omniomni/omni-engineering huggingface dataset:
Cr23C6 crystal structure. {{DISPLAYTITLE:Cr23C6 crystal structure}}

Cr23C6 is the prototypical compound of a common crystal structure, discovered in 1933 as part of the chromium-carbon binary phase diagram. Over 85 known compounds adopt this structure type, which can be described as a NaCl-like packing of chromium cubes and cuboctahedra.

Structure
The space group of this structure is called Fmm (in Hermann–Mauguin notation) or "225" (in the International Tables for Crystallography). It belongs to a cubic crystal system, with Pearson symbol cF116.

The shortest interatomic distances are between carbon and chromium atoms, which is expected on the basis of atomic size. The carbon atoms are in positions that cap each face of the chromium cubes and their coordination environment can be thought of as distorted square antiprisms formed from chromium atoms of both the cubes and the cuboctahedra.

The closest Cr-Cr contacts are between members of a cuboctahedron, and the third closest are between members of a cube. The members of the cube, however, are closer to the 8 chromium atoms in the unit cell that are not part of either polyhedron. The coordination environment of these other atoms can be thought of as distorted Friauf polyhedra composed of chromium atoms, if next-nearest neighbors are included.

Materials
Examples of compounds that form in this structure type include Cr23C6, Mn23C6, and many ternary intermetallic carbides and borides. A few phases of ternary silicides, germanides, and phosphides are also known to exist. In going from the binary to ternary systems, some of the transition metal atoms are substituted by a third element, which can be an alkali metal, alkaline earth metal, rare-earth element, main group element, or another transition metal. This leads to an empirical formula of the form A23−xBxC6. Materials of this kind continue to be studied for potentially interesting magnetic and physical properties.

References

External links
 International Crystal Structure Database

Crystal structure types
Level-sensitive scan design. Within the field of electronics Level-sensitive scan design (LSSD) is part of an integrated circuit manufacturing test process. It is a DFT scan design method which uses separate system and scan clocks to distinguish between normal and test mode. Latches are used in pairs, each has a normal data input, data output and clock for system operation. For test operation, the two latches form a master/slave pair with one scan input, one scan output and non-overlapping scan clocks A and B which are held low during system operation but cause the scan data to be latched when pulsed high during scan.

	  
	 |    |
 Sin ----|S   |
 A ------|>   |
	 |   Q|---+--------------- Q1
 D1 -----|D   |   |
 CLK1 ---|>   |   |
	 ||	  |    
		  |   |	   |
		  +---|S   |
 B -------------------|>   |
		      |	  Q|------ Q2 / SOut
 D2 ------------------|D   |
 CLK2 ----------------|>   |
		      ||

In a single latch LSSD configuration, the second latch is used only for scan operation. Allowing it to be used as a second system latch reduces the silicon overhead.

See also 
 Boundary scan
 In-circuit test
 JTAG

References

Hardware testing
Bushcaddy R-80. The Bushcaddy R-80 is a Canadian ultralight and light-sport aircraft that was designed by Jean Eudes Potvin of Lac Saint-Jean, Quebec in 1994 and produced by his company Club Aeronautique Delisle Incorporated (CADI). It was later built by Canadian Light Aircraft Sales and Service (CLASS) of St. Lazare, Quebec and later Les Cedres, Quebec and now Bushcaddy of Lachute, Quebec.

The R-80 designation indicates that the aircraft was originally designed for a Rotax engine of .

The aircraft is supplied as a kit for amateur construction or as a complete ready-to-fly-aircraft.

Design and development

The aircraft was designed to comply with the Canadian advanced ultralight rules and is also an approved US light-sport aircraft. It features a strut-braced high-wing, a two-seats-in-side-by-side configuration enclosed cockpit, fixed tricycle landing gear or conventional landing gear and a single engine in tractor configuration.

The aircraft is made from 6061-T6 aluminum sheet over a cage of welded aluminum square 6061-T6 aluminum tube. The tail boom is conventional semi-monocoque construction. The non-tapered planform wings have 6061-T6 ribs and spars and employ a NACA 4413 (mod) airfoil. The airfoil modification removes the undercamber on the bottom of the wing, which makes construction easier, without giving up low speed performance. The aircraft's structure uses 2024-T3 aluminium for critical parts where extra strength is required, such as the spar, float and strut attachments as well as other critical components like the rudder horns. The R-80's structure is covered with 6061-T6 sheet of varying thicknesses; wing bottom skins are  inches thick while the top is  inches. The wings are supported by conventional "V" struts. 6061-T6 is predominantly used for its lower cost and also its better corrosion resistance, since many R-80s are flown on floats. Its  span wing has an area of  and does not fit flaps.

Standard engines used on the R-80 include the  Rotax 912UL and the  Rotax 912ULS four-stroke powerplants. The  turbocharged Rotax 914 has also been fitted. The aircraft can also be mounted on floats and skis. Controls include a central "Y" control stick.

Construction time for the R-80 from the factory kit is 1,200 hours.

Variants

CADI R-80 
Original production version built by CADI, about 60 produced.
CLASS R-80 BushCaddy
Version produced by CLASS of Saint-Lazare, Quebec, after buying the rights from Potvin in 1998. Production was later moved to Les Cedres, Quebec. To acknowledge the CADI name the aircraft was named the Bushcaddy as it is capable of carrying "a load of people and freight into the Canadian bush".
Bushcaddy R-80
Current production version produced by Bushcaddy of Lachute, Quebec and later of Cornwall Regional Airport in Summerstown, Ontario, after buying the rights from CLASS in 2011.

Specifications (R-80)

References

External links

Official website

1990s Canadian ultralight aircraft
Homebuilt aircraft
Light-sport aircraft
Single-engined tractor aircraft
Dewar reactivity number. In Hückel theory, a Dewar reactivity number, also known as Dewar number, is a measure of the reactivity in aromatic systems. It is used to quantify the difference in energy between the π-system of the original molecule and the intermediate having the incoming electrophile or nucleophile attached. It can be used to study important transformations such as the nitration of conjugated systems  from a theoretical perspective.

Computation 
The change in energy during the reaction can be derived by allowing the orbitals nearby the site i of attack to interact with the incoming molecule. A secular determinant can be formulated resulting in the equation:

where β is the Huckel interaction parameter and ar and as are the coefficients of the highest energy molecular orbital at nearby sites r and s respectively. Dewar's reactivity number is then defined as .

Clearly, the smaller the value of Ni, the less the destabilization energy in going towards the transition state and the more reactive the site. Thus, by computation of the molecular orbital coefficients it is possible to evaluate Dewar's number for all the sites and establish which one will be the most reactive. This has been shown to correlate well with experimental results.

The method is particularly efficient for alternant hydrocarbons in which the coefficients of the non-bonding orbitals involved are very easy to calculate.

References 

Molecular physics
Theoretical chemistry
Kosmos 1687. Kosmos 1687 ( meaning Cosmos 1687) is a Soviet US-K missile early warning satellite which was launched in 1985 as part of the Soviet military's Oko programme. The satellite is designed to identify missile launches using optical telescopes and infrared sensors.

Kosmos 1687 was launched from Site 16/2 at Plesetsk Cosmodrome in the Russian SSR. A Molniya-M carrier rocket with a 2BL upper stage was used to perform the launch, which took place at 19:23 UTC on 30 September 1985. The launch successfully placed the satellite into a molniya orbit. It subsequently received its Kosmos designation, and the international designator 1985-088A. The United States Space Command assigned it the Satellite Catalog Number 16103.

See also

List of Kosmos satellites (1501–1750)
List of R-7 launches (1985–1989)
1985 in spaceflight
List of Oko satellites

References

Kosmos satellites
1985 in spaceflight
Oko
Spacecraft launched by Molniya-M rockets
Spacecraft launched in 1985
Kosmos 1684. Kosmos 1684 ( meaning Cosmos 1684) is a Soviet US-K missile early warning satellite which was launched in 1985 as part of the Soviet military's Oko programme. The satellite is designed to identify missile launches using optical telescopes and infrared sensors.

Kosmos 1684 was launched from Site 43/4 at Plesetsk Cosmodrome in the Russian SSR. A Molniya-M carrier rocket with a 2BL upper stage was used to perform the launch, which took place at 01:18 UTC on 24 September 1985. The launch successfully placed the satellite into a molniya orbit. It subsequently received its Kosmos designation, and the international designator 1985-084A. The United States Space Command assigned it the Satellite Catalog Number 16064.

See also

List of Kosmos satellites (1501–1750)
List of R-7 launches (1985–1989)
1985 in spaceflight
List of Oko satellites

References

Kosmos satellites
1985 in spaceflight
Oko
Spacecraft launched by Molniya-M rockets
Spacecraft launched in 1985
FSE Engineering Group. FSE Engineering Group Ltd (FSEE) (Chinese: 豐盛機電工程集團有限公司) is an Electrical Engineering & Mechanical Engineering business company. It was established in 1997 when its predecessor, NWS Engineering Group Ltd, sold out to Fung Seng Enterprises. Now, FSE Engineering Group Ltd (FSEE) is the largest E&M Building Services engineering companies in Hong Kong

History
NWS Holdings announced on 11 June 2010 that the Group had entered into an agreement with Fung Seng Enterprises Limited to dispose of certain subsidiary companies (NWS Engineering Group Ltd) engaged in service businesses for a total consideration of HK$888.5 million.

It is operated mainly under the subsidiaries of Fung Seng Enterprises Limited (FSE).  FSE Engineering Group Ltd (FSEE), previously named NWS Engineering Group Ltd, mainly comprising Young's Engineering Company Limited, Majestic Engineering Company Limited and Far East Engineering Services Limited.

Services areas
FSE Engineering Group Ltd income is mostly from the projects in the government, public organizations and large private corporations.

It can provided Initial Consultation, Design & Value Engineering, Supply & Installation, Energy Audit, Testing & Commissioning, Operation & Maintenance, Facility Management etc. in HVAC, Fire Services, Plumbing & Drainage, Lighting, Power & ELV, Building Automation, Acoustic & Water Treatment and Clean Room engineering field.

This company encompass a wide range of building types and facilities including office, shopping mall, convention and exhibition center, bank, hotel, residential, university, hospital, recreational, airport, power plant, container and ferry terminal, industrial and environments

Projects
 Hong Kong Museum of Art
 Hong Kong Convention and Exhibition Centre Atrium Link Extension
 Hong Kong Convention and Exhibition Centre Extension (Phases I and II)
 Hong Kong Stadium Redevelopment
 Hong Kong Disneyland Resort - Back of House Facilities, Hollywood Hotel and Tomorrow land
 Hong Kong Electric Headquarters
 Hong Kong Institute of Biotechnology Complex
 Hong Kong International Airport - Cathay Pacific City, Sea Rescue Berth and Seawater Pumping Equipment
 Macau Grand Hyatt, City of Dreams, Macau
 Macau International Airport - Passenger Terminal Building
 Mandarin Oriental Macau - Hotel and Services Apartment
 Singapore Esplanade Mall
 Singapore Ritz Carlton Millenia
 Thailand All Seasons Place Phase 1, Bangkok
 Thailand Krisda Plaza Ph I, Bangkok
 Thailand SV City, Bangkok
 Vietnam New World Hotel Saigon, Ho Chi Minh City
 Vietnam Riverside Renaissance Hotel, Ho Chi Minh City
 Vietnam Thuan Kieu Plaza, Ho Chi Minh City

References
 

Engineering companies of Hong Kong
Mageia. Mageia is a Linux-based operating system, distributed as free and open-source software. It was forked from the Mandriva Linux distribution. The Greek term  () means enchantment, fascination, glamour, wizardry.

The first release of the software distribution, Mageia 1, took place in June 2011.

History
Mageia was created in 2010 as a fork of Mandriva Linux, by a group of former employees of Mandriva S.A. and several other members of the Mandriva community.

On September 2, 2010, Edge IT, one of the subsidiaries of Mandriva, was placed under liquidation process by the Tribunal de commerce in Paris; effective September 17, all assets were liquidated and employees were let go.

The next day, on September 18, 2010, some of these former employees, who were mostly responsible for the development and maintenance of the Mandriva Linux distribution, and several community members announced the creation of Mageia, with the support of many members of the community of developers, users and employees of Mandriva Linux.

Desktop environments
Mageia can use all major desktop environments. As was the case with Mandrake and Mandriva Linux, KDE is the main and the most used environment. End-users can choose from KDE and GNOME 64-bit live DVD editions, 32-bit and 64-bit Xfce live DVD editions, and any environment in the full DVD installation edition.

It uses Mageia Control Center. LXDE, LXQt, Cinammon, MATE and Enlightenment are also available.

Application repository
Mageia offers a very large repository of software, such as productivity applications and a large variety of games. It was the first Linux distribution in which MariaDB replaced Oracle's MySQL.

Development
Mageia was originally planned to be released on a nine-month release cycle, with each release to be supported for 18 months.

Actual practice has been to release a new version when the Mageia development community feels the new release is ready from quality and stability viewpoints. 

The latest stable version is Mageia 9, released on 27 August 2023.

Version history

See also
OpenMandriva Lx—a Linux distribution based on Mandriva Linux
PCLinuxOS—another Linux distribution now independent, but whose start was based on Mandriva Linux
Unity Linux—Mandriva-based distribution designed to be a base for end-user distributions

References

External links

Official wiki

KDE
Mandriva Linux
RPM-based Linux distributions
X86-64 Linux distributions
Linux distributions
Independent Linux distributions
2011 software
Bushcaddy R-120. The Bushcaddy R-120 is a Canadian kit aircraft produced by Canadian Light Aircraft Sales and Service (CLASS) of St. Lazare, Quebec and later Les Cedres, Quebec and now Bushcaddy of Lachute, Quebec and more recently Cornwall Regional Airport in Summerstown, Ontario.

The R-120 is a development of the Bushcaddy R-80 and is supplied as a kit for amateur construction.

Design and development
The aircraft was designed to comply with the Canadian  and United States amateur-built aircraft rules. It features a strut-braced high-wing, a two-seats-in-side-by-side configuration enclosed cockpit, fixed tricycle landing gear or conventional landing gear and a single engine in tractor configuration. The R-120 is structurally strengthened over the R-80 to allow a higher gross weight and accept larger engines.

The aircraft is made from 6061-T6 aluminum sheet over a cage of welded aluminum square 6061-T6 aluminum tube. The tail boom is conventional semi-monocoque construction. The non-tapered planform wings have 6061-T6 ribs and spars and employ a NACA 4413 (mod) airfoil. The airfoil modification removes the undercamber on the bottom of the wing, which makes construction easier, without giving up low speed performance. The aircraft's structure uses 2024-T3 aluminium for critical parts where extra strength is required, such as the spar, float and strut attachments as well as other critical components like the rudder horns. The R-120's structure is covered with 6061-T6 sheet of varying thicknesses. The wings are supported by conventional "V" struts. 6061-T6 is predominantly used for its lower cost and also its better corrosion resistance, since many R-120s are flown on floats. Its  span wing has an area of . Flaps are optional.

Standard engines used on the R-120 include the  Rotax 912UL, the  Rotax 912ULS, the turbocharged  Rotax 914, the  Continental O-200, the  Lycoming O-235, the  Jabiru 3300 and other four-stroke powerplants. The aircraft can also be mounted on floats and skis. Controls include a central "Y" control stick.

Construction time for the R-120 from the factory kit is 1,000 hours.

Variants

CLASS R-120 BushCaddy
Version produced by CLASS of Saint-Lazare, Quebec. Production was later moved to Les Cedres, Quebec.
Bushcaddy R-120
Current production version produced by Bushcaddy of Lachute, Quebec after buying the rights from CLASS in 2011.

Specifications (R-120)

References

External links

Official website

1990s Canadian ultralight aircraft
Homebuilt aircraft
Light-sport aircraft
Single-engined tractor aircraft
Multiverse Foundation. The Multiverse Software Foundation is a non-profit organization that was formed by volunteers in November 2011 to take over and manage the assets of the now-defunct Multiverse Network. The Foundation maintains the Multiverse MMO Development Platform, which is a collection of open-source software used to create online games. The platform and assets are made available under the MIT License.

Mission statement

The Mission of The Multiverse Software Foundation is to shepherd the open source Multiverse Virtual World and MMOG Platform.

This includes the technology behind the system, as well as the community of users and developers.
We aim to advance the knowledge, usage, and availability of free open source software and tools.

We do not limit how the Multiverse platform can be used. We encourage casual usage as well as usage by for-profit businesses. The Multiverse Software Foundation functions as a non profit entity.
We believe this is the best way to advance the future of virtual worlds and MMOG platforms.

Software Releases 

Since acquiring the software and media assets of the Multiverse Network, the Multiverse Software Foundation has released new versions of the client, tools, and server packages.

Technology 
Multiverse client technology is based on the Axiom 3D Rendering Engine which is a C# based fork of the OGRE rendering engine. The client can be scripted and customized in Python. The server technology is based on Java and may be customized and modified in either Java or Python. The database uses MySQL and JDBC. Assets in COLLADA and OGRE format may be imported.

Original Multiverse Network 
The original Multiverse Network was shut down following an inability to achieve a profitable business model. Several online and promotional games were planned or in development by Multiverse including games based on Firefly, Buffy the Vampire Slayer and James Cameron's Avatar. There were also independent developers using the original Multiverse engine.

External links
 The Multiverse Foundation Homepage (archived)
 Multiverse Platform project on Sourceforge
 Multiverse Wiki (archived)
 OGRE rendering engine
 Original Multiverse Homepage

References

Virtual reality organizations
Free game engines
Alternant hydrocarbon. An alternant hydrocarbon is any conjugated hydrocarbon system which does not possess an odd-membered ring. For such systems it is possible to undertake a starring process, in which the carbon atoms are divided into two sets: all the carbons in one set are marked with a star such that no two starred or unstarred atoms are bonded to each other. Here the starred set contains the highest number of atoms. When this condition is met, the secular determinant in the Hückel approximation has a simpler form, since cross-diagonal elements between atoms in the same set are necessarily 0.

Alternant hydrocarbons display three very interesting properties:
The molecular orbital energies for the π system are paired, that is for an orbital of energy  there is one of energy .
The coefficients of two paired molecular orbitals are the same at the same site, except for a sign change in the unstarred set.
The population or electron density at all sites is equal to unity in the ground state, so the distribution of π electrons is uniform across the whole molecule.

Moreover, if the alternant hydrocarbon contains an odd number of atoms then there must be an unpaired orbital with zero bonding energy (a non-bonding orbital). For this orbital, the coefficients on the atomic sites can be written down without calculation: the coefficient on all the orbitals belonging to the smaller (unstarred) set are 0, and the sum of the coefficients of the (starred) orbitals around them must also be 0. Simple algebra allows the assignment of all coefficients and then normalize them. This procedure permits the prediction of reactivity patterns and can be exploited to calculate Dewar's reactivity numbers for all sites.

References 

Theoretical chemistry
Molecular physics
Isolation condenser. In a reactor core isolation cooling system ("RCIC"), an isolation condenser (IC or iso. condenser; also  isolation condenser system) is one of the emergency reactor safety systems in some nuclear plants (boiling water reactor safety systems).

Emergency passive system
It is a passive system for cooling of some reactors (BWR/2, BWR/3 ..., and the (E)SBWR series) in nuclear production, located above containment in a pool of water open to atmosphere.

In operation, decay heat boils steam, which is drawn into the heat exchanger and condensed; then it falls by weight of gravity back into the reactor. This process keeps the cooling water in the reactor, making it unnecessary to use powered feedwater pumps. The water in the open pool slowly boils off, venting clean steam to the atmosphere. This makes it unnecessary to run mechanical systems to remove heat. Periodically, the pool must be refilled, a simple task for a fire truck. The (E)SBWR reactors provide three days' supply of water in the pool. Some older reactors also have IC systems, including Fukushima Dai-ichi reactor 1, however their water pools may not be as large.

Under normal conditions, the IC system is not activated, but the top of the IC condenser is connected to the reactor's steam lines through an open valve. Steam enters the IC condenser and condenses until it is filled with water. When the IC system is activated, a valve at the bottom of the IC condenser is opened which connects to a lower area on the reactor. The water falls to the reactor via gravity, allowing the condenser to fill with steam, which then condenses. This cycle runs continuously until the bottom valve is closed.

Problems

In case of electricity failure, the valves close automatically, and operators have to open them manually, which can be difficult in case an accident has already released radioactive steam inside the building.

During the accident at the Fukushima nuclear plant in 2011, the operators did not open the valve manually, and emergency system had been activated too late and could not work for long. Operators did not know if they should have left the valves open or not when the tanks of two condensers were emptied of their water cooling.

References

Bibliography 
  AEC,  Severe Accident Analyses of Fukushima-Daiichi Units 1

External links 
 Patent for isolation condenser

Light water reactors
Energy conversion
Nuclear power
Nuclear technology
Nuclear power stations
Power station technology
Nuclear safety and security
Nuclear power plant components