omniomni/omni-engineering huggingface dataset:
Project Stealth Fighter. Project Stealth Fighter is a combat flight simulator released for the Commodore 64 in 1987 by MicroProse, featuring a fictional United States military aircraft. During the time of the game's release, there was heavy speculation surrounding a missing aircraft in the United States Air Force's numbering system, the F-19. Project Stealth Fighter was later renamed F-19 Stealth Fighter and was remade in 1988 for the 16-bit systems with much improved graphics.

Gameplay

In the game, the player take on the role of a fictional fighter pilot flying missions of varying difficulty over four geographic locations: Libya, the Persian Gulf, the North Cape, and Central Europe.

Reception

The game was critically acclaimed. Computer Gaming World in 1987 stated that Project Stealth Fighter pushed the limits of 8-bit hardware (noting the resulting great difficulty in landing at airfields) but concluded favorably: "Timely? It couldn't be more so. Realistic? Yes ... Challenging? Definitely!" In a 1994 survey of wargames the magazine gave the title two stars out of five, stating that F-19 and F-117 had superseded it. Compute! in 1988 called the game "a superlative flight simulator". It praised the graphics, stating that they improved on those of the company's F-15 Strike Eagle. The magazine concluded: "If you're to have only one flight simulator in your library, let it be this one ... Project: Stealth Fighter is Microprose's best". The Commodore 64 version's review in Zzap!64 said that the "Project Stealth Fighter is excellent, and sets new standards to which other must now aspire". ACE stated the game as certainly enjoyable and the rating for C64 version is 863 out of 1000.

Project: Stealth Fighter was awarded the Origins Award for "Best Military or Strategy Computer Game of 1987".

The game was nominated for the Golden Joystick Awards '88 in the category "Best Simulation - 8 Bit".

A port to the ZX Spectrum version was first advertised in 1988 prior to the game being renamed for the 16-bit releases. By the time it was published late 1989, it used the F-19 Stealth Fighter title in-game but was still packaged as Project Stealth Fighter. A review in Your Sinclair called it "the best Speccy flight sim to date".

Both the Spectrum and Commodore 64 versions were subsequently reissued as F-19 Stealth Fighter in the same packaging as the 16-bit versions.

In late 1990, the combined sales of F-19 Stealth Fighter across four platforms took the game into the UK Top 20 All Format games chart.

References

External links
 
 
 
 Project Stealth Fighter Manual on Steam

1987 video games
Cold War video games
Commodore 64 games
Flight simulation video games
MicroProse games
Origins Award winners
Single-player video games
Video games developed in the United States
Video games set in East Germany
Video games set in Iran
Video games set in Libya
Video games set in the Soviet Union
ZX Spectrum games
Thomas Brown (engineer). Thomas Brown (1772 – 30 January 1850) was an English surveyor, civil engineer, businessman and landowner.

Thomas Brown was born in 1772 in Mowhole, Disley in Cheshire, where his father owned 11 acres of land. He is believed to have apprenticed to engineer and industrialist Benjamin Outram. Brown had interests in coal-mining, particularly in the Haughton and Hyde areas of Greater Manchester, as well as lime burning and mineral extraction interests. He owned land at Disley, Manchester and Heaton Norris and he lived at Ardwick Green, Manchester.

He is known as the resident engineer for the construction of the Peak Forest Canal and the Peak Forest Tramway and in 1793 he made the initial survey of their routes. Following the resignation of Benjamin Outram in 1801 he was appointed as consulting engineer for the completion of the Marple canal locks. He was also the surveyor for the Ashton Canal and the resident engineer for the construction of the Macclesfield Canal.

Brown married Elizabeth Hancock, the daughter of his partner in his coal and lime business. Together they had 3 children.

By 1841, he was living in Allerton Place at 16 Ardwick Green. He died there on 30 January 1850, aged 78 years. He was buried at St Mary's Church, Disley.

References

People from Disley
English engineers
1772 births
1850 deaths
Hackworth. Hackworth is a surname. Notable people with the surname include:

Ben Hackworth (born 1977), Australian writer and film director
David Hackworth (1930–2005), United States Army colonel and prominent military journalist
Green Hackworth (1883–1973), American jurist of international law
John Hackworth (born 1970), American soccer coach
John Wesley Hackworth (19th century), inventor of Hackworth valve gear
Thomas Hackworth (died 1877), engineer and brother of Timothy Hackworth
Timothy Hackworth (1786–1850), steam locomotive mechanical engineer
Tony Hackworth (born 1980), English footballer
Travis Hackworth, American politician

See also
Hackworth valve gear, locomotive valve gear
1995 Trans Service Airlift Electra crash. The Trans Service Airlift Lockheed L-188 crash occurred on 18 December 1995 when a Lockheed L-188C Electra owned by Trans Service Airlift crashed near Jamba, Angola, killing 141 of the passengers and crew.

Trans Service Airlift (TSA), was a private company headquartered at Ndjili Airport, Kinshasa. The Electra was one of a number of ageing aircraft operated by TSA. Built in 1959, it was sold to TSA in 1992, after service with other operators.

On the date of the accident, the aircraft was flying a special charter for UNITA. Following the 1993 trade embargo on UNITA there were frequent "sanction busting" flights out of Zaire. TSA was one of the companies cited in connection with these operations. These flights rarely carried weapons (which were typically supplied over ground routes); usual cargoes were personnel, fuels, food, and medical supplies. The Angolan Government later claimed the aircraft was carrying weapons.

The aircraft, with 139 passengers and five crew members, was carrying forty more people than the plane was designed to carry, without taking cargo into account. It crashed two minutes after take-off. Some reports speculate that cargo may have slid to the back of the plane, resulting in a weight imbalance and causing the crash.

Initial reports by Zairean officials stated that the plane crashed near Cahungula, Lunda Norte Province, while transporting diamond miners from Zaire's capital, Kinshasa.

The co-pilot and two passengers survived the initial crash. The accident was the deadliest plane crash in 1995 until the crash of American Airlines Flight 965 two days later. It remains the deadliest ever plane crash in Angola.

See also 
 List of accidents and incidents involving airliners by airline

References 

Aviation accidents and incidents in Angola
Aviation accidents and incidents in 1995
Accidents and incidents involving the Lockheed L-188 Electra
Trans Service Airlift accidents and incidents
1995 in Angola
December 1995 events in Africa
1995 disasters in Angola
Perfect fluid. In physics, a perfect fluid or ideal fluid  is a fluid that can be completely characterized by its rest frame mass density  and isotropic pressure . Usually, "perfect fluid" is reserved for relativistic models and "ideal fluid" for classical inviscid flow. Real fluids are "sticky" and contain (and conduct) heat. Perfect fluids are idealized models in which these possibilities are ignored. Specifically, perfect fluids have no shear stresses, viscosity, or heat conduction. 
A quark–gluon plasma 
and graphene are examples of nearly perfect fluids that could been studied in a laboratory.

D'Alembert paradox 
In classical mechanics, ideal fluids are described by Euler equations. Ideal fluids produce no drag according to d'Alembert's paradox.

Relativistic formulation 

In space-positive metric signature tensor notation, the stress–energy tensor of a perfect fluid can be written in the form
 
where U is the 4-velocity vector field of the fluid and where  is the metric tensor of Minkowski spacetime.

In time-positive metric signature tensor notation, the stress–energy tensor of a perfect fluid can be written in the form
 
where  is the 4-velocity of the fluid and where  is the metric tensor of Minkowski spacetime.

This takes on a particularly simple form in the rest frame
 
where  is the energy density and  is the pressure of the fluid.

Perfect fluids admit a Lagrangian formulation, which allows the techniques used in field theory, in particular, quantization, to be applied to fluids. 

Perfect fluids are used in general relativity to model idealized distributions of matter, such as the interior of a star or an isotropic universe. In the latter case, the equation of state of the perfect fluid may be used in Friedmann–Lemaître–Robertson–Walker equations to describe the evolution of the universe.

In general relativity, the expression for the stress–energy tensor of a perfect fluid is written as
 
where  is the 4-velocity vector field of the fluid and where  is the inverse metric, written with a space-positive signature.

See also 
 Equation of state
 Ideal gas
 Fluid solutions in general relativity
 Potential flow

References

Further reading 
  ,  (pbk.)
  Topical review.

Fluid mechanics
Superfluidity
Physics
Active rollover protection. An active rollover protection (ARP), is a system that recognizes impending rollover and selectively applies brakes to resist.

ARP builds on electronic stability control and its three chassis control systems already on the vehicle – anti-lock braking system, traction control and yaw control. ARP adds another function: detection of an impending rollover. Excessive lateral force, generated by  excessive speed in a turn, may result in a rollover. ARP automatically responds whenever it detects a potential rollover. ARP rapidly applies the brakes with a high burst of pressure to the appropriate wheels and sometimes decreases the engine torque to interrupt the rollover before it occurs.

Rollovers can also occur when the vehicle is knocked into a stationary object such as a curb. In these so-called "trip events", a vehicle hit from the side but kept from moving laterally by a curb would produce a moment about the center of gravity sufficient to produce a rollover. To counteract this, rollover stability systems have begun to incorporate an active suspension system in rollover protection. To accomplish this, the onboard computer uses data from the inertial measurement unit (IMU) to determine when a vehicle is in a rollover condition independent of yaw rate and vehicle speed. When the computer determines that the vehicle is at risk of rollover, it calculates the direction of roll and activates the active suspension system. The force produced in the suspension creates a moment (torque) opposite to that created by the lateral force, and keeps the vehicle safe.

Other uses

The phrase is also used for active roll over bars for convertible cars, such as the Volkswagen Beetle, which can detect potential roll-over situations and automatically raises rollover bars hidden in the rear head restraints in a fraction of a second.

See also

 Anti-roll bar
 Crosswind stabilization
 Gyroscope
 Roll cage
 Roll over protection structure
 Side Impact Protection System
 WHIPS (Whiplash Protection System)

References

External links
Continental Automotive Systems
SafelyThere – Continental Automotive Systems
Physics of rollover crashes

Vehicle safety technologies
Vehicle braking technologies
Cold inflation pressure. Cold inflation pressure is the inflation pressure of tires as measured before a car is driven and the tires warmed up. Recommended cold inflation pressure is displayed in the owner's manual and on the Tire Information Placard attached to the vehicle door edge, pillar, glovebox door or fuel filler flap. 

Cold inflation pressure is a gauge pressure and not an absolute pressure. 

This article focuses on cold inflation pressures for passenger vehicles and trucks. The general principles are, of course, applicable to bicycle tires, tractor tires, and any other kind of tire with an internal structure that gives it a defined size and shape (as opposed to something that might resemble a very flexible balloon). 

A 2001 NHTSA study found that 40% of passenger cars have at least one tire under-inflated by  or more. The number one cause of tire failure was determined to be under-inflation. Drivers are encouraged to make sure their tires are adequately inflated at all times. 

Under-inflated tires can greatly reduce fuel economy, increase emissions, cause increased wear on the edges of the tread surface, and can lead to overheating and premature failure of the tire. 

Excessive pressure, on the other hand, will lead to impact-breaks, decreased braking performance, and increased wear on the center part of the tread surface. 

Tire pressure is commonly measured in psi in the imperial and US customary systems, bar, which is deprecated but accepted for use with SI, or the kilopascal (kPa), which is an SI unit.

Variation of tire pressure with temperature 

Daily temperature fluctuations can result in appreciable changes in tire pressure. Cold inflation pressure should therefore be measured in the morning, as this is the coldest time of day. This will ensure a tire meets or exceeds the required inflation pressure at any time of day. 

Seasonal temperature fluctuations can also result in appreciable changes in tire pressure, and a tire that is properly inflated in the summer is likely to become underinflated in the winter.  Because of this, it is important to check tire pressures whenever the local seasons change.

Variation of tire pressure with altitude 
Atmospheric pressure will decrease around 0.5 psi for every 1000 feet above sea level. As a vehicle descends from a high altitude location, the absolute pressure inside the tire remains the same, but the atmospheric pressure increases; therefore the gauge pressure will decrease. 

Take for example a vehicle which had its cold inflation tire pressure set near Denver (altitude 5300 feet), and is descending towards Los Angeles (altitude 300 feet). The tires could become underinflated by as much as 2.5 psi.  

Cold inflation pressure should therefore be readjusted after any significant changes in altitude.

See also 

 Direct TPMS
 Tire-pressure gauge
 Tire-pressure monitoring system

References 

Tire inflation
Pressure
Motor vehicle maintenance
Molybdenum hexacarbonyl. Molybdenum hexacarbonyl (also called molybdenum carbonyl) is the chemical compound with the formula Mo(CO)6. This colorless solid, like its chromium, tungsten, and seaborgium analogues, is noteworthy as a volatile, air-stable derivative of a metal in its zero oxidation state.

Structure and properties
Mo(CO)6 adopts an octahedral geometry consisting of six rod-like CO ligands radiating from the central Mo atom.  A recurring minor debate in some chemical circles concerns the definition of an "organometallic" compound.  Usually, organometallic indicates the presence of a metal directly bonded via a M–C bond to an organic fragment, which must in turn have a C–H bond.

Like many metal carbonyls, Mo(CO)6 is generally prepared by "reductive carbonylation", which involves reduction of a metal halide with under an atmosphere of carbon monoxide. As described in a 2023 survey of methods "most cost-effective routes for the synthesis of group 6 hexacarbonyls are based on the reduction of the metal chlorides (CrCl3, MoCl5 or WCl6) with magnesium, zinc or aluminium powders... under CO pressures".

Occurrence
Mo(CO)6 has been detected in landfills and sewage plants, the reducing, anaerobic environment being conducive to formation of Mo(CO)6.

Inorganic and organometallic research
Molybdenum hexacarbonyl is a popular reagent in academic research.

One or more CO ligands can be displaced by other ligands. Mo(CO)6, [Mo(CO)3(MeCN)3], and related derivatives are employed as catalysts in organic synthesis for example, alkyne metathesis and the Pauson–Khand reaction.

Mo(CO)6 reacts with 2,2′-bipyridine to afford Mo(CO)4(bipy).  UV-photolysis of a THF solution of Mo(CO)6 gives Mo(CO)5(THF).

[Mo(CO)4(piperidine)2]
The thermal reaction of Mo(CO)6 with piperidine affords Mo(CO)4(piperidine)2.  The two piperidine ligands in this yellow-colored compound are labile,  which allows other ligands to be introduced under mild conditions. For instance, the reaction of [Mo(CO)4(piperidine)2] with triphenyl phosphine in boiling dichloromethane (b.p. ca. 40 °C) gives cis-[Mo(CO)4(PPh3)2]. This cis- complex isomerizes in toluene to trans-[Mo(CO)4(PPh3)2].

[Mo(CO)3(MeCN)3]
Mo(CO)6 also can be converted to its tris(acetonitrile) derivative.  The compound serves as a source of "Mo(CO)3".  For instance treatment with allyl chloride gives [MoCl(allyl)(CO)2(MeCN)2], whereas treatment with KTp and sodium cyclopentadienide gives [MoTp(CO)3]− and [MoCp(CO)3]− anions, respectively. These anions react with a variety of electrophiles.  A related source of Mo(CO)3 is cycloheptatrienemolybdenum tricarbonyl.

Source of Mo atoms
Molybdenum hexacarbonyl is widely used in electron beam-induced deposition technique - it is easily vaporized and decomposed by the electron beam providing a convenient source of molybdenum atoms.

Safety and handling
Like all metal carbonyls, Mo(CO)6 is a dangerous source of volatile metal as well as CO.

References

Further reading
 
 
 

Molybdenum(0) compounds
Carbonyl complexes
Organomolybdenum compounds
Octahedral compounds
LunaCorp. LunaCorp, was a small but ambitious private company headed by its former president David Gump, established in 1989. It was designed around a privately funded mission, using Russian technology, to put a rover on the Moon.  The aim for the company was to fund the mission by the entertainment value of having customers drive the rover. The program's advisor was Dr. Buzz Aldrin, who, together with Neil Armstrong, walked on the surface of the Moon in 1969 during the first crewed lunar mission.
After producing no tangible results the company was dissolved in 2003.

The details of the mission evolved with time.  Because the Moon is hotter than boiling water at noon and colder than liquid nitrogen at night, in the final version of the design the robot would avoid those extremes by circumnavigating the Moon every 29.5 days (the length of a lunar day) to stay in sunlight, a strategy originally proposed by Geoffrey Landis. "Our robot, by driving completely around the Moon at a high latitude at only a few kilometers per hour, will enjoy lunar morning temperatures all the time by staying in sync with the sun", said the mission's controller.

References

External links
LunaCorp press release (2000) from Space Frontiers.org
Snapshots of LunaCorp History, 2007.
Interview:  LunaCorp and Orbital Outfitters, Daily Spaceflight News, 15 December 2010.

Private spaceflight companies
Companies disestablished in 2003
Defunct spaceflight companies
Two-wire circuit. In telecommunication, a two-wire circuit is characterized by supporting transmission in two directions simultaneously, as opposed to four-wire circuits, which have separate pairs for transmit and receive. The subscriber local loop from the telco central office are almost all two wire for analog baseband voice calls (and some digital services like ISDN), and converted to four-wire at the line card back when telephone switching was performed on baseband audio. Today the audio is digitized and processed completely in the digital domain upstream from the local loop.

The reason for using two wires rather than four is simple economics—half the materials cost half as much to purchase and install. Note the use of the past-tense "cost," as installation of two-wire copper local loops for telephony was done primarily during the mid 20th century. In the first world there is no new infrastructure planning for new copper-based technology, and as customers are migrating to cellular telephony and high-speed Internet, wireline carriers are abandoning their copper local loops, tearing out the copper and replacing it with fiber-optic cable and/or selling the rights-of-way to third parties for private use. In developing nations, wireless communications are considered to be the most cost-effective from an infrastructure perspective. Two-wire circuits in new installations are limited to intercom and military field telephone applications, though these too are being supplanted by modern digital communication modes.

To communicate in both directions in the same wire pair, conversion between four-wire and two-wire was necessary, both at the telephone and at the central office. A hybrid coil accomplishes the conversion for both. At the central office, it is part of a four-wire terminating set, more often as part of a line card. A modern line card has no two-to-four wire conversion whatsoever; it is strictly an analog/digital interface to a system that has a completely digital and integrated signal path internally. Using actual wires to circuit switch a telephone call became obsolete when the crossbar switch (a mechanical system) was replaced by 4ESS electronic switches in the 1970s by the Bell System in the US. The old telephone hybrids of yore have been replaced by inexpensive IC chip-based components that perform the same functions at greatly reduced cost. When personal computing and the Internet became popular at the end of the 20th century, the inductive load of traditional hybrids became a liability for computer modem users, and remaining loading coils in subscriber lines were scrapped.

Impedance standards 

Different countries have different standards for telephone impedance.

 The European regulatory requirement CTR 21 has been officially withdrawn. Some manufacturers prefer to continue meeting CTR 21, but there is little reason to do so.

References

 A History of engineering and science in the Bell System: Transmission Technology (1925-1975) 
 A History of engineering and science in the Bell System: Switching Technology (1925-1975) 

Communication circuits
SIPfoundry. SIPfoundry is a non-profit organization that develops open-source telephone software projects based on the Session Initiation Protocol(SIP).

Founded in 2004, SIPfoundry established ties with the SIP Forum. SIPfoundry promotes the standardization of SIP and interoperability of SIP products through the SIP Forum Test Framework (SFTF).

SIPfoundry spawned the development of sipXecs, an open source and standards-compliant SIP private branch exchange (PBX) for Linux.

See also 
sipXecs
VoIP

References

External links
sipfoundry.org
sipforum.org

VoIP organizations
Free and open-source software organizations