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Topic Review
Residual Stress Measurement Techniques for Railway Components
Manufacturing and maintenance procedures in the railway industry regularly implement welding and metal deposition operations to produce joints, coatings and repair structures. During these processes, residual stresses arise through the generation of heat affected zones and plastic deformation. This makes accurate measurements of the internal stresses a critical aspect of manufacturing, monitoring, repair and model validation in the develop new metallic coating and joining technologies. Selection of an appropriate residual stress measurement method has many important factors including component size, resolution and the magnitude and location of internal stresses, often resulting in a combination of techniques required to obtain complete assessment of the stress state. 
  • 1.5K
  • 13 Jan 2023
Topic Review
Derailleur Gears
Derailleur gears are a variable-ratio transmission system commonly used on bicycles, consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another. Although referred to as gears in the bike world, these bicycle gears are technically sprockets since they drive or are driven by a chain, and are not driven by one another. Modern front and rear derailleurs typically consist of a moveable chain-guide that is operated remotely by a Bowden cable attached to a shifter mounted on the down tube, handlebar stem, or handlebar. When a rider operates the lever while pedalling, the change in cable tension moves the chain-guide from side to side, "derailing" the chain onto different sprockets. For more information about the choice of particular gear ratios and sprocket sizes, see Bicycle gearing.
  • 1.5K
  • 16 Nov 2022
Topic Review
Reggiane Re.2001
The Reggiane Re.2001 Falco II was an Italian fighter aircraft, serving in the Regia Aeronautica (Italian Air Force) during World War II. A contemporary of the renowned Macchi C.202, the production of this type was to be limited to only 252, but it was a flexible design that proved to be able to undertake a number of roles. Thanks to its maneuverability it could dogfight with more powerful opponents like the Supermarine Spitfire. The Re.2001 became the basis of a later, more formidable fighter, the Re.2005.
  • 1.5K
  • 17 Oct 2022
Topic Review
CASA C-101
The CASA C-101 Aviojet is a low-wing single engine jet-powered advanced trainer and light attack aircraft designed and manufactured by Spanish aircraft company Construcciones Aeronáuticas SA (CASA). The C-101 was developed in response to a Spanish Air Force requirement, which needed a replacement for the already outdated Hispano Saeta. During 1975, CASA commenced work on what would become the C-101. In addition to its own design team, technical assistance was provided by Germany's Messerschmitt-Bölkow-Blohm (MBB) and the United States' Northrop. During June 1977, the first of four prototypes performed the type's maiden flight. The design was somewhat reminiscent of other jet trainers of the era, such as the BAE Hawk and the Alpha Jet, but was less aerodynamically sophisticated, being equipped with an unswept wing. Performance of the C-101 during flight testing was reported in excess of predictions. On 17 March 1980, the first examples were introduced to operational service with the Spanish Air Force, which would be the principal customer for the C-101. The initial model possessed only a limited weapons capability, this attack capability was expanded upon later-built aircraft. Several models were exported to overseas operators; the C-101 has been adopted by the Chilean Air Force , Honduran Air Force and the Royal Jordanian Air Force . A final improved model, designated C-101DD, was demonstrated but did not find customers and thus it did not enter serial production. In addition to its use as a trainer aircraft, it has been used to perform aerobatics; in the latter context, it has been flown by the Patrulla Aguila aerobatics team. As of 2019, the C-101 remains in service in the Spanish Air Force and several other countries. Early on the 2010s there were talks about the replacement of the C-101. Finally, in 2020 it was decided that the C-101 would be replaced by the Pilatus PC-21 (24) and the Airbus Future Jet Trainer (50 - 55).
  • 1.5K
  • 22 Nov 2022
Topic Review
Airborne Wind Energy
Airborne wind energy (AWE) is the direct use or generation of wind energy by the use of aerodynamic or aerostatic lift devices. AWE technology is able to harvest high altitude winds, in contrast to wind turbines, which use a rotor mounted on a tower. The term high-altitude wind power (HAWP) has been used to refer to AWE systems. However, semantically HAWP might also include wind energy conversion systems that are somehow positioned at a large height from the ground or sea surface. Various mechanisms are proposed for capturing the kinetic energy of winds such as kites, kytoons, aerostats, gliders, gliders with turbines for regenerative soaring, sailplanes with turbines, or other airfoils, including multiple-point building- or terrain-enabled holdings. Once the mechanical energy is derived from the wind's kinetic energy, then many options are available for using that mechanical energy: direct traction, conversion to electricity aloft or at ground station, conversion to laser or microwave for power beaming to other aircraft or ground receivers. Energy generated by a high-altitude system may be used aloft or sent to the ground surface by conducting cables, mechanical force through a tether, rotation of endless line loop, movement of changed chemicals, flow of high-pressure gases, flow of low-pressure gases, or laser or microwave power beams.
  • 1.5K
  • 14 Oct 2022
Topic Review
Al-Abid
The Al-Abid(Arabic: العابد) LV was an Iraqi three-stage "Satellite launch system", a civilian project that was commenced in 1988. The Iraqis intended to launch an Al-Ta'ir satellite with the help of such a launch vehicle. The Iraqis therefore pursued a LV with stages based on Scud missiles and the S-75 Dvina. However only the first stage could be tested on December 1989 and according to General Ra'ad the next stages could not be developed. General Ra'ad says that not even the drawings of the second and third stage vehicles are available and that no final report could be produced. UN inspectors and U.S intelligence did not offer many details regarding the Al-Abid launch vehicle as they were not interested in it.
  • 1.5K
  • 29 Nov 2022
Topic Review
ITS Launch Vehicle
The ITS launch vehicle was a 2016-2017 design for a privately funded orbital launch vehicle planned to be developed by SpaceX. Design work was discontinued in 2017 when development was shifted to a smaller version, now called BFR. The initial design objective of the ITS launch vehicle was to launch a variety of SpaceX Interplanetary Transport System missions to Mars and other destinations in the beyond-Earth-orbit portion of the Solar System. The first launch was not expected before the 2020s. The ITS launch vehicle was to be operated as a somewhat unusual two-stage rocket. Its first stage was to have been powered by 42 Raptor rocket engines—designed and manufactured by SpaceX—operating on densified (chilled near triple point) methane/oxygen, propellants that have not been widely used as rocket propellants in the past. Like the Falcon 9 orbital launch vehicle that preceded it, the ITS launch vehicle's first stage design was intended to be reusable, following a return to the launch site and vertical landing following each launch. When announced, it was also designed to have a new feature for SpaceX launch vehicles: full reusability of even the second-stage and orbital spacecraft as well. The large payload capacity of the launch vehicle placed it into the super-heavy lift class, with the ability to place 300 tonnes (660,000 lb) into low Earth orbit in reusable configuration and 550 tonnes (1,210,000 lb) in expendable mode. The second stage of the Earth launch vehicle was planned to have two versions, the Interplanetary spaceship for passengers and cargo and the ITS tanker to deliver propellants to Earth orbit. Both were to be powered by six vacuum-optimized Raptor rocket engines with three additional sea-level-nozzle Raptor engines for maneuvering. Thus, the element of the launch vehicle that was to provide second-stage acceleration to orbital velocity on all launches from Earth would also be used as an on-orbit spacecraft. The Interplanetary spaceship was planned as a very long-duration carrier of both passengers and space cargo to interplanetary destinations, and was to have served as both a descent and ascent vehicle at Mars. The high-level specifications for the vehicle were publicly announced in September 2016, but by July 2017, SpaceX had stated they would not build the 12 m (39 ft)-diameter vehicles as previously planned, but would instead build a "still large" but much smaller launch vehicle first. Subsequently, that was revealed to be the BFR in September 2017, a vehicle intended to cost-effectively replace and supersede all existing SpaceX launch vehicles and passenger/cargo spacecraft.
  • 1.5K
  • 10 Nov 2022
Topic Review
M9 Armored Combat Earthmover
The M9 Armored Combat Earthmover (ACE) is a highly mobile armored tracked vehicle that provides combat engineer support to front-line forces. Fielded by the United States Army, its tasks include eliminating enemy obstacles, maintenance and repair of roads and supply routes, and construction of fighting positions.
  • 1.4K
  • 02 Dec 2022
Topic Review
Hubsan X4
The Hubsan X4 is a series of very small lightweight remotely-controlled quadcopters (sometimes considered unmanned aerial vehicles or "drones") which utilize four propellers (hence the "X4" designation) powered by a single lithium-polymer battery. Since the marketing of the first model, several upgrades and improvements have taken place, each with a subsequent model number and designation attached.
  • 1.4K
  • 12 Oct 2022
Topic Review
Resilience in the Built Environment
Resilience in the Built Environment is the built environment's capability to keep adapting to existing and emerging threats such as severe wind storms or earthquakes and creating robustness and redundancy in building design. New implications of changing conditions on the efficiency of different approaches to design and planning can be addressed in the following term.
  • 1.4K
  • 18 Nov 2022
Topic Review
HMS Lady Nelson (1798)
His Majesty's Armed Survey Vessel Lady Nelson was commissioned in 1799 to survey the coast of Australia. At the time large parts of the Australian coast were unmapped and Britain had claimed only part of the continent. The British Government were concerned that, in the event of settlers of another European power becoming established in Australia, any future conflict in Europe would lead to a widening of the conflict into the southern hemisphere to the detriment of the trade that Britain sought to develop. It was against this background that Lady Nelson was chosen to survey and establish sovereignty over strategic parts of the continent. Lady Nelson left Portsmouth on 18 March 1800 and arrived at Sydney on 16 December 1800 after having been the first vessel to reach the east coast of Australia via Bass Strait. Prior to that date all vessels had sailed around the southern tip of Tasmania to reach their destination. Lady Nelson's survey work commenced shortly after her arrival at Sydney, initially in the Bass Strait area. She was involved in the discovery of Port Phillip, on the coast of Victoria, in establishing settlements on the River Derwent and at Port Dalrymple in Tasmania, at Newcastle and Port Macquarie in New South Wales, and on Melville Island off the north coast of the continent.
  • 1.4K
  • 23 Nov 2022
Topic Review
Design 1095 Ship
The Design 1095 ship was an Emergency Fleet Corporation (EFC) design for a troop transport to be built at New York Shipbuilding Corporation and delivered to the United States Shipping Board (USSB) that, at the end of World War I hostilities, was modified to a combined passenger and cargo vessel. The contract was for thirteen ships, EFC hulls 2579 though 2591, but later adjusted to seven ships with the remainder being changed during construction to the slightly larger ships of EFC Design 1029 built from the start as passenger and cargo ships rather than being modified from the troop ship plan. After initial service as USSB owned ships operated by agents, United States Lines in Atlantic service between New York and Europe with five ships and two ships with Swayne and Hoyt with the Pacific-Argentine-Brazil Line, the ships were sold in 1923 to Robert Dollar Company which initiated the Dollar and successor American President Lines' tradition of naming ships after presidents. The ships inaugurated Dollar's "Round-the-World" service which was continued by American President Lines with additional ships. During World War II the seven ships were used as troop transports, three being converted to hospital ships (2 Army and 1 Navy) and three were lost. The three ships built as Old North State, Panhandle State and Blue Hen State became hospital ships and survived the war. Creole State served as a transport and began conversion to a hospital ship in the closing days of the war but the conversion stopped with peace upon which she was reconverted to become an Army transport for dependent repatriation. Two, President Taylor, built as Granite State and President Grant, built as Centennial State, became total losses after groundings. The ship built as Wolverine State and President Harrison at the time, was on a second voyage to evacuate Marines and civilians from China sailing after 7 December 1941, was grounded in an attempt to deny use by the Japanese, but salvaged and named Kachidoki Maru. While transporting British prisoners of war Kachidoki Maru was torpedoed and sunk by USS Pampanito on 12 September 1944.
  • 1.4K
  • 14 Nov 2022
Topic Review
Army Ground Mobility Vehicle
The M1297 Army Ground Mobility Vehicle (A-GMV or AGMV), previously just GMV, and formerly called the Ultra Light Combat Vehicle (ULCV), is a U.S. Army airdroppable light off-road vehicle for light infantry brigades. The A-GMV is produced by General Dynamics. The design is closely based on the M1288 GMV 1.1, which is itself based on the Flyer 72. In March 2015, the Army changed the name of the Ultra Light Combat Vehicle to the Ground Mobility Vehicle. A-GMV is intended to be carried internally in a CH-47 Chinook or externally by a UH-60 Black Hawk. In order to be survivable but transportable, the GMV would be lightly armored and use speed, maneuverability, and off-road mobility to avoid major threats. The A-GMV is configured to carry an airborne infantry combat squad of nine paratroopers, and their gear – a payload capacity of over 5,000 pounds (2,300 kg). The vehicle has an open design, modifiable into flexible configurations, by remote and manned turrets, armor, or arctic kits. The AGMV was a limited purchase through USSOCOM's GMV 1.1 program. The Infantry Squad Vehicle will be purchased in greater numbers.
  • 1.4K
  • 03 Nov 2022
Topic Review
North American A-36 Apache
The North American A-36 Apache (listed in some sources as "Invader", but also called Mustang) was the ground-attack/dive bomber version of the North American P-51 Mustang, from which it could be distinguished by the presence of rectangular, slatted dive brakes above and below the wings. A total of 500 A-36 dive bombers served in the Mediterranean and Southeast Asia theaters during World War II before being withdrawn from operational use in 1944. The A-36 project was a stopgap measure intended to keep North American Aviation (NAA) assembly lines running during the first half of 1942 despite the US having exhausted its funds earmarked for fighter aircraft. When the order came for more P-51s in June 1942, the NAA workforce was thoroughly experienced.
  • 1.4K
  • 28 Sep 2022
Topic Review
BMW ActiveE
The BMW ActiveE was a demonstration electric car based on the BMW 1 Series small family cars. It was the second vehicle after the Mini E to be developed under BMW Group’s Project i. The electric drive system was the latest addition to BMW’s EfficientDynamics programme. The US Environmental Protection Agency official range is 151 kilometres (94 mi), with an energy consumption of 33 kW·h/100 miles, and the agency rated the ActiveE's combined fuel economy at 2.3L/100 km (102 miles per gallon gasoline equivalent). The four-seater, rear-wheel drive ActiveE was unveiled at the North American International Auto Show in Detroit in January 2010. Deliveries of the ActiveE for field testing in the U.S. began in January 2012, after the Mini E trial ended. A total of 1,100 vehicles were planned to participate in the program worldwide, with 700 allocated for the U.S. trial and 35 to a trial in China.[needs update] Participants in the Mini E trial had priority to lease the new electric car. Production began at BMW's Leipzig plant in July 2011. After the field trial of the Mini E, BMW took reservations for drivers, who BMW calls "Electronauts", in mid-2012. The field trial of the ActiveE started in early 2012. BMW stopped accepting reservations for the ActiveE, and has leased out all of their ActiveE cars. The lease details were similar to that of the Mini E lease details, a two-year limited lease with free maintenance. The lessee had to complete online surveys and take their ActiveE into their local BMW dealership for analysis and service periodically. Once the ActiveE program ended, all ActiveE cars were taken off of the road. Lessees returned their ActiveE vehicles to BMW, and were not able to purchase them. The cars were donated to tech schools or museums for analysis and disassembly, as well as for display purposes.
  • 1.4K
  • 03 Nov 2022
Topic Review
Driving Behavior of Educated Youth in Bangladesh
Proper traffic safety is defined as systems and techniques used to safeguard road users against dying or being severely injured. Educated and internet-using Bangladeshi drivers took part in a questionnaire about their emotional stability on an online platform with more than 100 questions comprising two parts. While one of the part outlines the physiological, cultural, and socioeconomic factors and driver education, in another part, an 18-point Driver’s Behavior Questionnaire was introduced to the responders. About 40% of the surveyed drivers in the poll were inexperienced. However, 49% of people prefer to ride two-wheelers. Moreover, 70% of surveyed drivers hold valid driver’s licenses. At the same time, 35.2% of those were college graduates. Even 34.8% of accidents were caused by excessive speed and non-aggressive driving. In addition, age and degree of education were significant indicators of distracted driving violations.
  • 1.4K
  • 07 May 2022
Topic Review
Mooring (Watercraft)
A mooring refers to any permanent structure to which a vessel may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to forestall free movement of the ship on the water. An anchor mooring fixes a vessel's position relative to a point on the bottom of a waterway without connecting the vessel to shore. As a verb, mooring refers to the act of attaching a vessel to a mooring. The term likely stems from the Dutch verb meren (to moor), used in English since the end of the 15th century.
  • 1.4K
  • 10 Nov 2022
Topic Review
Fiat BR.20
The Fiat BR.20 Cicogna (Italian: "stork") was a low-wing twin-engine medium bomber that was developed and manufactured by Italian aircraft company Fiat. It holds the distinction of being the first all-metal Italian bomber to enter service; at the time, it was regarded as one of the most modern medium bombers in the world. The BR.20 has its origins in a request by the Regia Aeronautica (Italian Royal Air Force) issued during 1934 for a new medium bomber capable of high speeds, long range, and satisfactory payload, reliability, and flight characteristics compared to contemporaries. Among the companies that chose to respond was Fiat, which completed its design for the competition during 1935. On 10 February 1936, the first prototype (serial number M.M.274) conducted its maiden flight. Flight testing proceeded at a rapid pace; during September 1936, initial deliveries of the type commenced to the Regia Aeronautica. During summer 1937, the BR.20 received its baptism of fire when a number were operated by the Aviazione Legionaria during the Spanish Civil War; the BR-20 came to form the backbone of Nationalist bombing operations, along with the German-built Heinkel He 111. It was also used in combat during the 1930s with relative success by the Japanese during the Second Sino-Japanese War. During 1939, a modified long-range BR.20 version (designated BR.20L) named Santo Francesco under the command of Maner Lualdi performed a highly publicised non-stop flight from Rome to Addis Ababa, Ethiopia. Upon the entry of Italy into the Second World War during mid-1940, the BR.20 served as the standard medium bomber of the Regia Aeronautica, however, by that point, the type was already approaching obsolescence. By 1942, the aircraft was mostly used for maritime patrol and operational training for bomber crews. The BR.20 was produced from the mid-1930s until the end of the Second World War. More than 500 were produced before the end of the war.
  • 1.3K
  • 31 Oct 2022
Topic Review
Indonesian Army Corps of Engineers
The Indonesian Army Corps of Engineers (Indonesian: Direktorat Zeni TNI Angkatan Darat), abbreviated Ditziad, or simply Zeni is an Indonesian Army Central Executive Agency made up of some 15,000 civilian and military personnel, making it one of Southeast Asia's and the ASEAN's, largest public engineering, design, and construction management agencies.The Corps is involved in a wide range of disaster relief and public works projects within the republic, as well as in combat support operations. The Indonesian term for military engineers, Zeni, is derived from the French/Dutch Genie, meaning sapper. Their most visible missions include: Public works construction (especially in villages, under the wider Tentara Manunggal Membangun Desa /TMMD program (previously known as ABRI Masuk Desa/ AMD program), flood control, beach nourishment, and dredging for waterway navigation. Design and construction of flood protection systems through various national mandates. Design and construction management of military facilities for the Army, Air Force, and other Defence and national agencies. Environmental regulation and ecosystem restoration in coordination with the national government and the private sector. Providing the Army with an active EOD detection and nuclear, biologial and chemical defence capability.
  • 1.3K
  • 08 Nov 2022
Topic Review
Savoia-Marchetti SM.81
The Savoia-Marchetti SM.81 Pipistrello (Italian: bat) was the first three-engine bomber/transport aircraft serving in the Italian Regia Aeronautica. When it appeared in 1935, it represented a real step ahead in Italian military aviation: it was fast, well armed and had a long range. It proved effective during the war with Ethiopia and the Spanish Civil War. Despite being too slow to remain competitive as a bomber in the later years of World War II, it was one of the most flexible, reliable and important aircraft of the Regia Aeronautica from 1935 to 1944, and adapted to second-line duties in a wide range of tasks.
  • 1.3K
  • 01 Dec 2022
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