omniomni/omni-engineering huggingface dataset:
Solid compression. In computing, solid compression is a method for data compression of multiple files, wherein all the uncompressed files are concatenated and treated as a single data block. Such an archive is called a solid archive. It is used natively in the 7z and RAR formats, as well as indirectly in tar-based formats such as .tar.gz and .tar.bz2. By contrast, the ZIP format is not solid because it stores separately compressed files (though solid compression can be emulated for small archives by combining the files into an uncompressed archive file and then compressing that archive file inside a second compressed ZIP file).

Explanation
Compressed file formats often feature both compression (storing the data in a small space) and archiving (storing multiple files and metadata in a single file). One can combine these in two natural ways:

 compress the individual files, and then archive into a single file;
 archive into a single data block, and then compress.

The order matters (these operations do not commute), and the latter is solid compression.

In Unix, compression and archiving are traditionally separate operations, which allows one to understand this distinction:

 Compressing individual files and then archiving would be a tar  gzip-compressed files this is very uncommon.
 Archiving various uncompressed files via tar and  compressing yields a compressed archive: a .tar.gz file this is solid compression.

A rough graphical representation:
In this example, three files each have a common part with the same information, a unique part with information not in the other files, and an "air" part with low-entropy and accordingly well-compressible information.

original file A

original file B

original file C

non solid archive:

solid archive:

Rationale

Benefits
Solid compression allows for much better compression rates when all the files are similar, which is often the case if they are of the same file format. It can also be efficient when archiving a large number of small files.

Costs
On the other hand, getting a single file out of a solid archive requires processing all the files before it, so modifying solid archives could be slow and inconvenient. On newer formats such as 7-zip, there is a solid block size option that allows for the concatenated data block to be split into individually-compressed smaller blocks, so that only a limited amount of data in the block must be processed in order to extract one file. Parameters control the maximum solid block window size, the number of files in a block, and whether blocks are separated by file extension.

Additionally, if the archive becomes even slightly damaged, some of the data (sometimes even all data) after the damaged part in the block can be unusable (depending on the compression and archiving format), whereas in a non-solid archive format, usually only one file is unusable and the subsequent files can usually still be extracted.

References

Data compression
American General Aviation Corporation. American General Aircraft Corporation, also known as AGAC, was an aircraft manufacturer based in Greenville, Mississippi, between the late 1980s and 1993.

The company was established in about 1988 to place the Gulfstream American AA-5B Tiger back in production. The Tiger had originally been produced by Grumman American and then later by Gulfstream American with production ending in 1979. The Tiger remained a popular aircraft amongst pilots and owners and American General sought to capitalize on that popularity with the production of new aircraft.

American General actually carried out a redesign of the Tiger, introducing many improvements over the older AA-5B, including a new split nose bowl that could be removed without removing the propeller, a new instrument panel, improved exterior lighting, a new fuel indication system, a 28 volt electrical system replacing the previous 12 volt system, a new style throttle quadrant and improvements to the heat and ventilation systems. These were enough changes that the FAA required an amended type certificate. This added to the time required to get the aircraft into production and the cost of doing so. The redesigned aircraft was known as the American General AG-5B Tiger.

The newly redesigned aircraft was well received by the civil aviation community. Many aircraft reviewers at that time wrote that the AG-5B was an evolutionary improvement over the previous production AA-5B Tigers and a worthy successor.

The company commenced production with the 1990 model year, building 13 production aircraft that year. 87 aircraft were produced in 1991 and 54 in 1992. The final year of production was 1992 when 24 were produced before the company closed its doors. Total AG-5B production at American General was 181, including prototypes.

Production of the AG-5B design was taken up again in 2001 by a new company, Tiger Aircraft.

Aircraft by date
 American General AG-5B Tiger (1990)

Related aircraft
 Bede BD-1
 AA-1
 AA-2
 AA-5
 GA-7

External links
 Tiger Aircraft Corporate website

Defunct companies based in Mississippi
Defunct aircraft manufacturers of the United States
American companies established in 1988
Manufacturing companies established in 1988
American companies disestablished in 1993
Manufacturing companies disestablished in 1993
Defunct manufacturing companies based in Mississippi
Rheopecty. In continuum mechanics, rheopecty or rheopexy is the rare property of some non-Newtonian fluids to show a time-dependent increase in viscosity (time-dependent viscosity); the longer the fluid undergoes shearing force, the higher its viscosity. Rheopectic fluids, such as some lubricants, thicken or solidify when shaken. The opposite and much more common type of behaviour, in which fluids become less viscous the longer they undergo shear, is called thixotropy.

Examples of rheopectic fluids include gypsum pastes, printer inks, and synovial fluid.

There is ongoing research into new ways to make and use rheopectic materials. There is great interest in possible military uses of this technology. Moreover, the high end of the sports market has also begun to respond to it. Body armor and combat vehicle armor are key areas where efforts are being made to use rheopectic materials. Work is also being done to use these materials in other kinds of protective equipment, which is seen as potentially useful to reduce apparent impact stress in athletics, motor sports, transportation accidents, and all forms of parachuting. In particular, footwear with rheopectic shock absorption is being pursued as a dual-use technology  that can provide better support to those who must frequently run, leap, climb, or descend.

Confusion between rheopectic and dilatant fluids
An incorrect example often used to demonstrate rheopecty is cornstarch mixed with water (sometimes called oobleck), which is a very viscous, white fluid. It is a cheap and simple demonstration, which can be picked up by hand as a semi-solid, but flows easily when not under pressure. However, oobleck is actually a dilatant fluid, since it does not show the time-dependent, shear-induced change required in order to be labeled rheopectic. These terms are often and easily confused since the terms are rarely used; a true rheopectic fluid would at first be liquid when shaken, becoming thicker as shaking continued.

Just as the opposite behaviour of becoming thinner with time is thixotropism (time dependent pseudoplastic behaviour), rheopectic behaviour may be described as time-dependent dilatant behaviour.

See also
 Time-dependent viscosity
 Thixotropy: The longer a fluid is subjected to a shear force, the lower its viscosity. It is a time-dependent shear thinning behavior.
 Shear thickening: Similar to rheopecty, but independent of the passage of time.
 Shear thinning: Similar to thixotropy, but independent of the passage of time.

References

Non-Newtonian fluids
Jordan Falcon. The Jordan Falcon, a joint venture between the King Abdulla Design and Development Bureau and Jordan Aerospace Industries, is a compact tactical unmanned aerial vehicle (UAV) capable of performing a wide range of aerial robotic applications. It performs real-time day and night reconnaissance, remote sensing, surveillance and target acquisition up to a range of 50 km.

The Jordan Falcon is powered by a quiet 200cc two-stroke engine burning a conventional gas/oil mixture with fuel for a 4-hour flight stored in the aircraft's fuselage tank. Additional fuel tanks may be equipped to provide added capacity. A generator and an emergency onboard batteries power the aircraft and payload.

Its heading, altitude, airspeed and GPS waypoint navigation are fully controlled by an autopilot. A 5-watt video/telemetry microwave datalink transmits real-time imagery and vehicle telemetry back from the UAV at ranges up to 50 km.

Specifications
 Stall speed, SLS                      - 80 km/h (50 mph)
 Maximum speed, SLS                    - 180 km/h (110 mph)
 Cruise speed, SLS                     - 120 km/h (75 mph)
 Operational maximum range (still air) - 450 km/h
 Operational endurance                 - 4 h
 MGTOW                                 - 60 kg (132 lb)
 Empty weight                          - 40 kg (88 lb)
 Maximum fuel                          - 14 kg (30 lb)
 Payload                               - 6 kg (13 lb)

References

Unmanned aerial vehicles of Jordan
Aircraft manufactured in Jordan
Comp Air 12. The Comp Air CA12 is a turboprop-powered civil utility aircraft, currently under development. Comp Air is seeking certification. It is configured as a conventional, low-wing monoplane with tricycle undercarriage.  The first flight was on April 14, 2007.

Specifications (as designed)

See also

External links
 

12
2000s United States civil utility aircraft
Single-engined turboprop aircraft
Low-wing aircraft
Single-engined tractor aircraft
Xylyl bromide. Xylyl-bromide, also known as methylbenzyl bromide or T-stoff ('substance-T'), is any member or a mixture of organic chemical compounds with the molecular formula C6H4(CH3)(CH2Br).  The mixture was formerly used as a tear gas and has an odor reminiscent of lilac. All members and the mixture are colourless liquids, although commercial or older samples appear yellowish.

Use as a weapon
Xylyl bromide is an irritant and lachrymatory agent.  It has been incorporated in chemical weapons since the early months of World War I. Some commentators say the first use was in August 1914, when the French attacked German soldiers with tear gas grenades, but the agent used in that incident was more likely to be ethyl bromoacetate, which the French had tested before the war.

The first extensive use of xylyl bromide was the firing by German forces of 18,000 "T-shells" at Russian positions in the Battle of Bolimów in January 1915. The shells were modified 15 cm (6 inch) artillery shells containing an explosive charge and c. 3 kg (7 lb) xylyl bromide. The attack was a complete failure because the winter weather was too cold to permit an effective aerosol, and the agent was either blown back towards the German lines, fell harmlessly to the ground, or was insufficiently concentrated to cause damage. A similar attack at Nieuwpoort in March 1915 was also unsuccessful. Nevertheless, because of its ease of manufacture xylyl bromide was widely used in World War I, in particular as a component of the Germans' Weisskreuz (white cross) mixture.

Structural isomers
Three isomers, collectively referred to by CAS registry number , are:

 CAS RN : o-xylyl bromide (2-methylbenzyl bromide, systematic name 1-(bromomethyl)-2-methylbenzene) (NIST record)
 CAS RN : m-xylyl bromide (3-methylbenzyl bromide, systematic name 1-(bromomethyl)-3-methylbenzene) (NIST record)
 CAS RN : p-xylyl bromide (4-methylbenzyl bromide, systematic name 1-(bromomethyl)-4-methylbenzene) (NIST record)

In the absence of clarification, the name "xylyl bromide" may refer to any one of these isomers or a mixture of all three.

See also
 Chemical weapons in World War I
 Tetrabromo-o-xylene

References

External links
 Hazardous Substances Data Bank (HSDB) record

Organobromides
Lachrymatory agents
World War I chemical weapons
Melges 24. The Melges 24 is an American trailerable sailboat that was designed by Reichel/Pugh as a one-design racer and first built in 1993.

The design became an accepted World Sailing international class in 1997.

Production
The design has been built by Melges Performance Sailboats in the United States, starting in 1993, and remains in production. It also was produced at one time by Devoti Sailing in the Czech Republic. A total of 250 boats had been built by the end of 1994 and more than 900 boats had been completed by 2021.

Design
The Melges 24 is a racing keelboat, built predominantly of fiberglass. It has a fractional sloop rig with a deck-stepped carbon fiber mast. The hull has a nearly-plumb stem, an open reverse transom, a transom-hung rudder controlled by a carbon fiber tiller with an extension and a retractable lifting keel with a weighted bulb. It displaces  and carries  of lead ballast.

The boat has a draft of  with the keel extended. With the keel retracted it can operate in shallow water or be transported on a trailer.

The boat may be fitted with a small  outboard motor for docking and maneuvering. The motor is stored under the cockpit when not in use.

For sailing downwind the design may be equipped with a masthead asymmetrical spinnaker of , flown from a retractable bowsprit. The design has a hull speed of  and a PHRF handicap of 75 to 105.

Typically the boat employs a crew of four sailors, but two to five crew may be carried.

Operational history
The boat is supported by an active class club that organizes racing events, the International Melges 24 Class Association.

The design is raced in over 20 countries on five continents and the class world championships typically attract over 100 boats.

In a 1996 review Darrell Nicholson wrote in Practical Sailor, "if sailboats were defined in human terms, the Melges 24 could easily be described as having the attributes of a precocious three-year-old who hadn't learned to respect her elders. More than likely, she also would be described as being gifted, if a little high strung ... Aside from its plumb bow, narrow beam, flat bottom, hard bilges and open transom, one of the most striking features of the boat's design is the enormous, 13-foot long cockpit, designed to allow crew to move quickly from side to side during tacks, and to position weight in pre-determined spots to maximize boat speed off the breeze."

Events

See also
List of sailing boat types

References

External links

Melges 24
Keelboats
1990s sailboat type designs
Sailing yachts
Trailer sailers
One-design sailing classes
Classes of World Sailing
Sailboat type designs by Reichel/Pugh
Sailboat types built by Melges Performance Sailboats
Sailboat types built by Devoti Sailing
Leo Graetz. Leo Graetz (26 September 1856 – 12 November 1941) was a German physicist.  He was born in Breslau, Germany, and was the son of historian Heinrich Graetz.

Graetz was one of the first to investigate the propagation of electromagnetic energy. The Graetz number (Gz), a dimensionless number describing heat flow, is named after him. Also sometimes known by his name is the diode bridge rectifier circuit that was invented by Polish electrotechnician Karol Pollak in 1896 and that was independently invented and published by Leo Graetz in 1897.

In 1880 he confirmed the Stefan–Boltzmann law.

Graetz died in Munich at age 85.

Publications 
 Die Elektrizität und ihre Anwendungen (Electricity and Its Applications), Stuttgart 1903 Digital 17th edition from 1914 by the University and State Library Düsseldorf
 Handbuch der Elektrizität und des Magnetismus (Handbook of Electricity and Magnetism) - 5 volumes, 1918, 1921, 1923, 1920, 1928
 Recent developments in atomic theory, 1922

References 

1856 births
1941 deaths
19th-century German physicists
Scientists from the Province of Silesia
Scientists from Wrocław
German fluid dynamicists
20th-century German physicists
Butterfly net. A butterfly net (sometimes called an aerial insect net) is one of several kinds of nets used to collect insects.  The entire bag of the net is generally constructed from a lightweight mesh to minimize damage to delicate butterfly wings. Other types of nets used in insect collecting include beat nets, aquatic nets, and sweep nets. 

Nets for catching different insects have different mesh sizes. Aquatic nets usually have bigger, more 'open' mesh. Catching small aquatic creatures usually requires an insect net. The mesh is smaller and can capture more.

References

External links
Collecting and Preserving Insects and Mites USDA
Anti Insect Net & Sun Shade Net

Collecting
Butterflies
Nets (devices)
Entomology equipment
Environmental Sampling Equipment
Portlands Energy Centre. The Portlands Energy Centre is a 550-megawatt natural gas electrical generating station in Toronto, Ontario. It is located in the Port Lands area of the Toronto waterfront at 470 Unwin Avenue, adjacent to the site of the decommissioned Hearn Generating Station.

Ownership
The Portlands Energy Centre was originally owned and operated as a 50/50 joint partnership between Ontario Power Generation (OPG) and TransCanada Corporation (now TC Energy). OPG acquired full ownership of the facility in 2020, and it is currently operated by OPG's subsidiary Atura Power.

Technical specifications of the plant
The technical specifications of the plant in the original submission of the environmental review report (a less rigorous form of a full environmental assessment) to the Ministry of the Environment in November 2003 have been significantly altered. This was due to the government instructing Ontario Power Generation to stop participating in projects which use more environmentally acceptable generations systems, such as co-generation.  Originally, the plant was described as two identical 275 MW power train systems, each comprising a 175 MW GE 7FA gas turbine generator, and other equipment. This proposed configuration was capable of producing over 272,000 per hour of steam for district heating.

Power purchase agreement, timing and capital costs
On September 18, 2006, TransCanada issued a press release announcing that Portlands Energy Centre L.P. had signed a 20-year Accelerated Clean Energy Supply (ACES) contract with the Ontario Power Authority for the power output of the PEC.

The plant started delivering 340 MW of power to the City of Toronto in June 2008 in single-cycle operation and was fully operational with an output of 550 MW by the second-quarter 2009.  Total capital costs are expected to reach $730MM.

See also

 Toronto waterfront
 Port Lands
 Toronto Hydro - City owned electricity distribution corporation
 Ontario Power Generation - Provincially owned electricity generation corporation
 Hearn Generating Station - The original electrical generation facility
 Toronto Port Authority - Federal government agency that controls the portlands

References

External links
 Portlands Energy Centre
 Top Plants: Portlands Energy Centre, Ontario, Canada
 Portlands Energy Centre Photos - 2007

Ontario Power Generation
Buildings and structures in Toronto
Natural gas-fired power stations in Ontario
Former joint ventures
TC Energy
2008 establishments in Ontario
Bernardo Vergara. Bernardo "Bernie" M. Vergara (born December 4, 1937) is a Filipino politician and professional civil engineer. He served as Congressman from the lone district of Baguio for three terms from 1992 to 2001, 2010-2013 and as mayor of Baguio for one term from 2001 to 2004.

Early and political career
Vergara is a former Department of Public Works and Highways District Engineer. At a young age of 30, he has been known as the country's youngest District Engineer. He has been in public service since the 1960s and has catapulted the Northern Philippines in particular the La Union and Ilocos areas to its premier state, as it is now today. As District Engineer for La Union, he was then tapped by Former President Ferdinand E. Marcos and Former Tourism Secretary Jose D. Aspiras to lead the Philippine Tourism Authority which he served as general manager from 1978 to 1986.

Through his leadership as congressman, he has been instrumental in the upliftment of Baguio ruined by the July 1990 devastating earthquake. He was awarded as the Philippines' Ten Most Outstanding Congressman for two times during his 9 year-tenure. He is most known for his involvement in the reconstruction of Marcos Highway and magnanimous efforts to improve Baguio's economy by way of extensive infrastructure projects.

Vergara won his 4th term as Congressman for the lone Legislative district of Baguio this 2010 elections, as the candidate of Lakas-Kampi-CMD. His 4th term from 2010 to 2013, makes his over-all tenure 12 years as legislator

Personal life
Vergara lives in Baguio with his wife, Gloria, and their six children.

References

External links
 https://web.archive.org/web/20100614202357/http://bernievergara.com/

1937 births
Living people
People from La Union
People from Baguio
Filipino civil engineers
National University (Philippines) alumni
Nationalist People's Coalition politicians
Lakas–CMD politicians
Members of the House of Representatives of the Philippines from Baguio
Mayors of Baguio
United Nationalist Alliance politicians