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Topic Review
Secondary Treatment
Secondary treatment is a treatment process for wastewater (or sewage) to achieve a certain degree of effluent quality by using a sewage treatment plant with physical phase separation to remove settleable solids and a biological process to remove dissolved and suspended organic compounds. After this kind of treatment, the wastewater may be called as secondary-treated wastewater. Secondary treatment is the portion of a sewage treatment sequence removing dissolved and colloidal compounds measured as biochemical oxygen demand (BOD). Secondary treatment is traditionally applied to the liquid portion of sewage after primary treatment has removed settleable solids and floating material. Secondary treatment is typically performed by indigenous, aquatic microorganisms in a managed aerobic habitat. Bacteria and protozoa consume biodegradable soluble organic contaminants (e.g. sugars, fats, and organic short-chain carbon molecules from human waste, food waste, soaps and detergent) while reproducing to form cells of biological solids. Biological oxidation processes are sensitive to temperature and, between 0 °C and 40 °C, the rate of biological reactions increase with temperature. Most surface aerated vessels operate at between 4 °C and 32 °C.
  • 2.3K
  • 08 Nov 2022
Topic Review
Diamond DA20
The Diamond DV20/DA20 Katana is an Austrian-designed two-seat tricycle gear general aviation light aircraft. Developed and manufactured by Austrian aircraft manufacturer Diamond Aircraft, it was originally produced in Austria as the DV20. The DV20 shares many features from the earlier Diamond HK36 Super Dimona. It was introduced to service during 1993. During the 1990s, production of the type was commenced at a new facility in Canada in order to meet demand for the type within the North American market. The Canadian-produced aircraft are designated as the DA20. It has been a relative success on the market, having sold in excess of 1,000 aircraft by 2008 and multiple improved variants of the DA20 have been developed. Additionally, it has been further developed into the four-seat Diamond DA40 Star.
  • 2.3K
  • 23 Nov 2022
Topic Review
Messerschmitt Me 321
The Messerschmitt Me 321 Gigant was a large German cargo glider developed and used during World War II. Intended to support large scale invasions, the Me 321 saw very limited use due to the low availability of suitable tug aircraft, high vulnerability whilst in flight and the difficult ground handling, both at base and at destination landing sites. The Me 321 was developed, in stages, into the six-engined Messerschmitt Me 323 Gigant, which removed some of the problems with ground handling, but vulnerability to ground fire and aerial attack remained a constant problem during operations of all variants.
  • 2.3K
  • 06 Dec 2022
Topic Review
Lunar Orbital Platform-Gateway
The Lunar Orbital Platform-Gateway (LOP-G) is a planned lunar-orbit space station that will serve as an all-in-one solar-powered communications hub, science laboratory, short-term habitation module, and holding area for rovers and other robots. The science disciplines to be studied on the Gateway are expected to include planetary science, astrophysics, Earth observations, heliophysics, fundamental space biology and human health and performance. The Gateway is designed to be developed, serviced, and utilized in collaboration with commercial and international partners. It will also serve as the staging point for crewed and robotic lunar exploration and a staging point for NASA's proposed Deep Space Transport craft to perform a 300-400 day shakedown mission prior to NASA's first crewed Mars mission. Deep Space Transport is a concept of a reusable vehicle that uses electric and chemical propulsion and would be specifically designed for crewed missions to destinations such as Mars. The development is led by the International Space Station partners: ESA, NASA, Roscosmos, JAXA and CSA for construction in the 2020s. The International Space Exploration Coordination Group (ISECG), which comprises 14 space agencies participating with NASA, have concluded that LOP-G will be critical in expanding human presence to the Moon, Mars and deeper into the solar system. Formerly known as the Deep Space Gateway, the station was renamed in NASA's proposal for the 2019 United States federal budget. The omnibus spending bill passed by Congress in March of 2018 provided NASA with $504 million for the development of LOP-G in fiscal year 2019.
  • 2.3K
  • 22 Nov 2022
Topic Review
Steam-Powered Vessels
Steam-powered vessels include steamboats and steamships. Smaller steamboats were developed first. They were replaced by larger steamships which were often ocean-going. Steamships required a change in propulsion technology from sail to paddlewheel to screw to steam turbines. The latter innovation changed the design of vessels to one that could move faster through the water. Engine propulsion changed to steam turbine in the early 20th century. In the latter part of the 20th century, these, in turn, were replaced by gas turbines. Steamship generally refers to larger steam-powered ships, usually ocean-going, capable of carrying a (ship's) boat. The SS Humboldt engine room, to the right, is a concept drawing during the construction of the ship. The term steam wheeler is archaic and rarely used. In England, "steam packet", after its sailing predecessor, was the usual term; even "steam barge" could be used (Steam tonnage in Lloyd's Register exceeded sailing ships tonnage by 1865). The French transatlantic steamer SS La Touraine was probably the last of her type to be equipped with sails, although she never used them. Steamships in turn were overtaken by diesel-driven ships in the second half of the 20th century. Most warships used steam propulsion from the 1860s until the late 20th century
  • 2.3K
  • 30 Nov 2022
Topic Review
Maruti Gypsy
The Maruti Gypsy is a four-wheel-drive vehicle based on the long wheelbase Suzuki Jimny SJ40/410 series. It is primarily an off-road vehicle, or a vehicle for rough unprepared roads. It was sold in New Zealand as the Suzuki Farm Worker. It was assembled at the Maruti Suzuki's Gurgaon plant in India.
  • 2.3K
  • 28 Oct 2022
Topic Review
Seaplane
A seaplane is a powered fixed-wing aircraft capable of taking off and landing (alighting) on water. Seaplanes are usually divided into two categories based on their technological characteristics: floatplanes and flying boats; the latter are generally far larger and can carry far more. Seaplanes that can also take off and land on airfields are in a subclass called amphibious aircraft, or amphibians. Seaplanes were sometimes called hydroplanes, but currently this term applies instead to motor-powered watercraft that use the technique of hydrodynamic lift to skim the surface of water when running at speed. The use of seaplanes gradually tapered off after World War II, partially because of the investments in airports during the war. In the 21st century, seaplanes maintain a few niche uses, such as for aerial firefighting, air transport around archipelagos, and access to undeveloped or roadless areas, some of which have numerous lakes.
  • 2.3K
  • 09 Nov 2022
Topic Review
City Cargo Transportation by Trams
A city’s transport and distribution system requires the effective organization of urban freight deliveries that take into consideration the economic, ecological, and social impact. Implementation of the concept of green logistics necessitates the use of environmentally friendly and energy-efficient modes of transport, which consider the existing infrastructure and the possibility of its development.
  • 2.2K
  • 09 Jun 2026
Topic Review
Detroit Diesel 60
The Detroit Diesel Series 60 is an inline-six 4 stroke diesel engine produced since 1987. At that time, it differed from most on-highway engines by using an overhead camshaft and "drive by wire" electronic control. In 1993, it was popular on many USA buses in the 11.1 L (677 cu in) displacement.
  • 2.2K
  • 07 Nov 2022
Topic Review
Time-of-day Traffic Signal Control
Improperly scheduled signal timing plans are one of the main reasons for reduced efficiency of traffic signals at coordinated urban arterials. Time-of-day (TOD) traffic signal control is based on the principle where multiple TOD signal timing plans (STPs) are scheduled to operate during the day. TOD plans are characterized by a unique cycle length that is highly correlated with traffic volumes. The determination of characteristic periods during the day where certain signal timing plans should operate was primarily done using the 24 h volume plots from single intersection and engineering judgments. In cases where data availability is higher, the analytical methods that serve for the determination of robust TOD breakpoints were not in place.
  • 2.2K
  • 27 Jun 2022
Topic Review
Factors Affecting Pavement Condition
The pavement experiences deterioration due to traffic and environment, i.e., unsatisfactory riding quality and structural inadequacy, over time. Thus, predicting pavement performance over time is one of the key elements of any pavement maintenance management system (PMMS).
  • 2.2K
  • 14 Jun 2022
Topic Review
Descent Propulsion System
The Descent Propulsion System (DPS) or Lunar Module Descent Engine (LMDE) is a variable-throttle hypergolic rocket engine developed by Space Technology Laboratories (TRW) for use in the Apollo Lunar Module Descent Stage. It used Aerozine 50 fuel and dinitrogen tetroxide (N2O4) oxidizer. This engine used a pintle injector, a design also used later in the SpaceX Merlin engine.
  • 2.2K
  • 18 Nov 2022
Topic Review
Earth Shelter
An earth shelter, also called an earth house, earth bermed house, or underground house, is a structure (usually a house) with earth (soil) against the walls, on the roof, or that is entirely buried underground. Earth acts as thermal mass, making it easier to maintain a steady indoor air temperature and therefore reduces energy costs for heating or cooling. Earth sheltering became relatively popular after the mid-1970s, especially among environmentalists. However, the practice has been around for nearly as long as humans have been constructing their own shelters.
  • 2.2K
  • 18 Oct 2022
Topic Review
Foundation (Engineering)
A foundation is the element of a structural engineering which connects it to the ground, and transfers loads from the structure to the ground. Foundations are generally considered either shallow or deep. Foundation engineering is the application of soil mechanics and rock mechanics (Geotechnical engineering) in the design of foundation elements of structures.
  • 2.2K
  • 08 Nov 2022
Topic Review
Ice Boat
An ice boat (often spelled as "iceboat") is a boat or purpose-built framework similar in functional design to a sail boat but fitted with skis or runners (skates) and designed to run over ice instead of through (liquid) water. Ice yachting is the sport of sailing and racing iceboats. Sail-able ice is known in the sport as "hard water" versus sailing on liquid or "soft" water. A related sport, land sailing, utilizes a configuration with an iceboat-like fuselage or frame equipped with wheels instead of runners. Iceboats commonly used for racing are usually only for one person, but several classes of two-seat and multiple-seat iceboats are more or less common. On some boats, a "side car" can be fitted to take others along for a ride.
  • 2.2K
  • 31 Oct 2022
Topic Review
N747PA
N747PA, was the registration of a Boeing 747-121. Also known as Clipper Juan T. Trippe, it was the second 747 ever built. It was purchased by Pan Am in 1970. Following an accident in 1971, the aircraft continued service with Pan Am until its collapse in 1991. It served as a freighter until 1997 when it was used as a source of spare parts. In 2000 it was purchased by a South Korean couple and converted into a restaurant. After laying abandoned for years following the restaurant's failure in 2005, the aircraft was finally scrapped in 2010.
  • 2.2K
  • 24 Oct 2022
Topic Review
Fiat G.50
The Fiat G.50 Freccia ("Arrow") was a World War II Italian fighter aircraft developed and manufactured by aviation company Fiat. Upon entering service, the type became Italy’s first single-seat, all-metal monoplane that had an enclosed cockpit and retractable undercarriage. On 26 February 1937, the G.50 conducted its maiden flight. During early 1938, the Freccias served in the Regia Aeronautica (the Italian Air Force) and with its expeditionary arm, the Aviazione Legionaria, in Spain, where they proved to be relatively fast and very manoeuvrable in comparison to its adversaries in the theatre. Early in the Second World War, it was determined that the G.50 possessed inadequate armament, comprising a pair of Breda-SAFAT 12.7-mm machine guns. The fighter was extensively used on various fronts by Italy, including in Northern Europe, North Africa, the Balkans, and the Italian mainland. The G.50 commonly came up against the British Hawker Hurricane, which was fast enough to frequently outrun and out-range the Italian opponent. Later models of the fighter had improvements, including a substantial increase in range. The G.50 was exported to several overseas customers, small numbers being flown by the Air Force of the Independent State of Croatia while 35 G.50 fighters were shipped to Finland , where they served with distinction during both the Winter War of 1940 and the Continuation War of 1941–1944 against the Soviet Union. In Finnish service, the type reportedly achieved an unprecedented kill/loss ratio of 33/1.
  • 2.2K
  • 08 Nov 2022
Topic Review
Ship Model Basin
A ship model basin is a basin or tank used to carry out hydrodynamic tests with ship models, for the purpose of designing a new (full sized) ship, or refining the design of a ship to improve the ship's performance at sea. It can also refer to the organization (often a company) that owns and operates such a facility. A ship model basin company is an engineering firm that acts as a contractor to the relevant shipyards, and provides hydrodynamic model tests and numerical calculations to support the design and development of ships and offshore structures.
  • 2.2K
  • 20 Oct 2022
Topic Review
Crowdsourcing Update Methods for High-Definition Maps
High-definition (HD) maps serve as crucial infrastructure for autonomous driving technology, facilitating vehicles in positioning, environmental perception, and motion planning without being affected by weather changes or sensor-visibility limitations.
  • 2.2K
  • 01 Apr 2024
Topic Review
Suspension (Vehicle)
Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both roadholding/handling and ride quality, which are at odds with each other. The tuning of suspensions involves finding the right compromise. It is important for the suspension to keep the road wheel in contact with the road surface as much as possible, because all the road or ground forces acting on the vehicle do so through the contact patches of the tires. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different.
  • 2.2K
  • 04 Nov 2022
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