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Biography
George Robert Carruthers
George Robert Carruthers (born October 1, 1939) is an award-winning African-American inventor, physicist, and space scientist. Carruthers invented the ultraviolet camera/spectograph for NASA to use when it launched Apollo 16 in 1972. His work also demonstrated that molecular hydrogen exists in the interstellar medium. In 2003, Carruthers was inducted into the National Inventor's Hall of Fame. He
  • 1.7K
  • 15 Nov 2022
Topic Review
U-Boat Campaign (World War I)
The U-boat Campaign from 1914 to 1918 was the World War I naval campaign fought by German U-boats against the trade routes of the Allies. It took place largely in the seas around the British Isles and in the Mediterranean. The German Empire relied on imports for food and domestic food production (especially fertilizer) and the United Kingdom relied heavily on imports to feed its population, and both required raw materials to supply their war industry; the powers aimed, therefore, to blockade one another. The British had the Royal Navy which was superior in numbers and could operate on most of the world's oceans because of the British Empire, whereas the Imperial German Navy surface fleet was mainly restricted to the German Bight, and used commerce raiders and unrestricted submarine warfare to operate elsewhere. In the course of events in the Atlantic alone, German U-boats sank almost 5,000 ships with nearly 13 million gross register tonnage, losing 178 boats and about 5,000 men in combat. Other naval theatres saw U-boats operating in both the Far East and South East Asia, the Indian Ocean and the Mediterranean and North Seas.
  • 1.6K
  • 06 Dec 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.
  • 1.6K
  • 19 Oct 2022
Topic Review
Kīla (Buddhism)
The kīla or phurba (Sanskrit Devanagari: कील; IAST: kīla; Tibetan: ཕུར་པ or ཕུར་བ, Wylie: phur ba, alternate transliterations and English orthographies: phurpa, phurbu, purbha, or phurpu) is a three-sided peg, stake, knife, or nail-like ritual implement traditionally associated with Indo-Tibetan Buddhism, Bön, and Indian Vedic traditions. The kīla is associated with the practice of the yidam (Sanskrit ishtadevata, Tibetan yidam) or meditational deity Vajrakīla (वज्रकील) or Vajrakīlaya (Tibetan Dorje Phurba).
  • 1.6K
  • 23 Nov 2022
Topic Review
Parliamentary Train
A Parliamentary train is a passenger service operated in the United Kingdom to comply with the Railway Regulation Act 1844 that required train companies to provide inexpensive and basic rail transport for less affluent passengers. The act required that at least one such service per day be run on every railway route in the UK. Now no longer a legal requirement (although most franchise agreements require such trains), the term describes train services that continue to be run to avoid the cost of formal closure of a route or station but with reduced services often to just one train per week and without specially low prices. Such services are often called "ghost trains".
  • 1.6K
  • 10 Nov 2022
Topic Review
Fluorescence Polarization-Based Bioassays
Fluorescence polarization holds considerable promise for bioanalytical systems because it allows the detection of selective interactions in real time and a choice of fluorophores, the detection of which the biosample matrix does not influence; thus, their choice simplifies and accelerates the preparation of samples. For decades, these possibilities were successfully applied in fluorescence polarization immunoassays based on differences in the polarization of fluorophore emissions excited by plane-polarized light, whether in a free state or as part of an immune complex. However, the results of recent studies demonstrate the efficacy of fluorescence polarization as a detected signal in many bioanalytical methods.
  • 1.6K
  • 17 Dec 2020
Topic Review
Loss-of-Coolant Accident
A loss-of-coolant accident (LOCA) is a mode of failure for a nuclear reactor; if not managed effectively, the results of a LOCA could result in reactor core damage. Each nuclear plant's emergency core cooling system (ECCS) exists specifically to deal with a LOCA. Nuclear reactors generate heat internally; to remove this heat and convert it into useful electrical power, a coolant system is used. If this coolant flow is reduced, or lost altogether, the nuclear reactor's emergency shutdown system is designed to stop the fission chain reaction. However, due to radioactive decay, the nuclear fuel will continue to generate a significant amount of heat. The decay heat produced by a reactor shutdown from full power is initially equivalent to about 5 to 6% of the thermal rating of the reactor. If all of the independent cooling trains of the ECCS fail to operate as designed, this heat can increase the fuel temperature to the point of damaging the reactor. Under operating conditions, a reactor may passively (that is, in the absence of any control systems) increase or decrease its power output in the event of a LOCA or of voids appearing in its coolant system (by water boiling, for example). This is measured by the coolant void coefficient. Most modern nuclear power plants have a negative void coefficient, indicating that as water turns to steam, power instantly decreases. Two exceptions are the Soviet RBMK and the Canadian CANDU. Boiling water reactors, on the other hand, are designed to have steam voids inside the reactor vessel. Modern reactors are designed to prevent and withstand loss of coolant, regardless of their void coefficient, using various techniques. Some, such as the pebble bed reactor, passively slow down the chain reaction when coolant is lost; others have extensive safety systems to rapidly shut down the chain reaction, and may have extensive passive safety systems (such as a large thermal heat sink around the reactor core, passively-activated backup cooling/condensing systems, or a passively cooled containment structure) that mitigate the risk of further damage.
  • 1.6K
  • 09 Oct 2022
Topic Review
Indefinite Lifespan
Indefinite lifespan (also known as indefinite life extension or bio-indefinite) is a term used in the life extension movement and transhumanism to refer to the hypothetical longevity of humans (and other life-forms) under conditions in which ageing is effectively and completely prevented and treated. Their lifespans would be "indefinite" (that is, they would not be "immortal"), because protection from the effects of aging on health does not guarantee survival. Such individuals would still be susceptible to death by disease, starvation, accidents, or deliberate killing, but not death from aging. Semantically, "indefinite lifespan" is more accurate than "immortality" which, especially in religious contexts, implies an inability to die.
  • 1.6K
  • 26 Oct 2022
Topic Review
Goal (Sport)
In sports, a goal is a physical structure or area where an attacking team must send the ball or puck in order to score points. In several sports, a goal is the sole method of scoring, and thus the final score is expressed in the total number of goals scored by each team. In other sports, a goal may be one of several scoring methods, and thus may be worth a different set number of points than the others. The structure of a goal varies from sport to sport. Most often, it is a rectangular structure that is placed at each end of the playing field. Each structure usually consists of two vertical posts, called goal posts, supporting a horizontal crossbar. A goal line marked on the playing surface between the goal posts demarcates the goal area. Thus, the objective is to send the ball or puck between the goal posts, under or over the crossbar (depending on the sport), and across the goal line. Less commonly, as in basketball or netball, goals are ring-shaped. The structure is often accompanied with an auxiliary net, which stops or slows down the ball when a goal is scored.
  • 1.6K
  • 11 Nov 2022
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.
  • 1.6K
  • 01 Nov 2022
Topic Review
RBS-15
The RBS-15 (Robotsystem 15) is a long-range fire-and-forget surface-to-surface and air-to-surface anti-ship missile. The later version Mk. III has the ability to attack land targets as well. The missile was developed by the Swedish company Saab Bofors Dynamics.
  • 1.6K
  • 01 Dec 2022
Topic Review
Blue Gene
Blue Gene is an IBM project aimed at designing supercomputers that can reach operating speeds in the PFLOPS (petaFLOPS) range, with low power consumption. The project created three generations of supercomputers, Blue Gene/L, Blue Gene/P, and Blue Gene/Q. Blue Gene systems have often led the TOP500 and Green500 rankings of the most powerful and most power efficient supercomputers, respectively. Blue Gene systems have also consistently scored top positions in the Graph500 list. The project was awarded the 2009 National Medal of Technology and Innovation. As of 2015, IBM seems to have ended the development of the Blue Gene family though no public announcement has been made. IBM's continuing efforts of the supercomputer scene seems to be concentrated around OpenPower, using accelerators such as FPGAs and GPUs to battle the end of Moore's law.
  • 1.6K
  • 29 Sep 2022
Topic Review
Frédérique Constant
Frédérique Constant SA is a Swiss manufacture of luxury wristwatches based in Plan-les-Ouates, Geneva. It was acquired in 2016 by Citizen Holdings of Tokyo, Japan. The company was established in 1988 by Peter Stas and Aletta Stas-Bax (a Dutch married couple). Before the sale to Citizen, Frédérique Constant SA was owned by Union Horlogère Holding B.V., which also owned Alpina Watches International SA, and Ateliers deMonaco SA, and was, in turn, owned by Frédérique Constant Holding SA.
  • 1.5K
  • 24 Oct 2022
Topic Review
GNSS Denied Environments
The GNSS information is vulnerable to external interference and causes failure when unmanned aerial vehicles (UAVs) are in a fully autonomous flight in complex environments such as high-rise parks and dense forests. This paper presents a pan-tilt based visual servoing (PBVS) method for obtaining world coordinate information. The system is equipped with an Inertial Measurement Unit (IMU), an air pressure sensor, a magnetometer, and a pan-tilt-zoom(PTZ) camera. In this paper, we explain the physical model and the application method of the PBVS system which can be briefly summarized as follows. We track the operation target with a UAV carrying a camera and output the information about the UAV's position and the angle between the PTZ and the anchor point. In this way, we can obtain the current absolute position information of the UAV with its absolute altitude collected by the height sensing unit and absolute geographic coordinate information and altitude information of the tracked target. We have set up an actual UAV experimental environment. In order to meet the calculation requirements, some sensor data will be sent to the cloud through the network.Through the field tests, it can be concluded that the systematic deviation of the overall solution is less than the error of ordinary GNSS sensor equipment, and it can provide navigation coordinate information for the UAV in complex environments. Compared with traditional visual navigation systems, our scheme has the advantage of obtaining absolute, continuous, accurate and efficient navigation information in a short distance (within 15m from the target). This system can be used in scenarios that require autonomous cruise, such as self-powered inspections of UAVs, patrols in parks, etc.
  • 1.5K
  • 30 Oct 2020
Topic Review
Lithium-Sulfur Redox Battery
The lithium-sulfur (Li-S) redox battery system is considered to be the most promising next-generation energy storage technology due to its high theoretical specific capacity (1673 mAh/g), high energy density (2600 Wh/kg), low cost, and environmentally friendly nature of sulfur. Though this system is deemed to be the next-generation energy storage device for portable electronics and electric vehicles, its poor cycle life, low coulombic efficiency, and low rate capability limit it from practical applications. These performance barriers were linked to several issues like polysulfide (LiPS) shuttle, inherent low conductivity of charge/discharge end products, and poor redox kinetics. Here, we review the recent developments made to alleviate these problems through an electrocatalysis approach, which is considered to be an effective strategy not only to trap the LiPS but also to accelerate their conversion reactions kinetics. Herein, the influence of different chemical interactions between the LiPS and the catalyst surfaces and their effect on the conversion of liquid LiPS to solid end products are reviewed. Finally, we also discussed the challenges and perspectives for designing cathode architectures to enable high sulfur loading along with the capability to rapidly convert the LiPS.
  • 1.5K
  • 21 Oct 2020
Biography
Hugh Herr
Hugh Herr (born October 25, 1964) is an American rock climber, engineer, and biophysicist. The youngest of five siblings of a Mennonite family from Lancaster, Pennsylvania, Hugh Herr was a prodigy rock climber: by age eight, he had scaled the face of the 11,627-foot (3,544 m) Mount Temple in the Canadian Rockies, and by 17 he was acknowledged to be one of the best climbers in the United Stat
  • 1.5K
  • 10 Nov 2022
Topic Review
Homemade Firearm
Homemade firearms are small improvised firearms built by individuals from kits or other equipment, which are generally excepted from commercial firearms markets or regulations. The phenomenon is most popular in the United States , where it is a political issue for gun control advocates, gun rights advocates, and law enforcement. Homemade guns are in general legal. Homemade guns are generally not subject to federal or state commercial background check regulations.
  • 1.5K
  • 18 Oct 2022
Topic Review
Treatment Methods of SC
Sulfur compounds(SC) are removed from petroleum by the addition of sodium hydroxide at a very high concentration. As a result, a residue called spent soda or spent caustic is generated, being extremely aggressive to the environment. In this work, the chemical properties of this residue are described in detail. The sodium hydroxide remains that have not reacted, sulfur compounds, and organic matter are the primary pollutants reported. Additionally, the main characteristics of the methods of treatment used to reduce them are described.
  • 1.5K
  • 14 Jan 2021
Topic Review
Electric Turbo Compound
An Electric Turbo Compound (ETC) system is defined where a turbine coupled to a generator (turbogenerator) is located in the exhaust gas flow of a reciprocating engine to harvest waste heat energy and convert it into electrical power. An example of an ETC system is where a turbogenerator is located downstream of a turbocharger turbine of an Internal Combustion Engine (ICE). The power generated from the ETC system can be used to feed into an electrical grid or provide power to local electrical loads such as engine auxiliaries. ETC systems are commercially available for stationary power gensets and at an advanced stage of development for automotive applications as a solution to the challenge of improving the fuel efficiency of gas and diesel engines by recovering waste energy from the exhaust gases.
  • 1.5K
  • 25 Oct 2022
Topic Review
Mini Clubman
The Mini Clubman is a supermini engineered and manufactured by BMW and sold under the Mini marque. The first-generation Clubman was introduced in 2007, as a variant of the Mini Hatch (Hardtop in the US). A commercial version called Clubvan was added to the range in 2012. The current second-generation model is produced since 2015 and available with front- and all-wheel drive.
  • 1.5K
  • 29 Nov 2022
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