omniomni/omni-engineering huggingface dataset:
Book folding. Book folding is the stage of the book production process in which the pages of the book are folded after printing and before binding.

Until the middle of the 19th century, book folding was done by hand, and was a trade.  In the 1880s and 1890s, book folding machines by Brown and Dexter came onto the market, and by the 1910s hand-folding was rare, with one publisher declaring them to be "practically obsolete" in 1914.

The folding process is also necessary to produce print products other than books—for instance mailings, magazines, leaflets etc.

Hand folding
In olden times, paper was folded by hand and stapled.

Folding machines

Two main types of mechanisms are commonly employed in folding machines: buckle folders and knife folders.

Buckle folder
In a buckle folder, the paper is first passed through 2 spinning rollers, which feed the paper into a pair of guide plates that redirect the paper at a slight angle, bending the paper. At the far end of the guide plates is a "paper stop". As the rollers continue to spin, the paper continues to slide in between the guides until it hits the paper stop, then, having nowhere else to go, buckles at the interface between the rollers and the angled guides. As the rollers continue to spin, the buckle increases, until it is eventually caught by a pair of "nip" rollers, which pull the buckle in and compresses and flattens it into a neat crease.

Adjusting the paper stop in a buckle folder determines where the fold will be placed. Also, a buckle folder may contain only 3 rollers, with one shared by both the input rollers and the nip rollers.

Although buckle folders are fast, simple, efficient, and have small folding tolerances, they are not suitable for substrate of very low (<40g/m2) or very heavy paper grammage (>120g/m2).

Knife folder
In a knife folder, a sheet of paper is fed horizontally over 2 unpowered rollers until it hits a paper stop, at which point a dull blade pushes down on the paper and in between the 2 rollers to create the fold.

Although the knife folder is slower than buckle folders, it is more precise and can handle extreme grammages very well. It also has small folding tolerances, but is a more complex machine.

Folding variants

Parallel folds
Folding a paper more than once in the same direction (i.e. with parallel creases) is called parallel folding. Common examples of this are the half fold, letter fold, gate fold, and Z-fold.

Cross folds
A cross fold is when a paper is folded once, then rotated 90 degrees and folded again. The creases therefore cross each other at right angles. The most basic cross fold is the French fold, or right-angle fold. Other examples include the 16-page broadside and the 12-page letter.

See also
 Book
 Book publishing
 Paper size (influenced by the number of folds)

References

Book arts
Print production
Frederick Funston-class attack transport. The Frederick Funston-class attack transport was a class of two US Navy attack transports. They saw service in World War II and later in the Korean War.

Attack transports were a special type of transport ship designed to transport troops and their equipment over long distances to hostile shores, and then execute an amphibious invasion at the destination, using an array of smaller integral assault boats. Like all attack transports, the Frederick Funston class was generously armed with antiaircraft weaponry to protect itself and its vulnerable cargo of troops from air attack in the battle zone.

History

The class derives its name from US Army General Frederick Funston, a veteran of the Philippine–American War and Medal of Honor recipient. The two ships of the Frederick Funston class were based on the Maritime Commission's ubiquitous Type C3 hull (specifically Type C3-S-A1). They began their service lives as transport ships for the US Army, but after several months of service in this role they were acquired by the US Navy and reclassified attack transports. It is not known whether they underwent any modifications for their new role.

There is no mention of cargo space in the DANFS entries, so it is not known how much cargo the vessels carried. The class carried a larger number of troops than most attack transports—2,200 as opposed to the 1,200 to 1,500 of most other APA's.

In service
The Frederick Funstons participated in the Mediterranean Theatre, taking part in the invasions of Salerno and Italy, and later in the Pacific Theatre. After the war, they were decommissioned and returned to the US Army, when they were redesignated USAT (US Army Transport). In the 1950s the ships were reacquired by the Navy and reclassified T-AP. Both of them then went on to serve in the Korean War - mostly on transport missions.

James O'Hara was struck from the Naval Register in 1961. Both vessels were scrapped in 1968-69.

References
See the DANFS entries for the individual ships: USS Frederick Funston (APA-89) and USS James O'Hara (APA-90).

Auxiliary transport ship classes
IRIS engine. The IRIS Engine is a design for a new type of internal combustion engine. Its inventors say that engines constructed using this design can be smaller, lighter and significantly more efficient than traditional engines of comparable horsepower and displacement. The design replaces the piston and cylinder architecture of conventional engines with a purportedly novel mechanism called the Internally Radiating Impulse Structure, or IRIS.

In January 2008, the IRIS Engine design won first prize for transportation technology in NASA's annual "Create the Future" design competition. In October 2008, the Radial Expansion Engine (RXE), a variant of the IRIS design, won second prize in the ConocoPhillips Energy Prize competition.

Geometry of the IRIS
In an IRIS combustion chamber, a number of inverted segments of a circle, or "chordons," interact to create a continuously sealed chamber of variable volume. Instead of elongating during combustion, as a traditional engine does, the IRIS engine's chamber expands in diameter. The inventors claim that this innovation will reduce waste heat and will increase the amount of surface area the engine has available to produce torque.

Design variations
IRIS engines are designed to run on traditional fuels, but could also be adapted to use biodiesel, natural gas, or hydrogen. IRIS chamber technology could also be utilized to create pumps, compressors and medical devices.

Designers
The IRIS was conceived of by Timber Dick, a Denver, Colorado inventor and businessman. Three of his sons, Corban, Levi, and Tomicah Tillemann-Dick, also contributed to the design and are credited on patent applications relating to the IRIS engine. The design recently won the $20,000 Dow Sustainability Award. A closely related design by the same team of inventors, the Radial Expansion Engine, was awarded a $75,000 prize in the ConocoPhillips Energy Prize Competition.

References

External links
http://money.cnn.com/galleries/2009/smallbusiness/0904/gallery.Rice_business_plan_competition_winners.smb/3.html
http://www.denverpost.com/search/ci_8189510
https://www.youtube.com/watch?v=Xb0pOKFr1fg

Internal combustion piston engines
Barcol hardness test. The Barcol hardness test characterizes the indentation hardness of materials through the depth of penetration of an indentor, loaded on a material sample and compared to the penetration in a reference material. The method is most often used for composite materials such as reinforced thermosetting resins or to determine how much a resin or plastic has cured. The test complements the measurement of glass transition temperature, as an indirect measure of the degree of cure of a composite. It is inexpensive and quick, and provides information on the cure throughout a part.

Barcol impressor
Originally called the Barber-Colman Impressor, the Barcol impressor was developed by Walter Colman as a hand-held, portable means of assessing the hardness of a material during World War II. The United States Army Air Corps required a hand-held method of checking the hardness of rivets due to concerns that aircraft could be sabotaged by replacing normal rivets with soft lead or wooden ones which would fail during flight. The impressor operates when the tip is pressed against the material in question. The hardness of the material determines how far the tip indents and this is transferred by a tension spring and lever to be read on a dial.

Operation
The Barcol hardness test is generally used on soft materials such as rigid plastics. It measures hardness based on indentation of a sharp point with a flat tip. The test is performed using a similar method and indentation device as that used to measure Shore D hardness, however the Shore D indentor has a round tip. Barcol hardness is not a valid hardness measure for curved surfaces.

Scales and values
The governing standard for the Barcol hardness test is ASTM D 2583. Barcol hardness is measured on a scale from 0 to 100 with the typical range being between 50B and 90B. A measurement of 60B is roughly equivalent to a Shore hardness of 80D or a Rockwell hardness M100. As defined in ASTM D 2583 the scale divisions from 0-100 should each indicate a depth of 0.0076 mm or the equivalent 0.0003 inches.

See also
 Brinell hardness test
 Knoop hardness test
 Rockwell scale
 Shore durometer
 Vickers hardness test
 Hardness comparison

References

Hardness tests
Ernest Crosbie Trench. Ernest Frederic Crosbie Trench CBE, TD (6 August 1869 – 15 September 1960) was a British civil engineer.

Ernest was born on 6 August 1869 to George Frederic Trench and Frances Charlotte Talbot Crosbie. Anne of York, Duchess of Exeter, sister to Edward IV and Richard III was an ancestor of Ernest's mother. He was educated at Monkton Combe School and at Lausanne before studying for a Master of Arts degree from Trinity College, Dublin.

He worked primarily as a railway engineer, beginning his railway career as a pupil of E.B. Thornhill on the London and North Western Railway (LNWR) in 1893, after which he worked for the Midland Railway (from 1899) and the North London Railway from January 1903, before returning to the LNWR on 1 March 1906 as assistant engineer. Three years later on 1 March 1909, he was promoted to chief assistant engineer, becoming chief engineer on 1 October the same year following the retirement of Thornhill the previous month. At the start of 1923 he was appointed as the chief engineer of the London, Midland and Scottish Railway (LMS), becoming the LMS consulting engineer from 1 February 1927, retiring on 1 April 1930.

He became involved in the Institution of Civil Engineers as an associate member in 1897, progressing to a full membership in 1904, he was first elected to the council in 1915 and would serve on it for the next seventeen years. He was elected vice president of the institution in 1924 and served as its president from 1927 to 1928.

In 1920 he was appointed a Commander of the Order of the British Empire for "services rendered in connexion with 1914-18 war" and in 1931 received the Territorial Decoration for service as a volunteer Colonel in the Engineer and Railway Staff Corps.

He married Netta Taylor on 3 April 1895 and fathered five sons and one daughter. He died in Marlborough, Wiltshire on 15 September 1960.

See also

References 

1869 births
1960 deaths
British civil engineers
Presidents of the Institution of Civil Engineers
Presidents of the Smeatonian Society of Civil Engineers
People educated at Monkton Combe School
Alumni of Trinity College Dublin
Engineer and Railway Staff Corps officers
London and North Western Railway people
London, Midland and Scottish Railway people
Option–operand separation. Option–operand separation is a principle of imperative computer programming. It was devised by Bertrand Meyer as part of his pioneering work on the Eiffel programming language.

It states that an operation's arguments should contain only operands — understood as information necessary to its operation — and not options — understood as auxiliary information. Options are supposed to
be set in separate operations.

The motivations for this are:
 Ease of learning: Beginners do not have to concern themselves with setting options.
 Wide spectrum coverage:  Experts can still set options using the auxiliary operations.
 Evolution. Options are more likely to change than operands, so the parameter list to the operation remains more stable.

References

Object-oriented programming
DAR 4. The DAR 4 was a prototype airliner built in Bulgaria in 1930.

Design and development
The DAR 4 was a conventional biplane design, with unstaggered wings of unequal span braced with Warren trusses. The fuselage offered fully enclosed accommodation for the two pilots and four passengers. A curious feature of the design was that the top wing was not attached directly to the top of the fuselage as is common in cabin biplanes, but was mounted above it with cabane struts. Power was provided by three radial engines; one in the nose, and one mounted on each lower wing where the struts met. Performance was disappointing, and in particular, the narrow track of the undercarriage created difficulties. After the single prototype, no further examples were built.

Specifications

References

 
 

1930s Bulgarian airliners
DAR 04
Trimotors
Biplanes
AIRS. AIRS may refer to:

 Atmospheric Infrared Sounder, a weather and climate instrument flying on NASA's Aqua satellite
 Advanced Inertial Reference Sphere, a guidance system designed for use in the LGM-118A Peacekeeper ICBM
 Put on airs, a phrase describing a person who behaves as if they are better than other people
 Airable Internet Radio Service

See also
Air (disambiguation)
Darzhavna Aeroplanna Rabotilnitsa. Darzhavna aeroplanna rabotilnitsa ( - State Aircraft Workshops), abbreviated DAR (), was the first Bulgarian aircraft manufacturer, established in 1924 at Bojourishte.

History
Initially involved in repairing German aircraft then in use in Bulgaria, DAR soon began producing copies of some of these (DAR Uzunov-1, DAR 2), before moving on to licensed production of the Focke-Wulf Fw 44. The workshops produced a number of original designs, some of these were produced (DAR 1, DAR 3, DAR 4, DAR 6, , DAR 9, DAR 11), while others never proceeded past prototype stage (DAR 5, DAR 7, DAR 10).

Although aircraft manufacture was moved to the Darzhavna Samoletna Fabrika (Държавна самолетна фабрика - State Airplane Factory, abbr. ДСФ - DSF) in Lovech in 1940, designers remained in DAR.  was DAR's head designer towards the end of the organisation's lifespan. Amongst others, he was responsible for its final design, the DAR 11 fighter of 1941 that never left the drawing board. DAR was closed after 1945 and the personnel and facilities were moved to the DSF in Lovech.

Although not direct legal successor, in 1995 a newly established private company called Aeroplani DAR based its name and heritage on DAR.

Products

See also 
 State Aircraft Factory (Bulgaria)

References

Footnotes

Notes

Bibliography

External links

 Romanian Military History Forum: Bulgarian Aircraft Production (1910-1945) – includes pictures of a magazine article with production lists

Aircraft manufacturers of Bulgaria
Government-owned companies of Bulgaria
Defunct manufacturing companies of Bulgaria
Manufacturing companies established in 1924
Bulgarian companies established in 1924
Four factor formula. The four-factor formula, also known as Fermi's four factor formula is used in nuclear engineering to determine the multiplication of a nuclear chain reaction in an infinite medium.

The symbols are defined as:
,  and  are the average number of neutrons produced per fission in the medium (2.43 for uranium-235).
 and  are the microscopic fission and absorption thermal cross sections for fuel, respectively.
 and  are the macroscopic absorption thermal cross sections in fuel and in total, respectively.
 is the macroscopic fission cross-section.
 is the number density of atoms of a specific nuclide.
 is the resonance integral for absorption of a specific nuclide.

 is the average lethargy gain per scattering event.
Lethargy is defined as decrease in neutron energy.
 (fast utilization) is the probability that a fast neutron is absorbed in fuel.
 is the probability that a fast neutron absorption in fuel causes fission.
 is the probability that a thermal neutron absorption in fuel causes fission.
 is the thermal non-leakage probability

Multiplication
The multiplication factor, , is defined as (see Nuclear chain reaction): 

 If  is greater than 1, the chain reaction is supercritical, and the neutron population will grow exponentially. 
 If  is less than 1, the chain reaction is subcritical, and the neutron population will exponentially decay. 
 If , the chain reaction is critical and the neutron population will remain constant.

In an infinite medium, neutrons cannot leak out of the system and the multiplication factor becomes the infinite multiplication factor, , which is approximated by the four-factor formula.

See also
 Six factor formula
 Critical mass
 Nuclear chain reaction
 Nuclear reactor

References

Nuclear technology
Radioactivity
Oxepin. Oxepin is an oxygen-containing heterocycle consisting of a seven-membered ring with three double bonds.  The parent C6H6O exists as an equilibrium mixture with benzene oxide.

The oxepin–benzene oxide equilibrium is affected by the ring substituents.  A related dimethyl derivative exists mainly as the oxepin isomer, an orange liquid.

Oxepin is an intermediate in the oxidation of benzene by the cytochrome P450 (CYP).  Other arene oxides are metabolites of the parent arene.

References
No. 224 Squadron IAF. No. 224 Squadron IAF (Warlords) is a Ground Attack squadron based at Jamnagar Air Force Station. It was temporarily disbanded in 2007 after the retirement of MiG-23MF aircraft. The unit was resurrected in 2008 with Jaguar Darin II aircraft and continues to operate from Jamnagar.

The crest
No.224 Sqn crest depicts a warrior on a chariot proceeding to war. The chariot signifies the weapon platforms which are highly lethal and flexible, the horse signifying the power and strength and the warrior is at high state of readiness and aiming his weapons on the enemies.

History
No. 224 Sqn, IAF was raised on 4 July 1983 at Airforce Station Adampur under the command of Wg Cdr RA Massey, Vr C, as a part of Western Air Command. The unit was equipped with the Mig 23MF and assigned the Air defence role and later an additional peacetime role of Banner Target Towing. Later it moved to Jamnagar, its MiG-23s modified to tow targets.

No.224 Sqn was the last operator of the MiG-23MF before their retirement from the Indian Air Force in 2007. The final fly past of the closing ceremony was done by Wing Commander M. K. Singh flying a banner titles "End of an Era", Wing Commander Tapas Sahu, Squadron Leader Vijay Shelke and Wing Commander RS Jamdar.

Operations
Operation Meghdoot from 1985 to 1986.
Operation Safed Sagar during May 1999.

Awards and honours
No 224 Sqn was adjudged the best over all fighter squadron in Western Air Command during 1986-1987
Wg Cdr  Radhakrishnan Radhish Vayusena Medal 2006
Sqn Ldr SV Bal                Vayusena Medal 1991
WO      L Jha                 Commendation by CAS 1997
WO      HS Saini              Commendation by CAS 1989
Sgt     Tanwar RS             Commendation by CAS 1988
Sgt     K Damodaran           Commendation by CAS 1988
WO      Ravi Nandan           Commendation by CAS 1987
Sgt     Sagar SC              Commendation by CAS 1986

Aircraft

References

1983 establishments in India
2007 disestablishments in India
224
Military units and formations established in 1983
Military units and formations disestablished in 2007
Vishnevite. Vishnevite, or sulfatic cancrinite, is a mineral of the cancrinite group with the chemical formula (Na, Ca, K)6(Si, Al)12O24[(SO4),(CO3), Cl2]2-4·nH2O. It has hexagonal crystals.

References

External links
 

Mindat data

Cancrinite group
Hexagonal minerals
Minerals in space group 173
Dimethyldioxirane. Dimethyldioxirane (DMDO) is the organic compound with the formula . It is the dioxirane derived from acetone and can be viewed as the monomer of acetone peroxide. It is a powerful selective oxidizing agent that finds some use in organic synthesis. It is known only in the form of a dilute solution, usually in acetone, and hence the properties of the pure material are largely unknown.

Synthesis
DMDO is not commercially available because of chemical instability. DMDO can be prepared as dilute solutions (~0.1 M) by treatment of acetone with potassium peroxymonosulfate , usually in the form of Oxone (2KHSO5·KHSO4·K2SO4).

The preparation of DMDO is rather inefficient (typical yields < 3%) and typically only yields a relatively dilute solution in acetone (only up to approximately 0.1 M).  This is tolerable as preparation uses inexpensive substances: acetone, sodium bicarbonate, and oxone.  Cold solutions (−10 to −20 °C) of DMDO are stable for days. Decomposition is accelerated by light and by heavy metals. The concentration of DMDO may be assayed immediately prior to its use.

Methyl(trifluoromethyl)dioxirane  can be similarly prepared from methyl trifluoromethyl ketone. It is a stronger oxidant than DMDO.

Uses
DMDO is most commonly used for the oxidation of alkenes to epoxides.  One advantage of using DMDO is that the only byproduct of oxidation is acetone, a fairly innocuous and volatile compound. DMDO oxidations are particularly mild, sometimes allowing oxidations which might not otherwise be possible. 

Despite its high reactivity, DMDO displays good selectivity for electron-rich olefins.  DMDO will also oxidize several other functional groups.  For example, DMDO will oxidize primary amines to nitro compounds and sulfides to sulfoxides.  In some cases, DMDO will even oxidize unactivated C-H bonds:

DMDO can also be used to convert nitro compounds to carbonyl compounds (Nef reaction).

See also

 Difluorodioxirane
 Dioxirane
 Shi epoxidation

References

Reagents for organic chemistry
Organic peroxides
Dioxiranes
Oxidizing agents
Technical Service Bulletin. Technical Service Bulletins (TSBs) are document recommended procedures for repairing vehicles issued by a vehicle manufacturer when there are several occurrences of an unanticipated problem. TSBs can range from vehicle-specific to covering entire product lines and break down the specified repair into a step-by-step process. While sometimes written by engineers employed by OEMs, the majority are authored by the first automotive technician to come up with a repair procedure. Because certain problems may have more than one cause and there is sometimes more than one way to fix a problem, there may be more than one TSB for the same problem.

A major difference between a product recall and a TSB in the automotive industry is that a recall usually evolves out of safety issues at the behest of an organization such as the US National Highway Traffic Safety Administration (NHTSA). The ensuing recall maintenance/repair work is usually done at no charge to the car owner, regardless of the car's warranty status. However, dealers are usually not obliged to call in cars for which TSBs for repairs have been issued. Nor is there a requirement to carry out the TSB repairs with no or reduced charges to the owner, since the manufacturer does not explicitly require the repair to be performed and does not reimburse the dealership for repairs. When the vehicle's manufacturer issues a recall, they require the dealership to perform the repair and will reimburse them for it.

Some benefits of an automotive TSB are that by widely circulating among dealership service departments and mechanics an engineering-level description and solution for a problem common to type, year, make or model of car, a well-managed TSB process can save technicians troubleshooting time; provide organized, itemized repair procedures; and standardize the repair process. This can also enhance the quality of the maintenance since it tends to be supported by repair history and high-level diagnostic procedure decisions.

References

External links
 National Highway Traffic Safety Administration's TSB search page

Motor vehicle maintenance