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Topic Review
Gel Ball Shooter
Gel blasters, also known as gel guns, gel shooters, gel markers, hydro markers, hydro blasters, water bead blasters or gelsoft, are toy guns similar in design to airsoft guns, but the projectiles they shoot are 6–8 mm (0.24–0.31 in) superabsorbent polymer water beads (most commonly sodium polyacrylate, colloquially called water beads, hydrogel balls, gel balls, water bullets or simply gels), which are often sold commercially as moisture retainers for gardening and pot/vase floriculture. Gel blasters are often played in CQB-style shooting skirmishes similar to paintball by squads or local clubs of enthusiasts often referred to as "gelballers", but follows an airsoft-like honor-based gameplay umpiring system. MilSim games involving players wearing camouflage and dump pouches are very popular, while "SpeedGel" players are more casual with team jerseys and often wear paintball masks. In addition to safety gear such as eye protections, the sport is heavily regulated on the field and players must adhere to safety rules.
  • 444
  • 02 Dec 2022
Topic Review
M9 Armored Combat Earthmover
The M9 Armored Combat Earthmover (ACE) is a highly mobile armored tracked vehicle that provides combat engineer support to front-line forces. Fielded by the United States Army, its tasks include eliminating enemy obstacles, maintenance and repair of roads and supply routes, and construction of fighting positions.
  • 695
  • 02 Dec 2022
Topic Review
Cathode Ray Tube
The cathode ray tube (CRT) is a vacuum tube that contains one or more electron guns and a phosphorescent screen, and is used to display images. It modulates, accelerates, and deflects electron beam(s) onto the screen to create the images. The images may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets, or other phenomena. CRTs have also been used as memory devices, in which case the visible light emitted from the fluorescent material (if any) is not intended to have significant meaning to a visual observer (though the visible pattern on the tube face may cryptically represent the stored data). In television sets and computer monitors, the entire front area of the tube is scanned repetitively and systematically in a fixed pattern called a raster. An image is produced by controlling the intensity of each of the three electron beams, one for each additive primary color (red, green, and blue) with a video signal as a reference. In all modern CRT monitors and televisions, the beams are bent by magnetic deflection, a varying magnetic field generated by coils and driven by electronic circuits around the neck of the tube, although electrostatic deflection is commonly used in oscilloscopes, a type of electronic test instrument. A CRT is constructed from a glass envelope which is large, deep (i.e., long from front screen face to rear end), fairly heavy, and relatively fragile. The interior of a CRT is evacuated to approximately 0.01 pascals (9.9×10−8 atm) to 133 nanopascals (1.31×10−12 atm), evacuation being necessary to facilitate the free flight of electrons from the gun(s) to the tube's face. The fact that it is evacuated makes handling an intact CRT potentially dangerous due to the risk of breaking the tube and causing a violent implosion that can hurl shards of glass at great velocity. As a matter of safety, the face is typically made of thick lead glass so as to be highly shatter-resistant and to block most X-ray emissions, particularly if the CRT is used in a consumer product. Since the late 2000s, CRTs have been largely superseded by newer "flat panel" display technologies such as LCD, plasma display, and especially OLED displays, which in the case of LCD and OLED displays have lower manufacturing costs and power consumption, as well as significantly less weight and bulk. Flat panel displays can also be made in very large sizes; whereas 38 to 40 in (97 to 102 cm) was about the largest size of a CRT television, flat panels are available in 60 in (150 cm) and larger sizes.
  • 3.6K
  • 02 Dec 2022
Topic Review
Application of Two-Dimensional Materials towards CMOS-Integrated Gas Sensors
The semiconductor metal oxide (SMO)-based gas sensor, considered the current workhorse of semiconductor-based chemiresistive gas sensor technologies, requires high temperatures to initiate the surface reactions which result in the sensing response, making it difficult to fabricate and prone to high mechanical instability. Therefore, alternatives at lower temperatures are desired, where 2D materials seem to hold the most promise. Even at ambient temperature, their sensitivity is extraordinarily large due to their extremely high surface-to-volume ratio. However, some ongoing issues still need to be resolved before gas sensors based on 2D materials can be widely used and commercialized. The alternative room temperature solutions involve optical signals, either by designing an nondispersive infrared (NDIR) sensor based on the Beer-Lambert law or by introducing an additional UV illumination to SMO sensors. In both cases, complementary metal oxide semiconductor (CMOS) integration is not feasible, which is why continued interest in 2D-material-based gas sensors persists.
  • 1.1K
  • 02 Dec 2022
Topic Review
Examination of Apollo Moon Photographs
The examination of Apollo Moon photographs is an endeavour undertaken by certain people engaged in the debate as to the merits of Moon landing conspiracy theories, despite the abundance of third-party evidence for Apollo Moon landings. A number of allegations and refutations with a variable degree of notability are put forward due to this examination.
  • 4.5K
  • 02 Dec 2022
Topic Review
Guitarrón Chileno
The Guitarrón Chileno (literally: "large Chilean guitar") is a guitar-shaped plucked string instrument from Chile , with 25 or 24 (rarely) strings. Its primary contemporary use is as the instrumental accompaniment for the traditional Chilean genre of singing poetry known as Canto a lo Poeta, though a few virtuosi have also begun to develop the instrument's solo possibilities.
  • 707
  • 02 Dec 2022
Topic Review
Split-Single
The split-single (Doppelkolbenmotor to its German and Austrian manufacturers), is a variant on the two-stroke engine with two cylinders sharing a single combustion chamber.
  • 1.1K
  • 02 Dec 2022
Topic Review
Mobile Phone Tracking
Mobile phone tracking is a process for identifying the location of a mobile phone, whether stationary or moving. Localization may be effected by a number of technologies, such as using multilateration of radio signals between (several) cell towers of the network and the phone, or simply using GPS. To locate a mobile phone using multilateration of radio signals, it must emit at least the idle signal to contact the next nearby antenna tower, but the process does not require an active call. The Global System for Mobile Communications (GSM) is based on the phone's signal strength to nearby antenna masts. Mobile positioning may include location-based services that disclose the actual coordinates of a mobile phone, which is a technology used by telecommunication companies to approximate the location of a mobile phone, and thereby also its user.
  • 914
  • 02 Dec 2022
Topic Review
Live, Virtual, and Constructive
Live, Virtual, & Constructive (LVC) Simulation is a broadly used taxonomy for classifying Models and Simulation (M&S). However, categorizing a simulation as a live, virtual, or constructive environment is problematic since there is no clear division between these categories. The degree of human participation in a simulation is infinitely variable, as is the degree of equipment realism. The categorization of simulations also lacks a category for simulated people working real equipment.
  • 642
  • 02 Dec 2022
Topic Review
MV Penguin II
MV Penguin II was an American refrigerated cargo ship in commission in the fleet of the United States Fish and Wildlife Service from 1950 to 1963. She ran a cargo service between Seattle, Washington (state) , and the Pribilof Islands, and also delivered provisions to Aleut communities on the Alaska Peninsula and in the Aleutian Islands. Prior to her fisheries service, she was the United States Army cargo ship U.S. Army Lt. Raymond Zussman (FS-246).
  • 428
  • 02 Dec 2022
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