omniomni/omni-engineering huggingface dataset:
Sparse conditional constant propagation. In computer science, sparse conditional constant propagation (SCCP) is an optimization frequently  applied in compilers after conversion to static single assignment form (SSA).  It propagates constants, which is the calculation of static values which can be calculated at compile time. Moreover, it can find more constant values, and thus more opportunities for improvement, than separately applying dead code elimination and constant propagation in any order or any number of repetitions.

The algorithm operates by performing abstract interpretation of the code in SSA form.  During abstract interpretation, it typically uses a flat lattice of constants for values and a global environment mapping SSA variables to values in this lattice.  The crux of the algorithm comes in how it handles the interpretation of branch instructions.  When encountered, the condition for a branch is evaluated as best possible given the precision of the abstract values bound to variables in the condition.  It may be the case that the values are perfectly precise (neither top nor bottom) and hence, abstract execution can decide in which direction to branch.  If the values are not constant, or a variable in the condition is undefined, then both branch directions must be taken to remain conservative.

Upon completion of the abstract interpretation, instructions which were never reached are marked as dead code.  SSA variables found to have constant values may then be inlined at (propagated to) their point of use.

Notes

References 
 Cooper, Keith D. and Torczon, Linda.  Engineering a Compiler.  Morgan Kaufmann.  2005.

Compiler optimizations
Autodynamics. Autodynamics was a physics theory proposed by Ricardo Carezani (1921–2016) in the early 1940s as a replacement for Einstein's theories of special relativity and general relativity. Autodynamics never gained status as a viable alternative model within the physics community, and today is wholly rejected by mainstream science.

Main tenets of autodynamics 

The primary claim of autodynamics is that the equations of the Lorentz transformation are incorrectly formulated to describe relativistic effects, which would invalidate special relativity, general relativity, and Maxwell's equations. The effect of the revised equations proposed in autodynamics is to cause particle mass to decrease with particle velocity, being exchanged with kinetic energy (with mass being zero and kinetic energy being equal to the rest mass at c). This exchange between mass and energy is the proposed mechanism underlying most of the derived conclusions of autodynamics.

Ancillary predictions of autodynamics include:
 the nonexistence of the neutrino,
 the existence of additional particles that have not been observed by mainstream physicists (including the "picograviton" and the "electromuon"),
 the existence of additional decay modes for muons and interaction modes for energetic atomic nuclei.

Status of autodynamics 
Autodynamics is wholly rejected by the mainstream scientific community. Since Carezani's original publication, no papers on autodynamics have appeared in the scientific literature, except for additional papers by Carezani published in alternative journals such as Physics Essays. A 1999 article in the  magazine Wired quotes H. Pierre Noyes, a professor at the Stanford Linear Accelerator Center, as stating, "autodynamics was disproved. Special relativity is correct" and noting that "mainstream physicists have considered autodynamics a crackpot theory for decades". Noyes was a researcher in an experiment attempting to compare the predictions of SR and AD, and concluded that the values calculated by SR were significantly closer to what was observed. Carezani later argued that the experiment was not relevant for comparing the two theories by pointing out that AD applies specifically to decay cases, yet the electrons in the Noyes experiment received energy from the external medium (klystron EM field). According to Lee Smolin, there has been "no serious attempt [by the autodynamics supporters] to make an argument or to discuss experimental data that refute their basic claims".

See also 
 List of topics characterized as pseudoscience

References

External links 
 The Society for the Advancement of Autodynamics (SAA)

Pseudoscience
Special relativity
Fringe physics
Copy propagation. In compiler theory, copy propagation is the process of replacing the occurrences of targets of direct assignments with their values.  A direct assignment is an instruction of the form x = y, which simply assigns the value of y to x.

From the following code:

 y = x
 z = 3 + y

Copy propagation would yield:

 z = 3 + x

Copy propagation often makes use of reaching definitions, use-def chains and def-use chains when computing which occurrences of the target may be safely replaced.  If all upwards exposed uses of the target may be safely modified, the assignment operation may be eliminated.

Copy propagation is a useful "clean up" optimization frequently used after other compiler passes have already been run.  Some optimizations—such as classical implementations of elimination of common sub expressions—require that copy propagation be run afterwards in order to achieve an increase in efficiency.

See also 
 Copy elision
 Constant folding and constant propagation

References

Further reading

Muchnick, Steven S.  Advanced Compiler Design and Implementation.  Morgan Kaufmann. 1997.

Compiler optimizations
Knudsen gas. A Knudsen gas is a gas in a state of such low density that the average distance travelled by the gas molecules between collisions (mean free path) is greater than the diameter of the receptacle that contains it. If the mean free path is much greater than the diameter, the flow regime is dominated by collisions between the gas molecules and the walls of the receptacle, rather than intermolecular collisions with each other. It is named after Martin Knudsen.

Knudsen number 
For a Knudsen gas, the Knudsen number must be greater than 1. The Knudsen number can be defined as:

where

 is the mean free path [m]

 is the diameter of the receptacle [m].

When , the flow regime of the gas is transitional flow. In this regime the intermolecular collisions between gas particles are not yet negligible compared to collisions with the wall. However when , the flow regime is free molecular flow, so the intermolecular collisions between the particles are negligible compared to the collisions with the wall.

Example 
For example, consider a receptacle of air at room temperature and pressure with a mean free path of 68nm. If the diameter of the receptacle is less than 68nm, the Knudsen number would greater than 1, and this sample of air would be considered a Knudsen gas. It would not be a Knudsen gas if the diameter of the receptacle is greater than 68nm.

See also 
 Free streaming
 Kinetic theory

References

Gases
Phases of matter
Shuttle-C. The Shuttle-C was a study by NASA to turn the Space Shuttle launch stack into a dedicated uncrewed cargo launcher. The Space Shuttle external tank and Space Shuttle Solid Rocket Boosters (SRBs) would be combined with a cargo module to take the place of the Shuttle orbiter and include the main engines. Various Shuttle-C concepts were investigated between 1984 and 1995.

The Shuttle-C concept would theoretically cut development costs for a heavy launch vehicle by re-using technology developed for the shuttle program. End-of-life and Space Shuttle hardware would also have been used. One proposal even involved converting Columbia or Enterprise into a single-use cargo launcher. Before the loss of Space Shuttle Challenger, NASA had expected about 24 shuttle flights a year. In the aftermath of the Challenger incident, it became clear that this launch rate was not feasible for a variety of reasons. With the Shuttle-C, it was thought that the lower maintenance and safety requirements for the uncrewed vehicle would allow a higher flight rate.

The Shuttle-C would have been the main crew launch vehicle for the ILREC Piloted Lander in the International Lunar Resources Exploration Program.

In the early 1990s, NASA engineers planning a crewed mission to Mars included a Shuttle-C design to launch six non-reusable, 80-ton segments to create two Mars ships in Earth orbit. After President George W. Bush called for the end of the Space Shuttle by 2010, these proposed configurations were put aside.

As early as the 1970s, some iteration of the Shuttle-C had been studied (Encyclopedia Astronautica mentions it as "Class 1 SDV"). It was discussed in Gerard O'Neill's 1976 book The High Frontier: Human Colonies in Space, with artwork by Don Davis.

See also
 Shuttle SERV
 Magnum (rocket)
 Shuttle-derived vehicle
 Shuttle-Derived Heavy Lift Launch Vehicle, a heavy lift launch vehicle with a similar design.
Energia
 List of space launch system designs

References

External links
 Encyclopedia Astronautica link on the Shuttle-C

Space Shuttle program
Partially reusable space launch vehicles
Shuttle-derived space launch vehicles
Cancelled space launch vehicles
MagBeam. MagBeam is the name given to an ion propulsion system for space travel initially proposed by Professor Robert Winglee of the Earth and Space Sciences Department at the University of Washington for the October 2004 meeting of the NIAC. MagBeam is different from a traditional electrostatic ion thruster in several ways, the primary one being that instead of the fuel and propulsion system being part of the payload craft, they are instead located on a platform held in orbit. It has also been suggested that the technology could be used to reduce the amount of space debris in orbit around Earth.

Propulsion system 

MagBeam propulsion uses a helicon plasma source to produce a plasma beam. A helicon drive consists of a quartz tube wrapped in a radio antenna, into which a gas such as argon or xenon is injected. RF currents pass through the antenna creating a rapid variation of the electric field, ionizing the gas. The ionized gas is accelerated by a magnetic field to produce thrust. The helicon drive produces a tight beam of ions as the magnetic field that accelerates them continuously expands with the plasma beam keeping them focused. This ion beam is used to push a payload which is equipped with a small amount of gas for propellant such as argon or xenon, a power source and a set of electromagnets to produce a mini-magnetosphere magnetic sail. The gas propellant is ejected into the plasma beam being directed at the craft which heats and ionizes it.

The electromagnets repel this ionized gas imparting thrust upon the payload. This results in an acceleration of around 1 ms−2, much faster than traditional ion propulsion systems. This amount of acceleration would make it possible to make a trip to Mars in as little as 50 days, reaching speeds as high as 20 km/s. The deceleration is accomplished by having another platform at the other end of the journey directing a plasma beam at the payload. By eliminating the mass of the propulsion system from the payload the MagBeam system allows for much faster acceleration and higher top speeds than conventional propulsion systems mounted on the payload. One problem with the system is the need for a sufficiently dense power-source, with a massive battery bank being proposed for an Earth-Mars Mag-Beam facility massing some 3,000 tons.

The system proposed by Winglee would allow a round-trip from Earth to Mars in 90 days, with 11 days stop-over at Mars.

A similar system for use of a particle beam to push a mini-magnetosphere magnetic sail was proposed by Geoffrey A. Landis in 2001 as a possible propulsion system for interstellar travel.

Space debris clearance
Winglee has also proposed that the technology could be used to help clear space debris in Earth orbit by pushing items of debris out of orbit towards the atmosphere where they could burn up safely.

References

External links
NASA site
Space.com article

Spacecraft propulsion
Magnetic propulsion devices
Elisha K. Root. Elisha King Root (May 5, 1808 - September 1, 1865) was a Connecticut machinist, inventor, and President of Colt's Manufacturing Company.

Root was born on a Massachusetts farm and worked as a bobbin boy in a cotton mill before switching, at the age of 15, to working in a machine shop in Ware, Massachusetts. At age 24 he was hired by Connecticut industrialist Samuel W. Collins to work in his axe factory in Collinsville, a village of Canton, Connecticut.

According to historian Diana Muir writing in Reflections in Bullough's Pond, Root "reconceptualized" the making of axes. Until his invention, axes were made by "flattening wrought iron, folding it around a steel pin, and forging the two sides together under a trip hammer."  Root arranged "a series of dies and rollers that could 'die forge' -or apply pressure to a mold, forming a piece of hot wrought iron into the shape of an ax, with an eye already punched to receive the handle."  According to Muir, Root next automated the tempering of axes by inventing a machine that moved ax heads through a temperature-regulated oven on a rotating wheel. And a machine that "shaved" the axes to give them a sharp edge, so that they needed only a small amount of finishing on a grindstone.

In 1849 Samuel Colt hired Root to come work in his Hartford firearms factory as a superintendent. Root performed this role with great success, developing many star employees.

It was while working for Colt that Root perfected the Lincoln miller milling machine, 150,000 of which were sold in the late 19th century, making it the most important American machine tool of the era. He modernized firearms production at Colt by designing state of the art drop hammers, boring machines, gauges, jigs, etc. Root also improved the milling machine invented by Simeon North and improved by the Robbins and Lawrence Company of Vermont and by Francis A. Pratt of the George S. Lincoln company in Hartford, Connecticut. The improved tool was known as the Lincoln Miller.

The Colt Model 1855 Sidehammer Pocket Revolver, or Colt Root Revolver, was named in honor of the engineer, and saw use during the American Civil War.

After Colt's death in 1862, Root took over as president of Colt's Patent Firearms until his death on September 1, 1865.

See also

 History of Connecticut industry
 Simeon North
 John H. Hall (gunsmith)

References

Bibliography
 
 

1808 births
1865 deaths
19th-century American inventors
Machine tool builders
People from Ludlow, Massachusetts
Francis A. Pratt. Francis Ashbury Pratt (February 15, 1827 – February 10, 1902) was an American mechanical engineer, inventor, and co-founder of Pratt & Whitney.

Biography
Pratt was born in Peru, New York. His parents moved the family to Lowell, Massachusetts, when he was eight years old. He was educated in Lowell and apprenticed in a machine shop. In 1848, he moved to Gloucester, New Jersey, and worked for Gloucester Machine Works as a journeyman and contractor. In 1852, Pratt moved to Hartford, Connecticut, to work at Colt Armory. It was at Colt that he met Amos Whitney. Pratt soon left Colt to work at Phoenix Iron Works and brought Whitney along with him.

While still working at Phoenix Iron Works, he designed a milling machine for George S. Lincoln & Company of Hartford, Connecticut, which became the Lincoln miller, in some ways perhaps the most important American machine tool of the late 19th century. Over 150,000 machines were built on this form factor (by many firms).

Pratt cofounded the Pratt & Whitney company along with Amos Whitney in 1860. Their first product was a thread winder for the Willimantic Linen Company. They went on to manufacture machine tools, tools for the makers of sewing machines, and gun making machinery for use by the Union Army during the American Civil War.  He is credited with being first to permit production of fine gear work. Pratt promoted interchangeable parts and the adoption of a standard system for gages for the United States and Europe. Among several machine-tool patents, his most important was for planing metal granted on July 28, 1869.

He served as a member of the board of water commissioners for the city of Hartford for four years. He was a director of the Hartford board of trade and the Pratt & Cady company. He served as president and director of the Electric Generator Company. He was a member of the American Society of Mechanical Engineers.

He died in Hartford, Connecticut and was interred at Cedar Hill Cemetery.

References

Bibliography

External links
 Picture of Francis Pratt  
 Pratt & Whitney Measurement Systems website 
 Francis Pratt cemetery

1827 births
1902 deaths
19th-century American inventors
American Civil War industrialists
American company founders
American mechanical engineers
Burials at Cedar Hill Cemetery (Hartford, Connecticut)
Businesspeople from Hartford, Connecticut
Machine tool builders
People from Lowell, Massachusetts
People from Peru, New York
Aerocoach. Aerocoach (full name General American Aerocoach Corporation) was a bus and coach manufacturer based in Chicago, Illinois, in the United States and was popular in the 1940s. The company existed between 1939 and 1952 when it went out of business. Its first manager was Harry Alphonse Fitzjohn, co-founder of the FitzJohn-Erwin Manufacturing Company.

Demise and Fate of East Chicago Plant
The East Chicago plant was acquired by Steel Car Company, a subsidiary of the General American Transportation Corporation, then by Graver Tank and Manufacturing Company and finally by Union Tank Car Company in 1969 to manufacture railway tank cars until it closed in 2008.

Products
 P45-37
 P46-37
 P46-137
 P-373 - 37 passenger intercity coach
 P-372 - intercity coach

See also
 FitzJohn Coach Company

References 

Defunct bus manufacturers of the United States
Companies that have filed for bankruptcy in the United States
Vehicle manufacturing companies established in 1939
Vehicle manufacturing companies disestablished in 1952
1939 establishments in Illinois
1952 disestablishments in Indiana
Amos Whitney. Amos Whitney (October 8, 1832 – August 5, 1920) was a mechanical engineer and inventor who co-founded the Pratt & Whitney company.  He was a member of the prominent Whitney family.

He was born in Biddeford, Maine, to Aaron and Rebecca (Perkins) Whitney and educated at the common schools in Saccarappa, Maine, and Exeter, New Hampshire.  He moved at the age of 14 with his parents to Lawrence, Massachusetts, and apprenticed at the Essex Machine Company.

In 1852, he moved to Hartford, Connecticut, and worked at the Colt Armory.  At Colt, he met Francis A. Pratt who soon left to become superintendent at the Phoenix Iron Works and took Whitney with him.  While working at Phoenix Iron Works, Whitney designed the Lincoln milling machine.

In 1860, while still working at the Phoenix Iron Works, Pratt and Whitney formed the Pratt & Whitney company.  Their first product was a thread winder for the Willimantic Linen Company.  They went on to manufacture machine tools for the manufacture of guns, sewing machines, bicycles and typewriters.  The manufacturing of gun making machinery rapidly increased during the American Civil War.

In 1893, Whitney was made vice-president of the company and worked as president from 1898 to 1901.  The company was acquired by the Niles-Bement-Pond Company and Whitney remained as one of the directors.  He also worked as president and director of the Gray Telephone Pay Station Company, director of the Pratt & Cady Co., director in the Co-operative Savings Bank and as treasurer of Whitney Manufacturing Company which was organized by his son Clarence.

He died on August 5, 1920, in Poland Spring, Maine and was interred at Cedar Hill Cemetery in Hartford, Connecticut.

See also
Whitney family

References

External links
 Pratt & Whitney Measurement Systems Website

1832 births
1920 deaths
Engineers from Connecticut
20th-century American businesspeople
19th-century American inventors
American Civil War industrialists
American company founders
American mechanical engineers
Burials at Cedar Hill Cemetery (Hartford, Connecticut)
Businesspeople from Hartford, Connecticut
Machine tool builders
People from Biddeford, Maine
Charles E. Billings. Charles Ethan Billings (1834–1920) was an American mechanical engineer, inventor, superintendent, and businessman. He held various U.S. patents on hand tools, either assigned or licensed to the firm that he and Christopher M. Spencer cofounded, the Billings & Spencer Company. His name as patent holder is stamped (as C.E. Billings) on countless forged hand tools, many of which survive. Billings was an expert in drop forging and was an influential leader in the American system of manufacturing and its successor systems of mass production for firearms, sewing machines, hand tools, bicycles, and other goods. He served as president of the American Society of Mechanical Engineers in 1895 and 1896. The Billings & Spencer Company was both a machine tool builder and a manufacturer of hand tools made with its machine tools.

Biography 
He was born in Weathersfield, Vermont, the son of Ethan F. and Clarissa M. (née Marsh) Billings. He served his apprenticeship at Robbins & Lawrence in Windsor, Vermont. Robbins & Lawrence was a factory and armory that was an important early node in the social network of the 19th century machine tool industry.

In 1856, at the age of 21, he worked at the Colt armory in Hartford, Connecticut, as a die sinker and tool maker and became their expert on the drop forging process. In 1862, he went to E. Remington & Sons, where he built up their forging plant, increasing its efficiency and  saving $50,000 by one improvement in frame forging alone. At the end of the American Civil War, he returned to Hartford as the superintendent of the Weed Sewing Machine Company, which had taken over the old Sharps Rifle Works, built by Robbins & Lawrence.

In 1868, while at the Roper Repeating Arms Company in Amherst, Massachusetts, he worked with Christopher M. Spencer. The Roper company failed and in 1869, the two founded a partnership in Hartford, Connecticut, called Billings & Spencer, which would manufacture sewing machines, drop-forged hand tools, and machine tools. Billings perfected a drop hammer for metal forging in the 1870s and designed the copper commutator which was central to the operation of electrical generators and motors.

In 1895, Billings was president of the American Society of Mechanical Engineers.

He died on June 5, 1920, in Hartford, Connecticut, and was interred at Cedar Hill Cemetery.

List of patents held
This list may not be exhaustive; if you like, you can verify its exhaustiveness with a US patent search.

References

Bibliography

External links
Biography from http://www.all-biographies.com/
Connecticut inventors

1834 births
1920 deaths
19th-century American businesspeople
19th-century American inventors
Burials at Cedar Hill Cemetery (Hartford, Connecticut)
Businesspeople from Hartford, Connecticut
People from Weathersfield, Vermont
Presidents of the American Society of Mechanical Engineers
Machine tool builders