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Topic Review
High-explosive Anti-tank Warhead
A high-explosive anti-tank (HEAT) warhead is a type of shaped charge explosive that uses the Munroe effect to penetrate thick tank armor. The warhead functions by having the explosive charge collapse a metal liner inside the warhead into a high-velocity superplastic jet. This superplastic jet is capable of penetrating armor steel to a depth of seven or more times the diameter of the charge (charge diameters, CD) but is usually used to immobilize or destroy tanks. Due to the way they work, they do not have to be fired as fast as an armor piercing shell, allowing less recoil. Contrary to a widespread misconception (possibly resulting from the acronym HEAT), the jet does not melt its way through armor, as its effect is purely kinetic in nature. The HEAT warhead has become less effective against tanks and other armored vehicles due to the use of composite armor, explosive-reactive armor, and active protection systems which destroy the HEAT warhead before it hits the tank. While HEAT ammunition has become less effective against the composite armor found on MBTs from 1964 onward and today pose little threat to any modern tank, they are still deadly against lighter vehicles. In addition, air vehicles are also possible targets.
  • 3.7K
  • 01 Nov 2022
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).
  • 3.7K
  • 20 Oct 2022
Topic Review
Switched-Capacitor-Based Converters
An extensive entry of basic concepts and switched capacitor structures employed in the conception of DC-DC converters is presented.
  • 3.6K
  • 06 May 2021
Topic Review
Multivariable Formulation of Surfactant-Oil-Water Systems
Surfactant-Oil-Water (SOW) systems are found in nature and synthetic products. They usually result in two immiscible phases, e.g., for two liquids, a water phase (often a brine), and an oily phase (which could be extremely complex as petroleum). Surfactant partitions between the two phases according to some physicochemical rules due to molecular interactions. There is a very particular formulation case in which SOW systems can form three immiscible phases, that is, two excess phases (water and oil) in equilibrium with a  so-called middle phase (because of an intermediate density that places it in the middle of a test tube). This middle phase is a so-called bicontinuous microemulsion which has no droplets dispersed in an external phase as a typical emulsion, but a complex single-phase structure similar to a disordered liquid crystal. When stirred, SOW systems can form multiple dispersed systems that can be described as macroemulsions or nanoemulsions depending on the drop size (O/W or W/O) or multiple emulsions (w/O/W or o/W/O) with droplets inside larger drops. Since the beginnings of the 20th century with Bancroft’s rule, the properties of these systems have been related to many thermodynamic variables, generally with one effect at a time. Nowadays, the generalized physicochemical concept of SOW systems with many formulation variables involved allows to make predictions in various application cases, even for very complex systems, as in enhanced oil recovery (EOR), crude oil dehydration, paints, foods, cosmetics and pharmaceutical formulations, that requires the control on 6-8 variables or even more. This is mainly because of the presence of mixtures of oils from linear alkanes to triglycerides or complex molecules perfumes, or a mixture of salts with cations from sodium to calcium or aluminum, and anions like chloride to phosphate. The complexity is even worse with mixtures of very different surface-active species, resulting in non-linear interactions.
  • 3.6K
  • 17 Aug 2021
Topic Review
105×617mm
The 105×617mm (4.1 inch) also known as 105 × 617 R is a common, NATO-standard, tank gun cartridge used in 105mm guns such as those derived from the Royal Ordnance L7. The 105 × 617 R cartridge was originally developed from the 84 mm (3.3 in) calibre Ordnance QF 20-pounder 84 × 618R cartridge as part of the development of the L7 105 mm rifled gun.
  • 3.6K
  • 03 Nov 2022
Topic Review
Molten Salt Reactor
A molten salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a molten salt mixture. Only two MSRs have ever operated, both research reactors in the United States . The 1950's Aircraft Reactor Experiment was primarily motivated by the compact size that the technique offers, while the 1960's Molten-Salt Reactor Experiment aimed to prove the concept of a nuclear power plant which implements a thorium fuel cycle in a breeder reactor. Increased research into Generation IV reactor designs began to renew interest in the technology, with multiple nations having projects and, as of September 2021, China is on the verge of starting its TMSR-LF1 thorium MSR. MSRs are considered safer than conventional reactors because they operate with fuel already in a molten state, and in event of an emergency, the fuel mixture is designed to drain from the core where it will solidify, preventing the type of nuclear meltdown and associated hydrogen explosions (like what happened in the Fukushima nuclear disaster) that are at risk in conventional (solid-fuel) reactors. They operate at or close to atmospheric pressure, rather than the 75-150 times atmospheric pressure of a typical light-water reactor (LWR), hence reducing the need for large, expensive reactor pressure vessels used in LWRs. Another characteristic of MSRs is that the radioactive fission gases produced are absorbed into the molten salt, as opposed to conventional reactors where the fuel rod tubes must contain the gas. MSR's can also be refueled while operating (essentially online-nuclear reprocessing) while conventional reactors must be shut down for refueling (Heavy water reactors like the CANDU or the Atucha-class PHWRs being a notable exception). A further key characteristic of MSRs is operating temperatures of around 700 °C (1,292 °F), significantly higher than traditional LWRs at around 300 °C (572 °F), providing greater electricity-generation efficiency, the possibility of grid-storage facilities, economical hydrogen production, and, in some cases, process-heat opportunities. Relevant design challenges include the corrosivity of hot salts and the changing chemical composition of the salt as it is transmuted by the neutron flux in the reactor core. MSRs offer multiple advantages over conventional nuclear power plants, although for historical reasons they have not been deployed.
  • 3.6K
  • 15 Nov 2022
Topic Review
Differential Signaling
Differential signaling is a method for electrically transmitting information using two complementary signals. The technique sends the same electrical signal as a differential pair of signals, each in its own conductor. The pair of conductors can be wires in a twisted-pair or ribbon cable or traces on a printed circuit board. Electrically, the two conductors carry voltage signals which are equal in magnitude, but of opposite polarity. The receiving circuit responds to the difference between the two signals, which results in a signal a magnitude twice as large. Any interference caused by the transmission of differential signals tend to cancel out resulting in reduced emission that could affect nearby circuits.
  • 3.5K
  • 02 Nov 2022
Topic Review
O3b MEO
O3b MEO is a satellite constellation in Medium Earth orbit (MEO) designed to provide low-latency broadband connectivity to remote locations for mobile network operators and internet service providers, maritime, aviation, and government and defence. Originally O3b, the name was changed in September 2020 to more clearly distinguish these satellites from the forthcoming O3b mPOWER constellation. O3b stood for "other three billion", or the other three billion people at the time that did not have stable internet access. The constellation was initially built, owned and operated by O3b Networks, which became a wholly owned subsidiary of SES S.A. in 2016 and ownership and operation of the constellation passed to SES Networks, a division of SES. The O3b MEO constellation began offering service in March 2014.
  • 3.5K
  • 19 Oct 2022
Topic Review
Venice Charter
The Venice Charter for the Conservation and Restoration of Monuments and Sites is a set of guidelines, drawn up in 1964 by a group of conservation professionals in Venice, that provides an international framework for the conservation and restoration of historic buildings. However, the document is now seen as outdated, representing Modernist views opposed to reconstruction. Reconstruction is now cautiously accepted by UNESCO in exceptional circumstances if it seeks to reflect a pattern of use or cultural practice that sustains cultural value, and is based on complete documentation without reliance on conjecture. The change in attitude can be marked by the reconstruction in 2015 of the Sufi mausoleums at the Timbuktu World Heritage Site in Mali after their destruction in 2012.
  • 3.5K
  • 04 Nov 2022
Biography
Benjamin Bradley
Benjamin Bradley (March 1836–1904) was an American engineer and inventor. Benjamin's correct surname was Boardley,[1][2][3] but since 1859 when the African Repository published an article wrongly spelling Benjamin's surname as Bradley, authors have written about him with the incorrect surname.[4] Benjamin Bradley was born a slave in Anne Arundel County, Maryland in March 1836.[2]  It has
  • 3.5K
  • 13 Dec 2022
Topic Review
List of ARM Microarchitectures
This is a list of microarchitectures based on the ARM family of instruction sets designed by ARM Holdings and 3rd parties, sorted by version of the ARM instruction set, release and name. In 2005, ARM provided a summary of the numerous vendors who implement ARM cores in their design. Keil also provides a somewhat newer summary of vendors of ARM based processors. ARM further provides a chart displaying an overview of the ARM processor lineup with performance and functionality versus capabilities for the more recent ARM core families.
  • 3.5K
  • 10 Nov 2022
Topic Review
Satellite Constellations
The New Space Economy encourages constellations of satellites that are being proposed in large numbers by private companies. They will provide communication, enable global monitoring of Earth, and enhance space observation. Mostly enabled by technology miniaturization, satellite constellations require a coordinated effort to face the technological limits in spacecraft operations and space traffic. In this Topic Review, we provide a survey of the upcoming satellite constellations and an overview of future challenges to be faced.
  • 3.5K
  • 27 Oct 2020
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
  • 3.5K
  • 15 Nov 2022
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.
  • 3.5K
  • 29 Oct 2020
Topic Review
List of AMD Athlon Microprocessors
Athlon is the name of a family of CPUs designed by AMD, targeted mostly at the desktop market. It has been largely unused as just "Athlon" since 2001 when AMD started naming its processors Athlon XP, but in 2008 began referring to single core 64-bit processors from the AMD Athlon X2 and AMD Phenom product lines. Later the name began being used for some APUs.
  • 3.5K
  • 26 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.
  • 3.5K
  • 22 Nov 2022
Topic Review
Interactivity
Across the many fields concerned with interactivity, including information science, computer science, human-computer interaction, communication, and industrial design, there is little agreement over the meaning of the term "interactivity", but most definitions are related to interaction between users and computers and other machines through a user interface. Interactivity can however also refer to interaction between people. It nevertheless usually refers to interaction between people and computers – and sometimes to interaction between computers – through software, hardware, and networks. Multiple views on interactivity exist. In the "contingency view" of interactivity, there are three levels: One body of research has made a strong distinction between interaction and interactivity. As the suffix 'ity' is used to form nouns that denote a quality or condition, this body of research has defined interactivity as the 'quality or condition of interaction'. These researchers suggest that the distinction between interaction and interactivity is important since interaction may be present in any given setting, but the quality of the interaction varies from low and high.
  • 3.5K
  • 26 Oct 2022
Biography
Howard Scott
Howard Scott (April 1, 1890 – January 1, 1970) was an American engineer and founder of the Technocracy movement. He formed the Technical Alliance and Technocracy Incorporated.[1] Little is known about Scott's background or his early life and he has been described as a "mysterious young man".[2] He was born in Virginia in 1890 and was of Scottish-Irish descent. He claimed to have been educat
  • 3.4K
  • 19 Dec 2022
Topic Review
Vinylidene Fluoride
1,1-difluoroethylene (VDF) is one of the major fluoromonomers, which are the feedstock for the production of various resins, rubbers membrane and paints. The polymers derived from VDF (PVDF) or co-polymers with unique chemical resistance, stability at elevated temperatures, oxidation resistance, weatherability, piezoelectricity, dielectric and thermoelectricity, find wide applications in areas including petrochemical, electronic and electrical, and fluorocarbon coating. VDF is the second largest product among fluorocarbons with an annual production capacity of above 53,000 tons. The demand for VDF is increasing rapidly. At present, in industry, VDF is usually produced via the dehydrochlorination of 1,1-difluoro-1-chloroethane (HCFC-142b) at reaction temperatures above 650 °C
  • 3.4K
  • 30 Oct 2020
Topic Review
Comet Lake
Comet Lake is Intel's codename for its 10th generation Core microprocessors. They are manufactured using Intel's third 14 nm Skylake process refinement, succeeding the Whiskey Lake U-series mobile processor and Coffee Lake desktop processor families. Intel announced low-power mobile Comet Lake-U CPUs on August 21, 2019, H-series mobile CPUs on April 2, 2020, desktop Comet Lake-S CPUs April 30, 2020, and Xeon W-1200 series workstation CPUs on May 13, 2020. Comet Lake processors and Ice Lake 10 nm processors are together branded as the Intel "10th Generation Core" family. Intel officially launched Comet Lake-Refresh CPUs on the same day as 11th Gen Core Rocket Lake launch. The low-power mobile Comet Lake-U Core and Celeron 5205U CPUs were discontinued on July 7, 2021.
  • 3.4K
  • 21 Nov 2022
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