Shear flow

The term shear flow is used in solid mechanics as well as in fluid dynamics. The expression "shear flow" is used to indicate:
In solid mechanics.
For thin-walled profiles, such as that through a beam or semi-monocoque structure, the shear stress distribution through the thickness can be neglected. Furthermore, there is no shear stress in the direction normal to the wall, only parallel. In these instances, it can be useful to express internal shear stress as shear flow, which is found as the shear stress multiplied by the thickness of the section. An equivalent definition for shear flow is the shear force "V" per unit length of the perimeter around a thin-walled section. Shear flow has the dimensions of force per unit of length. This corresponds to units of newtons per meter in the SI system and pound-force per foot in the US.
Origin.
When a transverse force is applied to a beam, the result is variation in bending normal stresses along the length of the beam. This variation causes a horizontal shear stress within the beam that varies with distance from the neutral axis in the beam. The concept of complementary shear then dictates that a shear stress also exists across the cross section of the beam, in the direction of the original transverse force. As described above, in thin-walled structures, the variation along the thickness of the member can be neglected, so the shear stress across the cross section of a beam that is composed of thin-walled elements can be examined as shear flow, or the shear stress multiplied by the thickness of the element.
Applications.
The concept of shear flow is particularly useful when analyzing semi-monocoque structures, which can be idealized using the skin-stringer model. In this model, the longitudinal members, or stringers, carry only axial stress, while the skin or web resists the externally applied torsion and shear force. In this case, since the skin is a thin-walled structure, the internal shear stresses in the skin can be represented as shear flow. In design, the shear flow is sometimes known before the skin thickness is determined, in which case the skin thickness can simply be sized according to allowable shear stress.
Shear center.
For a given structure, the shear center is the point in space at which shear force could be applied without causing torsional deformation (e.g. twisting) of the cross-section of the structure. The shear center is an imaginary point, but does not vary with the magnitude of the shear force - only the cross-section of the structure. The shear center always lies along the axis of symmetry, and can be found using the following method:
Calculating shear flow.
By definition, shear flow through a cross section of thickness t is calculated using formula_1, where formula_2. Thus the equation for shear flow at a particular depth in a particular cross-section of a thin-walled structure that is symmetric across its width is
where
In fluid mechanics.
In fluid mechanics, the term "shear flow" (or "shearing flow") refers to a type of fluid flow which is caused by forces, rather than to the forces themselves. In a shearing flow, adjacent layers of fluid move parallel to each other with different speeds. Viscous fluids resist this shearing motion. For a Newtonian fluid, the stress exerted by the fluid in resistance to the shear is proportional to the strain rate or shear rate.
A simple example of a shear flow is Couette flow, in which a fluid is trapped between two large parallel plates, and one plate is moved with some relative velocity to the other. Here, the strain rate is simply the relative velocity divided by the distance between the plates.
Shear flows in fluids tend to be unstable at high Reynolds numbers, when fluid viscosity is not strong enough to dampen out perturbations to the flow. For example, when two layers of fluid shear against each other with relative velocity, the Kelvin–Helmholtz instability may occur.


Mars Surface Exploration

Mars Surface Exploration (MSE) is a systems engineering tool for the design of rover missions originally developed in 2003 by the Space Systems Engineering graduate class at MIT. It has since been further enhanced by the MIT Space Systems Laboratory with the support of the Jet Propulsion Laboratory (JPL). The tool is intended to help designers during pre-phase A rover mission design. MSE enables designers to model and analyze very rapidly a wide range of design options for a mission whose science goals have been defined. The emphasis is on breadth rather than on in-depth modeling of specific designs. Other rover modeling tools exist at NASA’s and ESA’s concurrent engineering facilities that take the approach of interconnecting sophisticated software design environments to conduct detailed analyses of a particular mission. MSE's approach complements in-depth modeling techniques which, in return, assist in the validation of MSE's models at various points of the design space.
Analyses.
MSE has been used to analyze various types of missions ranging from traditional rover missions (e.g. Mars Science Laboratory and ExoMars ) to Mars Sample Return-type missions and Lunar missions.


Hamburger button

The hamburger button, so named for its unintentional resemblance to a hamburger, is a button typically placed in a top corner of a graphical user interface. Its function is to toggle a menu (sometimes referred to as a hamburger menu) or navigation bar between being collapsed behind the button or displayed on the screen. The icon which is associated with this widget, consisting of three horizontal bars, is also known as the "collapsed menu icon".
History.
Original design.
The icon was originally designed by Norm Cox as part of the user interface for the Xerox Star, introduced in 1981; it saw a resurgence starting in 2009 stemming from the limited screen area available to mobile apps. Cox described the icon's creation, saying “Its graphic design was meant to be very “road sign” simple, functionally memorable, and mimic the look of the resulting displayed menu list. With so few pixels to work with, it had to be very distinct, yet simple. I think we only had 16×16 pixels to render the image. (or possibly 13×13... can't remember exactly).”
In mainstream computing.
In possibly its first use after the Xerox Star, the release of Windows 1.0 in 1985 contained a hamburger icon in each window's control menu. It was short-lived, however, as the hamburger icon disappeared in Windows 2.0 in favor of a single horizontal line denoting the control menu. Windows 95 replaced the single line with the program's icon, and the hamburger would not return to Windows until a placement on the Start menu of the one-year update of Windows 10.
Appearance and functionality.
The "menu" button takes the form of an icon that consists of three parallel horizontal lines (displayed as ≡), suggestive of a list. The name refers to its resemblance to the menu that is typically exposed or opened when interacting with it. The wider button may be reduced to three vertically stacked dots (displayed as a tri-colon or vertical ellipsis ⋮ ), also known as a "kebab icon", "meatball icon" or "falafel icon". In the Microsoft Office 365 platform, a similar application menu consisting of three rows of three squares is displayed. Tapping, clicking or otherwise activating this button results in a menu being revealed, which distinguishes it from a menu or tab bar that is always on display.
Reception.
Appearance.
It has been argued that while the collapsed menu button is now commonplace, its functionality is not necessarily immediately obvious when first encountered; in particular, older users less familiar with modern iconography may find it confusing.
Usability.
The menu button may increase interaction cost compared to a bottom bar menu, requiring extra clicks to retrieve the same information, albeit with the benefit of less space usage of the screen, in the context of mobile apps. It has also been argued that designers tend to overload these icons with too much hidden information.


Organum (instrument)

An organum is any one of a number of musical instruments which were the forerunners of the organ.
The name comes from the Latin "organum", meaning any tool in general or any musical instrument in particular (or an organ of the body), which in turn came from the Greek "organon", with similar meanings, itself derived from "ergon" and so meaning something by which a task is accomplished. The name "organum" in turn gave rise to the modern everyday term "organ".


Swish cymbal

The swish cymbal and the pang cymbal are exotic ride cymbals originally developed and named as part of the collaboration between Gene Krupa and the Avedis Zildjian Company. The current Zildjian Swish Knocker is a redesign of their original swish, with more rivets, deeper bow and shallower bell, based on a cymbal made famous by Mel Lewis, who coined the name "knocker".
Originally a Zildjian exclusive, both swish and pang cymbals disappeared from their catalog for a time but have reappeared. Other makers have also offered explicit "swish" and "pang" designs from time to time. Typical sizes are 16" to 22" for the swish, and 16" to 20" for the pang.
Both swish and pang have the upturned and flanged edge of a china cymbal, with a very small bell, a thin profile overall with little taper, and a relatively thick rim for their size and weight. Although principally ride cymbals, they can also serve as exotic crash cymbals, particularly in the smaller sizes and at higher volumes. As a ride they can be mounted either bell up, for a trashier tone, or bell down, for a more mellow tone and better access to the ride area; As a crash they tend to be mounted bell down, to give a traditional rim angle.
The swish has a higher tone than the pang and is washier with a less pronounced ping, and this difference is accentuated as the swish is generally sold with rivets as a sizzle cymbal, while the pang is sold without rivets. However some drummers remove the rivets from a swish, or add them to a pang, to create intermediate sounds.
Swish and pang cymbals are sometimes considered types of china cymbal, towards the mellow end of the spectrum, and cymbals that are swishes and pangs in all but name have also been offered as china types by both Zildjian and other makers. Ufip produces a "swish china" in 16", 18", 20" and 22" models.


Rope lock

In a theater fly system, a rope lock is a device used to prevent a rope, and the line set it controls, from moving. A rope lock is controlled by a steel handle that engages the lock when vertical and releases it when horizontal. The handle is typically red powder coated or covered by a red rubber grip. A steel, oval-shaped safety ring encircles both the rope and the handle to ensure that the lock cannot be accidentally released. Rope locks are mounted to a locking rail, which provides structural support and holds them at a convenient level for the stage crew.
Locking mechanism.
Two metal cams, one stationary and one movable, are used to immobilize the rope. The position of the movable cam is controlled by the locking handle. When the handle is raised, the movable cam is pressed towards the stationary cam so as to grip the rope by compressing it between the cams. Conversely, the lock is released by lowering the handle, thus retracting the movable cam away from the stationary cam and releasing the grip on the rope. The position of the stationary cam can usually be adjusted with a socket head adjustment screw. This enables the spacing between the cams to be adjusted so that, when locked, the rope lock can accommodate ropes of different diameters.
Simple rope locks are designed to immobilize only balanced or slightly unbalanced loads; they will not hold significantly unbalanced line sets in place nor are they intended to be used for line set speed control. Most traditional rope locks are rated to hold a difference of or less. For this reason, proper loading technique is essential for safe operation. Misuse of the rope lock is a common source of rigging accidents, especially among students. More complex rope locks are available which will prevent unlocking if the line set is excessively unbalanced. These load-sensing locks reduce the probability of accidents, but may cause inconvenient loading situations and are more expensive than simpler locks. Rope locks are also available which are designed to hold unbalanced line-sets and act effectively as a brake.
Many rope locks provide a hole that will accommodate a padlock. When a padlock is installed, the control lever is locked in the vertical orientation and the line set cannot be moved. A rope lock is typically padlocked to prevent accidental movement of the set.


Structural analog (electronic)

Despite the field diversity, all "structural analog" analysis use some level of abstraction to transform models in mathematical graphs, and detected structural analogies by algorithms. Example: for molecular structure comparison and classification operations, the compared compounds are modeled as a mathematical graph.
Analogical models are used in a method of representing a ‘target system’ by another, more understandable or analysable system.
Two systems have analog structures (see illustration) if they are isomorphic graphs and have equivalent (mapped) lumped elements. In electronics, methods based on fault models of structural analogs gain some acceptance in industry.


Musical Box Society International

The Music Box Society International (MBSI) is a non-profit organization dedicated to the enjoyment, study and preservation of all automatic musical instruments. Founded in 1949, MBSI now numbers several thousand members with representation in 50 US states and nineteen other countries. It focuses on music boxes of all sizes, from small, hand-held wind-up boxes, to fairground organs or room sized orchestrions, including musical clocks and snuff boxes, singing bird boxes, player pianos (reproducing pianos, nickelodeons), and automatic musical instruments of any kind.


Coulometry

Coulometry determines the amount of matter transformed during an electrolysis reaction by measuring the amount of electricity (in coulombs) consumed or produced. It can be used for precision measurements of charge, and the amperes even used to have a coulometric definition. However, today coulometry is mainly used for analytical applications. Coulometry is a group of techniques in analytical chemistry. It is named after Charles-Augustin de Coulomb.
There are two basic categories of coulometric techniques. "Potentiostatic coulometry" involves holding the electric potential constant during the reaction using a potentiostat. The other, called "coulometric titration" or "amperostatic coulometry", keeps the current (measured in amperes) constant using an amperostat.
Potentiostatic coulometry.
Potentiostatic coulometry is a technique most commonly referred to as "bulk electrolysis". The working electrode is kept at a constant potential and the current that flows through the circuit is measured. This constant potential is applied long enough to fully reduce or oxidize all of the electroactive species in a given solution. As the electroactive molecules are consumed, the current also decreases, approaching zero when the conversion is complete. The sample mass, molecular mass, number of electrons in the electrode reaction, and number of electrons passed during the experiment are all related by Faraday's laws. It follows that, if three of the values are known, then the fourth can be calculated.
Bulk electrolysis is often used to unambiguously assign the number of electrons consumed in a reaction observed through voltammetry. It also has the added benefit of producing a solution of a species (oxidation state) which may not be accessible through chemical routes. This species can then be isolated or further characterized while in solution.
The rate of such reactions is not determined by the concentration of the solution, but rather the mass transfer of the electroactive species in the solution to the electrode surface. Rates will increase when the volume of the solution is decreased, the solution is stirred more rapidly, or the area of the working electrode is increased. Since mass transfer is so important the solution is stirred during a bulk electrolysis. However, this technique is generally not considered a hydrodynamic technique, since a laminar flow of solution against the electrode is neither the objective nor outcome of the stirring.
The extent to which a reaction goes to completion is also related to how much greater the applied potential is than the reduction potential of interest. In the case where multiple reduction potentials are of interest, it is often difficult to set an electrolysis potential a "safe" distance (such as 200 mV) past a redox event. The result is incomplete conversion of the substrate, or else conversion of some of the substrate to the more reduced form. This factor must be considered when analyzing the current passed and when attempting to do further analysis/isolation/experiments with the substrate solution.
An advantage to this kind of analysis over electrogravimetry is that it does not require that the product of the reaction be weighed. This is useful for reactions where the product does not deposit as a solid, such as the determination of the amount of arsenic in a sample from the electrolysis of arsenous acid (H3AsO3) to arsenic acid (H3AsO4).
Coulometric titration.
Coulometric titrations use a constant current system to accurately quantify the concentration of a species. In this experiment, the applied current is equivalent to a titrant. Current is applied to the unknown solution until all of the unknown species is either oxidized or reduced to a new state, at which point the potential of the working electrode shifts dramatically. This potential shift indicates the endpoint. The magnitude of the current (in amperes) and the duration of the current (seconds) can be used to determine the moles of the unknown species in solution. When the volume of the solution is known, then the molarity of the unknown species can be determined.
Advantages of Coulometric Titration
Coulometric titration has the advantage that constant current sources for the generation of titrants are relatively easy to make.
Applications.
Karl Fischer reaction.
The Karl Fischer reaction uses a coulometric titration to determine the amount of water in a sample. It can determine concentrations of water on the order of milligrams per liter. It is used to find the amount of water in substances such as butter, sugar, cheese, paper, and petroleum.
The reaction involves converting solid iodine into hydrogen iodide in the presence of sulfur dioxide and water. Methanol is most often used as the solvent, but ethylene glycol and diethylene glycol also work. Pyridine is often used to prevent the buildup of sulfuric acid, although the use of imidazole and diethanolamine for this role are becoming more common. All reagents must be anhydrous for the analysis to be quantitative. The balanced chemical equation, using methanol and pyridine, is:
In this reaction, a single molecule of water reacts with a molecule of iodine. Since this technique is used to determine the water content of samples, atmospheric humidity could alter the results. Therefore, the system is usually isolated with drying tubes or placed in an inert gas container. In addition, the solvent will undoubtedly have some water in it so the solvent’s water content must be measured to compensate for this inaccuracy.
To determine the amount of water in the sample, analysis must first be performed using either back or direct titration. In the direct method, just enough of the reagents will be added to completely use up all of the water. At this point in the titration, the current approaches zero. It is then possible to relate the amount of reagents used to the amount of water in the system via stoichiometry. The back-titration method is similar, but involves the addition of an excess of the reagent. This excess is then consumed by adding a known amount of a standard solution with known water content. The result reflects the water content of the sample and the standard solution. Since the amount of water in the standard solution is known, the difference reflects the water content of the sample.
Determination of film thickness.
Coulometry can be used in the determination of the thickness of metallic coatings. This is performed by measuring the quantity of electricity needed to dissolve a well-defined area of the coating. The film thickness formula_2 is proportional to the constant current formula_3, the molecular weight formula_4 of the metal, the density formula_5 of the metal, and the surface area formula_6:
formula_7
The electrodes for this reaction are often platinum electrode and an electrode that relates to the reaction. For tin coating on a copper wire, a tin electrode is used, while a sodium chloride-zinc sulfate electrode would be used to determine the zinc film on a piece of steel. Special cells have been created to adhere to the surface of the metal to measure its thickness. These are basically columns with the internal electrodes with magnets or weights to attach to the surface. The results obtained by this coulometric method are similar to those achieved by other chemical and metallurgic techniques.
Coulometers.
Electronic coulometer.
The electronic coulometer is based on the application of the operational amplifier in the "integrator"-type circuit. The current passed through the resistor R1 makes a potential drop which is integrated by operational amplifier on the capacitor plates; the higher current, the larger the potential drop. The current need not be constant. In such scheme "V"out is proportional of the passed charge. Sensitivity of the coulometer can be changed by choosing of the appropriate value of "R"1.
Electrochemical coulometers.
There are three common types of coulometers based on electrochemical processes:
"Voltameter" is a synonym for "coulometer".


Kirsch equations

The Kirsch equations describe the elastic stresses around the hole in an infinite plate in one directional tension. They are named after Ernst Gustav Kirsch.
Result.
Loading an infinite plate with circular hole of radius "a" with stress "σ", the resulting stress field is:
formula_1
formula_2
formula_3


Yaakov Bar-Shalom

Yaakov Bar-Shalom (May 11, 1941) is a Tracking/Sensor Fusion researcher. His work is associated with MS-MTT (Multi-Sensor, Multi-Target Tracking) and IMM (interacting-multiple-model) estimator.
Early life and education.
Yaakov Bar-Shalom was born in Romania and he emigrated to Israel with his family at the age of nineteen. He earned his Bachelor's and Master's degree both in Electrical Engineering from Technion in Haifa, Israel. Following this, he earned his Ph.D. from Princeton University.
Professional career.
Currently, Yaakov Bar-Shalom is Board of Trustees Distinguished Professor of Electrical & Computer Engineering and the Marianne E. Klewin Professor in Engineering in University of Connecticut. He is the recipient of the 2012 Connecticut Medal of Technology for his work in improving the sensitivity of remote sensors used for surveillance in the presence of background noise or clutter.
Anthony J. DeMaria, recipient of the 2004 Connecticut Medal of Technology and Chief Scientist at Coherent-DEOS, LLC, has stated that Yaakov Bar-Shalom is regarded as the "chief architect of probability-based methods for estimating the paths of moving objects."
Bar-Shalom's research mainly focuses on Target Tracking Systems: Information extraction and fusion from remote sensors (radar, sonar, electrooptical) for tracking cooperative or non-cooperative targets by estimating their trajectories in the presence of disturbances like measurement errors, target maneuvers and interfering signals (false measurements or from detection from other targets). Bar-Shalom has so far published more than 550 papers, 8 books, 20 book chapters and has over 35,000 citations. Under his supervision, 38 Ph.D. have graduated in his 42 years career as a professor.
Awards and honors.
Bar-Shalom is recipient of IEEE Control Systems Society Distinguished Member Award (1987); UConn AAUP Award for Excellence in Research (1988); J. Mignona Data Fusion Award from the DoD JDL Data Fusion Group (2002); IEEE Dennis J. Picard Medal for Radar Technologies and Applications (2008); Connecticut Medal of Technology (2012).
He has been listed by Microsoft Academic Search (top authors in engineering) as #1 among the researchers in Aerospace Engineering based on the citations of his work (2012-2016).
Bar-Shalom is also the recipient of the 2015 ISIF Award for a Lifetime of Excellence in Information Fusion. This award has been renamed in 2016 as the Yaakov Bar-Shalom Award for a Lifetime of Excellence in Information Fusion.


Letitia Chitty

Letitia Chitty (15 July 1897 – 29 September 1982) was an English engineer who became a respected structural analytical engineer, achieving several firsts for women engineers, including becoming the first female fellow of the Royal Aeronautical Society and the first female recipient of the Telford Medal.
Early life.
Born at 51 Campden House Road, Kensington, London, she was the eldest of four sisters and one brother. Her father Herbert Chitty (1863–1949) was a barrister and (from 1907) bursar of Winchester College. Her mother was Mabel Agatha, "née" Bradby (1865–1944). Her paternal grandfather was the judge Sir Joseph William Chitty and her maternal grandfather was Canon Edward Henry Bradby, the headmaster of Haileybury College. Her Bradby relatives included uncle G. F. Bradby, author of "The Lanchester Tradition" (1919), and aunt Barbara Bradby joint author of "The Village Labourer" (1911). Cousins included the poet Anne Ridler.
Education.
Chitty was privately educated between 1903 and 1916, latterly at Kensington High School. She entered Newnham College, Cambridge in 1916, taking the first part of the Tripos. During World War I, as part of a British programme to identify the best female mathematics graduates and current students, she was selected for war work with Alfred Pippard at the Admiralty Air Department at age 19. After the war she returned to her studies, changed subject to engineering, and graduated with a titular degree from Newnham College with first class honours in the Mechanical Sciences Tripos, 1921, the first woman to do so.
Early career.
Her early career focused on analysing the stresses of airframes, airships and civil engineering structures, initially with the Admiralty Air Department and then, after graduating, at the Air Ministry with Richard Southwell and Alfred Pippard.
Work with Tarrant Tabor.
W. G. Tarrant, previously a timber merchant, designed a massive bomber at the end of World War I, the Tarrant Tabor. The original biplane design had to be altered to triplane to accommodate more engines, and the Admiralty Air Department was asked to check its structural strength. Chitty was given this task.
In her own words:
"Mr. Tarrant was an inspired timber merchant who dreamed of a super-Camel. It hadn't a chance. It was too big, too heavy - that wasn't its fault, but Grade A spruce had by now run out and it had to be built of American white wood (tulip). In my language, 3,500 instead of 5,500 lb/sq in."
Tragically, her mathematical analysis was not heeded. The plane crashed nose down during its first take-off, from the Royal Aircraft Establishment at Farnborough on 26 May 1919, killing both pilots and seriously injuring the other six people on board.
Later career.
Chitty moved to Imperial College in 1934 where she remained for the rest of her career, initially specialising in structural stresses in aircraft. During the 1930s, she was part of a group which analysed the crash of the airship R38, and published various Air Ministry papers on stresses and strains on airship structures. She was an early member of the Women's Engineering Society.
Her World War II work included research into stresses in submarine hulls under shell attack, extensible cables and pulley blocks for barrage balloons, for the Director of Scientific Research of the Admiralty and the Ministry of Supply. Later research interests included arches and arch dams - in particular, the Dukan Dam in Iraq - and she contributed to an international symposium on arched dams in 1968.
Initially an Imperial College research assistant, Chitty became a lecturer in 1937, and retired in 1962. She was the first female Fellow of the Royal Aeronautical Society (FRAeS), the third female Corporate Member of the Institution of Civil Engineers and the first woman to be appointed to an ICE technical committee, in 1958. She was awarded four Telford Premium medals for papers written with Pippard, and in 1969 became the first woman to receive the Telford Gold Medal.
She travelled widely and published a book, "Abroad. An alphabet of Flowers", in 1948, with her own drawings and notes about her holidays.
In her will, she left a bequest to Imperial College, which named its Library reading room after her. Imperial College also presents a Letitia Chitty Centenary Memorial Prize, while Newnham College has presented a 'Letitia Chitty Award for Engineering'.


M39 lens mount

The M39 lens mount is a screw thread mounting system for attaching lenses to 35 mm cameras, primarily rangefinder (RF) Leicas. It is also the most common mount for Photographic enlarger lenses.
True Leica Thread-Mount (LTM) is 39 mm in diameter and has a thread of 26 turns-per-inch or threads-per-inch (tpi) (approximately 0.977 mm pitch) of Whitworth thread form. Whitworth threads were then the norm in microscope manufacture. The Royal Microscopical Society (RMS) thread, also known as "society thread", is a special 0.8" diameter x 36 tpi Whitworth thread used for microscope objective lenses and Leitz was a major manufacturer of microscopes, so the tooling at the plant was already set up to produce the Whitworth thread form. The Soviets in the 1930s produced their early FED cameras in M39×1 (39 mm by 1 mm DIN thread). Early Canon cameras also used a different M39 × 24 tpi thread mount, called "J-mount".
True LTM lenses have a flange focal distance of 28.8 mm, though this is of little importance for lenses used on bellows enlargers.
The Soviets later adopted the LTM mount for their Zenit single-lens-reflex (SLR) cameras, though with the longer optical registration of 45.2 mm, required to allow the mirror room to flip out of the focal path when a picture was taken.
The mount was developed by Oskar Barnack at Leica to provide a system that would allow for the exchange of lenses on their new small film cameras (Leica Type 1 and Leica Type 2), as Zeiss Ikon had indicated that their forthcoming Contax rangefinder cameras would have interchangeable lenses. The LTM system was tested at the request of Leitz on lenses manufactured in small batches by Hugo Meyer in Germany and marketed with a run of Leitz cameras by A. O. Roth in London. The test marketing program was a success, so regular production with Leitz camera bodies and lenses was introduced on the Leica II, and featured on the Leica Standard and Leica III.
Until the 1970s the 39 mm mount was the norm for exchangeable lenses in rangefinder cameras. The high cost of quality lenses led to the dual use camera/enlarger of the lenses, hence the fact that enlargers also accept 39 mm lenses.
Currently, Cosina in Japan — many of whose recent products are marketed under the Voigtländer brand — and FED in Ukraine continue to produce camera bodies using a true Leica thread-mount. These give amateurs the rare chance of having a very professional camera by combining a used Leica lens with an M39 body at a price well below a real Leica combination. On the other hand, one has to be careful as there are some issues with some bodies not using the same focusing system. Adaptors are available to use M39 lenses with modern digital cameras, such as the Canon EF-M and Sony E mounts.


Reverse DDM

Dynamic device mapping is a technology for USB KVM switches which is sometimes implemented as an alternative to standard USB keyboard and mouse emulation. Reverse DDM (short for Dynamic Device Mapping), on the other hand, is a related technology that allows further flexibility in regard to specific USB ports.
Design.
With DDM (Dynamic Device Mapping) Technology, the communication between shared peripherals and all connected systems are maintained 100% of the time, even as a user switches between the KVM ports. This makes generic device emulation unnecessary as the DDM allows each connected computer system to believe all connected I/O devices are remaining connected even as the KVM switch might move to another port.
With Reverse DDM, an administrator can provide port level management control. Individual USB ports can be limited, configured, or assigned to specific kinds of devices. This adds a level of security in certain environments that require no USB thumb drives to be used, or printers connected, etc.


Music roll

A music roll is a storage medium used to operate a mechanical musical instrument. They are used for the player piano, mechanical organ, electronic carillon and various types of orchestrion. The vast majority of music rolls are made of paper. Other materials that have been utilized include thin card (Imhof-system), thin sheet brass (Telektra-system), composite multi-layered electro-conductive aluminium and paper roll (Triste-system) and, in the modern era, thin plastic or PET film.
The music data is stored by means of perforations. The mechanism of the instrument reads these as the roll unwinds, using a pneumatic, mechanical or electrical sensing device called a tracker bar, and the mechanism subsequently plays the instrument.
After a roll is played, it is necessary for it to be rewound before it can be played again. This necessitates a break in a musical performance. To overcome this problem, some instruments were built with two player mechanisms (referred to as a duplex roll mechanism) allowing one roll to play while the other rewinds.
A piano roll is a specific type of music roll, and is designed to operate an automatic piano like the player piano or the reproducing piano.


Lathe dog

A lathe dog is a dog designed to be clamped on a work piece to allow it to be revolved by a lathe face-plate. Lathe dogs are generally provided in straight-tailed or bent-tailed form. Bent-tailed dogs are able to engage directly with a face-plate slot or a chuck jaw but can crowd work off centre. Straight-tailed dogs do not present the issue of crowding work off centre but require a driving stud to be mounted on the face-plate.
A carrier is most often used when "turning" between centers on a lathe, but it may be used on dividing heads or any similar situation. It is used in conjunction with a drive plate and drive pins: the plate is mounted directly on the machine spindle (as with a chuck) and the drive pin is attached to the plate. In use the carrier and workpiece are inserted between centers and the leg of the carrier rests against the drive pin.
Spindle speeds are reduced when working with carriers, due to the unbalanced nature of the setup. Care must also be taken by the operator when using carriers, as it is easy to get snagged on one.


MSP Groza silent pistol

The MSP Groza ("thunderstorm") silent pistol is a double-barrel, derringer-type firearm designed in the Soviet Union in 1972. The firearm is chambered for the silent 7.62×38 SP-3 cartridge which is fed via a two-round clip. The weapon was designed at the request of the special service. It is no longer in production, having been superseded by more modern designs.
The weapon was used operationally in Afghanistan and in Central America during the Cold War.
Design.
The Groza uses a specialised cartridge. When fired, an internal piston within the cartridge launches the bullet forward and retains all the gases within the case, thus making a near silent weapon with almost no flash.


Heavy Aircraft Test Squadron


Henry Paynter

Henry M. Paynter (August 11, 1923 – June 14, 2002) was an American scientist, best known as the inventor of bond graphs.
Bond graphs.
Bond graphs are a unique way of describing dynamic models, designed to model the interaction between different kinds of physical systems, like electrical, mechanical, hydraulical and chemical. This is possible because one thing all these components have in common is power. Power can flow from one component to another and bond graphs are designed to keep track of these flows in an easy way .
Bond graphs were invented on April 24, 1959:
He published on a wide variety of subjects in more than 100 papers, patents, articles, and book chapters, as well as several books. The Bond graph modelling approach was presented for the first time in the "Ports, Energy and Thermodynamic Systems" on April 24, 1959 at MIT, which was later published (Paynter, 1961). Paynter was elected to the National Academy of Engineering in 1997, one of the highest professional distinctions accorded to an engineer.
Academic career.
Paynter received the B.S. in civil engineering in 1944, the M.S. in mathematics and science in 1949, and the first Sc.D. ever awarded in hydroelectric engineering in 1951, all from MIT. Paynter joined the Department of Civil Engineering in 1946 and became an assistant professor in 1951. He was regarded as a creative, charismatic, and passionate teacher who deeply influenced the careers of his students. He urged them to think "big" and "deep" about engineering and science. He joined the Department of Mechanical Engineering in 1954 on a half-time basis to initiate a Systems Engineering curriculum. He became full time in mechanical engineering in 1959 and was promoted to associate professor the following year. He became a full professor in 1964. After he retired, Paynter was a senior lecturer in mechanical engineering.
In his work, he became one of the world's leading experts in analog computing. His work was closely associated with George Philbrick, who is credited along with Lovell as the developer of the operational amplifier. Paynter's earliest research lead to the formation of the Pi-Square Engineering Company. This company applied fast electronic analog computing to industrial process control. Paynter also collaborated closely with the Woodward Governor Company on hydro plant control.
Personal life.
Henry Martyn Paynter IV was born in Evanston, Illinois and grew up in New York City and its environs. He was married to Gayllis Anne Beasley and fathered six children.


General Computer Corporation

General Computer Corporation (GCC) is an American printer company formed in 1981 by Doug Macrae, John Tylko, and Kevin Curran. The company began as a video game company and then later changed to make computer peripherals.
History.
Video games.
They started out making mod-kits for existing arcade games - for example "Super Missile Attack", which was sold as an enhancement board to Atari's "Missile Command". At first Atari sued, but ultimately dropped the suit and hired GCC to develop games for Atari (and stop making enhancement boards for Atari's games without permission). They created an enhancement kit for "Pac-Man" called "Crazy Otto" which they sold to Midway, who in turn sold it as the sequel "Ms. Pac-Man"; they also developed "Jr. Pac-Man", that game's successor.
Under Atari, Inc., GCC made the original arcade games "Food Fight", "Quantum", and the unreleased "Nightmare"; developed the Atari 2600 versions of "Ms. Pac-Man" and "Centipede"; produced over half of the Atari 5200 cartridges; and developed the chip design for the Atari 7800, plus the first round of cartridges for that base unit.
Peripherals.
In 1984, the company changed direction to make peripherals for Macintosh computers: the HyperDrive (the Mac's first internal hard drive), the WideWriter 360 large format inkjet printer, and the Personal Laser Printer (the first QuickDraw laser printer). Presently the company focuses exclusively on laser printers.
HyperDrive was unusual because the original Macintosh did not have any internal interface for hard disks. It was attached directly to the CPU, and ran about seven times faster than Apple's "Hard Disk 20", an external hard disk that attached to the floppy disk port.
The HyperDrive was considered an elite upgrade at the time, though it was hobbled by Apple's Macintosh File System, which had been designed to manage 400K floppy disks; as with other early Macintosh hard disks, the user had to segment the drive such that it appeared to be two or more partitions, called Drawers.
The second issue of MacTech Magazine, in January 1985, included a letter that summed up the excitement:
In 1986 the company shipped the "HyperDrive 2000", a 20MB internal hard disk that also included a Motorola 68881 floating-point unit, but the speed advantage of the HyperDrive had been negated on the new Macintosh Plus computers by Apple's inclusion of an external SCSI port. General Computer responded with the "HyperDrive FX-20" external SCSI hard disk, but drowned in a sea of competitors that offered fast large hard disks.
Today, General Computer, currently located in Burlington, Massachusetts, sells laser printers.


Bachi

Bachi (桴, 枹) (also "batchi") are straight, wooden sticks used on Japanese taiko drums, and also (written 撥) the plectrum for stringed instruments of Japanese origin such as the "shamisen" and "biwa".
For percussion (桴/枹).
Drum bachi are made in a wide variety of sizes and materials, as appropriate to the drum it will be used to play. A typical bachi is about 22 mm (7/8 inches) in diameter, 400 mm (16 inches) long and made out of a hardwood such as oak. These would be suitable for a wide variety of playing styles.
A bachi for playing a larger drum like the O-daiko would be bigger both in circumference and length. Similarly, smaller bachi are used for smaller drums.
Distinctions between the characters 桴 and 枹 are not always made in technical terms, but 枹 can also literally refer to the white oak tree, or Quercus. Some other woods commonly used to make bachi are (Japanese names in parentheses): maple (楓, "kaede"), pine (松, "matsu"), cypress (檜, "hinoki"), magnolia (朴, "hou/hō"), beech (椈, "buna") and bamboo (竹, "take"). Magnolia is one of the lightest and softest woods, most suitable for playing smaller drums with a sharp attack and less decay. On a larger drum, however, a magnolia bachi usually sounds "slappy" and flat, because it is too light to strike the thicker head of the drum with enough power to generate the lower tones of the drum. It is also too soft to strike the rim of the drum (in kuchi shoka, it is called a "ka") without denting the wood. Cypress is slightly harder than magnolia, and is usually cheaper as well. On the opposite extreme, an evergreen oak (樫, "kashi") bachi is heavy and hard. It brings out a better, fuller sound when playing larger taiko, but it muffles the higher harmonics of smaller taiko, sounding "thunky" and dead.
Taiko drumming is a highly visual art form, and so bachi are sometimes decorated with bells and/or tassels for use during performance.
For stringed instruments (撥).
Bachi used for stringed instruments are actually picks. They are very distinct in form and use from Western-style picks, which are usually smaller in order to be held between or mounted to fingers. In shape, bachi are similar to an ice scraper or a putty knife.
Bachi can be made of various materials and with varying levels of strength. Similarly to guitar picks, bachi were traditionally made of tortoise shell (鼈甲, "bekkou") or ivory (象牙, "zouge"), but these materials are rare and expensive (and illegal to trade in some territories, due to protection of endangered species), therefore making bachi in these materials highly expensive and impractical. Modern, more affordable variants are often made of acrylic, plastic or wood.
Generally, bachi made of softer, more flexible materials are easier to play with for beginners, but harder materials produce a stronger sound and last longer.


William C. Mentzer

William C. Mentzer (May 27, 1907 – December 23, 1971) was an aeronautical engineer noted for his contributions to the airline industry, dealing particularly with aircraft maintenance and economics. He was born on May 27, 1907 in Knoxville, Iowa. After graduating from MIT in 1934, he worked for United Airlines as an engineer. During the course of his career, he was involved in the development of over 50 aircraft and was eventually promoted to a senior management level. He was elected a fellow of the American Institute of Aeronautics and Astronautics and a member of the National Academy of Engineering. He died on December 23, 1971 in Palo Alto, California. He was posthumously awarded the Daniel Guggenheim Medal in 1972.


ONERA

The Office National d'Etudes et de Recherches Aérospatiales (ONERA) is the French national aerospace research centre. It is a public establishment with industrial and commercial operations, and carries out application-oriented research to support enhanced innovation and competitiveness in the aerospace and defense sectors.
ONERA was created in 1946 as "Office National d’Études et de Recherches Aéronautiques". Since 1963, its official name has been "Office National d’Études et de Recherches Aérospatiales". However, in January 2007, ONERA has been dubbed "The French Aerospace Lab" to improve its international visibility.
History.
ONERA's historic roots are in the Paris suburb of Meudon, south of Paris. As early as 1877, this site hosted an aeronautical research center for military aerostats (balloons): Etablissement central de l’aérostation militaire.
ONERA was created in May 1946 to relaunch aeronautics research, an activity that had gone into hibernation during the Second World War and the German occupation. Its creation reflected the government's decision to recover the large wind tunnel in Ötztal, Austria, in the French administrative zone, and move it to France. Today, ONERA's extensive array of wind tunnels is one of its main assets. ONERA operates a world-class fleet of wind tunnels, the largest in Europe. The S1MA wind tunnel at Modane-Avrieux, developing 88 MW of total power, is the world's largest sonic wind tunnel (tests at Mach 0.05 to Mach 1).
Organization.
The Chairman and CEO of ONERA is appointed by the French Council of Ministers, acting on a proposal by the Minister of Defense. Since June 2014, the Chairman and CEO is Bruno Sainjon.
ONERA is organized in eight geographic areas. It has about 2,000 employees, with 1,500 engineers and scientists (including 230 doctoral candidates), as well as support staff.
Three centers in the greater Paris area (Ile-de-France):
Two centers in the Midi-Pyrenees region of southwest France:
Three other centers:
ONERA is organized in four scientific branches: Fluid Mechanics and Energetics; Materials and Structures; Physics; and Information Processing and Systems. Wind tunnel testing is managed in the GMT (Grands Moyens Techniques) department. Aerospace prospective depends on a specific department.
Missions.
Unlike NASA in the United States, ONERA is not an agency for space science and exploration. However, it carries out a wide range of research for space agencies, both CNES in France and the European Space Agency (ESA), as well as for the French defense agency, DGA (Direction générale de l’armement). ONERA also independently conducts its own long-term research to anticipate future technology needs. It focuses on scientific research, for example in aerodynamics for concrete applications on aircraft, the design of launchers and new defense technologies, such as drones or unmanned aerial systems (UAS).
ONERA also uses its research and innovation capabilities to support both French and European industry. ONERA has contributed to a number of landmark aerospace and defense programs in recent decades, including Airbus, Ariane, Rafale, Falcon, Mirage and Concorde.
Commercial partnerships.
ONERA's customer-partners include Airbus (Airbus Helicopters), Safran (Snecma, Turbomeca, Sagem), Dassault Aviation, Thales and other major industry players. Innovative small businesses are also encouraged to call on the expertise of ONERA's scientists and engineers, and to take advantage of technology transfer opportunities. The company Tefal was created by two ONERA engineers, the inventors of the “non-stick pan”. These products were produced and sold by Tefal S.A., which was subsequently acquired by SEB


Leica thread-mount


BACH motif

In music, the BACH motif is the motif, a succession of notes important or characteristic to a piece, "B flat, A, C, B natural". In German musical nomenclature, in which the note "B natural" is named "H" and the "B flat" named "B", it forms Johann Sebastian Bach's family name. One of the most frequently occurring examples of a musical cryptogram, the motif has been used by countless composers, especially after the Bach Revival in the first half of the 19th century.
Origin.
Johann Gottfried Walther's "Musicalisches Lexikon" (1732) contains the only biographical sketch of Johann Sebastian Bach published during the composer's lifetime. There the motif is mentioned thus:This reference work thus indicates Bach as the inventor of the motif.
Usage in compositions.
In a comprehensive study published in the catalogue for the 1985 exhibition "300 Jahre Johann Sebastian Bach" ("300 years of Johann Sebastian Bach") in Stuttgart, Germany, Ulrich Prinz lists 409 works by 330 composers from the 17th to the 20th century using the BACH motif. A similar list is available in Malcolm Boyd's volume on Bach: it also contains some 400 works.
Johann Sebastian Bach.
Johann Sebastian Bach used the motif in a number of works, most famously as a fugue subject in the last "Contrapunctus" of "The Art of Fugue". The motif also appears in other pieces. Later commentators wrote: "The figure occurs so often in Bach's bass lines that it cannot have been accidental."
Instances of B-A-C-H appearing in Johann Sebastian Bach's compositions and arrangements:
Hans Heinrich Eggebrecht goes as far as to reconstruct Bach's putative intentions as an expression of Lutheran thought, imagining Bach to be saying, "I am identified with the tonic and it is my desire to reach it ... Like you I am human. I am in need of salvation; I am certain in the hope of salvation, and have been saved by grace," through his use of the motif rather than a standard changing tone figure (B-A-C-B) in the final measures of the fourth fugue of "The Art of Fugue".
Other composers.
The motif was used as a fugue subject by Bach's son Johann Christian, and by his pupil Johann Ludwig Krebs. It also appears in a work by Georg Philipp Telemann.
The motif's wide popularity came only after the start of the Bach Revival in the first half of the 19th century. A few mid-19th century works that feature the motif prominently are:
Composers found that the motif could be easily incorporated not only into the advanced harmonic writing of the 19th century, but also into the totally chromatic idiom of the Second Viennese School; so it was used by Arnold Schoenberg, Anton Webern, and their disciples and followers. A few 20th-century works that feature the motif prominently are:
In the 21st century, composers continue writing works using the motif, frequently in homage to Johann Sebastian Bach.


Edmund T. Pratt Jr.

Edmund T. Pratt Jr. (1927 - September 5, 2002) was the Chairman and CEO of Pfizer Inc.. He served as President from 1971 to 1972, CEO from 1972 to 1991, and Chairman from 1972 to 1992. He is the namesake of Duke University's Engineering School.
Early life.
Pratt was born in Savannah, Georgia in 1927 and grew up in Elkton, Maryland. His father worked for the Army Corps of Engineers He graduated from Duke University in 1947 "magna cum laude" with a bachelor of science in electrical engineering. He also obtained an MBA from University of Pennsylvania's Wharton School of Business in 1949.
Career.
Pratt began his career at IBM in 1949. His time at IBM was interrupted for two years when he served with the Navy as a lieutenant during the Korean War. Afterwards, he returned to IBM in 1952, eventually serving as controller of IBM World Trade Corporation from 1958 to 1962. Pratt then joined the Kennedy Administration as assistant secretary of the Army for Financial Management.
After leaving the government in 1964, Pratt joined Pfizer as controller. In 1969, he became chairman and president of Pfizer International. In 1971, he was elected president of Pfizer, and in 1972 he succeeded John Powers, Jr. as chairman and CEO.
During Pratt's two decades at the helm, Pfizer evolved into one of the fastest-growing pharmaceutical companies in the United States. Pratt expanded research and development facilities worldwide, acquired Howmedica and other medical device companies, and introduced of products like Procardia, Feldene, Diflucan, and Norvasc. Under his leadership, annual revenue increased sevenfold, from $1 billion to nearly $7 billion.
Pratt's earlier government service in Washington stood him in good stead as the Company grew and played a greater role in national and international matters. As advisor to United States Trade Representative Bill Brock in the mid-1980s, he played an instrumental role encouraging private sector involvement in trade matters. As chairman of the presidentially appointed Advisory Committee for Trade Negotiations, he also broadened the trade agenda to include items of global impact, including the issue of intellectual property as a result of Pfizer's diminishing returns. In his own words "We were beginning to notice that we were losing market share [in developing countries] because our intellectual property rights were not being respected in these countries" A member of the IPC trade delegation in the Punta del Este round of the GATT trade talks in 1986, he pushed hard for the creation of a commercially beneficial system of worldwide IP rights.
Pratt served as chairman of the Business Council of New York State, The Business Round Table, and the President's Advisory Committee for Trade Negotiations. On March 1, 1992 Pratt retired as chairman and continued his involvement with the Company as a director of the board until 1997.
During his tenure as head of Pfizer, Ed Pratt was instrumental in the creation of low-income housing around Pfizer's Brooklyn plant, the donation of a Pfizer building for a public charter school, and the economic development and improvements in neighborhood safety. He also held leadership positions in organizations such as the United Way, the Boys Clubs of America, and the Girl Scouts of the USA. He made significant contributions to Long Island University, in 1998, to fund academic, computer, and library facilities and, in 1999, to Duke University which created the Pratt School of Engineering.
Personal.
Pratt was inducted into the Junior Achievement U.S. Business Hall of Fame in 1999. In 1987, he received The Hundred Year Association of New York's Gold Medal Award "in recognition of outstanding contributions to the City of New York."
A magna cum laude graduate of Duke - who relied on a U.S. Navy scholarship to fund his education - Pratt donated $35 million to the university in 1999.
Pratt died of cancer on September 5, 2002 at the age of 75.
He was married to Nancy Rhodes Pratt and had two sons, Randolph and Keith.


Automotive electronics

Automotive electronics are electronic systems used in vehicles, including engine management, ignition, radio, carputers, telematics, in-car entertainment systems, and others. Ignition, engine and transmission electronics are also found in trucks, motorcycles, off-road vehicles, and other internal combustion powered machinery such as forklifts, tractors and excavators. Related elements for control of relevant electrical systems are also found on hybrid vehicles and electric cars.
Electronic systems have become an increasingly large component of the cost of an automobile, from only around 1% of its value in 1950 to around 30% in 2010. Modern electric cars rely on power electronics for the main propulsion motor control, as well as managing the battery system. Future autonomous cars will rely on powerful computer systems, an array of sensors, networking, and satellite navigation, all of which will require electronics.
History.
The earliest electronic systems available as factory installations were vacuum tube car radios, starting in the early 1930s. The development of semiconductors after World War II greatly expanded the use of electronics in automobiles, with solid-state diodes making the automotive alternator the standard after about 1960, and the first transistorized ignition systems appearing about 1955.
The emergence of metal–oxide–semiconductor (MOS) technology led to the development of modern automotive electronics. The MOSFET (MOS field-effect transistor, or MOS transistor), invented by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959, led to the development of the power MOSFET by Hitachi in 1969, and the single-chip microprocessor by Federico Faggin, Marcian Hoff, Masatoshi Shima and Stanley Mazor at Intel in 1971.
The development of MOS integrated circuit (MOS IC) chips and microprocessors made a range of automotive applications economically feasible in the 1970s. In 1971, Fairchild Semiconductor and RCA Laboratories proposed the use of MOS large-scale integration (LSI) chips for a wide range of automotive electronic applications, including a transmission control unit (TCU), adaptive cruise control (ACC), alternators, automatic headlight dimmers, electric fuel pumps, electronic fuel-injection, electronic ignition control, electronic tachometers, sequential turn signals, speed indicators, tire-pressure monitors, voltage regulators, windshield wiper control, Electronic Skid Prevention (ESP), and heating, ventilation, and air conditioning (HAVC).
In the early 1970s, the Japanese electronics industry began producing integrated circuits and microcontrollers for the Japanese automobile industry, used for in-car entertainment, automatic wipers, electronic locks, dashboard, and engine control. The Ford EEC (Electronic Engine Control) system, which utilized the Toshiba TLCS-12 PMOS microprocessor, went into mass production in 1975. In 1978, the Cadillac Seville featured a "trip computer" based on a 6802 microprocessor. Electronically-controlled ignition and fuel injection systems allowed automotive designers to achieve vehicles meeting requirements for fuel economy and lower emissions, while still maintaining high levels of performance and convenience for drivers. Today's automobiles contain a dozen or more processors, in functions such as engine management, transmission control, climate control, antilock braking, passive safety systems, navigation, and other functions.
The power MOSFET and the microcontroller, a type of single-chip microprocessor, led to significant advances in electric vehicle technology. MOSFET power converters allowed operation at much higher switching frequencies, made it easier to drive, reduced power losses, and significantly reduced prices, while single-chip microcontrollers could manage all aspects of the drive control and had the capacity for battery management. MOSFETs are used in vehicles such as automobiles, cars, trucks, electric vehicles, and smart cars. MOSFETs are used for the electronic control unit (ECU), while the power MOSFET and IGBT are used as the load drivers for automotive loads such as motors, solenoids, ignition coils, relays, heaters and lamps. In 2000, the average mid-range passenger vehicle had an estimated $100200 of power semiconductor content, increasing by a potential 35 times for electric and hybrid vehicles. , the average vehicle has over 50 actuators, typically controlled by power MOSFETs or other power semiconductor devices.
Another important technology that enabled modern highway-capable electric cars is the lithium-ion battery. It was invented by John Goodenough, Rachid Yazami and Akira Yoshino in the 1980s, and commercialized by Sony and Asahi Kasei in 1991. The lithium-ion battery was responsible for the development of electric vehicles capable of long-distance travel, by the 2000s.
Types.
Automotive electronics or automotive embedded systems are distributed systems, and according to different domains in the automotive field, they can be classified into:
On average, a 2020s car has 50—150 chips, according to Chris Isidore of CNN Business.
Engine electronics.
One of the most demanding electronic parts of an automobile is the engine control unit (ECU). Engine controls demand one of the highest real-time deadlines, as the engine itself is a very fast and complex part of the automobile. Of all the electronics in any car, the computing power of the engine control unit is the highest, typically a 32-bit processor.
A modern car may have up to 100 ECU's and a commercial vehicle up to 40.
An engine ECU controls such functions as:
In a diesel engine:
In a gasoline engine:
Many more engine parameters are actively monitored and controlled in real-time. There are about 20 to 50 that measure pressure, temperature, flow, engine speed, oxygen level and NOx level plus other parameters at different points within the engine. All these sensor signals are sent to the ECU, which has the logic circuits to do the actual controlling. The ECU output is connected to different actuators for the throttle valve, EGR valve, rack (in VGTs), fuel injector (using a pulse-width modulated signal), dosing injector and more. There are about 20 to 30 actuators in all.
Transmission electronics.
These control the transmission system, mainly the shifting of the gears for better shift comfort and to lower torque interrupt while shifting. Automatic transmissions use controls for their operation, and also many semi-automatic transmissions having a fully automatic clutch or a semi-auto clutch (declutching only). The engine control unit and the transmission control exchange messages, sensor signals and control signals for their operation.
Chassis electronics.
The chassis system has a lot of sub-systems which monitor various parameters and are actively controlled:
Passive safety.
These systems are always ready to act when there is a collision in progress or to prevent it when it senses a dangerous situation:
Entertainment systems.
All of the above systems form an infotainment system. Developmental methods for these systems vary according to each manufacturer. Different tools are used for both hardware and software development.
Electronic integrated cockpit systems.
These are new generation hybrid ECUs that combine the functionalities of multiple ECUs of Infotainment Head Unit, Advanced Driver Assistance Systems (ADAS), Instrument Cluster, Rear Camera/Parking Assist, Surround View Systems etc. This saves on the cost of electronics as well as mechanical/physical parts like interconnects across ECUs etc. There is also a more centralized control so data can be seamlessly exchanged between the systems.
There are of course challenges too. Given the complexity of this hybrid system, a lot more rigor is needed to validate the system for robustness, safety and security. For example, if the infotainment system's application which could be running an open-source Android OS is breached, there could be possibility of hackers to take control of the car remotely and potentially misuse it for anti-social activities. Typically so, usage of a hardware+software enabled hypervisors are used to virtualize and create separate trust and safety zones that are immune to each other's failures or breaches. Lot of work is happening in this area and potentially will have such systems soon if not already.
Functional safety requirements.
In order to minimize the risk of dangerous failures, safety-related electronic systems have to be developed following the applicable product liability requirements. Disregard for, or inadequate application of these standards can lead to not only personal injuries, but also severe legal and economic consequences such as product cancellations or recalls.
The IEC 61508 standard, generally applicable to electrical/electronic/programmable safety-related products, is only partially adequate for automotive-development requirements. Consequently, for the automotive industry, this standard is replaced by the existing ISO 26262, currently released as a Final Draft International Standard (FDIS). ISO/DIS 26262 describes the entire product life-cycle of safety-related electrical/electronic systems for road vehicles. It has been published as an international standard in its final version in November 2011. The implementation of this new standard will result in modifications and various innovations in the automobile electronics development process, as it covers the complete product life-cycle from the concept phase until its decommissioning.
Security.
As more functions of the automobile are connected to short- or long-range networks, cybersecurity of systems against unauthorized modification is required. With critical systems such as engine controls, transmission, airbags, and braking connected to internal diagnostic networks, remote access could result in a malicious intruder altering the function of systems or disabling them, possibly causing injuries or fatalities. Every new interface presents a new "attack surface". The same facility that allows the owner to unlock and start a car from a smartphone app also presents risks due to remote access. Auto manufacturers may protect the memory of various control microprocessors both to secure them from unauthorized changes and also to ensure only manufacturer-authorized facilities can diagnose or repair the vehicle. Systems such as keyless entry rely on cryptographic techniques to ensure "replay" or "man-in-the-middle attacks" attacks cannot record sequences to allow later break-in to the automobile.
In 2015 the German general automobile club commissioned an investigation of the vulnerabilities of one manufacturer's electronics system, which could have led to such exploits as unauthorized remote unlocking of the vehicle.


Spectral signature

Spectral signature is the variation of reflectance or emittance of a material with respect to wavelengths (i.e., reflectance/emittance as a function of wavelength). The spectral signature of stars indicates the composition of the stellar atmosphere. The spectral signature of an object is a function of the incidental EM wavelength and material interaction with that section of the electromagnetic spectrum.
The measurements can be made with various instruments, including a task specific spectrometer, although the most common method is separation of the red, green, blue and near infrared portion of the EM spectrum as acquired by digital cameras. Calibrating spectral signatures under specific illumination are collected in order to apply a correction to airborne or satellite imagery digital images.
The user of one kind of spectroscope looks through it at a tube of ionized gas. The user sees specific lines of colour falling on a graduated scale. Each substance will have its own unique pattern of spectral lines.
Most remote sensing applications process digital images to extract spectral signatures at each pixel and use them to divide the image in groups of similar pixels (segmentation) using different approaches. As a last step, they assign a class to each group (classification) by comparing with known spectral signatures. Depending on pixel resolution, a pixel can represent many spectral signature "mixed" together - that is why much remote sensing analysis is done to "unmix mixtures". Ultimately correct matching of spectral signature recorded by image pixel with spectral signature of existing elements leads to accurate classification in remote sensing.


J. Erik Jonsson

John Erik Jonsson (6 September 1901 – 31 August 1995) was a co-founder and former president of Texas Instruments Incorporated. He became Mayor of Dallas, a major factor in the creation of Dallas-Fort Worth International Airport, and a philanthropist in later years.
Biography.
Erik Jonsson was born on 6 September 1901 in the Brooklyn borough of New York City. His parents, John Peter and Ellen Charlotte (Palmquist) Jonsson, were both born in Sweden and independently migrated to the United States in the prior decade. Both were naturalized citizens. Jonsson was an only child. The family moved in 1912 to Montclair, New Jersey, where at the age of sixteen Jonsson graduated from Montclair High School. Jonsson was a graduate of Rensselaer Polytechnic Institute (RPI), class of 1922 earning a degree in mechanical engineering. He was an Alpha Tau Omega. Jonsson married Margaret Fonde in Knoxville, Tennessee on 8 February 1923 and together they had three children.
Business career.
Jonsson began his career in 1922 at Alcoa as a rolling mill apprentice, and advanced to the position of manufacturing superintendent of an Alcoa subsidiary, the Aluminum Index Company. He held the position from 1923 to 1927. In 1927 he left Alcoa and entered the auto business attempting a Pontiac dealership, returning to Alcoa in 1929 as a sales engineer.
During Jonsson's last year at Alcoa, J. Clarence Karcher the husband of Mrs. Jonsson's cousin, occasionally asked Jonsson's assistance with expediting materials orders for his start-up company, Geophysical Service Incorporated a pioneering provider of seismic exploration services to the petroleum industry. In June 1930 Karcher offered Jonsson a job managing the manufacture of seismic instruments at Karcher's company lab in Newark, New Jersey, and in July Jonsson again left Alcoa.
In 1934, Jonsson and his family moved to Dallas, Texas. Jonsson held the position of secretary of Geophysical Service, which gave him responsibility for all of the accounting, banking, international, legal, manufacturing, personnel, purchasing, and warehousing activities of the company. Jonsson held this position until 1939.
In 1939, the company reorganized as Coronado Corp., an oil company with Geophysical Service Inc (GSI), now as a subsidiary. In 1939, Jonsson became secretary-treasurer. On 6 December 1941, Jonsson along with three other GSI employees, Eugene McDermott, Cecil H. Green, and H.B. Peacock purchased GSI. In 1942, he became vice president and treasurer. He held this position until 1951. During World War II, GSI built electronics for the United States Army Signal Corps and the Navy. After the war GSI continued to produce electronics. The rugged nature of equipment for the oil industry and of military equipment were similar and thus continued expansion into military contracts was a natural progression. In 1951, the company changed its name to Texas Instruments; GSI becoming a wholly owned subsidiary of the new company. Jonsson became president of Texas Instruments, a position he held until 1958. Jonsson was elected chairman of the board in 1958 and held this position until 1966. He became honorary chairman in 1966 through 1977.
Civic activities.
Jonsson was a strong advocate for education, serving or leading on the boards of many educational institutions and created alliances to improve local educational facilities. Jonsson was a founder of the Southwest Center for Advanced Studies, which became the University of Texas at Dallas in 1969.
In 1964, shortly after the assassination in Dallas of President John F. Kennedy, Jonsson became mayor of Dallas, Texas. He worked to improve morale and the image of the city. He was reelected three times. Jonsson pushed through a $175 million bond that financed a new city hall, the Dallas Convention Center and the Dallas Central Library. He was a central leader in the development of Dallas-Fort Worth International Airport.
Legacy.
Several facilities bear Jonsson's name in recognition of his contributions. These include the J. Erik Jonsson Central Library in Dallas, and the well-known Erik Jonsson School of Engineering and Computer Science at the University of Texas at Dallas in Richardson. A trustee of Rensselaer Polytechnic Institute, he helped fund major campus improvements, leading the institute to name the Jonsson Engineering Center and Jonsson-Rowland Science Center in his honor. The J. Erik Jonsson Center of the National Academy of Sciences, overlooking Quissett Harbor in Woods Hole on Cape Cod, is also named in honor of Jonsson. He also served as a trustee of Margaret's alma mater Skidmore College in Saratoga Springs, New York. Although founded in 1912, Skidmore started a new campus of which the Jonssons largely funded construction in the 1960s.


Oxymormyrus

Oxymormyrus is a small genus of elephantfish in the family Mormyridae. Its members reach about in length and are restricted to the Congo, Campo, Kouilou-Niari, Nyanga and Ogowe river basins in Middle Africa.
Taxonomy and species.
The validity of this genus is disputed. Catalog of Fishes only includes one species, while a second (marked with a star* in the list) occasionally has been included. Both these are placed in "Mormyrops" by FishBase.


SS Arctic

SS "Arctic" was a 2,856-ton paddle steamer, one of the Collins Line, which operated a transatlantic passenger and mail steamship service during the 1850s. She was the largest of a fleet of four, built with the aid of U.S. government subsidies to challenge the transatlantic supremacy of the British-backed Cunard Line. During its four-year period of service, the ship was renowned both for its speed and for the luxury of its accommodation.
On September 27, 1854, while on passage to New York from Liverpool, "Arctic" collided in fog with the French steamer "Vesta" off the coast of Newfoundland, and sank four hours later. "Arctic's" lifeboat capacity was around 180, enough for less than half those on board; the boats were launched in an atmosphere of panic and disorder, and the principle of "women and children first" was ignored. From around 400 on board (250 passengers, 150 crew), 24 male passengers and 61 crew survived; all the women and children died. No one was called to account for the disaster, and no official enquiry was held. Lifeboat provision on passenger-carrying ships remained inadequate until well into the 20th century.
Background.
The first shipping line to begin regular transatlantic steamer services was the British-backed Cunard Line, which began operating on July 4, 1840, with the departure from Liverpool of RMS "Britannia", bound for Halifax, Nova Scotia, and Boston. As the principal transatlantic mail carrier, the Cunard Line received subsidies from the British government and from the United States Post Office Department; many Americans, however, thought that an American line should benefit from these subsidies. Thus, in 1845, the United States Postmaster General asked shipowners to tender for the right to operate a subsidized passenger and mail service between the U.S. to Europe. The successful bidder, announced on March 3, 1847, was Edward Knight Collins. On the basis of the mail contract Collins founded the New York and Liverpool United States' Mail Steamship Company, familiarly known as the Collins Line, and begin an ambitious steamship construction program.
Construction and launching.
The William H. Brown and the Jacob Bell shipyards were each contracted to build two large wooden paddle steamers, for use by Collins in a regular twice-monthly transatlantic mail service. The Collins line would receive an annual subsidy, initially of $385,000 a year, from the U.S. government. Part of the government's interest in the project lay in the potential of these ships for use in times of war; they were constructed in a manner that facilitated rapid conversion to warships should the need arise. "Arctic", built at Brown's shipyard and designed by George Steers, was the third of the four ships to be launched, following "SS Atlantic" and "SS Pacific", and was marginally the largest of the four. She was in length, and measured at 2,856 tonnage by the U.S. Custom House measurement then in use. Her two side-lever steam engines, which accounted for $250,000 of the total construction cost of $700,000, were built and fitted by Stillman, Allan and Company. Each generated 1,000 horsepower, turning the paddle wheels at 16 revolutions a minute at full speed. Like her sister ships, "Arctic" was built to a luxurious standard; a contemporary description refers to her furnishings and fittings as giving "an air of almost Oriental magnificence." The ladies' saloon was described as a "gorgeous yet beautiful apartment, brilliant with light [presenting] as cheerful a scene as the heart could crave."
"Arctic" was launched on January 28, 1850, from Brown's yard on New York's East River, before a large crowd. According to a press account, she was "the most stupendous vessel ever constructed in the United States, or the world, since the patriarchal days of Noah." The "New York Herald"s reporter described the crowd's reaction as the ship slid into the water: "Men waved their hats, ladies their handkerchiefs, in admiration of the glad event ... the thousands who witnessed her launch [stood] for nearly half an hour, contemplating the splendid vessel."
Service history.
Under her captain, James F. Luce, "Arctic", now fully fitted out, underwent her sea trials during October 18–19, 1850, in preparation for entering regular transatlantic service on October 26. That first voyage, to Liverpool, passed without incident. In the years that followed, "Arctic" established a reputation as one of the fastest of ocean liners, regularly completing the crossing in ten days and sometimes less; in February 1852 she reached Liverpool in nine days, seventeen hours, considered an exceptional time for a winter crossing. She became the most celebrated of the Collins ships, and was known as the "clipper of the sea." On 23 November 1853, "Arctic" ran aground on the Burbo Bank, in Liverpool Bay whilst on a voyage from New York to Liverpool. She was refloated and taken in to Liverpool. On 18 May 1854, "Arctic" struck the Black Rock, off the coast of the Saltee Islands, County Wexford whilst on a voyage from Liverpool to New York. She was refloated and put back to Liverpool. In July 1854, "Arctic"s engines were adapted, in the hopes of reducing the heavy fuel costs that were helping to undermine the ship's profitability. The "Baltimore Sun" reported that the modifications were an invention of a Baltimore firm, Wethered Bros, and if successful, would reduce fuel costs by half. The powerful engines fitted to "Arctic" and her sisters strained their wooden hulls, and the line incurred large expenses in maintaining the vessels.
Sinking.
On September 27, 1854, while en route to New York from Liverpool, the "Arctic" collided with SS "Vesta", a much smaller vessel, 50 miles off the coast of Newfoundland. There were roughly 400 persons on board "Arctic" – approximately 250 passengers and 150 crew. Captain Luce's first thought was to give assistance to the stricken "Vesta", which appeared in danger of sinking, but when he was told that his own ship was holed beneath the waterline, he decided to make for the nearest land. As attempts to plug the leaks failed, "Arctic"s hull steadily filled with sea water. The boiler fires were gradually extinguished and the engines slowed and stopped, still far from land.
In accordance with the maritime regulations then in force, "Arctic" carried six lifeboats, the total capacity of which was around 180. Luce ordered these launched, but a breakdown in discipline among the crew meant that most places in the boats were taken by members of the crew or by the more able-bodied passengers; one of which was the French Ambassador, the duc de Gramont who was observed jumping from the ship into one of the last lifeboats.
The rest were left with makeshift rafts, or were unable to leave the ship and went down with her when she sank, four hours after the collision. Captain Luce, himself, unlike his crew, went down with his ship, although he survived. Meanwhile, "Vesta", which appeared to have sustained mortal damage, was saved from sinking by her watertight bulkheads, and was able to gain the harbour at St. Johns, Newfoundland.
Two of the six lifeboats that left "Arctic" safely reached the Newfoundland shore, and another was picked by a passing steamer which also rescued a few survivors from improvised rafts. Among these was Captain Luce, who had regained the surface after initially going down with the ship. He was rescued after clinging to wreckage of the paddle-wheel box for two days. The other three boats disappeared without trace.
In all, more than 300 lives were lost; the 85 survivors included 61 of the crew and 24 male passengers. All the women and children on board perished. Among those lost were the wife of Edward Collins and two of his children. Other victims included several members of the Brown family, whose bank, Brown Brothers, had helped to finance the Collins Line. Also lost was Frederick Catherwood, the English architect and painter whose name was mysteriously left off the official casualty lists for weeks until a concerted effort by his friends and colleagues resulted in a belated inclusion by the authorities and newspapers. In addition to the tragic loss of human life, a rare copy of William Shakespeare's First Folio that New York lawyer and Shakespeare collector Aldon W. Griswold had purchased and shipped from Liverpool, was lost. Among the lost as well were Mahlon Day, prominent New York publisher of children's books and business publications, with his wife and daughter.
Aftermath.
The limited telegraph communications of the time meant that news of "Arctic"s loss did not reach New York until two weeks after the sinking. As the full story emerged, initial public sorrow at the ship's loss quickly turned to condemnation of the perceived cowardice of the crew, and their failure of duty towards their passengers. Although some newspapers demanded an inquiry into the disaster, none was held, and nobody was called to account for their actions. Proposals that lifeboat capacity on passenger-carrying vessels should be increased, to provide a place for every person on board, were not acted on. Captain Luce, who was generally exonerated from blame by the public, retired from the sea; some of the crew survivors chose not to return to the US. The Collins Line continued its transatlantic service, until further maritime losses and insolvency led to its closure in 1858.
James Brown, president of Brown Brothers bank and the Collins Line, erected a grand monument in Green-Wood Cemetery, Brooklyn, New York, to the six members of his family lost in the "Arctic" disaster. This incorporates a sculpture of the ship, half-submerged by the waves. The names of those who died are inscribed on the pedestal.


USS Frank E. Evans

USS "Frank E. Evans" (DD-754), an , was named in honor of Brigadier General Frank Evans, USMC, a leader of the American Expeditionary Force in France during World War I. She served in late World War II, the Korean War and the Vietnam War before being cut in half in a collision with HMAS in 1969.
Construction.
Her keel was laid down at the Bethlehem Steel Company shipyard in Staten Island, New York. She was launched on 3 October 1944 sponsored by Mrs. Frank E. Evans, widow of General Evans, and commissioned on 3 February 1945, with Commander Harry Smith in command.
Service history.
World War II.
"Frank E. Evans" arrived at Pearl Harbor on 18 May 1945 for her final training, and crossed to Eniwetok, Guam, Ulithi, and Okinawa on escort duty. Reaching action waters on 24 June, she was assigned to radar picket and local escort duty, often firing on enemy aircraft. At the close of hostilities, she patrolled the Yellow Sea and the Gulf of Chihli, embarked released Americans from prisoner of war camps near Dairen, Manchuria, covered occupation landings at Jinsen, Korea, and continued to operate in the Far East until 6 March 1946 when she sailed from Tsingtao for San Francisco, California. Immobilized there on 31 March, "Evans" was decommissioned and placed in reserve on 14 December 1949.
Korean War.
Recommissioned on 15 September 1950 for duty in the Korean War, "Evans" sailed from San Diego, California on 2 January 1951 for duty with the 7th Fleet. On 26 February, she began her part in the lengthy siege of Wonsan, during which she engaged enemy shore batteries 11 times. On 18 June, she was struck by 30 shrapnel hits, which caused minor wounds to four crewmembers before the destroyer silenced the enemy battery. It was during this time that "Frank E. Evans" earned the nicknames "Lucky Evans" and the "Gray Ghost".
During this tour of duty, "Evans" also bombarded targets in the Songjin-Chongjin area, rescued downed aviators, and coordinated and controlled day and night bombing missions by United Nations aircraft. She returned to San Diego on 4 September 1951.
"Evans" sailed on 22 March 1952 for her second Korean tour, serving on patrol and bombardment duty along the coast of Korea and on the Taiwan Patrol before returning to her new home port, Long Beach, California, on 6 November 1952 for three months. Her tour in the Far East from 13 June to 20 December 1953 coincided with the Korean armistice, and was devoted primarily to patrol duty.
While riding out Typhoon Pamela in the Taiwan Straits in early November 1954, "Frank E. Evans" responded to an SOS by USNS "Muskingum", which had lost steering control near the center of the storm. "Frank E. Evans" had escaped to the edge of the typhoon, but turned back into the storm racing for five hours to render assistance while taking damage in the process. In the end, "Muskingum" was able to regain control before "Frank E. Evans" arrived, but the incident was widely publicized in newspaper syndication because Pulitzer prize winning correspondent Homer Bigart was reporting from "Frank E. Evans" during that period.
From 1954 to 1960, "Evans" completed five tours of duty in the Far East, as well as joining extensive training operations along the west coast and in the Hawaiian Islands, occasionally with Canadian naval ships.
From 1962 to 1963, the ship was the fictitious "Appleby" used in the NBC military comedy series "Ensign O'Toole" starring Dean Jones in the title role.
Vietnam War.
According to the US Navy Awards file, "Frank E. Evans" served in the waters off Vietnam for 12 days from July to September 1965. "Evans" was again in the vicinity of Vietnam for 61 days from August to November 1966. "Evans" returned to Vietnam and served there for 66 days from October 1967 to 20 February 1968. During the Tet Offensive, on 3 February 1968, "Frank E. Evans" provided naval gunfire support to the 101st Airborne Division near Phan Thiết against the 840th VC Battalion. "Evans" also spent an additional 14 days in 1969 in the Vietnam war zone.
Collision with HMAS "Melbourne".
At around 3:00 a.m. on 3 June 1969, between Vietnam and Spratly Island, "Frank E. Evans" was operating with the Royal Navy, Royal Australian Navy and Royal New Zealand Navy in company with the aircraft carrier which was in the process of going to flying stations and all ships in the formation were running without lights. "Melbourne" radioed "Evans", then to port of the carrier, to take up the rescue destroyer position. The logical movement would be to turn to port and make a circle taking up station on the carrier's port quarter. However, since the conning officer on "Evans" misunderstood the formation's base course and believed they were starboard of "Melbourne", they turned to starboard, cutting across the carrier's bow twice in the process. "Frank E. Evans" was struck at a point around 92 feet from her bow on her port side and was cut in two. Her bow drifted off to the port side of "Melbourne" and sank in less than five minutes taking 73 of her crew with it. One body was recovered from the water, making a total of 74 dead. The stern scraped along the starboard side of "Melbourne" and lines were able to be attached by the crew of "Melbourne". Around 60–100 men were also rescued from the water.
At the time of the collision the commanding officer of "Frank E. Evans" was asleep in his quarters having left instructions to be awakened if there were to be any changes in the formation. Neither the officer of the deck nor the junior officer of the deck notified him when the station change was ordered. The bridge crew also did not contact the combat information center to request clarification of the positions and movements of the surrounding ships. The collision occurred at .
USS "Frank E. Evans" was decommissioned at Subic Bay and stricken from the Naval Vessel Register on 1 July 1969. The stern section was sunk as a target in Subic Bay on 10 October 1969.
Awards.
"Frank E. Evans" received one battle star for World War II service, and five for Korean War service. According to the US Navy unit award website, "Frank E. Evans" had the following awards:
Based on history USS "Frank E. Evans" was also awarded the following:


Cross motif

In music, the cross motif is a motif.
A motif ("Crux fidelis") was used by Franz Liszt to represent the Christian cross ('tonisches Symbol des Kreuzes' or tonic symbol of the cross) and taken from Gregorian melodies.


List of Carl Zeiss Bessamatic DKL-mount lenses


370th Flight Test Squadron

The 370th Flight Test Squadron is a United States Air Force unit assigned to the 413th Flight Test Group, stationed at Edwards Air Force Base, California.
Mission.
The squadron is assigned to the United States Air Force Reserve and performs flight testing.
History.
World War II.
Formed as a heavy bombardment group in January 1942, trained in the Pacific Northwest under Second Air Force, with B-17 Flying Fortresses. Reassigned to Seventh Air Force in Hawaii, November 1942, performing search and rescue and antisubmarine patrols until January 1943 while transitioning to long-range B-24 Liberator heavy bombers.
Deployed to Central Pacific from Hawaii throughout 1943 for long-range combat bombardment operations against Japanese forces in the Central Pacific; New Guinea; Northern Solomon Islands and Eastern Mandates campaigns. Deployed to the New Hebrides in the South Pacific and operated from numerous temporary jungle airfields, engaging in long-range bombardment operations during the Bismarck Archipelago; Western Pacific; Leyte; Luzon and Southern Philippines campaigns until the end of the war in August 1945. Assigned to Clark Field, Philippines after the war ended, demobilized with personnel returning to the United States, unit inactivated as paper unit in January 1946 in California.
Strategic Air Command.
Reactivated as Boeing B-29 Superfortress squadron at MacDill Field, Florida in August 1946 as part of Strategic Air Command. Was a training unit for antisubmarine warfare.
Korean War.
Deployed to Okinawa during the Korean War, carrying out combat operations over Korea throughout the conflict. Remained in Okinawa until November 1954 when moved to the United States on paper.
Return to Strategic Air Command.
Reformed at Lincoln Air Force Base, Nebraska, as a Boeing B-47 Stratojet medium jet bomber squadron, performed Operation Reflex deployments to North Africa until phaseout of B-47 in 1965 and inactivated.
Flight Testing.
Reactivated as a flight test squadron in 2001.