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Topic Review
Modified Frequency Modulation
Modified Frequency Modulation, commonly MFM, is a run-length limited (RLL) coding scheme used to encode the actual data-bits on most floppy disks. It was first introduced in disk drives with the IBM 3330 hard disk drive in 1970. Floppy disk drive hardware examples include Amiga, most CP/M machines as well as IBM PC compatibles. MFM is a modification to the original digital FM (digital frequency modulation also known as delay coding) scheme for encoding data on single-density floppy disks and some early hard disk drives. Due to the minimum spacing between flux transitions that is a property of the disk, head and channel design, MFM, which guarantees at most one flux transition per data bit, can be written at higher density than FM, which can require two transitions per data bit. It is used with a data rate of 250–500 kbit/s (500–1000 kbit/s encoded) on industry standard 5¼-inch and 3½-inch ordinary and high density diskettes. MFM was also used in early hard disk designs, before the advent of more efficient types of run-length limited codes. Except for the steadily disappearing 360 KiB/1.2 MiB (5.25-inch) and 720~880 KiB/1.4~1.6 MiB (3.5-inch) floppy disk formats, MFM encoding is obsolete in magnetic recording.
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  • 22 Nov 2022
Topic Review
GM Y Platform
The Y platform, or Y body, designation has been used twice by the General Motors Corporation to describe a series of vehicles all built on the same basic body and sharing many parts and characteristics. The first was for a group of entry-level compacts including the conventional front-engine compacts built by GM divisions Buick, Oldsmobile and Pontiac from 1961 to 1963. The second, and current, incarnation is used for a high-end rear-wheel drive sports-car platform (chiefly that of the Chevrolet Corvette) from the 1980s through the 2000s.
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  • 22 Nov 2022
Topic Review
Weapons of the Cambodian–Vietnamese War
This article is about the weapons used in the Cambodian–Vietnamese War, involved the Vietnam (Army: People's Army of Vietnam (PAVN)), People's Republic of Kampuchea (Army: Kampuchean People's Revolutionary Armed Forces (KPRAF)) which of the Khmer Rouge (Army:Kampuchean Revolutionary Army), Khmer People's National Liberation Front (Army: Khmer People's National Liberation Armed Forces), FUNCINPEC and Thailand (Army: Royal Thai Armed Forces (Thai: กองทัพไทย; RTGS: Kong Thap Thai)) (border clashes) From Vietnam and People's Republic of Kampuchea supported by Soviet Union and other country socialist. From Khmer Rouge supported by China , Khmer People's National Liberation Front and FUNCINPEC supported by United States and United Kingdom
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Topic Review
Thin Film Lithium-Ion Battery
The thin film lithium-ion battery is a form of solid-state battery. Its development is motivated by the prospect of combining the advantages of solid-state batteries with the advantages of thin-film manufacturing processes. Thin-film construction could lead to improvements in specific energy, energy density, and power density on top of the gains from using a solid electrolyte. It allows for flexible cells only a few microns thick. It may also reduce manufacturing costs from scalable roll-to-roll processing and even allow for the use of cheap materials. thumb|right|Lithium Ion Battery
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Biography
George E. Waring Jr.
George E. Waring Jr. (July 4, 1833[1] – October 29, 1898) was an American sanitary engineer and civic reformer. He was an early American designer and advocate of sewer systems that keep domestic sewage separate from storm runoff. Waring was born in Pound Ridge, New York, the son of George E. Waring Sr., a wealthy stove manufacturer. Trained in agricultural chemistry, he began to lecture on
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Biography
Robert W. Farquhar
Robert Willard Farquhar (September 12, 1932 – October 18, 2015) was an American mission design specialist who worked for NASA. He designed halo orbits and was involved in a number of spaceflight missions. Robert Farquhar was born Robert Greener on September 12, 1932 in Chicago , Illinois. His father left when he was six weeks old and his mother remarried when he was thirteen years old, marr
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  • 22 Nov 2022
Biography
Ellison Onizuka
Ellison Shoji Onizuka (鬼塚 承次, Onizuka Shōji, June 24, 1946 – January 28, 1986) was an American astronaut from Kealakekua, Hawaii, who successfully flew into space with the Space Shuttle Discovery on STS-51-C. He died in the destruction of the Space Shuttle Challenger, on which he was serving as Mission Specialist for mission STS-51-L. He was the first Asian American and the first per
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Topic Review
Lunar Orbital Platform-Gateway
The Lunar Orbital Platform-Gateway (LOP-G) is a planned lunar-orbit space station that will serve as an all-in-one solar-powered communications hub, science laboratory, short-term habitation module, and holding area for rovers and other robots. The science disciplines to be studied on the Gateway are expected to include planetary science, astrophysics, Earth observations, heliophysics, fundamental space biology and human health and performance. The Gateway is designed to be developed, serviced, and utilized in collaboration with commercial and international partners. It will also serve as the staging point for crewed and robotic lunar exploration and a staging point for NASA's proposed Deep Space Transport craft to perform a 300-400 day shakedown mission prior to NASA's first crewed Mars mission. Deep Space Transport is a concept of a reusable vehicle that uses electric and chemical propulsion and would be specifically designed for crewed missions to destinations such as Mars. The development is led by the International Space Station partners: ESA, NASA, Roscosmos, JAXA and CSA for construction in the 2020s. The International Space Exploration Coordination Group (ISECG), which comprises 14 space agencies participating with NASA, have concluded that LOP-G will be critical in expanding human presence to the Moon, Mars and deeper into the solar system. Formerly known as the Deep Space Gateway, the station was renamed in NASA's proposal for the 2019 United States federal budget. The omnibus spending bill passed by Congress in March of 2018 provided NASA with $504 million for the development of LOP-G in fiscal year 2019.
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Topic Review
Xiaomi Smart Home
Xiaomi Smart Home Products (also known as Mi Ecosystem products) are products released by third-party manufacturers who have partnered with Xiaomi. These products are managed by Mi Home app.
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Topic Review
Propellant Depot
An orbital propellant depot is a cache of propellant that is placed in orbit around Earth or another body to allow spacecraft or the transfer stage of the spacecraft to be fueled in space. It is one of the types of space resource depots that have been proposed for enabling infrastructure-based space exploration. Many different depot concepts exist depending on the type of fuel to be supplied, location, or type of depot which may also include a propellant tanker that delivers a single load to a spacecraft at a specified orbital location and then departs. In-space fuel depots are not necessarily located near or at a space station. Potential users of in-orbit refueling and storage facilities include space agencies, defense ministries and communications satellite or other commercial companies. Satellite servicing depots would extend the lifetime of satellites that have nearly consumed all of their orbital maneuvering fuel and are likely placed in a geosynchronous orbit. The spacecraft would conduct a space rendezvous with the depot, or vice versa, and then transfer propellant to be used for subsequent orbital maneuvers. In 2011, Intelsat showed interest in an initial demonstration mission to refuel several satellites in geosynchronous orbit, but all plans have been since scrapped. A low earth orbit (LEO) depot's primary function would be to provide propellant to a transfer stage headed to the moon, Mars, or possibly a geosynchronous orbit. Since all or a fraction of the transfer stage propellant can be off-loaded, the separately launched spacecraft with payload and/or crew could have a larger mass or use a smaller launch vehicle. With a LEO depot or tanker fill, the size of the launch vehicle can be reduced and the flight rate increased—or, with a newer mission architecture where the beyond-Earth-orbit spacecraft also serves as the second stage, can facilitate much larger payloads—which may reduce the total launch costs since the fixed costs are spread over more flights and fixed costs are usually lower with smaller launch vehicles. A depot could also be placed at Earth-Moon Lagrange point 1 (EML-1) or behind the Moon at EML-2 to reduce costs to travel to the moon or Mars. Placing a depot in Mars orbit has also been suggested.
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