omniomni/omni-engineering huggingface dataset:
ALTQ. ALTQ (ALTernate Queueing) is the network scheduler for Berkeley Software Distribution.  ALTQ provides queueing disciplines, and other components related to quality of service (QoS), required to realize resource sharing. It is most commonly implemented on BSD-based routers. ALTQ is included in the base distribution of FreeBSD, NetBSD, and DragonFly BSD, and was integrated into the pf packet filter of OpenBSD but later replaced by a new queueing subsystem (it was deprecated with OpenBSD 5.5 release, and completely removed with 5.6 in 2014).

With ALTQ, packets can be assigned to queues for the purpose of bandwidth control. The scheduler defines the algorithm used to decide which packets get delayed, dropped or sent out immediately. There are five schedulers currently supported in the FreeBSD implementation of ALTQ:

  — Class-based Queueing. Queues attached to an interface build a tree, thus each queue can have further child queues. Each queue can have a priority and a bandwidth assigned. Priority mainly controls the time packets take to get sent out, while bandwidth has primarily effects on throughput.
  — Controlled Delay. Attempts to combat bufferbloat.
  — Fair Queuing. Attempts to fairly distribute bandwidth among all connections.
  — Hierarchical Fair Service Curve. Queues attached to an interface build a tree, thus each queue can have further child queues. Each queue can have a priority and a bandwidth assigned.  Priority mainly controls the time packets take to get sent out, while bandwidth has primarily effects on throughput.
  — Priority Queueing. Queues are flat attached to the interface, thus, queues cannot have further child queues. Each queue has a unique priority assigned, ranging from 0 to 15. Packets in the queue with the highest priority are processed first.

See also

 Traffic shaping
 KAME project

References

External links
ALTQ home 
Configuring ALTQ in OpenBSD 5.4 and earlier
PF and ALTQ documentation by the FreeBSD project
pfSense Documentation ALTQ Scheduler Types on pfSense Firewall

Network performance
Network scheduling algorithms
Quality of service
Free software programmed in C
Operating system technology
I/O scheduling
BSD software
FreeBSD
NetBSD
DragonFly BSD
HVDC Rihand–Delhi. The HVDC Rihand–Delhi is a HVDC connection between Rihand and Dadri (near Delhi) in India, put into service in 1990.
It connects the 3,000 MW coal-based Rihand Thermal Power Station in Uttar Pradesh to the northern region of India. The project has an  long bipolar overhead line. The transmission voltage is 500 kV and the maximum transmission power is 1,500 megawatts. The project was built by ABB.

On 24 June 1990, during the commissioning of the scheme, a complete quadrivalve of the Rihand converter station was destroyed, and the other two quadrivalves of the same pole badly damaged, by a fire which is believed to have started as a result of a loose connection on a grading capacitor. The fire was so intense that the valve hall was structurally damaged, and the affected converter was out of action for 18 months. Similar incidents on the Itaipu project in 1989 and the Sylmar Converter Station of the Pacific DC Intertie scheme in 1993 led to CIGRÉ publishing guidelines on the design of thyristor valves in order to reduce fire risks. In 1996 the National Fire Protection Association published NFPA 850{2} to further enhance fire prevention and protection guidelines base on input from the HVDC manufacturers and utility owners. Since that time, there have been no catastrophic fire incidents in the US or internationally.

HVDC Rihand-Dadri crosses north of E. Manjhpati the HVDC Ballia-Bhiwadi. This is the first crossing of two independent HVDC lines in India and one of the few worldwide.

Sites

References

External links 

 Power Grid Corporation of India
 ABB Group
 RIHAND - DELHI HVDC PROJECT
 Rihand-Delhi HVDC Scheme - Geographic Map

1990 establishments in Uttar Pradesh
HVDC transmission lines
Electric power transmission infrastructure in India
Energy in Uttar Pradesh
Energy infrastructure completed in 1990
20th-century architecture in India
Kolbe–Schmitt reaction. The Kolbe–Schmitt reaction or Kolbe process (named after Hermann Kolbe and Rudolf Schmitt) is a carboxylation chemical reaction that proceeds by treating phenol with sodium hydroxide to form sodium phenoxide, then heating sodium phenoxide with carbon dioxide under pressure (100 atm, 125 °C), then treating the product with sulfuric acid. The final product is an aromatic hydroxy acid which is also known as salicylic acid (the precursor to aspirin).

By using potassium hydroxide, 4-hydroxybenzoic acid is accessible, an important precursor for the versatile paraben class of biocides used e.g. in personal care products.

The methodology is also used in the industrial synthesis of 3-hydroxy-2-naphthoic acid;  the regiochemistry of the carboxylation in this case is sensitive to temperature.

Reaction mechanism
The Kolbe–Schmitt reaction proceeds via the nucleophilic addition of a phenoxide, classically sodium phenoxide (NaOC6H5), to carbon dioxide to give the salicylate.
The final step is the reaction (protonation) of the salicylate anion with an acid to form the desired salicylic acids (ortho- and para- isomers).

(animation)

References 

Addition reactions
Carbon-carbon bond forming reactions
Industrial processes
Name reactions
Möbius resistor. A Möbius resistor is an electrical component made up of two conductive surfaces separated by a dielectric material,  twisted 180° and connected to form a Möbius strip. As with the Möbius strip, once the Möbius resistor is connected up in this way it effectively has only one side and one continuous surface. 
Its connectors are attached at the same point on the circumference but on opposite surfaces. 
It provides a resistor with a reduced self-inductance, meaning that it can resist the flow of electricity in a more frequency-independent manner.

Transmission line
Due to a symmetrical construction, the voltage between the conductive surfaces of the Möbius resistor in the point equidistant to the feed point is exactly zero. This means that a short circuit placed at this point doesn't influence the characteristics of the device. Thus, the Möbius resistor can be thought of as two shorted lossy (resistive) transmission line segments, connected in parallel at the resistor's feed point.

Patents
 , Möbius capacitor
 , Non-inductive electrical resistor
 , Apparatus and method for minimizing electromagnetic emissions of technical emitters Dietrich Reichwein

See also
 Ayrton–Perry winding

References

External links
 R.L. Davis, Noninductive Resistor, collection of articles at rexresearch.com

Resistive components
Martin Allen (entrepreneur). Martin A. Allen (1931–2009) was the chairman,  co-founder, president, and largest individual stockholder (2,272,866 shares) of Computervision Corp. Its first product, CADDS-1, was aimed at the printed circuit layout, and 2-D drafting markets.

Career

Computervision Corp. 
Martin (Marty) A. Allen co-founded Computervision Corp. in 1969 with Philippe Villers in Boston, MA. In 1980 he led an effort to create the first Graphics Processing Unit (GPU), build to handle 2-D and 3-D modeling.

Retirement 
Allen netted $34 million when, at age 57, he sold Computervision Corp. to Prime Computer Inc. on 29 January 1988.

Early life and education 
Born in Des Moines, Iowa, Allen was raised in California. He attended the University of California, Berkeley and obtained a degree in engineering.

References

1931 births
2009 deaths
20th-century American businesspeople
American computer businesspeople
Graphite bomb. A graphite bomb is intended to be a non-lethal weapon used to disable an electrical grid. The bomb works by spreading a dense cloud of extremely fine, chemically treated carbon filaments over air-insulated high voltage installations like transformers and power lines, causing short-circuits and subsequent disruption of the electricity supply in an area, a region or even an entire small country. The weapon is sometimes referred to as a blackout bomb or soft bomb because its direct effects are largely confined to the targeted electrical power facility, with minimal risk of immediate collateral damage. However, since water supply systems and sewage treatment systems depend on electricity, widespread outbreaks of cholera and other waterborne diseases, causing large numbers of civilian deaths, have in the past been the direct consequence of this bomb's use.

Bomb structure
A graphite bomb consists of a metal canister that is filled with spools of graphite filament and an explosive device. The American version is typically labeled "BLU-114/B". BLU is a military acronym for "bomb live unit". Once the bomb is ejected from a plane or missile, the device's explosive is activated. The explosive detonates ejecting the graphite filaments from the metal canister. The filaments unwind and drift down until (hopefully in the intention of the attacker) some will straddle high voltage power distribution lines, usually consisting of several not insulated wires, and establish an electrical connection between two or more wires by resting on them. Graphite is a sufficiently good conductor and the current flowing in the fiber immediately vaporizes it, creating a thin channel of gas, ionized by the high temperature, around the space previously occupied by the fiber. The ionized gas, also a conductor, allows more current to flow, raising the temperature further and creating a bigger channel of ionized gas until the high voltage line is effectively short circuited. At this point either the protection of the line cuts the power, or the line fails due to overcurrent. In both cases the power distribution is cut.

Uses
South Korea has announced plans to build graphite bombs for use against North Korea to paralyse its electric grid in the event of a new war breaking out on the Korean Peninsula, subject to funding from the country's finance ministry. The weapons have been developed by South Korea's Agency for Defense Development, Yonhap news agency reported, as one element of the kill chain pre-emptive strike program. Contractors were selected in 2020 and the weapons are intended to be delivered by 2024.

Countermeasures

The effects of a graphite bomb can be mitigated by providing insulation. However, most power lines are not insulated in practice due to the high costs involved.

See also
Electromagnetic pulse
Operation Outward

References

External links
 

Non-lethal weapons
Bombs
Methylaluminoxane. Methylaluminoxane, commonly called MAO, is a mixture of organoaluminium compounds with the approximate formula (Al(CH3)O)n. It is usually encountered as a solution in (aromatic) solvents, commonly toluene but also xylene, cumene, or mesitylene, Used in large excess, it activates precatalysts for alkene polymerization.

Preparation and structure

MAO is prepared by the incomplete hydrolysis of trimethylaluminium, as indicated by this idealized equation:
n Al(CH3)3  +  n H2O  →  (Al(CH3)O)n  +  2n CH4
After many years of study, single crystals of an active MAO were analyzed by X-ray crystallography.  The molecule adopts a ruffled sheet of tetrahedral Al centers linked by triply bridging oxides.

Uses
MAO is well known as catalyst activator for olefin polymerizations by homogeneous catalysis.  In traditional Ziegler–Natta catalysis, supported titanium trichloride is activated by treatment with trimethylaluminium (TMA). TMA only weakly activates homogeneous precatalysts, such as zirconocene dichloride.  In the mid-1970s Kaminsky discovered that metallocene dichlorides can be activated by MAO (see Kaminsky catalyst). The effect was discovered when a small amount of water was found to enhance the activity in the Ziegler–Natta system.  

MAO serves multiple functions in the activation process. First it alkylates the metal-chloride pre-catalyst species giving Ti/Zr-methyl intermediates.  Second, it abstracts a ligand from the methylated precatalysts, forming an electrophilic, coordinatively unsaturated catalysts that can undergo ethylene insertion. This activated catalyst is an ion pair between a cationic catalyst and an weakly basic MAO-derived anion.   MAO also functions as scavenger for protic impurities.

Previous studies
Diverse mechanisms have been proposed for the formation of MAO and many structures as well.

See also
Aluminoxane

References 

Polymer chemistry
Aluminium compounds
Catalysts
Pyrophoric materials
Methyl compounds
Solderability. The solderability of a substrate is a measure of the ease with which a soldered joint can be made to that material. Good solderability requires wetting (low contact angle) of the substrate by the solder.



Of metals

Solderability varies depending on the type of solder alloy under discussion. The discussion that follows applies only to unspecified electronic solders (which may include solders that contain lead, now banned for use in nearly all electronic equipment made or sold in the EU). Solderability when using lead-free alloys can differ significantly from solderability when using lead based alloys.

Noble metals may be easy to solder but they have brittle joints. The metals in the good category require a large amount of heat therefore oxidation is an issue. To overcome this a flux is required. For carbon steel, low alloy steel, zinc, and nickel the presence of sulfur creates a brittle joint; lower temperatures are used to minimize this problem. The oxides on the surface of aluminium cause wetting issues and special solders must be used to prevent galvanic corrosion issues. Stainless steel and high alloy steel have a low solderability because the chromium alloying element creates oxides that require aggressive fluxes. The only way that the final category of metals can be soldered is by pre-plating them in a metal that is solderable.

Testing solderability
Both quantitative and qualitative tests for solderability exist.
The two most common testing methods are the 'dip and look' method and wetting balance analysis. In both of these tests, the soldered pieces undergo an accelerated aging process before being tested for solderability, to take into consideration the time a component was in storage prior to mounting to final assembly. The dip and look method is a qualitative test. One form of it is specified as Mil-Std-883 Method 2003. On the other hand, the wetting balance analysis is a quantitative test that measures the wetting forces between molten solder and the test surface as a function of time.

References

Soldering
Blobotics. Blobotics is a term describing research into chemical-based computer processors based on ions rather than electrons. Andrew Adamatzky, a computer scientist at the University of the West of England, Bristol used the term in an article in New Scientist March 28, 2005 .  

The aim is to create 'liquid logic gates' which would be 'infinitely reconfigurable and self-healing'.  The process relies on the Belousov–Zhabotinsky reaction, a repeating cycle of three separate sets of reactions.  Such a processor could form the basis of a robot which, using artificial sensors, interact with its surroundings in a way which mimics living creatures. 

The coining of the term was featured by ABC radio in Australia .

References

 Motoike I., Adamatzky A. "Three-valued logic gates in reaction-diffusion excitable media." Chaos, Solitons & Fractals 24 (2005) 107-114
 Adamatzky, A. "Collision-based computing in Belousov–Zhabotinsky medium." Chaos, Solitons & Fractals 21:(5), (2004), p1259-1264  

Robotics
Classes of computers
Celestair. Celestair is an alliance of Air Burkina, Air Mali, and Air Uganda.

Fleet 
Celestair Group represents an alliance of three airlines under the Aga Khan Fund for Economic Development, AKFED, and  benefits from technical and operative support from other airlines owned by the Aga Khan, such as Meridiana and Eurofly of Italy.  
The Celestair fleet consists of the following aircraft (as of March 2009 ): 
8 McDonnell Douglas MD-87 (three aircraft are operated for Air Uganda, two aircraft are operated for Air Burkina, and two aircraft are operated for Air Mali).  
At least 1 Bombardier CRJ (seen July 2014)

Members

External links 
Celestair Fleet

Aga Khan Development Network
Airline holding companies
CoCoA. CoCoA (Computations in Commutative Algebra)
is a free computer algebra system developed by the University of Genova, Italy, used to compute with numbers and polynomials. The CoCoA Library (CoCoALib) 
is available under GNU General Public License. CoCoA has been ported to many operating systems including Macintosh on PPC and x86, Linux on x86, Unix x86-64 & PPC, Solaris on SPARC and Windows on x86.
CoCoA is mainly used by researchers (see citations at
and), 
but can be useful even for "simple" computations.

CoCoA's features include:
 Very big integers and rational numbers using the GNU Multi-Precision Library
 Multivariate Polynomials
 Gröbner basis
 User interfaces: text; Emacs-based; Qt-based

It is able to perform simple and sophisticated operations on multivariate polynomials and on various data related to them (ideals, modules, matrices, rational functions). For example, it can readily compute Gröbner basis, syzygies and minimal free resolutions, intersection, division, the radical of an ideal, the ideal of zero-dimensional schemes, Poincaré series and Hilbert functions, factorization of polynomials, and toric ideals. The capabilities of CoCoA and the flexibility of its use are further enhanced by the dedicated high-level programming language.

Its mathematical core, CoCoALib, has been designed as an open source C++ library, focussing on ease of use and flexibility.

CoCoALib is based on GNU Multi-Precision Library.

CoCoALib is used by 
ApCoCoA
and
NmzIntegrate

See also

List of computer algebra systems
Standard Template Library

References

External links

ApCoCoA, an extension of CoCoA

Computer algebra system software for Linux
Free computer algebra systems
Science software that uses Qt
Vacancy defect. In crystallography, a vacancy is a type of point defect in a crystal where an atom is missing from one of the lattice sites. Crystals inherently possess imperfections, sometimes referred to as crystallographic defects. 

Vacancies occur naturally in all crystalline materials. At any given temperature, up to the melting point of the material, there is an equilibrium concentration (ratio of vacant lattice sites to those containing atoms). At the melting point of some metals the ratio can be approximately 1:1000. This temperature dependence can be modelled by

where  is the vacancy concentration,  is the energy required for vacancy formation,  is the Boltzmann constant,  is the absolute temperature, and  is the concentration of atomic sites i.e.

where  is density,  the Avogadro constant, and  the molar mass.

It is the simplest point defect. In this system, an atom is missing from its regular atomic site. Vacancies are formed during solidification due to vibration of atoms, local rearrangement of atoms, plastic deformation and ionic bombardments.

The creation of a vacancy can be simply modeled by considering the energy required to break the bonds between an atom inside the crystal and its nearest neighbor atoms. Once that atom is removed from the lattice site, it is put back on the surface of the crystal and some energy is retrieved because new bonds are established with other atoms on the surface. However, there is a net input of energy because there are fewer bonds between surface atoms than between atoms in the interior of the crystal.

Material physics
In most applications vacancy defects are irrelevant to the intended purpose of a material, as they are either too few or spaced throughout a multi-dimensional space in such a way that force or charge can move around the vacancy. In the case of more constrained structures like carbon nanotubes however, vacancies and other crystalline defects can significantly weaken the material.

See also 
Crystallographic defect
Schottky defect
Frenkel defect

References

External links 
Crystalline Defects in Silicon

Crystallographic defects
Concrete bridge. Concrete bridges are a type of bridge, constructed out of concrete. They started to appear widely in the early 20th century.

History 

Unreinforced concrete has been used in bridge construction since antiquity: the Romans incorporated concrete cores into a number of their masonry bridges and aqueducts, along with constructing spanning water conduits of concrete. From the late 18th century cast iron framed bridges may have had an unreinforced cast concrete deck, or had their structure encased in concrete, for example the Homersfield Bridge, constructed between 1869 and 1870, between the English counties of Suffolk and Norfolk. In 1873, Frenchman Joseph Monier obtained a French patent for a method of iron-wire reinforced concrete bridge construction; his first iron-wire reinforced concrete bridge was constructed across the moat of the marquis de Tillièrein's :fr:Château de Chazelet, in 1875. This and all later bridges made according to Monier's system patterned the construction of previously used stone bridges. Their main structural unit was an arch barrel. All barrel sections were reinforced similarly, regardless of the forces acting on it.

The longest steel reinforced bridge, in 2024, is the  Tian'e Longtan Bridge, Guangxi Zhuang, China.

The US's longest unreinforced concrete span, is the  arch of the, 1910, Rocky River Bridge in Cleveland, Ohio.

Early extant examples include:

Finland 
 
 Savisilta "clay bridge", Ylivieska, the second oldest concrete bridge in Finland. (reinforced concrete, constructed 1912).

France
 Pont du jardin des plantes, Grenoble, foorbridge (cast concrete, constructed 1855)
 Bridge across the moat at Château de Chazelet (iron-wire reinforced concrete, constructed 1875)

United Kingdom 
 Homersfield Bridge, River Waveney, England (cast and wrought iron reinforced, span , constructed 1869-1870)
 Axmouth Bridge, on the River Axe at Seaton, Devon (unreinforced, middle span , opened 1877)
 Glenfinnan Viaduct, Scotland (unreinforced, twenty-one  spans, constructed 1897–1901)
 Waterloo Bridge (reinforced cast concrete, longest span , opened 1942)

United States 
 Alvord Lake Bridge, Golden Gate Park, San Francisco (reinforced concrete,  span, 1889).
 Walnut Lane Bridge, Philadelphia, PA (unreinforced concrete,  span, 1908)
 Rocky River Bridge, Cleveland, Ohio (unreinforced concrete,  span, 1910)

References 

 
Bridges
Arne Asplund. Dr. Arne Asplund (1903 – 1993) was a Swedish inventor. He invented the Defibrator pulping refiner and the defibrator-method (also called Asplund-method) for pulping wooden chips in 1930s. His invention resulted in the company AB Defibrator in Stockholm which was merged with Sunds AB to form Sunds Defibrator in 1979.

Asplund was rewarded the Gold medal (Guldmedaljen) of the Royal Swedish Academy of Engineering Sciences (IVA) in 1947 for the invention and his further development of the defibrator-method for pulping wood and other fibre rich materials. He was later rewarded the Great gold medal (Stora guldmedaljen) from IVA in 1969 for his efforts on defibration technology. In 2014 Asplund was inducted to the Paper Industry International Hall of Fame.

Arne Asplund Mechanical Pulping Award 
The annual Arne Asplund Mechanical Pulping Award, was established in 1985 to commemorate Asplund’s contributions to the pulp and paper industry.

References 

1903 births
1993 deaths
20th-century Swedish engineers
20th-century Swedish inventors