omniomni/omni-engineering huggingface dataset:
Phase boundary. In thermal equilibrium, each phase (i.e. liquid, solid etc.) of physical matter comes to an end at a transitional point, or spatial interface, called a phase boundary, due to the immiscibility of the matter with the matter on the other side of the boundary.  This immiscibility is due to at least one difference between the two substances' corresponding physical properties. The behavior of phase boundaries has been a developing subject of interest and an active interdisciplinary research field, called interface science, for almost two centuries, due partly to phase boundaries naturally arising in many physical processes, such as the capillarity effect, the growth of grain boundaries, the physics of binary alloys, and the formation of snow flakes. 

One of the oldest problems in the area dates back to Lamé and Clapeyron who studied the freezing of the ground. Their goal was to determine the thickness of solid crust generated by the cooling of a liquid at constant temperature filling the half-space. In 1889, Stefan, while working on the freezing of the ground developed these ideas further and formulated the two-phase model which came to be known as the  Stefan Problem.

The proof for the existence and uniqueness of a solution to the Stefan problem was developed in many stages. Proving the general existence and uniqueness of the solutions in the case of  was solved by Shoshana Kamin.

References 

Phase transitions
Applied mathematics
Sodium hexanitritocobaltate(III). Sodium hexanitritocobaltate(III) is an inorganic compound with the formula . The anion of this yellow-coloured salt consists of the transition metal nitrite complex . It was a reagent for the qualitative test for potassium and ammonium ions.

Synthesis and reactions
The compound is prepared by oxidation of cobalt(II) salts in the presence of sodium nitrite:

Application for analysis of potassium
Although the sodium cobaltinitrite is soluble in water, it forms the basis of a quantitative determination of potassium, thallium, and ammonium ions. Under the recommended reaction conditions the insoluble double salt,  is precipitated and weighed. In geochemical analysis, sodium cobaltinitrite is used to distinguish alkali feldspars from plagioclase feldspars in thin section.

See also
 Potassium hexanitritocobaltate(III)

References

Cobalt complexes
Sodium compounds
Chemical tests
Inorganic compounds
Coordination complexes
Nitrites
Fukui University of Technology. The  is a private university founded in 1950 and located in Fukui, Fukui Prefecture, Japan. The university has undergraduate faculties in engineering, environmental and information sciences, and sports and health sciences, as well as a graduate department for applied science and engineering.

References

External links
Fukui University of Technology

Universities and colleges established in 1950
Universities and colleges in Fukui Prefecture
Private universities and colleges in Japan
Engineering universities and colleges in Japan
1950 establishments in Japan
Buildings and structures in Fukui (city)
Lockheed XV-4 Hummingbird. The Lockheed XV-4 Hummingbird (originally designated VZ-10) was a U.S. Army project to demonstrate the feasibility of using VTOL for a surveillance aircraft carrying target-acquisition and sensory equipment. It was designed and built by the Lockheed Corporation in the 1960s, one of many attempts to produce a V/STOL vertical take off/landing jet. Both prototype aircraft were destroyed in accidents.

Design and development
Vertical take-off lift was obtained by exhausting the engine flow downward through multiple nozzles, augmented by a secondary flow of cold air. But the performance was far below estimates with only a 1.04 thrust-to-weight ratio, and the prototype crashed on 10 June 1966, killing the pilot. The second aircraft was converted to lift jets instead, yet also crashed after several tests.

Rockwell's XFV-12 would be even less successful at producing lift by using engine exhaust to entrain cold air, in this case through flaps on the wings.

None of the early American V/STOL designs would result in a production aircraft. The British Hawker Siddeley Harrier used vectoring nozzles, while the Russian Yakovlev Yak-38 Forger attack jet used lift jets in conjunction with rotating rear nozzles. The Lockheed F-35 Lightning II would later employ a shaft-driven lift fan located in the fuselage.

Testing

The first conventional takeoff flight of the first prototype, XV-4A (62–4503), took place on 7 July 1962. Initial tethered flight tests were carried out on 30 November 1962 with the first free hovering flight occurring on 24 May 1963. The first flight to transition from hovering to forward flight took place on 8 November 1963. 62–4503 was destroyed in a fatal crash in Cobb County on 10 June 1966.

Lockheed modified the second prototype aircraft between 1966 and 1968 to XV-4B standard. The two Pratt & Whitney JT12 engines were replaced with six General Electric J85 turbojets, four of these units acting as lift jets. This aircraft crashed in Georgia on 14 March 1969; pilot Harlan J. Quamme escaped uninjured, using the ejection seat.

Variants

 XV-4A:
 XV-4B:

Specifications (XV-4A)

See also

Notes

References
 X-Planes and Prototypes by Jim Winchester

External links

 VSTOL.org Wheel

V-004
1960s United States experimental aircraft
Twinjets
Aircraft with auxiliary jet engines
Lift jet
Cancelled military aircraft projects of the United States
Mid-wing aircraft
Aircraft first flown in 1962
T-tail aircraft
Six-engined jet aircraft
Faraday cup electrometer. The Faraday cup electrometer is the simplest form of an electrical aerosol instrument used in aerosol studies. It consists of an electrometer and a filter inside a Faraday cage. Charged particles collected by the filter generate an electric current which is measured by the electrometer.

Principle
According to Gauss' law, the charge collected on the Faraday cup is the induced charge, that means that the filter does not need to be a conductor. It is typically used to measure particles of unipolar charge, which are particles with a net charge concentration that equals the charge concentration of positively or negatively charged particles.

With an aerosol electrometer the transportation of charge by electrical charged aerosol particles can be measured as electric current.

In a metal housing (Faraday cup) a particle filter is mounted on an insulator. A Faraday cup is a detector that measures the current in a beam of charged (aerosol) particles. Faraday cups are used e.g. in mass spectrometers being an alternative to secondary electron multipliers. The advantage of the Faraday cup is its robustness and the possibility to measure the ion or electron stream absolutely. Furthermore, the sensitiveness is constant by time and not mass-dependent. The simplest form is the following: A Faraday detector consists of a metal cup, that is placed in the path of the particle beam. The aerosol has to pass the filter inside the cup. The filter has to be isolated. It is connected to the electrometer circuit which measures the current.

See also
 Michael Faraday
 Faraday cup

References

Experimental physics
Aerosol measurement
American Gear Manufacturers Association. The American Gear Manufacturers Association (AGMA) is the trade group of companies involved in gears, couplings and related power transmission components and equipment.  AGMA was founded in 1916; as of December 30, 2016, there were 456 member companies listed on the association's website.

AGMA is accredited by the American National Standards Institute (ANSI) to write all U.S. standards on gearing, including terminology, nominal dimensions, tolerances, and tools for manufacturing and control. In 1993, AGMA became the Secretariat for Technical Committee 60 (TC 60) of ISO. TC 60 is the committee responsible for developing all international gearing standards. In addition to the position of Secretariat, AGMA also chairs one-third of the active ISO Working Groups related to gearing.

AGMA hosts the industry's trade show, Gear Expo, every two years. Gear Expo is the only trade show dedicated to the complete gear manufacturing process.

The AGMA Fall Technical Meeting provides paper presentations on the latest applied technical research in the gear and power transmission industry. The FTM is held annually at a different location in the United States each year. It is often held in conjunction with the Gear Expo.

References

External links 
 AGMA website
 GEARexpo 

Gears
Professional associations based in the United States
Organizations established in 1916
Mail (Unix). mail is a command-line email client for Unix and Unix-like operating systems.

History
"Electronic mail was there from the start", Douglas McIlroy writes in his article "A Research UNIX Reader: Annotated Excerpts from the Programmer’s Manual, 1971-1986", and so a  command was included in the first released version of research Unix, First Edition Unix.
This version of mail was capable to send (append) messages to the mailboxes of other users on the Unix system, and it helped managing (reading) the mailbox of the current user.

In 1978 Kurt Shoens wrote a completely new version of mail for BSD2, referred to as Berkeley Mail. Although initially installed at , (with the earlier Unix mail still available at ), on most modern Unix and Linux systems the commands ,  and/or  all invoke a descendant of this Berkeley Mail, which much later was the base for the standardization of a mail program by the OpenGroup, the POSIX standardized variant mailx.

See also
Cleancode email
mailx

References

External links
 at GNU Mailutils manual
S-nail manual

Unix Internet software
Dynamical Theory of Crystal Lattices. Dynamical Theory of Crystal Lattices is a book in solid state physics, authored collaboratively by Max Born and Kun Huang. The book was originally started by Born in c. 1940, and was finished in the 1950s by Huang in consultation with Born. The text is considered a classical treatise on the subject of lattice dynamics, phonon theory, and elasticity in crystalline solids, but excluding metals and other complex solids with order/disorder phenomena. J. D. Eshelby, Melvin Lax, and A. J. C. Wilson reviewed the book in 1955, among several others.

See also 
 Bibliography of Max Born
 Introduction to Solid State Physics

References

External links 
 

1954 non-fiction books
Physics textbooks
Max Born
Question (short story). "Question" is a science fiction short story by American writer Isaac Asimov. The story first appeared in the March 1955 issue of Computers and Automation (thought to be the first computer magazine), and was reprinted in the April 30, 1957, issue of Science World. It is the first of a loosely connected series of stories concerning a fictional supercomputer called Multivac.

The story concerns two technicians who are servicing Multivac, and their argument over whether or not the machine is truly intelligent and able to think. Multivac, however, supplies the answer on its own.

After the reprint, another author, Robert Sherman Townes, noticed the climax in the last sentence was very similar to one of his own stories, "Problem for Emmy" (Startling Stories, June 1952), and wrote to Asimov about it. After searching in his library, Asimov did find the original story and, although he did not recall having read it, admitted that the endings were pretty similar. He then replied to Townes, apologizing and promising the story would never again be published, and it never was. Asimov mentioned "Question" in an editorial called "Plagiarism" which appeared in the August 1985 issue of Asimov's Science Fiction (although he did not mention Townes' name or the title of either story). "Plagiarism" was reprinted in Asimov's collection Gold (1995).

Sources
 "Question" at AsimovReviews.net

External links 
 
 "Question" at the Internet Archive

Multivac short stories by Isaac Asimov
1955 short stories
American short stories
Science fiction short stories
Works originally published in American magazines
Works originally published in science and technology magazines
Jokester. "Jokester" is a science fiction short story by American writer Isaac Asimov. It first appeared in the December 1956 issue of Infinity Science Fiction, and was reprinted in the collections Earth Is Room Enough (1957) and Robot Dreams (1986). It is one of a loosely connected series of stories concerning a fictional computer called Multivac.

Plot summary
Noel Meyerhof is a "Grand Master", one of a small cadre of Earth's recognised geniuses, who has the insight to know what questions to ask Multivac. But a computer scientist is concerned that Meyerhof is acting erratically. As a known joke-teller, he has been discovered feeding jokes and riddles into Multivac.

By computer analysis, the characters in the story investigate the origin of humour, particularly why there seems to be no such thing as an original joke, except for puns. Every normal joke is something that was originally heard from someone else.

The computer eventually tells them that humour is actually a psychological study tool imposed on the human race by extraterrestrials studying mankind, similarly to how humans study mice. They needed to isolate the responses to their jokes from original ones, so they "programmed" us to react differently to puns.

The characters of the story conjecture that figuring this fact out makes humour useless as a tool, so the aliens will cease using it... And suddenly  the characters of the story feel that they cannot recall any joke.

Adaptations

The story was adapted as a 30 minute broadcast, read by Henry Goodman, in 2006 by BBC 7 (now BBC Radio 4 Extra).

Citations

External links 
 

Multivac short stories by Isaac Asimov
1956 short stories
Works originally published in Infinity Science Fiction
The Machine That Won the War (short story). "The Machine That Won the War" is a science fiction short story by American writer Isaac Asimov. The story first appeared in the October 1961 issue of The Magazine of Fantasy & Science Fiction, and was reprinted in the collections Nightfall and Other Stories (1969) and Robot Dreams (1986). It was also printed in a contemporary edition of Reader's Digest, illustrated. It is one of a loosely connected series of such stories concerning a fictional supercomputer called Multivac.

Plot summary
Three influential leaders of the human race meet in the aftermath of a successful war against the Denebians. Discussing how the vast and powerful Multivac computer was a decisive factor in the war, each of the men admits that in fact, he falsified his part of the decision process because he felt that the situation was too complex to follow normal procedures.

John Henderson, Multivac's Chief Programmer, admits that he altered the data being fed to Multivac, since the populace could not be trusted to report accurate information in the current situation.

Max Jablonski then admits that he altered the data that Multivac produced, since he knew that Multivac was not in good working order due to manpower and spare parts shortage.

Finally, Lamar Swift, executive director of the Solar Federation, reveals that he had not trusted the reports produced by Multivac, and had made the final decisions purely on the toss of a coin.

References

External links 
 
 The Machine That Won the War first edition title listing in WorldCat database
 The Machine That Won the War at the Internet Archive's OpenLibrary

Fiction set around Deneb
Machine That Won the War, The
1961 short stories
Works originally published in The Magazine of Fantasy & Science Fiction
Fiction about artificial intelligence
Point of View (short story). "Point of View" is a short story by American writer Isaac Asimov that first appeared in Boys' Life magazine in July 1975. Due to the poor reception it received, it was only reprinted in the collection The Complete Robot in 1982. It is one of a loosely connected series of such stories concerning a fictional computer called Multivac.

Plot summary
Roger's father works with a supercomputer called a Multivac, which has been malfunctioning lately as it comes up with different solutions each time to problems it is asked to solve. After coworkers tell him to take a break, he takes Roger out to lunch. His father tells him what he thinks is wrong with the Multivac, and then from this Roger decides that it is like a child, and like one needs a break from work, saying that if you made a kid do work all day than it would get stuff wrong on purpose. His father reassure this inference with Roger, who confirms it saying, "Dad, a kid's got to play too."

External links

References

Multivac short stories by Isaac Asimov
1975 short stories
Works originally published in Boys' Life
Phorum. Phorum is an open-source message board system written in PHP.

History
In April 1998, Brian Moon developed the initial scripts that would meet the basic forum needs of Dealmac, a small part time web based enterprise Moon was working on in his spare time with a number of others.  With 30 days of testing, the code was prepared enough to put into production. It was named WebThreads, though this name was later found to collide with another, similar product. The name Phorum came from combining "PHP" and "forum". It was released under the GPL, though it would later be changed to the Phorum license, a BSD style license.

As Dealmac grew, the demands for the software grew. Moon had already begun writing Phorum 2.0.  However, upon a review of the code, 2.0 was clearly not able to scale to Dealmac's needs.  Dealmac hiring Moon to create what would become Phorum 3.0. The site owners were very open to open source. Initially, Phorum 3 was developed primarily by Moon with some help from Jason Birch of Bar-None Drinks.  Moon announced the release of Phorum 3.0 on 28 July 1999 using version 3 of PHP and supporting both a MySQL and PostgresSQL backend databases.

In 2000, Dan Langille joined the Phorum team and has concentrated on maintaining the PostgreSQL code.

In 2001, Thomas Seifert of MySnip.de came on board, contributing an internal user system in Phorum.  Previously, Phorum had relied on external user systems for user management.

Version 4 was never realized due to several problems with the direction of the code.  Moon and Seifert instead started version 5, which was focused on speed and extensibility. This release made the product comparable to other offerings.

In September 2005, Maurice Makaay of Gitaar.net joined the Phorum team, contributing an easier to use message posting system and code for improving the Phorum module system. The Phorum module system provides a very flexible solution for implementing extra features and a lot of new features have been implemented as easy to install and use modules.  The first production release of Phorum 5, version 5.0.9, was made in September 2004.

Latest release

Phorum 5.2 was announced as stable in January 2008 after two years of development.   it is the latest minor release.    Key enhancements introduced with 5.2 included a new template which is totally based on XHTML and the addition of a publicly documented API for allowing other applications to integrate with Phorum.

Adoption 

Phorum at one point in the 2000s was used to provide such websites MySQL forums.  Sheffield Hallam university School of Mathematics attempted to use a web-based discussion forum for student communication but utilization proved poor in practice and e-mail based lists were found to be more productive.

Further reading

See also 

 Comparison of Internet forum software

References

External links
 

Free groupware
PHP software
Free Internet forum software
Wavelength shifter. A wavelength shifter is a photofluorescent material that absorbs higher frequency photons and emits lower frequency photons. The material absorbs one photon, and emits one or multiple lower-energy photons. The relaxation time of the excited molecule is usually in the order of nanoseconds.

Applications
Wavelength shifters are often used in particle physics to collect scintillation or Cherenkov light in particle detectors. Materials, such as acrylic slaps or optical fibers, are typically either doped with wavelength-shifting molecules or coated with wavelength-shifting paint.

Wavelength-shifting technology is of particular interest for low-background supernova neutrino detectors such as IceCube, Super-Kamiokande or its successor Hyper-Kamiokande. Here, wavelength shifters offer two advantages: As these types of detectors are based on the emission of Cherenkov radiation from secondary particles traveling faster than the phase velocity of light in the medium from the neutrino interaction, absorbing more photons in the UV range and shifting them to the visible range detectable by conventional PMTs is beneficial. In addition, with wavelength shifters larger collection areas can be covered price-efficiently as compared to standard PMT-based sensors. An example of a sensor making use of wavelength-shifting technology is the Wavelength-shifting Optical Module (WOM)  envisaged for an extension of the IceCube detector.

Furthermore, wavelength shifting materials can be used to increase the efficiency of a photovoltaic cell (solar cell) by changing one "too-high" energy photon into multiple "just-right" energy photons.

Besides the scientific application, wavelength shifters are sometimes used to achieve UV resistance of plastics instead of absorbers. Wavelength shifter are also used to shift UV light to the visible spectrum in Fluorescent lamps or LEDs, in most cases this is done with a Phosphor that can be considered a wavelength shifter with a long (ms) relaxation time.

Chemical structure
Organic wavelength shifters usually contain one or more benzene-ring(s) (e.g. :de:1,4-Bis(2-methylstyryl)benzol or p-Terphenyl) since the  and  bonds here are useful in the absorption/emission of the photon and the energy transport within the molecule. Modifications of the molecules allow in some cases the tuning of the acceptance and emission wavelength regime. The wavelength shift occurs due to the Franck–Condon principle, while excess energy is usually carried away in form of phonons.

Most organic wavelength shifters are planar molecules, causing a decrease in wavelength shifting efficiency when crystallized due to energy exchange between the molecules. Current research has also created 3 dimensional wavelength shifters that show the opposite effect since clustering together limits the energy that can be stored as rotational energy.

Spectral characteristics
Wavelength shifter usually have many absorption and emission lines that are broad enough to create an absorption and emission spectrum. The separation between absorption and emission spectrum is defined by the so-called Stokes shift.

References

Phosphors and scintillators