omniomni/omni-engineering huggingface dataset:
PL/pgSQL. PL/pgSQL (Procedural Language/PostgreSQL) is a procedural programming language supported by the PostgreSQL ORDBMS.  It closely resembles Oracle's PL/SQL language. Implemented by Jan Wieck, PL/pgSQL first appeared with PostgreSQL 6.4, released on October 30, 1998. Version 9 also implements some ISO SQL/PSM features, like overloading of SQL-invoked functions and procedures.

PL/pgSQL, as a fully featured programming language, allows much more procedural control than SQL, including the ability to use loops and other control structures. SQL statements and triggers can call functions created in the PL/pgSQL language.

The design of PL/pgSQL aimed to allow PostgreSQL users to perform more complex operations and computations than SQL, while providing ease of use. The language is able to be defined as trusted by the server.

PL/pgSQL is one of the programming languages included in the standard PostgreSQL distribution, the others being PL/Tcl, PL/Perl and PL/Python. In addition, many others are available from third parties, including PL/Java, PL/pgPSM, PL/php, PL/R,  PL/Ruby, 
PL/sh, 
 PL/Lua, Postmodern (based on Common Lisp) and PL/v8.  PostgreSQL uses Bison as its parser,
making it easy to port many open-source languages, as well as to reuse code.

Comparing with PSM 
The SQL/PSM language is specified by an ISO standard, but is also inspired by Oracle's PL/SQL and PL/pgPL/SQL, so there are few differences.  The PL/pgPSM contributed module implements the standard.  The main features of PSM that differ from PL/pgSQL:

 Exception handlers are subroutines (continue handlers);
 Warnings can be handled like an exception; 
 Declaration of variables should be based on SQL query result.

All three languages (Oracle PL/SQL, PostgreSQL PL/pgSQL and ISO SQL/PSM) are originally descended from the Ada programming language.

Example 
CREATE FUNCTION sales_tax(subtotal real) RETURNS real AS $$
BEGIN
    RETURN subtotal * 0.06;
END;
$$ LANGUAGE plpgsql;

Inline documentation external support 

Formal pseudo-language for documentation can be embedded in SQL and PL/pgSQL scripts. This documentation is then processed by a documentation generator—an external tool  which extracts data and generates hypertext. Since PL/SQL: supports some of these tools, PL/pgSQL is expected to provide full or partial support as well.
  

Other documentation tools: Doxygen, DBScribe, HyperSQL, Universal Report.

References

External links
Official PL/pgSQL documentation

SQL
PostgreSQL
Data-centric programming languages
Entropic explosion. An entropic explosion is an explosion in which the reactants undergo a large change in volume without releasing a large amount of heat. The chemical decomposition of triacetone triperoxide (TATP) may be an example of an entropic explosion. It is not a thermochemically highly favored event because little energy is generated in chemical bond formation in reaction products, but rather involves an entropy burst, which is the result of formation of one ozone and three acetone gas phase molecules from every molecule of TATP in the solid state.

This hypothesis has been questioned as opposing to other theoretical investigations as well as actual measurements of the detonation heat of TATP. Experiments have shown that the explosion heat of TATP is about 2800 kJ/kg (about 70% of TNT) and that it acts as a usual explosive, producing a mix of hydrocarbons, water and carbon oxides upon detonation.

The authors of the 2005 Dubnikova et al. study confirm that a final redox reaction (combustion) of ozone, oxygen and reactive species into water, various oxides and hydrocarbons takes place within about 180 ps after the initial reaction - within about a micron of the detonation wave. Crystals of TATP ultimately reach a temperature of 2300 K and pressure of 80 kbar.

References

Chemical reactions
Thermodynamic entropy
Explosions
UNIX/32V. UNIX/32V is an early version of the Unix operating system from Bell Laboratories, released in June 1979.  32V was a direct port of the Seventh Edition Unix to the DEC VAX architecture.

Overview

Before 32V, Unix had primarily run on DEC PDP-11 computers. The Bell Labs group that developed the operating system was dissatisfied with DEC, so its members refused DEC's offer to buy a VAX when the machine was announced in 1977. They had already begun a Unix port to the Interdata 8/32 instead. DEC then approached a different Bell Labs group in Holmdel, New Jersey, which accepted the offer and started work on what was to become 32V.

Performed by Tom London and John F. Reiser, porting Unix was made possible due to work done between the Sixth and Seventh Editions of the operating system to decouple it from its "native" PDP-11 environment. The 32V team first ported the C compiler (Johnson's pcc), adapting an assembler and loader written for the Interdata 8/32 version of Unix to the VAX. They then ported the April 15, 1978 version of Unix, finding in the process that "[t]he (Bourne) shell [...] required by far the largest conversion effort of any supposedly portable program, for the simple reason that it is not portable."

UNIX/32V was released without virtual memory paging, retaining only the swapping architecture of Seventh Edition.  A virtual memory system was added at Berkeley by Bill Joy and Özalp Babaoğlu in order to support Franz Lisp; this was released to other Unix licensees as the Third Berkeley Software Distribution (3BSD) in 1979. Thanks to the popularity of the two systems' successors, 4BSD and UNIX System V, UNIX/32V is an antecedent of nearly all modern Unix systems.

See also
 Ancient UNIX

References

Further reading
 Marshall Kirk McKusick and George V. Neville-Neil, The Design and Implementation of the FreeBSD Operating System (Boston: Addison-Wesley, 2004), , pp. 4–6.

External links
The Unix Heritage Society, (TUHS) a website dedicated to the preservation and maintenance of historical UNIX systems
Complete distribution of 32V with source code
Source code of the 32V kernel
Installation instructions and download for SimH
Information about running UNIX/32V in SIMH

Bell Labs Unices
Discontinued operating systems
1979 software
Constantin Sotiropoulos. Constantin Sotiropoulos is the co-creator (with François Lionet) of AMOS BASIC, a popular video game and multimedia programming language for the Amiga computer, and STOS BASIC on the Atari ST.
He has also been creator of copy protection software for some French companies.

Before joining the 16-bit scene, he also developed Speedy Wonder (BASIC compiler) on the Amstrad and Thomson 8-bit micro-computers, released by French company Minipuce, and ML1, a macro-assembler for the same machines (released by Micro-Application). Both software were co-developed with Youri Beltchenko.

References

French computer programmers
Living people
Year of birth missing (living people)
Place of birth missing (living people)
Alvand-class frigate. The Alvand class () or Saam class () was originally a class of four frigates built for the Imperial Iranian Navy. They were renamed after the Iranian Revolution, and served in the Islamic Republic of Iran Navy during Iran-Iraq War. Three still remain in service. A fourth was sunk by the U.S. Navy in 1988.

Development and construction

The ships were built in the United Kingdom by Vosper Ltd and based on their Mark 5 design with the following arms & equipment:

ASuW – 1 × quintuple Sea Killer Mk2 surface-to-surface missile
AAW – 1 × triple Sea Cat surface-to-air missile launcher
ASW – 1 × 3 barrelled Anti Submarine Mortar Mark 10 Limbo launcher
Guns – 1 × Mark 8 Mod 0 4.5 inch general purpose & 1 × twin 35mm Oerlikon AA
Electronics – Plessey AWS 1 air surveillance radar with on-mounted IFF; 2 × Contraves Seahunter systems (For use with Sea cat, Sea Killer & the 35mm mount); Decca RDL 1 passive direction finding equipment

They were refitted in the UK shortly before the 1979 Iranian Revolution.

History
The ships were originally named after characters from Ferdowsi's Shahnameh. After the Islamic Revolution they were renamed after mountains in Iran.

They saw action during the "Tanker War" phase of the Iran–Iraq War and proved effective against Iraqi forces. After one was sunk, and other significant losses taken, during Operation Praying Mantis they saw little further use as the Iranian Navy proved no match for the U.S. Navy.

Upgrades

The Sea Killer missiles were replaced by Chinese made C-802s in the 1990s. The Sea Cats were replaced by the addition of a  AA gun.

Two triple  torpedo tubes, two  mortars and two 0.50 caliber machine guns were also fitted.

Successors
The  is a modified Iranian-built version of the Alvand class, with five either in service or under construction.

Ships in the class

See also
 Islamic Republic of Iran Navy
 Current Iranian Navy vessels

References

Sources 
https://web.archive.org/web/20160303224923/http://www.iinavy.org/faramarz.htm
http://www.mafhoum.com/press8/237P2.pdf
https://web.archive.org/web/20041222105239/http://www.ii.uj.edu.pl/~artur/enc/F2.htm

External links

Photos of Alvand-class frigates in Operation Praying Mantis

Frigate classes
 
Iran–United Kingdom military relations
Ship classes of the Islamic Republic of Iran Navy
Claw hammer. A claw hammer is a hammer primarily used in carpentry for driving nails into or pulling them from wood. Historically, a claw hammer has been associated with woodworking, but is also used in general applications.  It is not suitable for heavy hammering on metal surfaces (such as in machining work), as the steel of its head is somewhat brittle; the ball-peen hammer is more suitable for such metalwork.

An early claw hammer is seen in Albrecht Dürer's etching "Melencolia I," dated 1514, halfway up the left side. There are several nails in the lower right corner.

Design 
A claw hammer is composed of a metal head and a handle, which historically was made of wood but also may be of steel, fiberglass, or other composite. One side of the head has a poll with either a smooth or textured surface and used for driving, while the other is formed into a pair of downward curving V-shaped claws and used for most commonly  extracting nails from wood. The greater the curve of the claw(s), and longer the handle, the greater the leverage that may be applied.

Types 

Claw hammers can be constructed many ways but generally come in one of two forms. The first, and most popular, type of hammer is the two-piece hammer. This hammer is constructed from a forged steel head with a hole for fixing a handle. One end is made to fit the hole in the hammer head, then a steel wedge is driven into the wood which forces it to expand and secure the hammer head to the handle.  Other handle materials include glass fiber and even carbon fiber. 

Another type of claw hammer is single-piece forged heat-treated steel where the head and handle are integral.  These hammers often have polymer grips to add to their ergonomics and decrease vibrations when the hammer is used. 

Another type of claw hammer is the framing hammer. This is an oversized claw hammer used in framing carpentry. The larger and heavier head can decrease the number of blows required to fully drive a nail, minimized further by increased leverage (torque) and head speed generated by longer handles.  Framing hammers also characteristically have a checkered "milled" face, which reduces skip-off of the head if the blow is not precisely struck on the nail.  The slight indentations left on the wood by the checkered face are considered unimportant in rough carpentry.  Framing hammers also have a much straighter claw than regular claw hammers, as the claw is designed more for prying nailed  boards apart, rather than removing nails (though its claw can also be used in that capacity).

The size of this type of hammer is commonly designated by the weight of its head, which may range from .

References

Bibliography
Hazra Choudhary, A text book on workshop technology

Hammers
Woodworking hand tools
NetWare File System. In computing, the NetWare File System (NWFS) was a file system based on a heavily optimized, journal-based FAT file system. It was used in the Novell NetWare network operating system. It was the only file system for all volumes in NetWare versions 2.x, 3.x and 4.x, and the default and only file system for the SYS: volume continuing through version 5.x. Novell developed two varieties of NWFS:

 16-bit NWFS 286, used in NetWare 2.x
 32-bit NWFS 386, used in NetWare 3.x through NetWare 6.x.

In NetWare 5 and above, Novell Storage Services (NSS, released in 1998), superseded the NWFS format.

The NWFS on-disk format was never publicly released by Novell, but it was released by former Novell engineers as an open source project on Windows, Linux, and DOS in 2000.  The project  contains a complete rewrite of the NetWare File System, publishes all of the file system internals, and is hosted on GitHub and GitLab.

The published specifications for 32-bit NWFS are:
 Maximum file size: 4 GB
 Maximum volume size: 1 TB
 Maximum files per volume: 2 million when using a single name space.
 Maximum files per server: 16 million
 Maximum directory entries: 16 million
 Maximum volumes per server: 64
 Maximum volumes per partition: 8
 Maximum open files per server: 100,000
 Maximum directory tree depth: 100 levels
 Characters used: ASCII double-byte
 Maximum extended attributes: 512
 Maximum data streams: 10
 Support for different name spaces: Microsoft Windows Long names (a.k.a. OS/2 namespace), Unix, Apple Macintosh
 Support for restoring deleted files (salvage)
 Support for journaling (Novell Transaction Tracking System a.k.a. TTS)
 Support for block suballocation, starting in NetWare 4.x

For larger files, the file system utilized a performance feature named Turbo FAT.

Transparent file compression was also supported, although this had a significant impact on the performance of file serving.

Every name space requires its own separate directory entry for each file. While the maximum number of directory entries is 16,000,000, two resident name spaces would reduce the usable maximum number of directory entries to 8,000,000, and three to 5,333,333.

16-bit NWFS could handle volumes of up to 256 MB. However, its only name-space support was a dedicated API to handle Macintosh clients.

The Netware File System supported native RAID 0 and RAID 1 capabilities long before RAID systems came into use on personal computers.  Disk mirroring and duplexing were basic features of the file system, and NWFS also supported multi-segmented volumes, and round-robin reads, much like RAID 0 and RAID 1 does today.

See also 

 List of file systems
 Comparison of file systems
 Transaction-Safe FAT File System

References

External links 
 Using the Transaction Tracking System

Compression file systems
Disk file systems
Network file systems
Novell NetWare
Ken Kalish. Kenneth Kalish is a game programmer who wrote TRS-80 Color Computer and Dragon 32/64 home computers in the 1980s. In the United Kingdom, most of Kalish's games were published by Microdeal.

Games
 Danger Ranger
 Dungeon Raid
 El Diablero
 Monkey Kong
 Phantom Slayer
 Devil Assault

References

External links
An Interview with Ken Kalish  by L. Curtis Boyle

Year of birth missing (living people)
Video game programmers
TRS-80 Color Computer
Living people
Place of birth missing (living people)
David Grant (engineer). Sir David Grant  FLSW (born 12 September 1947) is a British academic who was the vice-chancellor of Cardiff University in Wales from 2001 to 2012. Following his appointment, Grant oversaw the merger between Cardiff University and the University of Wales College of Medicine, which was completed in 2004, and the award of university status to Cardiff.

He gained his PhD in engineering science from Durham University in 1974.  Prior to his appointment at Cardiff University, Grant worked for the Dowty Group and then became director of technology at the General Electric Company (1991–2001).  He was awarded the Mensforth International Gold Medal by the Institution of Electrical Engineers in 1996.

He became a Fellow of the Royal Academy of Engineering in 1997, and was a vice-president from 2007 to 2012.  He is also a former council member of the Engineering and Physical Sciences Research Council, and was a governing board member of Innovate UK (formerly the Technology Strategy Board).  He served on the board of the Defence Science and Technology Laboratory from 2012 to 2018, and was chair of the Science, Technology, Engineering and Mathematics Network until 2018.

Grant is a non-executive director of Renishaw plc and of IQE, and chair of the National Physical Laboratory.

He was elected an Honorary Fellow of Wolfson College, Cambridge in 2000.

He was elected a Fellow of the Learned Society of Wales in 2018.

Grant was appointed a Commander of the Order of the British Empire in 1997 for his contribution to the UK Foresight Programme, and was knighted in the 2016 Birthday Honours for services to engineering, technology, and skills.

References

1947 births
Living people
People associated with Cardiff University
Fellows of the Royal Academy of Engineering
Fellows of Wolfson College, Cambridge
Commanders of the Order of the British Empire
Fellows of Jesus College, Oxford
Knights Bachelor
Alumni of Durham University Graduate Society
Scientists of the National Physical Laboratory (United Kingdom)

Fellows of the Learned Society of Wales
Monoski. A monoski is a single wide ski used for skiing on snow.  The same boots, bindings, and poles are used as in alpine skiing. Unlike in snowboarding, both feet face forward, rather than sideways to the direction of travel. Similar equipment includes the skwal and the teleboard, with feet in tandem formation (one ahead of the other).

Monoskiing was invented in the late 1950s by Dennis Phillips at Hyak, Washington using a single water ski and bear trap bindings. Surfer Mike Doyle promoted the monoski in the early 1970s, after which monoskiing's relative popularity slowly increased, but the interest eventually waned in favor of snowboarding.

Recently the popularity of monoskiing has increased, particularly in France and in the United States largely due to technological advances in the design of the ski. As with alpine skis the carved shape of the ski has meant easier turns, and as a result, skiers are finding the transition to monoskis less daunting.

Festivals 
Fans of monoskiing arrange festivals during the season to try out new skis and compete in various competitions. 
 In France one of the most popular is the "Mondial de Monoski"
 Also in France is the tongue-in-cheek 1980's themed "Monoski World Championships" held each April in Val d'Isere.
 In the United States this is the "Monopalooza"
 In Colorado, United States this is the "Cinco de Mono"

References

External links
 Association Française de Monoski – one ski, more pleasure is the French monoski association. It is the biggest community and organizer of the Mondial de Monoski
 Monoski.net  is a US-based site with information and reviews for everyone provided by the US Monoskiers
 Plesk Domain Default page  is a British site that aims to inform and promote monoskiing to the UK and provides new and used monoskis to buy
 RVM – RealVikingsMonoSki  is a Swedish site with monoski information, photos and videos

Skiing equipment
Sliding vehicles
TCB. TCB may refer to:

Companies and organizations
 Taiwan Cooperative Bank, a bank of Taiwan
 The Conference Board, a non-profit business membership and research group organization in New York City
 Touring Club Belgium, a motoring organization in Belgium
 Transportes Charter do Brasil, a cargo airline in São Paulo, Brazil

Computing
 Task Control Block, an instance of a process control block within IBM OS/360 and successor systems
 Thread control block, a data structure in the operating system kernel 
 Trusted computing base, a set of computer components critical to its security
 Temenos Core Banking, banking software from Temenos Group
 Transmission Control Block, a data structure used by a Transmission Control Protocol stack

Music
 TCB (album), James Reyne's album of Elvis Presley cover songs
 TCB (band), an early 1970s Canadian rock group
 TCB Band, rhythm section of Elvis Presley's band

Science
 TCB-2, a hallucinogenic phenethylamine compound
 Trichlorobenzene, an organic chemical
 Temps-Coordonnée Barycentrique (Barycentric Coordinate Time), a coordinate time standard in astronomy
 TCB meter (transcutaneous bilirubin meter), a device which measures bilirubin level

Other
 TCB (TV program), 1968 Motown television special and album
 TCB, IATA code for Treasure Cay Airport in The Bahamas
 TCB, NYSE symbol for TCF Financial Corporation
 TCB, Ordnance Survey map code for a telephone call box
 TCB spline ("tension, continuity, and bias"), in mathematics, another term for a Kochanek–Bartels spline
 Telecommunication Certification Body, compliance agency re Federal Communications Commission (FCC) rules and regulations
 Track circuit block, name used in the United Kingdom for automatic block signalling on railways

See also
 Taking Care of Business (disambiguation)
 Telephone Company Building (disambiguation)
Fly by wire. Fly by wire, Fly-by-wire or Fly by Wire may refer to:

 Fly-by-wire (FBW), electronic flight control system
 Fly by Wire (album), an album by Someone Still Loves You Boris Yeltsin
 Fly by Wire (book), a book about US Airways Flight 1549

See also 
 Drive by wire
 Power by wire
 Fly by light
 Fly by optics
 Fly wire (disambiguation)
Ethyl tert-butyl ether. Ethyl tertiary-butyl ether (ETBE), also known as ethyl tert-butyl ether, is commonly used as an oxygenate gasoline additive in the production of gasoline from crude oil.  ETBE offers equal or greater air quality benefits than ethanol, while being technically and logistically less challenging. Unlike ethanol, ETBE does not induce evaporation of gasoline, which is one of the causes of smog, and does not absorb moisture from the atmosphere.

Production 
Ethyl tert-butyl ether is manufactured industrially by the acidic etherification of isobutylene with ethanol at a temperature of 30–110 °C and a pressure of 0,8–1,3 MPa. The reaction is carried out with an acidic ion-exchange resin as a catalyst.

Suitable reactors are fixed-bed reactors such as tube bundle or circulation reactors in which the reflux can be cooled optionally.

Ethanol, produced by fermentation and distillation, is more expensive than methanol, which is derived from natural gas. Therefore, MTBE, made from methanol is cheaper than ETBE, made from ethanol.

See also 
Methyl tert-butyl ether (MTBE) 
tert-Amyl methyl ether (TAME) 
Tetraethyllead (TEL)
List of gasoline additives

References

External links
 EC Joint Research Centre ETBE risk assessment report
 Directive 98/70/EC of the European Parliament and of the Council of 13 October 1998 relating to the quality of petrol and diesel fuels and amending Council Directive 93/12/EEC
 An assessment of the impact of ethanol-blended petrol on the total NMVOC emission from road transport in selected countries

Commodity chemicals
Dialkyl ethers
Ether solvents
Oxygenates
Pollutants
Tert-butyl compounds
Radial stress. Radial stress is stress toward or away from the central axis of a component.

Pressure vessels
The walls of pressure vessels generally undergo triaxial loading. For cylindrical pressure vessels, the normal loads on a wall element are longitudinal stress, circumferential (hoop) stress and radial stress.

The radial stress for a thick-walled cylinder is equal and opposite to the gauge pressure on the inside surface, and zero on the outside surface. The circumferential stress and longitudinal stresses are usually much larger for pressure vessels, and so for thin-walled instances, radial stress is usually neglected.

Formula
The radial stress for a thick walled pipe at a point  from the central axis is given by

 
where  is the inner radius,  is the outer radius,  is the inner absolute pressure and  is the outer absolute pressure.  Maximum radial stress occurs when  (at the inside surface) and is equal to gauge pressure, or .

References

Solid mechanics