omniomni/omni-engineering huggingface dataset:
Nodal admittance matrix. In power engineering, nodal admittance matrix (or just admittance matrix) is an N x N matrix describing a linear power system with N buses.  It represents the nodal admittance of the buses in a power system.  In realistic systems which contain thousands of buses, the admittance matrix is quite sparse. Each bus in a real power system is usually connected to only a few other buses through the transmission lines.  The nodal admittance matrix is used in the formulation of the power flow problem.

Construction from a single line diagram 

The nodal admittance matrix of a power system is a form of Laplacian matrix of the nodal admittance diagram of the power system, which is derived by the application of Kirchhoff's laws to the admittance diagram of the power system. Starting from the single line diagram of a power system, the nodal admittance diagram is derived by:

 replacing each line in the diagram with its equivalent admittance, and
 converting all voltage sources to their equivalent current source.

Consider an admittance graph with  buses. The vector of bus voltages, , is an  vector where  is the voltage of bus , and vector of bus current injections, , is an  vector where  is the cumulative current injected at bus  by all loads and sources connected to the bus. The admittance between buses  and  is a complex number , and is the sum of the admittance of all lines connecting busses  and . The admittance between the bus  and ground is , and is the sum of the admittance of all the loads connected to bus .

Consider the current injection, , into bus . Applying Kirchhoff's current law

where  is the current from bus  to bus  for  and  is the current from bus  to ground through the bus load. Applying Ohm's law to the admittance diagram, the bus voltages and the line and load currents are linked by the relation

Therefore,

This relation can be written succinctly in matrix form using the admittance matrix. The nodal admittance matrix  is a  matrix such that bus voltage and current injection satisfy Ohm's law

in vector format. The entries of  are then determined by the equations for the current injections into buses, resulting in

As an example, consider the admittance diagram of a fully connected three bus network of figure 1. The admittance matrix derived from the three bus network in the figure is:

The diagonal entries  are called the self-admittances of the network nodes. The non-diagonal entries are the mutual admittances of the nodes corresponding to the subscripts of the entry. The admittance matrix  is typically a symmetric matrix as . However, extensions of the line model may make  asymmetrical. For instance, modeling phase-shifting transformers, results in a Hermitian admittance matrix.

Applications 

The admittance matrix is most often used in the formulation of the power flow problem.

See also 
 Admittance parameters
 Nodal analysis
 Zbus

References

External links 
A C/C++ Program and Source Code for Computing Ybus and Zbus Matrices

Electrical engineering
Electric power
I80. I80 or variation, may refer to:

 Interstate 80 (I-80), a U.S. highway
 Aérotrain I80, a hovertrain
 Cascade Kasperwing I-80, an ultralight motorglider
 , a WWII British Royal Navy Clemson-class destroyer

See also

 Watt/I-80 station, Sacramento, California
 80i
Lead telluride. Lead telluride is a compound of lead and tellurium (PbTe). It crystallizes in the NaCl crystal structure with Pb atoms occupying the cation and Te forming the anionic lattice. It is a narrow gap semiconductor with a band gap of 0.32 eV. It occurs naturally as the mineral altaite.

Properties 
 Dielectric constant ~1000.
 Electron Effective mass ~ 0.01me
 Hole mobility, μp = 600 cm2 V−1 s−1 (0 K); 4000 cm2 V−1 s−1 (300 K)

Applications 
PbTe has proven to be a very important intermediate thermoelectric material. The performance of thermoelectric materials can be evaluated by the figure of merit,  , in which  is the Seebeck coefficient,  is the electrical conductivity and  is the thermal conductivity. In order to improve the thermoelectric performance of materials, the power factor () needs to be maximized and the thermal conductivity needs to be minimized.

The PbTe system can be optimized for power generation applications by improving the power factor via band engineering. It can be doped either n-type or p-type with appropriate dopants. Halogens are often used as n-type doping agents. PbCl2, PbBr2 and PbI2 are commonly used to produce donor centers. Other n-type doping agents such as Bi2Te3, TaTe2, MnTe2, will substitute for Pb and create uncharged vacant Pb-sites. These vacant sites are subsequently filled by atoms from the lead excess and the valence electrons of these vacant atoms will diffuse through crystal. Common p-type doping agents are Na2Te, K2Te and Ag2Te. They substitute for Te and create vacant uncharged Te sites. These sites are filled by Te atoms which are ionized to create additional positive holes. With band gap engineering, the maximum zT of PbTe has been reported to be 0.8 - 1.0 at ~650K.

Collaborations at Northwestern University boosted the zT of PbTe by significantly reducing its thermal conductivity using ‘all-scale hierarchical architecturing'. With this approach, point defects, nanoscale precipitates and mesoscale grain boundaries are introduced as effective scattering centers for phonons with different mean free paths, without affecting charge carrier transport. By applying this method, the record value for zT of PbTe that has been achieved in Na doped PbTe-SrTe system is approximately 2.2.

In addition, PbTe is also often alloyed with tin to make lead tin telluride, which is used as an infrared detector material.

See also 
 Yellow Duckling, which used a lead telluride sensor to make the first infrared linescan camera

References

External links 
 National Pollutant Inventory Lead and compounds fact sheet
 Webelements

Tellurides
Lead(II) compounds
IV-VI semiconductors
Thermoelectricity
Rock salt crystal structure
Rolls-Royce/JAEC RJ500. The Rolls-Royce/JAEC RJ500 was a  civil turbofan which Rolls-Royce and the Japanese Aero Engine Corporation (JAEC) consortium hoped to develop for aircraft like the Boeing 737-300 and the McDonnell Douglas MD-80.

A single-stage fan, driven by a three-stage LP turbine, supercharged the nine-stage HP compressor, which was driven by a two-stage air-cooled HP turbine.  The combustor was annular and the exhaust separate jets.  The HP compressor was based on a scale-up of the Rolls-Royce RB401 HP compressor, with a ninth stage added at the rear.  Fan diameter was restricted to , because of the relatively short undercarriage of the 737. Even then, the engine nacelle required an oblate shape so as to improve ground clearance.

Although two prototype engines were built and ground tested, the project was cancelled in the early 1980s.

Specifications (RJ500)

See also

References
Notes

Bibliography
 
 Gunston, Bill. Rolls-Royce Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. 

1980s turbofan engines
Rolls-Royce RB401. The Rolls-Royce RB.401 was a British two-spool business jet engine which Rolls-Royce started to develop in the mid-1970s as a replacement for the Viper. RB.401-06 prototype engines were already being manufactured when a decision to develop the higher thrust RB.401-07 was taken. 

Although ground testing of both the -06 and -07 continued into the early 1980s, a lack of funds caused the project to be cancelled.

Design and development
Although the basic configuration of both engines was almost identical, the -07 variant had a larger fan diameter. The -06 version HP compressor was based on the eight-stage version of the RC34B research compressor, unscaled, whereas the -07 was a scaled-up unit. A single stage fan, driven by a two-stage LP turbine, supercharged the HP compressor which was driven by the single stage transonic HP turbine. The combustor was annular and the co-annular exhaust featured a lightweight target type thrust reverser.

Specifications (RB.401-07)

See also

References

Notes

Bibliography

 Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. 
 Taylor, John W.R. Jane's All the World's Aircraft 1984-85., London, Jane's Publishing Company Ltd, 1984. . 

RB401
High-bypass turbofan engines
1970s turbofan engines
Amplitude modulation signalling system. The amplitude modulation signalling system (AMSS or the AM signalling system) is a digital system for adding low bit rate information to an analogue amplitude modulated broadcast signal in the same manner as the Radio Data System (RDS) for frequency modulated (FM) broadcast signals.

This system has been standardized in March 2006 by ETSI (TS 102 386) as an extension to the Digital Radio Mondiale (DRM) system.

Broadcasting 

AMSS data are broadcast from the following transmitters:

 SW
 BBC World Service: 15.575 MHz

Formerly it was also used by:

 LW
 RTL France: 234 kHz

 MW
 Truckradio 531 kHz
 BBC World Service: 648 kHz
 Deutschlandradio Kultur: 990 kHz

External links 
 
 ETSI TS 102 386 V1.2.1 (2006-03) directly from ETSI Publications Download Area (account or free registration required)
 
 

Radio technology
Broadcast engineering
2006 introductions
2006 establishments
AMSS. AMSS may stand for:

Metropolitan Area of San Salvador (Área Metropolitana de San Salvador)
Amarchand & Mangaldas & Suresh A Shroff & Co, an Indian law firm
Amplitude modulation signalling system, a digital system for adding information to AM broadcast signals
Ainsworth's Maternal Sensitivity Scale, a measure of maternal sensitivity
Aeronautical mobile-satellite service
Auto-Moto Association of Serbia, an FIA member organisation
Copper-clad aluminium wire. Copper-clad aluminium wire (CCAW or CCA) is a dual-metal electrical conductor composed of an inner aluminium core and outer copper cladding.

Production
A copper strip is formed into the shape of a cylinder, while it is being wrapped around an aluminum core and the edges of the copper strip are welded together.  The assembly is then pulled through a die, where the cladded wire is squeezed and stretched while also improving the bonding between the copper and the aluminum core.

Uses
The primary applications of this conductor revolve around weight reduction requirements.  These applications include high-quality coils, such as the voice coils in headphones or portable loudspeakers; high frequency coaxial applications, such as RF antennas and cable television distribution cables; and power cables.

CCA was also used in electrical wiring for buildings. The copper/aluminium construction was adopted to avoid some of the problems with aluminium wire yet retain most of the cost advantage. Its low copper content makes it unattractive to copper thieves.

CCA is also seen in counterfeit unshielded twisted pair networking cables. These cables are often less expensive than their full-copper counterparts,  but 
the official specifications such as Category 6 require conductors to be pure copper. This has exposed the manufacturers or installers of cable with fake certification to legal liabilities.

Properties
The properties of copper-clad aluminium wire include:
 Less expensive than a pure copper wire
 Lighter than pure copper
 Higher electrical conductivity than pure aluminium
 Higher strength than aluminium
 Electrical connections typically more reliable than pure aluminium

Disadvantages
 Easily sold as counterfeit copper wire to unaware clients
 Much more prone to mechanical fatigue failure than pure copper wire
 Gets much hotter than pure copper in case of severe overcurrent, such as short circuits, although this is not an issue for code-compliant installations with proper fuses or circuit breakers.

Skin effect
The skin effect forces alternating current to flow on the outer periphery of any wire; in this case, the outer copper cladding of the conductor which has lower resistance than the mostly unused aluminum interior. The better conductor on the outer path causes the wire's resistance at high frequencies, where the skin effect is greater, to approach that of a pure copper wire. This improved conductivity over bare aluminum makes the copper-clad aluminium wire a good fit for radio frequency use. 

The skin effect is similarly exploited in copper-clad steel wire, such as the center conductors of many coaxial cables, which are commonly used for high frequency feedlines with high strength and conductivity requirements.

See also
 Copper conductor
 Graphene-clad wire
 Electroplating
 Galvanization

References

Electrical wiring
Power cables
Aluminium
Copper
Ken Jackson (trade unionist). Sir Kenneth Joseph Jackson (3 March 1937 – 25 July 2024) was a British trade unionist who was the General Secretary of the Amalgamated Engineering and Electrical Union (AEEU) from 1995 until that union's merger with the Manufacturing Science and Finance (MSF) union to form Amicus in 2001. He subsequently became one of the Joint General Secretaries (JGS) of Amicus.

Life and career
Jackson was born and educated in Wigan, Lancashire. He joined the Royal Air Force in 1956 as an electrical technician, and continued in the same profession after re-entering civilian life. In 1966, he was elected as a Branch Secretary in the Electrical Trades Union, later the Electrical, Electronic, Telecommunications and Plumbing Union (EETPU). He became an executive councillor of EETPU in 1987 and its president in 1992. In 1995, following EETPU's incorporation into the AEEU, he became AEEU General Secretary.

Following the merger of AEEU and the Manufacturing, Science and Finance Union (MSF) to form Amicus, Jackson automatically assumed the role of Joint General Secretary of the AEEU Section of Amicus. This position came up for re-election in June 2002 and he was defeated by the then relatively unknown Derek Simpson, who went on to become Amicus General Secretary.

Throughout his career, Jackson was on the right wing of the union movement. He was a vice-president of the Trade Union Committee for European and Transatlantic Understanding (TUCETU), an organisation with close links to NATO. He became a close associate of Labour's then-prime minister Tony Blair, often being described as "Tony Blair's favourite trade unionist", and received a knighthood in 1999, an unusual honour for a trade union leader. His defeat in 2002 occurred at a time when the trade union movement was moving to the left: he found himself at odds with his counterparts in the movement due to his support of issues such as private-public partnerships and the American conduct of the War on Terror. Six union officials had admitted to attempting to rig the election nominating process, but Jackson denied any involvement.

Jackson became chairman of Nirex, a company which formerly managed disposal of nuclear waste, in December 2001, while he was still a JGS of Amicus.

Jackson died on 25 July 2024, at the age of 87.

References

External links

 Guardian biography
 Union official quits in rigged ballot row – The Independent (UK), 12 June 2002
 

1937 births
2024 deaths
General secretaries of Amicus (trade union)
General secretaries of the Amalgamated Engineering and Electrical Union
Presidents of the Amalgamated Engineering and Electrical Union
Knights Bachelor
People from Wigan
Military personnel from the Metropolitan Borough of Wigan
Royal Air Force airmen
20th-century Royal Air Force personnel
Stephen Hyde. Professor Stephen Timothy Hyde is an Australian scientist who was appointed Fellow of the Australian Academy of Science in 2005.

He is professor and also the ARC Federation Fellow in the Department of Applied Mathematics, Research School of Physics, at the Australian National University. He holds the Barry Ninham Chair of Natural Sciences.

His speciality is in the field of theoretical physics: self-assembly of complex materials and systems.

From 1999 to 2002 he was Head of the Department of Applied Mathematics. In 2021 he took up a position at the University of Sydney.

References

Fellows of the Australian Academy of Science
Living people
Academic staff of the Australian National University
Australian physicists
Theoretical physicists
Place of birth missing (living people)
Year of birth missing (living people)
Rancilio. Rancilio is an espresso machine manufacturer, founded in 1927 by Roberto Rancilio in Parabiago, Italy.

Rancilio's earliest machine was 'La Regina' – a vertical boiler machine, similar to the original Bezzera and Victoria Arduino devices in function and gilded 'Belle Epoque' styling.

In 1950, Rancilio released a horizontal boiler machine, the Invicta Horizzontal, showing evidence of the postwar shift toward spare, modern styling. The machine however, still used the same forced-steam brewing method from the early 20th century. By 1953, Rancilio adopted lever piston technology introduced by Gaggia. In 1957, Rancilio released a model which automated the lever process, the H/L Automatica. The company followed new technological trends towards continuous deliver brewing introduced by Faema in 1961. In 1965, Rancilio commissioned design work from industrial designer Marco Zanuso, beginning with the Rancilio Z8, and continuing with the Z9 in 1974.  Rancilio continued with several Z-series machines, with the Z11 being the last.  The S-series machine would become popular in the 1990s, and become well known in the North American marketplace.

In 1997, Rancilio created a home kitchen-sized espresso machine based on their commercial offerings. This was initially only available as a thank-you gift to importers and vendors of Rancilio's restaurant-grade coffee machines. This machine was later sold to consumers as the Silvia. The Silvia is a one group machine with a vibratory pump from ULKA and a single brass boiler that's controlled by 3 thermostats for both steam and hot water. It is frequently sold with its companion Rocky grinder that is available in doserless and dosered models with stepped settings.

In 2001, Rancilio revamped their lineup, introducing the basic Epoca, and the Classe series. In 2011, they introduced a new advanced brewing system for the Classe 9 called Xcelsius, which gives precise control of water temperature during the brewing cycle.

Rancilio made an attempt at a super-automatic machine, the Classe 12, and used cafes in Borders bookstores as a test market. It was deemed a failure, recalled, and abandoned. They subsequently purchased the Swiss Egro brand of super-automatic machines and have built a presence in that market with their Egro One.

In October 2013 Rancilio was acquired by Ali group.

See also 

 Bialetti
 Cimbali
 De'Longhi
 Elektra (espresso machines)
 Faema
 FrancisFrancis
 Gaggia
 La Marzocco
 Saeco
 List of Italian companies

References

External links

Rancilio Official Site

Espresso machines
Home appliance brands
Home appliance manufacturers of Italy
Companies based in Lombardy
Coffee appliance vendors
Manufacturing companies established in 1927
1927 establishments in Italy
Italian brands
Coffee in Italy
Blaise ketone synthesis. The Blaise ketone synthesis (named after Edmond Blaise) is the chemical reaction of acid chlorides with organozinc compounds to give ketones.

The reaction was claimed to bring excellent yields by Blaise, however, investigators failed to obtain better than moderate yields (50%). Thus, the reaction is particularly ineffective in forming ketones from acyl chlorides. The reaction also works with organocuprates. Reviews have been written.

Reaction mechanism
The mechanism is sampled from the proposed mechanism for organocadmium compounds, given that the mechanisms are identical to one another the proposed mechanism for the reaction is the same as the one for organocadmium compounds.

After the oxygen forms a bond with the organozinc compound, R’ shifts to the carbonyl carbon, having chlorine act as a leaving group and removing the negative charge from zinc. The chlorine that left returns to form a bond with zinc, pushing the electrons back on to oxygen and thus forming the ketone.

Variations

Blaise-Maire reaction
The Blaise-Maire reaction is the Blaise ketone synthesis using β-hydroxy acid chlorides to give β-hydroxyketones, which are converted into α,β-unsaturated ketones using sulfuric acid.

Ketone formation from organocadmium compounds
This ketone formation is an identical reaction to the Blaise ketone synthesis. Only instead of organozinc compounds, organocadmium compounds are used and produce higher yields.

See also
Blaise reaction
Negishi coupling

References

  
  
  
  
  
  
  
  
  

Addition reactions
Carbon-carbon bond forming reactions
Name reactions
Organometallic compounds
2-Pyrrolidone. 2-Pyrrolidone, also known as 2-pyrrolidinone or butyrolactam, is an organic compound consisting of a 5-membered lactam, making it the simplest γ-lactam.  It is a colorless liquid that is miscible with water and most common organic solvents.

2-Pyrrolidone itself and it various derivatives, especially N-methylpyrrolidone, have a variety of industrial uses.

Production
2-Pyrrolidone is produced industrially almost exclusively by treating aqueous gamma-butyrolactone with ammonia at a temperature of 250–290 °C and pressures ranging from 0.4–1.4 MPa over solid magnesium silicate catalysts.

The reaction is carried out in a tubular reactor which is packed with the solid catalyst. The latter is arranged as a fixed bed and the reaction is carried out in the vapor phase. Product yields of 75–85% are reached. After subsequent distillation and purification, the desired 2-pyrrolidone is obtained with a purity of 99.5%.

Alternative routes include the catalytic or electrochemical reduction of succinimide, the carbonylation of allylamine, the hydrogenation of succinonitrile under hydrolytic conditions, and the reaction of maleic or succinic anhydride in aqueous ammonia with Pd–Ru-catalysts.

In 2010, the worldwide demand for 2-pyrrolidone was estimated to be 32.000 t. Important manufacturers of 2-pyrrolidone are BASF and ISP (International Speciality Products, now Ashland Inc.).

Uses
2-Pyrrolidone itself is used in inkjet cartridges.

A variety of pharmaceutical drugs are 2-pyrrolidone derivatives, including cotinine, doxapram, povidone, and ethosuximide, and the racetams.

The chemical is an intermediate in the production of the polyvinylpyrrolidone precursor vinylpyrrolidone.

Safety
2-Pyrrolidone is relatively innocuous with an LD50 in the range of grams per kilogram (rats, oral).  It is not mutagenic.  It can be an eye irritant.

References

External links

Amide solvents