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Topic Review
Ferroelastic Twinning in Minerals
Ferroelastic twinning in minerals is a very common phenomenon. The twin laws follow simple symmetry rules and they are observed in minerals, like feldspar, palmierite, leucite, perovskite, and so forth. The major discovery over the last two decades was that the thin areas between the twins yield characteristic physical and chemical properties, but not the twins themselves. Research greatly focusses on these twin walls (or ‘twin boundaries’); therefore, because they possess different crystal structures and generate a large variety of ‘emerging’ properties. Research on wall properties has largely overshadowed research on twin domains. 
  • 1.5K
  • 15 Jun 2021
Topic Review
Fetal Acidosis
Fetal acidosis or intrauterine hypoxia refers to a condition of deprived short supply of oxygen below the physiologic level of normal blood, which is defined as pH ≤ 7.25.
  • 1.4K
  • 18 Feb 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.
  • 545
  • 31 Oct 2022
Topic Review
Fiat CR.42
The Fiat CR.42 Falco ("Falcon", plural: Falchi) was a single-seat sesquiplane fighter developed and produced by Italian aircraft manufacturer Fiat Aviazione. It served primarily in Italy's Regia Aeronautica both before and during the Second World War. The CR.42 was an evolutionary design of Fiat’s earlier CR.32 fighter, featuring a more powerful supercharged Fiat A.74R1C.38 air-cooled radial engine and aerodynamic improvements to its relatively clean exterior surfaces. The aircraft proved to be relatively agile in flight, a factor that had been attributed to its very low wing loading and a sometimes decisive tactical advantage. RAF Intelligence praised its exceptional maneuverability, further noting that "the plane was immensely strong", though it was technically outclassed by faster, more heavily armed monoplanes. While primarily used as a fighter, various other roles were adopted for some variants of the type, such as the CR.42CN dedicated night fighter model, the CR.42AS ground attack aircraft, and the CR.42B Biposto twin-seat trainer aircraft. During May 1939, the CR.42 entered service with the Regia Aeronautica; it was the last of the Fiat biplane fighters to enter front line service. By 10 June 1940, the date when Italy entered the Second World War, roughly 300 of the type had been delivered, which were initially tasked with defending Italy's cities and key military installations. By the end of 1940, the Falco had been involved in combat on various fronts, including the Battle of France, the Battle of Britain, Malta, North Africa, and Greece. By the end of the war, Italian CR.42s had been used on further fronts, including Iraq, the Eastern Front and the Italian mainland. Following the signing of the Italian armistice with the Allies on 8 September 1943, the type was primarily relegated to use as a trainer by the Italian Co-Belligerent Air Force , while some Italian CR.42s were seized by the Germans and used by the Luftwaffe to perform ground attack missions. In addition to its service in Italy, the CR.42 was produced and entered service in smaller numbers with the air forces of several nations, including Belgium, Sweden and Hungary. By the end of production, in excess of 1,800 CR.42s has been constructed, making it the most numerous Italian aircraft to be used during the Second World War. Aviation author Przemyslaw Skulski has claimed that the fighter had performed at its best during its service with the Hungarian Air Force, specifically during its deployment against Soviet forces on the Eastern Front of the war, where it reportedly achieved a kill to loss ratio of 12 to 1.
  • 1.8K
  • 18 Nov 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.
  • 997
  • 08 Nov 2022
Topic Review
Fiat G.55
The Fiat G.55 Centauro (Italian: "Centaur") was a single-engine single-seat World War II fighter aircraft used by the Regia Aeronautica and the A.N.R. (Aeronautica Nazionale Repubblicana) in 1943–1945. It was designed and built in Turin by Fiat. The Fiat G.55 was arguably the best type produced in Italy during World War II, (a subjective claim also frequently made for the Macchi C.205 Veltro as well as for the Reggiane Re.2005 Sagittario) but it did not enter production until 1943, when, after comparative tests against the Messerschmitt Bf 109G and the Focke-Wulf 190, the Luftwaffe itself regarded the Fiat G.55 as "the best Axis fighter". During its short operational service, mostly under the Repubblica Sociale Italiana insignia, after the 8 September 1943 armistice, this powerful, robust and fast aircraft proved itself to be an excellent interceptor at high altitude. In 1944, over Northern Italy, the Centauro clashed with British Supermarine Spitfire, P-51 Mustang, P-47 Thunderbolt and P-38 Lightning, proving to be no easy adversary. Italian fighter pilots liked their Centauro but by the time the war ended, fewer than 300 had been built. By comparison, the Germans produced 35,000 Bf 109s.
  • 1.2K
  • 24 Oct 2022
Topic Review
Fiber Metal Laminates
Composite materials such as Fibre Metal Laminates (FMLs) have attracted the interest of the aerospace and automotive industries due to their high strength to weight ratio, but to use them as structures it is necessary to master the manufacturing and wiring techniques of these materials. The process parameters used in multi-material machining, such as drilling and milling, tool geometry, tool coating, lubricants and coolants, must be well established to achieve a successful machining process in FLM materials. Failure of any of these parameters can cause irreparable damage to the material, wasting the process and making it less sustainable. Understanding the failure process is essential to improve the accuracy of the analysis, to supplement the information and to provide a deterrent to adjusting process parameters.
  • 719
  • 19 Apr 2023
Topic Review
Fiber Optic Sensor
A fiber optic sensor is a sensor that uses optical fiber either as the sensing element ("intrinsic sensors"), or as a means of relaying signals from a remote sensor to the electronics that process the signals ("extrinsic sensors"). Fibers have many uses in remote sensing. Depending on the application, fiber may be used because of its small size, or because no electrical power is needed at the remote location, or because many sensors can be multiplexed along the length of a fiber by using light wavelength shift for each sensor, or by sensing the time delay as light passes along the fiber through each sensor. Time delay can be determined using a device such as an optical time-domain reflectometer and wavelength shift can be calculated using an instrument implementing optical frequency domain reflectometry. Fiber optic sensors are also immune to electromagnetic interference, and do not conduct electricity so they can be used in places where there is high voltage electricity or flammable material such as jet fuel. Fiber optic sensors can be designed to withstand high temperatures as well.
  • 587
  • 17 Nov 2022
Topic Review
Fiber Optic Sensors
The last decade has seen rapid developments in the areas of carbon fiber technology, additive manufacturing technology, sensor engineering, i.e., wearables, and new structural reinforcement techniques. These developments, although from different areas, have collectively paved way for concrete structures with non-corrosive reinforcement and in-built sensors. This effort bridges the gap between civil engineering and sensor engineering communities through an overview on the up-to-date technological advances in both sectors, with a special focus on textile reinforced concrete embedded with Fiber Optic Sensors (FOSs). These have advantages over alternative concepts, such as, immunity to electromagnetic interference or light weight. The former is an important aspect for some civil infrastructure, i.e., railways where the lines are electrified. Thus, there has been in depth research on the feasibility and deployment of FOSs for SHM purposes. The characteristics desired for the ideal FOS for strain measurement in civil structures would include: adequate sensitivity and dynamic range; linear response; sensitivity to the direction of measurand field change; being single-ended, i.e., to minimize the number of leads; insensitivity to thermal fluctuations; non-perturbativity to the structure; immunity to power interruptions; ability to multiplex; ease of mass production, and durability for the entire lifetime of the structure.
  • 501
  • 23 Dec 2021
Topic Review
Fiber to the Premises by Country
This article lists the deployment of fiber to the premises, fiber to the home and fiber to the building by country.
  • 2.4K
  • 30 Nov 2022
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