Air Armament Center

The Air Armament Center (AAC) was an Air Force Materiel Command (AFMC) center at Eglin Air Force Base, Florida, responsible for development, acquisition, testing, and deployment of all air-delivered weapons for the U.S. Air Force. Weapon systems maintained by the center included the Advanced Medium Range Air-to-Air Missile, High-speed anti-radiation missile, HARM Targeting System, Joint Air-to-Surface Standoff Missile, Joint Direct Attack Munition, Miniature Air-Launched Decoy, Sensor Fuzed Weapon, and the Small Diameter Bomb.
The Air Armament Center was inactivated as an AFMC center on July 18, 2012, and its functions merged into the former 96th Air Base Wing at Eglin AFB. The new organization was renamed as the 96th Test Wing (96 TW) the same day as a subordinate command of the Air Force Test Center at Edwards Air Force Base, California.
History.
On May 15, 1940, the Air Corps Specialized Flying School at Eglin Field was redesignated the Air Corps Proving Ground." It was redesignated Proving Ground Command on 1 April 1942.
In 1989, Mueller said the AAF Tactical Center was designated earlier on 16 October and that it and the subsequent AAF Center were different commands. For example, he cites "AAF School of Applied Tactics, c. Mar 1942 (redesignated AAF Tactical Center, 16 Oct 1942)" then "AAF Center, 1 June 1945".
On 27 October 1942 the United States Army Air Forces established the Army Air Forces School of Applied Tactics at Orlando Army Air Base, Florida. The next year, it was redesignated as the Army Air Forces Tactical Center, on 16 October 1943. In the last days of the war, it was redesignated the Army Air Forces Center, and documentation of the period appears to indicate that the AAF Proving Ground Command at Eglin Field, Florida and the Army Air Forces Center at Orlando AAB were merged as Army Air Forces Center on 1 June 1945.
The Air Force Center was the planned USAF unit for the development of tactical policy and procedures. The Air Force Center was to be the succeeding unit to the USAAF Army Air Forces Tactical Center, established on October 28, 1943, and which had become the Army Air Forces Center on 1 June 1945. Instead, the AAF Center merged into Proving Ground Command (PGC) to form a new Army Air Forces Proving Ground Command on 8 March 1946. The AAF PGC was redesignated the Air Proving Ground Command on 10 July 1946, and raised to major command status. The APGC was moved to the now renamed Eglin Air Force Base, Florida, on 1 July 1948.
Testing of weapons.
APGC conducted realistic testing of new weapons as an independent organization, reporting directly to the Chief of Staff of the Air Force and advocating a "fly-before-buy" approach to acquiring new systems. Such a shift, however, remained a challenge, for the Air Force continued the "buy-fly-fix" process that had grown from the demands of the Second World War and undervalued the importance of timely independent operational test and evaluation.
APGC attempted to simulate combat conditions during its tests. It also grew in size as it acquired the systems it tested. By 1956, Air Force regulations outlined an eight-phase test and evaluation process that did not include the APGC until phase seven. By that point in the acquisition cycle, the Air Force had often already fielded units with new systems that APGC had not yet tested. Not surprisingly, operators often experienced serious problems with these new, untested systems. This led to a misperception about the value of operational test and evaluation (OT&E) and APGC. Had OT&E taken place before production decisions and fielding new systems, there likely would not have been any question about the added value of independent OT&E.
As a result of the doubts about the value of APGC and cuts to the defense budget, in 1957 the Air Force stripped APGC of its major command status, reduced its budget and authorized personnel, and redesignated the Command the Air Proving Ground Center, and assigned it to the Air Research and Development Command. This action meant the Air Force no longer had an independent organization that specialized in impartial operational test and evaluation.
Decentralized operational testing at the major commands occurred from 1958 to 1973. Major command emphasis was often on quick deployment rather than thorough testing and impartial evaluations. Although the Air Force streamlined OT&E from eight to three phases during this period, OT&E still came at the end of the acquisition process. In addition, as systems became more complex, and the Air Force moved to acquire systems quickly, the "fly-before-buy" approach fell by the wayside. The consequences became clear when a Department of Defense study found that 21 of 22 major weapons systems used in the Vietnam War from 1965 to 1970 suffered severe operational deficiencies. These results strongly stated the case for independent OT&E in the Air Force.
The AAC was a focal point for the acquisition of advanced weapons systems. The center carried out scientific research, system management, production, operational performance, business management, requirements definition, customer and engineering support, technology planning, materiel identification, and field support activities.
While "fly-before-buy" has repeatedly proven its worth in thorough testing of systems and avoidance of later problems, the Air Force even in the twenty-first century remains severely hampered by a "buy-fly-fix" approach. Literally billions of dollars have been spent in making weapons systems operational after they have entered squadron service. For example, the Rockwell B-1B Lancer suffered repeated such problems. When declared operational, apart from nuclear weapons, the only conventional weapon the B-1 could use were free-fall bombs.
Structure through 2010.
To accomplish its mission the Air Armament Center commanded three wings through 2010.


Astra 400

The Astra modelo 400 was a Spanish service pistol produced by weapons manufacturer Astra-Unceta y Cia SA. as a replacement for the Campo-Giro 1913/1916, which had also been chambered in 9mm Largo. It was the standard issue sidearm in the Spanish Army during the Spanish Civil War and also saw service in Germany during World War II.
The pistol was mass-produced and many examples still exist today. The Spanish Navy, along with the German Luftwaffe and the Chilean Navy primarily used the smaller variant Astra 300 and the Wehrmacht later altered the Astra 400 into the Astra 600 to better handle the 9mm Luger. The 400 was considered heavy as in order to handle the power of the 9mm Largo round in a blowback action the 400 had a reinforced slide and tough spring.
It gained fame among Spanish African and Civil War veterans as a strong very reliable pistol, specially under mud and sand conditions, thanks to its hidden hammer, sealing its mechanism from the external elements and its forged slide and frame construction.
Underrated in the past by some American gun experts, who in general, had a poor view on Spanish guns, because of its origin and its “tubular” “water pistol” looks, the pistol is today an interesting collector piece, and much appreciated specially among German collectors, and it is also an accurate service pistol for target shooting, thanks to its low axis over the hand.
A powerful pistol, original 9mm largo spanish military loads were on a par with 38 super factory loads.
History.
The Spanish War Ministry of King Alfonso XIII began tests in 1919 to replace the Campo Giro pistol as the standard military sidearm. The 9mm Largo Astra modelo 400, patented by Pedro Careaga, was selected for the Spanish Army in August 1921, and was also adopted by other Spanish Armed forces. Astra pistols were supplied to Republican Spain and to the Basque government which controlled the plant until the Bombing of Guernica in April, 1937. Astra pistols were subsequently produced for Nationalist troops, while Republican forces made approximately 22,000 copies of the pistol in Terrassa (marked "F. Ascaso") and Valencia (marked RE for "Republica Española"). Astra production after the civil war was for Nationalist troops except serial numbers 92851 to 98850 for Nazi Germany. Astra continued private production until 1950 even though in 1946 the Spanish military adopted the Star Model A as the standard sidearm. Spanish military inventories were sold to civilian wholesalers between 1956 and 1965. A total of around 106,175 pistols were produced.
Mechanics.
The Astra 400 is heavy compared to many contemporary service pistols of the time like the Tokarev TT-33 but is similar in weight and length to the Colt 1911. The Astra 400 was designed to be safe to fire with a simple blowback action unaided by any breech-locking devices. This is only possible with a heavy slide and strong recoil spring. It was fitted with an internal hammer which was considered very hard to cock. The pistol also featured grooved finger grips and left sided combined slide lock/safety behind the trigger guard. The original design was chambered in 9mm Largo, but later variants would be chambered differently so as to better fulfill different military needs.
Variants.
Astra made some experimental variants of the 400 chambered in 7.63mm Mauser, .32 ACP, and .30 Luger. 9mm Largo rounds were often in short supply outside of Spain. Though several other 9mm cartridges like the 9mm Luger and .380ACP could feed, be fired, and eject successfully, this was a capability of questionable use where 9mm Largo ammunition was available as chronograph tests show considerably higher muzzle velocities and thus energies with the 9mm Largo than 9mm Luger and .380. The 9×23mm Steyr cartridge is more similar in dimension to the 9mm Largo than both the 9mm Luger and .380 and performs better as well.
The Astra 600, a slightly shorter and lighter version of the Astra 400 that is chambered in 9mm Luger, was later developed for export sales, primarily to Nazi Germany. A smaller variant for both domestic and export sales, the Astra 300, was offered in .32 ACP and .380 ACP. By the end of 1947 171,300 were made and were primarily issued to security forces of the Spanish Navy and the German Luftwaffe.


Harry H. Goode

Harry H. Goode (June 30, 1909 – October 30, 1960) was an American computer engineer and systems engineer and professor at the University of Michigan. He is known as co-author of the book "Systems Engineering" from 1957, which is one of the earliest significant books directly related to systems engineering.
Biography.
Harry H. Goode (née Goodstein) was born in New York City in 1909. He received his B.A. in history from New York University in 1931, when the country was in the depths of the Depression. While studying chemical engineering at Cooper Union, Goode earned his living playing the clarinet and saxophone in New York jazz bands. He received his second bachelor's degree in 1940. During the war he attended Columbia University and received a master's degree in mathematics in 1945.
In 1941 Goode started working as a statistician for the New York City Department of Health. From 1946 to 1949 Goode worked for the U.S. Navy in Sands Point, Long Island, where he became head of the Special Projects Branch. Here he contributed to flight control simulation training, aircraft instrumentation, antisubmarine warfare, weapons systems design, and computer research and initiated computerbased simulation projects.
In the 1950s Goode became professor at the University of Michigan. Until his death in 1960 he was president of the National Joint Computer Committee (NJCC). He was the principal architect of what was to become AFIPS (American Federation of Information Processing Societies). Had he lived, Goode undoubtedly would have become the first president of AFIPS, for he was the prime mover in organizing the three American constituent societies that were members of NJCC into one federation.
Work.
Harry Goode worked on the research frontiers of Management Science, Operations Research and Systems engineering in connection with organisms as systems, the reactions of groups, models of human preference, the experimental exploration of human observation, detection, and decision making, and the analysis and synthesis of speech.
Harry H. Goode Memorial Award.
The IEEE Computer Society yearly awards a Harry H. Goode Memorial Award for achievements in the information processing field which are considered either a single contribution of theory, design, or technique of outstanding significance, or the accumulation of important contributions on theory or practice over an extended time period, the total of which represent an outstanding contribution.
Publications.
Goode wrote several books and articles. Books:
Articles, a selection:
About Harry H. Goode:


Ruger Wrangler

The Ruger Wrangler is a single-action rimfire revolver produced by Sturm, Ruger & Co. Chambered for .22 Long Rifle cartridges, it was announced in April 2019. The revolver makes extensive use of aluminum and zinc castings for ease of manufacturability, and also has an unfluted cylinder and uses metal injection molded components for further cost reduction. The Wrangler's price point of $250 has been described as "very attractive", and is less than half the MSRP of Ruger's Single-Six and Bearcat models.


Buzzer

A buzzer or beeper is an audio signalling device, which may be mechanical, electromechanical, or piezoelectric ("piezo" for short). Typical uses of buzzers and beepers include alarm devices, timers, and confirmation of user input such as a mouse click or keystroke.
History.
Electromechanical.
The electric buzzer was invented in 1831 by Joseph Henry. They were mainly used in early doorbells until they were phased out in the early 1930s in favor of musical chimes, which had a softer tone.
Piezoelectric.
Piezoelectric buzzers, or piezo buzzers, as they are sometimes called, were invented by Japanese manufacturers and fitted into a wide array of products during the 1970s to 1980s. This advancement mainly came about because of cooperative efforts by Japanese manufacturing companies. In 1951, they established the Barium Titanate Application Research Committee, which allowed the companies to be "competitively cooperative" and bring about several piezoelectric innovations and inventions.
Types.
Electromechanical.
Early devices were based on an electromechanical system identical to an electric bell without the metal gong. Similarly, a relay may be connected to interrupt its own actuating current, causing the contacts to buzz (the contacts buzz at line frequency if powered by alternating current) Often these units were anchored to a wall or ceiling to use it as a sounding board. The word "buzzer" comes from the rasping noise that electromechanical buzzers made.
Mechanical.
A joy buzzer is an example of a purely mechanical buzzer and they require drivers. Other examples of them are doorbells.
Piezoelectric.
A piezoelectric element may be driven by an oscillating electronic circuit or other audio signal source, driven with a piezoelectric audio amplifier. Sounds commonly used to indicate that a button has been pressed are a click, a ring or a beep.
A piezoelectric buzzer/beeper also depends on acoustic cavity resonance or Helmholtz resonance to produce an audible beep.
Modern applications.
While technological advancements have caused buzzers to be impractical and undesirable, there are still instances in which buzzers and similar circuits may be used. Present day applications include:


Status bar

A status bar is a graphical control element which poses an information area typically found at the window's bottom. It can be divided into sections to group information. Its job is primarily to display information about the current state of its window, although some status bars have extra functionality. For example, many web browsers have clickable sections that pop up a display of security or privacy information.
A status bar can also be text-based, primarily in console-based applications, in which case it is usually the last row in an 80x25 text mode configuration, leaving the top 24 rows for application data. Usually the status bar (called a "status line" in this context) displays the current state of the application, as well as helpful keyboard shortcuts. One example is the 'vi' text editor of UNIX (from the 1970s) or newer Linux systems.
Status lines have been used for more than 30 years to display advisory messages in a predefined area, rather than as pop-up messages in center screen which can block the view of related information.
Sometimes, a video game places the player's vital information or Heads-up display (such as hit points, lives, and score) on a similar strip across the top or bottom of the screen; this is also referred to as a status bar.
Usage.
Status bars, and status lines before them, have been used for years to display advisory messages in a predefined area, predating dialog boxes which can block the view of related information behind the pop-up messages. The use of status bars (or status lines) involves both advantages and disadvantages:
Advantages of status bars:
Disadvantages of status bars:


Mechanome

The mechanome consists of the body, or ome, of data including cell and molecular processes relating to force and mechanical systems at molecular, cellular and tissue length scales - the fundamental "machine code" structures of the cell. The mechanome encompasses biological motors, like kinesin, myosin, RNAP, and Ribosome mechanical structures, like actin or the cytoskeleton and also proteomic and genomic components that are mechanosensitive and are involved in the response of cells to externally applied force.
A definition of the "Mechanome" extending to cell/organ/body given by Prof. Roger Kamm, at the 5th World Congress of Biomechanics Munich, includes understanding:
The complete state of stress existing from tissues to cells to molecules. The biological state that results from the distribution of forces. Requires knowledge of the distribution of force throughout the cell/organ/body, the functional interactions between these stresses and the fundamental biological processes.
The mechanome seeks to understand the fundamental physical-mechanical processes and events that affect biological function. An example at the molecular level includes the common structural designs used by kinesin and myosin motor proteins (such as dimer formation and mechanochemical cycles) that control their function and lead to properties such as processivity. The mechanome assembles the common features of these motors regardless of the "track" (microtubules, actin filaments, nucleotide based structures, membranes) they move on. A cytoskeletal example includes structures such as actin filament networks and bundles that can form from a variety of actin binding proteins that cross-link or bundle actin filaments leading to common mechanical changes of these structures. A cell machinery example includes common structures such as contractile ring formation formed by both actin and tubulin type structures leading to the same mechanical result of cell division.
In order to respond to loading cells require a functional mechanome, defined as the cellular and extracellular mechanosensitive elements (genomic, proteomic, metabolic etc.) that contribute to the mechanical responsiveness of specific cells within a defined mechanical environment.
Using mechanical force techniques, such as optical tweezers or atomic force microscopy, single proteins can be identified by a unique structural fingerprint .
Mechanomics.
Mechanomics is the study of how forces are transmitted and the influence they have on biological function.
Mechanomics is also an emerging field between biology and biomechanics.
Physicomics
Physicomics it the complex of other than mechanical forces involved in cellular physiology and response to its environment. Besides mechanical one should think of other physical parameters such as pressure, temperature, electro-magnetic fields such as light, et cetera.
References.
 First use of the term "mechanome" by Matthew Lang at MIT


36th Engineering and Test Squadron


Belloneon

The belloneon (or bellonion) was a mechanical musical instrument consisting of twenty-four trumpets and two kettle drums. It was invented in Dresden in 1812 by Johann and Friedrich Kaufmann.


Isichthys


Canvas (GUI)

In computer science and visualization, a canvas is a container that holds various drawing elements (lines, shapes, text, frames containing other elements, etc.). It takes its name from the canvas used in visual arts. It is sometimes called a scene graph because it arranges the logical representation of a user interface or graphical scene. Some implementations also define the spatial representation and allow the user to interact with the elements via a graphical user interface.
Library support.
Various free and open-source canvas or scene-graph libraries allow developers to construct a user interface and/or user-interface elements for their computer programs.
Examples of free and open-source scene-graph canvas options include:
Some canvas modules within various libraries do not provide the power of a full scene-graph - they operate at a lower level which requires programmers to provide code such as mapping mouse-clicks to objects in the canvas. Examples of libraries which include such a canvas module include:
Proprietary canvas libraries include, for example:


Coldplug


Tom-tom drum

A tom drum is a cylindrical drum with no snares, named from the Anglo-Indian and Sinhala language. It was added to the drum kit in the early part of the 20th century. Most toms range in size between in diameter, though floor toms can go as large as . It is not to be confused with a tam-tam, a gong. The Tom is popular and used by players worldwide.
Design history.
The drum called "Thammattama", played by the Sinhala people of Sri Lanka, is used in a number of Buddhist rituals in that country. It is commonly heard in Buddhist temples paired along with the reed instrument called horanava. This may be etymologically derived from the Tamil term "Thappattam" or "Thapp", a frame drum associated with South Indian Tamil culture. However, the tom-tom drums on the Western drum set clearly resemble the Sri Lankan version more than the frame drum.
The British colonists complained loudly about the noise generated by the "tom-toms" of the natives throughout South Asia. It is likely that the term tom-toms thus comes from their experiences in colonial Sri Lanka (then called Ceylon) or South India. The term "tom-tom" also has variants in the Telugu and Hindi languages, but only in Sri Lanka is there an indigenous drum with the same name (thammattama). Perhaps because of Americans' lack of experience with Asian cultures, the term is often misattributed to the Chinese, given that "tam-tam" in Western classical music refers to a Chinese gong.
The first American drum set toms had no rims and were usually what were referred to as "Chinese" tom toms. The pigskin heads were tacked to the wooden shells with metal tacks. Through close collaboration with Gene Krupa's concept of fully tunable toms, the Slingerland drum and banjo company were the first, in 1936, to begin offering fully tuneable tom-toms (top and bottom heads) with metal or wooden rims, tension rods, and lugs. Most Chinese toms were 10 to 14 inches in diameter, but the American drum companies were eventually producing a wider range of diameters and depths. These drums were usually clamped to the bass drum rims or sat in cradles as floor stand drums. The sizes that Krupa chose became the "standard" for many decades and they were 13 × 9″ (mounted) and 16 × 16″ (floor). Later, mounted on three (or, if larger than 16 × 16″, four) legs were attached to the floor tom designs. Together with a snare drum and a bass drum of varying size, the combination of the four drums became a "set". (The term "kit" did not appear until the mid 1960s.)
Later, the mounted toms, known as "hanging toms" or "rack toms", were deepened by one inch each, these sizes being called "power toms". Extra-deep hanging toms, known as "cannon depth", never achieved popularity. All these were double-headed.
Modern versions.
A wide variety of configurations have been available and in use at all levels from advanced student kits upwards. Most toms range in size between in diameter, though floor toms can go as large as .
Classic rack setups.
In the 50s and early 60s, it was common to have only a single hanging tom (a 13") and a single floor tom (16").
A basic rock configuration consists of 12" and 13" hanging toms, and a 16" floor tom with diameter × depth in inches used throughout this article. For a more detailed description of the conventions and their usage, see drum size conventions.
A basic fusion configuration refers to a set-up which has 10", 12" and 14" diameter toms, Note that these terms do not imply drum depths, so for example, the 14" in a fusion setup could have depth 10, 11, 12, or could be a 14×14 floor tom.
The terms "fusion" and "rock" are marketing terms invented by drum manufacturing companies, and there is no absolute definition for them; more a case of an accepted norm.
In the 1950-1980s the standard depth rack toms were 12×8 and 13×9. This "classic" configuration is still popular. Concert toms came in the early 1970s. With Ludwig producing single headed toms in 6x5.5,8x5.5,10x6.5,12x8,13x9,14x10, 15x12 16x14 mounted in pairs on a stand.
"FAST" sizes are 10×8, 12×9, 13×10, etc., a marketing term used by DW, although not unique to DW, but with all drum manufacturers.
The "New standard" sizes - 10×9, 12×10, 13×11, etc. are 2" deeper than what was considered "standard" in the 1950s.
"Power" toms are one inch deeper than standard, with sizes of 10×9 or 10×10, 12×11, 13×12, which overtook the classic setup in popularity during the 1980s.
Square - 10×10, 12×12, 13×13, etc., have been common in the 1980s and 1990s. Hyperdrive are shallow depths made popular initially by Tama: 10×6.5, 12×7, 13×7.5, etc.
Variations.
Single-headed.
Single-headed tom-toms, also known as concert toms, have also been used in drum kits, though their use has fallen off in popularity since the 1970s. "Concert toms" have a single head and a shell slightly shallower than the corresponding double-headed tom. Phil Collins still uses four single-headed rack-mount toms and two floor toms (Gretsch) in his setup. They are generally easier to tune as they have no bottom head to adjust.
The term "concert tom" has also been used to describe double- or single-headed tom-tom drums designed for use in a concert band rather than in a drum kit.
Rototoms.
Rototoms have no shell at all, just a single head and a steel frame. Unlike most other drums, they have a variable definite pitch and some composers write for them as a tuned instrument, demanding specific notes. They can be tuned quickly by rotating the head. Since the head rotates on a thread, this raises or lowers the head relative to the rim of the drum and so increases or decreases the tension in the head.
Gong bass drum.
A gong bass drum (also known as "gong drum"), is a large, single-headed tom often sized at or , with the drumhead being larger than the shell. The sound produced is similar to a bass drum, though it is more open and has longer sustain. They can be mounted with standard floor tom legs, though many drummers mount them at an angle next to the floor tom(s). Notable users include Neil Peart, Stewart Copeland, Bill Bruford, Simon Phillips, Jason Bittner, Mike Portnoy and Dom Howard.
Floor tom.
A floor tom is a double-skin drum, most often but not always as deep as its diameter, traditionally mounted on three legs and to the drummer's right for a right-handed drummer. It is normally the deepest-toned drum played by sticks in the kit, above the bass drum but below all others, and the most resonant, more so than even the bass drum.
Construction and manufacture.
Typically, a tom consists of a shell, chromed or plated metal hardware and head. Shell depth standards vary according to the era of manufacture and the drum style. Tom-toms are typically made in diameters of: , , , , , , , and , with heads to fit.
Tom-toms can be fitted with an adjustable mounting for a floor stand, or attachment to a bass drum or marching rig. They can be single- or double-headed.
Shell.
A crucial factor in achieving superior tone quality and insuring durability, especially with wood, is the creation of perfectly round shells and much research and development has been put into this manufacturing technology.
Shells are often constructed of 6–8 wood plies (often using different woods e. g. mahogany and falkata — birch or maple are commonly used for single-wood plies), solid wood (turned) or man-made materials (e. g. fibreglass, pressed steel, acrylic glass, resin-composite). Wood or composite shells can be finished by laminating in plastic in a large variety of colours and effects (e. g. sparkle or polychromatic); natural wood may be stained or left natural and painted with clear lacquer. Steel is usually chromed, fibreglass self-coloured and acrylic glass tinted or clear.
Hardware.
For drum hardware one or two cast or pressed metal rims attach by threaded tension rods or lugs to nut boxes bolted onto the shell and hold the heads onto the bearing edges of the shell. The tension rod assembly needs to be precision-machined, cast and fitted to enable predictable and secure tuning without inhibiting resonance or introducing extra vibration. All components will be placed under great tension and experience added stresses from playing.
Mounting systems vary greatly, from a simple cast block on the shell which accepts and clamps to a rod attached to a clamp or holder to much more sophisticated arrangements where there is no attachment to the shell, instead a frame clamps to the tuning lugs.
Another sort of rod clamp system allows attachment of the drum to the tom holder without the need of a hole in the drum shell for the rod to pass through. The clamp is attached to the shell at the nodal point with two bolts so as to allow the shell to vibrate freely without degrading the shell's dynamic range and sustain. The nodal point is the location on a shell with the least amount of vibration allowing for the mount to have minimal effect on the resonance of the shell.
Some drummers use a snare stand to hold and to make it easier to position the tom.


Hellenic Aeronautical Engineers Society

The Hellenic Aeronautical Engineers Society (HAES) (Greek: Σύλλογος Ελλήνων Αεροναυπηγών) is the society of professional licensed Aeronautical Engineers in Greece.
The purpose of HAES is to provide a basis where Greek licensed Aeronautical Engineers can fraternize and coordinate scientific and professional efforts to assist the state and support, develop and promote aviation and space activities.
HAES was first registered in 1975 as a society (non commercial) and it is a branch organization of the Hellenic Technical (Engineering) Chambers (Τεχνικό Επιμελητήριο Ελλάδας) in Greece. The Society is a member and the national representative in the International Council of the Aeronautical Sciences (ICAS), the Council of European Aerospace Societies (CEAS) and the European Federation of National Engineering Associations (FEANI).
The society numbers approximately 250 members, almost all having university degrees in Aeronautical Engineering from countries outside Greece (mostly United Kingdom, Italy, Germany, France and the United States) due to practically non-existence of such academic programs in Greece until recently.
The main requirement for one to become a member is to have Professional License in Aeronautical Engineering from the Hellenic Technical Chambers in Greece and be in a good standing with the chamber.


Magic Potion Spin


Rokhlin lemma

In mathematics, the Rokhlin lemma, or Kakutani–Rokhlin lemma is an important result in ergodic theory. It states that an aperiodic measure preserving dynamical system can be decomposed to an arbitrary high tower of measurable sets and a remainder of arbitrarily small measure. It was proven by Vladimir Abramovich Rokhlin and independently by Shizuo Kakutani. The lemma is used extensively in ergodic theory, for example in Ornstein theory and has many generalizations.
Terminology.
Rokhlin lemma belongs to the group mathematical statements such as Zorn's lemma in set theory and Schwarz lemma in complex analysis which are traditionally called lemmas despite the fact that their roles in their respective fields are fundamental.
Statement of the lemma.
Lemma: Let formula_1 be an invertible measure-preserving transformation on a standard measure space formula_2 with formula_3. We assume formula_4 is (measurably) aperiodic, that is, the set of periodic points for formula_4 has zero measure. Then for every integer formula_6 and for every formula_7, there exists a measurable set formula_8 such that the sets formula_9 are pairwise disjoint and such that formula_10.
A useful strengthening of the lemma states that given a finite measurable partition formula_11, then formula_8 may be chosen in such a way that formula_13 and formula_11 are independent for all formula_15.
A topological version of the lemma.
Let formula_16 be a topological dynamical system consisting of a compact metric space formula_17 and a homeomorphism formula_18. The topological dynamical system formula_16 is called minimal if it has no proper non-empty closed formula_4-invariant subsets. It is called (topologically) aperiodic if it has no periodic points (formula_21 for some formula_22 and formula_23 implies formula_24). A topological dynamical system formula_25 is called a factor of formula_16 if there exists a continuous surjective mapping formula_27 which is equivariant, i.e., formula_28 for all formula_29.
Elon Lindenstrauss proved the following theorem:
Theorem: Let formula_16 be a topological dynamical system which has an aperiodic minimal factor. Then for integer formula_6 there is a continuous function formula_32 such that the set formula_33 satisfies formula_9 are pairwise disjoint.
Gutman proved the following theorem:
Theorem: Let formula_35 be a topological dynamical system which has an aperiodic factor with the small boundary property. Then for every formula_36, there exists a continuous function formula_37 such that the set formula_38 satisfies formula_39, where formula_40 denotes orbit capacity.
See also.
Rokhlin's lemma should not be confused with Rokhlin's theorem.


Diamond wire cutting


Synchronous motor

A synchronous electric motor is an AC motor in which, at steady state, the rotation of the shaft is synchronized with the frequency of the supply current; the rotation period is exactly equal to an integral number of AC cycles. Synchronous motors contain multiphase AC electromagnets on the stator of the motor that create a magnetic field which rotates in time with the oscillations of the line current. The rotor with permanent magnets or electromagnets turns in step with the stator field at the same rate and as a result, provides the second synchronized rotating magnet field of any AC motor. A synchronous motor is termed "doubly fed" if it is supplied with independently excited multiphase AC electromagnets on both the rotor and stator.
The synchronous motor and induction motor are the most widely used types of AC motor. The difference between the two types is that the synchronous motor rotates at a rate locked to the line frequency since it does not rely on current induction to produce the rotor's magnetic field. By contrast, the induction motor requires "slip": the rotor must rotate slightly slower than the AC alternations in order to induce current in the rotor winding. Small synchronous motors are used in timing applications such as in synchronous clocks, timers in appliances, tape recorders and precision servomechanisms in which the motor must operate at a precise speed; speed accuracy is that of the power line frequency, which is carefully controlled in large interconnected grid systems.
Synchronous motors are available in self-excited sub-fractional horsepower sizes to high power industrial sizes. In the fractional horsepower range, most synchronous motors are used where precise constant speed is required. These machines are commonly used in analog electric clocks, timers and other devices where correct time is required.
In higher power industrial sizes, the synchronous motor provides two important functions. First, it is a highly efficient means of converting AC energy to work. Second, it can operate at leading or unity power factor and thereby providing power-factor correction.
Type.
Synchronous motors fall under the more general category of "synchronous machines" which also includes the synchronous generator. Generator action will be observed if the field poles are "driven ahead of the resultant air-gap flux by the forward motion of the prime mover". Motor action will be observed if the field poles are "dragged behind the resultant air-gap flux by the retarding torque of a shaft load".
There are two major types of synchronous motors depending on how the rotor is magnetized: "non-excited" and "direct-current excited".
Non-excited motors.
In non-excited motors, the rotor is made of steel. At synchronous speed it rotates in step with the rotating magnetic field of the stator, so it has an almost-constant magnetic field through it. The external stator field magnetizes the rotor, inducing the magnetic poles needed to turn it. The rotor is made of a high-retentivity steel such as cobalt steel. These are manufactured in permanent magnet, reluctance and hysteresis designs:
Reluctance motors.
These have a rotor consisting of a solid steel casting with projecting (salient) toothed poles. Typically there are fewer rotor than stator poles to minimize torque ripple and to prevent the poles from all aligning simultaneously—a position that cannot generate torque. The size of the air gap in the magnetic circuit and thus the reluctance is minimum when the poles are aligned with the (rotating) magnetic field of the stator, and increases with the angle between them. This creates a torque pulling the rotor into alignment with the nearest pole of the stator field. Thus at synchronous speed the rotor is "locked" to the rotating stator field. This cannot start the motor, so the rotor poles usually have squirrel-cage windings embedded in them, to provide torque below synchronous speed. The machine starts as an induction motor until it approaches synchronous speed, when the rotor "pulls in" and locks to the rotating stator field.
Reluctance motor designs have ratings that range from fractional horsepower (a few watts) to about . Very small reluctance motors have low torque, and are generally used for instrumentation applications. Moderate torque, multi-horsepower motors use squirrel cage construction with toothed rotors. When used with an adjustable frequency power supply, all motors in the drive system can be controlled at exactly the same speed. The power supply frequency determines motor operating speed.
Hysteresis motors.
These have a solid smooth cylindrical rotor, cast of a high coercivity magnetically "hard" cobalt steel. This material has a wide hysteresis loop (high coercivity), meaning once it is magnetized in a given direction, it requires a large reverse magnetic field to reverse the magnetization. The rotating stator field causes each small volume of the rotor to experience a reversing magnetic field. Because of hysteresis the phase of the magnetization lags behind the phase of the applied field. The result of this is that the axis of the magnetic field induced in the rotor lags behind the axis of the stator field by a constant angle δ, producing a torque as the rotor tries to "catch up" with the stator field. As long as the rotor is below synchronous speed, each particle of the rotor experiences a reversing magnetic field at the "slip" frequency which drives it around its hysteresis loop, causing the rotor field to lag and create torque. There is a 2-pole low reluctance bar structure in the rotor. As the rotor approaches synchronous speed and slip goes to zero, this magnetizes and aligns with the stator field, causing the rotor to "lock" to the rotating stator field.
A major advantage of the hysteresis motor is that since the lag angle δ is independent of speed, it develops constant torque from startup to synchronous speed. Therefore, it is self-starting and doesn't need an induction winding to start it, although many designs do have a squirrel-cage conductive winding structure embedded in the rotor to provide extra torque at start-up.
Hysteresis motors are manufactured in sub-fractional horsepower ratings, primarily as servomotors and timing motors. More expensive than the reluctance type, hysteresis motors are used where precise constant speed is required.
Permanent-magnet motors.
A permanent-magnet synchronous motor (PMSM) uses permanent magnets embedded in the steel rotor to create a constant magnetic field. The stator carries windings connected to an AC supply to produce a rotating magnetic field (as in an asynchronous motor). At synchronous speed the rotor poles lock to the rotating magnetic field. Permanent magnet synchronous motors are similar to brushless DC motors. Neodymium magnets are the most commonly used magnets in these motors. Although in the last few years, due to rapid fluctuation in the prices of Neodymium magnets, a lot of research has been looking at ferrite magnets as an alternative. Due to the inherent characteristics of the currently available ferrite magnets, the design of the magnetic circuit of these machines needs to be able to concentrate the magnetic flux, one of the most common strategies is the use of spoke type rotors. Currently, the new machines that use ferrite magnets have lower power density and torque density, when compared with machines that use Neodymium magnets.
Permanent magnet motors have been used as gearless elevator motors since 2000.
Most PMSMs require a variable-frequency drive to start. However, some incorporate a squirrel cage in the rotor for starting — these are known as line-start or self-starting PMSMs. These are typically used as higher-efficiency replacements for induction motors (owing to the lack of slip), but need to be specified carefully for the application to ensure that synchronous speed is reached and that the system can withstand the torque ripple during starting.
Permanent magnet synchronous motors are mainly controlled using direct torque control and field oriented control. However, these methods suffer from relatively high torque and stator flux ripples. Predictive control and neural network controllers are recently developed to cope with these isssues.
DC-excited motors.
Usually made in larger sizes (larger than about 1 horsepower or 1 kilowatt) these motors require direct current (DC) supplied to the rotor for excitation. This is most straightforwardly supplied through slip rings, but a brushless AC induction and rectifier arrangement may also be used. The direct current may be supplied from a separate DC source or from a DC generator directly connected to the motor shaft.
Control techniques.
A permanent magnet synchronous motor and reluctance motor requires a control system for operating (VFD or servo drive).
There are a large number of control methods for PMSM, which is selected depending on the construction of the electric motor and the scope.
Control methods can be divided into:
Sinusoidal
Trapezoidal
Synchronous speed.
The synchronous speed of a synchronous motor is given:
in RPM, by:
and in rad·s−1, by:
where:
Examples.
A single-phase, 4-pole (2-pole-pair) synchronous motor is operating at an AC supply frequency of 50 Hz. The number of pole-pairs is 2, so
the synchronous speed is:
A three-phase, 12-pole (6-pole-pair) synchronous motor is operating at an AC supply frequency of 60 Hz. The number of pole-pairs is 6, so the synchronous speed is:
The number of magnetic poles, formula_4, is equal to the number of coil groups per phase. To determine the number of coil groups per phase in a 3-phase motor, count the number of coils, divide by the number of phases, which is 3. The coils may span several slots in the stator core, making it tedious to count them. For a 3-phase motor, if you count a total of 12 coil groups, it has 4 magnetic poles. For a 12-pole 3-phase machine, there will be 36 coils. The number of magnetic poles in the rotor is equal to the number of magnetic poles in the stator.
Construction.
The principal components of a synchronous motor are the stator and the rotor. The stator of synchronous motor and stator of induction motor are similar in construction. With the wound-rotor synchronous doubly fed electric machine as the exception, the stator frame contains "wrapper plate". "Circumferential ribs" and "keybars" are attached to the wrapper plate. To carry the weight of the machine, "frame mounts" and "footings" are required. When the field winding is excited by DC excitation, brushes and slip rings are required to connect to the excitation supply. The field winding can also be excited by a brushless exciter. Cylindrical, round rotors, (also known as non salient pole rotor) are used for up to six poles. In some machines or when a large number of poles are needed, a salient pole rotor is used. The construction of synchronous motor is similar to that of a synchronous alternator. Most of the synchronous motors construction uses the stationary armature and rotating field winding. This type of construction as an advantage than dc motor type where the armature used is of rotating type.
Operation.
The operation of a synchronous motor is due to the interaction of the magnetic fields of the stator and the rotor. Its stator winding, which consists of a 3 phase winding, is provided with a 3 phase supply, and the rotor is provided with a DC supply. The 3 phase stator winding carrying 3 phase currents produces 3 phase rotating magnetic flux (and therefore a rotating magnetic field). The rotor locks in with the rotating magnetic field and rotates along with it. Once the rotor field locks in with the rotating magnetic field, the motor is said to be in synchronization. A single-phase (or two-phase derived from single phase) stator winding is possible, but in this case the direction of rotation is not defined and the machine may start in either direction unless prevented from doing so by the starting arrangements.
Once the motor is in operation, the speed of the motor is dependent only on the supply frequency. When the motor load is increased beyond the breakdown load, the motor falls out of synchronization and the field winding no longer follows the rotating magnetic field. Since the motor cannot produce (synchronous) torque if it falls out of synchronization, practical synchronous motors have a partial or complete squirrel-cage damper (amortisseur) winding to stabilize operation and facilitate starting. Because this winding is smaller than that of an equivalent induction motor and can overheat on long operation, and because large slip-frequency voltages are induced in the rotor excitation winding, synchronous motor protection devices sense this condition and interrupt the power supply (out of step protection).
Starting methods.
Above a certain size, synchronous motors are not self-starting motors. This property is due to the inertia of the rotor; it cannot instantly follow the rotation of the magnetic field of the stator. Since a synchronous motor produces no inherent average torque at standstill, it cannot accelerate to synchronous speed without some supplemental mechanism.
Large motors operating on commercial power frequency include a squirrel-cage induction winding which provides sufficient torque for acceleration and which also serves to damp oscillations in motor speed in operation. Once the rotor nears the synchronous speed, the field winding is excited, and the motor pulls into synchronization. Very large motor systems may include a "pony" motor that accelerates the unloaded synchronous machine before load is applied. Motors that are electronically controlled can be accelerated from zero speed by changing the frequency of the stator current.
Very small synchronous motors are commonly used in line-powered electric mechanical clocks or timers that use the power line frequency to run the gear mechanism at the correct speed. Such small synchronous motors are able to start without assistance if the moment of inertia of the rotor and its mechanical load is sufficiently small [because the motor] will be accelerated from slip speed up to synchronous speed during an accelerating half cycle of the reluctance torque." Single-phase synchronous motors such as in electric wall clocks can freely rotate in either direction unlike a shaded-pole type. See Shaded-pole synchronous motor for how consistent starting direction is obtained.
The operational economics is an important parameter to address different motor starting methods. Accordingly, the excitation of the rotor is a possible way to solve the motor starting issue. In addition, modern proposed starting methods for large synchronous machines include repetitive polarity inversion of the rotor poles during startup.
Applications, special properties, and advantages.
Use as synchronous condenser.
By varying the excitation of a synchronous motor, it can be made to operate at lagging, leading and unity power factor. Excitation at which the power factor is unity is termed "normal excitation voltage". The magnitude of current at this excitation is minimum. Excitation voltage more than normal excitation is called over excitation voltage, excitation voltage less than normal excitation is called under excitation. When the motor is over excited, the back emf will be greater than the motor terminal voltage. This causes a demagnetizing effect due to armature reaction.
The V curve of a synchronous machine shows armature current as a function of field current. With increasing field current armature current at first decreases, then reaches a minimum, then increases. The minimum point is also the point at which power factor is unity.
This ability to selectively control power factor can be exploited for power factor correction of the power system to which the motor is connected. Since most power systems of any significant size have a net lagging power factor, the presence of overexcited synchronous motors moves the system's net power factor closer to unity, improving efficiency. Such power-factor correction is usually a side effect of motors already present in the system to provide mechanical work, although motors can be run without mechanical load simply to provide power-factor correction. In large industrial plants such as factories the interaction between synchronous motors and other, lagging, loads may be an explicit consideration in the plant's electrical design.
Steady state stability limit.
where,
here,
When load is applied, torque angle formula_12 increases. When formula_12 = 90° the torque will be maximum. If load is applied further then the motor will lose its synchronism, since motor torque will be less than load torque. The maximum load torque that can be applied to a motor without losing its synchronism is called steady state stability limit of a synchronous motor.
Other.
Synchronous motors are especially useful in applications requiring precise speed or position control:


Lens mount

A lens mount is an interface – mechanical and often also electrical – between a photographic camera body and a lens. It is a feature of camera systems where the body allows interchangeable lenses, most usually the rangefinder camera, single lens reflex type, single lens mirrorless type or any movie camera of 16 mm or higher gauge. Lens mounts are also used to connect optical components in instrumentation that may not involve a camera, such as the modular components used in optical laboratory prototyping which join via C-mount or T-mount elements.
Mount types.
A lens mount may be a screw-threaded type, a bayonet-type, or a breech-lock (friction lock) type. Modern still camera lens mounts are of the bayonet type, because the bayonet mechanism precisely aligns mechanical and electrical features between lens and body. Screw-threaded mounts are fragile and do not align the lens in a reliable rotational position, yet types such as the C-mount interface are still widely in use for other applications like video cameras and optical instrumentation.
Bayonet mounts generally have a number of tabs (often three) around the base of the lens, which fit into appropriately sized recesses in the lens mounting plate on the front of the camera. The tabs are often "keyed" in some way to ensure that the lens is only inserted in one orientation, often by making one tab a different size. Once inserted the lens is fastened by turning it a small amount. It is then locked in place by a spring-loaded pin, which can be operated to remove the lens.
Lens mounts of competing manufacturers (Sony, Nikon, Canon, Contax/Yashica, Pentax, etc.) are almost always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance from the lens mount to the film or sensor can also be different. Many allege that these incompatibilities are due to the desire of manufacturers to "lock in" consumers to their brand.
In movie cameras, the two most popular mounts in current usage on professional digital cinematography cameras are Arri's PL-mount and Panavision's PV-mount. The PL-Mount is used both on Arri and RED digital cinematography cameras, which are the most used cameras for films shot in digital. The Panavision mounts are exclusively used with Panavision lenses, and thus are only available on Panaflex cameras or third-party cameras "Panavised" by a Panavision rental house, whereas the PL-mount style is favored with most other cameras and cine lens manufacturers. Both of these mounts are held in place with locating pins and friction locking rings. Other mounts which are now largely historical or a minority in relation to current practices are listed below.
List of lens mounts.
For small camera modules, used in e.g. CCTV systems and machine vision, a range of metric thread mounts exists. The smallest ones can be found also in e.g. cellphones and endoscopes. The most common by far is the M12x0.5, followed by M8x0.5 and M10x0.5.
Focusing lens mount.
The axial adjustment range for focusing Ultra wide angle lenses and some Wide-angle lenses in large format cameras is usually very small.
So some manufacturers (e.g. Linhof) offered special focusing lens mounts, so-called wide-angle focusing accessories for their cameras.
With such a device, the lens could be focused precisely without moving the entire front standard.
Secondary lens mount.
Secondary lens refers to a multi-element lens mounted either in front of a camera's primary lens, or in between the camera body and the primary lens.
(D)SLR camera & interchangeable-lens manufacturers offer lens accessories like extension tubes and secondary lenses like teleconverters, which mount in between the camera body and the primary lens, both using and providing a primary lens mount. Various lensmakers also offer optical accessories that mount in front of the lens; these may include wide-angle, telephoto, fisheye, and close-up or macro adapters.
Canon PowerShot A and Canon PowerShot G cameras have a built-in or non-interchangeable primary (zoom) lens, and Canon has "conversion tube" accessories available for some Canon PowerShot camera models which provide either a 52mm or 58mm "accessory/filter" screw thread. Canon's close-up, wide- (WC-DC), and tele-conversion (TC-DC) lenses have 2, 3, and 4-element lenses respectively, so they are multi-element lenses and not diopter "filters".
Lens mount adapters.
Lens mount adapters are designed to attach a lens to a camera body with non-matching mounts. Generally, a lens can be easily adapted to a camera body with a smaller flange focal distance by simply adding space between the camera and the lens. When attempting to adapt a lens to a camera body with a larger flange focal distance, the adapter must include a secondary lens in order to compensate. This has the side effect of decreasing the amount of light that reaches the sensor, as well as adding a crop factor to the lens. Without the secondary lens, these adapters will function as an extension tube and will not be able to focus to infinity.
Notes.
4/3's published facts:
So:
NOTE:
Some published reviews of 4/3 instead cite the (female) "outside diameter" of the lens or mount as ~50mm (and micro-4/3 as ~44mm), and not the appropriate "major" diameter (D) ~44mm which is the camera body's female mount inside-diameter and the lens's male mount outside-diameter (micro-4/3 ~38mm).


Tubular-pneumatic action

"Tubular-pneumatic action" refers to an apparatus used in many
pipe organs built during the late 19th and early 20th centuries. The term "tubular" refers to the extensive use of lead tubing to connect the organ's console to the valves that control the delivery of "wind" (air under pressure) to the organ's pipes. Many such organs are extant 100 or more years after their construction.
Description.
In any organ, each pipe has a valve located at its foot which responds to the organist's commands from the console's keyboard, pedalboard and stop controls. These valves are contained in windchests upon which the organ's pipework is set. Any type of apparatus that connects an organ's console with its windchest is referred to as its "action". An organ that utilizes tubular-pneumatic action is commonly called a "tubular-pneumatic organ".
It seems the first use of this action was in 1851, in Willis' Great Exhibition organ, though it was only very limited. It appears that the first organ using tubular-pneumatic action throughout was by T.C. Lewis at St Andrew's Hall, Glasgow, in 1877.
Invention.
Until the advent of the tubular-pneumatic action, all organs used a system of levers and wooden rods called trackers to transmit the action of the keys and stops to the valves contained within the windchests. This necessitated a close proximity between the console and the chests. In 1845, Prosper-Antoine Moitessier, an organ-builder of Montpellier, France, patented the tubular-pneumatic system which allowed the console to be at a much greater distance from the organ pipes. Cavaillé-Coll, Henry Willis and Edwin Horsell Pulbrook were pioneers in perfecting and introducing the pneumatic action. The development of the tubular-pneumatic type of organ marked the first departure from the tracker organ style of construction that had been used for hundreds of years.
Operation.
The operation of a tubular-pneumatic organ is accomplished by a change of air pressure within lead tubes of about inside diameter that connect the organ's console to its windchest. A separate tube is needed for each manual key, pedal key and stop control on the console. A large four manual organ can require over 300 individual tubes.
Two basic types of tubular-pneumatic actions were used: the "pressure" system and the more popular "exhaust" system. Both use three major components for each key and stop: a valve (within the console), a pneumatic (within the windchest), and a lead tube that connects them.
In the pressure system, the air in the tube and the pneumatic are normally at atmospheric pressure. Depressing a key increases the pressure in the tube, inflating the pneumatic, which opens the pipe's valve.
In the exhaust system, the pneumatic and tube normally contain windchest pressure. Depressing a key lets this pressure exhaust, which collapses the pneumatic and opens the pipe's valve.
Advantages and disadvantages.
The advantages of the tubular-pneumatic action over the mechanical tracker action are a lightness of touch and the flexibility of console location. Although the former was a great improvement over the tracker organ, the console location was still limited to around from the pipework.
While some considered the tubular-pneumatic action to be a great achievement in organ building, others thought just the opposite. Sir John Stainer, organist at St. Paul's, called it a "triumph of mechanical skill", while the eminent English organist W. T. Best called it "a complete failure; you cannot play a triplet on the Trumpet, and I consider it the most damnnable invention ever placed inside an organ".
The major disadvantage of tubular-pneumatic action is its sluggish response. This becomes more prevalent as the distance between the console and the pipework is increased. In organs whose divisions are located at various distances from the console, this slow response causes an undesirable time lag between the speech of the divisions.
Another disadvantage over a tracker action organ is a lack of "feel" and control of attack by the organist, a trait that is present in all non-tracker action organs.
Decline of usage.
With the application of electric power to pipe organ action, the use of tubular-pneumatic action quickly declined. An organ with electro-pneumatic action or direct electric action has the lightness of touch of a tubular-pneumatic organ, but a faster response, and the console can be in any remote location. The console can also be movable, with only a cable connecting it to the rest of the organ.
By the 1920s, tubular-pneumatic organs were rarely built.
Electro-pneumatic chests, however, frequently have sealed wood channels (tubes) in their wooden structural elements and bottom boards, usually consisting of wind channels running between the pipe valve and the primary with its electromagnets. Organ builders harnessed the difference in air pressures inside and outside the organ to do heavier work, taking the weak force of an electromagnet and multiplying its effect pneumatically to pull open pipe valves. In a sense, therefore, part of the tubular-pneumatic heritage was developed in later non-tracker organ building.


List of Razer products

This is a list of various Razer gaming hardware products. Individual products may have their own article, please see the navbox at the bottom if a product is not listed here.
Keyboards.
Razer Huntsman series feature optical switches, whereas BlackWidow family series feature mechanical switches.
BlackWidow Lite series is designed for use in professional work in addition to gaming. In addition to the same portable design as the BlackWidow Tournament series (below), the BlackWidow Lite ships with separate o-rings for extra sound dampening and fatigue control, Individually white-backlit keys on the keyboard which enable productivity in low light, and fully adjustable brightness controls.
BlackWidow Tournament series is designed for portability, as it features detachable cable, tenkeyless, and compact size.
Headsets.
1. Razer Kraken Ultimate
2. Razer Kraken X
3. Razer Kraken X USB
4. Razer Blackshark
5. Razer Blackshark V2 and SE
6. V Blackshark V2 PRO Wireless
7. Razer Blackshark V2 X
8. Razer Opus Wireless
9. Razer Hammerhead True Wireless
10. Razer Hammerhead True Wireless PRO
11. Razer Hammerhead USB-C ANC
12. Razer Kaira Pro Wireless and for XBOX
13. Razer Kraken Pro V2
14. Razer Kraken Tournament Edition
15. Razer Man O' War Wireless
16. Razer Kraken Kitty Ears Edition
17. Razer Nari Ultimate and XBOX
18. Razer Thresher 7.1
19. Razer Kraken
20. Razer Nari Essential
eGPUs.
Compatibility for Razer Blade models with Razer Core eGPU's are as follows:
For specific model numbers see table below:
Model Number Blade Model Supported
RZ09-00710 Razer Blade 17" (2011) No
RZ09-00830 Razer Blade 17" (2012) No
RZ09-00990 Razer Blade Pro 17" (2013) No
RZ09-00991 Razer Blade Pro 17" (2013) No
RZ09-01020 Razer Blade 14" (2013) No
RZ09-01021 Razer Blade 14" (2013) No
RZ09-01161 Razer Blade 14" (2014) No
RZ09-01171E1 Razer Blade Pro 17" (2014) No
RZ09-01171E5 Razer Blade Pro 17" (2015) No
RZ09-01301 Razer Blade 14" (2015) No
RZ09-01302 Razer Blade 14" (2015) No
RZ09-01652 Razer Blade 14" (2016) - GTX970M Yes
RZ09-01662 Razer Blade Pro 17" (2016) Yes
RZ09-01663 Razer Blade Pro 17" (2017) Yes
RZ09-01682 Razer Blade Stealth 12.5' (2016) - Intel 6500U Yes
RZ09-01952 Razer Blade 14" (2016) - Intel 6700HQ - GTX1060 Yes
RZ09-01953 Razer Blade 14" (2017) - Intel 7700HQ - GTX1060 Yes
RZ09-01962 Razer Blade 12.5" (2016) - Intel 7500U Yes
RZ09-01963 Black Razer Blade Stealth 13" (2017) - Intel 7500U Yes
RZ09-01964 Gunmetal Razer Blade Stealth 13" (2017) - Intel 7500U Yes
RZ09-02202 Razer Blade 17" (2017) - Full HD - GTX 1060 Yes
RZ09-02385 Razer Blade 15" (2018) - Advance Yes
RZ09-02386 Razer Blade 15" (2018) - Advance Yes
RZ09-02393 Gunmetal Razer Blade Stealth 13" (2017) Intel 8550U Yes
RZ09-02394 Black Razer Blade Stealth 13" (2017) Intel 8550U Yes
RZ09-02705 Razer Blade 15" (2018) - Base Model Yes
RZ09-02810 Razer Blade Stealth 13" (2019) Yes
RZ09-02812 Quartz Razer Blade Stealth 13" (2019) Yes
RZ09-02886 Razer Blade 15" (2019) - Advance Yes
RZ09-02887 Razer Blade 15" (2019) - Advance Yes
RZ09-02888 Razer Blade 15" (2019) - Advance Yes


FPT Industries

FPT Industries was formed in July 1939 as Fireproof Tanks Ltd (commonly known as FPT) As a subsidiary of Airspeed Ltd at Portsmouth Airport in response to an Air Ministry requirement for the development and manufacture of self-sealing fuel tanks for the impending war with Germany.
The intention of the board of directors was to commence work on the manufacture of self-sealing fuel tanks for aircraft entering service with the Royal Air Force, the highest priority being the Fairey Battle single engined bomber which although obsolete was regarded as a front line bomber by the Royal Air Force.
The early tanks were of welded aluminium structure with the sealing material applied as a composite layer on the outside. A major problem with welded aluminium tanks is weld decay and metal fatigue in the seams due to vibration in service. In response to this, the company started to develop flexible fuel bladders in the early 1940s. One of the earliest examples of this was a composite flexible fuel bladder with self-sealing coatings for the Supermarine Spitfire MkIX.
Post war.
During the war years and into the emerging jet age, Fireproof Tanks Ltd developed new technologies in rubber formulation, moulding and sheet production in order to remain a leader in other specialist markets such as the creation of hovercraft skirts. Working with Saunders Roe at Cowes on the Isle of Wight, the company became so important to the hovercraft industry that the now renamed FPT Industries was bought by the British Hovercraft Corporation in 1966.
Rationalisation of the aircraft industry.
The British Hovercraft Corporation was bought out by Westland Helicopters of Yeovil and a period of stability came as Westlands developed cutting edge composite material manufacture as part of their approach to advanced helicopter design and hovercraft construction. This paid dividends with advances in rotor blade design such as BERP later seen on the Westland Lynx and EH101 helicopters.
Post 1990 and the GKN buyout.
In the 1990s, Westland Group were purchased by GKN Plc who restructured the businesses before selling their shares in Westland Helicopters to Agusta of Italy. Finding the advanced composite business that Westlands had developed attractive, GKN retained the other Westland companies and renamed them as GKN Aerospace.
During this time, FPT Industries diversified again by developing advanced materials for helicopter Emergency Flotation Systems (EFS) and now manufactures EFS equipment for many large commercial and military helicopter types.
GKN Aerospace Portsmouth, as the business is now known, still manufacture self-sealing fuel tanks, and other fuel systems as well as helicopter EFS.
GKN Aerospace Portsmouth, together with Portsmouth Aviation and Hants & Sussex Aviation, are now all that remain of the once large aircraft manufacturing base at Portsmouth Airport(UK) which built aircraft such as the Airspeed Oxford, the Horsa glider and components for the Hawker Siddeley Trident.


Noise (electronics)

In electronics, noise is an unwanted disturbance in an electrical signal. Noise generated by electronic devices varies greatly as it is produced by several different effects.
In communication systems, noise is an error or undesired random disturbance of a useful information signal. The noise is a summation of unwanted or disturbing energy from natural and sometimes man-made sources. Noise is, however, typically distinguished from interference, for example in the signal-to-noise ratio (SNR), signal-to-interference ratio (SIR) and signal-to-noise plus interference ratio (SNIR) measures. Noise is also typically distinguished from distortion, which is an unwanted systematic alteration of the signal waveform by the communication equipment, for example in signal-to-noise and distortion ratio (SINAD) and total harmonic distortion plus noise (THD+N) measures.
While noise is generally unwanted, it can serve a useful purpose in some applications, such as random number generation or dither.
Noise types.
Different types of noise are generated by different devices and different processes. Thermal noise is unavoidable at non-zero temperature (see fluctuation-dissipation theorem), while other types depend mostly on device type (such as shot noise, which needs a steep potential barrier) or manufacturing quality and semiconductor defects, such as conductance fluctuations, including 1/f noise.
Thermal noise.
Johnson–Nyquist noise (more often thermal noise) is unavoidable, and generated by the random thermal motion of charge carriers (usually electrons), inside an electrical conductor, which happens regardless of any applied voltage.
Thermal noise is approximately white, meaning that its power spectral density is nearly equal throughout the frequency spectrum. The amplitude of the signal has very nearly a Gaussian probability density function. A communication system affected by thermal noise is often modelled as an additive white Gaussian noise (AWGN) channel.
Shot noise.
Shot noise in electronic devices results from unavoidable random statistical fluctuations of the electric current when the charge carriers (such as electrons) traverse a gap. If electrons flow across a barrier, then they have discrete arrival times. Those discrete arrivals exhibit shot noise. Typically, the barrier in a diode is used. Shot noise is similar to the noise created by rain falling on a tin roof. The flow of rain may be relatively constant, but the individual raindrops arrive discretely.
The root-mean-square value of the shot noise current "i"n is given by the Schottky formula.
where "I" is the DC current, "q" is the charge of an electron, and Δ"B" is the bandwidth in hertz. The Schottky formula assumes independent arrivals.
Vacuum tubes exhibit shot noise because the electrons randomly leave the cathode and arrive at the anode (plate). A tube may not exhibit the full shot noise effect: the presence of a space charge tends to smooth out the arrival times (and thus reduce the randomness of the current). Pentodes and screen-grid tetrodes exhibit more noise than triodes because the cathode current splits randomly between the screen grid and the anode.
Conductors and resistors typically do not exhibit shot noise because the electrons thermalize and move diffusively within the material; the electrons do not have discrete arrival times. Shot noise has been demonstrated in mesoscopic resistors when the size of the resistive element becomes shorter than the electron–phonon scattering length.
Flicker noise.
Flicker noise, also known as 1/"f" noise, is a signal or process with a frequency spectrum that falls off steadily into the higher frequencies, with a pink spectrum. It occurs in almost all electronic devices and results from a variety of effects.
Burst noise.
Burst noise consists of sudden step-like transitions between two or more discrete voltage or current levels, as high as several hundred microvolts, at random and unpredictable times. Each shift in offset voltage or current lasts for several milliseconds to seconds. It is also known a "popcorn noise" for the popping or crackling sounds it produces in audio circuits.
Transit-time noise.
If the time taken by the electrons to travel from emitter to collector in a transistor becomes comparable to the period of the signal being amplified, that is, at frequencies above VHF and beyond, the transit-time effect takes place and the noise input impedance of the transistor decreases. From the frequency at which this effect becomes significant, it increases with frequency and quickly dominates other sources of noise.
Coupled noise.
While noise may be generated in the electronic circuit itself, additional noise energy can be coupled into a circuit from the external environment, by inductive coupling or capacitive coupling, or through the antenna of a radio receiver.
Mitigation.
In many cases noise found on a signal in a circuit is unwanted. There are many different noise reduction techniques that can reduce the noise picked up by a circuit.
Quantification.
The noise level in an electronic system is typically measured as an electrical power "N" in watts or dBm, a root mean square (RMS) voltage (identical to the noise standard deviation) in volts, dBμV or a mean squared error (MSE) in volts squared. Examples of electrical noise-level measurement units are dBu, dBm0, dBrn, dBrnC, and dBrn("f"1 − "f"2), dBrn(144-line). Noise may also be characterized by its probability distribution and noise spectral density "N"0("f") in watts per hertz.
A noise signal is typically considered as a linear addition to a useful information signal. Typical signal quality measures involving noise are signal-to-noise ratio (SNR or "S"/"N"), signal-to-quantization noise ratio (SQNR) in analog-to-digital conversion and compression, peak signal-to-noise ratio (PSNR) in image and video coding and noise figure in cascaded amplifiers. In a carrier-modulated passband analogue communication system, a certain carrier-to-noise ratio (CNR) at the radio receiver input would result in a certain signal-to-noise ratio in the detected message signal. In a digital communications system, a certain "E"b/"N"0 (normalized signal-to-noise ratio) would result in a certain bit error rate. Telecommunication systems strive to increase the ratio of signal level to noise level in order to effectively transfer data. Noise in telecommunication systems is a product of both internal and external sources to the system.
Noise is a random process, characterized by stochastic properties such as its variance, distribution, and spectral density. The spectral distribution of noise can vary with frequency, so its power density is measured in watts per hertz (W/Hz). Since the power in a resistive element is proportional to the square of the voltage across it, noise voltage (density) can be described by taking the square root of the noise power density, resulting in volts per root hertz (formula_2). Integrated circuit devices, such as operational amplifiers commonly quote equivalent input noise level in these terms (at room temperature).
Dither.
If the noise source is correlated with the signal, such as in the case of quantisation error, the intentional introduction of additional noise, called dither, can reduce overall noise in the bandwidth of interest. This technique allows retrieval of signals below the nominal detection threshold of an instrument. This is an example of stochastic resonance.


LVOA-C

The LVOA-C is a variant of the M4 Carbine manufactured by North Carolina-based War Sport Industries.
Specifications.
The LVOA-C (manufactured by War Sport Industries by Inventor Joey Boswell) is a direct gas-impingement (DGI) operated rifle based on the AR-15. It features a proprietary barrel shroud with an integrated muzzle brake/flash suppressor which serves its intended manufacturing purpose to be a close quarter combat weapon with a low visibility operation application (LVOA). The sporting rifle features both chamber options of 5.56X45mm NATO rounds and .223 Wylde.
The LVOA-C weighs unloaded ( with a 30-round magazine) and measures in length ( with a closed stock). It has been widely used by private military companies for overseas and domestic operations due to its reliability, low recoil and visual signature.
History.
According to War Sport Industries, the rifle was developed as its support "Low Visibility Operation / Applications for the modern war fighter." in an effort to provide a relevant response to the current unconventional warfare requiring high mobility and low visibility in confined environments. In 2018, War Sport was acquired by Zrodelta who now maintains the LVOA weapons line.
Media presence.
The LVOA-C has been highly advertised in video games and movies for its engaging design and innovative proprietary barrel shroud. It is present in Ubisoft's "Tom Clancy's The Division" video game franchise and "Tom Clancy's Ghost Recon Wildlands" . It is also a weapon available in Tencent Games' battle royale shooter "Ring of Elysium" and Battlestate Games' "Escape from Tarkov". There is a class setup in "" where you can create a version of the LVOA rifle. In Call Of Duty Mobile, the Base M4 Model is an LVOA-C. Its media presence has been a major factor in the recent success of War Sport Industries, which saw its personnel roster growing from "two employees, to over twenty" from 2013 to 2016.


Banjo (wood lathe)

In the craft of woodturning, a banjo is a common term for a fixture on the wood lathe, mounted on the lathe's bed, for holding the toolrest. It allows for adjustment of the toolrest in various positions, by the lathe operator, making it possible to hold the turning tool in the most convenient position for removing material from the spinning wood.
The chosen position of the fixture can be locked in place on the lathe's bed in various ways, the most common method being a lever at the forward end of the fixture which acts upon an eccentric shaft with an attached clamp to secure the fixture to the lathe's bed.


Patrick E. Haggerty

Patrick Eugene Haggerty (March 17, 1914 – October 1, 1980) was an American engineer and businessman. He was a co-founder and former president and chairman of Texas Instruments, Incorporated. Haggerty is most responsible for turning a small Texas oil exploration company into the leader in semiconductors that Texas Instruments is today. Under his influence, the company invested in transistors when their commercial value was still much in question; his company created the first silicon transistor, the first commercial transistor radio, and the first integrated circuit.
Early life.
Pat Haggerty was born in Harvey, North Dakota, the son of Michael Eugene and Lillian (Evenson) Haggerty in 1914. In 1936, Pat graduated summa cum laude from the Marquette University School of Electrical Engineering.
Career.
In November 1945 Haggerty joined Geophysical Service Incorporated (GSI) in Dallas as general manager of the newly formed Laboratory and Manufacturing Division, with responsibility for developing the research, engineering, and manufacturing phases of the company's operations. In December 1951 GSI became Texas Instruments Incorporated. In 1951 Haggerty became executive vice president and director, in 1958 president, and in 1966 chairman, a post he held until retiring.
While at Texas Instruments, Haggerty developed his concepts of Strategic Management. This resulted in his objectives, strategies, tactics (OST) system of managing innovation.
Haggerty was active in the Institute of Radio Engineers (IRE), serving as its president in 1962. He was co-chair of the committee that merged the IRE and the American Institute of Electrical Engineers (AIEE) into the present Institute of Electrical and Electronics Engineers (IEEE). Haggerty was a Fellow of the IEEE. In 1968 Haggerty was awarded the IEEE Founders Medal "For outstanding contributions to the leadership of the electrical and electronics engineering profession, with special reference to the development of the worldwide semiconductor industry and service to the profession through his contributions leading to the creation of the IEEE.". In 1969, he was the IRI Medal recipient, awarded by the Industrial Research Institute.
Legacy.
Haggerty and his wife left part of their estate to found a museum of art at his alma mater which led to the founding of the Patrick and Beatrice Haggerty Museum of Art.


Maiden flight

The maiden flight, also known as first flight, of an aircraft is the first occasion on which an aircraft leaves the ground under its own power. The same term is also used for the first launch of rockets.
The maiden flight of a new aircraft type is always a historic occasion for the type and can be quite emotional for those involved. In the early days of aviation it could be dangerous, because the exact handling characteristics of the aircraft were generally unknown. The maiden flight of a new type is almost invariably flown by a highly experienced test pilot. Maiden flights are usually accompanied by a chase plane, to verify items like altitude, airspeed, and general airworthiness.
A maiden flight is only one stage in the development of an aircraft type. Unless the type is a pure research aircraft (such as the X-15), the aircraft must be tested extensively to ensure that it delivers the desired performance with an acceptable margin of safety. In the case of civilian aircraft, a new type must be certified by a governing agency (such as the Federal Aviation Administration in the United States) before it can enter operation.
Notable maiden flights (aircraft).
An incomplete list of maiden flights of notable aircraft types, organized by date, follows.


Ngelik

The ngelik (or lik) is a part of an Indonesian gamelan composition that contrasts from the surrounding section, either the ompak or merong. It is also sometimes called the "gendhing proper", in contrast to the bubuka gendhing (i.e. ompak).
The ngelik is often associated with a higher pitch, and is usually the part where the gerong sings the main melody of the composition. As many ketawang have the same ompak, the ngelik can be the main determinant of what the piece is.
Ngelik vary in length, but are usually longer than the surrounding ompak in a ketawang, the same length as the ompak in a ladrang, and the same length as the merong in a gendhing. The latter two are typically one gongan in length (like the surrounding section), whereas the ketawang ngelik is usually three or four gongan.


International Electrotechnical Vocabulary

The International Electrotechnical Vocabulary (IEV) serves to promote the global unification of terminology in the field of electrotechnology, electronics and telecommunications. It is developed by IEC Technical Committee 1 (Terminology), and published as both the IEC 60050 series of standards and online as the Electropedia. The Electropedia database contains English and French definitions for more than 20 000 concepts, and provides terms in up to 16 other languages.
International Electrotechnical Vocabulary – IEV – Electropedia.
First edition of the IEV.
In 1927 agreement was reached on the system of classification into groups and sections, the system of numbering the terms and definitions, the approximate extent of the IEV and other important items. The first edition of the IEV was published in 1938 with 2000 terms and definitions in English and French, and terms in German, Italian, Spanish and Esperanto. It was the outcome of patient work over 28 years.
The IEV grows and goes online: Electropedia.
Since 1938, although the aim of the IEV remains unchanged – to provide precise, brief and correct definitions of internationally accepted concepts in the field of electrotechnology, electronics and telecommunications – the scope of the IEV has expanded in line with the expansion of the electrotechnical industry.
The number of IEC technical committees is now more than 90, with almost as many subcommittees, and there are more than 20000 entries in the IEV, covering more than 80 subject areas. The terms and definitions are provided in English and French, and equivalent terms are provided in Arabic, Chinese, Czech, Finnish, German, Italian, Japanese, Norwegian (Bokmål and Nynorsk), Polish, Portuguese, Russian, Serbian, Slovenian, Spanish and Swedish (coverage varies by subject area). Traditionally the IEV was developed and published as a series of International Standards, initially under the reference number IEC 50 and later renumbered as IEC 60050, with each part of the standard covering a given subject, such as circuit theory, live working and electrobiology. The online version of the IEV, known as Electropedia, was launched on 2 April 2007.
Electropedia becomes a database standard.
As a collection of items managed in a database, the IEV is an ideal international standard to be managed under IEC’s database procedure. Through the use of a web-accessible database and electronic communication a validation team comprising experts appointed by and acting as delegates on behalf of their National Committees evaluate and validate requests to change the database. The change can comprise an addition or deletion, a revision (editorial or technical revision) or a simple correction, and can apply to one or many items in the database. The database procedure encompasses the comment gathering and validation stages of the traditional standards development process and allows for both a rapid procedure as well as the traditional procedure.
Future evolution.
The IEC Technical Committee 1, Terminology, is currently considering whether there is interest in the IEC community to evolve the vocabulary towards an electrotechnology ontology covering electrical, electronic and related technologies.


Curlew (steamboat)

Curlew was built in 1856 as a wooden-hulled propeller freight boat for the run between Providence, Rhode Island and New York. She served in several capacities during the American Civil War.
Merchant service.
The wooden propeller steamer "Curlew", was built in 1856 by Samuel Sneden of Greenpoint, New York for the Commercial Steamboat Company of Providence, Rhode Island. She was equipped with a direct-acting, two cylinder, vertical engine with a bore of and a stroke of . The boiler was on the main deck. "Curlew" was rigged as a three-masted schooner as were many of the propeller steamers in this service. She was configured with a full length spar deck which was enclosed above the main deck.
"Curlew" sank off of Point Judith, Rhode Island in May 1859 when a steam pipe burst and she began to fill with water. She was salvaged and a new boiler and engine were installed in 1860.
Civil War service.
"Curlew" was purchased for $44,000 by the U.S. Navy in 1861 during the American Civil War for the South Atlantic Blockading Squadron. She was outfitted as a gunboat with armament consisting of a 30-pounder rifled gun on the foredeck and six 32-pounder smoothbores on the main deck. "Curlew" participated in the expedition to Port Royal, South Carolina under the command of Acting Lieutenant P.G. Watmough. When her machinery proved to be inadequate she was towed to New York by the transport "Baltic" arriving on 21 November 1861 to be returned to her owners before the sixty-day trial period expired.
"Curlew" was chartered by the Quartermaster's Department in October 1862 and voyaged as far as New Orleans, Louisiana under Captain H.N. Parrish.
In the panic over the commerce raider , "Curlew" was again chartered in June 1863 for use as a gunboat, this time by the Navy Department. She was returned in October of that year.
Final voyage.
Back in commercial service "Curlew" inaugurated a freight service between New York and Baltimore, Maryland. She cleared Baltimore on 5 November 1863 and proceeded down the bay for New York with a full cargo. Near midnight on a dark, cloudy night she collided with the northbound steamer "Louisiana" near Point Lookout, Maryland hitting "Louisiana" near midships on the port side. "Curlew" sank but Captain Parrish and the crew rowed to safety at Point Lookout. "Louisiana" suffered damage and was towed to Baltimore.
Notes on tonnage.
"Curlew" was listed in the Custom House Register in Providence at 343 tons burden. The register dimensions shown in the box also result in that number when entered in the contemporary tonnage equation. The New York Marine Register and the succeeding American Lloyds Register both show 380 tons. The Navy appears to quote 380 tons from those registers. In February 1862 the registration was changed to New York and the tonnage remeasured at 557.
Other vessels.
A ferryboat "Curlew" of 392 tons, which was built in 1853, was purchased by the Quartermaster's Department for use during the Civil War.


Carcano

Carcano is the frequently used name for a series of Italian bolt-action, magazine-fed, repeating military rifles and carbines. Introduced in 1891, this rifle was chambered for the rimless 6.5×52mm Carcano round ("Cartuccia Modello 1895"). It was developed by the chief technician Salvatore Carcano at the Turin Army Arsenal in 1890, and was originally called the Modello (model) 91 or simply M91. Successively replacing the previous Vetterli-Vitali rifles and carbines in 10.35×47mmR, it was produced from 1892 to 1945. The M91 was used in both rifle ("fucile") and shorter-barreled carbine ("moschetto") form by most Italian troops during World War I and by Italian and some German forces during World War II. The rifle was also used during the Winter War by Finland, and again by regular and irregular forces in Syria, Libya, Tunisia and Algeria during various postwar conflicts in those countries.
The Type I Carcano rifle was produced by Italy for the Japanese Empire prior to World War II. After the invasion of China, all Arisaka production was required for use of the Imperial Army, so the Imperial Navy contracted with Italy for this weapon in 1937. The Type I is based on the Type 38 rifle and uses a Carcano action, but retains the Arisaka/Mauser type 5-round box magazine. The Type I was used primarily by Japanese Imperial Naval Forces and was chambered for the Japanese 6.5×50mm Arisaka cartridge. Approximately 60,000 Type I rifles were produced by Italian arsenals for Japan.
A Carcano M38 was used by Lee Harvey Oswald to assassinate United States President John F. Kennedy on November 22, 1963 in Dallas, TX.
History.
Although this rifle is often called "Mannlicher–Carcano", especially in American parlance, neither that designation nor the name "Mauser–Parravicino" is correct. Its official designation in Italian is simply Modello 1891, or M91 ("il novantuno"). The magazine system uses en bloc charger clips which were originally developed and patented by Ferdinand Mannlicher, but the actual shape and design of the Carcano clip is derived from the German Model 1888 Commission Rifle.
Until 1938, all M91 rifles and carbines were chambered for the rimless 6.5×52mm Modello 1895 cartridge, using a round-nose metal case bullet of 160 grains weight at approximately 2,000-2,400 ft/s muzzle velocity, depending upon barrel length. At least one small arms authority noted inconsistencies in powder types in arsenal-loaded 6.5×52mm military ammunition, often with different powder types and ammunition lots intermixed within a single clip of ammunition. The practice of intermixing powder types and ammunition lots in clipped rifle ammunition was generally avoided by arsenals of other nations, as it frequently resulted in varying bullet velocities and excessive bullet dispersion on the target.
After reports of inadequate performance at both short and long ranges during the campaigns in Italian North Africa (1924-1934), and the Second Italo-Abyssinian War (1934), the Italian army introduced a new short rifle in 1938, the Modello 1938, together with a new cartridge in 7.35×51mm caliber. In addition to the slightly larger caliber, Italian ordnance designers introduced a spitzer-type bullet for the new cartridge, with the tip filled with aluminum to produce an unstable (tumbling) projectile upon impact in soft tissue (a design most likely copied from the .303 British Mk VII bullet).
However, the Italian government was unable to successfully mass-produce the new arms in adequate quantities before the onset of war, and in 1940, all rifle and ammunition production reverted to 6.5 mm, but no 7.35 mm Mod. 38 rifles nor carbines were ever re-barreled to the old 6.5×52mm caliber. Some Italian troops serving on the Russian front were armed with 7.35 mm Mod. 1938 rifles, but exchanged them in 1942 for 6.5×52 mm arms.
Approximately 94,500 7.35mm Modello 1938 rifles were shipped to Finland, where they were known as "Terni" carbines (from the Terni stamp with the royal crown, the logo or seal of the "Regia fabbrica d’armi di Terni" arsenal where they were manufactured). They were primarily used by security and line-of-communications troops during the Winter War of 1939–1940, though some frontline troops were issued the weapon. According to reports, the Finns disliked the rifle. With its non-standard 7.35 mm caliber, it was problematic to keep frontline troops supplied with good quality, or any ammunition at all, and its non-adjustable rear sight (fixed for 200 m) made it ill-suited for use in precision shooting at the varied ranges encountered by Finnish soldiers during the conflict. Despite this, it's worth noticing that the Finns themselves modified the fixed optics on the rifle to operate from a range of 200 m to only 150 m. Whenever possible, Finnish soldiers discarded the weapon in favor of rifles acquired on the battlefield, including standard models of captured Soviet-made Mosin–Nagant rifles. The latter had the advantage of using commonly available 7.62×54mmR ammunition. By the outbreak of the Continuation War, the remaining Mod. 1938 7.35 mm rifles were issued to the Finnish Navy, as well as anti-aircraft, coastal defense, and other second-line (home front) troops.
In 1941, the Italian military returned to a long-barrelled infantry rifle once again (slightly shorter than the original M91), the Carcano M91/41. True sniper versions never existed, but in World War I a few rifles were fitted with telescopic lenses and issued for service use (World War II scoped rifles were strictly prototypes).
Several lots of Moschetti M91/38 TS (special troops' carbines) were chambered for the German 8×57mm Mauser sS heavy ball round. This modification entered service in 1943, just before the Italian capitulation. Two small batches of Moschetti M91/38 TS carbines shows barrels marked 1938 and 1941, but they were not used at these times with any Italian forces, and their peculiar serial numbering suggests that these might just be rebored unused surplus barrels that were converted with other ones after 1945. Many 7.92 mm Carcano carbines were apparently exported to Egypt after World War II, where they served as drill and training carbines. Several also bear Israeli armed forces markings. The occasionally used model moniker "Model 1943 (M43)" for these converted 7.92mm rifles is wrong, as they were never so designated by the Italian military.
German forces captured large quantities of Carcanos after Italy's capitulation in September 1943. It was the most commonly issued rifle to the German Volkssturm ("People's Militia") units in late 1944 and 1945.
After World War II, Italy replaced its Carcano rifles first with British Lee–Enfields and then with the US .30 caliber (7.62 mm) M1 Garand semi-automatic rifle, which the Italians labeled the "'Model 1952 (M52)". Finland sold all of its approximately 74,000 remaining 7.35 mm M91/38 Carcano rifles on the surplus market. As a consequence, large quantities of surplus Carcanos were sold in the United States and Canada beginning in the 1950s. In Italy, the Polizia di Stato and the Carabinieri retained the "Moschetto 38" TS, retiring it from service in 1981. Captured 6.5mm Carcano rifles were used by Greek forces post-war, with ammunition supplied by U.S. Western Cartridge Co. Some were also converted to 6.5×54mm Mannlicher–Schönauer, one of the standard cartridges of the Greek military at the time.
During the Libyan Civil War in 2011, many rebels went into battle with their personally-owned weapons, including old bolt-action rifles and shotguns. Of these, Carcano-style rifles and carbines have been the most frequently observed style of bolt-action rifle. They were predominantly used by rebels in the Nafusa Mountains. These old weapons saw combat once again due to the rebels' limited access to modern firearms. Additionally, some Libyan rebels preferred to use their familiar hunting weapons over the more modern, yet unfamiliar, assault rifles available. According to Al-Fitouri Muftah, a member of the rebel military council overseeing the western mountain front, as many as 1 in 10 rebels in the region were armed with World War II-era weapons.
Variants.
All variants used the same Carcano bolt action, fed by an en-bloc clip; the rifles and carbines had different barrel lengths and differences in stocks and sights depending on barrel length. As noted in the introduction, the word "moschetto" means literally "musket" but was used generally by Italian arms makers as a descriptor of Italian 20th century rifles, often shorter-barrelled rifles in the carbine style meant for other than regular infantry uses. Regular length infantry rifles are named as "fucile" models.
Kennedy assassination rifle.
In March 1963, Lee Harvey Oswald purchased a "6.5 [mm] Italian carbine", later improperly called a Mannlicher–Carcano (although it uses a Mannlicher-style en bloc clip system), through mail order, for $19.95 ($155 in 2015 dollars). The advertisement only specified a "6.5 Italian Carbine" and actually shows a Carcano model M91 TS, which was the Carcano carbine model sold through the ad when it was originally placed. However, from a time 11 months before Oswald placed his order, the Chicago sporting goods store from which he purchased it had been shipping the slightly longer Model 91/38 under the same ad, and this is the weapon Oswald received.
Official reports have concluded that Oswald used this weapon to assassinate U.S. President John F. Kennedy on 22 November 1963. The rifle, made in the Terni arsenal in 1940 and bearing the serial number C2766, was equipped for an extra $7 with a new 4x18 Japanese telescopic sight, on a sheet metal side mount. It was later scrutinized by local police, the FBI, the U. S. Army and two federal commissions. Shooting tests, conducted by those groups and others using the original rifle or similar models, addressed questions about the speed and accuracy with which the Carcano could be fired. Following lawsuits over its ownership, the rifle ended up in storage at the National Archives. The assassination was one of the factors leading to passage of the Gun Control Act of 1968, which banned mail order sales of firearms.