Topic Review
Waveguide (Electromagnetism)
In electromagnetics and communications engineering, the term waveguide may refer to any linear structure that conveys electromagnetic waves between its endpoints. However, the original and most common meaning is a hollow metal pipe used to carry radio waves. This type of waveguide is used as a transmission line mostly at microwave frequencies, for such purposes as connecting microwave transmitters and receivers to their antennas, in equipment such as microwave ovens, radar sets, satellite communications, and microwave radio links. A dielectric waveguide employs a solid dielectric rod rather than a hollow pipe. An optical fibre is a dielectric guide designed to work at optical frequencies. Transmission lines such as microstrip, coplanar waveguide, stripline or coaxial cable may also be considered to be waveguides. The electromagnetic waves in a (metal-pipe) waveguide may be imagined as travelling down the guide in a zig-zag path, being repeatedly reflected between opposite walls of the guide. For the particular case of rectangular waveguide, it is possible to base an exact analysis on this view. Propagation in a dielectric waveguide may be viewed in the same way, with the waves confined to the dielectric by total internal reflection at its surface. Some structures, such as non-radiative dielectric waveguides and the Goubau line, use both metal walls and dielectric surfaces to confine the wave.
  • 6
  • 07 Oct 2022
Topic Review
Secure Digital
Secure Digital (SD) is a non-volatile memory card format developed by the SD Card Association (SDA) for use in portable devices. The standard was introduced in August 1999 by joint efforts between SanDisk, Panasonic (Matsushita Electric) and Toshiba as an improvement over MultiMediaCards (MMC), and has become the industry standard. The three companies formed SD-3C, LLC, a company that licenses and enforces intellectual property rights associated with SD memory cards and SD host and ancillary products. The companies also formed the SD Association (SDA), a non-profit organization, in January 2000 to promote and create SD Card standards. SDA today has about 1,000 member companies. The SDA uses several trademarked logos owned and licensed by SD-3C to enforce compliance with its specifications and assure users of compatibility.
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  • 07 Oct 2022
Topic Review
Friction-plate Electromagnetic Couplings
Electromagnetic clutches and brakes operate electrically, but transmit torque mechanically. This is why they used to be referred to as electro-mechanical clutches or brakes. Over the years, EM became known as electromagnetic versus electro mechanical, referring more about their actuation method versus physical operation. Since the clutches started becoming popular over 60 years ago, the variety of applications and brake and clutch designs has increased dramatically, but the basic operation remains the same. This article is about the working principles of single face friction plate clutches and brakes. In this article, clutches and brakes are referred to as (mechanical) couplings.
  • 6
  • 07 Oct 2022
Topic Review
Nest Learning Thermostat
The Nest Learning Thermostat (or Nest Thermostat) is a smart thermostat developed by Nest Labs and designed by Tony Fadell, Ben Filson, and Fred Bould. It is an electronic, programmable, and self-learning Wi-Fi-enabled thermostat that optimizes heating and cooling of homes and businesses to conserve energy. The device is based on a machine learning algorithm: for the first weeks users have to regulate the thermostat in order to provide the reference data set. The thermostat can then learn people's schedule, at which temperature they are used to and when. Using built-in sensors and phones' locations, it can shift into energy saving mode when it realizes nobody is at home.
  • 8
  • 07 Oct 2022
Topic Review
Anti Urination Devices in Norwich
Anti urination devices were a form of hostile architecture installed in Norwich and the surrounding area in the late 19th century to discourage public urination. The overcrowded and narrow streets of the city centre and a lack of public toilets led to men urinating against the side of buildings, but the installation of new public urinals to address the issue was delayed by disputes over where they were to be sited. Anti urination devices were built in places which suffered particular problems with public urination, and were intended to discourage men from urinating at that spot. Most were built of sloped or curved stone, flint or concrete, and were shaped such that anyone attempting to urinate against the wall would need to stand well away from the wall in public view, hopefully discouraging them from doing so. The slope of the structure meant that should anyone still attempt to urinate against it, the stream of urine would be deflected back onto their feet and legs. A few instead consisted of a spiked metal bar positioned across a corner at the height of a typical man's groin, and were intended to dissuade men from approaching the corner with their genitals exposed. Following improved public toilet provision from the 1890s onwards, the problems caused by the lack of urinals became less of an issue, and anti urination devices ceased to be installed. Although most metal examples were removed during the Second World War, and many others have been demolished in subsequent years, around 30 remain in place in central Norwich with further surviving examples in other parts of East Anglia.
  • 5
  • 07 Oct 2022
Topic Review
Additive Manufacturing of Turbine Blades
Additive manufacturing is a technology of transforming a 3D prototype to a physical one directly by successive addition of the required material in a layer-by-layer manner. This technique helps to manufacture the turbine blade which is the revolution of green technology for high temperature engine parts.
  • 20
  • 07 Oct 2022
Topic Review
José António Tenreiro Machado
This manuscript intends to present Prof.Tenreiro Machado's main research interests, pointing to the most relevant work that was published throughout his life. Moreover, a brief description of his early life and international academic career are also presented. His contributions to control, robotics, modeling, complex systems and Fractional Calculus (FC) are emphasized.
  • 6
  • 06 Oct 2022
Topic Review
Competitive Swimwear
Competitive swimwear refers to the swimsuit, clothing, equipment, and accessories used in the aquatic sports of swimming, diving, synchronized swimming, triathlon, and water polo. Some swimsuits are designed specifically for swimming competitions where they may be constructed of a special low resistance fabric that reduces skin drag. For some kinds of swimming and diving, special bodysuits called "diveskins" are worn. These suits are made from spandex and provide little thermal protection, but they do protect the skin from stings and abrasion. Most competitive swimmers also wear special swimsuits including partial bodysuits, racerback styles, jammers and racing briefs to assist their glide through the water thus gaining a speed advantage. Unlike regular swimsuits, which are designed mainly for the aesthetic appearances, swimsuits designed to be worn during competitions are manufactured to assist the athlete in swim competitions. They reduce friction and drag in the water, increasing the efficiency of the swimmer's forward motion. The tight fits allow for easy movement and are said to reduce muscle vibration, thus reducing drag. This also reduces the possibility that a high forwards dive will remove a divers swimwear. Starting around 2000, in an effort to improve the effectiveness of the swimsuits, engineers have taken to designing them to replicate the skin of sea-based animals, sharks in particular. In July 2009, FINA voted to ban non-textile (non-woven) swimsuits in competitive events from 2010. The new policy was implemented to combat the issues associated with performance enhancing swimsuits, hindering the ability to accurately measure the performance of swimmers. Subsequently, the new ruling states that men's swimsuits may maximally cover the area from the navel to the knee, and women's counterparts from the shoulder to the knee. Some swimmers use a specialized training suit called drag suits to artificially increase drag during practice. Drag suits are swimwear with an outer layer of looser fabric – often mesh or nylon – to increase resistance against the water and build up the swimmer's endurance. They come in a variety of styles, but most resemble a looser fitting square-cut or swim brief.
  • 7
  • 06 Oct 2022
Topic Review
List of Gliders (G)
This is a list of gliders/sailplanes of the world, (this reference lists all gliders with references, where available) Note: Any aircraft can glide for a short time, but gliders are designed to glide for longer.
  • 8
  • 06 Oct 2022
Topic Review
Zellige
Zellige (Arabic: [zˈliʑ]; Arabic: الزليج; also zelige or zellij) is mosaic tilework made from individually chiseled geometric tiles set into a plaster base. This form of Islamic art is one of the main characteristics of Moroccan architecture. It consists of geometrically patterned mosaics, used to ornament walls, ceilings, fountains, floors, pools and tables.
  • 7
  • 06 Oct 2022
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