omniomni/omni-engineering huggingface dataset:
Magnesium sulfide. Magnesium sulfide is an inorganic compound with the formula MgS. It is a white crystalline material but often is encountered in an impure form that is brown and non-crystalline powder. It is generated industrially in the production of metallic iron.

Preparation and general properties
MgS is formed by the reaction of sulfur or hydrogen sulfide with magnesium.  It crystallizes in the rock salt structure as its most stable phase, its zinc blende and wurtzite structures can be prepared by molecular beam epitaxy. The chemical properties of MgS resemble those of related ionic sulfides such as those of sodium, barium, or calcium. It reacts with oxygen to form the corresponding sulfate, magnesium sulfate.  MgS reacts with water to give hydrogen sulfide and magnesium hydroxide.

Applications
In the BOS steelmaking process, sulfur is the first element to be removed. Sulfur is removed from the impure blast furnace iron by the addition of several hundred kilograms of magnesium powder by a lance. Magnesium sulfide is formed, which then floats on the molten iron and is removed.

MgS is a wide band-gap direct semiconductor of interest as a blue-green emitter, a property that has been known since the early 1900s. The wide-band gap property also allows the use of MgS as photo-detector for short wavelength ultraviolet light.

Occurrence
Aside from being a component of some slags, MgS is a rare nonterrestrial mineral niningerite detected in some meteorites.  It is also a solid solution component along with CaS and FeS in oldhamite. MgS is also found in the circumstellar envelopes of certain evolved carbon stars, i. e., those with C/O  > 1.

Safety
MgS evolves hydrogen sulfide upon contact with moisture.

References

Monosulfides
Magnesium compounds
II-VI semiconductors
Rock salt crystal structure
Harvard Mark IV. The Harvard Mark IV was an electronic stored-program computer built by Harvard University under the supervision of Howard Aiken for the United States Air Force. The computer was finished being built in 1952. It stayed at Harvard, where the Air Force used it extensively.

The Mark IV was all electronic.  The Mark IV used magnetic drum and had 200 registers of ferrite magnetic-core memory (one of the first computers to do so). It separated the storage of data and instructions in what is now sometimes referred to as the Harvard architecture although that term was not coined until the 1970s (in the context of microcontrollers).

See also
 Harvard Mark I
 Harvard Mark II
 Harvard Mark III
 List of vacuum-tube computers

References

Further reading

External links
 Harvard Mark IV 64-bit Magnetic Shift Register at ComputerHistory.org

1950s computers
Computer-related introductions in 1952
Vacuum tube computers
One-of-a-kind computers
Harvard University
Major stationary source. A major stationary source is a source that emits more than a certain amount of a pollutant as defined by the U.S. Environmental Protection Agency (EPA). The amount of pollutants allowed for certain new sources is defined by the EPA's New Source Performance Standards (NSPRS).

A stationary source in air quality terminology is any fixed emitter of air pollutants, such as fossil fuel burning power plants, petroleum refineries, petrochemical plants, food processing plants and other heavy industrial sources.

A mobile source in air quality terminology is a non-stationary source of air pollutants, such as automobiles, buses, trucks, ships, trains, aircraft and various other vehicles.

See also
Air pollution dispersion terminology
Atmospheric dispersion modeling
AP 42 Compilation of Air Pollutant Emission Factors
Lowest Achievable Emissions Rate

References

United States Environmental Protection Agency
Atmospheric dispersion modeling
Zero page (CP/M). The Zero Page (or Base Page) is a data structure used in CP/M systems for programs to communicate with the operating system. In 8-bit CP/M versions it is located in the first 256 bytes of memory, hence its name.

The equivalent structure in DOS is the Program Segment Prefix (PSP), a 256-byte (page-sized) structure, which is by default located exactly before offset 0 of the program's load segment, rather than in segment 0. A segment register is initialised to 0x10 less than the code segment, in order to address it.

In 8-bit CP/M, it has the following structure:

In CP/M-86, the structure is:

See also
 Zero page (processor property)
 Page boundary relocation

References

Further reading
  - in particular:
 
 

CP/M technology
Henry Baker (computer scientist). Henry Givens Baker Jr. is an American computer scientist who has made contributions in garbage collection, functional programming languages, and linear logic. He was one of the founders of Symbolics, a company that designed and manufactured a line of Lisp machines. In 2006 he was recognized as a Distinguished Scientist by the Association for Computing Machinery.

He is notable for his research in garbage collection, particularly Baker's real-time copying collector, and on the Actor model.

Baker received his B.Sc. (1969), S.M. (1973), E.E. (1973), and Ph.D. (1978) degrees at M.I.T.

The Chicken Scheme compiler was inspired by an innovative design of Baker's.

Bibliography

References

External links
 Henry Baker's Archive of Research Papers at the Internet Archive

Programming language researchers
Living people
Year of birth missing (living people)
Massachusetts Institute of Technology alumni
American computer scientists
21st-century American scientists
20th-century American scientists
GeneXus. GeneXus is a low code, cross-platform, knowledge representation-based development tool, mainly oriented towards enterprise-class applications for web applications, smart devices, and the Microsoft Windows platform.

GeneXus uses mostly declarative language to generate native code for multiple environments. It includes a normalization module, which creates and maintains an optimal database structure based on user views. The languages for which code can be generated include COBOL, Java, Objective-C, RPG, Ruby, Visual Basic, and Visual FoxPro. Some of the DBMSs supported are Microsoft SQL Server, Oracle, IBM Db2, Informix, PostgreSQL, and MySQL.

GeneXus was developed by Uruguayan company ARTech Consultores SRL which later renamed to Genexus SA. The latest version is GeneXus 18, which was released on November 10, 2022.

See also 
 Comparison of code generation tools
 List of low-code development platforms

References

External links
 
 

1988 software
Declarative programming languages
Integrated development environments
Programming tools
Prolog software
Side-spar cable-stayed bridge. A side-spar cable-stayed bridge may be an otherwise conventional cable-stayed bridge, but its cable support does not span the roadway, and is instead cantilevered from one side. The Esplanade Riel illustrated is located in Winnipeg, Manitoba, Canada. This bridge is intended for pedestrian use only and has a restaurant in its base.

In the example below the cable paths are aligned with the bridge centerline, so that structurally it differs only in the transfer of stresses through the tower to the foundation.

The side-spar principle is not limited to a straight bridge, however. The tower could be offset and the bridge deck wrap around the spar in an arc, e.g., Chords Bridge in Jerusalem. Such a bridge would be particularly suited for use in the confines of a canyon, where the road is brought in the upstream direction down one side, crosses a stream, and turns back to a downstream direction on the other side. By placing a large portion of the turn on the bridge, rather than on the approaches, the turn may be made more gentle, allowing faster traffic. This would require more torsional (twisting) rigidity in the roadbed than would a straight bridge. A bridge of this type (supported by a spar), traveling through a much smaller arc, was one of the original proposals for the eastern span replacement of the San Francisco-Oakland Bay Bridge. Similar bridges, without the spar, could be supported by cables anchored in the canyon walls (where conditions are suitable).

This subtype should not be confused with an asymmetrical single tower cable-stayed bridge, which possesses a single tower on one side of the gap to be crossed (see Rama VIII Bridge), nor with the cantilever spar cable-stayed bridge, which has span supporting cables on only one side of the tower along the direction of the roadbed.

Image gallery

See also
Cantilever spar cable-stayed bridge

References

Bridges by structural type
Liroconite. Liroconite is a complex mineral: Hydrated copper aluminium arsenate hydroxide, with the formula Cu2Al[(OH)4|AsO4]·4(H2O). It is a vitreous monoclinic mineral, colored bright blue to green, often associated with malachite, azurite, olivenite, and clinoclase. It is quite soft, with a Mohs hardness of 2–2.5, and has a specific gravity of 2.9–3.0.

It was first identified in 1825 in the tin and copper mines of Devon and Cornwall, England. Although it remains quite rare it has subsequently been identified in a variety of locations including France, Germany, Australia, New Jersey and California.

The type locality for liroconite is Wheal Gorland in St Day, Cornwall in the United Kingdom. The largest crystal specimen on public display is in the Royal Cornwall Museum in Truro.

It occurs as a secondary mineral in copper deposits in association with olivenite, chalcophyllite, clinoclase, cornwallite, strashimirite, malachite, cuprite and limonite.

Structure
Liroconite crystallizes in the monoclinic crystal system. The crystal structure consists of a framework of AsO4 tetrahedra, Jahn-Teller-distorted [CuO2(OH)2(H2O)2] octahedra and [AlO2(OH)4] octahedra.

See also
Kernowite – an isostructural mineral with iron in place of aluminium

References

Copper(II) minerals
Arsenate minerals
Monoclinic minerals
Minerals in space group 15
Street elbow. A street elbow (sometimes called a street ell or service ell) is a type of plumbing or piping fitting intended to join a piece of pipe and another fitting at an angle. The difference between a street elbow and a regular elbow is the gender of its two connections.

A regular elbow has a hub or female-threaded connection on each end, so it can join two male pipes. Instead, a street elbow has a female fitting on one end and a male fitting on the other. The advantage of the street elbow is that it can be connected directly to another fitting without having to use an additional short connecting piece (a pipe nipple).

Applications
Street elbows are available with bend angles of 90°, 45°, and 22.5°. They can be used in many plumbing applications, including water supply, drainage, sewers, vents, central vacuum systems, compressed air and gas lines, heating and air conditioning, sump pump drains, and other locations where plumbing fittings would be used to join sections of pipe.

Plumbing codes regulate the use of street elbows. For example, Canada's national plumbing code prohibits them in natural gas and propane installations:
Street elbows and tees are not permitted because these fittings have both male and female threaded ends. This makes alignment of the piping difficult since the direction of the piping does not always correspond with the fully seated position of the fitting. When the connection is backed off to align the piping, leakage may result.

See also
 Coupling (piping)
 Elbow (piping)
 Piping and plumbing fittings

References

Plumbing
Honda E series. The E series was a collection of successive humanoid robots created by the Honda Motor Company between the years of 1986 and 1993. These robots were only experimental, but later evolved into the Honda P series, with Honda eventually amassing the knowledge and experience necessary to create Honda's advanced humanoid robot: ASIMO. The fact that Honda had been developing the robots was kept secret from the public until the announcement of the Honda P2 in 1996.

E0, developed in 1986, was the first robot. It walked in a straight line on two feet, in a manner resembling human locomotion, taking around 5 seconds to complete a single step. Quickly engineers realised that in order to walk up slopes, the robot would need to travel faster. The model has 6 degrees of freedom: one in each groin, one in each knee and one in each ankle.

Models
E0, developed in 1986.
E1, developed in 1987, was larger than the first and walked at 0.25 km/h. This model and subsequent E-series robots have 12 degrees of freedom: 3 in each groin, 1 in each knee and 2 in each ankle.
E2, developed in 1989, could travel at 1.2km/h, through the development of "dynamic movement".
E3, developed in 1991, travelled at 3km/h, the average speed of a walking human.
E4, developed in 1991, lengthened the knee to achieve speeds of up to 4.7km/h.
E5, developed in 1992, was able to walk autonomously, albeit with a very large head.
E6, developed in 1993, was able to autonomously balance, walk over obstacles, and even climb stairs.

See also
 Honda P series

References

External links

History of humanoid robots - Honda official website

Robotics at Honda
Bipedal humanoid robots
1986 robots
1987 robots
1989 robots
1991 robots
1992 robots
1993 robots
Products and services discontinued in 1993
Japanese inventions
Frank Austin Gooch. Frank Austin Gooch (1852 – 1929) was an American chemist and engineer.

Biography
He was born to Joshua G. & Sarah Gates (Coolidge) Gooch in Watertown, Massachusetts.  On his mother's side of the family, he was a descendant of Thomas Hastings who came from the East Anglia region of England to the Massachusetts Bay Colony in 1634.

Gooch invented the Gooch crucible, which is used, for example, to determine the solubility of bituminous materials such as road tars and petroleum asphalts.  He was awarded a Ph.D. by Harvard University in 1877.  Gooch was a professor of chemistry at Yale University from 1885 to 1918.

He devised or perfected a large number of analytical processes and methods, including:

 Invented the Gooch filtering crucible.
 Studied the quantitative separation of lithium from the other alkali metals, and the estimation of boric acid by distillation with methanol and fixation by calcium oxide. 
 Developed methods for estimating molybdenum, vanadium, selenium, and tellurium.
 Studied the use of the paratungstate and pyrophosphate ions in analysis.
 Developed a series of methods for estimating various elements based on the volumetric determination of iodine.
 Discovered a method for the rapid electrolytic estimation of metals.

He was a member of the Connecticut Academy of Arts and Sciences, the American Philosophical Society, the American Academy of Arts and Sciences, and the U.S. National Academy of Sciences.

Further reading

  Biog. Mem. Nat. Acad. Sci. 1931, 15, 105–135. 
  Ind. Eng. Chem. 1923, 15, 1088–1089. 
  Proc. Am. Acad. Arts Sci. 1935–36, 70, 541. 
  Am. J. Sci. (Ser. 5) 1929, 18, 539–540. 
  National Cyclopaedia of American Biography, James T. White & Co.:  1921–1984; vol. 12, p329-330.

References

External links
 Frank Austin Gooch (biography at University of Illinois)
 Descendants of Thomas Hastings website
 Descendants of Thomas Hastings on Facebook

1852 births
1929 deaths
American chemists
American engineers
Harvard University alumni
People involved with the periodic table
Members of the American Philosophical Society
Harrods Aviation. Harrods Aviation Limited (formerly known as Metro Business Aviation Ltd) is a fixed-base operator and maintenance, repair, and operations service provider for business and corporate aviation in the United Kingdom with bases at London Luton Airport and London Stansted Airport.

Air Harrods 
Air Harrods Limited is the aircraft charter brokering arm of the Harrods company based at London Stansted Airport.
 
Customers vary immensely; news footage has shown Tony Blair travelling to the G8 summit on board an Air Harrods helicopter which was commissioned by MI5 to offset security concerns. The use of one Air Harrods helicopter was donated for a special of Challenge Anneka in 2007. The helicopter was used to transport some ill children to a choir performance.

On 7 May 2010, Air Harrods was sold as part of its parent group to a Qatari sovereign investment group in a combined deal worth £1.5bn.

See also 
 Air Harrods
 Harrods
 Harrods Estates

References

External links
 

Aviation
Fixed-base operators
Companies based in Essex
Harmonichord. A harmonichord is a kind of upright piano in which the strings are set in vibration not by the blow of the hammer but by indirectly transmitted friction.

Description 

The harmonichord, one of the many attempts to fuse the piano and violin, was invented by Johann Gottfried Kaufmann and Johann Friedrich Kaufmann (father and son) in Saxony at the beginning of the 19th century, when the craze for new and ingenious musical instruments was at its height.

The case was of the variety known as giraffe. The space under the keyboard was enclosed, a knee-hold being left in which were two pedals used to set in rotation a large wooden cylinder fixed just behind the keyboard over the levers, and covered with a roll-top similar to those of modern office desks. The cylinder (in some specimens covered with chamois leather) tapered towards the treble-end. When a key was depressed, a little tongue of wood, one end of which stopped the string, was pressed against the revolving cylinder, and the vibrations produced by friction were transmitted to the string and reinforced as in the piano and violin by the soundboard. The adjustment of the parts and the velocity of the cylinder required delicacy and great nicety, for if the little wooden tongues rested too lightly upon the cylinder or the strings, harmonics were produced, and the note jumped to the octave or twelfth.
Sometimes when chords were played the touch became so heavy that two performers were required, as in the early medieval organistrum, the prototype of the harmonichord. Carl Maria von Weber must have had some opinion of the possibilities of the harmonichord, which in tone resembled the glass harmonica, since he composed a concerto with orchestral accompaniment for the instrument.

Notes

References

Box zithers
Hurdy-gurdies
Keyboard instruments
Bottleneck (engineering). In engineering, a bottleneck is a phenomenon by which the performance or capacity of an entire system is severely limited by a single component. The component is sometimes called a bottleneck point. The term is metaphorically derived from the neck of a bottle, where the flow speed of the liquid is limited by its neck. 

Formally, a bottleneck lies on a system's critical path and provides the lowest throughput. Bottlenecks are usually avoided by system designers, also a great amount of effort is directed at locating and tuning them. Bottleneck may be for example a processor, a communication link, a data processing software, etc.

Bottlenecks in software

In computer programming, tracking down bottlenecks (sometimes known as "hot spots" - sections of the code that execute most frequently - i.e. have the highest execution count) is called performance analysis. Reduction is usually achieved with the help of specialized tools, known as performance analyzers or profilers. The objective being to make those particular sections of code perform as fast as possible to improve overall algorithmic efficiency.

Bottlenecks in max-min fairness

In a communication network, sometimes a max-min fairness of the network is desired, usually opposed to the basic first-come first-served policy. With max-min fairness, data flow between any two nodes is maximized, but only at the cost of more or equally expensive data flows. To put it another way, in case of network congestion any data flow is only impacted by smaller or equal flows.

In such context, a bottleneck link for a given data flow is a link that is fully utilized (is saturated) and of all the flows sharing this link, the given data flow achieves maximum data rate network-wide. Note that this definition is substantially different from a common meaning of a bottleneck. Also note, that this definition does not forbid a single link to be a bottleneck for multiple flows.

A data rate allocation is max-min fair if and only if a data flow between any two nodes has at least one bottleneck link.

See also

 Fairness measure
 Max-min fairness
 Optimization (computer science)
 Performance engineering
 Profiling (computer programming)
 Route capacity
 Theory of constraints

References

Network performance
Power density. Power density, defined as the amount of power (the time rate of energy transfer) per unit volume, is a critical parameter used across a spectrum of scientific and engineering disciplines. This metric, typically denoted in watts per cubic meter (W/m3), serves as a fundamental measure for evaluating the efficacy and capability of various devices, systems, and materials based on their spatial energy distribution.

The concept of power density finds extensive application in physics, engineering, electronics, and energy technologies. It plays a pivotal role in assessing the efficiency and performance of components and systems, particularly in relation to the power they can handle or generate relative to their physical dimensions or volume.

In the domain of energy storage and conversion technologies, such as batteries, fuel cells, motors, and power supply units, power density is a crucial consideration. Here, power density often refers to the volume power density, quantifying how much power can be accommodated or delivered within a specific volume (W/m3).

For instance, when examining reciprocating internal combustion engines, power density assumes a distinct importance. In this context, power density is commonly defined as power per swept volume or brake horsepower per cubic centimeter. This measure is derived from the internal capacity of the engine, providing insight into its power output relative to its internal volume rather than its external size.  This extends to advancement in material science where new materials which can withstand higher power densities can reduce size or weight of devices, or just increase their performance.

The significance of power density extends beyond these examples, impacting the design and optimization of a myriad of systems and devices. Notably, advancements in power density often drive innovations in areas ranging from renewable energy technologies to aerospace propulsion systems.

Understanding and enhancing power density can lead to substantial improvements in the performance and efficiency of various applications. Researchers and engineers continually explore ways to push the limits of power density, leveraging advancements in materials science, manufacturing techniques, and computational modeling.

By engaging with these educational resources and specialized coursework, students and professionals can deepen their understanding of power density and its implications across diverse industries. The pursuit of higher power densities continues to drive innovation and shape the future of energy systems and technological development.

Examples

See also
Surface power density, energy per unit of area
Energy density, energy per unit volume
Specific energy, energy per unit mass
Power-to-weight ratio/specific power, power per unit mass
Specific absorption rate (SAR)

References

Power (physics)