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Topic Review
The NIST World Trade Center Disaster Investigation
The National Construction Safety Team Act (NCST Act), signed into law on October 1, 2002 by President George W. Bush, mandated the National Institute of Standards and Technology (NIST) to establish the likely technical cause or causes of the three building failures that occurred on September 11, 2001 at the World Trade Center as a result of a terrorist attack. NIST issued its final report on the collapse of the World Trade Center Twin Towers in September 2005. It issued its final report on 7 World Trade Center in November 2008. NIST concluded that the collapse of each tower resulted from the combined effects of airplane impact damage, widespread fireproofing dislodgment, and the fires that ensued. The sequence of failures that NIST concluded initiated the collapse of both towers involved the heat-induced sagging of floor trusses pulling some of the exterior columns on one side of each tower inward until they buckled, after which instability rapidly spread and the upper sections then fell onto the floors below. World Trade Center Building 7 (7WTC), which was never directly hit by an airplane, collapsed as a result of thermal expansion of steel beams and girders that were heated by uncontrolled fires caused by the collapse of the North Tower and failure of the fire-resistive material.
  • 4.4K
  • 24 Nov 2022
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.
  • 4.4K
  • 07 Oct 2022
Topic Review
Epoxides Cycloaddition for CO2 Utilization
In the present review (10.3390/pr8050548), CO2 cycloaddition can be seen as a reasonably competent alternative to CO2 transformation, offsetting the high value-added nature by extending material use defer CO2 back to the atmosphere when compared to commodities and fuels such as urea, methanol, and methane.
  • 4.4K
  • 27 Aug 2020
Topic Review
Sakia
A saqia, alternative spelling sakieh, saqia or saqiya (from Arabic: ساقية, sāqiyah), also called Persian wheel, tablia, rehat, and in Latin tympanum is a mechanical water lifting device, similar in function to a scoop wheel, which uses buckets, jars, or scoops fastened either directly to a vertical wheel, or to an endless belt activated by such a wheel. The vertical wheel is itself attached by a drive shaft to a horizontal wheel, which is traditionally set in motion by animal power (oxen, donkeys, etc.) Because it is not using the power of flowing water, the sakia is different from a noria and any other type of water-wheel. It is still used in India , Egypt and other parts of the Middle East, and in the Iberian Peninsula and the Balearic Islands. It may have been invented in Hellenistic Egypt, Persia or India . The sakia was mainly used for irrigation, but not exclusively, as the example of Qusayr Amra shows, where it was used at least in part to provide water for a royal bathhouse.
  • 4.3K
  • 23 Nov 2022
Topic Review
Areal Density (Computer Storage)
Areal density is a measure of the quantity of information bits that can be stored on a given length of track, area of surface, or in a given volume of a computer storage medium. Generally, higher density is more desirable, for it allows more data to be stored in the same physical space. Density therefore has a direct relationship to storage capacity of a given medium. Density also generally affects the performance within a particular medium, as well as price.
  • 4.3K
  • 22 Nov 2022
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
  • 4.3K
  • 16 Nov 2022
Topic Review
Urban Wastewater Treatment in Greece
Although Greece has accomplished the wastewater infrastructure construction in a large extent, as 91% of the country’s population is already connected to urban wastewater treatment plants (WWTPs), many problems still need to be faced, such as the limited reuse of treated wastewater and of the surplus sludge (biosolids) produced, the relative higher energy consumption in the existing rather aged WWTPs infrastructure and the proper management of failing or inadequately designed septic tank/soil absorption systems, still in use in several (mostly rural) areas, lacking sewerage systems. Moreover, the wastewater treatment sector should be examined in the general framework of sustainable environmental development; therefore, Greece’s future challenges in this sector ought to be reconsidered. Thus, the review of Greece’s urban wastewater history, even from the ancient times, up to current developments and trends, will be shortly addressed. Noting also that the remaining challenges should be analyzed in respect to the country’s specific needs (e.g. interaction with the extensive tourism sector), as well as to the European Union’s relevant framework policies and to the respective international technological trends, aiming to consider the wastewater treatment plants (WWTPs) not only as sites for the treatment/removal of pollutants to prevent environmental pollution, but also as industrial places where energy is efficiently used (or even produced), resources’ content can be potentially recovered and reused (e.g. nutrients, treated water, biosolids) and the environmental sustainability is being overall practiced.
  • 4.3K
  • 04 Aug 2020
Topic Review
Structure from Motion
Structure from Motion (SfM) is a photogrammetric range imaging technique for estimating three-dimensional structures from two-dimensional image sequences that may be coupled with local motion signals. It is studied in the fields of computer vision and visual perception. In biological vision, SfM refers to the phenomenon by which humans (and other living creatures) can recover 3D structure from the projected 2D (retinal) motion field of a moving object or scene.
  • 4.3K
  • 06 Oct 2022
Topic Review
LCD Projector
An LCD projector is a type of video projector for displaying video, images or computer data on a screen or other flat surface. It is a modern equivalent of the slide projector or overhead projector. To display images, LCD (liquid-crystal display) projectors typically send light from a metal-halide lamp through a prism or series of dichroic filters that separates light to three polysilicon panels – one each for the red, green and blue components of the video signal. As polarized light passes through the panels (combination of polarizer, LCD panel and analyzer), individual pixels can be opened to allow light to pass or closed to block the light. The combination of open and closed pixels can produce a wide range of colors and shades in the projected image. Metal-halide lamps are used because they output an ideal color temperature and a broad spectrum of color. These lamps also have the ability to produce an extremely large amount of light within a small area; current projectors average about 2,000 to 15,000 American National Standards Institute (ANSI) lumens. Other technologies, such as Digital Light Processing (DLP) and liquid crystal on silicon (LCOS) are also becoming more popular in modestly priced video projection.
  • 4.2K
  • 04 Nov 2022
Topic Review
Apple Fermented Products
Fermentation is a process of transforming one substance into another, carried out by microorganisms, such as bacteria and fungi, under certain circumstances, and which can occur under aerobic and/or anaerobic conditions.
  • 4.2K
  • 18 Mar 2021
Topic Review
Carbon Fiber Reinforced Polymer
Carbon fiber reinforced polymer (American English), Carbon fibre reinforced polymer (Commonwealth English), or carbon fiber reinforced plastic, or carbon fiber reinforced thermoplastic (CFRP, CRP, CFRTP, or often simply carbon fiber, carbon composite, or even carbon), is an extremely strong and light fiber-reinforced plastic which contains carbon fibers. The spelling 'fibre' is typically used outside the US. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and stiffness (rigidity) are required, such as aerospace, superstructures of ships, automotive, civil engineering, sports equipment, and an increasing number of consumer and technical applications. The binding polymer is often a thermoset resin such as epoxy, but other thermoset or thermoplastic polymers, such as polyester, vinyl ester, or nylon, are sometimes used. The composite material may contain aramid (e.g. Kevlar, Twaron), ultra-high-molecular-weight polyethylene (UHMWPE), aluminium, or glass fibers in addition to carbon fibers. The properties of the final CFRP product can also be affected by the type of additives introduced to the binding matrix (resin). The most common additive is silica, but other additives such as rubber and carbon nanotubes can be used. The material is also referred to as graphite-reinforced polymer or graphite fiber-reinforced polymer (GFRP is less common, as it clashes with glass-(fiber)-reinforced polymer).
  • 4.2K
  • 28 Nov 2022
Topic Review
List of Intel Core I7 Microprocessors
The following is a list of Intel Core i7 brand microprocessors. Introduced in 2008, the Core i7 line of microprocessors are intended to be used by high-end users.
  • 4.2K
  • 24 Nov 2022
Topic Review
Panel Van
A panel van (or panelvan) is a form of solid (rigid-bodied, non-articulated) van, smaller than a lorry or truck, without rear side windows. In the UK this body style is referred to as a "car-derived van" and in North American as a "sedan delivery" (while the term "panel van" or "cargo van" generally refers to larger, truck-based vans such as the Ford E-Series and Chevrolet Express). In Australia panel vans were a development of the Australian "ute" (utility), a variety of pickup, based on a car chassis, these often utilizing the floorpan of the station wagon model. In North America a two-door station wagon base was used with only front seats and steel sheet-metal panels in place of the rear and side windows. Panel vans are widely used in many parts of the world for transporting cargo. In some national usages it is distinct from a purpose-designed van in that it is based on the chassis of a family car design. In places where they are distinct from a "van", they have less cargo space but better agility and maneuverability, making them particularly suited for cities with narrow streets or heavy traffic.
  • 4.2K
  • 11 Nov 2022
Topic Review
Centrifugal Fan
A centrifugal fan is a mechanical device for moving air or other gases in a direction at an angle to the incoming fluid. Centrifugal fans often contain a ducted housing to direct outgoing air in a specific direction or across a heat sink; such a fan is also called a blower, blower fan, biscuit blower, or squirrel-cage fan (because it looks like a hamster wheel). These fans increase the speed and volume of an air stream with the rotating impellers. Centrifugal fans use the kinetic energy of the impellers to increase the volume of the air stream, which in turn moves against the resistance caused by ducts, dampers and other components. Centrifugal fans displace air radially, changing the direction (typically by 90°) of the airflow. They are sturdy, quiet, reliable, and capable of operating over a wide range of conditions. Centrifugal fans are constant-displacement or constant-volume devices, meaning that, at a constant fan speed, a centrifugal fan moves a relatively constant volume of air rather than a constant mass. This means that the air velocity in a system is fixed even though the mass flow rate through the fan is not. Centrifugal fans are not positive-displacement devices and centrifugal fans have certain advantages and disadvantages when contrasted with positive-displacement blowers: centrifugal fans are more efficient, whereas positive-displacement blowers may have a lower capital cost. The centrifugal fan has a drum shape composed of a number of fan blades mounted around a hub. As shown in the animated figure, the hub turns on a driveshaft mounted in bearings in the fan housing. The gas enters from the side of the fan wheel, turns 90 degrees and accelerates due to centrifugal force as it flows over the fan blades and exits the fan housing.
  • 4.2K
  • 23 Oct 2022
Topic Review
King Abdulaziz International Airport
King Abdulaziz International Airport (KAIA) (Arabic: مطار الملك عبدالعزيز الدولي) (IATA: JED, ICAO: OEJN) is a Saudi international airport located 19 km to the north of Jeddah. Named after King Abdulaziz Al Saud and inaugurated in 1981, the airport is the busiest airport of Saudi Arabia and the third-largest airport in the kingdom. The airport's Hajj Terminal was specially built for Muslim pilgrims going to Mecca annually on the Hajj. It is one of the largest in the world, and can handle 80,000 passengers at the same time.
  • 4.1K
  • 23 Nov 2022
Topic Review
Powered Hang Glider
A foot-launched powered hang glider (FLPHG), also called powered harness, nanolight, or hangmotor, is a powered hang glider harness with a motor and propeller in pusher configuration. An ordinary hang glider is used for its wing and control frame, and the pilot can foot-launch from a hill or from flat ground, needing a length of about a football field to get airborne, or much less if there is an oncoming breeze and no obstacles.
  • 4.1K
  • 04 Nov 2022
Topic Review
Variable-Pitch Propeller
A variable-pitch propeller or controllable-pitch propeller (CPP) is a type of propeller with blades that can be rotated around their long axis to change the blade pitch. Reversible propellers—those where the pitch can be set to negative values—can also create reverse thrust for braking or going backwards without the need to change the direction of shaft revolution.
  • 4.1K
  • 23 Nov 2022
Topic Review
Frying
Frying is one of the oldest unit operations to produce food products with a crisp texture, an aromatic flavour and a golden-brown colour. Deep-fried foods such as French fries, potato/veggie crisps are popular among consumers. Detailed insights into the frying process in terms of heat, mass (water and oil) and momentum transfers are outlined in this entry.
  • 4.1K
  • 28 Jul 2020
Topic Review
Springfield Armory XDM
The Springfield Armory XDM (X-Treme Duty, the M is for the match grade barrel and match grade trigger) are a series of semi-automatic pistols that are polymer-framed and striker-fired. They closely resemble their predecessor, the HS2000 pistol (most widely known in the United States as Springfield Armory XD). Manufactured in the city of Karlovac, Croatia by HS Produkt (formerly I.M. Metal), the Springfield Armory XDM is the marketing name for the firearm, which is licensed and sold in the United States by Springfield Armory, Inc..
  • 4.0K
  • 25 Oct 2022
Topic Review
EPR (Nuclear Reactor)
The EPR is a third generation pressurised water reactor (PWR) design. It has been designed and developed mainly by Framatome (part of Areva between 2001 and 2017) and Électricité de France (EDF) in France, and Siemens in Germany. In Europe this reactor design was called European Pressurised Reactor, and the internationalised name was Evolutionary Power Reactor, but it is now simply named EPR. The first two EPR units, at Olkiluoto in Finland and Flamanville in France, are both facing costly construction delays (to at least 2019). Construction commenced on two Chinese units at Taishan in 2009 and 2010. Taishan 1 achieved criticality on 6 June 2018. Taishan 2 is expected to begin operation in 2019. Two units at Hinkley Point in the United Kingdom received final approval in September 2016 and are expected to be completed by 2025. EDF has acknowledged severe difficulties in building the EPR design. In September 2015 EDF stated that the design of a "New Model" EPR was being worked on, which will be easier and cheaper to build.
  • 4.0K
  • 15 Nov 2022
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