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Topic Review
TiO2
TiO2 probably plays the most important role in photocatalysis due to its excellent chemical and physical properties. However, the band gap of TiO2 corresponds to the Ultraviolet (UV) region, which is inactive under visible irradiation. At present, TiO2 has become activated in the visible light region by metal and nonmetal doping and the fabrication of composites. Recently, nano-TiO2 has attracted much attention due to its characteristics of larger specific surface area and more exposed surface active sites. nano-TiO2 has been obtained in many morphologies such as ultrathin nanosheets, nanotubes, and hollow nanospheres.
  • 2.3K
  • 29 Oct 2020
Topic Review
Ordnance QF 75 Mm
The Ordnance QF 75 mm, abbreviated to OQF 75 mm, was a British tank-gun of the Second World War. It was obtained by boring out the Ordnance QF 6 pounder ("6 pdr") 57-mm anti-tank gun to 75-mm, to give better performance against infantry targets in a similar fashion to the 75mm M3 gun fitted to the American Sherman tank. The QF came from "quick-firing", referring to the use of ammunition with the shell and propellant in a single cartridge. The gun was also sometimes known as ROQF from Royal Ordnance (the manufacturer) Quick-Firing.
  • 2.3K
  • 02 Nov 2022
Topic Review
Sound Attenuators
A sound attenuator, or duct silencer, sound trap, or muffler, is a noise control acoustical treatment of Heating Ventilating and Air-Conditioning (HVAC) ductwork designed to reduce transmission of noise through the ductwork, either from equipment into occupied spaces in a building, or between occupied spaces. In its simplest form, a sound attenuator consists of an baffle within the ductwork. These baffles often contain sound-absorbing materials. The physical dimensions and baffle configuration of sound attenuators are selected to attenuate a specific range of frequencies. Unlike conventional internally-lined ductwork, which is only effective at attenuating mid- and high-frequency noise, sound attenuators can achieve broader band attenuation in relatively short lengths. Certain types of sound attenuators are essentially a Helmholtz resonator used as a passive noise-control device.
  • 2.3K
  • 27 Oct 2022
Topic Review
EM-2 Rifle
The EM-2, also known as Rifle No.9 Mk1 or Janson rifle, was an experimental United Kingdom assault rifle. It was briefly adopted by British forces in 1951, but the decision was overturned very shortly thereafter by Winston Churchill's incoming government in an effort to secure NATO standardisation of small arms and ammunition. An innovative weapon with the compact bullpup layout and an optical sight, it used one of the early intermediate cartridges (a concept introduced by the Germans with the 7.92×33mm Kurz) as a result of combat experience and German advances in weapons design during World War II. It used the experimental, intermediate powered, but highly efficient .280 British round, which was designed to replace the venerable .303 round and Lee–Enfield rifle variants which had served since before the turn of the 20th century. The United States claimed the .280 British round was too weak for use in rifles and machine guns, and instead favored the much more powerful 7.62×51mm NATO round. As the EM-2 could not be easily adapted to the longer and more powerful round, it faded from use. However, the bullpup layout for a British service rifle was finally adopted some years later in form of the SA80 assault rifle, the EM-2's spiritual successor, which remains in service today.
  • 2.3K
  • 18 Nov 2022
Topic Review
Ghauri (Missile)
The Ghauri–I (Urdu: غوری-ا‎; official codename: Hatf–5 Ghauri–I) is a land-based surface-to-surface medium-range ballistic missile, in current service with the Pakistan Army's Strategic Forces Command— a subordinate command of Strategic Plans Division. Influenced from the design of Nodong-1 of North Korea, its extensive modification and engineering took place in Kahuta Research Laboratories (KRL) in 1990s with an objective of developing an electronic system that uses a single stage liquid fuel rocket motor to carry a payload of 700 kg to a range of 1,500 km. This is enough to reach most, if not all of India. Two variants of the Ghauri were produced under the secretive missile research programme started in 1987 and the development of a third variant was cancelled. The Ghauri-II uses increased motor assembly length and improved propellants for an increased range of 2,300 km (1,400 mi). The missile is named after Shahabuddin Muhammad Ghauri, while the "Hatf" designation originates from the name of the sword or lance of the Islamic prophet Muhammad.
  • 2.3K
  • 09 Nov 2022
Topic Review
Water Cooler
A water cooler or water dispenser is a device that cools and dispenses water. Water coolers come in a variety of form factors, ranging from wall-mounted to bottle filler water cooler combination units, to bi-level units and other formats. They are generally broken up in two categories: point-of use (POU) water coolers and bottled water coolers. POU Water coolers are connected to a water supply, while bottled water coolers require delivery (or self-pick-up) of water in large bottles from vendors. Bottled water coolers can be top-mounted or bottom-loaded, depending on the design of the model. Bottled water coolers typically use 5 or 10-gallon dispensers commonly found on top of the unit. Pressure coolers are a subcategory of water coolers encompassing water fountains and direct-piping water dispensers. Water cooler may also refer to a primitive device for keeping water cool. Water coolers are a common metonym referring to workplace socialization.
  • 2.2K
  • 18 Oct 2022
Topic Review
Active Hand Exoskeletons
Hand exoskeletons are still an active research field due to challenges that engineers face and are trying to solve. Each hand exoskeleton has certain requirements to fulfil to achieve their aims. 
  • 2.2K
  • 18 Mar 2021
Topic Review
Semaphore Line
A semaphore telegraph is a system of conveying information by means of visual signals, using towers with pivoting shutters, also known as blades or paddles. Information is encoded by the position of the mechanical elements; it is read when the shutter is in a fixed position. The most widely used system was invented in 1792 in France by Claude Chappe, and was popular in the late eighteenth to early nineteenth centuries. Lines of relay towers with a semaphore rig at the top were built within line-of-sight of each other, at separations of 5 to 20 miles. Operators at each tower would watch the neighboring tower through a spyglass, and when the semaphore arms began to move spelling out a message. They would pass the message on to the next tower. This system was much faster than post riders for conveying a message over long distances, and also had cheaper long-term operating costs, once constructed. Semaphore lines were a precursor of the electrical telegraph, which would replace them half a century later, and would also be cheaper, faster, and more private. The line-of-sight distance between relay stations was limited by geography and weather, and prevented the optical telegraph from crossing wide expanses of water, unless a convenient island could be used for a relay station. Modern derivatives of the semaphore system include flag semaphore (a flag relay system) and the heliograph (optical telegraphy using mirror-directed sunlight reflections).
  • 2.2K
  • 20 Oct 2022
Biography
William Anders
William Alison "Bill" Anders (born October 17, 1933), is a retired United States Air Force Major general, former electrical engineer, nuclear engineer, NASA astronaut, and businessman. He is known for being one of the first three persons to leave low Earth orbit and travel to the Moon in Apollo 8 along with fellow astronauts Frank Borman and Jim Lovell as well as for photographing the iconic ima
  • 2.2K
  • 15 Nov 2022
Topic Review
Lockheed Martin Compact Fusion Reactor
The Lockheed Martin Compact Fusion Reactor (CFR) is a proposed nuclear fusion reactor project at Lockheed Martin’s Skunk Works. Its high-beta configuration, which implies that the ratio of plasma pressure to magnetic pressure is greater than or equal to 1 (compared to tokamak designs' 0.05), allows a compact fusion reactor (CFR) design and expedited development. The CFR chief designer and technical team lead, Thomas McGuire studied fusion as a source of space propulsion in response to a NASA desire to improve travel times to Mars.
  • 2.2K
  • 17 Oct 2022
Topic Review
Microcomputer Revolution
The microcomputer revolution (or personal computer revolution or digital revolution) is a phrase used to describe the rapid advances of microprocessor-based computers from esoteric hobby projects to a commonplace fixture of homes in industrial societies during the 1970s and 1980s. Prior to 1977, the only contact most of the population had with computers was through utility bills, bank and payroll services, or computer-generated junk mail. Within a decade, computers became common consumer goods. The advent of affordable personal computers has had lasting impact on education, business, music, social interaction, and entertainment.
  • 2.2K
  • 27 Oct 2022
Topic Review
Woodworking Joints
Joinery is a part of woodworking that involves joining pieces of wood or lumber, to produce more complex items. Some wood joints employ fasteners, bindings, or adhesives, while others use only wood elements. The characteristics of wooden joints - strength, flexibility, toughness, appearance, etc. - derive from the properties of the materials involved and the purpose of the joint. Therefore, different joinery techniques are used to meet differing requirements. For example, the joinery used to construct a house can be different from that used to make puzzle toys, although some concepts overlap. In British English usage it is distinguished from carpentry which relates to structural timber work.
  • 2.2K
  • 22 Nov 2022
Topic Review
DTS (Sound System)
DTS, Inc. (originally Digital Theater Systems) is an American company that makes multichannel audio technologies for film and video. Based in Calabasas, California, the company introduced its DTS technology in 1993 as a competitor to Dolby Laboratories, incorporating DTS in the film Jurassic Park (1993). The DTS product is used in surround sound formats for both commercial/theatrical and consumer-grade applications. It was known as The Digital Experience until 1995. DTS licenses its technologies to consumer electronics manufacturers. The DTS brand was acquired by Tessera Holding Corporation in December 2016, then Tessera was renamed to Xperi Corporation.
  • 2.2K
  • 15 Nov 2022
Topic Review
Pocket-Sized Computer
Pocket-sized computer describes the post-programmable calculator / pre-smartphone pocket-sized portable-office hardware devices that included the earlier DOS-based palmtops and subsequent Windows-CE handhelds, as well as a few other terms, primarily covering the 1980s through 2007. Sometimes called Pocket-sized computing devices, they were a series of internally different devices, and included Handheld ("Pocket-sized handheld computing device"), and the earlier-introduced Palmtop ("Pocket-sized palmtop computing device") and "pocket-sized palmtop computer." The New York Times used the term "palmtop/handheld." The media called "the first computer that fits in your palm and weighs less than a pound" and its early day competitors a palmtop. Although the word "handheld" was used before Microsoft's 1996 introduction of Windows CE, a lawsuit by Palm, Inc pushed Microsoft's use of the new term Handheld PC. By 2007, the iPhone began to replace prior portable office devices, and by a decade later there were indications that "SmartGlasses" might be their replacement.
  • 2.1K
  • 28 Nov 2022
Topic Review
Mercedes-Benz First Series Automatic Transmission
The Mercedes-Benz first series of automatic transmission was produced from 1961 to 1983 in four- and three-speed variants for Mercedes-Benz passenger cars. In addition, variants for commercial vehicles were offered.
  • 2.1K
  • 21 Oct 2022
Topic Review
Springfield Armory XDM
The Springfield Armory XDM (X-Treme Duty, the M is for the match grade barrel and match grade trigger) are a series of semi-automatic pistols that are polymer-framed and striker-fired. They closely resemble their predecessor, the HS2000 pistol (most widely known in the United States as Springfield Armory XD). Manufactured in the city of Karlovac, Croatia by HS Produkt (formerly I.M. Metal), the Springfield Armory XDM is the marketing name for the firearm, which is licensed and sold in the United States by Springfield Armory, Inc..
  • 2.1K
  • 25 Oct 2022
Topic Review
SpaceX Dragon
Dragon, also known as Dragon 1 or Cargo Dragon, was a class of partially reusable cargo spacecraft developed by SpaceX, an American private space transportation company. Dragon was launched into orbit by the company's Falcon 9 launch vehicle to resupply the International Space Station (ISS). During its maiden flight in December 2010, Dragon became the first commercially built and operated spacecraft to be recovered successfully from orbit. On 25 May 2012, a cargo variant of Dragon became the first commercial spacecraft to successfully rendezvous with and attach to the ISS. SpaceX is contracted to deliver cargo to the ISS under NASA's Commercial Resupply Services program, and Dragon began regular cargo flights in October 2012. With the Dragon spacecraft and the Orbital ATK Cygnus, NASA seeks to increase its partnerships with domestic commercial aviation and aeronautics industry. On 3 June 2017, the C106 capsule, largely assembled from previously flown components from the CRS-4 mission in September 2014, was launched again for the first time on CRS-11, with the hull, structural elements, thrusters, harnesses, propellant tanks, plumbing and many of the avionics reused, while the heat shield, batteries and components exposed to sea water upon splashdown for recovery were replaced. SpaceX developed a second version called Dragon 2, which is capable of transporting humans. Flight testing was completed in 2019, after a delay caused by a test pad anomaly in April 2019, which resulted in the loss of a Dragon 2 capsule. The first flight of astronauts on Dragon 2 occurred on the Crew Dragon Demo-2 mission in May 2020. The last flight of the first version of the Dragon spacecraft (Dragon 1) launched 7 March 2020 (UTC); it was a cargo resupply mission (CRS-20) to International Space Station (ISS). This mission was the last mission of SpaceX of the first Commercial Resupply Services (CRS-1) program, and marked the retirement of the Dragon 1 fleet. Further SpaceX commercial resupply flights to ISS under the second Commercial Resupply Services (CRS-2) program use the cargo-carrying variant of the SpaceX Dragon 2 spacecraft.
  • 2.1K
  • 12 Oct 2022
Topic Review
Gel Blasters
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 follow 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.
  • 2.1K
  • 20 Nov 2022
Topic Review
Zen (Microarchitecture)
Zen is the codename for a computer processor microarchitecture from AMD, and was first used with their Ryzen series of CPUs in February 2017. The first Zen-based preview system was demonstrated at E3 2016, and first substantially detailed at an event hosted a block away from the Intel Developer Forum 2016. The first Zen-based CPUs codenamed "Summit Ridge" reached the market in early March 2017, Zen-derived Epyc server processors launched in June 2017 and Zen-based APUs arrived in November 2017. Zen is a clean sheet design that differs from the long-standing Bulldozer architecture. Zen-based processors use a 14 nm FinFET process, are reportedly more energy efficient, and can execute significantly more instructions per cycle. SMT has been introduced, allowing each core to run two threads. The cache system has also been redesigned, making the L1 cache write-back. Zen processors use three different sockets: desktop and mobile Ryzen chips use the AM4 socket, bringing DDR4 support; the high-end desktop Zen-based Threadripper chips support quad-channel DDR4 RAM and offer 64 PCIe 3.0 lanes (vs 24 lanes), using the TR4 socket; and Epyc server processors offer 128 PCI 3.0 lanes and octal-channel DDR4 using the SP3 socket. But not all Socket AM4 CPUs are based on Zen microarchitecture (the 7th gen APUs and Athlon X4s are based on Excavator microarchitecture). Zen is based on a SoC design. The memory, PCIe, SATA, and USB controllers are incorporated into the same chip as the processor cores. This has advantages in bandwidth and power, at the expense of chip complexity and die area. This SoC design allows the Zen microarchitecture to scale from laptops and small-form factor mini PCs to high-end desktops and servers.
  • 2.1K
  • 11 Nov 2022
Topic Review
Multiple Attribute-based Decision-making Models
Sustainability of agricultural practices depends on economic, environmental, and social conditions. The Rajasthan state of India has arid climatic conditions where kharif crops are commonly grown. In this work, the four major criteria are considered such as the farm area, crop yield per unit area, the cost prices, and the market sales price. Merged analytic hierarchy process (AHP) and entropy techniques have been employed to give reasonable weight coefficients for the objective and subjective weights to each criterion. Multiple attribute-based decision-making models (MADM) have been developed using three proven techniques, namely the Exprom2, the technique for order of preference by similarity to ideal solution (TOPSIS), and the VlseKriterijumska Optimizacija I KompromisnoResenje (VIKOR). The crop Pennisetum glaucum emerged as the most productive kharif crop in the arid climatic conditions of Rajasthan, India under the given criteria. The sensitivity analysis of the three methods identifies the most significant criteria and validates that Pennisetum glaucum is the first ranked crop despite the interchange of the weights. The methodology used in this study may be applied across the globe to select appropriate crops for maximizing the profit, optimizing the natural resources, and promoting sustainable agricultural practices. This study may be used to enhance the agricultural gross domestic product (GDP) to make the agriculturalists self-sufficient and to help the state policymakers in making elective regional policies.
  • 2.1K
  • 05 Nov 2020
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