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Topic Review
Metamaterial-Based Absorptive Structures
Metamaterials are artificially-engineered synthetic materials having periodic arrangements of sub-wavelength metallic/dielectric structures or resonators. Metamaterials have demanded a lot of recognition, due to their exotic and unique attributes such as negative-refraction, microwave cloaking, absorption of the inverse Doppler effect, etc. After the investigation of the first ‘perfect meta-absorber’ proposed in 2008, metamaterial absorbers (MMAs) have drawn significant interest from the microwave and optics community. These MMAs have multifarious features compared with the conventional Salisbury absorbers, such as a low-profile and light weight. Moreover, they are thinner, more compact, and more efficient than conventional absorbers. They have many applications for wireless communication and other optical systems, including MIMO antenna isolation, EM interference reduction, stealth technology, and solar photovoltaics.
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Topic Review
Grasshopper (Rocket)
Grasshopper and the Falcon 9 Reusable Development Vehicles (F9R Dev) were experimental flight test reusable rockets that performed vertical takeoffs and landings. The project was privately funded by SpaceX, with no funds provided by any government until later on. Two prototypes were built, and both were launched from the ground. Grasshopper was announced in 2011 and began low-altitude, low-velocity hover/landing testing in 2012. The initial Grasshopper test vehicle was 106 ft (32 m) tall and made eight successful test flights in 2012 and 2013 before being retired. A second Grasshopper-class prototype was the larger and more capable Falcon 9 Reusable Development Vehicle (F9R Dev, also known as F9R Dev1) based on the Falcon 9 v1.1 launch vehicle. It was tested at higher altitudes and was capable of much higher velocity but was never tested at high velocity. The F9R Dev1 vehicle was built in 2013–2014 and made its first low-altitude flight test on 17 April 2014; it was lost during a three-engine test at the McGregor test site on 22 August 2014, which ended the low-velocity test program. Further expansion of the flight test envelope for the reusable rocket was moved to descending Falcon 9 boosters that had been used on orbital flight trajectories on commercial orbital flights of the Falcon 9. The Grasshopper and F9R Dev tests were fundamental to the development of the reusable Falcon 9 and Falcon Heavy rockets, which require vertical landings of the near-empty Falcon 9 and Falcon Heavy first-stage booster tanks and engine assemblies. The Grasshopper and the F9R Dev tests led into a series of high-altitude, high-speed controlled-descent tests of post-mission (spent) Falcon 9 booster stages that accompanied the commercial Falcon 9 missions since September 2013. The latter eventually resulted in the first successful booster landing on 21 December 2015.
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Topic Review
Radar Configurations and Types
Radar configurations and types is an article about listing the different uses of radars.
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Biography
Ambrose Swasey
Ambrose Swasey (December 19, 1846 – June 15, 1937) was an United States mechanical engineer, inventor, entrepreneur, manager, astronomer, and philanthropist. With Worcester R. Warner he co-founded the Warner & Swasey Company. Swasey was born near Exeter, New Hampshire [1] to Nathaniel and Abigail Swasey. He apprenticed as a machinist at the Exeter Machine Works and was afterwards employed a
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Biography
Thomas J.R. Hughes
Thomas Joseph Robert Hughes (born 1943) is a Professor of Aerospace Engineering and Engineering Mechanics and currently holds the Computational and Applied Mathematics Chair III in the Institute for Computational Engineering and Sciences at The University of Texas at Austin.[1][2] Hughes has been listed as an ISI Highly Cited Author in Engineering by the ISI Web of Knowledge, Thomson Scientific
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Biography
Michael J. McCulley
Michael James "Mike" McCulley (born August 4, 1943), (Capt, USN, Ret.), is a retired American naval officer and aviator, test pilot, metallurgical engineer, former NASA astronaut, and was the first submariner in space. Born August 4, 1943, in San Diego, California, but considers Livingston, Tennessee to be his hometown. Married to the former Jane Emalie Thygeson of Melbourne, Florida. Six chi
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Biography
Rube Goldberg
File:Something for nothing (1940).ogv Reuben Garrett Lucius Goldberg (July 4, 1883 – December 7, 1970), known best as Rube Goldberg, was an American cartoonist, sculptor, author, engineer, and inventor. Goldberg is best known for a series of popular cartoons depicting complicated gadgets that perform simple tasks in indirect, convoluted ways, giving rise to the term Rube Goldberg machines for
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Topic Review
Cartridge (Respirator)
}} A respirator cartridge or canister is a container that cleans pollution from air. Employees working in a polluted atmosphere use respirators for health preservation. If the air in the workplace is polluted with noxious gases, but contains a lot of oxygen they often use air-purifying respirators (APR). These respirators provide employees breathable air by removing pollution from ambient air using canisters or cartridges. There are cartridges of different types, and they must be chosen correctly and replaced in a timely manner.
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Topic Review
IP Code
The IP Code, International Protection Marking, IEC standard 60529, sometimes interpreted as Ingress Protection Marking, classifies and rates the degree of protection provided against intrusion (body parts such as hands and fingers), dust, accidental contact, and water by mechanical casings and electrical enclosures. It is published by the International Electrotechnical Commission (IEC). The equivalent European standard is EN 60529. The standard aims to provide users more detailed information than vague marketing terms such as waterproof. For example, a cellular phone rated at IP68 is "dust resistant" and can be "immersed in 1.5 meters of freshwater for up to 30 minutes". Similarly, an electrical socket rated IP22 is protected against insertion of fingers and will not be damaged or become unsafe during a specified test in which it is exposed to vertically or nearly vertically dripping water. IP22 or IP2X are typical minimum requirements for the design of electrical accessories for indoor use. The digits indicate conformity with the conditions summarized in the tables below. The digit 0 is used where no protection is provided. The digit is replaced with the letter X when insufficient data has been gathered to assign a protection level. There are no hyphens in a genuine IP code. IPX-8 (for example) is thus an invalid IP code. This page contains a combination of IEC 60529 (also EN 60529) and other standards, such as ISO 20653. The original documents are available for purchase, and have important and specific requirements that cannot be fully reprinted due to copyright restrictions. This often includes drawings specifying the required test equipment, such as the shape of water nozzles used for water jet testing. Additional standards are often referenced that may contain important information. One must refer to the latest revision of the required standard when conducting tests for agency certification.
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Topic Review
Power-System Protection
Power-system protection is a branch of electrical power engineering that deals with the protection of electrical power systems from faults through the disconnection of faulted parts from the rest of the electrical network. The objective of a protection scheme is to keep the power system stable by isolating only the components that are under fault, whilst leaving as much of the network as possible still in operation. Thus, protection schemes must apply a very pragmatic and pessimistic approach to clearing system faults. The devices that are used to protect the power systems from faults are called protection devices.
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