omniomni/omni-engineering huggingface dataset:
PEPA. Performance Evaluation Process Algebra (PEPA) is a stochastic process algebra designed for modelling computer and communication systems introduced by Jane Hillston in the 1990s. The language extends classical process algebras such as Milner's CCS and Hoare's CSP by introducing probabilistic branching and timing of transitions.

Rates are drawn from the exponential distribution and PEPA models are finite-state and so give rise to a stochastic process, specifically a continuous-time Markov process (CTMC).  Thus the language can be used to study quantitative properties of models of computer and communication systems such as throughput, utilisation and response time as well as qualitative properties such as freedom from deadlock.  The language is formally defined using a structured operational semantics in the style invented by Gordon Plotkin.

As with most process algebras, PEPA is a parsimonious language.  It has only four combinators, prefix, choice, co-operation and hiding.  Prefix is the basic building block of a sequential component: the process (a, r).P performs activity a at rate r before evolving to behave as component P.  Choice sets up a competition between two possible alternatives: in the process (a, r).P + (b, s).Q either a wins the race (and the process subsequently behaves as P) or b wins the race (and the process subsequently behaves as Q).

The co-operation operator requires the two "co-operands" to join for those activities which are specified in the co-operation set: in the process P < a, b> Q the processes P and Q must co-operate on activities a and b, but any other activities may be performed independently. The reversed compound agent theorem gives a set of sufficient conditions for a co-operation to have a product form stationary distribution.

Finally, the process P/{a} hides the activity a from view (and prevents other processes from joining with it).

Syntax

Given a set of action names, the set of PEPA processes is defined by the following BNF grammar:

The parts of the syntax are, in the order given above

 action  the process  can perform an action a at rate  and continue as the process P.
 choice  the process P+Q may behave as either the process P or the process Q.
 cooperation  processes P and Q exist simultaneously and behave independently for actions whose names do not appear in L. For actions whose names appear in L, the action must be carried out jointly and a race condition determines the time this takes.
 hiding  the process P behaves as usual for action names not in L, and performs a silent action  for action names that appear in L.
 process identifier  write  to use the identifier A to refer to the process P.

Tools
 PEPA Plug-in for Eclipse
 ipc: the imperial PEPA compiler
 GPAnalyser for fluid analysis of massively parallel systems

References

External links
 PEPA: Performance Evaluation Process Algebra 

Process calculi
Theoretical computer science
Handel (warning system). Handel was the code-name for the UK's national attack warning system in the Cold War. It consisted of a small console with two microphones, lights and gauges.

If an enemy airstrike was detected, a key on the left-hand side of the console would be turned and two lights would come on. Then the operator would press and hold down a red button and give the message:

The message would be sent to the police by the telephone system used for the speaking clock, who would in turn activate air attack sirens using the local telephone lines. The rationale was to tackle two problems at once; it reduced running costs (it would most likely be used only once in its working life, though it was regularly tested) and the telephone lines were continually tested for readiness by sharing infrastructure with a public service.  This meant a fault could be detected in time to give a warning.

A Handel warning console can be seen at the Imperial War Museum in London among their Cold War exhibits, alongside the warning apparatus used by Kent Police (which was located at Maidstone police station to activate the sirens).

See also
BIKINI state
Four-minute warning
National Emergency Alarm Repeater
Plectron

References

External links 
 An explanation of how the system worked

Cold War military equipment of the United Kingdom
Civil defense
Emergency management in the United Kingdom
United Kingdom nuclear command and control
Emergency population warning systems
Cold War military history of the United Kingdom
Color codes
Isaac Asimov's Robots and Aliens. Isaac Asimov's Robots and Aliens is a series of novels written by various authors and loosely connected to Isaac Asimov's Robot series.  Each volume is complete in itself, but they form a continuing series. The series  follows the action of the novels of the Isaac Asimov's Robot City series,  with the same protagonists Derec and Ariel, and many other characters.  The plot deals with the Three Laws and encounters between robots and different varieties of alien life.

 Changeling by Stephen Leigh (1989)
 Renegade by Cordell Scotten (1989)
 Intruder by Robert Thurston (1990)
 Alliance by Jerry Oltion (1990)
 Maverick by Bruce Bethke (1990)
 Humanity by Jerry Oltion (1990)

Timeline 
 The plot line continues, picking up several years after the Robot City/Robot and Aliens series, in "The Robot Mysteries" trilogy by Mark W. Tiedemann.
 The plot line continues on from Mark W. Tiedemann's trilogy in story "Have Robot, Will Travel" by Alexander C. Irvine.

References 

Science fiction book series
Derating. In electronics, derating is the operation of a device at less than its rated maximum capability to prolong its life. Typical examples include operations below the maximum power rating, current rating, or voltage rating.

In electronics

Power semiconductor devices have a maximum power dissipation rating usually quoted at a case temperature of . The datasheet for the device also includes a derating curve which indicates how much a device will dissipate without getting damaged at any given case temperature, and this must be taken into account while designing a system. 

As can be seen from the derating curve image for a hypothetical bipolar junction transistor, the device (rated for 100 W at ) cannot be expected to dissipate anything more than about 40 W if the ambient temperature is such that the temperature at which the device's case will stabilize (after  heat-sinking) is . This final case temperature is a function of the thermal resistance between the device's case and the heat-sink; and the heat-sink and the ambient (this includes the heat-sinks temp/watt rating - with lower values implying better cooling characteristics).

Some capacitors' voltage capability is reduced at higher temperatures because the softened dielectric (e.g., a polymer) is softened further by the heat, and its breakdown field strength is reduced. Derating curves are included in data sheets for such capacitors.

Derating can also provide a safety margin for transient voltages or currents (spikes) that exceed normal operation or prolong life. For example, the life of electrolytic capacitors is dramatically increased by operating them below their maximum temperature rating.

In electrical installations
All dimmers rely on heat conduction and convection to keep the electronic components cool. Similarly, power wiring (e.g., house wiring) not surrounded by an air space (e.g., inside a conduit) needs to have its current-limiting device (e.g., circuit breaker or fuse) adjusted so as not to carry as much current through that circuit. Derating is the reduction of the maximum capacity (load) a unit can reliably handle when fins/side sections are removed.

See also 

 Safe operating area
 Underclocking

References
 

Electrical engineering
List of aircraft carriers of Russia and the Soviet Union. The list of aircraft carriers of the Soviet Union and Russia includes all aircraft carriers built by, proposed for, or in service with the naval forces of either the Soviet Union or Russia. Although listed as aircraft carriers, none of them (with the exception of the never-built Ulyanovsk) is a "true" aircraft carrier (supercarrier). Specifically, they were all ASW helicopter carriers or aircraft cruisers, including the Admiral Kuznetsov, the only carrier still in service with the Russian Navy. Russia is currently considering building a supercarrier, code-named Project Shtorm.
All completed aircraft carriers of Soviet and Russian navy have been built by Ukrainian shipyards in city of Mykolaiv.

See also 
 Project 1153 Orel
 Project 23000 aircraft carrier
 List of aircraft carriers
 List of aircraft carriers in service
 List of aircraft carriers by country
 Timeline for aircraft carrier service
 List of aircraft carriers by configuration

References

External links
 Prospective aircraft carrier (In Russian)
 Aircraft Carriers
 INS Vikramaditya Aircraft Carrier

 
 
Russia
Aircraft carrier
Russian Naval Aviation
Aircraft carriers
Graphics device interface. A graphics device interface is a subsystem that most operating systems use for representing graphical objects and transmitting them to output devices such as monitors and printers. In most cases, the graphics device interface is only able to draw 2D graphics and simple 3D graphics, in order to make use of more advanced graphics and keep performance, an API such as DirectX or OpenGL needs to be installed.

In Microsoft Windows, the GDI functionality resides in gdi.exe on 16-bit Windows, and gdi32.dll on 32-bit Windows.

Operating system technology
Fuel element failure. A fuel element failure is a rupture in a nuclear reactor's fuel cladding that allows the nuclear fuel or fission products, either in the form of dissolved radioisotopes or hot particles, to enter the reactor coolant or storage water.

The de facto standard nuclear fuel is uranium dioxide or a mixed uranium/plutonium dioxide. This has a higher melting point than the actinide metals.  Uranium dioxide resists corrosion in water and provides a stable matrix for many of the fission products; however, to prevent fission products (such as the noble gases) from leaving the uranium dioxide matrix and entering the coolant, the pellets of fuel are normally encased in tubes of a corrosion-resistant metal alloy (normally Zircaloy for water-cooled reactors).

Those elements are then assembled into bundles to allow good handling and cooling.  As the fuel fissions, the radioactive fission products are also contained by the cladding, and the entire fuel element can then be disposed of as nuclear waste when the reactor is refueled.

If, however, the cladding is damaged, those fission products (which are not immobile in the uranium dioxide matrix) can enter the reactor coolant or storage water and can be carried out of the core, into the rest of the primary cooling circuit, increasing contamination levels there.

In the EU, some work has been done in which fuel is overheated in a special research reactor named PHEBUS. During these experiments the emissions of radioactivity from the fuel are measured and afterwards the fuel is subjected to Post Irradiation Examination to discover more about what happened to it.

References

Nuclear safety and security
Nuclear chemistry
Radioactive waste
Hardenability. Hardenability is the depth to which a steel is hardened after putting it through a heat treatment process. It should not be confused with hardness, which is a measure of a sample's resistance to indentation or scratching. It is an important property for welding, since it is inversely proportional to weldability, that is, the ease of welding a material.

Process 

When a hot steel work-piece is quenched, the area in contact with the water immediately cools and its temperature equilibrates with the quenching medium. The inner depths of the material however, do not cool so rapidly, and in work-pieces that are large, the cooling rate may be slow enough to allow the austenite to transform fully into a structure other than martensite or bainite. This results in a work-piece that does not have the same crystal structure throughout its entire depth; with a softer core and harder "shell".  The softer core is some combination of ferrite and cementite, such as pearlite.

The hardenability of ferrous alloys, i.e. steels, is a function of the carbon content and other alloying elements and the grain size of the austenite. The relative importance of the various alloying elements is calculated by finding the equivalent carbon content of the material.

The fluid used for quenching the material influences the cooling rate due to varying thermal conductivities and specific heats.  Substances like brine and water cool the steel much more quickly than oil or air.  If the fluid is agitated cooling occurs even more quickly.  The geometry of the part also affects the cooling rate: of two samples of equal volume, the one with higher surface area will cool faster.

Testing 

The hardenability of a ferrous alloy is measured by a Jominy test: a round metal bar of standard size (indicated in the top image) is transformed to 100% austenite through heat treatment, and is then quenched on one end with room-temperature water.  The cooling rate will be highest at the end being quenched, and will decrease as distance from the end increases. Subsequent to cooling a flat surface is ground on the test piece and the hardenability is then found by measuring the hardness along the bar. The farther away from the quenched end that the hardness extends, the higher the hardenability. This information is plotted on a hardenability graph.

The Jominy end-quench test was invented by Walter E. Jominy (1893-1976) and A.L. Boegehold, metallurgists in the Research Laboratories Division of General Motors Corp., in 1937.  For his pioneering work in heat treating, Jominy was recognized by the American Society for Metals (ASM) with its Albert Sauveur Achievement Award in 1944.  Jominy served as president of ASM in 1951.

References

External links 

 Description of hardenability and testing
 Hardenability vs. hardness
 Jominy test simulation
 More in-depth Jominy test information.
 Video of an imperfect test (YouTube)

Metallurgy
Vesuvianite. Vesuvianite, also known as idocrase, is a green, brown, yellow, or blue silicate mineral. Vesuvianite occurs as tetragonal crystals in skarn deposits and limestones that have been subjected to contact metamorphism.  It was first discovered within included blocks or adjacent to lavas on Mount Vesuvius, hence its name. Attractive-looking crystals are sometimes cut as gemstones. Localities which have yielded fine crystallized specimens include Mount Vesuvius and the Ala Valley near Turin, Piedmont.

The specific gravity is 3.4 and the Mohs hardness is . The name "vesuvianite" was given by Abraham Gottlob Werner in 1795, because fine crystals of the mineral are found at Vesuvius; these are brown in color and occur in the ejected limestone blocks of Monte Somma. Several other names were applied to this species, one of which, "idocrase" by René Just Haüy in 1796, is now in common use.

A sky bluish variety known as cyprine has been reported from Franklin, New Jersey and other locations; the blue is due to impurities of copper in a complex calcium aluminum sorosilicate.  Californite is a name sometimes used for jade-like vesuvianite, also known as California jade, American jade or Vesuvianite jade. Xanthite is a manganese rich variety. Wiluite is an optically positive variety from Wilui, Siberia. Idocrase is an older synonym sometimes used for gemstone-quality vesuvianite. Also, Vessonite and Vassolite are variant spellings commonly encountered in the gem trade.

References

Additional sources 
 
 Webmineral data
 Vesuvianite at Franklin-Sterling
 Mindat - Cyprine variants with location data

Calcium minerals
Magnesium minerals
Aluminium minerals
Mount Vesuvius
Gemstones
Geology of Italy
Sorosilicates
Tetragonal minerals
Minerals in space group 126
Ion beam-assisted deposition. Ion beam assisted deposition (IBAD or IAD) is a materials engineering technique which combines ion implantation with simultaneous sputtering or another physical vapor deposition technique.  Besides providing independent control of parameters such as ion energy, temperature and arrival rate of atomic species during deposition, this technique is especially useful to create a gradual transition between the substrate material and the deposited film, and for depositing films with less built-in strain than is possible by other techniques.  These two properties can result in films with a much more durable bond to the substrate. Experience has shown that some meta-stable compounds like cubic boron nitride (c-BN), can only be formed in thin films when bombarded with energetic ions during the deposition process.

See also
Ion beam deposition
Physical vapor deposition
Ion plating

References
 
 4wave Inc.'s Ion beam deposition page with diagram of a typical IBD system

Physical vapor deposition techniques
Thin film deposition
F89. F89 or F-89 may refer to:

 Aradu (F89), a 1980 Nigerian frigate
 DKW F89, a 1950 compact front wheel drive saloon
 F89 Minimi, an Australian produced version of the FN Minimi light machine gun
 F89 strain, a mupirocin-resistant strain of Staphylococcus aureus
 HMCS Prince David (F89), a 1929 Canadian National Steamships passenger liner
 Royal Navy pennant numbers:
 HMS Battleaxe (F89), a 1977 Type 22 frigate
 HMS Cardiff (F89), a Type 26 frigate
 Northrop F-89 Scorpion, an early American jet-powered fighter 
 Reynard F89 from Reynard Motorsport
 Volvo F89, heavy-duty truck from Volvo
Aleksei Isaev. Aleksei Mikhailovich Isaev (also Isayev; Russian: Алексе́й Миха́йлович Иса́ев; October 24, 1908, in Saint Petersburg – June 10, 1971, in Moscow) was a Soviet engineer in the Soviet space program, working on rocket combustion and propellant.

Aleksei Isaev began work under Leonid Dushkin during World War II, on an experimental rocket-powered interceptor plane, the BI-1.  In 1944 he formed his own design bureau to engineer liquid-propellant engines.  After abandoning the heavy, complex and undercooled German engine designs, Russia's principal engine designer Valentin Glushko turned to Isaev's innovations: thin-walled copper combustion chambers backed by steel support, anti-oscillation baffle to prevent chugging, and the flat injector plate with mixing-swirling injectors.  The latter was an enormous simplification of the "plumbing nightmare" of the V-2 engine, because it avoided the need for separate fuel lines to each sprayer. Staged combustion (Замкнутая схема) was first proposed by Alexey Isaev in 1949.

Although his inventions influenced the design of Glushko's large engines, Isaev was better known for building efficient small rockets.  He designed engines for the Soviet anti-missile and anti-aircraft rockets, and in 1951, his engine powered the R-11 Zemlya short-range missile, later named the Scud.  He designed a series of course-correction engines for Soviet planetary probes, including the KDU-414 used in Venera 1, Mars 1 up to Venera 8, the KTDU-425 used in later planetary probes, KTDU-5 used in the Soviet lunar landers Luna 4 to Luna 13.

Isaev was a corresponding member of the USSR Academy of Sciences.

A.M. Isayev Chemical Engineering Design Bureau is named after him.

The crater Isaev on the far side of the Moon is named after him.

References

External links
Site dedicated to articles about Isaev (in Russian)
Encyclopedia Astronautica Bio
International Space Hall of Fame entry

1908 births
1971 deaths
Soviet engineers
Soviet inventors
Rocket scientists
SAGA GIS. System for Automated Geoscientific Analyses (SAGA GIS) is a geographic information system (GIS) computer program, used to edit spatial data. It is free and open-source software, developed originally by a small team at the Department of Physical Geography, University of Göttingen, Germany, and is now being maintained and extended by an international developer community.

SAGA GIS is intended to give scientists an effective but easily learnable platform for implementing geoscientific methods. This is achieved by the application programming interface (API). SAGA has a fast-growing set of geoscientific methods, bundled in exchangeable module libraries.

The standard modules are:

 File access: interfaces to various table, vector, image and grid file formats, including shapefiles, Esri grids (ASCII and binary), and many grid file formats supported by the Geospatial Data Abstraction Library (GDAL), along with the native SGRD format of SAGA GIS.
 Filter for grids: Gaussian, Laplacian, multi-directional Lee filter.
 Gridding: interpolation from vector data using triangulation, nearest neighbour, inverse distance.
 Geostatistics: residual analysis, ordinary and universal kriging, single and multiple regression analysis, variance analysis.
 Grid calculator: combine grids through user defined functions.
 Grid discretisation: skeletonisation, segmentation.
 Grid tools: merging, resampling, gap filling.
 Image classification: cluster analysis, box classification, maximum likelihood, pattern recognition, region growing.
 Projections: various coordinate transformations for vector and grid data (using Proj4 and GeoTrans libraries), georeferencing of grids.
 Simulation of dynamic processes: TOPMODEL, nitrogen distributions, erosion, landscape development.
 Terrain analysis: geomorphometric calculations such as slope, aspect, curvatures, curvature classification, analytical hillshading, sink elimination, flow path analysis, catchment delineation, solar radiation, channel lines, relative altitudes.
 Vector tools: polygon intersection, contour lines from grid.

SAGA GIS is an effective tool with user friendly graphical user interface (GUI) that requires only about 10 MB disk space. No installation is needed, since SAGA GIS can be run directly from a USB thumb drive if desired.

SAGA GIS is available for Windows, Linux, and FreeBSD.

SAGA GIS can be used together with other GIS software like Kosmo and QGIS in order to obtain enhanced detail in vector datasets as well as higher-resolution map-production capabilities. SAGA GIS modules can be executed from within the statistical data analysis software R, in order to integrate statistical and GIS analyses.

References

 Böhner, J., McCloy, K.R., Strobl, J. [eds.] (2006):  SAGA - Analysis and Modelling Applications. Göttinger Geographische Abhandlungen, Vol.115, 130pp.
 Böhner, J., Blaschke, T., Montanarella, L. [eds.] (2008):  SAGA - Seconds Out. Hamburger Beiträge zur Physischen Geographie und Landschaftsökologie, Vol.19, 113pp.

External links

SAGA GIS Sourceforge project
SAGA GIS FreeBSD installation

Free GIS software
Free software programmed in C++
Software that uses wxWidgets