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Elliptical Trammel
An ellipsograph is a mechanism (engineering), mechanism that generates the shape of an ellipse. One common form of ellipsograph is known as the trammel of Archimedes. () It consists of two shuttles which are confined to perpendicular channels or rails and a rod which is attached to the shuttles by pivots at adjustable positions along the rod. As the shuttles move back and forth, each along its channel, all points on the rod move in elliptical paths. The motion of the rod is termed elliptical motion. The semi-axes ''a'' and ''b'' of the ellipses have lengths equal to the distances from the point on the rod to each of the two pivots. The straight lines described by the pivots are special cases of an ellipse, where the length of one axis is twice the distance between the pivots and that of the other is zero. All points on a circle with a diameter defined by the two pivots reciprocate in such straight lines. This circle corresponds to the smaller circle in a Tusi couple. The point ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distances
Distance is a numerical or occasionally qualitative measurement of how far apart objects, points, people, or ideas are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). The term is also frequently used metaphorically to mean a measurement of the amount of difference between two similar objects (such as statistical distance between probability distributions or edit distance between strings of text) or a degree of separation (as exemplified by distance between people in a social network). Most such notions of distance, both physical and metaphorical, are formalized in mathematics using the notion of a metric space. In the social sciences, distance can refer to a qualitative measurement of separation, such as social distance or psychological distance. Distances in physics and geometry The distance between physical locations can be defined in different ways in different contexts. Strai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanisms (engineering)
Mechanism may refer to: *Mechanism (economics), a set of Game form, rules for a game designed to achieve Social choice function, a certain outcome **Mechanism design, the study of such mechanisms *Mechanism (engineering), rigid bodies connected by joints in order to accomplish a desired force and/or motion transmission *Mechanism (biology), explaining how a feature is created *Mechanism (philosophy), a theory that all natural phenomena can be explained by physical causes *Mechanism (sociology), a theory that all social phenomena can be explained by the existence of a deterministic mechanism Arts, films, and music * "The Mechanism", song by Disclosure * "Mechanism", song by Front Line Assembly from ''WarMech'' * The Mechanism (TV series), ''The Mechanism'' (TV series), a Netflix TV series See also *Machine *Machine (mechanical) *Linkage (mechanical) *Mechanism of action, the means by which a drug exerts its biological effects *Defence mechanism, unconscious mechanisms aimed a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traditional Toys
A tradition is a system of beliefs or behaviors (folk custom) passed down within a group of people or society with symbolic meaning or special significance with origins in the past. A component of cultural expressions and folklore, common examples include holidays or impractical but socially meaningful clothes (like lawyers' wigs or military officers' spurs), but the idea has also been applied to social norms and behaviors such as greetings, etc. Traditions can persist and evolve for thousands of years— the word ''tradition'' itself derives from the Latin word ''tradere'' literally meaning to transmit, to hand over, to give for safekeeping. While it is reportedly assumed that traditions have an ancient history, many traditions have been invented on purpose, whether it be political or cultural, over short periods of time. Various academic disciplines also use the word in a variety of ways. The phrase "according to tradition" or "by tradition" usually means that what follows i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mathologer
Burkard Polster (born 26 February 1965 in Würzburg) is a German mathematician who runs and presents the ''Mathologer'' channel on YouTube. He is a professor of mathematics at Monash University in Melbourne, Australia. Education and career Polster earned a doctorate from the University of Erlangen–Nuremberg in 1993 under the supervision of Karl Strambach. Other universities that Polster has been affiliated with, before joining Monash University in 2000, include the University of Würzburg, University at Albany, University of Kiel, University of California, Berkeley, University of Canterbury, and University of Adelaide. Polster's research involves topics in geometry, recreational mathematics, and the mathematics of everyday life, including how to tie shoelaces Shoelaces, also called shoestrings (US English) or bootlaces (UK English), are a system commonly used to secure shoes, boots, and other footwear. They typically consist of a pair of strings or cords, one for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lego
Lego (, ; ; stylised as LEGO) is a line of plastic construction toys manufactured by the Lego Group, a privately held company based in Billund, Denmark. Lego consists of variously coloured interlocking plastic bricks made of acrylonitrile butadiene styrene (ABS) that accompany an array of gears, figurines called minifigures, and various other parts. Its pieces can be assembled and connected in many ways to construct objects, including vehicles, buildings, and working robots. Assembled Lego models can be taken apart, and their pieces can be reused to create new constructions. The Lego Group began manufacturing the interlocking toy bricks in 1949. Moulding is done in Denmark, Hungary, Mexico, and China. Brick decorations and packaging are done at plants in the former three countries and in the Czech Republic. Annual production of the bricks averages approximately 36 billion, or about 1140 elements per second. One of Europe's biggest companies, Lego is the largest to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scott Russell Linkage
A Scott Russell linkage is a linkage which translates linear motion through a right angle. The linkage is named after John Scott Russell (1808–1882), although watchmaker William Freemantle had already patented it in 1803. A different form of the linkage has been used in a front-wheel-drive vehicle with solid rear axle to control lateral movement, and with a flexing elastomeric connection instead of the rolling or sliding connection. The linkage does not share the disadvantages of the asymmetric Panhard rod, and is more compact than the Watt's linkage. Construction and related linkages The linkage is composed of two links. One link is double the size of the other, and is connected to the smaller link by its midpoint. One of the ends is then connected to something that can generate linear motion, such as a rolling or sliding connection, or another straight line mechanism A straight-line mechanism is a mechanism that converts any type of rotary or angular motio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Useless Machine
A useless machine or useless box is a device whose only function is to turn itself off. The best-known useless machines are those inspired by Marvin Minsky's design, in which the device's sole function is to switch itself off by operating its own "off" switch. Such machines were popularized commercially in the 1960s, sold as an amusing engineering hack, or as a joke. More elaborate devices and some novelty toys, which have an obvious entertainment function, have been based on these simple useless machines. History The Italian artist Bruno Munari began building "useless machines" (''macchine inutili'') in the 1930s. He was a "third generation" Futurist and did not share the first generation's boundless enthusiasm for technology but sought to counter the threats of a world under machine rule by building machines that were artistic and unproductive. The version of the useless machine that became famous in information theory (basically a box with a simple switch which, when turne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypotrochoid
In geometry, a hypotrochoid is a roulette (curve), roulette traced by a point attached to a circle of radius rolling around the inside of a fixed circle of radius , where the point is a distance from the center of the interior circle. The parametric equations for a hypotrochoid are: :\begin & x (\theta) = (R - r)\cos\theta + d\cos\left(\theta\right) \\ & y (\theta) = (R - r)\sin\theta - d\sin\left(\theta\right) \end where is the angle formed by the horizontal and the center of the rolling circle (these are not polar equations because is not the polar angle). When measured in radian, takes values from 0 to 2 \pi \times \tfrac (where is least common multiple). Special cases include the hypocycloid with and the ellipse with and . The eccentricity of the ellipse is :e=\frac becoming 1 when d=r (see Tusi couple). The classic Spirograph toy traces out hypotrochoid and epitrochoid curves. Hypotrochoids describe the support of the eigenvalues of some random matrices with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypocycloid
In geometry, a hypocycloid is a special plane curve generated by the trace of a fixed point on a small circle that rolls within a larger circle. As the radius of the larger circle is increased, the hypocycloid becomes more like the cycloid created by rolling a circle on a line. History The 2-cusped hypocycloid called Tusi couple was first described by the 13th-century Persian people, Persian Islamic astronomy, astronomer and Islamic mathematics, mathematician Nasir al-Din al-Tusi in ''Tahrir al-Majisti (Commentary on the Almagest)''. German painter and German Renaissance theorist Albrecht Dürer described epitrochoids in 1525, and later Roemer and Bernoulli concentrated on some specific hypocycloids, like the astroid, in 1674 and 1691, respectively. Properties If the rolling circle has radius , and the fixed circle has radius , then the parametric equations for the curve can be given by either: \begin & x (\theta) = (R - r) \cos \theta + r \cos \left(\frac \theta \right) \\ & ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Farey Jr
John Farey Jr. (20 March 1791 – 17 July 1851) was an English mechanical engineer, consulting engineer and patent attorney, known for his pioneering contributions in the field of mechanical engineering. Alec Skempton.Farey, Jr., John" in: ''A Biographical Dictionary of Civil Engineers in Great Britain and Ireland: 1500–1830.'' 2002. p. 223-224 As consulting engineer Farey worked for many well-known inventors of the later Industrial Revolution, and was a witness to a number of parliamentary enquiries, inquests and court cases, and on occasion acted as an arbitrator. He was polymathic in his interests and contributed text and drawings to a number of periodicals and encyclopaedias. Farey is also remembered as the first English inventor of the ellipsograph, an instrument used by draughtsmen to inscribe ellipses. Biography Youth and education Born 20 March 1791, in Lambeth, Farey was the eldest son of John Farey Sr. (1766–1826), the geologist, and Sophia Hubert (1770–18 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bourke Engine
The Bourke engine was an attempt by Russell Bourke in the 1920s to improve the two-stroke internal combustion engine. Despite finishing his design and building several working engines, the onset of World War II, lack of test results, and the poor health of his wife compounded to prevent his engine from ever coming successfully to market. The main claimed virtues of the design are that it has only two moving parts, is lightweight, has two power pulses per revolution, and does not need oil mixed into the fuel. The Bourke engine is a two-stroke design, with one horizontally opposed piston assembly using two pistons that move in the same direction at the same time, so that their operations are 180 degrees out of phase. The pistons are connected to a Scotch yoke mechanism in place of the more usual crankshaft mechanism, thus the piston acceleration is perfectly sinusoidal. This causes the pistons to spend more time at top dead center than conventional engines. The incoming charg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
