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Topic Review
Heckler & Koch HK69A1
The HK69A1 is a 40 mm grenade launcher developed and produced by the German arms manufacturer Heckler & Koch (H&K). The weapon was designed to engage enemy troops and strongpoints out to a distance of 350 m; it can also be used to deploy smoke grenades and illumination flares.
  • 1.7K
  • 05 Nov 2022
Topic Review
Electroless Nickel Plating
Electroless nickel (EN) plating is an auto-catalytic reaction that deposits an even layer of nickel-phosphorus or nickel-boron alloy on the surface of a solid material, or substrate, like metal or plastic. The process involves dipping the substrate in a bath of plating solution, where a reducing agent, like hydrated sodium hypophosphite (NaPO2H2 · H2O), reacts with the material's ions to deposit the nickel alloy. The metallurgical properties of the alloy depend on the percentage of phosphorus, which can range from 2–5% (low phosphorus) to 11–14% (high phosphorus). Unlike electroplating, it is not necessary to pass an electric current through the plating solution to form a deposit. Electroless plating prevents corrosion and wear, and can be used to manufacture composite coatings by suspending powder in the bath.[1] EN plating creates an even layer regardless of the geometry of the surface – in contrast to electroplating which suffers from flux-density issues as an electric field will vary due to the surface profile and result in uneven depositions. Depending on the catalyst, EN plating can be applied to non-conductive surfaces.
  • 1.7K
  • 23 Nov 2022
Topic Review
DAvE (Infineon)
DAVE (Infineon) Digital Application Virtual Engineer (DAVE), is a C/C++-language software development and code generation tool for microcontroller applications. DAVE is a standalone system with automatic code generation modules. It is suited for the development of software drivers for Infineon microcontrollers and aids the developer with automatically created C-level templates and user desired functionalities. Latest releases of DAVE include all required parts to develop code, compile and debug on the target for free (based on the ARM GCC toolsuite). Together with several low-cost development boards one can get involved in microcontroller design very easy. This makes Infineon microcontroller products also more usable to small companies and to home-use / DIY projects - similar to established products of Atmel (AVR, SAM) and Microchip (PIC, PIC32) to name a few. DAVE was developed by Infineon Technologies. Therefore, the automatic code generator supports only Infineon microcontrollers. The user also has to get used to the concept of the Eclipse IDE. The generated code can be also used on other (often non-free) development environments from Keil, Tasking and so on.
  • 1.7K
  • 15 Nov 2022
Topic Review
Electromagnetic Coil
An electromagnetic coil is an electrical conductor such as a wire in the shape of a coil (spiral or helix). Electromagnetic coils are used in electrical engineering, in applications where electric currents interact with magnetic fields, in devices such as electric motors, generators, inductors, electromagnets, transformers, and sensor coils. Either an electric current is passed through the wire of the coil to generate a magnetic field, or conversely, an external time-varying magnetic field through the interior of the coil generates an EMF (voltage) in the conductor. A current through any conductor creates a circular magnetic field around the conductor due to Ampere's law. The advantage of using the coil shape is that it increases the strength of the magnetic field produced by a given current. The magnetic fields generated by the separate turns of wire all pass through the center of the coil and add (superpose) to produce a strong field there. The more turns of wire, the stronger the field produced. Conversely, a changing external magnetic flux induces a voltage in a conductor such as a wire, due to Faraday's law of induction. The induced voltage can be increased by winding the wire into a coil because the field lines intersect the circuit multiple times. The direction of the magnetic field produced by a coil can be determined by the right hand grip rule. If the fingers of the right hand are wrapped around the magnetic core of a coil in the direction of conventional current through the wire, the thumb will point in the direction the magnetic field lines pass through the coil. The end of a magnetic core from which the field lines emerge is defined to be the North pole. There are many different types of coils used in electric and electronic equipment.
  • 1.7K
  • 01 Dec 2022
Topic Review
InN SAs for Ultrafast Lasers
New fabrication methods are strongly demanded for the development of thin-film saturable absorbers with improved optical properties (absorption band, modulation depth, nonlinear optical response). In this sense, we investigate the performance of indium nitride (InN) epitaxial layers with low residual carrier concentration (<1018 cm^-3), which results in improved performance at telecom wavelengths (1560 nm). These materials have demonstrated a huge modulation depth of 23% and a saturation fluence of 830 uJ/cm2, and a large saturable absorption around -3 x10^4 cm/GW has been observed, attaining an enhanced, nonlinear change in transmittance. We have studied the use of such InN layers as semiconductor saturable absorber mirrors (SESAMs) for an erbium (Er)-doped fiber laser to perform mode-locking generation at 1560 nm. We demonstrate highly stable, ultrashort (134 fs) pulses with an energy of up to 5.6 nJ.a
  • 1.7K
  • 01 Dec 2020
Topic Review
SkySat
SkySat is a constellation of sub-meter resolution Earth observation satellites owned by Planet Labs, providing imagery, high-definition video and analytics services. Planet acquired the satellites with their purchase of Terra Bella (formerly Skybox Imaging), a Mountain View, California-based company founded in 2009 by Dan Berkenstock, Julian Mann, John Fenwick, and Ching-Yu Hu, from Google in 2017.
  • 1.7K
  • 22 Nov 2022
Topic Review
Leaching
Leaching is the process of a solute becoming detached or extracted from its carrier substance by way of a solvent. Leaching is a naturally occurring process which scientists have adapted for a variety of applications with a variety of methods. Specific extraction methods depend on the soluble characteristics relative to the sorbent material such as concentration, distribution, nature, and size. Leaching can occur naturally seen from plant substances (inorganic and organic), solute leaching in soil, and in the decomposition of organic materials. Leaching can also be applied affectedly to enhance water quality and contaminant removal, as well as for disposal of hazardous waste products such as fly ash, or rare earth elements (REEs). Understanding leaching characteristics is important in preventing or encouraging the leaching process and preparing for it in the case where it is inevitable. In an ideal leaching equilibrium stage, all the solute is dissolved by the solvent, leaving the carrier of the solute unchanged. The process of leaching however is not always ideal, and can be quite complex to understand and replicate, and often different methodologies will produce different results.
  • 1.7K
  • 15 Nov 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.
  • 1.7K
  • 25 Nov 2022
Biography
Caroline Pratt
Caroline Pratt (May 13, 1867 – June 6, 1954[1] ) was an American social thinker and progressive educational reformer whose ideas were influential in educational reform, policy, and practice.[2] Pratt is known as the founder of City and Country School in the Greenwich Village section of the borough of Manhattan in New York City ; the inventor of unit blocks;[3][4][5] and as the author of I Le
  • 1.7K
  • 01 Dec 2022
Topic Review
Anton Schlüter München
Anton Schlüter München (also spelled: Anton Schlueter Muenchen) was a Germany tractor manufacturer in the region of Munich, Bavaria. Amongst farmers and tractor enthusiasts, this brand is usually known simplified, as Schlüter (also spelled: Schlueter).
  • 1.7K
  • 04 Nov 2022
Topic Review
Tracking and Data Relay Satellite
File:TDRS Heart of Communication.ogv File:Tracking Data Relay Satellite (TDRS) Orbital Fleet Communicating with User Spacecraft.ogg File:Tracking Data Relay Satellite (TDRS) Orbital Fleet Communicating with User Spacecraft 2017 - 360 video.webm A tracking and data relay satellite (TDRS) is a type of communications satellite that forms part of the Tracking and Data Relay Satellite System (TDRSS) used by NASA and other United States government agencies for communications to and from independent "User Platforms" such as satellites, balloons, aircraft, the International Space Station, and remote bases like the Amundsen-Scott South Pole Station. This system was designed to replace an existing worldwide network of ground stations that had supported all of NASA's crewed flight missions and uncrewed satellites in low-Earth orbits. The primary system design goal was to increase the amount of time that these spacecraft were in communication with the ground and improve the amount of data that could be transferred. These TDRSS satellites are all designed and built to be launched to and function in geosynchronous orbit, 35,786 km (22,236 mi) above the surface of the Earth. The first seven TDRSS satellites were built by the TRW corporation. The three later versions have been manufactured by the Boeing corporation's Satellite Systems division. Thirteen satellites have been launched; however, one was destroyed in the Challenger disaster. TDRS-1 was decommissioned in October 2009. TDRS-4 was decommissioned in December 2011. Ten TDRSS satellites are currently in service. All of the TDRSS satellites have been managed by NASA's Goddard Space Flight Center. The contract for TDRS versions L & K was awarded to Boeing on December 20, 2007. On November 30, 2011, NASA announced the decision to order an additional third-generation TDRS satellite, TDRS M.
  • 1.7K
  • 04 Nov 2022
Topic Review
Three-Section Staff
The three-section staff, triple staff, three-part staff, sansetsukon in Japanese, or originally sanjiegun (Chinese: 三節棍; pinyin: sānjiégùn; Jyutping: saam1 zit3 gwan3, or Chinese: 三節鞭; pinyin: sānjiébiān three-sectional whip), is a Chinese flail weapon that consists of three wooden or metal staffs connected by metal rings or rope. The weapon is also known as 蟠龍棍 panlong gun, "coiling dragon staff". A more complicated version of the two section staff, the staves can be spun to gather momentum resulting in a powerful strike, or their articulation can be used to strike over or around a shield or other defense.
  • 1.7K
  • 10 Oct 2022
Topic Review
List of Tram Track Gauges
A list of tram track gauges is given below.
  • 1.7K
  • 14 Nov 2022
Topic Review
Tutedhara
A tutedhara (Nepali) or jahru (Newari) is a traditional drinking fountain found in Nepal. It is a water reservoir built out of stone with a tap that can be opened and closed. These structures are either free-standing or integrated into the wall of another building. They depend on a water well or a dhunge dhara to be filled. Only a few of them are in use today, but some of the stone parts have been put to other uses, and there are contemporary equivalents. The best known tutedhara is the one built into a wall in the royal palace on Kathmandu Durbar Square. It is inscribed with a poem dedicated to the goddess Kali, written in fifteen different languages.
  • 1.7K
  • 02 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
  • 1.7K
  • 22 Nov 2022
Topic Review
ERYX
ERYX is a short-range portable SACLOS-based wire-guided anti-tank missile (ATGM) produced by European company MBDA. It is used by several countries, including the Canadian Army, French, and Norwegian armies. The weapon can also be used against bunkers and pillboxes. It also has some capability in the anti aircraft role to bring down low flying helicopters, due to its wire guided system. An agreement was reached in 1989 between the French and Canadian governments to co-produce the ERYX missile system. It entered service in 1994.
  • 1.7K
  • 04 Nov 2022
Topic Review
Mobile Learning Technologies for Education
The digital revolution is transforming education by using information and communication technologies (ICTs) to improve student's learning outcomes. In the last 50 years, changes can be seen in every area of society, such as culture, entertainment, and social interaction. However, the current educational model is very similar to how it was back then. Due to the characteristics of mobile devices, and the inexperience of teachers and educational institutions, students may experience distractions in their learning and may be involved in inefficient educational methodologies. Digital revolution is transforming these educational models, involving students, teachers, and educational institutions in this process[3]. The appropriate use of digital technologies and a pedagogical approach in the design of learning models could generate an improvement in the learning results of the students. Today’s world demands more efficient learning models that allow students to play a more active role in their education. Technology is having an impact on how instruction is delivered and how information is found and share. Until very recently, the educational models encouraged memorization as an essential learning skill. These days, technologies have changed the educational model and access to information. Knowledge is available online, mostly free, and easily accessible. Reading, sharing, listening and, doing are currently necessary skills for education. The study of innovation in education systems has increasingly attracted the attention of academics around the world. Educational innovation refers to new ways of delivering education in a way that impacts new generations of students. The educational model in higher education institutions (HEIs) was not designed for this generation of "digital natives". Therefore, HEIs face the challenge of improving their teaching strategies and making them attractive to students and their needs. Mobile devices have become a complete set of applications, support, and help for educational organizations. By conducting an analysis of the behavior and use of mobile devices on current students, efficient educational applications can be developed. Although there are several initiatives for the use of mobile learning in education, there are also issues linked to this technology that must be addressed.
  • 1.7K
  • 11 May 2021
Topic Review
Bronze and Brass Ornamental Work
The use of bronze dates from remote antiquity. This important metal is an alloy composed of copper and tin, in proportion which vary slightly, but may be normally considered as nine parts of copper to one of tin. Other ingredients which are occasionally found are more or less accidental. The result is a metal of a rich golden brown colour, capable of being worked by casting — a process little applicable to its component parts, but peculiarly successful with bronze, the density and hardness of the metal allowing it to take any impression of a mould, however delicate. It is thus possible to create ornamental work of various kinds. The process of casting is known as cire perdue, and is the most primitive and most commonly employed through the centuries, having been described by the monk Theophilus, and also by Benvenuto Cellini. Briefly, it is as follows: a core, roughly representing the size and form of the object to be produced, is made of pounded brick, plaster or other similar substance and thoroughly dried. Upon this the artist overlays his wax, which he models to the degree required in his finished work. Passing from the core through the wax and projecting beyond are metal rods. The modelling being completed, called lost-wax casting, the outer covering which will form the mould has to be applied; this is a liquid formed of clay and plaster sufficiently thin to find its way into every detail of the wax model. Further coatings of liquid are applied, so that there is, when dry, a solid outer coating and a solid inner core held together by the metal rods, with the work of art modelled in wax between. Heat is applied and the wax melts and runs out, and the molten metal is poured in and occupies every detail which the wax had filled. When cool, the outer casing is carefully broken away, the core raked out as far as possible, the projecting rods are removed and the object modelled in wax appears in bronze. If further finish is required, it is obtained by tooling.
  • 1.7K
  • 28 Nov 2022
Biography
Harry Traver
Harry Guy Traver (November 25, 1877 – September 27, 1961) was an United States engineer and early roller coaster designer. As the founder of the Traver Engineering Company, Traver was responsible for the production of gentle amusement rides like the Tumble Bug and Auto Ride. However, Traver's coasters became legendary for their unique twisted layouts and thrilling, swooped turns. At a time wh
  • 1.7K
  • 16 Dec 2022
Topic Review
Ion Transport of Two-Dimensional Materials
Ion transport is one of the basic principles of the development of various different technologies that can improve the quality of our lives, such as the ever-growing importance of clean and sustainable energy, the reduction of water scarcity and even the improvement of fundamental medical application knowledge. Ion transport can be defined as the movement of charged ions from one position to another in ion electrolyte solutions within both organic (living cells) and inorganic (polymer materials) systems. Ion transport can be encouraged through various mechanisms such as electrochemical diffusion, ion active transport requiring external energy or bulk transport for the conversion of adenosine triphosphate (ATP) and energy consumption in biological functions.
  • 1.7K
  • 27 Oct 2021
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