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Gun Chronograph
A ballistic chronograph or gun chronograph is a measuring instrument used to measure the velocity of a projectile in flight, typically fired from a gun or other firearm. The instrument is often useful for tasks such as gauging the utility of a firearm or safety of less-lethal projectiles fired from items such as a paintball gun or BB gun. History Benjamin Robins (1707–1751) invented the ballistic pendulum that measures the momentum of the projectile fired by a gun. Dividing the momentum by the projectile mass gives the velocity. Robbins published his results as ''New Principles of Gunnery'' in 1742. The ballistic pendulum could make only one measurement per firing because the device catches the projectile. The gun's accuracy also limited how far down range a measurement could be made. Alessandro Vittorio Papacino d'Antoni published results in 1765 using a wheel chronometer. This used a horizontal spinning wheel with a vertical paper mounted on the rim. The bullet was fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measuring Instrument
Instrumentation is a collective term for measuring instruments, used for indicating, measuring, and recording physical quantities. It is also a field of study about the art and science about making measurement instruments, involving the related areas of metrology, automation, and control theory. The term has its origins in the art and science of scientific instrument-making. Instrumentation can refer to devices as simple as direct-reading thermometers, or as complex as multi- sensor components of industrial control systems. Instruments can be found in laboratories, refineries, factories and vehicles, as well as in everyday household use (e.g., smoke detectors and thermostats). Measurement parameters Instrumentation is used to measure many parameters (physical values), including: *Pressure, either differential or static * Flow *Temperature * Levels of liquids, etc. *Moisture or humidity *Density *Viscosity * ionising radiation * Frequency * Current *Voltage * Induct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Francis Bashforth
Francis Bashforth (8 January 1819 – 12 February 1912) was an English Anglican priest and mathematician, who is known for his use of applied mathematics on ballistics. Early life and education Bashforth was born on 8 January 1819 in Thurnscoe, Yorkshire, England. Bashforth was the eldest son of John Bashforth, a farmer. He was educated at Doncaster Grammar School. In 1839, he matriculated into St John's College, Cambridge as a sizar. Having studied the Mathematical Tripos at the University of Cambridge, he graduated with a Bachelor of Arts (BA) degree in 1843 and was the Second Wrangler. Bashforth later returned to his alma-mater to undertake a Bachelor of Divinity (BD) degree, which he completed in 1853. Career Bashforth was elected a Fellow of St John's College, Cambridge in 1843. Bashforth was ordained in the Church of England as a deacon in 1850 and as a priest in 1851. From 1857 until 1908, he was the Rector of Minting in Lincolnshire, the living of which belonged to h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horology
Chronometry or horology () is the science studying the measurement of time and timekeeping. Chronometry enables the establishment of standard measurements of time, which have applications in a broad range of social and scientific areas. ''Horology'' usually refers specifically to the study of mechanical timekeeping devices, while ''chronometry'' is broader in scope, also including biological behaviours with respect to time (biochronometry), as well as the dating of geological material (geochronometry). Horology is commonly used specifically with reference to the mechanical instruments created to keep time: clocks, watches, clockwork, sundials, hourglasses, Water clock, clepsydras, timers, time recorders, marine chronometers, and atomic clocks are all examples of Measuring instrument, instruments used to measure time. People interested in horology are called ''horologists''. That term is used both by people who deal professionally with timekeeping apparatuses, as well as enthus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aberdeen Chronograph
The Aberdeen chronograph was the first portable gun chronograph, an instrument for measuring the muzzle velocity and striking power of a projectile fired by a gun. It was invented in 1918 by Alfred Lee Loomis at the U.S. Army's Aberdeen Proving Ground. The method prevalent at the time was the Boulengé chronograph, which relied on the projectile passing through two wire screens. Breaking the first screen would release a rod held by electromagnets. While the rod was free-falling, breaking the second screen would activate a knife that marked the rod. Loomis' chronograph had a drum rotating at constant speed with a tape spooled inside. The projectile would pass through two screens, breaking the insulation between metal plates and creating a short circuit A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Doppler Radar
A Doppler radar is a specialized radar that uses the Doppler effect to produce velocity data about objects at a distance. It does this by bouncing a microwave signal off a desired target and analyzing how the object's motion has altered the frequency of the returned signal. This variation gives direct and highly accurate measurements of the radial component of a target's velocity relative to the radar. The term applies to radar systems in many domains like aviation, police radar detectors, navigation, meteorology, etc. Concept Doppler effect The Doppler effect (or Doppler shift), named after Austrian physicist Christian Doppler who proposed it in 1842, is the difference between the observed frequency and the emitted frequency of a wave for an observer moving relative to the source of the waves. It is commonly heard when a vehicle sounding a siren approaches, passes and recedes from an observer. The received frequency is higher (compared to the emitted frequency) during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photodetector
Photodetectors, also called photosensors, are devices that detect light or other forms of electromagnetic radiation and convert it into an electrical signal. They are essential in a wide range of applications, from digital imaging and optical communication to scientific research and industrial automation. Photodetectors can be classified by their mechanism of detection, such as the photoelectric effect, photochemical reactions, or thermal effects, or by performance metrics like spectral response. Common types include photodiodes, phototransistors, and photomultiplier tubes, each suited to specific uses. Solar cells, which convert light into electricity, are also a type of photodetector. This article explores the principles behind photodetectors, their various types, applications, and recent advancements in the field. History The development of photodetectors began with the discovery of the photoelectric effect by Heinrich Hertz in 1887, later explained by Albert Einst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capacitor
In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, a term still encountered in a few compound names, such as the '' condenser microphone''. It is a passive electronic component with two terminals. The utility of a capacitor depends on its capacitance. While some capacitance exists between any two electrical conductors in proximity in a circuit, a capacitor is a component designed specifically to add capacitance to some part of the circuit. The physical form and construction of practical capacitors vary widely and many types of capacitor are in common use. Most capacitors contain at least two electrical conductors, often in the form of metallic plates or surfaces separated by a dielectric medium. A conductor may be a foil, thin film, sintered bead of metal, or an electrolyte. The nonconductin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminum
Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has a great affinity towards oxygen, passivation (chemistry), forming a protective layer of aluminium oxide, oxide on the surface when exposed to air. It visually resembles silver, both in its color and in its great ability to reflect light. It is soft, magnetism, nonmagnetic, and ductility, ductile. It has one stable isotope, 27Al, which is highly abundant, making aluminium the abundance of the chemical elements, 12th-most abundant element in the universe. The radioactive decay, radioactivity of aluminium-26, 26Al leads to it being used in radiometric dating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypersonic
In aerodynamics, a hypersonic speed is one that exceeds five times the speed of sound, often stated as starting at speeds of Mach 5 and above. The precise Mach number at which a craft can be said to be flying at hypersonic speed varies, since individual physical changes in the airflow (like molecular dissociation and ionization) occur at different speeds; these effects collectively become important around Mach 5–10. The hypersonic regime can also be alternatively defined as speeds where specific heat capacity changes with the temperature of the flow as kinetic energy of the moving object is converted into heat. Characteristics of flow While the definition of hypersonic flow can be quite vague and is generally debatable (especially because of the absence of discontinuity between supersonic and hypersonic flows), a hypersonic flow may be characterized by certain physical phenomena that can no longer be analytically discounted as in supersonic flow. The peculiarities in hyperso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States's civil list of government space agencies, space program, aeronautics research and outer space, space research. National Aeronautics and Space Act, Established in 1958, it succeeded the National Advisory Committee for Aeronautics (NACA) to give the American space development effort a distinct civilian orientation, emphasizing peaceful applications in space science. It has since led most of America's space exploration programs, including Project Mercury, Project Gemini, the 1968–1972 Apollo program missions, the Skylab space station, and the Space Shuttle. Currently, NASA supports the International Space Station (ISS) along with the Commercial Crew Program and oversees the development of the Orion (spacecraft), Orion spacecraft and the Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Girl Gunners- The Work Of The Auxiliary Territorial Service At An Experimental Station, Shoeburyness, Essex, England, 1943 D12697
A girl is a young female human, usually a child or an adolescent. While the term ''girl'' has other meanings, including ''young woman'',Dictionary.com, "Girl"'' Retrieved January 2, 2008. ''daughter'' or ''girlfriend'' regardless of age, the first meaning is the most common one. The treatment and status of girls in any society is usually closely related to the status of women in that culture. In cultures where women have or had a low social position, girls may be unwanted by their parents, and society may invest less in girls. The difference in girls' and boys' upbringing ranges from slight to completely different. Mixing of the sexes may vary by age, and from totally mixed to total sex segregation. Etymology The English word ''girl'' first appeared during the Middle Ages between 1250 and 1300 CE and came from the Anglo-Saxon word ' (also spelled ' or '). The Anglo-Saxon word ' meaning ''dress'' or ''clothing item'' also seems to have been used as a metonym in some s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Military Academy, Woolwich
The Royal Military Academy (RMA) at Woolwich, in south-east London, was a British Army military academy for the training of Officer (armed forces), commissioned officers of the Royal Artillery and Royal Engineers. It later also trained officers of the Royal Corps of Signals and other technical corps. RMA Woolwich was commonly known as "The Shop" because its first building was a converted workshop of the Royal Arsenal, Woolwich Arsenal. History Origins in the Royal Arsenal An attempt had been made by the Board of Ordnance in 1720 to set up an academy within its Arsenal (then known as the Warren) to provide training and education for prospective officers of its new Royal Regiment of Artillery, Regiment of Artillery and Corps of Royal Engineers, Corps of Engineers (both of which had been established there in 1716). A new building was being constructed in readiness for the Academy and funds had been secured, seemingly, through investment in the South Sea Company; but the latter's col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
