limousine
Non-motorized:
Bicycle
Horse-drawn vehicle
Hot air balloon
Ice skates
Inline skates
Pack animal
Roller skates
Scooter
Skateboard
Walking
Wheelchair
Sustainability
Cycling and walking, above all, have been recognized as the most sustainable transport systems. In general, all muscle-driven mobility will have a similar energy efficiency while at the same time being almost emission-free (apart from the exhaled during breathing).
The negative environmental impact of private transport can be alleviated by choosing the optimal modal share for a given environment and transport requirements.
Dedicated infrastructure
Automobile repair shop
Controlled-access highway
Diner
Drive-thru
Drive-in theater
Filling station
Garage (residential)
Motel
Parking lot
Rest area
Retail park
Roadside zoo
Safari park
Roads
Racetrack (Cars)
Car Dealership
Tollbooth
Park and ride | Private transport | Wikipedia | 200 | 315973 | https://en.wikipedia.org/wiki/Private%20transport | Technology | Basics_7 | null |
Dalbergia is a large genus of small to medium-size trees, shrubs and lianas in the pea family, Fabaceae, subfamily Faboideae. It was recently assigned to the informal monophyletic Dalbergia clade (or tribe): the Dalbergieae. The genus has a wide distribution, native to the tropical regions of Central and South America, Africa, Madagascar and Southern Asia.
Fossil record
A fossil †Dalbergia phleboptera seed pod has been found in a Chattian deposit, in the municipality of Aix-en-Provence in France. Fossils of †Dalbergia nostratum have been found in rhyodacite tuff of Lower Miocene age in Southern Slovakia near the town of Lučenec. Fossil seed pods of †Dalbergia mecsekense have been found in a Sarmatian deposit in Hungary. †Dalbergia lucida fossils have been described from the Xiaolongtan Formation of late Miocene age in Kaiyuan County, Yunnan Province, China.
Uses
Many species of Dalbergia are important timber trees, valued for their decorative and often fragrant wood, rich in aromatic oils. The most famous of these are the rosewoods, so-named because of the smell of the timber when cut, but several other valuable woods are yielded by the genus.
Species such as Dalbergia nigra known as Rio, Bahia, Brazilian rosewood, palisander de Rio Grande, or jacaranda and Dalbergia latifolia known as (East) Indian Rosewood or Sonokeling have been heavily used in furniture given their colour and grain. Several East Asian species are important materials in traditional Chinese furniture.
The (Brazilian) tulipwood (D. decipularis) is cream coloured with red or salmon stripes. It is most often used in crossbanding and other veneers; it should not be confused with the "tulipwood" of the American tulip tree Liriodendron tulipifera, used in inexpensive cabinetwork.
The similarly used (but purple with darker stripes), and also Brazilian, kingwood is yielded by D. cearensis. Both are smallish to medium-sized trees, to 10 m. Another notable timber is cocobolo, mainly from D. retusa, a Central American timber with spectacular decorative orange red figure on freshly cut surfaces which slowly fades in air to more subdued tones and hues. | Dalbergia | Wikipedia | 495 | 316052 | https://en.wikipedia.org/wiki/Dalbergia | Biology and health sciences | Fabales | Plants |
Dalbergia sissoo (Indian rosewood) is primarily used for furniture in northern India. Its export is highly regulated due to recent high rates of tree death due to unknown causes. Dalbergia sissoo has historically been the primary rosewood species of northern India. This wood is strong and tough, with color golden to dark brown. It is extremely durable and handsome, and it maintains its shape well. It can be easily seasoned. It is difficult to work, but it takes a fine polish. It is used for high quality furniture, plywoods, bridge piles, sporting goods, and railway sleepers. It is a very good material for decorative work and carvings. Its density is 770 kg/m3.
African blackwood (D. melanoxylon) is an intensely black wood in demand for making woodwind musical instruments.
Dalbergia species are used as food plants by the larvae of some Lepidoptera species including Bucculatrix mendax which feeds exclusively on Dalbergia sissoo.
The Dalbergia species are notorious for causing allergic reactions due to the presence of sensitizing quinones in the wood.
Conservation
All Dalbergia species are protected under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). All but Dalbergia nigra are listed in Appendix II, with D.nigra listed in Appendix I.
Species
Dalbergia comprises the following species:
Dalbergia abbreviata Craib
Dalbergia abrahamii Bosser & R. Rabev.
Dalbergia acariiantha Harms
Dalbergia acuta Benth.
Dalbergia acutifoliolata Mendonca & Sousa
Dalbergia adami Berhaut
Dalbergia afzeliana G. Don
Dalbergia ajudana Harms
Dalbergia albertisii Prain
Dalbergia albiflora Hutch. & Dalziel
subsp. albiflora Hutch. & Dalziel
subsp. echinocarpa Hepper
Dalbergia altissima Baker f.
Dalbergia altissima Pittier
Dalbergia amazonica (Radlk.) Ducke
Dalbergia andapensis Bosser & R. Rabev.
Dalbergia antsirananae Phillipson, Crameri & N.Wilding
Dalbergia arbutifolia Baker
Dalbergia armata E. Mey. — Hluhluwe creeper
Dalbergia assamica Benth. | Dalbergia | Wikipedia | 511 | 316052 | https://en.wikipedia.org/wiki/Dalbergia | Biology and health sciences | Fabales | Plants |
Dalbergia aurea Bosser & R. Rabev.
Dalbergia bakeri Baker
Dalbergia balansae Prain
Dalbergia baronii Baker — Madagascar rosewood, Palisander rosewood, Palissandre voamboana
Dalbergia bathiei R. Vig.
Dalbergia beccarii Prain
Dalbergia beddomei Thoth.
Dalbergia benthamii Prain
Dalbergia bignonae Berhaut
Dalbergia bintuluensis Sunarno & Ohashi
Dalbergia boehmii Taub.
Dalbergia bojeri Drake
Dalbergia boniana Gagnep.
Dalbergia borneensis Prain
Dalbergia brachystachya Bosser & R. Rabev.
Dalbergia bracteolata Baker
Dalbergia brasiliensis Vogel
Dalbergia brownei (Jacq.) Urb. — Coin vine
Dalbergia burmanica Prain
Dalbergia calderonii Standl.
subsp. calderonii Standl.
subsp. molinae Rudd
Dalbergia calycina Benth.
Dalbergia campenonii Drake
Dalbergia cana Kurz
Dalbergia candenatensis (Dennst.) Prain
Dalbergia canescens (Elmer) Merr.
Dalbergia capuronii Bosser & R. Rabev.
Dalbergia carringtoniana Sousa
Dalbergia catingicola Harms
Dalbergia caudata G. Don
Dalbergia cearensis Ducke — Kingwood
Dalbergia chapelieri Baill.
Dalbergia chlorocarpa R. Vig.
Dalbergia chontalensis Standl. & L.O. Williams
Dalbergia clarkei Thoth.
Dalbergia cochinchinensis Pierre ex Laness. — Siamese rosewood, Thailand rosewood, Tracwood (synonym Dalbergia cambodiana Pierre)
Dalbergia commiphoroides Baker f.
Dalbergia confertiflora Benth.
Dalbergia congensis Baker f.
Dalbergia congesta Wight & Arn.
Dalbergia congestiflora Pittier
Dalbergia coromandeliana Prain
Dalbergia crispa Hepper
Dalbergia cubilquitzensis (Donn. Sm.) Pittier
Dalbergia cucullata Pittier
Dalbergia cuiabensis Benth. | Dalbergia | Wikipedia | 499 | 316052 | https://en.wikipedia.org/wiki/Dalbergia | Biology and health sciences | Fabales | Plants |
Dalbergia cultrata Benth.
Dalbergia cumingiana Benth.
Dalbergia curtisii Prain
Dalbergia cuscatlanica (Standl.) Standl.
Dalbergia dalzielii Hutch. & Dalziel
Dalbergia darienensis Rudd
Dalbergia davidii Bosser & R. Rabev.
Dalbergia debilis J.F. Macbr.
Dalbergia decipularis Rizzini & A. Mattos — Tulipwood
Dalbergia delphinensis Bosser & R. Rabev.
Dalbergia densa Benth.
Dalbergia densiflora (Benth.) Benth.
Dalbergia discolor Blume
Dalbergia duarensis Thoth.
Dalbergia dyeriana Harms
Dalbergia ealaensis De Wild.
Dalbergia ecastaphyllum (L.) Taub. — Coin vine
Dalbergia elegans A.M. Carvalho
Dalbergia emirnensis Benth.
Dalbergia enneaphylla Pittier
Dalbergia entadoides Prain
Dalbergia eremicola Polhill
Dalbergia ernest-ulei Hoehne
Dalbergia errans Craib
Dalbergia erubescens Bosser & R. Rabev.
Dalbergia falcata Prain
Dalbergia fischeri Taub.
Dalbergia floribunda Craib
Dalbergia florifera De Wild.
Dalbergia foliolosa Benth.
Dalbergia foliosa (Benth.) A.M. Carvalho
Dalbergia forbesii Prain
Dalbergia fouilloyana Pellegr.
Dalbergia frutescens (Vell.) Britton — Brazilian tulipwood, Jacarandá rosa, Pau de fuso, Pau rosa, Pinkwood, Tulipwood
Dalbergia funera Standl.
Dalbergia fusca Pierre
Dalbergia gardneriana Benth.
Dalbergia gentilii De Wild.
Dalbergia gilbertii Cronquist
Dalbergia glaberrima Bosser & R. Rabev.
Dalbergia glabra (Mill.) Standl.
Dalbergia glandulosa Benth. | Dalbergia | Wikipedia | 473 | 316052 | https://en.wikipedia.org/wiki/Dalbergia | Biology and health sciences | Fabales | Plants |
Dalbergia glaucescens (Benth.) Benth.
Dalbergia glaucocarpa Bosser & R. Rabev.
Dalbergia glaziovii Harms
Dalbergia glomerata Hemsl.
Dalbergia godefroyi Prain
Dalbergia gossweileri Baker f.
Dalbergia gracilis Benth.
Dalbergia granadillo Pittier
Dalbergia grandibracteata De Wild.
Dalbergia grandistipula A.M. Carvalho
Dalbergia greveana Baill.
Dalbergia guttembergii A.M. Carvalho
Dalbergia hainanensis Merr. & Chun
Dalbergia hancei Benth.
Dalbergia havilandii Prain
Dalbergia henryana Prain
Dalbergia heudelotii Stapf
Dalbergia hiemalis Malme
Dalbergia hildebrandtii Vatke
Dalbergia hirticalyx Bosser & R. Rabev.
Dalbergia horrida (Dennst.) Mabb.
Dalbergia hortensis Heringer & al.
Dalbergia hoseana Prain
Dalbergia hostilis Benth.
Dalbergia hullettii Prain
Dalbergia humbertii R. Vig.
Dalbergia hupeana Hance
Dalbergia hygrophila (Benth.) Hoehne
Dalbergia intermedia A.M. Carvalho
Dalbergia intibucana Standl. & L.O. Williams
Dalbergia inundata Benth.
Dalbergia iquitosensis Harms
Dalbergia jaherii Burck
Dalbergia junghuhnii Benth.
Dalbergia kerrii Craib
Dalbergia kingiana Prain
Dalbergia kisantuensis De Wild. & T. Durand
Dalbergia kostermansii Sunarno & Ohashi
Dalbergia kunstleri Prain
Dalbergia kurzii Prain
Dalbergia lacei Thoth.
Dalbergia lactea Vatke | Dalbergia | Wikipedia | 440 | 316052 | https://en.wikipedia.org/wiki/Dalbergia | Biology and health sciences | Fabales | Plants |
Dalbergia lakhonensis Gagnep.
Dalbergia lanceolaria L. f. – Viet. vảy ốc, bạt ong, trắc múi giáo, Burmese: သစ်ပုပ်, Malayalam: വെള്ളീട്ടി
Dalbergia lastoursvillensis Pellegr.
Dalbergia lateriflora Benth.
Dalbergia latifolia Roxb. — Bombay blackwood, East Indian rosewood, Indian palisandre, Indian rosewood, Irugudujava, Java palisandre, Malabar, Sonokeling, Shisham, Sitsal, Satisal
Dalbergia laxiflora Micheli
Dalbergia lemurica Bosser & R. Rabev.
Dalbergia librevillensis Pellegr.
Dalbergia louisii Cronquist
Dalbergia louvelii R. Vig. — violet rosewood
Dalbergia macrosperma Baker
Dalbergia madagascariensis Vatke
Dalbergia malabarica Prain
Dalbergia malangensis Sousa
Dalbergia marcaniana Craib
Dalbergia maritima R. Vig.
Dalbergia martinii F. White
Dalbergia mayumbensis Baker f.
Dalbergia melanocardium Pittier
Dalbergia melanoxylon Guill. & Perr. — African blackwood, African ebony, African grenadilo, Banbanus, Ebene, Granadilla, Granadille d'Afrique, Mpingo, Pau preto, Poyi, Zebrawood
Dalbergia menoeides Prain
Dalbergia mexicana Pittier
Dalbergia microphylla Chiov.
Dalbergia millettii Benth.
Dalbergia mimosella (Blanco) Prain
Dalbergia mimosoides Franch.
Dalbergia miscolobium Benth.
Dalbergia mollis Bosser & R. Rabev.
Dalbergia monetaria L. f. — Moneybush
Dalbergia monophylla G.A. Black
Dalbergia monticola Bosser & R. Rabev.
Dalbergia multijuga E. Mey.
Dalbergia negrensis (Radlk.) Ducke
Dalbergia neoperrieri Bosser & R. Rabev. | Dalbergia | Wikipedia | 471 | 316052 | https://en.wikipedia.org/wiki/Dalbergia | Biology and health sciences | Fabales | Plants |
Dalbergia ngounyensis Pellegr.
Dalbergia nigra (Vell.) Benth. — Bahia rosewood, Brazilian rosewood, Cabiuna, Caviuna, Jacarandá, Jacarandá de Brasil, Palisander, Palisandre da Brésil, Pianowood, Rio rosewood, Rosewood, Obuina
Dalbergia nigrescens Kurz
Dalbergia nitida (Benth.) Hoehne
Dalbergia nitidula Baker
Dalbergia noldeae Harms
Dalbergia normandii Bosser & R. Rabev.
Dalbergia obcordata N.Wilding, Phillipson & Crameri
Dalbergia obovata E. Mey. — Climbing flat bean
Dalbergia obtusifolia (Baker) Prain
Dalbergia odorifera T.C. Chen — Fragrant rosewood
Dalbergia oligophylla Hutch. & Dalziel
Dalbergia oliveri Prain (synonyms: Dalbergia bariensis Pierre, Dalbergia dongnaiensis Pierre, D. duperreana Pierre & Dalbergia mammosa Pierre)
Dalbergia orientalis Bosser & R. Rabev.
Dalbergia ovata Benth.
Dalbergia pachycarpa (De Wild. & T. Durand) De Wild.
Dalbergia palo-escrito Rzed. — Palo escrito
Dalbergia parviflora Roxb.
Dalbergia paucifoliolata Lundell
Dalbergia peguensis Thoth.
Dalbergia peishaensis Chun & T. Chen
Dalbergia peltieri Bosser & R. Rabev.
Dalbergia pervillei Vatke
Dalbergia pierreana Prain
Dalbergia pinnata (Lour.) Prain
Dalbergia pluriflora Baker f.
Dalbergia polyadelpha Prain
Dalbergia polyphylla Benth.
Dalbergia prainii Thoth.
Dalbergia pseudo-ovata Thoth.
Dalbergia pseudo-sissoo Miq.
Dalbergia pseudobaronii R. Vig.
Dalbergia purpurascens Baill. | Dalbergia | Wikipedia | 467 | 316052 | https://en.wikipedia.org/wiki/Dalbergia | Biology and health sciences | Fabales | Plants |
Dalbergia reniformis Roxb.
Dalbergia reticulata Merr.
Dalbergia retusa Hemsl. — Caviuna, Cocobolo, Cocobolo prieto, Funeram, Granadillo, Jacarandáholz, Nambar, Nicaraguan rosewood, Palisander, Palissandro, Palo negro, Pau preto, Rosewood, Urauna
Dalbergia revoluta Ducke
Dalbergia richardsii Sunarno & Ohashi
Dalbergia riedelii (Benth.) Sandwith
Dalbergia rimosa Roxb.
Dalbergia riparia (Mart.) Benth.
Dalbergia rostrata Hassk.
Dalbergia rubiginosa Roxb.
Dalbergia rufa G. Don
Dalbergia rugosa Hepper
Dalbergia sacerdotum Prain
Dalbergia sambesiaca Schinz
Dalbergia sampaioana Kuhlm. & Hoehne
Dalbergia sandakanensis Sunarno & Ohashi
Dalbergia saxatilis Hook. f.
Dalbergia scortechinii (Prain) Prain
Dalbergia sericea G. Don
Dalbergia setifera Hutch. & Dalziel
Dalbergia simpsonii Rudd
Dalbergia sissoides Wight & Arn.
Dalbergia sissoo DC. — Agara, Agaru, Errasissu, Gette, Hihu, Indian rosewood, Irugudujava, Iruvil, Iti, Khujrap, Padimi, Safedar, Sheesham, Shinshapa, Shisham, Shishma, Shishom, Sinsupa, Sissoo, Sisu, Tali, Tenach, Tukreekung, Yette
Dalbergia spinosa Roxb.
Dalbergia spruceana (Benth.) Benth. — Amazon rosewood
Dalbergia stenophylla Prain
Dalbergia stercoracea Prain
Dalbergia stevensonii Standl. — Honduras rosewood, Nagaed
Dalbergia stipulacea Roxb.
Dalbergia suaresensis Baill.
Dalbergia subcymosa Ducke
Dalbergia succirubra Gagnep. & Craib
Dalbergia teijsmannii Sunarno & Ohashi
Dalbergia teixeirae Sousa | Dalbergia | Wikipedia | 504 | 316052 | https://en.wikipedia.org/wiki/Dalbergia | Biology and health sciences | Fabales | Plants |
Dalbergia thomsonii Benth.
Dalbergia thorelii Gagnep.
Dalbergia tilarana N. Zamora
Dalbergia tinnevelliensis Thoth.
Dalbergia tonkinensis Prain
Dalbergia travancorica Thoth.
Dalbergia trichocarpa Baker
Dalbergia tricolor Drake
Dalbergia tsaratananensis Bosser & R. Rabev.
Dalbergia tsiandalana R. Vig.
Dalbergia tsoi Merr. & Chun
Dalbergia tucurensis Donn. Sm. — Guatemalan rosewood
Dalbergia uarandensis (Chiov.) Thulin
Dalbergia urschii Bosser & R. Rabev.
Dalbergia vacciniifolia Vatke
Dalbergia velutina Benth.
Dalbergia verrucosa Craib
Dalbergia viguieri Bosser & R. Rabev.
Dalbergia villosa (Benth.) Benth.
Dalbergia volubilis Roxb.
Dalbergia wattii C.B. Clarke
Dalbergia xerophila Bosser & R. Rabev.
Dalbergia yunnanensis Franch. | Dalbergia | Wikipedia | 253 | 316052 | https://en.wikipedia.org/wiki/Dalbergia | Biology and health sciences | Fabales | Plants |
A sluice ( ) is a water channel containing a sluice gate, a type of lock to manage the water flow and water level. It can also be an open channel which processes material, such as a river sluice used in gold prospecting or fossicking. A mill race, leet, flume, penstock or lade is a sluice channeling water toward a water mill. The terms sluice, sluice gate, knife gate, and slide gate are used interchangeably in the water and wastewater control industry.
Operation
"Sluice gate" refers to a movable gate allowing water to flow under it. When a sluice is lowered, water may spill over the top, in which case the gate operates as a weir. Usually, a mechanism drives the sluice up or down. This may be a simple, hand-operated, chain pulled/lowered, worm drive or rack-and-pinion drive, or it may be electrically or hydraulically powered. A flap sluice, however, operates automatically, without external intervention or inputs.
Types of sluice gates | Sluice | Wikipedia | 233 | 316061 | https://en.wikipedia.org/wiki/Sluice | Technology | Hydraulic infrastructure | null |
Flap sluice gate A fully automatic type, controlled by the pressure head across it; operation is similar to that of a check valve. It is a gate hinged at the top. When pressure is from one side, the gate is kept closed; a pressure from the other side opens the sluice when a threshold pressure is surpassed.
Vertical rising sluice gate A plate sliding in the vertical direction, which may be controlled by machinery.
Radial sluice gate A structure, where a small part of a cylindrical surface serves as the gate, supported by radial constructions going through the cylinder's radius. On occasion, a counterweight is provided.
Rising sector sluice gate Also a part of a cylindrical surface, which rests at the bottom of the channel and rises by rotating around its centre.
Needle sluice A sluice formed by a number of thin needles held against a solid frame through water pressure as in a needle dam.
Fan gate () This type of gate was invented by the Dutch hydraulic engineer in 1808. He was Inspector-General for Waterstaat (Water resource management) of the Kingdom of Holland at the time. The Fan door has the special property that it can open in the direction of high water solely using water pressure. This gate type was primarily used to purposely inundate certain regions, for instance in the case of the Hollandic Water Line. Nowadays this type of gate can still be found in a few places, for example in Gouda. A fan gate has a separate chamber that can be filled with water and is separated on the high-water-level side of the sluice by a large door. When a tube connecting the separate chamber with the high-water-level side of the sluice is opened, the water level, and with that the water pressure in this chamber, will rise to the same level as that on the high-water-level side. As there is no height difference across the larger gate, it exerts no force. However the smaller gate has a higher level on the upstream side, which exerts a force to close the gate. When the tube to the low water side is opened the water level in the chamber will fall. Due to the difference in the surface areas of the doors there will be a net force opening the gate. | Sluice | Wikipedia | 470 | 316061 | https://en.wikipedia.org/wiki/Sluice | Technology | Hydraulic infrastructure | null |
Designing the sluice gate
Sluice gates are one of the most common hydraulic structures used to control or measure the flow in open channels. Vertical rising sluice gates are the most common in open channels and can operate under two flow regimes: free flow and submerged flow. The most important depths in designing of sluice gates are:
: upstream depth
: opening of the sluice gate
: the minimum depth of flow after the sluice gate
: the initial depth of the hydraulic jump
: the secondary depth of the hydraulic jump
: downstream depth
Logging sluices
In the mountains of the United States, sluices transported logs from steep hillsides to downslope sawmill ponds or yarding areas. Nineteenth-century logging was traditionally a winter activity for men who spent summers working on farms. Where there were freezing nights, water might be applied to logging sluices every night so a fresh coating of slippery ice would reduce friction of logs placed in the sluice the following morning.
Placer mining applications
Sluice boxes are often used in the recovery of black sands, gold, and other minerals from placer deposits during placer mining operations. They may be small-scale, as used in prospecting, or much larger, as in commercial operations, where the material is sometimes screened using a trommel, screening plant or sieve. Traditional sluices have transverse riffles over a carpet or rubber matting, which trap the heavy minerals, gemstones, and other valuable minerals. Since the early 2000s more miners and prospectors are relying on more modern and effective matting systems. The result is a concentrate which requires additional processing.
Types of material
Aluminium Most sluices are formed with aluminium using a press brake to form a U shape
Wood Traditionally wood was the material of choice for sluice gates.
Cast iron Cast iron has been popular when constructing sluice gates for years. This material is great at keeping the strength needed when dealing with powerful water levels.
Stainless steel In most cases, stainless steel is lighter than the older cast iron material.
Fibre-reinforced plastic (FRP) In modern times, newer materials such as fibre-reinforced plastic are being used to build sluices. These modern technologies have many of the attributes of the older materials, while introducing advantages such as corrosion resistance and much lighter weights.
Regional names for sluice gates
In the Somerset Levels, sluice gates are known as clyse or clyce.
Most of the inhabitants of Guyana refer to sluices as kokers. | Sluice | Wikipedia | 511 | 316061 | https://en.wikipedia.org/wiki/Sluice | Technology | Hydraulic infrastructure | null |
The Sinhala people in Sri Lanka, who had an ancient civilization based on harvested rain water, refer to sluices as Horovuwa.
Gallery | Sluice | Wikipedia | 31 | 316061 | https://en.wikipedia.org/wiki/Sluice | Technology | Hydraulic infrastructure | null |
The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae or golden algae, are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer to a single species, Prymnesium parvum, which causes fish kills.
The Chrysophyceae should not be confused with the Chrysophyta, which is a more ambiguous taxon. Although "chrysophytes" is the anglicization of "Chrysophyta", it generally refers to the Chrysophyceae.
Members
Originally they were taken to include all such forms of the diatoms and multicellular brown algae, but since then they have been divided into several different groups (e.g., Haptophyceae, Synurophyceae) based on pigmentation and cell structure. Some heterotrophic flagellates as the bicosoecids and choanoflagellates were sometimes seen as related to golden algae too.
They are now usually restricted to a core group of closely related forms, distinguished primarily by the structure of the flagella in motile cells, also treated as an order Chromulinales. It is possible membership will be revised further as more species are studied in detail.
The Chrysophyceae have been placed by some in the polyphyletic Chromista. The broader monophyletic group to which the Chrysophyceae belong includes various non-algae including the bicosoecids, not the collar flagellates, opalines, oomycete fungi, proteromonads, actinophryid heliozoa, and other heterotrophic flagellates and is referred to as the Stramenopiles.
Description
The "primary" cell of chrysophytes contains two specialized flagella. The active, "feathered" (with mastigonemes) flagellum is oriented toward the moving direction. The smooth passive flagellum, oriented toward the opposite direction, may be present only in rudimentary form in some species. | Golden algae | Wikipedia | 440 | 316083 | https://en.wikipedia.org/wiki/Golden%20algae | Biology and health sciences | SAR supergroup | Plants |
An important characteristic used to identify members of the class Chrysophyceae is the presence of a siliceous cyst that is formed endogenously. Called statospore, stomatocyst or statocyst, this structure is usually globose and contains a single pore. The surface of mature cysts may be ornamented with different structural elements and are useful to distinguish species. | Golden algae | Wikipedia | 84 | 316083 | https://en.wikipedia.org/wiki/Golden%20algae | Biology and health sciences | SAR supergroup | Plants |
Most members are unicellular flagellates, with either two visible flagella, as in Ochromonas, or sometimes one, as in Chromulina. The Chromulinales as first defined by Pascher in 1910 included only the latter type, with the former treated as the order Ochromonadales. However, structural studies have revealed that a short second flagellum, or at least a second basal body, is always present, so this is no longer considered a valid distinction. Most of these have no cell covering. Some have loricae or shells, such as Dinobryon, which grows in branched colonies. Most forms with silicaceous scales are now considered a separate group, the synurids, but a few belong among the Chromulinales proper, such as Paraphysomonas.
Some members are generally amoeboid, with long branching cell extensions, though they pass through flagellate stages as well. Chrysamoeba and Rhizochrysis are typical of these. There is also one species, Myxochrysis paradoxa, which has a complex life cycle involving a multinucleate plasmodial stage, similar to those found in slime molds. These were originally treated as the order Chrysamoebales. The superficially similar Rhizochromulina was once included here, but is now given its own order based on differences in the structure of the flagellate stage.
Other members are non-motile. Cells may be naked and embedded in mucilage, such as Chrysosaccus, or coccoid and surrounded by a cell wall, as in Chrysosphaera. A few are filamentous or even parenchymatous in organization, such as Phaeoplaca. These were included in various older orders, most of the members of which are now included in separate groups. Hydrurus and its allies, freshwater genera which form branched gelatinous filaments, are often placed in the separate order Hydrurales, but may belong here.
Classifications
Pascher (1914)
Classification of the class Chrysophyceae according to Pascher (1914):
Division Chrysophyta
Class Chrysophyceae
Order Chrysomonadales
Order Chrysocapsales
Order Chrysosphaerales
Order Chrysotrichales
Class Heterokontae
Class Diatomeae | Golden algae | Wikipedia | 506 | 316083 | https://en.wikipedia.org/wiki/Golden%20algae | Biology and health sciences | SAR supergroup | Plants |
Smith (1938)
According to Smith (1938):
Class Chrysophyceae
Order Chrysomonadales
Suborder Cromulinae (e.g., Mallomonas)
Suborder Isochrysidineae (e.g., Synura)
Suborder Ochromonadineae (e.g., Dinobryon)
Order Rhizochrysidales (e.g., Chrysamoeba)
Order Chrysocapsales (e.g., Hydrurus)
Order Chrysotrichales (e.g., Phaeothamnion)
Order Chrysosphaerales (e.g., Epichrysis)
Bourrely (1957)
According to Bourrely (1957):
Class Chrysophyceae
Order Phaeoplacales
Order Stichogloeales
Order Phaeothamniales
Order Chrysapionales
Order Thallochrysidales
Order Chrysosphaerales
Order Chrysosaccales
Order Rhizochrysidales
Order Ochromonadales
Order Isochrysidales
Order Silicoflagellales
Order Craspedomonadales
Order Chromulinales
Starmach (1985)
According to Starmach (1985):
Class Chrysophyceae
Subclass Heterochrysophycidae
Order Chromulinales
Order Ochromonadales
Subclass Acontochrysophycidae
Order Chrysarachniales
Order Stylococcales
Order Chrysosaccales
Order Phaeoplacales
Subclass Craspedomonadophycidae
Order Monosigales
Kristiansen (1986)
Classification of the class Chrysophyceae and splinter groups according to Kristiansen (1986):
Class Chrysophyceae
Order Ochromonadales
Order Mallomonadales
Order Chrysamoebales
Order Chrysocapsales
Order Hydrurales
Order Chrysosphaerales
Order Phaeothamniales
Order Sarcinochrysidales
Class Pedinellophyceae
Order Pedinellales
Class Dictyochophyceae
Order Dictyochales
Margulis et al. (1990)
Classification of the phylum Chrysophyta according to Margulis et al. (1990): | Golden algae | Wikipedia | 490 | 316083 | https://en.wikipedia.org/wiki/Golden%20algae | Biology and health sciences | SAR supergroup | Plants |
Phylum Chrysophyta
Class Chrysophyceae
Class Pedinellophyceae
Class Dictyochophyceae (= Silicoflagellata)
van den Hoek et al. (1995)
According to van den Hoek, Mann and Jahns (1995):
Class Chrysophyceae
Order Ochromonadales (e.g., Ochromonas, Pseudokephyrion, Dinobryon)
Order Mallomonadales (= Class Synurophyceae, e.g., Mallomonas, Synura)
Order Pedinellales (= Class Pedinellophyceae, e.g., Pedinella)
Order Chrysamoebidales (e.g., Rhizochrysis, Chrysarachnion)
Order Chrysocapsales (e.g., Chrysocapsa, Hydrurus)
Order Chrysosphaerales (e.g., Chrysosphaera)
Order Phaeothamniales (e.g., Phaeothamnion, Thallochrysis)
Preisig (1995)
Classification of the class Chrysophyceae and splinter groups according to Preisig (1995):
Class Chrysophyceae
Order Bicosoecales
Order Chromulinales
Order Hibberdiales
Order Hydrurales
Order Sancinochrysidales
Order Chrysomioridales
Class Dictyochophyceae
Order Pedinellales
Order Rhizochromulinales
Order Dictyochales
Class Synurophyceae
Order Synurales
Guiry and Guiry (2019)
According to Guiry and Guiry (2019):
Class Chrysophyceae
Order Chromulinales
Order Hibberdiales
Order Hydrurales
Order Rhizochrysidales
Order Thallochrysidales
Chrysophyceae ordo incertae sedis (11 genera)
Ecology
Chrysophytes live mostly in freshwater, and are important for studies of food web dynamics in oligotrophic freshwater ecosystems, and for assessment of environmental degradation resulting from eutrophication and acid rain.
Evolution | Golden algae | Wikipedia | 458 | 316083 | https://en.wikipedia.org/wiki/Golden%20algae | Biology and health sciences | SAR supergroup | Plants |
Chrysophytes contain the pigment fucoxanthin. Because of this, they were once considered to be a specialized form of cyanobacteria. Because many of these organisms had a silica capsule, they have a relatively complete fossil record, allowing modern biologists to confirm that they are, in fact, not derived from cyanobacteria, but rather an ancestor that did not possess the capability to photosynthesize. Many of the chrysophyta precursor fossils entirely lacked any type of photosynthesis-capable pigment. The most primitive stramenopiles are regarded as heterotrophic, such as the ancestors of the Chrysophyceae were likely heterotrophic flagellates that obtained their ability to photosynthesize from an endosymbiotic relationship with fucoxanthin-containing cyanobacteria. | Golden algae | Wikipedia | 179 | 316083 | https://en.wikipedia.org/wiki/Golden%20algae | Biology and health sciences | SAR supergroup | Plants |
The chamois (; ) (Rupicapra rupicapra) or Alpine chamois is a species of goat-antelope native to the mountains in Southern Europe, from the Pyrenees, the Alps, the Apennines, the Dinarides, the Tatra to the Carpathian Mountains, the Balkan Mountains, the Rila–Rhodope massif, Pindus, the northeastern mountains of Turkey, and the Caucasus. It has also been introduced to the South Island of New Zealand. Some subspecies of chamois are strictly protected in the EU under the European Habitats Directive.
Description
The chamois is a very small bovid. A fully grown chamois reaches a height of and measures . Males, which weigh , are slightly larger than females, which weigh . Both males and females have short, straightish horns which are hooked backwards near the tip, the horn of the male being thicker. In summer, the fur has a rich brown colour which turns to a light grey in winter. Distinct characteristics are white contrasting marks on the sides of the head with pronounced black stripes below the eyes, a white rump and a black stripe along the back.
Biology and behaviour
Female chamois and their young live in herds of up to 15 to 30 individuals; adult males tend to live solitarily for most of the year.
During the rut (late November/early December in Europe, May in New Zealand), males engage in fierce battles for the attention of unmated females. An impregnated female undergoes a gestation period of 170 days, after which a single kid is usually born in May or early June. On rare occasions, twins may be born. If a mother is killed, other females in the herd may try to raise the young.
Kids are weaned at six months of age and are fully grown by one year of age, but do not reach sexual maturity until they are three to four years old, although some females may mate at as early two years old. At sexual maturity, young males are forced out of their mother's herds by dominant males (who sometimes kill them), to wander somewhat nomadically until they can establish themselves as mature breeding specimens at eight to nine years of age.
Chamois eat various types of vegetation, including highland grasses and herbs during the summer and conifers, barks and needles from trees in winter. Primarily diurnal in activity, they often rest around mid-day and may actively forage during moonlit nights. | Chamois | Wikipedia | 511 | 316157 | https://en.wikipedia.org/wiki/Chamois | Biology and health sciences | Bovidae | Animals |
Chamois can reach an age of 22 years in captivity, although the average recorded age in the wild ranges from 15 to 17 years. Common causes of mortality can include avalanches, epidemics and predation. In the past, the principal predators were Eurasian lynxes, Persian leopards and Golden Jackal, gray wolves, and possibly brown bears and golden eagles, but humans are now the main predators of chamois. Chamois usually use speed and stealthy evasion to escape predators and can run at and can jump vertically into the air or over a distance of .
Distribution and habitat
The chamois is native to the Pyrenees, the mountains of south and central Europe, Turkey, and the Caucasus. It lives in precipitous, rugged, rocky terrain at moderately high elevations of up to at least . In Europe, the chamois spends the summer months in alpine meadows above the tree line, but moves to elevations of around to spend the winter in pine-dominated forests.
In New Zealand
Alpine chamois arrived in New Zealand in 1907 as a gift from the Austrian Emperor, Franz Joseph I in exchange for specimens of living ferns, rare birds and lizards. Albert E. L. Bertling, formerly head keeper of the Zoological Society's Gardens, Regent's Park, London, accepted an invitation from the New Zealand Government to deliver a consignment of chamois (two bucks and six does) to the colony. They arrived in Wellington, New Zealand, on 23 January 1907, on board SS Turakina. From Wellington the chamois were transhipped to the Manaroa and conveyed to Lyttelton, then by rail to Fairlie in South Canterbury and a four-day horse trek to Mount Cook. The first surviving releases were made in the Aoraki / Mount Cook region and these animals gradually spread over much of the South Island.
In New Zealand, chamois hunting is unrestricted and even encouraged by the Department of Conservation to limit the animal's impact on New Zealand's native alpine flora.
New Zealand chamois tend to weigh about 20% less than European individuals of the same age, suggesting that food supplies may be limited.
Taxonomy
The species R. rupicapra is categorized into seven subspecies: | Chamois | Wikipedia | 462 | 316157 | https://en.wikipedia.org/wiki/Chamois | Biology and health sciences | Bovidae | Animals |
Hunting and wildlife management
As their meat is considered tasty, chamois are popular game animals. Chamois have two traits that are exploited by hunters: the first is that they are most active in the morning and evening when they feed; the second is that they tend to look for danger originating from below, which means that a hunter stalking chamois from above is less likely to be observed and more likely to be successful.
The tuft of hair from the back of the neck, the gamsbart (chamois "beard"), is traditionally worn as a decoration on hats throughout the alpine countries.
Chamois leather
Chamois leather, traditionally made from the hide of the chamois, is very smooth and absorbent and is favoured in cleaning, buffing, and polishing because it produces no scratching. Modern chamois leather may still be made from chamois hides, but hides of deer or domestic goats or sheep are much more commonly used.
Chamois fabric
An artificial fabric known as "chamois" is made variously from cotton flannel, PVA, viscose, and other materials with similar qualities. It is napped to produce a plush surface similar to moleskin or chamois leather. | Chamois | Wikipedia | 256 | 316157 | https://en.wikipedia.org/wiki/Chamois | Biology and health sciences | Bovidae | Animals |
A compass rose or compass star, sometimes called a wind rose or rose of the winds, is a polar diagram displaying the orientation of the cardinal directions (north, east, south, and west) and their intermediate points. It is used on compasses (including magnetic ones), maps (such as compass rose networks), or monuments. It is particularly common in navigation systems, including nautical charts, non-directional beacons (NDB), VHF omnidirectional range (VOR) systems, satellite navigation devices ("GPS").
Types
Linguistic anthropological studies have shown that most human communities have four points of cardinal direction. The names given to these directions are usually derived from either locally-specific geographic features (e.g. "towards the hills", "towards the sea") or from celestial bodies (especially the sun) or from atmospheric features (winds, temperature). Most mobile populations tend to adopt sunrise and sunset for East and West and the direction from where different winds blow to denote North and South.
Classical
The ancient Greeks originally maintained distinct and separate systems of points and winds. The four Greek cardinal points (, , and ) were based on celestial bodies and used for orientation. The four Greek winds (, , , ) were confined to meteorology. Nonetheless, both systems were gradually conflated, and wind names came eventually to denote cardinal directions as well.
In his meteorological studies, Aristotle identified ten distinct winds: two north–south winds (, ) and four sets of east–west winds blowing from different latitudes—the Arctic Circle (, ), the summer solstice horizon (, ), the equinox (, ) and the winter solstice (, ). Aristotle's system was asymmetric. To restore balance, Timosthenes of Rhodes added two more winds to produce the classical 12-wind rose, and began using the winds to denote geographical direction in navigation. Eratosthenes deducted two winds from Aristotle's system, to produce the classical eight-wind rose.
The Romans (e.g. Seneca, Pliny) adopted the Greek 12-wind system, and replaced its names with Latin equivalents, e.g. , , , , etc. The De architectura of the Roman architect Vitruvius describes 24 winds. | Compass rose | Wikipedia | 470 | 316410 | https://en.wikipedia.org/wiki/Compass%20rose | Technology | Navigation | null |
According to the chronicler Einhard (), the Frankish king Charlemagne himself came up with his own names for the classical 12 winds. During the Migration Period, the Germanic names for the cardinal directions entered the Romance languages, where they replaced the Latin names borealis with north, australis with south, occidentalis with west and orientalis with east.
The following table gives a rough equivalence of the classical 12-wind rose with the modern compass directions (Note: the directions are imprecise since it is not clear at what angles the classical winds are supposed to be with each other; some have argued that they should be equally spaced at 30 degrees each; for more details, see the article on Classical compass winds).
Sidereal
The sidereal compass rose demarcates the compass points by the position of stars ("steering stars"; not to be confused with zenith stars) in the night sky, rather than winds. Arab navigators in the Red Sea and the Indian Ocean, who depended on celestial navigation, were using a 32-point sidereal compass rose before the end of the 10th century. In the northern hemisphere, the steady Pole Star (Polaris) was used for the N–S axis; the less-steady Southern Cross had to do for the southern hemisphere, as the southern pole star, Sigma Octantis, is too dim to be easily seen from Earth with the naked eye. The other thirty points on the sidereal rose were determined by the rising and setting positions of fifteen bright stars. Reading from North to South, in their rising and setting positions, these are:
The western half of the rose would be the same stars in their setting position. The true position of these stars is only approximate to their theoretical equidistant rhumbs on the sidereal compass. Stars with the same declination formed a "linear constellation" or to provide direction as the night progressed.
A similar sidereal compass was used by Polynesian and Micronesian navigators in the Pacific Ocean, although different stars were used in a number of cases, clustering around the east–west axis.
Mariner's | Compass rose | Wikipedia | 432 | 316410 | https://en.wikipedia.org/wiki/Compass%20rose | Technology | Navigation | null |
In Europe, the Classical 12-wind system continued to be taught in academic settings during the Medieval era, but seafarers in the Mediterranean came up with their own distinct 8-wind system. The mariners used names derived from the Mediterranean lingua franca, composed principally of Ligurian, mixed with Venetian, Sicilian, Provençal, Catalan, Greek and Arabic terms from around the Mediterranean basin.
(N) Tramontana
(NE) Greco (or Bora)
(E) Levante
(SE) Scirocco (or Exaloc)
(S) Ostro (or Mezzogiorno)
(SW) Libeccio (or Garbino)
(W) Ponente
(NW) Maestro (or Mistral)
The exact origin of the mariner's eight-wind rose is obscure. Only two of its point names (Ostro, Libeccio) have Classical etymologies, the rest of the names seem to be autonomously derived. Two Arabic words stand out: Scirocco (SE) from al-Sharq (الشرق – east in Arabic) and the variant Garbino (SW), from al-Gharb (الغرب – west in Arabic). This suggests the mariner's rose was probably acquired by southern Italian seafarers; not from their classical Roman ancestors, but rather from Norman Sicily in the 11th to 12th centuries. The coasts of the Maghreb and Mashriq are SW and SE of Sicily respectively; the Greco (a NE wind), reflects the position of Byzantine-held Calabria-Apulia to the northeast of Arab Sicily, while the Maestro (a NW wind) is a reference to the Mistral wind that blows from the southern French coast towards northwest Sicily. | Compass rose | Wikipedia | 367 | 316410 | https://en.wikipedia.org/wiki/Compass%20rose | Technology | Navigation | null |
The 32-point compass used for navigation in the Mediterranean by the 14th century, had increments of 11° between points. Only the eight principal winds (N, NE, E, SE, S, SW, W, NW) were given special names. The eight half-winds just combined the names of the two principal winds, e.g. Greco-Tramontana for NNE, Greco-Levante for ENE, and so on. Quarter-winds were more cumbersomely phrased, with the closest principal wind named first and the next-closest principal wind second, e.g. "Quarto di Tramontana verso Greco" (literally, "one quarter wind from North towards Northeast", i.e. North by East), and "Quarto di Greco verso Tramontana" ("one quarter wind from NE towards N", i.e. Northeast by North). Boxing the compass (naming all 32 winds) was expected of all Medieval mariners.
Depiction on nautical charts
In the earliest medieval portolan charts of the 14th century, compass roses were depicted as mere collections of color-coded compass rhumb lines: black for the eight main winds, green for the eight half-winds and red for the sixteen quarter-winds. The average portolan chart had sixteen such roses (or confluence of lines), spaced out equally around the circumference of a large implicit circle.
The cartographer Cresques Abraham of Majorca, in his Catalan Atlas of 1375, was the first to draw an ornate compass rose on a map. By the end of the 15th century, Portuguese cartographers began drawing multiple ornate compass roses throughout the chart, one upon each of the sixteen circumference roses (unless the illustration conflicted with coastal details). | Compass rose | Wikipedia | 371 | 316410 | https://en.wikipedia.org/wiki/Compass%20rose | Technology | Navigation | null |
The points on a compass rose were frequently labeled by the initial letters of the mariner's principal winds (T, G, L, S, O, L, P, M). From the outset, the custom also began to distinguish the north from the other points by a specific visual marker. Medieval Italian cartographers typically used a simple arrowhead or circumflex-hatted T (an allusion to the compass needle) to designate the north, while the Majorcan cartographic school typically used a stylized Pole Star for its north mark. The use of the fleur-de-lis as north mark was introduced by Pedro Reinel, and quickly became customary in compass roses (and is still often used today). Old compass roses also often used a Christian cross at Levante (E), indicating the direction of Jerusalem from the point of view of the Mediterranean sea.
The twelve Classical winds (or a subset of them) were also sometimes depicted on portolan charts, albeit not on a compass rose, but rather separately on small disks or coins on the edges of the map.
The compass rose was also depicted on traverse boards used on board ships to record headings sailed at set time intervals.
Modern depictions
The contemporary compass rose appears as two rings, one smaller and set inside the other. The outside ring denotes true cardinal directions while the smaller inside ring denotes magnetic cardinal directions. True north refers to the geographical location of the north pole while magnetic north refers to the direction towards which the north pole of a magnetic object (as found in a compass) will point. The angular difference between true and magnetic north is called variation, which varies depending on location. The angular difference between magnetic heading and compass heading is called deviation which varies by vessel and its heading. North arrows are often included in contemporary maps as part of the map layout.
The modern compass rose has eight principal winds. Listed clockwise, these are:
Although modern compasses use the names of the eight principal directions (N, NE, E, SE, etc.), older compasses use the traditional Italianate wind names of Medieval origin (Tramontana, Greco, Levante, etc.).
Four-point compass roses use only the four "basic winds" or "cardinal directions" (North, East, South, West), with angles of difference at 90°. | Compass rose | Wikipedia | 475 | 316410 | https://en.wikipedia.org/wiki/Compass%20rose | Technology | Navigation | null |
Eight-point compass roses use the eight principal winds—that is, the four cardinal directions (N, E, S, W) plus the four "intercardinal" or "ordinal directions" (NE, SE, SW, NW), at angles of difference of 45°.
Twelve-point compass roses, with markings 30° apart, are often painted on airport ramps to assist with the adjustment of aircraft magnetic compass compensators.
Sixteen-point compass roses are constructed by bisecting the angles of the principal winds to come up with intermediate compass points, known as half-winds, at angles of difference of 22°. The names of the half-winds are simply combinations of the principal winds to either side, principal then ordinal. E.g. North-northeast (NNE), East-northeast (ENE), etc. Using gradians, of which there are 400 in a circle, the sixteen-point rose has twenty-five gradians per point.
Thirty-two-point compass roses are constructed by bisecting these angles, and coming up with quarter-winds at 11° angles of difference. Quarter-wind names are constructed with the names "X by Y", which can be read as "one quarter wind from X toward Y", where X is one of the eight principal winds and Y is one of the two adjacent cardinal directions. For example, North-by-east (NbE) is one quarter wind from North towards East, Northeast-by-north (NEbN) is one quarter wind from Northeast toward North. Naming all 32 points on the rose is called "boxing the compass".
The 32-point rose has 11° between points, but is easily found by halving divisions and may have been easier for those not using a 360° circle. Eight points make a right angle and a point is easy to estimate allowing bearings to be given such as "two points off the starboard bow".
Use as symbol | Compass rose | Wikipedia | 405 | 316410 | https://en.wikipedia.org/wiki/Compass%20rose | Technology | Navigation | null |
The NATO symbol uses a four-pointed rose.
Outward Bound uses the compass rose as the logo for various schools around the world.
An 8-point compass rose was the logo of Varig, the largest airline in Brazil for many decades until its bankruptcy in 2006.
An 8-point compass rose is a prominent feature in the logo of the Seattle Mariners Major League Baseball club.
Hong Kong Correctional Services's crest uses a four-pointed compass rose.
The compass rose is used as the symbol of the worldwide Anglican Communion of churches.
A 16-point compass rose was IBM's logo for the System/360 product line.
A 16-point compass rose is the official logo of the Spanish National University of Distance Education (Universidad Nacional de Educación a Distancia or UNED).
A 16-point compass rose is present on the seal and the flag of the Central Intelligence Agency of the federal government of the United States (the CIA).
Tattoos of eight-pointed stars are used by the Vor v Zakone to denote rank.
In popular culture
The Compass Rose is a 1982 collection of short stories by Ursula K. Le Guin. | Compass rose | Wikipedia | 232 | 316410 | https://en.wikipedia.org/wiki/Compass%20rose | Technology | Navigation | null |
Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "pyroclastics," and these are also technically sedimentary rocks.
Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces. It has been estimated that volcanic rocks cover about 8% of the Earth's current land surface.
Characteristics
Setting and size
Lava
Tephra
Volcanic bomb
Lapilli
Volcanic ash
Texture
Volcanic rocks are usually fine-grained or aphanitic to glass in texture. They often contain clasts of other rocks and phenocrysts. Phenocrysts are crystals that are larger than the matrix and are identifiable with the unaided eye. Rhomb porphyry is an example with large rhomb shaped phenocrysts embedded in a very fine grained matrix.
Volcanic rocks often have a vesicular texture caused by voids left by volatiles trapped in the molten lava. Pumice is a highly vesicular rock produced in explosive volcanic eruptions.
Chemistry
Most modern petrologists classify igneous rocks, including volcanic rocks,
by their chemistry when dealing with their origin. The fact that different mineralogies and textures may be developed from the same initial magmas has led petrologists to rely heavily on chemistry to look at a volcanic rock's origin. | Volcanic rock | Wikipedia | 404 | 316414 | https://en.wikipedia.org/wiki/Volcanic%20rock | Physical sciences | Igneous rocks | Earth science |
The chemical classification of igneous rocks is based first on the total content of silicon and alkali metals (sodium and potassium) expressed as weight fraction of silica and alkali oxides (K2O plus Na2O). These place the rock in one of the fields of the TAS diagram. Ultramafic rock and carbonatites have their own specialized classification, but these rarely occur as volcanic rocks. Some fields of the TAS diagram are further subdivided by the ratio of potassium oxide to sodium oxide. Additional classifications may be made on the basis of other components, such as aluminum or iron content.
Volcanic rocks are also broadly divided into subalkaline, alkaline, and peralkaline volcanic rocks. Subalkaline rocks are defined as rocks in which
SiO2 < -3.3539 × 10−4 × A6 + 1.2030 × 10−2 × A5 - 1.5188 × 10−1 × A4 + 8.6096 × 10−1 × A3 - 2.1111 × A2 + 3.9492 × A + 39.0
where both silica and total alkali oxide content (A) are expressed as molar fraction. Because the TAS diagram uses weight fraction and the boundary between alkaline and subalkaline rock is defined in terms of molar fraction, the position of this curve on the TAS diagram is only approximate. Peralkaline volcanic rocks are defined as rocks having Na2O + K2O > Al2O3, so that some of the alkali oxides must be present as aegirine or sodic amphibole rather than feldspar.
The chemistry of volcanic rocks is dependent on two things: the initial composition of the primary magma and the subsequent differentiation. Differentiation of most magmas tends to increase the silica (SiO2) content, mainly by crystal fractionation. The initial composition of most magmas is basaltic, albeit small differences in initial compositions may result in multiple differentiation series. The most common of these series are the tholeiitic, calc-alkaline, and alkaline. | Volcanic rock | Wikipedia | 442 | 316414 | https://en.wikipedia.org/wiki/Volcanic%20rock | Physical sciences | Igneous rocks | Earth science |
Mineralogy
Most volcanic rocks share a number of common minerals. Differentiation of volcanic rocks tends to increase the silica (SiO2) content mainly by fractional crystallization. Thus, more evolved volcanic rocks tend to be richer in minerals with a higher amount of silica such as phyllo and tectosilicates including the feldspars, quartz polymorphs and muscovite. While still dominated by silicates, more primitive volcanic rocks have mineral assemblages with less silica, such as olivine and the pyroxenes. Bowen's reaction series correctly predicts the order of formation of the most common minerals in volcanic rocks.
Occasionally, a magma may pick up crystals that crystallized from another magma; these crystals are called xenocrysts. Diamonds found in kimberlites are rare but well-known xenocrysts; the kimberlites do not create the diamonds, but pick them up and transport them to the surface of the Earth.
Naming
Volcanic rocks are named according to both their chemical composition and texture. Basalt is a very common volcanic rock with low silica content. Rhyolite is a volcanic rock with high silica content. Rhyolite has silica content similar to that of granite while basalt is compositionally equal to gabbro. Intermediate volcanic rocks include andesite, dacite, trachyte, and latite.
Pyroclastic rocks are the product of explosive volcanism. They are often felsic (high in silica). Pyroclastic rocks are often the result of volcanic debris, such as ash, bombs and tephra, and other volcanic ejecta. Examples of pyroclastic rocks are tuff and ignimbrite.
Shallow intrusions, which possess structure similar to volcanic rather than plutonic rocks, are also considered to be volcanic, shading into subvolcanic. | Volcanic rock | Wikipedia | 395 | 316414 | https://en.wikipedia.org/wiki/Volcanic%20rock | Physical sciences | Igneous rocks | Earth science |
The terms lava stone and lava rock are more used by marketers than geologists, who would likely say "volcanic rock" (because lava is a molten liquid and rock is solid). "Lava stone" may describe anything from a friable silicic pumice to solid mafic flow basalt, and is sometimes used to describe rocks that were never lava, but look as if they were (such as sedimentary limestone with dissolution pitting). To convey anything about the physical or chemical properties of the rock, a more specific term should be used; a good supplier will know what sort of volcanic rock they are selling.
Composition of volcanic rocks
The sub-family of rocks that form from volcanic lava are called igneous volcanic rocks (to differentiate them from igneous rocks that form from magma below the surface, called igneous plutonic rocks).
The lavas of different volcanoes, when cooled and hardened, differ much in their appearance and composition. If a rhyolite lava-stream cools quickly, it can quickly freeze into a black glassy substance called obsidian. When filled with bubbles of gas, the same lava may form the spongy appearing pumice. Allowed to cool slowly, it forms a light-colored, uniformly solid rock called rhyolite.
The lavas, having cooled rapidly in contact with the air or water, are mostly finely crystalline or have at least fine-grained ground-mass representing that part of the viscous semi-crystalline lava flow that was still liquid at the moment of eruption. At this time they were exposed only to atmospheric pressure, and the steam and other gases, which they contained in great quantity were free to escape; many important modifications arise from this, the most striking being the frequent presence of numerous steam cavities (vesicular structure) often drawn out to elongated shapes subsequently filled up with minerals by infiltration (amygdaloidal structure). | Volcanic rock | Wikipedia | 390 | 316414 | https://en.wikipedia.org/wiki/Volcanic%20rock | Physical sciences | Igneous rocks | Earth science |
As crystallization was going on while the mass was still creeping forward under the surface of the Earth, the latest formed minerals (in the ground-mass) are commonly arranged in subparallel winding lines that follow the direction of movement (fluxion or fluidal structure)—and larger early minerals that previously crystallized may show the same arrangement. Most lavas fall considerably below their original temperatures before emitted. In their behavior, they present a close analogy to hot solutions of salts in water, which, when they approach the saturation temperature, first deposit a crop of large, well-formed crystals (labile stage) and subsequently precipitate clouds of smaller less perfect crystalline particles (metastable stage).
In igneous rocks the first generation of crystals generally forms before the lava has emerged to the surface, that is to say, during the ascent from the subterranean depths to the crater of the volcano. It has frequently been verified by observation that freshly emitted lavas contain large crystals borne along in a molten, liquid mass. The large, well-formed, early crystals (phenocrysts) are said to be porphyritic; the smaller crystals of the surrounding matrix or ground-mass belong to the post-effusion stage. More rarely lavas are completely fused at the moment of ejection; they may then cool to form a non-porphyritic, finely crystalline rock, or if more rapidly chilled may in large part be non-crystalline or glassy (vitreous rocks such as obsidian, tachylyte, pitchstone).
A common feature of glassy rocks is the presence of rounded bodies (spherulites), consisting of fine divergent fibres radiating from a center; they consist of imperfect crystals of feldspar, mixed with quartz or tridymite; similar bodies are often produced artificially in glasses that are allowed to cool slowly. Rarely these spherulites are hollow or consist of concentric shells with spaces between (lithophysae). Perlitic structure, also common in glasses, consists of the presence of concentric rounded cracks owing to contraction on cooling. | Volcanic rock | Wikipedia | 437 | 316414 | https://en.wikipedia.org/wiki/Volcanic%20rock | Physical sciences | Igneous rocks | Earth science |
The phenocrysts or porphyritic minerals are not only larger than those of the ground-mass; as the matrix was still liquid when they formed they were free to take perfect crystalline shapes, without interference by the pressure of adjacent crystals. They seem to have grown rapidly, as they are often filled with enclosures of glassy or finely crystalline material like that of the ground-mass . Microscopic examination of the phenocrysts often reveals that they have had a complex history. Very frequently they show layers of different composition, indicated by variations in color or other optical properties; thus augite may be green in the center surrounded by various shades of brown; or they may be pale green centrally and darker green with strong pleochroism (aegirine) at the periphery.
In the feldspars the center is usually richer in calcium than the surrounding layers, and successive zones may often be noted, each less calcic than those within it. Phenocrysts of quartz (and of other minerals), instead of sharp, perfect crystalline faces, may show rounded corroded surfaces, with the points blunted and irregular tongue-like projections of the matrix into the substance of the crystal. It is clear that after the mineral had crystallized it was partly again dissolved or corroded at some period before the matrix solidified.
Corroded phenocrysts of biotite and hornblende are very common in some lavas; they are surrounded by black rims of magnetite mixed with pale green augite. The hornblende or biotite substance has proved unstable at a certain stage of consolidation, and has been replaced by a paramorph of augite and magnetite, which may partially or completely substitute for the original crystal but still retains its characteristic outlines. | Volcanic rock | Wikipedia | 367 | 316414 | https://en.wikipedia.org/wiki/Volcanic%20rock | Physical sciences | Igneous rocks | Earth science |
Mechanical behaviour of volcanic rocks
The mechanical behaviour of volcanic rocks is complicated by their complex microstructure. For example, attributes such as the partitioning of the void space (pores and microcracks), pore and crystal size and shape, and hydrothermal alteration can all vary widely in volcanic rocks and can all influence the resultant mechanical behaviour (e.g., Young's modulus, compressive and tensile strength, and the pressure at which they transition from brittle to ductile behaviour). As for other crustal rocks, volcanic rocks are brittle and ductile at low and high effective confining pressures, respectively. Brittle behaviour is manifest as faults and fractures, and ductile behaviour can either be distributed (cataclastic pore collapse) or localised (compaction bands). Understanding the mechanical behaviour of volcanic rocks can help us better understand volcanic hazards, such as flank collapse. | Volcanic rock | Wikipedia | 185 | 316414 | https://en.wikipedia.org/wiki/Volcanic%20rock | Physical sciences | Igneous rocks | Earth science |
Thallus (: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. A thallus usually names the entire body of a multicellular non-moving organism in which there is no organization of the tissues into organs. Many of these organisms were previously known as the thallophytes, a polyphyletic group of distantly related organisms. An organism or structure resembling a thallus is called thalloid, thalloidal, thalliform, thalline, or thallose.
Even though thalli do not have organized and distinct parts (leaves, roots, and stems) as do the vascular plants, they may have analogous structures that resemble their vascular "equivalents". The analogous structures have similar function or macroscopic structure, but different microscopic structure; for example, no thallus has vascular tissue. In exceptional cases such as the Lemnoideae, where the structure of a vascular plant is in fact thallus-like, it is referred to as having a thalloid structure, or sometimes as a thalloid.
Although a thallus is largely undifferentiated in terms of its anatomy, there can be visible differences and functional differences. A kelp, for example, may have its thallus divided into three regions. The parts of a kelp thallus include the holdfast (anchor), stipe (supports the blades) and the blades (for photosynthesis).
The thallus of a fungus is usually called a mycelium. The term thallus is also commonly used to refer to the vegetative body of a lichen. In seaweed, thallus is sometimes also called 'frond'.
The gametophyte of some non-thallophyte plants – clubmosses, horsetails, and ferns is termed "prothallus". | Thallus | Wikipedia | 417 | 316528 | https://en.wikipedia.org/wiki/Thallus | Biology and health sciences | Fungal morphology and anatomy | Biology |
Spring, also known as springtime, is one of the four temperate seasons, succeeding winter and preceding summer. There are various technical definitions of spring, but local usage of the term varies according to local climate, cultures and customs. When it is spring in the Northern Hemisphere, it is autumn in the Southern Hemisphere and vice versa. At the spring (or vernal) equinox, days and nights are approximately twelve hours long, with daytime length increasing and nighttime length decreasing as the season progresses until the Summer Solstice in June (Northern Hemisphere) and December (Southern Hemisphere).
Spring and "springtime" refer to the season, and also to ideas of rebirth, rejuvenation, renewal, resurrection and regrowth. Subtropical and tropical areas have climates better described in terms of other seasons, e.g. dry or wet, monsoonal or cyclonic. Cultures may have local names for seasons which have little equivalence to the terms originating in Europe.
Etymology
According to the Online Etymological Dictionary, "spring" in the sense of the season comes from phrases such as "springing time" (14th century) and "the spring of the year". This use is from an archaic noun meaning "act or time of springing or appearing; the first appearance; the beginning, birth, rise, or origin". Spring as a word in general appeared via the Middle English springen, via the Old English springan. These were verbs meaning to rise up or to burst forth, (see also the modern German springen 'jump') and are not believed to have originally related to the season. These all originate from Proto-Germanic *sprenganan.
Meteorological reckoning
Meteorologists generally define four seasons in many climatic areas: spring, summer, autumn (fall), and winter. These are determined by the values of their average temperatures on a monthly basis, with each season lasting three calendar months. The three warmest months are by definition summer, the three coldest months are winter, and the intervening gaps are spring and autumn. Meteorological spring can therefore, start on different dates in different regions.
In the United States and United Kingdom, spring months are March, April, and May.
In Ireland, following the Irish calendar, spring is often defined as February, March, and April. | Spring (season) | Wikipedia | 469 | 316532 | https://en.wikipedia.org/wiki/Spring%20%28season%29 | Physical sciences | Seasons | null |
In Sweden, meteorologists define the beginning of spring as the first occasion on which the average 24 hours temperature exceeds zero degrees Celsius for seven consecutive days, thus the date varies with latitude and elevation (but no earlier than 15 February, and no later than 31 July).
In Australia, New Zealand, South Africa and Brazil the spring months are September, October, and November.
Astronomical and solar reckoning
In the Northern Hemisphere (with countries such as Germany, the United States, Canada, and the UK), solar reckoning was traditionally used with the solstices and equinoxes representing the midpoints of each season, however, the astronomical vernal equinox (varying between 19 and 21 March) can be taken to mark the first day of spring with the summer solstice (around 21 June) marked as first day of summer. By solar reckoning, Spring is held to begin 1 February until the first day of Summer on May Day, with the summer and winter solstices being marked as Midsummer and Midwinter respectively, instead of as the beginning of the season as is the case with astronomical reckoning.
In Persian culture the first day of spring is the first day of the first month (called Farvardin) which begins on 20 or 21 March.
In the traditional Chinese calendar, the "spring" season () consists of the days between Lichun (3–5 February), taking Chunfen (20–22 March) as its midpoint, then ending at Lixia (5–7 May). Similarly, according to the Celtic tradition, which is based solely on daylight and the strength of the noon sun, spring begins in early February (near Imbolc or Candlemas) and continues until early May (Beltane), with Saint Patrick's Day (17 March) being regarded as the middle day of spring. Late Roman Republic scholar Marcus Terentius Varro defined spring as lasting from the seventh day before the Ides of Februarius (7 February) to the eighth day before the Ides of Maius (8 May).
The spring season in India is culturally in the months of March and April, with an average temperature of approx 32 °C. Some people in India especially from Karnataka state celebrate their new year in spring, Ugadi. | Spring (season) | Wikipedia | 470 | 316532 | https://en.wikipedia.org/wiki/Spring%20%28season%29 | Physical sciences | Seasons | null |
Ecological reckoning
The beginning of spring is not always determined by fixed calendar dates. The phenological or ecological definition of spring relates to biological indicators, such as the blossoming of a range of plant species, the activities of animals, and the special smell of soil that has reached the temperature for micro flora to flourish. These indicators, along with the beginning of spring, vary according to the local climate and according to the specific weather of a particular year. In England, Wales and Northern Ireland, the National Trust runs the #BlossomWatch campaign, which encourages people to share images of blossom with one another, as an early indicator of the arrival of the season.
Some ecologists divide the year into six seasons. In addition to spring, ecological reckoning identifies an earlier separate prevernal (early or pre-spring) season between the hibernal (winter) and vernal (spring) seasons. This is a time when only the hardiest flowers like the crocus are in bloom, sometimes while there is still some snowcover on the ground.
Natural events
During early spring, the axis of the Earth is increasing its tilt relative to the Sun, and the length of daylight rapidly increases for the relevant hemisphere. The hemisphere begins to warm significantly, causing new plant growth to "spring forth", giving the season its name.
Any snow begins to melt, swelling streams with runoff and any frosts become less severe. In climates that have no snow, and rare frosts, air and ground temperatures increase more rapidly.
Many flowering plants bloom at this time of year, in a long succession, sometimes beginning when snow is still on the ground and continuing into early summer. In normally snowless areas, "spring" may begin as early as February (Northern Hemisphere) or August (Southern Hemisphere), heralded by the blooming of deciduous magnolias, cherries, and quince. Many temperate areas have a dry spring, and wet autumn (fall), which brings about flowering in this season, more consistent with the need for water, as well as warmth. Subarctic areas may not experience "spring" at all until May. | Spring (season) | Wikipedia | 432 | 316532 | https://en.wikipedia.org/wiki/Spring%20%28season%29 | Physical sciences | Seasons | null |
While spring is a result of the warmth caused by the changing orientation of the Earth's axis relative to the Sun, the weather in many parts of the world is affected by other, less predictable events. The rainfall in spring (or any season) follows trends more related to longer cycles—such as the solar cycle—or events created by ocean currents and ocean temperatures—for example, the El Niño effect and the Southern Oscillation Index.
Unstable spring weather may occur more often when warm air begins to invade from lower latitudes, while cold air is still pushing from the Polar regions. Flooding is also most common in and near mountainous areas during this time of year, because of snow-melt which is accelerated by warm rains. In North America, Tornado Alley is most active at this time of year, especially since the Rocky Mountains prevent the surging hot and cold air masses from spreading eastward, and instead force them into direct conflict. Besides tornadoes, supercell thunderstorms can also produce dangerously large hail and very high winds, for which a severe thunderstorm warning or tornado warning is usually issued. Even more so than in winter, the jet streams play an important role in unstable and severe Northern Hemisphere weather in springtime.
In recent decades, season creep has been observed, which means that many phenological signs of spring are occurring earlier in many regions by around two days per decade.
Spring in the Southern Hemisphere is different in several significant ways to that of the Northern Hemisphere for several reasons, including:
There is no land bridge between Southern Hemisphere countries and the Antarctic zone capable of bringing in cold air without the temperature-mitigating effects of extensive tracts of water;
The vastly greater amount of ocean in the Southern Hemisphere at most latitudes;
There is a circumpolar flow of air (the roaring 40s and 50s) uninterrupted by large land masses;
No equivalent jet streams; and
The peculiarities of the reversing ocean currents in the Pacific.
Cultural associations
Carnival
Carnival is practiced by many Christians around the world in the days before Lent (40 days, without Sundays, before Easter). It is the first spring festival of the new year for many.
Easter | Spring (season) | Wikipedia | 441 | 316532 | https://en.wikipedia.org/wiki/Spring%20%28season%29 | Physical sciences | Seasons | null |
Easter is the most important religious feast in the Christian liturgical year.
Christians believe that Jesus was resurrected from the dead on the "third day" (two days after his crucifixion), and celebrate this resurrection on Easter Day, two days after Good Friday. Since the Last Supper was a Passover Seder, the date of Easter can be calculated as the first Sunday after the start of Passover. This is usually (see Passover below) the first Sunday after the first full moon following the spring equinox. The date of Easter varies between 22 March and 25 April (which corresponds to between 4 April and 8 May in the Gregorian Calendar for the Eastern and Oriental Orthodox Churches using the Julian Calendar). In this celebration, the children do an easter egg hunt.
May Day
The First of May is the date of many public holidays. In many countries, May Day is synonymous with International Workers' Day, or Labour Day, which celebrates the social and economic achievements of the labour movement. As a day of celebration, the holiday has ancient origins, and it can relate to many customs that have survived into modern times. Many of these customs are due to May Day being a cross-quarter day, meaning that (in the Northern Hemisphere where it is almost exclusively celebrated) it falls approximately halfway between the spring equinox and summer solstice. In the Celtic tradition, this date marked the end of spring and the beginning of summer.
Passover
The Passover begins on the 15th day of the month of Nisan, which typically falls in March or April of the Gregorian calendar on the night of a full moon after the northern spring equinox. However, due to leap months falling after the vernal equinox, Passover sometimes starts on the second full moon after vernal equinox, as in 2016. Jews celebrate this holiday to commemorate their escape from slavery in Egypt as described in the book of Exodus in the Torah.
Foods consumed during Passover seders, such as lamb and barley, are tied to springtime seasonal availability. In this celebration, children recite the Four Questions during the seder and hunt for the afikoman afterwards.
Allhallowtide
The Western Christian season encompassing the triduum of All Saints' Eve (Halloween), All Saints' Day (All Hallows') and All Souls' Day are observed in the spring in the Southern hemisphere. | Spring (season) | Wikipedia | 487 | 316532 | https://en.wikipedia.org/wiki/Spring%20%28season%29 | Physical sciences | Seasons | null |
A launch pad is an above-ground facility from which a rocket-powered missile or space vehicle is vertically launched. The term launch pad can be used to describe just the central launch platform (mobile launcher platform), or the entire complex (launch complex). The entire complex will include a launch mount or launch platform to physically support the vehicle, a service structure with umbilicals, and the infrastructure required to provide propellants, cryogenic fluids, electrical power, communications, telemetry, rocket assembly, payload processing, storage facilities for propellants and gases, equipment, access roads, and drainage.
Most launch pads include fixed service structures to provide one or more access platforms to assemble, inspect, and maintain the vehicle and to allow access to the spacecraft, including the loading of crew. The pad may contain a flame deflection structure to prevent the intense heat of the rocket exhaust from damaging the vehicle or pad structures, and a sound suppression system spraying large quantities of water may be employed. The pad may also be protected by lightning arresters. A spaceport typically includes multiple launch complexes and other supporting infrastructure.
A launch pad is distinct from a missile launch facility (or missile silo or missile complex), which also launches a missile vertically but is located underground in order to help harden it against enemy attack.
The launch complex for liquid fueled rockets often has extensive ground support equipment including propellant tanks and plumbing to fill the rocket before launch. Cryogenic propellants (liquid oxygen oxidizer, and liquid hydrogen or liquid methane fuel) need to be continuously topped off (i.e., boil-off replaced) during the launch sequence (countdown), as the vehicle awaits liftoff. This becomes particularly important as complex sequences may be interrupted by planned or unplanned holds to fix problems.
Most rockets need to be supported and held down for a few seconds after ignition while the engines build up to full thrust. The vehicle is commonly held on the pad by hold-down arms or explosive bolts, which are triggered when the vehicle is stable and ready to fly, at which point all umbilical connections with the pad are released.
History | Launch pad | Wikipedia | 436 | 316577 | https://en.wikipedia.org/wiki/Launch%20pad | Technology | Basics_6 | null |
Precursors to modern rocketry, such as fireworks and rocket launchers, did not generally require dedicated launch pads. This was due in part to their relatively portable size, as well as the sufficiency of their casings in sustaining stresses. One of the first pads for a liquid-fueled rocket, what would later be named the Goddard Rocket Launching Site after Robert H. Goddard's series of launch tests starting in 1926, consisted of a mount situated on an open field in rural Massachusetts. The mount consisted of a frame with a series of gasoline and liquid oxygen lines feeding into the rocket.
It wasn't until the 1930s that rockets were increasing enough in size and strength that specialized launch facilities became necessary. The Verein für Raumschiffahrt in Germany was permitted after a request for funding in 1930 to move from farms to the Berlin rocket launching site (), a repurposed ammunition dump.
A test stand was built for liquid-propellant rockets in Kummersdorf in 1932, where the early designs from the Aggregat series of ballistic missiles were afterwards developed. This site was also the location of the first casualties in rocket development, when Dr. Wahmke and 2 assistants were killed, and another assistant was injured. A propellant fuel tank exploded, while experimenting with mixing 90% hydrogen peroxide and alcohol, before combustion.
In May 1937, Dornberger, and most of his staff, moved to the Peenemünde Army Research Center on the island of Usedom on the Baltic coast which offered much greater space and secrecy. Dr. Thiel and his staff followed in the summer of 1940. Test Stand VI at Pennemünde was an exact replica to Kummersdorf's large test stand. It was this site which saw the development of the V-2 rocket. Test Stand VII was the principle testing facility at the Peenemünde Airfield and was capable of static firing rocket motors with up to 200 tons of thrust.
Launch pads would increase in complexity over the following decades throughout and following the Space Race. Where large volumes of exhaust gases are expelled during engine testing or vehicle launch, a flame deflector might be implemented to mitigate damage to the surrounding pad and direct exhaust. This is especially important with reusable launch vehicles to increase efficiency of launches while minimizing time spent refurbishing.
Construction | Launch pad | Wikipedia | 478 | 316577 | https://en.wikipedia.org/wiki/Launch%20pad | Technology | Basics_6 | null |
The construction of a launch pad begins with site selection, considering various geographical and logistical factors. It is often advantageous to position the launch pad on the coast, particularly with the ocean to the east, to leverage the Earth's rotation and increase the specific impulse of launches. Space programs such as Soviet space program or the French space program without this luxury may utilize facilities outside of their main territory such as the Baikonur Cosmodrome or Guiana Space Centre to launch for them. This orientation also allows for safe trajectory paths, minimizing risks to populated areas during ascent.
Facilities
Transport of rockets to the pad
Each launch site is unique, but a few broad types can be described by the means by which the space vehicle gets to the pad.
Horizontally integrated rockets travel horizontally with the tail forward to the launch site on a transporter erector launcher and are then raised to the vertical position over the flame duct. Examples include all large Soviet rockets, including Soyuz, Proton, N1, and Energia. This method is also used by the SpaceX and Electron launch vehicles.
Silo launched rockets are assembled inside of a missile silo. This method is only used by converted ICBMs due to the difficulty and expense of constructing a silo that can contain the forces of a rocket launch.
Vertically integrated rockets can be assembled in a separate hangar on a mobile launcher platform (MLP). The MLP contains the umbilical structure and is carried to the launch site on a large vehicle called Crawler-transporter. Launch Complex 39 at the Kennedy Space Center is an example of a facility using this method. A similar system is used to launch Ariane 5 rockets at ELA-3 at Guiana Space Centre.
Vertically assembled vehicles can also be transported on a mobile launcher platform resting on two parallel standard gauge railroad tracks that run from the integration building to launch area. This system is in use for the Atlas V and future Vulcan.
At SLC-6 and SLC-37, rockets are assembled on the launch mount. A windowless rail-mounted building encloses the launch pad and gantry to protect the vehicle from the elements, and for purposes of military secrecy. Prior to launch, the building is rolled away. This method is also used at Kagoshima for the M-V.
The former Sea Launch service used the converted self-propelled oil drilling platform Ocean Odyssey to transport Zenit 3SL rockets horizontally to the Equator, and then to erect and launch them from a floating launch platform into geostationary transfer orbits. | Launch pad | Wikipedia | 511 | 316577 | https://en.wikipedia.org/wiki/Launch%20pad | Technology | Basics_6 | null |
Service structure
A service structure is a steel framework or tower that is built on a launch pad to facilitate assembly and servicing.
An umbilical tower also usually includes an elevator which allows maintenance and crew access. Immediately before ignition of the rocket's motors, all connections between the tower and the craft are severed, and the bridges over which these connections pass often quickly swing away to prevent damage to the structure or vehicle.
Flame deflector systems
A flame deflector, flame diverter or flame trench is a structure or device designed to redirect or disperse the flame, heat, and exhaust gases produced by rocket engines or other propulsion systems. The amount of thrust generated by a rocket launch, along with the sound it produces during liftoff, can damage the launchpad and service structure, as well as the launch vehicle. The primary goal of the diverter is to prevent the flame from causing damage to equipment, infrastructure, or the surrounding environment. Flame diverters can be found at rocket launch sites and test stands where large volumes of exhaust gases are expelled during engine testing or vehicle launch.
Sound suppression systems
Sites for launching large rockets are often equipped with a sound suppression system to absorb or deflect acoustic energy generated during a rocket launch. As engine exhaust gasses exceed the speed of sound, they collide with the ambient air and shockwaves are created, with noise levels approaching 200 db. This energy can be reflected by the launch platform and pad surfaces, and could potentially cause damage to the launch vehicle, payload, and crew. For instance, the maximum admissible overall sound power level (OASPL) for payload integrity is approximately 145 db. Sound is dissipated by huge volumes of water distributed across the launch pad and launch platform during liftoff.
Water-based acoustic suppression systems are common on launch pads. They aid in reducing acoustic energy by injecting large quantities of water below the launch pad into the exhaust plume and in the area above the pad. Flame deflectors or flame trenches are designed to channel rocket exhaust away from the launch pad but also redirect acoustic energy away. | Launch pad | Wikipedia | 421 | 316577 | https://en.wikipedia.org/wiki/Launch%20pad | Technology | Basics_6 | null |
Hydrogen burn-off systems
In rockets using liquid hydrogen as their source of propellant, hydrogen burn-off systems (HBOI), also known as radially outward firing igniters (ROFI), can be utilized to prevent the build up of free gaseous hydrogen (GH2) in the aft engine area of the vehicle prior to engine start. Too much excess hydrogen in the aft during engine start can result in an overpressure blast wave that could damage the launch vehicle and surrounding pad structures.
Validating engine performance and system readiness
The SpaceX launch sequence includes a hold-down feature of the launch pad that allows full engine ignition and systems check before liftoff. After the first-stage engine starts, the launcher is held down and not released for flight until all propulsion and vehicle systems are confirmed to be operating normally. Similar hold-down systems have been used on launch vehicles such as Saturn V and Space Shuttle. An automatic safe shut-down and unloading of propellant occur if any abnormal conditions are detected. Prior to the launch date, SpaceX sometimes completes a test cycle, culminating in a three-and-a-half second first stage engine static firing as well. | Launch pad | Wikipedia | 240 | 316577 | https://en.wikipedia.org/wiki/Launch%20pad | Technology | Basics_6 | null |
A spring is a natural exit point at which groundwater emerges from an aquifer and flows across the ground surface as surface water. It is a component of the hydrosphere, as well as a part of the water cycle. Springs have long been important for humans as a source of fresh water, especially in arid regions which have relatively little annual rainfall.
Springs are driven out onto the surface by various natural forces, such as gravity and hydrostatic pressure. A spring produced by the emergence of geothermally heated groundwater is known as a hot spring. The yield of spring water varies widely from a volumetric flow rate of nearly zero to more than for the biggest springs.
Formation
Springs are formed when groundwater flows onto the surface. This typically happens when the water table reaches above the surface level, or if the terrain depresses sharply. Springs may also be formed as a result of karst topography,[aquifers or volcanic activity. Springs have also been observed on the ocean floor, spewing warmer, low-salinity water directly into the ocean.
Springs formed as a result of karst topography create karst springs, in which ground water travels through a network of cracks and fissures—openings ranging from intergranular spaces to large caves, later emerging in a spring.
The forcing of the spring to the surface can be the result of a confined aquifer in which the recharge area of the spring water table rests at a higher elevation than that of the outlet. Spring water forced to the surface by elevated sources are artesian wells. This is possible even if the outlet is in the form of a cave. In this case the cave is used like a hose by the higher elevated recharge area of groundwater to exit through the lower elevation opening.
Non-artesian springs may simply flow from a higher elevation through the earth to a lower elevation and exit in the form of a spring, using the ground like a drainage pipe. Still other springs are the result of pressure from an underground source in the earth, in the form of volcanic or magma activity. The result can be water at elevated temperature and pressure, i.e. hot springs and geysers.
The action of the groundwater continually dissolves permeable bedrock such as limestone and dolomite, creating vast cave systems.
Types | Spring (hydrology) | Wikipedia | 467 | 316612 | https://en.wikipedia.org/wiki/Spring%20%28hydrology%29 | Physical sciences | Hydrology | null |
Depression springs occur along a depression, such as the bottom of alluvial valleys, basins, or valleys made of highly permeable materials.
Contact springs, which occur along the side of a hill or mountain, are created when the groundwater is underlaid by an impermeable layer of rock or soil known as an aquiclude or aquifuge
Fracture, or joint occur when groundwater running along an impermeable layer of rock meets a crack (fracture) or joint in the rock.
Tubular springs occur when groundwater flows from circular fissures such as those found in caverns (solution tubular springs) or lava tubular springs found in lava tube caves.
Artesian springs typically occur at the lowest point in a given area. An artesian spring is created when the pressure for the groundwater becomes greater than the pressure from the atmosphere. In this case the water is pushed straight up out of the ground.
Wonky holes are freshwater submarine exit points for coral and sediment-covered, sediment-filled old river channels.
Karst springs occur as outflows of groundwater that are part of a karst hydrological system.
Thermal springs are heated by geothermal activity; they have a water temperature significantly higher than the mean air temperature of the surrounding area. Geysers are a type of hot spring where steam is created underground by trapped superheated groundwater resulting in recurring eruptions of hot water and steam.
Carbonated springs, such as Soda Springs Geyser, are springs that emit naturally occurring carbonated water, due to dissolved carbon dioxide in the water content. They are sometimes called boiling springs or bubbling springs.
"Gushette springs pour from cliff faces"
Helocrene springs are diffuse that sustain marshlands with groundwater.
Flow | Spring (hydrology) | Wikipedia | 352 | 316612 | https://en.wikipedia.org/wiki/Spring%20%28hydrology%29 | Physical sciences | Hydrology | null |
Spring discharge, or resurgence, is determined by the spring's recharge basin. Factors that affect the recharge include the size of the area in which groundwater is captured, the amount of precipitation, the size of capture points, and the size of the spring outlet. Water may leak into the underground system from many sources including permeable earth, sinkholes, and losing streams. In some cases entire creeks seemingly disappear as the water sinks into the ground via the stream bed. Grand Gulf State Park in Missouri is an example of an entire creek vanishing into the groundwater system. The water emerges away, forming some of the discharge of Mammoth Spring in Arkansas. Human activity may also affect a spring's discharge—withdrawal of groundwater reduces the water pressure in an aquifer, decreasing the volume of flow.
Classification
Springs fall into three general classifications: perennial (springs that flow constantly during the year); intermittent (temporary springs that are active after rainfall, or during certain seasonal changes); and periodic (as in geysers that vent and erupt at regular or irregular intervals).
Springs are often classified by the volume of the water they discharge. The largest springs are called "first-magnitude", defined as springs that discharge water at a rate of at least 2800 liters or of water per second. Some locations contain many first-magnitude springs, such as Florida where there are at least 27 known to be that size; the Missouri and Arkansas Ozarks, which contain 10 known of first-magnitude; and 11 more in the Thousand Springs area along the Snake River in Idaho. The scale for spring flow is as follows:
Water content | Spring (hydrology) | Wikipedia | 332 | 316612 | https://en.wikipedia.org/wiki/Spring%20%28hydrology%29 | Physical sciences | Hydrology | null |
Minerals become dissolved in the water as it moves through the underground rocks. This mineral content is measured as total dissolved solids (TDS). This may give the water flavor and even carbon dioxide bubbles, depending on the nature of the geology through which it passes. This is why spring water is often bottled and sold as mineral water, although the term is often the subject of deceptive advertising. Mineral water contains no less than 250 parts per million (ppm) of tds. Springs that contain significant amounts of minerals are sometimes called 'mineral springs'. (Springs without such mineral content, meanwhile, are sometimes distinguished as 'sweet springs'.) Springs that contain large amounts of dissolved sodium salts, mostly sodium carbonate, are called 'soda springs'. Many resorts have developed around mineral springs and are known as spa towns. Mineral springs are alleged to have healing properties. Soaking in them is said to result in the absorption of the minerals from the water. Some springs contain arsenic levels that exceed the 10 ppb World Health Organization (WHO) standard for drinking water. Where such springs feed rivers they can also raise the arsenic levels in the rivers above WHO limits.
Water from springs is usually clear. However, some springs may be colored by the minerals that are dissolved in the water. For instance, water heavy with iron or tannins will have an orange color.
In parts of the United States a stream carrying the outflow of a spring to a nearby primary stream may be called a spring branch, spring creek, or run. Groundwater tends to maintain a relatively long-term average temperature of its aquifer; so flow from a spring may be cooler than other sources on a summer day, but remain unfrozen in the winter. The cool water of a spring and its branch may harbor species such as certain trout that are otherwise ill-suited to a warmer local climate.
Types of mineral springs
Sulfur springs contain a high level of dissolved sulfur or hydrogen sulfide in the water. Historically they have been used to alleviate the symptoms of arthritis and other inflammatory diseases.
Borax springs
Gypsum springs
Saline springs
Iron springs (chalybeate spring)
Radium springs (or radioactive springs) have a detectable level of radiation produced by the natural radioactive decay process
Uses | Spring (hydrology) | Wikipedia | 456 | 316612 | https://en.wikipedia.org/wiki/Spring%20%28hydrology%29 | Physical sciences | Hydrology | null |
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