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Topic Review
Distance Measuring Equipment (Aviation)
In aviation, distance measuring equipment (DME) is a radio navigation technology that measures the slant range (distance) between an aircraft and a ground station by timing the propagation delay of radio signals in the frequency band between 960 and 1215 megahertz (MHz). Line-of-visibility between the aircraft and ground station is required. An interrogator (airborne) initiates an exchange by transmitting a pulse pair, on an assigned 'channel', to the transponder ground station. The channel assignment specifies the carrier frequency and the spacing between the pulses. After a known delay, the transponder replies by transmitting a pulse pair on a frequency that is offset from the interrogation frequency by 63 MHz and having specified separation. DME systems are used worldwide, using standards set by the International Civil Aviation Organization (ICAO), RTCA, the European Union Aviation Safety Agency (EASA) and other bodies. Some countries require that aircraft operating under instrument flight rules (IFR) be equipped with a DME interrogator; in others, a DME interrogator is only required for conducting certain operations. While stand-alone DME transponders are permitted, DME transponders are usually paired with an azimuth guidance system to provide aircraft with a two-dimensional navigation capability. A common combination is a DME colocated with a VHF omnidirectional range (VOR) transmitter in a single ground station. When this occurs, the frequencies of the VOR and DME equipment are paired. Such a configuration enables an aircraft to determine its azimuth angle and distance from the station. A VORTAC (a VOR co-located with a TACAN) installation provides the same capabilities to civil aircraft but also provides 2-D navigation capabilities to military aircraft. Low-power DME transponders are also associated with some instrument landing system (ILS), ILS localizer and microwave landing system (MLS) installations. In those situations, the DME transponder frequency/pulse spacing is also paired with the ILS, LOC or MLS frequency. ICAO characterizes DME transmissions as ultra high frequency (UHF). The term L-band is also used. Developed in Australia, DME was invented by James "Gerry" Gerrand under the supervision of Edward George "Taffy" Bowen while employed as Chief of the Division of Radiophysics of the Commonwealth Scientific and Industrial Research Organisation (CSIRO). Another engineered version of the system was deployed by Amalgamated Wireless Australasia Limited in the early 1950s operating in the 200 MHz VHF band. This Australian domestic version was referred to by the Federal Department of Civil Aviation as DME(D) (or DME Domestic), and the later international version adopted by ICAO as DME(I). DME is similar in principle to secondary radar ranging function, except the roles of the equipment in the aircraft and on the ground are reversed. DME was a post-war development based on the identification friend or foe (IFF) systems of World War II. To maintain compatibility, DME is functionally identical to the distance measuring component of TACAN.
  • 651
  • 14 Oct 2022
Biography
Walt Havenstein
Walter Perry "Walt" Havenstein (born April 24, 1949)[1] is an American businessman, engineer, and former United States Marine. He was the Republican nominee for Governor of New Hampshire in 2014. Havenstein is the son of Kathryn McKay (Creech) and Paul Lieder Havenstein, CDR, USN.[2][3][4] He graduated from the United States Naval Academy with a bachelor's degree in aerospace engineering and
  • 651
  • 29 Dec 2022
Biography
David E. Muller
David Eugene Muller (November 2, 1924 – April 27, 2008) was an American mathematician and computer scientist. He was a professor of mathematics and computer science at the University of Illinois (1953–92), when he became an emeritus professor, and was an adjunct professor of mathematics at the New Mexico State University (1995-2008). Muller received his BS in 1947 and his PhD in 1951 in phys
  • 650
  • 12 Dec 2022
Biography
Antônio Luz Furtado
Antonio Luz Furtado (born 1934) is a Brazilian computer scientist and Professor of Computer Science known for his work in databases and conceptual modeling. Furtado received undergrad degrees in Economics from Universidade do Estado do Rio de Janeiro (1964) and Law from Universidade Federal do Rio de Janeiro (1957), a M.Sc. in Computer Science from PUC-Rio (1969), a M.A. in Business Administr
  • 648
  • 13 Dec 2022
Topic Review
Watch System
A watch system, watch schedule, or watch bill is a method of assigning regular periods of work duty aboard ships and some other areas of employment. A watch system allows the ship's crew to operate the ship 24 hours a day for the duration of long voyages or operations. Many watch systems incorporate the concept of dogging, whereby one watch is split into two shorter watches so that there is an odd number each day. Doing so allows crew members to have a different watch schedule each day. Often, the dog watches are set at dinner time to allow the entire crew to be fed in short order.
  • 647
  • 12 Oct 2022
Topic Review
List of Gliders (K)
This is a list of gliders/sailplanes of the world, (this reference lists all gliders with references, where available) Note: Any aircraft can glide for a short time, but gliders are designed to glide for longer.
  • 646
  • 29 Sep 2022
Topic Review
Arms Control
Arms control is a term for international restrictions upon the development, production, stockpiling, proliferation and usage of small arms, conventional weapons, and weapons of mass destruction. Arms control is typically exercised through the use of diplomacy which seeks to impose such limitations upon consenting participants through international treaties and agreements, although it may also comprise efforts by a nation or group of nations to enforce limitations upon a non-consenting country.
  • 645
  • 25 Nov 2022
Topic Review
Gun Carrier Mark I
The Gun Carrier Mark I was the first piece of self-propelled artillery ever to be produced, a British development from the First World War. Gun carriers were first used in the Battle of Pilckem Ridge (31 July – 2 August 1917) during the Third Battle of Ypres (31 July – 10 November 1917).
  • 643
  • 21 Nov 2022
Topic Review
List of Gliders (G)
This is a list of gliders/sailplanes of the world, (this reference lists all gliders with references, where available) Note: Any aircraft can glide for a short time, but gliders are designed to glide for longer.
  • 642
  • 09 Oct 2022
Biography
Peter L. Jensen
Peter Laurits Jensen (16 May 1886 – 26 October 1961) was a Danish American engineer, inventor and entrepreneur. He founded Magnavox Company and Jensen Radio Manufacturing Company. Peter Laurits Jensen was born on the island of Falster in Denmark during 1886. His education was in Danish high schools from which he graduated in 1902. He attended Amherst College in Massachusetts and graduated w
  • 641
  • 27 Dec 2022
Topic Review
Epson HX-20
The Epson HX-20 (also known as the HC-20) was the first "true" laptop computer. It was invented in July 1980 by Yukio Yokozawa, who worked for Suwa Seikosha, a branch of Japanese company Seiko (now Seiko Epson), receiving a patent for the invention. It was announced in 1981 as the HC-20 in Japan, and was introduced by Epson in North America as the HX-20 at the 1981 COMDEX computer show in Las Vegas, where it drew significant attention for its portability. It had a mass-market release in July 1982, as the HC-20 in Japan and as the Epson HX-20 in North America. The size of an A4 notebook and weighing 1.6 kg, it was hailed by BusinessWeek magazine as the "fourth revolution in personal computing".
  • 640
  • 25 Oct 2022
Topic Review
Fiber Optic Sensor
A fiber optic sensor is a sensor that uses optical fiber either as the sensing element ("intrinsic sensors"), or as a means of relaying signals from a remote sensor to the electronics that process the signals ("extrinsic sensors"). Fibers have many uses in remote sensing. Depending on the application, fiber may be used because of its small size, or because no electrical power is needed at the remote location, or because many sensors can be multiplexed along the length of a fiber by using light wavelength shift for each sensor, or by sensing the time delay as light passes along the fiber through each sensor. Time delay can be determined using a device such as an optical time-domain reflectometer and wavelength shift can be calculated using an instrument implementing optical frequency domain reflectometry. Fiber optic sensors are also immune to electromagnetic interference, and do not conduct electricity so they can be used in places where there is high voltage electricity or flammable material such as jet fuel. Fiber optic sensors can be designed to withstand high temperatures as well.
  • 640
  • 17 Nov 2022
Topic Review
Chirality (Electromagnetism)
300px|thumb|The direction of current flow and induced magnetic flux follow a "handness" relationship The term chiral /ˈkaɪrəl/ describes an object, especially a molecule, which has or produces a non-superposable mirror image of itself. In chemistry, such a molecule is called an enantiomer or is said to exhibit chirality or enantiomerism. The term "chiral" comes from the Greek word for the human hand, which itself exhibits such non-superimposeability of the left hand precisely over the right. Due to the opposition of the fingers and thumbs, no matter how the two hands are oriented, it is impossible for both hands to exactly coincide. Helices, chiral characteristics (properties), chiral media, order, and symmetry all relate to the concept of left- and right-handedness.
  • 640
  • 01 Dec 2022
Biography
Mikhail Ageyev
Mikhail Dmitriyevich Ageyev (Russian: Михаил Дмитриевич Агеев; 14 May 1931 in Cheremhovo (now Irkutsk Oblast) – 19 November 2005) was a Soviet and Russian scientist, an expert in the field of navigation and control systems of moving objects, a member of the Russian Academy of Sciences (1992).[1][2] Ageyev was born on 14 May 1931 in Cheremhovo, a town of Irkutsk Oblast,
  • 639
  • 13 Dec 2022
Biography
Benjamin Allen Goldman
Benjamin A. Goldman (also known as Benjamin Allen Goldman, Ben Goldman) is an entrepreneur, author, artist, and inventor from the USA. He was an advisor to the Clinton Administration, serving as a Charter Member of the National Environmental Justice Advisory Council (1994-1995), a committee member of the President's Council on Sustainable Development(1994-1995).[1][2][3][4] Goldman was born t
  • 639
  • 12 Dec 2022
Biography
Russell W. Porter
Russell Williams Porter (December 13, 1871 – February 22, 1949) was an United States artist, engineer, amateur astronomer and Arctic explorer.[1] He was a pioneer in the field of “cutaway illustration"[2] and is sometimes referred to as the "founder"[3][4] or one of the "founders" of amateur telescope making."[5] Russell W. Porter, the youngest of five children, was born in 1871 Springfie
  • 638
  • 19 Dec 2022
Topic Review
Optical PAyload for Lasercomm Science
Optical Payload for Lasercomm Science (OPALS) is a spacecraft communication instrument developed at the Jet Propulsion Laboratory that was tested on the International Space Station (ISS) from 18 April 2014 to 17 July 2014 to demonstrate the technology for laser communications systems between spacecraft and ground stations. The purpose of OPALS is to do research into replacing traditional radio-frequency (RF) communications which are currently used on spacecraft. This will allow spacecraft to increase the rate at which data is downlinked by 10 to 100 times. It also will have less error than RF communication. It launched from Cape Canaveral Air Force Station to the ISS on 18 April 2014 on a Falcon 9 SpaceX CRS-3 Dragon capsule resupply. The experiment used commercial products rather than space qualified components.
  • 637
  • 08 Nov 2022
Biography
James O. Clephane
James Ogilvie Clephane (February 21, 1842[1] – November 30, 1910[2]) was an American inventor, bar-admitted court reporter and venture capitalist in Washington, D.C. and New York City . He was involved in improving, promoting and supporting several inventions during the Gilded Age, including the typewriter, the graphophone, and the linotype machine. He has been called the "father of the linoty
  • 633
  • 16 Dec 2022
Topic Review
Maritime Express
The Maritime Express was a Canada passenger train. When it was launched on the first of March, 1898, it was the flagship of the Intercolonial Railway (ICR) between Halifax, Nova Scotia and Montreal , Quebec. The train was operated by the Canadian National Railway (CNR) from 1919 until 1964, when it was reduced to a regional service and its name retired.
  • 628
  • 18 Nov 2022
Topic Review
Field-emission Display
A field-emission display (FED) is a flat panel display technology that uses large-area field electron emission sources to provide electrons that strike colored phosphor to produce a color image. In a general sense, an FED consists of a matrix of cathode ray tubes, each tube producing a single sub-pixel, grouped in threes to form red-green-blue (RGB) pixels. FEDs combine the advantages of CRTs, namely their high contrast levels and very fast response times, with the packaging advantages of LCD and other flat-panel technologies. They also offer the possibility of requiring less power, about half that of an LCD system. Sony was the major proponent of the FED design and put considerable research and development effort into the system during the 2000s, planning mass production in 2009. Sony's FED efforts started winding down in 2009, as LCD became the dominant flat-panel technology. In January 2010, AU Optronics announced that it acquired essential FED assets from Sony and intends to continue development of the technology. (As of 2016), no large-scale commercial FED production has been undertaken. FEDs can also be made transparent. FEDs are closely related to another developing display technology, the surface-conduction electron-emitter display (SED), differing primarily in details of the electron-emission system.
  • 627
  • 02 Nov 2022
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